Computed neutron coincidence counting applied to passive waste assay
Energy Technology Data Exchange (ETDEWEB)
Bruggeman, M.; Baeten, P.; De Boeck, W.; Carchon, R. [Nuclear Research Centre, Mol (Belgium)
1997-11-01
Neutron coincidence counting applied for the passive assay of fissile material is generally realised with dedicated electronic circuits. This paper presents a software based neutron coincidence counting method with data acquisition via a commercial PC-based Time Interval Analyser (TIA). The TIA is used to measure and record all time intervals between successive pulses in the pulse train up to count-rates of 2 Mpulses/s. Software modules are then used to compute the coincidence count-rates and multiplicity related data. This computed neutron coincidence counting (CNCC) offers full access to all the time information contained in the pulse train. This paper will mainly concentrate on the application and advantages of CNCC for the non-destructive assay of waste. An advanced multiplicity selective Rossi-alpha method is presented and its implementation via CNCC demonstrated. 13 refs., 4 figs., 2 tabs.
Computed neutron coincidence counting applied to passive waste assay
International Nuclear Information System (INIS)
Bruggeman, M.; Baeten, P.; De Boeck, W.; Carchon, R.
1997-01-01
Neutron coincidence counting applied for the passive assay of fissile material is generally realised with dedicated electronic circuits. This paper presents a software based neutron coincidence counting method with data acquisition via a commercial PC-based Time Interval Analyser (TIA). The TIA is used to measure and record all time intervals between successive pulses in the pulse train up to count-rates of 2 Mpulses/s. Software modules are then used to compute the coincidence count-rates and multiplicity related data. This computed neutron coincidence counting (CNCC) offers full access to all the time information contained in the pulse train. This paper will mainly concentrate on the application and advantages of CNCC for the non-destructive assay of waste. An advanced multiplicity selective Rossi-alpha method is presented and its implementation via CNCC demonstrated. 13 refs., 4 figs., 2 tabs
A portable neutron coincidence counter
Energy Technology Data Exchange (ETDEWEB)
Peurrung, A.J.; Bowyer, S.M.; Craig, R.A.; Dudder, G.B.; Knopf, M.A.; Panisko, M.E.; Reeder, P.L.; Stromswold, D.C.; Sunberg, D.S.
1996-11-01
Pacific Northwest National Laboratory has designed and constructed a prototype portable neutron coincidence counter intended for use in a variety of applications, such as the verification and inspection of weapons components, safety measurements for novel and challenging situations, portable portal deployment to prevent the transportation of fissile materials, uranium enrichment measurements in hard-to-reach locations, waste assays for objects that cannot be measured by existing measurement systems, and decontamination and decommissioning. The counting system weighs less than 40 kg and is composed of parts each weighing no more than 5 kg. In addition, the counter`s design is sufficiently flexible to allow rapid, reliable assembly around containers of nearly arbitrary size and shape. The counter is able to discern the presence of 1 kg of weapons-grade plutonium within an ALR-8 (30-gal drum) in roughly 100 seconds and 10 g in roughly 1000 seconds. The counter`s electronics are also designed for maximum adaptability, allowing operation under a wide variety of circumstances, including exposure to gamma-ray fields of 1 R/h. This report provides a detailed review of the design and construction process. Finally, preliminary experimental measurements that confirm the performance capabilities of this counter are discussed. 6 refs., 18 figs., 3 tabs.
Statistical data filtration in neutron coincidence counting
International Nuclear Information System (INIS)
Beddingfield, D.H.; Menlove, H.O.
1992-11-01
We assessed the effectiveness of statistical data filtration to minimize the contribution of matrix materials in 200-ell drums to the nondestructive assay of plutonium. Those matrices were examined: polyethylene, concrete, aluminum, iron, cadmium, and lead. Statistical filtration of neutron coincidence data improved the low-end sensitivity of coincidence counters. Spurious data arising from electrical noise, matrix spallation, and geometric effects were smoothed in a predictable fashion by the statistical filter. The filter effectively lowers the minimum detectable mass limit that can be achieved for plutonium assay using passive neutron coincidence counting
Fast counting electronics for neutron coincidence counting
International Nuclear Information System (INIS)
Swansen, J.E.
1987-01-01
This patent describes a high speed circuit for accurate neutron coincidence counting comprising: neutron detecting means for providing an above-threshold signal upon neutron detection; amplifying means inputted by the neutron detecting means for providing a pulse output having a pulse width of about 0.5 microseconds upon the input of each above threshold signal; digital processing means inputted by the pulse output of the amplifying means for generating a pulse responsive to each input pulse from the amplifying means and having a pulse width of about 50 nanoseconds effective for processing an expected neutron event rate of about 1 Mpps: pulse stretching means inputted by the digital processing means for producing a pulse having a pulse width of several milliseconds for each pulse received form the digital processing means; visual indicating means inputted by the pulse stretching means for producing a visual output for each pulse received from the digital processing means; and derandomizing means effective to receive the 50 ns neutron event pulses from the digital processing means for storage at a rate up to the neutron event rate of 1 Mpps and having first counter means for storing the input neutron event pulses
Bourva, L C A
1999-01-01
The general purpose neutron-photon-electron Monte Carlo N-Particle code, MCNP sup T sup M , has been used to simulate the neutronic characteristics of the on-site laboratory passive neutron coincidence counter to be installed, under Euratom Safeguards Directorate supervision, at the Sellafield reprocessing plant in Cumbria, UK. This detector is part of a series of nondestructive assay instruments to be installed for the accurate determination of the plutonium content of nuclear materials. The present work focuses on one aspect of this task, namely, the accurate calculation of the coincidence gate utilisation factor. This parameter is an important term in the interpretative model used to analyse the passive neutron coincidence count data acquired using pulse train deconvolution electronics based on the shift register technique. It accounts for the limited proportion of neutrons detected within the time interval for which the electronics gate is open. The Monte Carlo code MCF, presented in this work, represents...
More accurate thermal neutron coincidence counting technique
International Nuclear Information System (INIS)
Baron, N.
1978-01-01
Using passive thermal neutron coincidence counting techniques, the accuracy of nondestructive assays of fertile material can be improved significantly using a two-ring detector. It was shown how the use of a function of the coincidence count rate ring-ratio can provide a detector response rate that is independent of variations in neutron detection efficiency caused by varying sample moderation. Furthermore, the correction for multiplication caused by SF- and (α,n)-neutrons is shown to be separable into the product of a function of the effective mass of 240 Pu (plutonium correction) and a function of the (α,n) reaction probability (matrix correction). The matrix correction is described by a function of the singles count rate ring-ratio. This correction factor is empirically observed to be identical for any combination of PuO 2 powder and matrix materials SiO 2 and MgO because of the similar relation of the (α,n)-Q value and (α,n)-reaction cross section among these matrix nuclei. However the matrix correction expression is expected to be different for matrix materials such as Na, Al, and/or Li. Nevertheless, it should be recognized that for comparison measurements among samples of similar matrix content, it is expected that some function of the singles count rate ring-ratio can be defined to account for variations in the matrix correction due to differences in the intimacy of mixture among the samples. Furthermore the magnitude of this singles count rate ring-ratio serves to identify the contaminant generating the (α,n)-neutrons. Such information is useful in process control
International Nuclear Information System (INIS)
Bourva, L.C.A.; Croft, S.
1999-01-01
The general purpose neutron-photon-electron Monte Carlo N-Particle code, MCNP TM , has been used to simulate the neutronic characteristics of the on-site laboratory passive neutron coincidence counter to be installed, under Euratom Safeguards Directorate supervision, at the Sellafield reprocessing plant in Cumbria, UK. This detector is part of a series of nondestructive assay instruments to be installed for the accurate determination of the plutonium content of nuclear materials. The present work focuses on one aspect of this task, namely, the accurate calculation of the coincidence gate utilisation factor. This parameter is an important term in the interpretative model used to analyse the passive neutron coincidence count data acquired using pulse train deconvolution electronics based on the shift register technique. It accounts for the limited proportion of neutrons detected within the time interval for which the electronics gate is open. The Monte Carlo code MCF, presented in this work, represents a new evaluation technique for the estimation of gate utilisation factors. It uses the die-away profile of a neutron coincidence chamber generated either by MCNP TM , or by other means, to simulate the neutron detection arrival time pattern originating from independent spontaneous fission events. A shift register simulation algorithm, embedded in the MCF code, then calculates the coincidence counts scored within the electronics gate. The gate utilisation factor is then deduced by dividing the coincidence counts obtained with that obtained in the same Monte Carlo run, but for an ideal detection system with a coincidence gate utilisation factor equal to unity. The MCF code has been benchmarked against analytical results calculated for both single and double exponential die-away profiles. These results are presented along with the development of the closed form algebraic expressions for the two cases. Results of this validity check showed very good agreement. On this
Neutron coincidence counting with digital signal processing
International Nuclear Information System (INIS)
Bagi, Janos; Dechamp, Luc; Dransart, Pascal; Dzbikowicz, Zdzislaw; Dufour, Jean-Luc; Holzleitner, Ludwig; Huszti, Joseph; Looman, Marc; Marin Ferrer, Montserrat; Lambert, Thierry; Peerani, Paolo; Rackham, Jamie; Swinhoe, Martyn; Tobin, Steve; Weber, Anne-Laure; Wilson, Mark
2009-01-01
Neutron coincidence counting is a widely adopted nondestructive assay (NDA) technique used in nuclear safeguards to measure the mass of nuclear material in samples. Nowadays, most neutron-counting systems are based on the original-shift-register technology, like the (ordinary or multiplicity) Shift-Register Analyser. The analogue signal from the He-3 tubes is processed by an amplifier/single channel analyser (SCA) producing a train of TTL pulses that are fed into an electronic unit that performs the time- correlation analysis. Following the suggestion of the main inspection authorities (IAEA, Euratom and the French Ministry of Industry), several research laboratories have started to study and develop prototypes of neutron-counting systems with PC-based processing. Collaboration in this field among JRC, IRSN and LANL has been established within the framework of the ESARDA-NDA working group. Joint testing campaigns have been performed in the JRC PERLA laboratory, using different equipment provided by the three partners. One area of development is the use of high-speed PCs and pulse acquisition electronics that provide a time stamp (LIST-Mode Acquisition) for every digital pulse. The time stamp data can be processed directly during acquisition or saved on a hard disk. The latter method has the advantage that measurement data can be analysed with different values for parameters like predelay and gate width, without repeating the acquisition. Other useful diagnostic information, such as die-away time and dead time, can also be extracted from this stored data. A second area is the development of 'virtual instruments.' These devices, in which the pulse-processing system can be embedded in the neutron counter itself and sends counting data to a PC, can give increased data-acquisition speeds. Either or both of these developments could give rise to the next generation of instrumentation for improved practical neutron-correlation measurements. The paper will describe the
Fast-neutron coincidence-counter manual
International Nuclear Information System (INIS)
Ensslin, N.; Atwell, T.L.; Lee, D.M.; Erkkila, B.; Marshall, R.S.; Morgan, A.; Shonrock, C.; Tippens, B.; Van Lyssel, T.
1982-03-01
The fast neutron counter (FNC) described in this report is a computer-based assay system employing fast-pulse counting instrumentation. It is installed below a glove box in the metal electrorefining area of the Los Alamos National Laboratory Plutonium Processing Facility. The instrument was designed to assay plutonium salts and residues from this process and to verify the mass of electrorefined metal. Los Alamos National Laboratory Groups Q-1, Q-3, and CMB-11 carried out a joint test and evaluation plan of this instrument between May 1978 and May 1979. The results of that evaluation, a description of the FNC, and operating instructions for further use are given in this report
Energy Technology Data Exchange (ETDEWEB)
Baeten, P.; Bruggeman, M.; Carchon, R
1998-06-01
The objective of this study was to investigate the influence of different important parameters on measurement results for various fork-detectors. Computed Neutron Coincidence Counting (CNCC) with Time Interval Analysis (TIA) was used for this study. The performance of the electronics for the different fork-detectors was studied by investigating the deadtime perturbed zone of the Rossi-alpha distribution in TIA. The measurement revealed anomalies in the performance of the electronics of the IAEA BWR and LANL fork-detector. The IAEA PWR fork-detector functioned well and the deadtime parameter was calculated. The optimal setting for the pre delay was investigated and it was found that a pre delay of 10 micro seconds should be considered as an optimum between excluding from analysis data in the deadtime perturbed zone and keeping a high signal-to-noise ratio. For the shift register electronics used with the fork-detectors, a pre delay of only 4.5 micro seconds was used. The study of the pre delay and the deadtime showed that the calculated triples-rate is strongly dependent on these parameters. An accurate determination of the triple-rate in this type of measurements has proven to be quite difficult and requires proper operation of the electronics, a correct pre delay and an accurate deadtime correction formalism. By varying the boron concentration in water, the change of the decay time of the Rossi-alpha distribution was clearly observed. This change is due to the variation of the thermal multiplication. The variation of this decay time with the boron concentration proves that Boehnel's model for fast neutron multiplication is not valid under these measurement conditions and that a model for fast and thermal multiplication should be used in order to obtain unbiased measurement results. CNCC with TIA has proved to be a valuable tool in which parameter settings can be varied a posterori and the optimal setting can be determined for each measurement. Moreover, the
International Nuclear Information System (INIS)
Baeten, P.; Bruggeman, M.; Carchon, R.
1998-06-01
The objective of this study was to investigate the influence of different important parameters on measurement results for various fork-detectors. Computed Neutron Coincidence Counting (CNCC) with Time Interval Analysis (TIA) was used for this study. The performance of the electronics for the different fork-detectors was studied by investigating the deadtime perturbed zone of the Rossi-alpha distribution in TIA. The measurement revealed anomalies in the performance of the electronics of the IAEA BWR and LANL fork-detector. The IAEA PWR fork-detector functioned well and the deadtime parameter was calculated. The optimal setting for the pre delay was investigated and it was found that a pre delay of 10 micro seconds should be considered as an optimum between excluding from analysis data in the deadtime perturbed zone and keeping a high signal-to-noise ratio. For the shift register electronics used with the fork-detectors, a pre delay of only 4.5 micro seconds was used. The study of the pre delay and the deadtime showed that the calculated triples-rate is strongly dependent on these parameters. An accurate determination of the triple-rate in this type of measurements has proven to be quite difficult and requires proper operation of the electronics, a correct pre delay and an accurate deadtime correction formalism. By varying the boron concentration in water, the change of the decay time of the Rossi-alpha distribution was clearly observed. This change is due to the variation of the thermal multiplication. The variation of this decay time with the boron concentration proves that Boehnel's model for fast neutron multiplication is not valid under these measurement conditions and that a model for fast and thermal multiplication should be used in order to obtain unbiased measurement results. CNCC with TIA has proved to be a valuable tool in which parameter settings can be varied a posterori and the optimal setting can be determined for each measurement. Moreover, the
The IAEA neutron coincidence counting (INCC) and the DEMING least-squares fitting programs
International Nuclear Information System (INIS)
Krick, M.S.; Harker, W.C.; Rinard, P.M.; Wenz, T.R.; Lewis, W.; Pham, P.; Ridder, P. de
1998-01-01
Two computer programs are described: (1) the INCC (IAEA or International Neutron Coincidence Counting) program and (2) the DEMING curve-fitting program. The INCC program is an IAEA version of the Los Alamos NCC (Neutron Coincidence Counting) code. The DEMING program is an upgrade of earlier Windows reg-sign and DOS codes with the same name. The versions described are INCC 3.00 and DEMING 1.11. The INCC and DEMING codes provide inspectors with the software support needed to perform calibration and verification measurements with all of the neutron coincidence counting systems used in IAEA inspections for the nondestructive assay of plutonium and uranium
Electronic neutron sensor based on coincidence detection
International Nuclear Information System (INIS)
Barelaud, B.; Decossas, J.L.; Mokhtari, F.; Vareille, J.C.
1996-01-01
The last symposium on neutron dosimetry which took place in Paris in November 1995 have shown again that it doesn't exist any individual active neutron dosemeter. The state of art on electronic device, the needs of the nuclear power industry in individual neutron monitoring and the new trends of The last symposium on neutron dosimetry which took place in Paris in November 1995 have shown again that it doesn't exist any individual active neutron dosemeter. The state of art on electronic device, the needs of the nuclear power industry in individual neutron monitoring and the new trends of researches were presented. They confirm the relevance of our studies in progress in the C2M team of the University of Limoges. The aim of this work is to realize an individual electronic neutron dosemeter. The device in the progress of being development will operate either as a dosemeter or as ratemeter giving H p (10) and H p (10) either as a spectrometer permitting to characterize the primary neutron beam. (author)
Measurement of plutonium oxalate in thermal neutron coincidence counters
International Nuclear Information System (INIS)
Marshall, R.S.; Erkkila, B.H.
1979-01-01
A coincidence neutron counting method has been developed for assaying batches of plutonium oxalate. Using counting data from two concentric rings of 3 He detectors, corrections are made for the effects that water has on the coincidence neutron count rate. Batches of plutonium oxalate varying from 750 to 1000 g of plutonium and from 34 to 54% water are assayed with an average accuracy of +-3%
Introduction to Neutron Coincidence Counter Design Based on Boron-10
Energy Technology Data Exchange (ETDEWEB)
Kouzes, Richard T.; Ely, James H.; Lintereur, Azaree T.; Siciliano, Edward R.
2012-01-22
The Department of Energy Office of Nonproliferation Policy (NA-241) is supporting the project 'Coincidence Counting With Boron-Based Alternative Neutron Detection Technology' at Pacific Northwest National Laboratory (PNNL) for development of an alternative neutron coincidence counter. The goal of this project is ultimately to design, build and demonstrate a boron-lined proportional tube based alternative system in the configuration of a coincidence counter. This report, providing background information for this project, is the deliverable under Task 1 of the project.
A training and educational tool for neutron coincidence measurements
International Nuclear Information System (INIS)
Huszti, J.; Bagi, J.; Langner, D.
2009-01-01
Neutron coincidence counting techniques are widely used for nuclear safeguards inspection. They are based on the detection of time correlated neutrons created from spontaneous or induced fission of plutonium and some other actinides. IAEA inspectors are trained to know and to use this technique, but it is not easy to illustrate and explain the basics of the neutron coincidence counting. The traditional shift registers or multiplicity counters give only multiplicity distributions and the singles, doubles and triples count rates. Using the list mode method for the recording and evaluation of neutron coincidence data makes it easier to teach this technique. List mode acquisition is a relatively new way to collect data in neutron coincidence counting. It is based on the recording of the follow-up times of neutron pulses originating from a neutron detector into a file. The recorded pulse train can be evaluated with special software after the measurement. Hardware and software for list mode neutron coincidence acquisition have been developed in the Institute of Isotopes and is called a Pulse Train Reader. A system called Virtual Source for replaying pulse trains registered with the list mode device has also been developed. The list mode device and the pulse train 're-player' together build a good educational tool for teaching the basics of neutron coincidence counting. Some features of the follow-up time, multiplicity and Rossi-alpha distributions can be well demonstrated by replaying artificially generated or pre-recorded pulse trains. The choice of real sources is stored on DVD. There is no need to transport and maintain real sources for the training. Virtual sources also give the possibility of investigating rare sources that trainees would not have access to otherwise. (authors)
Standardization of portable assay instrumentation: the neutron-coincidence tree
International Nuclear Information System (INIS)
Menlove, H.O.
1983-01-01
Standardization of portable neutron assay instrumentation has been achieved by using the neutron coincidence technique as a common basis for a wide range of instruments and applications. The electronics originally developed for the High-Level Neutron Coincidence Counter has been adapted to both passive- and active-assay instrumentation for field verification of bulk plutonium, inventory samples, pellets, powders, nitrates, high-enriched uranium, and materials-testing-reactor, light-water-reactor, and mixed-oxide fuel assemblies. The family of detectors developed at Los Alamos National Laboratory and their performance under in-field conditions are described. 16 figures, 3 tables
On neutron activation analysis with γγ coincidence spectrometry
International Nuclear Information System (INIS)
Zeisler, Rolf; Danyal Turkoglu; Ibere Souza Ribeiro Junior; Shetty, M.G.
2017-01-01
A new γγ coincidence system has been set up at NIST. It is operated with a digital data finder supported by new software developed at NIST. The system is used to explore possible enhancements in instrumental neutron activation analysis (INAA) and study applicability to neutron capture prompt gamma activation analysis (PGAA). The performance of the system is tested with certified reference materials for efficiency calibration and quantitative performance. Comparisons of INAA results based on conventional gamma-ray spectrometry data with INAA results based on coincidence data obtained from the same samples show improvements in the counting uncertainties and demonstrates the quantitative accuracy of the new system. (author)
Some target assay uncertainties for passive neutron coincidence counting
International Nuclear Information System (INIS)
Ensslin, N.; Langner, D.G.; Menlove, H.O.; Miller, M.C.; Russo, P.A.
1990-01-01
This paper provides some target assay uncertainties for passive neutron coincidence counting of plutonium metal, oxide, mixed oxide, and scrap and waste. The target values are based in part on past user experience and in part on the estimated results from new coincidence counting techniques that are under development. The paper summarizes assay error sources and the new coincidence techniques, and recommends the technique that is likely to yield the lowest assay uncertainty for a given material type. These target assay uncertainties are intended to be useful for NDA instrument selection and assay variance propagation studies for both new and existing facilities. 14 refs., 3 tabs
Preliminary results of a neutron-gamma coincidence experiment
International Nuclear Information System (INIS)
Piercey, R.B.; Dunnam, F.E.; Muga, M.L.; Rester, A.C.; Ramayya, A.V.; Hamilton, J.H.; Eberth, J.; Zganjar, E.F.
1984-01-01
The recently completed neutron multiplicity detector dubbed PANDA (Pentagonal Annular Neutron Detector Array) is fully described later in this report. The new detector was recently used for the first time on-line at the Holifield Heavy Ion Research Facility to measure neutron-gamma coincidence in the 24 Mg( 58 Ni,xαypzn) reaction. The detector configuration for the experiment is shown. The PANDA was situated in the forward direction, coaxial to the beam line with five gamma-ray detectors placed at +/- 90 0 , +/- 135 0 , and 0 0 . 2 figures
High-level neutron coincidence counter (HLNCC): users' manual
International Nuclear Information System (INIS)
Krick, M.S.; Menlove, H.O.
1979-06-01
This manual describes the portable High-Level Neutron Coincidence Counter (HLNCC) developed at the Los Alamos Scientific Laboratory (LASL) for the assay of plutonium, particularly by inspectors of the International Atomic Energy Agency (IAEA). The counter is designed for the measurement of the effective 240 Pu mass in plutonium samples which may have a high plutonium content. The following topics are discussed: principle of operation, description of the system, operating procedures, and applications
International Nuclear Information System (INIS)
Menlove, H.O.
1981-08-01
An active neutron interrogation method has been developed for the measurement of 235 U content in fresh fuel assemblies. The neutron Coincidence Collar uses neutron interrogation with an AmLi neutron source and coincidence counting the induced fission reaction neutrons from the 235 U. This manual describes the system components, operation, and performance characteristics. Applications of the Coincidence Collar to PWR and BWR types of reactor fuel assemblies are described
High-level neutron coincidence counter maintenance manual
International Nuclear Information System (INIS)
Swansen, J.; Collinsworth, P.
1983-05-01
High-level neutron coincidence counter operational (field) calibration and usage is well known. This manual makes explicit basic (shop) check-out, calibration, and testing of new units and is a guide for repair of failed in-service units. Operational criteria for the major electronic functions are detailed, as are adjustments and calibration procedures, and recurrent mechanical/electromechanical problems are addressed. Some system tests are included for quality assurance. Data on nonstandard large-scale integrated (circuit) components and a schematic set are also included
High-level neutron coincidence counter maintenance manual
Energy Technology Data Exchange (ETDEWEB)
Swansen, J.; Collinsworth, P.
1983-05-01
High-level neutron coincidence counter operational (field) calibration and usage is well known. This manual makes explicit basic (shop) check-out, calibration, and testing of new units and is a guide for repair of failed in-service units. Operational criteria for the major electronic functions are detailed, as are adjustments and calibration procedures, and recurrent mechanical/electromechanical problems are addressed. Some system tests are included for quality assurance. Data on nonstandard large-scale integrated (circuit) components and a schematic set are also included.
First principle active neutron coincidence counting measurements of uranium oxide
Energy Technology Data Exchange (ETDEWEB)
Goddard, Braden, E-mail: goddard.braden@gmail.com [Nuclear Security Science and Policy Institute, Texas A and M University, College Station, Texas 77843 (United States); Charlton, William [Nuclear Security Science and Policy Institute, Texas A and M University, College Station, Texas 77843 (United States); Peerani, Paolo [European Commission, EC-JRC-ITU, Ispra (Italy)
2014-03-01
Uranium is present in most nuclear fuel cycle facilities ranging from uranium mines, enrichment plants, fuel fabrication facilities, nuclear reactors, and reprocessing plants. The isotopic, chemical, and geometric composition of uranium can vary significantly between these facilities, depending on the application and type of facility. Examples of this variation are: enrichments varying from depleted (∼0.2 wt% {sup 235}U) to high enriched (>20 wt% {sup 235}U); compositions consisting of U{sub 3}O{sub 8}, UO{sub 2}, UF{sub 6}, metallic, and ceramic forms; geometries ranging from plates, cans, and rods; and masses which can range from a 500 kg fuel assembly down to a few grams fuel pellet. Since {sup 235}U is a fissile material, it is routinely safeguarded in these facilities. Current techniques for quantifying the {sup 235}U mass in a sample include neutron coincidence counting. One of the main disadvantages of this technique is that it requires a known standard of representative geometry and composition for calibration, which opens up a pathway for potential erroneous declarations by the State and reduces the effectiveness of safeguards. In order to address this weakness, the authors have developed a neutron coincidence counting technique which uses the first principle point-model developed by Boehnel instead of the “known standard” method. This technique was primarily tested through simulations of 1000 g U{sub 3}O{sub 8} samples using the Monte Carlo N-Particle eXtended (MCNPX) code. The results of these simulations showed good agreement between the simulated and exact {sup 235}U sample masses.
International Nuclear Information System (INIS)
Zhang Songbai; Wu Jun; Zhu Jianyu; Tian Dongfeng; Xie Dong
2011-01-01
The active methodology of time correlation coincidence measurement of neutron is an effective verification means to authenticate uranium metal. A collimated 252 Cf neutron source was used to investigate mass and enrichment of uranium metal through the neutron transport simulation for different enrichments and different masses of uranium metal, then time correlation coincidence counts of them were obtained. By analyzing the characteristic of time correlation coincidence counts, the monotone relationships were founded between FWTH of time correlation coincidence and multiplication factor, between the total coincidence counts in FWTH for time correlation coincidence and mass of 235 U multiplied by multiplication factor, and between the ratio of neutron source penetration and mass of uranium metal. Thus the methodology to authenticate mass and enrichment of uranium metal was established with time correlation coincidence by active neutron investigation. (authors)
Sustaining IAEA Neutron Coincidence Counting: Past, Present and Future
International Nuclear Information System (INIS)
Longo, J.; Schaffer, K.M.; Nordquist, H.
2015-01-01
Los Alamos National Laboratory's IAEA Neutron Coincidence Counting (INCC) code is the standard tool for neutron coincidence counting measurements. INCC software and its' predecessors were originally implemented in the 1970s. The measurement and analysis techniques perfected in the code arise from many years of laboratory and field experience by nuclear engineers and physicists. Covering the full arc of INCC's lifecycle, we discuss the engineering approaches used for conception, original development, worldwide deployment of the stand-alone Windows application, more than a decade of sustained maintenance support, and our recent work to carry INCC successfully into future applications. We delve into the recent re-architecture of the INCC code base, an effort to create a maintainable and extensible architecture designed to preserve the existing INCC code base while adding support for new analyzes and instruments (e.g., List Mode PTR-32 and the List Mode Multiplicity Module). INCC now consists of separate modules implementing attended instrumentation control, data file processing, statistical and Pu mass calculation and analyzes, list mode counting and analyzes, reporting functions, and a database support library. Separating functional capabilities in this architecture enables better testing, isolates development risk and enables the use of INCC features in other software systems. We discuss our approach to handling divergent data and protocol support as a result of this re-architecture. INCC has complex testing requirements; we show how the testing effort was reduced by breaking the software into separate modules. This new architecture enables integration of INCC analysis into the IAEA's new Integrated Review and Analysis Programme (iRAP) data review system. iRAP is based on the respected Euratom Comprehensive Review Inspector Software Package (CRISP) software framework, and is expected to be the future data review system for IAEA and Euratom
The optimum choice of gate width for neutron coincidence counting
Energy Technology Data Exchange (ETDEWEB)
Croft, S., E-mail: crofts@ornl.gov [Safeguards and Security Technology (SST), Global Nuclear Security Technology Divisions, PO Box 2008, Building 5700, MS-6166, Oak Ridge, TN 37831-6166 (United States); Henzlova, D.; Favalli, A.; Hauck, D.K.; Santi, P.A. [Safeguards Science and Technology Group (NEN-1), Nuclear Engineering and Nonproliferation Division, MS-E540, Los Alamos, NM 87545 (United States)
2014-11-11
In the measurement field of international nuclear safeguards, passive neutron coincidence counting is used to quantify the spontaneous fission rate of certain special nuclear materials. The shift register autocorrelation analysis method is the most commonly used approach. However, the Feynman-Y technique, which is more commonly applied in reactor noise analysis, provides an alternative means to extract the correlation information from a pulse train. In this work we consider how to select the optimum gate width for each of these two time-correlation analysis techniques. The optimum is considered to be that which gives the lowest fractional precision on the net doublets rate. Our theoretical approach is approximate but is instructional in terms of revealing the key functional dependence. We show that in both cases the same performance figure of merit applies so that common design criteria apply to the neutron detector head. Our prediction is that near optimal results, suitable for most practical applications, can be obtained from both techniques using a common gate width setting. The estimated precision is also comparable in the two cases. The theoretical expressions are tested experimentally using {sup 252}Cf spontaneous fission sources measured in two thermal well counters representative of the type in common use by international inspectorates. Fast accidental sampling was the favored method of acquiring the Feynman-Y data. Our experimental study confirmed the basic functional dependences predicted although experimental results when available are preferred. With an appropriate gate setting Feynman-Y analysis provides an alternative to shift register analysis for safeguards applications which is opening up new avenues of data collection and data reduction to explore.
The neutron computer tomography
International Nuclear Information System (INIS)
Matsumoto, G.; Krata, S.
1983-01-01
The method of computer tomography (CT) was applied for neutrons instead of X-rays. The neutron radiography image of samples was scanned by microphotometer to get the transmission data. This process was so time-consuming that the number of incident angles to samples could not be increased. The transmission data was processed by FACOM computer and CT image was gained. In the experiment at the Japan Research Reactor No. 4 at Tokai-mura with 18 projection angles, the resolution of paraffin in the aluminum block was less than 0.8 mm. In the experiment at Van de Graaf accelerator of Nagoya University, this same resolution was 1.2 mm because of the angle distribution of neutron beam. This experiment is the preliminary one, the facility which utilizes neutron television and video-recorder will be necessary for the next stage. (Auth.)
Neutron coincidence counter for MOX fuel pins in storage trays: users' manual
International Nuclear Information System (INIS)
Cowder, L.; Menlove, H.
1982-08-01
The neutron coincidence counter for measurement of mixed-oxide fuel pins in storage trays is described. The special detector head has been designed so that the detectors, high-voltage junction boxes, and electronics are interchangeable with those of the high-level neutron coincidence counter system. This manual describes the system components and the operation and maintenance of the counter. The counter was developed at Los Alamos National Laboratory for in-plant inspection applications by the International Atomic Energy Agency
High sensitivity neutron activation analysis using coincidence counting method
International Nuclear Information System (INIS)
Suzuki, Shogo; Okada, Yukiko; Hirai, Shoji
1999-01-01
Four kinds of standard samples such as river sediment (NIES CRM No.16), Typical Japanese Diet, otoliths and river water were irradiated by TRIGA-II (100 kW, 3.7x10 12 n cm -2 s -1 ) for 6 h. After irradiation and cooling, they were analyzed by the coincidence counting method and a conventional γ-ray spectrometry. Se, Ba and Hf were determined by 75 Se 265 keV, 131 Ba 496 keV and 181 Hf 482 keV. On the river sediment sample, Ba and Hf showed the same values by two methods, but Se value contained Ta by the conventional method, although the coincidence counting method could analyze Se. On Typical Japanese Diet and otoliths, Se could be determined by two methods and Ba and Hf determined by the coincidence counting method but not determined by the conventional method. Se value in the river water agreed with the authorization value. (S.Y.)
Determination of U-235 quantity in fresh fuel elements by neutron coincidence collar technique
International Nuclear Information System (INIS)
Almeida, M.C.M. de; Almeida, S.G. de; Marzo, M.A.S.; Moita, L.P.M.
1990-01-01
The U-235 quantity per lenght of fresh fuel assemblies of the Angra-I first recharge was determined by Neutron Coincidence Collar technique (N.C.C.). This technique is well-founded in fresh fuel assemblies activation by thermal neutrons from AmLi source to generate U-235 fission neutrons. These neutrons are detected by coincidence method in polyethylene structure where 18 He-3 detectors were placed. The coincidence counting results, in active mode (AmLi), showed 0,7% to standard deviation and equal to 1,49% to mass in 1000s of counting. The accuracies of different calibration methods were evaluated and compared. The results showed that the operator declared values are consistent. This evaluation was part of technical-exchange program between Safeguards Laboratory from C.N.E.N. and Los Alamos National Lab., United States. (author)
International Nuclear Information System (INIS)
Gamage, Kelum A.A.; Joyce, Malcolm J.; Cave, Frank D.
2013-06-01
Neutron coincidence counting is an established, nondestructive method for the qualitative and quantitative analysis of nuclear materials. Several even-numbered nuclei of the actinide isotopes, and especially even-numbered plutonium isotopes, undergo spontaneous fission, resulting in the emission of neutrons which are correlated in time. The characteristics of this i.e. the multiplicity can be used to identify each isotope in question. Similarly, the corresponding characteristics of isotopes that are susceptible to stimulated fission are somewhat isotope-related, and also dependent on the energy of the incident neutron that stimulates the fission event, and this can hence be used to identify and quantify isotopes also. Most of the neutron coincidence counters currently used are based on 3 He gas tubes. In the 3 He-filled gas proportional-counter, the (n, p) reaction is largely responsible for the detection of slow neutrons and hence neutrons have to be slowed down to thermal energies. As a result, moderator and shielding materials are essential components of many systems designed to assess quantities of fissile materials. The use of a moderator, however, extends the die-away time of the detector necessitating a larger coincidence window and, further, 3 He is now in short supply and expensive. In this paper, a simulation based on the Monte Carlo method is described which has been performed using MCNPX 2.6.0, to model the geometry of a sector-shaped liquid scintillation detector in response to coincident neutron events. The detection of neutrons from a mixed-oxide (MOX) fuel pellet using an organic liquid scintillator has been simulated for different thicknesses of scintillators. In this new neutron detector, a layer of lead has been used to reduce the gamma-ray fluence reaching the scintillator. The effect of lead for neutron detection has also been estimated by considering different thicknesses of lead layers. (authors)
A high-efficiency neutron coincidence counter for small samples
International Nuclear Information System (INIS)
Miller, M.C.; Menlove, H.O.; Russo, P.A.
1991-01-01
The inventory sample coincidence counter (INVS) has been modified to enhance its performance. The new design is suitable for use with a glove box sample-well (in-line application) as well as for use in the standard at-line mode. The counter has been redesigned to count more efficiently and be less sensitive to variations in sample position. These factors lead to a higher degree of precision and accuracy in a given counting period and allow for the practical use of the INVS counter with gamma-ray isotopics to obtain a plutonium assay independent of operator declarations and time-consuming chemicals analysis. A calculation study was performed using the Los Alamos transport code MCNP to optimize the design parameters. 5 refs., 7 figs., 8 tabs
Boron-Coated Straw Collar for Uranium Neutron Coincidence Collar Replacement
International Nuclear Information System (INIS)
Hu, Jianwei; Croft, Stephen; McElroy, Robert Dennis
2017-01-01
The objective of this project was to design and optimize, in simulation space, an active neutron coincidence counter (or collar) using boron-coated straws (BCSs) as a non- 3 He replacement to the Uranium Neutron Coincidence Collar (UNCL). UNCL has been used by the International Atomic Energy Agency (IAEA) and European Atomic Energy Community (Euratom) since the 1980s to verify the 235 U content in fresh light water reactor fuel assemblies for safeguards purposes. This report documents the design and optimization of the BCS collar.
Boron-Coated Straw Collar for Uranium Neutron Coincidence Collar Replacement
Energy Technology Data Exchange (ETDEWEB)
Hu, Jianwei [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Croft, Stephen [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); McElroy, Robert Dennis [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
2017-01-01
The objective of this project was to design and optimize, in simulation space, an active neutron coincidence counter (or collar) using boron-coated straws (BCSs) as a non-^{3}He replacement to the Uranium Neutron Coincidence Collar (UNCL). UNCL has been used by the International Atomic Energy Agency (IAEA) and European Atomic Energy Community (Euratom) since the 1980s to verify the ^{235}U content in fresh light water reactor fuel assemblies for safeguards purposes. This report documents the design and optimization of the BCS collar.
Determination of plutonium in nuclear fuels using the neutron coincidence method
International Nuclear Information System (INIS)
Boehnel, K.
1978-03-01
In assays for plutonium the neutron coincidence technique is often used. This method which is based on measuring spontaneous fission rates is examined both experimentally and theoretically. A novel coincidence unit is described which works in effect without deadtime and which therefore has advantages over the currently used design. For waste samples a principle for measurement is described which avoids space dependence effects by rotating the probe in an asymmetric detector. Formulae are developed for the statistical error and various effects of deadtimes are discussed. Further it is shown that neutron multiplication in the sample is an important source of errors, especially when the (α, n)-background is neglected. (author)
Energy Technology Data Exchange (ETDEWEB)
Mueller, J.M., E-mail: jonathan_mueller@ncsu.edu; Mattingly, J.
2016-07-21
There is a significant and well-known anisotropy between the prompt neutrons emitted from a single fission event; these neutrons are most likely to be observed at angles near 0° or 180° relative to each other. However, the propagation of this anisotropy through different generations of a fission chain reaction has not been previously studied. We have measured this anisotropy in neutron–neutron coincidences from a subcritical highly-multiplying assembly of plutonium metal. The assembly was a 4.5 kg α-phase plutonium metal sphere composed of 94% {sup 239}Pu and 6% {sup 240}Pu by mass. Data were collected using two EJ-309 liquid scintillators and two EJ-299 plastic scintillators. The angular distribution of neutron–neutron coincidences was measured at 90° and 180° and found to be largely isotropic. Simulations were performed using MCNPX-PoliMi of similar plutonium metal spheres of varying sizes and a correlation between the neutron multiplication of the assembly and the anisotropy of neutron–neutron coincidences was observed. In principle, this correlation could be used to assess the neutron multiplication of an unknown assembly.
International Nuclear Information System (INIS)
Langner, D.G.; Russo, P.A.; Wachter, J.R.
1993-01-01
Americium is extracted from plutonium by a molten salt extraction (MSE) process. The residual americium-laden salts are a significant waste stream in this pyrochemical purification process. Rapid assay of MSE residues is desirable to minimize the exposure of personnel to these often high-level emissions. However, the quantitative assay of plutonium in MSE residues is difficult. Variable, unknown (a,n) rates and variable emitted-neutron energy spectra preclude the use of standard neutron coincidence counting techniques with old-generation neutron coincidence counters. Gamma-ray assay methods have not been successful with some residues because of random lumps of plutonium metal. In this paper, we present measurements of MSE residues with two state-of-the-art neutron coincidence counters at the Los Alamos Plutonium Processing Facility: an in-line counter built for the assay of bulk waste material and the pyrochemical multiplicity counter that underwent test and evaluation at that facility. Both of these counters were designed to minimize the effects on measurements of variations in the sample geometry and variable energy spectra of emitted neutrons. These results are compared to measurements made with an HLNCII and with a 20-yr-old in-line well counter. The latter two counters are not optimized in ft sense. We conclude that the newer counters provide significantly improved assay results. The pyrochemical multiplicity counter operated in the conventional coincidence mode provided the best assays overall
Field test and calibration of neutron coincidence counters for high-mass plutonium samples
International Nuclear Information System (INIS)
Menlove, H.O.; Dickinson, R.J.; Douglas, I.
1987-02-01
Five different neutron coincidence systems were evaluated and calibrated for high-mass PuO 2 samples. The samples were from 2 to 7.2 kg of PuO 2 in mass, with a large range of burnup. This report compares the equipment and the results, with an evaluation of deadtime and multiplication corrections
Energy Technology Data Exchange (ETDEWEB)
Deyglun, C.; Simony, B.; Perot, B.; Carasco, C. [CEA, DEN, Cadarache, Nuclear Measurement Laboratory, F-13108 Saint-Paul-lez-Durance (France); Saurel, N.; Colas, S. [CEA, DAM, Valduc, F-21120 Is-sur-Tille (France); Collot, J. [Laboratoire de Physique Subatomique et de Cosmologie, Universite Grenoble Alpes, CNRS/IN2P3, Grenoble (France)
2015-07-01
The quantification of radioactive material is essential in the fields of safeguards, criticality control of nuclear processes, dismantling of nuclear facilities and components, or radioactive waste characterization. The Nuclear Measurement Laboratory (LMN) of CEA is involved in the development of time-correlated neutron detection techniques using plastic scintillators. Usually, 3He proportional counters are used for passive neutron coincidence counting owing to their high thermal neutron capture efficiency and gamma insensitivity. However, the global {sup 3}He shortage in the past few years has made these detectors extremely expensive. In addition, contrary to {sup 3}He counters for which a few tens of microseconds are needed to thermalize fast neutrons, in view to maximize the {sup 3}He(n,p){sup 3}H capture cross section, plastic scintillators are based on elastic scattering and therefore the light signal is formed within a few nanoseconds, correlated pulses being detected within a few dozen- or hundred nanoseconds. This time span reflects fission particles time of flight, which allows reducing accordingly the duration of the coincidence gate and thus the rate of random coincidences, which may totally blind fission coincidences when using {sup 3}He counters in case of a high (α,n) reaction rate. However, plastic scintillators are very sensitive to gamma rays, requiring the use of a thick metallic shield to reduce the corresponding background. Cross talk between detectors is also a major issue, which consists on the detection of one particle by several detectors due to elastic or inelastic scattering, leading to true but undesired coincidences. Data analysis algorithms are tested to minimize cross-talk in simultaneously activated detectors. The distinction between useful fission coincidences and the correlated background due to cross-talk, (α,n) and induced (n,2n) or (n,n'γ) reactions, is achieved by measuring 3-fold coincidences. The performances of a
Moisture corrections in neutron coincidence counting of PuO2
International Nuclear Information System (INIS)
Stewart, J.E.; Menlove, H.O.
1987-01-01
Passive neutron coincidence counting is capable of 1% assay accuracy for pure, well-characterized PuO 2 samples that contain plutonium masses from a few tens of grams to several kilograms. Moisture in the sample can significantly bias the assay high by changing the (α,n) neutron production, the sample multiplication, and the detection efficiency. Monte Carlo calculations and an analytical model of coincidence counting have been used to quantify the individual and cumulative effects of moisture biases for two PuO 2 sample sizes and a range of moisture levels from 0 to 9 wt %. Results of the calculations suggest a simple correction procedure for moisture bias that is effective from 0 to 3 wt % H 2 O. The procedure requires that the moisture level in the sample be known before the coincidence measurement
Simulations of Lithium-Based Neutron Coincidence Counter for Gd-Loaded Fuel
Energy Technology Data Exchange (ETDEWEB)
Cowles, Christian C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Kouzes, Richard T. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Siciliano, Edward R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
2014-10-01
The Department of Energy Office of Nuclear Safeguards and Security (NA-241) is supporting the project Lithium-Based Alternative Neutron Detection Technology Coincidence Counting for Gd-loaded Fuels at Pacific Northwest National Laboratory for the development of a lithium-based neutron coincidence counter for nondestructively assaying Gd loaded nuclear fuel. This report provides results from MCNP simulations of a lithium-based coincidence counter for the possible measurement of Gd-loaded nuclear fuel. A comparison of lithium-based simulations and UNCL-II simulations with and without Gd loaded fuel is provided. A lithium-based model, referred to as PLNS3A-R1, showed strong promise for assaying Gd loaded fuel.
Uranium mass and neutron multiplication factor estimates from time-correlation coincidence counts
Energy Technology Data Exchange (ETDEWEB)
Xie, Wenxiong [China Academy of Engineering Physics, Center for Strategic Studies, Beijing 100088 (China); Li, Jiansheng [China Academy of Engineering Physics, Institute of Nuclear Physics and Chemistry, Mianyang 621900 (China); Zhu, Jianyu [China Academy of Engineering Physics, Center for Strategic Studies, Beijing 100088 (China)
2015-10-11
Time-correlation coincidence counts of neutrons are an important means to measure attributes of nuclear material. The main deficiency in the analysis is that an attribute of an unknown component can only be assessed by comparing it with similar known components. There is a lack of a universal method of measurement suitable for the different attributes of the components. This paper presents a new method that uses universal relations to estimate the mass and neutron multiplication factor of any uranium component with known enrichment. Based on numerical simulations and analyses of 64 highly enriched uranium components with different thicknesses and average radii, the relations between mass, multiplication and coincidence spectral features have been obtained by linear regression analysis. To examine the validity of the method in estimating the mass of uranium components with different sizes, shapes, enrichment, and shielding, the features of time-correlation coincidence-count spectra for other objects with similar attributes are simulated. Most of the masses and multiplications for these objects could also be derived by the formulation. Experimental measurements of highly enriched uranium castings have also been used to verify the formulation. The results show that for a well-designed time-dependent coincidence-count measuring system of a uranium attribute, there are a set of relations dependent on the uranium enrichment by which the mass and multiplication of the measured uranium components of any shape and size can be estimated from the features of the source-detector coincidence-count spectrum.
Fluorescent atom coincidence spectroscopy of extremely neutron-deficient barium isotopes
International Nuclear Information System (INIS)
Wells, S.A.; Evans, D.E.; Griffith, J.A.R.; Eastham, D.A.; Groves, J.; Smith, J.R.H.; Tolfree, D.W.L.; Warner, D.D.; Billowes, J.; Grant, I.S.; Walker, P.M.
1988-01-01
Fluorescent atom coincidence spectroscopy (FACS) has been used to measure the nuclear mean square radii and moments of the extremely neutron-deficient isotopes 120-124 Ba. At N=65 an abrupt change in nuclear mean square charge radii is observed which can be understood in terms of the occupation of the spin-orbit partner g 7/2 5/2[413] neutron and g 9/2 9/2[404] proton orbitals and the consequent enhancement of the n-p interaction. (orig.)
International Nuclear Information System (INIS)
Lee, S.Y.; Li, T.K.; Menlove, Howard O.; Kim, H.D.; Ko, W.I.; Park, S.W.
2005-01-01
The Advanced Spent Fuel Conditioning Process (ACP) is a pyrochemical dry reprocessing technique to convert oxide-type spent nuclear fuel into a metallic form. The Korea Atomic Energy Research Institute (KAERI) has been developing this technology for the purpose of spent fuel management and is planning to perform a lab-scale demonstration in 2006. With this technology, a significant reduction of the volume and heat load of spent fuel is expected, which could decrease the burden of safety and economics. In this study, MCNPX code calculations were carried out to estimate the performance of a neutron coincidence counter designed for measruement of the process materials in the pilot-scale ACP facility. To verify the design requirement, the singles and doubles counting rates of the detectors were simulated with the latest coincidence capability of the MCNPX code. Then, the precision of the coincidence measurements were evaluated on various process materials from the ACP. It was verified that the performance of the neutron coincidence counter could meet the design criteria for all samples in the ACP, and the material accounting system for the pilot-scale ACP facility could meet the IAEA safeguards goals.
Development of Coincidence Method for Determination Thermal Neutron Flux on RSG-GAS
International Nuclear Information System (INIS)
Bakhri, Syaiful; Hamzah, Amir
2004-01-01
The research to develop detection radiation system using coincidence method has been done to determine thermal neutron flux in RS1 and RS2 irradiation facilities RSG-GAS. At this research has arranged beta-gamma coincidence equipment system and parameter of measurement according to Au-198 beta-gamma spectrum. Gold foils that have irradiated for period of time, counted, and the activities of radiation is analyzed to get neutron flux. Result of research indicate that systems measurement of absolute activity with gamma beta coincidence method functioning well and can be applied at activity measurement of gold foil for irradiation facility characterization. The results show that thermal neutron flux in RS1 and RS2, respectively is 2.007E+12 n/cm 2 s and 2.147E+12 n/cm 2 s. To examine the system performance, the result was compared to measure activity using high resolution of Hp Ge detector and achieved discrepancy is about 1.26% and 6.70%. (author)
International Nuclear Information System (INIS)
Smith, B.G.R.; Outram, J.D.; Storey, M.
1991-01-01
A commercial Data Logger for unattended passive neutron coincidence data acquisition is described. This consists of an inexpensive commercial Data Logging equipment attached to a neutron coincidence electronics and a software package for data review. The Data Logger permits both the flexible configuration of a passive neutron coincidence measurement system for unattended mode monitoring and the storage of the measured Totals and Reals count rates. An additional feature of the Data Logger is a custom software package providing for the complete analysis of the stored data and yielding an assay of each item passing through the measurement cavity. The analysis includes an input for different isotopic compositions, the calculation of the multiplication corrected Reals rates, the inclusion of a calibration functions, and the determination of 240 Pu masses. The software package for data review displays the Totals and Reals count rates logged by the Data Logger as a function of time. In addition the custom software provides input files to the data review package to display the multiplication corrected Reals count rates and the measured 240 Pu masses as a function of time. Information on the Data Logger is presented along with the monitoring mode specifications. The analysis functions implemented are described as is the data review software. Results are presented for a specific application
Note: Coincidence measurements of 3He and neutrons from a compact D-D neutron generator
Ji, Q.; Lin, C.-J.; Tindall, C.; Garcia-Sciveres, M.; Schenkel, T.; Ludewigt, B. A.
2017-05-01
Tagging of neutrons (2.45 MeV) with their associated 3He particles from deuterium-deuterium (D-D) fusion reactions has been demonstrated in a compact neutron generator setup enabled by a high brightness, microwave-driven ion source with a high fraction of deuterons. Energy spectra with well separated peaks of the D-D fusion reaction products, 3He, tritons, and protons, were measured with a silicon PIN diode. The neutrons were detected using a liquid scintillator detector with pulse shape discrimination. By correlating the 3He detection events with the neutron detection in time, we demonstrated the tagging of emitted neutrons with 3He particles detected with a Si PIN diode detector mounted inside the neutron generator vacuum vessel.
Extraction of neutron-neutron scattering length from nn coincidence-geometry nd breakup data
Directory of Open Access Journals (Sweden)
E. S. Konobeevski
2011-03-01
Full Text Available We report preliminary results of a kinematically complete experiment on measurement of nd breakup reaction yield at neutron beam RADEX of Institute for Nuclear Research (Moscow, Russia. In the experiment two secondary neutrons are detected in geometry of neutron-neutron final-state interaction. Data are obtained at energy of incident neutrons En = 40 - 60 MeV for various divergence angles of two neutrons ΔΘ = 4, 6, 8º. 1S0 neutron-neutron scattering length ann were determined by comparison of the experimental dependence of reaction yield on the relative energy of two secondary neutrons with results of simulation depending on ann. For En = 40 MeV and ΔΘ = 6º (the highest statistics in the experiment the value ann = -17.9 ± 1.0 fm is obtained. The further improving of accuracy of the experiment and more rigorous theoretical analysis will allow one to remove the existing difference in ann values obtained in different experiments.
The development and application of a coincidence measurement apparatus with micro-computer system
International Nuclear Information System (INIS)
Du Hongshan; Zhou Youpu; Gao Junlin; Qin Deming; Cao Yunzheng; Zhao Shiping
1987-01-01
A coincidence measurement apparatus with micro-computer system is developed. Automatic data acquisition and processing are achieved. Results of its application for radioactive measurement are satisfactory
A deadtime reduction circuit for thermal neutron coincidence counters with Amptek preamplifiers
International Nuclear Information System (INIS)
Bourret, S.C.; Krick, M.S.
1994-01-01
We have developed a deadtime reduction circuit for thermal neutron coincidence counters using Amptek preamplifier/amplifier/discriminator circuits. The principle is to remove the overlap between the output pulses from the Amptek circuits by adding a derandomizer between the Amptek circuits and the shift-register coincidence electronics. We implemented the derandomizer as an Actel programmable logic array; the derandomizer board is small and can be mounted in the high-voltage junction box with the Amptek circuits, if desired. Up to 32 Amptek circuits can be used with one derandomizer. The derandomizer has seven outputs: four groups of eight inputs, two groups of 16 inputs, and one group of 32 inputs. We selected these groupings to facilitate detector ring-ratio measurements. The circuit was tested with the five-ring research multiplicity counter, which has five output signals-one for each ring. The counter's deadtime was reduced from 70 to 30 ns
The high-level neutron coincidence counter (HLNCC) family of detectors
International Nuclear Information System (INIS)
Ramalho, A.; Dahn, E.; Selleck, E.; Kupryashkin, V.; Dubreuil, A.
1983-01-01
A description of a group of detectors based on The High-Level Neutron Coincidence Counter (HLNCC) concept is presented. Experience in their utilization is summarized and the procedures followed in calibration and data treatment are described. Advantages of the use of this variety of detectors in simplifying the NDA verifications, reducing the interference with facility operators, and increasing the effectiveness of the inspectors' work are stressed. Likewise, remaining problems such as the need for a vigorous programme directed at achieving the best independent calibrations are emphasized. (author)
International Nuclear Information System (INIS)
Baron, N.
1978-01-01
A correction is described for multiplication and moderation when doing passive thermal neutron coincidence counting nondestructive assay measurements on powder samples of PuO 2 mixed arbitrarily with MgO, SiO 2 , and moderating material. The multiplication correction expression is shown to be approximately separable into the product of two independent terms; F/sub Pu/ which depends on the mass of 240 Pu, and F/sub αn/ which depends on properties of the matrix material. Necessary assumptions for separability are (1) isotopic abundances are constant, and (2) fission cross sections are independent of incident neutron energy: both of which are reasonable for the 8% 240 Pu powder samples considered here. Furthermore since all prompt fission neutrons are expected to have nearly the same energy distributions, variations among different samples can be due only to the moderating properties of the samples. Relative energy distributions are provided by a thermal neutron well counter having two concentric rings of 3 He proportional counters placed symmetrically about the well. Measured outer-to-inner ring ratios raised to an empirically determined power for coincidences, (N/sup I//N/sup O/)/sup Z/, and singles, (T/sup O//T/sup I/)/sup delta/, provide corrections for moderation and F/sub αn/ respectively, and F/sub Pu/ is approximated by M 240 /sup X//M 240 . The exponents are calibration constants determined by a least squares fitting procedure using standards' data. System calibration is greatly simplified using the separability principle. Once appropriate models are established for F/sub Pu/ and F/sub αn/, only a few standards are necessary to determine the calibration constants associated with these terms. Since F/sub Pu/ is expressed as a function of M 240 , correction for multiplication in a subsequent assay demands only a measurement of F/sub αn/
International Nuclear Information System (INIS)
Foley, J.E.
1980-10-01
The portable High-Level Neutron Coincidence Counter is used in the active mode with the addition of AmLi neutron sources to assay the 235 U content of highly enriched metal pieces or buttons. It is concluded that the portable instrument is a practical instrument for assaying uranium metal buttons with masses in the range 1.5 to 4 kg
International Nuclear Information System (INIS)
Suzuki, Shogo; Okada, Yukiko; Hirai, Shoji
2005-01-01
Trace element concentrations in scallop reference material and fish otolith certified reference materials prepared at the National Institute for Environmental Studies (NIES) of Japan were determined by instrumental neutron activation analysis (INAA). Nine aliquots of scallop sample (ca. 252∼507 mg) and five aliquots of fish otolith sample (ca. 502 ∼ 988 mg) and comparative standards were irradiated for a short time (10 s) at a thermal neutron flux of 1.5 x 10 12 n cm -2 s -1 (pneumatic transfer) and for a long time (6 h) at a thermal neutron flux of 3.7 x 10 12 n cm -2 s -1 (central thimble) in the Rikkyo University Research Reactor (100 kW). The irradiated samples were measured by conventional γ-ray spectrometry using a coaxial Ge detector, and by anti-coincidence and coincidence γ-ray spectrometry with a coaxial Ge detector and a well-type NaI (Tl) detector to determine as many trace elements as possible with high sensitivity. The concentrations of 34 elements of the NIES No.15 scallop reference material and 16 elements of the NIES No.22 fish otolith CRM were determined. Using the coincidence counting method to determine Se, Ba and Hf, the lower limit of the determination was improved by 2 times compared with the conventional counting method. (author)
Energy Technology Data Exchange (ETDEWEB)
Trivelpiece, Cory L., E-mail: cory@psu.ed [Department of Mechanical and Nuclear Engineering, The Pennsylvania, State University, University Park, PA 16802 (United States); Brenizer, J.S. [Department of Mechanical and Nuclear Engineering, The Pennsylvania, State University, University Park, PA 16802 (United States)
2011-01-01
A diameter of uncertainty (D{sub u}) was derived from a geometric uncertainty model describing the error that would be introduced into position-sensitive, coincidence neutron detection measurements by charged-particle transport phenomena and experimental setup. The transport of {alpha} and Li ions, produced by the {sup 10}B(n,{alpha}) {sup 7}Li reaction, through free-standing boro-phosphosilicate glass (BPSG) films was modeled using the Monte Carlo code SRIM, and the results of these simulations were used as input to determine D{sub u} for position-sensitive, coincidence techniques. The results of these calculations showed that D{sub u} is dependent on encoder separation, the angle of charged particle emission, and film thickness. For certain emission scenarios, the magnitude of D{sub u} is larger than the physical size of the neutron converting media that were being modeled. Spheres of uncertainty were developed that describe the difference in flight path times among the bounding-case emission scenarios that were considered in this work. It was shown the overlapping spheres represent emission angles and particle flight path lengths that would be difficult to resolve in terms of particle time-of-flight measurements. However, based on the timing resolution of current nuclear instrumentation, emission events that yield large D{sub u} can be discriminated by logical arguments during spectral deconvolution.
