The case of spontaneous radiation of channeled ultrarelativistic particles is considered when the dipolarity condition is not satisfied. The change of the particle longitudinal velocity affecting the maximum radiation frequency is included. The angular and frequency characteristics of the radiation for superhigh energies are studied for the first time. It is shown that there is an optimum energy at which the radiation density is maximum. The influence of the angle at which electrons enter a crystal and of the beam divergence on the radiation is investigated. The problem of quasichanneled particle radiation and also the radiation in axis-plane transitions are considered. (author).
By proposing the four-dimensional, reciprocity transformations the appropriate condition for superluminal electromagnetic Cerenkov radiation is obtained by introducing the hypothesis that tachyons possess vector energy and scalar momentum.
The biological age (BA) of the majority of the liquidators of the consequences of the radiation accidents in the Navy and of the liquidators of the Chernobyl' APS accident exceeds the medium standard and the DBA (due BA). The index of the BA can be a characteristic of the influence of the social-hygienic factors on the health condition of the Special Risk Subunit--the liquidators of the consequences of the radiation accidents. It was established, that the radiation influence concerns to the factors dramatically increasing the BA and the rate of senescence of the liquidators of the consequences of the radiation accidents. PMID:21809627
The decree refers to conditions of irradiation of food and its components for radappertization and radurization using gamma radiation from cobalt 60 or cesium 137, X radiation or electron beam up to maximum total medium absorbed dose 10 kGy.
In scattering of channeled particles by point defects and in emission of gamma rays in the spontaneous-radiation spectral region conditions are attained where the momentum transferred to the defect is taken up by the crystal as a whole. This leads to coherent and interference effects in the radiation from the crystal defects. When the longitudinal momentum transferred is zero, an induced radiation effect appears in the transitions between the states of transverse motion.
Turbulent premixed methane-air combustion in a cylindrical chamber is numerically simulated considering radiation effect. Reaction rates are considered as minimum rates between Arrhenius rates and eddy break up rates. A five step reduced mechanism is used. Turbulent modeling is done via standard k-{epsilon} model imposed by empirical inlet boundary conditions. Source terms of energy equation consist of reaction rates and radiation effects. The discrete ordinate method (DOM) is employed to solve the radiative transfer equation (RTE) and the weighted sum of gray gas model (WSGGM) is imposed to consider radiation effect of non-gray gases. The results indicate that in the case of turbulent combusting flows, the effect of radiation of gases can affect the temperature and species concentrations. The numerical results obtained considering radiation ...
Turbulent premixed methane-air combustion in a cylindrical chamber is numerically simulated considering radiation effect. Reaction rates are considered as minimum rates between Arrhenius rates and eddy break up rates. A five step reduced mechanism is used. Turbulent modeling is done via standard k-? model imposed by empirical inlet boundary conditions. Source terms of energy equation consist of reaction rates and radiation effects. The discrete ordinate method (DOM) is employed to solve the radiative transfer equation (RTE) and the weighted sum of gray gas model (WSGGM) is imposed to consider radiation effect of non-gray gases. The results indicate that in the case of turbulent combusting flows, the effect of radiation of gases can affect the temperature and species concentrations. The numerical results obtained considering radiation effect ...
A circumsolar telescope for determining the flux of energy from the sun and from the circumsolar region as a function of angle, wavelength, and atmospheric conditions is presented. The telescope system consists of a specially designed scanning telescope, an electronic control and recording system and some auxiliary equipment. The detector is a pyroelectric crystal, a type of thermal detector, thus the fundamental measurement is relatively wavelength insensitive. The telescope is designed to provide data for all weather conditions during which a concentrating solar energy system would be operating. Analyses show that for a clear blue sky, the amount of radiation coming directly from the sun, while for a sky with thin clouds or haze, the circumsolar radiation is some 25% of the direct solar radiation. Under such conditions a measure of the circumsolar ...
Regularities in the radiation cross-linking of low-density polyethylene under various conditions of ..gamma..-irradiation were studied. It is shown that at the 0.5 GPa pressure and 450 K the gel formation is initiated at doses of about 1 kGy, i.e. at doses 10 times as low as compared to normal conditions. Abnormally high rate of radiation cross-linking at high temperature and high pressure is an evidence of changes in the mechanism of polyethylene, radiation cross-linking, i.e. of the process transition from nonchain to chain conditions. Decrease in the potential barriers of macroradical reactions with macromolecules is the most probable reason of change in the polymer cross-linking nature.
Hard Nano-Strutural Coatings Resistant to the Extreme Conditions of Chemical, Abrasive and High Energy Media for Thermonuclear Power, Oil and Gas and Chemical Industries
Standard radiation monitoring has been conducted at Sendai nuclear power station for the purpose of estimation of 'source activity' during refueling outage and evaluation of countermeasures to reduce dose rate. Selected objects of the monitoring are radiation dose rate at maintenance area, radiation field at each equipment and piping, coolant chemistry and plant operation condition. Monitored data indicates that 'source activity' variation can be estimated to some extent using influential factors, and that evaluation of change of loose crud activity, which is presumed to be represented by the dose rate at letdown heat exchanger, is necessary to further explain change in radiation field at main work area. (author).
The optically stimulated luminescent (OSL) radiation dosimeter technically surveys a wide dynamic measurement range and a high sensitivity. Optical fiber dosimeters provide capability for remote monitoring of the radiation in the locations which are difficult-to-access and hazardous. In addition, optical fiber dosimeters are immune to electrical and radio-frequency interference. In this paper, a novel remote optical fiber radiation dosimeter is described. The optical fiber dosimeter takes advantage of the charge trapping materials CaS:Ce, Sm that exhibit OSL. The measuring range of the dosimeter is from 0.1 to 100 Gy. The equipment is relatively simple and small in size, and has low power consumption. This device is suitable for measuring the space radiation dose and also can be used in high radiation dose condition and other dangerous ...
Water vapor is well known to be a critical component in many aspects of atmospheric research, such as radiative transfer and cloud and aerosol processes. This requires both improved measurements of the columnar water vapor and its profiles in the atmosphere in a wide range of conditions, and adjustment of water vapor parameterizations in radiation codes including the perfection of spectroscopic parameters. In this paper we will present the results of comparison of our calculations and downward solar fluxes measured with Rotating Shadowband Spectroradiometer under conditions of horizontally homogeneous clouds. We also will discuss the sensitivity of atmospheric radiation characteristics to variations of water vapor in the band 940 nm: these results may be useful for development of new methods of retrieval of the total column water vapor content (WVC) in the atmosphere from data of ...
Total dose irradiation effects on a VDMOS developed at Institute of Microelectronics, CAS were investigated, particularly the electric parameter changes under different bias conditions. It was found that the breakdown voltage degradation by the irradiation depended mainly on the drain bias, whereas the threshold voltage degradation depended mainly on the gate bias. Thus, an innovative and effective method to domestic VDMOS total dose ionization characterization is that threshold voltage radiation hardening characterization should be tested on gate bias condition, and the breakdown voltage radiation hardening characterization, be tested on the drain bias. (authors)
Feasibility of using sterile females for population suppression of Earias vittella (Fabricius) was evaluated by conducting studies on mating competitiveness of radiation sterilized females, both in individual pairs and in simulated large population conditions. Results showed that sterility induced by using a 10:1:1 ratio (sterile female: normal female: normal male) in single pair experiments and also in simulated large population conditions was more than 99.0 per cent. Release of radiation- sterilized females of E. vittella in natural populations has thus an excellent potential for population suppression. (author)
The gravitational radiation produced by the big bang is calculated in order to provide a condition for the unification of the gravitational and electromagnetic forces. By analogy with electromagnetic radiation and under the assumption that gravity is also quantized, it is shown that matter would have decoupled from gravitational radiation at a time of approximately 10 to the -43rd sec and would have dominated it at 10 to the -17th sec. Furthermore, the theory predicts a background gravitational radiation temperature of 0.003 K which peaks at a wavelength of about 1 m, which may be detected by the comparison of the synchronization of clocks at increasing distances.
The somatic and genetic radiation exposure of patients undergoing Digital Subtraction Angiography (DSA) and traditional Film Arteriography (FA) of cranial, cervical, thoracic and abdominal vascular territories are compared. The radiation doses absorbed within the critical organs - red bone marrow, lung, thyroid gland and female breast - and in the gonads were measured using an anthropomorphic Alderson phantom. A Somatic Dose Index was calculated in order to estimate the somatic radiation risk. The somatic radiation exposure depends upon the location of the critical organs with respect to the entrance site of the x-ray beam, and can be reduced by an appropriate choice of the angiographic projection. Under this condition, the radiation exposure of the patient during DSA can be lower than during FA. For renal DSA an a.p. projection, the use of an abdominal ...
A 38 year old male dentist developed an oligodendroglioma of the left medial temporal lobe and parasellar region 12 years after radiotherapy with 6600 rads for acromegaly. The 30 cases of radiation-induced gliomas reported in the English literature are reviewed and analysed. The criteria for defining radiation-induced tumours of the central nervous system are proposed as follows: the tumour has a long quiescent ''latency period'', a location in the previously irradiated field, a verified histological difference from a primary condition, and does not arise from a primary condition associated with a genetic syndrome such as neurofibromatosis or tuberous sclerosis. The reported case fulfilled these criteria but appears to be the only reported radiation-induced oligodendroglioma.
We present experimental studies on the photoionization and photodissociation processes (photodestruction) of gaseous amino acids and nucleobases in interstellar and interplanetary radiationconditions analogs. The measurements have been undertaken at the Brazilian Synchrotron Light Laboratory (LNLS), employing vacuum ultraviolet (VUV) and soft X-ray photons. The experimental set up basically consists of a time-of-flight mass spectrometer kept under high vacuum conditions. Mass spectra were obtained using photoelectron photoion coincidence technique. We have shown that the amino acids are effectively more destroyed (up to 70-80%) by the stellar radiation than the nucleobases, mainly in the VUV. Since polycyclic aromatic hydrocarbons have the same survival capability and seem to be ubiquitous in the ISM, it is not unreasonable to predict that nucleobases could survive in the interstellar medium and/or in ...
The effect of adriamycin in combination with radiation on the skin reactions of mouse feet has been examined under a variety of experimental conditions including: (a) hyperthermic treatment of the foot immediately following adriamycin administration, with the former given either just before or just after x irradiation, and (b) fractionated treatments of drug and radiation in a variety of sequences over an 18-day period. In the case of the most severe hyperthermic treatment, no increased radiation reactions were observed in the presence of adriamycin. However, in the case of the less severe hyperthermic treatment a small but significant increase in skin reactions was observed. In the study of fractionated drug and radiation treatments, an enhancement of reaction in those animals receiving combined modality treatment over those receiving radiation alone was seen ...
Optimization of radiation shielding for a medium energy accelerator with 60 MeV alpha ions is carried out using the cost-benefit approach. Cost optimum shield thicknesses are estimated for different operating conditions of the accelerator. (author). 5 refs, 1 tab.
Radiation-and-thermal-combined degradation of some kinds of cable insulating and jacketing materials was evaluated by accelerated aging tests. Plasticized polyvinyl chloride (PVC), silicone rubber, crosslinked and non-crosslinked halogen-free flame-retardant polyolefins (NH-XLPO and NH-PO) and ethylene-propylene rubber (EP rubber) of experimental formulation were degraded at accelerated rates, that are 50-1000 times the degradation rate under standard conditions (e.g.; 1Gy/h, 50degC), and a method to assess the lifetime of these materials under standard conditions was studied. The degradation was investigated by measuring tensile properties. In the accelerated aging tests, rates of elongation decrease owing to degradation for these materials were in proportion to the increase in accelerated rate. The PVC lifetime estimated from sequential aging tests had a tendency to extend beyond that from simultaneous aging tests, while ...
Various nylons including nylon 6, nylon 66, nylon 610 and nylon 12 in the forms of fiber and film were irradiated with the gamma-ray from Co-60 at the dose rate of 0.12 Mrad/hr in the atmosphere of oxygen at 7 kg/cm/sup 2/ and at the room temperature. The irradiation in vacuum on the same specimens was performed at 0.5 Mrad/hr. The tensile properties and the gel fraction of the irradiated nylon samples were measured, and the radiation resistance of the nylons against the irradiation at low dose rate was estimated. From the experimental results, it became clear that in the case of irradiation in vacuum, all the nylons were durable to the irradiation of 250 Mrad or more, and nylon 6 was more durable than nylon 12, and in the case of irradiation in pressurized oxygen, the radiation resistance of the nylons decreased to one-tenth as compared with that in vacuum, and contrary to that in vacuum, nylon 12 was superior to nylon 6, while nylon 610 was ...
The characteristic space-time scales of surface solar radiation fields measured by the 111-instrument ME-SONET in Oklahoma are estimated after removal of the diurnal cycle. These estimates of {open_quotes}within-day{close_quotes} are used to deduce the representativeness of surface solar radiation measurements measurement site as a function of time-averaging interval. Nomograms of the relation between point measurements and area averages are given for different space-time-averaging intervals. Examples from the nomograms show, for instance, that under conditions of low mean radiation (cloudy days), the central site point measurements are representative of a spatial area the size of a T42 GCM grid box (280 km X 280 km) if one uses hourly averages and is willing to accept a correlation of 0.45 between area average and point measurement. The point data represent a 60 km X 60 km region at a 0.90 correlation ...
Prior to routine use, all newly installed x-ray machines must have a radiation-protection survey by a qualified expert. The survey is an evaluation of existing or potential radiation hazards associated with the use of diagnostic x-ray equipment under specific conditions. Such evaluation includes the measurement of exposure levels in the environment as well as environmental levels arising from operation of the equipment. The survey also includes an evaluation of the safety characteristics of the x-ray unit.
The inelastic scattering of the beam and the residual gas molecules in RHIC could represent one of the limitations on the beam life time and emittance growth. This report covers the dominant central nuclear collisions influence on the beam lifetime and transverse emittance growth. The cross sections for the beam-gas electron radiative captures are an order of magnitude smaller. The capture cross sections include the radiative and non-radiative capture, and the capture from the electron-positron pair creation from the 'vacuum capture'.
Exposure of teachers of physics to X-radiation emitted by instruments which are used for demonstrating rarefied gas discharges during physics lessons at secondary schools is discussed. The measurements performed provide an explicit evidence that an effective, annual exposure dose under the most unfavorable conditions does not exceed admissible levels according to Polish regulations pertaining to persons non-occupationally exposed to ionizing radiation. (author). 3 refs,1 fig.
Within the framework of homogeneous models of the Universe, inflation provides the simplest explanation for the present cosmic isotropy, and a Bianchi type-IX (mixmaster) model is the least prejudiced guess we can make about the state of the Universe before the inflationary phase. However, a mixmaster model would not inflate unless either shear or the radiation energy density are large enough. Particle creation enhances the radiation energy density and therefore enlarges the set of inflating initial conditions for the Universe.
Asynchronous Chinese hamster ovary (CHO) cells treated with conditioning hyperthermia (10 min at 45/sup 0/C) followed immediately by x irradiation with 4 Gy at room temperature display a decreased radiation response when either irradiated, or heated and irradiated again 24 h later. In addition, conditioning by 4 Gy of x radiation alone followed at 24 h by the combined heat and radiation treatment als resulted in a larger radiation D/sub 0/. Since the differential cell-cycle responses to heat- and x-ray-induced lethality are well established for CHO cells, the potential role of cell-cycle redistribution in the observed radiation desensitization was investigated by flow cytometry. At 24 h after the combined treatment, the fraction of the cells found in the G/sub 2/ + M portion of the DNA histograms was about three times that of the controls ...
Many assays for oncogenic transformation have been developed ranging from those in established rodent cell lines where morphological alteration is scored, to those in human cells growing in nude mice where tumor invasiveness is scored. In general, systems that are most quantitaive are also the least relevant in terms of human carcinogenesis and human risk estimation. The development of cell culture systems has made it possible to assess at the cellular level the oncogenic potential of a variety of chemical, physical and viral agents. Cell culture systems afford the opportunity to identify factors and conditions that may prevent or enhance cellular transformation by radiation and chemicals. Permissive and protective factors in radiation-induced transformation include thyroid hormone and the tumor promoter TPA that increase the transformation incidence for a given dose of radiation, and retinoids, ...
Many assays for oncogenic transformation have been developed ranging from those in established rodent cell lines where morphological alteration is scored, to those in human cells growing in nude mice where tumor invasiveness is scored. In general, systems that are most quantitaive are also the least relevant in terms of human carcinogenesis and human risk estimation. The development of cell culture systems has made it possible to assess at the cellular level the oncogenic potential of a variety of chemical, physical and viral agents. Cell culture systems afford the opportunity to identify factors and conditions that may prevent or enhance cellular transformation by radiation and chemicals. Permissive and protective factors in radiation-induced transformation include thyroid hormone and the tumor promoter TPA that increase the transformation incidence for a given dose of radiation, and retinoids, ...
The optically stimulated luminescent (OSL) radiation dosimeter technically surveys a wide dynamic measurement range and a high sensitivity. Optical fiber dosimeters provide capability for remote monitoring of the radiation in the locations which are difficult-to-access and hazardous. In addition, optical fiber dosimeters are immune to electrical and radio-frequency interference. In this paper, a novel remote optical fiber radiation dosimeter is described. The optical fiber dosimeter takes advantage of the charge trapping materials CaS:Ce, Sm that exhibit OSL. The measuring range of the dosimeter is from 0.1 to 100 Gy. The equipment is relatively simple and small in size, and has low power consumption. This device is suitable for measuring the space radiation dose and also can be used in high radiation dose condition and other dangerous ...
Evaluations were done to determine conditions that could permit nuclear criticality with fissile uranium in low-level waste (LLW) facilities and to estimate potential radiation exposures to personnel if there were such an accident. Simultaneous hydrogeochemical and nuclear criticality studies were done (1) to identity realistic scenarios for uranium migration and concentration increase at LLW disposal facilities, (2) to model groundwater transport of uranium and subsequent concentration via sorption or precipitation, (3) to evaluate the potential for nuclear criticality resulting from potential increases in uranium concentration over disposal limits, and (4) to estimate potential radiation exposures to personnel resulting from criticality consequences. This paper presents the details of the radiation exposure calculations relying on the conditions as determined from the preceding ...
The determination of the oxidation state of ultra-trace elements in the environment, especially in the case of actinides, is of importance in many ways. Speciation techniques using radiation may comprise methods based on the detection of the nuclear and atomic radiations emitted in radioactive decay or methods using external sources of excitation. In the former instance, information can be obtained from the energy and intensity of radiation, but at present the partition method is still the most commonly used, although its reliability is questionable. Excitation with intense laser beams, as is currently being used for trace element analysis in photoacoustic and thermal lensing spectroscopic techniques, could conceivably be applied under suitable conditions to ultra-trace elements with a sensitivity approaching that of the radiochemical methods.
The scattering of atoms by a resonance standing light wave is considered under conditions when the lower of two resonance levels is metastable, while the upper level rapidly decays due to mainly spontaneous radiative transitions to the nonresonance levels of an atom. The diffraction scattering regime is studied, when the Rabi frequency is sufficiently high and many diffraction maxima are formed due to scattering. The dynamics of spontaneous radiation of an atom is investigated. It is shown that scattering slows down substantially the radiative decay of the atom. The regions and characteristics of the power and exponential decay are determined. The adiabatic and nonadiabatic scattering regimes are studied. It is shown that the wave packets of atoms in the metastable and resonance excited states narrow down during scattering. A limiting (minimal) size of the wave packets is found, which is achieved upon ...
Inputs on radiological conditions forms the basis of implementation of effective exposure control to plant personnel in nuclear power station. Radiation monitoring system provides this input to the plant operator as well as to health physics group. Several design modifications have been incorporated in the Radiation Monitoring System at Tarapur Atomic Power Station (TAPS 3 and 4) over the similar systems at Kakrapar Atomic Power Station (KAPS) and Kaiga Generating Station (KGS). The radiological monitoring systems installed at TAPS unit 3 and 4 includes on line Radiation Data Acquisition System (RADAS), Emergency sampling system, effluent monitoring system and environmental monitoring system. The design changes and the versatile use of these systems are presented in this paper. (author)
Recently, foods are often exposed to radiation under packed states with various wrapping materials. In this study, the effects of #gamma#-ray radiation were investigated on the additives in wrapping materials on the market. 10 - 50 kGy #gamma# radiation was irradiated to samples under sealed condition in a glass-ware. Polyethylene bag and wrapping film, polypropylene wrapping film, cup and sheet, and polystyrene cup were used as samples. And the additives in these materials were analyzed by GC/MS to evaluate the radiation effects on them. The irradiation was found to induce rapid degradation of antioxidants, especially, Irgafos 168. Some fatty acid amides used as a lubricant and a plasticizer, DBP were also reduced, but not aliphatic hydrocarbons. However, all polystyrene products used in this study included no additives. The contents of styrene dimer and trimer in those wrapping ...
The unsteady state heat transfer behaviour of a vertical wall subject to the effects of uniform radiation is investigated and the dimensional analysis of combined heat transfers by conduction, convection and radiation is presented. The convective heat transfer coefficients used in the numerical model are determined experimentally by means of an assembly resembling the conditions encountered in the dwelling (variable temperatures and heat flows in time and space, wall associated with a floor, radiative flux outside the wall). In routine conditions (homogeneous wall dimensions, temperature differentials less than 40/sup 0/C), it is shown that the problem depends in practice on three parameters (instead of five) and that nomographs can give the energy accumulated in the wall as a function of its geometric and thermal charactersitics and the external conditions ...
Based on the practical condition of the plant and in reference to advanced management experiences worldwide, Daya Bay Nuclear Power Plant has established its own peculiar management system for radiation protection management and ALARA implementation. The characteristics of the system are: radiation protection training to all workers, active involvement of all managers and staffs, and whole process safety control to maintenance activities. The management philosophy of 'workers are responsible for their own radiation safety' is adopted in the plant. A strict, formalized and systematic whole staff radiation protection training, evaluation, authorization and periodically refreshing mechanism had been established and executed in the plant. In the organizational point of view, the responsibilities of line managers were specified in plant procedures, ALARA coordination organization on ...
Ionizing radiation, mainly in the form of #gamma#-rays from the radioisotope cobalt 60, is being used increasingly for the inactivation of contaminants in cosmetic and toiletry preparations. The treatment is applied to the product in its final pack, and therefore, it is important to recognize that the properties of the packaging materials could be affected, particularly if high radiation doses are used. The stability of a wide range of materials is discussed. The nature and extent of chemical and physical changes in plastics very much depends on the presence of antioxidants and other additives, and on the environmental conditions during irradiation. Some useful information is available from research into the use of radiation for the preservation of food - many films and laminates have been cleared for use in the United States. The low radiation doses used for the control of ...
Alanine/EPR Dosimetry system is classified as a reference-standard dosimeter which used to calibrate radiation environments and to calibrate routine dosimeters in absorbed dose range of 1 to 105 Gy. Characteristics of Alanine/EPR dosimetry system are better suitable than routinely used personnel dosimeters for the long term radiation measurement in harsh condition of Nuclear power plant : This system is not significantly affected by temperature and humidity and also has low fading rate. About 1 year ago, Alanine and Lithium compound dosimeters were installed at Wolsung unit 1 for the environment monitoring as a part of equipment qualification program. 35 positions which are most severe and representative cable positions were chosen for radiation and temperature monitoring. The recovered alanine dosimeter in the period of maintenance was measured by E-scan alanine analyzer system, Meanwhile measurement ...
Alanine/EPR Dosimetry system is classified as a reference-standard dosimeter which used to calibrate radiation environments and to calibrate routine dosimeters in absorbed dose range of 1 to 105 Gy. Characteristics of Alanine/EPR dosimetry system are better suitable than routinely used personnel dosimeters for the long term radiation measurement in harsh condition of Nuclear power plant : This system is not significantly affected by temperature and humidity and also has low fading rate. About 1 year ago, Alanine and Lithium compound dosimeters were installed at Wolsung unit 1 for the environment monitoring as a part of equipment qualification program. 35 positions which are most severe and representative cable positions were chosen for radiation and temperature monitoring. The recovered alanine dosimeter in the period of maintenance was measured by E-scan alanine analyzer system, Meanwhile measurement ...
In order to follow some of the changes induced by ultraviolet-B (UV-B, 280-320 nm) radiation in Phaseolus vulgaris and Brassica napus, experiments were designed to localize sites of changes in leaves and to correlate some of the physiological and biochemical changes with penetration of UV-B radiation. B.napus was exposed to 8.9 kJ m"-"2 day"-"1 biologically effective UV-B radiation (UV-B_B_E). The penetration of UV-B radiation into the leaf was followed using a quartz fibre optic microprobe. Monochromatic radiation at 310 nm was decreased by ca 50 and 34% in the adaxial and abaxial epidermis, respectively, in plants not exposed to UV-B, whereas the radiation was decreased by ca 70 and 42%, respectively, in the same region in UV-treated plants. Polychromatic radiation showed a wavelength dependent change mainly for the collimated ...
Ramsar, a city in the northern Iran, has the highest level of natural background radiation in the world. It has been clearly shown that low doses of ionising radiation can induce resistance to subsequent higher exposures. This phenomenon is termed radioadaptive response. We have compared induction of cytogenetic radioadaptive response by High Natural Background Radiation (HNBR) in Ramsar and X-ray occupational exposure as conditioning doses in human peripheral blood lymphocytes. 30 healthy control individuals, living in Ramsar but in normal background radiation areas, 15 healthy individuals from Talesh Mahalleh, a region with extraordinary high level of background radiation, and 7 X-ray radiographers working in Ramsar hospital located in normal natural background ionising radiation area were evaluated. Peripheral blood samples were prepared ...
Conditions for radiation induced grafting with butyl acrylate dispersed in water emulsion onto chrome-tanned pig skins have been worked out for #gamma#-rays and electron beam irradiations. The highest yield of grafting was observed at monomer concentration approximately 25% (w/w), dose equal to 25 kGy and dose rate not exceeding 10 MGy/h. At these conditions the yield of grafting attained a value approximately 25% and content of homopolymer in the leather amounted to 6%. The efficiency of monomer to polymer conversion decreases when the concentration of monomer in emulsion and dose rate increases. Yield of homopolymer is independent of the dose rate. An explanation of the observed relations has been proposed. The physical and used properties of grafted leathers were tested. Radiation processed leathers were found superior to samples finished by traditional methods. One has to point to better tolerance ...
The author describes the history of the Soviet Unions nuclear weapons testing in Siberia from the first bomb on 29th August 1949 until the test-ban treaty of 1963. The effects of the weapons testing on the local population is only now becoming widely known. Levels of cancers and cataracts are significantly higher than in uneffected populations, and there are also high levels of some lung, bone, skin and digestive conditions. Perhaps the most important information relates to cataracts, previously thought to be caused by single large bursts of radiation. Regulatory authorities worldwide will need to tighten the safety limits for eye radiation exposure to these findings. (U.K.).
The author describes the history of the Soviet Unions nuclear weapons testing in Siberia from the first bomb on 29th August 1949 until the test-ban treaty of 1963. The effects of the weapons testing on the local population is only now becoming widely known. Levels of cancers and cataracts are significantly higher than in uneffected populations, and there are also high levels of some lung, bone, skin and digestive conditions. Perhaps the most important information relates to cataracts, previously thought to be caused by single large bursts of radiation. Regulatory authorities worldwide will need to tighten the safety limits for eye radiation exposure to these findings. (U.K.).
In situ optical absorption spectroscopy was used to study the generation of E' centres in amorphous SiO_2 occurring by photo-induced breaking of Si-H groups under 4.7eV pulsed laser radiation. The dependence from laser intensity of the defect generation rate is consistent with a two-photon mechanism for Si-H rupture, while the growth and the saturation of the defects are conditioned by their concurrent annealing due to reaction with mobile hydrogen arising from the same precursor. A rate equation is proposed to model the kinetics of the defects and tested on experimental data.
The long-term survival of certain patients after treatment with radiation or chemotherapeutic agents has allowed the realization that agents that effectively control cancer in the human subject may also possess an oncogenic potential, resulting in secondary malignancies in a significant proportion of surviving patients. A quantitative assessment of the oncogenic effects of these agents at a cellular level is important, as is information on conditions and agents that may effectively alter the development of the neoplastic state. Cell culture systems where the neoplastic transformation of cells can be scored after exposure to carcinogens offer powerful tools for evaluating the oncogenic potential of radiation and chemotherapeutic agents.
