1978 source book for fusion--fission hybrid systems. Executive summary

International Nuclear Information System (INIS)

Crowley, J.H.; Pavlenco, G.F.; Kaminski, R.S.

1978-12-01

The 1978 Source Book for Fusion--Fission Hybrid Systems was prepared by United Engineers and Constructors Inc. for the U.S. Department of Energy and the Electric Power Research Institute. It reviews the current status of fusion--fission hybrid reactors, and presents the prevailing views of members of the fusion community on the RD and D timetable required for the development and commercialization of fusion--fission hybrids. The results presented are based on a review of related references as well as interviews with recognized experts in the field. Contributors from the academic and industrial communities are listed

Scoping studies of 233U breeding fusion fission hybrid

International Nuclear Information System (INIS)

Maniscalco, J.A.; Hansen, L.F.; Allen, W.O.

1978-05-01

Neutronic calculations have been carried out in order to design a laser fusion driven hybrid blanket which maximizes 233 U production per unit of thermal energy (greater than or equal to 1 kg/MW/sub T/-year) with acceptable fusion energy multiplication (M/sub F/ approximately 4). Two hybrid blankets, a thorium and a uranium-thorium blanket, are discussed in detail and their performance is evaluated by incorporating them into an existing hybrid design (the LLL/Bechtel design). The overall performance of the two laser fusion driven 233 U producers is discussed and estimates are given of (1) the number of equivalent thermal power fission reactors (LWR, HWR, SSCR and HTGR) that these fusion breeders can fuel, (2) their capital cost, and (3) the cost of electricity in the combined fusion breder-converter reactor scenario

Scoping studies of 233U breeding fusion fission hybrid

International Nuclear Information System (INIS)

Maniscalco, J.A.; Hansen, L.F.; Allen, W.O.

1978-01-01

Neutronic calculations have been carried out in order to design a laser fusion driven hybrid blanket which maximizes 233 U production per unit of thermal energy (greater than or equal to 1 kg/MW/sub T/-year) with acceptable fusion energy multiplication (M/sub F/ approx. 4). Two hybrid blankets, a thorium and a uranium--thorium blanket, are discussed in detail and their performance is evaluated by incorporating them into an existing hybrid design (the LLL/Bechtel design). The overall performance of the two laser fusion driven 233 U producers is discussed and estimates are given of (1) the number of equivalent thermal power fission reactors (LWR, HWR, SSCR and HTGR) that these fusion breeders can fuel, (2) their capital cost, and (3) the cost of electricity in the combined fusion breeder-converter reactor scenario

Advanced nuclear fuel production by using fission-fusion hybrid reactor

International Nuclear Information System (INIS)

Al-Kusayer, T.A.; Sahin, S.; Abdulraoof, M.

1993-01-01

Efforts are made at the College of Engineering, King Saud University, Riyadh to lay out the main structure of a prototype experimental fusion and fusion-fission (hybrid) reactor blanket in cylindrical geometry. The geometry is consistent with most of the current fusion and hybrid reactor design concepts in respect of the neutronic considerations. Characteristics of the fusion chamber, fusion neutrons and the blanket are provided. The studies have further shown that 1 GWe fission-fusion reactor can produce up to 957 kg/year which is enough to fuel five light water reactors of comparable power. Fuel production can be increased further. 29 refs

On the safety of conceptual fusion-fission hybrid reactors

International Nuclear Information System (INIS)

Kastenberg, W.E.; Okrent, D.; Badham, V.; Caspi, S.; Chan, C.K.; Ferrell, W.J.; Frederking, T.H.K.; Grzesik, J.; Lee, J.Y.; McKone, T.E.; Pomraning, G.C.; Ullman, A.Z.; Ting, T.D.; Kim, Y.I.

1979-01-01

A preliminary examination of some potential safety questions for conceptual fusion-fission hybrid reactors is presented in this paper. The study and subsequent analysis was largely based upon one design, a conceptual mirror fusion-fission reactor, operating on the deuterium-tritium plasma fusion fuel cycle and the uranium-plutonium fission fuel cycle. The major potential hazards were found to be: (a) fission products, (b) actinide elements, (c) induced radioactivity, and (d) tritium. As a result of these studies, it appears that highly reliable and even redundent decay heat removal must be provided. Loss of the ability to remove decay heat results in melting of fuel, with ultimate release of fission products and actinides to the containment. In addition, the studies indicate that blankets can be designed which will remain subcritical under extensive changes in both composition and geometry. Magnet safety and the effects of magnetic fields on thermal parameters were also considered. (Auth.)

Mirror hybrid (fusion--fission) reactor

International Nuclear Information System (INIS)

Bender, D.J.; Lee, J.D.; Neef, W.S.; Devoto, R.S.; Galloway, T.R.; Fink, J.H.; Schultz, K.R.; Culver, D.; Rao, S.

1977-10-01

The reference mirror hybrid reactor design performed by LLL and General Atomic is summarized. The reactor parameters have been chosen to minimize the cost of producing fissile fuel for consumption in fission power reactors. As in the past, we have emphasized the use of existing technology where possible and a minimum extrapolation of technology otherwise. The resulting reactor may thus be viewed as a comparatively near-term goal of the fusion program, and we project improved performance for the hybrid in the future as more advanced technology becomes available

Brief review of the fusion-fission hybrid reactor

International Nuclear Information System (INIS)

Tenney, F.H.

1977-01-01

Much of the conceptual framework of present day fusion-fission hybrid reactors is found in the original work of the early 1950's. Present day motivations for development are quite different. The role of the hybrid reactor is discussed as well as the current activities in the development program

Fusion-fission hybrid design with analysis of direct enrichment and non-proliferation features (the SOLASE-H study)

International Nuclear Information System (INIS)

Conn, R.W.; Abdel-Khalik, S.I.; Moses, G.A.; Kulcinski, G.L.; Larsen, E.; Maynard, C.W.; Magheb, M.M.H.; Sviatolslavsky, I.N.; Vogelsang, W.F.; Wolfer, W.G.

1981-01-01

The role of a fusion-fission hybrid in the context of a nuclear economy with and without reprocessing is examined. An inertial confinement fusion driver is assumed and a consistent set of reactor parameters are developed. The form of the driver is not critical, however, to the general concepts. The use of the hybrid as a fuel factory within a secured fuel production and reprocessing center is considered. Either the hybrid or a low power fission reactor can be used to mildly irradiate fuel prior to shipment to offsite reactors thereby rendering the fuel resistant to diversion. A simplified economic analysis indicates a hybrid providing fuel to 10 fission reactors of equal thermal power is insensitive to the recirculating power fraction provided reprocessing is permitted. If reprocessing is not allowed, the hybrid can be used to directly enrich light water reactor fuel bundles fabricated initially from fertile fuel (either ThO 2 or 238 UO 2 ). A detailed neutronic analysis indicates such direct enrichments is feasible but the support ratio for 233 U or 239 Pu production is only 2, making such an approach highly sensitive to the hybrid cost. The hybrid would have to produce considerable net power for economic feasibility in this case. Inertial confinement fusion performance requirements for hybrid application are also examined and an integrated design, SOLASE-H, is described based upon the direct enrichment concept. (orig.)

Optimization of the fission--fusion hybrid concept

International Nuclear Information System (INIS)

Saltmarsh, M.J.; Grimes, W.R.; Santoro, R.T.

1979-04-01

One of the potentially attractive applications of controlled thermonuclear fusion is the fission--fusion hybrid concept. In this report we examine the possible role of the hybrid as a fissile fuel producer. We parameterize the advantages of the concept in terms of the performance of the fusion device and the breeding blanket and discuss some of the more troublesome features of existing design studies. The analysis suggests that hybrids based on deuterium--tritium (D--T) fusion devices are unlikely to be economically attractive and that they present formidable blanket technology problems. We suggest an alternative approach based on a semicatalyzed deuterium--deuterium (D--D) fusion reactor and a molten salt blanket. This concept is shown to emphasize the desirable features of the hybrid, to have considerably greater economic potential, and to mitigate many of the disadvantages of D--T-based systems

Conceptual design of a fusion-fission hybrid reactor for transmutation of high level nuclear waste

International Nuclear Information System (INIS)

Qiu, L.J.; Wu, Y.C.; Yang, Y.W.; Wu, Y.; Luan, G.S.; Xu, Q.; Guo, Z.J.; Xiao, B.J.

1994-01-01

To assess the feasibility of the transmutation of long-lived radioactive waste using fusion-fission hybrid reactors, we are studying all the possible types of blanket, including a comparison of the thermal and fast neutron spectrum blankets. Conceptual designs of a small tokamak hybrid blanket with small inventory of actinides and fission products are presented. The small inventory of wastes makes the system safer. The small hybrid reactor system based on a fusion core with experimental parameters to be realized in the near future can effectively transmute actinides and fission products at a neutron wall loading of 1MWm -2 . An innovative energy system is also presented, including a fusion driver, fuel breeder, high level waste transmuter, fission reactor and so on. An optimal combination of all types of reactor is proposed in the system. ((orig.))

Conceptual design study of Hyb-WT as fusion–fission hybrid reactor for waste transmutation

International Nuclear Information System (INIS)

Siddique, Muhammad Tariq; Kim, Myung Hyun

2014-01-01

Highlights: • Conceptual design study of fusion-fission hybrid reactor for waste transmutation. • MCNPX and MONTEBURNS are compared for transmutation performance of WT-Hyb. • Detailed neutronic performance of final optimized Hyb-WT design is analyzed. • A new tube-in-duct core design is implemented and compared with pin type design. • Study shows many aspects of hybrid reactor even though scope was limited to neutronic analysis. - Abstract: This study proposes a conceptual design of a hybrid reactor for waste transmutation (Hyb-WT). The design of Hyb-WT is based on a low-power tokamak (less than 150 MWt) and an annular ring-shaped reactor core with metal fuel (TRU 60 w/o, Zr 40 w/o) and a fission product (FP) zone. The computational code systems MONTEBURNS and MCNPX2.6 are investigated for their suitability in evaluating the performance of Hyb-WT. The overall design performance of the proposed reactor is determined by considering pin-type and tube-in-duct core designs. The objective of such consideration is to explore the possibilities for enhanced transmutation with reduced wall loading from fusion neutrons and reduced transuranic (TRU) inventory. TRU and FP depletion is analyzed by calculating waste transmutation ratio, mass burned per full power year (in units of kg/fpy), and support ratio. The radio toxicity analysis of TRUs and FPs is performed by calculating the percentage of toxicity reduction in TRU and FP over a burn cycle

Physical Investigation for Neutron Consumption and Multiplication in Blanket Module of Fusion-Fission Hybrid Reactor

International Nuclear Information System (INIS)

Tariq Siddique, M.; Kim, Myung Hyun

2014-01-01

Fusion-fission hybrid reactor can be the first milestone of fusion technology and achievable in near future. It can provide operational experience for tritium recycling for pure fusion reactor and be used for incineration of high-level long-lived waste isotopes from existing fission power reactors. Hybrid reactor for waste transmutation (Hyb-WT) was designed and optimized to assess its otential for waste transmutation. ITER will be the first large scaled experimental tokamak facility for the testing of test blanket modules (TBM) which will layout the foundation for DEMO fusion power plants. Similarly hybrid test blanket module (HTBM) will be the foundation for rationality of fusion fission hybrid reactors. Designing and testing of hybrid blankets will lead to another prospect of nuclear technology. This study is initiated with a preliminary design concept of a hybrid test blanket module (HTBM) which would be tested in ITER. The neutrons generated in D-T fusion plasma are of high energy, 14.1 MeV which could be multiplied significantly through inelastic scattering along with fission in HTBM. In current study the detailed neutronic analysis is performed for the blanket module which involves the neutron growth and loss distribution within blanket module with the choice of different fuel and coolant materials. TRU transmutation and tritium breeding performance of HTBM is analyzed under ITER irradiation environment for five different fuel types and with Li and LiPb coolants. Simple box geometry with plate type TRU fuel is adopted so that it can be modelled with heterogeneous material geometry in MCNPX. Waste transmutation ratio (WTR) of TRUs and tritium breeding ration (TBR) is computed to quantify the HTBM performance. Neutron balance is computed in detail to analyze the performance parameters of HTBM. Neutron spectrum and fission to capture ratio in TRU fuel types is also calculated for detailed analysis of HTBM

Physical Investigation for Neutron Consumption and Multiplication in Blanket Module of Fusion-Fission Hybrid Reactor

Energy Technology Data Exchange (ETDEWEB)

Tariq Siddique, M.; Kim, Myung Hyun [Kyung Hee Univ., Yongin (Korea, Republic of)

2014-05-15

Fusion-fission hybrid reactor can be the first milestone of fusion technology and achievable in near future. It can provide operational experience for tritium recycling for pure fusion reactor and be used for incineration of high-level long-lived waste isotopes from existing fission power reactors. Hybrid reactor for waste transmutation (Hyb-WT) was designed and optimized to assess its otential for waste transmutation. ITER will be the first large scaled experimental tokamak facility for the testing of test blanket modules (TBM) which will layout the foundation for DEMO fusion power plants. Similarly hybrid test blanket module (HTBM) will be the foundation for rationality of fusion fission hybrid reactors. Designing and testing of hybrid blankets will lead to another prospect of nuclear technology. This study is initiated with a preliminary design concept of a hybrid test blanket module (HTBM) which would be tested in ITER. The neutrons generated in D-T fusion plasma are of high energy, 14.1 MeV which could be multiplied significantly through inelastic scattering along with fission in HTBM. In current study the detailed neutronic analysis is performed for the blanket module which involves the neutron growth and loss distribution within blanket module with the choice of different fuel and coolant materials. TRU transmutation and tritium breeding performance of HTBM is analyzed under ITER irradiation environment for five different fuel types and with Li and LiPb coolants. Simple box geometry with plate type TRU fuel is adopted so that it can be modelled with heterogeneous material geometry in MCNPX. Waste transmutation ratio (WTR) of TRUs and tritium breeding ration (TBR) is computed to quantify the HTBM performance. Neutron balance is computed in detail to analyze the performance parameters of HTBM. Neutron spectrum and fission to capture ratio in TRU fuel types is also calculated for detailed analysis of HTBM.

Hefei experimental hybrid fusion-fission reactor conceptual design

International Nuclear Information System (INIS)

Qiu Lijian; Luan Guishi; Xu Qiang

1992-03-01

A new concept of hybrid reactor is introduced. It uses JET-like(Joint European Tokamak) device worked at sub-breakeven conditions, as a source of high energy neutrons to induce a blanket fission of depleted uranium. The solid breeding material and helium cooling technique are also used. It can produce 100 kg of 239 Pu per year by partial fission suppressed. The energy self-sustained of the fusion core is not necessary. Plasma temperature is maintained by external 20 MW ICRF (ion cyclotron resonance frequency) and 10 MW ECRF (electron cyclotron resonance frequency) heating. A steady state plasma current at 1.5 Ma is driven by 10 MW LHCD (lower hybrid current driven). Plasma density will be kept by pellet injection. ICRF can produce a high energy tail in ion distribution function and lead to significant enhancement of D-T reaction rate by 2 ∼ 5 times so that the neutron source strength reaches to the level of 1 x 10 19 n/s. This system is a passive system. It's power density is 10 W/cm 3 and the wall loading is 0.6 W/cm 2 that is the lower limitation of fusion and fission technology. From the calculation of neutrons it could always be in sub-critical and has intrinsic safety. The radiation damage and neutron flux distribution on the first wall are also analyzed. According to the conceptual design the application of this type hybrid reactor earlier is feasible

Thermal safety analysis for pebble bed blanket fusion-fission hybrid reactor

International Nuclear Information System (INIS)

Wei Renjie

1998-01-01

Pebble bed blanket hybrid reactor may have more advantages than slab element blanket hybrid reactor in nuclear fuel production and nuclear safety. The thermo-hydraulic calculations of the blanket in the Tokamak helium cooling pebble bed blanket fusion-fission hybrid reactor developed in China are carried out using the Code THERMIX and auxiliary code. In the calculations different fuel pebble material and steady state, depressurization and total loss of flow accident conditions are included. The results demonstrate that the conceptual design of the Tokamak helium cooling pebble bed blanket fusion-fission hybrid reactor with dump tank is feasible and safe enough only if the suitable fuel pebble material is selected and the suitable control system and protection system are established. Some recommendations for due conceptual design are also presented

Power-balance analysis of muon-catalyzed fusion-fission hybrid reactor systems

International Nuclear Information System (INIS)

Miller, R.L.; Krakowski, R.A.

1985-01-01

A power-balance model of a muon-catalyzed fusion system in the context of a fission-fuel factory is developed and exercised to predict the required physics performance of systems competitive with either pure muon-catalyzed fusion systems or thermonuclear fusion-fission fuel factory hybrid systems

Overview of Fusion-Fission Hybrid Reactor Design Study in China

International Nuclear Information System (INIS)

Huang Jinhua; Feng Kaiming; Deng Baiquan; Deng, P.Zh.; Zhang Guoshu; Hu Gang; He Kaihui; Wu Yican; Qiu Lijian; Huang Qunying; Xiao Bingjia; Liu Xiaoping; Chen Yixue; Kong, M.H.

2002-01-01

The motivation for developing fusion-fission hybrid reactors is discussed in the context of electricity power requirements by 2050 in China. A detailed conceptual design of the Fusion Experimental Breeder (FEB) was developed from 1986-1995. The FEB has a subignited tokamak fusion core with a major radius of 4.0 m, a fusion power of 145 MW, and a fusion energy gain Q of 3. Based on this, an engineering outline design study of the FEB, FEB-E, has been performed. This design study is a transition from conceptual to engineering design in this research. The main results beyond that given in the detailed conceptual design are included in this paper, namely, the design studies of the blanket, divertor, test blanket, and tritium and environment issues. In-depth analyses have been performed to support the design. Studies of related advanced concepts such as the waste transmutation blanket concept and the spherical tokamak core concept are also presented

The Radiological and Thermal Characteristics of Fission Waste from a Deep-Burn Fusion-Fission Hybrid (LIFE) and Implications for Repository Performance

International Nuclear Information System (INIS)

Shaw, H.F.; Blink, J.; Farmer, J.; Latkowski, J.; Kramer, K.

2009-01-01

We are studying the use of a Laser Inertial-confinement Fusion Engine (LIFE) to drive a hybrid fusion-fission system that can generate electrical power and/or burn nuclear waste. The system uses the neutrons from laser driven ICF to produce tritium and to drive nuclear reactions in a subcritical fission blanket. The fusion neutron source obviates the need for a self-sustaining chain reaction in the fission blanket. Either fissile or fertile could be used as fission fuel, thus eliminating the need for isotopic enrichment. The 'driven' system potentially allows very high levels of burnup to be reached, extracting a large fraction of the available energy in the fission fuel without the need for reprocessing. In this note, we discuss the radionuclide inventory of a depleted uranium (DU) fuel burned to greater than 95% FIMA (Fissions per Initial heavy Metal Atom), the implications for thermal management of the resulting waste, and the implications of this waste for meeting the dose standards for releases from a geological repository for high-level waste. The fission waste discussed here would be that produced by a LIFE hybrid with a 500-MW fusion source. The fusion neutrons are multiplied and moderated by a sequence of concentric shells of materials before encountering the fission fuel, and fission in this region is largely due to thermal neutrons. The fission blanket consists of 40 metric tons (MT) of DU, assumed to be in the form of TRISO-like UOC fuel particles embedded in 2-cm-diameter graphite pebbles. (It is recognized that TRISO-based fuel may not reach the high burnup of the fertile fuel considered here, and other fuel options are being investigated. We postulate the existence of a fuel that can reach >95% FIMA so that the waste disposal implications of high burnup can be assessed.) The engine and plant design considered here would receive one load of fission fuel and produce ∼2 GWt of power (fusion + fission) over its 50- to 70-year lifetime. Neutron and

Neutronics issues in fusion-fission hybrid reactor design

International Nuclear Information System (INIS)

Liu Chengan

1995-01-01

The coupled neutron and γ-ray transport equations and nuclear number density equations, and its computer program systems concerned in fusion-fission hybrid reactor design are briefly described. The current status and focal point for coming work of nuclear data used in fusion reactor design are explained

Survey on the fusion/fission-hybrid-reactors, a literature review

International Nuclear Information System (INIS)

A survey, based on existing literature, of the work being pursued worldwide on fusion - fission (hybrid) reactor systems is presented. Six areas are reviewed: Plasma physics parameters; Blankets concepts; Fuel cycles; Reactor conceptual designs; Safety and environmental problems; System studies and economic perspectives. Attention has been restricted to systems using magnetically confined plasmas, mainly to mirror and Tokamak - type concepts. The aim is to provide sufficient information, even if not exhaustive, on hybrid reactor concepts in order to help understand what may be expected from their possible development and the ways in which hybrids could affect the future energy scenario. Some concluding remarks are made which represent the personal view of the authors only

Utility market penetration assessment of fusion-fission hybrids

International Nuclear Information System (INIS)

Jensen, B.K.; Nour, N.E.; Piascik, T.M.

1981-01-01

The objective of this paper is to describe the utility generation expansion evaluation procedure and to present the results of a fusion-fission hybrid market penetration assessment in a model of a typical utility system. The analysis addresses the key factors and tradeoffs affecting the utility's evaluation of generation alternatives

Materials compatibility considerations for a fusion-fission hybrid reactor design

International Nuclear Information System (INIS)

DeVan, J.H.; Tortorelli, P.F.

1983-01-01

The Tandem Mirror Hybrid Reactor is a fusion reactor concept that incorporates a fission-suppressed breeding blanket for the production of 233 U to be used in conventional fission power reactors. The present paper reports on compatibility considerations related to the blanket design. These considerations include solid-solid interactions and liquid metal corrosion. Potential problems are discussed relative to the reference blanket operating temperature (490 0 C) and the recycling time of breeding materials (<1 year)

A fission-fusion hybrid reactor in steady-state L-mode tokamak configuration with natural uranium

International Nuclear Information System (INIS)

Reed, Mark; Parker, Ronald R.; Forget, Benoit

2012-01-01

This work develops a conceptual design for a fusion-fission hybrid reactor operating in steady-state L-mode tokamak configuration with a subcritical natural or depleted uranium pebble bed blanket. A liquid lithium-lead alloy breeds enough tritium to replenish that consumed by the D-T fusion reaction. The fission blanket augments the fusion power such that the fusion core itself need not have a high power gain, thus allowing for fully non-inductive (steady-state) low confinement mode (L-mode) operation at relatively small physical dimensions. A neutron transport Monte Carlo code models the natural uranium fission blanket. Maximizing the fission power gain while breeding sufficient tritium allows for the selection of an optimal set of blanket parameters, which yields a maximum prudent fission power gain of approximately 7. A 0-D tokamak model suffices to analyze approximate tokamak operating conditions. This fission blanket would allow the fusion component of a hybrid reactor with the same dimensions as ITER to operate in steady-state L-mode very comfortably with a fusion power gain of 6.7 and a thermal fusion power of 2.1 GW. Taking this further can determine the approximate minimum scale for a steady-state L-mode tokamak hybrid reactor, which is a major radius of 5.2 m and an aspect ratio of 2.8. This minimum scale device operates barely within the steady-state L-mode realm with a thermal fusion power of 1.7 GW. Basic thermal hydraulic analysis demonstrates that pressurized helium could cool the pebble bed fission blanket with a flow rate below 10 m/s. The Brayton cycle thermal efficiency is 41%. This reactor, dubbed the Steady-state L-mode non-Enriched Uranium Tokamak Hybrid (SLEUTH), with its very fast neutron spectrum, could be superior to pure fission reactors in terms of breeding fissile fuel and transmuting deleterious fission products. It would likely function best as a prolific plutonium breeder, and the plutonium it produces could actually be more

Reprocessing free nuclear fuel production via fusion fission hybrids

Energy Technology Data Exchange (ETDEWEB)

Kotschenreuther, Mike, E-mail: mtk@mail.utexas.edu [Intitute for Fusion Studies, University of Texas at Austin (United States); Valanju, Prashant; Mahajan, Swadesh [Intitute for Fusion Studies, University of Texas at Austin (United States)

2012-05-15

Fusion fission hybrids, driven by a copious source of fusion neutrons can open qualitatively 'new' cycles for transmuting nuclear fertile material into fissile fuel. A totally reprocessing-free (ReFree) Th{sup 232}-U{sup 233} conversion fuel cycle is presented. Virgin fertile fuel rods are exposed to neutrons in the hybrid, and burned in a traditional light water reactor, without ever violating the integrity of the fuel rods. Throughout this cycle (during breeding in the hybrid, transport, as well as burning of the fissile fuel in a water reactor) the fissile fuel remains a part of a bulky, countable, ThO{sub 2} matrix in cladding, protected by the radiation field of all fission products. This highly proliferation-resistant mode of fuel production, as distinct from a reprocessing dominated path via fast breeder reactors (FBR), can bring great acceptability to the enterprise of nuclear fuel production, and insure that scarcity of naturally available U{sup 235} fuel does not throttle expansion of nuclear energy. It also provides a reprocessing free path to energy security for many countries. Ideas and innovations responsible for the creation of a high intensity neutron source are also presented.

Reprocessing free nuclear fuel production via fusion fission hybrids

International Nuclear Information System (INIS)

Kotschenreuther, Mike; Valanju, Prashant; Mahajan, Swadesh

2012-01-01

Fusion fission hybrids, driven by a copious source of fusion neutrons can open qualitatively “new” cycles for transmuting nuclear fertile material into fissile fuel. A totally reprocessing-free (ReFree) Th 232 –U 233 conversion fuel cycle is presented. Virgin fertile fuel rods are exposed to neutrons in the hybrid, and burned in a traditional light water reactor, without ever violating the integrity of the fuel rods. Throughout this cycle (during breeding in the hybrid, transport, as well as burning of the fissile fuel in a water reactor) the fissile fuel remains a part of a bulky, countable, ThO 2 matrix in cladding, protected by the radiation field of all fission products. This highly proliferation-resistant mode of fuel production, as distinct from a reprocessing dominated path via fast breeder reactors (FBR), can bring great acceptability to the enterprise of nuclear fuel production, and insure that scarcity of naturally available U 235 fuel does not throttle expansion of nuclear energy. It also provides a reprocessing free path to energy security for many countries. Ideas and innovations responsible for the creation of a high intensity neutron source are also presented.

Impact of fusion-fission hybrids on world nuclear future

International Nuclear Information System (INIS)

Abdel-Khalick, S.; Jansen, P.; Kessler, G.; Klumpp, P.

1980-08-01

An investigation has been conducted to examine the impact of fusion-fission hybrids on world nuclear future. The primary objectives of this investigation have been: (1) to determine whether hybrids can allow us to meet the projected nuclear component of the world energy demand within current estimates of uranium resources without fast breeders, and (2) to identify the preferred hybrid concept from a resource standpoint. The results indicate that hybrids have the potential to lower the world uranium demand to values well below the resource base. However, the time window for hybrid introduction is quite near and narrow (2000-2020). If historical market penetration rates are assumed, the demand will not be met within the resource base unless hybrids are coupled to the breeders. The results also indicate that from a resource standpoint hybrids which breed their own tritium and have a low blanket energy multiplication are preferable. (orig.) [de

Impact of fusion-fission hybrids on world nuclear future

International Nuclear Information System (INIS)

Abdel-Khalik, S.I.; Jansen, P.; Kessler, G.; Klumpp, P.

1981-01-01

An investigation has been conducted to examine the impact of fusion-fission hybrids on world nuclear future. The primary objectives of this investigation have been: (1) to determine whether hybrids can allow us to meet the projected nuclear component of the world energy demand within current estimates of uranium resources with or without fast breeders, and (2) to identify the preferred hybrid concept from a resource standpoint. The results indicate that hybrids have the potential to lower the world uranium demand to values well below the resource base. However, the time window for hybrid introduction is quite near and narrow (2000-2020). If historical market penetration rates are assumed, the demand will not be met within the resource base unless hybrids are coupled to the breeders. The results also indicate that from a resource standpoint hybrids which breed their own tritium and have a low blanket energy multiplication are preferable. (orig.) [de

Impact of fusion-fission hybrids on world nuclear future

International Nuclear Information System (INIS)

Abdel-Khalik, S.I.

1980-01-01

An investigation has been conducted to examine the impact of fusion-fission hybrids on world nuclear future. The primary objectives of this investigation have been (1) to determine whether hybrids can allow us to meet the projected nuclear component of the world energy demand within current estimates of uranium resources with or without fast breeders, and (2) to identify the preferred hybrid concept from a resource standpoint. The results indicate that hybrids have the potential to lower the world uranium demand to values well below the resource base. However, the time window for hybrid introduction is quite near and narrow (2000-2020). If historical market penetration rates are assumed, the demand will not be met within the resource base unless hybrides are coupled to the breeders. The results also indicate that from a resource standpaint hybrids which breed their own tritium and have a low blanket energy multiplication are preferable. (orig.) [de

Fusion-Fission hybrid reactors and nonproliferation

International Nuclear Information System (INIS)

Greenspan, E.

1984-09-01

New options for the development of the nuclear energy economy which might become available by a successful development of fusion-breeders or fusion-fission hybrid power reactors, identified and their nonproliferative attributes are discussed. The more promising proliferation-resistance ettributes identified include: (1) Justification for a significant delay in the initiation of fuel processing, (2) Denaturing the plutonium with 238 Pu before its use in power reactors of any kind, and (3) Making practical the development of denatured uranium fuel cycles and, in particular, denaturing the uranium with 232 U. Fuel resource utilization, time-table and economic considerations associated with the use of fusion-breeders are also discussed. It is concluded that hybrid reactors may enable developing a nuclear energy economy which is more proliferation resistant than possible otherwise, whileat the same time, assuring high utilization of t he uranium and thorium resources in an economically acceptable way. (author)

Safety analysis on tokamak helium cooling slab fuel fusion-fission hybrid reactor

International Nuclear Information System (INIS)

Wei Renjie; Jian Hongbing

1992-01-01

The thermal analyses for steady state, depressurization and total loss of flow in the tokamak helium cooling slab fuel element fusion-fission hybrid reactor are presented. The design parameters, computed results of HYBRID program and safety evaluation for conception design are given. After all, it gives some recommendations for developing the design

Neutron analysis of a hybrid system fusion-fission

International Nuclear Information System (INIS)

Dorantes C, J. J.; Francois L, J. L.

2011-11-01

The use of energy at world level implies the decrease of natural resources, reduction of fossil fuels, in particular, and a high environmental impact. In view of this problem, an alternative is the energy production for nuclear means, because up to now is one of the less polluting energy; however, the nuclear fuel wastes continue being even a problem without being solved. For the above mentioned this work intends the creation of a device that incorporates the combined technologies of fission and nuclear fusion, called Nuclear Hybrid Reactor Fusion-Fission (HRFF). The HRFF has been designed theoretically with base in experimental fusion reactors in different parts of the world like: United States, Russia, Japan, China and United Kingdom, mainly. The hybrid reactor model here studied corresponds at the Compact Nuclear Facility Source (CNFS). The importance of the CNFS resides in its feasibility, simple design, minor size and low cost; uses deuterium-tritium like main source of neutrons, and as fuel can use the spent fuel of conventional nuclear reactors, such as the current light water reactors. Due to the high costs of experimental research, this work consists on simulating in computer a proposed model of CNFS under normal conditions of operation, to modify the arrangement of the used fuel: MOX and IMF, to analyze the obtained results and to give final conclusions. In conclusion, the HRFF can be a versatile system for the management of spent fuel of light water reactors, so much for the possibility of actinides destruction, like for the breeding of fissile material. (Author)

Tokamak hybrid thermonuclear reactor for the production of fissionable fuel and electric power

International Nuclear Information System (INIS)

Velikhov, E.P.; Glukhikh, V.A.; Gur'ev, V.V.

1978-01-01

The results of feasibility studies of a tokamak- based hybrid reactor concept are presented. The system selected has a D-T plasma volume of 575 m 3 with additional plasma heating by injection of fast neutral particles. The method of heating makes it possible to achieve an economical two-component tokamak regime at ntau=(4-6)x10 13 sxcm -3 , i e. far below the Lawson criterion. Plasma and vacuum chamber are surrounded by a blanket where fissionable plutonium is produced and heat transformed into electric power is generated. Major plasma-neutron-physical characteristics of the 6905 MWth (2500 MWe) reactor and its electromagnetic system are presented. Evaluations show that the hybrid reactor can produce about 800 kg of Pu per 1GWth/yr as compared to 70-150 kg of Pu for fast breeder reactors. The increased Pu production rate is the major merit of the concept promising for both power generation and fuelling thermal fission reactions

The neutronics studies of a fusion fission hybrid reactor using pressure tube blankets

International Nuclear Information System (INIS)

Zheng Youqi; Zu Tiejun; Wu Hongchun; Cao Liangzhi; Yang Chao

2012-01-01

In this paper, a fusion fission hybrid reactor used for energy producing is proposed based on the situation of nuclear power in China. The pressurized light water is applied as the coolant. The fuel assemblies are loaded in the pressure tubes with a modular type structure. The neutronics analysis is performed to get the suitable design and prove the feasibility. The energy multiplication and tritium self-sustaining are evaluated. The neutron load is also cared. From different candidates, the PWR spent fuel is selected as the feed fuel. The results show that the hybrid reactor can meet the expected reactor core lifetime of 5 years with 1000 MWe power output. Two ways are discussed including burning the discharged PWR spent fuel and burning the reprocessed plutonium. The energy multiplication is big enough and the tritium can be self-sustaining for both of the two ways. The neutron wall load in the operating time is kept smaller than the one of ITER. The way to use the reprocessed plutonium brings low neutron wall load, but also brings additional difficulties in operating the hybrid reactor. The way to use the discharged spent fuel is proposed to be a better choice currently.

Systems study of tokamak fusion--fission reactors

International Nuclear Information System (INIS)

Tenney, F.H.; Bathke, C.G.; Price, W.G. Jr.; Bohlke, W.H.; Mills, R.G.; Johnson, E.F.; Todd, A.M.M.; Buchanan, C.H.; Gralnick, S.L.

1978-11-01

This publication reports the results of a two to three year effort at a systematic analysis of a wide variety of tokamak-driven fissioning blanket reactors, i.e., fusion--fission hybrids. It addresses the quantitative problems of determining the economically most desirable mix of the two products: electric power and fissionable fuel and shows how the price of electric power can be minimized when subject to a variety of constraints. An attempt has been made to avoid restricting assumptions, and the result is an optimizing algorithm that operates in a six-dimensional parameter space. Comparisons are made on sets of as many as 100,000 distinct machine models, and the principal results of the study have been derived from the examination of several hundred thousand possible reactor configurations

Mirror hybrid reactor optimization studies

International Nuclear Information System (INIS)

Bender, D.J.

1976-01-01

A system model of the mirror hybrid reactor has been developed. The major components of the model include (1) the reactor description, (2) a capital cost analysis, (3) various fuel management schemes, and (4) an economic analysis that includes the hybrid plus its associated fission burner reactors. The results presented describe the optimization of the mirror hybrid reactor, the objective being to minimize the cost of electricity from the hybrid fission-burner reactor complex. We have examined hybrid reactors with two types of blankets, one containing natural uranium, the other thorium. The major difference between the two optimized reactors is that the uranium hybrid is a significant net electrical power producer, whereas the thorium hybrid just about breaks even on electrical power. Our projected costs for fissile fuel production are approximately 50 $/g for 239 Pu and approximately 125 $/g for 233 U

Singlet-Fission-Sensitized Hybrid Thin-Films For Next-Generation Photovoltaics

Science.gov (United States)

2016-04-12

SECURITY CLASSIFICATION OF: This grant enabled the acquisition of equipment for the fabrication of organic and nanocrystal based photovoltaic (PV... Photovoltaics . The views, opinions and/or findings contained in this report are those of the author(s) and should not contrued as an official Department of...Research Office P.O. Box 12211 Research Triangle Park, NC 27709-2211 singlet fission, nanocrystal, triplet, hybrid, photovoltaic REPORT

Generalized hybrid Monte Carlo - CMFD methods for fission source convergence

International Nuclear Information System (INIS)

Wolters, Emily R.; Larsen, Edward W.; Martin, William R.

2011-01-01

In this paper, we generalize the recently published 'CMFD-Accelerated Monte Carlo' method and present two new methods that reduce the statistical error in CMFD-Accelerated Monte Carlo. The CMFD-Accelerated Monte Carlo method uses Monte Carlo to estimate nonlinear functionals used in low-order CMFD equations for the eigenfunction and eigenvalue. The Monte Carlo fission source is then modified to match the resulting CMFD fission source in a 'feedback' procedure. The two proposed methods differ from CMFD-Accelerated Monte Carlo in the definition of the required nonlinear functionals, but they have identical CMFD equations. The proposed methods are compared with CMFD-Accelerated Monte Carlo on a high dominance ratio test problem. All hybrid methods converge the Monte Carlo fission source almost immediately, leading to a large reduction in the number of inactive cycles required. The proposed methods stabilize the fission source more efficiently than CMFD-Accelerated Monte Carlo, leading to a reduction in the number of active cycles required. Finally, as in CMFD-Accelerated Monte Carlo, the apparent variance of the eigenfunction is approximately equal to the real variance, so the real error is well-estimated from a single calculation. This is an advantage over standard Monte Carlo, in which the real error can be underestimated due to inter-cycle correlation. (author)

Advantages of Production of New Fissionable Nuclides for the Nuclear Power Industry in Hybrid Fusion-Fission Reactors

Science.gov (United States)

Tsibulskiy, V. F.; Andrianova, E. A.; Davidenko, V. D.; Rodionova, E. V.; Tsibulskiy, S. V.

2017-12-01

A concept of a large-scale nuclear power engineering system equipped with fusion and fission reactors is presented. The reactors have a joint fuel cycle, which imposes the lowest risk of the radiation impact on the environment. The formation of such a system is considered within the framework of the evolution of the current nuclear power industry with the dominance of thermal reactors, gradual transition to the thorium fuel cycle, and integration into the system of the hybrid fusion-fission reactors for breeding nuclear fuel for fission reactors. Such evolution of the nuclear power engineering system will allow preservation of the existing structure with the dominance of thermal reactors, enable the reprocessing of the spent nuclear fuel (SNF) with low burnup, and prevent the dangerous accumulation of minor actinides. The proposed structure of the nuclear power engineering system minimizes the risk of radioactive contamination of the environment and the SNF reprocessing facilities, decreasing it by more than one order of magnitude in comparison with the proposed scheme of closing the uranium-plutonium fuel cycle based on the reprocessing of SNF with high burnup from fast reactors.

Neutronics analysis of water-cooled energy production blanket for a fusion-fission hybrid reactor

International Nuclear Information System (INIS)

Jiang Jieqiong; Wang Minghuang; Chen Zhong; Qiu Yuefeng; Liu Jinchao; Bai Yunqing; Chen Hongli; Hu Yanglin

2010-01-01

Neutronics calculations were performed to analyse the parameters of blanket energy multiplication factor (M) and tritium breeding ratio (TBR) in a fusion-fission hybrid reactor for energy production named FDS (Fusion-Driven hybrid System)-EM (Energy Multiplier) blanket. The most significant and main goal of the FDS-EM blanket is to achieve the energy gain of about 1 GWe with self-sustaining tritium, i.e. the M factor is expected to be ∼90. Four different fission materials were taken into account to evaluate M in subcritical blanket: (i) depleted uranium, (ii) natural uranium, (iii) enriched uranium, and (iv) Nuclear Waste (transuranic from 33 000 MWD/MTU PWR (Pressurized Water Reactor) and depleted uranium) oxide. These calculations and analyses were performed using nuclear data library HENDL (Hybrid Evaluated Nuclear Data Library) and a home-developed code VisualBUS. The results showed that the performance of the blanket loaded with Nuclear Waste was most attractive and it could be promising to effectively obtain tritium self-sufficiency and a high-energy multiplication.

Fusion-fission hybrid as an alternative to the fast breeder reactor

International Nuclear Information System (INIS)

Barrett, R.J.; Hardie, R.W.

1980-09-01

This report compares the fusion-fission hybrid on the plutonium cycle with the classical fast breeder reactor (FBR) cycle as a long-term nuclear energy source. For the purpose of comparison, the current light-water reactor once-through (LWR-OT) cycle was also analyzed. The methods and models used in this study were developed for use in a comparative analysis of conventional nuclear fuel cycles. Assessment areas considered in this study include economics, energy balance, proliferation resistance, technological status, public safety, and commercial viability. In every case the characteristics of all fuel cycle facilities were accounted for, rather than just those of the reactor

Measurement of tritium production rate distribution for a fusion-fission hybrid conceptual reactor

International Nuclear Information System (INIS)

Wang Xinhua; Guo Haiping; Mou Yunfeng; Zheng Pu; Liu Rong; Yang Xiaofei; Yang Jian

2013-01-01

A fusion-fission hybrid conceptual reactor is established. It consists of a DT neutron source and a spherical shell of depleted uranium and hydrogen lithium. The tritium production rate (TPR) distribution in the conceptual reactor was measured by DT neutrons using two sets of lithium glass detectors with different thicknesses in the hole in the vertical direction with respect to the D + beam of the Cockcroft-Walton neutron generator in direct current mode. The measured TPR distribution is compared with the calculated results obtained by the three-dimensional Monte Carlo code MCNP5 and the ENDF/B-Ⅵ data file. The discrepancy between the measured and calculated values can be attributed to the neutron data library of the hydrogen lithium lack S(α, β) thermal scattering model, so we show that a special database of low-energy and thermal neutrons should be established in the physics design of fusion-fission hybrid reactors. (authors)

Burn-up calculation of fusion-fission hybrid reactor using thorium cycle

International Nuclear Information System (INIS)

Shido, S.; Matsunaka, M.; Kondo, K.; Murata, I.; Yamamoto, Y.