Feynman variance-to-mean in the context of passive neutron coincidence counting
Energy Technology Data Exchange (ETDEWEB)
Croft, S., E-mail: scroft@lanl.gov [Los Alamos National Laboratory, PO Box 1663, Los Alamos, NM 87545 (United States); Favalli, A.; Hauck, D.K.; Henzlova, D.; Santi, P.A. [Los Alamos National Laboratory, PO Box 1663, Los Alamos, NM 87545 (United States)
2012-09-11
Passive Neutron Coincidence Counting (PNCC) based on shift register autocorrelation time analysis of the detected neutron pulse train is an important Nondestructive Assay (NDA) method. It is used extensively in the quantification of plutonium and other spontaneously fissile materials for purposes of nuclear materials accountancy. In addition to the totals count rate, which is also referred to as the singles, gross or trigger rate, a quantity known as the reals coincidence rate, also called the pairs or doubles, is obtained from the difference between the measured neutron multiplicities in two measurement gates triggered by the incoming events on the pulse train. The reals rate is a measure of the number of time correlated pairs present on the pulse train and this can be related to the fission rates (and hence material mass) since fissions emit neutrons in bursts which are also detected in characteristic clusters. A closely related measurement objective is the determination of the reactivity of systems as they approach criticality. In this field an alternative autocorrelation signature is popular, the so called Feynman variance-to-mean technique which makes use of the multiplicity histogram formed the periodic, or clock-triggered opening of a coincidence gate. Workers in these two application areas share common challenges and improvement opportunities but are often separated by tradition, problem focus and technical language. The purpose of this paper is to recognize the close link between the Feynman variance-to-mean metric and traditional PNCC using shift register logic applied to correlated pulse trains. We, show using relationships for the late-gate (or accidentals) histogram recorded using a multiplicity shift register, how the Feynman Y-statistic, defined as the excess variance-to-mean ratio, can be expressed in terms of the singles and doubles rates familiar to the safeguards and waste assay communities. These two specialisms now have a direct bridge between
Characterizations of double pulsing in neutron multiplicity and coincidence counting systems
Energy Technology Data Exchange (ETDEWEB)
Koehler, Katrina E., E-mail: kkoehler@lanl.gov [Los Alamos National Laboratory, P. O. Box 1663, Los Alamos, NM 87545 (United States); Henzl, Vladimir [Los Alamos National Laboratory, P. O. Box 1663, Los Alamos, NM 87545 (United States); Croft, Stephen S. [Oak Ridge National Laboratory, 1 Bethel Valley Rd, Oak Ridge, TN 37831 (United States); Henzlova, Daniela; Santi, Peter A. [Los Alamos National Laboratory, P. O. Box 1663, Los Alamos, NM 87545 (United States)
2016-10-01
Passive neutron coincidence/multiplicity counters are subject to non-ideal behavior, such as double pulsing and dead time. It has been shown in the past that double-pulsing exhibits a distinct signature in a Rossi-alpha distribution, which is not readily noticed using traditional Multiplicity Shift Register analysis. However, it has been assumed that the use of a pre-delay in shift register analysis removes any effects of double pulsing. In this work, we use high-fidelity simulations accompanied by experimental measurements to study the effects of double pulsing on multiplicity rates. By exploiting the information from the double pulsing signature peak observable in the Rossi-alpha distribution, the double pulsing fraction can be determined. Algebraic correction factors for the multiplicity rates in terms of the double pulsing fraction have been developed. We discuss the role of these corrections across a range of scenarios.
International Nuclear Information System (INIS)
Menlove, H.O.; Keddar, A.
1982-08-01
The passive neutron Coincidence Collar, which was developed for the verification of plutonium content in fast reactor fuel subassemblies, has been field tested using Prototype Fast Reactor fuel. For passive applications, the system measures the 240 Pu-effective mass from the spontaneous fission rate, and in addition, a self-interrogation technique is used to determine the fissile content in the subassembly. Both the passive and active modes were evaluated at the Windscale Works in the United Kingdom. The results of the tests gave a standard deviation 0.75% for the passive count and 3 to 7% for the active measurement for a 1000-s counting time. The unit will be used in the future for the verification of plutonium in fresh fuel assemblies
Energy Technology Data Exchange (ETDEWEB)
Nguyen, Tam Cong, E-mail: tam.nguyen.cong@energia.mta.hu; Huszti, Jozsef; Nguyen, Quan Van
2015-09-01
Effect of double false pulses of preamplifiers in neutron coincidence collar was investigated to explain non-parallel shape of calibrated D/S–M{sub Pu} curves of two commercial neutron coincidence collars, JCC-31 and JCC-13. Two curves, which were constructed from D/S ratio (doubles and singles count rate), and Pu content M{sub Pu}, of the same set of secondary standard PuBe neutron sources, should be parallel. Non-parallelism rises doubt about usability of the method based on this curve for determination of Pu content in PuBe neutron sources. We have shown in three steps that the problem originates from double false pulses of preamplifiers in JCC-13. First we used a pulse train diagram for analyzing the non-parallel shape, second we used Rossi-Alpha distribution measured by pulse train recorder developed in our institute and finally, we investigated the effect of inserted noise pulses. This implies a new type of QA test option in traditional multiplicity shift registers for excluding presence of double false pulses.
International Nuclear Information System (INIS)
Langner, D.G.; Russo, P.A.
1993-02-01
We have studied the problem of assaying impure plutonium-bearing materials using passive neutron coincidence counting. We have developed a technique to analyze neutron coincidence data from impure plutonium samples that uses the bulk geometry of the sample to correct for multiplication in samples for which the (α,n) neutron production rate is unknown. This technique can be applied to any impure plutonium-bearing material whose matrix constituents are approximately constant, whose self-multiplication is low to moderate, whose plutonium isotopic composition is known and not substantially varying, and whose bulk geometry is measurable or can be derived. This technique requires a set of reference materials that have well-characterized plutonium contents. These reference materials are measured once to derive a calibration that is specific to the neutron detector and the material. The technique has been applied to molten salt extraction residues, PuF 4 samples that have a variable salt matrix, and impure plutonium oxide samples. It is also applied to pure plutonium oxide samples for comparison. Assays accurate to 4% (1 σ) were obtained for impure samples measured in a High-Level Neutron Coincidence Counter II. The effects on the technique of variations in neutron detector efficiency with energy and the effects of neutron capture in the sample are discussed
Coincident measurement between neutron and fragment in reaction sup 1 sup 7 N + sup 1 sup 9 sup 7 Au
Li Xiang Qing; Jiang Dong Xing; Ye Yan Lin; Chen Tao; Li Zhi Huan; Ge Yuch Eng; Wang Quan Jin; Wu He Yu; Jin Ge; Duan Li Min; Xiao Zhi Gang; Wang Hong Wei; Li Zu Yu; Wang Su Fang
2002-01-01
In the reaction induced by 33.4 MeV/u sup 1 sup 7 N beam on sup 1 sup 9 sup 7 Au, the coincident measurement between neutron and fragment was performed with the different combinations of 16 neutron detectors at 4 degree-83 degree and 14 telescopes at 2.3 degree - 9.0 degree. Integrating the measured angular distributions of the different isotopes, the isotopic yield distributions of Z = 3-6 elements are obtained. Based on the Abrasion-ablation model, isotopic yield distributions are calculated using different density distributions for the projectile sup 1 sup 7 N and compared with the experiment data
Energy Technology Data Exchange (ETDEWEB)
Lahmann, B., E-mail: lahmann@mit.edu; Milanese, L. M.; Han, W.; Gatu Johnson, M.; Séguin, F. H.; Frenje, J. A.; Petrasso, R. D. [Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Hahn, K. D.; Jones, B. [Sandia National Laboratory, Albuquerque, New Mexico 87123 (United States)
2016-11-15
A compact neutron spectrometer, based on a CH foil for the production of recoil protons and CR-39 detection, is being developed for the measurements of the DD-neutron spectrum at the NIF, OMEGA, and Z facilities. As a CR-39 detector will be used in the spectrometer, the principal sources of background are neutron-induced tracks and intrinsic tracks (defects in the CR-39). To reject the background to the required level for measurements of the down-scattered and primary DD-neutron components in the spectrum, the Coincidence Counting Technique (CCT) must be applied to the data. Using a piece of CR-39 exposed to 2.5-MeV protons at the MIT HEDP accelerator facility and DD-neutrons at Z, a significant improvement of a DD-neutron signal-to-background level has been demonstrated for the first time using the CCT. These results are in excellent agreement with previous work applied to DT neutrons.
International Nuclear Information System (INIS)
Lahmann, B.; Milanese, L. M.; Han, W.; Gatu Johnson, M.; Séguin, F. H.; Frenje, J. A.; Petrasso, R. D.; Hahn, K. D.; Jones, B.
2016-01-01
A compact neutron spectrometer, based on a CH foil for the production of recoil protons and CR-39 detection, is being developed for the measurements of the DD-neutron spectrum at the NIF, OMEGA, and Z facilities. As a CR-39 detector will be used in the spectrometer, the principal sources of background are neutron-induced tracks and intrinsic tracks (defects in the CR-39). To reject the background to the required level for measurements of the down-scattered and primary DD-neutron components in the spectrum, the Coincidence Counting Technique (CCT) must be applied to the data. Using a piece of CR-39 exposed to 2.5-MeV protons at the MIT HEDP accelerator facility and DD-neutrons at Z, a significant improvement of a DD-neutron signal-to-background level has been demonstrated for the first time using the CCT. These results are in excellent agreement with previous work applied to DT neutrons.
Lahmann, B; Milanese, L M; Han, W; Gatu Johnson, M; Séguin, F H; Frenje, J A; Petrasso, R D; Hahn, K D; Jones, B
2016-11-01
A compact neutron spectrometer, based on a CH foil for the production of recoil protons and CR-39 detection, is being developed for the measurements of the DD-neutron spectrum at the NIF, OMEGA, and Z facilities. As a CR-39 detector will be used in the spectrometer, the principal sources of background are neutron-induced tracks and intrinsic tracks (defects in the CR-39). To reject the background to the required level for measurements of the down-scattered and primary DD-neutron components in the spectrum, the Coincidence Counting Technique (CCT) must be applied to the data. Using a piece of CR-39 exposed to 2.5-MeV protons at the MIT HEDP accelerator facility and DD-neutrons at Z, a significant improvement of a DD-neutron signal-to-background level has been demonstrated for the first time using the CCT. These results are in excellent agreement with previous work applied to DT neutrons.
Energy Technology Data Exchange (ETDEWEB)
McElroy, Robert Dennis [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Cleveland, Steven L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
2017-03-01
The ^{235}U mass assay of bulk uranium items, such as oxide canisters, fuel pellets, and fuel assemblies, is not achievable by traditional gamma-ray assay techniques due to the limited penetration of the item by the characteristic ^{235}U gamma rays. Instead, fast neutron interrogation methods such as active neutron coincidence counting must be used. For international safeguards applications, the most commonly used active neutron systems, the Active Well Coincidence Counter (AWCC), Uranium Neutron Collar (UNCL) and ^{252}Cf Shuffler, rely on fast neutron interrogation using an isotopic neutron source [i.e., ^{252}Cf or Am(Li)] to achieve better measurement accuracies than are possible using gamma-ray techniques for high-mass, high-density items. However, the Am(Li) sources required for the AWCC and UNCL systems are no longer manufactured, and newly produced systems rely on limited supplies of sources salvaged from disused instruments. The ^{252}Cf shuffler systems rely on the use of high-output ^{252}Cf sources, which while still available have become extremely costly for use in routine operations and require replacement every five to seven years. Lack of a suitable alternative neutron interrogation source would leave a potentially significant gap in the safeguarding of uranium processing facilities. In this work, we made use of Oak Ridge National Laboratory’s (ORNL’s) Large Volume Active Well Coincidence Counter (LV-AWCC) and a commercially available deuterium-deuterium (D-D) neutron generator to examine the potential of the D-D neutron generator as an alternative to the isotopic sources. We present the performance of the LV-AWCC with D-D generator for the assay of ^{235}U based on the results of Monte Carlo N-Particle (MCNP) simulations and measurements of depleted uranium (DU), low enriched uranium (LEU), and highly enriched uranium (HEU) items.
International Nuclear Information System (INIS)
Timm, Jan Horst Karl
2015-11-01
The aim of the COBRA experiment is the observation of neutrinoless double-beta decay, primarily of the isotope 116 Cd. The applied semiconductor detectors of cadmium zinc telluride that are 90% to be enriched enable both the detection and the source of this decay. The half-lives of decays of this kind are expected in the range of more than 10 26 years. Therefore, the reduction of contributions to the background is of decisive importance. The main subjects of this work are, on the one hand, the time synchronization of the data, which provides the basis for coincidence analysis. This analysis method has access not only to identification of contributions to the background, but also to observe decays involving positron annihilation and decays into excited states. In this study, the intrinsic detector contamination of some decay products of 238 U and 232 Th was measured and sensitivities to the half-lives of the decays like 120 Te and 128 Te in each case to the first excited state of daughter products are given. On the other hand, qualitative studies on the importance of neutrons in the COBRA experiment were conducted. These have shown that fast neutrons, thus with energies greater than 10 keV, only result in an insignificant contribution to the background for the detection of neutrinoless double-beta decay of the 116 Cd. Previous studies have also shown that the thermal neutron flux can be in situ determined by coincidence analysis.
The computer library of experimental neutron data
International Nuclear Information System (INIS)
Bychkov, V.M.; Manokhin, V.N.; Surgutanov, V.V.
1976-05-01
The paper describes the computer library of experimental neutron data at the Obninsk Nuclear Data Centre. The format of the library (EXFOR) and the system of programmes for supplying the library are briefly described. (author)
Heterogeneity effects in neutron transport computations
International Nuclear Information System (INIS)
Gelbard, E.M.
1975-01-01
A nuclear reactor is, generally, an intricate heterogeneous structure whose adjacent components may differ radically in their neutronic properties. The heterogeneities in the structure of the reactor complicate the work of the reactor analyst and tend to degrade the efficiency of the numerical methods used in reactor computations. Two types of heterogeneity effects are considered. First, certain singularities in the solution of the neutron transport equation, induced by heterogeneities, are briefly described. Second, the effect of heterogeneities on neutron leakage rates, and consequently on effective diffusion coefficients, are discussed. (5 figures) (U.S.)
Neutron stimulated emission computed tomography: Background corrections
International Nuclear Information System (INIS)
Floyd, Carey E.; Sharma, Amy C.; Bender, Janelle E.; Kapadia, Anuj J.; Xia, Jessie Q.; Harrawood, Brian P.; Tourassi, Georgia D.; Lo, Joseph Y.; Kiser, Matthew R.; Crowell, Alexander S.; Pedroni, Ronald S.; Macri, Robert A.; Tajima, Shigeyuki; Howell, Calvin R.
2007-01-01
Neutron stimulated emission computed tomography (NSECT) is an imaging technique that provides an in-vivo tomographic spectroscopic image of the distribution of elements in a body. To achieve this, a neutron beam illuminates the body. Nuclei in the body along the path of the beam are stimulated by inelastic scattering of the neutrons in the beam and emit characteristic gamma photons whose unique energy identifies the element. The emitted gammas are collected in a spectrometer and form a projection intensity for each spectral line at the projection orientation of the neutron beam. Rotating and translating either the body or the beam will allow a tomographic projection set to be acquired. Images are reconstructed to represent the spatial distribution of elements in the body. Critical to this process is the appropriate removal of background gamma events from the spectrum. Here we demonstrate the equivalence of two background correction techniques and discuss the appropriate application of each
Evaluation of B10Plus+* proportional detectors for neutron coincidence counting
Energy Technology Data Exchange (ETDEWEB)
Beddingfield, David H.; Yoon, Seokryung [International Atomic Energy Agency, Vienna International Centre, PO Box 100, 1400 Vienna, (Austria)
2015-07-01
GE-Reuter-Stokes (GERS) has developed a new line of neutron proportional counters, the B10Plus+* proportional counter. The detector design is intended to serve as a cost-effective alternative to traditional {sup 3}He proportional counters in a variety of applications. The detector is a hybrid design 10B-lined tube optimized with the addition of a small quantity of 3He gas to improve the detector performance and efficiency. As a demonstration of the B10Plus+* detector, GERS has constructed a Uranium Neutron Collar (UNCL) system consisting of B-10Plus+* proportional counters. GERS has designed and built a demonstration UNCL system intended to match the performance of a Type-I UNCL design in Pressurized Water Reactor (PWR) geometry operating in thermal mode. GERS offered their system on loan to the International Atomic Energy Agency (IAEA) Safeguards Division of Technical and Scientific Services for an assessment of the detector technology and the demonstration system. We have characterized the demonstration UNCL system and compared its performance with a traditional Type-I UNCL design in regular use by the IAEA. This paper summarizes our findings and observations during the characterization and testing activity. (authors)
Joyce, Malcolm J.; Gamage, Kelum A. A.; Aspinall, M. D.; Cave, F. D.; Lavietes, A.
2014-06-01
The design, principle of operation and the results of measurements made with a four-channel organic scintillator system are described. The system comprises four detectors and a multiplexed analyzer for the real-time parallel processing of fast neutron events. The function of the real-time, digital multiple-channel pulse-shape discrimination analyzer is described together with the results of laboratory-based measurements with 252Cf, 241Am-Li and plutonium. The analyzer is based on a single-board solution with integrated high-voltage supplies and graphical user interface. It has been developed to meet the requirements of nuclear materials assay of relevance to safeguards and security. Data are presented for the real-time coincidence assay of plutonium in terms of doubles count rate versus mass. This includes an assessment of the limiting mass uncertainty for coincidence assay based on a 100 s measurement period and samples in the range 0-50 g. Measurements of count rate versus order of multiplicity for 252Cf and 241Am-Li and combinations of both are also presented.
Li Xiang Qing; Ye Yan Lin; Hua Hui; Chen Tao; Li Zhi Huan; Ge Yuch Eng; Wang Quan Jin; Wu He Yu; Jin Ge; Duan Li Min; Xiao Zhi Gang; Wang Hong Wei; Li Zhu Yu; Wang Su Fang
2002-01-01
The authors present the experimental isotopic distributions of the sup 1 sup 8 N projectile fragmentation products Li, Be, B and C in coincidence with neutrons, as well as the inclusive ones on sup 1 sup 9 sup 7 Au and sup 9 Be targets. In the framework of the abrasion-ablation model, these distributions are calculated for various nucleon density distributions of the projectile. The comparison with experimental isotopic distributions of the projectile-like fragments in coincidence with neutrons shows that the information on the nucleon density distribution of the sup 1 sup 8 N projectile can be extracted
International Nuclear Information System (INIS)
Zhang, W.H.; Chatt, A.
1997-01-01
Iodine is an element of interest in nutritional research. Its lower limit of safe and adequate daily dietary intake for adults varies between 150 and 200 micrograms per day. In the present study, an epithermal instrumental neutron activation analysis (EINAA) method in conjunction with anti-coincidence counting has been developed for the determination of ppb levels of iodine in individual food items. Typically 200-300 mg of a sample are irradiated for 10 or 20 minutes at the Dalhousie University SLOWPOKE-2 reactor in an epithermal flux of 1x10 11 n cm -2 s -1 , followed by 1 min decay and then counting for 30 min. The 443-keV gamma-ray of 128 I is used for measuring iodine content by anti-coincidence counting. The anti-coincidence spectrometer consists of a 25% HPGe detector surrounded by a 10''x10'' NaI(TI) annulus and a 3''x3'' NaI(TI) plug. This system has a peak-to-Compton ratio of about 650 to 1 for the 661.6-keV photopeak of 137 Cs. The Compton background resulting from the scattering of many gamma-rays of energies higher than 443 keV can be reduced by a factor of about 4 using anti-coincidence counting compared to conventional counting. The detection limit for iodine can be improved by a factor of 2 to 5 depending on the sample matrix, dead time, position of the annulus and counting geometry among several other factors.The lowest detection limit of 5 ppb can be achieved for low-salt foods. This limit is comparable to that obtained by a preconcentration NAA (PNAA) method. However, a detection limit of 20 ppb is more realistic for samples containing high amounts of Na, Cl and Al. The results obtained for many reference materials are in good agreement with the certified values and those reported by the PNAA method. Details of the methods and results will be reported
Energy Technology Data Exchange (ETDEWEB)
Zhang, W.H.; Chatt, A. [Dalhousie University, Halifax, Nova Scotia (Canada). Radiochemistry Research Laboratory
1997-10-01
Iodine is an element of interest in nutritional research. Its lower limit of safe and adequate daily dietary intake for adults varies between 150 and 200 micrograms per day. In the present study, an epithermal instrumental neutron activation analysis (EINAA) method in conjunction with anti-coincidence counting has been developed for the determination of ppb levels of iodine in individual food items. Typically 200-300 mg of a sample are irradiated for 10 or 20 minutes at the Dalhousie University SLOWPOKE-2 reactor in an epithermal flux of 1x10{sup 11} n cm{sup -2} s{sup -1}, followed by 1 min decay and then counting for 30 min. The 443-keV gamma-ray of {sup 128}I is used for measuring iodine content by anti-coincidence counting. The anti-coincidence spectrometer consists of a 25% HPGe detector surrounded by a 10``x10`` NaI(TI) annulus and a 3``x3`` NaI(TI) plug. This system has a peak-to-Compton ratio of about 650 to 1 for the 661.6-keV photopeak of {sup 137}Cs. The Compton background resulting from the scattering of many gamma-rays of energies higher than 443 keV can be reduced by a factor of about 4 using anti-coincidence counting compared to conventional counting. The detection limit for iodine can be improved by a factor of 2 to 5 depending on the sample matrix, dead time, position of the annulus and counting geometry among several other factors.The lowest detection limit of 5 ppb can be achieved for low-salt foods. This limit is comparable to that obtained by a preconcentration NAA (PNAA) method. However, a detection limit of 20 ppb is more realistic for samples containing high amounts of Na, Cl and Al. The results obtained for many reference materials are in good agreement with the certified values and those reported by the PNAA method. Details of the methods and results will be reported 6 refs., 2 tabs.
International Nuclear Information System (INIS)
Sukhovoj, A.M.; Khitrov, V.A.
1982-01-01
A method of improvement of amplitude resolution in the case of record of coinciding codes on the magnetic tape is suggested. It is shown on the record with Ge(Li) detectors of cascades of gamma-transitions from the 35 Cl(n, #betta#) reaction that total width at a half maximum of the peak may decrease by a factor of 2.6 for quanta with the energy similar to the neutron binding energy. Efficiency loss is absent
Total variation-based neutron computed tomography
Barnard, Richard C.; Bilheux, Hassina; Toops, Todd; Nafziger, Eric; Finney, Charles; Splitter, Derek; Archibald, Rick
2018-05-01
We perform the neutron computed tomography reconstruction problem via an inverse problem formulation with a total variation penalty. In the case of highly under-resolved angular measurements, the total variation penalty suppresses high-frequency artifacts which appear in filtered back projections. In order to efficiently compute solutions for this problem, we implement a variation of the split Bregman algorithm; due to the error-forgetting nature of the algorithm, the computational cost of updating can be significantly reduced via very inexact approximate linear solvers. We present the effectiveness of the algorithm in the significantly low-angular sampling case using synthetic test problems as well as data obtained from a high flux neutron source. The algorithm removes artifacts and can even roughly capture small features when an extremely low number of angles are used.
Computed image analysis of neutron radiographs
International Nuclear Information System (INIS)
Dinca, M.; Anghel, E.; Preda, M.; Pavelescu, M.
2008-01-01
Similar with X-radiography, using neutron like penetrating particle, there is in practice a nondestructive technique named neutron radiology. When the registration of information is done on a film with the help of a conversion foil (with high cross section for neutrons) that emits secondary radiation (β,γ) that creates a latent image, the technique is named neutron radiography. A radiographic industrial film that contains the image of the internal structure of an object, obtained by neutron radiography, must be subsequently analyzed to obtain qualitative and quantitative information about the structural integrity of that object. There is possible to do a computed analysis of a film using a facility with next main components: an illuminator for film, a CCD video camera and a computer (PC) with suitable software. The qualitative analysis intends to put in evidence possibly anomalies of the structure due to manufacturing processes or induced by working processes (for example, the irradiation activity in the case of the nuclear fuel). The quantitative determination is based on measurements of some image parameters: dimensions, optical densities. The illuminator has been built specially to perform this application but can be used for simple visual observation. The illuminated area is 9x40 cm. The frame of the system is a comparer of Abbe Carl Zeiss Jena type, which has been adapted to achieve this application. The video camera assures the capture of image that is stored and processed by computer. A special program SIMAG-NG has been developed at INR Pitesti that beside of the program SMTV II of the special acquisition module SM 5010 can analyze the images of a film. The major application of the system was the quantitative analysis of a film that contains the images of some nuclear fuel pins beside a dimensional standard. The system was used to measure the length of the pellets of the TRIGA nuclear fuel. (authors)
Neutron spectrum unfolding using computer code SAIPS
International Nuclear Information System (INIS)
Karim, S.
1999-01-01
The main objective of this project was to study the neutron energy spectrum at rabbit station-1 in Pakistan Research Reactor (PARR-I). To do so, multiple foils activation method was used to get the saturated activities. The computer code SAIPS was used to unfold the neutron spectra from the measured reaction rates. Of the three built in codes in SAIPS, only SANDI and WINDOWS were used. Contribution of thermal part of the spectra was observed to be higher than the fast one. It was found that the WINDOWS gave smooth spectra while SANDII spectra have violet oscillations in the resonance region. The uncertainties in the WINDOWS results are higher than those of SANDII. The results show reasonable agreement with the published results. (author)
Progress in multidimensional neutron transport computation
International Nuclear Information System (INIS)
Lewis, E.E.
1977-01-01
The methods available for solution of the time-independent neutron transport problems arising in the analysis of nuclear systems are examined. The merits of deterministic and Monte Carlo methods are briefly compared. The capabilities of deterministic computational methods derived from the first-order form of the transport equation, from the second-order even-parity form of this equation, and from integral transport formulations are discussed in some detail. Emphasis is placed on the approaches for dealing with the related problems of computer memory requirements, computational cost, and achievable accuracy. Attention is directed to some areas where problems exist currently and where the need for further work appears to be particularly warranted
International Nuclear Information System (INIS)
Stewart, J.E.; Menlove, H.O.; Ferran, R.R.; Aparo, M.; Zeppa, P.; Troiani, F.
1993-05-01
For passive neutron-coincidence-counting verification measurements of PuO 2 and MOX powder, assay biases have been observed that result from moisture entrained in the sample. This report describes a unique set of experiments in which MOX samples, with a range of moisture concentrations, were produced and used to calibrate and evaluate two prototype moisture monitors. A new procedure for moisture corrections to PuO 2 and MOX verification measurements yields MOX assays accurate to 1.5% (1σ) for 0.6- and 1.1-kg samples. Monte Carlo simulations were used to extend the measured moisture calibration data to higher sample masses. A conceptual design for a high-efficiency neutron coincidence counter with improved sensitivity to moisture is also presented
Overview of the history of neutronics computations
International Nuclear Information System (INIS)
Gelbard, E.M.
1992-01-01
This paper provides some background and perspective on the history of neutronics computations. The author started his carerr at Bettis Atomic Power Laboratory (BAPL) in 1954. At that time, computers were primitive and unfamiliar to most of us. Bettis did own an IBM Card Programmed Computer, which, as its name suggested, had a punched-card memory, and some of the industry's first cross-section preparation codes (the early MUFTs) were written for this machine by Ben Mount. There was also at BAPL another digital machine, which spewed output everywhere on punched tape. But the laboratory's most powerful machine was an analog computer that solved two-group diffusion equations in two dimensions. An excellent physicist of that period argued that analog machines were the wave of the future because digital computers could never solve the diffusion equation in two dimensions. At the time, this seemed like a very reasonable prediction; yet it was not very long before Bettis was renting time on UNIVACs all over the country precisely to solve the two-dimensional diffusion equation. Since then, we have learned that it is always risky to predict future trends in the computer industry
International Nuclear Information System (INIS)
Plischke, P.
1981-01-01
With the proton beam of the Hamburg isochronous cyclotron (HAIZY) thin uranium targets with the mass numbers 235, 236, and 238 were bombarded. Both fragments from the fission of the Np reaction systems and the neutrons coincident with the fragments were detected in the plane perpendicular to the beam direction. Measured and stored event by event were for all particles the times of flight. The detection of the neutron succeeded in conventional time-of-flight technique with NE213 liquid scintillators. A fission detector system with plastic scintillator foils was developed. It permits high event rates over long measuring times and allows the choice of so long neutron flight paths that a neutron energy resolution between 2% and 4% could be reached. The determination of the fragment masses is in spite of the short flight paths of 15 respectively 21 cm possible to +-2 amu. The isotropic component das discussed under the assumption that it is composed of prefission and scission neutrons which were emitted befor fission respectively during the fragmentation. From the post fission results the distribution of the excitation energy to both fragments was determined in dependence of Esup(*) and the fragment mass. (orig./HSI) [de
Channel coincidence counter: version 1
International Nuclear Information System (INIS)
Krick, M.S.; Menlove, H.O.
1980-06-01
A thermal neutron coincidence counter has been designed for the assay of fast critical assembly fuel drawers and plutonium-bearing fuel rods. The principal feature of the detector is a 7-cm by 7-cm by 97-cm detector channel, which provides a uniform neutron detection efficiency of 16% along the central 40 cm of the channel. The electronics system is identical to that used for the High-Level Neutron Coincidence Counter
Energy Technology Data Exchange (ETDEWEB)
Ambrosino, G; Sorriaux, A [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires
1964-07-01
The experiment described consists in the measurement of the total cross-section of various materials: aluminium, carbon, fluorine and hydrogen, for mono-energetic 2.77 MeV neutrons obtained from the d,d reaction. The measurement is carried out by transmission. The neutrons are detected by means of a plastic scintillator mounted on a 56 AVP photomultiplier, and are isolated from all secondary phenomena (background noise, scattered neutrons) by coincidence with helium 3. which particles are associated to the neutrons from the reaction {sup 2}{sub 1}D ({sup 2}{sub 1}D, n) {sup 3}{sub 2}H The helium 3 particles are detected by a PN junction diode used with inverted polarisation. An absorption exponential has been traced out using measurements made on seven aluminium bars. The accuracy of the total cross-section measurements is about 10{sup -2}. (authors) [French] L'experience exposee dans ce rapport consiste en la mesure des sections efficaces totales de differents materiaux: aluminium, carbone, fluor et hydrogene, pour des neutrons monoenergetiques de 2,77 MeV, obtenus par la reaction d,d. La mesure est faite par transmission. Les neutrons sont detectes par un scintillateur plastique monte sur un photomultiplicateur 56 AVP, et sont separes de tout phenomene secondaire (bruit de fond, neutrons diffuses) par coincidence avec les helium 3, particules associees aux neutrons de la reaction {sup 2}{sub 1}D ({sup 2}{sub 1}D, n) {sup 3}{sub 2}H Les helium 3 sont detectes par une diode a jonction PN utilisee en polarisation inverse. Une exponentielle d'absorption a ete tracee a partir de mesures faites sur sept barreaux d'aluminium. La precision des mesures des sections efficaces totales est de l'ordre de 10{sup -2}. (auteurs)
Megachannel γ--γ coincidence system using a PDP-8/E computer and moving-head disks
International Nuclear Information System (INIS)
Ruhter, W.D.; Camp, D.C.; Mann, L.G.; Niday, J.B.; Siemens, P.D.
1976-01-01
A megachannel pulse-height analysis system using a PDP-8/E computer and two moving-head disk memories has been developed. The system has a storage capacity of 220 memory locations, is capable of processing 1100 events/s, and provides on-line sorting and disk storage. An X- or Y-pulse-height spectrum in coincidence with one or several arbitrary pulse-height windows can be assembled in core for scope display and spectral analysis within 2 to 20 seconds. Reconstruction of a complete X- or Y-pulse-height spectrum requires about 3 minutes
International Nuclear Information System (INIS)
Rizzo, S.; Tomarchio, E.
2008-01-01
Full text: The analytical relations used to compute the coincidence-summing effects on spectral response of Ge semiconductor detectors are quite complex and involve full-energy peak and total efficiencies. For point-sources, a general method for calculating the correction factors for gamma ray coincidences has been formulated by Andreev et al. and used by Schima and Hoppes to obtain γ-X K coincidence correction expressions for 17 nuclides. However, because the higher-order terms are neglected, the expressions supplied do not give reliable results in the case of short sample-detector distances. Using the formulae given by Morel et al.[3] and Lepy et al.[4], we have developed a computer program able to get numerical expressions to compute γ-γ e γ-X K coincidence summing corrections for point sources. Only full-energy peak and total efficiencies are needed. Alternatively, values of peak-to-total ratio can be introduced. For extended sources, the same expressions can be always considered with the introduction of 'effective efficiencies' as defined by Arnold and Sima, i.e. an average over the source volume of the spatial distribution of the elementary photon source total efficiency, weighted by the corresponding peak efficiency. We have considered the most used calibration radioisotopes as well as fission products, activation products and environmental isotopes. All decay data were taken from the most recent volumes of 'Table of Radionuclides', CEA Monographie BIPM-5 and a suitable matrix representation of a decay scheme was adopted. For the sake of brevity, we provide for each nuclide a set of expressions for the more intense gamma emissions, considered sufficient for most applications. However, numerical expressions are available for all the stored gamma transitions and can be obtained on request. As examples of the use of the expressions, the evaluation of correction values for point sources and a particulate sample reduced to a 6x6x0.7 cm packet - with reference
Computer codes for neutron data evaluation
International Nuclear Information System (INIS)
Nakagawa, Tsuneo
1979-01-01
Data compilation codes such as NESTOR and REPSTOR, and NDES (Neutron Data Evaluation System) are mainly discussed. NDES is a code for neutron data evaluation using a TSS terminal, TEKTRONIX 4014. Users of NDES can perform plotting of data and calculation with nuclear models under conversational mode. (author)
Computer-automated neutron activation analysis system
International Nuclear Information System (INIS)
Minor, M.M.; Garcia, S.R.
1983-01-01
An automated delayed neutron counting and instrumental neutron activation analysis system has been developed at Los Alamos National Laboratory's Omega West Reactor (OWR) to analyze samples for uranium and 31 additional elements with a maximum throughput of 400 samples per day. 5 references
Styron, Jedediah; Ruiz, Carlos; Hahn, Kelly; Cooper, Gary; Chandler, Gordon; Jones, Brent; McWatters, Bruce; Smith, Jenny; Vaughan, Jeremy
2017-10-01
A measured neutron time-of-flight (nTOF) signal is a convolution of the neutron reaction history and the instrument response function (IRF). For this work, the IRF was obtained by measuring single, D-T neutron events by utilizing n-alpha coincidence. The d(t, α) n nuclear reaction was produced at Sandia National Laboratories' Ion Beam Laboratory using a 300-keV Cockroft-Walton generator to accelerate a 2- μA beam, of 175-keV D + ions, into a stationary, 2.6- μm, ErT2 target. Comparison of these results to those obtained using cosmic-rays and photons will be discussed. Sandia National Laboratories.
International Nuclear Information System (INIS)
Valles, V.; Guiresse, M.; Tcherbakov, R.
1989-01-01
The distance between the gamma and neutron probe measurement centres was determined for the Nardeux Solo 40 and CPN 501 B probes. The centre of the spheres of influence was localized using a water-air interface constituted by a metal cylinder filled with 200 liters of water. For Solo 40, the discrepancy between the two measurement centres was 6 cm. This shift value, which is quite acceptable, does not require any correction for these measurements, even when the soil is heterogeneous. For CNP 501 B, the discrepancy between the neutron and gamma measurement was 11 cm, i.e. nearly twice the value observed with Solo 40. In soils with a marked vertical heterogeneity, it therefore seems preferable to operate a 11 cm shift of the probe between the moisture and density measurements [fr
International Nuclear Information System (INIS)
Croft, S.; McElroy, RD.; Favalli, A.; Hauck, D.; Henzlova, D.; Henzl, V.; Santi, PA.
2015-01-01
Passive neutron correlation counting is widely used, for example by international inspection agencies, for the non‑destructive assay of spontaneously fissile nuclear materials for nuclear safeguards. The mass of special nuclear material present in an item is usually estimated from the observed neutron counting rates by using equations based on mathematically describing the object as an isolated multiplying point‑like source. Calibration using representative physical standards can often adequately compensate for this theoretical oversimplification through the introduction and use of effective‑interpretational‑model‑parameters meaning that useful assay results are obtained. In this work we extend the point‑model treatment by including a simple reflector around the fissioning material. Specifically we show how the leakage self‑multiplication equation mathematically connects the traditional bare source and the reflected source cases. In doing so we explicitly demonstrate that although the presence of a simple reflector changes the leakage self‑multiplication the traditional bare‑item point model multiplicity equations retain the same mathematical form. Making and explaining this connection is important because it helps to explain and justify the practical success and use of the traditional point‑model equations even when the assumptions used to generate the key functional dependences are violated. We are not aware that this point has been recognized previously.
Analytic computation of average energy of neutrons inducing fission
International Nuclear Information System (INIS)
Clark, Alexander Rich
2016-01-01
The objective of this report is to describe how I analytically computed the average energy of neutrons that induce fission in the bare BeRP ball. The motivation of this report is to resolve a discrepancy between the average energy computed via the FMULT and F4/FM cards in MCNP6 by comparison to the analytic results.
Systems for neutronic, thermohydraulic and shielding calculation in personal computers
International Nuclear Information System (INIS)
Villarino, E.A.; Abbate, P.; Lovotti, O.; Santini, M.
1990-01-01
The MTR-PC (Materials Testing Reactors-Personal Computers) system has been developed by the Nuclear Engineering Division of INVAP S.E. with the aim of providing working conditions integrated with personal computers for design and neutronic, thermohydraulic and shielding analysis for reactors employing plate type fuel. (Author) [es
Local computer network of the JINR Neutron Physics Laboratory
International Nuclear Information System (INIS)
Alfimenkov, A.V.; Vagov, V.A.; Vajdkhadze, F.
1988-01-01
New high-speed local computer network, where intelligent network adapter (NA) is used as hardware base, is developed in the JINR Neutron Physics Laboratory to increase operation efficiency and data transfer rate. NA consists of computer bus interface, cable former, microcomputer segment designed for both program realization of channel-level protocol and organization of bidirectional transfer of information through direct access channel between monochannel and computer memory with or witout buffering in NA operation memory device
International Nuclear Information System (INIS)
Bruggeman, M.; Baeten, P.; De Boeck, W.; Carchon, R.
1996-03-01
The report describes a new neutron multiplicity counting method based on Rossi-alpha distributions. The report also gives the necessary dead time correction formulas for the multiplicity counting method. The method was tested numerically using a Monte Carlo simulation of pulse trains. The use of this multiplicity method in the field of waste assay is explained: it can be used to determine the amount of fissile material in a waste drum without prior knowledge of the actual detection efficiency
Initial water quantification results using neutron computed tomography
Heller, A. K.; Shi, L.; Brenizer, J. S.; Mench, M. M.
2009-06-01
Neutron computed tomography is an important imaging tool in the field of non-destructive testing and in fundamental research for many engineering applications. Contrary to X-rays, neutrons can be attenuated by some light materials, such as hydrogen, but can penetrate many heavy materials. Thus, neutron computed tomography is useful in obtaining important three-dimensional information about a sample's interior structure and material properties that other traditional methods cannot provide. The neutron computed tomography system at the Pennsylvania State University's Radiation Science and Engineering Center is being utilized to develop a water quantification technique for investigation of water distribution in fuel cells under normal conditions. A hollow aluminum cylinder test sample filled with a known volume of water was constructed for purposes of testing the quantification technique. Transmission images of the test sample at different angles were easily acquired through the synthesis of a dedicated image acquisition computer driving a rotary table controller and an in-house developed synchronization software package. After data acquisition, Octopus (version 8.2) and VGStudio Max (version 1.2) were used to perform cross-sectional and three-dimensional reconstructions of the sample, respectively. The initial reconstructions and water quantification results are presented.
An improved computer controlled triple-axis neutron spectrometer
International Nuclear Information System (INIS)
Cooper, M.J.; Hall, J.W.; Hutchings, M.T.
1975-07-01
A description is given of the computer-controlled triple-axis neutron spectrometer installed at the PLUTO reactor at Harwell. The reasons for an nature of recent major improvements are discussed. Following a general description of the spectrometer, details are then given of the new computerised control system, including the functions of the various programs which are now available to the user. (author)
Initial water quantification results using neutron computed tomography
Energy Technology Data Exchange (ETDEWEB)
Heller, A.K. [Department of Mechanical and Nuclear Engineering, Pennsylvania State University (United States)], E-mail: axh174@psu.edu; Shi, L.; Brenizer, J.S.; Mench, M.M. [Department of Mechanical and Nuclear Engineering, Pennsylvania State University (United States)
2009-06-21
Neutron computed tomography is an important imaging tool in the field of non-destructive testing and in fundamental research for many engineering applications. Contrary to X-rays, neutrons can be attenuated by some light materials, such as hydrogen, but can penetrate many heavy materials. Thus, neutron computed tomography is useful in obtaining important three-dimensional information about a sample's interior structure and material properties that other traditional methods cannot provide. The neutron computed tomography system at Pennsylvania State University's Radiation Science and Engineering Center is being utilized to develop a water quantification technique for investigation of water distribution in fuel cells under normal conditions. A hollow aluminum cylinder test sample filled with a known volume of water was constructed for purposes of testing the quantification technique. Transmission images of the test sample at different angles were easily acquired through the synthesis of a dedicated image acquisition computer driving a rotary table controller and an in-house developed synchronization software package. After data acquisition, Octopus (version 8.2) and VGStudio Max (version 1.2) were used to perform cross-sectional and three-dimensional reconstructions of the sample, respectively. The initial reconstructions and water quantification results are presented.
NNS computing facility manual P-17 Neutron and Nuclear Science
International Nuclear Information System (INIS)
Hoeberling, M.; Nelson, R.O.
1993-11-01
This document describes basic policies and provides information and examples on using the computing resources provided by P-17, the Neutron and Nuclear Science (NNS) group. Information on user accounts, getting help, network access, electronic mail, disk drives, tape drives, printers, batch processing software, XSYS hints, PC networking hints, and Mac networking hints is given
Informational-computer system for the neutron spectra analysis
International Nuclear Information System (INIS)
Berzonis, M.A.; Bondars, H.Ya.; Lapenas, A.A.
1979-01-01
In this article basic principles of the build-up of the informational-computer system for the neutron spectra analysis on a basis of measured reaction rates are given. The basic data files of the system, needed software and hardware for the system operation are described
Computer aided design of fast neutron therapy units
International Nuclear Information System (INIS)
Gileadi, A.E.; Gomberg, H.J.; Lampe, I.
1980-01-01
Conceptual design of a radiation-therapy unit using fusion neutrons is presently being considered by KMS Fusion, Inc. As part of this effort, a powerful and versatile computer code, TBEAM, has been developed which enables the user to determine physical characteristics of the fast neutron beam generated in the facility under consideration, using certain given design parameters of the facility as inputs. TBEAM uses the method of statistical sampling (Monte Carlo) to solve the space, time and energy dependent neutron transport equation relating to the conceptual design described by the user-supplied input parameters. The code traces the individual source neutrons as they propagate throughout the shield-collimator structure of the unit, and it keeps track of each interaction by type, position and energy. In its present version, TBEAM is applicable to homogeneous and laminated shields of spherical geometry, to collimator apertures of conical shape, and to neutrons emitted by point sources or such plate sources as are used in neutron generators of various types. TBEAM-generated results comparing the performance of point or plate sources in otherwise identical shield-collimator configurations are presented in numerical form. (H.K.)
Activation method for measuring the neutron spectra parameters. Computer software
International Nuclear Information System (INIS)
Efimov, B.V.; Ionov, V.S.; Konyaev, S.I.; Marin, S.V.
2005-01-01
The description of mathematical statement of a task for definition the spectral characteristics of neutron fields with use developed in RRC KI unified activation detectors (UKD) is resulted. The method of processing of results offered by authors activation measurements and calculation of the parameters used for an estimation of the neutron spectra characteristics is discussed. Features of processing of the experimental data received at measurements of activation with using UKD are considered. Activation detectors UKD contain a little bit specially the picked up isotopes giving at irradiation peaks scale of activity in the common spectrum scale of activity. Computing processing of results of the measurements is applied on definition of spectrum parameters for nuclear reactor installations with thermal and close to such power spectrum of neutrons. The example of the data processing, the measurements received at carrying out at RRC KI research reactor F-1 is resulted [ru
Styron, Jedediah D.
The focus of this work is the characterization of a typical neutron time-of-flight (NTOF) detector that is fielded on inertial confinement fusion (ICF) experiments conducted at the Z-experimental facility with emphasis on the Magnetized Liner Fusion (MagLIF) concept. An NTOF detector consisting of EJ-228 scintillator and two independent photomultiplier tubes (PMTs), a Hamamatsu-mod 5 and Photek-PMT240, has been characterized in terms of the absolute time and energy response. The characterization was done by measuring single, neutron-induced events in the scintillator by measuring the alpha particle and neutron produced from the D-T reaction in kinematic coincidence. The results of these experiments provided the time dependent instrument response function and the detector sensitivity as a function of applied voltage covering the entire dynamic range of the detector. Historically, impulse response functions have been measured using various photon sources as surrogates for a neutron source. Thus, this measurement using a single hit neutron source results in the most accurate measured response function, which will improve the accuracy of impulse response corrections to the NTOF signals. While this detector has not yet been fielded on any MagLIF experiments, the development of a predictive capability was desired for transferring the measured detector response from the calibration geometry to the more complex Z geometry. As a proof-of-principle, a detailed model of the Z-machine was developed in MCNP6 to correct for geometry issues when transferring the calibration results from a light lab setting to the Z-environment. Representative values for the instrument response function and the sensitivity for the current detectors fielded on MagLIF experiments were convolved with the modeled results. These results were compared with data collected on three previous MagLIF experiments. The comparison shows the model results can be used to constrain three parameters that are
International Nuclear Information System (INIS)
Gallmeier, F.X.; Glasgow, D.C.; Jerde, E.A.; Johnson, J.O.; Yugo, J.J.
1999-01-01
The Spallation Neutron Source (SNS) will provide an intense source of low-energy neutrons for experimental use. The low-energy neutrons are produced by the interaction of a high-energy (1.0 GeV) proton beam on a mercury (Hg) target and slowed down in liquid hydrogen or light water moderators. Computer codes and computational techniques are being benchmarked against relevant experimental data to validate and verify the tools being used to predict the performance of the SNS. The LAHET Code System (LCS), which includes LAHET, HTAPE ad HMCNP (a modified version of MCNP version 3b), have been applied to the analysis of experiments that were conducted in the Alternating Gradient Synchrotron (AGS) facility at Brookhaven National Laboratory (BNL). In the AGS experiments, foils of various materials were placed around a mercury-filled stainless steel cylinder, which was bombarded with protons at 1.6 GeV. Neutrons created in the mercury target, activated the foils. Activities of the relevant isotopes were accurately measured and compared with calculated predictions. Measurements at BNL were provided in part by collaborating scientists from JAERI as part of the AGS Spallation Target Experiment (ASTE) collaboration. To date, calculations have shown good agreement with measurements
Computational Dosimetry and Treatment Planning Considerations for Neutron Capture Therapy
International Nuclear Information System (INIS)
Nigg, David Waler
2003-01-01
Specialized treatment planning software systems are generally required for neutron capture therapy (NCT) research and clinical applications. The standard simplifying approximations that work well for treatment planning computations in the case of many other modalities are usually not appropriate for application to neutron transport. One generally must obtain an explicit three-dimensional numerical solution of the governing transport equation, with energy-dependent neutron scattering completely taken into account. Treatment planning systems that have been successfully introduced for NCT applications over the past 15 years rely on the Monte Carlo stochastic simulation method for the necessary computations, primarily because of the geometric complexity of human anatomy. However, historically, there has also been interest in the application of deterministic methods, and there have been some practical developments in this area. Most recently, interest has turned toward the creation of treatment planning software that is not limited to any specific therapy modality, with NCT as only one of several applications. A key issue with NCT treatment planning has to do with boron quantification, and whether improved information concerning the spatial biodistribution of boron can be effectively used to improve the treatment planning process. Validation and benchmarking of computations for NCT are also of current developmental interest. Various institutions have their own procedures, but standard validation models are not yet in wide use
Neutronic computational modeling of the ASTRA critical facility using MCNPX
International Nuclear Information System (INIS)
Rodriguez, L. P.; Garcia, C. R.; Milian, D.; Milian, E. E.; Brayner, C.
2015-01-01
The Pebble Bed Very High Temperature Reactor is considered as a prominent candidate among Generation IV nuclear energy systems. Nevertheless the Pebble Bed Very High Temperature Reactor faces an important challenge due to the insufficient validation of computer codes currently available for use in its design and safety analysis. In this paper a detailed IAEA computational benchmark announced by IAEA-TECDOC-1694 in the framework of the Coordinated Research Project 'Evaluation of High Temperature Gas Cooled Reactor (HTGR) Performance' was solved in support of the Generation IV computer codes validation effort using MCNPX ver. 2.6e computational code. In the IAEA-TECDOC-1694 were summarized a set of four calculational benchmark problems performed at the ASTRA critical facility. Benchmark problems include criticality experiments, control rod worth measurements and reactivity measurements. The ASTRA Critical Facility at the Kurchatov Institute in Moscow was used to simulate the neutronic behavior of nuclear pebble bed reactors. (Author)
Parallel computing for homogeneous diffusion and transport equations in neutronics
International Nuclear Information System (INIS)
Pinchedez, K.
1999-06-01
Parallel computing meets the ever-increasing requirements for neutronic computer code speed and accuracy. In this work, two different approaches have been considered. We first parallelized the sequential algorithm used by the neutronics code CRONOS developed at the French Atomic Energy Commission. The algorithm computes the dominant eigenvalue associated with PN simplified transport equations by a mixed finite element method. Several parallel algorithms have been developed on distributed memory machines. The performances of the parallel algorithms have been studied experimentally by implementation on a T3D Cray and theoretically by complexity models. A comparison of various parallel algorithms has confirmed the chosen implementations. We next applied a domain sub-division technique to the two-group diffusion Eigen problem. In the modal synthesis-based method, the global spectrum is determined from the partial spectra associated with sub-domains. Then the Eigen problem is expanded on a family composed, on the one hand, from eigenfunctions associated with the sub-domains and, on the other hand, from functions corresponding to the contribution from the interface between the sub-domains. For a 2-D homogeneous core, this modal method has been validated and its accuracy has been measured. (author)
Energy Technology Data Exchange (ETDEWEB)
Proskuryakov, K.N.; Bogomazov, D.N.; Poliakov, N. [Moscow Power Engineering Institute (Technical University), Moscow (Russian Federation)
2007-07-01
The new special module to neutron-physic and thermal-hydraulic computer codes for coolant acoustical characteristics calculation is worked out. The Russian computer code Rainbow has been selected for joint use with a developed module. This code system provides the possibility of EFOCP (Eigen Frequencies of Oscillations of the Coolant Pressure) calculations in any coolant acoustical elements of primary circuits of NPP. EFOCP values have been calculated for transient and for stationary operating. The calculated results for nominal operating were compared with results of measured EFOCP. For example, this comparison was provided for the system: 'pressurizer + surge line' of a WWER-1000 reactor. The calculated result 0.58 Hz practically coincides with the result of measurement (0.6 Hz). The EFOCP variations in transients are also shown. The presented results are intended to be useful for NPP vibration-acoustical certification. There are no serious difficulties for using this module with other computer codes.
International Nuclear Information System (INIS)
Proskuryakov, K.N.; Bogomazov, D.N.; Poliakov, N.
2007-01-01
The new special module to neutron-physic and thermal-hydraulic computer codes for coolant acoustical characteristics calculation is worked out. The Russian computer code Rainbow has been selected for joint use with a developed module. This code system provides the possibility of EFOCP (Eigen Frequencies of Oscillations of the Coolant Pressure) calculations in any coolant acoustical elements of primary circuits of NPP. EFOCP values have been calculated for transient and for stationary operating. The calculated results for nominal operating were compared with results of measured EFOCP. For example, this comparison was provided for the system: 'pressurizer + surge line' of a WWER-1000 reactor. The calculated result 0.58 Hz practically coincides with the result of measurement (0.6 Hz). The EFOCP variations in transients are also shown. The presented results are intended to be useful for NPP vibration-acoustical certification. There are no serious difficulties for using this module with other computer codes
International Nuclear Information System (INIS)
Panteleev, Ts.Ts.; Penchev, O.I.; Trifonov, A.I.; Troshev, T.M.; Christov, V.I.
1986-01-01
Neutron data are widely applied in nuclei physics and into practice as well. Data obtained by means of different measurement methods are of interest for increasing the accuracy and reliability of the recommended values for the cross sections of neutron interactions, with substance. The activation analysis method gives a possibility to obtain data about cross section interactions of 14 MeV neutrons with the nuclei σ (n,2n), σ( n,p), σ (n,pn), σ (n,α), etc. A serious shortcoming of this measuring method is the necessity of applying express methods of analysis of induced activities - restrictions connected with the life-times of the reaction products. It is also necessary to comply with the requirements for high accuracy in the data about the decay schemes and the absolute intensities of the γ-transitions in the investigated nuclei. The investigations directly measuring the output of the reaction, products from the targets, placed into the neutron beam, do not possess the shortcomings of the activation method but require serious demands toward the detecting apparatuses (ionization chambers, semiconducting and scintillation detectors, proportional counters, etc.). These demands are connected with the heavy background conditions of work at the beams for measurements of whatever partial cross sections. During the experimental measurements of the reactions by neutron emission for registration, it is necessary to slow them down to thermal energies, since only in this energy interval there exist sufficiently effective without threshold detectors. We have elaborated the experimental set-up allowing to measure the neutron multiplicity in an interaction. In the present work we have also used it for a relative measurement the the reaction cross section σ (n,2n) for Pe and Pb nuclei in their natural isotope mixtures. As it is known, this reaction has an important application for the blanket materials of thermonuclear reactors and for tritium fuel regeneration problem. The
Computational models for probabilistic neutronic calculation in TADSEA
International Nuclear Information System (INIS)
Garcia, Jesus A.R.; Curbelo, Jesus P.; Hernandez, Carlos R.G.; Oliva, Amaury M.; Lira, Carlos A.B.O.
2013-01-01
The Very High Temperature Reactor is one of the main candidates for the next generation of nuclear power plants. In pebble bed reactors, the fuel is contained within graphite pebbles in the form of TRISO particles, which form a randomly packed bed inside a graphite-walled cylindrical cavity. In previous studies, the conceptual design of a Transmutation Advanced Device for Sustainable Energy Applications (TADSEA) has been made. The TADSEA is a pebble-bed ADS cooled by helium and moderated by graphite. In order to simulate the TADSEA correctly, the double heterogeneity of the system must be considered. It consists on randomly located pebbles into the core and randomly located TRISO particles into the fuel pebbles. These features are often neglected due to the difficulty to model with MCNP code. The main reason is that there is a limited number of cells and surfaces to be defined. In this paper a computational tool, which allows to get a new geometrical model for fuel pebble to neutronic calculation with MCNPX, was presented. The heterogeneity of system is considered, and also the randomly located TRISO particles inside the pebble. There are also compared several neutronic computational models for TADSEA's fuel pebbles in order to study heterogeneity effects. On the other hand the boundary effect given by the intersection between the pebble surface and the TRISO particles could be significative in the multiplicative properties. A model to study this e ect is also presented. (author)
Complex of two-dimensional multigroup programs for neutron-physical computations of nuclear reactor
International Nuclear Information System (INIS)
Karpov, V.A.; Protsenko, A.N.
1975-01-01
Briefly stated mathematical aspects of the two-dimensional multigroup method of neutron-physical computation of nuclear reactor. Problems of algorithmization and BESM-6 computer realisation of multigroup diffuse approximations in hexagonal and rectangular calculated lattices are analysed. The results of computation of fast critical assembly having complicated composition of the core are given. The estimation of computation accuracy of criticality, neutron fields distribution and efficiency of absorbing rods by means of computer programs developed is done. (author)
Online In-Core Thermal Neutron Flux Measurement for the Validation of Computational Methods
International Nuclear Information System (INIS)
Mohamad Hairie Rabir; Muhammad Rawi Mohamed Zin; Yahya Ismail
2016-01-01
In order to verify and validate the computational methods for neutron flux calculation in RTP calculations, a series of thermal neutron flux measurement has been performed. The Self Powered Neutron Detector (SPND) was used to measure thermal neutron flux to verify the calculated neutron flux distribution in the TRIGA reactor. Measurements results obtained online for different power level of the reactor. The experimental results were compared to the calculations performed with Monte Carlo code MCNP using detailed geometrical model of the reactor. The calculated and measured thermal neutron flux in the core are in very good agreement indicating that the material and geometrical properties of the reactor core are modelled well. In conclusion one can state that our computational model describes very well the neutron flux distribution in the reactor core. Since the computational model properly describes the reactor core it can be used for calculations of reactor core parameters and for optimization of RTP utilization. (author)
A computer code for calculating neutron cross-sections from resonance parameter data
International Nuclear Information System (INIS)
Mill, A.J.
1979-08-01
A computer code, XSEC, has been written which calculates neutron cross-sections from resonance data. Although the program was originally written in order to identify neutron 'windows' in enriched nuclides, it may be used to evaluate the total neutron cross-section of any medium mass nuclide at intermediate energies. XSEC has proved very useful in identifying suitable nuclides for use as neutron filters at intermediate energies. (author)
Steyerl, A.; Malik, S. S.; Desai, A. M.; Kaufman, C.
2009-01-01
We review the diffuse scattering and the loss coefficient in ultracold neutron reflection from slightly rough surfaces, report a surprising reduction in loss coefficient due to roughness, and discuss the possibility of transition from quantum treatment to ray optics. The results are used in a computer simulation of neutron storage in a recent neutron lifetime experiment that re-ported a large discrepancy of neutron lifetime with the current particle data value. Our partial re-analysis suggest...
Parallel computing solution of Boltzmann neutron transport equation
International Nuclear Information System (INIS)
Ansah-Narh, T.