Two species of wood, viz. Haldu (Adina Cordifolia) and Jamun (Syzygium Cumini) were vacuum-impregnated with two styrene-based monomer systems and polymerized in situ with gamma radiation from a cobalt-60 source. The electrical conductivity of these specimens was determined at various polymer loadings under dry conditions, after wetting and after wet recovery as per ASTM standards. The water absorption characteristics are also presented. The results are discussed with special reference to the role of water. Potential applications are also discussed. 7 figures.
The radiation degradation behavior of three commercial polyvinyl chloride (PVC) materials has been investigated. All three exhibit an interesting reversal in the trend of the tensile strength part way through the aging experiment: the tensile strength first drops, then rises. The early drop is associated with oxidative scission; the rise is associated with crosslinking and is preceded by the material reaching the gel point. It was also found that the tensile elongation tended to level out in advanced stages of aging with the levelling-out values dependent on the dose rate. These phenomena pose complications for the design of accelerated aging tests. (author).
The radiation degradation behavior of three commercial polyvinyl chloride (PVC) materials has been investigated. All three exhibit an interesting reversal in the trend of the tensile strength part way through the aging experiment: the tensile strength first drops, then rises. The early drop is associated with oxidative scission; the rise is associated with crosslinking and is preceded by the material reaching the gel point. It was also found that the tensile elongation tended to level out in advanced stages of aging with the leveling-out values dependent on the dose rate. These phenomena pose complications for the design of accelerated aging tests.
The radiation dose and the atmospheric dispersion for Pressurized Heavy Water Reactors (PHWR) are based on the CAN/CSA N288.2-M91 standards: for Pressurized Water Reactor (PWR) on the NRC Regulatory Guide 1.145. There are some differences between in the methodologies used in the standards, including the atmospheric dispersion model, the release height, the temperature lapse rate, the cutoff condition. This paper reports on a comparison of standards for atmospheric dispersion models of PHWRs and PWRs in order to determine which one is the more conservative. The comparison between PHWR and PWR for atmospheric dispersion factors and radiation doses confirms that there are no big differences
Retention kinetics and tissue partition coefficients for "8"5Kr were determined in rats exposed to known concentrations of "8"5Kr gas. The tissue partition coefficients were used to calculate the relative tissue radiation dose, assuming exposure conditions equivalent to the maximum permissible concentration in air (MPC)a. The estimated radiation dose was highest in adrenals and body fat, about twice the dose estimated for the next highest tissue, ovaries. Saturation and desaturation curves show that the contents of the large intestines have a prolonged desaturation time compared to other samples analyzed.
Up to this time the sigmoid colostomy has been widely accepted and conventional treatment for radiation-injured rectum, but patients without residual malignancy strongly desire to live without colostomy. We have tried to remove the involved rectal segments by sphincter-saving procedures. Four patients underwent these procedures, pull-through procedure in three and low anterior resection in one. Among sphincter-saving procedures, pull-through procedure was most adequate. Provided the following five conditions are fulfilled, pull-through procedure should be considered for severe radiation-injured rectum. (1) No recurrence of initial malignancy in the pelvis. (2) More than 2 cm intact rectal segment above dentate line may be preserved. (3) No radiation-injured segment in upper sigmoid. (4) No severe radiation damage in small intestine. (5) Patients under 70 year-old, with normal tonus ...
The main problems arising in decommissioning nuclear-powered submarines (NPS) relate to choosing a concept of handling reactor compartments followed by handling technology development. Reactor compartments (RC) are characterized with extremely space-saving or integral layout of large-size power equipment and systems, restricted access for dismantling, high radiation dose rates in a number of bays of RC. The above RC features pose a problem to find optimum option of RC utilization which on the one hand would be the most cost efficient, and the safest as possible on the other, i.e. dose commitments of personnel involved should be minimum, and effect on population and environment should be negligible. The main radiation factors specifying safety in RC handling at any decommissioning stage are as follows: (1) total radioactivity integrated in reactor facility (RF); (2) distribution of this radioactivity through RF equipment and structures; (3) ...
The application of robotics for repair, refurbishing or dismantling of nuclear installations implies eventually severe radiation resistance requirements on embarked components and subsystems. This is particularly critical when optical sensing is considered. Optoelectronic components and optical fibers are indeed quite sensitive to radiation, and without special design are rapidly out-of-operation in such an environment. This paper reports the results of a series of #gamma# irradiation experiments on such devices, and identify their behavior under radiation. Test results show that carefully selected optical fibers can keep their radiation induced attenuation lower than 0.3 dB/m even up to a total dose of 10 MGy. Temperature annealing can even lower this attenuation down to 0.1 dB/m. On the other hand, commercially available light emitting diodes and photodiodes present attenuations figures up to 15 dB, ...
Oncospheres produced by a nonirradiated worm and oncospheres produced by a worm that had been subjected to high gamma radiation (successive generations of cysticercoids were irradiated with 15,000 r until a cumulative dose of 120,000 r was obtained) were compared. Radiation had no effect on the sizes of the embryos, the shell, and the median hooks. Radiation may have resulted in certain large, hookless embryos that did not occur in the normal worm. Two anomalies, reduced hook number and failure of growth, were more frequent in the normal than in the irradiated worm. This result, although surprising, can be explained by the high selection pressure operating under the experimental conditions. (auth)
Based on a collisional-radiative model, an atomic-kinetic calculation of the gains on the 41.8-nm transitions of Pd-like xenon was performed for the plasma produced due to the interaction of a femtosecond laser pulse with gaseous xenon. The gains g(z,{tau}) averaged over the spatial and temporal coordinates were compared with the known gains which had been measured experimentally in Xe{sup 8+}. The amplification was shown to occur under the conditions of ionisation of the working ions, and the time of output radiation saturation depends on the time of Xe{sup 8+} transformation to higher-ionised ions. Our theoretical investigation enables determining the optimal pump parameters, at which the product of the gain g by the active medium length L is about 20, which exceeds the experimental gL value. (active media)
Based on a collisional-radiative model, an atomic-kinetic calculation of the gains on the 41.8-nm transitions of Pd-like xenon was performed for the plasma produced due to the interaction of a femtosecond laser pulse with gaseous xenon. The gains g(z,?) averaged over the spatial and temporal coordinates were compared with the known gains which had been measured experimentally in Xe8+. The amplification was shown to occur under the conditions of ionisation of the working ions, and the time of output radiation saturation depends on the time of Xe8+ transformation to higher-ionised ions. Our theoretical investigation enables determining the optimal pump parameters, at which the product of the gain g by the active medium length L is about 20, which exceeds the experimental gL value. (active media)
Using longitudinal data from Ukraine we examine the extent of any long-lasting effects of exposure to the Chernobyl disaster on the health and labour market performance of the adult workforce. Variation in the local area level of radiation fallout from the Chernobyl accident is considered as a random exogenous shock with which to try to establish its causal impact on poor health, labour force participation, hours worked and wages. There appears to be a significant positive association between local area-level radiation dosage and perception of poor health, though much weaker associations between local area-level dosage and other specific self-reported health conditions. There is also some evidence to suggest that those who lived in areas more exposed to Chernobyl-induced radiation have sig...
The determination of optical parameter type in x-ray pelvimetry was performed on 59 subjects using Fuji computed radiography (FCR). Excellent measurable images were obtained at GT (type A), RT (type P), GA (1.6) and RN (2.0). To reduce maternal and fetal exposure to radiation, the doses were progressively decreased to 50%, 25%, 12.5%, 6.3%, that of conventional screen/film system. One-eighth per cent of conventional radiation dose was minimum for FCR at which measurable images could be obtained. Thereby drastically reducing the radiological exposure to both mother and fetus was possible to obtain measurable images in FCR. (author).
The determination of optical parameter type in x-ray pelvimetry was performed on 59 subjects using Fuji computed radiography (FCR). Excellent measurable images were obtained at GT (type A), RT (type P), GA (1.6) and RN (2.0). To reduce maternal and fetal exposure to radiation, the doses were progressively decreased to 50%, 25%, 12.5%, 6.3%, that of conventional screen/film system. One-eighth per cent of conventional radiation dose was minimum for FCR at which measurable images could be obtained. Thereby drastically reducing the radiological exposure to both mother and fetus was possible to obtain measurable images in FCR. (author).
Seventy-one patients with intestinal injury secondary to pelvic irradiation had predominantly large bowel lesions. Seventeen cases were treated conservatively and 54 came to surgery, 28 patients having more than one operation. Following this essentially salvage surgery there were more ileal than colonic anastomotic leaks. Thirty-four patients died during the follow-up period (2-12 years), 19 from recurrent malignancy, and nine as a result of continuing radiation effects. Seventy per cent of the patients who had a radiation fistula died as a result of malignancy. Of 42000 cases of pelvic malignancy treated by irradiation over the decade 1972-1982, surgical referrals for complications constituted 1.7%, with an overall radiation-related mortality of 0.2%. It is our opinion that colostomy alone has little part to play in this condition, and a policy based on excisional surgery is suggested.
The synthetic process of polyethylene cation exchange capillary via radiation grafting polystyrene by simultaneous irradiation with "6"0Co #gamma#-ray source and sulfonation with concentrated H_2SO_4 was studied. The effects of dose, dose rate, monomer concentration, solvents, temperature and crosslinking agents on the graft copolymerization of styrene with polyethylene capillary were illustrated. The relationship between the radiation grafting conditions and the properties of ion-exchange capillary were examined. A polyethylene cation exchange capillary with I.D. 0.8 mm, length 20 m, exchange capacity 0.7 Meq/g 60% capacity in 10 s (flow rate 20 ml/min) was prepared. No significant loss of copacity was found from this ion-exchange capillary after 200 adsorption/regeneration cycles.
The physics of density limit phenomena in toroidal helical plasmas based on an analytic point model of toroidal plasmas is discussed. The combined mechanism of the transport and radiation loss of energy is analyzed, and the achievable density is derived. A scaling law of the density limit is discussed. The dependence of the critical density on the heating power, magnetic field, plasma size and safety factor in the case of L-mode energy confinement is explained. The dynamic evolution of the plasma energy and radiation loss is discussed. Assuming a simple model of density evolution, of a sudden loss of density if the temperature becomes lower than critical value, then a limit cycle oscillation is shown to occur. A condition that divides the limit cycle oscillation and the complete radiation collapse is discussed. This model seems to explain the density limit oscillation that has been observed on the W7-AS ...
A method for conditioning electron beams is proposed, making use of the TM{sub 210} mode of microwave cavities, to reduce the axial velocity spread within the beam, in order to enhance gain in resonant electron beam devices, such as the free-electron laser (FEL). Effectively, a conditioner removes the restriction on beam emittance. The conditioner is analyzed using a simple model for beam transport and ideal RF cavities. Analysis of an FEL is employed to evaluate performance with reduced axial velocity spread. Examples of FELs are presented showing the distinct advantage of conditioning.
This paper analyses the errors caused by interpolation from existing cases for assessing indoor air flow, air quality and thermal comfort in an office. A sensitivity study is then provided to determine the influence of several boundary conditions on indoor air diffusion. The research is conducted numerically by using a low-Reynolds-number k-{epsilon} model. It can be concluded that the interpolation errors caused by the variations of solar radiation, window size, heat source location due to lighting, and the surface temperatures of interior walls are small and can be quantitatively determined. But it is difficult to estimate the errors introduced by the variations of furniture location and size. (author).
Steady-state and transient behavior of the longitudinally pumped semiconductor laser is theoretically investigated by using a rate-equation model with distributed gain and photon density. Conditions necessary for bistable operation are derived. Dependencies of such major switching characteristics as turn-on and turn-off powers, delay, and rise times on laser parameters are examined. Influences of spontaneous radiation, impurities, and Auger recombination are studied. The results offer an explanation for the observed nonlinear behavior of face-pumped lasers.
Spontaneous and ultraviolet-induced changeabilities of wine yeasts from the killer state to sensitive one have been studied. Observed often spontaneous changes of killer and neutral phenotypes under laboratory store conditions as well as high mutation frequency of genetic elements responsible for the killer indication on ultraviolet irradiation testify that often encounterability in nature and in the production of sensitive yeasts is attributed to high frequency of mutation changes of the killer and neutral phenotypes to the sensitive state.
Elevated pH operation to the pH value of 7.3 at 285degC is known to be effective for the reduction of radiation source in the primary water system of PWRs. A research project was started in 1989 and concluded in 1996 to study and verify the optimum pH and/or Li concentration from the viewpoint of radiation source reduction and materials integrity under improved water chemistry. This research project is sponsored by the Ministry of International Trade and Industries (MITI) in Japan and has two programs; high pH and high Li. The high Li program was conducted to establish the optimum Li concentration for the high boron concentration region (1100 - 1800 ppm) of the high burn up operation. In this paper, we shall discuss radiation source behavior under high pH conditions and PWSCC (Primary Water Stress Corrosion Cracking) susceptibility of materials with change of primary water chemistry ...
Generally, neutron, ion and electron Irradiations cause a substantial amount of hardening and significantly alter the deformation behavior of metals and alloys at relatively low irradiation temperatures. A radiation hardening is caused by the formation of microstructural defects such as dislocation loops, voids and precipitates under irradiation. Therefore, it is important to have a better knowledge of the irradiation induced microstructural defects under irradiation condition. As a part of the National mid- and long-term atomic energy R and D program, we are dealing with the radiation hardening behavior in Fe-Cr binary alloy. Fe-Cr binary alloy is a base alloy of Ferritic/Martensitic steel(F/M steel) planning to use for the Gen IV nuclear system. In this work, we investigated the radiation hardening and microstructural defect evolution in ion irradiated Fe-Cr alloys with irradiation temperature using ...
Two local repair procedures, one without (9) and the other with (14) a bulbocavernosus muscle graft were performed on 20 patients with a radiation induced rectovaginal fistula. Four patients had two procedures successively. The initial success rate of both procedures was 7/9 and 14/14 respectively. Though the initial result of the bulbocavernosus graft was obviously better, in many of the local repair procedures, subclinical radiation damage progressed, resulting in recurrence of rectovaginal fistula (5), rectovesical fistula (4), pararectal abscess (2) etc. After a mean follow up of around 10 years, the success rate of fistula repair decreased to 5/9 and 13/14 and only 2/9 and 6/14 finally remained without a colostomy. A local repair operation should be restricted to carefully selected cases. The musculus gracilis is proposed as a better vascular graft. If the general condition of the patient does not allow more aggressive ...
The purpose of this study is to identify the radiative heat transfer augmentation by a coaxial cylinder introduced in the infinite cylindrical pipe enclosing a participating gas. The gas is either a mixture of water vapor and carbon dioxide or gray. The gas is assumed to be homogeneous at a constant temperature, and has a refractive index of unity. All of the surfaces are opaque and gray, diffusely emitting and reflecting at a constant temperature. The effect of system diameter, diameter ratio, wall emittances, gas and surface temperatures, mixture component on heat transfer augmentation are studied by using the zone method with participating gas radiative properties evaluated from the weighted sum of gray gases model. From the radiative equilibrium condition, the installed wall temperature is formulated and calculated by the iteration method. If the medium is a gray gas, the augmentation observed are ...
E-35 reported the specific air flow analysis program using a CFSV model (including a human body model) to develop a high-accuracy evaluation simulator for heterogeneous thermal environment based on human thermal physiological conditions. E-36 reported development of the radiation heat transfer analysis module by using a numerical integral method to calculate shape factors. Radiation heat transfer characteristics every body part were clarified quantitatively by this module. E-37 reported the results on continuous measurement of physiological conditions and thermal environment factors every monitor under controlled indoor thermal environment, to collect measurement data necessary for improving the accuracy of a prediction program for human body temperatures. E-38 reported the study result on physiological reaction and subjective evaluation through an examinee experiment in a blood controlled region, to ...
Full text of publication follows: Radiation hardening and embrittlement due to high-energy neutron radiation around 623 K are the important issues on reduced-activation ferritic/martensitic (RAF/M) steels. It is expected that the improvement of radiation hardening might be one of effective ways to control the mechanical properties of RAF/M after irradiation. It has been reported that the weld joint has less hardening than the base metal from the tensile test results of TIG weldments irradiated in HFIR. This report indicated that radiation hardening can be reduced by the optimization of heat treatment condition for F82H. The purposes of this study are to establish the condition of heat treatment for minimum of radiation hardening in F82H steel using Neutron/Ion-irradiation and to examine a correlation between tensile property and ...
New comparative tests on two different types of solar collectors are presented in this paper. A standard glazed flat plate collector and an evacuated tube collector are installed in parallel and tested at the same working conditions; the evacuated collector is a direct flow through type with external compound parabolic concentrator (CPC) reflectors. Efficiency in steady-state and quasi-dynamic conditions is measured following the standard and it is compared with the input/output curves measured for the whole day. The first purpose of the present work is the comparison of results in steady-state and quasi-dynamic test methods both for flat plate and evacuated tube collectors. Besides this, the objective is to characterize and to compare the daily energy performance of these two types of collectors. An effective mean for describing and analyzing the daily performance is the so called input/output diagram, in which the collected solar energy is ...
The absorption of solar heat and the attendant thermal and mechanical loadings on the tubes of cavity receivers depend predominantly on the flux distribution of the incident solar radiation. For an axially symmetric cavity receiver with a parabolic dish collector, it is simple to determine the insolation pattern on the receiver internal surfaces if the system is ideal. In such a system the surface of the dish is perfectly parabolic (no contour flaws are present), and the sun's central ray impinges on the dish surface parallel to the focal axis (no sun tracking flaws are present). These two conditions cannot be achieved in practice, and therefore the feasible parabolic dish system is referred to as a real system although, in actual fact, it is only an approximation to any actual system. The purpose of this paper is to devise calculation principles which permit analysis of a receiver designed for ideal conditions to ...
We study the stability of the circular orbits of the electromagnetic two-body problem of classical electrodynamics. We introduce the concept of resonant dissipation, i.e. a motion that radiates the center-of-mass energy while the interparticle distance performs bounded oscillations about a metastable orbit. The stability mechanism is established by the existence of a quartic resonant constant generated by the stiff eigenvalues of the linear stability problem. This constant bounds the particles together during the radiative recoil. The condition of resonant dissipation predicts angular momenta for the metastable orbits in reasonable agreement with the Bohr atom. The principal result is that the emission lines agree with the predictions of quantum electrodynamics (QED) with 1 percent average error even up to the $40^{th}$ line. Our angular momenta depend logarithmically on the mass of the heavy body, such that the deuterium ...
Consideration is given to the data, demonstrating the effect of ion radiation on strength characteristics of ionic crystals, presented by magnesium oxide. Crystals, prepared in the form of plates, were irradiated by Si"+, Fe"+, C"+ ions by the dose of 10"1"6-10"1"7 ion/cm"2 at room temperature in vacuum. The following characteristics were investigated: dislocation density, microhardness, crack resistance. Investigation of dislocation structure showed, that dislocation density in irradiated sample was 2-3 times higher, as compared to nonirradiated one. Sufficient increase of fracture viscosity of MgO crystals was revealed. It can be conditioned by occurrence of compression stresses in the surface layer, decelerating crack formation and propagation.
The formation of nanoparticles during the radiation-induced chemical reduction of silver ions, copper ions, and nickel ions in films based on poly(acrylic acid)-poly(ethylenimine) complexes are studied via electron microscopy. This approach allows preparation of composites containing nanoparticles that are randomly distributed in the polymer matrix and materials with a regular spatial distribution of nanoparticles across the film thickness and in subsurface layers. The structure of metal-polymer hybrid materials is dependent on the irradiation conditions, the type of reduced metal ions, and their initial content in polymer matrices. The ratio between the rate of nucleation and the rate of growth of nanoparticles in the matrices of interpolyelectrolyte complexes depends on the intensity of ...
Temperature variations due to climate changes are a major cause of movements in a concrete structure, both in the longitudinal and transversal directions and between different parts of the structure. If these movements are restrained, stresses will be induced which may contribute to cracking. The movements are caused by complex interactions of several factors such as solar radiation, air temperature, long-wave heat radiation and wind speed. To predict the varying thermal conditions in a concrete structure a finite element model has been used. A validation of the model has been performed using field measurements in a concrete slab together with climate data from the Swedish Meteorological and Hydrological Institute to be able to use the model for simulations over long time periods and for s...
This paper reviews various techniques to harden Charged Coupled Device (CCD) sensors and the results after irradiation of three Thomson n buried channel CCDs having a different degree of hardening. It describes the major irradiation effects on CCD performances and it makes a comparison of the results between the different hardening levels. It shows good results on dark voltage after ionizing radiation for TH 7863M device hardened both by design and by operating conditions (MPP mode) with respect to the standard device TH 7863A. The irradiations were performed with "6"0Co or X-ray (10 keV) sources on devices in operating mode. (author). 3 refs., 8 figs.
This paper provides a physically-based engineering model to estimate radiation hardening of 9%Cr-steels under both displacement damage (dpa) and helium. The model is essentially based on the dispersed barrier hardening theory and the dynamic re-solution of helium under displacement cascades but incorporating a number of assumptions and simplifications [Trinkaus, J. Nucl. Mater. 318 (2003) 234-340]. As a result, the kinetics of the damage accumulation kept fixed, its amplitude is fitted on one experimental condition. The model was rationalized on an experimental database that mainly consists of 9%Cr-steels irradiated in the range of 50-600degreeC up to 50dpa and with a He-content up to 5000appm. The test temperature effect is taken into account through a normalization procedure based on the...
The operation and proper handling of equipment for measuring EMR-300 electromagnetic waves are studied and apply that knowledge to determine which areas of the metropolitan area are mostly affected by exposure to the emission of radiation. This team is able to measure magnetic field strength, electric field strength and power density, also can measure the most important parameters in a simple manner. International standards provide maximum values for these parameters that limit human exposure to such radiation. These standards are based on epidemiological several and laboratory that have been carried out in order to determine in which circumstances a biological entity is exposed to a level of radiation that can cause harm to their health. It focuses on measuring the level of radiation in certain areas of interest, which were chosen because are areas with high population density and also in proximity to ...
The opportunity of use self-maintained plasma-beam discharge in an extended pulsing plasma diode of low pressure for making powerful sources of the soft X-rays is investigated. Conditions of formation of the self-maintained plasma-beam discharge are determined. The mode of making of dense high-temperature plasma on the basis of stannum ions in the discharge is shown. The stannum ions are used as a working element of a radiation sources at pulsing power of electron beam P?10...100 MW. Results of the examination on formation of the dense (np?1016 cm3), small sizes (le?100 eV in conditions of working material evaporation from the anode are given. The total contribution of energy to the discharge has made W < 20 J.
This study presents results from Monte Carlo radiation transport calculations aimed at characterizing a novel methodology being developed to detect partial defects in Pressurized Water Reactor (PWR) spent fuel assemblies (SFAs). The methodology uses a combination of measured neutron and gamma fields inside a spent fuel assembly in an in-situ condition where no movement of the fuel assembly is required. Previous studies performed on single isolated assemblies resulted in a unique base signature that would change when some of the fuel in the assembly is replaced with dummy fuel. These studies indicate that this signature is still valid in the in-situ condition enhancing the prospect of building a practical tool, Partial Defect Detector (PDET), which can be used in the field for partial defect detection.
A study was conducted to determine the fitting soil moisture for the normal growth of two-year-old W. sinensis (Sims) Sweets by using gas exchange technique. Remarkable threshold values of net photosynthetic rate (Pn), transpiration rate (Tr) and water use efficiency (WUE) were observed in the W. sinensis leaves treated by various soil moisture and photosynthetic available radiation (PAR). The fitting soil moisture for maintaining a high level of Pn and WUE was in range of 15.3%?26.5% of volumetric water content (VWC), of which the optimal VWC was 23.3%. Under the condition of fitting soil moisture, the light saturation point of leaves occurred at above 800?mol?m?2?s?1, whereas under the condition of water deficiency (VWC, 11.9% and 8.2%) or oversaturation (VWC, 26.5%), the light saturatio...
Under operational conditions in nuclear power plants, the carbon steel components of the primary and secondary circuits react with high temperature cooling agent forming several iron oxides and oxyhydroxides. These deposits can result in tubes' constrictions, pitting and intergranular corrosion and finally to heat transfer reducing and increasing of radiation fields around the circuits, as well. The descaling process involves the chemical dissolution of the corrosion deposits by means of diluted organic acidic solutions containing usually a carboxylic acid, a reductant and one or more corrosion inhibitors. To evaluate the removing rates of these superficial films two types of methods were used, the gravimetric and potentiodynamic techniques. By correlating the experimental results, we established the chemical composition of descaling solution and two models of mechanisms applicable to our specific conditions. (authors)
In this article a methodology is presented for studying the influence of the biomass moisture content and the biomass/air ratio on the producer gas composition and on the chemiluminescent emissions during the combustion process. Firstly, a mathematical model based on the thermo-chemical processes inside the gasifier is used to predict the composition of the producer gas as a mixture of CO, CO2, H2, N2, CH4 and H2O gases. Secondly, the predicted composition is introduced into a constant volume combustion bomb (CVCB), which simulates the typical conditions inside the combustion chamber of an internal combustion engine, in order to characterize its combustion under gasoline-type conditions through the instantaneous pressure and the detection of the spontaneous luminous radiation (chemilumines...
We study the phonon fluxes emitted when the condensate velocity crosses the speed of sound, i.e., in backgrounds which are analogue to that of a black hole. We focus on elongated one dimensional condensates, and on stationary flows. Our theoretical analysis and numerical results are based on the Bogoliubov-de-Gennes equation without any further approximation. The spectral properties of the fluxes and of the long distance density-density correlations are obtained, with and without an initial temperature. In realistic conditions, we show that the condensate temperature dominates the fluxes, and thus hides the presence of the spontaneous emission (the Hawking effect). We also explain why the temperature amplifies the long distance correlations which are intrinsic to this effect. This confirms that the correlations pattern offers a neat signature of the Hawking effect. Optimal conditions to observe the pattern are discussed.
A computer model of cryogenic system for storing solid antimatter is used to explore the radiative cooling-power requirements for long-term antimatter storage. If vacuum-chamber pressures as low as 10 to -18th power torr can be reached, and the rest of the large set of assumptions is valid, milligram quantities of solid antimatter could be stored indefinitely at 1.5 K using cooling powers of less than a microwatt. Many of the assumptions made are problematic and need verification, as they could potentially change the results greatly. The system modeled is a sphere of solid anti-parahydrogen at 1.5 K or below levitated in a spherical cryogenic vacuum chamber. The free matter gas in the chamber is assumed to be molecular hydrogen, and sublimation of both matter and antimatter is assumed to be negligible. The antihydrogen is assumed to be in thermal equilibrium, although annihilation-energy deposition is localized and hydrogen's thermal-impulse response time ...
Advanced modality of high-precision radiotherapy fulfilled by a composition of large numbers of small field beams called 'beamlets' can be achieved via nonuniform intensity fluencies. In case of radiation measurements and calculations with narrow high-energy photon beams, however, an accurate two-dimensional dosimetry is a challenging task due to dosimetrically unfavorable phenomena such as dramatic changes of the dose at the field boundaries, dis-equilibrium of the electrons resulting from larger detector volume, and non-uniformity between the detector and the phantom materials. Meanwhile, with the advantages of high spatial resolution and wide range of absorbed doses, there is a growing demand of GAFCHROMICat..EBT film to confirm delivered dose distribution. Especially, the effects from the material differences between the phantom and the film can be minimized in the heterogeneous condition since the GAFCHROMICat..EBT film is composed of ...
This paper provides a physically-based engineering model to estimate radiation hardening of 9%Cr-steels under both displacement damage (dpa) and helium. The model is essentially based on the dispersed barrier hardening theory and the dynamic re-solution of helium under displacement cascades but incorporating a number of assumptions and simplifications [Trinkaus, J. Nucl. Mater. 318 (2003) 234-340]. As a result, the kinetics of the damage accumulation kept fixed, its amplitude is fitted on one experimental condition. The model was rationalized on an experimental database that mainly consists of ?9%Cr-steels irradiated in the range of 50-600 deg. C up to 50 dpa and with a He-content up to 5000 appm. The test temperature effect is taken into account through a normalization procedure based on the change of the Young's modulus and the anelastic deformation that occurs at high temperature. Despite the large experimental scatter, inherent to the ...
We developed a new TLD array for precise dose measurement and verification of the spatial dose distribution in small radiation targets. It consists of a hemicylindrical, tissue-equivalent rod made of polystyrene with 17 parallel moulds for an exact positioning of each TLD. The spatial resolution of the TLD array was evaluated using the Leskell spherical phantom. Dose planning was performed with KULA 4.4 under stereotactic conditions on axial CT images. In the Leksell gamma unit the TLD array was irradiated with a maximal dose of 10 Gy with an unplugged 14 mm collimator. The doses delivered to the TLDs were rechecked by diode detector and film dosimetry and compared to the computer-generated dose profile. We found excellent agreement of our measured values, even at the critical penumbra decline. For the 14 mm and 18 mm collimator and for the 11 mm collimator combination we compared the measured and calculated data at full width at half maximum. ...