2006-01-01

A burn-up calculation system has been developed to estimate performance of blanket in a fusion-fission hybrid reactor which is a fusion reactor with a blanket region containing nuclear fuel. In this system, neutron flux is calculated by MCNP4B and then burn-up calculation is performed by ORIGEN2. The cross-section library for ORIGEN2 is made from the calculated neutron flux and evaluated nuclear data. The 3-dimensional ITER model was used as a base fusion reactor. The nuclear fuel (reprocessed plutonium as the fission materials mixed with thorium as the fertile materials), transmutation materials (minor actinides and long-lived fission products) and tritium breeder were loaded into the blanket. Performances of gas-cooled and water-cooled blankets were compared with each other. As a result, the proposed reactor can meet the requirement for TBP and power density. As far as nuclear waste incineration is concerned, the gas-cooled blanket has advantages. On the other hand, the water cooled-blanket is suited to energy production. (author)

Studies of fission fragment yields via high-resolution γ-ray spectroscopy

Science.gov (United States)

Wilson, J. N.; Lebois, M.; Qi, L.; Amador-Celdran, P.; Bleuel, D.; Briz, J. A.; Carroll, R.; Catford, W.; Witte, H. De; Doherty, D. T.; Eloirdi, R.; Georgiev, G.; Gottardo, A.; Goasduff, A.; Hadyñska-Klek, K.; Hauschild, K.; Hess, H.; Ingeberg, V.; Konstantinopoulos, T.; Ljungvall, J.; Lopez-Martens, A.; Lorusso, G.; Lozeva, R.; Lutter, R.; Marini, P.; Matea, I.; Materna, T.; Mathieu, L.; Oberstedt, A.; Oberstedt, S.; Panebianco, S.; Podolyak, Zs.; Porta, A.; Regan, P. H.; Reiter, P.; Rezynkina, K.; Rose, S. J.; Sahin, E.; Seidlitz, M.; Serot, O.; Shearman, R.; Siebeck, B.; Siem, S.; Smith, A. G.; Tveten, G. M.; Verney, D.; Warr, N.; Zeiser, F.; Zielinska, M.

2018-03-01

Precise spectroscopic information on the fast neutron induced fission of the 238U(n,f) reaction was recently gained using a new technique which involved coupling of the Miniball high resolution y-ray spectrometer and the LICORNE directional neutron source. The experiment allowed measurement of the isotopic fission yields for around 40 even-even nuclei at an incident neutron energy of around 2 MeV where yield data are very sparse. In addition spectroscopic information on very neutron-rich fission products was obtained. Results were compared to models, both the JEFF-3.1.1 data base and the GEF code, and large discrepancies for the S1 fission mode in the Sn/Mo isotope pair were discovered. This suggests that current models are overestimating the role played by spherical shell effects in fast neutron induced fission. In late 2017 and 2018 the nu-ball hybrid spectrometer will be constructed at the IPN Orsay to perform further experimental investigations with directional neutrons coupled to a powerful hybrid Ge/LaBr3 detector array. This will open up new possibilities for measurements of fission yields for fast-neutron-induced fission using the spectroscopic technique and will be complimentary to other methods being developed.

Studies of fission fragment yields via high-resolution γ-ray spectroscopy

Directory of Open Access Journals (Sweden)

Wilson J.N.

2018-01-01

Full Text Available Precise spectroscopic information on the fast neutron induced fission of the 238U(n,f reaction was recently gained using a new technique which involved coupling of the Miniball high resolution y-ray spectrometer and the LICORNE directional neutron source. The experiment allowed measurement of the isotopic fission yields for around 40 even-even nuclei at an incident neutron energy of around 2 MeV where yield data are very sparse. In addition spectroscopic information on very neutron-rich fission products was obtained. Results were compared to models, both the JEFF-3.1.1 data base and the GEF code, and large discrepancies for the S1 fission mode in the Sn/Mo isotope pair were discovered. This suggests that current models are overestimating the role played by spherical shell effects in fast neutron induced fission. In late 2017 and 2018 the nu-ball hybrid spectrometer will be constructed at the IPN Orsay to perform further experimental investigations with directional neutrons coupled to a powerful hybrid Ge/LaBr3 detector array. This will open up new possibilities for measurements of fission yields for fast-neutron-induced fission using the spectroscopic technique and will be complimentary to other methods being developed.

Fusion-fission energy systems evaluation

Energy Technology Data Exchange (ETDEWEB)

Teofilo, V.L.; Aase, D.T.; Bickford, W.E.

1980-01-01

This report serves as the basis for comparing the fusion-fission (hybrid) energy system concept with other advanced technology fissile fuel breeding concepts evaluated in the Nonproliferation Alternative Systems Assessment Program (NASAP). As such, much of the information and data provided herein is in a form that meets the NASAP data requirements. Since the hybrid concept has not been studied as extensively as many of the other fission concepts being examined in NASAP, the provided data and information are sparse relative to these more developed concepts. Nevertheless, this report is intended to provide a perspective on hybrids and to summarize the findings of the rather limited analyses made to date on this concept.

Fusion-fission energy systems evaluation

International Nuclear Information System (INIS)

Teofilo, V.L.; Aase, D.T.; Bickford, W.E.

1980-01-01

This report serves as the basis for comparing the fusion-fission (hybrid) energy system concept with other advanced technology fissile fuel breeding concepts evaluated in the Nonproliferation Alternative Systems Assessment Program (NASAP). As such, much of the information and data provided herein is in a form that meets the NASAP data requirements. Since the hybrid concept has not been studied as extensively as many of the other fission concepts being examined in NASAP, the provided data and information are sparse relative to these more developed concepts. Nevertheless, this report is intended to provide a perspective on hybrids and to summarize the findings of the rather limited analyses made to date on this concept

Pulsed fission/fusion hybrid engines

International Nuclear Information System (INIS)

Hudson, G.C.

1979-01-01

Research into high-thrust, high-specific impulse rocket engines using energy from nuclear reactions which has been conducted at this organization will be discussed. The engines are all conceptual in nature, yet are within the realization of conventional or near-term technology. The engine concepts under study at Foundation, Inc. are designed to obviate or minimize these negative effects of the ORION scheme. By using non-chemical triggers to initiate a non-breakeven fusion reaction at the core of a target composed of both fission and fusion fuel, it should be possible to employ the fusion neutrons thus produced to begin a fission reaction in U-235 or Pu-239. Since the density of the target can be increased by as much as a factor of 250 through compression of the pellet, the amount of fission material necessary to produce a critical mass can be greatly reduced. (This also means that the amount of fission products produced for a giventhrust level is also reduced from the ORION levels.) Coupling this eeffect to the large number of 14 MeV fusion neutrons produced early in the compression process and subsequently to the heating of some additional fusion fuel surrounding the critical mass leads to the very efficient burnup of the target. This insures both high yield from the target as well as low cost per MJ energy released. Finally, the use of such small pellets allows the scale of the energy released to be tailored to a level usable in rocket engines of a few tens of tons thrust level. (orig.) [de

Feasibility study of a fission-suppressed tandem-mirror hybrid reactor

International Nuclear Information System (INIS)

Lee, J.D.; Moir, R.W.; Barr, W.L.

1982-04-01

Results of a conceptual design study of a U-233 producing fusion breeder consisting of a tandem mirror fusion device and two types of fission-suppressed blankets are presented. The majority of the study was devoted to the conceptual design and evaluation of the two blankets. However, studies in the areas of fusion engineering, reactor safety, fuel reprocessing, other fuel cycle issues, economics, and deployment were also performed

Conceptual design of the blanket and power conversion system for a mirror hybrid fusion-fission reactor. 12-month progress report, July 1, 1975--June 30, 1976

International Nuclear Information System (INIS)

Schultz, K.R.; Baxi, C.B.; Rao, R.

1976-01-01

This report presents the conceptual design and preliminary feasibility assessment for the hybrid blanket and power conversion system of the Mirror Hybrid Fusion-Fission Reactor. Existing gas-cooled fission reactor technology is directly applicable to the Mirror Hybrid Reactor. There are a number of aspects of the present conceptual design that require further design and analysis effort. The blanket and power conversion system operating parameters have not been optimized. The method of supporting the blanket modules and the interface between these modules and the primary loop helium ducting will require further design work. The means of support and containment of the primary loop components must be studied. Nevertheless, in general, the conceptual design appears quite feasible

Perspective on the fusion-fission energy concept

International Nuclear Information System (INIS)

Liikala, R.C.; Perry, R.T.; Teofilo, V.L.

1978-01-01

A concept which has potential for near-term application in the electric power sector of our energy economy is combining fusion and fission technology. The fusion-fission system, called a hybrid, is distinguished from its pure fusion counterpart by incorporation of fertile materials (uranium or thorium) in the blanket region of a fusion machine. The neutrons produced by the fusion process can be used to generate energy through fission events in the blanket or produce fuel for fission reactors through capture events in the fertile material. The performance requirements of the fusion component of hybrids is perceived as being less stringent than those for pure fusion electric power plants. The performance requirements for the fission component of hybrids is perceived as having been demonstrated or could be demonstrated with a modest investment of research and development funds. This paper presents our insights and observations of this concept in the context of why and where it might fit into the picture of meeting our future energy needs. A bibliography of hybrid research is given

Non-electrical uses of thermal energy generated in the production of fissile fuel in fusion--fission reactors: a comparative economic parametric analysis for a hybrid with or without synthetic fuel production

International Nuclear Information System (INIS)

Tai, A.S.; Krakowski, R.A.

1979-01-01

A parametric analysis has been carried out for testing the sensitivity of the synfuel production cost in relation to crucial economic and technologic quantities (investment costs of hybrid and synfuel plant, energy multiplication of the fission blanket, recirculating power fraction of the fusion driver, etc.). In addition, a minimum synfuel selling price has been evaluated, from which the fission--fusion--synfuel complex brings about a higher economic benefit than does the fusion--fission hybrid entirely devoted to fissile-fuel and electricity generation. Assuming an electricity cost of 2.7 cents/kWh, an annual investment cost per power unit of 4.2 to 6 $/GJ (132 to 189 k$/MWty) for the fission--fusion complex and 1.5 to 3 $/GJ (47 to 95 k$/MWty) for the synfuel plant, the synfuel production net cost (i.e., revenue = cost) varies between 6.5 and 8.6 $/GJ. These costs can compete with those obtained by other processes (natural gas reforming, resid partial oxidation, coal gasification, nuclear fission, solar electrolysis, etc.). This study points out a potential use of the fusion--fission hybrid other than fissile-fuel and electricity generation

Research Needs for Fusion-Fission Hybrid Systems. Report of the Research Needs Workshop (ReNeW) Gaithersburg, Maryland, September 30 - October 2, 2009

Energy Technology Data Exchange (ETDEWEB)

None

2009-09-30

Largely in anticipation of a possible nuclear renaissance, there has been an enthusiastic renewal of interest in the fusion-fission hybrid concept, driven primarily by some members of the fusion community. A fusion-fission hybrid consists of a neutron-producing fusion core surrounded by a fission blanket. Hybrids are of interest because of their potential to address the main long-term sustainability issues related to nuclear power: fuel supply, energy production, and waste management. As a result of this renewed interest, the U.S. Department of Energy (DOE), with the participation of the Office of Fusion Energy Sciences (OFES), Office of Nuclear Energy (NE), and National Nuclear Security Administration (NNSA), organized a three-day workshop in Gaithersburg, Maryland, from September 30 through October 2, 2009. Participants identified several goals. At the highest level, it was recognized that DOE does not currently support any R&D in the area of fusion-fission hybrids. The question to be addressed was whether or not hybrids offer sufficient promise to motivate DOE to initiate an R&D program in this area. At the next level, the workshop participants were asked to define the research needs and resources required to move the fusion-fission concept forward. The answer to the high-level question was given in two ways. On the one hand, when viewed as a standalone concept, the fusion-fission hybrid does indeed offer the promise of being able to address the sustainability issues associated with conventional nuclear power. On the other hand, when participants were asked whether these hybrid solutions are potentially more attractive than contemplated pure fission solutions (that is, fast burners and fast breeders), there was general consensus that this question could not be quantitatively answered based on the known technical information. Pure fission solutions are based largely on existing both fusion and nuclear technology, thereby prohibiting a fair side-by-side comparison

Economic regimes for fission--fusion energy systems

International Nuclear Information System (INIS)

Deonigi, D.E.

1974-01-01

The objectives of this hybrid fusion-fission economic regimes study are to: (1) define the target costs to be met, (2) define the optimum fissile/electrical production ratio for hybrid blankets, (3) discover synergistic configurations, and (4) define the windows of economic hybrid design having desirable cost/benefit ratios. (U.S.)

Hybrid reactors

International Nuclear Information System (INIS)

Moir, R.W.

1980-01-01

The rationale for hybrid fusion-fission reactors is the production of fissile fuel for fission reactors. A new class of reactor, the fission-suppressed hybrid promises unusually good safety features as well as the ability to support 25 light-water reactors of the same nuclear power rating, or even more high-conversion-ratio reactors such as the heavy-water type. One 4000-MW nuclear hybrid can produce 7200 kg of 233 U per year. To obtain good economics, injector efficiency times plasma gain (eta/sub i/Q) should be greater than 2, the wall load should be greater than 1 MW.m -2 , and the hybrid should cost less than 6 times the cost of a light-water reactor. Introduction rates for the fission-suppressed hybrid are usually rapid

Neutron transport-burnup code MCORGS and its application in fusion fission hybrid blanket conceptual research

Science.gov (United States)

Shi, Xue-Ming; Peng, Xian-Jue

2016-09-01

Fusion science and technology has made progress in the last decades. However, commercialization of fusion reactors still faces challenges relating to higher fusion energy gain, irradiation-resistant material, and tritium self-sufficiency. Fusion Fission Hybrid Reactors (FFHR) can be introduced to accelerate the early application of fusion energy. Traditionally, FFHRs have been classified as either breeders or transmuters. Both need partition of plutonium from spent fuel, which will pose nuclear proliferation risks. A conceptual design of a Fusion Fission Hybrid Reactor for Energy (FFHR-E), which can make full use of natural uranium with lower nuclear proliferation risk, is presented. The fusion core parameters are similar to those of the International Thermonuclear Experimental Reactor. An alloy of natural uranium and zirconium is adopted in the fission blanket, which is cooled by light water. In order to model blanket burnup problems, a linkage code MCORGS, which couples MCNP4B and ORIGEN-S, is developed and validated through several typical benchmarks. The average blanket energy Multiplication and Tritium Breeding Ratio can be maintained at 10 and 1.15 respectively over tens of years of continuous irradiation. If simple reprocessing without separation of plutonium from uranium is adopted every few years, FFHR-E can achieve better neutronic performance. MCORGS has also been used to analyze the ultra-deep burnup model of Laser Inertial Confinement Fusion Fission Energy (LIFE) from LLNL, and a new blanket design that uses Pb instead of Be as the neutron multiplier is proposed. In addition, MCORGS has been used to simulate the fluid transmuter model of the In-Zinerater from Sandia. A brief comparison of LIFE, In-Zinerater, and FFHR-E will be given.

Advanced burnup calculation code system in a subcritical state with continuous-energy Monte Carlo code for fusion-fission hybrid reactor

International Nuclear Information System (INIS)

Matsunaka, Masayuki; Ohta, Masayuki; Miyamaru, Hiroyuki; Murata, Isao

2009-01-01

The fusion-fission (FF) hybrid reactor is a promising energy source that is thought to act as a bridge between the existing fission reactor and the genuine fusion reactor in the future. The burnup calculation system that aims at precise burnup calculations of a subcritical system was developed for the detailed design of the FF hybrid reactor, and the system consists of MCNP, ORIGEN, and postprocess codes. In the present study, the calculation system was substantially modified to improve the calculation accuracy and at the same time the calculation speed as well. The reaction rate estimation can be carried out accurately with the present system that uses track-length (TL) data in the continuous-energy treatment. As for the speed-up of the reaction rate calculation, a new TL data bunching scheme was developed so that only necessary TL data are used as long as the accuracy of the point-wise nuclear data is conserved. With the present system, an example analysis result for our proposed FF hybrid reactor is described, showing that the computation time could really be saved with the same accuracy as before. (author)

Hybrid nuclear cycles for nuclear fission sustainability

International Nuclear Information System (INIS)

Piera, M.; Martinez-Val, M. M.

2007-01-01

Nuclear fission can play and must play an important role in paving the road to Energy Sustainability. Nuclear Fission does not produce CO 2 emissions, and it is already exploited at commercial level with the current NPP (Nuclear Power Plants). Most of them are based on LWR reactors, which have a very good safety record. It must be noted, however, that all LWR (including the advanced or evolutionary ones) have some drawbacks, particularly their very poor efficiency in exploiting the natural resources of nuclear fuels. In this paper, an analysis is presented on how to maximize the energy actually generated from the potential contents of fission natural resources. The role of fertile-to-fissile breeding is highlighted, as well as the need of attaining a very high safety performance in the reactors and other installations of the fuel cycle. The proposal presented in this paper is to use advanced and evolutionary LWR as energy producing reactors, and to use subcritical fast assemblies as breeders. The main result would be to increase by two orders of magnitude the percentage of energy effectively exploited from fission natural resources, while keeping a very high level of safety standards in the full fuel cycle. Breeders would not be intended for energy production, so that safety standards could rely on very low values of the thermal magnitudes, so allowing for very large safety margins for emergency cooling. Similarly, subcriticality would offer a very large margin for not to reach prompt criticality in any event. The main drawback of this proposal is that a sizeable fraction of the energy generated in the cycle (about 1/3, maybe a little more) would not be useful for the thermodynamic cycle to produce electricity. Besides that, a fraction of the generated electricity, between 5 and 10 %, would have to be recirculated to feed the accelerator activating the neutron source. Even so, the overall result would be very positive, because more than 50 % of the natural

Radiochemistry and the Study of Fission

Energy Technology Data Exchange (ETDEWEB)

Rundberg, Robert S. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2016-11-14

These are slides from a lecture given at UC Berkeley. Radiochemistry has been used to study fission since its discovery. Radiochemical methods are used to determine cumulative mass yields. These measurements have led to the two-mode fission hypothesis to model the neutron energy dependence of fission product yields. Fission product yields can be used for the nuclear forensics of nuclear explosions. The mass yield curve depends on both the fuel and the neutron spectrum of a device. Recent studies have shown that the nuclear structure of the compound nucleus can affect the mass yield distribution. The following topics are covered: In the beginning: the discovery of fission; forensics using fission products: what can be learned from fission products, definitions of R-values and Q-values, fission bases, K-factors and fission chambers, limitations; the neutron energy dependence of the mass yield distribution (the two mode fission hypothesis); the influence of nuclear structure on the mass yield distribution. In summary: Radiochemistry has been used to study fission since its discovery. Radiochemical measurement of fission product yields have provided the highest precision data for developing fission models and for nuclear forensics. The two-mode fission hypothesis provides a description of the neutron energy dependence of the mass yield curve. However, data is still rather sparse and more work is needed near second and third chance fission. Radiochemical measurements have provided evidence for the importance of nuclear states in the compound nucleus in predicting the mass yield curve in the resonance region.

Radiochemistry and the Study of Fission

International Nuclear Information System (INIS)

Rundberg, Robert S.

2016-01-01

These are slides from a lecture given at UC Berkeley. Radiochemistry has been used to study fission since its discovery. Radiochemical methods are used to determine cumulative mass yields. These measurements have led to the two-mode fission hypothesis to model the neutron energy dependence of fission product yields. Fission product yields can be used for the nuclear forensics of nuclear explosions. The mass yield curve depends on both the fuel and the neutron spectrum of a device. Recent studies have shown that the nuclear structure of the compound nucleus can affect the mass yield distribution. The following topics are covered: In the beginning: the discovery of fission; forensics using fission products: what can be learned from fission products, definitions of R-values and Q-values, fission bases, K-factors and fission chambers, limitations; the neutron energy dependence of the mass yield distribution (the two mode fission hypothesis); the influence of nuclear structure on the mass yield distribution. In summary: Radiochemistry has been used to study fission since its discovery. Radiochemical measurement of fission product yields have provided the highest precision data for developing fission models and for nuclear forensics. The two-mode fission hypothesis provides a description of the neutron energy dependence of the mass yield curve. However, data is still rather sparse and more work is needed near second and third chance fission. Radiochemical measurements have provided evidence for the importance of nuclear states in the compound nucleus in predicting the mass yield curve in the resonance region.

Parametric systems analysis for ICF hybrid reactors

International Nuclear Information System (INIS)

Berwald, D.H.; Maniscalco, J.A.; Chapin, D.L.

1981-01-01

Parametric design and systems analysis for inertial confinement fusion-fission hybrids are presented. These results were generated as part of the Electric Power Research Institute (EPRI) sponsored Feasibility Assessment of Fusion-Fission Hybrids, using an Inertial Confinement Fusion (ICF) hybrid power plant design code developed in conjunction with the feasibility assessment. The SYMECON systems analysis code, developed by Westinghouse, was used to generate economic results for symbiotic electricity generation systems consisting of the hybrid and its client Light Water Reactors (LWRs). These results explore the entire fusion parameter space for uranium fast fission blanket hybrids, thorium fast fission blanket hybrids, and thorium suppressed fission blanket types are discussed, and system sensitivities to design uncertainties are explored

Feasibility of recycling thorium in a fusion-fission hybrid/PWR symbiotic system

International Nuclear Information System (INIS)

Josephs, J.M.

1980-01-01

A study was made of the economic impact of high levels of radioactivity in the thorium fuel cycle. The sources of this radioactivity and means of calculating the radioactive levels at various stages in the fuel cycle are discussed and estimates of expected levels are given. The feasibility of various methods of recycling thorium is discussed. These methods include direct recycle, recycle after storage for 14 years to allow radioactivity to decrease, shortening irradiation times to limit radioactivity build up, and the use of the window in time immediately after reprocessing where radioactivity levels are diminished. An economic comparison is made for the first two methods together with the throwaway option where thorium is not recycled using a mass energy flow model developed for a CTHR (Commercial Tokamak Hybrid Reactor), a fusion fission hybrid reactor which serves as fuel producer for several PWR reactors. The storage option is found to be most favorable; however, even this option represents a significant economic impact due to radioactivity of 0.074 mills/kW-h which amounts to $4 x 10 9 over a 30 year period assuming a 200 gigawatt supply of electrical power

Study of hypernuclei fission

International Nuclear Information System (INIS)

Malek, F.

1990-01-01

This work is about PS177 experience made on LEAR machine at CERN in 1988. The annihilation reaction of anti protons on a target of Bismuth or Uranium is studied. Lambda particles are produced by this reaction, in the nucleus in 2% of cases 7.1 10 -3 hypernuclei by stopped antiproton in the target are produced. The prompt hypernucleus fission probability of uranium is 75% and that of Bismuth 10%. The mass distribution of fission fragments is symmetrical ((≡ the excitation energy of the nucleus is very high). If the nucleus hasn't fissioned, the non-mesonic lambda decay, gives it an energy of 100 MeV, what allows to fission later. This fission is delayed because the hypernucleus lifetime is 1.3 +0.25 -0.21 10 -10 sec for Bismuth [fr

Thorium--uranium cycle ICF hybrid concept

International Nuclear Information System (INIS)

Frank, T.G.

1978-01-01

The results of preliminary studies of a laser-driven fusion-fission hybrid concept utilizing the 232 Th- 233 U breeding cycle are reported. Neutron multiplication in the breeding blanket is provided by a region containing 238 UO 2 and the equilibrium concentration of 239 PuO 2 . Established fission reactor technology is utilized to determine limits on operating conditions for high-temperature fuels and structures. The implications of nonproliferation policies for the operation of fusion-fission hybrid reactors are discussed

Case for the fusion hybrid

International Nuclear Information System (INIS)

Rose, R.P.

1981-01-01

The use of nuclear fusion to produce fuel for nuclear fission power stations is discussed in the context of a crucial need for future energy options. The fusion hybrid is first considered as an element in the future of nuclear fission power to provide long term assurance of adequate fuel supplies for both breeder and convertor reactors. Generic differences in neutronic characteristics lead to a fuel production potential of fusion-fission hybrid systems which is significantly greater than that obtainable with fission systems alone. Furthermore, cost benefit studies show a variety of scenarios in which the hybrid offers sufficient potential to justify development costs ranging in the tens of billions of dollars. The hybrid is then considered as an element in the ultimate development of fusion electric power. The hybrid offers a near term application of fusion where experience with the requisite technologies can be derived as a vital step in mapping a credible route to eventual commercial feasibility of pure fusion systems. Finally, the criteria for assessment of future energy options are discussed with prime emphasis on the need for rational comparision of alternatives

Fission-suppressed hybrid reactor: the fusion breeder

International Nuclear Information System (INIS)

Moir, R.W.; Lee, J.D.; Coops, M.S.

1982-12-01

Results of a conceptual design study of a 233 U-producing fusion breeder are presented. The majority of the study was devoted to conceptual design and evaluation of a fission-suppressed blanket and to fuel cycle issues such as fuel reprocessing, fuel handling, and fuel management. Studies in the areas of fusion engineering, reactor safety, and economics were also performed

Conceptual design of a hybrid fusion-fission reactor with intrinsic safety and optimized energy productivity

International Nuclear Information System (INIS)

Talebi, Hosein; Sadat Kiai, S.M.

2017-01-01

Highlights: • Designing a high yield and feasible Dense Plasma Focus for driving the reactor. • Presenting a structural method to design the dual layer cylindrical blankets. • Finding, the blanket production energy, in terms of its geometrical and material parameters. • Designing a subcritical blanket with optimization of energy amplification in detail. - Abstract: A hybrid fission-fusion reactor with a Dense Plasma Focus (DPF) as a fusion core and the dual layer fissionable blanket as the energy multiplier were conceptually designed. A cylindrical DPF, energized by a 200 kJ bank energy, is considered to produce fusion neutron, and these neutrons drive the subcritical fission in the surrounding blankets. The emphasis has been placed on the safety and energy production with considering technical and economical limitations. Therefore, the k eff-t of the dual cylindrical blanket was defined and mathematically, specified. By applying the safety criterion (k eff-t ≤ 0.95), the geometrical and material parameters of the blanket optimizing the energy amplification were obtained. Finally, MCNPX code has been used to determine the detailed dimensions of the blankets and fuel rods.

Laser Intertial Fusion Energy: Neutronic Design Aspects of a Hybrid Fusion-Fission Nuclear Energy System

Energy Technology Data Exchange (ETDEWEB)

Kramer, Kevin James [Univ. of California, Berkeley, CA (United States)

2010-04-08

This study investigates the neutronics design aspects of a hybrid fusion-fission energy system called the Laser Fusion-Fission Hybrid (LFFH). A LFFH combines current Laser Inertial Confinement fusion technology with that of advanced fission reactor technology to produce a system that eliminates many of the negative aspects of pure fusion or pure fission systems. When examining the LFFH energy mission, a significant portion of the United States and world energy production could be supplied by LFFH plants. The LFFH engine described utilizes a central fusion chamber surrounded by multiple layers of multiplying and moderating media. These layers, or blankets, include coolant plenums, a beryllium (Be) multiplier layer, a fertile fission blanket and a graphite-pebble reflector. Each layer is separated by perforated oxide dispersion strengthened (ODS) ferritic steel walls. The central fusion chamber is surrounded by an ODS ferritic steel first wall. The first wall is coated with 250-500 μm of tungsten to mitigate x-ray damage. The first wall is cooled by Li₁₇Pb₈₃ eutectic, chosen for its neutron multiplication and good heat transfer properties. The Li₁₇Pb₈₃ flows in a jacket around the first wall to an extraction plenum. The main coolant injection plenum is immediately behind the Li₁₇Pb₈₃, separated from the Li₁₇Pb₈₃ by a solid ODS wall. This main system coolant is the molten salt flibe (2LiF-BeF₂), chosen for beneficial neutronics and heat transfer properties. The use of flibe enables both fusion fuel production (tritium) and neutron moderation and multiplication for the fission blanket. A Be pebble (1 cm diameter) multiplier layer surrounds the coolant injection plenum and the coolant flows radially through perforated walls across the bed. Outside the Be layer, a fission fuel layer comprised of depleted uranium contained in Tristructural-isotropic (TRISO) fuel particles

Nuclear fission studies: from LOHENGRIN to FIPPS

International Nuclear Information System (INIS)

Chebboubi, Abdelaziz

2015-01-01

Nuclear fission consists in splitting a nucleus, in general an actinide, into smaller nuclei. Despite nuclear fission was discovered in 1939 by Hahn and Strassman, fission models cannot predict the fission observables with an acceptable accuracy for nuclear fuel cycle studies for instance. Improvement of fission models is an important issue for the knowledge of the process itself and for the applications. To reduce uncertainties of the nuclear data used in a nuclear reactor simulation, a validation of the models hypothesis is mandatory. In this work, two features of the nuclear fission were investigated in order to test the resistance of the theories. One aspect is the study of the symmetric fission fragments through the measurement of their yield and kinetic energy distribution. The other aspect is the study of the fission fragment angular momentum.Two techniques are available to assess the angular momentum of a fission fragment. The first one is to look at the properties of the prompt gamma. The new spectrometer FIPPS (Fission Product Prompt gamma-ray Spectrometer), is currently under development at the ILL and will combine a fission filter with a large array of gamma and neutron detectors in order to respond to these issues. The first part of this work is dedicated to the study of the properties of a Gas Filled Magnet (GFM) which is the type of fission filter considered for the FIPPS project.The second part of this work deals with the measurement of isomeric yields and evaluations of the angular momentum distribution of fission fragments. The study of the spherical nucleus 132 Sn shed the light on the current limits of fission models. Finally, the last part of this work is about the measurement of the yields and kinetic energy distributions of symmetric fission fragments. Since models predict the existence of fission modes, the symmetry region is a suitable choice to investigate this kind of prediction. In parallel with all these studies, an emphasis on the

Conceptual design of the blanket and power conversion system for a mirror hybrid fusion-fission reactor. Addendum 1. Alternate concepts. 12-month progress report addendum, July 1, 1975--June 30, 1976

International Nuclear Information System (INIS)

Schultz, K.R.; Dee, J.B.; Backus, G.A.; Culver, D.W.

1976-01-01

During the course of the Mirror Hybrid Fusion-Fission Reactor study several alternate concepts were considered for various reactor components. Several of the alternate concepts do appear to exhibit features with potential advantage for use in the mirror hybrid reactor. These are described and should possibly be investigated further in the future

Radiochemical studies on fission

Energy Technology Data Exchange (ETDEWEB)

None

1973-07-01

Research progress is reported on nuclear chemistry; topics considered include: recoil range and kinetic energy distribution in the thermal neutron ftssion of /sup 245/Cm; mass distribution and recoil range measurements in the reactor neutron-induced fission of /sup 232/U; fission yields in the thermal neutron fission of /sup 241/PU highly asymmetric binary fission of uranium induced by reactor neutrons; and nuclear charge distribution in low energy fission. ( DHM)

Preliminary design and analysis on nuclear fuel cycle for fission-fusion hybrid spent fuel burner

International Nuclear Information System (INIS)

Chen Yan; Wang Minghuang; Jiang Jieqiong

2012-01-01

A wet-processing-based fuel cycle and a dry-processing were designed for a fission-fusion hybrid spent fuel burner (FDS-SFB). Mass flow of SFB was preliminarily analyzed. The feasibility analysis of initial loaded fuel inventory, recycle fuel fabrication and spent fuel reprocessing were preliminarily evaluated. The results of mass flow of FDS-SFB demonstrated that the initial loaded fuel inventory, recycle fuel fabrication and spent fuel reprocessing of nuclear fuel cycle of FDS-SFB is preliminarily feasible. (authors)

Neutronic calculation and cross section sensitivity analysis of the Livermore mirror fusion/fission hybrid reactor blanket

International Nuclear Information System (INIS)

Ku, L.P.; Price, W.G. Jr.

1977-08-01

The neutronic calculation for the Livermore mirror fusion/fission hybrid reactor blanket was performed using the PPPL cross section library. Significant differences were found in the tritium breeding and plutonium production in comparison to the results of the LLL calculation. The cross section sensitivity study for tritium breeding indicates that the response is sensitive to the cross section of 238 U in the neighborhood of 14 MeV and 1 MeV. The response is also sensitive to the cross sections of iron in the vicinity of 14 MeV near the first wall. Neutron transport in the resonance region is not important in this reactor model

Fusion--fission energy systems, some utility perspectives

International Nuclear Information System (INIS)

Huse, R.A.; Burger, J.M.; Lotker, M.

1974-01-01

Some of the issues that are important in assessing fusion-- fission energy systems from a utility perspective are discussed. A number of qualitative systems-oriented observations are given along with some economic quantification of the benefits from fusion--fission hybrids and their allowed capital cost. (U.S.)

Activation analysis and waste management for blanket materials of multi-functional experimental fusion–fission hybrid reactor (FDS-MFX)

International Nuclear Information System (INIS)

Jiang, Jieqiong; Yuan, Baoxin; Zou, Jun; Wu, Yican

2014-01-01

The preliminary studies of the activation analysis and waste management for blanket materials of the multi-functional experimental fusion–fission hybrid reactor, i.e. Multi-Functional eXperimental Fusion Driven Subcritical system named FDS-MFX, were performed. The neutron flux of the FDS-MFX blanket was calculated using VisualBUS code and Hybrid Evaluated Nuclear Data Library (HENDL) developed by FDS Team. Based on these calculated neutron fluxes, the activation properties of blanket materials were analyzed by the induced radioactivity, the decay heat and the contact dose rate for different regions of the FDS-MFX blanket. The safety and environment assessment of fusion power (SEAFP) strategy, which was developed in Europe, was applied to FDS-MFX blanket for the management of activated materials. Accordingly, the classification and management strategy of activated materials after different cooling time were proposed for FDS-MFX blanket

Study on the effect factor of the absolute fission rates measured by depleted uranium fission chamber

International Nuclear Information System (INIS)

Jiang Li; Liu Rong; Wang Dalun; Wang Mei; Lin Jufang; Wen Zhongwei

2003-01-01

The absolute fission rates was measured by the depleted uranium fission chamber. The efficiency of the fission fragments recorded in the fission chamber was analyzed. The factor influencing absolute fission rates was studied in the experiment, including the disturbing effect between detectors and the effect of the structural of the fission chamber, etc

Conceptual innovations in hybrid reactors

International Nuclear Information System (INIS)

Greenspan, E.; Miley, G.H.

1980-01-01

A number of innovations in the conception of fusion-fission hybrid reactors, including the blanket, the fusion driver, the coupling of the fusion and the fission components as well as the application of hybrid reactors are described, and their feasibility assessed

Proceedings of the Second Fusion-Fission Energy Systems Review Meeting

Energy Technology Data Exchange (ETDEWEB)

None

1977-11-02

The agenda of the meeting was developed to address, in turn, the following major areas: specific problem areas in nuclear energy systems for application of fusion-fission concepts; current and proposed fusion-fission programs in response to the identified problem areas; target costs and projected benefits associated with fusion-fission energy systems; and technical problems associated with the development of fusion-fission concepts. The greatest emphasis was placed on the characteristics of and problems, associated with fuel producing fusion-fission hybrid reactors.

Development of fission micro-chambers for nuclear waste incineration studies

CERN Document Server

Fadil, M; Christophe, S; Deruelle, O; Fioni, G; Marie, F; Mounier, C; Ridikas, D; Trapp, J P

2002-01-01

The Incineration by Accelerator (INCA) project of the Directorate for Science of Matter of the French Atomic Energy Authority (CEA/DSM) aims to outline the ideal physical conditions to transmute minor actinides in a high intensity neutron flux obtained either by hybrid systems or innovative critical reactors. To measure on-line the incineration rates of minor actinides, we are developing an innovative Double Deposit Fission Chamber (DDFC) working in current mode. Our method is based on a comparison between the isotope under study and a reference material whose nuclear parameters are well known, as sup 2 sup 3 sup 5 U and sup 2 sup 3 sup 9 Pu. This new fission chamber will be used in the High Flux Reactor in Grenoble/France in a neutron flux of 1.2x10 sup 1 sup 5 n cm sup - sup 2 s sup - sup 1 for 50 days, the operating cycle of the reactor. These specific experimental conditions require substantial modifications of the existing chambers. The first experiment will be carried out in fall 2000.

An economic parametric analysis of the synthetic fuel produced by a fusion-fission complex

International Nuclear Information System (INIS)

Tai, A.S.; Krakowski, R.A.

1980-01-01

A simple analytic model is used to examine economic constraints of a fusion-fission complex in which a portion of a thermal energy is used for producing synthetic fuel (synfuel). Since the values of many quantities are not well-known, a parametric analysis has been carried out for testing the sensitivity of the synfuel production cost in relation to crucial economic and technological quantities (investment costs of hybrid and synfuel plants, energy multiplication of the fission blanket, recirculating power fraction of the fusion driver, etc.). In addition, a minimum synfuel selling price has been evaluated, from which the fission-fusion-synfuel complex brings about a higher economic benefit than does the fusion-fission hybrid entirely devoted to fissile-fuel and electricity generation. This paper describes the energy flow diagram of fusion-fission synfuel concept, express the revenue-to-cost formulation and the breakeven synfuel selling price. The synfuel production cost given by the model is evaluated within a range of values of crucial parameters. Assuming an electric cost of 2.7 cents/kWh, an annual investment cost per energy unit of 4.2 to 6 $/FJ for the fusion-fission complex and 1.5 to 3 $/GJ for the synfuel plant, the synfuel production cost lies between 6.5 and 8.5 $/GJ. These production costs can compete with those evaluated for other processes. The study points out a potential use of the fusion-fission hybrid reactor for other than fissile-fuel and electricity generation. (orig.) [de

Critical masses of miniexplosion in fission-fusion hybrid systems

Energy Technology Data Exchange (ETDEWEB)

Kaliski, S [Polska Akademia Nauk, Warsaw. Inst. Podstawowych Problemow Techniki

1976-01-01

The critical mass of the fissionable material subjected to the explosive compression and the action of the neutron stream originating from the process of D-T fusion in the spherical cavity was estimated. High energy recovery from the fissionable material was obtained and the energy of the laser pulse was minimized.

Report of fission study meeting

International Nuclear Information System (INIS)

1986-03-01

This book is the report of fission Study Meeting held from September 19 to 21, 1985 in the Research Center for Nuclear Physics, Osaka University. The objective of this study meeting was to stimulate the research on nuclear physics in Japan, which began to show new development accompanying the advance of the research on heavy ion nuclear reaction, and to make this a new starting point. More than 50 participants from physical, chemical and engineering fields, who have interest in the theory and experiment related to nuclear fission, gathered, and the meeting was a success beyond expectation. The contents covered a wide range including nuclear smashing reaction as well as nuclear fission in a narrow sense. In this book, the gists of 28 papers are collected. (Kako, I.)

Preliminary assessment of a symbiotic fusion--fission power system using the TH/U refresh fuel cycle

International Nuclear Information System (INIS)

Bender, D.J.; Lee, J.D.; Moir, R.W.

1977-10-01

Studies of the mirror hybrid reactor by LLL/GA have concluded that the most promising role for this reactor concept is that of a producer of fissile fuel for fission reactors. Studies to date have examined primarily the U/Pu fuel cycle with light-water reactors serving as the consumers of the hybrid-bred fissile fuel; the specific scenarios examined required reprocessing and refabrication of the bred fuel before introduction into the fission reactor. This combination of technologies was chosen to illustrate the manner in which the hybrid reactor concept could serve the needs of, and use the technology of, the fission reactor industry as it now exists (and as it was thought it would evolve). However, the current U.S. Administration has expressed strong concerns about proliferation of nuclear weapons capability and terrorist diversion of weapons-grade nuclear materials. These concerns are based on the projected technology for the light-water reactor/fast breeder reactor using the U/Pu fuel cycle and extensive reprocessing/refabrication. A symbiotic nuclear power generation concept (hybrid fissile producer plus fission burner reactors) is described which eliminates those aspects of the present nuclear fuel cycle that (may) represent significant proliferation/diversion risks. Specifically, the proposed concept incorporates the following features: (1)Th/U 233 fuel cycle, (2) no reprocessing or fabrication of fissile material, and (3) no fissile material in a weapons-grade state

Feasibility study on fission moly target development

International Nuclear Information System (INIS)

Kim, Byung Ku; Kim, Seong Nyun; Shon, Dong Seong; Choi, Chang Beom; Lee, Jae Kuk; Park, Jin Ho; Jeong, Won Myung; Jeon, Kwan Sik; You, Jae Hyung; Kang, Kyung Chul; Ahn, Jong Hwan; Ju, Po Kuk

1996-01-01

A multi-purpose research reactor, HANARO has been operated on the beginning of 1995 and can be utilized for production of various radioisotopes. And a R and D program for fission Mo production was established, and the technical and economical feasibility study has been performed for fission Mo production in Korea. In this study the process for fission Mo production was recommended as follows; 1. Target : UO 2 of annulus type. 2. Separation and purification : Nitric acid dissolution → Alumina adsorption → Benzoin oxime precipitation → Alumina adsorption. And more desirable plan for steady supply of fission Mo were suggested in following viewpoints; 1. Technical collaboration with foreign company. 2. Backup supply system. 3. Marketing arrangement. (Author)

Mirror hybrid reactors

International Nuclear Information System (INIS)

Moir, R.W.