2010-01-01
The focus of the research was on developing parallel computing algorithm for solving Eigen-values of the Boltzmam Neutron Transport Equation (BNTE) in a slab geometry using multi-grid approach. In response to the problem of slow execution of serial computing when solving large problems, such as BNTE, the study was focused on the design of parallel computing systems which was an evolution of serial computing that used multiple processing elements simultaneously to solve complex physical and mathematical problems. Finite element method (FEM) was used for the spatial discretization scheme, while angular discretization was accomplished by expanding the angular dependence in terms of Legendre polynomials. The eigenvalues representing the multiplication factors in the BNTE were determined by the power method. MATLAB Compiler Version 4.1 (R2009a) was used to compile the MATLAB codes of BNTE. The implemented parallel algorithms were enabled with matlabpool, a Parallel Computing Toolbox function. The option UseParallel was set to 'always' and the default value of the option was 'never'. When those conditions held, the solvers computed estimated gradients in parallel. The parallel computing system was used to handle all the bottlenecks in the matrix generated from the finite element scheme and each domain of the power method generated. The parallel algorithm was implemented on a Symmetric Multi Processor (SMP) cluster machine, which had Intel 32 bit quad-core x 86 processors. Convergence rates and timings for the algorithm on the SMP cluster machine were obtained. Numerical experiments indicated the designed parallel algorithm could reach perfect speedup and had good stability and scalability. (au)
Neutron physics computation of CERCA fuel elements for Maria Reactor
International Nuclear Information System (INIS)
Andrzejewski, K.J.; Kulikowska, T.; Marcinkowska, Z.
2008-01-01
Neutron physics parameters of CERCA design fuel elements were calculated in the framework of the RERTR (Reduced Enrichment for Research and Test Reactors) program for Maria reactor. The analysis comprises burnup of experimental CERCA design fuel elements for 4 cycles in Maria Reactor To predict the behavior of the mixed core the differences between the CERCA fuel (485 g U-235 as U 3 Si 2 , 5 fuel tubes, low enrichment 19.75 % - LEU) and the presently used MR-6 fuel (430 g as UO 2 , 6 fuel tubes, high enrichment 36 % - HEU) had to be taken into account. The basic tool used in neutron-physics analysis of Maria reactor is program REBUS using in its dedicated libraries of effective microscopic cross sections. The cross sections were prepared using WIMS-ANL code, taking into account the actual structure, temperature and material composition of the fuel elements required preparation of new libraries.The problem is described in the first part of the present paper. In the second part the applicability of the new library is shown on the basis of the fuel core computational analysis. (author)
Energy Technology Data Exchange (ETDEWEB)
Stuart R. Slattery; David W. Nigg; John D. Brockman; M. Frederick Hawthorne
2010-05-01
Parameter studies, design calculations and initial neutronic performance measurements have been completed for a new thermal neutron beamline to be used for neutron capture therapy cell and small-animal radiobiology studies at the University of Missouri Research Reactor. The beamline features the use of single-crystal silicon and bismuth sections for neutron filtering and for reduction of incident gamma radiation. The computational models used for the final beam design and performance evaluation are based on coupled discrete-ordinates and Monte Carlo techniques that permit detailed modeling of the neutron transmission properties of the filtering crystals with very few approximations. This is essential for detailed dosimetric studies required for the anticipated research program.
Computer dosimetry for flattened and wedged fast-neutron beams
International Nuclear Information System (INIS)
Hogstrom, K.R.; Smith, A.R.; Almond, P.R.; Otte, V.A.; Smathers, J.B.
1976-01-01
Beam flattening by the use of polyethylene filters has been developed for the 50-MeV d→Be fast-neutron therapy beam at the Texas AandM Variable-Energy Cyclotron (TAMVEC) as a result of the need for a more uniform dose distribution at depth within the patient. A computer algorithm has been developed that allows the use of a modified decrement line method to calculate dose distributions; standard decrement line methods do not apply because of off-axis peaking. The dose distributions for measured flattened beams are transformed into distributions that are physically equivalent to an unflattened distribution. In the transformed space, standard decrement line theory yields a distribution for any field size which, by applying the inverse transformation, generates the flattened dose distribution, including the off-axis peaking. A semiempirical model has been constructed that allows the calculation of dose distributions for wedged beams from open-beam data
Neutron visual sensing techniques making good use of computer science
International Nuclear Information System (INIS)
Kureta, Masatoshi
2009-01-01
Neutron visual sensing technique is one of the nondestructive visualization and image-sensing techniques. In this article, some advanced neutron visual sensing techniques are introduced. The most up-to-date high-speed neutron radiography, neutron 3D CT, high-speed scanning neutron 3D/4D CT and multi-beam neutron 4D CT techniques are included with some fundamental application results. Oil flow in a car engine was visualized by high-speed neutron radiography technique to make clear the unknown phenomena. 4D visualization of pained sand in the sand glass was reported as the demonstration of the high-speed scanning neutron 4D CT technique. The purposes of the development of these techniques are to make clear the unknown phenomena and to measure the void fraction, velocity etc. with high-speed or 3D/4D for many industrial applications. (author)
CINDA 83 (1977-1983). The index to literature and computer files on microscopic neutron data
International Nuclear Information System (INIS)
1983-01-01
CINDA, the Computer Index of Neutron Data, contains bibliographical references to measurements, calculations, reviews and evaluations of neutron cross-sections and other microscopic neutron data; it includes also index references to computer libraries of numerical neutron data exchanged between four regional neutron data centres. The present issue, CINDA 83, is an index to the literature on neutron data published after 1976. The basic volume, CINDA-A, together with the present issue, contains the full CINDA file as of 1 April 1983. A supplement to CINDA 83 is foreseen for fall 1983. Next year's issue, which is envisaged to be published in June 1984, will again cover all relevant literature that has appeared after 1976
A hybrid source-driven method to compute fast neutron fluence in reactor pressure vessel - 017
International Nuclear Information System (INIS)
Ren-Tai, Chiang
2010-01-01
A hybrid source-driven method is developed to compute fast neutron fluence with neutron energy greater than 1 MeV in nuclear reactor pressure vessel (RPV). The method determines neutron flux by solving a steady-state neutron transport equation with hybrid neutron sources composed of peripheral fixed fission neutron sources and interior chain-reacted fission neutron sources. The relative rod-by-rod power distribution of the peripheral assemblies in a nuclear reactor obtained from reactor core depletion calculations and subsequent rod-by-rod power reconstruction is employed as the relative rod-by-rod fixed fission neutron source distribution. All fissionable nuclides other than U-238 (such as U-234, U-235, U-236, Pu-239 etc) are replaced with U-238 to avoid counting the fission contribution twice and to preserve fast neutron attenuation for heavy nuclides in the peripheral assemblies. An example is provided to show the feasibility of the method. Since the interior fuels only have a marginal impact on RPV fluence results due to rapid attenuation of interior fast fission neutrons, a generic set or one of several generic sets of interior fuels can be used as the driver and only the neutron sources in the peripheral assemblies will be changed in subsequent hybrid source-driven fluence calculations. Consequently, this hybrid source-driven method can simplify and reduce cost for fast neutron fluence computations. This newly developed hybrid source-driven method should be a useful and simplified tool for computing fast neutron fluence at selected locations of interest in RPV of contemporary nuclear power reactors. (authors)
Development Of The Computer Code For Comparative Neutron Activation Analysis
International Nuclear Information System (INIS)
Purwadi, Mohammad Dhandhang
2001-01-01
The qualitative and quantitative chemical analysis with Neutron Activation Analysis (NAA) is an importance utilization of a nuclear research reactor, and this should be accelerated and promoted in application and its development to raise the utilization of the reactor. The application of Comparative NAA technique in GA Siwabessy Multi Purpose Reactor (RSG-GAS) needs special (not commercially available yet) soft wares for analyzing the spectrum of multiple elements in the analysis at once. The application carried out using a single spectrum software analyzer, and comparing each result manually. This method really degrades the quality of the analysis significantly. To solve the problem, a computer code was designed and developed for comparative NAA. Spectrum analysis in the code is carried out using a non-linear fitting method. Before the spectrum analyzed, it was passed to the numerical filter which improves the signal to noise ratio to do the deconvolution operation. The software was developed using the G language and named as PASAN-K The testing result of the developed software was benchmark with the IAEA spectrum and well operated with less than 10 % deviation
International Nuclear Information System (INIS)
Bareiss, E.H.
1975-01-01
The objectives of the research remain the same as outlined in the original proposal. They are in short as follows: Develop mathematically and computationally founded criteria for the design of highly efficient and reliable multi-dimensional neutron transport codes to solve a variety of neutron migration and radiation problems and analyze existing and new methods for performance. (U.S.)
International Nuclear Information System (INIS)
Bareiss, E.H.
1977-08-01
The objectives of this research are to develop mathematically and computationally founded criteria for the design of highly efficient and reliable multidimensional neutron transport codes to solve a variety of neutron migration and radiation problems, and to analyze existing and new methods for performance
International Nuclear Information System (INIS)
Steyerl, A.; Malik, S. S.; Desai, A. M.; Kaufman, C.
2010-01-01
We review the diffuse scattering and the loss coefficient in ultracold neutron reflection from slightly rough surfaces, report a surprising reduction in loss coefficient due to roughness, and discuss the possibility of transition from quantum treatment to ray optics. The results are used in a computer simulation of neutron storage in a recent neutron lifetime experiment that reported a large discrepancy of neutron lifetime with the current particle data value. Our partial reanalysis suggests the possibility of systematic effects that were not included in this publication.
On efficiently computing multigroup multi-layer neutron reflection and transmission conditions
International Nuclear Information System (INIS)
Abreu, Marcos P. de
2007-01-01
In this article, we present an algorithm for efficient computation of multigroup discrete ordinates neutron reflection and transmission conditions, which replace a multi-layered boundary region in neutron multiplication eigenvalue computations with no spatial truncation error. In contrast to the independent layer-by-layer algorithm considered thus far in our computations, the algorithm here is based on an inductive approach developed by the present author for deriving neutron reflection and transmission conditions for a nonactive boundary region with an arbitrary number of arbitrarily thick layers. With this new algorithm, we were able to increase significantly the computational efficiency of our spectral diamond-spectral Green's function method for solving multigroup neutron multiplication eigenvalue problems with multi-layered boundary regions. We provide comparative results for a two-group reactor core model to illustrate the increased efficiency of our spectral method, and we conclude this article with a number of general remarks. (author)
Computer-controlled neutron time-of-flight spectrometer. Part II
International Nuclear Information System (INIS)
Merriman, S.H.
1979-12-01
A time-of-flight spectrometer for neutron inelastic scattering research has been interfaced to a PDP-15/30 computer. The computer is used for experimental data acquisition and analysis and for apparatus control. This report was prepared to summarize the functions of the computer and to act as a users' guide to the software system
Energy Technology Data Exchange (ETDEWEB)
Oyamatsu, Kazuhiro [Nagoya Univ. (Japan)
1998-03-01
Application programs for personal computers are developed to calculate the decay heat power and delayed neutron activity from fission products. The main programs can be used in any computers from personal computers to main frames because their sources are written in Fortran. These programs have user friendly interfaces to be used easily not only for research activities but also for educational purposes. (author)
Multiple channel programmable coincidence counter
Arnone, Gaetano J.
1990-01-01
A programmable digital coincidence counter having multiple channels and featuring minimal dead time. Neutron detectors supply electrical pulses to a synchronizing circuit which in turn inputs derandomized pulses to an adding circuit. A random access memory circuit connected as a programmable length shift register receives and shifts the sum of the pulses, and outputs to a serializer. A counter is input by the adding circuit and downcounted by the seralizer, one pulse at a time. The decoded contents of the counter after each decrement is output to scalers.
International Nuclear Information System (INIS)
Zimny, M.
2001-01-01
Positron emission tomography with 18 F-fluoro-deoxyglucose (FDG PET) is a promising imaging tool for detecting and staging of primary or recurrent head and neck cancer. The aim of this study was to evaluate a dual-head gamma camera modified for coincidence detection (KGK-PET) in comparison to computed tomography (CT) and dedicated PET (dPET). 50 patients with known or suspected primary or recurrent head and neck cancer were enrolled. 32 patients underwent KGK-PET and dPET using a one-day protocol. The sensitivity for the detection of primary/ recurrent head and neck cancer for KGK-PET and CT was 80% and 54%, respectively, specificity was 73% and 82%, respectively. The sensitivity and specificity for the detection of lymph node metastases based on neck sides with KGK-PET was 71% (CT: 65%) and 88% (CT: 89%) respectively. In comparison to dPET, KGK-PET revealed concordant results in 32/32 patients with respect to primary tumor/recurrent disease and in 55/60 evaluated neck sides. All involved neck sides that were missed by KGK-PET were also negative with dPET. These results indicate that in patients with head and neck cancer KGK-PET reveals information, that are similar to dPET and complementary to CT. (orig.) [de
Some neutronics and thermal-hydraulics codes for reactor analysis using personal computers
International Nuclear Information System (INIS)
Woodruff, W.L.
1990-01-01
Some neutronics and thermal-hydraulics codes formerly available only for main frame computers may now be run on personal computers. Brief descriptions of the codes are provided. Running times for some of the codes are compared for an assortment of personal and main frame computers. With some limitations in detail, personal computer versions of the codes can be used to solve many problems of interest in reactor analyses at very modest costs. 11 refs., 4 tabs
Energy Technology Data Exchange (ETDEWEB)
Grebennikov, A.N.; Zhitnik, A.K.; Zvenigorodskaya, O.A. [and others
1995-12-31
In conformity with the protocol of the Workshop under Contract {open_quotes}Assessment of RBMK reactor safety using modern Western Codes{close_quotes} VNIIEF performed a neutronics computation series to compare western and VNIIEF codes and assess whether VNIIEF codes are suitable for RBMK type reactor safety assessment computation. The work was carried out in close collaboration with M.I. Rozhdestvensky and L.M. Podlazov, NIKIET employees. The effort involved: (1) cell computations with the WIMS, EKRAN codes (improved modification of the LOMA code) and the S-90 code (VNIIEF Monte Carlo). Cell, polycell, burnup computation; (2) 3D computation of static states with the KORAT-3D and NEU codes and comparison with results of computation with the NESTLE code (USA). The computations were performed in the geometry and using the neutron constants presented by the American party; (3) 3D computation of neutron kinetics with the KORAT-3D and NEU codes. These computations were performed in two formulations, both being developed in collaboration with NIKIET. Formulation of the first problem maximally possibly agrees with one of NESTLE problems and imitates gas bubble travel through a core. The second problem is a model of the RBMK as a whole with imitation of control and protection system controls (CPS) movement in a core.
International Nuclear Information System (INIS)
McGill, B.L.; Roussin, R.W.; Trubey, D.K.; Maskewitz, B.F.
1980-01-01
The Radiation Shielding Information Center (RSIC), established in 1962 to collect, package, analyze, and disseminate information, computer codes, and data in the area of radiation transport related to fission, is now being utilized to support fusion neutronics technology. The major activities include: (1) answering technical inquiries on radiation transport problems, (2) collecting, packaging, testing, and disseminating computing technology and data libraries, and (3) reviewing literature and operating a computer-based information retrieval system containing material pertinent to radiation transport analysis. The computer codes emphasize methods for solving the Boltzmann equation such as the discrete ordinates and Monte Carlo techniques, both of which are widely used in fusion neutronics. The data packages include multigroup coupled neutron-gamma-ray cross sections and kerma coefficients, other nuclear data, and radiation transport benchmark problem results
Computed tomography with thermal neutrons and gaseous position sensitive detector
International Nuclear Information System (INIS)
Souza, Maria Ines Silvani
2001-12-01
A third generation tomographic system using a parallel thermal neutron beam and gaseous position sensitive detector has been developed along three discrete phases. At the first one, X-ray tomographic images of several objects, using a position sensitive detector designed and constructed for this purpose have been obtained. The second phase involved the conversion of that detector for thermal neutron detection, by using materials capable to convert neutrons into detectable charged particles, testing afterwards its performance in a tomographic system by evaluation the quality of the image arising from several test-objects containing materials applicable in the engineering field. High enriched 3 He, replacing the argon-methane otherwise used as filling gas for the X-ray detection, as well as, a gadolinium foil, have been utilized as converters. Besides the pure enriched 3 He, its mixture with argon-methane and later on with propane, have been also tested, in order to evaluate the detector efficiency and resolution. After each gas change, the overall performance of the tomographic system using the modified detector, has been analyzed through measurements of the related parameters. This was done by analyzing the images produced by test-objects containing several materials having well known attenuation coefficients for both thermal neutrons and X-rays. In order to compare the performance of the position sensitive detector as modified to detect thermal neutrons, with that of a conventional BF 3 detector, additional tomographs have been conducted using the last one. The results have been compared in terms of advantages, handicaps and complementary aspects for different kinds of radiation and materials. (author)
Fusion spectrum neutron source computation in "6LiD convertor for HFETR
International Nuclear Information System (INIS)
Sun Shouhua; Hu Yifei; Ye Bin
2014-01-01
A computation model of 14 MeV neutron from the "6LiD convertor has been established, the 14 MeV neutron sources and flux in the irradiation samples from the "6LiD convertor and the core have been computed separately, the neutron spectrum in the irradiation samples have been computed, too. The results show that the neutron sources that over 13 MeV account for 1 MeV above in the "6LiD convertor is 25.7%, 24.6% respectively, 14 MeV neutron sources get 4.31 × 10"1"3 n_T·s"-"1, 3.34 × 10"1"3 n_T·s"-"1, 14 MeV neutron flux get 2.66 × 10"1"0 n_T·cm"-"2·s"-"1, 3.53 × 10"1"0 n_T·cm"-"2·s"-"1, as He and H_2O charged in the irradiation capsule. (authors)
Deconvolution of neutron scattering data: a new computational approach
International Nuclear Information System (INIS)
Weese, J.; Hendricks, J.; Zorn, R.; Honerkamp, J.; Richter, D.
1996-01-01
In this paper we address the problem of reconstructing the scattering function S Q (E) from neutron spectroscopy data which represent a convolution of the former function with an instrument dependent resolution function. It is well known that this kind of deconvolution is an ill-posed problem. Therefore, we apply the Tikhonov regularization technique to get an estimate of S Q (E) from the data. Special features of the neutron spectroscopy data require modifications of the basic procedure, the most important one being a transformation to a non-linear problem. The method is tested by deconvolution of actual data from the IN6 time-of-flight spectrometer (resolution: 90 μeV) and simulated data. As a result the deconvolution is shown to be feasible down to an energy transfer of ∼100 μeV for this instrument without recognizable error and down to ∼20 μeV with 10% relative error. (orig.)
Computer Program for Inelastic Neutron Scattering by an Anharmonic Crystal
International Nuclear Information System (INIS)
Bohlin, L.; Ebbsjoe, I.; Hoegberg, T.
1969-02-01
A description is given of the program SAW (Shift and Width), which calculates the energy-dependent shift and width of the intensity peaks obtained for thermal neutrons scattered inelastically by an anharmonic crystal. The program has been coded in FORTRAN IV and may be applied to every solid with a monatomic face-centered cubic lattice where the intermolecular interactions can be described by a centro-symmetrical potential. Interactions beyond third neighbours are neglected
Computer Program for Inelastic Neutron Scattering by an Anharmonic Crystal
Energy Technology Data Exchange (ETDEWEB)
Bohlin, L; Ebbsjoe, I; Hoegberg, T
1969-02-15
A description is given of the program SAW (Shift and Width), which calculates the energy-dependent shift and width of the intensity peaks obtained for thermal neutrons scattered inelastically by an anharmonic crystal. The program has been coded in FORTRAN IV and may be applied to every solid with a monatomic face-centered cubic lattice where the intermolecular interactions can be described by a centro-symmetrical potential. Interactions beyond third neighbours are neglected.
The definition and computation of average neutron lifetimes
International Nuclear Information System (INIS)
Henry, A.F.
1983-01-01
A precise physical definition is offered for a class of average lifetimes for neutrons in an assembly of materials, either multiplying or not, or if the former, critical or not. A compact theoretical expression for the general member of this class is derived in terms of solutions to the transport equation. Three specific definitions are considered. Particular exact expressions for these are derived and reduced to simple algebraic formulas for one-group and two-group homogeneous bare-core models
International Nuclear Information System (INIS)
Bareiss, E.H.
1976-05-01
The objectives of the work are to develop mathematically and computationally founded for the design of highly efficient and reliable multidimensional neutron transport codes to solve a variety of neutron migration and radiation problems, and to analyze existing and new methods for performance. As new analytical insights are gained, new numerical methods are developed and tested. Significant results obtained include implementation of the integer-preserving Gaussian elimination method (two-step method) in a CDC 6400 computer code, modes analysis for one-dimensional transport solutions, and a new method for solving the 1-T transport equation. Some of the work dealt with the interface and corner problem in diffusion theory
Integrated coincidence circuits
International Nuclear Information System (INIS)
Borejko, V.F.; Grebenyuk, V.M.; Zinov, V.G.
1976-01-01
The description is given of two coincidence units employing integral circuits in the VISHNYA standard. The units are distinguished for the coincidence selection element which is essentially a combination of a tunnel diode and microcircuits. The output fast response of the units is at least 90 MHz in the mode of the output signal unshaped in duration and 50 MHz minimum in the mode of the output signal shaping. The resolution time of the units is dependent upon the duration of input signals
Neutron shielding point kernel integral calculation code for personal computer: PKN-pc
International Nuclear Information System (INIS)
Kotegawa, Hiroshi; Sakamoto, Yukio; Nakane, Yoshihiro; Tomita, Ken-ichi; Kurosawa, Naohiro.
1994-07-01
A personal computer version of PKN code, PKN-pc, has been developed to calculate neutron and secondary gamma-ray 1cm depth dose equivalents in water, ordinary concrete and iron for neutron source. Characteristics of PKN code are, to able to calculate dose equivalents in multi-layer three-dimensional system, which are described with two-dimensional surface, for monoenergetic neutron source from 0.01 to 14.9 MeV, 252 Cf fission and 241 Am-Be neutron source quick and easily. In addition to these features, the PKN-pc is possible to process interactive input and to get graphical system configuration and graphical results easily. (author)
AUS - the Australian modular scheme for reactor neutronics computations
International Nuclear Information System (INIS)
Robinson, G.S.
1975-12-01
A general description is given of the AUS modular scheme for reactor neutronics calculations. The scheme currently includes modules which provide the capacity for lattice calculations, 1D transport calculations, 1 and 2D diffusion calculations (with feedback-free kinetics), and burnup calculations. Details are provided of all system aspects of AUS, but individual modules are only outlined. A complete specification is given of that part of user input which controls the calculation sequence. The report also provides sufficient details of the supervisor program and of the interface data sets to enable additional modules to be incorporated in the scheme. (author)
Neutron Computed Tomography of Freeze/thaw Phenomena in Polymer Electrolyte Fuel Cells
Energy Technology Data Exchange (ETDEWEB)
Matthew M. Mech; Jack Brenizer; Kenan Unlu; A.K. Heller
2008-12-12
This report summarizes the final year's progress of the three-year NEER program. The overall objectives of this program were to 1) design and construct a sophisticated hight-resolution neutron computed tomography (NCT) facility, 2) develop novel and sophisticated liquid water and ice quantification analysis software for computed tomography, and 3) apply the advanced software and NCT capability to study liquid and ice distribution in polymer electrolyte fuel cells (PEFCs) under cold-start conditions. These objectives have been accomplished by the research team, enabling a new capability for advanced 3D image quantification with neutron imaging for fuel cell and other applications. The NCT water quantification methodology and software will greatly add to the capabilities of the neutron imaging community, and the quantified liquid water and ice distribution provided by its application to PEFCs will enhance understanding and guide design in the fuel cell community.
Utilizing of computational tools on the modelling of a simplified problem of neutron shielding
Energy Technology Data Exchange (ETDEWEB)
Lessa, Fabio da Silva Rangel; Platt, Gustavo Mendes; Alves Filho, Hermes [Universidade do Estado do Rio de Janeiro (UERJ), Nova Friburgo, RJ (Brazil). Inst. Politecnico]. E-mails: fsrlessa@gmail.com; gmplatt@iprj.uerj.br; halves@iprj.uerj.br
2007-07-01
In the current technology level, the investigation of several problems is studied through computational simulations whose results are in general satisfactory and much less expensive than the conventional forms of investigation (e.g., destructive tests, laboratory measures, etc.). Almost all of the modern scientific studies are executed using computational tools, as computers of superior capacity and their systems applications to make complex calculations, algorithmic iterations, etc. Besides the considerable economy in time and in space that the Computational Modelling provides, there is a financial economy to the scientists. The Computational Modelling is a modern methodology of investigation that asks for the theoretical study of the identified phenomena in the problem, a coherent mathematical representation of such phenomena, the generation of a numeric algorithmic system comprehensible for the computer, and finally the analysis of the acquired solution, or still getting use of pre-existent systems that facilitate the visualization of these results (editors of Cartesian graphs, for instance). In this work, was being intended to use many computational tools, implementation of numeric methods and a deterministic model in the study and analysis of a well known and simplified problem of nuclear engineering (the neutron transport), simulating a theoretical problem of neutron shielding with physical-material hypothetical parameters, of neutron flow in each space junction, programmed with Scilab version 4.0. (author)
Utilizing of computational tools on the modelling of a simplified problem of neutron shielding
International Nuclear Information System (INIS)
Lessa, Fabio da Silva Rangel; Platt, Gustavo Mendes; Alves Filho, Hermes
2007-01-01
In the current technology level, the investigation of several problems is studied through computational simulations whose results are in general satisfactory and much less expensive than the conventional forms of investigation (e.g., destructive tests, laboratory measures, etc.). Almost all of the modern scientific studies are executed using computational tools, as computers of superior capacity and their systems applications to make complex calculations, algorithmic iterations, etc. Besides the considerable economy in time and in space that the Computational Modelling provides, there is a financial economy to the scientists. The Computational Modelling is a modern methodology of investigation that asks for the theoretical study of the identified phenomena in the problem, a coherent mathematical representation of such phenomena, the generation of a numeric algorithmic system comprehensible for the computer, and finally the analysis of the acquired solution, or still getting use of pre-existent systems that facilitate the visualization of these results (editors of Cartesian graphs, for instance). In this work, was being intended to use many computational tools, implementation of numeric methods and a deterministic model in the study and analysis of a well known and simplified problem of nuclear engineering (the neutron transport), simulating a theoretical problem of neutron shielding with physical-material hypothetical parameters, of neutron flow in each space junction, programmed with Scilab version 4.0. (author)
PAD: a one-dimensional, coupled neutronic-thermodynamic-hydrodynamic computer code
International Nuclear Information System (INIS)
Peterson, D.M.; Stratton, W.R.; McLaughlin, T.P.
1976-12-01
Theoretical and numerical foundations, utilization guide, sample problems, and program listing and glossary are given for the PAD computer code which describes dynamic systems with interactive neutronics, thermodynamics, and hydrodynamics in one-dimensional spherical, cylindrical, and planar geometries. The code has been applied to prompt critical excursions in various fissioning systems (solution, metal, LMFBR, etc.) as well as to nonfissioning systems
HADES. A computer code for fast neutron cross section from the Optical Model
International Nuclear Information System (INIS)
Guasp, J.; Navarro, C.
1973-01-01
A FORTRAN V computer code for UNIVAC 1108/6 using a local Optical Model with spin-orbit interaction is described. The code calculates fast neutron cross sections, angular distribution, and Legendre moments for heavy and intermediate spherical nuclei. It allows for the possibility of automatic variation of potential parameters for experimental data fitting. (Author) 55 refs
Processing of evaluated neutron data files in ENDF format on personal computers
International Nuclear Information System (INIS)
Vertes, P.
1991-11-01
A computer code package - FDMXPC - has been developed for processing evaluated data files in ENDF format. The earlier version of this package is supplemented with modules performing calculations using Reich-Moore and Adler-Adler resonance parameters. The processing of evaluated neutron data files by personal computers requires special programming considerations outlined in this report. The scope of the FDMXPC program system is demonstrated by means of numerical examples. (author). 5 refs, 4 figs, 4 tabs
A computer-controlled CAMAC system for the operation of a neutron diffractometer
International Nuclear Information System (INIS)
Zwoll, K.; Mueller, K.D.; Will, G.
1976-01-01
The paper describes a computer-controlled four-circle diffractometer for the investigation of single crystals by neutron diffraction. The hardware is based on the internationally standardised CAMAC system. This makes the system described here independent of the type of computer used and also largely independent of the mechanical equipment used. The software is written in the interpretative language FOCAL which is easy to learn and ensures high flexibility in programming and thus also in the use of the diffractometer. (orig.) [de
International Nuclear Information System (INIS)
Vondy, D.R.; Fowler, T.B.; Cunningham, G.W.
1979-07-01
User input data requirements are presented for certain special processors in a nuclear reactor computation system. These processors generally read data in formatted form and generate binary interface data files. Some data processing is done to convert from the user oriented form to the interface file forms. The VENTURE diffusion theory neutronics code and other computation modules in this system use the interface data files which are generated
International Nuclear Information System (INIS)
Vondy, D.R.; Fowler, T.B.; Cunningham, G.W.
1976-11-01
This report presents user input data requirements for certain special processors in a nuclear reactor computation system. These processors generally read data in formatted form and generate binary interface data files. Some data processing is done to convert from the user-oriented form to the interface file forms. The VENTURE diffusion theory neutronics code and other computation modules in this system use the interface data files which are generated
Computer-controlled CAMAC system for the operation of a neutron diffractometer
Energy Technology Data Exchange (ETDEWEB)
Zwoll, K; Mueller, K D [Kernforschungsanlage Juelich G.m.b.H. (Germany, F.R.). Zentrallabor fuer Elektronik; Will, G [Bonn Univ. (Germany, F.R.). Mineralogisches Inst.
1976-10-01
The paper describes a computer-controlled four-circle diffractometer for the investigation of single crystals by neutron diffraction. The hardware is based on the internationally standardised CAMAC system. This makes the system described here independent of the type of computer used and also largely independent of the mechanical equipment used. The software is written in the interpretative language FOCAL which is easy to learn and ensures high flexibility in programming and thus also in the use of the diffractometer.
Kumada, H; Matsumura, A; Nakagawa, Y; Nose, T; Torii, Y; Uchiyama, J; Yamamoto, K; Yamamoto, T
2003-01-01
The Neutron Beam Facility at JRR-4 enables us to carry out boron neutron capture therapy with epithermal neutron beam. In order to make treatment plans for performing the epithermal neutron beam BNCT, it is necessary to estimate radiation doses in a patient's head in advance. The JAERI Computational Dosimetry System (JCDS), which can estimate distributions of radiation doses in a patient's head by simulating in order to support the treatment planning for epithermal neutron beam BNCT, was developed. JCDS is a software that creates a 3-dimentional head model of a patient by using CT and MRI images, and that generates a input data file automatically for calculation of neutron flux and gamma-ray dose distributions in the brain with the Monte Carlo code MCNP, and that displays these dose distributions on the head model for dosimetry by using the MCNP calculation results. JCDS has any advantages as follows; By using CT data and MRI data which are medical images, a detail three-dimensional model of patient's head is...
Computational features of the MELT-III neutronics, thermal-hydraulics computer code system
International Nuclear Information System (INIS)
Wilburn, N.P.; Waltar, A.E.
1976-01-01
A multichannel, thermal-hydraulics, neutronic accident analysis program for simulating fast reactor behavior from a hypothetical accident inception to the start of core disassembly or to reactor shutdown is described
Coincidence studies with antiprotons
Energy Technology Data Exchange (ETDEWEB)
McGovern, M; Walters, H R J [Department of Applied Mathematics and Theoretical Physics, Queen' s University, Belfast BT7 1NN (United Kingdom); Assafrao, D; Mohallem, J R [Laboratorio de Atomos e Moleculas Especiais, Departamento de Fisica, ICEx, Universidade Federal de Minas Gerais, P.O Box 702, 30123-970 Belo Horizonte, MG (Brazil); Whelan, Colm T, E-mail: mmcgovern06@qub.ac.u [Department of Physics, Old Dominion University, Norfolk, VA 23529-0116 (United States)
2010-02-01
We present a short overview of a new method for calculating fully differential cross sections that is able to describe any aspect of coincidence measurements involving heavy projectiles. The method is based upon impact parameter close coupling with pseudostates. Examples from antiproton impact ionization are shown.
Experiments using coincidence methods
International Nuclear Information System (INIS)
Anwar Dhani.
1978-01-01
Experiments on γ spectroscopy using the simple coincidence techniques, including investigation of angular distribution of γ radiation from annihilation process in decay of Na 22 , γ - γ angular correlation technique in decay of Co 60 , decay scheme study of Bi 207 and life time measurement of nuclear Pb 207 excited state have been carried out. (author)
International Nuclear Information System (INIS)
Agullo, F.
1960-01-01
A β - γ coincidence method for absolute counting is given. The fundamental principles are revised and the experimental part is detailed. The results from 1 98 Au irradiated in the JEN 1 Swimming pool reactor are given. The maximal accuracy is 1 per cent. (Author) 11 refs
New computational methodology for large 3D neutron transport problems
International Nuclear Information System (INIS)
Dahmani, M.; Roy, R.; Koclas, J.
2004-01-01
We present a new computational methodology, based on 3D characteristics method, dedicated to solve very large 3D problems without spatial homogenization. In order to eliminate the input/output problems occurring when solving these large problems, we set up a new computing scheme that requires more CPU resources than the usual one, based on sweeps over large tracking files. The huge capacity of storage needed in some problems and the related I/O queries needed by the characteristics solver are replaced by on-the-fly recalculation of tracks at each iteration step. Using this technique, large 3D problems are no longer I/O-bound, and distributed CPU resources can be efficiently used. (authors)
International Nuclear Information System (INIS)
Buckman, S.M.; Ius, D.
1996-01-01
This paper reports on the development of a digital coincidence-counting system which comprises a custom-built data acquisition card and associated PC software. The system has been designed to digitise the pulse-trains from two radiation detectors at a rate of 20 MSamples/s with 12-bit resolution. Through hardware compression of the data, the system can continuously record both individual pulse-shapes and the time intervals between pulses. Software-based circuits are used to process the stored pulse trains. These circuits are constructed simply by linking together icons representing various components such as coincidence mixers, time delays, single-channel analysers, deadtimes and scalers. This system enables a pair of pulse trains to be processed repeatedly using any number of different methods. Some preliminary results are presented in order to demonstrate the versatility and efficiency of this new method. (orig.)
Buckman, S. M.; Ius, D.
1996-02-01
This paper reports on the development of a digital coincidence-counting system which comprises a custom-built data acquisition card and associated PC software. The system has been designed to digitise the pulse-trains from two radiation detectors at a rate of 20 MSamples/s with 12-bit resolution. Through hardware compression of the data, the system can continuously record both individual pulse-shapes and the time intervals between pulses. Software-based circuits are used to process the stored pulse trains. These circuits are constructed simply by linking together icons representing various components such as coincidence mixers, time delays, single-channel analysers, deadtimes and scalers. This system enables a pair of pulse trains to be processed repeatedly using any number of different methods. Some preliminary results are presented in order to demonstrate the versatility and efficiency of this new method.
International Nuclear Information System (INIS)
Reginatto, M.; Goldhagen, P.
1998-06-01
The problem of analyzing data from a multisphere neutron spectrometer to infer the energy spectrum of the incident neutrons is discussed. The main features of the code MAXED, a computer program developed to apply the maximum entropy principle to the deconvolution (unfolding) of multisphere neutron spectrometer data, are described, and the use of the code is illustrated with an example. A user's guide for the code MAXED is included in an appendix. The code is available from the authors upon request
International Nuclear Information System (INIS)
Kirk, B.L.; Azmy, Y.Y.
1992-01-01
In this paper the one-group, steady-state neutron diffusion equation in two-dimensional Cartesian geometry is solved using the nodal integral method. The discrete variable equations comprise loosely coupled sets of equations representing the nodal balance of neutrons, as well as neutron current continuity along rows or columns of computational cells. An iterative algorithm that is more suitable for solving large problems concurrently is derived based on the decomposition of the spatial domain and is accelerated using successive overrelaxation. This algorithm is very well suited for parallel computers, especially since the spatial domain decomposition occurs naturally, so that the number of iterations required for convergence does not depend on the number of processors participating in the calculation. Implementation of the authors' algorithm on the Intel iPSC/2 hypercube and Sequent Balance 8000 parallel computer is presented, and measured speedup and efficiency for test problems are reported. The results suggest that the efficiency of the hypercube quickly deteriorates when many processors are used, while the Sequent Balance retains very high efficiency for a comparable number of participating processors. This leads to the conjecture that message-passing parallel computers are not as well suited for this algorithm as shared-memory machines
Prospects in coincidence experiments
International Nuclear Information System (INIS)
Laget, J.M.
1984-01-01
The sensitivity of virtual photons to the local variations of the charge and magnetization densities is exploited to study the short-range part of the nucleon-nucleon interaction inside the nucleus. The possibility of varying energy, squared mass and longitudinal polarization of the photons independently enables us to disentangle the mechanisms related to the internal structure of the nucleon (e.g. quark interchange) and the contribution due to meson exchange. Coincidence experiments of the type (e,e'N) and (e,e'NN) are performed to suppress the meson contribution to the longitudinal part of the quasi-elastic peak. Four typical examples of coincidence experiments induced by virtual photons are discussed: experiments (1) on the spectroscopic structure of the quasi-elastic peak and the problem of deep lying hole states; (2) on the structure of the continuum; (3) on the low energy side of the quasi-elastic peak; and finally a three-arm coincidence experiment. (Auth.)
TEABAGS: computer programs for instrumental neutron activation analysis
Energy Technology Data Exchange (ETDEWEB)
Lindstrom, D J [Washington Univ., St. Louis, MO (USA); Korotev, R L [Washington Univ., St. Louis, MO (USA). McDonnell Center for the Space Sciences
1982-01-01
Described is a series of INAA data reduction programs collectively known as TEABAGS (Trace Element Analysis By Automated Gamma-ray Spectrometry). The programs are written in FORTRAN and run on a Nuclear Data ND-6620 computer system, but should be adaptable to any medium-sized minicomputer. They are designed to monitor the status of all spectra obtained from samples and comparison standards irradiated together and to do all pending calculations without operator intervention. Major emphasis is placed on finding all peaks in the spectrum, properly identifying all nuclides present and all contributors to each peak, determining accurate estimates of the background continua under peaks, and producing realistic uncertainties on peak areas and final abundances.
Computation of 3D neutron fluxes in one pin hexagonal cell
International Nuclear Information System (INIS)
Prabha, Hem; Marleau, Guy
2013-01-01
Highlights: ► Computations of 3D neutron fluxes in one pin hexagonal cell is performed by Carlvik’s method of collision probability. ► Carlvik’s method requires computation of track lengths in the geometry. ► Equations are developed to compute tracks, in 2D and 3D, in hexagons and are implemented in a program HX7. ► The program HX7 is implemented in NXT module of the code DRAGON, where tracks in pins are computed. ► The tracks are plotted and fluxes are compared with the EXCELT module of the code DRAGON. - Abstract: In this paper we are presenting the method of computation of three dimensional (3D) neutron fluxes in one pin hexagonal cell. Carlvik’s collision probability method of solving neutron transport equation for computing fluxes has been used here. This method can consider exact geometrical details of the given geometry. While using this method, track length computations are required to be done. We have described here the method of computing tracks in one 3D hexagon. A program HX7 has been developed for this purpose. This program has been implemented in the NXT module of the code DRAGON, where tracks in the pins are computed. For computing tracks in 3D, first we use the tracks computed in the two dimensions (2D) and then we project them in the third dimension. We have developed equations for this purpose. In both the regions, fuel pin as well as in the moderator surrounding the pin the fluxes are assumed to be uniform. A uniform source is assumed in the moderator region. Reflecting boundary conditions are applied on all the sides as well as on the top and bottom surfaces. One group 2D and 3D fluxes are compared with the respective results obtained by the EXCELT module of DRAGON. To check the computations, tracks are plotted and errors in the computations are obtained. It is observed by using both the modules EXCELT and NXT that the fluxes in the pins converge faster and in the moderator region fluxes converge very slowly
A study to compute integrated dpa for neutron and ion irradiation environments using SRIM-2013
Saha, Uttiyoarnab; Devan, K.; Ganesan, S.
2018-05-01
Displacements per atom (dpa), estimated based on the standard Norgett-Robinson-Torrens (NRT) model, is used for assessing radiation damage effects in fast reactor materials. A computer code CRaD has been indigenously developed towards establishing the infrastructure to perform improved radiation damage studies in Indian fast reactors. We propose a method for computing multigroup neutron NRT dpa cross sections based on SRIM-2013 simulations. In this method, for each neutron group, the recoil or primary knock-on atom (PKA) spectrum and its average energy are first estimated with CRaD code from ENDF/B-VII.1. This average PKA energy forms the input for SRIM simulation, wherein the recoil atom is taken as the incoming ion on the target. The NRT-dpa cross section of iron computed with "Quick" Kinchin-Pease (K-P) option of SRIM-2013 is found to agree within 10% with the standard NRT-dpa values, if damage energy from SRIM simulation is used. SRIM-2013 NRT-dpa cross sections applied to estimate the integrated dpa for Fe, Cr and Ni are in good agreement with established computer codes and data. A similar study carried out for polyatomic material, SiC, shows encouraging results. In this case, it is observed that the NRT approach with average lattice displacement energy of 25 eV coupled with the damage energies from the K-P option of SRIM-2013 gives reliable displacement cross sections and integrated dpa for various reactor spectra. The source term of neutron damage can be equivalently determined in the units of dpa by simulating self-ion bombardment. This shows that the information of primary recoils obtained from CRaD can be reliably applied to estimate the integrated dpa and damage assessment studies in accelerator-based self-ion irradiation experiments of structural materials. This study would help to advance the investigation of possible correlations between the damages induced by ions and reactor neutrons.
NCT-ART - a neutron computer tomography code based on the algebraic reconstruction technique
International Nuclear Information System (INIS)
Krueger, A.
1988-01-01
A computer code is presented, which calculates two-dimensional cuts of material assemblies from a number of neutron radiographic projections. Mathematically, the reconstruction is performed by an iterative solution of a system of linear equations. If the system is fully determined, clear pictures are obtained. Even for an underdetermined system (low number of projections) reasonable pictures are reconstructed, but then picture artefacts and convergence problems occur increasingly. (orig.) With 37 figs [de
Use of digital computers for correction of gamma method and neutron-gamma method indications
International Nuclear Information System (INIS)
Lakhnyuk, V.M.
1978-01-01
The program for the NAIRI-S computer is described which is intended for accounting and elimination of the effect of by-processes when interpreting gamma and neutron-gamma logging indications. By means of slight corrections it is possible to use the program as a mathematical basis for logging diagram standardization by the method of multidimensional regressive analysis and estimation of rock reservoir properties
ENEL overall PWR plant models and neutronic integrated computing systems
International Nuclear Information System (INIS)
Pedroni, G.; Pollachini, L.; Vimercati, G.; Cori, R.; Pretolani, F.; Spelta, S.
1987-01-01
To support the design activity of the Italian nuclear energy program for the construction of pressurized water reactors, the Italian Electricity Board (ENEL) needs to verify the design as a whole (that is, the nuclear steam supply system and balance of plant) both in steady-state operation and in transient. The ENEL has therefore developed two computer models to analyze both operational and incidental transients. The models, named STRIP and SFINCS, perform the analysis of the nuclear as well as the conventional part of the plant (the control system being properly taken into account). The STRIP model has been developed by means of the French (Electricite de France) modular code SICLE, while SFINCS is based on the Italian (ENEL) modular code LEGO. STRIP validation was performed with respect to Fessenheim French power plant experimental data. Two significant transients were chosen: load step and total load rejection. SFINCS validation was performed with respect to Saint-Laurent French power plant experimental data and also by comparing the SFINCS-STRIP responses
International Nuclear Information System (INIS)
Shanjie, Xiao; Tatjana, Jevremovic
2010-01-01
The accurate, detailed and 3D neutron transport analysis for Gen-IV reactors is still time-consuming regardless of advanced computational hardware available in developed countries. This paper introduces a new concept in addressing the computational time while persevering the detailed and accurate modeling; a specifically designed FPGA co-processor accelerates robust AGENT methodology for complex reactor geometries. For the first time this approach is applied to accelerate the neutronics analysis. The AGENT methodology solves neutron transport equation using the method of characteristics. The AGENT methodology performance was carefully analyzed before the hardware design based on the FPGA co-processor was adopted. The most time-consuming kernel part is then transplanted into the FPGA co-processor. The FPGA co-processor is designed with data flow-driven non von-Neumann architecture and has much higher efficiency than the conventional computer architecture. Details of the FPGA co-processor design are introduced and the design is benchmarked using two different examples. The advanced chip architecture helps the FPGA co-processor obtaining more than 20 times speed up with its working frequency much lower than the CPU frequency. (authors)
Energy Technology Data Exchange (ETDEWEB)
Kumada, Hiroaki; Yamamoto, Kazuyoshi; Torii, Yoshiya; Uchiyama, Junzo [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Matsumura, Akira; Yamamoto, Tetsuya; Nose, Tadao [Tsukuba Univ., Tsukuba, Ibaraki (Japan); Nakagawa, Yoshinobu [National Sanatorium Kagawa-Children' s Hospital, Kagawa (Japan); Kageji, Teruyoshi [Tokushima Univ., Tokushima (Japan)
2003-03-01
The Neutron Beam Facility at JRR-4 enables us to carry out boron neutron capture therapy with epithermal neutron beam. In order to make treatment plans for performing the epithermal neutron beam BNCT, it is necessary to estimate radiation doses in a patient's head in advance. The JAERI Computational Dosimetry System (JCDS), which can estimate distributions of radiation doses in a patient's head by simulating in order to support the treatment planning for epithermal neutron beam BNCT, was developed. JCDS is a software that creates a 3-dimentional head model of a patient by using CT and MRI images, and that generates a input data file automatically for calculation of neutron flux and gamma-ray dose distributions in the brain with the Monte Carlo code MCNP, and that displays these dose distributions on the head model for dosimetry by using the MCNP calculation results. JCDS has any advantages as follows; By using CT data and MRI data which are medical images, a detail three-dimensional model of patient's head is able to be made easily. The three-dimensional head image is editable to simulate the state of a head after its surgical processes such as skin flap opening and bone removal in the BNCT with craniotomy that are being performed in Japan. JCDS can provide information for the Patient Setting System which can support to set the patient to an actual irradiation position swiftly and accurately. This report describes basic design of JCDS and functions in several processing, calculation methods, characteristics and performance of JCDS. (author)
Energy Technology Data Exchange (ETDEWEB)
Fong, G; Kapadia, A [Carl E Ravin Advanced Imaging Laboratories, Durham, North Carolina (United States)
2016-06-15
Purpose: To optimize collimation and shielding for a deuterium-deuterium (DD) neutron generator for an inexpensive and compact clinical neutron imaging system. The envisioned application is cancer diagnosis through Neutron Stimulated Emission Computed Tomography (NSECT). Methods: Collimator designs were tested with an isotropic 2.5 MeV neutron source through GEANT4 simulations. The collimator is a 52×52×52 cm{sup 3} polyethylene block coupled with a 1 cm lead sheet in sequence. Composite opening was modeled into the collimator to permit passage of neutrons. The opening varied in shape (cylindrical vs. tapered), size (1–5 cm source-side and target-side openings) and aperture placements (13–39 cm from source-side). Spatial and energy distribution of neutrons and gammas were tracked from each collimator design. Parameters analyzed were primary beam width (FWHM), divergence, and efficiency (percent transmission) for different configurations of the collimator. Select resultant outputs were then used for simulated NSECT imaging of a virtual breast phantom containing a 2.5 cm diameter tumor to assess the effect of the collimator on spatial resolution, noise, and scan time. Finally, composite shielding enclosure made of polyethylene and lead was designed and evaluated to block 99.99% of neutron and gamma radiation generated in the system. Results: Analysis of primary beam indicated the beam-width is linear to the aperture size. Increasing source-side opening allowed at least 20% more neutron throughput for all designs relative to the cylindrical openings. Maximum throughput for all designs was 364% relative to cylindrical openings. Conclusion: The work indicates potential for collimating and shielding a DD neutron generator for use in a clinical NSECT system. The proposed collimator designs produced a well-defined collimated neutron beam that can be used to image samples of interest with millimeter resolution. Balance in output efficiency, noise reduction, and scan
International Nuclear Information System (INIS)
Fong, G; Kapadia, A
2016-01-01
Purpose: To optimize collimation and shielding for a deuterium-deuterium (DD) neutron generator for an inexpensive and compact clinical neutron imaging system. The envisioned application is cancer diagnosis through Neutron Stimulated Emission Computed Tomography (NSECT). Methods: Collimator designs were tested with an isotropic 2.5 MeV neutron source through GEANT4 simulations. The collimator is a 52×52×52 cm"3 polyethylene block coupled with a 1 cm lead sheet in sequence. Composite opening was modeled into the collimator to permit passage of neutrons. The opening varied in shape (cylindrical vs. tapered), size (1–5 cm source-side and target-side openings) and aperture placements (13–39 cm from source-side). Spatial and energy distribution of neutrons and gammas were tracked from each collimator design. Parameters analyzed were primary beam width (FWHM), divergence, and efficiency (percent transmission) for different configurations of the collimator. Select resultant outputs were then used for simulated NSECT imaging of a virtual breast phantom containing a 2.5 cm diameter tumor to assess the effect of the collimator on spatial resolution, noise, and scan time. Finally, composite shielding enclosure made of polyethylene and lead was designed and evaluated to block 99.99% of neutron and gamma radiation generated in the system. Results: Analysis of primary beam indicated the beam-width is linear to the aperture size. Increasing source-side opening allowed at least 20% more neutron throughput for all designs relative to the cylindrical openings. Maximum throughput for all designs was 364% relative to cylindrical openings. Conclusion: The work indicates potential for collimating and shielding a DD neutron generator for use in a clinical NSECT system. The proposed collimator designs produced a well-defined collimated neutron beam that can be used to image samples of interest with millimeter resolution. Balance in output efficiency, noise reduction, and scan time
The application of computer and automatic technology in dose measurement of neutron radiation
International Nuclear Information System (INIS)
Zhou Yu; Li Chenglin; Luo Yisheng; Guo Yong; Chen Di; Xiaojiang
1999-01-01
Generally the dose measurement of neutron radiation requires three electrometers, two bias, three workers in the same time. To improve the accuracy and efficiency of measurement, a Model 6517A electrometer that accommodate Model 6521 scanner cards and a portable computer are used to make up of a automatic measurement system. Corresponding software is developed and used to control it. Because of the application of computer and automatic technology, this system can not only measure dose rate automatically, but also make data's calculating, saving, querying, printing and comparing ease
NADAC and MERGE: computer codes for processing neutron activation analysis data
International Nuclear Information System (INIS)
Heft, R.E.; Martin, W.E.
1977-01-01
Absolute disintegration rates of specific radioactive products induced by neutron irradition of a sample are determined by spectrometric analysis of gamma-ray emissions. Nuclide identification and quantification is carried out by a complex computer code GAMANAL (described elsewhere). The output of GAMANAL is processed by NADAC, a computer code that converts the data on observed distintegration rates to data on the elemental composition of the original sample. Computations by NADAC are on an absolute basis in that stored nuclear parameters are used rather than the difference between the observed disintegration rate and the rate obtained by concurrent irradiation of elemental standards. The NADAC code provides for the computation of complex cases including those involving interrupted irradiations, parent and daughter decay situations where the daughter may also be produced independently, nuclides with very short half-lives compared to counting interval, and those involving interference by competing neutron-induced reactions. The NADAC output consists of a printed report, which summarizes analytical results, and a card-image file, which can be used as input to another computer code MERGE. The purpose of MERGE is to combine the results of multiple analyses and produce a single final answer, based on all available information, for each element found
International Nuclear Information System (INIS)
Tittle, C.W.
1992-01-01
Diffusion theory has been successfully used to model the effect of fluid invasion into the formation for neutron porosity logs and for the gamma-gamma density log. The purpose of this paper is to present results of computations using a five-group time-dependent diffusion code on invasion effects for the pulsed neutron thermal decay time log. Previous invasion studies by the author involved the use of a three-dimensional three-group steady-state diffusion theory to model the dual-detector thermal neutron porosity log and the gamma-gamma density log. The five-group time-dependent code MGNDE (Multi-Group Neutron Diffusion Equation) used in this work was written by Ferguson. It has been successfully used to compute the intrinsic formation life-time correction for pulsed neutron thermal decay time logs. This application involves the effect of fluid invasion into the formation
Culbertson, C N; Wangerin, K; Ghandourah, E; Jevremovic, T
2005-08-01
The goal of this study was to evaluate the COG Monte Carlo radiation transport code, developed and tested by Lawrence Livermore National Laboratory, for neutron capture therapy related modeling. A boron neutron capture therapy model was analyzed comparing COG calculational results to results from the widely used MCNP4B (Monte Carlo N-Particle) transport code. The approach for computing neutron fluence rate and each dose component relevant in boron neutron capture therapy is described, and calculated values are shown in detail. The differences between the COG and MCNP predictions are qualified and quantified. The differences are generally small and suggest that the COG code can be applied for BNCT research related problems.
Computational uncertainties in silicon dioxide/plutonium intermediate neutron spectrum systems
International Nuclear Information System (INIS)
Jaegers, P.J.
1997-01-01
In the past several years, several proposals have been made for the long-term stabilization and storage of surplus fissile materials. Many of these proposed scenarios involve systems that have an intermediate neutron energy spectrum. Such intermediate-energy systems are dominated by scattering and fission events induced by neutrons ranging in energy from 1 eV to 100keV. To ensure adequate safety margins and cost effectiveness, it is necessary to have benchmark data for these intermediate-energy spectrum systems; however, a review of the nuclear criticality benchmarks indicates that no formal benchmarks are available. Nuclear data uncertainties have been reported for some types of intermediate-energy spectrum systems. Using a variety of Monte Carlo computer codes and cross-section sets, reported significant variations in the calculated k ∞ of intermediate-energy spectrum metal/ 235 U systems. We discuss the characteristics of intermediate neutron spectrum systems and some of the computational differences that can occur in calculating the k eff of these systems
Mathematical processing of experimental data on neutron yield from separate fission fragments
International Nuclear Information System (INIS)
Basova, B.G.; Rabinovich, A.D.; Ryazanov, D.K.
1975-01-01
The algorithm is described for processing the multi-dimensional experiments on measurements of prompt emission of neutrons from separate fission fragments. While processing the data the effect of a number of experimental corrections is correctly taken into account; random coincidence background, neutron spectrum, neutron detector efficiency, instrument angular resolution. On the basis of the described algorithm a program for BESM-4 computer is realized and the treatment of experimental data is performed according to the spontaneous fission of 252 Cf
Bromley, Blair Patrick
2001-12-01
The axial-cylindrical Inertial Electrostatic Confinement fusion neutron generator (IEC C-Device) is a high- voltage, low-pressure glow discharge device that produces neutrons from the deuterium-deuterium fusion reaction. Such a neutron source has potential applications for neutron activation analysis and capture therapies for cancer treatment. The IEC C-Device operating with deuterium fuel is modeled with the CHIMP computer code developed and written completely by the author to predict the fusion neutron generation rate and the plasma physics behavior using fundamental first principles. The CHIMP code is a time-dependent, spatially two-dimensional (r,z), particle-in-cell, Monte-Carlo-Collision (PIC-MCC) direct simulation model. The effects of secondary electron emission due to ion and electron impact on the metal electrodes and the glass walls and charge build-up on the glass wall are included. Either monatomic or molecular ions and electrons are modeled in a monatomic or molecular background neutral deuterium gas. CHIMP code predictions are compared against experimental results for the C-Device operating between 10 and 30 kV of anode voltage, between 10 and 40 mA of electrode current, and between 0.29 and 1.1 milliTorr of deuterium gas pressure. A calibration factor for the pressure accounts for the calibration of the ionization pressure gauge in the experiment, and an estimated pressure drop between the main chamber of the C-Device and the pressure gauge that is downstream of the exhaust port. Upgraded versions of the CHIMP code which have modifications to the algorithms for the boundary conditions, and which include charge exchange processes, and the contribution of fast neutrals to the neutron generation rate are also tested against several experimental data points. Although the CHIMP code gives predictions for the neutron generation rate that exhibit the same near-linear trends with current found in the experiment, it is apparent that at least five types of
Sabaibang, S.; Lekchaum, S.; Tipayakul, C.
2015-05-01
This study is a part of an on-going work to develop a computational model of Thai Research Reactor (TRR-1/M1) which is capable of accurately predicting the neutron flux level and spectrum. The computational model was created by MCNPX program and the CT (Central Thimble) in-core irradiation facility was selected as the location for validation. The comparison was performed with the typical flux measurement method routinely practiced at TRR-1/M1, that is, the foil activation technique. In this technique, gold foil is irradiated for a certain period of time and the activity of the irradiated target is measured to derive the thermal neutron flux. Additionally, the flux measurement with SPND (self-powered neutron detector) was also performed for comparison. The thermal neutron flux from the MCNPX simulation was found to be 1.79×1013 neutron/cm2s while that from the foil activation measurement was 4.68×1013 neutron/cm2s. On the other hand, the thermal neutron flux from the measurement using SPND was 2.47×1013 neutron/cm2s. An assessment of the differences among the three methods was done. The difference of the MCNPX with the foil activation technique was found to be 67.8% and the difference of the MCNPX with the SPND was found to be 27.8%.
Neutron spectra calculation in material in order to compute irradiation damage
International Nuclear Information System (INIS)
Dupont, C.; Gonnord, J.; Le Dieu de Ville, A.; Nimal, J.C.; Totth, B.
1982-01-01
This short presentation will be on neutron spectra calculation methods in order to compute the damage rate formation in irradiated structure. Three computation schemes are used in the French C.E.A.: (1) 3-dimensional calculations using the line of sight attenuation method (MERCURE IV code), the removal cross section being obtained from an adjustment on a 1-dimensional transport calculation with the discrete ordinate code ANISN; (2) 2-dimensional calculations using the discrete ordinates method (DOT 3.5 code), 20 to 30 group library obtained by collapsing the 100 group a library on fluxes computed by ANISN; (3) 3-dimensional calculations using the Monte Carlo method (TRIPOLI system). The cross sections which originally came from UKNDL 73 and ENDF/B3 are now processed from ENDF B IV. (author)
The use of symbolic computation in radiative, energy, and neutron transport calculations
Frankel, J. I.