The survivability of the final optic, which must sit in the line of sight of high-energy neutrons and gamma rays, is a key issue for any laser-driven inertial fusion energy (IFE) concept. Previous work has concentrated on the use of reflective optics. Here, we introduce and analyze the use of a transmissive final optic for the IFE application. Our experimental work has been conducted at a range of doses and dose rates, including those comparable to the conditions at the IFE final optic. The experimental work, in conjunction with detailed analysis, suggests that a thin, fused silica Fresnel lens may be an attractive option when used at a wavelength of 351 nm. Our measurements and molecular dynamics simulations provide convincing evidence that the radiation damage, which leads to optical absorption, not only saturates but that a 'radiation annealing' effect is observed. A system-level description is provided, including ...
Large-scale field tracer experiments have been conducted on Ulchin and Wolsung nuclear sites for the purpose of validating FADAS and of analyzing the environmental characteristics around the nuclear site. The most influential factor in atmospheric dispersion is the meteorological condition. During the experiment, meteorological data were measured on the release point and the selected positions among sampling points. Once radioactive materials are released to the atmosphere, members of public may be exposed through the environmental media such as air, soil and foods. Therefore, to protect the public, adequate countermeasures should be taken at due time for those exposure pathways. Both processes of justification and optimization are applied to a countermeasure simultaneously for decision-making. The work scope of biological research for the radiation protection had contained the search of biological microanalytic methods for the assessment of ...
Manned-space missions bring an exposure due to corpuscular radiations of which nature is quite different from what we encounter in the ground environment. In the space environment, many secondaries are produced through interactions of cosmic ray primaries with the spacecraft wall and other surrounding materials. Among this large variety of radiation components in the space, the contribution of neutrons to the radiation exposure of astronauts has remained to be studied. Up to today, efforts to measure neutron dose equivalent have been made using passive detector systems. Considering uncertainties involved in current measurements and estimations of high energy neutrons, and their increasing importance for future manned missions, it is necessary to measure neutron spectrum in the spacecraft under realistic conditions. The neutron spectra have never been measured on board a spacecraft, because the neutron ...
We compare the predictions of four different algorithms for the distribution of ionized gas during the Epoch of Reionization. These algorithms are all used to run a 100 Mpc/h simulation of reionization with the same initial conditions. Two of the algorithms are state-of-the-art ray-tracing radiative transfer codes that use disparate methods to calculate the ionization history. The other two algorithms are fast but more approximate schemes based on iterative application of a smoothing filter to the underlying source and density fields. We compare these algorithms' resulting ionization and 21 cm fields using several different statistical measures. The two radiative transfer schemes are in excellent agreement with each other (with the cross-correlation coefficient of the ionization fields >0.8 for k 0.6 for k < 1 h/Mpc). When used to predict the 21cm power spectrum at different times during reionization, all ionization ...
A multi-stage, multi-disk type seismic source was developed as a downhole seismic source. The seismic source is an improved version of the downhole seismic source of a system in which an elastic wave is generated by a weight accelerated by restitutive force of a spring striking the upper part of a laminated structure consisted of metal disks and elastic bodies installed in water in a well. Enhancing the vibration exciting efficiency requires impedance radiated from the disks to be increased. The multi-disk structure was adopted because of restrictions on the disk area under the limiting condition of being inside the well. Further limitation has still existed, which led to finally structuring the multi-disk type to a multi-stage construction to increase the radiated impedance. In order to increase average velocity on the radiation surface, mass relationship between the hammer and the anvil was sought so ...
Results are presented applying an enteral nutrition by means of probes with Cosilat in complex therapy of patients with radiotherapeutic late effects of the colon. This nutrition was prescribed with the intention to gave the colon a functional recovery and to guarantee optimal conditions for repair of radiation injuries. Good results were seen in 27 of 28 patients (96.7%), the situation of one patient (3.3%) continued without any change. Cosilat has a high nutritive value, good organoleptic qualities and is well digested without any complications. (author).
Application to carbon fiber started in this Year. In this paper, a spinning and calcination process are explained. Fiber was obtained by wet spinning of the PAN solution. Ten solvents were tested and the results proved that dimethyl sulfoxide (DMSO) was the best solvent. Glycerine was used as a coagulating bath. The thin fiber (10 to 50 denier) was produced under the conditions of about 20wt% concentration at about 110degC. Heat-treat temperature was about 270 to 275degC. The viscosity-tacticity relationship and T{sub sol} vs. inverse tacticity were shown in the paper. (S.Y.)
Various remedial measures have been tried to lower radon levels in buildings in Uranium City. The methods used are source material removal, passive ventilation of crawl spaces, sub-floor ventilation, complete epoxy coating of the entire basement, sealants for floor-wall joints and cracks in basements, electrostatic precipitators, mechanical ventilation, and sealing and grouting concrete block plenums in basement walls. The type and condition of structures encountered in Uranium City as well as the relative isolation of the town indicate that mechanical ventilation is the most long-term cost-effective method.
The document represents a guide for the external decontamination of persons accidentally radio contaminated due to the use, production or transport of radioactive materials. The general conditions, from the medical point of view, to be kept in mind, in the event of accidental overexposures as decontamination treatment and the handling of samples are detailed throughout report. The external contamination without injury in skin or with wound its considered. The distribution of measures and responsibilities for the therapy of the irradiated patients with radioactive materials are enumerated. The preparations of decontaminate solutions are detailed in this work. Moreover, forms for the reception, physical evaluation of the patient and external contamination are presented. (author)
In a supercritical water-cooled reactor, property of water changes significantly around the critical point. It is expected that irradiation and change of water property will affect the chemistry and material corrosion. Deep understanding of interactions between supercritical water and materials under irradiation is important. However, comprehensive data on radiolysis, kinetics, corrosion and thermodynamics have not been obtained due to the severe experimental condition. To get such data by experiments and computer simulations, a national program funded by Ministry of Education, Culture, Sports, Science and Technology (MEXT) has been started since December 2002. (author)
Bases of the algorithm for assessing the reinforcement status in reinforced concrete products by gamma-absorption method are presented. Analytical equations are obtained for estimation of error of the parameter characterizing the degree of reinforcement destruction. It is recommended to use high-energy Bremsstrahlung sources-betatrons of 4-10 MeV maximum energy for testing products of 500-600 mm thick. Linear radiation attenuation factor (LAF) of concrete in estimated equation is replaced by effective LAF of concrete, and LAF of reinforcement and corrosion materials - by differential LAF. Corresponding LAF of nonevident form in the algorithm is assessed by the results of processing of direct-shadow radiographs of defectometers
Axially symmetric waveguides, resonators, and scatterers of arbitrary cross section and anisotropy in the cross section can be modeled rigorously with use of 2-D Cartesian-grid based codes by means of mere redefinition of material permittivity and permeability profiles. The method is illustrated by the frequencydomain simulations of resonant modes in a circular-cylinder cavity with perfectly conducting walls, a shielded uniaxial anisotropic dielectric cylinder, and an open dielectric sphere for which, after proper implementation of the perfectly matched layer boundary conditions, the radiation quality factor is also determined.
In an ideal system the surface of the dish is perfectly parabolic (no contour flaws are present), and the sun rays fall on the dish surface parallel to the focal axis (no sun tracking flaws are present). These two conditions are not realizable in practice; in this case, the parabolic dish system is called real system. In this paper a procedure for analysing the flux distribution on the receiver internal surfaces is presented for a cavity receiver with a real parabolic dish collector. First, the theoretical principles are discussed. Then the effect of the inaccuracy in the collector and in the sun tracking on the insolation pattern is described using an example.
The linear integral equation based computer code (RON: Roger Oleg Nikolai), which was recently developed at Argonne National Laboratory, was used to calculate the self-amplified spontaneous emission (SASE) performance of the free-electron laser (FEL) being built at Argonne. Signal growth calculations under different conditions are used for estimating tolerances of actual design parameters. The radiation characteristics are discussed, and calculations using an ideal undulator magnetic field and a real measured magnetic field will be compared and discussed.
We have developed a new type personal dosemeter by using a B-10 doped silicon p-n junction detector with a polyethylene radiator and a polyethylene moderator. The purpose of this study was to develop a real time neutron dosemeter with a nearly flat response in the energy range from thermal to 15 MeV and low angular dependence to the incident neutron direction. The neutron response of the dosemeter was obtained with the Monte Carlo calculation and the monoenergetic neutron experiment in a free air field and also under a condition attached on a phantom.
HT-29 human colon tumor cells growing as spheroids have been evaluated as a model system for measuring the response of human colon tumor cell to antineoplastic agents. HT-29 cells have been capacity to form spheroids up to 1 mm or more in diameter when grown in spinner culture. The multicellular HT-29 spheroids develop hypoxic centers reflecting the cellular conditions found in human cancer treatment, i.e., nutritionally deficient hypoxic cells that are felt to be a significant source of both radiation and chemotherapy clinical treatment failures. Spheroids of increasing size were radiated and then dispersed into single cells for colony survival assay. Compared with irradiated single cell suspensions, the spheroid cells demonstrated a significant increase in radioresistance. Growing spheroids developed a complex radiation survival curve which was variable with respect to size of the spheroid. The drug ...
Abstract The authors provide a survey of how images are used in radiation therapy to improve the precision of radiation therapy plans, and delivery of radiation treatment. In contrast...Full Text Available
... radiation during clinical therapy and exposures due to radiation accidents or attacks, in which the doses are uncontrolled ... only be used off-label in victims of radiation accidents or attacks. The idea...
Purpose: To evaluate the effect of low-dose radiation therapy and surgery on local control in patients with Ewing's Sarcoma. Materials and Methods: Between 1979 and 1995 24 patients (ages 4-47) with Ewing's sarcoma were treated with combined modality therapy that included multi agent chemotherapy, surgical resection, and radiation therapy. Twelve patients had metastatic disease at the time of presentation (pleura = 3, lung = 5, bone 4). Tumor location was central in 16 and peripheral in 8. Multi agent chemotherapy consisted of vincristine/actinomycin D/cyclophosphamide/doxorubicin in 19. The same agents with the addition of ifosfamide and etoposide were given in 5. The extent of resection was considered to be radical in 14 and of the 16 patients who received preoperative chemotherapy, 5 were found to have a pathologic complete response. All patients with lung metastases at diagnosis received whole-lung irradiation to 1400 cGy in 10 fractions. ...
"What happens to conventional metals near the ocean?" you might ask the workers who are repairing the water tower at Jones Beach. They will tell you that both the tower's steel framework and copper roof show extensive corrosion from the salty air. To power future generations of cars, homes, utility plants, and even particle accelerators, unprecedented levels of efficiency will be needed. Such efficiency will require new unconventional alloys and composite materials that can also withstand high temperatures, intense radiation fluxes, high stresses, and other extreme conditions in highly corrosive environments that accelerate the aging and weakening of materials, as salty air weakens steel and copper. During the lecture, Simos will discuss the demands of next-generation energy systems and focus on the extreme conditions that materials used in these systems will perform under. He will also explain Brookhaven ...
Sodium-dependent high-affinity choline uptake was measured in the striatum, frontal cortex, hippocampus, and hypothalamus of rats after acute exposure (45 min) to pulsed (2 microseconds, 500 pps) or continuous-wave 2,450-MHz microwaves in cylindrical waveguides or miniature anechoic chambers. In all exposure conditions, the average whole-body specific absorption rate was at 0.6 W/kg. Decrease in choline uptake was observed in the frontal cortex after microwave exposure in all of the above irradiation conditions. Regardless of the exposure system used, hippocampal choline uptake was decreased after exposure to pulsed but not continuous-wave microwaves. Striatal choline uptake was decreased after exposure to either pulsed or continuous-wave microwaves in the miniature anechoic chamber. No significant change in hypothalamic choline uptake was observed under any of the exposure conditions studied. We conclude that depending on ...
The Two-Column Aerosol Project (TCAP) field campaign will provide a detailed set of observations with which to (1) perform radiative and cloud condensation nuclei (CCN) closure studies, (2) evaluate a new retrieval algorithm for aerosol optical depth (AOD) in the presence of clouds using passive remote sensing, (3) extend a previously developed technique to investigate aerosol indirect effects, and (4) evaluate the performance of a detailed regional-scale model and a more parameterized global-scale model in simulating particle activation and AOD associated with the aging of anthropogenic aerosols. To meet these science objectives, the Atmospheric Radiation Measurement (ARM) Climate Research Facility will deploy the ARM Mobile Facility (AMF) and the Mobile Aerosol Observing System (MAOS) on Cape Cod, Massachusetts, for a 12-month period starting in the summer of 2012 in order to quantify aerosol properties, radiation, and ...
Studies were made on different types of packaging materials used for packing dried fish in the Philippines with a view to finding a suitable packaging material for irradiated dried fish. Among these packaging materials (polyethylene, cello/polyethylene, polyester/polyethylene, Kraft paper, polypropylene and interwoven polypropylene sacks), polyester/polyethylene laminate was the most resistant material against penetration by Dermestes carnivorous. No insect damage occurred on the dried fish packed in interwoven polypropylene lined with polyester/polyethylene laminate. The cost per sack of such packaging material having a capacity of 50-80 kg is US$ 0.50. The sack lined with polyester/polyethylene proved to be durable for surface transportation from Bacolod City to Manila (approx. 360 miles). Radiation treatment at 225 krad was effective against bacterial contamination but not effective in inhibiting mould growth. Raw fish soaked in 25% salt for 2 hours before ...
In light water reactors, austenitic stainless steels (SSs) are used extensively as structural alloys in reactor core internal components because of their high strength, ductility, and fracture toughness. However, exposure to high levels of neutron irradiation for extended periods degrades the fracture properties of these steels by changing the material microstructure (e.g., radiation hardening) and microchemistry (e.g., radiation-induced segregation). Experimental data are presented on the fracture toughness and crack growth rates (CGRs) of wrought and cast austenitic SSs, including weld heat-affected-zone materials, that were irradiated to fluence levels as high as {approx} 2x 10{sup 21} n/cm{sup 2} (E > 1 MeV) ({approx} 3 dpa) in a light water reactor at 288-300 C. The results are compared with the data available in the literature. The effects of material composition, irradiation dose, and water chemistry on CGRs under cyclic and ...
Systematics of neutron capture radiative width were studied in the target element range from Th to Cm. Reduced radiative widths were analyzed with a simple radiative width formula based on E1 transition. Average radiative width is presented with the standard deviation of 15%. (author)
Investigated here were the effects of microwave (MW) radiation (2450-MHz, continuous-wave, mean specific absorption rate of 103.5 + or - 4.2 W/kg) and convention heating on the nonphosphorylating oxidative metabolism of human peripheral mononuclear leukocytes (96% lymphocytes, 4% monocytes) at 37 C. Metabolic activity, determined by chemiluminescence (CL) of cells challenged with luminol (5-aminO-2, 3-dihydro-1, 4-phthalazinedione) linked to bovine serum albumin, was detected with a brightness photomer. A significant stimulation after after MW exposure (p < 0.005) over total CL of matched 37 C-incubator controls was observed. A similar degree of stimulation, compared to incubator controls, was also detected after sham treatment. No significant difference existed between changes in total CL or stimulation indices of the MW and sham-exposed groups. Exposure to MW radiation, under normothermic (37 + or - 0.03 C) conditions, ...
Large-scale field tracer experiments have been conducted on Ulchin, Wolsung and Daeduk sites for the purpose of validating FADAS and of analyzing the environmental characteristics around the nuclear sites. The most influential factor in atmospheric dispersion is the meteorological condition. During the experiment, meteorological data were measured on the release point and the selected positions among sampling points. Once radioactive materials are released to the atmosphere, members of public may be exposed through the environmental media such as air, soil and foods. Therefore, to protect the public, adequate countermeasures should be taken at due time for those exposure pathways. both processes, of justification and optimization are applied to a countermeasure simultaneously for decision-making. The work scope of Biological research for the radiation protection had contained the search of biological microanalytic methods for assessing the ...
In order to qualify corrosion resistant materials for high level waste (HLW) packagings acting as a long-term barrier in a rock salt repository, the corrosion behaviour of the preselected materials Ti 99.8-Pd, Hastelloy C4 and two unalloyed steels was investigated. The resistance of the materials to general corrosion, local corrosion and stress corrosion cracking was examined under postulated accident conditions in the repository by long-term immersion tests of up to 4 years duration and electrochemical methods. The parameters investigated were different salt brines, temperatures of 90 deg. C, 170 deg. C and 200 deg. C as well as a gamma radiation field of 10"3Gy/h (10"5rad/h). Among the materials studied, Ti 99.8-Pd exhibited the highest corrosion resistance. This material corroded at a very low rate (radiation, and proved to be resistant to local corrosion and stress corrosion ...
Objective: To apply the obtained results from 3 stages of research in Chinese radiation protection field. Methods: Based on the identification of physical, chemical and biological qualities for element and its radionuclides under equilibrium condition, main application of these results in Chinese radiation protection field have been discussed by using reported methods in literature. Results: Based on developing elemental reference values of organs or tissues, whole body burdens and their distribution for Chinese Reference Man, discussed in the above 3 articles, current dietary elemental intakes of 42 elements have been updated, and related basis for certain important parameters of bio-kinetic model for use in radiation protection (for example, f_l, T_e and T_b) have been provided. The internal doses from primordial radionuclides and transfer coefficients of elements from environment into the critical ...
General estimates and references are made in connection with the role of technological physics in obtaining materials with specific features. The first part of the paper presents the modification of weak wood essences as well as technological processes at bench-scale and semi industrial scale of wood-plastic composites, under various irradiation conditions. Two technological installations for the fabrication of wood-plastic composites on both scales with technical and practical specifications of their performances are presented. Experimental data for different wood-plastic composite systems using some local wood essences in combination with several polymer and copolymer systems are given. Impregnation and polymerization levels are mentioned for every specific system. The radiation dose rate and integrated dose are given for every experimental polymerization system. The features of the wood-plastic composites are compared with the initial wood ...
Upgrading of oil palm empty fruit bunch (EFB), which is a main by-product of palm oil industry, to animal feeds by radiation pasteurization and fermentation was investigated for recycling the agro-resources and reducing the environmental pollution. The following results were obtained: 1) The necessary dose for pasteurization of EFB contaminated by various microorganisms including aflatoxin producing fungi was determined as 10 kGy. The chemical and biological properties of EFB were changed little by irradiation up to 50 kGy. 2) In the fermentation process, Pleurotus sajor-caju was selected as the most effective fungi and the optimum condition for fermentation was clarified. The process of fermentation in suspension was also established for the liquid seed preparation. 3) The digestibility and nutritional value of fermented products were evaluated as ruminant animal feeds and the mushroom can be produced as by-product. 4) The pilot plant named ...
A brain weight deficit of about 70 mg was induced at doses of approximately 75-mGy and a deficit of 60 mg was induced at 100 mGy. This confirms the effects projected and observed by Wanner and Edwards. Although the data do not demonstrate a clear dose-response relationship between the 75-mGy and 100-mGy groups, the data are statistically consistent with a dose-response effect because of the overlapping confidence intervals. The lack of a statistically significant observation is most likely related to the small difference in doses and the limited numbers of animals examined. There are several factors that can influence the brain weight of guinea pig pups, such as caging and housing conditions, the sex of the animal, and litter size. These should be taken into account for accurate analysis. Dam weight did not appear to have a significant effect. The confirmation of a micrencephalic effect induced x rays at doses of 75-mGy during this late embryonic stage of ...
In Canada, the cost of heating is a major expense in the operation of greenhouses in the winter season, inhibiting greenhouse production in winter months in most part of the country. Alternative energy sources, such as solar energy and biomass energy may offer an economically feasible heating alternative. A solar energy greenhouse technology developed in northern China for winter vegetable production has demonstrated good potential for Manitoba winter conditions. The design and performance of solar energy greenhouses depend on the geographical location. Therefore, in order to optimize the design of solar greenhouses with respect to the latitude of the location for maximum solar radiation gain, a theoretical analysis was performed that analyzed parameters such as greenhouse length and the roof slope. This paper described the methodology of the study, including a description of solar energy greenhouses; the energy of solar ...
The project is described, the motivation for the research and the microclimate is defined in relation to both building physics research and applications. Air temperatur, air humidity, solar radiation and air velocity are briefly considered, whilst driving rain and long-wave radiation are described in more detail. Convective heat transfer and surface coefficients are discussed, although they are not microclimatic factors, merely resulting from combinations of such factors. They are included as they are important in relation to transfer of heat and moisture at the surface of the building envelope. Driving rain measurement is the main area of interest, including development of measurement equipment. Long-wave irradiation is measured and compared with empirical formulae from the literature. Window convection heat transfer is another main area of interest. Nocturnal convective heat transfer from a double pane glazing is studied and measurement ...
Radiation defects produced by helium implantation were used to shape profiles of palladium (Pd) and platinum (Pt) atoms in-diffusing (for 20 min at temperatures 600-800 deg. C) either from surface silicide (Pd_2Si, PtSi) or implanted layers. Results show that this procedure allows a strong localization of substitutional Pd and Pt at the depth where the damage produced by helium peaks. This results in local reduction of carrier lifetime by an almost ideal recombination centers - the acceptor level of substitutional Pd (E _c - 0.22 eV) or Pt (E _c - 0.23 eV). While optimum conditions for Pt in-diffusion are about 700 deg. C, Pd gives the best results already at lower temperatures (600 deg. C) where it also exhibits higher peak solubility. Both methods were used for optimization of turn-off properties of high power PiN diodes. The devices, where the lifetime was killed locally by Pd and Pt, exhibited similar trade-off between the static and ...
Radiation-and-thermal-combined degradation of ethylene-propylene rubber (EP rubber) and chlorosulfonated polyethylene (CSM) as cable insulating and jacketing materials were evaluated by accelerated aging tests and a method to assess the lifetime of these materials under practical application was studied. EP rubber and CSM of experimental formulation were degraded at accelerated rates, that are 50 [approx] 1000 times the degradation rate under a standard condition (1Gy/h, 50degC). The degradation was investigated by measuring the tensile properties. In the accelerated aging tests, rates of elongation decrease owing to degradation for both EP rubber and CSM were in proportion to increase in accelerated rate. Behaviors of elongation changes showed little difference with accelerated rate. EP rubber lifetime estimated from sequential aging test had a tendency to extend beyond that from simultaneous aging test, while CSM lifetime estimated from both ...
Radiation-and-thermal-combined degradation of ethylene-propylene rubber (EP rubber) and chlorosulfonated polyethylene (CSM) as cable insulating and jacketing materials were evaluated by accelerated aging tests and a method to assess the lifetime of these materials under practical application was studied. EP rubber and CSM of experimental formulation were degraded at accelerated rates, that are 50 #approx# 1000 times the degradation rate under a standard condition (1Gy/h, 50degC). The degradation was investigated by measuring the tensile properties. In the accelerated aging tests, rates of elongation decrease owing to degradation for both EP rubber and CSM were in proportion to increase in accelerated rate. Behaviors of elongation changes showed little difference with accelerated rate. EP rubber lifetime estimated from sequential aging test had a tendency to extend beyond that from simultaneous aging test, while CSM lifetime estimated from both ...
An experimental investigation of premixed methane-air combustion within the one-dimensional porous ceramic burners for various burner configurations is presented. The burner is nonhomogeneous because of different pore size ceramic block used in different section of the burner. Therefore, the thermophysical and transport properties are nonuniform along the burner core length. The burners are constructed of partially stabilized zirconia. The CO and NO{sub x} emissions, flame speed, and flame stability are examined and compared at lean equivalence ratios for five different burner configurations. The sandwich-structured burner has very favorable flame stabilizing characteristic due to the radiation reflecting region. While the combustion proceeds at faster rate than other burner configurations, the radiation reflecting region and the exit surface have low temperature. Thus the NO{sub x} emission can be kept at the same low level as the other burner ...
Forty samples of medicinal plants (Peumus boldus, Camellia sinensis, Maytenus ilicifolia and Cassia angustifolia), purchased from pharmacies and street market in the five cities of Sao Paulo State, were irradiated using a "6"0Co gamma ray source (Gammacell) with a dose of 10.0 kGy, delivered at dose rate of 3.0 kGy/h. Nonirradiated samples were used as controls of fungal isolates. For fungal counts and identification in medicinal plants a serial dilutions from 10"-"1 to 10"-"6 of the samples were seeded in duplicates and plated using the method in Dichloran 18% Glycerol Agar (DG 18) and were counted after five days at 25 deg C. Mycological analysis of control samples revealed the presence of genera Aspergillus and Penicillium, which are known as toxigenic fungi. The process of gamma radiation was effective in reducing the number of colony forming units (cfu/g) in all irradiated samples of medicinal plants after 30 days, using the dose of 10.0 kGy and kept of veiled ...
The author studied the conditions needed to routinely estimate the radiation dose in chicken bone by repeated re-irradiation and measuring ESR signals. Chicken meat containing bone was {gamma}-irradiated at doses of up to 3kGy, accepted as the commercially used dose. The results show that points in sample preparation and ESR measurement are as follows: Both ends of bone are cut off and central part of compact bone is used for experiment. To obtain accurate ESR spectrum, marrow should be scraped out completely. Sample bone fragments of 1-2mm particle size and ca.100mg are recommended to obtain stable and maximum signal. In practice, by re-irradiating up to 5kGy and extrapolating data of the signal intensity to zero using linear regression analysis, radiation dose is estimated. For example, in one experiment, estimated doses of chicken bones initially irradiated at 3.0kGy, 1.0kGy, 0.50kGy and 0.25kGy were 3.4kGy, 1.3kGy, ...
A heat transfer (condenser) of a domestic freezer was tested in a vertical channel in order to study the influence of the chimney effect in the optimization of the heat transfer coefficient. The variation of the opening of the channel, position and the heating power of the heat exchanger in the heat transfer coefficient was considered. The influence of the surface emissivity on the heat transfer by thermal radiation was studied with the heat exchanger testes without paint and with black paint. The air velocity entering the channel was measured with a hot wire anemometer. In order to evaluate the chimney effect, the heat exchanger was testes in a open ambient. This situation simulates its operational conditions when installed on the freezer system. The variables collected in the experimental procedures was gathered in the form of dimensionless parameters as Nusselt, Rayleigh, Grashof and Prandtl numbers, and dimensional parameters of the ...
This paper presents results from one of the projects developed within the general framework of the international Programme 'CORE' (Cooperation for Rehabilitation in Belarus). The overall objective of the programme is to make sustainable improvements to the living conditions of the inhabitants of the territories affected by the Chernobyl disaster. The CORE Programme is currently developed in four contaminated districts of Belarus (Bragin, Cherchersk, Slavgorod and Stolyn) in the following four areas: economic and social development; health care and surveillance; education and culture; and radiological quality. The project that is presented here refers specifically to the field of 'radiological quality' and will last until the end of 2008. The project named 'implementation of an inclusive radiation monitoring system' was launched in April 2004 in the Bragin district, which is one of the most ...
The United States Department of Energy (U.S. DOE) has recently implemented a series of strategic initiatives to address long-term radiological surveillance needs at former U.S. nuclear test sites in the Marshall Islands. The plan is to engage local atoll communities in developing shared responsibilities for implementing radiation protection monitoring programs for resettled and resettling populations in the northern Marshall Islands. Using the pooled resources of the U.S. DOE and local atoll governments, individual radiological surveillance programs have been developed in whole body counting and plutonium urinalysis in order to accurately assess radiation doses resulting from the ingestion and uptake of fallout radionuclides contained in locally grown foods. Permanent whole body counting facilities have been established at three separate locations in the Marshall Islands including Rongelap Atoll (Figure 1). These facilities are operated and ...
Radiation induced polymerization of methylmethacrylate and copolymerization of styrene-acrylonitrile mixture in mamrase Carpinus betulus was carried out by means of #gamma#-ray, under different moisture levels and additives. Under all conditions the degree of polymerization was as high as 60%. No pronounced differences were observed in the kinetics of the polymerization of MMA either with moisture content of wood nor with kind and amount of additives. At high moisture (80% RH) content the dimensional stability of wood-PMMA was increased four fold as compared with untreated wood. The hardness increased about 100% for a weight conversion of monomer of about 30 to 40%. Hardness of this wood-polymer composite is comparable to that of the best noble woods in the world. (author).