1978-01-01

The fusion-fission hybrid is a combination of the fusion and fission processes, having features which are complementary. Fission energy is running out of readily available fuel, and fusion has extra neutrons which can be used to breed that fission fuel. Fusion would have to take on an extra burden of radioactivity, but this early application would give fusion, which does not work well enough now to make power, practical experience which may accelerate development of pure fusion

New hybrid systems

International Nuclear Information System (INIS)

Bernardin, B.

2001-01-01

New hybrid systems are made up of a subcritical core, a spallation target and a proton accelerator. The neutrons that are produced in the target by the flux of protons are necessary to maintain the chain reaction of fission. Some parameters that are important for a classical nuclear reactor like doppler coefficient or delayed neutron fraction do not matter in a hybrid system. In a PWR-type reactor or in a fast reactor the concentration of actinides has a bad impact on these 2 parameters, so it is justified to study hybrid systems as actinide transmuters. The hybrid system, because of its external source of neutrons can put aside an important reactivity margin. This reactivity margin can be used to design safer nuclear reactors (particularly in some situations of reactivity accidents) or to irradiate fuel elements containing high concentrations of minor actinides that could not be allowed in a classical reactor. This article reviews various ways of integrating hybrid systems in a population of already existing nuclear reactors in order to manage quantities of plutonium, of minor actinides or of long-life fission products. (A.C.)

Conceptual design study for a laser fusion hybrid

International Nuclear Information System (INIS)

Maniscalco, J.A.

1976-09-01

Lawrence Livermore Laboratory and Bechtel Corporation have been involved in a joint effort to conceptually design a laser fusion hybrid reactor. The design which has evolved is a depleted-uranium fueled fast-fission blanket which produces fissile plutonium and electricity. A major objective of the design study was to evaluate the feasibility of producing fissile fuel with laser fusion. This feasibility evaluation was carried out by analyzing the integrated engineering performance of the complete conceptual design and by identifying the required laser/pellet performance. The performance of the laser fusion hybrid has also been compared to a typical fast breeder reactor. The results show that the laser fusion hybrid produces enough fissile material to fuel more than six light water reactors (LWR's) of equivalent thermal power while operating in a regime which requires an order of magnitude less laser and pellet performance than pure laser fusion. In comparison to a fast breeder reactor the hybrid produces 10 times more fissile fuel. An economic analysis of the design shows that the cost of electricity in a combined hybrid-LWR scenario is insensitive to the capital cost of the hybrid, increasing by only 20 to 40 percent when the capital cost of the hybrid ranges from 2 to 3 times more than an LWR

Neutronic performance of a fusion-fission hybrid reactor designed for fuel enrichment for LWRs

International Nuclear Information System (INIS)

Yapici, H.; Baltacioglu, E.

1997-01-01

In this study, the breeding performance of a fission hybrid reactor was analyzed to provide fissile fuel for Light Water Reactors (LWR) as an alternative to the current methods of gas diffusion and gas centrifuge. LWR fuel rods containing UO 2 or ThO 2 fertile material were located in the fuel zone of the blanket and helium gas or Flibe (Li 2 BeF 4 ) fluid was used as coolant. As a result of the analysis, according to fusion driver (D,T and D,D) and the type of coolant the enrichment of 3%-4% were achieved for operation periods of 12 and 36 months in case of fuel rods containing UO 2 , respectively and for operation periods of 18 and 48 months in case of fuel rods containing ThO 2 , respectively. Depending on the type of fusion driver, coolant and fertile fuel, varying enrichments of between 3% and 8.9% were achieved during operation period of four years

Analytical definition of fission chain reaction parameters for cylindrical uranium bar and energy release evaluations for HIF hybrid targets

International Nuclear Information System (INIS)

Imshennik, V.S.

2006-01-01

Within the conditions of Heavy-Ion Fusion (HIF) arises a possibility to obtain the fission chain reaction for a cylindrical HIF target. The paper contains the solution interpolated with the diffusion approximation in order to receive the general approximation expressions for the bar critical radius as well as for over-critical state. The obtained critical parameters generalized for uranium envelope are used for rough evaluation of the energy release in HIF hybrid targets [ru

Development and testing of multigroup library with correction of self-shielding effects in fusion-fission hybrid reactor

International Nuclear Information System (INIS)

Zou Jun; He Zhaozhong; Zeng Qin; Qiu Yuefeng; Wang Minghuang

2010-01-01

A multigroup library HENDL2.1/SS (Hybrid Evaluated Nuclear Data Library/Self-Shielding) based on ENDF/B-VII.0 evaluate data has been generated using Bondarenko and flux calculator method for the correction of self-shielding effect of neutronics analyses. To validate the reliability of the multigroup library HENDL2.1/SS, transport calculations for fusion-fission hybrid system FDS-I were performed in this paper. It was verified that the calculations with the HENDL2.1/SS gave almost the same results with MCNP calculations and were better than calculations with the HENDL2.0/MG which is another multigroup library without self-shielding correction. The test results also showed that neglecting resonance self-shielding caused underestimation of the K eff , neutron fluxes and waste transmutation ratios in the multigroup calculations of FDS-I.

First wall material damage induced by fusion-fission neutron environment

Energy Technology Data Exchange (ETDEWEB)

Khripunov, Vladimir, E-mail: Khripunov_VI@nrcki.ru

2016-11-01

Highlights: • The highest damage and gas production rates are experienced within the first wall materials of a hybrid fusion-fission system. • About ∼2 times higher dpa and 4–5 higher He appm are expected compared to the values distinctive for a pure fusion system at the same DT-neutron wall loading. • The specific nuclear heating may be increased by a factor of ∼8–9 due to fusion and fission neutrons radiation capture in metal components of the first wall. - Abstract: Neutronic performance and inventory analyses were conducted to quantify the damage and gas production rates in candidate materials when used in a fusion-fission hybrid system first wall (FW). The structural materials considered are austenitic SS, Cu-alloy and V- alloys. Plasma facing materials included Be, and CFC composite and W. It is shown that the highest damage rates and gas particles production in materials are experienced within the FW region of a hybrid similar to a pure fusion system. They are greatly influenced by a combined neutron energy spectrum formed by the two-component fusion-fission neutron source in front of the FW and in a subcritical fission blanket behind. These characteristics are non-linear functions of the fission neutron source intensity. Atomic displacement damage production rate in the FW materials of a subcritical system (at the safe subcriticality limit of ∼0.95 and the neutron multiplication factor of ∼20) is almost ∼2 times higher compared to the values distinctive for a pure fusion system at the same 14 MeV neutron FW loading. Both hydrogen (H) and helium (He) gas production rates are practically on the same level except of about ∼4–5 times higher He-production in austenitic and reduced activation ferritic martensitic steels. A proper simulation of the damage environment in hybrid systems is required to evaluate the expected material performance and the structural component residence times.

Neutronics study on hybrid reactor cooled by helium, water and molten salt

International Nuclear Information System (INIS)

Li Zaixin; Feng Kaiming; Zhang Guoshu; Zheng Guoyao; Zhao Fengchao

2009-01-01

There is no serious magnetohydrodynamics (MHD) problem when helium,water or molten salt of Flibe flows in high magnetic field. Thus helium, water and Flibe were proposed as candidate of coolant for fusion-fission hybrid reactor based on magnetic confinement. The effect on neutronics of hybrid reactor due to coolant was investigated. The analyses of neutron spectra and fuel breeding of blanket with different coolants were performed. Variations of tritium breeding ratio (TBR), blanket energy multiplication (M) and keff with operating time were also studied. MCNP code was used for neutron transport simulation. It is shown that spectra change greatly with different coolants. The blanket with helium exhibits very hard spectrum and good tritium breeding ability. And fission reactions are mainly from fast neutron. The blanket with water has soft spectrum and high energy multiplication factor. However, it needs to improve TBR. The blanket with Flibe has hard spectrum and less energy release. (authors)

Theoretical study of fission dynamics with muons

International Nuclear Information System (INIS)

Oberacker, V.E.; Umar, A.S.; Bottcher, C.; Strayer, M.R.; Maruhn, J.A.; Frankfurt Univ.

1992-01-01

Following muon capture by actinide atoms, some of the inner shell muonic transitions proceed by inverse internal conversion, i.e. the excitation energy of the muonic atom is transferred to the nucleus. In particular, the muonic E2:(3d→1s) transition energy is close to the peak of the isoscalar giant quadrupole resonance in actinide nuclei which exhibits a large fission width. Prompt fission in the presence of a bound muon allows us to study the dynamics of large-amplitude collective motion. We solve the time-dependent Dirac equation for the muonic spinor wave function in the Coulomb field of the fissioning nucleus on a 3-dimensional lattice and demonstrate that the muon attachment probability to the light fission fragment is a measure of the nuclear energy dissipation between the outer fission barrier and the scission point

Conceptual design study for a laser fusion hybrid

International Nuclear Information System (INIS)

Maniscalco, J.A.

1976-01-01

Lawrence Livermore Laboratory and Bechtel Corporation have been involved in a joint effort to conceptually design a laser fusion hybrid reactor. The design which has evolved is a depleted-uranium fueled fast-fission blanket which produces fissile plutonium and electricity. A major objective of the design study was to evaluate the feasibility of producing fissile fuel with laser fusion. This feasibility evaluation was carried out by analyzing the integrated engineering performance of the complete conceptual design and by identifying the required laser/pellet performance. The performance of the laser fusion hybrid has also been compared to a typical fast breeder reactor. The results show that the laser fusion hybrid produces enough fissile material to fuel more than six light water reactors (LWRs) of equivalent thermal power while operating in a regime which requires an order of magnitude less laser and pellet performance than pure laser fusion. In comparison to a fast breeder reactor the hybrid produces 10 times more fissile fuel. An economic analysis of the design shows that the cost of electricity in a combined hybrid-LWR scenario increases by only 20 to 40 percent when the capital cost of the hybrid ranges from 2 to 3 times more than an LWR

Opimization of fusion-driven fissioning systems

International Nuclear Information System (INIS)

Chapin, D.L.; Mills, R.G.

1976-01-01

Potential advantages of hybrid or fusion/fission systems can be exploited in different ways. With selection of the 238 U-- 239 Pu fuel cycle, we show that the system has greatest value as a power producer. Numerical examples of relative revenue from power production vs. 239 Pu production are discussed, and possible plant characteristics described. The analysis tends to show that the hybrid may be more economically attractive than pure fusion systems

Fission theory and actinide fission data

Energy Technology Data Exchange (ETDEWEB)

Michaudon, A.

1975-06-01

The understanding of the fission process has made great progress recently, as a result of the calculation of fission barriers, using the Strutinsky prescription. Double-humped shapes were obtained for nuclei in the actinide region. Such shapes could explain, in a coherent manner, many different phenomena: fission isomers, structure in near-threshold fission cross sections, intermediate structure in subthreshold fission cross sections and anisotropy in the emission of the fission fragments. A brief review of fission barrier calculations and relevant experimental data is presented. Calculations of fission cross sections, using double-humped barrier shapes and fission channel properties, as obtained from the data discussed previously, are given for some U and Pu isotopes. The fission channel theory of A. Bohr has greatly influenced the study of low-energy fission. However, recent investigation of the yields of prompt neutrons and γ rays emitted in the resonances of {sup 235}U and {sup 239}Pu, together with the spin determination for many resonances of these two nuclei cannot be explained purely in terms of the Bohr theory. Variation in the prompt neutron and γ-ray yields from resonance to resonance does not seem to be due to such fission channels, as was thought previously, but to the effect of the (n,γf) reaction. The number of prompt fission neutrons and the kinetic energy of the fission fragments are affected by the energy balance and damping or viscosity effects in the last stage of the fission process, from saddle point to scission. These effects are discussed for some nuclei, especially for {sup 240}Pu.

Parametric systems analysis for tandem mirror hybrids

International Nuclear Information System (INIS)

Lee, J.D.; Chapin, D.L.; Chi, J.W.H.

1980-09-01

Fusion fission systems, consisting of fissile producing fusion hybrids combining a tandem mirror fusion driver with various blanket types and net fissile consuming LWR's, have been modeled and analyzed parametrically. Analysis to date indicates that hybrids can be competitive with mined uranium when U 3 O 8 cost is about 100 $/lb., adding less than 25% to present day cost of power from LWR's. Of the three blanket types considered, uranium fast fission (UFF), thorium fast fission (ThFF), and thorium fission supressed (ThFS), the ThFS blanket has a modest economic advantage under most conditions but has higher support ratios and potential safety advantages under all conditions

Investigation of tritium and 233U breeding in a fission-fusion hybrid reactor fuelling with ThO2

International Nuclear Information System (INIS)

Yildiz, K.; Sahin, S.; Sahin, H. M.; Acir, A.; Yalcin, S.; Altinok, T.; Bayrak, M.; Alkan, M.; Durukan, O.

2007-01-01

In the world, thorium reserves are three times more than natural Uranium reserves. It is planned in the near future that nuclear reactors will use thorium as a fuel. Thorium is not a fissile isotope because it doesn't make fission with thermal neutrons so it could be converted to 2 33U isotope which has very high quality fission cross-section with thermal neutrons. 2 33U isotope can be used in present LWRs as an enrichment fuel. In the fusion reactors, tritium is the most important fossil fuel. Because tritium is not natural isotope, it has to be produced in the reactor. The purpose of this work is to investigate the tritium and 2 33U breeding in a fission-fusion hybrid reactor fuelling with ThO 2 for Δt=10 days during a reactor operation period in five years. The neutronic analysis is performed on an experimental hybrid blanket geometry. In the center of the hybrid blanket, there is a line neutron source in a cylindrical cavity, which simulates the fusion plasma chamber where high energy neutrons (14.1 MeV) are produced. The conventional fusion reaction delivers the external neutron source for blankets following, 2 D + 3 T →? 4 He (3.5 MeV) + n (14.1 MeV). (1) The fuel zone made up of natural-ThO 2 fuel and it is cooled with different coolants. In this work, five different moderator materials, which are Li 2 BeF 4 , LiF-NaF-BeF 2 , Li 2 0Sn 8 0, natural Lithium and Li 1 7Pb 8 3, are used as coolants. The radial reflector, called tritium breeding zones, is made of different Lithium compounds and graphite in sandwich structure. In the work, eight different Lithium compounds were used as tritium breeders in the tritium breeding zones, which are Li 3 N, Li 2 O, Li 2 O 2 , Li 2 TiO 3 , Li 4 SiO 3 , Li 2 ZrO 3 , LiBr and LiH. Neutron transport calculations are conducted in spherical geometry with the help of SCALE4.4A SYSTEM by solving the Boltzmann transport equation with code CSAS and XSDRNPM, under consideration of unresolved and resolved resonances, in S 8 -P 3

Fission blanket benchmark experiment on spherical assembly of uranium and PE with PE reflector

Energy Technology Data Exchange (ETDEWEB)

Zhu, Tonghua; Lu, Xinxin; Wang, Mei; Han, Zijie, E-mail: neutron_integral@aliyun.com; Jiang, Li; Wen, Zhongwei; Liu, Rong

2016-04-15

Highlights: • The fission rate distribution on two depleted uranium assemblies was measured with plate fission chambers. • We do calculations using MCNP code and ENDF/B-V.0 library. • The overestimation of calculations to the measured fission rates was found. • The observed discrepancy are discussed. - Abstract: New concept of fusion-fission hybrid for energy generation has been proposed. To validate the nuclear performance of fission blanket of hybrid, as part of series of validation experiment, two types of fission blanket assemblies were setup in this work and measurements were made of the reaction rate distribution for uranium fission in the spherical assembly of depleted uranium and polyethylene by Plate Fission Chamber (PFC). There are two PFCs in experiment, one is depleted uranium chamber and the other is enriched uranium chamber. The Monte-Carlo transport code MCNP5 and continuous energy cross sections library ENDF/BV.0 were used for the analysis of fission rate distribution in the two types of assemblies. The calculated results were compared with the experimental ones. The overestimation of fission rate for depleted uranium and enriched uranium were found in the inner boundary of the two assemblies. However, the C/E ratio tends to decrease for the distance from the core slightly and the results for enriched uranium are better than that for depleted uranium.

Comparison of the recently proposed super-Marx generator approach to thermonuclear ignition with the deuterium-tritium laser fusion-fission hybrid concept by the Lawrence Livermore National Laboratory

International Nuclear Information System (INIS)

Winterberg, F.

2009-01-01

The recently proposed super-Marx generator pure deuterium microdetonation ignition concept is compared to the Lawrence Livermore National Ignition Facility (NIF) Laser deuterium-tritium fusion-fission hybrid concept (LIFE). In a super-Marx generator, a large number of ordinary Marx generators charge up a much larger second stage ultrahigh voltage Marx generator from which for the ignition of a pure deuterium microexplosion an intense GeV ion beam can be extracted. Typical examples of the LIFE concept are a fusion gain of 30 and a fission gain of 10, making up a total gain of 300, with about ten times more energy released into fission as compared to fusion. This means the substantial release of fission products, as in fissionless pure fission reactors. In the super-Marx approach for the ignition of pure deuterium microdetonation, a gain of the same magnitude can, in theory, be reached. If feasible, the super-Marx generator deuterium ignition approach would make lasers obsolete as a means for the ignition of thermonuclear microexplosions

Event tree analysis for the system of hybrid reactor

International Nuclear Information System (INIS)

Yang Yongwei; Qiu Lijian

1993-01-01

The application of probabilistic risk assessment for fusion-fission hybrid reactor is introduced. A hybrid reactor system has been analysed using event trees. According to the character of the conceptual design of Hefei Fusion-fission Experimental Hybrid Breeding Reactor, the probabilities of the event tree series induced by 4 typical initiating events were calculated. The results showed that the conceptual design is safe and reasonable. through this paper, the safety character of hybrid reactor system has been understood more deeply. Some suggestions valuable to safety design for hybrid reactor have been proposed

Contribution to the study of nuclear fission

International Nuclear Information System (INIS)

Serot, O.

2009-09-01

The author proposes an overview of his research activity during the past fifteen years and more particularly that dealing with nuclear fission. The first part reports works on nucleus physics at the scission via the investigation of ternary fission (experimental procedure, influence of fission modes, influence of resonance spin, influence of excitation energy of the fissioning nucleus, emission probabilities, energy spectra of ternary alphas and tritons, emission mechanism). The second part reports measurements and assessments of neutron-induced fission cross sections. The third part reports the investigation of some properties of fission products (efficiencies, branching ratios of the main delayed neutron precursors)

Motivational study for an hybrid demonstrator

International Nuclear Information System (INIS)

Boidron, M.; Fiorini, G.L.; Thomas, J.B.

2001-02-01

This document recalls first the role of hybrid accelerator driven systems (ADS) in the domain of transmutation of long-lived fission products and minor actinides. It presents the specific contribution of these systems in the management of radioactive wastes and their technical feasibility and safety aspects. Then, follows a motivational analysis for the construction of a demonstration facility with its specifications and R and D needs: feasibility, schedule, links with other ADS-related programs, cost, international cooperation, recommendations. (J.S.)

Study of the number of neutrons produced by fission of 239Pu

International Nuclear Information System (INIS)

Jacob, M.

1958-01-01

Study of the number of neutrons produced by fission of 239 Pu. The counting by coincidence of fissions and neutrons produced by these fissions allows the study of the variation of the mean number of neutrons emitted by ν fission. In the first chapter, it studied the variation of the mean number of neutrons emitted by 239 Pu fission with the energy of the incident neutron. A description of the experiment is given: a spectrometer with a crystal of sodium chloride or beryllium (mounted on a goniometer) is used, a fission chamber containing 10 mg of 239 Pu and the neutron detection system constituted of BF 3 counters which are enriched in 10 B. In the second part, the counting by coincidence of fissions and neutrons produced by the same fission and received by two different groups of counters allow the determination of a relationship between the root mean square and the average of neutron number produced by fission. The variation of the mean number of neutrons emitted by fission of 239 Pu is studied when we change from a thermal spectra of neutrons to a fission spectra of incident neutrons. Finally, when separating in two different part the fission chamber, it is possible to measure the mean number of neutrons emitted from fission of two different sources. It compared the mean number of neutrons emitted by fission of 239 Pu and 233 U. (M.P.)

Recent progress in the study of fission reaction

International Nuclear Information System (INIS)

Blons, J.; Paya, D.; Signarbieux, C.

1977-01-01

The different steps of the fission phenomenon are briefly recalled before a more detailed study of the static aspect of the fission barrier crossing. The experiments performed at Saclay during the last few years seem to confirm the calculations according to which a triple humped fission barrier is expected for the thorium isotopes. The last part deals with some dynamical aspects of the process. Recent results are presented which tend to prove that the nuclear viscosity decreases when the excitation energy increases [fr

Fission--fusion systems: classification and critique

International Nuclear Information System (INIS)

Lidsky, L.M.

1974-01-01

A useful classification scheme for hybrid systems is described and some common features that the scheme makes apparent are pointed out. The early history of fusion-fission systems is reviewed. Some designs are described along with advantages and disadvantages of each. The extension to low and moderate Q devices is noted. (U.S.)

Progress on the conceptual design of a mirror hybrid fusion--fission reactor

International Nuclear Information System (INIS)

Moir, R.W.; Lee, J.D.; Burleigh, R.J.

1975-01-01

A conceptual design study was made of a fusion-fission reactor for the purpose of producing fissile material and electricity. The fusion component is a D-T plasma confined by a pair of magnetic mirror coils in a Yin-Yang configuration and is sustained by neutral beam injection. The neutrons from the fusion plasma drive the fission assembly which is composed of natural uranium carbide fuel rods clad with stainless steel and helium cooled. It was shown conceptually how the reactor might be built using essentially present-day technology and how the uranium-bearing blanket modules can be routinely changed to allow separation of the bred fissile fuel

Motivational study for an hybrid demonstrator; Dossier de motivation pour un demonstrateur hybride

Energy Technology Data Exchange (ETDEWEB)

Boidron, M.; Fiorini, G.L.; Thomas, J.B. [CEA Cadarache, 13 - Saint Paul lez Durance (France). Direction des Reacteurs Nucleaires; Flocard, H. [Institut National de Physique Nucleaire et de Physique des Particules (CNRS/IN2P3), 75 - Paris (France)

2001-02-15

This document recalls first the role of hybrid accelerator driven systems (ADS) in the domain of transmutation of long-lived fission products and minor actinides. It presents the specific contribution of these systems in the management of radioactive wastes and their technical feasibility and safety aspects. Then, follows a motivational analysis for the construction of a demonstration facility with its specifications and R and D needs: feasibility, schedule, links with other ADS-related programs, cost, international cooperation, recommendations. (J.S.)

Post-irradiation studies on knock-out and pseudo-recoil releases of fission products from fissioning UO2

International Nuclear Information System (INIS)

Yamagishi, S.; Tanifuji, T.

1976-01-01

By using post-irradiation techniques, in-pile releases of 133 Xe, sup(85m)Kr, 88 Kr, 87 Kr and 138 Xe from UO 2 fissioning at low temperatures below about 200 0 C are studied: these are analyzed into a time-dependent knock-out and time-independent pseudo-recoil releases. For the latter, a 'self knock-out' mechanism is proposed: when a fission fragment loses thoroughly its energy near the UO 2 surface and stops there, it will knock out the surface substances and accordingly the fragment (i.e. the fission product) will be released. The effective thickness of the layer where the self knock-out occurs is found to be approximately 7A. As for the knock-out release, the following is estimated from its dependence on various factors: the knock-out release of fission products occurs from the surface layer with the effective thickness of approximately 20A: the shape of UO 2 matrix knocked out by one fission fragment passing through the surface is equivalent to a cylinder approximately 32A diameter by approximately 27A thick, (i.e. the knock-out coefficient for UO 2 is approximately 660 uranium atoms per knock-out event). On the basis of the above estimations, the conclusions derived from the past in-pile studies of fission gas releases are evaluated. (Auth.)

Fission-track studies of uranium distribution in geological samples

International Nuclear Information System (INIS)

Brynard, H.J.

1983-01-01

The standard method of studying uranium distribution in geological material by registration of fission tracks from the thermal neutron-induced fission of 235 U has been adapted for utilisation in the SAFARI-1 reactor at Pelindaba. The theory of fission-track registration as well as practical problems are discussed. The method has been applied to study uranium distribution in a variety of rock types and the results are discussed in this paper. The method is very sensitive and uranium present in quantities far below the detection limit of the microprobe have been detected

Workshop summaries for the third US/USSR symposium on fusion-fission reactors

International Nuclear Information System (INIS)

Jassby, D.L.

1979-07-01

Workshop summaries on topics related to the near-term development requirements for fusion-fission (hybrid) reactors are presented. The summary topics are as follows: (1) external factors, (2) plasma engineering, (3) ICF hybrid reactors, (4) blanket design, (5) materials and tritium, and (6) blanket engineering development requirements

Economic implications of fusion-fission energy systems

International Nuclear Information System (INIS)

Deonigi, D.E.; Schulte, S.C.

1979-04-01

The principal conclusions that can be made based on the estimated costs reported in this paper are twofold. First, hybrid reactors operating symbiotically with conventional fission reactors are a potentially attractive supply alternative. Estimated hybrid energy system costs are slightly greater than estimated costs of the most attractive alternatives. However, given the technological, economic, and institutional uncertainties associated with future energy supply, differences of such magnitude are of little significance. Second, to be economically viable, hybrid reactors must be both fuel producers and electricity producers. A data point representing each hybrid reactor driver-blanket concept is plotted as a function of net electrical production efficiency and annual fuel production. The plots illustrate that the most economically viable reactor concepts are those that produce both fuel and electricity

Nuclear fission and fission-product spectroscopy: 3. International workshop on nuclear fission and fission-product spectroscopy

International Nuclear Information System (INIS)

Goutte, Heloise; Fioni, Gabriele; Faust, Herbert; Goutte, Dominique

2005-01-01

The present book contains the proceedings of the third workshop in a series of workshops previously held in Seyssins in 1994 and 1998. The meeting was jointly organized by different divisions of CEA and two major international laboratories. In the opening address, Prof. B. Bigot, the French High Commissioner for Atomic Energy, outlined France's energy policy for the next few decades. He emphasized the continuing progress of nuclear fission in both technical and economic terms, allowing it to contribute to the energy needs of the planet even more in the future than it does today. Such progress implies a very strong link between fundamental and applied research based on experimental and theoretical approaches. The workshop gathered the different nuclear communities studying the fission process, including topics as the following: - nuclear fission experiments, - spectroscopy of neutron rich nuclei, - fission data evaluation, - theoretical aspects of nuclear fission, - and innovative nuclear systems and new facilities. The scientific program was suggested by an International Advisory Committee. About 100 scientists from 13 different countries attended the conference in the friendly working atmosphere of the Castle of Cadarache in the heart of the Provence. The proceedings of the workshop were divided into 11 sections addressing the following subject matters: 1. Cross sections and resonances (5 papers); 2. Fission at higher energies - I (5 papers); 3. Fission: mass and charge yields (4 papers); 4. Light particles and cluster emission (4 papers); 5. Spectroscopy of neutron rich nuclei (5 papers); 6. Resonances, barriers, and fission times (5 papers); 7. Fragment excitation and neutron emission (4 papers); 8. Mass and energy distributions (4 papers); 9. Needs for nuclear data and new facilities - I (4 papers); 10. Angular momenta and fission at higher Energies - II (3 papers); 11. New facilities - II (2 papers). A poster session of 8 presentations completed the workshop

Study of fission dynamics with the three-dimensional Langevin equations

Energy Technology Data Exchange (ETDEWEB)

Eslamizadeh, H. [Persian Gulf University, Department of Physics, Bushehr (Iran, Islamic Republic of)

2011-11-15

The dynamics of fission has been studied by solving one- and three-dimensional Langevin equations with dissipation generated through the chaos weighted wall and window friction formula. The average prescission neutron multiplicities, fission probabilities and the mean fission times have been calculated in a broad range of the excitation energy for compound nuclei {sup 210}Po and {sup 224}Th formed in the fusion-fission reactions {sup 4}He+{sup 206}Pb, {sup 16}O+{sup 208}Pb and results compared with the experimental data. The analysis of the results shows that the average prescission neutron multiplicities, fission probabilities and the mean fission times calculated by one- and three-dimensional Langevin equations are different from each other, and also the results obtained based on three-dimensional Langevin equations are in better agreement with the experimental data. (orig.)

Studies on the reaction mechanism of the muon induced nuclear fission

International Nuclear Information System (INIS)

Mutius, R. von.

1985-01-01

The mass and energy distribution of the fission fragments after muon induced nuclear fission allows the determination of the mean excitation energy of the fissioning nucleus after muon capture. By the systematic comparison with a mass distribution of a corresponding reaction for the first time for this an accuracy of about 1 MeV could be reached. Theoretical calculations on the excitation probability in the muon capture allow in connection with the fission probability an estimating calculation of this energy. The experimental result represents by this a test criterium for the valuation of the theoretical calculation. The measured probabilities for the occurrence of radiationless transitions in the muonic γ cascade of 237 Np permit an indirect experimental determination of the barrier enhancement which causes the muon present during the fission process. The value found for this extends to 0.75+-0.1 MeV. A change of the mass distribution by the muon cannot be detected in the nuclides 235 U, 237 Np, and 242 Pu studied here. Only the mean total kinetic energy of the fission products is reduced in these three nuclides in the prompt μ - induced fission by 1 to 2 MeV. For this result the incomplete screening of the nuclear charge during the fission process is made responsible. A mass dependence of this reduction has not been stated. Because the muon has appearently no influence on the mass splitting it can be valied as nearly ideal particle in order to study the hitherto little studied dynamics of the fission process. (orig.) [de

Fission dynamics as brought out in cold fragmentation studies

International Nuclear Information System (INIS)

Signarbieux, G.

1986-10-01

Fission dynamics problem has been addressed since the beginning. This paper is specifically concerned by ''even-odd effects '' in fragment distribution. These effects are reinterpreted, some complementary thoughts on double ionization chamber are given together with a study of fission dymanics at low energy [fr

Study of the number of neutrons produced by fission of {sup 239}Pu; Etude du nombre de neutrons produits par la fission de {sup 239}Pu

Energy Technology Data Exchange (ETDEWEB)

Jacob, M [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1958-07-01

Study of the number of neutrons produced by fission of {sup 239}Pu. The counting by coincidence of fissions and neutrons produced by these fissions allows the study of the variation of the mean number of neutrons emitted by {nu} fission. In the first chapter, it studied the variation of the mean number of neutrons emitted by {sup 239}Pu fission with the energy of the incident neutron. A description of the experiment is given: a spectrometer with a crystal of sodium chloride or beryllium (mounted on a goniometer) is used, a fission chamber containing 10 mg of {sup 239}Pu and the neutron detection system constituted of BF{sub 3} counters which are enriched in {sup 10}B. In the second part, the counting by coincidence of fissions and neutrons produced by the same fission and received by two different groups of counters allow the determination of a relationship between the root mean square and the average of neutron number produced by fission. The variation of the mean number of neutrons emitted by fission of {sup 239}Pu is studied when we change from a thermal spectra of neutrons to a fission spectra of incident neutrons. Finally, when separating in two different part the fission chamber, it is possible to measure the mean number of neutrons emitted from fission of two different sources. It compared the mean number of neutrons emitted by fission of {sup 239}Pu and {sup 233}U. (M.P.)

Studies on fission with ALADIN. Precise and simultaneous measurement of fission yields, total kinetic energy and total prompt neutron multiplicity at GSI

International Nuclear Information System (INIS)

Martin, Julie-Fiona; Taieb, Julien; Chatillon, Audrey; Belier, Gilbert; Boutoux, Guillaume; Ebran, Adeline; Gorbinet, Thomas; Grente, Lucie; Laurent, Benoit; Pellereau, Eric; Alvarez-Pol, Hector; Ayyad, Yassid; Benlliure, Jose; Cortina Gil, Dolores; Caamano, Manuel; Fernandez Dominguez, Beatriz; Paradela, Carlos; Ramos, Diego; Rodriguez-Sanchez, Jose-Luis; Vargas, Jossitt; Audouin, Laurent; Tassan-Got, Laurent; Aumann, Thomas; Casarejos, Enrique; Farget, Fanny; Rodriguez-Tajes, Carme; Heinz, Andreas; Jurado, Beatriz; Kelic-Heil, Aleksandra; Kurz, Nikolaus; Nociforo, Chiara; Pietri, Stephane; Rossi, Dominic; Schmidt, Karl-Heinz; Simon, Haik; Voss, Bernd; Weick, Helmut

2015-01-01

A novel technique for fission studies, based on the inverse kinematics approach, is presented. Following pioneering work in the nineties, the SOFIA Collaboration has designed and built an experimental set-up dedicated to the simultaneous measurement of isotopic yields, total kinetic energies and total prompt neutron multiplicities, by fully identifying both fission fragments in coincidence, for the very first time. This experiment, performed at GSI, permits to study the fission of a wide variety of fissioning systems, ranging from mercury to neptunium, possibly far from the valley of stability. A first experiment, performed in 2012, has provided a large array of unprecedented data regarding the nuclear fission process. An excerpt of the results is presented. With this solid starter, further improvements of the experimental set-up are considered, which are consistent with the expected developments at the GSI facility, in order to measure more fission observables in coincidence. The completeness reached in the SOFIA data, permits to scrutinize the correlations between the interesting features of fission, offering a very detailed insight in this still unraveled mechanism. (orig.)

Studies on fission with ALADIN. Precise and simultaneous measurement of fission yields, total kinetic energy and total prompt neutron multiplicity at GSI

Energy Technology Data Exchange (ETDEWEB)

Martin, Julie-Fiona; Taieb, Julien; Chatillon, Audrey; Belier, Gilbert; Boutoux, Guillaume; Ebran, Adeline; Gorbinet, Thomas; Grente, Lucie; Laurent, Benoit; Pellereau, Eric [CEA DAM Bruyeres-le-Chatel, Arpajon (France); Alvarez-Pol, Hector; Ayyad, Yassid; Benlliure, Jose; Cortina Gil, Dolores; Caamano, Manuel; Fernandez Dominguez, Beatriz; Paradela, Carlos; Ramos, Diego; Rodriguez-Sanchez, Jose-Luis; Vargas, Jossitt [Universidad de Santiago de Compostela, Santiago de Compostela (Spain); Audouin, Laurent; Tassan-Got, Laurent [CNRS/IN2P3, IPNO, Orsay (France); Aumann, Thomas [Technische Universitaet Darmstadt, Darmstadt (Germany); Casarejos, Enrique [Universidad de Vigo, Vigo (Spain); Farget, Fanny; Rodriguez-Tajes, Carme [CNRS/IN2P3, GANIL, Caen (France); Heinz, Andreas [Chalmers University of Technology, Gothenburg (Sweden); Jurado, Beatriz [CNRS/IN2P3, CENBG, Gradignan (France); Kelic-Heil, Aleksandra; Kurz, Nikolaus; Nociforo, Chiara; Pietri, Stephane; Rossi, Dominic; Schmidt, Karl-Heinz; Simon, Haik; Voss, Bernd; Weick, Helmut [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany)

2015-12-15

A novel technique for fission studies, based on the inverse kinematics approach, is presented. Following pioneering work in the nineties, the SOFIA Collaboration has designed and built an experimental set-up dedicated to the simultaneous measurement of isotopic yields, total kinetic energies and total prompt neutron multiplicities, by fully identifying both fission fragments in coincidence, for the very first time. This experiment, performed at GSI, permits to study the fission of a wide variety of fissioning systems, ranging from mercury to neptunium, possibly far from the valley of stability. A first experiment, performed in 2012, has provided a large array of unprecedented data regarding the nuclear fission process. An excerpt of the results is presented. With this solid starter, further improvements of the experimental set-up are considered, which are consistent with the expected developments at the GSI facility, in order to measure more fission observables in coincidence. The completeness reached in the SOFIA data, permits to scrutinize the correlations between the interesting features of fission, offering a very detailed insight in this still unraveled mechanism. (orig.)

Study of transfer induced fission and fusion-fission reactions for 28 Si + 232 Th system at 340 MeV

International Nuclear Information System (INIS)

Prete, G.; Rizzi, V.; Fioretto, E.; Cinausero, M.; Shetty, D.V.; Pesente, S.; Brondi, A.; La Rana, G.; Moro, R.; Vardaci, E.; Boiano, A.; Ordine, A.; Gelli, N.; Lucarelli, F.; Bortignon, P.F.; Saxena, A.; Nayak, B.K.; Biswas, D.C.; Choudhury, R.K.; Kapoor, R.S.

2001-01-01

Full text: Fission induced by nucleons transfer has been investigated in the reaction 28 Si + 232 Th at 340 MeV. Looking at the projectile-like-fragments (PLF), the fission yield increases as the transfer increases, but a decreases is observed for transfers with DZ . Light charged particles in coincidence with PLF and Fission have been detected with large solid angle and show an increasing multiplicity as the Z of PLF is reduced and a constant value when fission is requested. The present results indicate inhibition of transfer induced fission reaction for higher Z transfer and increasing probability for decay through charged particle evaporation. Fission is the dominant decay process in heavy reactions involving fissile systems but the dynamical evolution of the composite system is largely governed by the formation and decay mechanisms. Important insight into the formation and the survival probability of the heavy composite nuclei formed in heavy ion collisions can be gained by simultaneously investigate the fission process and light particle emission over a continuous range of excitation energy, angular momentum and fissility. This can be achieved by studying fission induced by transfer of nucleons between the interacting projectile and the target nucleus. In the present work, we have carried out measurements on multinucleon transfer induced fission reactions in 28 Si + 232 Th system at Elab = 340 MeV. The experiment has been performed at the Laboratori Nazionale di Legnaro (LNL) using the 8pLP detector in its final configuration with 257 DE-E telescopes. The backward detectors were used to measure both light charged particles and fission fragments. The projectile-like fragments were detected using separate DE-E telescopes around the grazing angle. Two neutron detectors were placed at a distance of 115.5 cm from the target to measure neutrons emitted in coincidence with fission fragments. Here we present the results of the data analysis of transfer induced fission

Role of fission-reactor-testing capabilities in the development of fusion technology

International Nuclear Information System (INIS)

Hsu, P.Y.; Deis, G.A.; Longhurst, G.R.; Miller, L.G.; Schmunk, R.E.; Takata, M.L.; Watts, K.D.

1981-01-01

Testing of fusion materials and components in fission reactors will be increasingly important in the future due to the near-term lack of fusion engineering test devices, and the long-term high demand for testing when fusion reactors become available. Fission testing is capable of filling many gaps in fusion reactor design information, and thus should be aggressively pursued. EG and G Idaho has investigated the application of fission testing in three areas, which are discussed in this paper. First, we investigated radiation damage to magnet insulators. This work is now continuing with the use of an improved test capsule. Second, a study was performed which indicated that a fission-suppressed hybrid blanket module could be effectively tested in a reactor such as the Engineering Test Reactor (ETR), closely reproducing the predicted performance in a fusion environment. Finally, we explored a conceptual design for a fission-based Integrated Test Facility (ITF), which can accommodate entire First Wall/Blanket (FW/B) modules for testing in a nuclear environment, simultaneously satisfying many of the FW/B test requirements. This ITF can provide a cyclic neutron/gamma flux, as well as the necessary module support functions

Present status of the EPFL (Swiss) fusion-fission experiment 'LOTUS'

International Nuclear Information System (INIS)

Haldy, P.A.; Frueh, R.; Ligou, J.; Schneeberger, J.P.; Kumar, A.

1984-01-01

The present status of the LOTUS project - a fusion-fission hybrid research facility under construction at the Ecole Polytechnique Federale de Lausanne (EPFL) Switzerland - is presented. Emphasis is places on the description of the facility and on the design studies of an initial blanket of the ''fission-suppressed'' type. The LOTUS facility consists of a parallelepiped-shaped blanket, occupying roughly a volume of 1 m 3 , driven by a sealed 14 MeV (D,T) neutron generator with a rated source strength of 5x10 12 n/s. The experiment is housed in a massive concrete shielding of 220 cm thick walls, which leaves an experimental test chamber of 360 cm by 240 cm lateral dimensions and a height of 300 cm. (orig.) [de

Major features of a mirror fusion--fast fission hybrid reactor

International Nuclear Information System (INIS)

Moir, R.W.; Lee, J.D.; Burleigh, R.J.