This investigation uses symbolic computation in developing analytical methods and general computational strategies for solving both linear and nonlinear, regular and singular, integral and integro-differential equations which appear in radiative and combined mode energy transport. This technical report summarizes the research conducted during the first nine months of the present investigation. The use of Chebyshev polynomials augmented with symbolic computation has clearly been demonstrated in problems involving radiative (or neutron) transport, and mixed-mode energy transport. Theoretical issues related to convergence, errors, and accuracy have also been pursued. Three manuscripts have resulted from the funded research. These manuscripts have been submitted to archival journals. At the present time, an investigation involving a conductive and radiative medium is underway. The mathematical formulation leads to a system of nonlinear, weakly-singular integral equations involving the unknown temperature and various Legendre moments of the radiative intensity in a participating medium. Some preliminary results are presented illustrating the direction of the proposed research.
NEWSPEC: A computer code to unfold neutron spectra from Bonner sphere data
International Nuclear Information System (INIS)
Lemley, E.C.; West, L.
1996-01-01
A new computer code, NEWSPEC, is in development at the University of Arkansas. The NEWSPEC code allows a user to unfold, fold, rebin, display, and manipulate neutron spectra as applied to Bonner sphere measurements. The SPUNIT unfolding algorithm, a new rebinning algorithm, and the graphical capabilities of Microsoft (MS) Windows and MS Excel are utilized to perform these operations. The computer platform for NEWSPEC is a personal computer (PC) running MS Windows 3.x or Win95, while the code is written in MS Visual Basic (VB) and MS VB for Applications (VBA) under Excel. One of the most useful attributes of the NEWSPEC software is the link to Excel allowing additional manipulation of program output or creation of program input
Using the transportable, computer-operated, liquid-scintillator fast-neutron spectrometer system
International Nuclear Information System (INIS)
Thorngate, J.H.
1988-01-01
When a detailed energy spectrum is needed for radiation-protection measurements from approximately 1 MeV up to several tens of MeV, organic-liquid scintillators make good neutron spectrometers. However, such a spectrometer requires a sophisticated electronics system and a computer to reduce the spectrum from the recorded data. Recently, we added a Nuclear Instrument Module (NIM) multichannel analyzer and a lap-top computer to the NIM electronics we have used for several years. The result is a transportable fast-neutron spectrometer system. The computer was programmed to guide the user through setting up the system, calibrating the spectrometer, measuring the spectrum, and reducing the data. Measurements can be made over three energy ranges, 0.6--2 MeV, 1.1--8 MeV, or 1.6--16 MeV, with the spectrum presented in 0.1-MeV increments. Results can be stored on a disk, presented in a table, and shown in graphical form. 5 refs., 51 figs
New way on designing majorant coincidence circuits
International Nuclear Information System (INIS)
Gajdamaka, R.I.; Kalinnikov, V.A.; Nikityuk, N.M.; Shirikov, V.P.
1982-01-01
A new way of designing fast devices of combinatorial selection by the number of particles passing through a multichannel charged particle detector is decribed. The algorithm of their operation is based on modern algebraic coding theory. By application of analytical computational methods Boolean expressions can be obtianed for designing basic circuits for a large number of inputs. An example of computation of 15 inputs majorant coincidence circuit is considered
Analysis of neutron data in the resonance region via the computer code SAMMY
International Nuclear Information System (INIS)
Larson, N.M.
1985-01-01
Procedures for analysis of resonance neutron cross-section data have been implemented in a state-of-the-art computer code SAMMY, developed at the Oak Ridge Electron Linear Accelerator (ORELA) at Oak Ridge National Laboratory. A unique feature of SAMMY is the use of Bayes' equations to determine ''best'' values of parameters, which permits sequential analysis of data sets (or subsets) while giving the same results as would be given by a simultaneous analysis. Another important feature is the inclusion of data-reduction parameters in the fitting procedure. Other features of SAMMY are also described
Aquelarre. A computer code for fast neutron cross sections from the statistical model
International Nuclear Information System (INIS)
Guasp, J.
1974-01-01
A Fortran V computer code for Univac 1108/6 using the partial statistical (or compound nucleus) model is described. The code calculates fast neutron cross sections for the (n, n'), (n, p), (n, d) and (n, α reactions and the angular distributions and Legendre moments.for the (n, n) and (n, n') processes in heavy and intermediate spherical nuclei. A local Optical Model with spin-orbit interaction for each level is employed, allowing for the width fluctuation and Moldauer corrections, as well as the inclusion of discrete and continuous levels. (Author) 67 refs
Computational analysis of neutronic parameters of CENM TRIGA Mark II research reactor
International Nuclear Information System (INIS)
El Younoussi, C.; El Bakkari, B.; Boulaich, Y.; Riyach, D.; Otmani, S.; Marrhich, I.; Badri, H.; Htet, A.; Nacir, B.; El Bardouni, T.; Boukhal, H.; Zoubair, M.; Ossama, M.; Chakir, E.
2010-01-01
The CENM TRIGA MARK II reactor is part of the National Center for Energy, Sciences and Nuclear Techniques (CNESTEN). It's a standard design 2MW, natural-convection-cooled reactor with a graphite reflector containing 4 beam tubes and a thermal column. The reactor has several applications in different fields as industry, agriculture, medicine, training and education. In the present work a computational study has been carried out in the framework of neutronic parameters studies of the reactor. A detailed MCNP model that include all elements of the core and surrounding structures has been developed to calculate different parameters of the core (The effective multiplication factor, reactivity experiments comprising control rods worth, excess reactivity and shutdown margin). Further calculations have been carried out to calculate the neutron flux profiles at different locations of the reactor core. The cross sections used are processed from the library provided with MCNP5 and based on the ENDF/B-VII with continuous dependence in energy and special treatment of thermal neutrons in lightweight materials. (author)
Wilson, C.; King, J.
The Colorado School of Mines installed a neutron radiography system at the United States Geological Survey TRIGA reactor in 2012. An upgraded beamline could dramatically improve the imaging capabilities of this system. This project performed computational analyses to support the design of a new beamline, with the major goals of minimizing beam divergence and maximizing beam intensity. The new beamline will consist of a square aluminum tube with an 11.43 cm (4.5 in) inner side length and 0.635 cm (0.25 in) thick walls. It is the same length as the original beam tube (8.53 m) and is composed of 1.22 m (4 ft) and 1.52 m (5 ft) flanged sections which bolt together. The bottom 1.22 m of the beamline is a cylindrical aluminum pre-collimator which is 0.635 cm (0.25 in) thick, with an inner diameter of 5.08 cm (2 in). Based on Monte Carlo model results, when a pre-collimator is present, the use of a neutron absorbing liner on the inside surface of the beam tube has almost no effect on the angular distribution of the neutron current at the collimator exit. The use of a pre-collimator may result in a non-uniform flux profile at the image plane; however, as long as the collimator is at least three times longer than the pre-collimator, the flux distortion is acceptably low.
Triple-coincidence with automatic chance coincidence correction
International Nuclear Information System (INIS)
Chase, R.L.
1975-05-01
The chance coincidences in a triple-coincidence circuit are of two types--partially correlated and entirely uncorrelated. Their relative importance depends on source strength and source and detector geometry so that the total chance correction cannot, in general, be calculated. The system described makes use of several delays and straightforward integrated circuit logic to provide independent evaluation of the two components of the chance coincidence rate. (auth)
International Nuclear Information System (INIS)
Ortiz R, J. M.; Vega C, H. R.; Martinez B, M. R.; Gallego, E.
2009-10-01
The neutron dosimetry is one of the most complicated tasks of radiation protection, due to it is a complex technique and highly dependent of neutron energy. One of the first devices used to perform neutron spectrometry is the system known as spectrometric system of Bonner spheres, that continuous being one of spectrometers most commonly used. This system has disadvantages such as: the components weight, the low resolution of spectrum, long and drawn out procedure for the spectra reconstruction, which require an expert user in system management, the need of use a reconstruction code as BUNKIE, SAND, etc., which are based on an iterative reconstruction algorithm and whose greatest inconvenience is that for the spectrum reconstruction, are needed to provide to system and initial spectrum as close as possible to the desired spectrum get. Consequently, researchers have mentioned the need to developed alternative measurement techniques to improve existing monitoring systems for workers. Among these alternative techniques have been reported several reconstruction procedures based on artificial intelligence techniques such as genetic algorithms, artificial neural networks and hybrid systems of evolutionary artificial neural networks using genetic algorithms. However, the use of these techniques in the nuclear science area is not free of problems, so it has been suggested that more research is conducted in such a way as to solve these disadvantages. Because they are emerging technologies, there are no tools for the results analysis, so in this paper we present first the design of a computation tool that allow to analyze the neutron spectra and equivalent doses, obtained through the hybrid technology of neural networks and genetic algorithms. This tool provides an user graphical environment, friendly, intuitive and easy of operate. The speed of program operation is high, executing the analysis in a few seconds, so it may storage and or print the obtained information for
International Nuclear Information System (INIS)
Drozdowicz, K.; Woznicka, U.
1982-01-01
The program in FORTRAN for the ODRA-1305 computer is described. The dependence of the decay constant of the thermal neutron flux upon the dimensions of the two-region concentric cylindrical system is the result of the program. The solution (with a constant neutron flux in the inner medium assumed) is generally obtained in the one-group diffusion approximation by the method of the perturbation calculation. However, the energy distribution of the thermal neutron flux and the diffusion cooling are taken into account. The program is written for the case when the outer medium is hydrogenous. The listing of the program and an example of calculation results are included. (author)
Implementing of AMPX-II system for a univac computer neutron cross-section libraries
International Nuclear Information System (INIS)
Sancho, J.; Verdu, G.; Serradell, V.
1984-01-01
The AMPX-II system, developed at ORNL, is constituted by a modular set of computer programs, for generation and handling of several nuclear data libraries. The processing starts from ENDF/B library. Along this paper, we refer mainly to the modules related with neutron cross section libraries: master, working and weighted. These modules have been implemented recently for a UNIVAC 1100/60 computer in the Universidad Politecnica de Valencia (Spain). In order to run the programs in that machine it has been necessary to introduce a number of modifications into their programing structure. The main difficulties found in this work and the need of verification for the new versions are also pointed out. We also refer to the results obtained from the execution of a set of little sample problems. (author)
International Nuclear Information System (INIS)
Greim, L.; Motamedi, K.; Niedergesaess, R.
1976-01-01
A computer code evaluating experimental data of neutron activation analysis (NAA) for determination of atomic abundancies is described. The experimental data are, beside a probe designation, the probe weight, irradiation parameters and a Ge(Li)-pulse-height-spectrum from the activity measurement. The organisation of the necessary nuclear data, comprising all methods of activation in reactor-irradiations, is given. Furthermore the automatic evaluation of spectra, the designation of the resulting peaks to nuclei and the calculation of atomic abundancies are described. The complete evaluation of a spectrum with many lines, e.g. 100 lines of 20 nuclei, takes less than 1 minute machine-time on the TR 440 computer. (orig.) [de
International Nuclear Information System (INIS)
Szopa, Z.; Plejewska, M.; Staszelis, J.
1982-01-01
A full system of four computer programs for routine - qualitative and quantitative - neutron activation analysis (NAA) using high resolution gamma ray-spectrometry had been elaborated. The structure and possibilities of the ''data flow'' programs i.e. programs DIDPDP and DIDCDC, dedicated for fast and reliable ''off line'' data transfer between the buffer memory of the spectrometric line (9-track magnetic tape) and the fast access memory (disc) of the used computers PDP-11/45 and CYBER-73 had been presented. The structure and organization of the ''data processing'' programs i.e. programs SAWAPS and MAZYG had been presented as well. The utility and reliability of these programs in the case of the large-scale, routine NAA, exampled by analysis of filters with air polutants, had been tested and discussed. Programs are written mainly in FORTRAN. (author)
Coincidence counting corrections for dead time losses and accidental coincidences
International Nuclear Information System (INIS)
Wyllie, H.A.
1987-04-01
An equation is derived for the calculation of the radioactivity of a source from the results of coincidence counting taking into account the dead-time losses and accidental coincidences. The derivation is an extension of the method of J. Bryant [Int. J. Appl. Radiat. Isot., 14:143, 1963]. The improvement on Bryant's formula has been verified by experiment
Operations manual for the megachannel gamma-ray coincidence system
International Nuclear Information System (INIS)
Ruhter, W.
1977-01-01
To aid in the study of nuclear structures, a megachannel pulse-height coincidence analysis system on a PDP-8 computer was constructed. The system digitizes the energies of coincident gamma-rays and stores the resultant information on a moving-head disk. The system uses a minicomputer to sort and store gamma-gamma coincident information on line. The megachannel system and how to use it are described
Response functions for computing absorbed dose to skeletal tissues from neutron irradiation
Bahadori, Amir A.; Johnson, Perry; Jokisch, Derek W.; Eckerman, Keith F.; Bolch, Wesley E.
2011-11-01
Spongiosa in the adult human skeleton consists of three tissues—active marrow (AM), inactive marrow (IM) and trabecularized mineral bone (TB). AM is considered to be the target tissue for assessment of both long-term leukemia risk and acute marrow toxicity following radiation exposure. The total shallow marrow (TM50), defined as all tissues lying within the first 50 µm of the bone surfaces, is considered to be the radiation target tissue of relevance for radiogenic bone cancer induction. For irradiation by sources external to the body, kerma to homogeneous spongiosa has been used as a surrogate for absorbed dose to both of these tissues, as direct dose calculations are not possible using computational phantoms with homogenized spongiosa. Recent micro-CT imaging of a 40 year old male cadaver has allowed for the accurate modeling of the fine microscopic structure of spongiosa in many regions of the adult skeleton (Hough et al 2011 Phys. Med. Biol. 56 2309-46). This microstructure, along with associated masses and tissue compositions, was used to compute specific absorbed fraction (SAF) values for protons originating in axial and appendicular bone sites (Jokisch et al 2011 Phys. Med. Biol. 56 6857-72). These proton SAFs, bone masses, tissue compositions and proton production cross sections, were subsequently used to construct neutron dose-response functions (DRFs) for both AM and TM50 targets in each bone of the reference adult male. Kerma conditions were assumed for other resultant charged particles. For comparison, AM, TM50 and spongiosa kerma coefficients were also calculated. At low incident neutron energies, AM kerma coefficients for neutrons correlate well with values of the AM DRF, while total marrow (TM) kerma coefficients correlate well with values of the TM50 DRF. At high incident neutron energies, all kerma coefficients and DRFs tend to converge as charged-particle equilibrium is established across the bone site. In the range of 10 eV to 100 Me
Coincidence measurements of FFTF breeder fuel subassemblies
International Nuclear Information System (INIS)
Eccleston, G.W.; Foley, J.E.; Krick, M.; Menlove, H.O.; Goris, P.; Ramalho, A.
1984-04-01
A prototype coincidence counter developed to assay fast breeder reactor fuel was used to measure four fast-flux test facility subassemblies at the Hanford Engineering Development Laboratory in Richland, Washington. Plutonium contents in the four subassemblies ranged between 7.4 and 9.7 kg with corresponding 240 Pu-effective contents between 0.9 and 1.2 kg. Large count rates were observed from the measurements, and plots of the data showed significant multiplication in the fuel. The measured data were corrected for deadtime and multiplication effects using established formulas. These corrections require accurate knowledge of the plutonium isotopics and 241 Am content in the fuel. Multiplication-corrected coincidence count rates agreed with the expected count rates based on spontaneous fission-neutron emission rates. These measurements indicate that breeder fuel subassemblies with 240 Pu-effective contents up to 1.2 kg can be nondestructively assayed using the shift-register electronics with the prototype counters. Measurements using the standard Los Alamos National Laboratory shift-register coincidence electronics unit can produce an assay value accurate to +-1% in 1000 s. The uncertainty results from counting statistics and deadtime-correction errors. 3 references, 8 figures, 8 tables
Consler, T G; Uberbacher, E C; Bunick, G J; Liebman, M N; Lee, J C
1988-02-25
The effects of ligands on the structure of rabbit muscle pyruvate kinase were studied by small angle neutron scattering. The radius of gyration, RG, decreases by about 1 A in the presence of the substrate phosphoenolpyruvate, but increases by about the same magnitude in the presence of the allosteric inhibitor phenylalanine. With increasing pH or in the absence of Mg2+ and K+, the RG of pyruvate kinase increases. Hence, there is a 2-A difference in RG between two alternative conformations. Length distribution analysis indicates that, under all experimental conditions which increase the radius of gyration, there is a pronounced increase observed in the probability for interatomic distance between 80 and 110 A. These small angle neutron scattering results indicate a "contraction" and "expansion" of the enzyme when it transforms between its active and inactive forms. Using the alpha-carbon coordinates of crystalline cat muscle pyruvate kinase, a length distribution profile was calculated, and it matches the scattering profile of the inactive form. These observations are expected since the crystals were grown in the absence of divalent cations (Stuart, D. I., Levine, M., Muirhead, H., and Stammers, D. K. (1979) J. Mol. Biol. 134, 109-142). Hence, results from neutron scattering, x-ray crystallographic, and sedimentation studies (Oberfelder, R. W., Lee, L. L.-Y., and Lee, J.C. (1984) Biochemistry 23, 3813-3821) are totally consistent with each other. With the aid of computer modeling, the crystal structure has been manipulated in order to effect changes that are consistent with the conformational change described by the solution scattering data. The structural manipulation involves the rotation of the B domain relative to the A domain, leading to the closure of the cleft between these domains. These manipulations resulted in the generation of new sets of atomic (C-alpha) coordinates, which were utilized in calculations, the result of which compared favorably with the
PERIGEE computer codes for reactor simulation in 3 dimensions, using 1 or 2 neutron velocity groups
International Nuclear Information System (INIS)
Olson, A.P.
1964-02-01
PERIGEE is a code written in SNAP for the G-20 computer. It solves the one- or two-group neutron diffusion equations by finite-difference methods on a three-dimensional, uniform mesh having a common spacing in the two directions normal to the fuel channels. The positions of mesh points along a fuel channel, relative to points in adjacent channels, may correspond to either NPD or CANDU fuel bundle positions. The extrapolated flux boundary may be specified in sufficient detail to represent a tapered or stepped circumferential reflector, a variable axial length and, for a reactor with axis horizontal, a variable moderator level and a variable plane bottom surface equivalent to the CANDU dump structure. The neutron flux may be normalized to give a specified power output from the hottest fuel bundle or hottest channel, or to give a total thermal power limited by the turbine and generator. Reactor operation may be simulated in finite time steps, taking into account any fuel shifts, any changes in moderator level and the change in nuclear properties of the fuel with increasing irradiation. The appropriate properties are obtained by interpolation from tables supplied for as many as 8 types of fuel bundle. The mean fuel exit burnup can be calculated at equilibrium for a reactor in which the exit burnups for two zones may be adjusted to give radial power flattening and the fuelling schedules may be designed to give axial power flattening in one or both zones. (author)
Verification of the computational dosimetry system in JAERI (JCDS) for boron neutron capture therapy
International Nuclear Information System (INIS)
Kumada, H; Yamamoto, K; Matsumura, A; Yamamoto, T; Nakagawa, Y; Nakai, K; Kageji, T
2004-01-01
Clinical trials for boron neutron capture therapy (BNCT) by using the medical irradiation facility installed in Japan Research Reactor No. 4 (JRR-4) at Japan Atomic Energy Research Institute (JAERI) have been performed since 1999. To carry out the BNCT procedure based on proper treatment planning and its precise implementation, the JAERI computational dosimetry system (JCDS) which is applicable to dose planning has been developed in JAERI. The aim of this study was to verify the performance of JCDS. The experimental data with a cylindrical water phantom were compared with the calculation results using JCDS. Data of measurements obtained from IOBNCT cases at JRR-4 were also compared with retrospective evaluation data with JCDS. In comparison with phantom experiments, the calculations and the measurements for thermal neutron flux and gamma-ray dose were in a good agreement, except at the surface of the phantom. Against the measurements of clinical cases, the discrepancy of JCDS's calculations was approximately 10%. These basic and clinical verifications demonstrated that JCDS has enough performance for the BNCT dosimetry. Further investigations are recommended for precise dose distribution and faster calculation environment
IMPROVED COMPUTATIONAL NEUTRONICS METHODS AND VALIDATION PROTOCOLS FOR THE ADVANCED TEST REACTOR
Energy Technology Data Exchange (ETDEWEB)
David W. Nigg; Joseph W. Nielsen; Benjamin M. Chase; Ronnie K. Murray; Kevin A. Steuhm
2012-04-01
The Idaho National Laboratory (INL) is in the process of modernizing the various reactor physics modeling and simulation tools used to support operation and safety assurance of the Advanced Test Reactor (ATR). Key accomplishments so far have encompassed both computational as well as experimental work. A new suite of stochastic and deterministic transport theory based reactor physics codes and their supporting nuclear data libraries (HELIOS, KENO6/SCALE, NEWT/SCALE, ATTILA, and an extended implementation of MCNP5) has been installed at the INL. Corresponding models of the ATR and ATRC are now operational with all five codes, demonstrating the basic feasibility of the new code packages for their intended purpose. Of particular importance, a set of as-run core depletion HELIOS calculations for all ATR cycles since August 2009 was successfully completed during 2011. This demonstration supported a decision late in the year to proceed with the phased incorporation of the HELIOS methodology into the ATR fuel cycle management process beginning in 2012. On the experimental side of the project, new hardware was fabricated, measurement protocols were finalized, and the first four of six planned physics code validation experiments based on neutron activation spectrometry were conducted at the ATRC facility. Data analysis for the first three experiments, focused on characterization of the neutron spectrum in one of the ATR flux traps, has been completed. The six experiments will ultimately form the basis for a flexible, easily-repeatable ATR physics code validation protocol that is consistent with applicable ASTM standards.
International Nuclear Information System (INIS)
Najjar, F.; Moretti, J.
2007-01-01
Solitary Pulmonary Nodules (size 40 mm) is the most frequent indication of coincidence detection emission tomography (CDET) with fluorine-18 fluoro-2-deoxy-D-glucose (18FDG). The aim of the present study was to establish the efficacy of this system with and without attenuation correction (AC) in correlation with computed tomography (CT) findings for the distinction between benign and malignant pulmonary nodules. Material and methods: Sixty-eight patients were included in this study. All patients presented with suspected pulmonary nodules on thoracic CT. In addition, they had CDET scan using a dual-head coincidence gamma-camera with and without measured attenuation using caesium- 137 source. Corrected images were independently interpreted from non-attenuation corrected images in a blinded manner of any clinical data. 18FDG-CDET findings were evaluated by histology when it was available. Otherwise, the final clinical outcome has been considered in data analysis. Results: A total of 71 suspected nodules were observed by CT. Malignant pulmonary disease was found in 38 of these nodules whereas 33 pulmonary nodules were proved to be benign. In addition, one malignant nodule was confirmed with negative CT findings. 18FDG-CDET imaging without AC demonstrated 48 suspected pulmonary lesions included 4 nodules with negative CT findings (sensitivity, 92%; specificity, 68.4%) Versus 43 lesions identified with AC (sensitivity, 92%; specificity, 81.5%). All of the malignant nodules >20 mm in diameter by 18FDG-CDET. In 5 patients (8% of cases), uncorrected images were spotting benign nodules which were considered as negative on corrected images. So lower specificity rate was obtained by non AC mode in comparison with AC mode (68.4% versus 81.5% respectively). Both modalities techniques failed to detect malignancy in 3 patients. In general, the diagnostic accuracy of 18FDG-CDET without AC was relatively comparable to that found with AC (82.6% to 87%, respectively).
International Nuclear Information System (INIS)
Itagaki, Masafumi; Sahashi, Naoki.
1996-01-01
The multiple reciprocity method (MRM) in conjunction with the boundary element method has been employed to solve one-group eigenvalue problems described by the three-dimensional (3-D) neutron diffusion equation. The domain integral related to the fission source is transformed into a series of boundary-only integrals, with the aid of the higher order fundamental solutions based on the spherical and the modified spherical Bessel functions. Since each degree of the higher order fundamental solutions in the 3-D cases has a singularity of order (1/r), the above series of boundary integrals requires additional terms which do not appear in the 2-D MRM formulation. The critical eigenvalue itself can be also described using only boundary integrals. Test calculations show that Wielandt's spectral shift technique guarantees rapid and stable convergence of 3-D MRM computations. (author)
International Nuclear Information System (INIS)
Blink, J.A.; Dye, R.E.; Kimlinger, J.R.
1981-12-01
Calculation of neutron activation of proposed fusion reactors requires a library of neutron-activation cross sections. One such library is ACTL, which is being updated and expanded by Howerton. If the energy-dependent neutron flux is also known as a function of location and time, the buildup and decay of activation products can be calculated. In practice, hand calculation is impractical without energy-averaged cross sections because of the large number of energy groups. A widely used activation computer code, ORIGEN2, also requires energy-averaged cross sections. Accordingly, we wrote the ORLIB code to collapse the ACTL library, using the flux as a weighting function. The ORLIB code runs on the LLNL Cray computer network. We have also modified ORIGEN2 to accept the expanded activation libraries produced by ORLIB
Papasotiriou, P. J.; Geroyannis, V. S.
We implement Hartle's perturbation method to the computation of relativistic rigidly rotating neutron star models. The program has been written in SCILAB (© INRIA ENPC), a matrix-oriented high-level programming language. The numerical method is described in very detail and is applied to many models in slow or fast rotation. We show that, although the method is perturbative, it gives accurate results for all practical purposes and it should prove an efficient tool for computing rapidly rotating pulsars.
Computational investigations on a catenary-shaped double-reflecting neutron guide
International Nuclear Information System (INIS)
Priesmeyer, H.G.
1983-01-01
The results of Monte-Carlo calculations of the neutron transmission of a vertical catenary-shaped neutron guide are presented. A two-dimensional problem was considered. Focussing and special coatings are investigated. (orig.) [de
Energy Technology Data Exchange (ETDEWEB)
Schneider, E.A. [Department of Mechanical Engineering, University of Texas, Austin, TX (United States); Deinert, M.R. [Theoretical and Applied Mechanics, Cornell University, 219 Kimball Hall, Ithaca, NY 14853 (United States)]. E-mail: mrd6@cornell.edu; Cady, K.B. [Theoretical and Applied Mechanics, Cornell University, 219 Kimball Hall, Ithaca, NY 14853 (United States)
2006-10-15
The balance of isotopes in a nuclear reactor core is key to understanding the overall performance of a given fuel cycle. This balance is in turn most strongly affected by the time and energy-dependent neutron flux. While many large and involved computer packages exist for determining this spectrum, a simplified approach amenable to rapid computation is missing from the literature. We present such a model, which accepts as inputs the fuel element/moderator geometry and composition, reactor geometry, fuel residence time and target burnup and we compare it to OECD/NEA benchmarks for homogeneous MOX and UOX LWR cores. Collision probability approximations to the neutron transport equation are used to decouple the spatial and energy variables. The lethargy dependent neutron flux, governed by coupled integral equations for the fuel and moderator/coolant regions is treated by multigroup thermalization methods, and the transport of neutrons through space is modeled by fuel to moderator transport and escape probabilities. Reactivity control is achieved through use of a burnable poison or adjustable control medium. The model calculates the buildup of 24 actinides, as well as fission products, along with the lethargy dependent neutron flux and the results of several simulations are compared with benchmarked standards.
International Nuclear Information System (INIS)
Fehrenbacher, G.; Meckbach, R.; Paretzke, H.G.
1996-01-01
The dependence of the shape of the right-sided broadening of the inelastic scattering peak at 692 keV in the pulse-height distribution measured with a Ge detector in fast neutron fields on the energy of the incident neutrons has been analyzed. A model incorporating the process contributing to the energy deposition that engender the peak, including the partitioning of the energy deposition by the Ge recoils, was developed. With a Monte Carlo code based on this model, the detector response associated with this peak was computed and compared with results of measurements with quasi-monoenergetic neutrons for energies between 0.88 and 2.1 MeV. A set of 80 response functions for neutron energies in the range from the reaction threshold at 0.7 to 6 MeV was computed, which will serve as a starting point for methods, which aim at obtaining information on the spectral distribution of fast neutron fields for this energy range from measurements with a Ge detector. (orig.)
International Nuclear Information System (INIS)
Nigg, D.W.; Wemple, C.A.; Hartwell, J.K.; Harker, Y.D.; Venhuizen, J.R.; Risler, R.
1997-12-01
A closed-form direct method for unfolding neutron spectra from foil activation data is presented. The method is applied to measurements of the free-field neutron spectrum produced by the proton-cyclotron-based fast-neutron radiotherapy facility at the University of Washington (UW) School of Medicine. The results compare favorably with theoretical expectations based on an a-priori calculational model of the target and neutron beamline configuration of the UW facility
Wangerin, K; Culbertson, C N; Jevremovic, T
2005-08-01
The goal of this study was to evaluate the COG Monte Carlo radiation transport code, developed and tested by Lawrence Livermore National Laboratory, for gadolinium neutron capture therapy (GdNCT) related modeling. The validity of COG NCT model has been established for this model, and here the calculation was extended to analyze the effect of various gadolinium concentrations on dose distribution and cell-kill effect of the GdNCT modality and to determine the optimum therapeutic conditions for treating brain cancers. The computational results were compared with the widely used MCNP code. The differences between the COG and MCNP predictions were generally small and suggest that the COG code can be applied to similar research problems in NCT. Results for this study also showed that a concentration of 100 ppm gadolinium in the tumor was most beneficial when using an epithermal neutron beam.
International Nuclear Information System (INIS)
Avdic, S.; Pesic, M.
1992-01-01
The ORTEC 580 Neutron Spectrometer system contains a detector unit in diode coincidence arrangement for measurement of fast neutron spectrum in the energy range from 1 MeV to 14 MeV. Numerical code HE3 for computation of semiconductor 3 He detector efficiency in a collimated neutron beam is based on analytical method in infinite diode approximation and Monte Carlo method for real spectrometer geometry. Calculations are performed in the first collision approximation in the detector active volume including evaluation of correction factors. Accuracy of relative detector efficiency calculation is improved by using neutron cross section from nuclear library ENDF/B-6. (author)
Directory of Open Access Journals (Sweden)
Kaoru Sakasai
2017-08-01
Full Text Available Neutron devices such as neutron detectors, optical devices including supermirror devices and 3He neutron spin filters, and choppers are successfully developed and installed at the Materials Life Science Facility (MLF of the Japan Proton Accelerator Research Complex (J-PARC, Tokai, Japan. Four software components of MLF computational environment, instrument control, data acquisition, data analysis, and a database, have been developed and equipped at MLF. MLF also provides a wide variety of sample environment options including high and low temperatures, high magnetic fields, and high pressures. This paper describes the current status of neutron devices, computational and sample environments at MLF.
International Nuclear Information System (INIS)
Azmy, Y. Y.
2004-01-01
An approach is developed for solving the neutron diffusion equation on combinatorial geometry computational cells, that is computational cells composed by combinatorial operations involving simple-shaped component cells. The only constraint on the component cells from which the combinatorial cells are assembled is that they possess a legitimate discretization of the underlying diffusion equation. We use the Finite Difference (FD) approximation of the x, y-geometry diffusion equation in this work. Performing the same combinatorial operations involved in composing the combinatorial cell on these discrete-variable equations yields equations that employ new discrete variables defined only on the combinatorial cell's volume and faces. The only approximation involved in this process, beyond the truncation error committed in discretizing the diffusion equation over each component cell, is a consistent-order Legendre series expansion. Preliminary results for simple configurations establish the accuracy of the solution to the combinatorial geometry solution compared to straight FD as the system dimensions decrease. Furthermore numerical results validate the consistent Legendre-series expansion order by illustrating the second order accuracy of the combinatorial geometry solution, the same as standard FD. Nevertheless the magnitude of the error for the new approach is larger than FD's since it incorporates the additional truncated series approximation. (authors)
International Nuclear Information System (INIS)
Mansur, Ralph S.; Barros, Ricardo C.
2011-01-01
We describe a method to determine the neutron scalar flux in a slab using monoenergetic diffusion model. To achieve this goal we used three ingredients in the computational code that we developed on the Scilab platform: a spectral nodal method that generates numerical solution for the one-speed slab-geometry fixed source diffusion problem with no spatial truncation errors; a spatial reconstruction scheme to yield detailed profile of the coarse-mesh solution; and an angular reconstruction scheme to yield approximately the neutron angular flux profile at a given location of the slab migrating in a given direction. Numerical results are given to illustrate the efficiency of the offered code. (author)
International Nuclear Information System (INIS)
Santoro, R.T.; Maskewitz, B.F.; Roussin, R.W.; Trubey, D.K.
1976-01-01
The activities of the Radiation Shielding Information Center (RSIC) of the Oak Ridge National Laboratory are being utilized in support of fusion reactor technology. The major activities of RSIC include the operation of a computer-based information storage and retrieval system, the collection, packaging, and distribution of large computer codes, and the compilation and dissemination of processed and evaluated data libraries, with particular emphasis on neutron and gamma-ray cross-section data. The Center has acquired thirteen years of experience in serving fission reactor, weapons, and accelerator shielding research communities, and the extension of its technical base to fusion reactor research represents a logical progression. RSIC is currently working with fusion reactor researchers and contractors in computer code development to provide tested radiation transport and shielding codes and data library packages. Of significant interest to the CTR community are the 100 energy group neutron and 21 energy group gamma-ray coupled cross-section data package (DLC-37) for neutronics studies, a comprehensive 171 energy group neutron and 36 energy group gamma-ray coupled cross-section data base with retrieval programs, including resonance self-shielding, that are tailored to CTR application, and a data base for the generation of energy-dependent atomic displacement and gas production cross sections and heavy-particle-recoil spectra for estimating radiation damage to CTR structural components
Coincident Detection Significance in Multimessenger Astronomy
Ashton, G.; Burns, E.; Dal Canton, T.; Dent, T.; Eggenstein, H.-B.; Nielsen, A. B.; Prix, R.; Was, M.; Zhu, S. J.
2018-06-01
We derive a Bayesian criterion for assessing whether signals observed in two separate data sets originate from a common source. The Bayes factor for a common versus unrelated origin of signals includes an overlap integral of the posterior distributions over the common-source parameters. Focusing on multimessenger gravitational-wave astronomy, we apply the method to the spatial and temporal association of independent gravitational-wave and electromagnetic (or neutrino) observations. As an example, we consider the coincidence between the recently discovered gravitational-wave signal GW170817 from a binary neutron star merger and the gamma-ray burst GRB 170817A: we find that the common-source model is enormously favored over a model describing them as unrelated signals.
A generalized model for coincidence counting
International Nuclear Information System (INIS)
Lu, Ming-Shih; Teichmann, T.
1992-01-01
The aim of this paper is to provide a description of the multiplicative processes associated with coincidence counting techniques, for example in the NDA of plutonium bearing materials. The model elucidates both the physical processes and the underlying mathematical formalism in a relatively simple but comprehensive way. In particular, it includes the effect of absorption by impurities or poisons, as well as that of neutron leakage on a parallel basis to the treatment of induced fission itself. The work thus parallels and generalizes the methods of Boehnel of Hage and Cifarelli, and more recently of Yanjushkin. This paper introduces the concept of a dual probability generating function to account for both the basic physical multiplication phenomena, as well as the detection phenomena. The underlying approach extends the idea of a simple probability generating function, due to De Moivre. The basic mathematical background may be found, for example, in Feller 1966
Development of coincidence processing module for PEM
International Nuclear Information System (INIS)
Feng Baotong; Shuai Lei; Li Ke
2011-01-01
For the breast cancer diagnosis and therapy, a prototype of positron emission mammography (PEM) was developed in Institute of High Energy Physics, Chinese Academy of Sciences. In this paper, the design of coincidence processing module (CPM) for this PEM was presented. Both the hardware architecture and the software logic were introduced. In this design, the CPM used the Rocket IO fast interface in FPGA and fiber technology to acquire the preprocessed data from the continuous sampling module (CSM) and then selected the valid event with the coincidence timing window method, which was performed in the FPGA on the daughter board. The CPM transmits the processed data to host computer via gigabit Ethernet. The whole system was controlled by CAN bus. The primary tests indicate that the performance of this design is good. (authors)
International Nuclear Information System (INIS)
Kolev, N.A.
1981-07-01
A mathematical model based on the three group theory for theoretical calculation by means of computer of the calibration curves of neutron soil moisture probes with highly effective counters, is described. Methods for experimental correction of the mathematical model are discussed and proposed. The computer programme described allows the calibration of neutron probes with high or low effective counters, and central or end geometry, with or without linearizing of the calibration curve. The use of two calculation variants and printing of output data gives the possibility not only for calibration, but also for other researches. The separate data inputs for soil and probe temperature allow the temperature influence analysis. The computer programme and calculation examples are given. (author)
Energy Technology Data Exchange (ETDEWEB)
Bilheux, Hassina Z [ORNL; Bilheux, Jean-Christophe [ORNL; Tremsin, Anton S [University of California, Berkeley; Santodonato, Louis J [ORNL; Dehoff, Ryan R [ORNL; Kirka, Michael M [ORNL; Bailey, William Barton [ORNL; Keener, Wylie S [ORNL; Herwig, Kenneth W [ORNL
2015-01-01
The Oak Ridge National Laboratory (ORNL) Neutron Sciences Directorate (NScD) has installed a neutron imaging (NI) beam line at the High Flux Isotope Reactor (HFIR) cold guide hall. The CG-1D beam line produces cold neutrons for a broad range of user research spanning from engineering to material research, additive manufacturing, vehicle technologies, archaeology, biology, and plant physiology. Recent efforts have focused on increasing flux and spatial resolution. A series of selected engineering applications is presented here. Historically and for more than four decades, neutron imaging (NI) facilities have been installed exclusively at continuous (i.e. reactor-based) neutron sources rather than at pulsed sources. This is mainly due to (1) the limited number of accelerator-based facilities and therefore the fierce competition for beam lines with neutron scattering instruments, (2) the limited flux available at accelerator-based neutron sources and finally, (3) the lack of high efficiency imaging detector technology capable of time-stamping pulsed neutrons with sufficient time resolution. Recently completed high flux pulsed proton-driven neutron sources such as the ORNL Spallation Neutron Source (SNS) at ORNL and the Japanese Spallation Neutron Source (JSNS) of the Japan Proton Accelerator Research Complex (J-PARC) in Japan produce high neutron fluxes that offer new and unique opportunities for NI techniques. Pulsed-based neutron imaging facilities RADEN and IMAT are currently being built at J-PARC and the Rutherford National Laboratory in the U.K., respectively. ORNL is building a pulsed neutron imaging beam line called VENUS to respond to the U.S. based scientific community. A team composed of engineers, scientists and designers has developed a conceptual design of the future VENUS imaging instrument at the SNS.
Quantitative neutron radiography using neutron absorbing honeycomb
International Nuclear Information System (INIS)
Tamaki, Masayoshi; Oda, Masahiro; Takahashi, Kenji; Ohkubo, Kohei; Tasaka, Kanji; Tsuruno, Akira; Matsubayashi, Masahito.
1993-01-01
This investigation concerns quantitative neutron radiography and computed tomography by using a neutron absorbing honeycomb collimator. By setting the neutron absorbing honeycomb collimator between object and imaging system, neutrons scattered in the object were absorbed by the honeycomb material and eliminated before coming to the imaging system, but the neutrons which were transmitted the object without interaction could reach the imaging system. The image by purely transmitted neutrons gives the quantitative information. Two honeycombs were prepared with coating of boron nitride and gadolinium oxide and evaluated for the quantitative application. The relation between the neutron total cross section and the attenuation coefficient confirmed that they were in a fairly good agreement. Application to quantitative computed tomography was also successfully conducted. The new neutron radiography method using the neutron-absorbing honeycomb collimator for the elimination of the scattered neutrons improved remarkably the quantitativeness of the neutron radiography and computed tomography. (author)
International Nuclear Information System (INIS)
Trindade, Bruno Machado
2011-02-01
This work shows the remodeling of the Computer System for Dosimetry of Neutrons and Photons in Radiotherapy Based on Stochastic Methods . SISCODES. The initial description and status, the alterations and expansions (proposed and concluded), and the latest system development status are shown. The SISCODES is a system that allows the execution of a 3D computational planning in radiation therapy, based on MCNP5 nuclear particle transport code. The SISCODES provides tools to build a patient's voxels model, to define a treatment planning, to simulate this planning, and to view the results of the simulation. The SISCODES implements a database of tissues, sources and nuclear data and an interface to access then. The graphical SISCODES modules were rewritten or were implemented using C++ language and GTKmm library. Studies about dose deviations were performed simulating a homogeneous water phantom as analogue of the human body in radiotherapy planning and a heterogeneous voxel phantom, pointing out possible dose miscalculations. The Soft-RT and PROPLAN computer codes that do interface with SISCODES are described. A set of voxels models created on the SISCODES are presented with its respective sizes and resolutions. To demonstrate the use of SISCODES, examples of radiation therapy and dosimetry simulations for prostate and heart are shown. Three protocols were simulated on the heart voxel model: Sm-153 filled balloon and P-32 stent, to prevent angioplasty restenosis; and Tl-201 myocardial perfusion, to imaging. Teletherapy with 6MV and 15MV beams were simulated to the prostate, and brachytherapy with I-125 seeds. The results of these simulations are shown on isodose curves and on dose-volume histograms. The SISCODES shows to be a useful tool for research of new radiation therapy treatments and, in future, can also be useful in medical practice. At the end, future improvements are proposed. I hope this work can contribute to develop more effective radiation therapy
International Nuclear Information System (INIS)
Hatsukawa, Yuichi; Oshima, Masumi; Toh, Yosuke; Shinohara, Nobuo; Kushita, Kosuke; Ueno, Takashi
2003-01-01
Multiparameter coincidence γ-ray spectrometry based on g-g coincidence is widely used in the field of nuclear structure studies, and has produced many successful results. In this study, feasibility of the method for neutron activation analysis of long lived iodine isotope, 129 I, was investigated. (author)
Licata, M.; Joyce, M. J.
2018-02-01
The potential of a combined and simultaneous fast-neutron/γ-ray computed tomography technique using Monte Carlo simulations is described. This technique is applied on the basis of a hypothetical tomography system comprising an isotopic radiation source (americium-beryllium) and a number (13) of organic scintillation detectors for the production and detection of both fast neutrons and γ rays, respectively. Via a combination of γ-ray and fast neutron tomography the potential is demonstrated to discern nuclear materials, such as compounds comprising plutonium and uranium, from substances that are used widely for neutron moderation and shielding. This discrimination is achieved on the basis of the difference in the attenuation characteristics of these substances. Discrimination of a variety of nuclear material compounds from shielding/moderating substances (the latter comprising lead or polyethylene for example) is shown to be challenging when using either γ-ray or neutron tomography in isolation of one another. Much-improved contrast is obtained for a combination of these tomographic modalities. This method has potential applications for in-situ, non-destructive assessments in nuclear security, safeguards, waste management and related requirements in the nuclear industry.
New approach to calculate the true-coincidence effect of HpGe detector
Energy Technology Data Exchange (ETDEWEB)
Alnour, I. A., E-mail: aaibrahim3@live.utm.my, E-mail: ibrahim.elnour@yahoo.com [Department of Physics, Faculty of Pure and Applied Science, International University of Africa, 12223 Khartoum (Sudan); Wagiran, H. [Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, 81310 UTM Skudai,Johor (Malaysia); Ibrahim, N. [Faculty of Defence Science and Technology, National Defence University of Malaysia, Kem Sungai Besi, 57000 Kuala Lumpur (Malaysia); Hamzah, S.; Elias, M. S. [Malaysia Nuclear Agency (MNA), Bangi, 43000 Kajang, Selangor D.E. (Malaysia); Siong, W. B. [Chemistry Department, Faculty of Resource Science & Technology, Universiti Malaysia Sarawak, 94300 Kota Samarahan, Sarawak (Malaysia)
2016-01-22
The corrections for true-coincidence effects in HpGe detector are important, especially at low source-to-detector distances. This work established an approach to calculate the true-coincidence effects experimentally for HpGe detectors of type Canberra GC3018 and Ortec GEM25-76-XLB-C, which are in operation at neutron activation analysis lab in Malaysian Nuclear Agency (NM). The correction for true-coincidence effects was performed close to detector at distances 2 and 5 cm using {sup 57}Co, {sup 60}Co, {sup 133}Ba and {sup 137}Cs as standard point sources. The correction factors were ranged between 0.93-1.10 at 2 cm and 0.97-1.00 at 5 cm for Canberra HpGe detector; whereas for Ortec HpGe detector ranged between 0.92-1.13 and 0.95-100 at 2 and 5 cm respectively. The change in efficiency calibration curve of the detector at 2 and 5 cm after correction was found to be less than 1%. Moreover, the polynomial parameters functions were simulated through a computer program, MATLAB in order to find an accurate fit to the experimental data points.
International Nuclear Information System (INIS)
Corge, C.
1967-01-01
The neutron induced resonances analysis aims to determine the neutrons characteristics, leading to the excitation energies, de-excitation probabilities by gamma radiation emission, by neutron emission or by fission, their spin, their parity... This document describes the methods developed, or adapted, the calculation schemes and the algorithms implemented to realize such analysis on a computer, from data obtained during time-of-flight experiments on the linear accelerator of Saclay. (A.L.B.)
Improvement of JCDS, a computational dosimetry system in JAEA for neutron capture therapy
International Nuclear Information System (INIS)
Kumada, Hiroaki; Yamamoto, Kazuyoshi; Matsumura, Akira; Yamamoto, Tetsuya; Nakagawa, Yoshinobu; Kageji, Teruyoshi
2006-01-01
JCDS, a computational dosimetry system for neutron capture therapy, was developed by Japan Atomic Energy Agency. The system has been sophisticated to facilitate dose planning so far. In dosimetry with JCDS for BNCT clinical trials at JRR-4, several absorbed doses and the dose distributions are determined by a voxel model consisted of 2x2x2mm 3 voxel cells. By using the detailed voxel model, accuracy of the dosimetry can be improved. Clinical trials for melanoma and head-and-neck cancer as well as brain tumor were started using hot version of JCDS in 2005. JCDS is also being of improved so as to enable a JCDS application to dosimetry by PHITS as well as dosimetry by MCNP. By using PHITS, total doses of a patient by a combined modality therapy, for example a combination of BNCT and proton therapy, can be estimated consistently. Moreover, PET images can be adopted in combination with CT and MRI images as a farsighted approach. JCDS became able to identify target regions by using the PET values. (author)
Video Histories, Memories, and Coincidences
DEFF Research Database (Denmark)
Kacunko, Slavko
2012-01-01
Looping images allows us to notice things that we have never noticed before. Looping a small but exquisite selection of the video tapes of Marcel Odenbach, Dieter Kiessling and Matthias Neuenhofer may allow the discovering of Histories, Coincidences, and Infinitesimal Aesthetics inscribed...
International Nuclear Information System (INIS)
Afanas'ev, A.M.
1987-01-01
The large-scale construction of atomic power stations results in a need for trainers to instruct power-station personnel. The present work considers one problem of developing training computer software, associated with the development of a high-speed algorithm for calculating the neutron field after control-rod (CR) shift by the operator. The case considered here is that in which training units are developed on the basis of small computers of SM-2 type, which fall significantly short of the BESM-6 and EC-type computers used for the design calculations, in terms of speed and memory capacity. Depending on the apparatus for solving the criticality problem, in a two-dimensional single-group approximation, the physical-calculation programs require ∼ 1 min of machine time on a BESM-6 computer, which translates to ∼ 10 min on an SM-2 machine. In practice, this time is even longer, since ultimately it is necessary to determine not the effective multiplication factor K/sub ef/, but rather the local perturbations of the emergency-control (EC) system (to reach criticality) and change in the neutron field on shifting the CR and the EC rods. This long time means that it is very problematic to use physical-calculation programs to work in dialog mode with a computer. The algorithm presented below allows the neutron field following shift of the CR and EC rods to be calculated in a few seconds on a BESM-6 computer (tens of second on an SM-2 machine. This high speed may be achieved as a result of the preliminary calculation of the influence function (IF) for each CR. The IF may be calculated at high speed on a computer. Then it is stored in the external memory (EM) and, where necessary, used as the initial information
Performance of an active well coincidence counter for HEU samples
International Nuclear Information System (INIS)
Ferrari, Francesca; Peerani, Paolo
2010-01-01
Neutron coincidence counting is the reference NDA technique used in nuclear safeguards to measure the mass of nuclear material in samples. For high-enriched uranium (HEU) samples active neutron interrogation is generally performed and the most common device used by nuclear inspectors is the Active Well Coincidence Counter (AWCC). Within her master thesis at the Polytechnic of Milan, the first author performed an intensive study on the characteristics and performances of the AWCC in order to assess the 235 U mass in HEU oxide samples at the PERLA laboratory of JRC. The work has been summarised in this paper that starts with the optimisation of the use of AWCC for nuclear safeguards, describing the calibration procedure, reporting results of a series of verification measurements, summarising the performances that can be obtained with this instruments during inspections at fuel production plants and concluding with the discussion of uncertainties related to these measurements.
International Nuclear Information System (INIS)
Dubois, J.
2011-01-01
In science, simulation is a key process for research or validation. Modern computer technology allows faster numerical experiments, which are cheaper than real models. In the field of neutron simulation, the calculation of eigenvalues is one of the key challenges. The complexity of these problems is such that a lot of computing power may be necessary. The work of this thesis is first the evaluation of new computing hardware such as graphics card or massively multi-core chips, and their application to eigenvalue problems for neutron simulation. Then, in order to address the massive parallelism of supercomputers national, we also study the use of asynchronous hybrid methods for solving eigenvalue problems with this very high level of parallelism. Then we experiment the work of this research on several national supercomputers such as the Titane hybrid machine of the Computing Center, Research and Technology (CCRT), the Curie machine of the Very Large Computing Centre (TGCC), currently being installed, and the Hopper machine at the Lawrence Berkeley National Laboratory (LBNL). We also do our experiments on local workstations to illustrate the interest of this research in an everyday use with local computing resources. (author) [fr
Zohreh Gholamzadeh; Seyed Mohammad Mirvakili; Hossein Khalafi
2015-01-01
Background: 241Am, 243Am, and 237Np isotopes are among the most radiotoxic components of spent nuclear fuel. Recently, researchers have planned different incineration scenarios for the highly radiotoxic elements of nuclear waste in critical reactors. Computational methods are widely used to predict burnup rates of such nuclear wastes that are used under fuel matrixes in critical reactors. Methods: In this work, the Monte Carlo N-particle transport code was used to calculate the neutronic b...
International Nuclear Information System (INIS)
Santoro, R.T.; Maskewitz, B.F.; Roussin, R.W.; Trubey, D.K.
1976-01-01
The activities of the Radiation Shielding Information Center (RSIC) of the Oak Ridge National Laboratory are being utilized in support of fusion reactor technology. The major activities of RSIC include the operation of a computer-based information storage and retrieval system, the collection, packaging, and distribution of large computer codes, and the compilation and dissemination of processed and evaluated data libraries, with particular emphasis on neutron and gamma-ray cross-section data. The Center has acquired thirteen years of experience in serving fission reactor, weapons, and accelerator shielding research communities, and the extension of its technical base to fusion reactor research represents a logical progression. RSIC is currently working with fusion reactor researchers and contractors in computer code development to provide tested radiation transport and shielding codes and data library packages. Of significant interest to the CTR community are the 100 energy group neutron and 21 energy group gamma-ray coupled cross-section data package (DLC-37) for neutronics studies, a comprehensive 171 energy group neutron and 36 energy group gamma-ray coupled cross-section data base with retrieval programs, including resonance self-shielding, that are tailored to CTR application, and a data base for the generation of energy-dependent atomic displacement and gas production cross sections and heavy-particle-recoil spectra for estimating radiation damage to CTR structural components. Since 1964, the Center has been involved in the international exchange of information, encouraged and supported by both government and interagency agreements; and to achieve an equally viable and successful program in fusion research, the reciprocal exchange of CTR data and computing technology is encouraged and welcomed
Software correction of scatter coincidence in positron CT
International Nuclear Information System (INIS)
Endo, M.; Iinuma, T.A.
1984-01-01
This paper describes a software correction of scatter coincidence in positron CT which is based on an estimation of scatter projections from true projections by an integral transform. Kernels for the integral transform are projected distributions of scatter coincidences for a line source at different positions in a water phantom and are calculated by Klein-Nishina's formula. True projections of any composite object can be determined from measured projections by iterative applications of the integral transform. The correction method was tested in computer simulations and phantom experiments with Positologica. The results showed that effects of scatter coincidence are not negligible in the quantitation of images, but the correction reduces them significantly. (orig.)
International Nuclear Information System (INIS)
Konshin, V.A.
1981-01-01
Neutron cross section calculational methods for actinides in the unresolved resonance energy range (1-150 kev) are discussed, with a special emphasis on calculation of width fluctuation factors for the generalized distribution, as well as for a sub-threshold fission. It is shown that the energy dependence of sub(J), the (n,n') -process competition and the structure in neutron cross section has to be taken into account in the energy range considered. Analysis of different approaches in the statistical theory for heavy nuclei neutron cross-section calculation is given, and it is shown to be important to allow for the (n,γf)-reaction in neutron cross section calculations for fissile nuclei. The use of the non-spherical potential, the Lorentzian spectral factor and the Fermi-gas model involving the collective modes enables to obtain the self-consistent data for all neutron cross sections, including σnγ. (author)
International Nuclear Information System (INIS)
Kumada, Hiroaki; Torii, Yoshiya
2002-09-01
A boron neutron capture therapy (BNCT) with epithermal neutron beam is expected to treat effectively for malignant tumor that is located deeply in the brain. It is indispensable to estimate preliminarily the irradiation dose in the brain of a patient in order to perform the epithermal neutron beam BNCT. Thus, the JAERI Computational Dosimetry System (JCDS), which can calculate the dose distributions in the brain, has been developed. JCDS is a software that creates a 3-dimensional head model of a patient by using CT and MRI images and that generates a input data file automatically for calculation neutron flux and gamma-ray dose distribution in the brain by the Monte Carlo code: MCNP, and that displays the dose distribution on the head model for dosimetry by using the MCNP calculation results. JCDS has any advantages as follows; By treating CT data and MRI data which are medical images, a detail three-dimensional model of patient's head is able to be made easily. The three-dimensional head image is editable to simulate the state of a head after its surgical processes such as skin flap opening and bone removal for the BNCT with craniotomy that are being performed in Japan. JCDS can provide information for the Patient Setting System to set the patient in an actual irradiation position swiftly and accurately. This report describes basic design and procedure of dosimetry, operation manual, data and library structure for JCDS (ver.1.0). (author)
Kumada, H
2002-01-01
A boron neutron capture therapy (BNCT) with epithermal neutron beam is expected to treat effectively for malignant tumor that is located deeply in the brain. It is indispensable to estimate preliminarily the irradiation dose in the brain of a patient in order to perform the epithermal neutron beam BNCT. Thus, the JAERI Computational Dosimetry System (JCDS), which can calculate the dose distributions in the brain, has been developed. JCDS is a software that creates a 3-dimensional head model of a patient by using CT and MRI images and that generates a input data file automatically for calculation neutron flux and gamma-ray dose distribution in the brain by the Monte Carlo code: MCNP, and that displays the dose distribution on the head model for dosimetry by using the MCNP calculation results. JCDS has any advantages as follows; By treating CT data and MRI data which are medical images, a detail three-dimensional model of patient's head is able to be made easily. The three-dimensional head image is editable to ...
Computational methods for the nuclear and neutron matter problems: Final report
International Nuclear Information System (INIS)
Kalos, M.H.; Chen, J.M.C.
1988-01-01
This paper discusses the following topics: variational Monte Carlo study of oxygen 16; microscopic calculations of alpha-neutron scattering; exact Monte Carlo treatment of the fermion problem; and random field method
A neutron spectrum unfolding computer code based on artificial neural networks
International Nuclear Information System (INIS)
Ortiz-Rodríguez, J.M.; Reyes Alfaro, A.; Reyes Haro, A.; Cervantes Viramontes, J.M.; Vega-Carrillo, H.R.
2014-01-01
The Bonner Spheres Spectrometer consists of a thermal neutron sensor placed at the center of a number of moderating polyethylene spheres of different diameters. From the measured readings, information can be derived about the spectrum of the neutron field where measurements were made. Disadvantages of the Bonner system are the weight associated with each sphere and the need to sequentially irradiate the spheres, requiring long exposure periods. Provided a well-established response matrix and adequate irradiation conditions, the most delicate part of neutron spectrometry, is the unfolding process. The derivation of the spectral information is not simple because the unknown is not given directly as a result of the measurements. The drawbacks associated with traditional unfolding procedures have motivated the need of complementary approaches. Novel methods based on Artificial Intelligence, mainly Artificial Neural Networks, have been widely investigated. In this work, a neutron spectrum unfolding code based on neural nets technology is presented. This code is called Neutron Spectrometry and Dosimetry with Artificial Neural networks unfolding code that was designed in a graphical interface. The core of the code is an embedded neural network architecture previously optimized using the robust design of artificial neural networks methodology. The main features of the code are: easy to use, friendly and intuitive to the user. This code was designed for a Bonner Sphere System based on a 6 LiI(Eu) neutron detector and a response matrix expressed in 60 energy bins taken from an International Atomic Energy Agency compilation. The main feature of the code is that as entrance data, for unfolding the neutron spectrum, only seven rate counts measured with seven Bonner spheres are required; simultaneously the code calculates 15 dosimetric quantities as well as the total flux for radiation protection purposes. This code generates a full report with all information of the unfolding
Dynamical model of computation of the rhodium self-powered neutron detector current
International Nuclear Information System (INIS)
Erben, O.; Slovacek, M.; Zerola, L.
1992-01-01
A model is presented for the calculation of the rhodium self-powered neutron detector current in dependence on the neutron flux density during reactor core transients. The total signal consists of a beta emission, prompt, and gamma component and a background signal. The model has been verified by means of experimental data obtained during measurements on the LVR-15 research reactor and at the Dukovany nuclear power plant. (author) 9 figs., 21 refs
International Nuclear Information System (INIS)
Singleterry, R.C. Jr.; Wilson, J.W.