Results are presented from a numerical model of the steady-state energy transfer in molten-salt-in-tube solar cavity receivers that includes convective energy transfer at a local (spatially resolved) level. Molten salt energy absorption and gray radiative transfer between all cavity surfaces are also included. This model is applied to the Molten Salt Subsystem Component Test Experiment (MSS/CTE) cavity receiver. Results for this receiver indicate the global (entire cavity) receiver thermal efficiency is invariant within a few percent to most parameters investigated, although front surface temperatures of the nonabsorbing walls vary considerably, and are particularly sensitive to the type of convective submodel used. Absorption efficiencies indicate the effects of the cavity enclosure environment. For all conditions investigated, tube inner wall temperatures remain under 855 K, ensuring that the salt remains chemically stable.
When one uses the Coleman-Weinberg renormalization condition, the effective potential $V$ in the massless $\\phi_4^4$ theory with O(N) symmetry is completely determined by the renormalization group functions. It has been shown how the $(p+1)$ order renormalization group function fix the N$^{p}$LL order contribution to $V$. We discuss here how, in addition to fixing the N$^{p}$LL contribution to $V$, the $(p+1)$ order renormalization group functions also can be used to determine portions of the N$^{p+n}$LL contributions to $V$. When these contributions are summed to all orders, the singularity structure of \\mcv is altered. An alternate approach to fixing \\mcv in terms of the renormalization group functions is shown to eliminate dependence on the background field if spontaneous symmetry breaking occurs.
This paper consists the radiation streaming analysis of Horizontal Flux Unit (HFU) penetrations in Calandria Vault of 540 MWe PHWR. There are total 7 HFU penetrations on west wall of calandria vault. As these penetrations are in accessible area, a detailed analysis has been carried out to find the neutron and gamma dose rates around these penetrations when reactor is operating. Analysis has been carried out Using the computer code MCNP and DOT-III. Based on the predictions at HFU penetrations, shielding arrangement was recommended. Neutron and gamma dose rate higher than estimated were observed at TAPS-4. This was because of installed shield not being similar to recommended one due to site conditions. Subsequently semi-empirical calculations using measured data were carried out by MCNP to further augment the existing shield taking into consideration the space limitations at site. (author)
The #alpha# radiation dose to the lungs of people who live in buildings constructed of some granites, low density concretes, and gypsum boards is higher than for residents of most other types of dwellings due to the air-borne progeny of radon. There is evidence that sealing the interior surfaces with epoxy paint, for example, can reduce the #alpha# dose to the lung significantly without a compensating increase in whole-body exposure to the #gamma#-rays from radon progeny. Based on the incidence rates for lung cancer in uranium miners, a concentration of radon of the order of 1 to 5 pCi/l. appears to be a reasonable limit for 'lifetime' exposure indoors for 'typical' home ventilation conditions. (author).
This study is an attempt to measure the quantities of elements in a composite by irradiating that composite with #gamma#-rays of various energies and detecting the transmitted radiation through the composite. A previous knowledge of the number of the elements and their attenuation coefficients is required. The quantities are calculated by solving the matrix of a linear system of equations. A computer program was developed to select the best combinations of the available energies. Five criteria were established to determine these energy combinations: (i) the determinant of the attenuation coefficient matrix; (ii) the condition number, (iii) the number of times the solution of the matrix leads to acceptable results; (iv) the indicator, (a new concept); (v) the standard deviations of the results. The intended application of this technique in medicine is to measure the bone mineral content of the skeleton. An examination of the error propagation, ...
Two dogs were given 3.0 mCi/kg body weight of "1"0"6Ru-"1"0"6Rh and two were given 4.0 mCi/kg. At 5 days after treatment, one dog from each dose level was colectomized. The dog given the larger dose but not surgically treated was killed in extremis due to acute lower bowel injury at 18 days. The other dog, given 3.0 mCi/kg but not surgically treated, was killed in a moribund condition at 145 days after dosing. The rectum had perforated. The colectomized dogs recovered from intestinal injury and showed no radiation damage at the termination of the study.
Monte Carlo calculations of proton irradiation of permanent magnets for the TRADE experiment have been performed. An irradiation dose of about 4´106 Gy/yr/mA has been estimated due to beam losses in normal operating conditions. Existing experimental results indicate that this irradiation level may induce a considerable demagnetization: in fact, a dose of 6´107 Gy induces a remanence loss of 0.3 % on samples of Sm2Co17 magnets, which are the most resistant type. More detailed calculations with the final design of the magnets and of the beam line are suggested, to determine if the irradiation levels allowed a reliable operation of the permanent magnets for the entire duration of the TRADE experiment. Damage and gas production rates have also been calculated; the values obtained are very low, thus confirming that the demagnetization process is in great part reversible.
This Final Report documents the research accomplishments achieved in the first phase of operations of a new Advanced Photon Source beam line (7-ID MHATT-CAT) dedicated to real-time x-ray studies. The period covered by this report covers the establishment of a world-class facility for time-dependent x-ray studies of materials. During this period many new and innovative research programs were initiated at Sector 7 with support of this grant, most notably using a combination of ultrafast lasers and pulsed synchrotron radiation. This work initiated a new frontier of materials research: namely, the study of the dynamics of materials under extreme conditions of high intensity impulsive laser irradiation.
The latent heat of evapotranspiration (ET) plays an important role in the assessment of drought severity as one sensitive indicator of land drought status. A simple and accurate method of estimating global ET for the monitoring of global land surface droughts from remote sensing data is essential. The objective of this research is to develop a hybrid ET model by introducing empirical coefficients based on a simple linear two-source land ET model, and to then use this model to calculate the Evaporative Drought Index (EDI) based on the actual estimated ET and the potential ET in order to characterize global surface drought conditions. This is done using the Global Energy and Water Cycle Experiment (GEWEX) Surface Radiation Budget (SRB) products, AVHRR-NDVI products from the Global Inventory ...
The condition for obtaining a calorimetric response linear with energy for hadronic showers and an energy resolution that improves as the incident energy increases is the equalization of the electromagnetic (e) and the hadronic (#pi#) signal responses. This equalization is obtained by exploiting a local hardening effect realized through the insertion of low-Z thin plates between the high-Z absorbers and the active material in a hadronic calorimeter with silicon readout. This effect, which allows the reduction of the calorimeter response to the electromagnetic component of the incoming hadronic showers, has been investigated for different low-Z materials. The relevance of some aspects of this study to the radiation hardness of the calorimeters is also addressed. (orig.).
Studies of the adsorption of oxides of sulfur and nitrogen, and their coadsorption, on black carbon in the form of n-hexane soot have been carried out by microgravimetry, EPR and FTIR spectroscopy over a wide range of experimental conditions. The mechanisms of adsorption of O{sub 2} and NO{sub 2} are entirely different, as reflected by adsorption isotherms, the behavior of carbon`s unpaired electrons, the spectral features of surface species formed, mass changes during adsorption-desorption cycles, and an essential lack of competition for surface sites. Significant effects of temperature, water, SO{sub 2} and NO{sub 2} concentration, O{sub 2}, simulated solar radiation, and the presence of trace metals, have been observed and interpreted.
A passive dosemeter, based on a Makrofol ED track detector covered with aluminized Mylar, enclosed in diffusion chamber, has been used for radon concentration studies. Detectors have been irradiated, using a {sup 241}Am source, at different energies and fluences in order to obtain the electrochemical etching conditions that allow the optimum registration of alpha particles having energies over 3 MeV. Thirty dosemeters have been sent to the UK National Radiation Protection Board (NRPB) Radon Environmental Chamber for calibration. The sensitivity of the dosemeter has been calculated. Several dosemeters have also been exposed in houses and dwellings in the Barcelona and Madrid areas for monitoring. Values for radon concentration in the areas under study are presented. (author).
A passive dosemeter, based on a Makrofol ED track detector covered with aluminized Mylar, enclosed in diffusion chamber, has been used for radon concentration studies. Detectors have been irradiated, using a "2"4"1Am source, at different energies and fluences in order to obtain the electrochemical etching conditions that allow the optimum registration of alpha particles having energies over 3 MeV. Thirty dosemeters have been sent to the UK National Radiation Protection Board (NRPB) Radon Environmental Chamber for calibration. The sensitivity of the dosemeter has been calculated. Several dosemeters have also been exposed in houses and dwellings in the Barcelona and Madrid areas for monitoring. Values for radon concentration in the areas under study are presented. (author).
An experiment lasting a number of hours was carried out with 6 men under standardised climate chamber conditions to find out to what extent wallpaper that reflects about 65-75% in the infra-red range by comparison with normal wallpaper that reflect only 3-5% of heat, has measurable positive effects on the thermoregulation of the human body and the human sensation of temperature. The measurements of skin temperature and heat flow intensity in the deeper areas of the body and the periphery, and metabolic heat conversion measurements (indirect calorimetry) confirm that infra-red reflection of the heat irradiated from the body lead to a measurable heat recovery on the body surface with a reduction of metabolic conversion. It was proved that it is possible to reduce the average room temperature by up to 4 K whilst maintaining the same degree of thermal comfort, which corresponds to a 20% saving in heating energy. (orig./BWI).
The risks from mining and processing of ores is reviewed on a generic basis with particular reference to some of the confusions which can arise due to lack of consistency or common logic in the use of exclusion, exemption and clearance. The difference in exclusion and exemption are challenged by comparing doses received in high background radiation areas and the doses received from a mining practice. The common principle of risk to the human species is not applied consistently. The differences between IAEA recommendations and local regulatory conditions are compared, and the use of exemption levels as clearance levels is considered. A case study on management of mine tailings is presented with special focus on the use of clearance levels. In all areas of review the interpretation of regulation is subject to confusion resulting from inconsistencies which can distort free market economics. (author).
Computer experiments imitating specimen strain on tension with constant deformation rate have been carried out. A formation possibility of atmosphere from defects around gliding dislocations (I) and a work of Frank-Read sources (II) have been accounted for. In result deformation curves until stresses do not exceed a critical shear stress were calculated. Influence of effects (I) and (II) was analyzed. It is determined that both by pass of dislocations over defect ''atmospheres'' and dislocation multiplication can cause a peak in flow stress occurrence on the deformation curves. Reasons and conditions of such peak occurrence have been studied. 12 refs.; 9 figs. (author).
With the combination of source ventilation and ceiling cooling for air-conditioning of working and recreation rooms, a ventilation system is available which fulfills the highest demands regarding thermal comfort. In order to utilize the advantages of this ventilation system with regard to air quality and thermal comfort to an optimum, the influence of the radiation exchange between cooling ceiling and walls on the flow in the room is investigated experimentally. Energy transfer from the walls to the cooled ceiling may result in an insufficient temperature of the walls compared to ambient air and in an upward flow on the wall surfaces (downward flow of) driven by gravity, which influences the flow pattern in the case of source ventilation. (orig.)
The main sources of energy that might be available in remote low populated areas of Libya are either diesel generating units or wind mills for water pumping. Several problems in the working performance of these two types of energy production may arise due to environmental conditions. Direct conversion of solar energy can replace other ways of energy delivery or production, especially in this country where the solar radiation all year is relatively high. Direct conversion of solar energy is relatively expensive, however the cost of erecting long feeders and supervising them may be much more expensive than the usage of solar systems. This paper investigates the economics associated with either solutions of energy production. A case study is given in detail to supply one of the remote areas with a population of about 250. (author)
Presented here is the calculation of radionuclide concentration in gaseous effluents from the Daya Bay Nuclear Power Plant by using the Gaussian model, based on the analysis of the radionuclides in gaseous effluents and based on the measured wind field in the area of Guangdong province in November 2005. The calculating results about the relative concentration distribution of the radionuclides in Guangdong province, especially in Daya Bay, Shengzheng, Zhuhai and Guangzhou, are obtained. These results can provide reference data for the effect of radiation on the environment of Guangdong province under normal conditions of operation of the Daya Bay Nuclear Power Plant. It can also provide reference data for monitoring possible nuclear incidents in nuclear power plants. (authors)
Bowel infarction is a rare and typical condition of the elderly; despite improvements in diagnostic imaging and vascular surgery, bowel infarction remains a major cause of acute abdomen, with mortality rates ranging 70-80%. Diagnosis on often late because clinical sings, laboratory data and radiologic findings are a specific. The authors investigated radiographic and particular CT patterns of intestinal infraction in 56 patients submitted to surgery within 12 hours of admission. We also report the CT findings of 5 of these patients who had reversible mesenteric ischemia. CT is more sensitive than radiography and does not exhibit the limitations of angiography (i.e., invasiveness, radiation exposure an complex organization. Therefore CT can presently be considered the method of choice in patients with suspected bowel infarction.
The deliveration by the Nuclear Safety Commission was commenced on the alteration in reactor installation, as it had been inquired by the Ministry of International Trade and Industry. The alteration is the additional installation of the reactor No. 2 in the Sendai Nuclear Power Station, Kyushu Electric Power Co., Inc. It is a PWR power plant with thermal output of about 2,660 MW (electric output of 890 MW), to be installed, adjoining to the reactor No. 1 of the same type and capacity under construction. In the examination by MITI, it was confirmed that the technological capabilities for its construction and operation and the radiation protection measures in power generation are both sufficient. The contents of the examination include the siting conditions, the location and construction of reactor facilities, etc. (J.P.N.).
The deliberation by the Nuclear Safety Commission was initiated on the alteration in reactor installation, as was required by the Ministry of International Trade and Industry. The alteration is the additional installation of the reactor No. 2 in the Sendai Nuclear Power Station, Kyushu Electric Power Co., Inc. It is a PWR power plant with thermal output of about 2,660 MW (electric output of 890 MW), to be installed, adjoining to the reactor No. 1 of the same type and capacity under construction. In the examination by MITI, it was confirmed that the technological capabilities for its construction and operation and the radiation protection measures in power generation are both sufficient. The contents of the examination include the siting conditions, the location and construction of reactor facilities, etc.
Objective: To develop a computerized method of internal dose estimation on radiation protection. Methods: Based on MIRD mathematic model of the organs and by means of the programming language of MS Visual Basic 6.0, a computer program of dose estimation in internal radiation was developed for radiation protection. Results: The computerized method of dose estimation for internal radiation was completed. Conclusions: This computerized method is very convenient for internal radiation dose estimation of several aspects. It can also be used in radiation accident. (authors)
Naturally occurring radionuclides are present in most material. The most common naturally occurring radionuclides in material are those of the uranium and thorium series and potassium-40. This material is commonly referred to as Naturally Occurring Radioactive Material (NORM). In some material the levels of naturally occurring radionuclides are significantly higher, to the extent that regulatory control may be required for radiation protection purposes. Regulation of NORM presents a range of new challenges for both regulators and operators. Unlike more traditional industries dealing with radionuclides, NORM industries have generally not had any radiological oversight and, for example, are not equipped for radiological monitoring. Some consumer goods containing NORM, which have not traditionally been considered as a radiological problem (such as some fertilizers), may require regulation and this may have social and economic consequences. The transport and disposal ...
To resolve the central thermal safety issue for spent fuel dry storage concrete canister design or Wolsung (CANDU) nuclear power plant unit 1, a thermal analysis method has been developed for the complicated geometry of rod bundles and the multi-dimensional and multi-mode heat transfer phenomena. The canister geometry is simplified and combined heat transfer by conduction, convection, and radiation is considered through effective heat transfer coefficients. Mean temperature distributions of the fuel bundles within the fuel basket are obtained by solving the heat transfer problem using an existing computer code HEATING5. The measured steady state temperature distribution within a mock-up of a storage basket is compared to the calculated result. Steady state and/or transient fuel temperature distributions have been calculated for various ambient conditions at the canister exterior surface.
To resolve the central thermal safety issue for spent fuel dry storage concrete canister design or Wolsung (CANDU) nuclear power plant unit 1, a thermal analysis method has been developed for the complicated geometry of rod bundles and the multi-dimensional and multi-mode heat transfer phenomena. The canister geometry is simplified and combined heat transfer by conduction, convection, and radiation is considered through effective heat transfer coefficients. Mean temperature distributions of the fuel bundles within the fuel basket are obtained by solving the heat transfer problem using an existing computer code HEATING5. The measured steady state temperature distribution within a mock-up of a storage basket is compared to the calculated result. Steady state and/or transient fuel temperature distributions have been calculated for various ambient conditions at the canister exterior surface.
The Oxycoal burner for pulverised coal combustion previously developed by the authors has been scaled up to typical power plant dimensions and a CFD study of pulverised coal combustion in a 1200 MWth oxy-firing furnace has been performed. The study revealed the importance of modelling the flue gas radiation behaviour for flue gas temperatures and wall heat transfer. This was done using a non-grey implementation of the Exponential Wide Band Model (EWBM). Typically, comparisons between air and oxy-fired furnaces point out that to obtain similar flame behaviour, the oxygen content in oxy-firing conditions should be increased until the same adiabatic flame temperature is reached. However, it was found that for these conditions, significantly increased wall heat fluxes can be the result. Furthermore, at gas temperatures comparable to air combustion, particle burnout is accelerated in oxy-firing due to the influence of ...
This study examines some radiation accidents occurred in the past. This information has been systematically assessed to get global lessons. The experience feedback shows that the most of accidents happened in certain conditions. These conditions can be distributed in four categories: 1- perception and vigilance in occupation: accidental exposure happened by lack of vigilance in details and lack of vigilance and perception; 2- procedures: accidental exposure happened following a lack of procedures or control that were not enough complete, not enough documented or not completely implemented; 3- training and understanding: accidental exposures happened because the personnel was not enough qualified and educated, did not get the general training nor the the necessary specialized training; 4- liabilities: accidental exposures happened following lacks and ambiguity in the definition of functions of the personnel and in the ...
The electrical conductivity of Vitox-alumina (99.2%), Wesgo-alumina (99.9%) and AlN (99.6%) has been measured during and after irradiation with an experimental set-up which allows fusion relevant loading conditions. All irradiations were performed in high vacuum at 450 C using a 104 MeV {alpha}-particle beam with an applied DC electric field of 100 kV/m. In the high purity Vitox-alumina the in-situ and postirradiation bulk conductivities {sigma} and {sigma}{sub 0} show the highest irradiation induced electrical breakdown ever observed. The saturation level near 4 x 10{sup -2} ({Omega}m){sup -1}, reached already after 0.015 dpa (O-sublattice), is already above the critical value necessary to avoid MHD pressure drop with 10 {mu}m coatings in flowing liquid metal coolants. Under the same conditions no radiation induced electrical degradation at all has been found in Wesgo-alumina and AlN. (orig.).
The aim of this research is to experimentally study the efficiency of a new-design plate collector used to heat air in a new desalination humidification-dehumidification process. In fact, in such processes, the air solar collectors work at unusual experimental parameters (forced convection, elevated air humidity, high solar irradiation). At these stressed experimental conditions, few published works are available in literature. Furthermore, the comparison of the efficiency of collectors running with normal air humidity content (about 10-20 g kg{sup -1}) and air of elevated humidity (20-50 g kg{sup -1}) have not been published to our knowledge. In the present investigation, a new air solar plate collector was designed and developed for its use in a desalination process. Moreover, a characterization of such collector was performed under different experimental conditions. The effect of different parameters, namely: the solar ...
A custom-built graphite-coated transmission ionization chamber is compared to the VacuDAP 2001 (VacuTec, Dresden, Germany), which has transparent conductive electrodes. A study was made of the dependence of response on x-ray tube potential for both types of chamber under identical conditions of exposure using over-table and under-table x-ray tubes. Since the calibration factor is the dose-area product of the radiation incident on the patient per chamber reading, it depends on the intrinsic response of the chamber as well as the effect of material in the beam between the x-ray tube and patient. Differences of about 20% were measured between the intrinsic and the over-table calibration factors and between the over-table and the under-table calibration factors for both chambers. The VacuDAP display is specifically calibrated for the over-table condition and would overstate the actual DAP in the under-table case. The intrinsic ...
Laser devices are currently in widespread use in particular by armed forces for different tasks. Electro-optical sensors as well as unprotected human eyes are extremely sensitive to laser radiation and can be permanently damaged from direct or reflected beams. Laser damage depends on the interaction between the laser beam and the atmosphere in which it traverses. The atmospheric conditions, including the range, terrain features, turbulence, and atmospheric particulates, may alter the laser's effect on different electro-optical devices and systems. When a laser beam passes through the atmosphere the optical turbulence affects the beam. As a result, temporal intensity fluctuations (scintillations) or spatial variations in intensity within a beam cross-section occur. Atmospheric scintillations pose a safety problem because an observer or sensor can be subjected to the risk of a localized irradiance (local focusing effect) much greater than that ...
German translation of the publication 'The evaluation of risks from radiation' published in 1965 by the International Commission on Radiological Protection. In a survey, genetic and somatic risks from radiation are presented and explained. (HP).
This book gives an overview of the entire field of radiation protection with the subject areas radioactivity, X-rays, UV radiation, laser beams and high-frequency electromagnetic fields. It deals graphically with the most important physical notions, the incidence, origin, properties and biological effects of types of radiation, administrative and practical protection measures and the code of rules governing them. Apart from fundamentals of radiation protection the emphasis on the following: natural radiation exposure, radiation exposure to radon, disaster relief plans in the environment of nuclear plant, the precautionary radiation protection system evolved after Chernobyl, radiation exposure through UV radiation devices, radio, RF communication, radar, microwave ovens and high-voltage transmission ...
The measuring series was performed from November 1991 through April 1992 in seven drinking-water conditioning plants of the Fichtel mountains area in the north-eastern part of Bavaria, and the results revealed as an annual average a dose of about 1 - 40 WLM. The area of interest is a drinking-water catchment area where the ground water and other water resources include waters particularly rich in radon content, which explains this relatively high dose range. This is why comprehensive, specific local and long-term mearurements were carried out in order to assess the occupational radiation dose in the drinking-water conditioning plants, taking as a model site the conditioning plant of the municipal utilities of Hof in Weissenstadt. These more specific measurements were performed by the Technical Inspectorates (TUeV) of Bavaria and Saxony and the isotope laboratory of Georg-August University of Goettingen ...
Heat transfer augmentation techniques (passive, active or a combination of passive and active methods) are commonly used in areas such as process industries, heating and cooling in evaporators, thermal power plants, air- conditioning equipment, refrigerators, radiators for space vehicles, automobiles, etc. Passive techniques, where inserts are used in the flow passage to augment the heat transfer rate, are advantageous compared with active techniques, because the insert manufacturing process is simple and these techniques can be easily employed in an existing heat exchanger. In design of compact heat exchangers, passive techniques of heat transfer augmentation can play an important role if a proper passive insert configuration can be selected according to the heat exchanger working condition (both flow and heat transfer conditions). In the past decade, several studies on the passive techniques of heat ...
To simulate radiation damage under a future Spallation Neutron Source (SNS) environment, irradiation experiments were conducted on a candidate 9Cr-2WVTa ferritic/martensitic steel using the Triple Ion Facility (TIF) at ORNL. Irradiation was conducted in single, dual, and triple ion beam modes using 3.5 MeV Fe{sup ++}, 360 keV He{sup +}, and 180 keV H{sup +} at 80, 200, and 350{degrees}C. These irradiations produced various defects comprising black dots, dislocation loops, line dislocations, and gas bubbles, which led to hardening. The largest increase in hardness, over 63 %, was observed after 50 dpa for triple beam irradiation conditions, revealing that both He and H are augmenting the hardening. Hardness increased less than 30 % after 30 dpa at 200{degrees}C by triple beams, compatible with neutron irradiation data from previous work which showed about a 30 % increase in yield strength after 27.2 dpa at 365{degrees}C. However, the very large ...
Etching of SiO_2 rods has been obtained with a dc torch with argon as the process gas in an air environment at atmospheric pressure; the high temperature of the plasma jet causes vaporization of the exposed area. The apparatus and torch operative parameters have been set up to obtain a depth etch rate of up to 0.6 mm min"-"1 corresponding to 0.826 g min"-"1. An enthalpy probe has been employed to monitor the plasma conditions before the thermal plasma etching process and from the experimental etch rate a surface rod temperature of T_s_u_r = 2057 K has been derived. Etching has been obtained with uniformity over the entire exposed area with peak to peak differences below 1%. The plasma to rod heat transfer has been simulated using a commercial CFD code Fluent (copyright). The model consists of a non-steady two-dimensional simulation for a compressible turbulent fluid, with an adapted grid calculation. Boundary conditions have been set out using ...
International standards and guidelines for calibrating high-dose dosimetry systems to be used in industrial radiation processing recommend that dose-rate effects on dosimeters be evaluated under conditions of use. This is important when the irradiation relies on high-current electron accelerators, which usually provide very high dose-rates. However, most dosimeter calibration facilities use low-intensity gamma radiation or low-current electron accelerators, which deliver comparatively low dose-rates. Because of issues of thermal conductivity and response, portable calorimeters cannot be practically used with high-current accelerators, where product conveyor speeds under an electron beam can exceed several meters per second and the calorimeter is not suitable for use with product handling systems. As an alternative, Monte Carlo calculations can give theoretical estimates of the absorbed dose in materials with flat or complex ...
This report documents the results of a project funded by DoD's Strategic Environmental Research and Development Program (SERDP) on the science behind development of predictive models for soot emission from gas turbine engines. Measurements of soot formation were performed in laminar flat premixed flames and turbulent non-premixed jet flames at 1 atm pressure and in turbulent liquid spray flames under representative conditions for takeoff in a gas turbine engine. The laminar flames and open jet flames used both ethylene and a prevaporized JP-8 surrogate fuel composed of n-dodecane and m-xylene. The pressurized turbulent jet flame measurements used the JP-8 surrogate fuel and compared its combustion and sooting characteristics to a world-average JP-8 fuel sample. The pressurized jet flame measurements demonstrated that the surrogate was representative of JP-8, with a somewhat higher tendency to soot formation. The premixed flame measurements revealed that ...
Austenitic 316LN alloy was ion-irradiated using the unique Triple Ion Beam Facility (TIF) at ORNL to investigate radiation damage effects relevant to spallation neutron sources. The TIF was used to simulate significant features of GeV proton irradiation effects in spallation neutron source target materials by producing displacement damage while simultaneously injecting helium and hydrogen at appropriately high gas/dpa ratios. Irradiations were carried out at 80, 200, and 350 C using 3.5 MeV Fe{sup ++}, 360 keV He{sup +}, and 180 keV H{sup +} to accumulate 50 dpa by Fe, 10,000 appm of He, and 50,000 appm of H. Irradiations were also carried out at 200 C in single and dual ion beam modes. The specific ion energies were chosen to maximize the damage and the gas accumulation at a depth of {approximately} 1 {micro}m. Variations in microstructure and hardness of irradiated specimens were studied using transmission electron microscopy (TEM) and a nanoindentation ...
The spectral characteristics of the Cherenkov radiation have been evaluated and converted to equivalent retinal irradiance from external sources. On the basis of the conversion, electron fluxes have been estimated for 2-sec recovery times from flashblindness. The electrons are assumed to have energies greater than 6 MeV and to be delivered in one or more bursts of 1 microsecond each over 1 sec. It is important to note that very little data exists on recovery times as short as 2 sec for either photopic and scotopic conditions. This situation is a direct result of the lack of definition of the critical tasks and their sensitivity to an interruption of background adaptation. The Cherenkov radiation produced within the eye by relativistic electrons can be compared to light from external sources by the relationships: 1 rad approx. = 4.6 scotopic td-sec and 1 rad approx. = 0.55 photopic td sec. Based on these conversion factors, ...
Commercial focused ion beam (FIB) systems are commonly used to image integrated circuits (ICS) after device processing, especially in failure analysis applications. FIB systems are also often employed to repair faults in metal lines for otherwise functioning ICS, and are being evaluated for applications in film deposition and nanofabrication. A problem that is often seen in FIB imaging and repair is that ICS can be damaged during the exposure process. This can result in degraded response or out-right circuit failure. Because FIB processes typically require the surface of an IC to be exposed to an intense beam of 30--50 keV Ga{sup +} ions, both charging and secondary radiation damage are potential concerns. In previous studies, both types of effects have been suggested as possible causes of device degradation, depending on the type of device examined and/or the bias conditions. Understanding the causes of this damage is important for ICS that ...
This paper explores for the first time the post-radiation-induced-graft polymerization on solid substrate using reversible addition-fragmentation transfer (RAFT) mechanism. Radiation-induced graft polymerization onto polymers is a potentially interesting technique to create easily new materials from highly resistant polymers, e.g. surface graft polymerization of acrylic acid (AA) onto poly(vinylidene difluoride) (PVDF) improves its surface properties without losing its excellent mechanical properties. As a consequence of the radical nature of the polymerization processes it is difficult to control molecular weight of grafted chains, and therefore design and standardize the properties of the final product. RAFT polymerization is a suitable method to obtain monodisperse polymers. The ability of the RAFT agents to control the polymer chain length could be an interesting approach to improve the grafted polymers obtained by ...