1974-01-01

A conceptual design was made of a fusion-fission reactor. The fusion component is a D-T plasma confined by a pair of magnetic mirror coils in a Yin-Yang configuration and sustained by hot neutral beam injection. The neutrons from the fusion plasma drive the fission assembly which is composed of natural uranium carbide fuel rods clad with stainless steel and is cooled by helium. It was shown how the reactor can be built using essentially present day construction technology and how the uranium bearing blanket modules can be routinely changed to allow separation of the bred fissile fuel of which approximately 1200 kg of plutonium are produced each year along with the approximately 750 MW of electricity. (U.S.)

1978 source book for fusion--fission hybrid systems

International Nuclear Information System (INIS)

Crowley, J.H.; Pavlenco, G.F.; Kaminski, R.S.

1978-12-01

This study summarizes the promise and timing of the hybrid concept and culminates in a generic R and D timetable. This document emphasizes the meaningfulness of the concept to tomorrow's energy needs and energy production systems rather than strict analysis of technical feasibility

Contribution to the study of prompt gamma-rays from fission

International Nuclear Information System (INIS)

Regnier, D.

2013-01-01

This PhD thesis has essentially been motivated by the nuclear heating problematic in reactors. The main goal of this work was the production of methods capable of simulating the prompt gamma emission from fission. First of all, several algorithms for the treatment of the nucleus deexcitation were implemented. They have been successfully tested through various calculations (isomeric branching ratio, total radiative width, etc). These methods were then incorporated in the frame of the fission code FIFRELIN. The tool which results from this work, enables the determination of numerous fission observables in the frame of a single consistent model. A sensitivity study of the results to several numerical and nuclear models has been realized. At last, calculation have been lead for the 252 Cf spontaneous fission and the thermal neutron induced fission of 235 U and 239 Pu. The prompt gamma spectra obtained for those three fissioning systems have been determined. The results are in good agreement with available experimental data, including recent measurements published in 2012 and 2013. (author) [fr

Review of the current status of linear hybrid reactor concepts

International Nuclear Information System (INIS)

Schultz, K.R.

1977-07-01

A review was made of the current status of linear fusion-fission hybrid reactor design studies in the USA. The linear hybrid reactor concepts reviewed include the linear theta-pinch hybrid reactor being studied at Los Alamos Scientific Laboratory, the electron beam-heated solenoid hybrid reactor under development at Physics International Co., the laser-heated solenoid hybrid reactor being investigated at Mathematical Sciences Northwest, Inc., and the linear fusion waste burning reactor being studied at General Atomic Company. The discussion addresses confinement and heating mechanisms for each concept, as well as the hybrid blanket designs. The current state of the four reactor designs is summarized and the performance of the various concepts compared

Natural uranium fueled light water moderated breeding hybrid power reactors

International Nuclear Information System (INIS)

Greenspan, E.; Schneider, A.; Misolovin, A.; Gilai, D.; Levin, P.

The feasibility of fission-fusion hybrid reactors based on breeding light water thermal fission systems is investigated. The emphasis is on fuel-self-sufficient (FSS) hybrid power reactors that are fueled with natural uranium. Other LWHRs considered include FSS-LWHRs that are fueled with spent fuel from LWRs, and LWHRs which are to supplement LWRs to provide a tandem LWR-LWHR power economy that is fuel-self-sufficient

Nuclear fission and reactions

International Nuclear Information System (INIS)

Anon.

1975-01-01

The nuclear fission research programs are designed to elucidate basic features of the fission process. Specifically, (1) factors determining how nucleons of a fissioning nucleus are distributed between two fission fragments, (2) factors determining kinetic energy and excitation energies of fragments, and (3) factors controlling fission lifetimes. To these ends, fission studies are reported for several heavy elements and include investigations of spontaneous and neutron-induced fission, heavy ion reactions, and high energy proton reactions. The status of theoretical research is also discussed. (U.S.)

Some applications of fission-based testing capabilities in the development of fusion technology

International Nuclear Information System (INIS)

Hsu, P.Y.; Deis, G.A.; Longhurst, G.R.; Masson, L.S.; Miller, L.G.; Schmunk, R.E.; Takata, M.L.; Watts, K.D.

1981-10-01

The testing of fusion materials and components in fission reactors will be increasingly important in the future due to the near-term lack of fusion engineering test devices, and the long-term high demand for fusion testing when they do become available. Fission testing is capable of filling many gaps in fusion reactor design information, and should be aggressively pursued. EG and G Idaho has investigated the application of fission testing in three areas, which are discussed in this paper. First, work was performed on the irradiation of magnet insulators. This work is continuing with an improved test environment. Second, a study was performed which indicated that a fission-suppressed hybrid blanket module could be effectively tested in a reactor such as the Engineering Test Reactor (ETR), closely reproducing the predicted performance in a fusion environment. Finally, a conceptual design is presented for a fission-based Integrated Test Facility (ITF), which can accommodate entire wall/blanket (FW/B) modules for testing in a nuclear environment, simultaneously satisfying many of the FW/B test requirements. This ITF can provide a cyclic neutron/gamma flux, as well as the necessary module support functions

Solidification of residual fission-product solutions; laboratory studies; Solidification de solutions residuaires concentrees de produits de fission: etudes de laboratoire

Energy Technology Data Exchange (ETDEWEB)

Boniaud, R; Cohen, P; Sombret, C [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

1961-07-01

This paper describes the results obtained, at laboratory scale, during the study of the incorporation of fission products into glasses and synthetic micas. The rate of leaching of fission products from the glass and their volatility during firing were measured. A hot cell was built to complete these results. (author) [French] Ce rapport resume le resultat des etudes faites en laboratoire (activite de l'ordre du millicurie) sur l'incorporation des produits de fission dans des verres et micas synthetiques. On a mesure le taux de lixiviation des produits de fission et leur volatilisation au cours de la cuisson. Une cellule chaude a ete installee pour completer ces resultats au moyen d'essais realises avec une activite superieure. (auteur)

Fission Product Yield Study of 235U, 238U and 239Pu Using Dual-Fission Ionization Chambers

Science.gov (United States)

Bhatia, C.; Fallin, B.; Howell, C.; Tornow, W.; Gooden, M.; Kelley, J.; Arnold, C.; Bond, E.; Bredeweg, T.; Fowler, M.; Moody, W.; Rundberg, R.; Rusev, G.; Vieira, D.; Wilhelmy, J.; Becker, J.; Macri, R.; Ryan, C.; Sheets, S.; Stoyer, M.; Tonchev, A.

2014-05-01

To resolve long-standing differences between LANL and LLNL regarding the correct fission basis for analysis of nuclear test data [M.B. Chadwick et al., Nucl. Data Sheets 111, 2891 (2010); H. Selby et al., Nucl. Data Sheets 111, 2891 (2010)], a collaboration between TUNL/LANL/LLNL has been established to perform high-precision measurements of neutron induced fission product yields. The main goal is to make a definitive statement about the energy dependence of the fission yields to an accuracy better than 2-3% between 1 and 15 MeV, where experimental data are very scarce. At TUNL, we have completed the design, fabrication and testing of three dual-fission chambers dedicated to 235U, 238U, and 239Pu. The dual-fission chambers were used to make measurements of the fission product activity relative to the total fission rate, as well as for high-precision absolute fission yield measurements. The activation method was employed, utilizing the mono-energetic neutron beams available at TUNL. Neutrons of 4.6, 9.0, and 14.5 MeV were produced via the 2H(d,n)3He reaction, and for neutrons at 14.8 MeV, the 3H(d,n)4He reaction was used. After activation, the induced γ-ray activity of the fission products was measured for two months using high-resolution HPGe detectors in a low-background environment. Results for the yield of seven fission fragments of 235U, 238U, and 239Pu and a comparison to available data at other energies are reported. For the first time results are available for neutron energies between 2 and 14 MeV.

Singlet exciton fission in polycrystalline pentacene: from photophysics toward devices.

Science.gov (United States)

Wilson, Mark W B; Rao, Akshay; Ehrler, Bruno; Friend, Richard H

2013-06-18

Singlet exciton fission is the process in conjugated organic molecules bywhich a photogenerated singlet exciton couples to a nearby chromophore in the ground state, creating a pair of triplet excitons. Researchers first reported this phenomenon in the 1960s, an event that sparked further studies in the following decade. These investigations used fluorescence spectroscopy to establish that exciton fission occurred in single crystals of several acenes. However, research interest has been recently rekindled by the possibility that singlet fission could be used as a carrier multiplication technique to enhance the efficiency of photovoltaic cells. The most successful architecture to-date involves sensitizing a red-absorbing photoactive layer with a blue-absorbing material that undergoes fission, thereby generating additional photocurrent from higher-energy photons. The quest for improved solar cells has spurred a drive to better understand the fission process, which has received timely aid from modern techniques for time-resolved spectroscopy, quantum chemistry, and small-molecule device fabrication. However, the consensus interpretation of the initial studies using ultrafast transient absorption spectroscopy was that exciton fission was suppressed in polycrystalline thin films of pentacene, a material that would be otherwise expected to be an ideal model system, as well as a viable candidate for fission-sensitized photovoltaic devices. In this Account, we review the results of our recent transient absorption and device-based studies of polycrystalline pentacene. We address the controversy surrounding the assignment of spectroscopic features in transient absorption data, and illustrate how a consistent interpretation is possible. This work underpins our conclusion that singlet fission in pentacene is extraordinarily rapid (∼80 fs) and is thus the dominant decay channel for the photoexcited singlet exciton. Further, we discuss our demonstration that triplet excitons

Fast fission phenomena

International Nuclear Information System (INIS)

Gregoire, Christian.

1982-03-01

Experimental studies of fast fission phenomena are presented. The paper is divided into three parts. In the first part, problems associated with fast fission processes are examined in terms of interaction potentials and a dynamic model is presented in which highly elastic collisions, the formation of compound nuclei and fast fission appear naturally. In the second part, a description is given of the experimental methods employed, the observations made and the preliminary interpretation of measurements suggesting the occurence of fast fission processes. In the third part, our dynamic model is incorporated in a general theory of the dissipative processes studied. This theory enables fluctuations associated with collective variables to be calculated. It is applied to highly inelastic collisions, to fast fission and to the fission dynamics of compound nuclei (for which a schematic representation is given). It is with these calculations that the main results of the second part can be interpreted [fr

Fission yield covariance generation and uncertainty propagation through fission pulse decay heat calculation

International Nuclear Information System (INIS)

Fiorito, L.; Diez, C.J.; Cabellos, O.; Stankovskiy, A.; Van den Eynde, G.; Labeau, P.E.

2014-01-01

Highlights: • Fission yield data and uncertainty comparison between major nuclear data libraries. • Fission yield covariance generation through Bayesian technique. • Study of the effect of fission yield correlations on decay heat calculations. • Covariance information contribute to reduce fission pulse decay heat uncertainty. - Abstract: Fission product yields are fundamental parameters in burnup/activation calculations and the impact of their uncertainties was widely studied in the past. Evaluations of these uncertainties were released, still without covariance data. Therefore, the nuclear community expressed the need of full fission yield covariance matrices to be able to produce inventory calculation results that take into account the complete uncertainty data. State-of-the-art fission yield data and methodologies for fission yield covariance generation were researched in this work. Covariance matrices were generated and compared to the original data stored in the library. Then, we focused on the effect of fission yield covariance information on fission pulse decay heat results for thermal fission of 235 U. Calculations were carried out using different libraries and codes (ACAB and ALEPH-2) after introducing the new covariance values. Results were compared with those obtained with the uncertainty data currently provided by the libraries. The uncertainty quantification was performed first with Monte Carlo sampling and then compared with linear perturbation. Indeed, correlations between fission yields strongly affect the uncertainty of decay heat. Eventually, a sensitivity analysis of fission product yields to fission pulse decay heat was performed in order to provide a full set of the most sensitive nuclides for such a calculation

Study of DD versus DT fusion fuel cycles for different fusion-fission hybrid energy systems

International Nuclear Information System (INIS)

Gohar, Y.; Baker, C.C.

1981-01-01

A study was performed to investigate the characteristics of an energy system to produce fissile fuel for fission reactors. DD and DT fusion reactors were examined in this study with either a thorium or uranium blanket for each fusion reactor. Various fuel cycles were examined for light-water reactors including the denatured fuel cycles (which may offer proliferation resistance compared to other fuel cycles); these fuel cycles include a uranium fuel cycle with 239 Pu makeup, a thorium fuel cycle with 239 Pu makeup, a denatured uranium fuel cycle with 233 U makeup, and a denatured thorium fuel cycle with 233 U makeup. Four different blankets were considered for this study. The first two blankets have a tritium breeding capability for DT reactors. Lithium oxide (Li 2 O) was used for tritium breeding due to its high lithium density and high temperature capability; however, the use of Li 2 O may result in higher tritium inventories compared to other solid breeders

Development of prototype induced-fission-based Pu accountancy instrument for safeguards applications.

Science.gov (United States)

Seo, Hee; Lee, Seung Kyu; An, Su Jung; Park, Se-Hwan; Ku, Jeong-Hoe; Menlove, Howard O; Rael, Carlos D; LaFleur, Adrienne M; Browne, Michael C

2016-09-01

Prototype safeguards instrument for nuclear material accountancy (NMA) of uranium/transuranic (U/TRU) products that could be produced in a future advanced PWR fuel processing facility has been developed and characterized. This is a new, hybrid neutron measurement system based on fast neutron energy multiplication (FNEM) and passive neutron albedo reactivity (PNAR) methods. The FNEM method is sensitive to the induced fission rate by fast neutrons, while the PNAR method is sensitive to the induced fission rate by thermal neutrons in the sample to be measured. The induced fission rate is proportional to the total amount of fissile material, especially plutonium (Pu), in the U/TRU product; hence, the Pu amount can be calibrated as a function of the induced fission rate, which can be measured using either the FNEM or PNAR method. In the present study, the prototype system was built using six (3)He tubes, and its performance was evaluated for various detector parameters including high-voltage (HV) plateau, efficiency profiles, dead time, and stability. The system's capability to measure the difference in the average neutron energy for the FNEM signature also was evaluated, using AmLi, PuBe, (252)Cf, as well as four Pu-oxide sources each with a different impurity (Al, F, Mg, and B) and producing (α,n) neutrons with different average energies. Future work will measure the hybrid signature (i.e., FNEM×PNAR) for a Pu source with an external interrogating neutron source after enlarging the cavity size of the prototype system to accommodate a large-size Pu source (~600g Pu). Copyright © 2016 Elsevier Ltd. All rights reserved.

Neutronic Parametric Study on a Conceptual Design for a Transmutation Fusion Blanket

International Nuclear Information System (INIS)

Tariq Siddique, M.; Kim, Myung Hyun

2011-01-01

Fusion energy may be the one of options of future energy. In all over the world, researchers are putting their efforts for its commercial and economical availability. Fusion-fission hybrid reactors have been studied for various applications in China. First milestone of fusion energy is expected to be the fusion fission hybrid reactors. In fusion-fission hybrid reactor the blanket design is of second prime importance after fusion source. In this study conceptual design of a fusion blanket is initiated for calculation of tritium production, transmutation of minor actinides (MA) and fission products (FP) and energy multiplication calculations

TRISO Fuel Performance: Modeling, Integration into Mainstream Design Studies, and Application to a Thorium-fueled Fusion-Fission Hybrid Blanket

Energy Technology Data Exchange (ETDEWEB)

Powers, Jeffrey James [Univ. of California, Berkeley, CA (United States)

2011-11-30

This study focused on creating a new tristructural isotropic (TRISO) coated particle fuel performance model and demonstrating the integration of this model into an existing system of neutronics and heat transfer codes, creating a user-friendly option for including fuel performance analysis within system design optimization and system-level trade-off studies. The end product enables both a deeper understanding and better overall system performance of nuclear energy systems limited or greatly impacted by TRISO fuel performance. A thorium-fueled hybrid fusion-fission Laser Inertial Fusion Energy (LIFE) blanket design was used for illustrating the application of this new capability and demonstrated both the importance of integrating fuel performance calculations into mainstream design studies and the impact that this new integrated analysis had on system-level design decisions. A new TRISO fuel performance model named TRIUNE was developed and verified and validated during this work with a novel methodology established for simulating the actual lifetime of a TRISO particle during repeated passes through a pebble bed. In addition, integrated self-consistent calculations were performed for neutronics depletion analysis, heat transfer calculations, and then fuel performance modeling for a full parametric study that encompassed over 80 different design options that went through all three phases of analysis. Lastly, side studies were performed that included a comparison of thorium and depleted uranium (DU) LIFE blankets as well as some uncertainty quantification work to help guide future experimental work by assessing what material properties in TRISO fuel performance modeling are most in need of improvement. A recommended thorium-fueled hybrid LIFE engine design was identified with an initial fuel load of 20MT of thorium, 15% TRISO packing within the graphite fuel pebbles, and a 20cm neutron multiplier layer with beryllium pebbles in flibe molten salt coolant. It operated

Source driven breeding fission power reactors and the nuclear energy strategy

International Nuclear Information System (INIS)

Greenspan, E.

The nuclear energy economy is facing severe difficulties associated with low utilization of uranium resources, safety, non-proliferation and environmental issues. Energy policy makers face the dilemma: commercialize LMFBRs immediately with the risk of negative economical, proliferation or other consequences, or continue with R and D programs that will provide the information needed for sounder decisions, but now taking the risk of running out of economically exploitable uranium ore resources. The development of hybrid reactors can provide an assurance against the latter risk and offers many interesting new options for the nuclear energy strategy. Being based on the technology of LWRs and HWRs, Light Water Hybrid Reactors (LWHR) provide a most natural link between the fission reactor technology of the present and the fusion power technology of the future. The investment in their development in excess of that required for the development of fusion power reactors is expected to be relatively small, thus making the development of LWHRs potentially a high benefit-to-cost ratio program. It is recommended that the fission and fusion communities will cooperate in hybrids R and D programs aimed at assessing the technological and economical viability of hybrid reactors as reliably and soon as possible. (author)

Ternary fission

International Nuclear Information System (INIS)

Wagemans, C.

1991-01-01

Since its discovery in 1946, light (charged) particle accompanied fission (ternary fission) has been extensively studied, for spontaneous as well as for induced fission reactions. The reason for this interest was twofold: the ternary particles being emitted in space and time close to the scission point were expected to supply information on the scission point configuration and the ternary fission process was an important source of helium, tritium, and hydrogen production in nuclear reactors, for which data were requested by the nuclear industry. Significant experimental progress has been realized with the advent of high-resolution detectors, powerful multiparameter data acquisition systems, and intense neutron and photon beams. As far as theory is concerned, the trajectory calculations (in which scission point parameters are deduced from the experimental observations) have been very much improved. An attempt was made to explain ternary particle emission in terms of a Plateau-Rayleigh hydrodynamical instability of a relatively long cylindrical neck or cylindrical nucleus. New results have also been obtained on the so-called open-quotes trueclose quotes ternary fission (fission in three about-equal fragments). The spontaneous emission of charged particles has also clearly been demonstrated in recent years. This chapter discusses the main characteristics of ternary fission, theoretical models, light particle emission probabilities, the dependence of the emission probabilities on experimental variables, light particle energy distributions, light particle angular distributions, correlations between light particle accompanied fission observables, open-quotes trueclose quotes ternary fission, and spontaneous emission of heavy ions. 143 refs., 18 figs., 8 tabs

Heavy neutron-deficient radioactive beams: fission studies and fragment distributions

Energy Technology Data Exchange (ETDEWEB)

Schmidt, K.H.; Benlliure, J.; Heinz, A.; Voss, B. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Boeckstiegel, C.; Grewe, A.; Steinhaeuser, S.; Clerc, H.G.; Jong, M. de; Junghans, A.R.; Mueller, J. [Technische Hochschule Darmstadt (Germany). Inst. fuer Kernphysik; Pfuetzner, M. [Warsaw Univ. (Poland). Inst. of Experimental Physics

1998-02-01

The secondary-beam facility of GSI Darmstadt was used to study the fission process of short-lived radioactive nuclei. Relativistic secondary projectiles were produced by fragmentation of a 1 A GeV {sup 238}U primary beam and identified in nuclear charge and mass number. Their production cross sections were determined, and the fission competition in the statistical deexcitation was deduced for long isotopical chains. New results on the enhancement of the nuclear level density in spherical and deformed nuclei due to collective rotational and vibrational excitations were obtained. Using these reaction products as secondary beams, the dipole giant resonance was excited by electromagnetic interactions in a secondary lead target, and fission from excitation energies around 11 MeV was induced. The fission fragments were identified in nuclear charge, and their velocity vectors were determined. Elemental yields and total kinetic energies have been determined for a number of neutron-deficient actinides and preactinides which were not accessible with conventional techniques. The characteristics of multimodal fission of nuclei around {sup 226}Th were systematically investigated and related to the influence of shell effects on the potential energy and on the level density between fission barrier and scission. A systematic view on the large number of elemental yields measured gave rise to a new interpretation of the enhanced production of even elements in nuclear fission and allowed for a new understanding of pair breaking in large-scale collective motion. (orig.)

Enhanced fuel production in thorium fusion hybrid blankets utilizing uranium multipliers

International Nuclear Information System (INIS)

Pitulski, R.H.; Chapin, D.L.; Klevans, E.

1979-01-01

The multiplication of 14 MeV D-T fusion neutrons via (n,2n), (n,3n), and fission reactions by 238 U is well known and established. This study consistently evaluates the effectiveness of a depleted (tails) UO 2 multiplier on increasing the production of 233 U and tritium in a thorium/lithium fusion--fission hybrid blanket. Nuclear performance is evaluated as a function of exposure and zone thickness

Hybrid reactors: Nuclear breeding or energy production?

International Nuclear Information System (INIS)

Piera, Mireia; Lafuente, Antonio; Abanades, Alberto; Martinez-Val, J.M.

2010-01-01

After reviewing the long-standing tradition on hybrid research, an assessment model is presented in order to characterize the hybrid performance under different objectives. In hybrids, neutron multiplication in the subcritical blanket plays a major role, not only for energy production and nuclear breeding, but also for tritium breeding, which is fundamental requirement in fusion-fission hybrids. All three objectives are better achieved with high values of the neutron multiplication factor (k-eff) with the obvious and fundamental limitation that it cannot reach criticality under any event, particularly, in the case of a loss of coolant accident. This limitation will be very important in the selection of the coolant. Some general considerations will be proposed, as guidelines for assessing the hybrid potential in a given scenario. Those guidelines point out that hybrids can be of great interest for the future of nuclear energy in a framework of Sustainable Development, because they can contribute to the efficient exploitation of nuclear fuels, with very high safety features. Additionally, a proposal is presented on a blanket specially suited for fusion-fission hybrids, although this reactor concept is still under review, and new work is needed for identifying the most suitable blanket composition, which can vary depending on the main objective of the hybrid.

Review of fission-fusion pellet designs and inertial confinement system studies at EIR

Energy Technology Data Exchange (ETDEWEB)

Seifriz, W [Eidgenoessisches Inst. fuer Reaktorforschung, Wuerenlingen (Switzerland)

1978-01-01

The article summarizes the work done so far at the Swiss Federal Institute for Reactor Research (EIR) in the field of the inertial confinement fusion technique. The following subjects are reviewed: a) fission fusion pellet designs using fissionable triggers, b) uranium tampered pellets, c) tampered pellets recycling unwanted actinide wastes from fission reactors in beam-driven micro-explosion reactors, and d) symbiotic fusion/fission reactor studies.

A hybrid source-driven method to compute fast neutron fluence in reactor pressure vessel - 017

International Nuclear Information System (INIS)

Ren-Tai, Chiang

2010-01-01

A hybrid source-driven method is developed to compute fast neutron fluence with neutron energy greater than 1 MeV in nuclear reactor pressure vessel (RPV). The method determines neutron flux by solving a steady-state neutron transport equation with hybrid neutron sources composed of peripheral fixed fission neutron sources and interior chain-reacted fission neutron sources. The relative rod-by-rod power distribution of the peripheral assemblies in a nuclear reactor obtained from reactor core depletion calculations and subsequent rod-by-rod power reconstruction is employed as the relative rod-by-rod fixed fission neutron source distribution. All fissionable nuclides other than U-238 (such as U-234, U-235, U-236, Pu-239 etc) are replaced with U-238 to avoid counting the fission contribution twice and to preserve fast neutron attenuation for heavy nuclides in the peripheral assemblies. An example is provided to show the feasibility of the method. Since the interior fuels only have a marginal impact on RPV fluence results due to rapid attenuation of interior fast fission neutrons, a generic set or one of several generic sets of interior fuels can be used as the driver and only the neutron sources in the peripheral assemblies will be changed in subsequent hybrid source-driven fluence calculations. Consequently, this hybrid source-driven method can simplify and reduce cost for fast neutron fluence computations. This newly developed hybrid source-driven method should be a useful and simplified tool for computing fast neutron fluence at selected locations of interest in RPV of contemporary nuclear power reactors. (authors)

Fission 2009 4. International Workshop on Nuclear Fission and Fission Product Spectroscopy - Compilation of slides

International Nuclear Information System (INIS)

2009-01-01

This conference is dedicated to the last achievements in experimental and theoretical aspects of the nuclear fission process. The topics include: mass, charge and energy distribution, dynamical aspect of the fission process, nuclear data evaluation, quasi-fission and fission lifetime in super heavy elements, fission fragment spectroscopy, cross-section and fission barrier, and neutron and gamma emission. This document gathers the program of the conference and the slides of the presentations

Nuclear fission and neutron-induced fission cross-sections

Energy Technology Data Exchange (ETDEWEB)

James, G.D.; Lynn, J.E.; Michaudon, A.; Rowlands, J.; de Saussure, G.

1981-01-01

A general presentation of current knowledge of the fission process is given with emphasis on the low energy fission of actinide nuclei and neutron induced fission. The need for and the required accuracy of fission cross section data in nuclear energy programs are discussed. A summary is given of the steps involved in fission cross section measurement and the range of available techniques. Methods of fission detection are described with emphasis on energy dependent changed and detector efficiency. Examples of cross section measurements are given and data reduction is discussed. The calculation of fission cross sections is discussed and relevant nuclear theory including the formation and decay of compound nuclei and energy level density is introduced. A description of a practical computation of fission cross sections is given.

Study of α-particle multiplicity in 16O+196Pt fusion-fission reaction

International Nuclear Information System (INIS)

Kapoor, K.; Kumar, A.; Bansal, N.

2016-01-01

Study of dynamics of fusion-fission reaction is one of the interesting parts of heavy-ion-induced nuclear reaction. Extraction of fission time scales using different probes is of central importance for understanding the dynamics of fusion-fission process. In the past, extensive theoretical and experimental efforts have been made to understand the various aspects of the heavy ion induced fusion-fission reactions. Compelling evidences have been obtained from the earlier studies that the fission decay of hot nuclei is protracted process i.e. slowed down relative to the expectations of the standard statistical model, and large dynamical delays are required due to this hindrance. Nuclear dissipation is assumed to be responsible for this delay and more light particles are expected to be emitted during the fission process. One of neutron multiplicity measurements have been performed for the 16,18 O+ 194,198 Pt populating the CN 210,212,214,216 Rn and observed fission delay due to nuclear viscosity. In order to have complete understanding for the dynamics of 212 Rn nucleus, we measured the charged particle multiplicity for 16 O+ 196 Pt system. Study of charged particles will give us more information about the emitter in comparison to neutrons as charged particles faces Coulomb barrier and are more sensitive probe for understanding the dynamics of fusion-fission reactions. In the present work, we are reporting some of the preliminary results of charged particle multiplicity

Studies of Fission Fragment Rocket Engine Propelled Spacecraft

Science.gov (United States)

Werka, Robert O.; Clark, Rodney; Sheldon, Rob; Percy, Thomas K.

2014-01-01

The NASA Office of Chief Technologist has funded from FY11 through FY14 successive studies of the physics, design, and spacecraft integration of a Fission Fragment Rocket Engine (FFRE) that directly converts the momentum of fission fragments continuously into spacecraft momentum at a theoretical specific impulse above one million seconds. While others have promised future propulsion advances if only you have the patience, the FFRE requires no waiting, no advances in physics and no advances in manufacturing processes. Such an engine unequivocally can create a new era of space exploration that can change spacecraft operation. The NIAC (NASA Institute for Advanced Concepts) Program Phase 1 study of FY11 first investigated how the revolutionary FFRE technology could be integrated into an advanced spacecraft. The FFRE combines existent technologies of low density fissioning dust trapped electrostatically and high field strength superconducting magnets for beam management. By organizing the nuclear core material to permit sufficient mean free path for escape of the fission fragments and by collimating the beam, this study showed the FFRE could convert nuclear power to thrust directly and efficiently at a delivered specific impulse of 527,000 seconds. The FY13 study showed that, without increasing the reactor power, adding a neutral gas to the fission fragment beam significantly increased the FFRE thrust through in a manner analogous to a jet engine afterburner. This frictional interaction of gas and beam resulted in an engine that continuously produced 1000 pound force of thrust at a delivered impulse of 32,000 seconds, thereby reducing the currently studied DRM 5 round trip mission to Mars from 3 years to 260 days. By decreasing the gas addition, this same engine can be tailored for much lower thrust at much higher impulse to match missions to more distant destinations. These studies created host spacecraft concepts configured for manned round trip journeys. While the

Delayed fission

Energy Technology Data Exchange (ETDEWEB)

Hatsukawa, Yuichi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

1997-07-01

Delayed fission is a nuclear decay process that couples {beta} decay and fission. In the delayed fission process, a parent nucleus undergoes {beta} decay and thereby populates excited states in the daughter. If these states are of energies comparable to or greater than the fission barrier of the daughter, then fission may compete with other decay modes of the excited states in the daughter. In this paper, mechanism and some experiments of the delayed fission will be discussed. (author)

HAC and fission reactors

International Nuclear Information System (INIS)

Fujiwara, I.; Moriyama, H.; Tachikawa, E.

1984-01-01

In the fission process, newly formed fission products undergo hot atom reactions due to their energetic recoil and abnormal positive charge. The hot atom reactions of the fission products are usually accompanied by secondary effects such as radiation damage, especially in condensed phase. For reactor safety it is valuable to know the chemical behaviour and the release behaviour of these radioactive fission products. Here, the authors study the chemical behaviour and the release behaviour of the fission products from the viewpoint of hot atom chemistry (HAC). They analyze the experimental results concerning fission product behaviour with the help of the theories in HAC and other neighboring fields such as radiation chemistry. (Auth.)

Fission and activation of uranium by fashion-plasma neutrons

International Nuclear Information System (INIS)

Lee, J.H.; Hochl, F.; McFarland, D.R.

1978-01-01

Disks of enriched and depleted uranium were irradiated by neutrons from the D-D fusions in a dense plasma-focus. A fission yield of 10 6 fissions-cm -3 in U 235 per pulse was determined with Ge(Li) gamme-ray spectrometry. Activation of U 238 caused increased beta activity after the plasma-neutron irradiation but alpha-particle spectrometry showed Pu 239 production was negligible. In addition, with a disk of lithium in the apparatus, 13.3 MeV neutrons from 7 Li(d,n) 8 Be was observed with a 80-m time-of-flight neutron detector. Dense plasma focuses are now operated not only in a single coaxial gun, but also in improved geometries, such as the hypocycloidal pinch and the staged plasma focus, from which a multiple plasma-focus array suitable for experimental verification of, and eventuel development into a fusion-fission hybrid reactor could be produced. (orig.) [de

Burnup calculation for a tokamak commercial hybrid reactor

International Nuclear Information System (INIS)

Feng Kaiming; Xie Zhongyou

1990-08-01

A computer code ISOGEN-III and its associated data library BULIB have been developed for fusion-fission hybrid reactor burnup calculations. These are used to calcuate burnup of a tokamak commercial hybrid reactor. The code and library are introduced briefly, and burnup calculation results are given

Fission of heavy nuclei: microscopic study of fission barriers and fragments angular momentum

International Nuclear Information System (INIS)

Bonneau, L.

2003-11-01

A lot of experimental data on nuclear fission has been being collected for the last 65 years, allowing theoreticians to confront their models with reality. The first part of this work is dedicated to the computation of fission barriers. We have extended the HF + BCS (Hartree Fock + Bandeen-Cooper-Schrieffer) method in order to include a new set of polynomials on which wave functions can be broken to, more accurately than on Hermite's polynomials in the 2 fragment configuration. The fission barriers of 26 heavy nuclei from Thorium-230 to Nobelium-256 have been assessed and compared to experimental data, it appears that differences are no greater than 1 MeV. We have discovered a neat correlation between the variation of the experimental fission lifetimes of even Fermium isotopes and the computed heights of second barriers. Moreover our model reproduces the hyper-deformed well of Thorium-230 with a good agreement on the well depth. The second part deals with the scission region. We have performed Hartree-Fock calculations in order to explore different ways of fragmentation. We have shown that the harmonic oscillator gives a valid description of such ways. In order to compute the mean value of J 2 in the fragments we have been driven to propose an adequate definition of that quantity consistent with the non-locality property of the J 2 operator. (A.C.)

The study of prompt and delayed muon induced fission III. The ratios of prompt to delayed fission yields

NARCIS (Netherlands)

Rösel, Ch.; Hänscheid, H.; Hartfiel, J.; Mutius, von R.; Achard van Enschut, d' J.F.M.; David, P; Janszen, H.; Johansson, T.; Konijn, J.; Krogulski, T.; Laat, de C.T.A.M.; Paganetti, H.; Petitjean, C.; Polikanov, S.M.; Reist, H.W.; Risse, F.; Schaller, L.A.; Schrieder, W.; Sinha, A.K.; Taal, A.; Theobald, J.P.; Tibell, G.; Trautmann, N.

1993-01-01

The ratios of prompt to delayed fission yields for the isotopes U-233, U-234, U-235, U-236, U-238, Np-237, Pu-242, and Pu-244 and the fission probabilities relative to each other have been investigated experimentally. Using the value of the total fission probability for Np-237 the absolute

Mechanical and thermal design of hybrid blankets

International Nuclear Information System (INIS)

Schultz, K.R.

1978-01-01

The thermal and mechanical aspects of hybrid reactor blanket design considerations are discussed. This paper is intended as a companion to that of J. D. Lee of Lawrence Livermore Laboratory on the nuclear aspects of hybrid reactor blanket design. The major design characteristics of hybrid reactor blankets are discussed with emphasis on the areas of difference between hybrid reactors and standard fusion or fission reactors. Specific examples are used to illustrate the design tradeoffs and choices that must be made in hybrid reactor design. These examples are drawn from the work on the Mirror Hybrid Reactor

Survey of Materials for Fusion Fission Hybrid Reactors Vol 1 Rev. 0

Energy Technology Data Exchange (ETDEWEB)

Farmer, Joseph Collin [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Chemistry Materials and Life Sciences Directorate

2007-07-03

Materials for fusion-fission hybrid reactors fall into several broad categories, including fuels, blanket and coolant materials, cladding, structural materials, shielding, and in the specific case of inertial-confinement fusion systems, laser and optical materials. This report surveys materials in all categories of materials except for those required for lasers and optics. Preferred collants include two molten salt mixtures known as FLIBE (Li2BeF4) and FLINABE (LiNaBeF4). In the case of homogenous liquid fuels, UF4 can be dissolved in these molten salt mixtures. The transmutation of lithium in this coolant produces very corrosive hydrofluoric acid species (HF and TF), which can rapidly degrade structural materials. Broad ranges of high-melting radiation-tolerant structural material have been proposed for fusion-fission reactor structures. These include a wide variety of steels and refractory alloys. Ferritic steels with oxide-dispersion strengthening and graphite have been given particular attention. Refractory metals are found in Groups IVB and VB of the periodic table, and include Nb, Ta, Cr, Mo, and W, as serve as the basis of refractory alloys. Stable high-melting composites and amorphous metals may also be useful. Since amorphous metals have no lattice structure, neutron bombardment cannot dislodge atoms from lattice sites, and the materials would be immune from this specific mode of degradation. The free energy of formation of fluorides of the alloying elements found in steels and refractory alloys can be used to determine the relative stability of these materials in molten salts. The reduction of lithium transmutation products (H⁺ and T⁺) drives the electrochemical corrosion process, and liberates aggressive fluoride ions that pair with ions formed from dissolved structural materials. Corrosion can be suppressed through the use of metallic Be and Li, though the molten salt becomes laden with colloidal suspensions of Be and Li corrosion

Symbiosis of near breeder HTR's with hybrid fusion reactors

International Nuclear Information System (INIS)

Seifritz, W.

1978-07-01

In this contribution to INFCE a symbiotic fusion/fission reactor system, consisting of a hybrid beam-driven micro-explosion fusion reactor (HMER) and associated high-temperature gas-cooled reactors (HTR) with a coupled fuel cycle, is proposed. This system is similar to the well known Fast Breeder/Near Breeder HTR symbiosis except that the fast fission breeder - running on the U/Pu-cycle in the core and the axial blankets and breeding the surplus fissile material as U-233 in its radial thorium metal or thorium oxide blankets - is replaced by a hybrid micro-explosion DT fusion reactor

Insights into nuclear structure and the fission process from spontaneous fission

Energy Technology Data Exchange (ETDEWEB)

Hamilton, J.H.; Butler-Moore, K.; Ramayya, A.V. [Vanderbilt Univ., Nashville, TN (United States)] [and others

1993-12-31

The {gamma}-rays emitted following spontaneous and induced fission are rich sources of information about the structure of neutron-rich nuclei and about the fission process itself. The study of spontaneous fissioning isotopes with large Ge detector arrays are providing a wealth of such information as seen, for example, in recent reports. In this paper we present some of our most recent results on nuclear structure studies and conclusions on the fission process itself. In our work, we have employed in spontaneous fission, a triple gamma coincidence study for the first time and a high resolution, X-ray detector-{gamma}-coincidence study. These data provide powerful ways of separating the gamma rays which belong to a particular nucleus. The triple coincidence technique was used to uniquely identify the levels in {sup 136}Te and higher spin states in its N=84 isotones, {sup 138}Xe and {sup 140}Ba{sup 171}. Some other examples of the level structures observed in the low and high mass partners are presented, including a detailed analysis of the backbending of the moment of inertia in {sup 112,114,116}Pd. Finally, we present the first examples of how our analysis allows one to extract a detailed picture of the dependence of the angular momentum on the mass and atomic numbers of the fission fragments and of the long-sought neutron multiplicity distribution from zero-n to ten-n as a function of the charge and mass asymmetry.

Correlation of errors in the Monte Carlo fission source and the fission matrix fundamental-mode eigenvector

International Nuclear Information System (INIS)

Dufek, Jan; Holst, Gustaf

2016-01-01

Highlights: • Errors in the fission matrix eigenvector and fission source are correlated. • The error correlations depend on coarseness of the spatial mesh. • The error correlations are negligible when the mesh is very fine. - Abstract: Previous studies raised a question about the level of a possible correlation of errors in the cumulative Monte Carlo fission source and the fundamental-mode eigenvector of the fission matrix. A number of new methods tally the fission matrix during the actual Monte Carlo criticality calculation, and use its fundamental-mode eigenvector for various tasks. The methods assume the fission matrix eigenvector is a better representation of the fission source distribution than the actual Monte Carlo fission source, although the fission matrix and its eigenvectors do contain statistical and other errors. A recent study showed that the eigenvector could be used for an unbiased estimation of errors in the cumulative fission source if the errors in the eigenvector and the cumulative fission source were not correlated. Here we present new numerical study results that answer the question about the level of the possible error correlation. The results may be of importance to all methods that use the fission matrix. New numerical tests show that the error correlation is present at a level which strongly depends on properties of the spatial mesh used for tallying the fission matrix. The error correlation is relatively strong when the mesh is coarse, while the correlation weakens as the mesh gets finer. We suggest that the coarseness of the mesh is measured in terms of the value of the largest element in the tallied fission matrix as that way accounts for the mesh as well as system properties. In our test simulations, we observe only negligible error correlations when the value of the largest element in the fission matrix is about 0.1. Relatively strong error correlations appear when the value of the largest element in the fission matrix raises

Study of scission shapes in spontaneous ternary fission of 252Cf

International Nuclear Information System (INIS)

Singer, P.; Schwalm, D.; Thirolf, P.; Goennenwein, F.; Hesse, M.

1995-06-01

A new kinematic study on the ternary fission of 252 Cf has been conducted by registering prompt neutrons and fission γ rays coincidence with light charged particles (LCP) and fission fragments. The aim is to investigate changes in fragment deformation energy between the binary and ternary fission modes from measured prompt neutron angular distributions and multiplicities, and to explore the influence of light particle emission on the energy distribution, multiplicity and angular anisotropy of γ rays emitted during fragment de-excitation. The experiment was performed at the MPI Heidelberg using the Darmstadt-Heidelberg crystal ball spectrometer as γ-ray and neutron detector. Fragments were identified by a double-E measurement with an angular sensitive twin ionization chamber (IC). Light charged particles from fission were measured by ΔE-E telescopes composed of ΔE ICs and silicon PIN diodes. The telescopes enable to identify various LCPs which are emitted much more rarely than ternary α particles. The parameters of the experiment and the method of data analysis are described and first results presented. (orig.)