1997-01-01
Extension of the high charge and energy (HZE) transport computer program HZETRN for angular transport of neutrons is considered. For this paper, only light ion transport, He 4 and lighter, will be analyzed using a pure solar proton source. The angular transport calculator is the ANISN/PC program which is being controlled by the HZETRN program. The neutron flux values are compared for straight-ahead transport and angular transport in one dimension. The shield material is aluminum and the target material is water. The thickness of these materials is varied; however, only the largest model calculated is reported which is 50 gm/cm 2 of aluminum and 100 gm/cm 2 of water. The flux from the ANISN/PC calculation is about two orders of magnitude lower than the flux from HZETRN for very low energy neutrons. It is only a magnitude lower for the neutrons in the 10 to 20 MeV range in the aluminum and two orders lower in the water. The major reason for this difference is in the transport modes: straight-ahead versus angular. The angular treatment allows a longer path length than the straight-ahead approximation. Another reason is the different cross section sets used by the ANISN/PC-BUGLE-80 mode and the HZETRN mode. The next step is to investigate further the differences between the two codes and isolate the differences to just the angular versus straight-ahead transport mode. Then, create a better coupling between the angular neutron transport and the charged particle transport
International Nuclear Information System (INIS)
Ivascu, M.
1983-10-01
Computer codes incorporating advanced nuclear models (optical, statistical and pre-equilibrium decay nuclear reaction models) were used to calculate neutron cross sections needed for fusion reactor technology. The elastic and inelastic scattering (n,2n), (n,p), (n,n'p), (n,d) and (n,γ) cross sections for stable molybdenum isotopes Mosup(92,94,95,96,97,98,100) and incident neutron energy from about 100 keV or a threshold to 20 MeV were calculated using the consistent set of input parameters. The hydrogen production cross section which determined the radiation damage in structural materials of fusion reactors can be simply deduced from the presented results. The more elaborated microscopic models of nuclear level density are required for high accuracy calculations
Energy Technology Data Exchange (ETDEWEB)
Lee, Yi-Kang, E-mail: yi-kang.lee@cea.fr
2016-11-01
Highlights: • Verification and validation of TRIPOLI-4 radiation transport calculations for ITER shielding benchmark. • Evaluation of CEA-V5.1.1 and FENDL-3.0 nuclear data libraries on D–T fusion neutron continuous energy transport calculations. • Advances in nuclear analyses for nuclear heating and radiation damage in iron. • This work also demonstrates that the “safety factors” concept is necessary in the nuclear analyses of ITER. - Abstract: With the growing interest in using the continuous-energy TRIPOLI-4{sup ®} Monte Carlo radiation transport code for ITER applications, a key issue that arises is whether or not the released TRIPOLI-4 code and its associated nuclear data libraries are verified and validated for the D–T fusion neutronics calculations. Previous published benchmark results of TRIPOLI-4 code on the ITER related activities have concentrated on the first wall loading, the reactor dosimetry, the nuclear heating, and the tritium breeding ratio. To enhance the TRIPOLI-4 verification and validation on neutron-gamma coupled calculations for fusion device application, the computational ITER shielding benchmark of M. E. Sawan was performed in this work by using the 2013 released TRIPOLI-4.9S code and the associated CEA-V5.1.1 data library. First wall, blanket, vacuum vessel and toroidal field magnet of the inboard and outboard components were fully modelled in this 1-D toroidal cylindrical benchmark. The 14.1 MeV source neutrons were sampled from a uniform isotropic distribution in the plasma zone. Nuclear responses including neutron and gamma fluxes, nuclear heating, and material damage indicator were benchmarked against previous published results. The capabilities of the TRIPOLI-4 code on the evaluation of above physics parameters were presented. The nuclear data library from the new FENDL-3.0 evaluation was also benchmarked against the CEA-V5.1.1 results for the neutron transport calculations. The results show that both data libraries
International Nuclear Information System (INIS)
Lee, Yi-Kang
2016-01-01
Highlights: • Verification and validation of TRIPOLI-4 radiation transport calculations for ITER shielding benchmark. • Evaluation of CEA-V5.1.1 and FENDL-3.0 nuclear data libraries on D–T fusion neutron continuous energy transport calculations. • Advances in nuclear analyses for nuclear heating and radiation damage in iron. • This work also demonstrates that the “safety factors” concept is necessary in the nuclear analyses of ITER. - Abstract: With the growing interest in using the continuous-energy TRIPOLI-4 ® Monte Carlo radiation transport code for ITER applications, a key issue that arises is whether or not the released TRIPOLI-4 code and its associated nuclear data libraries are verified and validated for the D–T fusion neutronics calculations. Previous published benchmark results of TRIPOLI-4 code on the ITER related activities have concentrated on the first wall loading, the reactor dosimetry, the nuclear heating, and the tritium breeding ratio. To enhance the TRIPOLI-4 verification and validation on neutron-gamma coupled calculations for fusion device application, the computational ITER shielding benchmark of M. E. Sawan was performed in this work by using the 2013 released TRIPOLI-4.9S code and the associated CEA-V5.1.1 data library. First wall, blanket, vacuum vessel and toroidal field magnet of the inboard and outboard components were fully modelled in this 1-D toroidal cylindrical benchmark. The 14.1 MeV source neutrons were sampled from a uniform isotropic distribution in the plasma zone. Nuclear responses including neutron and gamma fluxes, nuclear heating, and material damage indicator were benchmarked against previous published results. The capabilities of the TRIPOLI-4 code on the evaluation of above physics parameters were presented. The nuclear data library from the new FENDL-3.0 evaluation was also benchmarked against the CEA-V5.1.1 results for the neutron transport calculations. The results show that both data libraries can be
International Nuclear Information System (INIS)
Campioni, Guillaume; Mounier, Claude
2006-01-01
The main goal of the thesis about studies of cold neutrons sources (CNS) in research reactors was to create a complete set of tools to design efficiently CNS. The work raises the problem to run accurate simulations of experimental devices inside reactor reflector valid for parametric studies. On one hand, deterministic codes have reasonable computation times but introduce problems for geometrical description. On the other hand, Monte Carlo codes give the possibility to compute on precise geometry, but need computation times so important that parametric studies are impossible. To decrease this computation time, several developments were made in the Monte Carlo code TRIPOLI-4.4. An uncoupling technique is used to isolate a study zone in the complete reactor geometry. By recording boundary conditions (incoming flux), further simulations can be launched for parametric studies with a computation time reduced by a factor 60 (case of the cold neutron source of the Orphee reactor). The short response time allows to lead parametric studies using Monte Carlo code. Moreover, using biasing methods, the flux can be recorded on the surface of neutrons guides entries (low solid angle) with a further gain of running time. Finally, the implementation of a coupling module between TRIPOLI- 4.4 and the Monte Carlo code McStas for research in condensed matter field gives the possibility to obtain fluxes after transmission through neutrons guides, thus to have the neutron flux received by samples studied by scientists of condensed matter. This set of developments, involving TRIPOLI-4.4 and McStas, represent a complete computation scheme for research reactors: from nuclear core, where neutrons are created, to the exit of neutrons guides, on samples of matter. This complete calculation scheme is tested against ILL4 measurements of flux in cold neutron guides. (authors)
A neutron spectrum unfolding computer code based on artificial neural networks
Ortiz-Rodríguez, J. M.; Reyes Alfaro, A.; Reyes Haro, A.; Cervantes Viramontes, J. M.; Vega-Carrillo, H. R.
2014-02-01
The Bonner Spheres Spectrometer consists of a thermal neutron sensor placed at the center of a number of moderating polyethylene spheres of different diameters. From the measured readings, information can be derived about the spectrum of the neutron field where measurements were made. Disadvantages of the Bonner system are the weight associated with each sphere and the need to sequentially irradiate the spheres, requiring long exposure periods. Provided a well-established response matrix and adequate irradiation conditions, the most delicate part of neutron spectrometry, is the unfolding process. The derivation of the spectral information is not simple because the unknown is not given directly as a result of the measurements. The drawbacks associated with traditional unfolding procedures have motivated the need of complementary approaches. Novel methods based on Artificial Intelligence, mainly Artificial Neural Networks, have been widely investigated. In this work, a neutron spectrum unfolding code based on neural nets technology is presented. This code is called Neutron Spectrometry and Dosimetry with Artificial Neural networks unfolding code that was designed in a graphical interface. The core of the code is an embedded neural network architecture previously optimized using the robust design of artificial neural networks methodology. The main features of the code are: easy to use, friendly and intuitive to the user. This code was designed for a Bonner Sphere System based on a 6LiI(Eu) neutron detector and a response matrix expressed in 60 energy bins taken from an International Atomic Energy Agency compilation. The main feature of the code is that as entrance data, for unfolding the neutron spectrum, only seven rate counts measured with seven Bonner spheres are required; simultaneously the code calculates 15 dosimetric quantities as well as the total flux for radiation protection purposes. This code generates a full report with all information of the unfolding in
International Nuclear Information System (INIS)
Al-Taweel, M.H.
2015-01-01
It is a conventional practice in the design of nuclear reactor to introduce calculation of hot points to determine spatial variation for energy generated and then determine power distribution.The study had been carried out for core of a reactor type (MTR) by the neutronic code SQUID. In this study, we replace the reflector of the reactor by H 2 O instead of D 2 O as originally the reactor designed.From the study we conclude that the reactor can operates safely, to make sure of that we calculate the multiplication factor where their values ranged from (1.0854) when all control rods are up to (1.001)when three control rods are up.Also the values of hot points were calculated and compared with French documents results with D 2 O as a reflector where the difference is (0.19%), and with light water as reflector instead of heavy water was calculated.For different cases according to control rod position , the values of hot point ranged between (0.46) to (1.64) in case all control rods are up also the values of the average power distributed on different fuel cells were calculated in case of light water as reflector firstly with three control rods are down and the maximum value (2.13*10 -2 Μw).Secondly in case offour control rods are down, the maximum value (1.925*10 -2 Μw) we notice almost coincidence between the neutron flux distribution through the core of reactor and in different positions of control rods
International Nuclear Information System (INIS)
Larson, N.M.; Perey, F.G.
1980-11-01
A method is described for determining the parameters of a model from experimental data based upon the utilization of Bayes' theorem. This method has several advantages over the least-squares method as it is commonly used; one important advantage is that the assumptions under which the parameter values have been determined are more clearly evident than in many results based upon least squares. Bayes' method has been used to develop a computer code which can be utilized to analyze neutron cross-section data by means of the R-matrix theory. The required formulae from the R-matrix theory are presented, and the computer implementation of both Bayes' equations and R-matrix theory is described. Details about the computer code and compelte input/output information are given
International Nuclear Information System (INIS)
Schriewer, J.; Hehn, G.; Mattes, M.
1976-06-01
Transmission experiments for fast neutrons and pure materials offer the possibility to check the accuracy of nuclear data compilations by recalculating the measured discharge spectra. In this paper the calculations were mainly based on two Benchmark experiments with pure iron carried out at the Karlsruhe Nuclear Research Center. One of the experiments employed a 252 Cf fission source and spherically symmetric arrangement; the other was based on transmission of an iron cylinder by 14-MeV neutrons from a D+T source. The checking calculations were based on the data compilation ENDF/B-IV (occasionally also ENDF/B-III) and on the transport codes ANISN (1D) and DOT-2 (2D) with lined up ESTOQ (for calculating the first-collision source). The calculations with the Cf source showed good agreement with the results of measurement, whereas the checking of the arrangement with 14 MeV neutrons yielded a marked underestimation of the neutron flux density in the range of 2 MeV up to 14 MeV. The discussion of the results including the choice of codes was done on the basis of a literature review on the Benchmark experiments for iron with fast neutrons carried out until now. (orig.) [de
International Nuclear Information System (INIS)
Azmy, Y.Y.; Kirk, B.L.
1990-01-01
Modern parallel computer architectures offer an enormous potential for reducing CPU and wall-clock execution times of large-scale computations commonly performed in various applications in science and engineering. Recently, several authors have reported their efforts in developing and implementing parallel algorithms for solving the neutron diffusion equation on a variety of shared- and distributed-memory parallel computers. Testing of these algorithms for a variety of two- and three-dimensional meshes showed significant speedup of the computation. Even for very large problems (i.e., three-dimensional fine meshes) executed concurrently on a few nodes in serial (nonvector) mode, however, the measured computational efficiency is very low (40 to 86%). In this paper, the authors present a highly efficient (∼85 to 99.9%) algorithm for solving the two-dimensional nodal diffusion equations on the Sequent Balance 8000 parallel computer. Also presented is a model for the performance, represented by the efficiency, as a function of problem size and the number of participating processors. The model is validated through several tests and then extrapolated to larger problems and more processors to predict the performance of the algorithm in more computationally demanding situations
International Nuclear Information System (INIS)
Hiraoka, Eiichi
1988-01-01
The thermal neutron absorption coefficient is essentially different from the X-ray absorption coefficient. Each substance has a characteristic absorption coefficient regardless of its density. Neutron deams have the following features: (1) neutrons are not transmitted efficiently by low molecular weight substances, (2) they are transmitted efficiently by heavy metals, and (3) the transmittance differs among isotopes. Thus, neutron beams are suitable for cheking for foreign matters in heavy metals and testing of composites consisting of both heavy and light materials. A neutron source generates fast neutrons, which should be converted into thermal neutrons by reducing their energy. Major neutron souces include nuclear reactors, radioisotopes and particle accelerators. Photographic films and television systems are mainly used to observe neutron transmission images. Computers are employed for image processing, computerized tomography and three-dimensional analysis. The major applications of neutron radiography include inspection of neclear fuel; evaluation of material for airplane; observation of fuel in the engine and oil in the hydraulic systems in airplanes; testing of composite materials; etc. (Nogami, K.)
International Nuclear Information System (INIS)
Zee, S.K.
1987-01-01
A numeric algorithm and an associated computer code were developed for the rapid solution of the finite-difference method representation of the few-group neutron-diffusion equations on parallel computers. Applications of the numeric algorithm on both SIMD (vector pipeline) and MIMD/SIMD (multi-CUP/vector pipeline) architectures were explored. The algorithm was successfully implemented in the two-group, 3-D neutron diffusion computer code named DIFPAR3D (DIFfusion PARallel 3-Dimension). Numerical-solution techniques used in the code include the Chebyshev polynomial acceleration technique in conjunction with the power method of outer iteration. For inner iterations, a parallel form of red-black (cyclic) line SOR with automated determination of group dependent relaxation factors and iteration numbers required to achieve specified inner iteration error tolerance is incorporated. The code employs a macroscopic depletion model with trace capability for selected fission products' transients and critical boron. In addition to this, moderator and fuel temperature feedback models are also incorporated into the DIFPAR3D code, for realistic simulation of power reactor cores. The physics models used were proven acceptable in separate benchmarking studies
Energy Technology Data Exchange (ETDEWEB)
Corcoran, E.C. [Department of Chemistry and Chemical Engineering, Royal Military College of Canada, P.O. Box 17000, St. Forces, Kingston, Ont., K7K 7B4 (Canada)], E-mail: emily.corcoran@rmc.ca; Lewis, B.J.; Thompson, W.T. [Department of Chemistry and Chemical Engineering, Royal Military College of Canada, P.O. Box 17000, St. Forces, Kingston, Ont., K7K 7B4 (Canada); Hood, J. [Atomic Energy of Canada Ltd., Sheridan Park, 2251 Speakman Drive, Mississauga, Ont., L5K 1B2 (Canada); Akbari, F.; He, Z. [Atomic Energy of Canada Ltd., Chalk River Laboratories, Chalk River, Ont., K0J 1J0 (Canada); Reid, P. [Atomic Energy of Canada Ltd., Sheridan Park, 2251 Speakman Drive, Mississauga, Ont., L5K 1B2 (Canada)
2009-03-31
Burnable neutron absorbing materials are expected to be an integral part of the new fuel design for the Advanced CANDU [CANDU is as a registered trademark of Atomic Energy of Canada Limited.] Reactor. The neutron absorbing material is composed of gadolinia and dysprosia dissolved in an inert cubic-fluorite yttria-stabilized zirconia matrix. A thermodynamic model based on Gibbs energy minimization has been created to provide estimated phase equilibria as a function of composition and temperature. This work includes some supporting experimental studies involving X-ray diffraction.
BCG: a computer code for calculating neutron spectra and criticality in cells of fast reactors
International Nuclear Information System (INIS)
Leite, S.B.; Caldeira, A.D.; Garcia, R.D.M.
1988-01-01
The BCG code for determining the space and energy neutron flux distribution and criticality of fast reactor cylindrical cells is discussed. The code solves the unidimensional neutron transport equation together with interface current relations at each energy point in an unionized energy grid prepared for the cell and at an arbitrary number of spatial zones. While the spatial resolution is user specified, the energy dependence of the flux distribution is resolved according to the degree of variation in the reconstruced total microscopic cross sections of the atomic species in the cell. Results for a simplified fuel cell illustrate the high resolution and accuracy that can be obtained with the code. (author) [pt
International Nuclear Information System (INIS)
Sahni, D.C.; Sharma, A.
2000-01-01
The integral form of one-speed, spherically symmetric neutron transport equation with isotropic scattering is considered. Two standard problems are solved using normal mode expansion technique. The expansion coefficients are obtained by solving their singular integral equations. It is shown that these expansion coefficients provide a representation of all spherical harmonics moments of the angular flux as a superposition of Bessel functions. It is seen that large errors occur in the computation of higher moments unless we take certain precautions. The reasons for this phenomenon are explained. They throw some light on the failure of spherical harmonics method in treating spherical geometry problems as observed by Aronsson
Czech Academy of Sciences Publication Activity Database
Viani, Alberto; Sotiriadis, Konstantinos; Kumpová, Ivana; Mancini, L.; Appavou, M.-S.
2017-01-01
Roč. 33, č. 4 (2017), s. 402-417 ISSN 0109-5641 R&D Projects: GA MŠk(CZ) LO1219 Keywords : zinc phosphate cements * small angle neutron scattering * X-ray micro-computed tomography * X-ray powder diffraction * zinc oxide * acid-base cements Subject RIV: JJ - Other Materials OBOR OECD: Composites (including laminates, reinforced plastics, cermets, combined natural and synthetic fibre fabrics Impact factor: 4.070, year: 2016 https://www.sciencedirect.com/science/article/pii/S0109564116305127
Numerical coincidences and 'tuning' in cosmology
Rees, Martin J.
2004-01-01
Fred Hoyle famously drew attention to the significance of apparent coincidences in the energy levels of the carbon and oxygen nucleus. This paper addresses the possible implications of other coincidences in cosmology.
Coincident photoelectron spectroscopy on superconductors
International Nuclear Information System (INIS)
Voss, Stefan
2011-01-01
Aim of the performed experiments of this thesis was to attempt to detect Cooper pairs as carriers of the superconducting current directly by means of the photoelectric effect. The method of the coincident photoelectron spectroscopy aims thereby at the detection of two coherently emitted electrons by the interaction with a photon. Because electrostatic analyzers typically cover only a very small spatial angle, which goes along with very low coincidence rates, in connection with this thesis a time-of-flight projection system has been developed, which maps nearly the whole spatial angle on a position-resolving detector. The pulsed light source in form of special synchrotron radiation necessary for the measurement has been adjusted so weak, that only single photons could arrive at the sample. Spectroscoped were beside test measurements on silver layers both a lead monocrystal as representative of the classical BCS superconductors and monocrystalline Bi 2 Sr 2 CaCu 2 O 8 from the family of the high-temperature superconductors. With excitation energies up to 40 eV could be shown that sufficiently smooth and clean surfaces in the superconducting phase exhibit within the resolving power of about 0.5 eV no recognizable differences in comparison to the normally conducting phase. Beside these studies furthermore the simple photoemission at the different samples and especially in the case of the lead crystal is treated, because here no comparable results are known. Thereby the whole momentum space is discussed and the Fermi surface established as three-dimensional model, by means of which the measurement results are discussed. in the theoretical descriptions different models for the Cooper-pair production are presented, whereby to the momentum exchange with the crystal a special role is attributed, because this can only occur in direct excitations via discrete lattice vectors.
International Nuclear Information System (INIS)
Uddin, M.N.; Sarker, M.M.; Khan, M.J.H.; Islam, S.M.A.
2010-01-01
The aim of this study is to analyze the neutronic parameters of TRIGA Mark-II research reactor using the chain of NJOY-WIMS-CITATION computer codes based on evaluated nuclear data libraries CENDL-2.2 and JEFF-3.1.1. The nuclear data processing code NJOY99.0 has been employed to generate the 69 group WIMS library for the isotopes of TRIGA core. The cell code WIMSD-5B was used to generate the cross sections in CITATION format and then 3-dimensional diffusion code CITTATION was used to calculate the neutronic parameters of the TRIGA Mark-II research reactor. All the analyses were performed using the 7-group macroscopic cross section library. The CITATION test-runs using different cross section sets based on different models applied in WIMS calculations have shown a strong influence of those models on the final integral parameters. Some of the cells were specially treated with PRIZE options available in WIMSD-5B to take into account the fine structure of the flux gradient in the fuel-reflector interface region. It was observed that two basic parameters, the effective multiplication factor, k eff and the thermal neutron flux, were in good agreement among the calculated results with each other as well as the measured values. The maximum power densities at the hot spot were 1.0446E02 W/cc and 1.0426E02 W/cc for the libraries CENDL-2.2 and JEFF-3.1.1 respectively. The calculated total peaking factors 5.793 and 5.745 were compared to the original SAR value of 5.6325 as well as MCNP result. Consequently, this analysis will be helpful to enhance the neutronic calculations and also be used for the further thermal-hydraulics study of the TRIGA core.
International Nuclear Information System (INIS)
Dhairyawan, M.P.
1979-01-01
Neutrons of energies below 500 keV are important from the point of view of radiation protection of personnel working around reactors. However, as no neutron sources are available at lower energies, no measured values of neutron energy response are available between thermal and 0.5 MeV (but for Sb-Be source at 24 keV). The response functions in this range are, therefore, arrived at theoretically. After giving a comprehensive review of the work done in the field of response of moderated neutron detectors, a Monte Carlo method developed for this purpose is described and used to calculate energy response functions of the two spherical moderator-detector systems, namely, one using a central BF 3 counter and the other using 6 LiI(Eu) scintillator of 0.490 dia crystal. The polythene sphere diameter ranged from 2'' to 12''. The results obtained follow the trend predicted by other calculations and experiments, but are a definite improvement over them, because the most recent data on cross sections and angular distribution are used and the opacity of the detector i.e. the presence and size of the detector within the moderator is taken into account in the present calculations. The reasons for the discrepancies in the present results and those obtained earlier by other methods are discussed. The response of the Leake counter arrived at by the present method agrees very well with experimental calibration. (M.G.B.)
Computational methods for the nuclear and neutron matter problems. Progress report
International Nuclear Information System (INIS)
Kalos, M.H.
1979-01-01
A brief report is given of progress on the development of Monte Carlo methods for the treatment of both simplified and realistic models of extensive neutron and nuclear matter and, eventually, of finite nuclei. A wide class of algorithms that may allow the efficient sampling of the integrands required in calculating the energy expectations with useful trial wave functions was devised
Small angle neutron scattering analysis programs on the Rutherford Laboratory IBM 360/195 computers
International Nuclear Information System (INIS)
Knowles, K.J.; Johnson, M.W.
1980-06-01
The implementation and operation of the suite of programs used for the analysis of small angle neutron scattering data originally written at the ILL (Grenoble) is described. The programs make use of a circulating data file which is also described and may be used by a variety of data analysis programs. (author)
Dynamics of crystalline acetanilide: Analysis using neutron scattering and computer simulation
Hayward, R. L.; Middendorf, H. D.; Wanderlingh, U.; Smith, J. C.
1995-04-01
The unusual temperature dependence of several optical spectroscopic vibrational bands in crystalline acetanilide has been interpreted as providing evidence for dynamic localization. Here we examine the vibrational dynamics of crystalline acetanilide over a spectral range of ˜20-4000 cm-1 using incoherent neutron scattering experiments, phonon normal mode calculations and molecular dynamics simulations. A molecular mechanics energy function is parametrized and used to perform the normal mode analyses in the full configurational space of the crystal i.e., including the intramolecular and intermolecular degrees of freedom. One- and multiphonon incoherent inelastic neutron scattering intensities are calculated from harmonic analyses in the first Brillouin zone and compared with the experimental data presented here. Phonon dispersion relations and mean-square atomic displacements are derived from the harmonic model and compared with data derived from coherent inelastic neutron scattering and neutron and x-ray diffraction. To examine the temperature effects on the vibrations the full, anharmonic potential function is used in molecular dynamics simulations of the crystal at 80, 140, and 300 K. Several, but not all, of the spectral features calculated from the molecular dynamics simulations exhibit temperature-dependent behavior in agreement with experiment. The significance of the results for the interpretation of the optical spectroscopic results and possible improvements to the model are discussed.
Resolution of the neutron transport equation by massively parallel computer in the Cronos code
International Nuclear Information System (INIS)
Zardini, D.M.
1996-01-01
The feasibility of neutron transport problems parallel resolution by CRONOS code's SN module is here studied. In this report we give the first data about the parallel resolution by angular variable decomposition of the transport equation. Problems about parallel resolution by spatial variable decomposition and memory stage limits are also explained here. (author)
International Nuclear Information System (INIS)
Keney, G.S.
1981-08-01
A computer code has been written to calculate neutron induced activation of neutral-beam injector components and the corresponding dose rates as a function of geometry, component composition, and time after shutdown. The code, ACDOS1, was written in FORTRAN IV to calculate both activity and dose rates for up to 30 target nuclides and 50 neutron groups. Sufficient versatility has also been incorporated into the code to make it applicable to a variety of general activation problems due to neutrons of energy less than 20 MeV
International Nuclear Information System (INIS)
Wolschke, U.
1986-08-01
Estelle is a formal method of description, which was developed based on an extended state transition model for the specification of communication records and services. Regardless of the field of application, there are problems common to all systems in distributed systems, i.e. in communication systems as in process computer systems, which are to be specified. These include real time problems, such as waiting for events, reactions to expected events and those occurring at the correct time, reacting to unexpected events or those not occurring at the correct time, transmitting and receiving data and the synchronisation of process going on simultaneously. This work examines, using the example of a process computer-controlled neutron scatter experiment, whether Estelle is suitable for the specification of distributed real time systems in this field of application. (orig.) [de
Energy Technology Data Exchange (ETDEWEB)
Gholamzadeh, Zohreh; Mirvakili, Seyed Mohammad; Khalafi, Hossein [Reactor Research School, Nuclear Science and Technology Research Institute, Tehran (Iran, Islamic Republic of)
2015-02-15
241Am, 243Am, and 237Np isotopes are among the most radiotoxic components of spent nuclear fuel. Recently, researchers have planned different incineration scenarios for the highly radiotoxic elements of nuclear waste in critical reactors. Computational methods are widely used to predict burnup rates of such nuclear wastes that are used under fuel matrixes in critical reactors. In this work, the Monte Carlo N-particle transport code was used to calculate the neutronic behavior of a transuranic (TRU)-bearing CANada Deuterium Uranium 6 reactor. The computational data showed that the 1.0% TRU-containing thorium-based fuel matrix presents higher proliferation resistance and TRU depletion rate than the other investigated fuel Matrixes. The fuel matrix includes higher negative temperature reactivity coefficients as well. The investigated thorium-based fuel matrix can be successfully used to decrease the production of highly radiotoxic isotopes.
Using CHIMERA detector at LNS for gamma-particle coincidences
Directory of Open Access Journals (Sweden)
Cardella G.
2016-01-01
Full Text Available We have recently evaluated the quality of γ-ray angular distributions that can be extracted in particle-gamma coincidence measurements using the CHIMERA detector at LNS. γ-rays have been detected using the CsI(Tl detectors of the spherical part of the CHIMERA array. Very clean γ-rays angular distributions were extracted in reactions induced by different stable beams impinging on 12C thin targets. The results evidenced an effect of projectile spin flip on the γ-rays angular distributions. γ-particle coincidence measurements were also performed in reactions induced by neutron rich exotic beams produced through in-flight fragmentation at LNS. In recent experiments also the Farcos array was used to improve energy and angular resolution measurements of the detected charged particles. Results obtained with both stable and radioactive beams are reported.
Asres, Yihunie Hibstie; Mathuthu, Manny; Birhane, Marelgn Derso
2018-04-22
This study provides current evidence about cross-section production processes in the theoretical and experimental results of neutron induced reaction of uranium isotope on projectile energy range of 1-100 MeV in order to improve the reliability of nuclear stimulation. In such fission reactions of 235 U within nuclear reactors, much amount of energy would be released as a product that able to satisfy the needs of energy to the world wide without polluting processes as compared to other sources. The main objective of this work is to transform a related knowledge in the neutron-induced fission reactions on 235 U through describing, analyzing and interpreting the theoretical results of the cross sections obtained from computer code COMPLET by comparing with the experimental data obtained from EXFOR. The cross section value of 235 U(n,2n) 234 U, 235 U(n,3n) 233 U, 235 U(n,γ) 236 U, 235 U(n,f) are obtained using computer code COMPLET and the corresponding experimental values were browsed by EXFOR, IAEA. The theoretical results are compared with the experimental data taken from EXFOR Data Bank. Computer code COMPLET has been used for the analysis with the same set of input parameters and the graphs were plotted by the help of spreadsheet & Origin-8 software. The quantification of uncertainties stemming from both experimental data and computer code calculation plays a significant role in the final evaluated results. The calculated results for total cross sections were compared with the experimental data taken from EXFOR in the literature, and good agreement was found between the experimental and theoretical data. This comparison of the calculated data was analyzed and interpreted with tabulation and graphical descriptions, and the results were briefly discussed within the text of this research work. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.
FPGA based computation of average neutron flux and e-folding period for start-up range of reactors
International Nuclear Information System (INIS)
Ram, Rajit; Borkar, S.P.; Dixit, M.Y.; Das, Debashis
2013-01-01
Pulse processing instrumentation channels used for reactor applications, play a vital role to ensure nuclear safety in startup range of reactor operation and also during fuel loading and first approach to criticality. These channels are intended for continuous run time computation of equivalent reactor core neutron flux and e-folding period. This paper focuses only the computational part of these instrumentation channels which is implemented in single FPGA using 32-bit floating point arithmetic engine. The computations of average count rate, log of average count rate, log rate and reactor period are done in VHDL using digital circuit realization approach. The computation of average count rate is done using fully adaptive window size moving average method, while Taylor series expansion for logarithms is implemented in FPGA to compute log of count rate, log rate and reactor e-folding period. This paper describes the block diagrams of digital logic realization in FPGA and advantage of fully adaptive window size moving average technique over conventional fixed size moving average technique for pulse processing of reactor instrumentations. (author)
A large data base on a small computer. Neutron Physics data and bibliography under IDMS
International Nuclear Information System (INIS)
Schofield, A.; Pellegrino, L.; Tubbs, N.
1978-01-01
The transfer of three associated files to an IDMS data base is reported: the CINDA bibliographic index to neutron physics publications, the cumulated EXFOR exchange tapes used for maintaining parallel data collections at all four centres and the CCDN's internal data storage and retrieval system NEUDADA. With associated dictionaries and inter-file conversion tables the corresponding IDMS data base will be about 160 Mbytes. The main characteristics of the three files are shown
A study of the responses of neutron dose equivalent survey meters with computer codes
International Nuclear Information System (INIS)
Sartori, D.E.; Beer, G.P. de
1983-01-01
The ANISN and DOT discrete-ordinates radiation transport codes for one and two dimensions have been proved as effective and simple techniques to study the response of dose equivalent neutron detectors. Comparisons between results of an experimental calibration of the Harwell 95/0075 survey meter and calculated results rendered satisfactory agreement, considering the different techniques and sources of error involved. Possible improvements in the methods and designs and causes of error are discussed. (author)
International Nuclear Information System (INIS)
Ropero, M.
1978-01-01
Efigie is a program written in Fortran V which can calculate the concentration of radionuclides produced by neutron irradiation of a target made of either a single isotope or several isotopes. The program includes optimization criteria that can be applied when the goal is the production of a single nuclide. The effect of a cooling time before chemical processing of the target is also accounted for.(author) [es
Improvement of Sodium Neutronic Nuclear Data for the Computation of Generation IV Reactors
International Nuclear Information System (INIS)
Archier, P.
2011-01-01
The safety criteria to be met for Generation IV sodium fast reactors (SFR) require reduced and mastered uncertainties on neutronic quantities of interest. Part of these uncertainties come from nuclear data and, in the particular case of SFR, from sodium nuclear data, which show significant differences between available international libraries (JEFF-3.1.1, ENDF/B-VII.0, JENDL-4.0). The objective of this work is to improve the knowledge on sodium nuclear data for a better calculation of SFR neutronic parameters and reliable associated uncertainties. After an overview of existing 23 Na data, the impact of the differences is quantified, particularly on sodium void reactivity effects, with both deterministic and stochastic neutronic codes. Results show that it is necessary to completely re-evaluate sodium nuclear data. Several developments have been made in the evaluation code Conrad, to integrate new nuclear reactions models and their associated parameters and to perform adjustments with integral measurements. Following these developments, the analysis of differential data and the experimental uncertainties propagation have been performed with Conrad. The resolved resonances range has been extended up to 2 MeV and the continuum range begins directly beyond this energy. A new 23 Na evaluation and the associated multigroup covariances matrices were generated for future uncertainties calculations. The last part of this work focuses on the sodium void integral data feedback, using methods of integral data assimilation to reduce the uncertainties on sodium cross sections. This work ends with uncertainty calculations for industrial-like SFR, which show an improved prediction of their neutronic parameters with the new evaluation. (author) [fr
Multiverse understanding of cosmological coincidences
International Nuclear Information System (INIS)
Bousso, Raphael; Hall, Lawrence J.; Nomura, Yasunori
2009-01-01
There is a deep cosmological mystery: although dependent on very different underlying physics, the time scales of structure formation, of galaxy cooling (both radiatively and against the CMB), and of vacuum domination do not differ by many orders of magnitude, but are all comparable to the present age of the universe. By scanning four landscape parameters simultaneously, we show that this quadruple coincidence is resolved. We assume only that the statistical distribution of parameter values in the multiverse grows towards certain catastrophic boundaries we identify, across which there are drastic regime changes. We find order-of-magnitude predictions for the cosmological constant, the primordial density contrast, the temperature at matter-radiation equality, the typical galaxy mass, and the age of the universe, in terms of the fine structure constant and the electron, proton and Planck masses. Our approach permits a systematic evaluation of measure proposals; with the causal patch measure, we find no runaway of the primordial density contrast and the cosmological constant to large values.
Optimising the neutron environment of Radiation Portal Monitors: A computational study
Energy Technology Data Exchange (ETDEWEB)
Gilbert, Mark R., E-mail: mark.gilbert@ccfe.ac.uk [United Kingdom Atomic Energy Authority, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Ghani, Zamir [United Kingdom Atomic Energy Authority, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); McMillan, John E. [Department of Physics and Astronomy, University of Sheffield, Hicks building, Hounsfield Road, Sheffield S3 7RH (United Kingdom); Packer, Lee W. [United Kingdom Atomic Energy Authority, Culham Science Centre, Abingdon OX14 3DB (United Kingdom)
2015-09-21
Efficient and reliable detection of radiological or nuclear threats is a crucial part of national and international efforts to prevent terrorist activities. Radiation Portal Monitors (RPMs), which are deployed worldwide, are intended to interdict smuggled fissile material by detecting emissions of neutrons and gamma rays. However, considering the range and variety of threat sources, vehicular and shielding scenarios, and that only a small signature is present, it is important that the design of the RPMs allows these signatures to be accurately differentiated from the environmental background. Using Monte-Carlo neutron-transport simulations of a model {sup 3}He detector system we have conducted a parameter study to identify the optimum combination of detector shielding, moderation, and collimation that maximises the sensitivity of neutron-sensitive RPMs. These structures, which could be simply and cost-effectively added to existing RPMs, can improve the detector response by more than a factor of two relative to an unmodified, bare design. Furthermore, optimisation of the air gap surrounding the helium tubes also improves detector efficiency.
International Nuclear Information System (INIS)
Glushkov, E.S.; Grebennik, V.N.; Davidenko, V.G.; Kosovskij, V.G.; Smirnov, O.N.; Tsibul'skij, V.F.
1991-01-01
The paper is dedicated to the consideration of uncertainties is neutron-physical characteristics (NPC) of high-temperature gas-cooled reactors (HTGR) with a core as spherical fuel element bed, which are caused by calculations from HTGR parameters mean values affecting NPC. Among NPC are: effective multiplication factor, burnup depth, reactivity effect, control element worth, distribution of neutrons and heat release over a reactor core, etc. The short description of calculated methods and codes used for HTGR calculations in the USSR is given and evaluations of NPC uncertainties of the methodical character are presented. Besides, the analysis of the effect technological deviations in parameters of reactor main elements such as uranium amount in the spherical fuel element, number of neutron-absorbing impurities in the reactor core and reflector, etc, upon the NPC is carried out. Results of some experimental studies of NPC of critical assemblies with graphite moderator are given as applied to HTGR. The comparison of calculations results and experiments on critical assemblies has made it possible to evaluate uncertainties of calculated description of HTGR NPC. (author). 8 refs, 8 figs, 6 tabs
International Nuclear Information System (INIS)
Vyropaev, V.Ya.; Zlokazov, V.B.; Kul'kina, L.I.; Maslov, O.D.; Fefilov, B.V.
1977-01-01
A computer program is described for processing gamma spectra in the instrumental activation analysis of multicomponent objects. Structural diagrams of various variants of connection with the computer are presented. The possibility of using a mini-computer as an analyser and for preliminary processing of gamma spectra is considered
Automatic classification of gammas-gamma coincidence matrices
International Nuclear Information System (INIS)
Los Arcos Merino, J. M.; Gonzalez, J. A.
1978-01-01
The information obtained during a coincidence experiment, recorded on magnetic tape by a MULTI-8 minicomputer, is transferred to a new tape in 36 bit words, using the program LEC0M8. The classification in two dimensional matrix form is carried out off-line, on a magnetic disk file, by the program CLAFI. On finishing classification one obtains a copy of the coincidence matrix on the second magnetic tape. Both programs are written to be processed in that order with the UNIVAC 1106 computer of J.E.N. (Author) 4 refs
Automatic classification of gamma-gamma coincidence matrices
International Nuclear Information System (INIS)
Los Arcos Merino, J.M.; Gonzalez Gonzalez, J.A.
1978-01-01
The information obtained during a coincidence experiment, recorded on magnetic tape by a Multi-8 minicomputer, is transferred to a new tape in 36 bit words, using the program Lecom8. The classification in two dimensional matrix form is carried out off-line, on a magnetic disk file, by the program Clafi. On finishing classification one obtains a copy of the coincidence matrix on the second magnetic tape. Both programs are written to be processed in that order with the Univac 1106 computer of J.E.N. (author)
International Nuclear Information System (INIS)
Buckel, G.
1983-01-01
The objectives are the development, testing and cultivation of reliable, efficient and user-optimized neutron-physical calculation methods and conformity with users' requirements concerning design of power reactors, planning and analysis of experiments necessary for their protection as well as research on physical key problems. A short outline of available computing programmes for the following objectives is given: - Provision of macroscopic group constants, - Calculation of neutron flux distribution in transport theory and diffusion approximation, - Evaluation of neutron flux-distribution, - Execution of disturbance calculations for the determination reactivity coefficients, and - graphical representation of results. (orig./RW) [de
Radiation doses from radiation sources of neutrons and photons by different computer calculation
International Nuclear Information System (INIS)
Siciliano, F.; Lippolis, G.; Bruno, S.G.
1995-12-01
In the present paper the calculation technique aspects of dose rate from neutron and photon radiation sources are covered with reference both to the basic theoretical modeling of the MERCURE-4, XSDRNPM-S and MCNP-3A codes and from practical point of view performing safety analyses of irradiation risk of two transportation casks. The input data set of these calculations -regarding the CEN 10/200 HLW container and dry PWR spent fuel assemblies shipping cask- is frequently commented as for as connecting points of input data and understanding theoric background are concerned
International Nuclear Information System (INIS)
Elmahroug, Y.; Tellili, B.; Souga, C.; Manai, K.
2015-01-01
Highlights: • Description of the theoretical method used by the ParShield program. • Description of the ParShield program. • Test and validation the ParShield program. - Abstract: This study aims to present a new computer program called ParShield which determines the neutron and gamma-ray shielding parameters. This program can calculate the total mass attenuation coefficients (μ t ), the effective atomic numbers (Z eff ) and the effective electron densities (N eff ) for gamma rays and it can also calculate the effective removal cross-sections (Σ R ) for fast neutrons for mixtures and compounds. The results obtained for the gamma rays by using ParShield were compared with the results calculated by the WinXcom program and the measured results. The obtained values of (Σ R ) were tested by comparing them with the measured results,the manually calculated results and with the results obtained by using MERCSFN program and an excellent agreement was found between them. The ParShield program can be used as a fast and effective tool to choose and compare the shielding materials, especially for the determination of (Z eff ) and (N eff ), there is no other programs in the literature which can calculate
Device for multi-dimensional γ-γ-coincidence study
International Nuclear Information System (INIS)
Gruzinova, T.M.; Erokhina, K.I.; Kutuzov, V.I.; Lemberg, I.Kh.; Petrov, S.A.; Revenko, V.S.; Senin, A.T.; Chugunov, I.N.; Shishlinov, V.M.
1977-01-01
A device for studying multi-dimensional γ-γ coincidences is described which operates on-line with the BESM-4 computer. The device comprises Ge(Li) detectors, analog-to-digital converters, shaper discriminators and fast amplifiers. To control the device operation as a whole and to elaborate necessary commands, an information distributor has been developed. The following specific features of the device operation are noted: the device may operate both in the regime of recording spectra of direct γ radiation in the block memory of multi-channel analyzer, and in the regime of data transfer to the computer memory; the device performs registration of coincidences; it transfers information to the computer which has a channel of direct access to the memory. The procedure of data processing is considered, the data being recorded on a magnetic tape. Partial spectra obtained are in a good agreement with data obtained elsewhere
Photoion spectroscopy of atoms using coincidence techniques
International Nuclear Information System (INIS)
Hayaishi, Tatsuji
1990-01-01
Interaction of atoms or molecules with photons causes many effects which are often obscured because of many decay paths from the event. To pick up an effect in the mixed-up ones, it is necessary to observe the decay path arising the effect alone. There is a coincidence technique in one of experimental means for the purpose of observing the decay path. In this article, two coincidence measurements are presented; a photoelectron-photoion coincidence technique and a threshold photoelectron-photoion coincidence technique. Furthermore, experimental facts of rare gases atoms obtained by the techniques are reviewed. (author)
It takes two—coincidence coding within the dual olfactory pathway of the honeybee
Brill, Martin F.; Meyer, Anneke; Rössler, Wolfgang
2015-01-01
To rapidly process biologically relevant stimuli, sensory systems have developed a broad variety of coding mechanisms like parallel processing and coincidence detection. Parallel processing (e.g., in the visual system), increases both computational capacity and processing speed by simultaneously coding different aspects of the same stimulus. Coincidence detection is an efficient way to integrate information from different sources. Coincidence has been shown to promote associative learning and...
International Nuclear Information System (INIS)
Masukawa, Fumihiro; Takano, Makoto; Naito, Yoshitaka; Yamazaki, Takao; Fujisaki, Masahide; Suzuki, Koichiro; Okuda, Motoi.
1993-11-01
In order to improve the accuracy and calculating speed of shielding analyses, MCNP 4, a Monte Carlo neutron and photon transport code system, has been parallelized and measured of its efficiency in the highly parallel distributed memory type computer, AP1000. The code has been analyzed statically and dynamically, then the suitable algorithm for parallelization has been determined for the shielding analysis functions of MCNP 4. This includes a strategy where a new history is assigned to the idling processor element dynamically during the execution. Furthermore, to avoid the congestion of communicative processing, the batch concept, processing multi-histories by a unit, has been introduced. By analyzing a sample cask problem with 2,000,000 histories by the AP1000 with 512 processor elements, the 82 % of parallelization efficiency is achieved, and the calculational speed has been estimated to be around 50 times as fast as that of FACOM M-780. (author)
International Nuclear Information System (INIS)
Yoo, Han Jong; Won, Jong Hyuck; Cho, Nam Zin
2011-01-01
In computational studies of neutron transport equations, the fine-group to few-group condensation procedure leads to equivalent total cross section that becomes angle dependent. The difficulty of this angle dependency has been traditionally treated by consistent P or extended transport approximation in the literature. In a previous study, we retained the angle dependency of the total cross section and applied directly to the discrete ordinates equation, with additional concept of angle-collapsing, and tested in a one-dimensional slab problem. In this study, we provide further results of this discrete ordinates-like method in comparison with the typical traditional methods. In addition, IRAM acceleration (based on Krylov subspace method) is tested for the purpose of further reducing the computational burden of few-group calculation. From the test results, it is ascertained that the angle-dependent total cross section with angle-collapsing gives excellent estimation of k_e_f_f and flux distribution and that IRAM acceleration effectively reduces the number of outer iterations. However, since IRAM requires sufficient convergence in inner iterations, speedup in total computer time is not significant for problems with upscattering. (author)
Coincidence summing corrections for positron emitters in germanium gamma spectrometry
International Nuclear Information System (INIS)
Richardson, A.E.; Sallee, W.W.; New Mexico State Univ., Las Cruces
1990-01-01
For positron emitters, 511 keV annihilation quanta are in coincidence with other gamma rays in the decay scheme. If the positrons are not localized at the point of decay, annihilation quanta will be produced at a site some distance from the point of emission. The magnitude of the summing coincidence effect will depend upon the position of annihilation. A method for determining the magnitude of the summing effect for a single gamma of energy E in coincidence with the annihilation gammas from non-localized positrons has been developed which makes use of the counting data for the full energy peaks for both the gamma ray (E) and the 511 keV annihilation gammas. With this data and efficiency calibration data one can determine the average total efficiency for the annihilation positions from which 511 keV gammas originate, and thereby obtain the summing correction factor, SCF, for gamma ray (E). Application of the method to a 22 Na NIST standard gave excellent agreement of observed emission rates for the 1275 keV gamma with the NIST value for wide ranging degrees of positron localization having summing correction factors ranging from 1.021 to 1.505. The method was also applied successfully to 58 Co in neutron-irradiated nickel foils. The method shows promise as a check on the accuracy of the efficiency calibration for a particular detector geometry at the 511 keV energy and energies for other gammas associated with positron emission. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Guasp, J; Navarro, C
1973-07-01
A FORTRAN V computer code for UNIVAC 1108/6 using a local Optical Model with spin-orbit interaction is described. The code calculates fast neutron cross sections, angular distribution, and Legendre moments for heavy and intermediate spherical nuclei. It allows for the possibility of automatic variation of potential parameters for experimental data fitting. (Author) 55 refs.
Computational methods for the nuclear and neutron matter problem. Progress report
International Nuclear Information System (INIS)
Kalos, M.H.; Carlson, J.; Panoff, R.; Schmidt, K.
1985-10-01
A new method is presented for treating fermion systems by Monte Carlo methods. This method is based on the concept of a ''mirror potential,'' which is a many-body potential that forces the Monte Carlo iteration to have a stable anti-symmetric component. The potential may be determined from the wave function and, within the framework of Green's Function Monte Carlo (GFMC), from the random walk whose density converges to the wave function. Further work has been given to the variational study of light nuclei. In particular, microscopic calculations of alpha-neutron scattering were performed. Techniques were also developed for performing variational calculations of heavier nuclei interacting with realistic interactions. A series of calculations on liquid 3 He at its experimental equilibrium density has also been done. 42 refs
National Research Council Canada - National Science Library
Labowski, Kristofer
2001-01-01
The Linear Characteristic (LC) method on rectangular boxoid meshes is a discrete ordinate neutron transport technique that uses both zeroth and first moments of the angular neutron flux to construct a relatively accurate...
Sensitivity to coincidences and paranormal belief.
Hadlaczky, Gergö; Westerlund, Joakim
2011-12-01
Often it is difficult to find a natural explanation as to why a surprising coincidence occurs. In attempting to find one, people may be inclined to accept paranormal explanations. The objective of this study was to investigate whether people with a lower threshold for being surprised by coincidences have a greater propensity to become believers compared to those with a higher threshold. Participants were exposed to artificial coincidences, which were formally defined as less or more probable, and were asked to provide remarkability ratings. Paranormal belief was measured by the Australian Sheep-Goat Scale. An analysis of the remarkability ratings revealed a significant interaction effect between Sheep-Goat score and type of coincidence, suggesting that people with lower thresholds of surprise, when experiencing coincidences, harbor higher paranormal belief than those with a higher threshold. The theoretical aspects of these findings were discussed.
International Nuclear Information System (INIS)
1999-01-01
CINDA, the Computer Index of Neutron Data, contains bibliographical references to measurements, calculations, reviews and evaluations of neutron cross-sections and other microscopic neutron data; it includes also index references to computer libraries of numerical neutron data available from four regional neutron data centres. The present issue, CINDA 99, is the second supplement to CINDA 97, the index to the literature on neutron data published after 1987. It supersedes the first supplement, CINDA 98. The complete CINDA file as of 1 June 1999 is contained in: the archival issue CINDA-A (5 volumes, 1990), CINDA 97 and the current issue CINDA 99. The compilation and publication of CINDA are the result of worldwide co-operation involving the following four data centres. Each centre is responsible for compiling the CINDA entries from the literature published in a defined geographical area given in brackets below: the USA National Nuclear Data Center at the Brookhaven National Laboratory, USA (United States of America and Canada); the Russian Nuclear Data Centre at the Fiziko-Energeticheskij Institut, Obninsk, Russian Federation (former USSR countries); the NEA Data Bank in Paris, France (European OECD member countries in Western Europe and Japan); and the IAEA Nuclear Data Section in Vienna, Austria (all other countries in Eastern Europe, Asia, Australia, Africa, Central and South America; also IAEA publications and translation journals). Besides the published CINDA books, up-to-date computer retrievals for specified CINDA information are currently available on request from the responsible CINDA centres, or via direct access to the on-line services as described in this publication
International Nuclear Information System (INIS)
Rezende, Gabriel Fonseca da Silva
2015-01-01
Many radiotherapy centers acquire 15 and 18 MV linear accelerators to perform more effective treatments for deep tumors. However, the acquisition of these equipment must be accompanied by an additional care in shielding planning of the rooms that will house them. In cases where space is restricted, it is common to find primary barriers made of concrete and metal. The drawback of this type of barrier is the photoneutron emission when high energy photons (e.g. 15 and 18 MV spectra) interact with the metallic material of the barrier. The emission of these particles constitutes a problem of radiation protection inside and outside of radiotherapy rooms, which should be properly assessed. A recent work has shown that the current model underestimate the dose of neutrons outside the treatment rooms. In this work, a computational model for the aforementioned problem was created from Monte Carlo Simulations and Artificial Intelligence. The developed model was composed by three neural networks, each being formed of a pair of material and spectrum: Pb18, Pb15 and Fe18. In a direct comparison with the McGinley method, the Pb18 network exhibited the best responses for approximately 78% of the cases tested; the Pb15 network showed better results for 100% of the tested cases, while the Fe18 network produced better answers to 94% of the tested cases. Thus, the computational model composed by the three networks has shown more consistent results than McGinley method. (author)
Software for the computized neutron data library of the SOKRATOR system
International Nuclear Information System (INIS)
Kolesov, V.E.; Krivtsov, A.S.; Solov'ev, N.A.
1976-01-01
When preparing data for nuclear reactors and shield computations using the evaluated nuclear data library it is necessary to have a set of special service programs to maintain the library itself. In this paper the structure of this set is discussed and a brief description of some programs is presented
International Nuclear Information System (INIS)
Kirk, B.L.; Azmy, Y.
1994-01-01
A modified scheme is developed for solving the two-dimensional nodal diffusion equations on distributed memory computers. The scheme is aimed at minimizing the volume of communication among processors while maximizing the tasks in parallel. Results show a significant improvement in parallel efficiency on the Intel iPSC/860 hypercube compared to previous algorithms
International Nuclear Information System (INIS)
Frankel, J.I.
1997-01-01
This investigation used sysmbolic manipulation in developing analytical methods and general computational strategies for solving both linear and nonlinear, regular and singular integral and integro-differential equations which appear in radiative and mixed-mode energy transport. Contained in this report are seven papers which present the technical results as individual modules
International Nuclear Information System (INIS)
Irvine, J.M.
1978-01-01
The subject is covered in chapters entitled: introduction (resume of stellar evolution, gross characteristics of neutron stars); pulsars (pulsar characteristics, pulsars as neutron stars); neutron star temperatures (neutron star cooling, superfluidity and superconductivity in neutron stars); the exterior of neutron stars (the magnetosphere, the neutron star 'atmosphere', pulses); neutron star structure; neutron star equations of state. (U.K.)
Energy Technology Data Exchange (ETDEWEB)
Bess, John D.; Briggs, J. Blair; Ivanova, Tatiana; Hill, Ian; Gulliford, Jim
2017-02-01
-generation reactor design, safety analysis requirements, and all other front- and back-end activities contributing to the overall nuclear fuel cycle where quality neutronics calculations are paramount.
Abramo, M C; Caccamo, C; Costa, D; Pellicane, G; Ruberto, R; Wanderlingh, U
2012-01-21
We report protein-protein structure factors of aqueous lysozyme solutions at different pH and ionic strengths, as determined by small-angle neutron scattering experiments. The observed upturn of the structure factor at small wavevectors, as the pH increases, marks a crossover between two different regimes, one dominated by repulsive forces, and another one where attractive interactions become prominent, with the ensuing development of enhanced density fluctuations. In order to rationalize such experimental outcome from a microscopic viewpoint, we have carried out extensive simulations of different coarse-grained models. We have first studied a model in which macromolecules are described as soft spheres interacting through an attractive r(-6) potential, plus embedded pH-dependent discrete charges; we show that the uprise undergone by the structure factor is qualitatively predicted. We have then studied a Derjaguin-Landau-Verwey-Overbeek (DLVO) model, in which only central interactions are advocated; we demonstrate that this model leads to a protein-rich/protein-poor coexistence curve that agrees quite well with the experimental counterpart; experimental correlations are instead reproduced only at low pH and ionic strengths. We have finally investigated a third, "mixed" model in which the central attractive term of the DLVO potential is imported within the distributed-charge approach; it turns out that the different balance of interactions, with a much shorter-range attractive contribution, leads in this latter case to an improved agreement with the experimental crossover. We discuss the relationship between experimental correlations, phase coexistence, and features of effective interactions, as well as possible paths toward a quantitative prediction of structural properties of real lysozyme solutions. © 2012 American Institute of Physics
International Nuclear Information System (INIS)
Watanabe, N.; Nishiguchi, R.; Shimomura, Y.
1991-01-01
Spatial distribution of point defects in displacement damage cascades at the early stage of their formation was simulated with the MARLOWE code for primary knock-on atoms which is relevant to D-T neutron irradiation. Calculations were carried out for Au, Ag, Cu, Ni and Al. Computer-simulated results were analyzed with complement of TEM observations of D-T neutron-irradiated metals at low temperature. The spatial configuration of displacement cascades, the size of small vacancy aggregates and the size of displacement damage cascade were examined. Results suggest that most of vacancy clusters which were formed in damage cascades may be as small as below 20 vacancies. The remarkable difference in defect yield of cascade damage in Ni and Cu is due to interstitial cluster formation and main contribution of cascade energy overlapping observed in cryotransfer TEM of D-T neutron-irradiated Au is due to ejected interstitials from cascade cores. (orig.)
International Nuclear Information System (INIS)
Schaefer, A.
1979-02-01
A new code for efficient solution of the multidimensional stationary multi-group, diffusion equation, to be used within a HTGR-code model, is presented. The approximation and iteration methods are described. Spacial approximation is based on the QUABOX-coarse-mesh method, but iteration methods are different from QUABOX to give linear dependence of computation time on the number of energy groups. Results for various multidimensional multi-group problems, among them the THTR pebble bed reactor are analyzed. It is shown, that computational labor for a 3D-case is reduced by about a factor 30 in comparison with conventional finite-difference-methods. Thus 3D-full-core calculations appear to be feasible for large HTGR's. (orig.) [de
Coincident effect characteristic in a thermoacoustic regenerator
International Nuclear Information System (INIS)
Liu Yicai; Xin Tianlong; Huang Qian; Shi Xiangnan; Chen Siming; Chen Lixin
2011-01-01
Many previous studies on characteristics of thermoacoustic regenerator are based on fluid micro-groups and their compression-expansion cycle. In this paper, coincident frequency is introduced to evaluate its acoustic characteristics by combining structural acoustic with structural vibration theories. The relationship among structure wave radiation and regenerator position, slab thickness, and properties of material are analyzed by numerical calculation. The results show that in the low-frequency thermoacoustic system, the coincident effect generated by higher frequency wave weakens the fundamental sound wave. While in the high-frequency thermoacoustic system, where the oscillating fundamental frequency is higher than the coincident frequency, the sound field strength is enhanced by stronger structure wave radiation because of the coincident effect.
A versatile fast coincidence system with memory
International Nuclear Information System (INIS)
Pouthas, J.
1976-01-01
A versatile fast coincidence system has been studied for experiments using several detectors. In this system, all the coincidence events are produced with an associated code, and thus, different kinds of events can be processed with the same experimental set-up. Also, the classification of the logical pulses gives the possibility of using a large number of ways (30 in this system). The setting of the system is very simple: there are only two time windows to adjust. (Auth.)