Full text of publication follows: Fission neutron irradiation to steels doped with isotope boron-10 is frequently conducted to study effects of the helium production on mechanical properties. The intrinsic mechanical properties of F82H steels could have been changed due to the boron doping. Recently, we reported that co-doping with boron and nitrogen to F82H (F82H+B+N) improved the mechanical properties of F82H doped only with boron. The mechanical properties of F82H+B+N are successfully comparable with the non-doped F82H before irradiation. In order to evaluate the effects of initial microstructure and helium production on radiation hardening, F82H and F82H+B+N were irradiate d Specimens used in this study were standard F82H martensitic steels, F82H steels doped with 60 mass ppm 10B and 200 ppm N (F82H+10B+N) and F82H steels doped with 60 mass ppm 11B and 200 ppm N (F82H+11B+N). Initial microstructures were changed by tempering conditions, and ...
Active galactic nuclei (AGNs) and quasars (QSOs) appear to emit roughly equal energy per decade from radio to gamma-ray energies (e.g. Ramaty and Ligenfelter 1982). This argues strongly for a nonthermal radiation mechanism (see Rees 1984). In addition, statistical studies have indicated that the spectra of these objects in the IR-UV and 2 to 50 keV x-ray band, can be fitted very well with power laws of specific indices. These spectral indices do not seem to depend on the luminosity or morphology of the objects (Rothschild et al. 1983; Malkan 1984), and any theory should account for them in a basic and model independent way. If shocks accelerate relativistic protons via the first-order Fermi mechanism (e.g. Axfor 1981), the radiating electrons can be produced as secondaries throughout the source by proton-proton (p-p) collisions and pion decay, thus eliminating Compton losses (Protheroe and Kazanas 1983). As shown by Kazanas (1984), if ...
Land surface parameterization schemes such as the Simple Biosphere Model (SiB2) have found considerable use in climate simulation models, where they provide lower boundary conditions in the form of surface sensible and latent heat fluxes. A methodology is described to apply models of this type at high resolution, using data from the Department of Energy{close_quote}s Cloud and Radiation Testbed in Oklahoma and Kansas, to determine the spatial variations of heat fluxes over the domain and to determine area-weighted flux averages for use in single-column model studies. Data from a dense array of meteorological instruments are interpolated to provide the wind, temperature, vapor pressure, radiation, and precipitation values needed by SiB2. The state of the vegetation is characterized through the use of the normalized difference vegetation index determined from satellites. The performance of the SiB2 model is evaluated by ...
In areas where radiation dose monitoring has not been performed, it is essential to use material available in the environment be able to rapidly assess doses to individuals for immediate emergency medical care or for general estimation of the radiological consequences. It was shown that certain types of telephone cards containing microchips have the potential to be used as individual radiation dosimeters in emergency situations to detect doses over 250 mGy by luminescence measurements. In order to understand the dosimetric properties of chip cards, the components obtained from INFINIEON Company at various stages of production were used for luminescence measurements. It is found that the protecting layer used above the chips so called 'globe top' is the main source of radiation induced signal in chip cards. The globe top produced by INFINIEON at that stage is found to contain SiO2 and Epoxy. In order to improve the ...
Subject to the provisions of the Radiation Protection Act, the Authority, on the advice of ...(f) in collaboration with the Radiation Protection Board, conduct an ionising radiation monitoring programme and ...or document kept under the control of the Radiation Protection Board.
Described and discussed in this paper are radiation processes and their advantages over the conventional techniques. Radiation sterilization of medical products, food irradiation, wood plastic composites, and radiation treatment of sewage and waste waters are presented. The Philippine experience in using these technologies, its problems and barriers are also given. (ELC).
This text-book (electronic book - multi-media CD-ROM) constitutes a course-book - author's collection of lectures. It consists of 13 lectures in which the reader acquaints with the basis of radiobiology: Introduction to radiobiology; Physical fundamentals of radiobiology; Radiation of cells; Modification of radiation damage of cells; Reparation of radiation damage of cells; Radiation syndromes and their modification; Radiation injury; Radiation damage of tissues; Effect of radiation on embryo and fetus; Biological effects of incorporated radionuclides; Therapy of acute irradiation sickness; Delayed consequences of irradiation; Radiation oncology and radiotherapy. This course-book may be interesting for students, post-graduate students of chemistry, biology, physics, medicine as well as for teachers, scientific workers ...
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This chapter is concerned with standards and guidances for limiting radiation exposures. It is divided into three sections, each of which has several parts. Section 1: Ionizing Radiation -- Standards and Guidances Applicable to the Public: Part A, Radiation Protection Standards; Part B, Environmental Radiation Standards; Part C, Exempt Levels of Radioactivity; Part D, Protective Action Guides for Accidents. Section 2: Ionizing Radiation -- Standards Applicable to the Workplace. Section 3: Medical and Other Standards.
On the basis of legally provided area dose measurements and time records of fluoroscopic examinations during the operation, radiation doses to medical personnel and patients are evaluated. Adequate radiation protection measures and a careful behaviour in the operating room keep the radiation exposure to the personnel below the maximum permissible exposure. Taking into account the continuous personnel radiation monitoring and medical supervision, radiation hazards in the operating room can be considered low.
The literature of radiation damage measurements on cadmium zinc telluride (CZT), cadmium telluride (CT), and mercuric iodide (HgI{sub 2}) is reviewed and in the case of CZT supplemented by new alpha particle data. CZT strip detectors exposed to intermediate energy (1.3 MeV) proton fluences exhibit increased interstrip leakage after 10{sup 10} p/cm{sup 2} and significant bulk leakage after 10{sup 12} p/cm{sup 2}. CZT exposed to 200 MeV protons shows a two-fold loss in energy resolution after a fluence of 5 {times} 10{sup 9} p/cm{sup 2} in thick (3 mm) planar devices but little effect in 2 mm devices. No energy resolution effects were noted from moderated fission spectrum of neutrons after fluences up to 10{sup 10} n/cm{sup 2}, although activation was evident. Exposures of CZT to 5 MeV alpha particle at fluences up to 1.5 {times} 10{sup 10} {alpha}/cm{sup 2} produced a near linear decrease in peak position with fluence and increases in FWHM beginning at about 7.5 ...
Full text: As you know, thin films which generate anomalous big photovoltage (APhV) , as film photo resistive structures made of the combinations of A_2B_6 respond to X-ray and #gamma#- radiations. In this work the influence of X-ray and #gamma#-radiations on the quantity of APhV in the system APhV-film-photoresistor was investigated. Earlier polycrystal films with anomalous photo voltage properties were received only on the clean and flat surface with high isolation property (R>10"1"4 #OMEGA#). We worked out the technology of receiving APhV films CdTe on the surface of the photosensitive film CdS. The main condition under which this effect may be observed is that the lining must be slant concerning to the direction of the motion of evaporated substance's molecular bunch during the growing of the film, i.e. received film must have a dendritic structure. That is why photosensitive film CdS was received with thermo vacuum ...
The current state and need for radiation protection training in Finland have been surveyed by the Radiation and Nuclear Safety Authority STUK. The survey sought to determine whether the current requirements for radiation protection training had been met, and to promote radiation protection training. Details of the scope and quality of present radiation protection training were requested from all educational institutes and organizations providing radiation protection training. The survey covered both basic and further training, special training of radiation safety officers, and supplementary training. The questionnaire was sent to 77 educational organization units, 66 per cent of which responded. Radiation workers and radiation safety officers were asked about radiation protection ...
The Anisotropic Analytical Algorithm (AAA) is a new pencil beam convolution/superposition algorithm proposed by Varian for photon dose calculations. The configuration of AAA depends on linear accelerator design and specifications. The purpose of this study was to investigate the accuracy of AAA for an Elekta SL25 linear accelerator for small fields and intensity modulated radiation therapy (IMRT) treatments in inhomogeneous media. The accuracy of AAA was evaluated in two studies. First, AAA was compared both with Monte Carlo (MC) and the measurements in an inhomogeneous phantom simulating lung equivalent tissues and bone ribs. The algorithm was tested under lateral electronic disequilibrium conditions, using small fields (2x2 cm"2). Good agreement was generally achieved for depth dose and profiles, with deviations generally below 3% in lung inhomogeneities and below 5% at interfaces. However, the effects of attenuation and scattering close to ...
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The assumed linear relationship between exposure to radiation and cancer incidence is questioned in this article. The current research data on radiation effects at the cellular level is reviewed, as are epidemiological studies of background radiation effects and health effects of populations exposed to low levels of radiation exposure via employment or medical treatments. Statistics reveal that threshold levels currently in force need to be reviewed. Some evidence of beneficial effects of low level radiation exposure effects of low level radiation exposure is also presented, and so regulations should be reviewed at an international level. (UK).
The most propagated mechanisms of stimulated radiation of electron beam such as Cherenkov one-particle and collective effects, ondulator and magnetic bremsshrahlung radiations, Doppler anomalous effect, Thompson and Raman scattering and radiation are discussed. Relation of spontaneous radiation mechanisms of individual electron and stimulated radiation effects in electron beams has been elucidated, grounds of linear electrodynamics of radiative beam instabilities are stated, and main mechanisms of their nonlinear stabilization are elucidated as well. Various simulated processes in electron beams are considered from the unique point of view using a simple mathematical apparatus and such physical laws as conservation and Newton laws.
Full text: Pigments possessing the ability to confer high solar reflectance have received considerable attention in recent years. The inorganic class of NIR reflective pigments are mainly metal oxides and are primarily employed in two applications: (i) visual camouflage and (ii) reducing heat build up. More than half of the solar radiation consists of near-infrared radiation (52%), the remaining being 43% visible light and 5% ultraviolet radiation. Over heating due to solar radiation negatively affects comfort in the built environment and contributes substantially to electrical consumption for air conditioning and release of green house gases. A pigment which has strong reflections in the NIR region (780-2500 nm) can be referred to as a 'cool' pigment. However, most of the NIR reflective inorganic pigments particularly yellow (eg. cadmium yellow, lead chromate, chrome titanate ...
This manual was written for individuals who wish to become qualified in radiation protection as an adjunct to working with sources of ionizing radiation or using radionuclides in the field of medicine. It provides the radiation user with information needed to protect himself and others and to understand and comply with governmental and institutional regulations regarding the use of radionuclides and radiation machines. It is designed for a wide spectrum of users, including physicians, research scientists, engineers, and technicians. It should be useful also to radiation safety officers, members of radiation safety committees, and others who are responsible for the proper use of radiation sources, although they may not be working with the sources directly. The presentation in this manual is designed to obviate the need for reviews of atomic ...
Abstract Satellite measurements and numerical forecast model reanalysis data are used to compute an updated estimate of the cloud radiative effect on the global multi-annual mean radiative energy budget of the atmosphere and surface. The cloud radiative cooling effect through reflection of short wave radiation dominates over the long wave heating effect, resulting in a net cooling of the climate system of - 21 Wm-2. The short wave radiative effect of cloud is primarily manifest as a reduction in the solar radiation absorbed at the surface of - 53 Wm-2. Clouds impact long wave radiation by heating the moist tropical atmosphere (up to around 40 Wm-2 for global annual means) while enhancing the radiative cooling of the atmosphere over other regions, in particular higher latitudes and sub-trop...
The book examines current experimental and clinical knowledge concerning the biological and biophysical effects of electromagnetic radiation, particularly that in the microwave range. The biophysical bases of the interaction of electromagnetic radiation with matter are reviewed with emphasis on biological systems, and the effects of radiation on critical biological systems, including the nervous, reproductive, visual and blood-forming systems are compared. Data concerning the lethal effects of nonionizing radiation is presented and characteristics of the effects of electromagnetic radiation on the whole mammalian organisms are examined. Various reactions of the neuroendocrine system to electromagnetic radiation are described, with particular attention given to the adrenal system, and the combined effects of ionizing and microwave radiation ...
The experimental device for generation of undulator radiation in terahertz wavelength region by use of undulator with ferromagnets is created. The device is based on a beam of a microtron with the energy 7.5 MeV. The radiation wavelength is 200 mu. Registered spontaneous radiation has a power 10{sup -6} W at a current of a beam 2 mA in a pulse. With the optical resonator, in a mode, the amplification of 6% is received, that in sometimes is more than the expected value. This effect is explained as a result of partial coherence of radiation.
The emission of Cerenkov radiation by tachyons has been examined by using the reduced expansions of superluminal electromagnetic fields in terms of standard helicity representation of Poincare group. It has been shown that the tachyons emit Cerenkov radiation through their coupling only with subluminal electromagnetic fields and that a charged tachyon can emit Cerenkov radiation only in the media in which it travels with a velocity lower than that of light while in the usual medium in which its velocity is more than that of light, it will never emit Cerenkov radiation.
Characteristics of the Ukrainian NSA NRI radiation facility for scientific researches and developments of industrial radiation technology are performed. Parts of the facility, design peculiarities of technical tools are described. Biological protection of the facility and radiation protection system, transport line, systems of technical provision and radiation measurements are discussed
The radiation burden of the people of the GDR in relation to biomedical radiography altogether as well as organ doses, gonad doses and genetically significant doses in detail are outlined. The concepts of radiation protection and standards of radiographic examination are demonstrated. Possibilities of influencing radiation exposure by scientifically based indication of X-ray examination, application of new and improvement of usual examination techniques are discussed with regard to quality assurance and control. Proposals concerning the reduction of radiation exposure of the GDR population are presented.
High energy muon colliders, such as the TeV-scale conceptual designs now being considered, are found to produce enough high energy neutrinos to constitute a potentially serious off-site radiation hazard in the neighbourhood of the accelerator site. A general characterization of this radiation hazard is given, followed by an order-of-magnitude calculation for the off-site annual radiation dose and a discussion of accelerator design and site selection strategies to minimize the radiation hazard.
Correlation characteristics of quantum noise on the shadow radiation image (RI) of the object under nondestructive testing are studied. Mathematical model of RI occasional distortions is derived. The model takes into account the parameters of object under testing and of radiation beam by radiation quanta flux density. The results obtained can be used as a component in the process of investigation of various radiation testing systems
Coherent oscillator radiation is considered. A comparison is made with classical particle radiation with gauss distribution. Decay probability for coherent state in spontaneous radiation is estimated. The method suggested for describing harmonic oscillator allows to separate the effect of classical field radiation from quantum description of particle state within the framework of a self-consistent quantum mechanical problem.
Silicon carbide (SiC) based electronic devices are of great importance for applications under the condition of high temperature, high power and high radiation. Schottky diodes of Palladium/SiC are good candidates for hydrogen and hydrocarbon gas sensors at elevated temperature. The detection sensibility of the diodes has been found heavily temperature dependent. In this work, the electrical and chemical properties of Pd/SiC Schottky contacts were studied by XPS and AES at different annealing temperatures. Schottky diodes were made by depositing ultra-thin palladium films onto a silicon carbide substrate. No significant change in the Schottky barrier height of the Pd/SiC contact was found in the temperature range of 300-673K. Palladium diffusion into SiC and the formation of palladium silicides were observed at room temperature and became significant at 300^oC and higher temperature. The mechanism of diffusion and reaction at the Pd/SiC ...
Phase contrast X-ray imaging has been studied intensively using X-rays from synchrotron radiation and micro-focus X-ray tubes. However, these studies have revealed the difficulty of this technique's application to practical medical imaging. We have created a phase contrast imaging technique using a molybdenum X-ray tube with a small focal spot size for mammography. We identified the radiographic conditions in phase contrast magnification mammography with a screen-film system, where edge effect due to phase contrast overcomes geometrical unsharpness caused by the 0.1 mm-focal spot of a molybdenum X-ray tube. The edge enhancement due to phase imaging was observed in an image of a plastic tube, and then geometrical configuration of the X-ray tube, the object and the screen-film system was determined for phase imaging of mammography. In order to investigate a potential for medical application of this method, we conducted evaluation of the images of ...
In this paper, the wavefunction of the universe with a tunneling boundary condition is considered in the context of the Brans-Dicke-type scalar-tensor theory with matter. The matter may be interpreted as a D-particle (or D0-brane) in string theory when the Brans-Dicke parameter {omega} is -1. We study two simple examples. The first example, the {gamma}=0 (matter) case, has a scale factor duality even if the low energy string action is coupled to matter. The universe undergoes quantum transition from super-inflationary (pre-big-bang) to deflationary (post-big-bang) phase. We calculate the transition rate by solving the Wheeler-DeWitt equation and find that it is non-vanishing. The two phases are disconnected classically. The second example is the {gamma}=1/3(radiation) case. With the help of earlier work this matter can be identified with a D0-brane in string theory. In this case, due to the absence of the scale factor duality and the ...
A series of copolymers based on the cellulose acetate/propionate-g.co-acrylic acid system has been prepared under radiation-induced control. These copolymers have been assessed for their water-retention capacity both in an unmodified state and after ''decrystallization'' or ''neutralization'' treatments. The grafting of acrylic acid onto the cellulose acetate/propionate had little effect on the water retention power of the cellulose acetate/propionate. However, improvements to the water retentivity was obtained after ''decrystallization'' procedures had been carried out on the copolymers using selected alkali metal salts with methanol as the continuous medium. The water-retentivity of the copolymers increased with increase in the extent of grafting, though the effect is less pronounced at high graft levels. Neutralization of the functional groups of the ...
One of the main objectives of the Finnish Research Programme on Climate Change (SILMU) has been to assess the possible impacts of future changes in climate due to the enhanced greenhouse effect on natural systems and human activities in Finland. In order to address this objective, it was first necessary to specify the types of climate changes to be expected in the Finnish region. Estimates of future climate are conventionally obtained using numerical models, which simulate the evolution of the future climate in response to radiative forcing due to changes in the composition of the atmosphere (i.e. of greenhouse gases and aerosols). However, there are large uncertainties in the model estimates because current knowledge and understanding of atmospheric processes remains incomplete. Since accurate predictions of climate change are not available, an alternative approach is to develop scenarios. These are plausible projections which reflect the best estimates to the ...
The improvement of the ecological conditions at waste storing reservoirs is an important task of the restoration activity at Production Association (PA) ``Mayak`` (South Urals). The radionuclides mostly {sup 90}Sr, {sup 137}Cs, and chemical pollutants deposited in the reservoir water and in the bottom sediment are very dangerous sources for the contamination of Techa River below the reservoirs and the contamination of groundwater in the surrounding formations. The spreading of radioactive contaminants has both hydrogeological and the chemical features. The thermodynamic approach used to account for physical-chemical interactions between water and the bed rocks based on Gibbs free energy minimization of multicomponent system (H-O-Ca-Mg-K-Na-S-Cl-C-Sr) permitted the authors to calculate the corresponding ionic and complex species existing in the solutions, and to characterize the processes of precipitation and dissolution. The model takes into account the input and ...
A technical review is presented of experiment activities and state of knowledge on air-borne, radiation source terms resulting from explosive sabotage attacks on spent reactor fuel subassemblies in shielded casks. Current assumptions about the behavior of irradiated fuel are largely based on a limited number of experimental results involving unirradiated, depleted uranium dioxide ''surrogate'' fuel. The behavior of irradiated nuclear fuel subjected to explosive conditions could be different from the behavior of the surrogate fuel, depending on the assumptions made by the evaluator. Available data indicate that these potential differences could result in errors, and possible orders-of-magnitude overestimates of aerosol dispersion and potential health effects from sabotage attacks. Furthermore, it is suggested that the current assumptions used in arriving at existing regulations for the transportation and ...
When chest radiographs are obtained using an anti-scatter grid in a mobile x-ray unit by Fuji Computed Radiography (FCR), right lung densities may differ from left lung densities owing to misalignment caused by an oblique x-ray beam. Such misalignment is considered to be caused by factors such as the shape of the bed and angle of the x-ray tube. Misalignment is especially frequent when exposure is carried out in the sitting position. Although a low-ratio grid has been reported to offer improvement, the misalignment is not completely eliminated. Therefore, we used a copper plate without a lattice feature instead of grid, and examined the results. The copper plate was found to have the ability of a grid to eliminate radiation scatter, and, furthermore, to offer the physical capabilities of a grid as determined by Carlin's new grid assessment method. Image quality was demonstrated through contrast manipulation to be equal to that obtained by grid use. ...
When chest radiographs are obtained using an anti-scatter grid in a mobile x-ray unit by Fuji Computed Radiography (FCR), right lung densities may differ from left lung densities owing to misalignment caused by an oblique x-ray beam. Such misalignment is considered to be caused by factors such as the shape of the bed and angle of the x-ray tube. Misalignment is especially frequent when exposure is carried out in the sitting position. Although a low-ratio grid has been reported to offer improvement, the misalignment is not completely eliminated. Therefore, we used a copper plate without a lattice feature instead of grid, and examined the results. The copper plate was found to have the ability of a grid to eliminate radiation scatter, and, furthermore, to offer the physical capabilities of a grid as determined by Carlin's new grid assessment method. Image quality was demonstrated through contrast manipulation to be equal to that obtained by grid use. Further, optimal ...
Standard Leadframes used in surface mount technology are finished with a layer of eutectic SnPb for passivation and for enhancing solder wetting during reflow. When eutectic SnPb is replaced by Pb-free solder, especially the eutectic SnCu, a large number of Sn whiskers are found on the Pb-free finish. Some of the whiskers are long enough to become shorts between the neighboring legs of the leadframe. How to suppress their growth and how to perform accelerated test of Sn whisker growth are crucial reliability issues in the electronic packaging industry. In this paper, we report the study of spontaneous Sn whisker growth at room temperature on eutectic SnCu and pure Sn finishes. Both compressive stress and surface oxide on Sn are necessary conditions for whisker growth. Structure and stress analyses by using the micro-diffraction in synchrotron radiation are reported. Cross-sectional electron microscopy, with samples prepared by focused ion beam, ...
This report presents results of the 1st regular inspection of the No.2 unit of the Sendai Nuclear Power Plant. It was carried out during the period from September 22, 1986, to December 24, 1986. The inspection covered the main unit of the nuclear reactor, facilities for the nuclear reactor cooling system, facilities for the instrumentation control system, fuel facilities, radiation control facilities, disposal facilities, nuclear reactor containment facilities, and emergency power generation system. Checking of appearance, disassemblage, leak and functions-performance of these facilities was conducted and no abnormalities were found. All operations involved in the inspection were performed under conditions within the permissible dose as specified in the applicable laws. No major modification work was carried out during the period of the regular inspection. The exposure dose measurements (total dose, average dose and maximum dose) for the ...
This report presents results of the 1st regular inspection of the No. 2 unit of the Sendai Nuclear Power Plant. It was carried out during the period from September 22, 1986, to December 24, 1986. The inspection covered the main unit of the nuclear reactor, facilities for the nuclear reactor cooling system, facilities for the instrumentation control system, fuel facilities, radiation control facilities, disposal facilities, nuclear reactor containment facilities, and emergency power generation system. Checking of appearance, disassemblage, leak and functions-performance of these facilities was conducted and no abnormalities were found. All operations involved in the inspection were performed under conditions within the permissible dose as specified in the applicable laws. No major modification work was carried out during the period of the regular inspection. The exposure dose measurements (total dose, average dose and maximum dose) for the ...
We study an exactly solvable model where an uniformly accelerated detector is linearly coupled to a massless scalar field initially in the Minkowski vacuum. Using the exact correlation functions we show that as soon as the coupling is switched on one can see information flowing from the detector to the field and propagating with the radiation into null infinity. By expressing the reduced density matrix of the detector in terms of the two-point functions, we calculate the purity function in the detector and study the evolution of quantum entanglement between the detector and the field. Only in the ultraweak coupling regime could some degree of recoherence in the detector appear at late times, but never in full restoration, as an earlier work seems to suggest. We explicitly show that under the most general conditions the detector never recovers its quantum coherence and the entanglement between the detector and the field remains large at late ...
The purpose and need for DOE to undertake the actions described in this document are to improve the efficiency of the Alternating Gradient Synchrotron (AGS) complex. Benefits would include optimization of the AGS scientific program, increased high-energy and nuclear physics experimentation, improved health and safety conditions for workers and users, reduced impact on the environment and the general public, energy conservation, decreased generation of hazardous and radioactive wastes, and completion of actions required to permit the AGS to be the injector to the Relativistic Heavy Ion Collider (RHIC)., Improved efficiency is defined as increasing the AGS`s capabilities to capture and accelerate the proton intensity transferred to the AGS from the AGS booster. Improved capture of beam intensity would reduce the beam losses which equate to lost scientific opportunity for study and increased potential for radiation doses to workers and the general ...
Low-frequency current noise and current-voltage (I-V) characteristics have been studied in InAs/GaAs self-assembled Quantum Dot Infrared Photodetectors in dark conditions and under illumination, at T = 77K and T = 5K. The noise behavior is consistent with a generation-recombination fluctuation process mainly related to thermally excited charge carriers at T = 77K. At T = 5K the current noise is consistent with a mechanism of fluctuations driven by the electric field, related to tunneling rather than emission-capture of charge carriers from the Quantum Dots. A very effective noise suppression mechanism, related to the tunneling regime, determines a decrease of fluctuation intensity as a function of the voltage. At T = 5K, an interesting behavior is observed in the current-voltage and noise power spectra for some of nominally identical QDIP structures in the presence of irradiation. Some devices indeed exhibit (i) a very high photoresponse and (ii) a 1/f-shaped noise ...
We present the results of three-dimensional hydrodynamical simulations of the final stages of inspiral in a black hole-neutron star binary, when the separation is comparable to the stellar radius. We use a Newtonian Smooth Particle Hydrodynamics (SPH) code to model the evolution of the system, and take the neutron star to be a polytrope with a soft (adiabatic index G=2 and G=5/3) equation of state and the black hole to be a Newtonian point mass. The only non-Newtonian effect we include is a gravitational radiation back reaction force, computed in the quadrupole approximation for point masses. We use irrotational binaries as initial conditions for our dynamical simulations, which are begun when the system is on the verge of initiating mass transfer and followed for approximately 23 ms. For all the cases studied we find that the star is disrupted on a dynamical time-scale, and forms a massive (the disc mass is approximately 0.2 solar masses) ...
Digital imaging techniques such as Digital Image Intensifier Radiography and Digital Storage Phosphor (Selenium) Radiography are replacing conventional film-screen radiography more and more. The aim of this development is the extension of diagnostic capabilities and the reduction of side effects such as radiation dose. Conventional film-screen radiography and digital radiography are very different ways of imaging. For digital radiography specific post-processing is the link between imaging conditions and film documentation. Optimisation of the images includes new possibilities of post-processing and a broad range for variation of the dose. Especially in fluoroscopy, dose can be reduced significantly by new technical features like pulsed fluoroscopy. For digital radiography the European guidelines on quality criteria have to be applied to projection radiography, digital subtraction radiography and to fluoroscopy. Further work should lead to a ...
Digital imaging techniques such as Digital Image Intensifier Radiography and Digital Storage Phosphor (Selenium) Radiography are replacing conventional film-screen radiography more and more. The aim of this development is the extension of diagnostic capabilities and the reduction of side effects such as radiation dose. Conventional film-screen radiography and digital radiography are very different ways of imaging. For digital radiography specific post-processing is the link between imaging conditions and film documentation. Optimisation of the images includes new possibilities of post-processing and a broad range for variation of the dose. Especially in fluoroscopy, dose can be reduced significantly by new technical features like pulsed fluoroscopy. For digital radiography the European guidelines on quality criteria have to be applied to projection radiography, digital subtraction radiography and to fluoroscopy. Further work should lead to a ...
We present the results of modeling intended to evaluate the feasibility of using neutrons from induced fission in highly enriched uranium (HEU) as a means of detecting clandestine HEU, even when it is embedded in absorbing surroundings, such as commercial cargo. We characterized radiation from induced fission in HEU, which consisted of delayed neutrons at all energies and prompt neutrons at energies above a threshold. We found that for the candidate detector and for the conditions we considered, a distinctive HEU signature should be detectable, given sufficient detector size, and should be robust over a range of cargo content. In the modeled scenario, an intense neutron source was used to induce fissions in a spherical shell of HEU. To absorb, scatter, and moderate the neutrons, we place one layer of simulated cargo between the source and target and an identical layer between the target and detector. The resulting neutrons and gamma rays are ...