Control of a laser inertial confinement fusion-fission power plant

Science.gov (United States)

Moses, Edward I.; Latkowski, Jeffery F.; Kramer, Kevin J.

2015-10-27

A laser inertial-confinement fusion-fission energy power plant is described. The fusion-fission hybrid system uses inertial confinement fusion to produce neutrons from a fusion reaction of deuterium and tritium. The fusion neutrons drive a sub-critical blanket of fissile or fertile fuel. A coolant circulated through the fuel extracts heat from the fuel that is used to generate electricity. The inertial confinement fusion reaction can be implemented using central hot spot or fast ignition fusion, and direct or indirect drive. The fusion neutrons result in ultra-deep burn-up of the fuel in the fission blanket, thus enabling the burning of nuclear waste. Fuels include depleted uranium, natural uranium, enriched uranium, spent nuclear fuel, thorium, and weapons grade plutonium. LIFE engines can meet worldwide electricity needs in a safe and sustainable manner, while drastically shrinking the highly undesirable stockpiles of depleted uranium, spent nuclear fuel and excess weapons materials.

Studies of Fission-Induced Surface Damage in Actinides Using Ultracold Neutrons

Energy Technology Data Exchange (ETDEWEB)

Broussard, Leah J. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2014-03-05

This report describes the results of the fission-induced actinide studies at LANL. Previously, there was no fission data at these energies though there were initial characterizations of UCN energy dependence and material thickness. The proof of principle was demonstrated and the initial characterizations of sputtered rates, angular and size distribution are underway.

Elise: a new facility for unprecedented experimental nuclear fission studies

International Nuclear Information System (INIS)

Taieb, J.; Belier, G.; Chatillon, A.; Granier, T.; Kelic, A.; Ricciardi, V.; Schmidt, K.H.; Voss, B.; Coste-Delclaux, M.; Diop, C.; Jouanne, C.; Schmitt, C.; Aiche, M.; Czajkowski, S.; Jurado, B.; Audouin, L.; Peyre, J.; Rosier, P.; Tassan-Got, L.; Bertoumieux, E.; Dore, D.; Dupont, E.; Letourneau, A.; Panebianco, S.

2009-01-01

A novel experimental program aiming to study the properties of fragments and neutrons emitted in the fission process has been initiated. The experiment will be held at the ELISe electron-ion collider to be constructed at GSI, Darmstadt in the framework of the FAIR extension of the facility. The experiment will take advantage of the inverse kinematics allowing, in particular, a total mass and charge resolution for all fission fragments. (authors)

Coulomb fission and transfer fission at heavy ion collisions

International Nuclear Information System (INIS)

Himmele, G.

1981-01-01

In the present thesis the first direct evidence of nuclear fission after inelastic scattering of heavy ions (sup(183,184)W, 152 Sm → 238 U; 184 W → 232 Th; 184 W, 232 Th → 248 Cm) is reported. Experiments which were performed at the UNILAC of the Gesellschaft fuer Schwerionenforschung in Darmstadt show the observed heavy ion induced fission possesses significant properties of the Coulomb fission. The observed dependence of the fission probability for inelastic scattering on the projectile charge proves that the nuclear fission is mediated by the electromagnetic interaction between heavy ions. This result suggests moreover a multiple Coulomb-excitation preceding the fission. Model calculations give a first indication, that the Coulomb fission proceeds mainly from the higher β phonons. In the irradiation with 184 W the fission probability of 232 Th is for all incident energies about 40% smaller that at 238 U. The target dependence of the Coulomb fission however doesn't allow, to give quantitative statements about the position and B(E2)-values of higher lying β phonons. (orig./HSI) [de

Correlation studies of neutron multiplicities in the 252Cf spontaneous fission

International Nuclear Information System (INIS)

Alkhazov, I.D.; Dmitriev, V.D.; Kovalenko, S.S.; Kuznetsov, A.V.; Malkin, L.Z.; Petrzhak, K.A.; Petrov, B.F.; Shpakov, V.I.

1988-01-01

Correlations between the numbers of neutrons emitted by the 252 Cf spontaneous fission fragments have been studied as a function of the fragment mass and total kinetic energy. Behaviour of the neutron number dispersions and covariances was studied for the region of symmetric fission. Parameters of the complementary fragment excitation energy distribution (mean values, dispersions, covariances) were determined. Various factors describing correlations between the complementary fragment excitation energies are considered

Fission fragment distributions within dynamical approach

Energy Technology Data Exchange (ETDEWEB)

Mazurek, K. [Institute of Nuclear, Physics Polish Academy of Sciences, Krakow (Poland); Nadtochy, P.N. [Omsk State Technical University, Omsk (Russian Federation); Ryabov, E.G.; Adeev, G.D. [Omsk State University, Physics Department, Omsk (Russian Federation)

2017-04-15

The review covers recent developments and achievements in the dynamical description of fission process at high excitation energy. It is shown that the dynamical approach based on multidimensional Langevin equations combined with the statistical description of nuclear decay by particles evaporation is capable of fairly well describing the formation of fission fragment mass-energy, charge, and angular distributions of fission fragments in coincidence with the pre- and post-scission particle emission. The final yields of fission and evaporation residues channels products could be obtained. The detailed description of fission dynamics allows studying different stages of fission process, indicating the most important ingredients governing fission process and studying in detail such fundamental nuclear properties as nuclear viscosity and fission timescale. The tasks and perspectives of multidimensional dynamical approach are also discussed. (orig.)

An introduction to hybrid fusion

International Nuclear Information System (INIS)

Reynolds, J.A.

1982-01-01

This report gives a brief introduction to some hybrid fusion proposals. The idea is to take advantage of the high neutron energy in fusion compared to fission either to breed fuel more efficiently than in a fast reactor, or increase the power output by fission of U 238 or transmute radioactive waste. The penalty is an increased cost and complexity of the blanket and the loss of environmental and safety arguments for fusion systems which rest on their low inventory of radioactive materials. (author)

Hybrid system concepts

International Nuclear Information System (INIS)

Landeyro, P.A.

1995-01-01

Hybrid systems studied for fissile material production, were reconsidered for minor actinide and long-lived fission product destruction as alternative to the traditional final disposal of nuclear waste. Now there are attempts to extend the use of the concepts developed for minor actinide incineration to plutonium burning. The most promising hybrid system concept considers fuel and target both as liquids. From the results obtained, the possibility to adopt composite targets seems the most promising solution, but still there remains the problem of Pu production, not acceptable in a burning system. This kind of targets can be mainly used for fissile material production, while for accelerator driven burners it is most convenient to use a liquid lead target. The most suitable solvent is heavy water for minor actinide annihilation in the blanket of a hybrid system. Due to the criticality conditions and the necessity of electric energy production, the blanket using plutonium dissolved in molten salts is the most convenient one. (author)

Decay times for second-chance fission of 239U studied by crystal blocking

International Nuclear Information System (INIS)

Andersen, J.U.; Chechenin, N.G.; Jensen, A.S.; Joergensen, K.; Laegsgaard, E.

1979-01-01

Neutron-induced fission of 238 U has been studied by the crystal-blocking technique for neutron energies just below and above the threshold for second-chance fission. In agreement with earlier measurements, in this energy range the lifetime for first-chance fission is found to be too short to have an observable effect on the blocking dips. Above the threshold, however, an appreciable filling-in of the dips is observed. The results are analyzed in the terms of a two-component lifetime distribution and then indicate an average lifetime of a few fsec for second-chance fission at a neutron energy of Esub(n)approximately7.2 MeV, in agreement with results from a simple calculation. It is shown that in this analysis it is important to take into account the anisotropy of the fission-fragment distribution and, in particular, the difference between the angular distributions for first- and second-chance fission. (Auth.)

Study of 235U very asymmetric thermal fission

International Nuclear Information System (INIS)

Sida, J.L.

1989-12-01

The fission fragment separator Lohengrin of the Institut Laue-Langevin in Grenoble was used to determine the yields of the very asymmetric light fission products (A=84-69) as a function of A, Z, and the kinetic energy E. The proton pairing effect causes fine structures in the mass distribution, in the mean nuclear charge anti Z and its variance σ z , and in the mean kinetic energies of the elements. The neutron pairing effect in the production yields is found for the first time of the same order of magnitude than the proton pairing effect. In the mass region investigated both are the largest observed in fission of 235 U. A decrease in the mean kinetic energy for the isotopes of Ni and Cu was observed. It points to a large deformation at scission. Our results support the view that very asymmetric low-energy fission is a weakly dissipative process. The highly deformed transient system breaks by a slow necking-in process [fr

Study of electron-capture delayed fission in Am-232

International Nuclear Information System (INIS)

Kreek, S.A.; Hall, H.L.; Hoffman, D.C.; Strellis, D.; Gregorich, K.E.

1996-01-01

An automated x-ray-fission coincidence system was designed and constructed by LLNL and Lawrence Berkeley National Laboratory (LBNL) for use inside the Gammasphere high efficiency gamma-ray detector array at LBNL. The x-ray-fission coincidence apparatus detection station consists of two surface barrier detectors (for detection of fission fragments) and two high-purity Ge (HPGe) planar x-ray detectors (for measurement of x-rays and low-energy gamma rays). The detection station is placed inside Gammasphere at the 88-Inch Cyclotron at LBNL and used in conjunction with Gammasphere to measure the x-rays, low-energy gamma-rays and fission fragments resulting from the ECDF process. A series of collaborative experiment between LLNL, LBNL, and LANL utilizing various components of the x-ray-fission coincidence apparatus to measure x-rays and gamma-rays in the decay of a stationary 252 Cf source were performed to test the various components of the x-ray-fission coincidence apparatus. The test experiments have been completed and the data is currently being analyzed by LBNL. Preliminary test results indicate that the system performed better than expected (e.g., the x-ray detectors performed better than expected with no evidence of microphonic noise that would reduce the photon energy resolution)

Conceptual design of a Tokamak hybrid power reactor (THPR)

International Nuclear Information System (INIS)

Matsuoka, F.; Imamura, Y.; Inoue, M.; Asami, N.; Kasai, M.; Yanagisawa, I.; Ida, T.; Takuma, T.; Yamaji, K.; Akita, S.

1987-01-01

A conceptual design of a fusion-fission hybrid tokamak reactor has been carried out to investigate the engineering feasibility and promising scale of a commercial hybrid reactor power plant. A tokamak fusion driver based on the recent plasma scaling law is introduced in this design study. The major parameters and features of the reactor are R=6.06 m, a=1.66 m, Ip=11.8 MA, Pf=668 MW, double null divertor plasma and steady state burning with RF current drive. The fusion power has been determined with medium energy multiplication in the blanket so as to relieve thermal design problems and produce electric power around 1000 MW. Uranium silicide is used for the fast fission blanket material to promise good nuclear performance. The coolant of the blanket is FLIBE and the tritium breeding blanket material is Li 2 O ceramics providing breeding ratio above unity

Nuclear Forensics and Radiochemistry: Fission

Energy Technology Data Exchange (ETDEWEB)

Rundberg, Robert S. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-11-07

Radiochemistry has been used to study fission since it’ discovery. Radiochemical methods are used to determine cumulative mass yields. These measurements have led to the two-mode fission hypothesis to model the neutron energy dependence of fission product yields. Fission product yields can be used for the nuclear forensics of nuclear explosions. The mass yield curve depends on both the fuel and the neutron spectrum of a device. Recent studies have shown that the nuclear structure of the compound nucleus can affect the mass yield distribution.

Effects of fissioning nuclei distributions on fragment mass distributions for high energy fission

Directory of Open Access Journals (Sweden)

Rossi P C R

2012-02-01

Full Text Available We study the effects of fissioning nuclei mass- and energy-distributions on the formation of fragments for fission induced by high energy probes. A Monte Carlo code called CRISP was used for obtaining mass distributions and spectra of the fissioning nuclei for reactions induced by 660 MeV protons on 241Am and on 239Np, by 500 MeV protons on 208Pb, and by Bremsstrahlung photons with end-point energies at 50 MeV and 3500 MeV on 238U. The results show that even at high excitation energies, asymmetric fission may still contribute significantly to the fission cross section of actinide nuclei, while it is the dominante mode in the case of lead. However, more precise data for high energy fission on actinide are necessary in order to allow definite conclusions.

Measurement of Fission Product Yields from Fast-Neutron Fission

Science.gov (United States)

Arnold, C. W.; Bond, E. M.; Bredeweg, T. A.; Fowler, M. M.; Moody, W. A.; Rusev, G.; Vieira, D. J.; Wilhelmy, J. B.; Becker, J. A.; Henderson, R.; Kenneally, J.; Macri, R.; McNabb, D.; Ryan, C.; Sheets, S.; Stoyer, M. A.; Tonchev, A. P.; Bhatia, C.; Bhike, M.; Fallin, B.; Gooden, M. E.; Howell, C. R.; Kelley, J. H.; Tornow, W.

2014-09-01

One of the aims of the Stockpile Stewardship Program is a reduction of the uncertainties on fission data used for analyzing nuclear test data [1,2]. Fission products such as 147Nd are convenient for determining fission yields because of their relatively high yield per fission (about 2%) and long half-life (10.98 days). A scientific program for measuring fission product yields from 235U,238U and 239Pu targets as a function of bombarding neutron energy (0.1 to 15 MeV) is currently underway using monoenergetic neutron beams produced at the 10 MV Tandem Accelerator at TUNL. Dual-fission chambers are used to determine the rate of fission in targets during activation. Activated targets are counted in highly shielded HPGe detectors over a period of several weeks to identify decaying fission products. To date, data have been collected at neutron bombarding energies 4.6, 9.0, 14.5 and 14.8 MeV. Experimental methods and data reduction techniques are discussed, and some preliminary results are presented.

Nuclear fission and neutron-induced fission cross-sections

CERN Document Server

James, G D; Michaudon, A; Michaudon, A; Cierjacks, S W; Chrien, R E

2013-01-01

Nuclear Fission and Neutron-Induced Fission Cross-Sections is the first volume in a series on Neutron Physics and Nuclear Data in Science and Technology. This volume serves the purpose of providing a thorough description of the many facets of neutron physics in different fields of nuclear applications. This book also attempts to bridge the communication gap between experts involved in the experimental and theoretical studies of nuclear properties and those involved in the technological applications of nuclear data. This publication will be invaluable to those interested in studying nuclear fis

Study of actinides fission induced by multi-nucleon transfer reactions in inverse kinematics

International Nuclear Information System (INIS)

Derkx, X.

2010-10-01

The study of actinide fission encounters two major issues. On one hand, measurements of the fission fragment distributions and the fission probabilities allow a better understanding of the fission process itself and the discrimination among the models of nuclear structure and dynamics. On the other hand, new measurements are required to improve nuclear data bases, which are a key component for the design of new generation reactors and radio-toxic waste incinerators. This thesis is in line with different French and American experimental projects using the surrogate method, i.e. transfer reactions leading to the same compound nuclei as in neutron irradiation, allowing the study of fission of actinides which are inaccessible by conventional techniques, whereas they are important for applications. The experiment is based on multi-nucleon transfer reactions between a 238 U beam and a 12 C target, using the inverse kinematics technique to measure, for each transfer channel, the complete isotopic distributions of the fission fragments with the VAMOS spectrometer. The work presented in this dissertation is focused on the identification of the transfer channels and their properties, as their angular distributions and the distributions of the associated excitation energy, using the SPIDER telescope to identify the target recoil nuclei. This work of an exploratory nature aims to generalize the surrogate method to heavy transfers and to measure, for the first time, the fission probabilities in inverse kinematics. The obtained results are compared with available direct kinematics and neutron irradiation measurements. (author)

Experimental neutronic science and instrumentation: from hybrid reactors to fourth generation reactors

International Nuclear Information System (INIS)

Jammes, Ch.

2010-07-01

After an overview of his academic career and scientific and research activities, the author proposes a rather detailed synthesis and overview of his scientific activities in the fields of cross sections and Doppler effect (development and validation of a code), on the MUSE-4 hybrid reactor (experiments, static and dynamic measurements), on the TRADE hybrid reactor (experimental means, sub-critical reactivity measurement), on the RACE hybrid reactor (experimental results, modelling and interpretation), and on neutron detection (design and modelling of fission chamber, on-line measurement of the fast flow). The next part gives an overview of some research programs (neutron monitoring in sodium-cool fast reactors, research and development on fission chambers, improvement of effective delayed neutron measurements)

Fission studies of gold induced by (1665 MeV) π- using a CR-39 detector

International Nuclear Information System (INIS)

Muhammad Ikram Shahzad; Yasin, Zafar; Sher, Gul

2012-01-01

The fission cross section and fission probability of 197 Au, induced by (1665 MeV) π'-, have been studied using CR-39 track detectors. A 4π-geometry was used to count track statistics. A beam of negative pions of 1665 MeV was produced at AGS of Brookhaven National Laboratory, USA, and allowed to fall normally on the stack. Two detectors from the stack were scanned for fission fragment tracks after etching in 6N NaOH at 70 ℃. The statistics of fission fragment tracks in both detectors were obtained. It was found that there was a marked asymmetry of registered tracks with respect to the forward and backward hemispheres. This asymmetry could be partly accounted for on the basis of momentum transfer to the struck nucleus. On the basis of counting statistics fission cross section was measured, and fission probability was determined by dividing the fission cross section with the reaction cross section. The fission cross-section and fission probability were compared with the computed values using the cascade-exciton model code CEM95. (authors)

[Fission product yields of 60 fissioning reactions]. Final report

International Nuclear Information System (INIS)

Rider, B.F.

1995-01-01

In keeping with the statement of work, I have examined the fission product yields of 60 fissioning reactions. In co-authorship with the UTR (University Technical Representative) Talmadge R. England ''Evaluation and Compilation of Fission Product Yields 1993,'' LA-UR-94-3106(ENDF-349) October, (1994) was published. This is an evaluated set of fission product Yields for use in calculation of decay heat curves with improved accuracy has been prepared. These evaluated yields are based on all known experimental data through 1992. Unmeasured fission product yields are calculated from charge distribution, pairing effects, and isomeric state models developed at Los Alamos National Laboratory. The current evaluation has been distributed as the ENDF/B-VI fission product yield data set

Study on decay of rare earth nuclei produced by fission

Energy Technology Data Exchange (ETDEWEB)

Kawade, Kiyoshi; Yamamoto, Hiroshi; Shibata, Michihiro; Asai, Masato [Nagoya Univ. (Japan); Tsukada, Kazuaki; Osa, Akihiko; Shinohara, Nobuo; Iimura, Hideki

1996-01-01

JAERI-ISOL utilizes charge particle induced fission by proton and heavy proton produced by the tandem type accelerator (JAERI). To study the decay mechanism and nuclei structure of neutron and excess nuclei produced by actinoid fission, JAERI-ISOL was improved by developing the multilayer target tank. So that, the intensity of mass separated ion beam increased enough to use. New 76.6 KeV {gamma}-ray with about 10s of half life was found in the preliminary experiment. (S.Y.)

Fission product vapour - aerosol interactions in the containment: simulant fuel studies

International Nuclear Information System (INIS)

Beard, A.M.; Benson, C.G.; Bowsher, B.R.

1988-12-01

Experiments have been conducted in the Falcon facility to study the interaction of fission product vapours released from simulant fuel samples with control rod aerosols. The aerosols generated from both the control rod and fuel sample were chemically distinct and had different deposition characteristics. Extensive interaction was observed between the fission product vapours and the control rod aerosol. The two dominant mechanisms were condensation of the vapours onto the aerosol, and chemical reactions between the two components; sorption phenomena were believed to be only of secondary importance. The interaction of fission product vapours and reactor materials aerosols could have a major impact on the transport characteristics of the radioactive emission from a degrading core. (author)

A stochastic approach to fission

International Nuclear Information System (INIS)

Boilley, D.; Suraud, E.; Abe, Yasuhisa

1992-01-01

A microscopically derived Langevin equation is applied to thermally induced nuclear fission. An important memory effect is pointed out. A strong friction coefficient, calculated from microscopic quantities, tends to decrease the stationary limit of the fission rate and to increase the transient time. Fission was described as a diffusion over a barrier of a collective variable, and a Langevin Equation (LE) was used to study the phenomenon. A study of the stationary flow over the saddle point with a Fokker-Planck Equation (FPE), equivalent to the LE was used to give formula for the stationary fission rate (or reaction rate for the chemistry applications). More recently, a complete study of the fission process was performed numerically with both FPE and LE. A long transient time, that could allow more pre-scission neutrons to evaporate, was pointed out. The derivation of this new LE is recalled, followed by the description of the memory dependence and by the effect of a large friction coefficient on the fission rate. (author) 6 refs., 3 figs

A cluster dynamics study of fission gases in uranium dioxide

International Nuclear Information System (INIS)

Skorek, Richard

2013-01-01

During in-pile irradiation of nuclear fuels a lot of rare gases are produced, mainly xenon and krypton. The behaviour of these highly insoluble fission gases may lead to an additional load of the cladding, which may have detrimental safety consequences. For these reasons, fission gas behaviour (diffusion and clustering) has been extensively studied for years.In this work, we present an application of Cluster Dynamics to address the behaviour of fission gases in UO_2 which simultaneously describes changes in rare gas atom and point defect concentrations in addition to the bubble size distribution. This technique, applied to Kr implanted and annealed samples, yields a precise interpretation of the release curves and helps justifying the estimation of the Kr diffusion coefficient, which is a data very difficult to obtain due to the insolubility of the gas. (author) [fr

Enhanced fuel production in thorium/lithium hybrid blankets utilizing uranium multipliers

International Nuclear Information System (INIS)

Pitulski, R.H.

1979-10-01

A consistent neutronics analysis is performed to determine the effectiveness of uranium bearing neutron multiplier zones on increasing the production of U 233 in thorium/lithium blankets for use in a tokamak fusion-fission hybrid reactor. The nuclear performance of these blankets is evaluated as a function of zone thicknesses and exposure by using the coupled transport burnup code ANISN-CINDER-HIC. Various parameters such as U 233 , Pu 239 , and H 3 production rates, the blanket energy multiplication, isotopic composition of the fuels, and neutron leakages into the various zones are evaluated during a 5 year (6 MW.y.m -2 ) exposure period. Although the results of this study were obtained for a tokomak magnetic fusion device, the qualitative behavior associated with the use of the uranium bearing neutron multiplier should be applicable to all fusion-fission hybrids

Status report on actinide and fission product transmutation studies

International Nuclear Information System (INIS)

1997-06-01

The management of radioactive waste is one of the key issues in today's political and public discussions on nuclear energy. One of the fields that looks into the future possibilities of nuclear technology is the neutronic transmutation of actinides and of some most important fission products. Studies on transmutation of actinides are carried out in various countries and at an international level. This status report which gives an up-to-date general overview of current and planned research on transmutation of actinides and fission products in non-OECD countries, has been prepared by a Technical Committee meeting organized by the IAEA in September 1995. 168 refs, 16 figs, 34 tabs

Backtracing neutron analysis in the fusion-fission dynamics study

International Nuclear Information System (INIS)

Brennand, E. de Goes; Hanappe, F.; Stuttge, L.

2001-01-01

A new method for the analysis of multi parametric experimental data is used in the study of the dynamics of the fission process for the compound system 126 Ba. We apply this method to obtain the correlation between thermal energy related to the neutron total multiplicity and the correlation between pre-scission neutron and pos-scission neutron multiplicities. The results obtained are interpreted into the framework of a dynamical model. From this interpretation we have access to the following information: the friction intensity which drives the dynamical evolution of the system; the initial deformation of the compound system; the barrier evolution with temperature and angular momentum, and fission times. (author)

Study on the calculation method of source term from fission products

International Nuclear Information System (INIS)

Zhou Jing; Gong Quan; Qiu Haifeng

2014-01-01

As a major part of radioactive nuclides, fission products play an important role in nuclear power plant design. The paper analyzes the calculation model of core activity inventory, the model of fission products releasing from the pellets to RCS, the balance model of fission products in RCS, and then proves them by calculation of the typical pressurized water reactor. The model is proved applicable for calculating fission products of pressurized water reactors. (authors)

The fission-track analysis: An alternative technique for provenance studies of prehistoric obsidian artefacts

CERN Document Server

Bellot-Gurlet, L; Dorighel, O; Oddone, M; Poupeau, G; Yegingil, Z

1999-01-01

Comparison of fission-track parameters - age and track densities - is an alternative tool for correlating obsidian artefacts with their potential natural sources. This method was applied by different fission-track groups in various regions and results were compared with those obtained using the more popular provenance identification techniques based on chemical composition studies. Hundreds of analyses prove that fission-track dating is a complementary technique which turns out to be very useful, specially when the chemical composition does not fully discriminate different sources. Archaeologically significant results were obtained applying the fission-track analysis in various regions of earth.

The fission-track analysis: An alternative technique for provenance studies of prehistoric obsidian artefacts

International Nuclear Information System (INIS)

Bellot-Gurlet, L.; Bigazzi, G.; Dorighel, O.; Oddone, M.; Poupeau, G.; Yegingil, Z.

1999-01-01

Comparison of fission-track parameters - age and track densities - is an alternative tool for correlating obsidian artefacts with their potential natural sources. This method was applied by different fission-track groups in various regions and results were compared with those obtained using the more popular provenance identification techniques based on chemical composition studies. Hundreds of analyses prove that fission-track dating is a complementary technique which turns out to be very useful, specially when the chemical composition does not fully discriminate different sources. Archaeologically significant results were obtained applying the fission-track analysis in various regions of earth

Fission level densities

International Nuclear Information System (INIS)

Maslov, V.M.

1998-01-01

Fission level densities (or fissioning nucleus level densities at fission saddle deformations) are required for statistical model calculations of actinide fission cross sections. Back-shifted Fermi-Gas Model, Constant Temperature Model and Generalized Superfluid Model (GSM) are widely used for the description of level densities at stable deformations. These models provide approximately identical level density description at excitations close to the neutron binding energy. It is at low excitation energies that they are discrepant, while this energy region is crucial for fission cross section calculations. A drawback of back-shifted Fermi gas model and traditional constant temperature model approaches is that it is difficult to include in a consistent way pair correlations, collective effects and shell effects. Pair, shell and collective properties of nucleus do not reduce just to the renormalization of level density parameter a, but influence the energy dependence of level densities. These effects turn out to be important because they seem to depend upon deformation of either equilibrium or saddle-point. These effects are easily introduced within GSM approach. Fission barriers are another key ingredients involved in the fission cross section calculations. Fission level density and barrier parameters are strongly interdependent. This is the reason for including fission barrier parameters along with the fission level densities in the Starter File. The recommended file is maslov.dat - fission barrier parameters. Recent version of actinide fission barrier data obtained in Obninsk (obninsk.dat) should only be considered as a guide for selection of initial parameters. These data are included in the Starter File, together with the fission barrier parameters recommended by CNDC (beijing.dat), for completeness. (author)

Preconceptual design and assessment of a Tokamak Hybrid Reactor

Energy Technology Data Exchange (ETDEWEB)

Teofilo, V.L.; Leonard, B.R. Jr.; Aase, D.T.

1980-09-01

The preconceptual design of a commercial Tokamak Hybrid Reactor (THR) power plant has been performed. The tokamak fusion driver for this hybrid is operated in the ignition mode. The D-T fusion plasma, which produces 1140 MW of power, has a major radius of 5.4 m and a minor radius of 1.0 m with an elongation of 2.0. Double null poloidal divertors are assumed for impurity control. The confining toroidal field is maintained by D-shaped Nb/sub 3/Sn superconducting magnets with a maximum field of 12T at the coil. Three blankets with four associated fuel cycle alternatives have been combined with the ignited tokamak fusion driver. The engineering, material, and balance of plant design requirements for the THR are briefly described. Estimates of the capital, operating and maintenance, and fuel cycle costs have been made for the various driver/blanket combinations and an assessment of the market penetrability of hybrid systems is presented. An analysis has been made of the nonproliferation aspects of the hybrid and its associated fuel cycles relative to fission reactors. The current and required level of technology for both the fusion and fission components of the hybrid system has been reviewed. Licensing hybrid systems is also considered.

Preconceptual design and assessment of a Tokamak Hybrid Reactor

International Nuclear Information System (INIS)

Teofilo, V.L.; Leonard, B.R. Jr.; Aase, D.T.

1980-09-01

The preconceptual design of a commercial Tokamak Hybrid Reactor (THR) power plant has been performed. The tokamak fusion driver for this hybrid is operated in the ignition mode. The D-T fusion plasma, which produces 1140 MW of power, has a major radius of 5.4 m and a minor radius of 1.0 m with an elongation of 2.0. Double null poloidal divertors are assumed for impurity control. The confining toroidal field is maintained by D-shaped Nb 3 Sn superconducting magnets with a maximum field of 12T at the coil. Three blankets with four associated fuel cycle alternatives have been combined with the ignited tokamak fusion driver. The engineering, material, and balance of plant design requirements for the THR are briefly described. Estimates of the capital, operating and maintenance, and fuel cycle costs have been made for the various driver/blanket combinations and an assessment of the market penetrability of hybrid systems is presented. An analysis has been made of the nonproliferation aspects of the hybrid and its associated fuel cycles relative to fission reactors. The current and required level of technology for both the fusion and fission components of the hybrid system has been reviewed. Licensing hybrid systems is also considered

High-precision spectrometer for studies of ion-induced and spontaneous fission dynamics

International Nuclear Information System (INIS)

Batenkov, O.; Elmgren, K.; Majorov, M.; Blomgren, J.; Conde, H.; Hultqvist, S.; Olsson, N.; Rahm, J.; Ramstroem, E.; Smirnov, S.; Veshikov, A.

1997-01-01

A spectrometer has been designed and built to investigate the dynamics of spontaneous and ion-induced fission processes. It consists of 8 neutron detectors surrounding a low mass scattering chamber containing the fissionable targets and two fission fragment telescopes. The spectrometer measures neutron spectra, and energy and angular correlations of neutrons, as well as kinetic energy, mass, and relative angle of fission fragments. A 252 Cf fission reference source is used for calibration. (orig.)

The nuclear fission

International Nuclear Information System (INIS)

Fiorentino, J.

1983-01-01

The nuclear fission process considering initially the formation of compound nucleus and finishing with radioactive decay of fission products is studied. The process is divided in three parts which consist of the events associated to the nucleus of intermediate transitional state, the scission configuration, and the phenomenum of post scission. (M.C.K.) [pt

Microprobe study of fission product behavior in high-burnup HTR fuels

International Nuclear Information System (INIS)

Kleykamp, H.

Electron microprobe analysis of irradiated coated particles with high burnup (greater than 50 percent fima) gives detailed information on the chemical state and the transport behavior of the fission products in UO 2 and UC 2 kernels and in the coatings. In oxide fuel kernels, metallic inclusions and ceramic precipitations are observed. The solubility behavior of the fission products in the fuel matrix has been investigated. Fission product inclusions could not be detected in carbide fuel kernels; post irradiation annealed UC 2 kernels, however, give information on the element combinations of some fission product phases. Corresponding to the chemical state in the kernel, Cs, Sr, Ba, Pd, Te and the rare earths are released easily and diffuse through the entire pyrocarbon coating. These fission products can be retained by a silicon carbide layer. The initial stage of a corrosive attack of the SiC coating by the fission products is evidenced

Fission yield measurements at IGISOL

Science.gov (United States)

Lantz, M.; Al-Adili, A.; Gorelov, D.; Jokinen, A.; Kolhinen, V. S.; Mattera, A.; Moore, I.; Penttilä, H.; Pomp, S.; Prokofiev, A. V.; Rakopoulos, V.; Rinta-Antila, S.; Simutkin, V.; Solders, A.

2016-06-01

The fission product yields are an important characteristic of the fission process. In fundamental physics, knowledge of the yield distributions is needed to better understand the fission process. For nuclear energy applications good knowledge of neutroninduced fission-product yields is important for the safe and efficient operation of nuclear power plants. With the Ion Guide Isotope Separator On-Line (IGISOL) technique, products of nuclear reactions are stopped in a buffer gas and then extracted and separated by mass. Thanks to the high resolving power of the JYFLTRAP Penning trap, at University of Jyväskylä, fission products can be isobarically separated, making it possible to measure relative independent fission yields. In some cases it is even possible to resolve isomeric states from the ground state, permitting measurements of isomeric yield ratios. So far the reactions U(p,f) and Th(p,f) have been studied using the IGISOL-JYFLTRAP facility. Recently, a neutron converter target has been developed utilizing the Be(p,xn) reaction. We here present the IGISOL-technique for fission yield measurements and some of the results from the measurements on proton induced fission. We also present the development of the neutron converter target, the characterization of the neutron field and the first tests with neutron-induced fission.

Fission yield measurements at IGISOL

Directory of Open Access Journals (Sweden)

Lantz M.

2016-01-01

Full Text Available The fission product yields are an important characteristic of the fission process. In fundamental physics, knowledge of the yield distributions is needed to better understand the fission process. For nuclear energy applications good knowledge of neutroninduced fission-product yields is important for the safe and efficient operation of nuclear power plants. With the Ion Guide Isotope Separator On-Line (IGISOL technique, products of nuclear reactions are stopped in a buffer gas and then extracted and separated by mass. Thanks to the high resolving power of the JYFLTRAP Penning trap, at University of Jyväskylä, fission products can be isobarically separated, making it possible to measure relative independent fission yields. In some cases it is even possible to resolve isomeric states from the ground state, permitting measurements of isomeric yield ratios. So far the reactions U(p,f and Th(p,f have been studied using the IGISOL-JYFLTRAP facility. Recently, a neutron converter target has been developed utilizing the Be(p,xn reaction. We here present the IGISOL-technique for fission yield measurements and some of the results from the measurements on proton induced fission. We also present the development of the neutron converter target, the characterization of the neutron field and the first tests with neutron-induced fission.

$\\beta$-delayed fission, laser spectroscopy and shape-coexistence studies with radioactive At beams

CERN Multimedia

We propose to study the $\\beta$-delayed fission, laser spectroscopy and radioactive decay of the newly available pure beams of neutron-deficient and neutron-rich astatine (Z=85) isotopes. The fission probability and the fission fragment distribution of the even-even isotopes $^{194,196}$Po following the $\\beta$-decay of the isotopes $^{194,196}$At will be studied with the Windmill setup. In-source laser spectroscopy will be performed on the entire astatine isotopic chain, using a combination of the Windmill setup, ISOLTRAP MR-ToF and ISOLDE Faraday. Radioactive decay data will be acquired at the Windmill setup throughout those studies and contribute to the global understanding of the phenomenon of shape coexistence in the neutron-deficient lead region.

Enhanced fuel production in thorium/lithium hybrid blankets utilizing uranium multipliers

Energy Technology Data Exchange (ETDEWEB)

Pitulski, R.H.

1979-10-01

A consistent neutronics analysis is performed to determine the effectiveness of uranium bearing neutron multiplier zones on increasing the production of U/sup 233/ in thorium/lithium blankets for use in a tokamak fusion-fission hybrid reactor. The nuclear performance of these blankets is evaluated as a function of zone thicknesses and exposure by using the coupled transport burnup code ANISN-CINDER-HIC. Various parameters such as U/sup 233/, Pu/sup 239/, and H/sup 3/ production rates, the blanket energy multiplication, isotopic composition of the fuels, and neutron leakages into the various zones are evaluated during a 5 year (6 MW.y.m/sup -2/) exposure period. Although the results of this study were obtained for a tokomak magnetic fusion device, the qualitative behavior associated with the use of the uranium bearing neutron multiplier should be applicable to all fusion-fission hybrids.

Role of a hybrid (fusion--fission) reactor in a nuclear economy

International Nuclear Information System (INIS)

Wolkenhauer, W.C.

1974-01-01

Some of the hybrid concepts which have been proposed to date are separated into groups according to their apparent neutronic characteristics. An attempt is made to identify these hybrid groups with two possible roles in a nuclear economy. An analysis is made to see if there is enough current information to determine which hybrid concepts appear most promising when assigned to these roles. (U.S.)

Relativistic Coulomb Fission

Science.gov (United States)

Norbury, John W.

1992-01-01

Nuclear fission reactions induced by the electromagnetic field of relativistic nuclei are studied for energies relevant to present and future relativistic heavy ion accelerators. Cross sections are calculated for U-238 and Pu-239 fission induced by C-12, Si-28, Au-197, and U-238 projectiles. It is found that some of the cross sections can exceed 10 b.

Post-scission fission theory: Neutron emission in fission

International Nuclear Information System (INIS)

Madland, D.G.

1997-01-01

A survey of theoretical representations of two of the observables in neutron emission in fission is given, namely, the prompt fission neutron spectrum N (E) and the average prompt neutron multiplicity bar ν p . Early representations of the two observables are presented and their deficiencies are discussed. This is followed by summaries and examples of recent theoretical models for the calculation of these quantities. Emphasis is placed upon the predictability and accuracy of the recent models. In particular, the dependencies of N (E) and bar ν p upon the fissioning nucleus and its excitation energy are treated. Recent work in the calculation of the prompt fission neutron spectrum matrix N (E, E n ), where E n is the energy of the neutron inducing fission, is then discussed. Concluding remarks address the current status of our ability to calculate these observables with confidence, the direction of future theoretical efforts, and limitations to current (and future) approaches

Dual-fission chamber and neutron beam characterization for fission product yield measurements using monoenergetic neutrons

Science.gov (United States)

Bhatia, C.; Fallin, B.; Gooden, M. E.; Howell, C. R.; Kelley, J. H.; Tornow, W.; Arnold, C. W.; Bond, E. M.; Bredeweg, T. A.; Fowler, M. M.; Moody, W. A.; Rundberg, R. S.; Rusev, G.; Vieira, D. J.; Wilhelmy, J. B.; Becker, J. A.; Macri, R.; Ryan, C.; Sheets, S. A.; Stoyer, M. A.; Tonchev, A. P.

2014-09-01

A program has been initiated to measure the energy dependence of selected high-yield fission products used in the analysis of nuclear test data. We present out initial work of neutron activation using a dual-fission chamber with quasi-monoenergetic neutrons and gamma-counting method. Quasi-monoenergetic neutrons of energies from 0.5 to 15 MeV using the TUNL 10 MV FM tandem to provide high-precision and self-consistent measurements of fission product yields (FPY). The final FPY results will be coupled with theoretical analysis to provide a more fundamental understanding of the fission process. To accomplish this goal, we have developed and tested a set of dual-fission ionization chambers to provide an accurate determination of the number of fissions occurring in a thick target located in the middle plane of the chamber assembly. Details of the fission chamber and its performance are presented along with neutron beam production and characterization. Also presented are studies on the background issues associated with room-return and off-energy neutron production. We show that the off-energy neutron contribution can be significant, but correctable, while room-return neutron background levels contribute less than <1% to the fission signal.

Fission products collecting devices

International Nuclear Information System (INIS)

Matsumoto, Hiroshi

1979-01-01

Purpose: To enable fission products trap with no contamination to coolants and cover gas by the provision of a fission products trap above the upper part of a nuclear power plant. Constitution: Upon fuel failures in a reactor core, nuclear fission products leak into coolants and move along the flow of the coolants to the coolants above the reactor core. The fission products are collected in a trap container and guided along a pipeline into fission products detector. The fission products detector monitors the concentration of the fission products and opens the downstream valve of the detector when a predetermined concentration of the fission products is detected to introduce the fission products into a waste gas processing device and release them through the exhaust pipe. (Seki, T.)

Observed mass distribution of spontaneous fission fragments from samples of lime - an SSNTD study

CERN Document Server

Paul, D; Ghose, D; Sastri, R C

1999-01-01

SSNTD is one of the most commonly used detectors in the studies involving nuclear phenomena. The ease of registration of the presence of alpha particles and fission fragments has made it particularly suitable in studies where stable long exposures are needed to extract reliable information. Studies on the presence of alpha emitting nuclides in the environment assume importance since they are found to be carcinogenic. Lime samples from Silchar in Assam of Eastern India have shown the presence of spontaneous fission fragments besides alphas. In the present study we look at the ratio of the average mass distribution of these fission fragments, that gives us an indication of the presence of the traces of transuranic elements.

Further microscopic studies of the fission barriers of heavy nuclei

International Nuclear Information System (INIS)

Nhan Hao, T.V.; Le Bloas, J.; Bonneau, L.; Quentin, P.; Koh, Meng-Hock

2012-01-01

Two systematic sources of error in most current microscopic evaluations of fission-barrier heights are studied. They are concerned with an approximate treatment of the Coulomb exchange terms (known as the Slater approximation) in the self-consistent mean-fields and the projection on good parity states (e.g., of positive parity for the spontaneous fission of an even–even nucleus) of left–right reflection asymmetric intrinsic solutions (e.g., around the second barrier). Approximate or unprojected solutions are shown to lead each to an underestimation of the barrier heights by a few hundred keV. (author)

Study of the desintegration of short-life fission products. Application to the mass distribution in the fission of 238U and 233U induced by 14MeV neutrons

International Nuclear Information System (INIS)

Cavallini, Pierre.