Simulation of triple coincidences in PET
International Nuclear Information System (INIS)
Cal-González, J; Herranz, E; Vicente, E; Udias, J M; Lage, E; Dave, S R; Parot, V; Herraiz, J L; Moore, S C; Park, M-A
2015-01-01
Although current PET scanners are designed and optimized to detect double coincidence events, there is a significant amount of triple coincidences in any PET acquisition. Triple coincidences may arise from causes such as: inter-detector scatter (IDS), random triple interactions (R T ), or the detection of prompt gamma rays in coincidence with annihilation photons when non-pure positron-emitting radionuclides are used (β + γ events). Depending on the data acquisition settings of the PET scanner, these triple events are discarded or processed as a set of double coincidences if the energy of the three detected events is within the scanner’s energy window. This latter option introduces noise in the data, as at most, only one of the possible lines-of-response defined by triple interactions corresponds to the line along which the decay occurred. Several novel works have pointed out the possibility of using triple events to increase the sensitivity of PET scanners or to expand PET imaging capabilities by allowing differentiation between radiotracers labeled with non-pure and pure positron-emitting radionuclides. In this work, we extended the Monte Carlo simulator PeneloPET to assess the proportion of triple coincidences in PET acquisitions and to evaluate their possible applications. We validated the results of the simulator against experimental data acquired with a modified version of a commercial preclinical PET/CT scanner, which was enabled to acquire and process triple-coincidence events. We used as figures of merit the energy spectra for double and triple coincidences and the triples-to-doubles ratio for different energy windows and radionuclides. After validation, the simulator was used to predict the relative quantity of triple-coincidence events in two clinical scanners assuming different acquisition settings. Good agreement between simulations and preclinical experiments was found, with differences below 10% for most of the observables considered. For
Energy Technology Data Exchange (ETDEWEB)
Souza, Maria Ines Silvani
2001-12-01
A third generation tomographic system using a parallel thermal neutron beam and gaseous position sensitive detector has been developed along three discrete phases. At the first one, X-ray tomographic images of several objects, using a position sensitive detector designed and constructed for this purpose have been obtained. The second phase involved the conversion of that detector for thermal neutron detection, by using materials capable to convert neutrons into detectable charged particles, testing afterwards its performance in a tomographic system by evaluation the quality of the image arising from several test-objects containing materials applicable in the engineering field. High enriched {sup 3} He, replacing the argon-methane otherwise used as filling gas for the X-ray detection, as well as, a gadolinium foil, have been utilized as converters. Besides the pure enriched {sup 3} He, its mixture with argon-methane and later on with propane, have been also tested, in order to evaluate the detector efficiency and resolution. After each gas change, the overall performance of the tomographic system using the modified detector, has been analyzed through measurements of the related parameters. This was done by analyzing the images produced by test-objects containing several materials having well known attenuation coefficients for both thermal neutrons and X-rays. In order to compare the performance of the position sensitive detector as modified to detect thermal neutrons, with that of a conventional BF{sub 3} detector, additional tomographs have been conducted using the last one. The results have been compared in terms of advantages, handicaps and complementary aspects for different kinds of radiation and materials. (author)
Energy Technology Data Exchange (ETDEWEB)
Corge, C
1967-07-01
The neutron induced resonances analysis aims to determine the neutrons characteristics, leading to the excitation energies, de-excitation probabilities by gamma radiation emission, by neutron emission or by fission, their spin, their parity... This document describes the methods developed, or adapted, the calculation schemes and the algorithms implemented to realize such analysis on a computer, from data obtained during time-of-flight experiments on the linear accelerator of Saclay. (A.L.B.)
Energy Technology Data Exchange (ETDEWEB)
Corge, C
1967-07-01
The neutron induced resonances analysis aims to determine the neutrons characteristics, leading to the excitation energies, de-excitation probabilities by gamma radiation emission, by neutron emission or by fission, their spin, their parity... This document describes the methods developed, or adapted, the calculation schemes and the algorithms implemented to realize such analysis on a computer, from data obtained during time-of-flight experiments on the linear accelerator of Saclay. (A.L.B.)
International Nuclear Information System (INIS)
Oblath, N.S.; Poon, A.W.P.
2000-01-01
The Sudbury Neutrino Observatory (SNO) has the ability to measure the total flux of all active flavors of neutrinos using the neutral current reaction, whose signature is a neutron. By comparing the rates of the neutral current reaction to the charged current reaction, which only detects electron neutrinos, one can test the neutrino oscillation hypothesis independent of solar models. It is necessary to understand the neutron detection efficiency of the detector to make use of the neutral current reaction. This report demonstrates a coincidence technique to identify neutrons emitted from the 252 Cf neutron calibration source. The source releases on average four neutrons when a 252 Cf nucleus spontaneously fissions. Each neutron is detected as a separate event when the neutron is captured by a deuteron, releasing a gamma ray of approximately 6.25 MeV. This gamma ray is in turn detected by the photomultiplier tube (PMT) array. By investigating the time and spatial separation between neutron-like events, it is possible to obtain a pure sample of neutrons for calibration study. Preliminary results of the technique applied to two calibration runs are presented
International Nuclear Information System (INIS)
Rohatgi, U.S.; Cheng, H.S.; Khan, H.J.; Mallen, A.N.; Neymotin, L.Y.
1998-03-01
This document is the User's Manual for the Boiling Water Reactor (BWR), and Simplified Boiling Water Reactor (SBWR) systems transient code RAMONA-4B. The code uses a three-dimensional neutron-kinetics model coupled with a multichannel, nonequilibrium, drift-flux, phase-flow model of the thermal hydraulics of the reactor vessel. The code is designed to analyze a wide spectrum of BWR core and system transients. Chapter 1 gives an overview of the code's capabilities and limitations; Chapter 2 describes the code's structure, lists major subroutines, and discusses the computer requirements. Chapter 3 is on code, auxillary codes, and instructions for running RAMONA-4B on Sun SPARC and IBM Workstations. Chapter 4 contains component descriptions and detailed card-by-card input instructions. Chapter 5 provides samples of the tabulated output for the steady-state and transient calculations and discusses the plotting procedures for the steady-state and transient calculations. Three appendices contain important user and programmer information: lists of plot variables (Appendix A) listings of input deck for sample problem (Appendix B), and a description of the plotting program PAD (Appendix C). 24 refs., 18 figs., 11 tabs
An advanced course in computational nuclear physics bridging the scales from quarks to neutron stars
Lombardo, Maria; Kolck, Ubirajara
2017-01-01
This graduate-level text collects and synthesizes a series of ten lectures on the nuclear quantum many-body problem. Starting from our current understanding of the underlying forces, it presents recent advances within the field of lattice quantum chromodynamics before going on to discuss effective field theories, central many-body methods like Monte Carlo methods, coupled cluster theories, the similarity renormalization group approach, Green’s function methods and large-scale diagonalization approaches. Algorithmic and computational advances show particular promise for breakthroughs in predictive power, including proper error estimates, a better understanding of the underlying effective degrees of freedom and of the respective forces at play. Enabled by recent improvements in theoretical, experimental and numerical techniques, the state-of-the art applications considered in this volume span the entire range, from our smallest components – quarks and gluons as the mediators of the strong force – to the c...
Analysis of 125Xe electron-photon coincidence decay
International Nuclear Information System (INIS)
Klingberg, F.J.; Biegalski, S.R.
2016-01-01
As part of the verification component of the Comprehensive Nuclear-Test-Ban Treaty (CTBT), environmental gas samples originating from nuclear fission are analyzed for the presence of 131m Xe, 133m Xe, 133 Xe, and 135 Xe. In this work, the non-traditional radioxenon isotope 125 Xe was investigated. The isotope was produced as an isotopically pure sample via neutron activation of 124 Xe at the University of Texas at Austin Nuclear Engineering Teaching Lab's TRIGA MARK II Reactor. The sample was then measured using a HPGe detector as well as an ARSA-style b-c coincidence detector. Potential sources and sensitivities for production of 125 Xe are also considered for relevance to the CTBT verification mission. (author)
Kalinichev, A. G.; Faraone, A.; Udovic, T.; Kolesnikov, A. I.; de Souza, N. R.; Reinholdt, M. X.; Kirkpatrick, R.
2008-12-01
Layered double hydroxides (LDHs, anionic clays) represent excellent model systems for detailed molecular- level studies of the structure, dynamics, and energetics of nano-confined water in mineral interlayers and nano-pores, because LDH interlayers can have a well-defined structures and contain H2O molecules and a wide variety of anions in structurally well-defined positions and coordinations. [Ca2Al(OH)6]Cl·2H2O, also known as hydrocalumite or Friedel's salt, has a well- ordered Ca,Al distribution in the hydroxide layer and a very high degree of H2O,Cl ordering in the interlayer. It is also one of the only LDH phase for which a single crystal structure refinement is available. Thus, it is currently the best model compound for understanding the structure and dynamical behavior of interlayer and surface species in other, less-ordered, LDHs. We investigated the structural and dynamic behavior of water in the interlayers of hydrocalumite using inelastic (INS) and quasielastic (QENS) neutron scattering and molecular dynamics computer simulations. The comperehensive neutron scattering studies were performed for one fully hydrated and one dehydrated sample of hydrocalumite using several complementary instruments (HFBS, DCS and FANS at NCNR; HRMECS and QENS at IPNS) at temperatures above and below the previously discovered order-disorder interlayer phase transition. Together the experimental and molecular modeling results capture the important details of the dynamics of nano-confined water and the effects of the orientational ordering of H2O molecules above and below the phase transition. They provide otherwise unobtainable experimental information about the transformation of H2O librational and diffusional modes across the order-disorder phase transition and significantly add to our current understanding of the structure and dynamics of water in LDH phases based on the earlier NMR, IR, X-ray, and calorimetric measurements. The approach can now be extended to probe the
International Nuclear Information System (INIS)
Kliem, S.; Grahn, A.; Rohde, U.; Schuetze, J.; Frank, Th.
2010-01-01
The computational fluid dynamics code ANSYS CFX has been coupled with the neutron-kinetic core model DYN3D. ANSYS CFX calculates the fluid dynamics and related transport phenomena in the reactors coolant and provides the corresponding data to DYN3D. In the fluid flow simulation of the coolant, the core itself is modeled within the porous body approach. DYN3D calculates the neutron kinetics and the fuel behavior including the heat transfer to the coolant. The physical data interface between the codes is the volumetric heat release rate into the coolant. In the prototype that is currently available, the coupling is restricted to single-phase flow problems. In the time domain an explicit coupling of the codes has been implemented so far. Steady-state and transient verification calculations for two small-size test problems confirm the correctness of the implementation of the prototype coupling. The first test problem was a mini-core consisting of nine real-size fuel assemblies with quadratic cross section. Comparison was performed with the DYN3D stand-alone code. In the steady state, the effective multiplication factor obtained by the DYN3D/ANSYS CFX codes hows a deviation of 9.8 pcm from the DYN3D stand-alone solution. This difference can be attributed to the use of different water property packages in the two codes. The transient test case simulated the withdrawal of the control rod from the central fuel assembly at hot zero power in the same mini-core. Power increase during the introduction of positive reactivity and power reduction due to fuel temperature increase are calculated in the same manner by the coupled and the stand-alone codes. The maximum values reached during the power rise differ by about 1 MW at a power level of 50 MW. Beside the different water property packages, these differences are caused by the use of different flow solvers. The same calculations were carried for a mini-core with seven real-size fuel assemblies with hexagonal cross section in
Coincidence method for determination of radionuclides activities
International Nuclear Information System (INIS)
Andrukhovich, S.K.; Berestov, A.V.; Rudak, E.A.
2004-01-01
The radon and radium activity measurements using six-crystal gamma-gamma coincidence, 4 -spectrometer PRIPJAT and radioactivity measurements in different samples of meat and vegetation by 32-crystal spectrometer ARGUS, are described. Radiation detector with 4 -geometry provides higher efficiency, and therefore shorter counting time than a detector without such geometry. However, its application is limited by the fact that obtained spectrum contains summing peaks of all γ-quanta registered in coincidence. Multiparameter information on coincident photon emission can be obtained only by a detection system where the 4 -geometry is made by many detectors, such are both the PRIPJAT and the ARGUS - γ-coincidence spectrometer of the Crystal Ball type in the Institute of Physics, Minsk [1,2]. There are other characteristics, as background conditions, energy and time resolution, makes it ve suitable for investigation of rare decays and interactions, cascade transitions, k intensity radiations etc. We are developing a method of 2 26R a and 2 26 Rn measurement by a multidetector 4 -spectrometer. The method is based on coincidence counting of γ-rays from two step cascade transitions that follow - decay of 2 14 Bi. Its application to the PRIPL spectrometer, which has 6 Nal(Tl) detectors, is presented here, as well as the method of the determination of radionuclide activities based on the registration of the cascades intensity of γ-rays of different multiplicity using ARGUS
Energy Technology Data Exchange (ETDEWEB)
Martinez B, M. R.; Ortiz R, J. M.; Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Av. Ramon Lopez Velarde No. 801, Col. Centro, Zacatecas (Mexico)], e-mail: mrosariomb@yahoo.com.mx
2009-10-15
By using the integrated accounts of spectrometric system of Bonner spheres is possible to reconstruct the neutron spectrum using various methods such as: Monte Carlo, the parameterization and iterative methods. The response matrix, counting rates and neutron spectrum are intimately related through the integral-differential of Fredholm of first type. however, the weight of Bonner spheres system, the procedure of spectra reconstruction, the need of a expert user, the high time consumption, the need to use a reconstruction code (BUNKI, SAND, among others) and the spectrum resolution, are some of problems that this system presents. The above difficulties have motivated the development of complementary procedures such as maximum entropy, genetic algorithms and artificial neural networks. In recent years, using neural network technology has become an alternative procedure in the nuclear science research area, considering a replacement for classical techniques used for years. In previous works, was used a new method called robust design methodology of artificial neural networks, to construct various network topologies capable of solving the problems of neutron spectrometry and dosimetry, however noted that not exist tools for end-user that allow test and validate the designed networks. This paper presents the development of a software for neutronic spectrometry and dosimetry, based on information extracted from an artificial neural network designed in previous work, through the robust design methodology of artificial neural networks with the following characteristics: was designed in a user graphical interface easy to use, speed on the application execution, unlike other deconvolution codes, not is necessary to select and initial spectrum for spectrum reconstruction, as an additional element to this tool, besides spectrum, the calculation is performed simultaneous of 13 equivalent dose from just counting rates from a spectrometric system of Bonner spheres. (Author)
International Nuclear Information System (INIS)
Barton, J.P.
1993-01-01
Neutron radiography (or radiology) is a diverse filed that uses neutrons of various energies, subthermal, thermal, epithermal or fast in either steady state or pulsed mode to examine objects for industrial, medical, or other purposes, both microscopic and macroscopic. The applications include engineering design, biological studies, nondestructive inspection and materials evaluation. In the past decade, over 100 different centers in some 30 countries have published reports of pioneering activities using reactors, accelerators and isotopic neutron sources. While film transparency and electronic video are most common imaging methods for static or in motion objects respectively, there are other important data gathering techniques, including track etch, digital gauging and computed tomography. A survey of the world-wide progress shows the field to be gaining steadily in its diversity, its sophistication and its importance. (author)
Computational methods for the nuclear and neutron matter problems: Progress report
International Nuclear Information System (INIS)
Kalos, M.H.
1989-01-01
This proposal is concerned with the use of Monte Carlo methods as a numerical technique in the study of nuclear structure. The straightforward use of Monte Carlo in nuclear physics has been impeded by certain technical difficulties. Foremost among them is the fact that numerical integration of the Schr/umlt o/dinger equation, by now straightforward for the ground state of boson systems, is substantially more difficult for many-fermion systems. The first part of this proposal outlines a synthesis of several advances into a single experimental algorithm. The proposed work is to implement and study the properties of the algorithm with simple models of few-body nuclei as the physical system to be investigated. Variational Monte Carlo remains an extremely powerful and useful method. Its application to nuclear structure physics presents unique difficulties. The varieties of interactions in the phenomenological potentials must be reflected in a corresponding richness of the correlations in accurate trial wave functions. Then the sheer number of terms in such trial fashions written as a product of pairs presents specific difficulties. We have had good success in our first experiments on a random field method that decouples the interactions and propose to extend our research to 16 O and to p-shell nuclei. Spin-orbit terms present special problems as well, because the implied gradient operators must be applied repeatedly. We propose to treat them in first order only, for now, and to calculate the result in three- and four-body nuclei. We propose a new Monte Carlo method for computing the amplitude of deuteron components in trial functions for heavier nuclei (here, specifically for 6 Li). The method is an extension of that used for off-diagonal matrix elements in quantum fluids
Quintessence, Cosmic Coincidence, and the Cosmological Constant
International Nuclear Information System (INIS)
Zlatev, I.; Wang, L.; Steinhardt, P.J.; Steinhardt, P.J.
1999-01-01
Recent observations suggest that a large fraction of the energy density of the Universe has negative pressure. One explanation is vacuum energy density; another is quintessence in the form of a scalar field slowly evolving down a potential. In either case, a key problem is to explain why the energy density nearly coincides with the matter density today. The densities decrease at different rates as the Universe expands, so coincidence today appears to require that their ratio be set to a specific, infinitesimal value in the early Universe. In this paper, we introduce the notion of a open-quotes tracker field,close quotes a form of quintessence, and show how it may explain the coincidence, adding new motivation for the quintessence scenario. copyright 1999 The American Physical Society
International Nuclear Information System (INIS)
Corge, Ch.
1969-01-01
Numerical analysis of transmission resonances induced by s wave neutrons in time-of-flight experiments can be achieved in a fairly automatic way on an IBM 7094/II computer. The involved computations are carried out following a four step scheme: 1 - experimental raw data are processed to obtain the resonant transmissions, 2 - values of experimental quantities for each resonance are derived from the above transmissions, 3 - resonance parameters are determined using a least square method to solve the over determined system obtained by equalling theoretical functions to the correspondent experimental values. Four analysis methods are gathered in the same code, 4 - graphical control of the results is performed. (author) [fr
Slow coincidences for CAMAC multiparameter analysis
International Nuclear Information System (INIS)
Akimov, Yu.K.; Kalinin, A.I.; Tissol'd, E.; Fromm, V.D.; Ekstein, P.
1978-01-01
A coincidence circuit with controlled parameters is described. The circuit has six coincidence inputs and one input for anticoincidences. A pulse duration in channels is changed from 0.25 to 5 μs and delay time, within 8 μs. The circuit is developed for multiparameter spectrometric analysis with the use of amplitude-digital and time-digital convertors. Its introduction permits one to diminish considerably the ''dead'' time of apparatus and to select rapidly and reliably strictly correlated digital information from convertors
International Nuclear Information System (INIS)
Rouchon, Amelie
2016-01-01
Neutron noise analysis addresses the description of small time-dependent flux fluctuations induced by small global or local perturbations of the macroscopic cross-sections. These fluctuations may occur in nuclear reactors due to density fluctuations of the coolant, to vibrations of fuel elements, control rods, or any other structures in the core. In power reactors, ex-core and in-core detectors can be used to monitor neutron noise with the aim of detecting possible anomalies and taking the necessary measures for continuous safe power production. The objective of this thesis is to develop techniques for neutron noise analysis and especially to implement a neutron noise solver in the deterministic transport code APOLLO3 developed at CEA. A new Monte Carlo algorithm that solves the transport equations for the neutron noise has been also developed. In addition, a new vibration model has been developed. Moreover, a method based on the determination of a new steady state has been proposed for the linear and the nonlinear full theory so as to improve the traditional neutron noise theory. In order to test these new developments we have performed neutron noise simulations in one-dimensional systems and in a large pressurized water reactor with heavy baffle in two and three dimensions with APOLLO3 in diffusion and transport theories. (author) [fr
Coincidence-counting corrections for accidental coincidences, set dead time and intrinsic dead time
International Nuclear Information System (INIS)
Wyllie, H.A.
1998-01-01
An equation is derived for calculating the radioactivity of a source from the results of coincidence counting, taking into account dead-time losses and accidental coincidences. The corrections allow for the extension of the set dead time in the p channel by the intrinsic dead time. Experimental verification shows improvement over a previous equation. (author)
Energy Technology Data Exchange (ETDEWEB)
Kumada, Hiroaki; Torii, Yoshiya [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment
2002-09-01
A boron neutron capture therapy (BNCT) with epithermal neutron beam is expected to treat effectively for malignant tumor that is located deeply in the brain. It is indispensable to estimate preliminarily the irradiation dose in the brain of a patient in order to perform the epithermal neutron beam BNCT. Thus, the JAERI Computational Dosimetry System (JCDS), which can calculate the dose distributions in the brain, has been developed. JCDS is a software that creates a 3-dimensional head model of a patient by using CT and MRI images and that generates a input data file automatically for calculation neutron flux and gamma-ray dose distribution in the brain by the Monte Carlo code: MCNP, and that displays the dose distribution on the head model for dosimetry by using the MCNP calculation results. JCDS has any advantages as follows; By treating CT data and MRI data which are medical images, a detail three-dimensional model of patient's head is able to be made easily. The three-dimensional head image is editable to simulate the state of a head after its surgical processes such as skin flap opening and bone removal for the BNCT with craniotomy that are being performed in Japan. JCDS can provide information for the Patient Setting System to set the patient in an actual irradiation position swiftly and accurately. This report describes basic design and procedure of dosimetry, operation manual, data and library structure for JCDS (ver.1.0). (author)
International Nuclear Information System (INIS)
Bakkari, B. El; Nacir, B.; El Younoussi, C.; Boulaich, Y.; Riyach, I.; Otmani, S.; Marcih, I.; Elbadri, H.; El Bardouni, T; Merroun, O.; Boukhal, H.; Zoubair, M.; Htet, A.; Chakir, M.
2010-01-01
The 2-MW TRIGA MARK II research reactor at Centre National de l'Energie, des Sciences et des Techniques Nucleaires (CNESTEN) achieved initial criticality on May 2, 2007 with 71 fuel elements. The reactor is designed to effectively implement the various fields of basic nuclear research, manpower and training and production of radioisotopes for their use in agriculture, industry and medicine. This work aims to study the time-dependent neutronics parameters of the TRIGA reactor for elaborating and planning of an in-core fuel management strategy to maximize the utilization of the TRIGA fluxes, using a new elaborated burnup computer code called 'BUCAL1'. The code can be used to aid in analysis, prediction, and optimization of fuel burnup performance in a nuclear reactor. It was developed to incorporate the neutron absorption tally/reaction information generated directly by MCNP5 code in the calculation of fissioned or neutron-transmuted isotopes for multi-fueled regions. The use of Monte Carlo method and punctual cross section data characterizing the MCNP code allows an accurate simulation of neutron life cycle in the reactor, and the integration of data on the entire energy spectrum, thus a more accurate estimation of results than deterministic code can do. Also, for the purpose of this study, a full-model of the TRIGA reactor was developed using the MCNP5 code. The validation of the MCNP model of the TRIGA reactor was made by benchmarking the reactivity experiments. (author)
International Nuclear Information System (INIS)
Petrov, Yu. V.; Nazarov, A. I.; Onegin, M. S.; Petrov, V. Yu.; Sakhnovsky, E. G.
2006-01-01
Using modern methods of reactor physics, we performed full-scale calculations of the Oklo natural reactor. For reliability, we used recent versions of two Monte Carlo codes: the Russian code MCU-REA and the well-known international code MCNP. Both codes produced similar results. We constructed a computer model of the Oklo reactor zone RZ2 which takes into account all details of design and composition. The calculations were performed for three fresh cores with different uranium contents. Multiplication factors, reactivities, and neutron fluxes were calculated. We also estimated the temperature and void effects for the fresh core. As would be expected, we found for the fresh core a significant difference between reactor and Maxwell spectra, which had been used before for averaging cross sections in the Oklo reactor. The averaged cross section of 62 149 Sm and its dependence on the shift of a resonance position E r (due to variation of fundamental constants) are significantly different from previous results. Contrary to the results of previous papers, we found no evidence of a change of the samarium cross section: a possible shift of the resonance energy is given by the limits -73≤ΔE r ≤62 meV. Following tradition, we have used formulas of Damour and Dyson to estimate the rate of change of the fine structure constant α. We obtain new, more accurate limits of -4x10 -17 ≤α·/α≤3x10 -17 yr -1 . Further improvement of the accuracy of the limits can be achieved by taking account of the core burn-up. These calculations are in progress
International Nuclear Information System (INIS)
Huang Derong; Yan Yongjun; Zhou Jianliang; Qiu Shoukang
2013-01-01
The method and calculation formulas to determine the chance coincidence in the 220 Rn coincidence measurement are introduced in this paper. The poisson distribution is introduced to correct the chance coincidence. The relative deviation of the true coincidence between the method and the Giffin's is within 5% after the correction of the cohance coincidence. The measurement of 220 Rn is done by comparative measurement with RAD7. The results shows that 220 Rn can be measured by the method with a relative deviation of 14%. Mean while, for the 220 Rn flow regime is difficult to meet the condition of calculation formulas, a solution to solve the survival factor and decay factor is proposed and the error come from the useage of theoretical calculation formula is avoided. (authors)
Microcomputerized neutron moisture gauge
International Nuclear Information System (INIS)
Liu Shengkang; Mei Yu
1987-01-01
A microcomputerized neutron moisture gauge is introduced. This gauge consists of a neutron moisture sensor and instruments. It is developed from the neutron moisture gauge for concrete mixer. A TECH-81 single card microcomputer is used for count, computation and display. It has the function of computing compensated quantity of sand. It can acquire the data from several neutron sensors by the multichanneling sampling, therefore it can measure moisture values of sand in several hoppers simultaneously. The precision of the static state calibration curve is 0.24% wt. The error limits of the dynamic state check is < 0.50% wt
Tachyon driven solution to Cosmic Coincidence Problrm
Srivastaca, S. K.
2004-01-01
Here, non-minimally coupled tachyon to gravity is considered as a source of "dark energy". It is demonstrated that with expansion of the universe, tachyon dark energy decays to "dark matter" providing a solution to "cosmic coincidence problem".Moreover, it is found that universe undergoes accelerated expansion simultaneously.
It Takes Two – Coincidence coding within the dual olfactory pathway of the honeybee
Directory of Open Access Journals (Sweden)
Martin F. Brill
2015-07-01
Full Text Available To rapidly process biologically relevant stimuli, sensory systems have developed a broad variety of coding mechanisms like parallel processing and coincidence detection. Parallel processing (e.g. in the visual system, increases both computational capacity and processing speed by simultaneously coding different aspects of the same stimulus. Coincidence detection is an efficient way to integrateinformation from different sources. Coincidence has been shown to promote associative learning and memory or stimulus feature detection (e.g. in auditory delay lines. Within the dual olfactory pathway of the honeybee both of these mechanisms might be implemented by uniglomerular projection neurons (PNs that transfer information from the primary olfactory centers, the antennal lobe (AL, to a multimodal integration center, the mushroom body (MB. PNs from anatomically distinct tracts respond to the same stimulus space, but have different physiological properties, characteristics that are prerequisites for parallel processing of different stimulus aspects. However, the PN pathways also display mirror-imaged like anatomical trajectories that resemble neuronal coincidence detectors as known from auditory delay lines. To investigate temporal processing of olfactory information, we recorded PN odor responses simultaneously from both tracts and measured coincident activity of PNs within and between tracts. Our results show that coincidence levels are different within each of the two tracts. Coincidence also occurs between tracts, but to a minor extent compared to coincidence within tracts. Taken together our findings support the relevance of spike timing in coding of olfactory information (temporal code.
It takes two-coincidence coding within the dual olfactory pathway of the honeybee.
Brill, Martin F; Meyer, Anneke; Rössler, Wolfgang
2015-01-01
To rapidly process biologically relevant stimuli, sensory systems have developed a broad variety of coding mechanisms like parallel processing and coincidence detection. Parallel processing (e.g., in the visual system), increases both computational capacity and processing speed by simultaneously coding different aspects of the same stimulus. Coincidence detection is an efficient way to integrate information from different sources. Coincidence has been shown to promote associative learning and memory or stimulus feature detection (e.g., in auditory delay lines). Within the dual olfactory pathway of the honeybee both of these mechanisms might be implemented by uniglomerular projection neurons (PNs) that transfer information from the primary olfactory centers, the antennal lobe (AL), to a multimodal integration center, the mushroom body (MB). PNs from anatomically distinct tracts respond to the same stimulus space, but have different physiological properties, characteristics that are prerequisites for parallel processing of different stimulus aspects. However, the PN pathways also display mirror-imaged like anatomical trajectories that resemble neuronal coincidence detectors as known from auditory delay lines. To investigate temporal processing of olfactory information, we recorded PN odor responses simultaneously from both tracts and measured coincident activity of PNs within and between tracts. Our results show that coincidence levels are different within each of the two tracts. Coincidence also occurs between tracts, but to a minor extent compared to coincidence within tracts. Taken together our findings support the relevance of spike timing in coding of olfactory information (temporal code).
Using Compton scattering for random coincidence rejection
International Nuclear Information System (INIS)
Kolstein, M.; Chmeissani, M.
2016-01-01
The Voxel Imaging PET (VIP) project presents a new approach for the design of nuclear medicine imaging devices by using highly segmented pixel CdTe sensors. CdTe detectors can achieve an energy resolution of ≈ 1% FWHM at 511 keV and can be easily segmented into submillimeter sized voxels for optimal spatial resolution. These features help in rejecting a large part of the scattered events from the PET coincidence sample in order to obtain high quality images. Another contribution to the background are random events, i.e., hits caused by two independent gammas without a common origin. Given that 60% of 511 keV photons undergo Compton scattering in CdTe (i.e. 84% of all coincidence events have at least one Compton scattering gamma), we present a simulation study on the possibility to use the Compton scattering information of at least one of the coincident gammas within the detector to reject random coincidences. The idea uses the fact that if a gamma undergoes Compton scattering in the detector, it will cause two hits in the pixel detectors. The first hit corresponds to the Compton scattering process. The second hit shall correspond to the photoelectric absorption of the remaining energy of the gamma. With the energy deposition of the first hit, one can calculate the Compton scattering angle. By measuring the hit location of the coincident gamma, we can construct the geometric angle, under the assumption that both gammas come from the same origin. Using the difference between the Compton scattering angle and the geometric angle, random events can be rejected.
International Nuclear Information System (INIS)
Rastogi, B.P.
1989-01-01
This report discusses various reactor physics codes developed for neutronic design, fuel-management, reactor operation and safety analysis of PHWRs. These code packages have been utilized for nuclear design of 500 MWe and new 235 MWe PHWRs. (author)
Energy Technology Data Exchange (ETDEWEB)
Ortiz R, J. M.; Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Ingenieria Electrica, Av. Ramon Lopez Velarde No. 801, Col. Centro, Zacatecas (Mexico); Martinez B, M. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Av. Ramon Lopez Velarde No. 801, Col. Centro, Zacatecas (Mexico); Gallego, E. [Universidad Politecnica de Madrid, Departamento de Ingenieria Nuclear, Jose Gutierrez Abascal No. 2, E-28006 Madrid (Spain)], e-mail: morvymmyahoo@com.mx
2009-10-15
The neutron dosimetry is one of the most complicated tasks of radiation protection, due to it is a complex technique and highly dependent of neutron energy. One of the first devices used to perform neutron spectrometry is the system known as spectrometric system of Bonner spheres, that continuous being one of spectrometers most commonly used. This system has disadvantages such as: the components weight, the low resolution of spectrum, long and drawn out procedure for the spectra reconstruction, which require an expert user in system management, the need of use a reconstruction code as BUNKIE, SAND, etc., which are based on an iterative reconstruction algorithm and whose greatest inconvenience is that for the spectrum reconstruction, are needed to provide to system and initial spectrum as close as possible to the desired spectrum get. Consequently, researchers have mentioned the need to developed alternative measurement techniques to improve existing monitoring systems for workers. Among these alternative techniques have been reported several reconstruction procedures based on artificial intelligence techniques such as genetic algorithms, artificial neural networks and hybrid systems of evolutionary artificial neural networks using genetic algorithms. However, the use of these techniques in the nuclear science area is not free of problems, so it has been suggested that more research is conducted in such a way as to solve these disadvantages. Because they are emerging technologies, there are no tools for the results analysis, so in this paper we present first the design of a computation tool that allow to analyze the neutron spectra and equivalent doses, obtained through the hybrid technology of neural networks and genetic algorithms. This tool provides an user graphical environment, friendly, intuitive and easy of operate. The speed of program operation is high, executing the analysis in a few seconds, so it may storage and or print the obtained information for
Reconstructed Image Spatial Resolution of Multiple Coincidences Compton Imager
Andreyev, Andriy; Sitek, Arkadiusz; Celler, Anna
2010-02-01
We study the multiple coincidences Compton imager (MCCI) which is based on a simultaneous acquisition of several photons emitted in cascade from a single nuclear decay. Theoretically, this technique should provide a major improvement in localization of a single radioactive source as compared to a standard Compton camera. In this work, we investigated the performance and limitations of MCCI using Monte Carlo computer simulations. Spatial resolutions of the reconstructed point source have been studied as a function of the MCCI parameters, including geometrical dimensions and detector characteristics such as materials, energy and spatial resolutions.
Neutron-deuteron analyzing power data at 19.0 MeV
International Nuclear Information System (INIS)
Weisel, G. J.; Tornow, W.; Crowe, B. J. III; Crowell, A. S.; Esterline, J. H.; Howell, C. R.; Kelley, J. H.; Macri, R. A.; Pedroni, R. S.; Walter, R. L.; Witala, H.
2010-01-01
Measurements of neutron-deuteron (n-d) analyzing power A y (θ) at E n =19.0 MeV are reported at 16 angles from θ c.m. =46.7 to 152.0 deg. The objective of the experiment is to better characterize the discrepancies between n-d data and the predictions of three-nucleon calculations for neutron energies above 16.0 MeV. The experiment used a shielded neutron source, which produced polarized neutrons via the 2 H(d-vector,n-vector) 3 He reaction, a deuterated liquid scintillator center detector (CD) and liquid-scintillator neutron side detectors. A coincidence between the CD and the side detectors isolated the elastic-scattering events. The CD pulse height spectrum associated with each side detector was sorted by using pulse-shape discrimination, time-of-flight techniques, and by removing accidental coincidences. A Monte Carlo computer simulation of the experiment accounted for effects due to finite geometry, multiple scattering, and CD edge effects. The resulting high-precision data (with absolute uncertainties ranging from 0.0022 to 0.0132) have a somewhat lower discrepancy with the predictions of three-body calculations, as compared to those found at lower energies.
International Nuclear Information System (INIS)
Bilanovic, Z.; McCracken, D.R.
1994-12-01
In order to assess irradiation-induced corrosion effects, coolant radiolysis and the degradation of the physical properties of reactor materials and components, it is necessary to determine the neutron, photon, and electron energy deposition profiles in the fuel channels of the reactor core. At present, several different computer codes must be used to do this. The most recent, advanced and versatile of these is the latest version of MCNP, which may be capable of replacing all the others. Different codes have different assumptions and different restrictions on the way they can model the core physics and geometry. This report presents the results of ANISN and MCNP models of neutron and photon energy deposition. The results validate the use of MCNP for simplified geometrical modelling of energy deposition by neutrons and photons in the complex geometry of the CANDU reactor fuel channel. Discrete ordinates codes such as ANISN were the benchmark codes used in previous work. The results of calculations using various models are presented, and they show very good agreement for fast-neutron energy deposition. In the case of photon energy deposition, however, some modifications to the modelling procedures had to be incorporated. Problems with the use of reflective boundaries were solved by either including the eight surrounding fuel channels in the model, or using a boundary source at the bounding surface of the problem. Once these modifications were incorporated, consistent results between the computer codes were achieved. Historically, simple annular representations of the core were used, because of the difficulty of doing detailed modelling with older codes. It is demonstrated that modelling by MCNP, using more accurate and more detailed geometry, gives significantly different and improved results. (author). 9 refs., 12 tabs., 20 figs
Methods of neutron spectrometry
International Nuclear Information System (INIS)
Doerschel, B.
1981-01-01
The different methods of neutron spectrometry are based on the direct measurement of neutron velocity or on the use of suitable energy-dependent interaction processes. In the latter case the measuring effect of a detector is connected with the searched neutron spectrum by an integral equation. The solution needs suitable unfolding procedures. The most important methods of neutron spectrometry are the time-of-flight method, the crystal spectrometry, the neutron spectrometry by use of elastic collisions with hydrogen nuclei, and neutron spectrometry with the aid of nuclear reactions, especially of the neutron-induced activation. The advantages and disadvantages of these methods are contrasted considering the resolution, the measurable energy range, the sensitivity, and the experimental and computational efforts. (author)
International Nuclear Information System (INIS)
Horrocks, D.L.
1980-01-01
A method and apparatus for the reliable determination of a random coincidence count attributable to chance coincidences of single-photon events which are each detected in only a single detector of a scintillation counter utilizing two detectors in a coincidence counting technique are described. A firstdelay device is employed to delay output pulses from one detector, and then the delayed signal is compared with the undelayed signal from the other detector in a coincidence circuit, to obtain an approximate random coincidence count. The output of the coincidence circuit is applied to an anti-coincidence circuit, where it is corrected by elimination of pulses coincident with, and attributable to, conventionally detected real coincidences, and by elimination of pulses coincident with, and attributable to, real coincidences that have been delayed by a second delay device having the same time parameter as the first. 8 claims
Recent progress with digital coincidence counting
International Nuclear Information System (INIS)
Butcher, K.S.A.; Watt, G.C.; Alexiev, D.
1999-01-01
Digital Coincidence Counting (DCC) is a new technique, based on the older method of analogue coincidence counting. It has been developed by ANSTO as a faster more reliable means of determining the activity of ionising radiation samples. The technique employs a dual channel analogue to digital converter acquisition system for collecting pulse information from a 4Π beta detector and a NaI(Tl) gamma detector. The digitised pulse information is stored on a high speed hard disk and timing information for both channels is also stored. The data may subsequently be recalled and analysed using software based algorithms. The system is operational and results are now being routinely collected and analysed. Some of the early work is presented for Co-60, Na-22 and Sm-153
International Nuclear Information System (INIS)
Frankel, J.I.
1995-01-01
This investigation uses symbolic computation in developing analytical methods and general computational strategies for solving both linear and nonlinear, regular and singular, integral and integro-differential equations which appear in radiative and combined mode energy transport. This technical report summarizes the research conducted during the first nine months of the present investigation. The use of Chebyshev polynomials augmented with symbolic computation has clearly been demonstrated in problems involving radiative (or neutron) transport, and mixed-mode energy transport. Theoretical issues related to convergence, errors, and accuracy have also been pursued. Three manuscripts have resulted from the funded research. These manuscripts have been submitted to archival journals. At the present time, an investigation involving a conductive and radiative medium is underway. The mathematical formulation leads to a system of nonlinear, weakly-singular integral equations involving the unknown temperature and various Legendre moments of the radiative intensity in a participating medium. Some preliminary results are presented illustrating the direction of the proposed research
Kinematical coincidence method in transfer reactions
Energy Technology Data Exchange (ETDEWEB)
Acosta, L.; Amorini, F. [INFN—Laboratori Nazionali del Sud, Via S. Sofia, Catania (Italy); Auditore, L. [INFN Gruppo Collegato di Messina and Dipartimento di Fisica, Università di Messina (Italy); Berceanu, I. [Institute for Physics and Nuclear Engineering, Bucharest (Romania); Cardella, G., E-mail: cardella@ct.infn.it [INFN—Sezione di Catania, Via S. Sofia, 95123 Catania (Italy); Chatterjiee, M.B. [Saha Institute for Nuclear Physics, Kolkata (India); De Filippo, E. [INFN—Sezione di Catania, Via S. Sofia, 95123 Catania (Italy); Francalanza, L.; Gianì, R. [INFN—Laboratori Nazionali del Sud, Via S. Sofia, Catania (Italy); Dipartimento di Fisica e Astronomia, Università di Catania, Via S. Sofia, Catania (Italy); Grassi, L. [INFN—Sezione di Catania, Via S. Sofia, 95123 Catania (Italy); Rudjer Boskovic Institute, Zagreb (Croatia); Grzeszczuk, A. [Institut of Physics, University of Silesia, Katowice (Poland); La Guidara, E. [INFN—Sezione di Catania, Via S. Sofia, 95123 Catania (Italy); Centro Siciliano di Fisica Nucleare e Struttura della Materia, Catania (Italy); Lanzalone, G. [INFN—Laboratori Nazionali del Sud, Via S. Sofia, Catania (Italy); Facoltà di Ingegneria e Architettura, Università Kore, Enna (Italy); Lombardo, I. [INFN—Laboratori Nazionali del Sud, Via S. Sofia, Catania (Italy); Dipartimento di Scienze Fisiche, Università Federico II and INFN Sezione di Napoli (Italy); Loria, D.; Minniti, T. [INFN Gruppo Collegato di Messina and Dipartimento di Fisica, Università di Messina (Italy); Pagano, E.V. [INFN—Laboratori Nazionali del Sud, Via S. Sofia, Catania (Italy); Dipartimento di Fisica e Astronomia, Università di Catania, Via S. Sofia, Catania (Italy); and others
2013-07-01
A new method to extract high resolution angular distributions from kinematical coincidence measurements in binary reactions is presented. Kinematics is used to extract the center of mass angular distribution from the measured energy spectrum of light particles. Results obtained in the case of {sup 10}Be+p→{sup 9}Be+d reaction measured with the CHIMERA detector are shown. An angular resolution of few degrees in the center of mass is obtained. The range of applicability of the method is discussed.
Coincident-inclusive electrofission angular correlations
International Nuclear Information System (INIS)
Arruda Neto, J.D.T.
1983-08-01
A method for the joint analysis of coincident and inclusive electrofission data, in order to minimize effects of the model dependence of data interpretation, is developed. Explicit calculations of the (e,e'f) angular correlations are presented. The potentialities of the method to the study of sub- and near-barrier properties of the fission process, and to the study of the giant resonances fission mode, are discussed. (Author) [pt
Timing coincidence studies with fast photomultipliers
International Nuclear Information System (INIS)
Raoof, M.A.; Raoof, S.A.
1981-01-01
The time response of RCA C70045D photomultipliers was studied using a subnanosecond light flasher. The tubes, which have an output rise time of approximately 0.5 ns, were used in coincidence to study the variations in the fwhm of the time spectrum over a certain dynamic range of pulse amplitudes for both leading edge and constant fraction discrimination. A comparison has also been made for the measured time resolutions with some of the other fast photomultipliers. (orig.)
Fast coincidence counting with active inspection systems
Mullens, J. A.; Neal, J. S.; Hausladen, P. A.; Pozzi, S. A.; Mihalczo, J. T.
2005-12-01
This paper describes 2nd and 3rd order time coincidence distributions measurements with a GHz processor that synchronously samples 5 or 10 channels of data from radiation detectors near fissile material. On-line, time coincidence distributions are measured between detectors or between detectors and an external stimulating source. Detector-to-detector correlations are useful for passive measurements also. The processor also measures the number of times n pulses occur in a selectable time window and compares this multiplet distribution to a Poisson distribution as a method of determining the occurrence of fission. The detectors respond to radiation emitted in the fission process induced internally by inherent sources or by external sources such as LINACS, DT generators either pulsed or steady state with alpha detectors, etc. Data can be acquired from prompt emission during the source pulse, prompt emissions immediately after the source pulse, or delayed emissions between source pulses. These types of time coincidence measurements (occurring on the time scale of the fission chain multiplication processes for nuclear weapons grade U and Pu) are useful for determining the presence of these fissile materials and quantifying the amount, and are useful for counter terrorism and nuclear material control and accountability. This paper presents the results for a variety of measurements.
Fast coincidence counting with active inspection systems
International Nuclear Information System (INIS)
Mullens, J.A.; Neal, J.S.; Hausladen, P.A.; Pozzi, S.A.; Mihalczo, J.T.
2005-01-01
This paper describes 2nd and 3rd order time coincidence distributions measurements with a GHz processor that synchronously samples 5 or 10 channels of data from radiation detectors near fissile material. On-line, time coincidence distributions are measured between detectors or between detectors and an external stimulating source. Detector-to-detector correlations are useful for passive measurements also. The processor also measures the number of times n pulses occur in a selectable time window and compares this multiplet distribution to a Poisson distribution as a method of determining the occurrence of fission. The detectors respond to radiation emitted in the fission process induced internally by inherent sources or by external sources such as LINACS, DT generators either pulsed or steady state with alpha detectors, etc. Data can be acquired from prompt emission during the source pulse, prompt emissions immediately after the source pulse, or delayed emissions between source pulses. These types of time coincidence measurements (occurring on the time scale of the fission chain multiplication processes for nuclear weapons grade U and Pu) are useful for determining the presence of these fissile materials and quantifying the amount, and are useful for counter terrorism and nuclear material control and accountability. This paper presents the results for a variety of measurements
Neutron transportation simulator
International Nuclear Information System (INIS)
Uenohara, Yuzo.
1995-01-01
In the present invention, problems in an existent parallelized monte carlo method is solved, and behaviors of neutrons in a large scaled system are accurately simulated at a high speed. Namely, a neutron transportation simulator according to the monte carlo method simulates movement of each of neutrons by using a parallel computer. In this case, the system to be processed is divided based on a space region and an energy region to which neutrons belong. Simulation of neutrons in the divided regions is allotted to each of performing devices of the parallel computer. Tarry data and nuclear data of the neutrons in each of the regions are memorized dispersedly to memories of each of the performing devices. A transmission means for simulating the behaviors of the neutrons in the region by each of the performing devices, as well as transmitting the information of the neutrons, when the neutrons are moved to other region, to the performing device in a transported portion are disposed to each of the performing devices. With such procedures, simulation for the neutrons in the allotted region can be conducted with small capacity of memories. (I.S.)
Energy Technology Data Exchange (ETDEWEB)
Pinchedez, K
1999-06-01
Parallel computing meets the ever-increasing requirements for neutronic computer code speed and accuracy. In this work, two different approaches have been considered. We first parallelized the sequential algorithm used by the neutronics code CRONOS developed at the French Atomic Energy Commission. The algorithm computes the dominant eigenvalue associated with PN simplified transport equations by a mixed finite element method. Several parallel algorithms have been developed on distributed memory machines. The performances of the parallel algorithms have been studied experimentally by implementation on a T3D Cray and theoretically by complexity models. A comparison of various parallel algorithms has confirmed the chosen implementations. We next applied a domain sub-division technique to the two-group diffusion Eigen problem. In the modal synthesis-based method, the global spectrum is determined from the partial spectra associated with sub-domains. Then the Eigen problem is expanded on a family composed, on the one hand, from eigenfunctions associated with the sub-domains and, on the other hand, from functions corresponding to the contribution from the interface between the sub-domains. For a 2-D homogeneous core, this modal method has been validated and its accuracy has been measured. (author)
Measurement of neutron importance by a dynamic method
International Nuclear Information System (INIS)
Dmitriev, V.M.; Matusevich, E.S.; Regushevskij, V.I.; Sazonov, S.P.; Usikov, D.A.
1977-01-01
A procedure is proposed for measuring neutron importance spatial distribution in a critical reactor by determining the parameters of its run-up with a constant neutron source. 252 Cf quasiisotropic point source was used. The measurements were performed at a critical assembly with a highly enriched uranium core and beryllium reflector. Importance distributions in critical and subsritical assemblies were compared for various degrees of subcriticality. Absolute normalization for the importance was obtained, and some new integral reactor characteristics were determined experimentally on its basis. An experimental data acquisition and processing system was developed on the basis of the ELECTRONIKA-100 computer. An algorithm was also developed for statistical treatment of the data. The importance distributions in critical and subcritical assemblies proved to coincide up to a rather deep subcriticality
International Nuclear Information System (INIS)
Williams, W.G.
1988-01-01
The book on 'polarized neutrons' is intended to inform researchers in condensed matter physics and chemistry of the diversity of scientific problems that can be investigated using polarized neutron beams. The contents include chapters on:- neutron polarizers and instrumentation, polarized neutron scattering, neutron polarization analysis experiments and precessing neutron polarization. (U.K.)
The LANL/LLNL Program to Measure Prompt Fission Neutron Spectra at LANSCE
Haight, Robert; Wu, Ching Yen; Lee, Hye Young; Taddeucci, Terry; Mosby, Shea; O'Donnell, John; Fotiades, Nikolaos; Devlin, Mattew; Ullmann, John; Nelson, Ronald; Wender, Stephen; White, Morgan; Solomon, Clell; Neudecker, Denise; Talou, Patrick; Rising, Michael; Bucher, Brian; Buckner, Matthew; Henderson, Roger
2015-10-01
Accurate data on the spectrum of neutrons emitted in neutron-induced fission are needed for applications and for a better understanding of the fission process. At LANSCE we have made important progress in understanding systematic uncertainties and in obtaining data for 235U on the low-energy part of the prompt fission neutron spectra (PFNS), a particularly difficult region because down-scattered neutrons go in this direction. We use a double time-of-flight technique to determine energies of incoming and outgoing neutrons. With data acquisition via waveform digitizers, accidental coincidences between fission chamber and neutron detector are measured to high statistical accuracy and then subtracted from measured events. Monte Carlo simulations with high performance computers have proven to be essential in the design to minimize neutron scattering and in calculating detector response. Results from one of three approaches to analyzing the data will be presented. This work is funded by the US Department of Energy, National Nuclear Security Administration and Office of Nuclear Physics.
International Nuclear Information System (INIS)
Pashchenko, A.B.
1996-09-01
The present report contains the Summary of the Third and Final IAEA Research Co-ordination Meeting (RCM) on ''Improvement of Measurements, Theoretical Computations and Evaluations of Neutron Induced Helium Production Cross Sections'' which was hosted by the Tohoku University and held in Sendai, Japan, from 25 to 29 September 1995. This RCM was organized by the IAEA Nuclear Data Section (NDS), with the co-operation and assistance of local organizers from Tohoku University. Summarized are the proceedings and results of the meeting. The List of Participants and meeting Agenda are included. (author)
Coincidence corrections for a multi-detector gamma spectrometer
Energy Technology Data Exchange (ETDEWEB)
Britton, R., E-mail: r.britton@surrey.ac.uk [University of Surrey, Guildford GU2 7XH (United Kingdom); AWE, Aldermaston, Reading, Berkshire RG7 4PR (United Kingdom); Burnett, J.L.; Davies, A.V. [AWE, Aldermaston, Reading, Berkshire RG7 4PR (United Kingdom); Regan, P.H. [University of Surrey, Guildford GU2 7XH (United Kingdom)
2015-01-01
List-mode data acquisition has been utilised in conjunction with a high-efficiency γ–γ coincidence system, allowing both the energetic and temporal information to be retained for each recorded event. Collected data is re-processed multiple times to extract any coincidence information from the γ-spectroscopy system, correct for the time-walk of low-energy events, and remove accidental coincidences from the projected coincidence spectra. The time-walk correction has resulted in a reduction in the width of the coincidence delay gate of 18.4±0.4%, and thus an equivalent removal of ‘background’ coincidences. The correction factors applied to ∼5.6% of events up to ∼500 keV for a combined {sup 137}Cs and {sup 60}Co source, and are crucial for accurate coincidence measurements of low-energy events that may otherwise be missed by a standard delay gate. By extracting both the delay gate and a representative ‘background’ region for the coincidences, a coincidence background subtracted spectrum is projected from the coincidence matrix, which effectively removes ∼100% of the accidental coincidences (up to 16.6±0.7% of the total coincidence events seen during this work). This accidental-coincidence removal is crucial for accurate characterisation of the events seen in coincidence systems, as without this correction false coincidence signatures may be incorrectly interpreted.
International Nuclear Information System (INIS)
Appiah-Ofori, F. F.
2014-07-01
The Effects of Gamma Radiation Heating and Irradiation Damage in the reactor vessel of Ghana Research Reactor 1, Miniature Neutron Source Reactor were assessed using Implicit Control Volume Finite Difference Numerical Computation and validated by SRIM - TRIM Code. It was assumed that 5.0 MeV of gamma rays from the reactor core generate heat which interact and absorbed completely by the interior surface of the MNSR vessel which affects it performance due to the induced displacement damage. This displacement damage is as result of lattice defects being created which impair the vessel through formation of point defect clusters such as vacancies and interstitiaIs which can result in dislocation loops and networks, voids and bubbles and causing changes in the layers in the thickness of the vessel. The microscopic defects produced in the vessel due to γ - radiation damage are referred to as radiation damage while the defects thus produced modify the macroscopic properties of the vessel which are also known as the radiation effects. These radiation damage effects are of major concern for materials used in nuclear energy production. In this study, the overall objective was to assess the effects of gamma radiation heating and damage in GHARR - I MNSR vessel by a well-developed Mathematical model, Analytical and Numerical solutions, simulating the radiation damage in the vessel. SRIM - TRIM Code was used as a computational tool to determine the displacement per atom (dpa) associated with radiation damage while implicit Control Volume Finite Difference Method was used to determine the temperature profile within the vessel due to γ - radiation heating respectively. The methodology adopted in assessing γ - radiation heating in the vessel involved development of the One-Dimensional Steady State Fourier Heat Conduction Equation with Volumetric Heat Generation both analytical and implicit Control Volume Finite Difference Method approach to determine the maximum temperature and
International Nuclear Information System (INIS)
Allen, L.S.
1977-01-01
A borehole logging tool includes a steady-state source of fast neutrons, two epithermal neutron detectors, and two thermal neutron detectors. A count rate meter is connected to each neutron detector. A first ratio detector provides an indication of the porosity of the formation surrounding the borehole by determining the ratio of the outputs of the two count rate meters connected to the two epithermal neutron detectors. A second ratio detector provides an indication of both porosity and macroscopic absorption cross section of the formation surrounding the borehole by determining the ratio of the outputs of the two count rate meters connected to the two thermal neutron detectors. By comparing the signals of the two ratio detectors, oil bearing zones and salt water bearing zones within the formation being logged can be distinguished and the amount of oil saturation can be determined. 6 claims, 2 figures
Abbott, B. P.; Hughey, Brennan; Zanolin, Michele; Szczepanczyk, Marek; Gill, Kiranjyot; Abbott, R.; Abbott, T. D.; Abernathy, M. R.; Acernese, F.; Ackley, K.;
2016-01-01
We present an archival search for transient gravitational-wave bursts in coincidence with 27 single-pulse triggers from Green Bank Telescope pulsar surveys, using the LIGO (Laser Interferometer Gravitational Wave Observatory), Virgo (Variability of Solar Irradiance and Gravity Oscillations) and GEO (German-UK Interferometric Detector) interferometer network. We also discuss a check for gravitational-wave signals in coincidence with Parkes fast radio bursts using similar methods. Data analyzed in these searches were collected between 2007 and 2013. Possible sources of emission of both short-duration radio signals and transient gravitational-wave emission include star quakes on neutron stars, binary coalescence of neutron stars, and cosmic string cusps. While no evidence for gravitational-wave emission in coincidence with these radio transients was found, the current analysis serves as a prototype for similar future searches using more sensitive second-generation interferometers.
Neutron multiplicity of fission fragments
Energy Technology Data Exchange (ETDEWEB)
Abdelrahman, Y S [Physics department, mu` rah university Al-Karak, (Jordan)
1995-10-01
The total average neutron multiplicity of the fission fragments produced by the spontaneous fission of {sup 248} Cm has been measured. This measurement has been done by using a new experimental technique. This technique mainly depends on {gamma}-{gamma} coincidence using a very high resolution high purity germanium (HPGe) detector. 2 figs.
Reproduction of the coincidence effect in gamma ray spectrometry by using Monte Carlo method
International Nuclear Information System (INIS)
Park, S. H.; Kim, J. K.; Lee, S. H.
2001-01-01
Scintillation detector such as NaI(TI), or semiconductor detector, such as HPGe, are used for Measurement/Assessment of the radiation type and radiation activity. The measured energy spectrum are used for measuring the radiation type and activity. Corrections for true coincidence due to emit more than 2 photons at the same time and random coincidence due to measuring system when increasing of the radiation intensity. For accurate assessment, measurement with adequate measure system is performed, and corrections for coincidence are performed in the hardware aspect and software aspect. In general, there are limitations or difficulties in measurement of radiation assessment, computational simulation is instead used. In simulation, it has much advantages than measurement in technically, timely, and financially, it is widely used instead of measurement. In this study, the method to reproduce of the coincidence effect was proposed by using monte carlo method
Coincidence logic modules for criticality alarming
International Nuclear Information System (INIS)
Schaief, C.C. III.
1977-04-01
A coincidence Logic Module and a companion contact closure Relay Module utilizing the NIM Standard have been developed for criticality alarming. The units provide an ALARM whenever two or more out of N detectors become activated. In addition, an ALERT is generated whenever one or more detectors is activated or when certain electronic component failures occur. The number of detector inputs (N) can be expanded in groups of six by adding modules. Serial and parallel redundancy were used to reduce the probability of system failure
Modeling of a Low-Background Spectroscopic Position-Sensitive Neutron Detector
Energy Technology Data Exchange (ETDEWEB)
Postovarova, Daria; Evsenin, Alexey; Gorshkov, Igor; Kuznetsov, Andrey; Osetrov, Oleg; Vakhtin, Dmitry; Yurmanov, Pavel [V.G. Khlopin Radium Institute, 194021, 28, 2nd Murinsky pr., Saint-Petersburg (Russian Federation)
2011-12-13
A new low-background spectroscopic direction-sensitive neutron detector that would allow one to reduce the neutron background component in passive and active neutron detection techniques is proposed. The detector is based on thermal neutron detectors surrounded by a fast neutron scintillation detector, which serves at the same time as a neutron moderator. Direction sensitivity is achieved by coincidence/anticoincidence analysis between different parts of the scintillator. Results of mathematical modeling of several detector configurations are presented.
Modeling of a Low-Background Spectroscopic Position-Sensitive Neutron Detector
International Nuclear Information System (INIS)
Postovarova, Daria; Evsenin, Alexey; Gorshkov, Igor; Kuznetsov, Andrey; Osetrov, Oleg; Vakhtin, Dmitry; Yurmanov, Pavel
2011-01-01
A new low-background spectroscopic direction-sensitive neutron detector that would allow one to reduce the neutron background component in passive and active neutron detection techniques is proposed. The detector is based on thermal neutron detectors surrounded by a fast neutron scintillation detector, which serves at the same time as a neutron moderator. Direction sensitivity is achieved by coincidence/anticoincidence analysis between different parts of the scintillator. Results of mathematical modeling of several detector configurations are presented.
International Nuclear Information System (INIS)
Menlove, H.O.; Keddar, A.
1982-12-01
The neutron coincidence counter has been field tested and evaluated for the measurement of boiling-water-reactor (BWR) fuel assemblies at the ASEA-ATOM Fuel Fabrication Facility. The system measures the 235 U content per unit length of full fuel assemblies using neutron interrogation and coincidence counting. The 238 U content is measured in the passive mode without the AmLi neutron interrogatioin source. The field tests included both standard production movable fuel rods to investigate enrichment and absorber variations. Results gave a response standard deviation of 0.9% for the active case and 2.1% for the passive case in 1000-s measurement times. 10 figures, 2 tables
International Nuclear Information System (INIS)
Steenstrup, S.
Briefly surveys recent developments in research work with ultracold neutrons (neutrons of very low velocity, up to 10 m/s at up to 10 -7 eV and 10 -3 K). Slow neutrons can be detected in an ionisation chamber filled with B 10 F 3 . Very slow neutrons can be used for investigations into the dipole moment of neutrons. Neutrons of large wave length have properties similar to those of light. The limit angle for total reflection is governed by the wave length and by the material. Total reflection can be used to filter ultracold neutrons out of the moderator material of a reactor. Total reflection can also be used to store ultracold neutrons but certain problems with storage have not yet been clarified. Slow neutrons can be made to lose speed in a neutron turbine, and come out as ultracold neutrons. A beam of ultracold neutrons could be used in a neutron microscope. (J.S.)