Phase II collimators will complement the existing system to improve the expected high RF impedance and limited efficiency of Phase I jaws. An international collaborative effort has been launched to identify novel advanced materials responding to the very challenging requirements of the new collimators. Complex numerical calculations simulating extreme conditions and experimental tests are in progress. In parallel, an innovative modular design concept of the jaw assembly is being developed to allow fitting in alternative materials, minimizing the thermally induced deformations, withstanding accidents and accepting high radiation doses. Phase II jaw assembly is made up of a molybdenum back-stiffener ensuring high geometrical stability and a modular jaw split in threes sectors. Each sector is equipped with a high-efficiency independent cooling circuit. Beam position monitors (BPM) are embedded in the jaws to fasten setup time and improve beam ...
The release of any potential radioactive pollutant to the environment during routine operation of a Nuclear Power Plant should be the subject of appropriate controls and assessments. It is impossible to monitor directly the dose contribution of normal releases because the environmental radioactivity levels are very small but source monitoring provides a means of assessing the radiation exposure of population groups, critical groups and individual members of the public. Derived emissions limits ( DELs ) are used to quantify the relationship between releases of radioactivity and doses to public - critical groups. CNE Cernavoda DELs are based on a pathway analysis conducted for Cernavoda site specific conditions and they were computed using a compartment transfer model. Annual air and water emissions for the most significant radionuclides between 1997 and 2008 are presented in terms of doses and can be observed that population doses are far below ...
Geological, geophysical, thermal, petrophysical and hydrological data available for the East Mesa hydrothermal system that are pertinent to the construction of a computer model of the natural flow of heat and fluid mass within the system are assembled and correlated. A conceptual model of the full system is developed and a subregion selected for quantitative modeling. By invoking the Boussinesq approximation, valid for describing the natural flow of heat and mass in a liquid hydrothermal system, it is found practical to carry computer simulations far enough in time to ensure that steady-state conditions are obtained. Initial calculations for an axisymmetric model approximating the system demonstrate that the vertical formation permeability of the deep East Mesa system must be very low (k/sub v/ approx. 0.25 to 0.5 md). Since subsurface temperature and surface heat flow data exhibit major deviations from the axisymmetric approximation, exploratory three-dimensional ...
In this paper, we define, design and test a radiation tolerant autonomous monitoring tool for nuclear embedded applications. The goal of the instrumentation system was to record the values of some parameters such as dose, temperature or vibrations appearing inside the containment building of nuclear power plants. The knowledge of these parameters will be a good help for predictive maintenance of the power plant components. For the design of the monitoring tool, we rely on commercial-off-the-shelf (COTS) low power electronic components to use battery-supplied power. A large amount of components starting from discrete transistors or logic units to memories and micro-controllers was associated to define and design a prototype. We then confirm the environment conditions tolerance estimated to up to 2 kGy of total dose and 80 C for temperature by on-line irradiation experiments for individual components and functions and prototypes. Two different ...
Natural radioactive materials under certain conditions can reach hazardous radiological levels. The natural radionuclide ({sup 238}U, {sup 232}Th, {sup 40}K) contents of rock samples at various locations in the North Tushki area were investigated using gamma-spectrometric analysis. Estimates of the measured radionuclide content have been made for the absorbed dose rate of gamma radiation. The equivalent radium (R{sub eq}) and the external hazard index (H{sub ex}) which resulted from the natural radionuclides in soil are also calculated and tabulated. The studied samples have been collected from various rock exposures in the North Tushki area. The distribution of major oxides, U and Th were studied. It is found that the enrichment and depletion of the major oxides are mainly due to the effect of hydrothermal alteration, which caused mobility of some major oxides, which increases some elements and decreases others. It is important to mention that ...
Decommissioning of radiological and nuclear installations is for this century the new challenge. One of the performance criteria is the reduction of total quantities of radioactive materials (liquid or solid) arising from dismantling and decontamination of radiological and nuclear installations. In this work we present a new application of the water soluble polymers used as: - flocculation agents in treatment and conditioning process within the management of radioactive liquid materials; - strippable coatings on solid materials based on the water soluble polymers. The parameters of water soluble polymers made in our Institute by radiation processing have been analysed, namely the molecular average weight, composition, and efficiency of utilization of these polymeric materials as well as the content of ash, additives, decontamination factor, consumption per surfaces/liter, corrosion aspects, compatibility with various surfaces (of metal, ...
The molar of guinea pigs was irradiated with /sup 60/Co-..gamma.. ray for daily observations of the manifestation of disturbed tooth formation by microradiography and the time registration by tetracycline-labelling. Irradiation first injured young blast cells of the dentin in the growth phase, dental pulp cells, and cells of the enamel. The portion composed of injured cells formed a depressed ''constriction'' from the dental pulp side toward the border between the enamel and dentin. The cells of the enamel injured by irradiation in the growth phase later formed a very thin irregular stroma. In contrast, cells in the differentiation or subsequent phase at the time of irradiation and cells probably having started to grow after irradiation proceeded with formation of a normal stroma and calcification. No uniform relation was obtained between the histological staining of the organic stroma of normal or abnormal dentin and calcification. Labelling with ...
A joint US/Russia program is being conducted to develop, fabricate, launch, and operate a solar dynamic demonstration system on Space Station Mir. The goal of the program is to demonstrate and confirm that solar dynamic power systems are viable for future space applications such as the International Space Station Alpha. The major components of the system include a heat receiver, a closed Brayton cycle power conversion unit, a power conditioning and control unit, a concentrator, a radiator, a thermal control system, and a Space Shuttle carrier. This paper discusses the design of the heat receiver component. The receiver comprises a cylindrical cavity, the walls of which are lined with a series of tubes running the length of the cavity. The engine working fluid, a mixture of xenon and helium, is heated by the concentrated sunlight incident on these tubes. The receiver incorporates integral thermal storage, using a eutectic mixture of lithium ...
The thermal neutron column of the JRR-2 reactor was remodelled in order to install a medical irradiation facility. The design experience and the cource of this remodelling are presented. At first, the thermal neutron flux was lower than expected, and the expected radiationcondition was achieved by the following improvements: (1) removal of graphite from the thermal neutron column to increase the neutron flux, (2) twice increase of bismuth shielding and the shift of its position to improve the shielding effect against gamma ray, (3) application of B{sub 4}C rubber on the both surfaces of the shielding door to suppress the secondary gamma ray generation from the structural materials, (4) LiF tiles are applied on the inner face of the neutron beam exit hole to suppress the secondary gamma ray from the beam exit, and (5) installment a cone-shape polyethylene collimator to relieve the decay of thermal neutron. After the improvements, medical ...
We have developed a compact terahertz (THz) free electron laser (FEL). The FEL operates in the wavelength range of 100-1200 #mu#m, which corresponds to 0.3-3 THz. THz radiation from the FEL shows much higher power of 100 W compared to the power level, <100 mW, of the table-top sources by conventional lasers. The THz FEL beam shows good performance in pulse-energy stability, polarization, spectrum and spatial distribution. The main application of the FEL is THz imaging for bio-medical researches. We demonstrated the THz imaging of bugs for living condition at 3 THz. The bugs were died just before experiments, so they were not dried. We could get transmitted information through the samples by using the THz FEL beam. In this paper, we will estimate and discuss the required power level of the THz source for the practical application of the imaging.
The aim of this paper is offering a critical review of Calibration-Free Laser-Induced Breakdown Spectroscopy (CF-LIBS), the approach of multi-elemental quantitative analysis of LIBS spectra, based on the measurement of line intensities and plasma properties (plasma electron density and temperature) and on the assumption of a Boltzmann population of excited levels, which does not require the use of calibration curves or matrix-matched standards. The first part of this review focuses on the applications of the CF-LIBS method. Quantitative results reported in the literature, obtained in the analysis of various materials and in a wide range of experimental conditions, are summarized, with a special emphasis on the departure from nominal composition values. The second part is a discussion of the simplifying assumptions which lie at the basis of the CF-LIBS algorithm (stoichiometric ablation and complete atomization, thermal equilibrium, homogeneous plasma, thin ...
The aim of this paper is offering a critical review of Calibration-Free Laser-Induced Breakdown Spectroscopy (CF-LIBS), the approach of multi-elemental quantitative analysis of LIBS spectra, based on the measurement of line intensities and plasma properties (plasma electron density and temperature) and on the assumption of a Boltzmann population of excited levels, which does not require the use of calibration curves or matrix-matched standards. The first part of this review focuses on the applications of the CF-LIBS method. Quantitative results reported in the literature, obtained in the analysis of various materials and in a wide range of experimental conditions, are summarized, with a special emphasis on the departure from nominal composition values. The second part is a discussion of the simplifying assumptions which lie at the basis of the CF-LIBS algorithm (stoichiometric ablation and complete atomization, thermal equilibrium, homogeneous plasma, thin ...
The atmosphere and the biosphere are inherently coupled to one another. Atmospheric surface state variables such as temperature, winds, water vapor, precipitation, and radiation control biophysical, biogeochemical, and ecological processes at the surface and subsurface. At the same time, surface fluxes of momentum, moisture, heat, and trace gases act as time-dependent boundary conditions providing feedback on atmospheric processes. To understand such phenomena, a coupled set of interactive models is required. Costs are still prohibitive for computing surface/subsurface fluxes directly for medium-resolution atmospheric general circulation models (AGCMs), but a technique has been developed for testing large-scale homogeneity and accessing surface parameterizations and models to reduce this computational cost and maintain accuracy. This modeling system potentially bridges the observed spatial and temporal ranges yet allows the incorporation of ...
To develop a work in an area with high radiation, it requires of a detailed knowledge of the surroundings work, a communication and effective vision, a near dosimetric control. In a work where the spaces variables and reduced accesses exist, noise that hinders the communication, defendant operative condition, radiation field and taking of decision, it is necessary to have tools that allow a total control of the environment to make opportune and effective decisions, there where the task is developed. Under this elementary concept, it was developed in the Laguna Verde Central a project that it allowed a mechanism, interactive of control in spaces complex; to see, to hear, to speak, to measure. This concept takes to the creation of an equipped system with closed circuit of television, wireless communication systems, tele dosimetry wireless systems, VHS and DVD recording equipment, uninterrupted energy units. The system ...
We revisit our original papers on the burst mode of accretion by incorporating a detailed energy balance equation into a thin-disk model for the formation and evolution of circumstellar disks around low-mass protostars. Our model includes the effect of radiative cooling, viscous and shock heating, and heating due to stellar and background irradiation. Following the collapse from the prestellar phase allows us to model the early embedded phase of disk formation and evolution. During this time, the disk is susceptible to fragmentation, depending upon the properties of the initial prestellar core. Globally, we find that higher initial core angular momentum and mass content favors more fragmentation, but higher levels of background radiation can moderate the tendency to fragment. A higher rate of mass infall onto the disk than that onto the star is a necessary but not a sufficient condition for disk fragmentation. More locally, ...
The feasibility of immobilizing simulated radioactive slurry (SRS) by alkali-activated slag---clay minerals composite cement (AASCM) was studied under the experimental conditions. The results show that the dosage of SRS and water cement ratio (W/C) have significant effect on the flowability of the mixture of AASCM and SRS. The more dosage of SRS, the lower flowability. When cement/sand ratio is 1: 1 and W/C is 0.45, the flowability of the mixture meets the case of solidification engineering and the compressive strength of the waste forms containing 20% SRS meets the needs of GB 14569.1-93. The setting time of the mixture of AASCM and SRS is highly dependent on temperature while sorts of anions have little influence on it. The application of AASCM is suitable below 20 degree C. The leaching resistance of AASCM based waste forms is superior to that of OPC based waste forms. The control of the forms to Sr2+ is stronger than that to Cs+. Silicon fume can improve ...
In-reactor testing of bolt-loaded compact tension specimens was performed in 360 C water to determine the irradiation-assisted stress corrosion cracking (IASCC) behavior of HTH Alloy X-750 and direct-aged Alloy 625. New data confirm previous results showing that high irradiation levels reduce SCC resistance in Alloy X-750. Heat-to-heat variability correlates with boron content, with low boron heats showing improved IASCC properties. Alloy 625 is resistant to IASCC, as no cracking was observed in any Alloy 625 specimens. Microstructural, microchemical and deformation studies were performed to characterize the mechanisms responsible for IASCC in Alloy X-750 and the lack of an effect in Alloy 625. The mechanisms under investigation are: boron transmutation effects, radiation-induced changes in microstructure and deformation characteristics, and radiation-induced segregation. Irradiation of Alloy X-750 caused significant strengthening and ductility ...
The transmutation of minor actinides in-reactor is one solution currently being studied for the long time management of nuclear waste. In the heterogeneous concept the radionuclides are incorporating in an inert ceramic matrix. The support material must be insensitive to radiation damage. Fission product damage is the main radiation damage source during the transmutation process and therefore it is of the utmost importance to study their effects. We irradiated spinels MgAl_2O_4 (matrix of reference) and ZnAl_2O_4 by fast ions (by example: (86)Kr of approximately 400 MeV) simulating the fission products. Under these conditions, the damage is primarily due to the electronic energy losses (Se). One of the structural features of spinel AB_2O_4 is that the two cations (A(2+) and B(3+)) can exchange their site. This phenomenon is quantified by the inversion parameter. We highlight by XRD in grazing incidence that the structural ...
This present study evaluated the effect of gamma radiation on the fungal survival in packed medicinal plants, purchased from wholesale and retail market, in different period (0 and 30 days) after the treatment. Five kind of medicinal plants (Peumus boldus, Camellia sinensis, Maytenus ilicifolia, Paullinia cupana and Cassia angustifolia), were collected from different cities of Sao Paulo State, and submitted to irradiation treatment using a 60Co source (type Gammacell 220) with doses of 5,0 kGy and 10 kGy and at dose rate of 3.0 kGy/h. Non-irradiated samples (control group) were used for fungal counts and serial dilutions from 10-1 to 10-6 of the samples were seeded in duplicates and plated using the surface culture method in Dichloran 18% Glycerol Agar (DG 18) and were counted after five days at 25 deg C. The control group revealed the presence of genera Aspergillus and Penicillium, which are known as toxigenic fungi and a few samples of control group were within ...
Some of the Indian pressurized heavy water reactors (PHWRs) which use Stellite balls in the ball and screw mechanism of the adjustor rod drive mechanism in the moderator circuit have encountered high radiation fields in the moderator system due to "6"0Co. Release of particulate Stellite is responsible for the hotspots in addition to the general uniform contamination of internal surfaces with "6"0Co. Extensive laboratory studies have shown that it is possible to dissolve these Stellite particles by adopting a three-step redox process with permanganic acid as the oxidizing agent. These investigations with inactive Stellite in powder form helped to optimize the process conditions. Permanganic acid was found to have the highest dissolution efficiency as compared to alkaline and nitric acid permanganate. The susceptibility of Stellite to corrode or dissolve was found to depend on the concentration of the permanganate, pH and temperature of the ...
A laser resonance absorption spectrometer is used to investigate the characteristics of both self and nitrogen collision broadened carbon dioxide in resonance with He--Ne laser radiation at 4.2 ..mu..m. The absorption coefficient in these broadening conditions has contributions from the R(28) to R(34) absorption lines of the ..nu../sub 3/ CO/sub 2/ spectrum. The Fletcher-Powell optimization method is used to reduce the raw absorption data and to find the best value average collision broadening coefficient and laser emission frequency for a Lorentzian line shape model of the contributing lines. Pure carbon dioxide absorption in a pressure range of from 0.0016 atm (1.25 Torr) to 0.33 atm (250 Torr) is described well by the model with an average self broadening coefficient of 0.084 +- 0.008 cm/sup -1/ atm/sup -1/ for laser frequencies located at either 2370.591 +- 0.020 cm/sup -1/ or 2371.135 +- 0.019 cm/sup -1/. Nitrogen broadened carbon dioxide ...
Simulation irradiation experiments were carried out to investigate the formation processes and contribution to hardening of radiation-induced features in low alloy steels. Medium Cu (0.12 and 0.16%) and low Cu (0.03%) A533B steels were irradiated with 3 MeV Ni ions and 5 MeV electrons, and in KUR at 290degC. Irradiated steels were examined by three-dimensional atom probe, positron annihilation, high-resolution transmission electron microscopy and hardness measurements. Electron irradiation caused almost the same hardening as KUR irradiation in medium Cu steels under almost the same dose rate and dose conditions, whereas the formation of larger, denser and more Cu enriched clusters and smaller accumulation of single vacancies were confirmed for KUR irradiation. This indicated that cascade damage provides additional cluster nucleation sites to compensate for lower free point defect production. High dose rate Ni ion irradiation produced Mn-Ni-Si ...
A new type of radiation which occurs when particles are accelerated in the field of a longitudinal wave and in a transverse magnetic field is studied. The characteristics of such spontaneous radiation are obtained, and the influence of collective effects on the radiation is analyzed. The application of the findings to the theory of free electron lasers is discussed. 8 references.
Objectives To provide direct estimates of risk of cancer after protracted low doses of ionising radiation and to strengthen the scientific basis of radiation protection standards for environmental,...Full Text Available
Forty-four patients with histologically proven Hodgkin's disease underwent initial treatment with extended-field radiation therapy. Nineteen of these patients also received combination chemotherapy....Full Text Available
Exact anatomic knowledge about the location of the gonads and the application of corresponding measures of radiation protection are the preconditions for an efficient reduction of the danger of a possible genetic damage as a result of radiation exposition during X-ray examination of the hip joint of newborns. (VJ).
Adaptive radiation therapy (ART) is the incorporation of daily images in the radiotherapy treatment process so that the treatment plan can be evaluated and modified to maximize the amount of radiation...Full Text Available
Analytical method of theoretical simulation of collective hydrodynamic instabilities of intensive flows of discrete radiators, interacting with each other only through the coherent fields of their spontaneous radiation in corresponding media was suggested...
... Top of page Testing Radiation coming from granite countertops results from natural radioactive material in the granite. Identifying the presence and concentration of radioactive elements in granite requires expensive and sophisticated portable instruments or laboratory equipment. These instruments and equipment require proper calibration, and interpretation of ...
The different radiation loads caused by natural and artificial radionuclides are compared in this paper. This examples will serve to illustrate that the problem of population exposure to radiation can only be solved in consideration of all components and to show which effects of the radiation from natural sources are of special importance in this connexion. (orig./AK).
The problem of optimizing a horn radiator of electromagnetic waves for the reflection coefficient and the coefficient of transformation of the fundamental mode into higher order modes is solved. Optimization is performed by means of selecting a combined shape of the radiator generatrices.
An optical klystron is built in the 800 MeV electron storage ring at University of Science and Technology of China for harmonic super-radiation generation. In single bunch operation mode the repetition rate of the spontaneous radiation pulses is about 4.533 MHz, and the repetition rate of the seed laser pulses is about 3 Hz, while the radiation pulse duration is 300 ps. For measuring harmonic radiation a high on/off ratio ICCD is used as an optical switch to reject spontaneous radiation pulses of high repetition rate
The document published under A/63:46 and titled report of the scientific committee of United Nations for the study of ionizing radiations effects, gives the situation of the fifty sixth session of the committee that stood at Vienna from the 10. to 18. july 2008. In the chapter 3 of this report the writers summarize the strategic planning and the working program of the scientific committee for the period 2009-2013. They note that the committee worry about the inadequate means, particularly in personnel. The priorities for the given period will be the medical exposure of patients, the radiation levels and the effects of energy production, the exposure to natural radiation sources and the improvement of the understanding of the effects of the low doses radiation exposure. (N.C.)
Nov 8, 2010 ... Ihring Mission 11, the radiation dosimetry measurement system functioned normally and provided data on the Earth's trapped radiation belts ...
Selection of the appropriate radiation quality is an important aspect of optimisation for every clinical imaging task in radiology, since it affects both image quality and patient dose. Spreadsheet...Full Text Available
drical Enclosures Using a Numerical Ray Tracing Technique. NASA. TM-I02527, 1990 . Buckley, H.: Radiation from the Interior of a Reflecting Cylinder. Philos. ...
...References | Radiation Protection | US EPA This page provides links to the reference material on EPA's Radiation Protection Web site. U.S. EPA/...OAR/ORIA/Radiation Protection Division Jump to main content. Radiation Protection Contact Us Search: All EPA This Area You are here: EPA Home ... Radiation Protection References PageName Technical Users General Public Reporters Librarians Students/Teachers PROGRAMS TOPICS REFERENCES References The Reference Section provides general material that support the ...other sections of EPA's Radiation Protection Web site. You will find links within the information to related pages throughout the Radiation Protection , EPA ...
The fundamental product of tetracycline hydrochlorine gamma radiolysis was separated in its solid state. From the results of spectroscopic studies it has been established that it is des-N,N-dimethylaminotetracycline.
... iFfficiency-en- enhanced spontaneous radiation at the free-electron- ... as enhanced spontaneous radiation at the free-electron-laser wavelength. ...
The introduction of tolerance to radiation (''radiation-hardness'') into large electronic systems is one of the major tasks to which this Handbook will be put. The practices recommended here for inculcating radiation-tolerance in equipment require advanced physical modeling techniques, precise engineering procedures, and firm assurance procedures. The degree to which these procedures should be used in an equipment project can be measured by the severity of the raw radiation environment, the desired reliability of the system, and the requirement of that project for radiation-sensitive technologies. The balance of device/circuit design versus shielding will depend on whether the radiation is highly penetrating -- as in isotope handling or military environments -- or readily attenuated, as in space. In this chapter the authors have attempted to summarize the ...
When energetic bunches of electrons traverse an undulator field, they can spontaneously emit radiation both coherently and incoherently. Although it has generally been assumed that undulator radiation is incoherent at wavelengths short compared to the longitudinal size of the electron bunch, several recent observations have proved this assumption false. Furthermore, the appearance of coherent radiation is often accompanied by a significant increase in radiated power. Here we report observations of strongly enhanced coherent spontaneous radiation together with direct measurements, using transition radiation techniques, of the electron distributions responsible for the coherent emission. We also report demonstrated enhancements in the predicted spontaneous radiated power by as much as 6x10"4 using electron bunch compression. copyright 1996 ...
... Except for isolated radiation accidents over the ensuing years, little practical experience has been gained in the treatment of thermal injuries ...
... spontaneous radiation of amplifiers within a relatively w~de range of ... pulse widths are 20-30ns, while amplified spontaneous radiation pulse ...
Thermal models are constructed and analyses are performed of aluminum-based spent nuclear fuel (Al-SNF) in interim dry storage and geologic disposal configurations. Two models are developed, referred to as the interim storage model and the codisposal waste package (WP) model. Time-dependent source terms of Al-SNF forms and the defense high-level waste (DHLW) canisters are also developed for thermal performance analysis of the geologic codisposal WP.The interim storage model is a three-dimensional conduction-convection conjugate model to investigate the natural convection cooling of a sealed dry storage canister with vertical orientation in a dry storage vault. The analysis is made for various decay heat sources (equivalent to 25 to 35 kW/m{sup 3}) using various boundary conditions around the canister wall and with backfilled nitrogen or helium gas. Based on the data obtained from the Savannah River Site experimental work and available from the literature, an ...
Fourier transform infrared spectroscopy is a simple, fast, reliable and nondestructive analytical method. By using the method developed in Clark Atlanta University, consistent and reliable infrared spectral results can be obtained. An accurate radiant energy can be calculated from these infrared spectra by using a blackbody as the calibration standards. By means of the specially-designed-and-lab-made sampling inlet and the Horiba gas analyzers, the compositions of CO{sub 2}, CO, UCH, NOx and O{sub 2} etc. from the combustion exhaust gases have been on-line accurately analyzed. The commercial natural gas IR burner performed differently in the different conditions. For the methane-air combustion, at the equivalence ratio {Phi} = 1, the IR burner produced its maximum radiation efficiency, {approximately}31.4%, and the concentration of CO{sub 2} reached its maximum value, {approximately}10.7%. In the fuel-lean region, the O{sub 2} concentration in ...
Version III of the Salix Maskiner ``Bender`` coppice harvester was used to successfully harvest 11.2 hectares of short rotation poplar and willow coppice in February 1997. On a wide range of typical UK crop and site conditions, the Swedish harvester was shown to have productivity rates ranging from 4.28 to 7.97 odt/smh. Based on a total system cost of Pound 81.26 per scheduled machine hour, the Bender III is able to produce wood chip for between Pound 10.20 and pound 18.97 per dry tonne. The variation in machine productivity is dependent on crop productivity and working method, emphasising the importance of site design in optimising system efficiency. In willow crops the wood chip produced by the Bender III contained a significant amount of material greater than 75mm in length. The bulk of the chips however, fell into the 5-45mm category with only a very limited amount of fine materials less than 5mm in length. The chips from poplar crops were more uniform with the ...
The commercial Modular High Temperature Gas-Cooled Reactor (MHTGR) achieves improved reactor safety performance and reliability by utilizing an integrated sequence of completely passive thermal storage and heat transfer mechanisms to reject decay heat in the event that all its active cooling systems fail to operate. During such events, the initial heatup transient in the core is followed by a quasi-steady state cooldown process which, if uninterrupted, can continue for several days. A buoyancy-driven natural convection cooling system called the RCCS facilitates the continuous heat removal by circulating ambient air through the reactor cavity, where it is heated and then exhausted to the outside environment. The peak thermal load on the RCCS occurs approximately at the time that the vessel reaches its highest temperature. To confirm the adequacy of the RCCS design, detailed analytical models were developed to simulate the decay heat removal process and predict the maximum vessel ...
The finite-volume based commercial CFD-code Fluent was used to simulate the reacting flow in a heavy fuel oil fired laboratory furnace. Both the standard {kappa}-{epsilon} turbulence model and the Reynolds stress model (RSM) were tested. The combustion model was based on the conserved scalar (mixture fraction) and prescribed probability density function approach. The heavy fuel oil droplet trajectories were predicted by solving the momentum equations for the droplets using the Lagrangian treatment. The soot distribution in the furnace was calculated by solving a transport equation for the soot mass fraction. Simple expressions for the soot formation and oxidation rates were employed. The radiation heat transfer equation was solved using the finite volume method. The formation of thermal NO from molecular nitrogen was modeled according to the extended Zeldovich mechanism. Fuel-based NO was modeled assuming that all the nitrogen in the fuel is released as hydrogen ...
The germination and growth of Pinus radials Don. plantlets in solid residues deriving from a Kraft pulp industry was evaluated. Plant conditions were monitored by histological studies of roots and shoot-tips, as well as by plant analyses of several essential and non essential elements. The solids employed consisted of ashes, fly-ashes, dregs, grits, primary sludge, brown stock screening rejects and various mixtures of them. Their addition, in a range of combinations to sandy/metamorphic or marine terrace/clay soils, resulted in effective and sustained growth under greenhouse conditions. Low proportions of wastes favored growth in most cases, indicating that they may act as fertilisers. In some experiments, especially in those where waste was added in proportions ranging from 50% to 60%, germination and/or development were slightly affected. Two-year old field experiments have confirmed that in spite of the high pH values, Na ion content or ...
Determination of the suitability of the site for WIPP is only the first major phase in the evaluation of the radiological impact of the repository on the public health and safety. The Environmental Evaluation Group (EEG) will continue to independently review the design of the facility, the operational procedures, the criteria for packaging and shipment of the waste, the plans, procedures and results of the WIPP experiments, emergency preparedness, adherence to EPA and pertinent NRC regulations, and other important features of the project. EEG has concluded from existing evidence that the Los Medanos site for the WIPP project has been characterized in sufficient detail to warrant confidence in the validation of the site for the permanent emplacement of approximately 6 million cubic feet of defense transuranic waste. This conclusion is based on the assumption that the maximum surface dose rate for the unshielded remote-handled transuranic waste canisters will be 100 rem/hr with a maximum ...
The diverse microenvironments of foods, changing with processing and preservation, might provide conditions that would enhance the growth of microorganisms which are the principal cause of spoilage, off-odor and unpleasant flavor in foods. Radiation is a potential process which may provide a product with far superior microbial quality for food preservation, by reduction of microbial population; elimination of food-borne pathogens; extension of shelf-life; and reduction of spoilage. The aim of irradiation at low dose level is to eliminate certain microorganisms, especially spoilage types and those of public health significance. But, the radurization dose allows the outgrowth of radioresistant bacteria. Certain strains of Moraxella-Acinetobacter (M-A) groups have been recognized as radioresistant bacteria (Welch and Maxcy, 1975), which may have gone unnoticed by food microbiologists, since these bacteria have not been associated with problems and ...