1975-01-01

Nuclear spectrometry of short-life fission products was investigated, together with direct applications to the study of mass and charge distribution in fission reactions. It is shown that, by choosing judiciously the target in which the fission product is created and owing to the differences in stabilities and evaporation temperatures of the compounds obtained, it is possible to separate some elements. For example, niobium was separated by heating after irradiation of a mixture of UC and RuCl 3 , and sublimation in a tube with temperature gradient. It was thus possible to study the 99 Nb isotope. Other classical chemical separation processes were used for yttrium and strontium. The half-lifes beta and gamma spectra, decay schemes of 93 Sr, 94 Y and 95 Y were studied. It was shown how to obtain mass distribution in fission using a nondestructive gamma analysis method. As an application, results obtained in the fission of 233 U and 238 U at 14 MeV are given [fr

Fission in a Plasma

Energy Technology Data Exchange (ETDEWEB)

Younes, W. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2016-10-26

A three-year theory project was undertaken to study the fission process in extreme astrophysical environments, such as the crust of neutron stars. In the first part of the project, the effect of electron screening on the fission process was explored using a microscopic approach. For the first time, these calculations were carried out to the breaking point of the nucleus. In the second part of the project, the population of the fissioning nucleus was calculated within the same microscopic framework. These types of calculations are extremely computer-intensive and have seldom been applied to heavy deformed nuclei, such as fissioning actinides. The results, tools and methodologies produced in this work will be of interest to both the basic-science and nuclear-data communities.

Fission of heavy nuclei: microscopic study of fission barriers and fragments angular momentum; Fission des noyaux lourds: etude microscopique des barrieres de fission et du moment angulaire des fragments

Energy Technology Data Exchange (ETDEWEB)

Bonneau, L

2003-11-01

A lot of experimental data on nuclear fission has been being collected for the last 65 years, allowing theoreticians to confront their models with reality. The first part of this work is dedicated to the computation of fission barriers. We have extended the HF + BCS (Hartree Fock + Bandeen-Cooper-Schrieffer) method in order to include a new set of polynomials on which wave functions can be broken to, more accurately than on Hermite's polynomials in the 2 fragment configuration. The fission barriers of 26 heavy nuclei from Thorium-230 to Nobelium-256 have been assessed and compared to experimental data, it appears that differences are no greater than 1 MeV. We have discovered a neat correlation between the variation of the experimental fission lifetimes of even Fermium isotopes and the computed heights of second barriers. Moreover our model reproduces the hyper-deformed well of Thorium-230 with a good agreement on the well depth. The second part deals with the scission region. We have performed Hartree-Fock calculations in order to explore different ways of fragmentation. We have shown that the harmonic oscillator gives a valid description of such ways. In order to compute the mean value of J{sup 2} in the fragments we have been driven to propose an adequate definition of that quantity consistent with the non-locality property of the J{sup 2} operator. (A.C.)

Physics and chemistry of fission

International Nuclear Information System (INIS)

1979-01-01

Full text: In the pleasant and hospitable atmosphere of the Kernforschungsanlage Juelich in the Federal Republic of Germany, the IAEA symposium on the Physics and Chemistry of Fission took place. Almost 200 scientists attended, 154 abstracts were submitted, and 57 papers presented, but more important than the numbers was the quality of the contributions and the progress reported at the symposium. The neutron was discovered almost 50 years ago; 40 years ago the idea of nuclear fission was born. Since then, a number of laboratories have worked hard to explain the phenomenon of fission One would expect that by now scientists would know exactly what happens in a nucleus before and during the process of fission, particularly as there are hundreds of power and research reactors in operation, and fission of uranium isotopes is the basis of their functioning. At first glance, fission seems a simple process: a neutron hits and penetrates the uranium nucleus which becomes excited, i.e. has a surplus of energy. One way to get rid of this energy is for the nucleus to split into two parts; additional products of this process are energy and more neutrons. Nature, however, seems to dislike such straightforward explanations. In the case of fission, scientists have observed a number of phenomena which disagree with a simple model. Sometimes, a nucleus will split into two parts without being 'attacked' by a neutron; this spontaneous fission opens up a new line of fission research and several contributions at the symposium reported on sophisticated experiments designed to unravel some of its specific details. Sometimes, a fissioning nucleus will emit another particle: ternary fission has become a powerful tool for studying the properties of nuclei during the fission process. For the scientist, it is fascinating to observe how the nucleus behaves during fission. They invent models which are supposed to reproduce the most probable course of events leading to fission. In one of these

Fission dynamics with systems of intermediate fissility

Indian Academy of Sciences (India)

results concerning nuclear dissipation and fission time-scale obtained from several of these studies. In particular ... alent to the assumption that fission is delayed, namely, that the fission probability is not .... parameters to be adjusted on the experimental data. ..... (b) Time distribution of all fission events for the 132Ce nucleus.

What do we learn on the dynamics of fission from α-accompanied fission data

International Nuclear Information System (INIS)

Guet, C.; Asghar, M.; Nifenecker, H.; Perrin, P.

1978-01-01

Measurements of the angular distribution of α-particles emitted by thermal fission of 236 U are presented. Also the dependence of the angular distribution on the kinetic energy of the fission products is studied. (WL) [de

Identification and systematical studies of the electron-capture delayed fission (ECDF) in the lead region

CERN Multimedia

Pauwels, D B; Lane, J

2008-01-01

In our recent experiment (March 2007) at the velocity filter SHIP(GSI) we observed the electron-capture delayed fission of the odd-odd isotope $^{194}$At. This is the first unambiguous identification of this phenomenon in the very neutron-deficient nuclei in the vicinity of the proton shell closure at Z=82. In addition, the total kinetic energy (TKE) for the daughter nuclide $^{194}$Po was measured, despite the fact that this isotope does not decay via spontaneous fission. Semi-empirical analysis of the electron-capture Q$_{EC}$ values and fission barriers B$_{f}$ shows that a relatively broad island of ECDF must exist in this region of the Nuclide Chart, with some of the nuclei having unusually high ECDF probabilities. Therefore, this Proposal is intended to initiate the systematic identification and study of $\\beta$-delayed fission at ISOLDE in the very neutron-deficient lead region. Our aim is to provide unique low-energy fission data (e.g. probabilities, TKE release, fission barriers and their isospin dep...

Fission-product yields for thermal-neutron fission of curium-243

International Nuclear Information System (INIS)

Breederland, D.G.

1982-01-01

Cumulative fission yields for 25 gamma rays emitted during the decay of 23 fission products produced by thermal-neutron fission of 243 Cm have been determined. Using Ge(Li) spectroscopy, 33 successive pulse-height spectra of gamma rays emitted from a 77-ng sample of 243 Cm over a period of approximately two and one-half months were analyzed. Reduction of these spectra resulted in the identification and matching of gamma-ray energies and half-lives to specific radionuclides. Using these results, 23 cumulative fission-product yields were calculated. Only those radionuclides having half-lives between 6 hours and 65 days were observed. Prior to this experiment, no fission-product yields had been recorded for 243 Cm

Evaporation channel as a tool to study fission dynamics

Science.gov (United States)

Di Nitto, A.; Vardaci, E.; La Rana, G.; Nadtochy, P. N.; Prete, G.

2018-03-01

The dynamics of the fission process is expected to affect the evaporation residue cross section because of the fission hindrance due to the nuclear viscosity. Systems of intermediate fissility constitute a suitable environment for testing such hypothesis since they are characterized by evaporation residue cross sections comparable or larger than the fission ones. Observables related to emitted charged particles, due to their relatively high emission probability, can be used to put stringent constraints on models describing the excited nucleus decay and to recognize the effects of fission dynamics. In this work model simulations are compared with the experimental data collected via the 32S +100 Mo reaction at Elab = 200 MeV. Consequently we pointed out, exploring an extended set of evaporation channel observables, the limits of the statistical model and the large improvement obtained with a dynamical model. Moreover we stress the importance of using an apparatus covering a large fraction of 4π to extract observables. Finally, we discuss the opportunity to measure more sensitive observables by a new detection device in operation at LNL.

Fusion--fission hybrid reactors based on the laser solenoid

International Nuclear Information System (INIS)

Steinhauer, L.C.; Taussig, R.T.; Quimby, D.C.

1976-01-01

Fusion-fission reactors, based on the laser solenoid concept, can be much smaller in scale than their pure fusion counterparts, with moderate first-wall loading and rapid breeding capabilities (1 to 3 tonnes/yr), and can be designed successfully on the basis of classical plasma transport properties and free-streaming end-loss. Preliminary design information is presented for such systems, including the first wall, pulse coil, blanket, superconductors, laser optics, and power supplies, accounting for the desired reactor performance and other physics and engineering constraints. Self-consistent point designs for first and second generation reactors are discussed which illustrate the reactor size, performance, component parameters, and the level of technological development required

Neutron emission as a probe of fusion-fission and quasi-fission dynamics

International Nuclear Information System (INIS)

Hinde, D.J.

1991-01-01

Pre- and post scission neutron yeilds have been measured as a function of projectile mass, compound nucleus fissility, and fission mass-split and total kinetic energy (TKE) for 27 fusion-fission and quasi-fission reactions induced by beams of 16,18 O, 40 Ar and 64 Ni. A new method of interpretation of experimental pre-scission neutron multiplicities ν-pre and mean kinetic energies ε ν allows the extraction of fission time scales with much less uncertainty than previously, all fusion-fission results being consistent with a dynamical time scale of (35±15) x 10 -21 s for symmetric fission. All reactions show that ν-pre falls quite rapidly with increasing mass-asymmetry; evidence is presented that for fusion-fission reactions this is partly due to a reduction of the dynamical fission time scale with mass-asymmetry. For quasi-fission, the data indicate that the pre-scission multiplicity and mean neutron kinetic energy are very sensitive to the final mass-asymmetry, but that the time scale is virtually independent of mass-asymmetry. It is concluded that for fusion-fission there is no dependence of ν-pre on TKE, whilst for 64 Ni-induced quasi-fission reactions, a strong increase of ν-pre with decreasing TKE is observed, probably largely caused by neutron emission during the acceleration time of the fission fragments in these fast reactions. Interpretation of post-scission multiplicities in terms of fragment excitation energies leads to deduced time scales consistent with those determined from the pre-scission data. 54 refs., 17 tabs., 25 figs

Energy released in fission

International Nuclear Information System (INIS)

James, M.F.

1969-05-01

The effective energy released in and following the fission of U-235, Pu-239 and Pu-241 by thermal neutrons, and of U-238 by fission spectrum neutrons, is discussed. The recommended values are: U-235 ... 192.9 ± 0.5 MeV/fission; U-238 ... 193.9 ± 0.8 MeV/fission; Pu-239 ... 198.5 ± 0.8 MeV/fission; Pu-241 ... 200.3 ± 0.8 MeV/fission. These values include all contributions except from antineutrinos and very long-lived fission products. The detailed contributions are discussed, and inconsistencies in the experimental data are pointed out. In Appendix A, the contribution to the total useful energy release in a reactor from reactions other than fission are discussed briefly, and in Appendix B there is a discussion of the variations in effective energy from fission with incident neutron energy. (author)

The evaluation for reference fission yield of 238U fission

International Nuclear Information System (INIS)

Liang Qichang; Liu Tingjin

1998-01-01

In the fission yield data evaluation and measurement, the reference yield is very important, good or poor recommended or measurement values depend upon the reference data to a great extent. According to the CRP's requirement, the evaluation of reference fission yields have been and will be carried out in CNDC, as a part of the whole work (contract No.9504/R 0 /Regular Budget Fund), the evaluation for 29 reference fission yields of 15 product nuclides from 238 U fission have been completed

Fission product behaviour in severe accidents

International Nuclear Information System (INIS)

Jokiniemi, J.; Auvinen, A.; Maekynen, J.; Valmari, T.

1998-01-01

The understanding of fission product (FP) behaviour in severe accidents is important for source term assessment and accident mitigation measures. For example in accident management the operator needs to know the effect of different actions on the behaviour and release of fission products. At VTT fission product behaviour have been studied in different national and international projects. In this presentation the results of projects in EU funded 4th framework programme Nuclear Fission Safety 1994-1998 are reported. The projects are: fission product vapour/aerosol chemistry in the primary circuit (FI4SCT960020), aerosol physics in containment (FI4SCT950016), revaporisation of test samples from Phebus fission products (FI4SCT960019) and assessment of models for fission product revaporisation (FI4SCT960044). Also results from the national project 'aerosol experiments in the Victoria facility' funded by IVO PE and VTT Energy are reported

Experimental approach to fission process of actinides

Energy Technology Data Exchange (ETDEWEB)

Baba, Hiroshi [Osaka Univ., Toyonaka (Japan). Faculty of Science

1997-07-01

From experimental views, it seems likely that the mechanism of nuclear fission process remains unsolved even after the Bohr and Weeler`s study in 1939. Especially, it is marked in respect of mass distribution in unsymmetric nuclear fission. The energy dependency of mass distribution can be explained with an assumption of 2-mode nuclear fission. Further, it was demonstrated that the symmetrical fission components and the unsymmetrical ones have different saddle and fission points. Thus, the presence of the 2-mode fission mechanism was confirmed. Here, transition in the nuclear fission mechanism and its cause were investigated here. As the cause of such transition, plausible four causes; a contribution of multiple-chance fission, disappearance of shell effects, beginning of fission following collective excitation due to GDR and nuclear phase transition were examined in the condition of excitation energy of 14.0 MeV. And it was suggested that the transition in the nuclear fission concerned might be related to phase transition. In addition, the mechanism of nuclear fission at a low energy and multi-mode hypothesis were examined by determination of the energy for thermal neutron fission ({sup 233,235}U and {sup 239}Pu) and spontaneous nuclear fission ({sup 252}Cf). (M.N.)

Burn-Up Determination by High Resolution Gamma Spectrometry: Fission Product Migration Studies

Energy Technology Data Exchange (ETDEWEB)

Forsyth, R S; Blackadder, W H; Ronqvist, N

1967-04-15

The migration of solid fission products, in particular caesium and ruthenium, in high temperature oxide fuel can create a severe problem during the application of non-destructive burn-up methods employing gamma spectrometry, since caesium-137 is otherwise the most convenient long-lived burn-up monitor and ruthenium-106 can be used to distinguish between fissions in U-235 and Pu-239. As part of an experimental programme to develop burn-up methods, gamma scanning experiments have been performed on slices of irradiated UO{sub 2} pellets using a lithium-drifted germanium detector. The usefulness of the technique for migration studies has been demonstrated by comparing the fission product distribution curves across the specimen diameters with the microstructure of the specimens after polishing and etching.

Consultancy to review and finalize the IAEA publication 'Compendium on the use of fusion/fission hybrids for the utilization and transmutation of actinides and long-lived fission products'. Working material

International Nuclear Information System (INIS)

2004-01-01

In addition to the traditional fission reactor research, fusion R and D activities are becoming of interest also to nuclear fission power development. There is renewed interest in utilizing fusion neutrons, Heavy Liquid Metals, and molten salts for innovative systems (energy production and transmutation). Indeed, for nuclear power development to become sustainable as a long-term energy option, innovative fuel cycle and reactor technologies will have to be developed to solve the problems of resource utilization and long-lived radioactive waste management. In this context Member States clearly expressed the need for comparative assessments of various transmutation reactors. Both the fusion and fission communities are currently investigating the potential of innovative reactor and fuel cycle strategies that include a fusion/fission system. The attention is mainly focused on substantiating the potential advantages of such systems: utilization and transmutation of actinides and long-lived fission products, intrinsic safety features, enhanced proliferation resistance, and fuel breeding capabilities. An important aspect of the ongoing activities is the comparison with the accelerator driven subcritical system (spallation neutron source), which is the other main option for producing excess neutrons. Apart from comparative assessments, knowledge preservation is another subject of interest to the Member States: the goal, applied to fusion/fission systems, is to review the status of, and to produce a 'compendium' of past and present achievements in this area

Computer program FPIP-REV calculates fission product inventory for U-235 fission

Science.gov (United States)

Brown, W. S.; Call, D. W.

1967-01-01

Computer program calculates fission product inventories and source strengths associated with the operation of U-235 fueled nuclear power reactor. It utilizes a fission-product nuclide library of 254 nuclides, and calculates the time dependent behavior of the fission product nuclides formed by fissioning of U-235.

Fission of heavy nuclei: microscopic study of fission barriers and fragments angular momentum; Fission des noyaux lourds: etude microscopique des barrieres de fission et du moment angulaire des fragments

Energy Technology Data Exchange (ETDEWEB)

Bonneau, L

2003-11-01

A lot of experimental data on nuclear fission has been being collected for the last 65 years, allowing theoreticians to confront their models with reality. The first part of this work is dedicated to the computation of fission barriers. We have extended the HF + BCS (Hartree Fock + Bandeen-Cooper-Schrieffer) method in order to include a new set of polynomials on which wave functions can be broken to, more accurately than on Hermite's polynomials in the 2 fragment configuration. The fission barriers of 26 heavy nuclei from Thorium-230 to Nobelium-256 have been assessed and compared to experimental data, it appears that differences are no greater than 1 MeV. We have discovered a neat correlation between the variation of the experimental fission lifetimes of even Fermium isotopes and the computed heights of second barriers. Moreover our model reproduces the hyper-deformed well of Thorium-230 with a good agreement on the well depth. The second part deals with the scission region. We have performed Hartree-Fock calculations in order to explore different ways of fragmentation. We have shown that the harmonic oscillator gives a valid description of such ways. In order to compute the mean value of J{sup 2} in the fragments we have been driven to propose an adequate definition of that quantity consistent with the non-locality property of the J{sup 2} operator. (A.C.)

Fusion breeder studies program: Final report

International Nuclear Information System (INIS)

Berwald, D.H.

1986-01-01

This report is an assessment of technology related to hybrid reactors, especially the Fission-suppressed hybrid. A description of a typical fission-suppressed reactor is given. The economic advantages of the use of a hybrid reactor as part of a fuel cycle center are discussed at length. The inherent safety advantages of the hybrid reactor are analyzed. The report concludes with a proposed timetable for research and development

Study of the Fission Decay of Heavy Hypernuclei

CERN Multimedia

2002-01-01

The purpose of the original experiment PS177 was to produce heavy hypernuclei using the annihilation at rest of antiprotons in heavy targets, and to measure their lifetime. \\\\ \\\\ Lambda hyperons can be produced, within a nucleus, in a 2-step process: p@*~@A~K&bar.K~+~X; &bar.KN~@A~@L@p; or in a direct 3-body interaction: @*NN~@A~K|+@L. In the first case, the kinematical conditions favour recoilless lambda with, consequently, a higher probability of attachment to the nucleus. In a heavy nucleus the lambda-hyperon decays weakly according to: @LN~@A~NN, and the &prop.170~MeV energy released induces fission.\\\\ \\\\ The identification of the hypernuclei and their lifetime measurements were performed through the detection of delayed fission using the recoil-distance-method (suitable for lifetimes in the expected region @=10|-|1|0s). The fission fragments were detected by parallel-plate avalanche counters. \\\\ \\\\ The new proposal aims at i) increasing the accuracy of the measured lifetimes, ii) having a str...

(d,p)-transfer induced fission of heavy radioactive beams

CERN Document Server

Veselsky, Martin

2012-01-01

(d,p)-transfer induced fission is proposed as a tool to study low energy fission of exotic heavy nuclei. Primary goal is to directly determine the fission barrier height of proton-rich fissile nuclei, preferably using the radio-active beams of isotopes of odd elements, and thus confirm or exclude the low values of fission barrier heights, typically extracted using statistical calculations in the compound nucleus reactions at higher excitation energies. Calculated fission cross sections in transfer reactions of the radioactive beams show sufficient sensitivity to fission barrier height. In the probable case that fission rates will be high enough, mass asymmetry of fission fragments can be determined. Results will be relevant for nuclear astrophysics and for production of super-heavy nuclei. Transfer induced fission offers a possibility for systematic study the low energy fission of heavy exotic nuclei at the ISOLDE.

Mica fission detectors

International Nuclear Information System (INIS)

Wong, C.; Anderson, J.D.; Hansen, L.; Lehn, A.V.; Williamson, M.A.

1977-01-01

The present development status of the mica fission detectors is summarized. It is concluded that the techniques have been refined and developed to a state such that the mica fission counters are a reliable and reproducible detector for fission events

Nuclear fission: a review of experimental advances and phenomenology

Science.gov (United States)

Andreyev, A. N.; Nishio, K.; Schmidt, K.-H.

2018-01-01

In the last two decades, through technological, experimental and theoretical advances, the situation in experimental fission studies has changed dramatically. With the use of advanced production and detection techniques both much more detailed and precise information can now be obtained for the traditional regions of fission research and, crucially, new regions of nuclei have become routinely accessible for fission studies. This work first of all reviews the recent developments in experimental fission techniques, in particular the resurgence of transfer-induced fission reactions with light and heavy ions, the emerging use of inverse-kinematic approaches, both at Coulomb and relativistic energies, and of fission studies with radioactive beams. The emphasis on the fission-fragment mass and charge distributions will be made in this work, though some of the other fission observables, such as prompt neutron and γ-ray emission will also be reviewed. A particular attention will be given to the low-energy fission in the so far scarcely explored nuclei in the very neutron-deficient lead region. They recently became the focus for several complementary experimental studies, such as β-delayed fission with radioactive beams at ISOLDE(CERN), Coulex-induced fission of relativistic secondary beams at FRS(GSI), and several prompt fusion–fission studies. The synergy of these approaches allows a unique insight in the new region of asymmetric fission around {\\hspace{0pt}}180 Hg, recently discovered at ISOLDE. Recent extensive theoretical efforts in this region will also be outlined. The unprecedented high-quality data for fission fragments, completely identified in Z and A, by means of reactions in inverse kinematics at FRS(GSI) and VAMOS(GANIL) will be also reviewed. These experiments explored an extended range of mercury-to-californium elements, spanning from the neutron-deficient to neutron-rich nuclides, and covering both asymmetric, symmetric and transitional fission regions

Studies on the fission products behavior during dissolution process of BWR spent fuel

International Nuclear Information System (INIS)

Sato, K.; Nakai, E.; Kobayashi, Y.

1987-01-01

In order to obtain basic data on fission products behavior in connection with the head end process of fuel reprocessing, especially to obtain better understanding on undissolved residues, small scale dissolution studies were performed by using BWR spent fuel rods which were irradiated as monitoring fuel rods under the monitoring program for LWR fuel assembly performance entitled PROVING TEST ON RELIABILITY OF FUEL ASSEMBLY . The Zircaloy-2 claddings and the fuel pellets were subjected individually to the following studies on 1) release of fission products during dissolution process, 2) characterization of undissolved residues, and 3) analysis of the claddings. This paper presents comprehensive descriptions of the fission products behavior during dissolution process, based on detailed and through PIE conducted by JNFS under the sponsorship of MITI (Ministry of International Trade and Industry)

Fission fragment angular distributions and fission cross section validation

International Nuclear Information System (INIS)

Leong, Lou Sai

2013-01-01

The present knowledge of angular distributions of neutron-induced fission is limited to a maximal energy of 15 MeV, with large discrepancies around 14 MeV. Only 238 U and 232 Th have been investigated up to 100 MeV in a single experiment. The n-TOF Collaboration performed the fission cross section measurement of several actinides ( 232 Th, 235 U, 238 U, 234 U, 237 Np) at the n-TOF facility using an experimental set-up made of Parallel Plate Avalanche Counters (PPAC), extending the energy domain of the incident neutron above hundreds of MeV. The method based on the detection of the 2 fragments in coincidence allowed to clearly disentangle the fission reactions among other types of reactions occurring in the spallation domain. I will show the methods we used to reconstruct the full angular resolution by the tracking of fission fragments. Below 10 MeV our results are consistent with existing data. For example in the case of 232 Th, below 10 MeV the results show clearly the variation occurring at the first (1 MeV) and second (7 MeV) chance fission, corresponding to transition states of given J and K (total spin and its projection on the fission axis), and a much more accurate energy dependence at the 3. chance threshold (14 MeV) has been obtained. In the spallation domain, above 30 MeV we confirm the high anisotropy revealed in 232 Th by the single existing data set. I'll discuss the implications of this finding, related to the low anisotropy exhibited in proton-induced fission. I also explore the critical experiments which is valuable checks of nuclear data. The 237 Np neutron-induced fission cross section has recently been measured in a large energy range (from eV to GeV) at the n-TOF facility at CERN. When compared to previous measurements, the n-TOF fission cross section appears to be higher by 5-7 % beyond the fission threshold. To check the relevance of n-TOF data, we simulate a criticality experiment performed at Los Alamos with a 6 kg sphere of 237 Np. This

Studies on fission tracks and distributions of uranium and rare earths in granite materials

International Nuclear Information System (INIS)

Matsuda, Hiroshi; Sakanoue, Masanobu

1987-01-01

Many materials contain fossil records of the slow spontaneous fission of uranium they contain as an impurity. Fission fragments, heavy charged particles released in each fission event, produce microscopic trails of radiation damage that may persist over geological times and may be developed to a size observable under an optical microscope by a suitable etching treatment. Such tracks are also produced by fissions induced by thermal neutron irradiation of the uranium. When the material is heated sufficiently, it anneals and the the microscopic trails become shorter and narrower. The track density decreases, because the chemical etchant will not reach some of the shortened tracks. Measurements of track densities before and after annealing can be used, along with laboratory studies of annealing rates, to determine the annealing temperature. Also, the track density of induced fissions is related to the concentration of uranium and the fluence of neutrons to which it was exposed. If the track density due to induced fissions can be distinguished from that due to fossil tracks, estimates of either the concentration or the fluence can be made if the other is known. Two such materials (one a fragment of a granite paving stone, the other a piece of stained glass from a cathedral window) that had been exposed to the atomic bomb at Nagasaki were used in the present work. The fossil record in zircons in the granite was used to estimate the temperature to which it had been exposed in the bombing. Induced fissions were used to estimate the concentration of uranium in the zircons. Nonuniform heating and cooling and nearly uniform exposure to the neutrons make the granite sample unsuitable for determining the neutron fluence from the bomb. Induced fissions in the stained glass were used to estimate the concentration of uranium and the thermal neutron fluence from the A-bomb. Annealing of tracks in glass was also studied

Study of fission fragments produced by 14N + 235U reaction

International Nuclear Information System (INIS)

Yalcinkaya, M.; Erduran, M.N.; Ganioglu, E.; Akkus, B.; Bostan, M.; Gurdal, G.; Erturk, S.; Balabanski, D.; Minkova, A.; Danchev, M.

2005-01-01

This work was performed to understand the structure of neutron rich fission fragments around ∼ 130 region. A thin metallic 235 U target was bombarded by 14 N beam with 10 MeV/A from the Separated Sector Cyclotron at the National Accelerator Centre, Cape Town, South Africa. The main goal to detect and identify fission fragments and to obtain their mass distribution was achieved by using Solar Cell detectors in the AFRODITE (African Omnipurpose Detector for Innovative Techniques and Experiments) spectrometer. The X-rays emitted from fission fragments were detected by LEP detectors and γ rays emitted from excited states of the fission fragments were detected by CLOVER detectors in the spectrometer. (author)

Study on the formation of fission isomer via 232Th + α reaction

International Nuclear Information System (INIS)

Vianna, D.M.

1982-01-01

The formation of fission isomer through 232 Th+α reaction is studied using the distance-recoil method, employing policarbonate MAKROFOL detector. The total isomeric half-life measured has the value T 1/2 = 0.23 ± 0.03 ns and an ratio of formation of isomeric fission relative to prompt fission(σ i /σ p =0.75x10 -5 ). According to the energy of incident particle (Eα = 28 MeV), the cross-sections presented in the literature and the low value found for the total isomeric half-life, we attribute these half-life value to the 234 U isomer (even-even nucleus). The results were compared with those existent in the literature (La69, E170, Re70, Wo70, Po70, Br71) for this isomer. (author) [pt

Measurements of fission yields

International Nuclear Information System (INIS)

Denschlag, H.O.

2000-01-01

After some historical introductory remarks on the discovery of nuclear fission and early fission yield determinations, the present status of knowledge on fission yields is briefly reviewed. Practical and fundamental reasons motivating the pursuit of fission yield measurements in the coming century are pointed out. Recent results and novel techniques are described that promise to provide new interesting insights into the fission process during the next century. (author)

Measurement of prompt fission gamma-ray spectra in fast neutron-induced fission

International Nuclear Information System (INIS)

Laborie, J.M.; Belier, G.; Taieb, J.

2012-01-01

Knowledge of prompt fission gamma-ray emission has been of major interest in reactor physics for a few years. Since very few experimental spectra were ever published until now, new measurements would be also valuable to improve our understanding of the fission process. An experimental method is currently being developed to measure the prompt fission gamma-ray spectrum from some tens keV up to 10 MeV at least. The mean multiplicity and total energy could be deduced. In this method, the gamma-rays are measured with a bismuth germanate (BGO) detector which has the advantage to present a high P/T ratio and a high efficiency compared to other gamma-ray detectors. The prompt fission neutrons are rejected by the time of flight technique between the BGO detector and a fission trigger given by a fission chamber or a scintillating active target. Energy and efficiency calibration of the BGO detector were carried out up to 10.76 MeV by means of the Al-27(p, gamma) reaction. First prompt fission gamma-ray spectrum measurements performed for the spontaneous fission of Cf-252 and for 1.7 and 15.6 MeV neutron-induced fission of U-238 at the CEA, DAM, DIF Van de Graaff accelerator, will be presented. (authors)

Contribution to the study of the influences of the excitation energy on the characteristics of the fission process

International Nuclear Information System (INIS)

Wagemans, C.

1979-01-01

Neutron induced and spontaneous fission with neutron energies from 10 -2 to 2.10 5 eV have been studied. Thermal neutron induced fission measurements in Pa 231 , Th 232 , Np 237 , U 233 , U 235 , Pu 239 and Pu 241 are reported. Energy and mass distributions of heavy fission fragments due to the spontaneous fission of Pu 240 are compared to the results obtained by thermal neutron fission of Pu 239 ; the events observed with U 236 , Pu 240 , Pa 232 and Np 238 are explained by the Bohr theory of fission channels. Ternary fission phenomena of U 233 , U 235 , Pu 239 , Pa 231 and Np 237 induced by thermal neutrons are explained and compared to models of Carjan and Feather. (MDC)

System model for analysis of the mirror fusion-fission reactor

International Nuclear Information System (INIS)

Bender, D.J.; Carlson, G.A.

1977-01-01

This report describes a system model for the mirror fusion-fission reactor. In this model we include a reactor description as well as analyses of capital cost and blanket fuel management. In addition, we provide an economic analysis evaluating the cost of producing the two hybrid products, fissile fuel and electricity. We also furnish the results of a limited parametric analysis of the modeled reactor, illustrating the technological and economic implications of varying some important reactor design parameters

International conference on fifty years research in nuclear fission

International Nuclear Information System (INIS)

1989-02-01

These proceedings contain extended abstracts of the papers presented at the named conference. They deal with static properties of fission, instrumentation for fission studies, fission in compound-nucleus reactions, fission dynamics, fission-like heavy ion reactions, and fusion reactions. See hints under the relevant topics. (HSI)

Theoretical Description of the Fission Process

International Nuclear Information System (INIS)

Nazarewicz, Witold

2009-01-01

Advanced theoretical methods and high-performance computers may finally unlock the secrets of nuclear fission, a fundamental nuclear decay that is of great relevance to society. In this work, we studied the phenomenon of spontaneous fission using the symmetry-unrestricted nuclear density functional theory (DFT). Our results show that many observed properties of fissioning nuclei can be explained in terms of pathways in multidimensional collective space corresponding to different geometries of fission products. From the calculated collective potential and collective mass, we estimated spontaneous fission half-lives, and good agreement with experimental data was found. We also predicted a new phenomenon of trimodal spontaneous fission for some transfermium isotopes. Our calculations demonstrate that fission barriers of excited superheavy nuclei vary rapidly with particle number, pointing to the importance of shell effects even at large excitation energies. The results are consistent with recent experiments where superheavy elements were created by bombarding an actinide target with 48-calcium; yet even at high excitation energies, sizable fission barriers remained. Not only does this reveal clues about the conditions for creating new elements, it also provides a wider context for understanding other types of fission. Understanding of the fission process is crucial for many areas of science and technology. Fission governs existence of many transuranium elements, including the predicted long-lived superheavy species. In nuclear astrophysics, fission influences the formation of heavy elements on the final stages of the r-process in a very high neutron density environment. Fission applications are numerous. Improved understanding of the fission process will enable scientists to enhance the safety and reliability of the nation's nuclear stockpile and nuclear reactors. The deployment of a fleet of safe and efficient advanced reactors, which will also minimize radiotoxic

Nuclear fission

International Nuclear Information System (INIS)

Kodama, T.

1981-01-01

The nuclear fission process is pedagogically reviewed from a macroscopic-microscopic point of view. The Droplet model is considered. The fission dynamics is discussed utilizing path integrals and semiclassical methods. (L.C.) [pt

Thorium-uranium fission radiography

Science.gov (United States)

Haines, E. L.; Weiss, J. R.; Burnett, D. S.; Woolum, D. S.

1976-01-01

Results are described for studies designed to develop routine methods for in-situ measurement of the abundance of Th and U on a microscale in heterogeneous samples, especially rocks, using the secondary high-energy neutron flux developed when the 650 MeV proton beam of an accelerator is stopped in a 42 x 42 cm diam Cu cylinder. Irradiations were performed at three different locations in a rabbit tube in the beam stop area, and thick metal foils of Bi, Th, and natural U as well as polished silicate glasses of known U and Th contents were used as targets and were placed in contact with mica which served as a fission track detector. In many cases both bare and Cd-covered detectors were exposed. The exposed mica samples were etched in 48% HF and the fission tracks counted by conventional transmitted light microscopy. Relative fission cross sections are examined, along with absolute Th track production rates, interaction tracks, and a comparison of measured and calculated fission rates. The practicality of fast neutron radiography revealed by experiments to data is discussed primarily for Th/U measurements, and mixtures of other fissionable nuclei are briefly considered.

Coulex fission of 234U, 235U, 237Np, and 238Np studied within the SOFIA experimental program

International Nuclear Information System (INIS)

Martin, Julie-Fiona

2014-01-01

SOFIA (Studies On FIssion with Aladin) is an experimental project which aims at systematically measuring the fission fragments' isotopic yields as well as their total kinetic energy, for a wide variety of fissioning nuclei. The PhD work presented in this dissertation takes part in the SOFIA project, and covers the fission of nuclei in the region of the actinides: 234 U, 235 U, 237 Np and 238 Np. The experiment is led at the heavy-ion accelerator GSI in Darmstadt, Germany. This facility provides intense relativistic primary beam of 238 U. A fragmentation reaction of the primary beam permits to create a secondary beam of radioactive ions, some of which the fission is studied. The ions of the secondary beam are sorted and identified through the FR-S (Fragment Separator), a high resolution recoil spectrometer which is tuned to select the ions of interest.The selected - fissile - ions then fly further to Cave-C, an experimental area where the fission experiment itself takes place. At the entrance of the cave, the secondary beam is excited by Coulomb interaction when flying through an target; the de-excitation process involves low-energy fission. Both fission fragments fly forward in the laboratory frame, due to the relativistic boost inferred from the fissioning nucleus.A complete recoil spectrometer has been designed and built by the SOFIA collaboration in the path of the fission fragments, around the existing ALADIN magnet. The identification of the fragments is performed by means of energy loss, time of flight and deviation in the magnet measurements. Both fission fragments are fully (in mass and charge) and simultaneously identified.This document reports on the analysis performed for (1) the identification of the fissioning system, (2) the identification of both fission fragments, on an event-by-event basis, and (3) the extraction of fission observables: yields, TKE, total prompt neutron multiplicity. These results, concerning the actinides, are discussed, and

Study of asymmetric fission yield behavior from neutron-deficient Hg isotope

International Nuclear Information System (INIS)

Perkasa, Y. S.; Waris, A.; Kurniadi, R.; Su'ud, Z.

2014-01-01

A study of asymmetric fission yield behavior from a neutron-deficient Hg isotope has been conducted. The fission yield calculation of the neutron-deficient Hg isotope using Brownian Metropolis shape had showed unusual result at decreasing energy. In this paper, this interesting feature will be validated by using nine degree of scission shapes parameterization from Brosa model that had been implemented in TALYS nuclear reaction code. This validation is intended to show agreement between both model and the experiment result. The expected result from these models considered to be different due to dynamical properties that implemented in both models

Yields of fission products produced by thermal-neutron fission of 229Th

International Nuclear Information System (INIS)

Dickens, J.K.; McConnell, J.W.

1983-01-01

Absolute yields have been determined for 47 gamma rays emitted in the decay of 37 fission products representing 25 mass chains created during thermal-neutron fission of 229 Th. Using a Ge(Li) detector, spectra were obtained of gamma rays emitted between 15 min and 0.4 yr after very short irradiations by thermal neutrons of a 15-μg sample of 229 Th. On the basis of measured gamma-ray yields and known nuclear data, yields for cumulative production of 37 fission products were deduced. The absolute overall normalization uncertainty is 235 U, we postulate a simple functional dependence sigma = sigma(Z/sub p/), and using this dependence obtain values of Z/sub p/(A) for 15 mass chains created during fission of 229 Th. Values of Z/sub p/(A) were estimated for other mass chains based upon results of a recent study of Z/sub p/(A). Charge distributions determined using the deduced mass distribution and the deduced sets of Z/sub p/(A) and sigma(Z/sub p/) are in very good agreement with recent measurements, exhibiting a pronounced even-odd effect in elemental yields. These results may be used to predict unmeasured yields for 229 Th fission

Towards a microscopic description of the fission process

CERN Document Server

Goutte, H; Berger, J F

2010-01-01

One major issue in nuclear physics is to develop a consistent model able to describe on the same footing the different aspects of the fission process, i.e. properties of the fissioning system, fission dynamics and fragment distributions. Microscopic fission studies based on the mean-field approximation are here presented.

Prompt fission neutron spectra of n + 235U above the (n, nf) fission threshold

International Nuclear Information System (INIS)

Shu Nengchuan; Chen Yongjing; Liu Tingjin; Jia Min

2015-01-01

Calculations of prompt fission neutron spectra (PFNS) from the 235 U(n, f) reaction were performed with a semi-empirical method for En = 7.0 and 14.7 MeV neutron energies. The total PFNS were obtained as a superposition of (n, xnf) pre-fission neutron spectra and post-fission spectra of neutrons which were evaporated from fission fragments, and these two kinds of spectra were taken as an expression of the evaporation spectrum. The contributions of (n, xnf) fission neutron spectra on the calculated PFNS were discussed. The results show that emission of one or two neutrons in the (n, nf) or (n, 2nf) reactions influences the PFNS shape, and the neutron spectra of the (n, xnf) fission-channel are soft compared with the neutron spectra of the (n, f) fission channel. In addition, analysis of the multiple-chance fission component showed that second-chance fission dominates the PFNS with an incident neutron energy of 14.7 MeV whereas first-chance fission dominates the 7 MeV case. (authors)

Fission product yields

International Nuclear Information System (INIS)

Valenta, V.; Hep, J.

1978-01-01

Data are summed up necessary for determining the yields of individual fission products from different fissionable nuclides. Fractional independent yields, cumulative and isobaric yields are presented here for the thermal fission of 235 U, 239 Pu, 241 Pu and for fast fission (approximately 1 MeV) of 235 U, 238 U, 239 Pu, 241 Pu; these values are included into the 5th version of the YIELDS library, supplementing the BIBFP library. A comparison is made of experimental data and possible improvements of calculational methods are suggested. (author)

Fission dynamics in the proton induced fission of heavy nuclei

Energy Technology Data Exchange (ETDEWEB)

Rubchenya, V.A. E-mail: rubchen@phys.jyu.fi; Trzaska, W.H.; Itkis, I.M.; Itkis, M.G.; Kliman, J.; Kniajeva, G.N.; Kondratiev, N.A.; Kozulin, E.M.; Krupa, L.; Pokrovski, I.V.; Voskressenski, V.M.; Hanappe, F.; Materna, T.; Dorvaux, O.; Stuttge, L.; Chubarian, G.; Khlebnikov, S.V.; Vakhtin, D.N.; Lyapin, V.G

2004-04-05

Multi-parameter correlation study of the reaction {sup 242}Pu(p, f) at E{sub p} 13, 20 and 55 MeV has been carried out. Fission fragment mass and kinetic energy distributions and the double differential neutron spectra have been measured. It was observed that the two-humped shape of mass distributions prevailed up to highest proton energy. Manifestation of the nuclear shell Z 28 near fragment mass A{sub fr} = 70 has been detected. The experimental results were analyzed in the framework of a time-dependent statistical model with inclusion of nuclear friction effects in the fission process. The multi-parameter correlation study of the reaction.

Cumulative fission yield of Ce-148 produced by thermal-neutron fission of U-235

International Nuclear Information System (INIS)

Hasan, A.A.