International Nuclear Information System (INIS)
Goldberg, H.J.; Morford, R.J.
1993-06-01
The disposal of high-level defense waste in a geologic repository necessitates conversion of the waste to a stable form. For this purpose, the Hanford Waste Vitrification Plant (HWVP) will be constructed. In this facility the waste will be converted into 6.3 x 10 5 cm 3 glassified cylinders, 59 cm in diameter and 230 cm in height, which will be placed in steel containers and buried. The waste packages must be adequately shielded to ensure the safety of personnel handling them. To calculate the shielding necessary, the radiation source term must be determined. Although the γ-ray source term does not present a problem, the neutron source term is a concern. Because the glass matrix is composed of light elements, the presence of any α-particle emitting radionuclides in the waste will contribute to the neutron flux. This paper attempts to ascertain the neutron flux and spectrum from (α,n) reactions and add it to the flux resulting from spontaneous fission
SPECTER-ANL, Neutron Damage for Material Irradiation
International Nuclear Information System (INIS)
1989-01-01
1 - Description of program or function: SPECTER calculates spectral- averaged displacements, recoil spectra, gas production, and total damage energy (Kerma) for 41 pure elements using ENDF/B-V derived cross sections. The user need only specify a neutron energy spectrum. Because SPECTER does not handle compounds, SPECOMP was developed to determine displacement damage for alloys, insulators, and breeder materials. 2 - Method of solution: In SPECTER elastic scattering is treated exactly including angular distributions from ENDF/B-V. Inelastic scattering calculations consider both discrete and continuous nuclear level distributions. Multiple (n,xn) reactions use a Monte Carlo technique to derive the recoil distributions. The (n,d) and (n,t) reactions are treated as (n,p) and (n, 3 He) as (n, 4 He). The neutron-gamma reaction and subsequent beta-decay are also included, using a new treatment of gamma-gamma coincidences, angular correlations, beta-neutrino correlations and the incident neutron energy. The Lindhard model was used to compute the energy available for nuclear displacement at each recoil energy. SPECOMP reads the required files from SPECTER, computes secondary displacement functions for each combination of recoil and matrix atom, and then integrates over recoil energy to find the net displacement cross section at each neutron energy. Damage due to neutron, gamma-ray and beta decay events is then added in and the results are summed to obtain the total dpa cross section. 3 - Restrictions on the complexity of the problem: The DISCS computer code was used to process ENDF/B-V data for 41 pure elements for use with SPECTER-ANL. SPECOMP can use any combination of four elements in a single run
International Nuclear Information System (INIS)
Yuecel, H.; Solmaz, A.N.; Koese, E.; Bor, D.
2010-01-01
In this study, true coincidence-summing (TCS) correction factors have been measured for the sources 22 Na, 60 Co, 133 Ba and 152 Eu by use of three large volume coplanar grid CdZnTe (acronym: CZT) detectors. In case of a close-in detection geometry, two different TCS calculation algorithms were used to compute the required TCS correction factors. Both of the algorithms are based on the measured total-to-peak (TTP) ratio and full-energy peak (FEP) efficiency values that were obtained using almost 'single' energy and coincidence-free nuclides. The results for TCS correction factors obtained by two different algorithms were agreeable to each other. The obtained TCS factors were ranged from about 7% to 30.5% in a 2250 mm 3 CZT detector when a close counting geometry was used. For other two detectors with a volume of 1000 and 1687.5 mm 3 , the resulted TCS correction factors were relatively smaller and varied between about 0.1% and 20% at the close counting geometry condition. Therefore, the results indicate that there is a need for the estimation of TCS corrections in CZT detectors, especially when their crystal volumes are greater than 1 cm 3 and these detectors are used in the case of a close-in detection geometry.
Electron-electron coincidence spectroscopies at surfaces
International Nuclear Information System (INIS)
Stefani, G.; Iacobucci, S.; Ruocco, A.; Gotter, R.
2002-01-01
In the past 20 years, a steadily increasing number of electron-electron coincidence experiments on atoms and molecules have contributed to a deeper understanding of electron-electron correlation effects. In more recent years this technique has been extended to the study of solid surfaces. This class of one photon IN two electrons OUT experiments will be discussed with an emphasis on grazing incidence geometry, that is expected to be particularly suited for studying surfaces. The crucial question of which is the dominant mechanism that leads to ejection of pairs of electron from the surface will be addressed. It will be shown that, depending on the kinematics chosen, the correlated behaviour of the pairs of electrons detected might be singled out from independent particle one
International Nuclear Information System (INIS)
Dickens, J.K.
1991-04-01
The organic scintillation detector response code SCINFUL has been used to compute secondary-particle energy spectra, dσ/dE, following nonelastic neutron interactions with 12 C for incident neutron energies between 15 and 60 MeV. The resulting spectra are compared with published similar spectra computed by Brenner and Prael who used an intranuclear cascade code, including alpha clustering, a particle pickup mechanism, and a theoretical approach to sequential decay via intermediate particle-unstable states. The similarities of and the differences between the results of the two approaches are discussed. 16 refs., 44 figs., 2 tabs
Minicomputer system for radiochemical analysis by coincidence spectrometry
International Nuclear Information System (INIS)
Brauer, F.P.; Fager, J.E.
1979-01-01
Minicomputer-based coincidence analysis methods have been developed for use in performing radiochemical analysis by high-resolution x- and gamma-ray coincidence spectrometry. This paper describes the data-acquisition and analysis methods develolped for qualitative and quantitative analyses of coincidence spectrometric data. Data-acquisition capabilities include both direct multiparameter pulse-height analysis and buffered list-mode acquisition
Analysis of mean lifetime for capture of neutrons in boron-loaded plastic scintillators
Energy Technology Data Exchange (ETDEWEB)
Kamykowski, E.A. (Grumman Corp., Bethpage, NY (USA). Research Center)
1990-12-20
The commercial availabiltiy of boron-loaded organic scintillators has led to the development of neutron detectors that operate as ''electronically'' black, totally absorbing spectrometers. The key to the enhanced spectroscopy is the delayed capture of nearly thermalized neutrons by {sup 10}B that can occur within a few microseconds after the energy pulse from prompt proton recoils. Accurate information regarding the mean lifetime is important for correct setting of the timing logic of the detection system to obtain good neutron detection efficiency with a low chance coincidence rate. In this paper we present an analysis of the mean lifetime for neutron capture for the boron-loaded plastic BC454. Measurements of the capture time constant obtained with a 7.62 cm diameter, 10.16 cm long detector are compared with values computed with the time-dependent Monte Carlo neutron transport code MCNP. Additional analyses using MCNP examine the dependence of the mean lifetime on the boron concentration, the detector's dimensions and the incident neutron energy. (orig.).
Performance of coincidence-based PSD on LiF/ZnS Detectors for Multiplicity Counting
Energy Technology Data Exchange (ETDEWEB)
Robinson, Sean M.; Stave, Sean C.; Lintereur, Azaree; Siciliano, Edward R.; Cowles, Christian C.; Kouzes, Richard T.; Behling, Richard S.
2016-10-06
Abstract: Mass accountancy measurement is a nuclear nonproliferation application which utilizes coincidence and multiplicity counters to verify special nuclear material declarations. With a well-designed and efficient detector system, several relevant parameters of the material can be verified simultaneously. 6LiF/ZnS scintillating sheets may be used for this purpose due to a combination of high efficiency and short die-away times in systems designed with this material, but involve choices of detector geometry and exact material composition (e.g., the addition of Ni-quenching in the material) that must be optimized for the application. Multiplicity counting for verification of declared nuclear fuel mass involves neutron detection in conditions where several neutrons arrive in a short time window, with confounding gamma rays. This paper considers coincidence-based Pulse-Shape Discrimination (PSD) techniques developed to work under conditions of high pileup, and the performance of these algorithms with different detection materials. Simulated and real data from modern LiF/ZnS scintillator systems are evaluated with these techniques and the relationship between the performance under pileup and material characteristics (e.g., neutron peak width and total light collection efficiency) are determined, to allow for an optimal choice of detector and material.
Freitas, M C; De Corte, F
1994-01-01
As part of a recent study on the environmental effects caused by the operation of a coal-fired power station at Sines, Portugal, k0-based instrumental neutron activation analysis (INAA) was used for the determination of the lanthanides (and also of tantalum and uranium) in plant leaves and lichens. In view of the accuracy and sensitivity of the determinations, it was advantageous to make use of a low-energy photon detector (LEPD). To begin with, in the present article, a survey is given of the former developments leading to user-friendly procedures for detection efficiency calibration of the LEPD and for correction for true-coincidence (cascade summing) effects. As a continuation of this, computer coincidence correction factors are now tabulated for the relevant low-energetic gamma-rays of the analytically interesting lanthanide, tantalum, and uranium radionuclides. Also the 140.5-keV line of 99Mo/99mTc is included, molybdenum being the comparator chosen when counting using an LEPD.
International Nuclear Information System (INIS)
Terry, W.K.; Gougar, H.D.; Ougouag, A.M.
2002-01-01
A new deterministic method has been developed for the neutronics analysis of a pebble-bed reactor (PBR). The method accounts for the flow of pebbles explicitly and couples the flow to the neutronics. The method allows modeling of once-through cycles as well as cycles in which pebbles are recirculated through the core an arbitrary number of times. This new work is distinguished from older methods by the systematically semi-analytical approach it takes. In particular, whereas older methods use the finite-difference approach (or an equivalent one) for the discretization and the solution of the burnup equation, the present work integrates the relevant differential equation analytically in discrete and complementary sub-domains of the reactor. Like some of the finite-difference codes, the new method obtains the asymptotic fuel-loading pattern directly, without modeling any intermediate loading pattern. This is a significant advantage for the design and optimization of the asymptotic fuel-loading pattern. The new method is capable of modeling directly both the once-through-then-out fuel cycle and the pebble recirculating fuel cycle. Although it currently includes a finite-difference neutronics solver, the new method has been implemented into a modular code that incorporates the framework for the future coupling to an efficient solver such as a nodal method and to modern cross section preparation capabilities. In its current state, the deterministic method presented here is capable of quick and efficient design and optimization calculations for the in-core PBR fuel cycle. The method can also be used as a practical 'scoping' tool. It could, for example, be applied to determine the potential of the PBR for resisting nuclear-weapons proliferation and to optimize proliferation-resistant features. However, the purpose of this paper is to show that the method itself is viable. Refinements to the code are under way, with the objective of producing a powerful reactor physics
Energy Technology Data Exchange (ETDEWEB)
Rezende, Gabriel Fonseca da Silva
2015-06-01
Many radiotherapy centers acquire 15 and 18 MV linear accelerators to perform more effective treatments for deep tumors. However, the acquisition of these equipment must be accompanied by an additional care in shielding planning of the rooms that will house them. In cases where space is restricted, it is common to find primary barriers made of concrete and metal. The drawback of this type of barrier is the photoneutron emission when high energy photons (e.g. 15 and 18 MV spectra) interact with the metallic material of the barrier. The emission of these particles constitutes a problem of radiation protection inside and outside of radiotherapy rooms, which should be properly assessed. A recent work has shown that the current model underestimate the dose of neutrons outside the treatment rooms. In this work, a computational model for the aforementioned problem was created from Monte Carlo Simulations and Artificial Intelligence. The developed model was composed by three neural networks, each being formed of a pair of material and spectrum: Pb18, Pb15 and Fe18. In a direct comparison with the McGinley method, the Pb18 network exhibited the best responses for approximately 78% of the cases tested; the Pb15 network showed better results for 100% of the tested cases, while the Fe18 network produced better answers to 94% of the tested cases. Thus, the computational model composed by the three networks has shown more consistent results than McGinley method. (author)
International Nuclear Information System (INIS)
Zizin, M.N.; Savochkina, O.A.; Chukhlova, O.P.
1978-01-01
A structure of standard designations is described and semantics of a number of standard values used in a NF-6 program complex is given. Main source data and results of neutron-physical reactor calculation are standard values, the peculiarities of FORTRAN and ALGOL-GDR algorithm languages in the DUBNA monitoring system were taken account of. As a base of standard values list the FIHAR system list, supplemented with new standard designations for integral reactor characteristics, is used. Developed is also a list of standard values to organize the exchange with external memory in the process of task solution and long-range storage
Energy Technology Data Exchange (ETDEWEB)
Hansen, G E [Los Alamos Scientific Laboratory, University of California, Los Alamos, NM (United States)
1962-03-15
New assemblies and improved measuring techniques call for periodic review of the status of computation vs. experiment. It is appropriate to emphasize neutron-spectral characterizations because of the particularly elusive problems associated with absolute spectral-index measurement and the need for checks of computation beyond simple critical size. The ever-improving spectral-index measurements in conjunction with increasing precision, both of microscopic data for detector and assembly materials and of computational techniques, produce a gradual clarification of the characteristics of a family of fast-neutron critical assemblies. This family now includes unreflected and thick-uranium-reflected U{sup 233} in spherical geometry. Direct correlations among the experimental data will be presented to indicate the a priori possibilities for successful correlations with computation. Sensitivity of computed spectra and critical sizes to neutron-transport models (transport and linear approximations ) and arithmetic approximations (finite angular segmentations and multi-group representations) will be presented for several typical assemblies to help establish the necessary computational detail. Comparisons between experiment and prediction will include, in addition to spectral indices and critical sizes, neutron lifetimes and delayed-neutron fractions. (author) [French] Du fait de la mise en service de nouveaux reacteurs et de l'amelioration des methodes de mesure, il est necessaire de faire periodiquement la correlation des experiences et des calculs. Il est utile d'insister sur les caracterisations de spectres de neutrons a cause des problemes particulieremen t delicats que pose la mesure absolue de l'indice spectral et de la necessite de verifier les calculs au-dela des simples dimensions critiques. Les mesures constamment ameliorees de l'indice spectral, associees a la precision croissante des donnees microscopiques relatives aux materiaux utilises dans les detecteurs et
Soudan 2 muons in coincidence with BATSE bursts
International Nuclear Information System (INIS)
DeMuth, D.M.; Marshak, M.L.; Wagner, G.L.
1994-01-01
We explore the possibilities of statistically significant temporal and spatial coincidences between underground muons at Soudan 2 and Gamma Ray Bursts at the GRO-BATSE detector. Our search uses data from the April 91 to March 92 BATSE burst catalog to seek correlations within a 100 second window of coincidence. Sixteen of 180 BATSE triggers have temporally and spatially coincident muons in the Soudan 2 detector. We estimate the chance probability of each coincidence assuming the null hypothesis on the basis of a study of the multiplicities of spatially coincident muons observed over a two day period centered on the time of burst
A full automatic system controlled with IBM-PC/XT micro-computer for neutron activation analysis
International Nuclear Information System (INIS)
Song Quanxun
1992-01-01
A full automatic system controlled with micro-computers for NAA is described. All processes are automatically completed with an IBM-PC/XT micro-computer. The device is stable, reliable, flexible and convenient for use and has many functions and applications in automatical analysis of long, middle and short lived nuclides. Due to a high working efficiency of the instrument and micro-computers, both time and power can be saved. This method can be applied in other nuclear analysis techniques
International Nuclear Information System (INIS)
Dewanckele, J.; De Kock, T.; Fronteau, G.; Derluyn, H.; Vontobel, P.; Dierick, M.; Van Hoorebeke, L.; Jacobs, P.; Cnudde, V.
2014-01-01
Euville and Savonnières limestones were weathered by acid test and this resulted in the formation of a gypsum crust. In order to characterize the crystallization pattern and the evolution of the pore structure below the crust, a combination of high resolution X-ray computed tomography and SEM–EDS was used. A time lapse sequence of the changing pore structure in both stones was obtained and afterwards quantified by using image analysis. The difference in weathering of both stones by the same process could be explained by the underlying microstructure and texture. Because water and moisture play a crucial role in the weathering processes, water uptake in weathered and non-weathered samples was characterized based on neutron radiography. In this way the water uptake was both visualized and quantified in function of the height of the sample and in function of time. In general, the formation of a gypsum crust on limestone slows down the initial water uptake in the materials. - Highlights: • Time lapse sequence in 3D of changing pore structures inside limestone • A combination of X-ray CT, SEM and neutron radiography was used. • Quantification of water content in function of time, height and weathering • Characterization of weathering processes due to gypsum crystallization
Complete characterization of breakup of 9Be by α-α coincidence measurements
International Nuclear Information System (INIS)
Rafiei, R.; Luong, D.H.; Hinde, D.J.; Dasgupta, M.; Du Rietz, R.
2011-01-01
The breakup mechanisms for 9 Be have been studied through coincident detection of the breakup α particles at sub-barrier energies, where the probability of capture of a charged breakup fragment by the target nucleus is negligible. Combining the reconstructed reaction Q-value and the relative energy of the two coincident breakup α particles a complete picture of breakup dynamics has been obtained. The measurements reveal breakup processes which are fast enough (~ 10 -22 s) to affect fusion, called prompt breakup. It is shown that prompt breakup is triggered predominantly by the transfer of a neutron -a two-step process. The prompt breakup probabilities are shown to have an exponential dependence on the surface-to-surface separation of the interacting nuclei, but are independent of the target nuclei, ranging from 144 Sm to 209 Bi. These results provide significant input towards a complete quantal model aiming to describe the breakup of weakly bound stable and halo nuclei. (author)
Neutron radiography with the cyclotron
International Nuclear Information System (INIS)
Tazawa, Shuichi; Asada, Yorihisa; Yano, Munehiko; Nakanii, Takehiko.
1985-01-01
Neutron radiography is well recognized as a powerful tool in nondestructive testing, but not widely used yet owing to lack of high intense thermal neutron source convenient for practical use. This article presents a new neutron radiograph facility, utilizing a sub-compact cyclotron as neutron source and is equipped with vertical and horizontal irradiation ports. The article describes a series of experiments, we conducted using beams of a variable energy cyclotron at Tohoku University to investigate the characteristics of thermal neutron obtained from 9 Be(p, n) reaction and thermalized by elastic scattering process. The article also describes a computer simulation of neutron moderator to analyze conditions getting maximal thermal neutron flux. Further, some of practical neutron radiograph examinations of aero-space components and museum art objects of classic bronze mirror and an attempt realizing real time imaging technique, are introduced in the article. (author)
Directory of Open Access Journals (Sweden)
Mohammadnia Meysam
2013-01-01
Full Text Available The flux expansion nodal method is a suitable method for considering nodalization effects in node corners. In this paper we used this method to solve the intra-nodal flux analytically. Then, a computer code, named MA.CODE, was developed using the C# programming language. The code is capable of reactor core calculations for hexagonal geometries in two energy groups and three dimensions. The MA.CODE imports two group constants from the WIMS code and calculates the effective multiplication factor, thermal and fast neutron flux in three dimensions, power density, reactivity, and the power peaking factor of each fuel assembly. Some of the code's merits are low calculation time and a user friendly interface. MA.CODE results showed good agreement with IAEA benchmarks, i. e. AER-FCM-101 and AER-FCM-001.
International Nuclear Information System (INIS)
Stefani, Giovanni Laranjo de
2009-01-01
This work proceeds the elaboration of a computational program for execution of various neutron and thermalhydraulic calculation methodology programs of the IEA-R1-Sao Paulo, Brazil, making the process more practical and safe, besides transforming de output data of each program an automatic process. This reactor is largely used for production of radioisotopes for medical use, material irradiation, personnel training and also for basic research. For that purposes it is necessary to change his core configuration in order to adapt the reactor for different uses. The work will transform various existent programs into subroutines of a principal program, i.e.,a program which call each of the programs automatically when necessary, and create another programs for manipulation the output data and therefore making practical the process
International Nuclear Information System (INIS)
Satoh, Daiki; Takahashi, Fumiaki; Shigemori, Yuji; Sakamoto, Kensaku
2010-06-01
DOSE-Analyzer is a computer program to retrieve the dose information from a database and generate a graph through a graphical user interface (GUI). The database is constructed for absorbed dose, fluence, and energy distribution inside a body of mouse and human exposed upon external neutrons, which is calculated by our developed Monte-Carlo simulation method using voxel-based phantom and particle transport code PHITS. The input configurations of irradiation geometry, subject, and energy are set by GUI. The results are tabulated at particle types, i.e. electron, proton, deuteron, triton, and alpha particle, and target organs on a data sheet of Microsoft Office Excel TM . Simple analysis to compare the output values for two subjects is also performed on DOSE-Analyzer. This report is a user manual of DOSE-Analyzer. (author)
International Nuclear Information System (INIS)
Giannini, M.; Oliva, P.R.; Ramorino, C.
1978-01-01
A description is given of a computer code which automatically analyses gamma-ray spectra obtained with Ge(Li) detectors. The program contains features as automatic peak location and fitting, determination of peak energies and intensities, nuclide identification and calculation of masses and errors. Finally the results obtained with our computer code for a lunar sample are reported and briefly discussed
Energy Technology Data Exchange (ETDEWEB)
Trindade, Bruno Machado
2011-02-15
This work shows the remodeling of the Computer System for Dosimetry of Neutrons and Photons in Radiotherapy Based on Stochastic Methods . SISCODES. The initial description and status, the alterations and expansions (proposed and concluded), and the latest system development status are shown. The SISCODES is a system that allows the execution of a 3D computational planning in radiation therapy, based on MCNP5 nuclear particle transport code. The SISCODES provides tools to build a patient's voxels model, to define a treatment planning, to simulate this planning, and to view the results of the simulation. The SISCODES implements a database of tissues, sources and nuclear data and an interface to access then. The graphical SISCODES modules were rewritten or were implemented using C++ language and GTKmm library. Studies about dose deviations were performed simulating a homogeneous water phantom as analogue of the human body in radiotherapy planning and a heterogeneous voxel phantom, pointing out possible dose miscalculations. The Soft-RT and PROPLAN computer codes that do interface with SISCODES are described. A set of voxels models created on the SISCODES are presented with its respective sizes and resolutions. To demonstrate the use of SISCODES, examples of radiation therapy and dosimetry simulations for prostate and heart are shown. Three protocols were simulated on the heart voxel model: Sm-153 filled balloon and P-32 stent, to prevent angioplasty restenosis; and Tl-201 myocardial perfusion, to imaging. Teletherapy with 6MV and 15MV beams were simulated to the prostate, and brachytherapy with I-125 seeds. The results of these simulations are shown on isodose curves and on dose-volume histograms. The SISCODES shows to be a useful tool for research of new radiation therapy treatments and, in future, can also be useful in medical practice. At the end, future improvements are proposed. I hope this work can contribute to develop more effective radiation therapy
International Nuclear Information System (INIS)
Pirouzmand, Ahmad; Hadad, Kamal; Suh, Kune Y.
2011-01-01
This paper considers the concept of analog computing based on a cellular neural network (CNN) paradigm to simulate nuclear reactor dynamics using a time-dependent second order form of the neutron transport equation. Instead of solving nuclear reactor dynamic equations numerically, which is time-consuming and suffers from such weaknesses as vulnerability to transient phenomena, accumulation of round-off errors and floating-point overflows, use is made of a new method based on a cellular neural network. The state-of-the-art shows the CNN as being an alternative solution to the conventional numerical computation method. Indeed CNN is an analog computing paradigm that performs ultra-fast calculations and provides accurate results. In this study use is made of the CNN model to simulate the space-time response of scalar flux distribution in steady state and transient conditions. The CNN model also is used to simulate step perturbation in the core. The accuracy and capability of the CNN model are examined in 2D Cartesian geometry for two fixed source problems, a mini-BWR assembly, and a TWIGL Seed/Blanket problem. We also use the CNN model concurrently for a typical small PWR assembly to simulate the effect of temperature feedback, poisons, and control rods on the scalar flux distribution
K-chameleon and the coincidence problem
International Nuclear Information System (INIS)
Wei Hao; Cai Ronggen
2005-01-01
In this paper we present a hybrid model of k-essence and chameleon, named as k-chameleon. In this model, due to the chameleon mechanism, the directly strong coupling between the k-chameleon field and matters (cold dark matters and baryons) is allowed. In the radiation-dominated epoch, the interaction between the k-chameleon field and background matters can be neglected; the behavior of the k-chameleon therefore is the same as that of the ordinary k-essence. After the onset of matter domination, the strong coupling between the k-chameleon and matters dramatically changes the result of the ordinary k-essence. We find that during the matter-dominated epoch, only two kinds of attractors may exist: one is the familiar K attractor and the other is a completely new, dubbed C attractor. Once the Universe is attracted into the C attractor, the fraction energy densities of the k-chameleon Ω φ and dust matter Ω m are fixed and comparable, and the Universe will undergo a power-law accelerated expansion. One can adjust the model so that the K attractor does not appear. Thus, the k-chameleon model provides a natural solution to the cosmological coincidence problem
Coincidence orientations of grains in hexagonal materials
International Nuclear Information System (INIS)
Grimmer, H.; Warrington, D.H.
1986-06-01
The connection between the rotation matrix in hexagonal lattice coordinates and an angle-axis quadruple is given. The multiplication law of quadruples is derived. It corresponds to multiplying two matrices and gives the effect of two successive rotations. The relation is given between two quadruples that describe the same relative orientation of two lattices due to their hexagonal symmetry; a unique standard description of the relative orientation is proposed. The restrictions satisfied by rotations generating coincidence site lattices (CSLs) are derived for any value of the axial ratio rho = c/a. It is shown that the law for cubic lattices, where the multiplicity SIGMA of the CSL was equal to the least common denominator of the elements of the rotation matrix, does not always hold for hexagonal lattices. A generalisation of this law to lattices of arbitrary symmetry is given and another, quicker method to determine SIGMA for hexagonal lattices is derived. Finally, convenient algorithms are described for determining bases of the CSL and the DSC lattice. (author)
Complex action support from coincidences of couplings
International Nuclear Information System (INIS)
Nielsen, H.B.
2011-01-01
Our model (Refs. 1–7) with a complex action in a functional integral formulation with path integrals extending over all times, both past and future, is reviewed. Several numerical relations between coupling constants are presented as supporting evidence. The new evidence is that several more hitherto unexplained coincidences are explained by our model: (1) The "scale problem" is solved because the Higgs field expectation value is predicted to be very small compared to say some fundamental scale, that might be the Planck scale. (2) The Higgs VEV need not be just zero, but rather is predicted to be so that the running top-quark Yukawa coupling just is about to be unity at this scale; in this way the (weak) scale easily becomes "exponentially small." Instead of the top-Yukawa we should rather say the highest flavor Yukawa coupling here. These predictions are only achieved by allowing the principle of minimization of the imaginary part of the action SI(history) to a certain extent adjust some coupling constants in addition to the initial conditions. If supersymmetric partners are not found at LHC it would strengthen the need for a "solution" to the hierarchy problem in our direction of an explanation via a fine-tuning scheme inside the Standard Model, from say minimizing "the imaginary part of the action" in our complex action model. (author)
Microdosimetry of intermediate energy neutrons in fast neutron fields
International Nuclear Information System (INIS)
Saion, E.B.; Watt, D.E.
1988-01-01
A coaxial double cylindrical proportional counter has been constructed for microdosimetry of intermediate energy neutrons in mixed fields. Details are given of the measured gas gain and resolution characteristics of the counter for a wide range of anode voltages. Event spectra due to intermediate neutrons in any desired energy band is achieved by an appropriate choice of thickness of the common dividing wall in the counter and by appropriate use of the coincidence, anticoincidence pulse counting arrangements. Calculated estimates indicate that the dose contribution by fast neutrons to the energy deposition events in the intermediate neutron range may be as large as 25%. Empirical procedures being investigated aim to determine the necessary corrections to be applied to the microdose distributions, with a precision of 10%. (author)
International Nuclear Information System (INIS)
Bogdzel', A.A.; Vasil'eva, Eh.V.; Elizarov, O.I.
1982-01-01
Main performanes and peculiarities of spectrometer based on the coincidence pulse amplitude total-count method and containing two Ge(La) detectors with transmission neutron spectrometer - IBR-30 pulse reactor are considered. It is shown on the 35 Cl(n, #betta#) reaction that the method of summalion of amplitudes of coinciding pulses from the Ge(Li) detector can be used to study the cascades of two #betta#-transitions with a total energy similar to the neutron binding energy. The shape of the response function of this spectrometer was studied versus the energies of #betta#-transition cascades
International Nuclear Information System (INIS)
Sukhovoj, A.M.; Khitrov, V.A.
1984-01-01
A method of unfolding the differential γ-cascade spectra during radiation capture of slow neutrons based on the computeri-- zed processing of the results of measurements performed, by means of a spectrometer with two Ge(Li) detectors is suggested. The efficiency of the method is illustrated using as an example the spectrum of 35 Cl(n, γ) reaction corresponding to the 8580 keV peak. It is shown that the above approach permits to improve the resolution by 1.2-2.6 times without decrease in registration efficiency within the framework of the method of coincidence pulse amplitude summation
International Nuclear Information System (INIS)
Ichihara, Akira; Kunieda, Satoshi; Chiba, Satoshi; Iwamoto, Osamu; Shibata, Keiichi; Nakagawa, Tsuneo; Fukahori, Tokio; Katakura, Jun-ichi
2005-07-01
The computer code, POD, was developed to calculate angle-differential cross sections and analyzing powers for shape-elastic scattering for collisions of neutron or light ions with target nucleus. The cross sections are computed with the optical model. Angle-differential cross sections for neutron inelastic scattering can also be calculated with the distorted-wave Born approximation. The optical model potential parameters are the most essential inputs for those model computations. In this program, the cross sections and analyzing powers are obtained by using the existing local or global parameters. The parameters can also be inputted by users. In this report, the theoretical formulas, the computational methods, and the input parameters are explained. The sample inputs and outputs are also presented. (author)
A 15 channel 2- and 3-fold coincidence counting system for radioactivity standardization
International Nuclear Information System (INIS)
Simpson, B.R.S.; Meyer, B.R.; Raave, D.A.
1986-01-01
The 4π β-γ liquid scintillation coincidence counting system which is used at the National Accelerator Centre for standardizing radioisotopes, has been extended to allow for up to fifteen data points to be measured simultaneously by introducing a 15-fold coincidence unit and a 32-channel scaler into the system. A new control / data acquisition computer program has been written and its operation explained in detail. The advantages of the new system are discussed, and the activity of a 139 Ce source as measured by the new system and the old 3-fold system is compared
Cordeiro, João M. M.; Soper, Alan K.
2013-01-01
The solvation of N-methylformamide (NMF) by dimethylsulfoxide (DMSO) in a 20% NMF/DMSO liquid mixture is investigated using a combination of neutron diffraction augmented with isotopic substitution and Monte Carlo simulations. The aim is to investigate the solute-solvent interactions and the structure of the solution. The results point to the formation of a hydrogen bond (H-bond) between the H bonded to the N of the amine group of NMF and the O of DMSO particularly strong when compared with other H-bonded liquids. Moreover, a second cooperative H-bond is identified with the S atom of DMSO. As a consequence of these H-bonds, molecules of NMF and DMSO are rather rigidly connected, establishing very stable dimmers in the mixture and very well organized first and second solvation shells.
Lattice dynamics of Ba1-xKxBiO3 as studied by neutron scattering and computer simulation
International Nuclear Information System (INIS)
Belushkin, A.V.; Vagov, A.V.; Zemlyanov, M.G.; Parshin, P.P.
1991-01-01
A time-of-flight neutron inelastic scattering study of the lattice dynamics of Ba 1-x K x BiO 3 for x=0.0 and x=0.4 has been performed for the temperatures 10 K, 80 K and 290 K. No temperature effects were found for the generalized phonon density of states. The phonon spectrum of a superconducting sample reveals less in number van Hove singularities and softens in comparison with that of the nonsuperconducting one. On the basis of the simple model for interatomic potential the lattice dynamics of this system was calculated. Some features of the structural phase diagram and the optical spectroscopy data were explained using this model. The calculated phonon density of states was found to be in good agreement with experiment. 36 refs.; 3 figs
International Nuclear Information System (INIS)
Van Well, A.A.
1999-01-01
Neutron research where reflection, refraction, and interference play an essential role is generally referred to as 'neutron optics'. The neutron wavelength, the scattering length density and the magnetic properties of the material determine the critical angle for total reflection. The theoretical background of neutron reflection, experimental methods and the interpretation of reflection data are presented. (K.A.)
Design and performance of the Savannah River Site Billet Active Well Coincidence Counter
International Nuclear Information System (INIS)
Griffin, J.C.; Sadowski, E.T.
1991-01-01
The Savannah River Site (SRS) has acquired, installed, and tested a custom-built Billet Active Well (neutron) Coincidence Counter (BAWCC). The BAWCC is used to make accountability measurements of the 235 U content of U-Al coextrusion billets in the SRS fuel fabrication facility. The instrument design incorporates a unique center-source configuration, with two moderated americium-lithium (AmLi) neutron sources located in a central spindle that inserts through the center hole of the U-Al billets. This configuration, a result of earlier experimental studies at SRS, yields improved response and precision for billet assay when compared to the standard AWCC source arrangement. Initial tests of the BAWCC at SRS have yielded one-sigma uncertainties of 0.8--1.0% for a fifteen-minute assay. This paper will describe the design, testing program and performance characteristics of the BAWCC
The underwater coincidence counter for plutonium measurements in mixed-oxide fuel assemblies manual
International Nuclear Information System (INIS)
Eccleston, G.W.; Menlove, H.O.; Abhold, M.; Baker, M.; Pecos, J.
1999-01-01
This manual describes the Underwater Coincidence Counter (UWCC) that has been designed for the measurement of plutonium in mixed-oxide (MOX) fuel assemblies prior to irradiation. The UWCC uses high-efficiency 3 He neutron detectors to measure the spontaneous-fission and induced-fission rates in the fuel assembly. Measurements can be made on MOX fuel assemblies in air or underwater. The neutron counting rate is analyzed for singles, doubles, and triples time correlations to determine the 240 Pu effective mass per unit length of the fuel assembly. The system can verify the plutonium loading per unit length to a precision of less than 1% in a measurement time of 2 to 3 minutes. System design, components, performance tests, and operational characteristics are described in this manual
International Nuclear Information System (INIS)
Kuklin, A.I.; Rogov, A.D.; Gorshkova, Yu.E.; Kovalev, Yu.S.; Kutuzov, S.A.; Utrobin, P.K.; Rogachev, A.V.; Ivan'kov, O.I.; Solov'ev, D.V.; Gordelij, V.I.
2011-01-01
Results of experimental and computer modeling investigations of neutron spectra and fluxes obtained with cold and thermal moderators at the IBR-2 reactor (JINR, Dubna) are presented. The studies are done for small-angle neutron scattering (SANS) spectrometer YuMO (beamline number 4 of the IBR-2). The measurements of neutron spectra for two methane cold moderators are done for the standard configuration of the SANS instrument. The data from both moderators under different conditions of their operation are compared. The ratio of experimentally determined neutron fluxes of cold and thermal moderators at different wavelength is shown. Monte Carlo simulations are done to determine spectra for cold methane and thermal moderators. The results of the calculations of the ratio of neutron fluxes of cold and thermal moderators at different wavelength are demonstrated. In addition, the absorption of neutrons in the air gaps on the way from the moderator to the investigated sample is presented. SANS with the protein apoferritin was done in the case of cold methane as well as a thermal moderator and the data were compared. The perspectives for the use of the cold moderator for a SANS spectrometer at the IBR-2 are discussed. The advantages of the YuMO spectrometer with the thermal moderator with respect to the tested cold moderator are shown
neutron transmission through crystalline materials
International Nuclear Information System (INIS)
El Mesiry, M.S.
2011-01-01
The aim of the present work is to study the neutron transmission through crystalline materials. Therefore a study of pyrolytic graphite (PG) as a highly efficient selective thermal neutron filter and Iron single crystal as a whole one, as well as the applicability of using their polycrystalline powders as a selective cold neutron filters is given. Moreover, the use of PG and iron single crystal as an efficient neutron monochromator is also investigated. An additive formula is given which allows calculating the contribution of the total neutron cross-section including the Bragg scattering from different )(hkl planes to the neutron transmission through crystalline iron and graphite. The formula takes into account their crystalline form. A computer CFe program was developed in order to provide the required calculations for both poly- and single-crystalline iron. The validity of the CFe program was approved from the comparison of the calculated iron cross-section data with the available experimental ones. The CFe program was also adapted to calculate the reflectivity from iron single crystal when it used as a neutron monochromator The computer package GRAPHITE, developed in Neutron Physics laboratory, Nuclear Research Center, has been used in order to provide the required calculations for crystalline graphite in the neutron energy range from 0.1 meV to 10 eV. A Mono-PG code was added to the computer package GRAPHITE in order to calculate the reflectivity from PG crystal when it used as a neutron monochromator.
Application of GESPECOR software for the calculation of coincidence summing effects in special cases
International Nuclear Information System (INIS)
Arnold, Dirk; Sima, Octavian
2004-01-01
In this work, coincidence summing correction factors have been measured for 133 Ba, 152 Eu and 88 Y point sources with a 50% relative efficiency p-type detector and a 25% relative efficiency n-type detector in two close-to-detector measurement geometries. The experimental data for 133 Ba and 152 Eu and the results obtained with the GESPECOR software reveal a complex structure of the conventional dead layer of the p-type detector. The high value of the coincidence summing correction factor for the 511 keV peak of 88 Y, in agreement with the values computed by GESPECOR, in this case cautions against the application of the semiempirical method for evaluating coincidence summing effects
System for ν-ν-coincidence spectra processing with data compression
International Nuclear Information System (INIS)
Byalko, A.A.; Volkov, N.G.; Tsupko-Sitnikov, V.M.; Churakov, A.K.
1982-01-01
Calculational algorithm and program for analyzing gamma-gamma coincidence spectra based on using the method of expansion in singular values for data compression (the SVD method) are described. Results of the testing of the program during the processing of coincidence spectrum for the low-energy region of transitions corresponding to decay 164 Lu → 164 Yb are given. The program is written in the FORTRAN language and is realized by the ES-1040 computer. The counting time constitutes about 20 min. It is concluded that the use of the SVD method permits to correct the data at the expense of distortion filtration caused with statistical deviations and random interferences, at that not distorting the initial data. The data compressed correspond more to theoretical suggestions of forms of semiconductor detector lines and two-dimensional line in the coincidence spectrum
International Nuclear Information System (INIS)
Palfalvi, J.
1984-03-01
The combined effect of incident and albedo neutrons on the response of several fission and (n,α) track detectors was investigated by calculations for monoenergetic neutrons and for neutrons from different energetic sources. The response functions are presented in tables and plots. (author)
Neutron radiography with ultracold neutrons
International Nuclear Information System (INIS)
Bates, J.C.
1981-01-01
The neutron transmission factor of very thin films may be low if the neutron energy is comparable to the pseudo-potential of the film material. Surprisingly, perhaps, it is relatively easy to obtain neutrons with such low energies in sufficient numbers to produce neutron radiographs. (orig.)
Principle of coincidence method and application in activity measurement
International Nuclear Information System (INIS)
Li Mou; Dai Yihua; Ni Jianzhong
2008-01-01
The basic principle of coincidence method was discussed. The basic principle was generalized by analysing the actual example, and the condition in theory of coincidence method was brought forward. The cause of variation of efficiency curve and the effect of dead-time in activity measurement were explained using the above principle and condition. This principle of coincidence method provides the foundation in theory for activity measurement. (authors)
Determination of true coincidence correction factors using Monte-Carlo simulation techniques
Directory of Open Access Journals (Sweden)
Chionis Dionysios A.
2014-01-01
Full Text Available Aim of this work is the numerical calculation of the true coincidence correction factors by means of Monte-Carlo simulation techniques. For this purpose, the Monte Carlo computer code PENELOPE was used and the main program PENMAIN was properly modified in order to include the effect of the true coincidence phenomenon. The modified main program that takes into consideration the true coincidence phenomenon was used for the full energy peak efficiency determination of an XtRa Ge detector with relative efficiency 104% and the results obtained for the 1173 keV and 1332 keV photons of 60Co were found consistent with respective experimental ones. The true coincidence correction factors were calculated as the ratio of the full energy peak efficiencies was determined from the original main program PENMAIN and the modified main program PENMAIN. The developed technique was applied for 57Co, 88Y, and 134Cs and for two source-to-detector geometries. The results obtained were compared with true coincidence correction factors calculated from the "TrueCoinc" program and the relative bias was found to be less than 2%, 4%, and 8% for 57Co, 88Y, and 134Cs, respectively.
Study on the eγ coincidences in the 169Lu decay
International Nuclear Information System (INIS)
Batsev, S.; Bonch-Osmolovskaya, N.A.; Budzyak, A.; Kuznetsov, V.V.; Usmanov, R.R.
1979-01-01
The 169 Lu→ 169 Yb decay scheme was analyzed on the basis of measurements of eγ coincidence. The 169 Lu sources were obtained by irradiating a tantalum target by 660 MeV protons. The eγ-coincidence spectra were measured by an ironless β-spectrometer with a toroidal magnetic field and a detector. The γ-ray and eγ-coincidence spectra were processed by a computer. The results of processing the 169 Lu coincidence spectra are tabulated. No excited states of 169 Yb not confirmed by γγ and eγ coincidences (except for the head level of the 3/2 + (651) 720 keV band) remain in the 169 Lu decay scheme proposed. Weak transitions with the total intensity of no more than 3.3% per a 169 Lu decay have remained unarranged, they should discharge weakly excited levels of 169 Yb. Probabilities of the 169 Yb level population per a 169 Lu decay and the corresponding values of probabilities of transitions in them are presented. As a whole, the 169 Lu decay scheme involves 60 levels, 31 states of them are new
Coincidence Imaging and interference with coherent Gaussian beams
Institute of Scientific and Technical Information of China (English)
CAI Yang-jian; ZHU Shi-yao
2006-01-01
we present a theoretical study of coincidence imaging and interference with coherent Gaussian beams The equations for the coincidence image formation and interference fringes are derived,from which it is clear that the imaging is due to the corresponding focusing in the two paths .The quality and visibility of the images and fringes can be high simultaneously.The nature of the coincidence imaging and interference between quantum entangled photon pairs and coherent Gaussian beams are different .The coincidence image with coherent Gaussian beams is due to intensity-intensity correspondence,a classical nature,while that with entangled photon pairs is due to the amplitude correlation a quantum nature.
Neutron Skins and Neutron Stars
Piekarewicz, J.
2013-01-01
The neutron-skin thickness of heavy nuclei provides a fundamental link to the equation of state of neutron-rich matter, and hence to the properties of neutron stars. The Lead Radius Experiment ("PREX") at Jefferson Laboratory has recently provided the first model-independence evidence on the existence of a neutron-rich skin in 208Pb. In this contribution we examine how the increased accuracy in the determination of neutron skins expected from the commissioning of intense polarized electron be...
Neutron activation system for spectral measurements of pulsed ion diode neutron production
International Nuclear Information System (INIS)
Hanson, D.L.; Kruse, L.W.
1980-02-01
A neutron energy spectrometer has been developed to study intense ion beam-target interactions in the harsh radiation environment of a relativistic electron beam source. The main component is a neutron threshold activation system employing two multiplexed high efficiency Ge(Li) detectors, an annihilation gamma coincidence system, and a pneumatic sample transport. Additional constraints on the neutron spectrum are provided by total neutron yield and time-of-flight measurements. A practical lower limit on the total neutron yield into 4π required for a spectral measurement with this system is approx. 10 10 n where the neutron yield is predominantly below 4 MeV and approx. 10 8 n when a significant fraction of the yield is above 4 MeV. Applications of this system to pulsed ion diode neutron production experiments on Hermes II are described
Neutron-neutron quasifree scattering in nd breakup at 10 MeV
Directory of Open Access Journals (Sweden)
Malone R.C.
2016-01-01
We are conducting new measurements of the cross section for nn QFS in nd breakup. The measurements are performed at incident neutron beam energies below 20 MeV. The neutron beam is produced via the 2H(d, n3He reaction. The target is a deuterated plastic cylinder. Our measurements utilize time-of-flight techniques with a pulsed neutron beam and detection of the two emitted neutrons in coincidence. A description of our initial measurements at 10 MeV for a single scattering angle will be presented along with preliminary results. Also, plans for measurements at other energies with broad angular coverage will be discussed.
Directory of Open Access Journals (Sweden)
Wonkyeong Kim
2015-01-01
Full Text Available A high-leakage core has been known to be a challenging problem not only for a two-step homogenization approach but also for a direct heterogeneous approach. In this paper the DIMPLE S06 core, which is a small high-leakage core, has been analyzed by a direct heterogeneous modeling approach and by a two-step homogenization modeling approach, using contemporary code systems developed for reactor core analysis. The focus of this work is a comprehensive comparative analysis of the conventional approaches and codes with a small core design, DIMPLE S06 critical experiment. The calculation procedure for the two approaches is explicitly presented in this paper. Comprehensive comparative analysis is performed by neutronics parameters: multiplication factor and assembly power distribution. Comparison of two-group homogenized cross sections from each lattice physics codes shows that the generated transport cross section has significant difference according to the transport approximation to treat anisotropic scattering effect. The necessity of the ADF to correct the discontinuity at the assembly interfaces is clearly presented by the flux distributions and the result of two-step approach. Finally, the two approaches show consistent results for all codes, while the comparison with the reference generated by MCNP shows significant error except for another Monte Carlo code, SERPENT2.
International Nuclear Information System (INIS)
Macias B, L.R.
1991-05-01
The objective of this work consists on determining the calibration in the angular parameters and the neutron wavelength used in the neutron diffractometer of the TRIGA Mark III reactor, through some readings in that a well-known sample is used by means of a Fortran computer program that is used in the CYBER computer of the ININ in Mexico, and/or in micro computers compatible with IBM. The program was also designed to determine the zero of the 2 θ angle of the goniometer of the diffractometer. The generated data were proven by means of well-known data of the Powder Diffraction File of the Joint Committee on Powder Diffraction Standards (JCPDS). (Author)
International Nuclear Information System (INIS)
Buckman, S.M.
1995-03-01
The major part of the thesis is devoted to the theoretical development of a comprehensive PC-based statistical package for the analysis of data from coincidence-counting experiments. This analysis is applied to primary standardizations of Co performed in Australia and Japan. The Australian standardisation, the accuracy of which is confirmed through international comparison, is used to re-calibrate the ionisation chamber. Both Australian and Japanese coincidence-counting systems are interfaced to personal computers to enable replicated sets of measurements to be made under computer control. Further research to confirm the validity of the statistical model includes an experimental investigation into the non-Poisson behaviour of radiation detectors due to the effect of deadtime. Experimental investigation is conducted to determine which areas are most likely to limit the ultimate accuracy achievable with coincidence counting. The thesis concludes by discussing the possibilities of digital coincidence counting and outlines the design of a prototype system presently under development. The accuracy of the Australian standardisation is confirmed by international comparison. From this result a more accurate Co calibration is obtained for the Australian working standard. Based on the work of this thesis, uncertainties in coincidence counting experiments can be better handled with resulting improvements in measurement reliability. The concept and benefits of digital coincidence counting are discussed and a proposed design is given for such a system. All of the data and software associated with this thesis is provided on computer discs. 237 refs., figs., tabs
International Nuclear Information System (INIS)
Vanhavere, F.
2001-01-01
The objective of SCK-CEN's R and D programme on neutron dosimetry is to improve the determination of neutron doses by studying neutron spectra, neutron dosemeters and shielding adaptations. In 2000, R and D focused on the contiued investigation of the bubble detectors type BD-PND and BDT, in particular their sensitivity and temperature dependence; the updating of SCK-CEN's criticality dosemeter, the investigation of the characteristics of new thermoluminescent materials and their use in neutron dosemetry; and the investigation of neutron shielding
Energy Technology Data Exchange (ETDEWEB)
Vanhavere, F
2001-04-01
The objective of SCK-CEN's R and D programme on neutron dosimetry is to improve the determination of neutron doses by studying neutron spectra, neutron dosemeters and shielding adaptations. In 2000, R and D focused on the contiued investigation of the bubble detectors type BD-PND and BDT, in particular their sensitivity and temperature dependence; the updating of SCK-CEN's criticality dosemeter, the investigation of the characteristics of new thermoluminescent materials and their use in neutron dosemetry; and the investigation of neutron shielding.
International Nuclear Information System (INIS)
Sadowski, E.T.; Griffin, J.C.; Rinard, P.M.
1991-01-01
A Scrap Californium Shuffler at the Savannah River Site (SRS) was calibrated to assay the U-Al cores of billets (an intermediate step in the SRS reactor fuel fabrication cycle.) The precision of the Scrap Shuffler over several years has been approximately 0.50%. A typical total uncertainty for the assay of a core on the Scrap Shuffler is approximately 0.33% for a twelve minute assay. The precision over several months and a typical total uncertainty for the Billet Active Well (neutron) Coincidence Counter (BAWCC) are approximately 1.0% and 1.9%, respectively, for a fifteen minute assay. A new Billet Californium Shuffler specifically designed for assaying SRS billets has yielded precision (over one month) and total uncertainty results of 0.40% and 0.69%, respectively, for an eight minute assay. The introduction of a measurement point into the fuel fabrication cycle to replace estimates based upon material weight will greatly enhance material and process control in the Reactor Materials area of SRS. The use of all three instruments provides a comparison of the relative merits of Active Well (neutron) Coincidence Counters (AWCCs) and shufflers for assay of homogeneous and geometrically simple material containing 235 U. The measurement precisions, systematic and random uncertainties, as well as the procurement and operation of each instrument will be compared. 3 refs., 5 figs., 1 tab
Calculation of coincidence summing corrections for a specific small soil sample geometry
Energy Technology Data Exchange (ETDEWEB)
Helmer, R.G.; Gehrke, R.J.
1996-10-01
Previously, a system was developed at the INEL for measuring the {gamma}-ray emitting nuclides in small soil samples for the purpose of environmental monitoring. These samples were counted close to a {approx}20% Ge detector and, therefore, it was necessary to take into account the coincidence summing that occurs for some nuclides. In order to improve the technical basis for the coincidence summing corrections, the authors have carried out a study of the variation in the coincidence summing probability with position within the sample volume. A Monte Carlo electron and photon transport code (CYLTRAN) was used to compute peak and total efficiencies for various photon energies from 30 to 2,000 keV at 30 points throughout the sample volume. The geometry for these calculations included the various components of the detector and source along with the shielding. The associated coincidence summing corrections were computed at these 30 positions in the sample volume and then averaged for the whole source. The influence of the soil and the detector shielding on the efficiencies was investigated.
Application of multi-thread computing and domain decomposition to the 3-D neutronics Fem code Cronos
International Nuclear Information System (INIS)
Ragusa, J.C.
2003-01-01
The purpose of this paper is to present the parallelization of the flux solver and the isotopic depletion module of the code, either using Message Passing Interface (MPI) or OpenMP. Thread parallelism using OpenMP was used to parallelize the mixed dual FEM (finite element method) flux solver MINOS. Investigations regarding the opportunity of mixing parallelism paradigms will be discussed. The isotopic depletion module was parallelized using domain decomposition and MPI. An attempt at using OpenMP was unsuccessful and will be explained. This paper is organized as follows: the first section recalls the different types of parallelism. The mixed dual flux solver and its parallelization are then presented. In the third section, we describe the isotopic depletion solver and its parallelization; and finally conclude with some future perspectives. Parallel applications are mandatory for fine mesh 3-dimensional transport and simplified transport multigroup calculations. The MINOS solver of the FEM neutronics code CRONOS2 was parallelized using the directive based standard OpenMP. An efficiency of 80% (resp. 60%) was achieved with 2 (resp. 4) threads. Parallelization of the isotopic depletion solver was obtained using domain decomposition principles and MPI. Efficiencies greater than 90% were reached. These parallel implementations were tested on a shared memory symmetric multiprocessor (SMP) cluster machine. The OpenMP implementation in the solver MINOS is only the first step towards fully using the SMPs cluster potential with a mixed mode parallelism. Mixed mode parallelism can be achieved by combining message passing interface between clusters with OpenMP implicit parallelism within a cluster
Application of multi-thread computing and domain decomposition to the 3-D neutronics Fem code Cronos
Energy Technology Data Exchange (ETDEWEB)
Ragusa, J.C. [CEA Saclay, Direction de l' Energie Nucleaire, Service d' Etudes des Reacteurs et de Modelisations Avancees (DEN/SERMA), 91 - Gif sur Yvette (France)
2003-07-01
The purpose of this paper is to present the parallelization of the flux solver and the isotopic depletion module of the code, either using Message Passing Interface (MPI) or OpenMP. Thread parallelism using OpenMP was used to parallelize the mixed dual FEM (finite element method) flux solver MINOS. Investigations regarding the opportunity of mixing parallelism paradigms will be discussed. The isotopic depletion module was parallelized using domain decomposition and MPI. An attempt at using OpenMP was unsuccessful and will be explained. This paper is organized as follows: the first section recalls the different types of parallelism. The mixed dual flux solver and its parallelization are then presented. In the third section, we describe the isotopic depletion solver and its parallelization; and finally conclude with some future perspectives. Parallel applications are mandatory for fine mesh 3-dimensional transport and simplified transport multigroup calculations. The MINOS solver of the FEM neutronics code CRONOS2 was parallelized using the directive based standard OpenMP. An efficiency of 80% (resp. 60%) was achieved with 2 (resp. 4) threads. Parallelization of the isotopic depletion solver was obtained using domain decomposition principles and MPI. Efficiencies greater than 90% were reached. These parallel implementations were tested on a shared memory symmetric multiprocessor (SMP) cluster machine. The OpenMP implementation in the solver MINOS is only the first step towards fully using the SMPs cluster potential with a mixed mode parallelism. Mixed mode parallelism can be achieved by combining message passing interface between clusters with OpenMP implicit parallelism within a cluster.
Energy Technology Data Exchange (ETDEWEB)
Macias B, L R
1991-05-15
The objective of this work consists on determining the calibration in the angular parameters and the neutron wavelength used in the neutron diffractometer of the TRIGA Mark III reactor, through some readings in that a well-known sample is used by means of a Fortran computer program that is used in the CYBER computer of the ININ in Mexico, and/or in micro computers compatible with IBM. The program was also designed to determine the zero of the 2 {theta} angle of the goniometer of the diffractometer. The generated data were proven by means of well-known data of the Powder Diffraction File of the Joint Committee on Powder Diffraction Standards (JCPDS). (Author)
Neutronic analysis of JET external neutron monitor response
Energy Technology Data Exchange (ETDEWEB)
Snoj, Luka, E-mail: luka.snoj@ijs.si [Reactor Physics Division, Jožef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana (Slovenia); Lengar, Igor; Čufar, Aljaž [Reactor Physics Division, Jožef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana (Slovenia); Syme, Brian; Popovichev, Sergey [Culham Centre for Fusion Energy, Culham Science Centre, Abingdon, OX14 3DB, United Kingdom (United Kingdom); Batistoni, Paola [ENEA C. R. Frascati, via E. Fermi 45, 00044 Frascati, Roma (Italy); Conroy, Sean [VR Association, Uppsala University, Department of Physics and Astronomy, PO Box 516, SE-75120 Uppsala (Sweden)
2016-11-01
Highlights: • We model JET tokamak containing JET remote handling system. • We investigate effect of remote handling system on external neutron monitor response. • Remote handling system correction factors are calculated. • Integral correction factors are relatively small, i.e up to 8%. - Abstract: The power output of fusion devices is measured in terms of the neutron yield which relates directly to the fusion yield. JET made a transition from Carbon wall to ITER-Like Wall (Beryllium/Tungsten/Carbon) during 2010–11. Absolutely calibrated measurement of the neutron yield by JET neutron monitors was ensured by direct measurements using a calibrated {sup 252}Cf neutron source (NS) deployed by the in-vessel remote handling system (RHS) inside the JET vacuum vessel. Neutronic calculations were required in order to understand the neutron transport from the source in the vacuum vessel to the fission chamber detectors mounted outside the vessel on the transformer limbs of the tokamak. We developed a simplified computational model of JET and the JET RHS in Monte Carlo neutron transport code MCNP and analyzed the paths and structures through which neutrons reach the detectors and the effect of the JET RHS on the neutron monitor response. In addition we performed several sensitivity studies of the effect of substantial massive structures blocking the ports on the external neutron monitor response. As the simplified model provided a qualitative picture of the process only, some calculations were repeated using a more detailed full 3D model of the JET tokamak.
International Nuclear Information System (INIS)
Leal, L.C.; de Saussure, G.; Perez, R.B.
1990-01-01
The URR computer code has been developed to calculate cross-section probability tables, Bondarenko self-shielding factors, and self-indication ratios for fertile and fissile isotopes in the unresolved resonance region. Monte Carlo methods are utilized to select appropriate resonance parameters and to compute the cross sections at the desired reference energy. The neutron cross sections are calculated by the single-level Breit-Wigner formalism with s-, p-, and d-wave contributions. The cross-section probability tables are constructed by sampling by Doppler broadened cross-sections. The various self-shielding factors are computer numerically as Lebesgue integrals over the cross-section probability tables
A magnetic-lens - mini-orange coincidence spectrometer
International Nuclear Information System (INIS)
Bargholtz, C.; Holmberg, L.; Ruus, N.; Tegner, P.E.; Weiss, G.
1997-04-01
A coincidence spectrometer consisting of a Gerholm type magnetic lens and a permanent magnet mini-orange spectrometer is described. Electron-electron or electron-positron coincidences may be registered in various angular settings. The spectrometer has been developed mainly to search for anomalous contributions to Bhabha scattering or positrons and is at present used for such studies. 6 refs
An Inexpensive Coincidence Circuit for the Pasco Geiger Sensors
Fichera, F; Librizzi, F; Riggi, F
2005-01-01
A simple coincidence circuit was devised to carry out educational coincidence experiments involving the use of Geiger counters. The system was tested by commercially available Geiger sensors from PASCO, and is intended to be used in collaboration with high school students and teachers
Identification of peaks in multidimensional coincidence {gamma}-ray spectra
Energy Technology Data Exchange (ETDEWEB)
Morhac, Miroslav E-mail: fyzimiro@savba.sk; Kliman, Jan; Matousek, Vladislav; Veselsky, Martin; Turzo, Ivan
2000-03-21
In the paper a new algorithm to find peaks in two, three and multidimensional spectra, measured in large multidetector {gamma}-ray arrays, is derived. Given the dimension m, the algorithm is selective to m-fold coincidence peaks. It is insensitive to intersections of lower-fold coincidences, hereinafter called ridges.