The boundary-integral equation method is well suited for the calculation of the dynamic-stiffness matrix of foundations embedded in a layered visco-elastic halfspace (or a transmitting boundary of arbitrary shape), which represents an unbounded domain. It also allows pile groups to be analyzed, taking pile-soil-pile interaction into account. The discretization of this boundary-element method is restricted to the structure-soil interface. All trial functions satisfy exactly the field equations and the radiationcondition at infinity. In the indirect boundary-element method distributed source loads of initially unknown intensities act on a source line located in the excavated part of the soil and are determined such that the prescribed boundary conditions on the structure-soil interface are satisfied in an average sense. In the two-dimensional case the variables are expanded in a Fourier integral in the wave number domain, ...
For obtaining radiation less damagable laser mirrors, a preliminary optimization of film fabrication suitable for the analysis of laser damage mechanism has been done as the first step. Here, the optimization requires not only the stable fabrication process but also the ideal film structure i.e., the amorphous and smooth film structure simultaneously, eliminating latently unwanted secondary effects such as light scattering during laser damage test. For this purpose, we adopted the ion assisted deposition (IAD) method and modified the deposition conditions for titanium and tantalum oxide films, both of which compose typical high index layers, and where SiO_2 layers are also chosen as low index layers because of their amorphous and smooth nature, in alternative multilayer laser mirrors. Surface and cross sectional film structures and film crystallinity are compared and characterized, using a high resolution SEM and a x-ray diffractometer, ...
Feasibility of using combined release of sterile males and sterile females for population suppression of Earias vittella (Fabricius) was evaluated on okra in two ways. In one study, a combined release of sterile males and sterile females was evaluated under simulated conditions in laboratory, a 10: 10: 1: 1 (sterile male: sterile female: normal female: normal male) ratio effected > 99% sterility. In the second study, in a field cage experiment, a combined release of sterile males and sterile females was evaluated using normal males and tethered normal females. In this experiment, the release of sterile males and sterile females in 10: 10: 1: 1 ratio caused complete 'shut off' of mating of normal females for first 2 days and indicated>93% reduction in the larval progeny in the next generation. The tethered females were allowed to mate only once. E. vittella females mate multiply and so with overwhelming numbers of sterile males present, most probably the next ...
The operation and safety of both fossil-fuel and nuclear power stations depend on adequate cooling of the thermal source involved. This is usually accomplished using liquid coolants that are forced through the high temperature regions by a pumping system; this fluid then transports the thermal energy to another section of the power station. However, fluids that undergo boiling during this process create vapor that can be detrimental, and influence safe operation of other system components. The behavior of this vapor, or void, as it is generated and transported through the system is critical in predicting the operational and safety performance. This study uses two advanced penetrating radiation techniques, Real Time Neutron Radiography (RTNR), and High Speed X-Ray Tomography (HS-XCT), to examine void generation and transport behavior in a flow boiling system. The geometries studied were tube side flow boiling in a cylindrical configuration, and a similar flow ...
The responses of ramets of hybrid poplar (Populus spp.) (HP) clones NE388 and NE359, and seedlings of red maple (Acer rubrum, L.) to ambient ozone (O_3) were studied during May-September of 2000 and 2001 under natural forest conditions and differing natural sunlight exposures (sun, partial shade and full shade). Ambient O_3 concentrations at the study site reached hourly peaks of 109 and 98 ppb in 2000 and 2001, respectively. Monthly 12-h average O_3 concentrations ranged from 32.3 to 52.9 ppb. Weekly 12-h average photosynthetically active radiation (PAR) within the sun, partial shade and full shade plots ranged from 200 to 750, 50 to 180, and 25 to 75 #mu#mol m"-"2 s"-"1, respectively. Ambient O_3 exposure induced visible foliar symptoms on HP NE388 and NE359 in both growing seasons, with more severe injury observed on NE388 than on NE359. Slight foliar symptoms were observed on red maple seedlings during the 2001growing season. Percentage of ...
The following topics are discussed: insertion of incorrect bases in DNA; ability of DNA polymerase to copy uv-irradiated DNA; role of enzymes in repair of DNA; effects of uv radiation on molecular weight of DNA; photoreactivation; repair of DNA in Escherichia coli and xp cells following uv radiation; and synchrotron radiation studies on DNA repair. (HLW)
The book is divided into two approximately equal parts. The first four chapters are relatively lengthy and cover the basic principles of radiation biology, carcinogenesis and therapy, along with a brief introduction to radiological physics to orient the reader without background in this specialized related discipline. The remainder consists of twenty-four relatively brief chapters, each covering the radiation biology of a specific organ, tissue, or systems tissues, with emphasis on the tumorigenic and tumoricidal action of ionizing radiations.
The present state of knowledge on the influence of stray radiation on image quality and its physical description and quantification is summarized. Experimental results on the influence of physical parameters on the fraction of scattered radiation and the effect of scatter reduction by air gap technique and secondary radiation grids are committed. Open theoretical and practical problems and the limitations of common methods of scatter reduction are pointed out. (author).
Disclosed herein is a radiation detector providing for the in situ automatic sampling of fluids containing substances emitting radiation, especially Cerenkov radiation. The detector permits sampling within well casings and is self-purging such that no additional provisions must be established for the storage and disposal of contaminated fluids.
A study is made of the mechanical properties of vanadium irradiated with fast neutrons up to dose 8.6.10"-"4 dpa, as a function of the temperature of post-radiation annealing. The radiation-annealing hardening (RAH) effect is observed at 300"oC, in agreement with previous studies. It is established for the first time that RAH is accompanied by fall in ductility. A phenomenological model is described which explains the dependence of RAH on radiation dose and temperature, as well as on the content of chemically active alloying impurities. (author).
A multi-spectral Schottky barrier infrared detector array in which individual pixels of radiation from a remote radiating object are detected by two or more Schottky barrier infrared radiation detectors each having a different spectral response so as to provide a ''color'' discrimination for the array.
A multi-spectral Schottky barrier infrared detector array in which individual pixels of radiation from a remote radiating object are detected by two or more Schottky barrier infrared radiation detectors each having a different spectral response so as to provide a ''color'' discrimination for the array.
A formula is obtained which describes the kinetics of low-temperature radiation hardening caused by creation of dislocation loops of interstitial type during irradiation. The radiation hardening of aluminum and vanadium is estimated using this formula and results of experiments on studying processes of nucleation and growth of interstitial dislocation loops in these materials by transparent electron microscopy. It is shown that the proposed formula is valid for description of the kinetics of low-temperature radiation hardening.
External radiation dose exceeded 5,000 rad in three cases, and intravaginal radiation dose was 5,000 rad in one case. Radiation damage including perforation was seen in the end of ileus in one case, in the sigmoid and rectum in two cases, and in the end of ileus, sigmoid and rectum in the last case. Satisfactory results were obtained by the removal of the ileocecum in the case of the damage in the end of the ileus. However, only colostomy was performed for the damage in the sigmoid and rectum.
Due to the intensity and vast number of subjects, this Bremen experts' discussion, too, could discuss only part of the problem of the possibilitiy to quantify the radiation hazard. One preliminary result is that there is no scientific proof of the harmlessness of radiation exposure during normal operation of a nuclear power plant, either within the plant or in its vicinity. Other results are that some important questions can not be answered yet, and that there are important hints on the dangers even of low radiation doses. (GL).
In 1998, research began at Idaho National Engineering and Environmental Laboratory to investigate the application of {sup 6}Li and {sup 7}Li isotopes to the measurement of neutron and gamma radiation. Various size pairs of {sup 6}Li and {sup 7}Li based detectors were exposed to mixed neutron and gamma radiation. Experiments demonstrated that these detectors could be used to measure low level neutron radiation in the presence of high level gamma radiation. (author)
In 1998, research began at Idaho National Engineering and Environmental Laboratory to investigate the application of "6Li and "7Li isotopes to the measurement of neutron and gamma radiation. Various size pairs of "6Li and "7Li based detectors were exposed to mixed neutron and gamma radiation. Experiments demonstrated that these detectors could be used to measure low level neutron radiation in the presence of high level gamma radiation. (author)
The total radiation rate, angular distribution of the emitted energy and photon correlations of the cooperative spontaneous radiation from two atoms with different resonance frequencies and spontaneous decay rates are calculated. Contrary to the case of two identical atoms oscillations appear in the total radiation rate and the spatial distribution of the total number of emitted photons differs from the single-atom radiation pattern. The effect of the dipole-dipole near-field interaction on the time evolution of the atomic system is discussed. (author).
BackgroundTo compare two strategies of dynamic intensity modulated radiation therapy (dIMRT) with 3-dimensional conformal radiation therapy (3DCRT) in the setting of hypofractionated...Full Text Available
Results on defect structure study and degree of molybdenum radiation hardening irradiated by fission neutrons and medium energy alpha-particles are presented. It is shown that molybdenum irradiation by alpha-particles and neutrons leads to different degree of material hardening for the same damage level. It is established that molybdenum radiation hardening is mainly defined by radiation defect clusters visible in electron microscope whose coefficient of rigidity depends on their size. 5 refs.; 6 figs.; 2 tabs. (author).
We formulate a complete theory of Edge Radiation based on a novel method relying on Fourier Optics techniques. Similar types of radiation like Transition Undulator Radiation are addressed in the framework of the same formalism. Special attention is payed in discussing the validity of approximations upon which the theory is built. Our study makes consistent use of both similarity techniques and comparisons with numerical results from simulation. We discuss both near and far zone. Physical understanding of many asymptotes is discussed. Based on the solution of the field equation with a tensor Green's function technique, we also discuss an analytical model to describe the presence of a vacuum chamber. In particular, explicit calculations for a circular vacuum chamber are reported. Finally, we consider the use of Edge Radiation as a tool for electron beam diagnostics. We discuss Coherent Edge ...
The influence of a periodic electromagnetic field on the radiative corrections to the atomic energy levels is studied for the case of ''strong fields'' for which the interaction between the atom and field is of the order or greater than the radiative effects. The analysis is carried out on the basis of the Schwinger-Dirac equation for the propagation function of a bound electron in the field and on the basis of the density matrix in the Furry representation. It is shown that in the strong field approximation the radiative shifts and widths are manifest as radiative corrections to the quasi-energies. In super-high resolution experiments intensity effects in the radiative corrections to the atomic levels are obtained in the case of single-photon resonance. Some multiphoton processes are condidered by taking into account the effect of the field on ...
The stages of processes leading to radiation damage are studied, as well as, the direct and indirect mechanics of its production. The radiation effects on nucleic acid and protein macro moleculas are treated. The physical and chemical factors that modify radiosensibility are analysed, in particular the oxygen effects, the sensibilization by analogues of nitrogen bases, post-effects, chemical protection and inherent cell factors. Consideration is given to restoration processes by excision of injured fragments, the bloching of the excision restoration processes, the restoration of lesions caused by ionizing radiations and to the restoration by genetic recombination. Referring to somatic effects of radiation, the early ones and the acute syndrome of radiation are discussed. The difference of radiosensibility observed in mammalian cells and main observable alterations in tissues and ...
The atomic explosions in Hiroshima and Nagasaki made the name radiation itself become a nightmare. Notwithstanding this, radiation continued to serve the mankind specially in diagnosis of several human diseases and in the treatment of intractable malignancies. With their latest research tools biologists have now shown a significant shift in the earlier paradigm; even the concept that radiation initiates cancer appears to be no longer tenable. On the contrary, selective radiation doses inhibit growth of cancer cells and radiation in combination with many chemotherapeutic drugs, radiosensitizing chemicals and/or hyperthermia, is emerging as a new modality for cancer treatment which offers high therapeutic advantages. In addition, the deleterious effects of radiation can now be strategically counter poised by the use of many drugs and chemicals. This has been ...
Scattered radiation generated in patient and imaging system has to be considered when quality-assurance tests involve dose detection or image-quality estimations. Measurement of automatic-exposure control dose can be altered by backscattering from intensifying screens of more than 10% and the equipment transmission factor can be overestimated up to a factor of 10 when only primary radiation is used. The sensitivity of intensifying screens depends on the angle of incidence of the radiation and so primary and scattered radiation are detected differently. The quality-control aspects of anti-scatter grids are discussed. (author).
Scattered radiation generated in patient and imaging system has to be considered when quality-assurance tests involve dose detection or image-quality estimations. Measurement of automatic-exposure control dose can be altered by backscattering from intensifying screens of more than 10% and the equipment transmission factor can be overestimated up to a factor of 10 when only primary radiation is used. The sensitivity of intensifying screens depends on the angle of incidence of the radiation and so primary and scattered radiation are detected differently. The quality-control aspects of anti-scatter grids are discussed. (author).
The emission of Cerenkov radiation by tachyons has been examined by using the reduced expansions of superluminal electromagnetic fields in terms of standard helicity representation of Poincare group. It has been shown that the tachyons emit Cerenkov radiation through their coupling only with subluminal electromagnetic fields and that a charged tachyon can emit Cerenkov radiation only in the media in which it travels with a velocity lower than that of light while in the usual medium in which its velocity is more than that of light, it will never emit Cerenkov radiation. (author).
The authors give a survey of the somatic radiation risk in X-ray diagnostics. A somatic dose index is calculated for different examination methods containing the organ doses to the red bone marrow, the lung, the female breast, and the thyroid gland and evaluating their somatic significance. If this somatic dose index by which the individual radiation risk is described, is multiplied by the examination frequencies per year in the German Federal Republic, one gets the somatically significant dose index, which is a measure of the collective somatic radiation risk. In this sense, mammography has the highest, and dental radiography the lowest collective radiation risk.
The authors give a survey of the somatic radiation ris in X-ray diagnostics. A somatic dose index is calculated for different examination methods containing the organ doses to the red bone marrow, the lung, the female breast, and the thyroid gland and evaluating their somatic significance. If this somatic dose index by which the individual radiation risk is described, is multiplied by the examination frequencies per year in the German Federal Republic, one gets the somatically significant dose index, which is a measure of the collective somatic radiation risk. In this sense, mammography has the highest, and dental radiography the lowest collective radiation risk. (orig.).
The diffusion coefficient of particles in radioactive gases has been calculated with account of random wandering of aerosols (occurrence of local fields affecting the particles; recoils accompanying radiation emitted by particles, etc.). To determine the diffusion coefficient, the method of Fokker-Planck equation derivation was used. A formula is presented for calculating the radiation-stimulated diffusion coefficient. A linear growth of the diffusion coefficient with radioactivity is noted according to the formula, the diffusion coefficient is mainly determined by the field in the radiation damage region. The aerosol radioactivity may result in a more rapid deposition of aerosols in the pipelines and aerosol purification systems. The diffusion rate grows not only in the presence of intrinsic radioactivity but in case of external radiation exposure as well.
The results of theoretical and experimental investigations, describing the effect of ionizing radiation on wood and its main components and methods for production of wood-plastic composites by means of radiation-induced chemical modification are generalized. Domestic and foreign experience in their production is systematized; physico-mechanical characteristics of new material, simulation and calculation of irradiating devices, as well as calculation and experimental study of #gamma#-radiation attenuation both by wood material and by wood of different species are given. Gamma sources ("6"0Co isotope, a hot loop of a nuclear reactor) as well as electron accelerators are considered as ionizing radiation sources.
RADSOLVER is a computer program which calculates the radiation energy transport in cavity type receivers having an arbitrary number of apertures through which collimated beams of solar radiation enter. In contrast to the common assumption of gray (or semi-gray) surfaces used in the modeling of radiation transport, RADSOLVER accounts for the wavelength-dependence of emission, absorption and reflection with a band model of the radiative properties. It is intended that this report serve both as an instruction manual for the use of the RADSOLVER code and a vehicle for presenting the underlying theory. Illustrative examples along with input and output are presented.
Outage is a specific period of time for radiation protection in a nuclear power plant, in which the radiation risk and collective dose are both at the highest level. In this article, the practice and experience of occupational exposure control in the outages of Daya Bay Nuclear Power Plant are introduced through following aspects: early involvement in outage preparation by radiation protection service, control of source term, radiation protection and safety management in the outage implementation processes, the effectiveness of the plant's safety management network and overall involvement of all staffs of the plant, experience feedback and continuous improvement in radiation protection management, etc
In radiation risk assessment it must be differentiated between somatic and genetic effect on the one hand as well as between stochastic and non-stochastic effect on the other. According to definitions of the ICRP report 26 the limit for the dose equivalent of all tissues prevents non-stochastic radiation effects. With stochastic radiation effects probably exist no threshold doses; therefore the ALARA principle must be applied concerning radiation protection. The individual risk by stochastic radiation effects in its linear, linear-quadratic and quadratic extrapolations, respectively, is discussed in detail. The effective stochastic dose equivalent (H/sub eff/) as well as collective dose and collective damage are outlined.
In Korea, the Proton Engineering Frontier Project (PEFP) is building a proton linear accelerator facility with energy up to 100MeV and a beam current of 20mA. In this study, a radiation field after shutdown in the accelerator facility of the PEFP was evaluated for the purpose of the radiation shielding by using MCNPX code. A facility modeling was performed for the accelerator tunnel building, accelerator chain, target rooms and beam experiment hall. And radiation source terms were evaluated in the facility. With this facility, model and radiation source terms, the concentration of 41Ar was evaluated and the cooling time satisfying regulation in Korea was calculated.
Delayed cerebral necroses after irradiation are to be divided into hemispheric and midline lesions, as they differ from each other in several aspects. Apart from the symptoms, they are differing in the duration of latency, in the course and prognosis, and also with regard to morphology. Though there is no doubt that radiation tolerance of cerebral midline structures is relatively limited, on biological grounds, evidence of a difference between the tolerated doses could not be given from the existent inhomogeneous radiation data, with the help of the NSD-concept. Radiation planning for the region of the head, nevertheless, carefully should avoid in every case to involve the structures of the cerebral midline.
Remote-controlled handling systems are required for work to be done in the decommissioning and dismantling of nuclear facilities. These systems are equipped with electronic devices suitable for use in working environments affected by ionizing radiation. The publication explains the step-wise progress achieved for improving the radiation resistance of electronic devices with the example of a four-quadrant controlling device for the motors of a manipulator. The radiation resistance of the device could be enhanced to radiation energies of 5.500 Gy. This means that a manipulator vehicle equipped with this controlling device can take up to approx. 15 kGy all in all, taking into account its own shielding properties. (DG).
Investigations were carried out of radiation level around Daya Bay for three times since the construction and operation Daya bay Nuclear Power Station and Lingao Nuclear Power Station in Guangdong province in the period of 1988 to 2000. As shown by the investigation, the radiation levels both in the field and indoors remains unchanged by and large but slightly higher than before on the roads. Also this paper gives the analysis of variations in radiation levels form site to site and from time to time. It was shown that, for environmental ? radiation levels measurements, typical measuring sites have significant impact on the meaning results. (authors)
To date, no single passive detector has been found that measures dose equivalent from ionizing radiation exposure in low-Earth orbit. We have developed the I.S.S. Passive Dosimetry System (P.D.S.), utilizing a combination of TLD in the form of the self-contained Pille TLD system and stacks of CR-39 plastic nuclear track detector (P.N.T.D.) oriented in three mutually orthogonal directions, to measure total dose and dose equivalent aboard the International Space Station (I.S.S.). The Pille TLD system, consisting on an on board reader and a large number of Ca{sub 2}SO{sub 4}:Dy TLD cells, is used to measure absorbed dose. The Pille TLD cells are read out and annealed by the I.S.S. crew on orbit, such that dose information for any time period or condition, e.g. for E.V.A. or following a solar particle event, is immediately available. Near-tissue equivalent CR-39 P.N.T.D. provides Let spectrum, dose, and dose equivalent from charged particles of ...
The work scope of 'Biological Research for the Radiation Protection' had contained the research about ornithine decarboxylase and its controlling proteins, thioredoxin, peroxiredoxin, S-adenosymethionine decarboxylase, and glutamate decarboxylase 67KD effect on the cell death triggered ionizing radiation and H_2O_2(toxic agents). In this study, to elucidate the role of these proteins in the ionizing radiation (or H_2O_2)-induced apoptotic cell death, we utilized sensesed (or antisensed) cells, which overexpress (or down-regulate) RNAs associated with these proteins biosynthesis, and investigated the effects of these genes on the cytotoxicity caused by ionizing radiation and H_2O_2(or paraquat). We also investigated whether genisteine(or thiamine) may enhance the cytotoxic efficacy of tumor cells caused by ionizing radiation (may enhance the preventing effect ...
Spontaneous radiation emitted from relativistic electrons undergoing betatron motion in a plasma-focusing channel is analyzed, and applications to plasma wake-field accelerator experiments and to the ion-channel laser (ICL) are discussed. Important similarities and differences between a free electron laser (FEL) and an ICL are delineated. It is shown that the frequency of spontaneous radiation is a strong function of the betatron strength parameter a(beta), which plays a role similar to that of the wiggler strength parameter in a conventional FEL. For a(beta) > or approximately 1, radiation is emitted in numerous harmonics. Furthermore, a(beta) is proportional to the amplitude of the betatron orbit, which varies for every electron in the beam. The radiation spectrum emitted from an electron beam is calculated by averaging the single-electron spectrum over the electron distribution. This leads to a ...
The incidence of hilar cholangiocarcinoma is very rare worldwide. Radical resection is the only prognostic factor for long survival in patients with hilar cholangiocarcinoma. Postoperative radiation therapy can improve local control and survival rates for patients with palliative resection, but it remains controversial in patients with radical resection. Biliary drainage can effectively release bile duct obstruction for the majority of patients with locally advanced disease, and may even prolong survival when combined with radiation therapy. Radiation therapy includes extrernal beam therapy alone, external beam therapy with intraluminal brachytheapy and new radiation technique, such as three dimentional conformal therapy and intensity modulated radiation therapy. The propective randomized clinical study is needed for further investigation in the role of combined modality therapy ...
The purpose of the invention is to improve a radiation receiver, consisting of a hollow body with an opening for the entry of radiation and a ceramic absorber situated in the hollow body, which absorbs the radiation energy entering through the opening, and emits it as thermal radiation to a heat medium, so that a higher efficiency can be achieved. According to the invention, the problem is solved by the fact that the absorber consists of ceramic material on the side towards the solar radiation, which has a low emission value and a high absorption value, and that the side of the absorber towards the heat medium has ceramic material of high emission value and low absorption value. This ensures that reradiation is prevented near the opening of the hollow body, and that the solar energy entering is largely absorbed in the hollow body.
Microprocessor based ''smart'' pressure, level, and flow transmitters were tested to determine the radiation hardness of this class of electronic instrumentation for use in reactor building applications. Commercial grade Complementary Metal Oxide Semiconductor (CMOS) integrated circuits used in these transmitters were found to fail at total gamma dose levels between 2500 and 10,000 rad. This results in an unacceptably short lifetime in many reactor building radiation environments. Radiation hardened integrated circuits can, in general, provide satisfactory service life for normal reactor operations when not restricted to the extremely low power budget imposed by standard 4--20 mA two-wire instrument loops. The design of these circuits will require attention to vendor radiation hardness specifications, dose rates, process control with respect to radiation hardness factors, and ...
The invention refers a procedure of radiation dose control in irradiated tissues during electron-beam therapy. It aims at meeting the planned radiation dose for diseased tissues and taking care of the healthy ones. Therefore, the dose distribution required is determined before irradiation in consideration of such factors as energy-dependence of detector sensitivity, self-absorption within the tissue, and relative biological effectiveness. Furthermore, the expected intensity distribution of secondary quantum radiation excited in the irradiated tissue is calculated. A radiation detector for local resolution is used for registration. During irradiation the calculated intensity distribution is compared with the measured one. The invention is applicable in radiation therapy with monoenergetic electron beams.
Presented are the investigation results of electrophysical and physico-mechanical properties of KLF-20, Viksint U-4-21, Viksint KT-73, UF-7-21, KG-184, KL-4, KL-16SE-305, VIAT-1 and PPK-21 sealants, irradiated with sources of continuous and pulse #gamma#-radiation, as well as pulse #gamma#-neutron radiation. It is shown that electrophysical and physico-mechanical properties of sealants after irradiation by continuous #gamma#-radiation up to 10"6 doses and pulse gamma-neutron radiation with neutron fluence of 10"1"3 neutron/cm"2 and #gamma#-radiation dose of 10"4R do not practically change. Electric conductivity and tangent of the angle of dielectric losses increase in the process of irradiation. Electric conductivity depends on irradiation type, is proportional to dose rate and does not depend on temperature and pulse duration.
A consideration is given to the problem of selecting optimized methods of radionuclide radiation registration during the control of the objects with essential changes in thickness. Adequate model of information signal formation is developed and analyzed for the case of the existence of an inertial link of the system with the dead time of a noncontinued type. The boundary values of radiation thickness and radiation flux intensity that divide the priority of using either digital or analog registration modes are revealed. The method is found for the full correction of a systematic error of flux intensity measurement because of the dead time of the apparatus. To control the objects with essential variation of thickness the method of selective measurement of radiation intensity is proposed
Four general topics are covered in respect to the natural space radiation environment: (1) particles trapped by the earth`s magnetic field, (2) cosmic rays, (3) radiation environment inside a spacecraft, (4) laboratory radiation sources. The interaction of radiation with materials is described by ionization effects and displacement effects. Total-dose effects on MOS devices is discussed with respect to: measurement techniques, electron-hole yield, hole transport, oxide traps, interface traps, border traps, device properties, case studies and special concerns for commercial devices. Other device types considered for total-dose effects are SOI devices and nitrided oxide devices. Lastly, single event phenomena are discussed with respect to charge collection mechanisms and hard errors. (GHH)
Metal oxide semiconductor (MOS) integrated circuits, with the benefits of low power consumption, represent the state of the art technology for implantable medical devices. Three significant sources of radiation are classified as having the ability to damage or alter the behavior of implantable electronics; Secondary neutron cosmic radiation, alpha particle radiation from the device packaging and therapeutic doses(up to 70 G{gamma}) of high energy radiation used in radiation oncology. The effects of alpha particle radiation from the packaging may be eliminated by the use of polyimide or silicone rubber die coatings. The relatively low incidence of therapeutic radiation incident on an implantable device and the use of die coating leaves cosmic radiation induced secondary neutron single event upset (SEU) as the main ...
In radiation processing of food, the product often has to be prepackaged to prevent microbial recontamination during and after irradiation. The packaging material is exposed to radiation during radiation processing and radiation stability is a key consideration in the selection of packaging materials. The effects of ionizing radiation on many food packaging materials at the dose levels recommended for food precessing can be minimized by selecting appropriate radiation resistant materials. It is important to select materials in which chemicals formed as a result of the radiation treatment do not migrate and interact with the food, affecting its organoleptic and toxicological aspects. It is also important to select materials in which the physical properties are not altered to the extent they cannot resist damage during commercial production, ...
A method, system and a radiation detector system for use therein are provided for determining the depth distribution of radiation-emitting material distributed in a source medium, such as a contaminated field, without the need to take samples, such as extensive soil samples, to determine the depth distribution. The system includes a portable detector assembly with an x-ray or gamma-ray detector having a detector axis for detecting the emitted radiation. The radiation may be naturally-emitted by the material, such as gamma-ray-emitting radionuclides, or emitted when the material is struck by other radiation. The assembly also includes a hollow collimator in which the detector is positioned. The collimator causes the emitted radiation to bend toward the detector as rays parallel to the detector axis of the detector. The collimator may be a hollow cylinder ...
A series of meteorological and tracer experiments, was conducted during May and June 1984 over the 20-km wide /O/resund strait between Denmark and Sweden for the purpose of studying atmospheric dispersion processes over cold water and warm land surfaces and providing the data needed to evaluate meso-scale models in a coastal environment. In concert with these objectives the data from these experiments have been used as part of a continuing effort to evaluate the capability of the three-dimensional MATHEW/ADPIC (M/A) atmospheric dispersion models to simulate pollutant transport and diffusion characteristics of the atmospheric during a wide variety of meteorological conditions. Since previous studies have focused primarily on M/A model evaluations over rolling and complex terrain at inland sites, the /O/resund experiments provide a unique opportunity to evaluate the models in a coastal environment. The M/A models are used by the Atmospheric Release Advisory ...
To ensure safe and reliable power production nuclear power plants must be operated at high level. Non destructive in-service inspections are inseparable part of the effort. Non destructive in-service inspections are essential on the ground of degradation mechanisms existence in nuclear power components. Degradation processes are constituent of operation of each industrial installation including nuclear power plants. Mission of non-destructive testing is degradation detection, closer characterization of its parameters (dimensions) and to supply as much information as possible to nuclear power plant operator. Eddy current testing method can be assigned to surface - volumetric methods. Method enables inspection of electrically conductive materials. It is particularly suitable for inspection of non-ferromagnetic materials like austenitic stainless steel and brass. The method is used for detection of stress corrosion cracking, pitting corrosion or surface corrosion. The method experienced ...