1984-12-01

Cumulative fission yield of 148 cesium isotopes and some other fission products produced by thermal-neutron fission of 235 uranium is determined by Germanium/Lithium spectroscopic methods. The measuremets were done at Tsing-Hua open pool reactor using 3 to 4 mg of 93.15% enriched 235 uranium samples. Gamma rays are assigned to the responsible fission products by matching gamma rays energies and half lives. Fission rate is calculated by fission track method. Cumulative fission yields of 148 cesium, 90 krypton, 130 iodine, 144 lanthanum, 89 krypton, 136 xenon, 137 xenon and 140 cesium are calculated. This values are compared with previously predicted values and showed good agreement. 21 Ref

Fusion-fission of heavy systems

International Nuclear Information System (INIS)

Rivet, M.F.; Alami, R.; Borderie, B.; Fuchs, H.; Gardes, D.; Gauvin, H.

1988-01-01

The influence of the entrance channel on fission processes was studied by forming the same composite system by two different target-projectile combinations ( 40 Ar + 209 Bi and 56 Fe + 187 Re, respectively). Compound nucleus fission and quasi fission were observed and the analysis was performed in the framework of the extra-extra-push model, which provides a qualitative interpretation of the results; limits for the extra-extra-push threshold are given, but problems with quantitative predictions for the extra-push are noted. (orig.)

Fission of nuclei far from stability

International Nuclear Information System (INIS)

Schmidt, K.H.; Benlliure, J.; Junghans, A.R.

2000-11-01

The secondary-beam facility of GSI provided the technical equipment for a new kind of fission experiment. Fission properties of short-lived neutron-deficient nuclei have been investigated in inverse kinematics. The measured element distributions reveal new kinds of systematics on shell structure and even-odd effects and lead to an improved understanding of structure effects in nuclear fission. Prospects for further experimental studies are discussed. (orig.)

Uranium resources and their implications for fission breeder and fusion hybrid development

International Nuclear Information System (INIS)

Max, C.E.

1984-01-01

Present estimates of uranium resources and reserves in the US and the non-Communist world are reviewed. The resulting implications are considered for two proposed breeder technologies: the liquid metal fast breeder reactor (LMFBR) and the fusion hybrid reactor. Using both simple arguments and detailed scenarios from the published literature, conditions are explored under which the LMFBR and fusion hybrid could respectively have the most impact, considering both fuel-supply and economic factors. The conclusions emphasize strong potential advantages of the fusion hybrid, due to its inherently large breeding rate. A discussion is presented of proposed US development strategies for the fusion hybrid, which at present is far behind the LMFBR in its practical application and maturity

Study of potential of nuclear waste transmutation and safety characteristics of an hybrid system: sub critical accelerator reactor; Etude du potentiel de transmutation et des caracteristiques de surete d`un systeme hybride: accelerateur reacteur sous critique

Energy Technology Data Exchange (ETDEWEB)

Tchistiakov, A

1998-04-01

The study of potential of nuclear waste transmutation for the new reactor systems - hybrid reactors - was the object of this work. Global review of different projects is presented. The basic physical parameters definitions, as neutron surplus and relative importance of external source neutrons, are introduced and explained. For these parameters, numerical values are obtained. The advantage in neutron surplus of fast system is noted. Equilibrium model and corresponding toxicities of different isotopes nd nuclear cycles are presented. Numerical analysis for equilibrium model converge validation are performed also. The study of neutron consumption by `transmutable` Long-Lived Fission Products (Tc, I and Cs) show the possibility of their incineration in dedicated fast hybrid reactors. Equilibrium model shown the influence of reprocessing losses level to cycle toxicity level. Relations between specific fuel inventories (mass normalised by power unit) for thermal and fast spectra are examined. The differences are relatively small. Finally, few hybrid reactor concepts with different objects were analysed. These studies confirm that in frameworks of certain Nuclear Energy scenarios the fast hybrid systems can reduce significantly the radio-toxicity of fuel cycle. Preliminary analyses of sub-critical reactor behaviour show big potential of this reactor type in `Transient of Power` kind of accident, even if more detailed study is necessary. (author)

Fission cross-section calculations and the multi-modal fission model

International Nuclear Information System (INIS)

Hambsch, F.J.

2004-01-01

New, self consistent, neutron-induced reaction cross section calculations for 235,238 U, 237 Np have been performed. The statistical model code STATIS was improved to take into account the multimodality of the fission process. The three most dominant fission modes, the two asymmetric standards I (S1) and standard II (S2) modes and the symmetric superlong (SL) mode have been taken into account. De-convoluted fission cross sections for those modes for 235,238 U(n,f) and 237 Np(n,f) based on experimental branching ratios, were calculated for the first time up to the second chance fission threshold. For 235 U(n,f), the calculations being made up to 28 MeV incident neutron energy, higher fission chances have been considered. This implied the need for additional calculations for the neighbouring isotopes. As a side product also mass yield distributions could be calculated at energies hitherto not accessible by experiment. Experimental validation of the predictions is being envisaged

Joint ICFRM-14 (14. international conference on fusion reactor materials) and IAEA satellite meeting on cross-cutting issues of structural materials for fusion and fission applications. PowerPoint presentations

International Nuclear Information System (INIS)

2009-01-01

The Conference was devoted to the challenges in the development of new materials for advanced fission, fusion and hybrid reactors. The topics discussed include fuels and materials research under the high neutron fluence; post-irradiation examination; development of radiation resistant structural materials utilizing fission research reactors; core materials development for the advanced fuel cycle initiative; qualification of structural materials for fission and fusion reactor systems; application of charged particle accelerators for radiation resistance investigations of fission and fusion structural materials; microstructure evolution in structural materials under irradiation; ion beams and ion accelerators

Fission fragment angular momentum

International Nuclear Information System (INIS)

Frenne, D. De

1991-01-01

Most of the energy released in fission is converted into translational kinetic energy of the fragments. The remaining excitation energy will be distributed among neutrons and gammas. An important parameter characterizing the scission configuration is the primary angular momentum of the nascent fragments. Neutron emission is not expected to decrease the spin of the fragments by more than one unit of angular momentum and is as such of less importance in the determination of the initial fragment spins. Gamma emission is a suitable tool in studying initial fragment spins because the emission time, number, energy, and multipolarity of the gammas strongly depend on the value of the primary angular momentum. The main conclusions of experiments on gamma emission were that the initial angular momentum of the fragments is large compared to the ground state spin and oriented perpendicular to the fission axis. Most of the recent information concerning initial fragment spin distributions comes from the measurement of isomeric ratios for isomeric pairs produced in fission. Although in nearly every mass chain isomers are known, only a small number are suitable for initial fission fragment spin studies. Yield and half-life considerations strongly limit the number of candidates. This has the advantage that the behavior of a specific isomeric pair can be investigated for a number of fissioning systems at different excitation energies of the fragments and fissioning nuclei. Because most of the recent information on primary angular momenta comes from measurements of isomeric ratios, the global deexcitation process of the fragments and the calculation of the initial fragment spin distribution from measured isomeric ratios are discussed here. The most important results on primary angular momentum determinations are reviewed and some theoretical approaches are given. 45 refs., 7 figs., 2 tabs

Fusion-Fission Transmutation Scheme-Efficient destruction of nuclear waste

International Nuclear Information System (INIS)

Kotschenreuther, M.; Valanju, P.M.; Mahajan, S.M.; Schneider, E.A.

2009-01-01

A fusion-assisted transmutation system for the destruction of transuranic nuclear waste is developed by combining a subcritical fusion-fission hybrid assembly uniquely equipped to burn the worst thermal nonfissile transuranic isotopes with a new fuel cycle that uses cheaper light water reactors for most of the transmutation. The center piece of this fuel cycle, the high power density compact fusion neutron source (100 MW, outer radius <3 m), is made possible by a new divertor with a heat-handling capacity five times that of the standard alternative. The number of hybrids needed to destroy a given amount of waste is an order of magnitude below the corresponding number of critical fast-spectrum reactors (FRs) as the latter cannot fully exploit the new fuel cycle. Also, the time needed for 99% transuranic waste destruction reduces from centuries (with FR) to decades

Experimental study of fission process by fragment-neutron correlation measurement

Energy Technology Data Exchange (ETDEWEB)

Nishio, Katsuhisa; Yamamoto, Hideki; Kanno, Ikuo; Kimura, Itsuro; Nakagome, Yoshihiro [Kyoto Univ. (Japan). Faculty of Engineering

1997-07-01

Fragment-neutron correlation measurement of {sup 235}U(n{sub th}, f) was carried out. The obtained results showed more statistical accuracy than that of reported thermal neutron reaction. Experimental results and it`s analysis made clear the following facts. The minimum values of <{eta}> (m*) are shown at about 90 and 145 {mu} and <{eta}> (m*) showed the symmetrical form with an axis of symmetrical fission. This tendency is same as the distribution of {sup 252}Cf(s.f). -dV/dTKE(m*) indicates the saw-teethed distribution as same as <{nu}>(m*). The distribution seems depend on stiffness of fission fragment affected by the shell effect. The level density parameter a(m*) of fission fragment obtained from {sup 235}U(n{sub th}, f) expresses the saw-teethed distribution as same as that of {sup 252}Cf(s.f). This distribution can be explained by the empirical equation under consideration of the fission fragment depending on the shell effect and the collective motion. (S.Y.)

Utilization of fission reactors for fusion engineering testing

International Nuclear Information System (INIS)

Deis, G.A.; Miller, L.G.

1985-01-01

Fission reactors can be used to conduct some of the fusion nuclear engineering tests identified in the FINESSE study. To further define the advantages and disadvantages of fission testing, the technical and programmatic constraints on this type of testing are discussed here. This paper presents and discusses eight key issues affecting fission utilization. Quantitative comparisons with projected fusion operation are made to determine the technical assets and limitations of fission testing. Capabilities of existing fission reactors are summarized and compared with technical needs. Conclusions are then presented on the areas where fission testing can be most useful

Fission Research at IRMM

Directory of Open Access Journals (Sweden)

Al-Adili A.

2010-03-01

Full Text Available Fission Research at JRC-IRMM has a longstanding tradition. The present paper is discussing recent investigations of fission fragment properties of 238 U(n,f, 234 U(n,f, prompt neutron emission in fission of 252 Cf(SF as well as the prompt fission neutron spectrum of 235 U(n,f and is presenting the most important results.

Detection of fission fragments by secondary emission; Detection des fragments de fission par emission secondaire

Energy Technology Data Exchange (ETDEWEB)

Audias, A [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1965-07-01

This fission fragment detecting apparatus is based on the principle that fragments traversing a thin foil will cause emission of secondary electrons. These electrons are then accelerated (10 kV) and directly detected by means of a plastic scintillator and associated photomultiplier. Some of the advantages of such a detector are, its rapidity, its discriminating power between alpha particles and fission fragments, its small energy loss in detecting the fragments and the relatively great amount of fissionable material which it can contain. This paper is subdivided as follows: a) theoretical considerations b) constructional details of apparatus and some experimental details and c) a study of the secondary emission effect itself. (author) [French] Le detecteur de fragments de fission que nous avons realise est base sur le principe de l'emission secondaire produite par les fragments de fission traversant une feuille mince: les electrons secondaires emis sont acceleres a des tensions telles (de l'ordre de 10 kV), qu'ils soient directement detectables par un scintillateur plastique associe a un photomultiplicateur. L'interet d'un tel detecteur reside: dans sa rapidite, sa tres bonne discrimination alpha, fission, la possibilite de detecter les fragments de fission avec une perte d'energie pouvant rester relativement faible, et la possibilite d'introduire des quantites de matiere fissile plus importantes que dans les autres types de detecteurs. Ce travail comporte: -) un apercu bibliographique de la theorie du phenomene, -) realisation et mise au point du detecteur avec etude experimentale de quelques parametres intervenant dans l'emission secondaire, -) etude de l'emission secondaire (sur la face d'emergence des fragments de fission) en fonction de l'energie du fragment et en fonction de l'epaisseur de matiere traversee avant emission secondaire, et -) une etude comparative de l'emission secondaire sur la face d'incidence et sur la face d'emergence des fragments de

Exploratory study of fission product yield determination from photofission of 239Pu at 11 MeV with monoenergetic photons

Science.gov (United States)

Bhike, Megha; Tornow, W.; Krishichayan, Tonchev, A. P.

2017-02-01

Measurements of fission product yields play an important role for the understanding of fundamental aspects of the fission process. Recently, neutron-induced fission product-yield data of 239Pu at energies below 4 MeV revealed an unexpected energy dependence of certain fission fragments. In order to investigate whether this observation is prerogative to neutron-induced fission, a program has been initiated to measure fission product yields in photoinduced fission. Here we report on the first ever photofission product yield measurement with monoenergetic photons produced by Compton back-scattering of FEL photons. The experiment was performed at the High-Intensity Gamma-ray Source at Triangle Universities Nuclear Laboratory on 239Pu at Eγ=11 MeV. In this exploratory study the yield of eight fission products ranging from 91Sr to 143Ce has been obtained.

Shell effects in fission and quasi-fission of heavy and superheavy nuclei

Energy Technology Data Exchange (ETDEWEB)

Itkis, M.G. E-mail: itkis@flnr.jinr.ru; Aeystoe, J.; Beghini, S.; Bogachev, A.A.; Corradi, L.; Dorvaux, O.; Gadea, A.; Giardina, G.; Hanappe, F.; Itkis, I.M.; Jandel, M.; Kliman, J.; Khlebnikov, S.V.; Kniajeva, G.N.; Kondratiev, N.A.; Kozulin, E.M.; Krupa, L.; Latina, A.; Materna, T.; Montagnoli, G.; Oganessian, Yu.Ts.; Pokrovsky, I.V.; Prokhorova, E.V.; Rowley, N.; Rubchenya, V.A.; Rusanov, A.Ya.; Sagaidak, R.N.; Scarlassara, F.; Stefanini, A.M.; Stuttge, L.; Szilner, S.; Trotta, M.; Trzaska, W.H.; Vakhtin, D.N.; Vinodkumar, A.M.; Voskressenski, V.M.; Zagrebaev, V.I

2004-04-05

Results of the experiments aimed at the study of fission and quasi-fission processes in the reactions {sup 12}C+{sup 204}Pb, {sup 48}Ca+{sup 144,154}Sm, {sup 168}Er, {sup 208}Pb, {sup 244}Pu, {sup 248}Cm; {sup 58}Fe+{sup 208}Pb, {sup 244}Pu, {sup 248}Cm, and {sup 64}Ni+{sup 186}W, {sup 242}Pu are presented in the work. The choice of the above-mentioned reactions was inspired by recent experiments on the production of the isotopes {sup 283}112, {sup 289}114 and {sup 283}116 at Dubna [1],[2] using the same reactions. The {sup 58}Fe and {sup 64}Ni projectiles were chosen since the corresponding projectile-target combinations lead to the synthesis of even heavier elements. The experiments were carried out at the U-400 accelerator of the Flerov Laboratory of Nuclear Reactions (JINR, Russia), the XTU Tandem accelerator of the National Laboratory of Legnaro (LNL, Italy) and the Accelerator of the Laboratory of University of Jyvaskyla (JYFL, Finland) using the time-of-flight spectrometer of fission fragments CORSET[3] and the neutron multi-detector DEMON[4],[5]. The role of shell effects and the influence of the entrance channel on the mechanism of the compound nucleus fusion-fission and the competitive process of quasi-fission are discussed.

Fusion-Fission like studies from medium heavy to light compound systems

International Nuclear Information System (INIS)

Heusch, B.

1991-01-01

It has been shown that for systems as light as A CN = 47 up to systems just above the Businaro Gallone point in the mass region of 100 to 110 the probability for a system to deexcite by the fission channel, is not negligible. As predicted, the asymmetrical separation becomes dominant when the A CN mass is decreasing but the symmetrical mode remains measurable. The ambiguities in the measured outgoing fragment distributions arise from the competition with IMF emissions as well as dynamical fission processes which depend strongly on the studied system. Fully relaxed DIC has also be used to interpret the results. I tried to show that precise checks on the behavior of two neighbouring systems as well as search for entrance channel effect and/or energy dependence bring evidence enough that the deexcitation of the compound nucleus can account for the symmetric and asymmetric fission channels as well as IMF emissions. This is strongly supported by different recent calculations all done in this frame. These all conclusions indicate also that the RLDM fails in the data interpretation. The strength of the fission channel depends strongly on the possibilities a system has to deexcite. For very light systems especially the number of open channels available determines directly the flux repartition between direct or compound processes and therefore very large differences in the general behaviour of two neighbouring systems can be observed. 15 figs

Nuclear fission as a macroscopic quantum tunneling

International Nuclear Information System (INIS)

Takigawa, N.

1995-01-01

We discuss nuclear fission from the point of view of a macroscopic quantum tunneling, one of whose major interests is to study the effects of environments on the tunneling rate of a macroscopic variable. We show that a vibrational excitation of the fissioning nucleus significantly enhances the fission rate. We show this effect by two different methods. The one is to treat the vibrational excitation as an environmental degree of freedom, the other treats the fission as a two dimensional quantum tunneling. (author)

Investigation of short-living fission products from the spontaneous fission of Cf-252

International Nuclear Information System (INIS)

Klonk, H.

1976-01-01

In this paper, a method of separating and measuring fission products of Cf-252 is presented. The measurement was achieved by means of γ-spectrometry and thus provides a quantitative analysis with a good separation of the fission products with respect to both atomic number Z and mass number A. The separation of the fission products from the fission source was achieved by means of solid traps. An automatic changing apparatus made it possible to keep irradiation and measuring times short, so even very short-lived fission products could be registered. The quantitative evaluation of primary fission products was made possible by correction according to Bateman equations. With that, the yields of single nuclides and the dispersion of charge can be determined. (orig./WL) [de

Theoretical Description of the Fission Process

International Nuclear Information System (INIS)

Witold Nazarewicz

2003-01-01

The main goals of the project can be summarized as follows: Development of effective energy functionals that are appropriate for the description of heavy nuclei. Our goal is to improve the existing energy density (Skyrme) functionals to develop a force that will be used in calculations of fission dynamics. Systematic self-consistent calculations of binding energies and fission barriers of actinide and trans-actinide nuclei using modern density functionals. This will be followed by calculations of spontaneous fission lifetimes and mass and charge divisions using dynamic adiabatic approaches based on the WKB approximation. Investigate novel microscopic (non-adiabatic) methods to study the fission process

Theoretical Description of the Fission Process

Energy Technology Data Exchange (ETDEWEB)

Witold Nazarewicz

2003-07-01

The main goals of the project can be summarized as follows: Development of effective energy functionals that are appropriate for the description of heavy nuclei. Our goal is to improve the existing energy density (Skyrme) functionals to develop a force that will be used in calculations of fission dynamics. Systematic self-consistent calculations of binding energies and fission barriers of actinide and trans-actinide nuclei using modern density functionals. This will be followed by calculations of spontaneous fission lifetimes and mass and charge divisions using dynamic adiabatic approaches based on the WKB approximation. Investigate novel microscopic (non-adiabatic) methods to study the fission process.

Characterization of a facility for the measurement of fission fragment transport effects: experimental determination of the fission rates for fissile and fissionable isotopes

International Nuclear Information System (INIS)

Benetti, P.; Raselli, G.L.; Tigliole, A. Borio di; Cagnazzo, M.; Cesana, A.; Mongelli, S.; Terrani, M.

2002-01-01

The transfer facility of the LENA laboratory allows the direct neutron irradiation of fissionable material in the D channel of the TRIGA reactor. A test measurement carried out with a ionization chamber and a 239 Pu sample shows the possibility to use this tool for the study of the transport effects of the fission fragment emerging from thin layers of fissile materials. (author)

The nuclear fission process

International Nuclear Information System (INIS)

Wagemans, C.

1991-01-01

Fifty years after its discovery, the nuclear fission phenomenon is of recurring interest. When its fundamental physics aspects are considered, fission is viewed in a very positive way, which is reflected in the great interest generated by the meetings and large conferences organized for the 50th anniversary of its discovery. From a purely scientific and practical point of view, a new book devoted to the (low energy) nuclear fission phenomenon was highly desirable considering the tremendous amount of new results obtained since the publication of the book Nuclear Fission by Vandenbosch and Huizenga in 1973 (Academic Press). These new results could be obtained thanks to the growth of technology, which enabled the construction of powerful new neutron sources, particle and heavy ion accelerators, and very performant data-acquisition and computer systems. The re-invention of the ionization chamber, the development of large fission fragment spectrometers and sophisticated multiparameter devices, and the production of exotic isotopes also contributed significantly to an improved understanding of nuclear fission. This book is written at a level to introduce graduate students to the exciting subject of nuclear fission. The very complete list of references following each chapter also makes the book very useful for scientists, especially nuclear physicists. The book has 12 chapters covering the fission barrier and the various processes leading to fission as well as the characteristics of the various fission reaction products. In order to guarantee adequate treatment of the very specialized research fields covered, several distinguished scientists actively involved in some of these fields were invited to contribute their expertise as authors or co-authors of the different chapters

Some aspects of fission and quasifission processes

Indian Academy of Sciences (India)

2015-07-22

Jul 22, 2015 ... In this talk, I will review an incomplete subset of the major milestones in fission research, and briefly discuss some of the topics that I have been involved in during my career. These include studies of vibrational resonances and fission isomers that are caused by the second minimum in the fission barrier in ...

Intermediate energy nuclear fission

International Nuclear Information System (INIS)

Hylten, G.

1982-01-01

Nuclear fission has been investigated with the double-kinetic-energy method using silicon surface barrier detectors. Fragment energy correlation measurements have been made for U, Th and Bi with bremsstrahlung of 600 MeV maximum energy. Distributions of kinetic energy as a function of fragment mass are presented. The results are compared with earlier photofission data and in the case of bismuth, with calculations based on the liquid drop model. The binary fission process in U, Yb, Tb, Ce, La, Sb, Ag and Y induced by 600 MeV protons has been investigated yielding fission cross sections, fragment kinetic energies, angular correlations and mass distributions. Fission-spallation competition calculations are used to deduce values of macroscopic fission barrier heights and nuclear level density parameter values at deformations corresponding to the saddle point shapes. We find macroscopic fission barriers lower than those predicted by macroscopic theories. No indication is found of the Businaro Gallone limit expected to occur somewhere in the mass range A = 100 to A = 140. For Ce and La asymmetric mass distributions similar to those in the actinide region are found. A method is described for the analysis of angular correlations between complementary fission products. The description is mainly concerned with fission induced by medium-energy protons but is applicable also to other projectiles and energies. It is shown that the momentum and excitation energy distributions of cascade residuals leading to fission can be extracted. (Author)

Fission cross section calculations for 209Bi target nucleus based on fission reaction models in high energy regions

Directory of Open Access Journals (Sweden)

Kaplan Abdullah

2015-01-01

Full Text Available Implementation of projects of new generation nuclear power plants requires the solving of material science and technological issues in developing of reactor materials. Melts of heavy metals (Pb, Bi and Pb-Bi due to their nuclear and thermophysical properties, are the candidate coolants for fast reactors and accelerator-driven systems (ADS. In this study, α, γ, p, n and 3He induced fission cross section calculations for 209Bi target nucleus at high-energy regions for (α,f, (γ,f, (p,f, (n,f and (3He,f reactions have been investigated using different fission reaction models. Mamdouh Table, Sierk, Rotating Liquid Drop and Fission Path models of theoretical fission barriers of TALYS 1.6 code have been used for the fission cross section calculations. The calculated results have been compared with the experimental data taken from the EXFOR database. TALYS 1.6 Sierk model calculations exhibit generally good agreement with the experimental measurements for all reactions used in this study.

Fission times of excited nuclei: An experimental overview

International Nuclear Information System (INIS)

Morjean, M.; Morjean, M.; Jacquet, D.

2009-01-01

An overview of selected recent experimental results on fission times is presented. Evidences for over-damped motion up to saddle point during the fission process of highly excited nuclei have been obtained independently through fission probability, pre-scission multiplicity and direct time measurements. In addition, strong clues have been found for a temperature dependency of friction. Experiments probing transient effects through fission probabilities are presented and the counterbalanced effects of friction and level density parameters are discussed. Promising perspectives for super-heavy stability studies, based on fission time measurements, are presented. (authors)

Extraction chromatography of fission products

International Nuclear Information System (INIS)

Bonnevie-Svendsen, M.; Goon, K.

1978-01-01

Various cases of using extraction chromatography during analysis of fission products are reviewed. The use of the extraction chromatography method is considered while analysing reprocessed products of nuclear fuel for quantitative radiochemical analysis and control of fission product and actinoide separation during extraction and their chemical state in production solutions. The method is used to obtain pure fractions of typical burnup monitors (neodymium, molybdenum, cerium, cesium, europium, lanthanides) during determination of nuclear fuel burnup degree. While studying the nature of nuclear reactions the method is used to separate quickly short-life isotopes, to purify β-radiator fractions before measuring their half-life periods, to enrich isotopes forming with low output during fission. Examples of using extraction chromatography are given to separate long half-life or stable fission products from spent solutions, to control environment object contamination

Study of ternary and quaternary spontaneous fission of 252Cf with the NESSI detector

International Nuclear Information System (INIS)

Tishchenko, V.G.; Jahnke, U.; Herbach, C.M.; Hilscher, D.

2002-11-01

Ternary and quaternary spontaneous decay of 252 Cf was studied with the NESSI detector, a combination of two 4π detectors for charged particles, neutrons and γ-rays. The applied method of particle identification by measuring the energies and relative time-of-flights of the decay products is shown to be very effective for the study of rare decay modes. The energy and angular distributions of the decay products, the associated neutron multiplicities, the total energy of the prompt γ-radiation as well as correlations between the various observables were measured for the first time in a single full-scale experiment. The characteristics of ternary fission known from previous investigations are confirmed in the frame of a methodically independent experiment. Preliminary estimates of the quaternary fission yield are presented. An attempt is made to determine the mechanism of quaternary fission. (orig.)

Progress in fission product nuclear data

International Nuclear Information System (INIS)

Lammer, M.

1984-09-01

This is the tenth issue of a report series on Fission Product Data, which informs us about all the activities in this field, which are planned, ongoing, or have recently been completed. The types of activities included are measurements, compilations and evaluations of: fission product yields (neutron induced and spontaneous fission), neutron reaction cross sections of fission products, data related to the radioactive decay of fission products, delayed neutron data of fission products, lumped fission product data (decay heat, absorption, etc.). There is also a section with recent references relative to fission product nuclear data

Studies of short-lived products of spallation fission reactions at TRIUMF

CERN Document Server

Bischoff, G; D'Auria, J M; Dautet, H; Lee, J K P; Pate, B D; Wiesehahn, W

1976-01-01

The gas-jet recoil transport technique has been used to transport products from spallation and fission reactions from a target chamber to a shielded location for nuclear spectroscopic studies. These involve X- beta - gamma coincidence measurements and (shortly) time- of-flight mass spectroscopy. It has been deduced that the proton beam at present intensities has no appreciable effect on the ability of ethylene and other cluster-producing gases to transport radioactivity. Preliminary results will be presented for shortlived fission products from uranium, and for spallation products of iodine and argon. The latter were obtained from the bombardment of gas and aerosol targets mixed with the transporting gas in the target chamber, which appears to be a generally useful technique.

Fission times studies of the Z=124 superheavy nucleus by X-ray fluorescence

International Nuclear Information System (INIS)

Airiau, Maud

2016-01-01

Since the 1960's nuclear structure model have predicted the existence of an island of stability of superheavy elements. It should be located around the next magic numbers expected at N=172 or 184 and between Z=114 and 126 depending on the model. Very high fission barrier of a few MeV are predicted to be generated by microscopic effects for those nuclei for which large fission times distributions extended to very high fission times are induced. Fission time measurements of the superheavy element Z=124 have been made by us using the X-ray fluorescence technique, a method based on the filling of inner-shell electronic vacancies created during the collision leading to the formation of the compound nucleus. The aim of this experiment was to detect in coincidence both fission fragments and characteristic X-rays from the Z=124, created by the reaction 238 U+ 70,76 Ge. The main difficulty was to identify those X-rays due to the fact that gamma-rays from fission fragments were emitted in the same energy range, which affected our photon multiplicities for any fragment selection. This new difficulty brings an important limitation to the study of some particular superheavy elements by the X-ray fluorescence method. K X-rays spectra have been simulated using MCDF (Multi-Configuration-Dirac-Fock) and then compared to the experimental ones in order to get a maximal K X-ray multiplicity compatible with our data. The extracted results were about 6-7% for 76 Ge and from 12 to 14% for 70 Ge. Those values remain compatible with the experimental signature of long lifetime component observed for the same system but using a blocking technique in single crystals. (author) [fr

What can we learn about heavy ion fusion by studying fission angular distributions

International Nuclear Information System (INIS)

Back, B.B.

1984-01-01

Determinations of complete fusion reactions leading to fissionable systems are associated with problems of separating fragments from quasi-fission reactions from those arising from fission of the completely fused system. Inferring complete fusion cross sections from the minute cross sections for the evaporation residue channel is hampered by the insufficient knowledge of the branching ratio for neutron emission and fission in the decay sequence of the completely fused system. From a quantitative analysis of the fragment angular distributions it is, however, possible under certain assumptions to deduce the relative contribution of complete fusion and quasi-fission. It is found that the complete fusion process is hindered for heavy projectiles. The excess radial energy over the interaction barrier needed to induce fusion with heavy projectiles is determined in several cases and systematic trends are presented

Thermochromatographic investigations of fission product transport and chemistry

International Nuclear Information System (INIS)

Growcock, F.B.; Aronson, S.; Friedlander, M.; Skalyo, J. Jr.; Hosseini, A.; Taylor, R.D.

1978-01-01

A thermochromatographic technique has been developed to investigate the chemical states of fission products from irradiated fuel as well as in fission product simulation studies. Some recent work on iodine transport and on release of fission products from irradiated fuel kernels will be discussed

Angular momenta of fission fragments in the {alpha}-accompanied fission of {sup 252}Cf

Energy Technology Data Exchange (ETDEWEB)

Jandel, M.; Kliman, J.; Krupa, L.; Morhac, M. [Slovak Academy of Sciences, Department of Nuclear Physics, Bratislava (Slovakia); Joint Institute for Nuclear Research, Flerov Laboratory for Nuclear Reactions, Dubna (Russian Federation); Hamilton, J.H.; Kormicki, J.; Ramayya, A.V.; Hwang, J.K.; Luo, Y.X.; Fong, D.; Gore, P. [Vanderbilt University, Department of Physics, Nashville, TN (United States); Ter-Akopian, G.M.; Oganessian, Yu.Ts.; Rodin, A.M.; Fomichev, A.S.; Popeko, G.S. [Joint Institute for Nuclear Research, Flerov Laboratory for Nuclear Reactions, Dubna (Russian Federation); Daniel, A.V. [Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Rasmussen, J.O.; Macchiavelli, A.O.; Stoyer, M.A. [Lawrence Livermore National Laboratory, Livermore, CA (United States); Donangelo, R.; Cole, J.D.

2005-06-01

For the first time, average angular momenta of the ternary fission fragments {sup 100,102}Zr, {sup 106}Mo, {sup 144,146}Ba and {sup 138,140,142}Xe from the {alpha}-accompanied fission of {sup 252}Cf were obtained from relative intensities of prompt {gamma}-ray transitions with the use of the statistical model calculation. Average values of the angular momenta were compared with the corresponding values for the same fission fragments from the binary fission of {sup 252}Cf. Results indicate the presence of a decreasing trend in the average values of angular momenta induced in ternary fission fragments compared to the same binary fission fragments. On the average, the total angular momentum extracted for ternary fission fragments is {proportional_to}1.4{Dirac_h} lower than in binary fission. Consequently, results indicate that the mechanism of the ternary {alpha}-particles emission may directly effect an induction of angular momenta of fission fragments, and possible scenarios of such mechanisms are discussed. Further, the dependence of the angular momenta of {sup 106}Mo and {sup 140}Xe on the number of emitted neutrons from correlated pairs of primary fragments was obtained also showing a decreasing dependence of average angular momenta with increasing number of emitted neutrons. Consequences are briefly discussed. (orig.)

A Preliminary Study on Time Projection Chamber Simulation for Fission Cross Section Measurements with Geant4

International Nuclear Information System (INIS)

Kim, Jong Woon; Lee, Youngouk; Kim, Jae Cheon

2014-01-01

We present the details of the TPC simulation with Geant4 and show the results. TPC can provide more information than a fission chamber in that it is possible to distinguish different particle types. Simulations are conducted for uranium and plutonium targets with 20MeV neutrons. The simulation results are compared with the reference and show reasonable results. This is the first phase of study for realizing a TPC in the NFS at RAON, and we have more work to do, such as applying an electric field, signal processing in the simulation, and manufacturing of a TPC. The standard in fission cross section measurement is a fission chamber. It is basically just two parallel plates separated by a few centimeters of gas. A power supply connected to the plates sets up a moderate electric field. The target is deposited onto one of the plates. When fission occurs, the fragments ionize the gas, and the electric field causes the produced electrons to drift to the opposite plate, which records the total energy deposited in the chamber. A Time Projection Chamber (TPC) is a gas ionization detector similar to a fission chamber. However, it can measure the charged particle trajectories in the active volume in three dimensions by adding several readouts on the pad plane (fission chamber has only one readout one a pad plane). The specific ionization for each particle track enables the TPC to distinguish different particle types. A TPC will be used for fission cross section measurements in the Neutron Science Facility (NSF) at RAON. As a preliminary study, we present details of TPC simulation with Geant4 and discuss the results

Fission fragment yields and total kinetic energy release in neutron-induced fission of235,238U,and239Pu

Science.gov (United States)

Tovesson, F.; Duke, D.; Geppert-Kleinrath, V.; Manning, B.; Mayorov, D.; Mosby, S.; Schmitt, K.

2018-03-01

Different aspects of the nuclear fission process have been studied at Los Alamos Neutron Science Center (LANSCE) using various instruments and experimental techniques. Properties of the fragments emitted in fission have been investigated using Frisch-grid ionization chambers, a Time Projection Chamber (TPC), and the SPIDER instrument which employs the 2v-2E method. These instruments and experimental techniques have been used to determine fission product mass yields, the energy dependent total kinetic energy (TKE) release, and anisotropy in neutron-induced fission of U-235, U-238 and Pu-239.

Specific fission J-window and angular momentum dependence of the fission barrier

Energy Technology Data Exchange (ETDEWEB)

Baba, Hiroshi; Saito, Tadashi; Takahashi, Naruto; Yokoyama, Akihiko [Osaka Univ., Suita (Japan); Shinohara, Atsushi

1997-04-01

A method to determine a unique J-window in the fission process was devised and the fissioning nuclide associated with thus extracted J-window was identified for each of the heavy-ion reaction systems. Obtained fission barriers at the resulting J-window were compared with the calculated values by the rotating finite range model (RFRM). The deduced barriers for individual nuclides were compared with the RFRM barriers to reproduce more or less the angular momentum dependence the RFRM prediction. The deduced systematic behavior of the fission barrier indicates no even-odd and shell corrections are necessary. The nuclear dissipation effect based on Kramer`s model revealed substantial reduction of the statistically deduced barrier heights and brought a fairly large scattering from the RFRM J-dependence. However, introduction of the temperature-dependent friction coefficient ({gamma} = 2 for T {>=} 1.0 MeV and 0.5 for T < 1.0 MeV) was found to bring about satisfactory agreement with both RFRM fission barriers and the pre-fission neutron multiplicity systematics. (author). 81 refs.

Fission gas release of MOX with heterogeneous structure

International Nuclear Information System (INIS)

Nakae, N.; Akiyama, H.; Kamimura, K; Delville, R.; Jutier, F.; Verwerft, M.; Miura, H.; Baba, T.

2015-01-01

It is very useful for fuel integrity evaluation to accumulate knowledge base on fuel behavior of uranium and plutonium mixed oxide (MOX) fuel used in light water reactors (LWRs). Fission gas release is one of fuel behaviors which have an impact on fuel integrity evaluation. Fission gas release behavior of MOX fuels having heterogeneous structure is focused in this study. MOX fuel rods with a heterogeneous fuel microstructure were irradiated in Halden reactor (IFA-702) and the BR-3/BR-2 CALLISTO Loop (CHIPS program). The 85 Kr gamma spectrometry measurements were carried out in specific cycles in order to examine the concerned LHR (Linear Heat Rate) for fission gas release in the CHIPS program. The concerned LHR is defined in this paper to be the LHR at which a certain additional fission gas release thermally occurs. Post-irradiation examination was performed to understand the fission gas release behavior in connection with the pellet microstructure. The followings conclusions can be made from this study. First, the concerned LHR for fission gas release is estimated to be in the range of 20-23 kW/m with burnup over 37 GWd/tM. It is moreover guessed that the concerned LHR for fission gas release tends to decrease with increasing burnup. Secondly It is observed that FGR (fission gas release rate) is positively correlated with LHR when the LHR exceeds the concerned value. Thirdly, when burnup dependence of fission gas release is discussed, effective burnup should be taken into account. The effective burnup is defined as the burnup at which the LHR should be exceed the concerned value at the last time during all the irradiation period. And fourthly, it appears that FGR inside Pu spots is higher than outside and that retained (not released) fission gases mainly exist in the fission gas bubbles. Since fission gases in bubbles are considered to be easily released during fuel temperature increase, this information is very important to estimate fission gas release behavior

A cost/benefit analysis of commercial fusion-fission hybrid reactor development

International Nuclear Information System (INIS)

Kostoff, R.N.

1983-01-01

A simple algorithm was developed that allows rapid computation of the ratio R, of present worth of benefits to present worth of hybrid RandD program costs as a function of potential hybrid unit electricity cost savings, discount rate, electricity demand growth rate, total hybrid RandD program cost, and time to complete a demonstration reactor. In the sensitivity study, these variables were assigned nominal values (unit electricity cost savings of 4 mills/k W-hr, discount rate of 4%/year, growth rate of 2.25%/year, total RandD program cost of $20 billion, and time to complete a demonstration reactor of 30 years), and the variable of interest was varied about its nominal value. Results show that R increases with decreasing discount rate and increasing unit electricity savings and ranges from 4 to 94 as discount rateranges from 5 to 3%/year and unit electricity savings range from 2 to 6 mills/k W-hr. R increases with increasing growth rate and ranges from 3 to 187 as growth rate ranges from 1 to 3.5%/year and unit electricity cost savings range from 2 to 6 mills/k W-hr. R attains a maximum value when plotted against time to complete a demonstration reactor. The location of this maximum value occurs at shorter completion times as discount rate increases, and this optimal completion time ranges from 20 years for a discount rate of 4%/year to 45 years for a discount rate of 3%/year

Liquid metal coolants for fusion-fission hybrid system: A neutronic analysis

Energy Technology Data Exchange (ETDEWEB)

Marques, Renato V.A.; Velasquez, Carlos E.; Pereira, Claubia; Veloso, Maria Auxiliadora F.; Costa, Antonella L., E-mail: claubia@nuclear.ufmg.br [Universidade de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Departamento de Engenharia Nuclear; Barros, Graiciany P. [Comissão Nacional de Energia Nuclear (CNEN), Rio de Janeiro, RJ (Brazil)

2017-07-01

Based on a work already published by the UFMG Nuclear Engineering Department, it was suggested to use different coolant materials in a fusion-fission system after a fuel burnup simulation, including that one used in reference work. The goal is to compare the neutron parameters, such as the effect multiplication factor and actinide amounts in transmutation layer, for each used coolant and find the best(s) coolant material(s) to be applied in the considered system. Results indicate that the lead and lead-bismuth coolant are the most suitable choices to be applied to cool the system. (author)

Reactor systems modeling for ICF hybrids

International Nuclear Information System (INIS)

Berwald, D.H.; Meier, W.R.

1980-10-01

The computational models of ICF reactor subsystems developed by LLNL and TRW are described and a computer program was incorporated for use in the EPRI-sponsored Feasibility Assessment of Fusion-Fission Hybrids. Representative parametric variations have been examined. Many of the ICF subsystem models are very preliminary and more quantitative models need to be developed and included in the code

Neutron-induced fission cross sections

International Nuclear Information System (INIS)

Weigmann, H.

1991-01-01

In the history of fission research, neutron-induced fission has always played the most important role. The practical importance of neutron-induced fission rests upon the fact that additional neutrons are produced in the fission process, and thus a chain reaction becomes possible. The practical applications of neutron-induced fission will not be discussed in this chapter, but only the physical properties of one of its characteristics, namely (n,f) cross sections. The most important early summaries on the subject are the monograph edited by Michaudon which also deals with the practical applications, the earlier review article on fission by Michaudon, and the review by Bjornholm and Lynn, in which neutron-induced fission receives major attention. This chapter will attempt to go an intermediate way between the very detailed theoretical treatment in the latter review and the cited monograph which emphasizes the applied aspects and the techniques of fission cross-section measurements. The more recent investigations in the field will be included. Section II will survey the properties of cross sections for neutron-induced fission and also address some special aspects of the experimental methods applied in their measurement. Section Ill will deal with the formal theory of neutron-induced nuclear reactions for the resolved resonance region and the region of statistical nuclear reactions. In Section IV, the fission width, or fission transmission coefficient, will be discussed in detail. Section V will deal with the broader structures due to incompletely damped vibrational resonances, and in particular will address the special case of thorium and neighboring isotopes. Finally, Section VI will briefly discuss parity violation effects in neutron-induced fission. 74 refs., 14 figs., 3 tabs

On the mechanism of fission neutron emission

International Nuclear Information System (INIS)

Maerten, H.; Richter, D.; Seeliger, D.