Identification of peaks in multidimensional coincidence γ-ray spectra
International Nuclear Information System (INIS)
Morhac, Miroslav; Kliman, Jan; Matousek, Vladislav; Veselsky, Martin; Turzo, Ivan
2000-01-01
In the paper a new algorithm to find peaks in two, three and multidimensional spectra, measured in large multidetector γ-ray arrays, is derived. Given the dimension m, the algorithm is selective to m-fold coincidence peaks. It is insensitive to intersections of lower-fold coincidences, hereinafter called ridges
International Nuclear Information System (INIS)
Wilmore, D.; Hodgson, P.E.
1976-01-01
The purpose of this paper is to provide a guide to the use of optical model computer programs to analyse and calculate neutron data. After a brief discussion of the physical basis of the optical model a survey is given of the most widely used optical model and Hauser-Feshbach computer programs. The range of applicability and reliability of the major optical potentials proposed is assessed by comparison with available experimental data and some observations and suggestions are made for the optimum choice of optical potentials for given purposes of neutron data calculations. (author)
Recovery and normalization of triple coincidences in PET
Energy Technology Data Exchange (ETDEWEB)
Lage, Eduardo, E-mail: elage@mit.edu; Parot, Vicente; Dave, Shivang R.; Herraiz, Joaquin L. [Madrid-MIT M+Visión Consortium, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Moore, Stephen C.; Sitek, Arkadiusz; Park, Mi-Ae [Division of Nuclear Medicine, Department of Radiology, Harvard Medical School and Brigham and Women’s Hospital, Boston, Massachusetts 02115 (United States); Udías, Jose M. [Grupo de Física Nuclear, Departamento de Física Atómica Molecular y Nuclear, Universidad Complutense de Madrid, CEI Moncloa, Madrid 28040 (Spain); Vaquero, Juan J. [Departamento de Ingeniería Biomédica e Ingeniería Aeroespacial, Universidad Carlos III de Madrid, Leganés 28911 (Spain)
2015-03-15
Purpose: Triple coincidences in positron emission tomography (PET) are events in which three γ-rays are detected simultaneously. These events, though potentially useful for enhancing the sensitivity of PET scanners, are discarded or processed without special consideration in current systems, because there is not a clear criterion for assigning them to a unique line-of-response (LOR). Methods proposed for recovering such events usually rely on the use of highly specialized detection systems, hampering general adoption, and/or are based on Compton-scatter kinematics and, consequently, are limited in accuracy by the energy resolution of standard PET detectors. In this work, the authors propose a simple and general solution for recovering triple coincidences, which does not require specialized detectors or additional energy resolution requirements. Methods: To recover triple coincidences, the authors’ method distributes such events among their possible LORs using the relative proportions of double coincidences in these LORs. The authors show analytically that this assignment scheme represents the maximum-likelihood solution for the triple-coincidence distribution problem. The PET component of a preclinical PET/CT scanner was adapted to enable the acquisition and processing of triple coincidences. Since the efficiencies for detecting double and triple events were found to be different throughout the scanner field-of-view, a normalization procedure specific for triple coincidences was also developed. The effect of including triple coincidences using their method was compared against the cases of equally weighting the triples among their possible LORs and discarding all the triple events. The authors used as figures of merit for this comparison sensitivity, noise-equivalent count (NEC) rates and image quality calculated as described in the NEMA NU-4 protocol for the assessment of preclinical PET scanners. Results: The addition of triple-coincidence events with the
Recovery and normalization of triple coincidences in PET.
Lage, Eduardo; Parot, Vicente; Moore, Stephen C; Sitek, Arkadiusz; Udías, Jose M; Dave, Shivang R; Park, Mi-Ae; Vaquero, Juan J; Herraiz, Joaquin L
2015-03-01
Triple coincidences in positron emission tomography (PET) are events in which three γ-rays are detected simultaneously. These events, though potentially useful for enhancing the sensitivity of PET scanners, are discarded or processed without special consideration in current systems, because there is not a clear criterion for assigning them to a unique line-of-response (LOR). Methods proposed for recovering such events usually rely on the use of highly specialized detection systems, hampering general adoption, and/or are based on Compton-scatter kinematics and, consequently, are limited in accuracy by the energy resolution of standard PET detectors. In this work, the authors propose a simple and general solution for recovering triple coincidences, which does not require specialized detectors or additional energy resolution requirements. To recover triple coincidences, the authors' method distributes such events among their possible LORs using the relative proportions of double coincidences in these LORs. The authors show analytically that this assignment scheme represents the maximum-likelihood solution for the triple-coincidence distribution problem. The PET component of a preclinical PET/CT scanner was adapted to enable the acquisition and processing of triple coincidences. Since the efficiencies for detecting double and triple events were found to be different throughout the scanner field-of-view, a normalization procedure specific for triple coincidences was also developed. The effect of including triple coincidences using their method was compared against the cases of equally weighting the triples among their possible LORs and discarding all the triple events. The authors used as figures of merit for this comparison sensitivity, noise-equivalent count (NEC) rates and image quality calculated as described in the NEMA NU-4 protocol for the assessment of preclinical PET scanners. The addition of triple-coincidence events with the authors' method increased peak
High rate 4π β-γ coincidence counting system
International Nuclear Information System (INIS)
Johnson, L.O.; Gehrke, R.J.
1978-01-01
A high count rate 4π β-γ coincidence counting system for the determination of absolute disintegration rates of short half-life radionuclides is described. With this system the dead time per pulse is minimized by not stretching any pulses beyond the width necessary to satisfy overlap coincidence requirements. The equations used to correct for the β, γ, and coincidence channel dead times and for accidental coincidences are presented but not rigorously developed. Experimental results are presented for a decaying source of 56 Mn initially at 2 x 10 6 d/s and a set of 60 Co sources of accurately known source strengths varying from 10 3 to 2 x 10 6 d/s. A check of the accidental coincidence equation for the case of two independent sources with varying source strengths is presented
Standardisation of 64Cu using a software coincidence counting system
International Nuclear Information System (INIS)
Havelka, Miroslav; Sochorová, Jana
2014-01-01
The activity of the radionuclide 64 Cu was determined by the efficiency extrapolation method applied to 4π(PC)−γ coincidence counting. The standardisation was performed by software coincidence counting—a digital method for primary activity measurement that simplifies the setting of optimal coincidence parameters. The γ-ray-energy window, characterised by identical gamma detection efficiency related to the sum of EC and to the sum of beta decay branches, was found. This setting ensured a linear and zero slope extrapolation curve. - Highlights: • Standardisation realised by extrapolation method applied to 4π(PC)−γ coincidence. • Digital method for optimal setting of coincidence parameters was used. • Result with total standard uncertainty of 0.74% was obtained
International Nuclear Information System (INIS)
Hrdlicka, Z.
1977-01-01
Neutron radiography is a radiographic method using a neutron beam of a defined geometry. The neutron source usually consists of a research reactor, a specialized neutron radiography reactor or the 252 Cf radioisotope source. There are two types of the neutron radiography display system, viz., a system producing neutron radiography images by a photographic process or a system allowing a visual display, eg., using a television monitor. The method can be used wherever X-ray radiography is used except applications in the radiography of humans. The neutron radiography unit at UJV uses the WWR-S reactor as the neutron source and both types of the above mentioned display system. (J.P.)
Energy Technology Data Exchange (ETDEWEB)
Viana, Rodrigo S.S.; Yoriyaz, Helio [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, (SP) (Brazil)
2011-07-01
In this paper we presented an application of the Neutron Stimulated Emission Computed Tomography (NSECT), which uses a thin beam of fast neutrons to stimulate stable nuclei in a sample, emitting characteristic gamma radiation. The photon energy is unique and it is used to identify the emitting nuclei. This technique was applied for evaluating the calcium isotopic composition changing due to the development of breast microcalcifications. A particular situation was simulated in which clustered microcalcifications were modeled with diameters less than 1.40 mm. In this case, neutron beam breast spectroscopy was successful in detecting the counting changes in the photon emission spectra for energies, which are characteristics of 4{sup 0C}a isotope in a low deposited dose rate. (author)
Advances in passive neutron instruments for safeguards use
International Nuclear Information System (INIS)
Menlove, H.O.; Krick, M.S.; Langner, D.G.; Miller, M.C.; Stewart, J.E.
1994-01-01
Passive neutron and other nondestructive assay techniques have been used extensively by the International Atomic Energy Agency to verify plutonium metal, powder, mixed oxide, pellets, rods, assemblies, scrap, and liquids. Normally, the coincidence counting rate is used to measure the 240 Pu-effective mass and gamma-ray spectrometry or mass spectrometry is used to verify the plutonium isotopic ratios. During the past few years, the passive neutron detectors have been installed in plants and operated in the unattended/continuous mode. These radiation data with time continuity have made it possible to use the totals counting rate to monitor the movement of nuclear material. Monte Carlo computer codes have been used to optimize the detector designs for specific applications. The inventory sample counter (INVS-III) has been designed to have a higher efficiency (43%) and a larger uniform counting volume than the original INVS. Data analyses techniques have been developed, including the ''known alpha'' and ''known multiplication'' methods that depend on the sample. For scrap and other impure or poorly characterized samples, we have developed multiplicity counting, initially implemented in the plutonium scrap multiplicity counter. For large waste containers such as 200-L drums, we have developed the add-a-source technique to give accurate corrections for the waste-matrix materials. This paper summarizes recent developments in the design and application of passive neutron assay systems
Energy Technology Data Exchange (ETDEWEB)
Saion, E.B.; Watt, D.E. (Saint Andrews Univ. (UK). Dept. of Physics); East, B.W. (Scottish Universities Research and Reactor Centre, Glasgow (UK)); Colautti, P. (Istituto Nazionale di Fisica Nucleare, Padua (Italy))
1990-01-01
A new low pressure tissue-equivalent proportional counter (TEPC) in a coaxial double cylindrical form has been developed to measure separately the microdose spectrum from any desired energy band of neutrons in the presence of mixed fields of faster neutrons, by selecting the thickness of the common TE dividing wall to be equivalent to the corresponding maximum proton ranges and by appropriate use of coincidence/anti-coincidence pulse arrangements. This thickness ensures charged particle equilibrium for the relevant neutron energy. Event spectra due to recoils generated by faster neutrons which interact with both the counters are removed completely by anti-coincidence techniques, thereby optimising the sensitivity of the inner microdosemeter to the event spectra of interest. The ability of this counter to discriminate in favour of events due to neutrons of energy <850 keV was achieved in microdosimetric measurements from mixed fields of a nuclear reactor. Mean values of lineal energy and quality factor for neutrons of energy <850 keV from a nuclear reactor were determined from the anti-coincidence spectrum. Good discrimination against {gamma} ray induced events is also achieved for the spectrum recorded in the anti-coincidence mode. This is an advantageous feature for other applications and requires further investigation. (author).
International Nuclear Information System (INIS)
Saion, E.B.; Watt, D.E.; Colautti, P.
1990-01-01
A new low pressure tissue-equivalent proportional counter (TEPC) in a coaxial double cylindrical form has been developed to measure separately the microdose spectrum from any desired energy band of neutrons in the presence of mixed fields of faster neutrons, by selecting the thickness of the common TE dividing wall to be equivalent to the corresponding maximum proton ranges and by appropriate use of coincidence/anti-coincidence pulse arrangements. This thickness ensures charged particle equilibrium for the relevant neutron energy. Event spectra due to recoils generated by faster neutrons which interact with both the counters are removed completely by anti-coincidence techniques, thereby optimising the sensitivity of the inner microdosemeter to the event spectra of interest. The ability of this counter to discriminate in favour of events due to neutrons of energy <850 keV was achieved in microdosimetric measurements from mixed fields of a nuclear reactor. Mean values of lineal energy and quality factor for neutrons of energy <850 keV from a nuclear reactor were determined from the anti-coincidence spectrum. Good discrimination against γ ray induced events is also achieved for the spectrum recorded in the anti-coincidence mode. This is an advantageous feature for other applications and requires further investigation. (author)
International Nuclear Information System (INIS)
Menlove, H.O.
2005-01-01
We have designed a portable neutron detector for passive neutron scanning measurement and coincidence counting of bulk samples of plutonium. The counter will be used for neutron survey applications as well as the measurement of plutonium samples for portable applications. The detector uses advanced design 3 He tubes to increase the efficiency and battery operated shift register electronics. This report describes the hardware, performance, and calibration for the system
International Nuclear Information System (INIS)
Kredov, B.M.
1979-01-01
The history of the neutron is displayed on the basis of contributions by scientists who produced outstanding results in neutron research (part 1), of summarizing discoveries and theories which led to the discovery of the neutron and the resulting development of nuclear physics (part 2), and of fundamental papers written by Rutherford, Chadwick, Iwanenko, and others (appendix). Of interest to physicists, historians, and students
International Nuclear Information System (INIS)
Charlton, J.S.
1986-01-01
The way in which neutrons interact with matter such as slowing-down, diffusion, neutron absorption and moderation are described. The use of neutron techniques in industry, in moisture gages, level and interface measurements, the detection of blockages, boron analysis in ore feedstock and industrial radiography are discussed. (author)
International Nuclear Information System (INIS)
Satoh, Daiki; Sato, Tatsuhiko; Shigyo, Nobuhiro; Ishibashi, Kenji
2006-11-01
The Monte Carlo based computer code SCINFUL-QMD has been developed to evaluate response function and detection efficiency of a liquid organic scintillator for neutrons from 0.1 MeV to 3 GeV. This code is a modified version of SCINFUL that was developed at Oak Ridge National Laboratory in 1988, to provide a calculated full response anticipated for neutron interactions in a scintillator. The upper limit of the applicable energy was extended from 80 MeV to 3 GeV by introducing the quantum molecular dynamics incorporated with the statistical decay model (QMD+SDM) in the high-energy nuclear reaction part. The particles generated in QMD+SDM are neutron, proton, deuteron, triton, 3 He nucleus, alpha particle, and charged pion. Secondary reactions by neutron, proton, and pion inside the scintillator are also taken into account. With the extension of the applicable energy, the database of total cross sections for hydrogen and carbon nuclei were upgraded. This report describes the physical model, computational flow and how to use the code. (author)
Development of DUPIC safeguards neutron counter
Energy Technology Data Exchange (ETDEWEB)
Lee, Young Gil; Cha, Hong Ryul; Kim, Ho Dong; Hong, Jong Sook; Kang, Hee Young
1999-08-01
KAERI, in cooperation with LANL, developed DSNC (DUPIC Safeguards Neutron Counter) for safeguards implementing on DUPIC process which is under development by KAERI for direct use of spent PWR fuel in CANDU reactors. DSNC is a well-type neutron coincidence counter with substantial shielding to protect system from high gamma radiation of spent fuel. General development procedures in terms of design, manufacturing, fabrication, cold and hot test, performance test for DSNC authentication by KAERI-IAEA-LANL are described in this report. It is expected that the techniques related DSNC development and associated neutron detection and evaluation method could be applied for safeguards improvement. (Author). 20 refs., 16 tabs. 98 figs.
Utilizing horizontal reactors channels for neutron therapy
International Nuclear Information System (INIS)
Stankovsky, E.Yu.; Kurachenko, Yu.A.
2000-01-01
Two experimental heterogeneous reactors have been considered. The reactors may be applied in neutron capture therapy and in a conventional manner. The channel out of the core serves as the neutron source. At each of these facilities, both fast and epithermal neutron fluxes for BNCT research, human clinical trials, and characterized common computational techniques have been evaluated. (authors)
Energy Technology Data Exchange (ETDEWEB)
Rohatgi, U.S.; Cheng, H.S.; Khan, H.J.; Mallen, A.N.; Neymotin, L.Y.
1998-03-01
This document is the User`s Manual for the Boiling Water Reactor (BWR), and Simplified Boiling Water Reactor (SBWR) systems transient code RAMONA-4B. The code uses a three-dimensional neutron-kinetics model coupled with a multichannel, nonequilibrium, drift-flux, phase-flow model of the thermal hydraulics of the reactor vessel. The code is designed to analyze a wide spectrum of BWR core and system transients. Chapter 1 gives an overview of the code`s capabilities and limitations; Chapter 2 describes the code`s structure, lists major subroutines, and discusses the computer requirements. Chapter 3 is on code, auxillary codes, and instructions for running RAMONA-4B on Sun SPARC and IBM Workstations. Chapter 4 contains component descriptions and detailed card-by-card input instructions. Chapter 5 provides samples of the tabulated output for the steady-state and transient calculations and discusses the plotting procedures for the steady-state and transient calculations. Three appendices contain important user and programmer information: lists of plot variables (Appendix A) listings of input deck for sample problem (Appendix B), and a description of the plotting program PAD (Appendix C). 24 refs., 18 figs., 11 tabs.
Neutron spectrum unfolding: Pt. 2
International Nuclear Information System (INIS)
Matiullah; Wiyaja, D.S.; Berzonis, M.A.; Bondars, H.; Lapenas, A.A.; Kudo, K.; Majeed, A.; Durrani, S.A.
1991-01-01
In Part I of this paper, we described the use of the computer code SAIPS in neutron spectrum unfolding. Here in Part II, we present our experimental work carried out to study the shape of the neutron spectrum in different experimental channels of a 5 MW light-water cooled and moderated research reactor. The spectral neutron flux was determined using various fission foils (placed in close contact with mica track detectors) and activation detectors. From the measured activities, the neutron spectrum was unfolded by SAIPS. (author)
Array detector for neutron pre-emission investigations
International Nuclear Information System (INIS)
Petrascu, M.; Cruceru, I.; Bordeanu, C.
1999-01-01
It was predicted that in a fusion experiment induced by 11 Li halo nuclei on light targets, due to the very large dimension of 11 Li, one may expect that the valence neutrons will not be absorbed together with the 9 Li core, but will be emitted in the early stage of the fusion process. The experiment aiming at checking this expectation was performed at the RIKEN-RIPS facility. It was found from neutron energy spectra measurements, that an important number of fusions, more than 30%, are preceded by the pre-emission of one or two neutrons. In the position spectra measurements a very narrow neutron component has been found. This component is much narrower than that calculated by using the Cluster Shell Model Approximation (COSMA). The recent results of time- position coincidence measurements show that within the narrow component the neutrons are pre-emitted predominantly as neutron pairs. The Program Advisory Committee of RIKEN has approved a new measurement at RIKEN Ring Cyclotron aiming at investigation of neutron-neutron coincidences by using a new neutron array detector. This detector has been recently accomplished within the collaboration existing between IFIN-HH, Romania and RIKEN, Japan. The array system consists of 81 4 x 4 x 12 cm 3 BC400 plastic scintillators each coupled to XP2972 Phototubes. The mounting and the testing of the new neutron array detector will be done at RIKEN. The components of one of the 81 elements of the array detector are shown in a photo. The Monte Carlo calculated neutron detection efficiencies as a function of energy are shown. This detector will be used for the investigation of neutron-neutron coincidences in the case of Si( 11 Li, fusion) reaction. The cross- talk between adjacent and non adjacent detectors will be determined by using a 9 Li beam. As it is known in the case of Si( 9 Li, fusion) the neutrons are of evaporation origin, and since these neutrons are emitted in 4 π the chance for detecting 2 coincident neutrons in the
Low-resource synchronous coincidence processor for positron emission tomography
International Nuclear Information System (INIS)
Sportelli, Giancarlo; Belcari, Nicola; Guerra, Pedro; Santos, Andres
2011-01-01
We developed a new FPGA-based method for coincidence detection in positron emission tomography. The method requires low device resources and no specific peripherals in order to resolve coincident digital pulses within a time window of a few nanoseconds. This method has been validated with a low-end Xilinx Spartan-3E and provided coincidence resolutions lower than 6 ns. This resolution depends directly on the signal propagation properties of the target device and the maximum available clock frequency, therefore it is expected to improve considerably on higher-end FPGAs.
International Nuclear Information System (INIS)
Zucker, M.S.; Holden, N.E.
1986-01-01
Recent development in the theory and practice of neutron correlation (''coincidence'') counting require knowledge of the higher factorial moments of the P/sub ν/ distribution (the probability that (ν) neutrons are emitted in a fission) for the case where the fission is induced by bombarding neutrons of more than thermal energies. In contrast to the situation with spontaneous and thermal neutron induced fission, where with a few exceptions the P/sub ν/ is reasonably well known, in the fast neutron energy region, almost no information is available concerning the multiplicity beyond the average value, [ν], even for the most important nuclides. The reason for this is the difficulty of such experiments, with consequent statistically poor and physically inconsistent results
M. Kasemann
Overview In autumn the main focus was to process and handle CRAFT data and to perform the Summer08 MC production. The operational aspects were well covered by regular Computing Shifts, experts on duty and Computing Run Coordination. At the Computing Resource Board (CRB) in October a model to account for service work at Tier 2s was approved. The computing resources for 2009 were reviewed for presentation at the C-RRB. The quarterly resource monitoring is continuing. Facilities/Infrastructure operations Operations during CRAFT data taking ran fine. This proved to be a very valuable experience for T0 workflows and operations. The transfers of custodial data to most T1s went smoothly. A first round of reprocessing started at the Tier-1 centers end of November; it will take about two weeks. The Computing Shifts procedure was tested full scale during this period and proved to be very efficient: 30 Computing Shifts Persons (CSP) and 10 Computing Resources Coordinators (CRC). The shift program for the shut down w...
Unbiased estimators of coincidence and correlation in non-analogous Monte Carlo particle transport
International Nuclear Information System (INIS)
Szieberth, M.; Kloosterman, J.L.
2014-01-01
Highlights: • The history splitting method was developed for non-Boltzmann Monte Carlo estimators. • The method allows variance reduction for pulse-height and higher moment estimators. • It works in highly multiplicative problems but Russian roulette has to be replaced. • Estimation of higher moments allows the simulation of neutron noise measurements. • Biased sampling of fission helps the effective simulation of neutron noise methods. - Abstract: The conventional non-analogous Monte Carlo methods are optimized to preserve the mean value of the distributions. Therefore, they are not suited to non-Boltzmann problems such as the estimation of coincidences or correlations. This paper presents a general method called history splitting for the non-analogous estimation of such quantities. The basic principle of the method is that a non-analogous particle history can be interpreted as a collection of analogous histories with different weights according to the probability of their realization. Calculations with a simple Monte Carlo program for a pulse-height-type estimator prove that the method is feasible and provides unbiased estimation. Different variance reduction techniques have been tried with the method and Russian roulette turned out to be ineffective in high multiplicity systems. An alternative history control method is applied instead. Simulation results of an auto-correlation (Rossi-α) measurement show that even the reconstruction of the higher moments is possible with the history splitting method, which makes the simulation of neutron noise measurements feasible
Neutron-proton bremsstrahlung experiments
Energy Technology Data Exchange (ETDEWEB)
Koster, J.E. (Los Alamos National Lab., NM (United States)); Nelson, R.O. (Los Alamos National Lab., NM (United States)); Schillaci, M.E. (Los Alamos National Lab., NM (United States)); Wender, S.A. (Los Alamos National Lab., NM (United States)); Mayo, D. (Univ. of California at Davis, CA (United States)); Brady, F.P. (Univ. of California at Davis, CA (United States)); Romero, J. (Univ. of California at Davis, CA (United States)); Krofcheck, D. (Lawrence Livermore National Lab., CA (United States)); Blann, M. (Lawrence Livermore National Lab., CA (United States)); Anthony, P. (Lawrence Livermore National Lab., CA (United States)); Brown, V.R. (Lawrence Livermore National Lab., CA (United States)); Hansen, L. (Lawrence Livermore National Lab., CA (United States)); Pohl, B. (Lawrence Livermore National Lab., CA (United States)); Sangster, T.C. (Lawrence Livermore National Lab., CA (United States)); Nifenecker, H. (Inst. des Sciences Nucleaires, Grenoble (France)); Pinston,
1993-06-01
It is well known that charged particles emit bremsstrahlung radiation when they are accelerated. Classical electron bremsstrahlung occurs when a proton is emitted by an electron accelerated in the field of a nucleus. The bremsstrahlung process also occurs in the scattering of nucleons, for which it is the lowest energy inelastic process that can occur. Like electron bremsstrahlung, nucleon-nucleon bremsstrahlung also requires the exchange of a virtual particle to conserve energy and momentum. In electron bremsstrahlung a virtual photon is exchanged but with two nucleons a meson can be exchanged. Unlike electron bremsstrahlung, in nucleon-nucleon bremsstrahlung the photon can originate from the exchanged meson. This exchange contribution has been shown in calculations to be a significant fraction of bremsstrahlung events. Thus bremsstrahlung serves as a probe of exchange currents in the nucleon-nucleon interaction. Because of a lack of a free neutron target or an intense neutron beam, few measurements of neutron-proton bremsstrahlung exist, each having poor statistical accuracy and poor energy resolution. The white neutron source at the Weapons Neutron Research (WNR) target area at the Los Alamos Meson Physics Facility (LAMPF) produces neutrons with energies from below 50 to above 400 MeV. Using time-of-flight techniques and a liquid hydrogen target, we are measuring the outgoing photons of energies up to 250 MeV at gamma ray angles of around 90 relative to the incident beam. Protons scattered at very forward angles are also detected in coincidence with the gamma rays. (orig.)
International Nuclear Information System (INIS)
Jewer, S.; Buchan, A.G.; Pain, C.C.; Cacuci, D.G.
2014-01-01
Highlights: • A new method of coupled radiation transport, heat and momentum exchanges on fluids, and heat transfer simulations. • Simulation of the thermal hydraulics and radiative properties within whole PWR assemblies. • An immersed body method for modelling complex solid domains on practical computational meshes. - Abstract: A recently developed immersed body method is adapted and used to model a typical pressurised water reactor (PWR) fuel assembly. The approach is implemented with the numerical framework of the finite element, transient criticality code, FETCH which is composed of the neutron transport code, EVENT, and the CFD code, FLUIDITY. Within this framework the neutron transport equation, Navier–Stokes equations and a fluid energy conservation equation are solved in a coupled manner on a coincident structured or unstructured mesh. The immersed body method has been used to model the solid fuel pins. The key feature of this method is that the fluid/neutronic domain and the solid domain are represented by overlapping and non-conforming meshes. The main difficulty of this approach, for which a solution is proposed in this work, is the conservative mapping of the energy and momentum exchange between the fluid/neutronic mesh and the solid fuel pin mesh. Three numerical examples are presented which include a validation of the fuel pin submodel against an analytical solution; an uncoupled (no neutron transport solution) PWR fuel assembly model with a specified power distribution which was validated against the COBRA-EN subchannel analysis code; and finally a coupled model of a PWR fuel assembly with reflective neutron boundary conditions. Coupling between the fluid and neutron transport solutions is through the nuclear cross sections dependence on Doppler fuel temperature, coolant density and temperature, which was taken into account by using pre-calculated cross-section lookup tables generated using WIMS9a. The method was found to show good agreement
THE LIMITED EFFECT OF COINCIDENT ORIENTATION ON THE CHOICE OF INTRINSIC AXIS (.).
Li, Jing; Su, Wei
2015-06-01
The allocentric system computes and represents general object-to-object spatial relationships to provide a spatial frame of reference other than the egocentric system. The intrinsic frame-of-reference system theory, which suggests people learn the locations of objects based upon an intrinsic axis, is important in research about the allocentric system. The purpose of the current study was to determine whether the effect of coincident orientation on the choice of intrinsic axis was limited. Two groups of participants (24 men, 24 women; M age = 24 yr., SD = 2) encoded different spatial layouts in which the objects shared the coincident orientation of 315° and 225° separately at learning perspective (0°). The response pattern of partial-scene-recognition task following learning reflected different strategies for choosing the intrinsic axis under different conditions. Under the 315° object-orientation condition, the objects' coincident orientation was as important as the symmetric axis in the choice of the intrinsic axis. However, participants were more likely to choose the symmetric axis as the intrinsic axis under the 225° object-orientation condition. The results suggest the effect of coincident orientation on the choice of intrinsic axis is limited.
I. Fisk
2011-01-01
Introduction CMS distributed computing system performed well during the 2011 start-up. The events in 2011 have more pile-up and are more complex than last year; this results in longer reconstruction times and harder events to simulate. Significant increases in computing capacity were delivered in April for all computing tiers, and the utilisation and load is close to the planning predictions. All computing centre tiers performed their expected functionalities. Heavy-Ion Programme The CMS Heavy-Ion Programme had a very strong showing at the Quark Matter conference. A large number of analyses were shown. The dedicated heavy-ion reconstruction facility at the Vanderbilt Tier-2 is still involved in some commissioning activities, but is available for processing and analysis. Facilities and Infrastructure Operations Facility and Infrastructure operations have been active with operations and several important deployment tasks. Facilities participated in the testing and deployment of WMAgent and WorkQueue+Request...
P. McBride
The Computing Project is preparing for a busy year where the primary emphasis of the project moves towards steady operations. Following the very successful completion of Computing Software and Analysis challenge, CSA06, last fall, we have reorganized and established four groups in computing area: Commissioning, User Support, Facility/Infrastructure Operations and Data Operations. These groups work closely together with groups from the Offline Project in planning for data processing and operations. Monte Carlo production has continued since CSA06, with about 30M events produced each month to be used for HLT studies and physics validation. Monte Carlo production will continue throughout the year in the preparation of large samples for physics and detector studies ramping to 50 M events/month for CSA07. Commissioning of the full CMS computing system is a major goal for 2007. Site monitoring is an important commissioning component and work is ongoing to devise CMS specific tests to be included in Service Availa...
M. Kasemann
Overview During the past three months activities were focused on data operations, testing and re-enforcing shift and operational procedures for data production and transfer, MC production and on user support. Planning of the computing resources in view of the new LHC calendar in ongoing. Two new task forces were created for supporting the integration work: Site Commissioning, which develops tools helping distributed sites to monitor job and data workflows, and Analysis Support, collecting the user experience and feedback during analysis activities and developing tools to increase efficiency. The development plan for DMWM for 2009/2011 was developed at the beginning of the year, based on the requirements from the Physics, Computing and Offline groups (see Offline section). The Computing management meeting at FermiLab on February 19th and 20th was an excellent opportunity discussing the impact and for addressing issues and solutions to the main challenges facing CMS computing. The lack of manpower is particul...
Applied neutron resonance theory
International Nuclear Information System (INIS)
Froehner, F.H.
1980-01-01
Utilisation of resonance theory in basic and applications-oriented neutron cross section work is reviewed. The technically important resonance formalisms, principal concepts and methods as well as representative computer programs for resonance parameter extraction from measured data, evaluation of resonance data, calculation of Doppler-broadened cross sections and estimation of level-statistical quantities from resonance parameters are described. (author)
Applied neutron resonance theory
International Nuclear Information System (INIS)
Froehner, F.H.
1978-07-01
Utilisation of resonance theory in basic and applications-oriented neutron cross section work is reviewed. The technically important resonance formalisms, principal concepts and methods as well as representative computer programs for resonance parameter extraction from measured data, evaluation of resonance data, calculation of Doppler-broadened cross sections and estimation of level-statistical quantities from resonance parameters are described. (orig.) [de
Permutational symmetries for coincidence rates in multimode multiphotonic interferometry
Khalid, Abdullah; Spivak, Dylan; Sanders, Barry C.; de Guise, Hubert
2018-06-01
We obtain coincidence rates for passive optical interferometry by exploiting the permutational symmetries of partially distinguishable input photons, and our approach elucidates qualitative features of multiphoton coincidence landscapes. We treat the interferometer input as a product state of any number of photons in each input mode with photons distinguished by their arrival time. Detectors at the output of the interferometer count photons from each output mode over a long integration time. We generalize and prove the claim of Tillmann et al. [Phys. Rev. X 5, 041015 (2015), 10.1103/PhysRevX.5.041015] that coincidence rates can be elegantly expressed in terms of immanants. Immanants are functions of matrices that exhibit permutational symmetries and the immanants appearing in our coincidence-rate expressions share permutational symmetries with the input state. Our results are obtained by employing representation theory of the symmetric group to analyze systems of an arbitrary number of photons in arbitrarily sized interferometers.
Calculation of the n-th coincidences frequency
International Nuclear Information System (INIS)
Mercier, C.
1959-01-01
Events can occur randomly with a given frequency. Each event lasts a Θ-time. During this Θ-time other events can occur. A coincidence beginning of order n at a t-time is when an event occurs while n other events already occurred between t-Θ and t. In this work the frequency of coincidence beginnings with an order greater than or equal to n is established
Neutronic and thermalhydraulic aspects
Energy Technology Data Exchange (ETDEWEB)
Thomas, J.B. [CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France). Dept. de Mecanique et de Technologie; Bergeonneau, P. [CEA Centre d`Etudes de Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. d`Etudes des Reacteurs
1995-12-31
Precise computation of neutron flux in the core of a nuclear reactor represents one of the basic aspects of reactor design and operation. Neutron flux is computed by solving Boltzmann`s linear equation. Anyway, the direct solution of the equation involves too great a number of operations for practical application, leading up to TeraFlops or even PetaFlops supercomputing capabilities. Physical and mathematical models are then required to handle the extensive variety of configurations encountered. Numerical methods must be adapted to the rapid evolution of computer power, as also computer architecture: sequential, vector or parallel. Physical and mathematical models must allow for very fast estimation for online control and monitoring, adequate quantification for industrial studies and high-precision, best estimate computations. Coupling of neutronics to mechanics and two-phase flow thermohydraulics must be implemented in order to improve the accuracy in best-estimate computation schemes and to take into account the transient behaviour of the plant during normal operation or incidents. In this field of continuous improvement, the new methods applied in Reactor Physics lead obviously to good results and provide the improvements required in the future for the needs of efficiency, safety and advanced fuel cycle. This trend and the ``evolutionary`` implementation in large and modular software systems will be illustrated by the example of the SAPHYR system. (authors). 3 tabs.
Neutronic and thermalhydraulic aspects
International Nuclear Information System (INIS)
Thomas, J.B.; Bergeonneau, P.
1995-01-01
Precise computation of neutron flux in the core of a nuclear reactor represents one of the basic aspects of reactor design and operation. Neutron flux is computed by solving Boltzmann's linear equation. Anyway, the direct solution of the equation involves too great a number of operations for practical application, leading up to TeraFlops or even PetaFlops supercomputing capabilities. Physical and mathematical models are then required to handle the extensive variety of configurations encountered. Numerical methods must be adapted to the rapid evolution of computer power, as also computer architecture: sequential, vector or parallel. Physical and mathematical models must allow for very fast estimation for online control and monitoring, adequate quantification for industrial studies and high-precision, best estimate computations. Coupling of neutronics to mechanics and two-phase flow thermohydraulics must be implemented in order to improve the accuracy in best-estimate computation schemes and to take into account the transient behaviour of the plant during normal operation or incidents. In this field of continuous improvement, the new methods applied in Reactor Physics lead obviously to good results and provide the improvements required in the future for the needs of efficiency, safety and advanced fuel cycle. This trend and the ''evolutionary'' implementation in large and modular software systems will be illustrated by the example of the SAPHYR system. (authors). 3 tabs
I. Fisk
2013-01-01
Computing activity had ramped down after the completion of the reprocessing of the 2012 data and parked data, but is increasing with new simulation samples for analysis and upgrade studies. Much of the Computing effort is currently involved in activities to improve the computing system in preparation for 2015. Operations Office Since the beginning of 2013, the Computing Operations team successfully re-processed the 2012 data in record time, not only by using opportunistic resources like the San Diego Supercomputer Center which was accessible, to re-process the primary datasets HTMHT and MultiJet in Run2012D much earlier than planned. The Heavy-Ion data-taking period was successfully concluded in February collecting almost 500 T. Figure 3: Number of events per month (data) In LS1, our emphasis is to increase efficiency and flexibility of the infrastructure and operation. Computing Operations is working on separating disk and tape at the Tier-1 sites and the full implementation of the xrootd federation ...
Stephan, Andrew C [Knoxville, TN; Jardret,; Vincent, D [Powell, TN
2011-04-05
A neutron detector has a volume of neutron moderating material and a plurality of individual neutron sensing elements dispersed at selected locations throughout the moderator, and particularly arranged so that some of the detecting elements are closer to the surface of the moderator assembly and others are more deeply embedded. The arrangement captures some thermalized neutrons that might otherwise be scattered away from a single, centrally located detector element. Different geometrical arrangements may be used while preserving its fundamental characteristics. Different types of neutron sensing elements may be used, which may operate on any of a number of physical principles to perform the function of sensing a neutron, either by a capture or a scattering reaction, and converting that reaction to a detectable signal. High detection efficiency, an ability to acquire spectral information, and directional sensitivity may be obtained.
Wu, Yican
2017-01-01
This book provides a systematic and comprehensive introduction to fusion neutronics, covering all key topics from the fundamental theories and methodologies, as well as a wide range of fusion system designs and experiments. It is the first-ever book focusing on the subject of fusion neutronics research. Compared with other nuclear devices such as fission reactors and accelerators, fusion systems are normally characterized by their complex geometry and nuclear physics, which entail new challenges for neutronics such as complicated modeling, deep penetration, low simulation efficiency, multi-physics coupling, etc. The book focuses on the neutronics characteristics of fusion systems and introduces a series of theories and methodologies that were developed to address the challenges of fusion neutronics, and which have since been widely applied all over the world. Further, it introduces readers to neutronics design’s unique principles and procedures, experimental methodologies and technologies for fusion systems...
International Nuclear Information System (INIS)
Poortmans, F.
1977-01-01
Experimental work in the field of low-energy neutron physics can be subdivided into two classes: 1)Study of the decay process of the compound-nucleus state as for example the study of the capture gamma rays and of the neutron induced fission process; 2)Study of the reaction mechanism, mainly by measuring the reaction cross-sections and resonance parameters. These neutron cross-sections and resonance parameters are also important data required for many technological applications especially for reactor development programmes. In general, the second class of experiments impose other requirements on the neutron spectrometer than the first class. In most cases, a better neutron energy resolution and a broader neutron energy range are required for the study of the reaction mechanism than for the study of various aspects of the decay process. (author)
International Nuclear Information System (INIS)
Mukhopadhyay, Himan; Dhurandhar, Sanjeev; Sago, Norichika; Tagoshi, Hideyuki; Takahashi, Hirotaka; Kanda, Nobuyuki
2006-01-01
We compare two strategies of multidetector detection of compact binary inspiral signals, namely, the coincidence and the coherent. For simplicity we consider here two identical detectors having the same power spectral density of noise, that of initial LIGO, located in the same place and having the same orientation. We consider the cases of independent noise as well as that of correlated noise. The coincident strategy involves separately making two candidate event lists, one for each detector, and from these choosing those pairs of events from the two lists which lie within a suitable parameter window, which then are called coincidence detections. The coherent strategy on the other hand involves combining the data phase coherently, so as to obtain a single network statistic which is then compared with a single threshold. Here we attempt to shed light on the question as to which strategy is better. We compare the performances of the two methods by plotting the receiver operating characteristics (ROC) for the two strategies. Several of the results are obtained analytically in order to gain insight. Further we perform numerical simulations in order to determine certain parameters in the analytic formulae and thus obtain the final complete results. We consider here several cases from the relatively simple to the astrophysically more relevant in order to establish our results. The bottom line is that the coherent strategy although more computationally expensive in general than the coincidence strategy, is superior to the coincidence strategy--considerably less false dismissal probability for the same false alarm probability in the viable false alarm regime
Neutronics activities for next generation devices
International Nuclear Information System (INIS)
Gohar, Y.
1985-01-01
Neutronic activities for the next generation devices are the subject of this paper. The main activities include TFCX and FPD blanket/shield studies, neutronic aspects of ETR/INTOR critical issues, and neutronics computational modules for the tokamak system code and tandem mirror reactor system code. Trade-off analyses, optimization studies, design problem investigations and computational models development for reactor parametric studies carried out for these activities are summarized
International Nuclear Information System (INIS)
Prillinger, G.; Konynenburg, R.A. van
1998-01-01
As a result of the popularity of the Agencies report 'Neutron Irradiation Embrittlement of Reactor Pressure Vessel Steels' of 1975, it was decided that another report on this broad subject would be of use. In this report, background and contemporary views on specially identified areas of the subject are considered as self-contained chapters, written by experts. In chapter 6, LWR-PV neutron transport calculations and dosimetry methods and how they are combined to evaluate the neutron exposure of the steel of pressure vessels are discussed. An effort to correlate neutron exposure parameters with damage is made
International Nuclear Information System (INIS)
Preszler, A.M.; Moon, S.; White, R.S.
1976-01-01
Additional calibrations of the University of California double-scatter neutron and additional analysis corrections lead to the slightly changed neutron fluxes reported here. The theoretical angular distributions of Merker (1975) are in general agreement with our experimental fluxes but do not give the peaks for vertical upward and downward moving neutrons. The theoretical neutron escape current J 2 /sub pi/ (Merker, 1972; Armstrong et al., 1973) is in agreement with the experimental values from 10 to 100 MeV. Our experimental fluxes agree with those of the Kanbach et al. (1974) in the overlap region from 70 to 100 MeV
Ignatovich, V K
2005-01-01
A new, algebraic, method is applied to calculation of neutron albedo from substance to check the claim that use of ultradispersive fuel and moderator of an active core can help to gain in size and mass of the reactor. In a model of isotropic distribution of incident and reflected neutrons it is shown that coherent scattering on separate grains in the case of thermal neutrons increases transport cross section negligibly, however it decreases albedo from a wall of finite thickness because of decrease of substance density. A visible increase of albedo takes place only for neutrons with wave length of the order of the size of a single grain.
I. Fisk
2010-01-01
Introduction It has been a very active quarter in Computing with interesting progress in all areas. The activity level at the computing facilities, driven by both organised processing from data operations and user analysis, has been steadily increasing. The large-scale production of simulated events that has been progressing throughout the fall is wrapping-up and reprocessing with pile-up will continue. A large reprocessing of all the proton-proton data has just been released and another will follow shortly. The number of analysis jobs by users each day, that was already hitting the computing model expectations at the time of ICHEP, is now 33% higher. We are expecting a busy holiday break to ensure samples are ready in time for the winter conferences. Heavy Ion An activity that is still in progress is computing for the heavy-ion program. The heavy-ion events are collected without zero suppression, so the event size is much large at roughly 11 MB per event of RAW. The central collisions are more complex and...
M. Kasemann P. McBride Edited by M-C. Sawley with contributions from: P. Kreuzer D. Bonacorsi S. Belforte F. Wuerthwein L. Bauerdick K. Lassila-Perini M-C. Sawley
Introduction More than seventy CMS collaborators attended the Computing and Offline Workshop in San Diego, California, April 20-24th to discuss the state of readiness of software and computing for collisions. Focus and priority were given to preparations for data taking and providing room for ample dialog between groups involved in Commissioning, Data Operations, Analysis and MC Production. Throughout the workshop, aspects of software, operating procedures and issues addressing all parts of the computing model were discussed. Plans for the CMS participation in STEP’09, the combined scale testing for all four experiments due in June 2009, were refined. The article in CMS Times by Frank Wuerthwein gave a good recap of the highly collaborative atmosphere of the workshop. Many thanks to UCSD and to the organizers for taking care of this workshop, which resulted in a long list of action items and was definitely a success. A considerable amount of effort and care is invested in the estimate of the comput...
Intermediate and fast neutron absorbed doses in fast neutron field at the RB reactor
International Nuclear Information System (INIS)
Sokcic-Kostic, M.; Pesic, M.; Antic, D.
1987-10-01
The experimental fuel channel EFC is created as one of the fast neutron fields at the RB reactor. The intermediate and fast neutron spectra in EFC are measured by activation technique. The intermediate and fast neutron absorbed doses are computed on the basis of these experimental results. At the end the obtained doses are compared. (author)
A coincidence-type ion-electron converter detector for low-energy protons
International Nuclear Information System (INIS)
Benka, O.; Weinzierl, P.; Dobrozemsky, R.; Stratowa, C.
1981-04-01
A coincidence type ion-electron converter detector has been developed and used - together with an electrostatic energy-analyser - for precision measurements of the energy distribution of recoil protons from free-neutron decay. The most important aspect of the development was, besides keeping the background below 0,2 counts/sec in the presence of a certain radiation background, to achieve a high and energy-independent counting probability for protons with energies between 100 and 1000 eV. With an acceleration voltage of about 25 kV and Al-foils (20 to 35 ug/cmsup2) as converter, we obtained counting efficiences of 70 to 85 percent. The design and performance of the detector system, employing six foils with different sensitive areas, are described and discussed in detail. (author)
Calculation of “LS-curves” for coincidence summing corrections in gamma ray spectrometry
Vidmar, Tim; Korun, Matjaž
2006-01-01
When coincidence summing correction factors for extended samples are calculated in gamma-ray spectrometry from full-energy-peak and total efficiencies, their variation over the sample volume needs to be considered. In other words, the correction factors cannot be computed as if the sample were a point source. A method developed by Blaauw and Gelsema takes the variation of the efficiencies over the sample volume into account. It introduces the so-called LS-curve in the calibration procedure and only requires the preparation of a single standard for each sample geometry. We propose to replace the standard preparation by calculation and we show that the LS-curves resulting from our method yield coincidence summing correction factors that are consistent with the LS values obtained from experimental data.
Neutron dosimetry; Dosimetria de neutrons
Energy Technology Data Exchange (ETDEWEB)
Fratin, Luciano
1993-12-31
A neutron irradiation facility was designed and built in order to establish a procedure for calibrating neutron monitors and dosemeters. A 185 GBq {sup 241} Am Be source of known is used as a reference source. The irradiation facility using this source in the air provides neutron dose rates between 9 nSv s{sup -1} and 0,5 {sup {mu}}Sv s{sup -1}. A calibrated 50 nSv s{sup -1} thermal neutron field is obtained by using a specially designed paraffin block in conjunction with the {sup 241} Am Be source. A Bonner multisphere spectrometer was calibrated, using a procedure based on three methods proposed by international standards. The unfold {sup 241} Am Be neutron spectrum was determined from the Bonner spheres data and resulted in a good agreement with expected values for fluence rate, dose rate and mean energy. A dosimetric system based on the electrochemical etching of CR-39 was developed for personal dosimetry. The dosemeter badge using a (n,{alpha}) converter, the etching chamber and high frequency power supply were designed and built specially for this project. The electrochemical etching (ECE) parameters used were: a 6N KOH solution, 59 deg C, 20 kV{sub pp} cm{sup -1}, 2,0 kHz, 3 hours of ECE for thermal and intermediate neutrons and 6 hours for fast neutrons. The calibration factors for thermal, intermediate and fast neutrons were determined for this personal dosemeter. The sensitivities determined for the developed dosimetric system were (1,46{+-} 0,09) 10{sup 4} tracks cm{sup -2} mSv{sup -1} for thermal neutrons, (9{+-}3) 10{sup 2} tracks cm{sup -2} mSV{sup -1} for intermediate neutrons and (26{+-}4) tracks cm{sup -2} mSv{sup -1} for fast neutrons. The lower and upper limits of detection were respectively 0,002 mSv and 0,6 mSv for thermal neutrons, 0,04 mSv and 8 mSv for intermediate neutrons and 1 mSv and 12 mSv for fast neutrons. In view of the 1990`s ICRP recommendations, it is possible to conclude that the personal dosemeter described in this work is
Neutron dosimetry; Dosimetria de neutrons
Energy Technology Data Exchange (ETDEWEB)
Fratin, Luciano
1994-12-31
A neutron irradiation facility was designed and built in order to establish a procedure for calibrating neutron monitors and dosemeters. A 185 GBq {sup 241} Am Be source of known is used as a reference source. The irradiation facility using this source in the air provides neutron dose rates between 9 nSv s{sup -1} and 0,5 {sup {mu}}Sv s{sup -1}. A calibrated 50 nSv s{sup -1} thermal neutron field is obtained by using a specially designed paraffin block in conjunction with the {sup 241} Am Be source. A Bonner multisphere spectrometer was calibrated, using a procedure based on three methods proposed by international standards. The unfold {sup 241} Am Be neutron spectrum was determined from the Bonner spheres data and resulted in a good agreement with expected values for fluence rate, dose rate and mean energy. A dosimetric system based on the electrochemical etching of CR-39 was developed for personal dosimetry. The dosemeter badge using a (n,{alpha}) converter, the etching chamber and high frequency power supply were designed and built specially for this project. The electrochemical etching (ECE) parameters used were: a 6N KOH solution, 59 deg C, 20 kV{sub pp} cm{sup -1}, 2,0 kHz, 3 hours of ECE for thermal and intermediate neutrons and 6 hours for fast neutrons. The calibration factors for thermal, intermediate and fast neutrons were determined for this personal dosemeter. The sensitivities determined for the developed dosimetric system were (1,46{+-} 0,09) 10{sup 4} tracks cm{sup -2} mSv{sup -1} for thermal neutrons, (9{+-}3) 10{sup 2} tracks cm{sup -2} mSV{sup -1} for intermediate neutrons and (26{+-}4) tracks cm{sup -2} mSv{sup -1} for fast neutrons. The lower and upper limits of detection were respectively 0,002 mSv and 0,6 mSv for thermal neutrons, 0,04 mSv and 8 mSv for intermediate neutrons and 1 mSv and 12 mSv for fast neutrons. In view of the 1990`s ICRP recommendations, it is possible to conclude that the personal dosemeter described in this work is
'TrueCoinc' software utility for calculation of the true coincidence correction
International Nuclear Information System (INIS)
Sudar, S.
2002-01-01
The true coincidence correction plays an important role in the overall accuracy of the γ ray spectrometry especially in the case of present-day high volume detectors. The calculation of true coincidence corrections needs detailed nuclear structure information. Recently these data are available in computerized form from the Nuclear Data Centers through the Internet or on a CD-ROM of the Table of Isotopes. The aim has been to develop software for this calculation, using available databases for the levels data. The user has to supply only the parameters of the detector to be used. The new computer program runs under the Windows 95/98 operating system. In the framework of the project a new formula was prepared for calculating the summing out correction and calculation of the intensity of alias lines (sum peaks). The file converter for reading the ENDSF-2 type files was completed. Reading and converting the original ENDSF was added to the program. A computer accessible database of the X rays energies and intensities was created. The X ray emissions were taken in account in the 'summing out' calculation. Calculation of the true coincidence 'summing in' correction was done. The output was arranged to show independently two types of corrections and to calculate the final correction as multiplication of the two. A minimal intensity threshold can be set to show the final list only for the strongest lines. The calculation takes into account all the transitions, independently of the threshold. The program calculates the intensity of X rays (K, L lines). The true coincidence corrections for X rays were calculated. The intensities of the alias γ lines were calculated. (author)
Performance of a tagged neutron inspection system (TNIS) based on portable sealed generators
International Nuclear Information System (INIS)
Nebbia, G.; Pesente, S.; Lunardon, M.; Viesti, G.; LeTourneur, P.; Heuveline, F.; Mangeard, M.; Tcheng, C.
2004-01-01
A portable sealed neutron generator has been modified to produce 14MeV tagged neutron beams with an embedded YAP:Ce scintillation detector. The system has been tested by detecting the coincident gamma-rays produced in the irradiation of a graphite sample by means of a standard NaI(Tl) scintillator. Time resolution of about δt=4-5ns (FWHM) has been measured. The sealed neutron tube has been operated up to 10 7 neutron/s. Possible applications in non-destructive assays and future developments of the Tagged Neutron Inspection System concept are discussed
P. McBride
It has been a very active year for the computing project with strong contributions from members of the global community. The project has focused on site preparation and Monte Carlo production. The operations group has begun processing data from P5 as part of the global data commissioning. Improvements in transfer rates and site availability have been seen as computing sites across the globe prepare for large scale production and analysis as part of CSA07. Preparations for the upcoming Computing Software and Analysis Challenge CSA07 are progressing. Ian Fisk and Neil Geddes have been appointed as coordinators for the challenge. CSA07 will include production tests of the Tier-0 production system, reprocessing at the Tier-1 sites and Monte Carlo production at the Tier-2 sites. At the same time there will be a large analysis exercise at the Tier-2 centres. Pre-production simulation of the Monte Carlo events for the challenge is beginning. Scale tests of the Tier-0 will begin in mid-July and the challenge it...
M. Kasemann
Introduction During the past six months, Computing participated in the STEP09 exercise, had a major involvement in the October exercise and has been working with CMS sites on improving open issues relevant for data taking. At the same time operations for MC production, real data reconstruction and re-reconstructions and data transfers at large scales were performed. STEP09 was successfully conducted in June as a joint exercise with ATLAS and the other experiments. It gave good indication about the readiness of the WLCG infrastructure with the two major LHC experiments stressing the reading, writing and processing of physics data. The October Exercise, in contrast, was conducted as an all-CMS exercise, where Physics, Computing and Offline worked on a common plan to exercise all steps to efficiently access and analyze data. As one of the major results, the CMS Tier-2s demonstrated to be fully capable for performing data analysis. In recent weeks, efforts were devoted to CMS Computing readiness. All th...
I. Fisk
2011-01-01
Introduction It has been a very active quarter in Computing with interesting progress in all areas. The activity level at the computing facilities, driven by both organised processing from data operations and user analysis, has been steadily increasing. The large-scale production of simulated events that has been progressing throughout the fall is wrapping-up and reprocessing with pile-up will continue. A large reprocessing of all the proton-proton data has just been released and another will follow shortly. The number of analysis jobs by users each day, that was already hitting the computing model expectations at the time of ICHEP, is now 33% higher. We are expecting a busy holiday break to ensure samples are ready in time for the winter conferences. Heavy Ion The Tier 0 infrastructure was able to repack and promptly reconstruct heavy-ion collision data. Two copies were made of the data at CERN using a large CASTOR disk pool, and the core physics sample was replicated ...
I. Fisk
2012-01-01
Introduction Computing continued with a high level of activity over the winter in preparation for conferences and the start of the 2012 run. 2012 brings new challenges with a new energy, more complex events, and the need to make the best use of the available time before the Long Shutdown. We expect to be resource constrained on all tiers of the computing system in 2012 and are working to ensure the high-priority goals of CMS are not impacted. Heavy ions After a successful 2011 heavy-ion run, the programme is moving to analysis. During the run, the CAF resources were well used for prompt analysis. Since then in 2012 on average 200 job slots have been used continuously at Vanderbilt for analysis workflows. Operations Office As of 2012, the Computing Project emphasis has moved from commissioning to operation of the various systems. This is reflected in the new organisation structure where the Facilities and Data Operations tasks have been merged into a common Operations Office, which now covers everything ...
M. Kasemann
CCRC’08 challenges and CSA08 During the February campaign of the Common Computing readiness challenges (CCRC’08), the CMS computing team had achieved very good results. The link between the detector site and the Tier0 was tested by gradually increasing the number of parallel transfer streams well beyond the target. Tests covered the global robustness at the Tier0, processing a massive number of very large files and with a high writing speed to tapes. Other tests covered the links between the different Tiers of the distributed infrastructure and the pre-staging and reprocessing capacity of the Tier1’s: response time, data transfer rate and success rate for Tape to Buffer staging of files kept exclusively on Tape were measured. In all cases, coordination with the sites was efficient and no serious problem was found. These successful preparations prepared the ground for the second phase of the CCRC’08 campaign, in May. The Computing Software and Analysis challen...
I. Fisk
2010-01-01
Introduction The first data taking period of November produced a first scientific paper, and this is a very satisfactory step for Computing. It also gave the invaluable opportunity to learn and debrief from this first, intense period, and make the necessary adaptations. The alarm procedures between different groups (DAQ, Physics, T0 processing, Alignment/calibration, T1 and T2 communications) have been reinforced. A major effort has also been invested into remodeling and optimizing operator tasks in all activities in Computing, in parallel with the recruitment of new Cat A operators. The teams are being completed and by mid year the new tasks will have been assigned. CRB (Computing Resource Board) The Board met twice since last CMS week. In December it reviewed the experience of the November data-taking period and could measure the positive improvements made for the site readiness. It also reviewed the policy under which Tier-2 are associated with Physics Groups. Such associations are decided twice per ye...
M. Kasemann
Introduction More than seventy CMS collaborators attended the Computing and Offline Workshop in San Diego, California, April 20-24th to discuss the state of readiness of software and computing for collisions. Focus and priority were given to preparations for data taking and providing room for ample dialog between groups involved in Commissioning, Data Operations, Analysis and MC Production. Throughout the workshop, aspects of software, operating procedures and issues addressing all parts of the computing model were discussed. Plans for the CMS participation in STEP’09, the combined scale testing for all four experiments due in June 2009, were refined. The article in CMS Times by Frank Wuerthwein gave a good recap of the highly collaborative atmosphere of the workshop. Many thanks to UCSD and to the organizers for taking care of this workshop, which resulted in a long list of action items and was definitely a success. A considerable amount of effort and care is invested in the estimate of the co...
International Nuclear Information System (INIS)
Okada, Yukiko
2005-01-01
Trends and progress in neutron activation analysis (NAA) for the period starting in 1999 to 2003 are presented. Numbers of published reports on NAA are decreasing year by year as investigated from the database JST and NUCLEN. Summary reports on the international conferences held on NAA are followed by classifying according to the fields: various measurement techniques and application fields. Specially focused topics are newly developed techniques for measuring trace elements with high sensitivity and high accuracy such as (1) by diminishing the Compton-background gamma-rays using anti-coincidence technique, (2) by using prompt-gamma rays measurement method (PGAA) and (3) by using a gamma-ray detector array (GEMINI), which has succeeded in a simultaneous quantification of 27 elements from a standard rock sample having a weight of only 10 milligrams, and others. These techniques will be applied in the space and earth sciences and medical fields. (S. Ohno)
Energy Technology Data Exchange (ETDEWEB)
Jacob, M [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires
1958-07-01
Study of the number of neutrons produced by fission of {sup 239}Pu. The counting by coincidence of fissions and neutrons produced by these fissions allows the study of the variation of the mean number of neutrons emitted by {nu} fission. In the first chapter, it studied the variation of the mean number of neutrons emitted by {sup 239}Pu fission with the energy of the incident neutron. A description of the experiment is given: a spectrometer with a crystal of sodium chloride or beryllium (mounted on a goniometer) is used, a fission chamber containing 10 mg of {sup 239}Pu and the neutron detection system constituted of BF{sub 3} counters which are enriched in {sup 10}B. In the second part, the counting by coincidence of fissions and neutrons produced by the same fission and received by two different groups of counters allow the determination of a relationship between the root mean square and the average of neutron number produced by fission. The variation of the mean number of neutrons emitted by fission of {sup 239}Pu is studied when we change from a thermal spectra of neutrons to a fission spectra of incident neutrons. Finally, when separating in two different part the fission chamber, it is possible to measure the mean number of neutrons emitted from fission of two different sources. It compared the mean number of neutrons emitted by fission of {sup 239}Pu and {sup 233}U. (M.P.)