There are two types of ionization chamber using magnetically levitated electrode: one is that by Tanaka et al. and the other, by authors'. The latter lacks the sensitivity relative to the former and thereby to solve the problem, authors made an improvement so that the electrode charge could be readout by noncontact after the leviated electrode was electrified by noncontact for an interval. This new type ionization chamber made it possible to measure the quite low dose radiation with stability and high sensitivity. Actually, the electrode was suspended by the teflon thread fixed on the steel cup levitated magnetically in the ionization chamber of which wall was covered by Al and equipped with an electrostatic charger for the electrode by noncontact. After measurement, the electrode was moved in the Faraday cage placed under the chamber to readout the voltage. For operation conditions of the apparatus, observation was done on the ...
A new diffuser/permeator design has been proposed for a new Savannah River Site tritium project. The use of a single heater well in the center of the shell had raised concerns that the Pd/Ag coils may be shielding radiative heat transfer to the walls thus reducing Pd/Ag tube temperatures near the shell below the recommended minimum operating temperature. The diffuser was fitted with thermocouples to measure shell temperatures during testing. Tests were run with the shell evacuated, helium feed flows of 0, 1000, and 2000 sccm; bleed pressures ranging from 0 to 203 kPa, and heater temperatures of 650, 675, and 700 degrees C. Hydrogen permeation tests were run with two hydrogen/helium mixtures and feed rates to simulate 1st and 2nd stage diffuser operations. Approximately 20 hours were required to bring the diffuser from ambient temperature to steady-state conditions. For tests with a heater temperature of 675 degrees C and no hydrogen flow, ...
RangerMaster{trademark} is the embedded firmware for Quantrad Sensor`s integrated nuclear instrument package, the Ranger{trademark}. The Ranger{trademark}, which is both a gamma-ray and neutron detection system, was originally developed at Los Alamos National Laboratory for in situ surveys at the Plutonium Facility to confirm the presence of nuclear materials. The new RangerMaster{trademark} software expands the library of isotopes and simplifies the operation of the instrument by providing an easy mode suitable for untrained operators. The expanded library of the Ranger{trademark} now includes medical isotopes {sup 99}Tc, {sup 201}Tl, {sup 111}In, {sup 67}Ga, {sup 133}Xe, {sup 103}Pa, and {sup 131}I; industrial isotopes {sup 241}Am, {sup 57}Co, {sup 133}Ba, {sup 137}Cs, {sup 40}K, {sup 60}Co, {sup 232}Th, {sup 226}Ra, and {sup 207}Bi; and nuclear materials {sup 235}U, {sup 238}U, {sup 233}U, and {sup 239}Pu. To accomplish isotopic identification, a simulated spectrum for each of the ...
Nuclear power in Romania was initiated on the basis of CANDU reactor type technology, an option found to fulfill the requirements for a sustainable economic development, to support the electric energy demand of the country and to ensure the population and environment protection. The construction of the Cernavoda NPP was heavily based on the Romanian industry participation and basic and applied nuclear research national resources. The experience acquired from Cernavoda NPP Unit 1 will be fructified in the construction of Units 2-5 to be built. The Romanian Ministry of Education and Research implemented a nuclear national program for research and development taking into account the European Union requirements and recommendations, the cooperation with the IAEA - Vienna and the Romanian government policy on short and medium terms in the nuclear field. The research-development program targeted: the reactor physics and nuclear fuel management; the operation safety of Cernavoda NPP Unit 1; ...
In this work tests of quality control in beams of X rays have been carried out, at diagnostic level, of two radiological services equipments of Brazilian hospitals (Aracaju, SE). We obtained the air kerma and kerma rate values, the beams efficiency, the coherence between the luminous fields and the referring fields of irradiation and half-value layer to each equipment and set of parameters. The measures of direct form have been obtained using two ionization chambers, one cylindrical and another one with parallel plates. An optional method for accomplishment some of the tests were carried out with CaSO{sub 4}:Dy + Teflon thermoluminescent dosimeters. The values of air kerma were evaluated for three tube voltage, 40, 60 and 81 kV at 1.0 m from the focus of the equipments. For each one of the voltages three distinct current values were chosen besides a fixed value of exposition time. The results showed that the values of air kerma varied between 8.0 {mu}Gy and 0.35 {mu}Gy. The T.L.D. have ...
The performance of PAN-based composite absorbers was evaluated in dynamic experiments at flow rates ranging from 25--100 bed volumes (BV) per hour. Composite absorbers with active components of ammonium molybdophosphate (AMP) PAN and K-Co ferrocyanide (KCoFC) PAN were used for separating Cs from a 1 M HNO{sub 3} + 1 M NaNO{sub 3} + 2 {times} 10{sup {minus}5} M CsCl acidic simulant solution. KCoFC-PAN and two other FC-based composite absorbers were tested for separating Cs from alkaline simulant solutions containing 0.01 M to 1 M NaOH and 1 M NaNO{sub 3} + x {times} 10{sup {minus}4} M CsCl. The efficiency of the Cs sorption on the AMP-PAN absorber from acidic simulant solutions was negatively influenced by the dissolution of the AMP active component. At flow rates of 50 BV/hr, the decontamination factor of about 10{sup 3} could be maintained for treatment of 380 BV of the feed. With the KCoFC-PAN absorber, the decontamination factor of about 10{sup 3} could be maintained for a feed ...
As an explosion develops in the collapsed core of a massive star, neutrino emission drives convection in a hot bubble of radiation, nucleons, and pairs just outside a proto-neutron star. Shortly thereafter, neutrinos drive a wind-like outflow from the neutron star. In both the convective bubble and the early wind, weak interactions temporarily cause a proton excess (Y{sub e} {approx}> 0.50) to develop in the ejected matter. This situation lasts for at least the first second, and the approximately 0.05-0.1 M{sub {circle_dot}} that is ejected has an unusual composition that may be important for nucleosynthesis. Using tracer particles to follow the conditions in a two-dimensional model of a successful supernova explosion calculated by Janka, Buras, and Rampp (2003), they determine the composition of this material. most of it is helium and {sup 56}Ni. The rest is relatively rare species produced by the decay of proton-rich isotopes unstable ...
Brachytherapy refers to short distance treatment of cancer with radiation from small, encapsulated radionuclide sources. This type of treatment is given by placing sources directly into or near the volume to be treated. The dose is then delivered continuously, either over a short period of time (temporary implants) or over the lifetime of the source to a complete decay (permanent implants). This technique is extensively used in the treatments of gynecological, breast, prostate, head and neck, and other soft tissue cancers. The clinical outcomes of this treatment depend on accurate dosimetry and dose delivery. The patient is generally considered to be water equivalent. So the treatment planning system software generally is based on measured or calculated dose distributions in homogenous water medium. In real situation, the treatment volume is not homogenous water medium, but it is a heterogeneous medium consisting of bone, soft tissue, lung, air etc. For better ...
The radiation-induced microstructural changes have been studied by cross-sectional transmission electron microscopy for single-crystal {alpha}-Al{sub 2}O{sub 3} samples irradiated with triple ion beams (0.25 MeV H{sup +}, 0.6 MeV He{sup +} and 2.4 MeV O{sup 2+}; `Triple (A)`), (0.33 MeV H{sup +}, 0.45 MeV He{sup +} and 1.3 MeV O{sup +}; `Triple (B)`) and three consecutive single ion beams (0.3 MeV H{sup +} ion followed by 0.6 MeV He{sup +} and then 0.8 MeV O{sup +} ions) at 650 C to doses in the range 0.1-8.4 dpa at the damage peak. In the specimen irradiated with Triple (A), having the same average projected range to a total peak dose of 3.7 dpa, cavities with an average diameter of 13 nm were formed between 1.2 and 1.75 {mu}m in depth causing a swelling of 0.1% at the peak, which is larger than those of the specimens irradiated with other conditions. The extent of the cavity-introduced region is some 40% smaller than observed in the damage ...
The radiation-induced microstructural changes have been studied by cross-sectional transmission electron microscopy for single-crystal #alpha#-Al_2O_3 samples irradiated with triple ion beams (0.25 MeV H"+, 0.6 MeV He"+ and 2.4 MeV O"2"+; 'Triple (A)'), (0.33 MeV H"+, 0.45 MeV He"+ and 1.3 MeV O"+; 'Triple (B)') and three consecutive single ion beams (0.3 MeV H"+ ion followed by 0.6 MeV He"+ and then 0.8 MeV O"+ ions) at 650 C to doses in the range 0.1-8.4 dpa at the damage peak. In the specimen irradiated with Triple (A), having the same average projected range to a total peak dose of 3.7 dpa, cavities with an average diameter of 13 nm were formed between 1.2 and 1.75 #mu#m in depth causing a swelling of 0.1% at the peak, which is larger than those of the specimens irradiated with other conditions. The extent of the cavity-introduced region is some 40% smaller than observed in the damage region due to the He"+ and the O"+ ions and due to the ...
The purpose of this investigation is to show that resource to anisotropic compression along a magnetic field is not a necessary condition for star formation within large collapsing interstellar gas clouds. Although such a scenario would certainly eliminate the magnetic field and angular momentum problems associated with isotropically collapsing clouds, it is believed there is sufficient observational theoretical evidence to warrant the present study of magnetically braked, isotropically collapsing gas clouds. It is not attempted to disprove the hypothesis of anisotropic compression, but to offer instead, a reasonable alternative. Angular momentum transfer from magnetically braked, cool interstellar gas clouds of 10"2, 10"3 and 10"4 times the mass of the sun is examined. Magnetic torques acting on a contracting, rotating cloud, permeated by a frozen-in magnetic field coupling the cloud to the galactic field of the surrounding interstellar medium, produce kinks in ...
This report uses experimental data to compare the performance of two sodium cooled solar central receivers operated at the International Energy Agency Small Solar Power Systems project near Almeria, Spain. Performance includes point-in-time steady state efficiency, average efficiency, start-up time, and operation time. Point-in-time steady state efficiency calculations were based on the statistical method of least squares using receiver incident and absorbed powers. One receiver, a cavity type, showed a peak steady state receiver efficiency of 87% +- 5% and an average efficiency of about 67%. The other receiver, an external ''billboard'' type, had a peak steady state receiver efficiency of 96% +- 4% and an average efficiency of about 79%. The original design peak steady state efficiency predictions for both receivers were within the experimentally determined 95% probability interval. Thermal loss test data were evaluated for the external receiver to ...
Observations are presented that link extratropical Rossby wave disturbances excited in the Southern Hemisphere subtropical jet to the initiation of convectively coupled Kelvin waves in the Pacific intertropical convergence zone (ITCZ) during austral winter. A baroclinic, zonal wavenumber 6, eastward-propagating Rossby wave train in the subtropical jet turns northeastward in the vicinity of Australia, inducing upper tropospheric divergence and vertical motion fields that spread equatorward and induce cloudiness anomalies in the Tropics. Lower tropospheric pressure surges excited from the extratropics also induce Kelvin wave-like geopotential height and temperature anomalies at the surface, providing additional lower tropospheric convergence and vertical motion forcing. The tropical outgoing longwave radiation (OLR) and circulation fields propagate eastward in tandem with the extratropical Rossby wave train at approximately 17 m s-1. Kelvin wave activity in the ...
Natural radioactive materials under certain conditions can reach hazardous radiological levels. The natural radionuclide ("2"3"8U, "2"3"2Th, "4"0K) contents of rock samples at various locations in the North Tushki area were investigated using gamma-spectrometric analysis. Estimates of the measured radionuclide content have been made for the absorbed dose rate of gamma radiation. The equivalent radium (R_e_q) and the external hazard index (H_e_x) which resulted from the natural radionuclides in soil are also calculated and tabulated. The studied samples have been collected from various rock exposures in the North Tushki area. The distribution of major oxides, U and Th were studied. It is found that the enrichment and depletion of the major oxides are mainly due to the effect of hydrothermal alteration, which caused mobility of some major oxides, which increases some elements and decreases others. It is important to mention that the study area is ...
Effect of helium and hydrogen production on radiation-hardening of F82H irradiated by dual or triple beam condition were investigated. The specimens used were four types of ferritic martensitic steels of F82H-std (Fe-8Cr-2W-0.2V-0.04Ta-0.1C) steels tempered at 750degC for 60 minutes, 20% cold worked F82H steel, F82H tempered for 10 minutes and non-tempered F82H steels. The irradiation was performed at 450degC to 50 dpa under simultaneous dual beams of 10.5 MeV Fe"3"+ and 1.05 MeV He"+ or triple beams of those and 380 keV H"+ ions. The ratios of He (appm)/dpa and H(appm)/dpa were 15 nad 15 (or 150) for dual and triple ion beams. The hardness of the irradiated specimens measured at room temperature using a micro indentation after the irradiations. The hardness in these F82H steels irradiated at 450degC to 18 dpa under triple beam irradiation was harder than that under dual beam irradiation. Irradiation softening and hardening under dual beams was ...
The proton beam has a unique advantage over the electron and photon beams in that it can give very high radiation dose to the tumor volume, while effectively sparing the neighboring healthy tissue and organs. For the clinical application of the proton beam, it is very important to confirm the location of the proton beam in the patient, preferentially during the treatment. It has been suggested that the range of the proton beam in the patient can be determined by measuring prompt gammas from the proton beam passage. Recently, a prototype prompt-gamma scanning system has been constructed and tested using experimental and therapeutic proton beams. The measurement results for the proton beams of 70 . 230 MeV showed that a clear correlation exists between the distribution of the prompt gammas and the proton beam range. The scanning method, however, is not suitable for the upcoming 'spot scanning' technique. The 'spot scanning' ...
Cytochrome c, labeled with /sup 125/I, has been used by us for staining glycosaminoglycans (GAG) separated by electrophoresis on cellulose acetate strips. As GAG between 1-10 ng could be quantified by autoradiography and densitometry, the reagent is approximately 100-fold more sensitive than currently used non-radiolabeled stains. The authors extend now the use of radiolabeled cytochrome c to the quantification of PG transblotted to solid supports subsequent to separation on polyacrylamine slab gels. Dot blotting used for exploring optimal conditions for detecting PG indicated that because of low background positively charged Nylon 66 was superior to nitrocellulose. Increasing the positive charge of the staining reagent by cationization decreased background radiation even further so that 1 ng PG could be seen readily after 5 hrs of autoradiography. Use of cationized /sup 125/I-cytochrome c has been made in detecting PG of bovine fetal ...
Our Universe is ruled by quantum mechanics and its extension quantum field theory. However, the explanations for a number of cosmological phenomena such as inflation, dark energy, symmetry breakings, and phase transitions need the presence of classical scalar fields. Although the process of condensation of scalar fields in the lab is fairly well understood, the extension of results to a cosmological context is not trivial. Here we investigate the formation of a condensate--a classical scalar field--after reheating of the Universe. We assume a light quantum scalar field produced by the decay of a heavy particle, which for simplicity is assumed to be another scalar. We show that during the radiation domination epoch under certain conditions, the decay of the heavy particle alone is sufficient for the production of a condensate. This process is very similar to preheating--the exponential particle production at the end of inflation. During the ...
A study was conducted to determine the feasibility and the opportunity of photochemical pretreatment on the biodegradation and detoxification of Methyl Tert Butyl Ether (MTBE), Ethyl Tert Butyl Ether (ETBE) and Tert Amyl Methyl Ether (TAME), the most common oxygenates used as octane enhancers in unleaded gasoline. The production, storage, uses and disposal of oxygenates result in an unknown amount of groundwater pollution. Because of their high solubility, MTBE, ETBE and TAME are detected in large portions in saturated zones of aquifers. The biodegradation of these oxygenates is difficult and slow, and information regarding their biodegradability is scarce. Photo-decomposition of oxidants under appropriate UV radiation has been shown to be very effective because the hydroxyl radicals produced possess high oxidation potential. In this study, the H{sub 2}O{sub 2}/UV process was used to generate hydroxyl radicals. Maximal oxygenates transformation was obtained in a ...
A study was conducted to determine the feasibility and the opportunity of photochemical pretreatment on the biodegradation and detoxification of Methyl Tert Butyl Ether (MTBE), Ethyl Tert Butyl Ether (ETBE) and Tert Amyl Methyl Ether (TAME), the most common oxygenates used as octane enhancers in unleaded gasoline. The production, storage, uses and disposal of oxygenates result in an unknown amount of groundwater pollution. Because of their high solubility, MTBE, ETBE and TAME are detected in large portions in saturated zones of aquifers. The biodegradation of these oxygenates is difficult and slow, and information regarding their biodegradability is scarce. Photo-decomposition of oxidants under appropriate UV radiation has been shown to be very effective because the hydroxyl radicals produced possess high oxidation potential. In this study, the H_2O_2/UV process was used to generate hydroxyl radicals. Maximal oxygenates transformation was obtained in a few minutes. ...
The most serious challenges in the design of chambers for inertial fusion energy (IFE) are 1) protecting the first wall from fusion energy pulses on the order of several hundred megajoules released in the form of x rays, target debris, and high energy neutrons, and 2) operating the chamber at a pulse repetition rate of 5-10 Hz (i.e., re-establishing, the wall protection and chamber conditions needed for beam propagation to the target between pulses). In meeting these challenges, designers have capitalized on the ability to separate the fusion burn physics from the geometry and environment of the fusion chamber. Most recent conceptual designs use gases or flowing liquids inside the chamber. Thin liquid layers of molten salt or metal and low pressure, high-Z gases can protect the first wall from x rays and target debris, while thick liquid layers have the added benefit of protecting structures from fusion neutrons thereby significantly reducing the ...
Bowel infarction is a rare and typical condition of the elderly; despite improvements in diagnostic imaging and vascular surgery, bowel infarction remains a major cause of acute abdomen, with mortality rates ranging 70-80%. Diagnosis on often late because clinical signs, laboratory data and radiologic findings are a specific. The authors investigated radiographic and particular CT patterns of intestinal infraction in 56 patients submitted to surgery within 12 hours of admission. We also report the CT findings of 5 of these patients who had reversible mesenteric ischemia. CT is more sensitive than radiography and does not exhibit the limitations of angiography (i.e., invasiveness, radiation exposure and complex organization). Therefore CT can presently be considered the method of choice in patients with suspected bowel infarction. [Italian] L'infarto intestinale rappresenta una malattia rara e tipica del soggeto anziano; nonostante il ...
As an important radioisotope in nuclear industry and other fields, americium-241 is one of the most serious contamination concerns duo to its high radiation toxicity and long half-life. In this experiment, the biosorption of "2"4"1Am from solution by a fungus, Saccharomyces cerevisiae (S. cerevisiae), and the effects of various experimental conditions on the biosorption and the mechanism were explored. The preliminary results showed that S. cerevisiae is a very efficient biosorbent. An average of more than 99% of the total "2"4"1Am could be removed by S. cerevisiae of 2.1g/L (dry weight) from "2"4"1Am solutions of 2.22MBq/L -555 MBq/L (Co). The adsorption equilibrium was achieved within 1 hour and the optimum pH ranged 1-3. The culture times of more than 16 hours were suitable and the efficient adsorption of 241Am by the S. cerevisiae could be noted. The biosorption of 241Am by the decomposed cell wall, protoplasm or cell membrane of S. ...
The somatically significant dose index can be considered as a measure for the somatic radiation risk to which the population is exposed. Figures are stated for conventional tomography of the skull and thorax. These are compared with the corresponding data for other x-ray examinations, especially computerised tomography. PMID:7134769
A brief overview if provided of selected reports presented at the International Symposium on Molecular Mechanisms of Radiation- and Chemical Carcinogen-Induced Cell Transformation held at Mackinac Island, Michigan on September 19-23, 1993.
A brief description of the physical process of dose enhancement effects produced by X-ray radiation on materials is given, with emphasis on the influence on electronic devices. The damages caused by X-ray radiation dose enhancement is more serious than that of #gamma#-ray with higher energy.
PurposeWe conducted a comparative study of Clinical Target Volume (CTV) definition of pelvic lymph nodes by multiple GU radiation oncologists looking at the levels...Full Text Available
We show that, in addition to radiation travelling at the speed of light, QED theory predicts a second type of radiation with an infinite velocity. We also show that charge, as it appears in the Dirac equation, may have a triune nature.
Terminal-differential algorithm for identification of local nonhomogeneities in items under control is developed on the basis of measurements of X-ray or gamma-radiation weakening. The algorithm may be applied by developing radiation schemes of nondestructive control, identifying inadmissible inclusions in the object under study
To capitalize on the response of tumor cells to ionizing radiation, we developed a controlled-release nanoparticle drug delivery system using a targeting peptide that recognizes a radiation-induced...Full Text Available
The somatically significant dose index can be considered as a measure for the somatic radiation risk to which the population is exposed. Figures are stated for conventional tomography of the skull and thorax. These are compared with the corresponding data for other X-ray examinations, especially computerised tomography.
The somatically significant dose index can be considered as a measure for the somatic radiation risk to which the population is exposed. Figures are stated for conventional tomography of the skull and thorax. These are compared with the corresponding data for other X-ray examinations, especially computerised tomography. (orig.).
BackgroundMicrovascular injury plays a key role in normal tissue radiation responses. Statins, in addition to their lipid-lowering effects, have vasculoprotective...Full Text Available
This paper describes a radiation shield verification survey of a large hot cell at the Fast Flux Test Facility (FFTF). The following aspects of the shield test are discussed: description of the FFTF; description of the hot cell; the test procedures; radiation protection, and the test results.
A possible receiver configuration is a cavity in which a falling sheet of solid particles is directly irradiated by the concentrated solar flux passing through the aperture. Regardless of the particular geometry, the radiative transfer within the falling particle curtain must be studied in order to determine the net radiative heating rate for the particles. A discrete ordinate radiative transfer model has been developed to predict the radiative coupling within the falling particle curtain. The model determines how much energy is absorbed by the particles, how much is transmitted to the rear wall of the receiver, and determines the effects of particle scattering and thermal emission on the net radiation absorbed by the particles. The model accounts for the directional nature of the radiation field, particle scattering, and the wavelength dependence of the optical ...
The achievements made in the field of radiation protection over the past 20 years are outlined. Risk analysis as applied to medicine is considered and genetic significant doses, genetic risks, somatic effective doses and somatic risks are discussed. (C.F.).
The in situ assembly states of the glucose transport carrier protein in the plasma membrane and in the intracellular (microsomal) storage pool of rat adipocytes were assessed by studying radiation-induced inactivation of the D-glucose-sensitive cytochalasin B binding activities. High energy radiation inactivated the glucose-sensitive cytochalasin B binding of each of these membrane preparations by reducing the total number of the binding sites without affecting the dissociation constant. The reduction in total number of binding sites was analyzed as a function of radiation dose based on target theory, from which a radiation-sensitive mass (target size) was calculated. When the plasma membranes of insulin-treated adipocytes were used, a target size of approximately 58,000 daltons was obtained. For adipocyte microsomal membranes, we obtained target sizes of approximately 112,000 and 109,000 daltons prior ...
Radiation decontamination of dry ingredients, herbs and enzyme preparations is a technically feasible, economically viable and safe physical process. The procedure is direct, simple, requires no additives and is highly efficient. Its dose requirement is moderate. Radiation doses of 3-10 kGy (0.3-1 mrad) have proved sufficient to reduce the viable counts to a satisfactory level. Ionising radiations do not cause any significant rise in temperature. The flavour, texture or other important technological or sensory properties of most ingredients are not influenced at radiation doses necessary for satisfactory decontamination, and radiation obviates the chemical residue problem. The microflora surviving radiation decontamination of dry ingredients are more susceptible to subsequent antimicrobial treatments. Recontamination can be prevented as the product can be ...
PurposeRadiation-induced heart disease (RIHD) is a severe side effect of thoracic radiotherapy. This study examined the effects of PTX and α-tocopherol on...Full Text Available
Inhibition of photosynthesis by ultraviolet-A radiation (UV-A, 315-380 nanometers) was examined in three marine angiosperms: Halophila engelmannii Aschers, Halodule wrightii...Full Text Available
Adaptive radiation is the rapid origination of multiple species from a single ancestor as the result of concurrent adaptation to disparate environments. This fundamental evolutionary process is considered...Full Text Available
An ex-employee's claims that inadequate enforcement of radiation safety regulations allowed excess radiation exposure thereby causing his deteriorating health was not substantiated by a thorough investigation.
Spontaneous radiation by an atom in a Rydberg state is inhibited by use of parallel conducting planes to eliminate the vacuum modes at the transition frequency. Spontaneous radiation emission is observed to turn off abruptly at the cutoff frequency of the waveguidelike structure, and the natural lifetime is measured to increase by a factor of at least 20.
Somatic radiation doses are recognized to be possible factors of carcinogenesis. In correctly performed mammography, however, even as screening test, the radiation dose does not reach such an order of magnitude that the benefit of the procedure as to prevention of breast cancer is called into question.
The United Kingdom Atomic Energy Authority mortality study was designed to investigate the relation between exposure to ionising radiation and mortality among the authority's employees. The present...Full Text Available
In the synthesis of the peptidyl-polymer corresponding to the sequence (57-100) of the ..beta.. chain of human hemoglobin on Teflon with radiationally grafted polystyrene a comparative study was made of different methods of fragment condensation. It was shown that the most effective methods are azide condensation and condensation with the use of complex F.
In the synthesis of the peptidyl-polymer corresponding to the sequence (57-100) of the #beta# chain of human hemoglobin on Teflon with radiationally grafted polystyrene a comparative study was made of different methods of fragment condensation. It was shown that the most effective methods are azide condensation and condensation with the use of complex F.
A method for recycling laser flashlamp radiation in selected wavelength ranges to decrease thermal loading of the solid state laser matrix while substantially maintaining the pumping efficiency of the flashlamp.
This volume presents the collations tables of a six volume comparative epidemiological survey of the effects of low level radiation dose. Data are collated for the effects observed in the following irradiated groups:- Preconception irradiation, intra-uterine irradiation, childhood irradiation, adult irradiation. (UK).
Electron spin resonance spectroscopy can provide a powerful approach to the study of radiation effects in biological materials. This memorandum gives an overview of current and future research. (author).
The risks to human health from small doses of ionizing radiation raise questions which remain largely unanswered. This paper begins by explaining the historical background to this subject; it goes on to discuss recent developments and concludes with a personal view of the dose-reponse relationship. (author).
The risks to human health from small doses of ionizing radiation raise questions which remain largely unanswered. This paper begins by explaining the historical background to this subject; it goes on to discuss recent developments and concludes with a personal view of the dose-reponse relationship. (author).
By using EPR measurements of radiation-induced radicals it is possible to utilize human fingernails to estimate radiation dose after-the-fact. One of the potentially limiting factors in this...Full Text Available
Although skin is usually exposed during human exposures to ionizing radiation, there have been no thorough examinations of the transcriptional response of skin fibroblasts and keratinocytes...Full Text Available
A compensatory response, viz. in vivo recovery from radiation damage to mitochondria, occurs in preclimacteric pear fruits (Pyrus communis L.) treated with ionizing...Full Text Available
This guidebook organizes the profusion of rules and regulations surrounding radiation protection into a single-volume reference. Employee and public protection, accident prevention, and emergency preparedness are included in this comprehensive coverage. Whenever possible, information is presented in convenient checklists, tables, or outlines that enable you to locate information quickly.
The annealing behavior of the radiation damage in epitaxial Pd_2Si and NiSi_2 films on Si, due to the implantation of 100 keV Ar ions, is investigated by using the channeling technique with "4He ions. (U.K.).
Many mechanical parts are subjected to stresses and strains that may eventually lead to their failure. In order to prevent the costly delays associated with equipment down-time, many parts have to be tested for weaknesses and defects when machinery is constructed or dismantled for maintenance. These procedures are known as Non-Destructive Testing (NDT) methods. Five types of non-destructive testing methods routinely used are radiographic testing, ultrasonic testing, magnetic particle inspection, liquid penetrant testing and eddy current testing. Out of these five techniques industrial radiography plays an important role in non-destructive testing to reveal interior defects in materials. In radiography almost two-thirds of the radiation reaching the film is scattered radiation which does not form the image of defects. Scattered radiation generated inside and outside a material has a very large effect on sensitivity of flaw ...
In many radiotherapy clinics, geometric uncertainties in the delivery of 3D conformal radiation therapy and intensity modulated radiation therapy of the prostate are reduced by aligning the...Full Text Available
The mission includes a reflected solar instrument retrieving at-sensor .... incoming solar radiation. This direct aerosol radiative forcing (DARF) ... examining the behavior of geosynchronous rocket bodies and non-stabilized payloads as ...
The chapter presents the nuclear energy development in 20th century and the most important radiation accidents happened from the point of view of technological risk and high impact consequences: Three Mile Island and Chernobyl.