1986-01-01

This review represents the present knowledge of the mechanism of prompt fission neutron emission. Starting with a brief fission process characterization related with neutron emission, possible emission mechanisms are discussed. It is emphasized that the experimental study of special mechanisms, i.e. scission neutron emission processes, requires a sufficiently correct description of emission probabilities on the base of the main mechanism, i.e. the evaporation from fully accelerated fragments. Adequate statistical-model approaches have to account for the complexity of nuclear fission reflected by an intricate fragment distribution. The present picture of scission neutron emission is not clarified neither experimentally nor theoretically. Deduced data are contradictory and depend on the used analysis procedures often involving rough discriptions of evaporated-neutron distributions. The contribution of two secondary mechanisms of fission neutron emission, i.e. the neutron evaporation during fragment acceleration and neutron emission due to the decay of 5 He after ternary fission, is estimated. We summarize the recent progress of the theoretical description of fission neutron spectra in the framework of statistical models considering the standard spectrum of 252 Cf(sf) neutrons especially. The main experimental basis for the study of fission neutron emission is the accurate measurement of emission probabilities as a function of emission energy and angle (at least) as well as fragment parameters (mass number ratio and kinetic energy). The present status is evaluated. (author)

Economics analysis of fuel cycle cost of fusion–fission hybrid reactors based on different fuel cycle strategies

Energy Technology Data Exchange (ETDEWEB)

Zu, Tiejun, E-mail: tiejun@mail.xjtu.edu.cn; Wu, Hongchun; Zheng, Youqi; Cao, Liangzhi

2015-01-15

Highlights: • Economics analysis of fuel cycle cost of FFHRs is carried out. • The mass flows of different fuel cycle strategies are established based on the equilibrium fuel cycle model. • The levelized fuel cycle costs of different fuel cycle strategies are calculated, and compared with current once-through fuel cycle. - Abstract: The economics analysis of fuel cycle cost of fusion–fission hybrid reactors has been performed to compare four fuel cycle strategies: light water cooled blanket burning natural uranium (Strategy A) or spent nuclear fuel (Strategy B), sodium cooled blanket burning transuranics (Strategy C) or minor actinides (Strategy D). The levelized fuel cycle costs (LFCC) which does not include the capital cost, operation and maintenance cost have been calculated based on the equilibrium mass flows. The current once-through (OT) cycle strategy has also been analyzed to serve as the reference fuel cycle for comparisons. It is found that Strategy A and Strategy B have lower LFCCs than OT cycle; although the LFCC of Strategy C is higher than that of OT cycle when the uranium price is at its nominal value, it would become comparable to that of OT cycle when the uranium price reaches its historical peak value level; Strategy D shows the highest LFCC, because it needs to reprocess huge mass of spent nuclear fuel; LFCC is sensitive to the discharge burnup of the nuclear fuel.

Study of advanced fission power reactor development for the United States. Volume I

International Nuclear Information System (INIS)

1976-01-01

This volume summarizes the results and conclusions of an assessment of five advanced fission power reactor concepts in the context of potential nuclear power economies developed over the time period 1975 to 2020. The study was based on the premise that the LMFBR program has been determined to be the highest priority fission reactor program and it will proceed essentially as planned. Accepting this fact, the overall objective of the study was to provide evaluations of advanced fission reactor systems for input to evaluating the levels of research and development funding for fission power. Evaluation of the reactor systems included the following categories: (1) power plant performance, (2) fuel resource utilization; (3) fuel-cycle requirements; (4) economics; (5) environmental impact; (6) risk to the public; and (7) R and D requirements to achieve commercial status. The specific major objectives of the study were twofold: (1) to parametrically assess the impact of various reactor types for various levels of power demand through the year 2020 on fissile fuel utilization, economics, and the environment, based on varying but reasonable assumptions on the rates of installation; and (2) to qualitatively assess the practicality of the advanced reactor concepts, and their research and development. The reactor concepts examined were limited to the following: advanced high-temperature, gas-cooled reactor (HTGR) systems including the thorium/U-233 fuel cycle, gas turbine, and binary cycle (BIHTGR); gas-cooled fast breeder reactor (GCFR); molten salt breeder reactor (MSBR); light water breeder reactor (LWBR); and CANDU heavy water reactor

Measurements of actinide-fission product yields in Caliban and Prospero metallic core reactor fission neutron fields

Energy Technology Data Exchange (ETDEWEB)

Casoli, P.; Authier, N. [CEA, Centre de Valduc, 21120 Is-sur-Tille (France); Laurec, J.; Bauge, E.; Granier, T. [CEA, Centre DIF, 91297 Arpajon (France)

2011-07-01

In the 1970's and early 1980's, an experimental program was performed on the facilities of the CEA Valduc Research Center to measure several actinide-fission product yields. Experiments were, in particular, completed on the Caliban and Prospero metallic core reactors to study fission-neutron-induced reactions on {sup 233}U, {sup 235}U, and {sup 239}Pu. Thick actinide samples were irradiated and the number of nuclei of each fission product was determined by gamma spectrometry. Fission chambers were irradiated simultaneously to measure the numbers of fissions in thin deposits of the same actinides. The masses of the thick samples and the thin deposits were determined by mass spectrometry and alpha spectrometry. The results of these experiments will be fully presented in this paper for the first time. A description of the Caliban and Prospero reactors, their characteristics and performances, and explanations about the experimental approach will also be given in the article. A recent work has been completed to analyze and reinterpret these measurements and particularly to evaluate the associated uncertainties. In this context, calculations have also been carried out with the Monte Carlo transport code Tripoli-4, using the published benchmarked Caliban description and a three-dimensional model of Prospero, to determine the average neutron energy causing fission. Simulation results will be discussed in this paper. Finally, new fission yield measurements will be proposed on Caliban and Prospero reactors to strengthen the results of the first experiments. (authors)

A spin exchange model for singlet fission

Science.gov (United States)

Yago, Tomoaki; Wakasa, Masanobu

2018-03-01

Singlet fission has been analyzed with the Dexter model in which electron exchange occurs between chromophores, conserving the spin for each electron. In the present study, we propose a spin exchange model for singlet fission. In the spin exchange model, spins are exchanged by the exchange interaction between two electrons. Our analysis with simple spin functions demonstrates that singlet fission is possible by spin exchange. A necessary condition for spin exchange is a variation in exchange interactions. We also adapt the spin exchange model to triplet fusion and triplet energy transfer, which often occur after singlet fission in organic solids.

$\\bar{p}$-Induced Fission Studies with Plastic Track Detectors Using 4$\\pi$-Geometry

CERN Multimedia

2002-01-01

% EMU20 \\\\ \\\\ The annihilation of a stopped antiproton on the surface of a target nucleus produces on the average five pions with a mean energy of 230~MeV. The high excitation of the nuclei with low angular momentum transfer can also be achieved by direct pion-nucleus interactions. The fission probabilities of highly excited nuclei can be explained on the basis of high energy limit of statistical theory. Previously the binary fission and higher multiplicity break-up of various nuclei caused by the absorption of pions has been studied by our group. The mechanism of nuclear excitation may still be the same when an antiproton annihilates in a nucleus and produces pions. It would be interesting to see whether the $\\bar{p}$ annihilation produces high enough excitation energies for nuclear phase-transition to take place. If so, then the fragmentation would overwhelm binary and ternary fission process. \\\\ \\\\The use of a highly sensitive plastic detector, CR-39, was made by our group in a number of studies involving ...

The Growth of Sea cucumber Stichopus herrmanni After Transverse Induced Fission in Two and Three Fission Plane

Directory of Open Access Journals (Sweden)

Retno Hartati

2016-06-01

Full Text Available Transverse induced fission proven could be done in Teripang Tril, Stichopus herrmanni. This present works aimed to analyze wound recovery, regeneration period and growth of Teripang Trill  after asexual reproduction by fission using two and three fission plane. Observations were made every day until the sea cucumber body separated into two or more (depending on treatment and reared for 16 weeks.  The results showed that there are differences in wound recovery, regeneration period and growth of S. herrmanni depend on their different fission plane. The wound recovery and regeneration period (days of anterior, middle and posterior individu S. herrmanni resulted from two and three fission plane were varied but the two fission plane the anterior individu recover for longer period than posterior part and  the wound recover process in both end for thee fission plane was same. Average growth of anterior and posterior fragment were longer for two fission plane than three fission plane.  The middle fragment (M1 and M2 both fission plane was able to grow but very low.  It showed that three fission plane gave very slow growth in every fragment of the body. Keywords: growth, post-fission, fission plane, Stichopus herrmanni

Effect of fission dynamics on the spectra and multiplicities of prompt fission neutrons

International Nuclear Information System (INIS)

Nix, J.R.; Madland, D.G.; Sierk, A.J.

1985-01-01

With the goal of examining their effect on the spectra and multiplicities of the prompt neutrons emitted in fission, we discuss recent advances in a unified macroscopic-microscopic description of large-amplitude collective nuclear dynamics. The conversion of collective energy into single-particle excitation energy is calculated for a new surface-plus-window dissipation mechanism. By solving the Hamilton equations of motion for initial conditions appropriate to fission, we obtain the average fission-fragment translational kinetic energy and excitation energy. The spectra and multiplicities of the emitted neutrons, which depend critically upon the average excitation energy, are then calculated on the basis of standard nuclear evaporation theory, taking into account the average motion of the fission fragments, the distribution of fission-fragment residual nuclear temperature, the energy dependence of the cross section for the inverse process of compound-nucleus formation, and the possibility of multiple-chance fission. Some illustrative comparisons of our calculations with experimental data are shown

Equilibrium fission model calculations

International Nuclear Information System (INIS)

Beckerman, M.; Blann, M.

1976-01-01

In order to aid in understanding the systematics of heavy ion fission and fission-like reactions in terms of the target-projectile system, bombarding energy and angular momentum, fission widths are calculated using an angular momentum dependent extension of the Bohr-Wheeler theory and particle emission widths using angular momentum coupling

Comparative studies of actinide and sub-actinide fission cross section calculation from MCNP6 and TALYS

International Nuclear Information System (INIS)

Perkasa, Y. S.; Waris, A.; Kurniadi, R.; Su'ud, Z.

2014-01-01

Comparative studies of actinide and sub-actinide fission cross section calculation from MCNP6 and TALYS have been conducted. In this work, fission cross section resulted from MCNP6 prediction will be compared with result from TALYS calculation. MCNP6 with its event generator CEM03.03 and LAQGSM03.03 have been validated and verified for several intermediate and heavy nuclides fission reaction data and also has a good agreement with experimental data for fission reaction that induced by photons, pions, and nucleons at energy from several ten of MeV to about 1 TeV. The calculation that induced within TALYS will be focused mainly to several hundred MeV for actinide and sub-actinide nuclides and will be compared with MCNP6 code and several experimental data from other evaluator

Fusion-fission type collisions

International Nuclear Information System (INIS)

Oeschler, H.

1980-01-01

Three examples of fusion-fission type collisions on medium-mass nuclei are investigated whether the fragment properties are consistent with fission from equilibrated compound nuclei. Only in a very narrow band of angular momenta the data fulfill the necessary criteria for this process. Continuous evolutions of this mechnism into fusion fission and into a deep-inelastic process and particle emission prior to fusion have been observed. Based on the widths of the fragment-mass distributions of a great variety of data, a further criterion for the compound-nucleus-fission process is tentatively proposed. (orig.)

Fission neutron multiplicity calculations

International Nuclear Information System (INIS)

Maerten, H.; Ruben, A.; Seeliger, D.

1991-01-01

A model for calculating neutron multiplicities in nuclear fission is presented. It is based on the solution of the energy partition problem as function of mass asymmetry within a phenomenological approach including temperature-dependent microscopic energies. Nuclear structure effects on fragment de-excitation, which influence neutron multiplicities, are discussed. Temperature effects on microscopic energy play an important role in induced fission reactions. Calculated results are presented for various fission reactions induced by neutrons. Data cover the incident energy range 0-20 MeV, i.e. multiple chance fission is considered. (author). 28 refs, 13 figs

Mirror hybrid reactor studies

International Nuclear Information System (INIS)

Bender, D.J.

1978-01-01

The hybrid reactor studies are reviewed. The optimization of the point design and work on a reference design are described. The status of the nuclear analysis of fast spectrum blankets, systems studies for fissile fuel producing hybrid reactor, and the mechanical design of the machine are reviewed

Modelling isothermal fission gas release

International Nuclear Information System (INIS)

Uffelen, P. van

2002-01-01

The present paper presents a new fission gas release model consisting of two coupled modules. The first module treats the behaviour of the fission gas atoms in spherical grains with a distribution of grain sizes. This module considers single atom diffusion, trapping and fission induced re-solution of gas atoms associated with intragranular bubbles, and re-solution from the grain boundary into a few layers adjacent to the grain face. The second module considers the transport of the fission gas atoms along the grain boundaries. Four mechanisms are incorporated: diffusion controlled precipitation of gas atoms into bubbles, grain boundary bubble sweeping, re-solution of gas atoms into the adjacent grains and gas flow through open porosity when grain boundary bubbles are interconnected. The interconnection of the intergranular bubbles is affected both by the fraction of the grain face occupied by the cavities and by the balance between the bubble internal pressure and the hydrostatic pressure surrounding the bubbles. The model is under validation. In a first step, some numerical routines have been tested by means of analytic solutions. In a second step, the fission gas release model has been coupled with the FTEMP2 code of the Halden Reactor Project for the temperature distribution in the pellets. A parametric study of some steady-state irradiations and one power ramp have been simulated successfully. In particular, the Halden threshold for fission gas release and two simplified FUMEX cases have been computed and are summarised. (author)

Fission - track age of the Marjalahti Pallasite

International Nuclear Information System (INIS)

Bondar, Yu.V.; Perelygin, V.P.

2006-01-01

contribution from 244 Pu doubles every 82 Myr providing a very sensitive measure of the age of a studied sample. The results of the determination of the fission-track age of the Marjalahti pallasite (stony-iron meteorite) are presented. Thorough examination of fossil tracks in the phosphate (whitlockite) crystals coupled with U content determination in whitlockites allowed us to estimate the contributions of all possible track sources to the total track density and to calculate a value of the model fission-track age. It was found out that whitlockite crystals of the Marjalahti pallasite contain fossil tracks due to galactic cosmic rays (VH, VVH nuclei); induced fission of U and Th by cosmic rays; spontaneous fission of 238 U; spontaneous fission of extinct short-lived 244 Pu nuclei presented in significant quantities in the early solar system. The initial ratio ( 244 Pu/ 238 U) 0 at the time of the pallasite parent body formation (taken as 4.6x10 9 yr) was estimated as 0.015. A great track density attributed to the extinct 244 Pu testified to the high value of the fission-track age. The model fission-track ages of (4.37± 0.02)x10 9 yr for the Marjalahti pallasite was calculated. The comparison of the represented data with petrographic analyses allowed us to interpret a value of the fission-track age as the time of the last intensive shock/thermal event in the cosmic history of the pallasite. (author)

Development of DEMO-FNS tokamak for fusion and hybrid technologies

Science.gov (United States)

Kuteev, B. V.; Azizov, E. A.; Alexeev, P. N.; Ignatiev, V. V.; Subbotin, S. A.; Tsibulskiy, V. F.

2015-07-01

The history of fusion-fission hybrid systems based on a tokamak device as an extremely efficient DT-fusion neutron source has passed through several periods of ample research activity in the world since the very beginning of fusion research in the 1950s. Recently, a new roadmap of the hybrid program has been proposed with the goal to build a pilot hybrid plant (PHP) in Russia by 2030. Development of the DEMO-FNS tokamak for fusion and hybrid technologies, which is planned to be built by 2023, is the key milestone on the path to the PHP. This facility is in the phase of conceptual design aimed at providing feasibility studies for a full set of steady state tokamak technologies at a fusion energy gain factor Q ˜ 1, fusion power of ˜40 MW and opportunities for testing a wide range of hybrid technologies with the emphasis on continuous nuclide processing in molten salts. This paper describes the project motivations, its current status and the key issues of the design.

Some aspects of the nuclear fission process; Quelques aspects du processus de fission nucleaire

Energy Technology Data Exchange (ETDEWEB)

Netter, F [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1961-07-01

In the following report one can find first a short general view on the present situation of our knowledge concerning the nuclear fission process, namely on the nucleus going through the saddle-point. Then there are some aspects connected with the excitation energy of the fissioning nucleus. The measurements made at Saclay on the fast neutron fission cross-section of U{sup 233}, U{sup 235}, Pu{sup 239}, U{sup 238} are described at the beginning of this work. It appears that for U{sup 233} there is some characteristic shape modulation of the cross-section curve, in relation with the collective excited state of the deformed nucleus at the saddle-point. Good evidence of this is also given by the study of the relative fission rate with emission of long-range particles; it appears also that this ternary fission rate does not change substantially for neutron between thermal energy and 2 MeV, but that is very lower for the compound nucleus U{sup 239} than for even-even compound nuclei. At the end there are some experiments on the strong 4,5 MeV gamma-ray originated by slow neutron absorption in U{sup 235}. Time-of-flight device is used to establish that this 4,5 MeV gamma-ray seems mostly connected with radiative capture. (author) [French] Le present travail debute par un apercu de l'etat actuel de nos connaissances sur le processus de fission nucleaire, notamment sur le passage par le point-seuil. Puis sont evoques des aspects lies au niveau d'energie d'excitation auquel est porte le noyau qui subit la fission. Les mesures de sections efficaces de fission induite dans {sup 233}U, {sup 235}U, {sup 239}Pu et {sup 238}U par des neutrons rapides effectuees a Saclay sont decrites en premier lieu; elles font apparaitre pour {sup 233}U une ondulation caracteristique du role des etats collectifs d'excitation du noyau deforme au point-seuil. Des experiences sur la fission avec emission de particules de long parcours confirment cet aspect tout en demontrant que la frequence

Fission track geochronology of Eastern Ghats

Energy Technology Data Exchange (ETDEWEB)

Virk, H S; Koul, S L; Singh, S [Punjabi Univ., Patiala (India). Dept. of Physics

1978-12-01

Fission track geochronology of Eastern Ghats has been established by using fission track technique in dating micaceous and accessory minerals occurring in the region. Annealing studies confirm that radiation damage fossil tracks can be erased in minerals under intense metamorphic episodes thus resetting the geological clock. The fission track ages of the minerals range between 450 +- 5 m.y. to 622 +- 148 m.y. It is concluded that f.t. ages of the minerals date the last metamorphic event of the Eastern Ghats, known as the Indian Ocean Cycle.

Elastocapillary Instability in Mitochondrial Fission

Science.gov (United States)

Gonzalez-Rodriguez, David; Sart, Sébastien; Babataheri, Avin; Tareste, David; Barakat, Abdul I.; Clanet, Christophe; Husson, Julien

2015-08-01

Mitochondria are dynamic cell organelles that constantly undergo fission and fusion events. These dynamical processes, which tightly regulate mitochondrial morphology, are essential for cell physiology. Here we propose an elastocapillary mechanical instability as a mechanism for mitochondrial fission. We experimentally induce mitochondrial fission by rupturing the cell's plasma membrane. We present a stability analysis that successfully explains the observed fission wavelength and the role of mitochondrial morphology in the occurrence of fission events. Our results show that the laws of fluid mechanics can describe mitochondrial morphology and dynamics.

Study of fission mechanism with the reactions 230Th, 231Pa, 235U, 237Np(n,f) and 252Cf(fs)

International Nuclear Information System (INIS)

Benfoughal, T.

1983-01-01

In this work, the different stages of the nuclear fission process have been investigated. The analysis of fission cross-section and fission fragment angular distribution measurements are made using the hypothesis of asymmetrically deformed states. From the correlation between fissioning nucleus excitation energy and fragment total kinetic energy measurement for several fissioning systems, it is shown that the nuclear viscosity is relatively strong during the saddle-point to scission-point transition. The study of the spontaneous fission of 252 Cf shows that the fragment mass and kinetic energy distributions are mainly determinated by the nucleon shell effects and pairing correlations [fr

Fusion-fission of superheavy nuclei at low excitation energies

International Nuclear Information System (INIS)

Itkis, M.G.; Oganesyan, Yu.Ts.; Kozulin, E.M.

2000-01-01

The process of fusion-fission of superheavy nuclei with Z = 102 -122 formed in the reactions with 22 Ne, 26 Mg, 48 Ca, 58 Fe and 86 Kr ions at energies near and below the Coulomb barrier has been studied. The experiments were carried out at the U-400 accelerator of the Flerov Laboratory of Nuclear Reactions (JINR) using a time-of-flight spectrometer of fission fragments CORSET and a neutron multi-detector DEMON. As a result of the experiments, mass and energy distributions of fission fragments, fission and quasi-fission cross sections, multiplicities of neutrons and gamma-rays and their dependence on the mechanism of formation and decay of compound superheavy systems have been studied

SYMMETRICAL AND ASYMMETRIC TERNARY FISSION OF HOT NUCLEI

NARCIS (Netherlands)

SIWEKWILCZYNSKA, K; WILCZYNSKI, J; LEEGTE, HKW; SIEMSSEN, RH; WILSCHUT, HW; GROTOWSKI, K; PANASIEWICZ, A; SOSIN, Z; WIELOCH, A

Emission of a particles accompanying fusion-fission processes in the Ar-40 + Th-232 reaction at E(Ar-40) = 365 MeV was studied in a wide range of in-fission-plane and out-of-plane angles. The exact determination of the emission angles of both fission fragments combined with the time-of-flight

Determination of the fission products yields, lanthanide and yttrium, in the fission of 238U with neutrons of fission spectra

International Nuclear Information System (INIS)

Nicoli, I.G.

1981-06-01

A radiochemical investigation is performed to measure the cumulative fission product yields of several lantanides and yttrium nuclides in the 238 U by fission neutron spectra. Natural and depleted uranium are irradiated under the same experimental conditions in order to find a way to subtract the contribution of the 235 U fission. 235 U percentage in the natural uranium was 3.5 times higher than in the depleted uranium. Uranium oxides samples are irradiated inside the core of the Argonaut Reactor, at the Instituto de Engenharia Nuclear, and the lantanides and yttrium are chemically separated. The fission products gamma activities were detected, counted and analysed in a system constituted by a high resolution Ge(Li) detector, 4096 multichannel analyser and a PDP-11 computer. Cumulative yields for fission products with half-lives between 1 to 33 hours are measured: 93 Y, 141 La, 142 La, 143 Ce and 149 Nd. The chain total yields are calculated. The cumulative fission yields measured for 93 Y, 141 La, 142 La, 143 Ce and 149 Nd are 4,49%, 4,54%, 4,95%, 4,16% and 1,37% respectively and they are in good agreement with the values found in the literature. (Author) [pt

The electronuclear cycle: from fission to new reactor systems

International Nuclear Information System (INIS)

Belier, G.; Cugnon, J.; Lapoux, V.; Liatard, E.; Porquet, Marie-Genevieve; Rudolf, G.

2006-09-01

The Joliot Curie School trains each year, and since 1981, PhD students, post-Doctorates and researchers on scientific breakthroughs performed in a topic related to nuclear physics, in a broad range. These proceedings brings together the 11 lectures given at the 2006 session of Joliot Curie School on the topic of the electronuclear cycle: - Fission: from phenomenology to theory (Berger, J.F.); - Physics of nuclear reactors (Baeten, P.); - Data modeling and evaluation (Bauge, E.; Hilaire, S.); - Measurement of cross sections of interest for minor actinides incineration (Jurado, B.); - Spallation data and modelling for hybrid reactors (Boudard, A.); - Nuclear wastes: overview (Billard, I.); - Long living nuclear wastes transmutation processes and feasibility (Varaine, F.); - Hybrid reactors: recent advances for a demonstrator (Billebaud, A.); - Systems of the future and strategy (David, S.); - Non-nuclear energies (Nifenecker, H.); - Fundamental physics with ultracold neutrons (Protasov, K). The last section is a compilation of abstracts of presentations given by Young searchers' (Young searchers' seminars)

Barium 139 as Fission Indicator

Energy Technology Data Exchange (ETDEWEB)

Broda, E.

1943-07-01

This report is based on a measurement performed at the Cavendish Laboratory (Cambridge) by E. Broda in December 1943 where a technique has been worked out for measuring the fission density in a uranium containing medium in relative units by determining the amount of a suitable fission product formed. Generally a given fission product will be formed in natural uranium by slow neutron fission of U235 or by fast neutron fission of either U235 or U238. It is intended to translate the relative units into absolute units by comparison of the Ba yield with the indication of UF6 fission chamber in the same medium. This has to be done separately for fast and slow neutron fission as the yields may be different. Another application of the technique developed is the measurement of thermal neutron density in an uraniferous medium without using a detector subject to variations of sensitivity according to the properties of the medium. (nowak)

Contribution of the fission-track method to the study of the Alpine chains: relationship between tectonics and metamorphism

International Nuclear Information System (INIS)

Carpena, J.

1984-01-01

The fission-track method allows geologists to date rocks and to get information on the thermal history of rocks. Fission tracks in minerals are essentially due to the spontaneous fission of uranium 238. The knowledge of the density of tracks and the concentration of uranium 238 lead to the determination of the age of the rock. The irradiation in a neutron flux of a sample of the rock allows the determination of the concentration of uranium. The age obtained is in fact an apparent age that does not take into account possible geological annealing process that may erase fission tracks, some corrections are then necessary. The first part of this work details the fission-track method, its scope and limitations. It is shown that fission-track method on apatites can reveal the thermal evolution of the rock and that the same method used on zircons can give information of the setting of volcanic rocks. The second part is dedicated to the contribution of the fission-track method to a both dating and thermal evolution study of a french-italian part of the Alpine chain

Fusion-fission in Ar-heavy nuclei collisions

International Nuclear Information System (INIS)

Zaric, Alexandre

1984-01-01

Fusion-fission products have been studied for three reactions: Ar + Au, Ar + Bi and Ar + U (5.25-7.5 MeV/u). By measuring symmetric fragmentation components (fission-like events), cross sections for fusion were deduced and compared with the prediction of static and dynamic models. With increasing projectile energy, the width of the mass distributions strongly increases for the two lighter systems. By contrast, for Ar + U it remains essentially constant at a very large value. These results clearly demonstrate that the large increase of the width of the mass distribution cannot be attributed simply to large values of the angular momentum. However, they can be explained by the occurrence of a different dissipative process, fast fission, which can be expected if there is no barrier to fission. For the reaction Ar + Au, the total kinetic-energy distributions were also studied in detail. In this case fast fission occurs only at high incident energy. The average total kinetic energy (TKE) was found to be constant with increasing energy. (author) [fr

Modelisation of the fission cross section

International Nuclear Information System (INIS)

Morariu, Claudia

2013-03-01

The neutron cross sections of four nuclear systems (n+ 235 U, n+ 233 U, n+ 241 Am and n+ 237 Np) are studied in the present document. The target nuclei of the first case, like 235 U and 239 Pu, have a large fission cross section after the absorption of thermal neutrons. These nuclei are called 'fissile' nuclei. The other type of nuclei, like 237 Np and 241 Am, fission mostly with fast neutrons, which exceed the fission threshold energy. These types of nuclei are called 'fertile'. The compound nuclei of the fertile nuclei have a binding energy higher than the fission barrier, while for the fissile nuclei the binding energy is lower than the fission barrier. In this work, the neutron induced cross sections for both types of nuclei are evaluated in the fast energy range. The total, reaction and shape-elastic cross sections are calculated by the coupled channel method of the optical model code ECIS, while the compound nucleus mechanism are treated by the statistical models implemented in the codes STATIS, GNASH and TALYS. The STATIS code includes a refined model of the fission process. Results from the theoretical calculations are compared with data retrieved from the experimental data base EXFOR. (author) [fr

Determination of the fission barrier height in fission of heavy radioactive beams induced by the (d,p)-transfer

CERN Multimedia

A theoretical framework is described, allowing to determine the fission barrier height using the observed cross sections of fission induced by the (d,p)-transfer with accuracy, which is not achievable in another type of low-energy fission of neutron-deficient nuclei, the $\\beta$-delayed fission. The primary goal is to directly determine the fission barrier height of proton-rich fissile nuclei, preferably using the radio-active beams of isotopes of odd elements, and thus confirm or exclude the low values of fission barrier heights, typically extracted using statistical calculations in the compound nucleus reactions at higher excitation energies. Calculated fission cross sections in transfer reactions of the radioactive beams show sufficient sensitivity to fission barrier height. In the probable case that fission rates will be high enough, mass asymmetry of fission fragments can be determined. Results will be relevant for nuclear astrophysics and for production of super-heavy nuclei. Transfer induced fission of...

Inverse kinematics technique for the study of fission-fragment isotopic yields at GANIL energies

International Nuclear Information System (INIS)

Delaune, O.

2012-01-01

The characteristics of the fission-products distributions result of dynamical and quantum properties of the deformation process of the fissioning nucleus. These distributions have also an interest for the conception of new nuclear power plants or for the transmutation of the nuclear wastes. Up to now, our understanding of the nuclear fission remains restricted because of experimental limitations. In particular, yields of the heavy fission products are difficult to get with precision. In this work, an innovative experimental technique is presented. It is based on the use of inverse kinematics coupled to the use of a spectrometer, in which a 238 U beam at 6 or 24 A MeV impinges on light targets. Several actinides, from 238 U to 250 Cf, are produced by transfer or fusion reactions, with an excitation energy ranges from ten to few hundreds MeV depending on the reaction and the beam energy. The fission fragments of these actinides are detected by the VAMOS spectrometer or the LISE separator. The isotopic yields of fission products are completely measured for different fissioning systems. The neutron excess of the fragments is used to characterise the isotopic distributions. Its evolution with excitation energy gives important insights on the mechanisms of the compound-nucleus formation and its deexcitation. Neutron excess is also used to determine the multiplicity of neutrons evaporated by the fragments. The role of the proton and neutron shell effects into the formation of fission fragments is also discussed. (author) [fr

Studies of the Fission Integrals of U-{sup 235} and Pu-{sup 239} with Cadmium and Filters

Energy Technology Data Exchange (ETDEWEB)

Hellstrand, E

1965-04-15

The resonance fissions in U{sup 235} and Pu{sup 239} have been studied using cadmium and boron filters. Fission chambers were used as detectors and the experiments were performed in beam geometry. The neutron energy distribution in the beams transmitted through the different filters was determined with a fast chopper. From the cadmium filter, measurements the fission resonance integrals were determined. The values obtained were 278{+-}9 b for U{sup 235} and 301{+-}10 b for Pu{sup 239}; 0.5 eV < E < 1 MeV. Complementary Pu{sup 239} measurements were made in which the fission events were detected from the fission product activity in irradiated foils. Contrary to what has been reported elsewhere the value of the Pu{sup 239} resonance integral, found in this way, agreed well with that obtained from the fission chamber measurement. The experiments with the boron filters yielded results which, for the thin filter, agreed well with those calculated from the cross section data given in the Karlsruhe compilation. The discrepancy was larger for the thick filter but the values did not disagree outside the common limits of error.

Tip model of cold fission

International Nuclear Information System (INIS)

Goennenwein, F.; Boersig, B.

1991-01-01

Cold fission is defined to be the limiting case of nuclear fission where virtually all of the available energy is converted into the total kinetic energy of the fragments. The fragments have, therefore, to be born in or at least close to their respective ground states. Starting from the viewpoint that cold fission corresponds to most compact scission configurations, energy constraints have been exploited to calculate minimum tip distances between the two nascent fragments in binary fission. Crucial input parameters to this tip model of cold fission are the ground-state deformations of fragment nuclei. It is shown that the minimum tip distances being compatible with energy conservation vary strongly with both the mass and charge fragmentation of the fission prone nucleus. The tip distances refer to nuclei with equivalent sharp surfaces. In keeping with the size of the surface width of leptodermous nuclei, only configurations where the tip distances are smaller than a few fm may be considered as valid scission configurations. From a comparison with experimental data on cold fission this critical tip distance appears to be 3.0 fm for the model parameters chosen. Whenever the model calculation yields tip distances being smaller than the critical value, a necessary condition for attaining cold fission is considered to be fulfilled. It is shown that this criterion allows to understand in fair agreement with experiment which mass fragmentations are susceptible to lead to cold fission and which fragment-charge divisions are the most favored in each isobaric mass chain. Being based merely on energy arguments, the model cannot aim at predicting fragment yields in cold fission. However, the tip model proposed appears well suited to delineate the phase space where cold fission phenomena may come into sight. (orig.)

Fission of heavy hypernuclei

International Nuclear Information System (INIS)

Nifenecker, H.

1993-01-01

The results on delayed and prompt fission of heavy hypernuclei obtained by the LEAR PS177 collaboration are recalled and discussed. It is shown that the hypernuclei life-times can be explained in term of a weak strangeness violating lambda-nucleon interaction with a cross section close to 6.0 10 -15 barns. The lambda attachment function is shown to be sensitive to the scission configuration, just before fission, and to the neck dynamics. This function provides a new way to study the nuclear scission process. (author)

Study of the behaviour of tetracycline as fission products extracting agent

International Nuclear Information System (INIS)

Cunha, I.I.L.

1983-01-01

Both spectrophotometric and potentiometric titration techniques were used to show the formation of complexes between tetracycline and the elements: zirconium, uranium, molybdenum, strontium, barium and ruthenium. It has been verified that tetracycline does not form complexes with cesium, tellurium and iodine. Those techniques have also been used to determine the sites on the tetracycline molecule at which ions may be bound. The behaviour of tetracycline as an extracting agent for those elements, as well as for niobium and technetium has been studied and the influence of the acidity of the aqueous phase upon extraction of the elements mentioned has been considered. Extraction experiments were carried out in the presence of chloride, perchlorate, nitrate and sulfate ions. Studies have been made to determine whether or not the complex extracted into organic phase is really the complex formed between tetracycline and the elements considered as well as to determine the time of shaking necessary so that the equilibrium between the phases is attained. Based on all information obtained from extraction experiments made for uranium and the fission products Zr-95, Nb-95, Ce-141, La-140, Ru-103, Ba-140 and Cs-137, the possibility of using tetracycline for separating those fission products from each other and from uranium has been studies and a scheme for simultaneous separation of those elements has been proposed. The same study has been made for I-131, Tc-99m, Mo-99, Te-132, Np-239 and uranium. The method described is applicable to the separation of some fission products existing in solutions at tracer levels, and not to be used in nuclear fuel reprocessing or any other industrial application. (Author) [pt

Nuclear dynamics in heavy ion induced fusion-fission reactions

International Nuclear Information System (INIS)

Kapoor, S.S.

1992-01-01

Heavy ion induced fission and fission-like reactions evolve through a complex nuclear dynamics encountered in the medium energy nucleus-nucleus collisions. In the recent years, measurements of the fragment-neutron and fragment-charged particle angular correlations in heavy ion induced fusion-fission reactions, have provided new information on the dynamical times of nuclear deformations of the initial dinuclear complex to the fission saddle point and the scission point. From the studies of fragment angular distributions in heavy ion induced fission it has been possible to infer the relaxation times of the dinuclear complex in the K-degree of freedom and our recent measurements on the entrance channel dependence of fragment anisotropies have provided an experimental signature of the presence of fissions before K-equilibration. This paper reviews recent experimental and theoretical status of the above studies with particular regard to the questions relating to dynamical times, nuclear dissipation and the effect of nuclear dissipation on the K-distributions at the fission saddle in completely equilibrated compound nucleus. (author). 19 refs., 9 figs

A threshold for dissipative fission

International Nuclear Information System (INIS)

Thoennessen, M.; Bertsch, G.F.

1993-01-01

The empirical domain of validity of statistical theory is examined as applied to fission data on pre-fission data on pre-fission neutron, charged particle, and γ-ray multiplicities. Systematics are found of the threshold excitation energy for the appearance of nonstatistical fission. From the data on systems with not too high fissility, the relevant phenomenological parameter is the ratio of the threshold temperature T thresh to the (temperature-dependent) fission barrier height E Bar (T). The statistical model reproduces the data for T thresh /E Bar (T) thresh /E Bar (T) independent of mass and fissility of the systems

Studies on short-lived fission products at the Mainz TRIGA reactor

International Nuclear Information System (INIS)

Trautmann, N.

1974-01-01

Neutron-rich nuclei of medium mass number are produced by thermal-neutron-induced fission of heavy elements, e.g., 235 U, 239 Pu, and 249 Cf. Pulse irradiations lead to an enhancement of the ratio of short-lived activities to the accompanying longer-lived components. One approach for investigating the properties of short-lived nuclei consists in a combination of rapid chemical separations with higher-resolution gamma spectroscopy. This is demonstrated by the isolation of neutron-rich isotopes of niobium by sorption on glass and of ruthenium by solvent extraction. Other rapid separation procedures from aqueous solutions are briefly summarized and a few examples for their application in nuclear fission- and delayed neutron studies are given. Some experiments with an on-line mass separator of the ISOLDE-type, using chemical targets, are described. (U.S.)

Reexamination of fission fragment angular distributions and the fission process: Formalism

International Nuclear Information System (INIS)

Bond, P.D.

1985-01-01

The theory of fission fragment angular distributions is examined and the universally used expression is found to be valid only under restrictive assumptions. A more general angular distribution formula is derived and applied to recent data of high spin systems. At the same time it is shown that the strong anisotropies observed from such systems can be understood without changing the essential basis of standard fission theory. The effects of reaction mechanisms other than complete fusion on fission fragment angular distributions are discussed and possible angular distribution signatures of noncompound nucleus formation are mentioned

Process for treating fission waste

International Nuclear Information System (INIS)

Rohrmann, C.A.; Wick, O.J.

1983-01-01

A method is described for the treatment of fission waste. A glass forming agent, a metal oxide, and a reducing agent are mixed with the fission waste and the mixture is heated. After melting, the mixture separates into a glass phase and a metal phase. The glass phase may be used to safely store the fission waste, while the metal phase contains noble metals recovered from the fission waste

Investigation of the heavy nuclei fission with anomalously high values of the fission fragments total kinetic energy

Science.gov (United States)

Khryachkov, Vitaly; Goverdovskii, Andrei; Ketlerov, Vladimir; Mitrofanov, Vecheslav; Sergachev, Alexei

2018-03-01

Binary fission of 232Th and 238U induced by fast neutrons were under intent investigation in the IPPE during recent years. These measurements were performed with a twin ionization chamber with Frisch grids. Signals from the detector were digitized for further processing with a specially developed software. It results in information of kinetic energies, masses, directions and Bragg curves of registered fission fragments. Total statistics of a few million fission events were collected during each experiment. It was discovered that for several combinations of fission fragment masses their total kinetic energy was very close to total free energy of the fissioning system. The probability of such fission events for the fast neutron induced fission was found to be much higher than for spontaneous fission of 252Cf and thermal neutron induced fission of 235U. For experiments with 238U target the energy of incident neutrons were 5 MeV and 6.5 MeV. Close analysis of dependence of fission fragment distribution on compound nucleus excitation energy gave us some explanation of the phenomenon. It could be a process in highly excited compound nucleus which leads the fissioning system from the scission point into the fusion valley with high probability.

A Study on Fission Product Model Comparison between MAAP4 and MAAP5

Energy Technology Data Exchange (ETDEWEB)

Shin, Tae-young; Seo, Mi Ro [KHNP CRI, Daejeon (Korea, Republic of)

2016-10-15

The newly added safety goal required that the sum of the accident frequency that the release of the radioactive nuclide Cs-137 to environment exceeds the 100TBq should be less than 1.0E-6/RY. This requirement is known to be come from the provision for preventing the long term ground contamination due to the release of radioactive material. Validation of this standard was performed by many researchers recently. In the outlook of Cs-137, the mass of Cs-137 correspondent with the 100TBq is calculated as 32g. However, during the severe accident, if the containment has been failed, it is generally expected that the mass of Cs-137 released to the environment is more than 1kg for most accident sequences. The purpose of this study compare fission product model in MAAP4 and MAAP5. So the same accident will be simulated as MAAP4 and MAAP5. And will compare fission product release fraction. This will help to improvements obtained to meet the regulatory requirements of Cs-137. This paper was a comparison of MAAP4's fission product models with those of MAAP5. And this paper simulated the station blackout accident to compare MAAP4 and MAAP5 fission product release fraction. So far Level 2 PSA analysis used MAAP4. And this result failed to meet the regulatory requirements of Cs-137 up to now. Fission product release fraction calculated by MAAP5 is more conservative than that calculated by MAAP4. Therefore, using MAAP5 is more difficult to meet the requirements of Cs-137. Thus, Level 1 PSA analysis must find ways to reduce CDF and Level 2 PSA analysis must find ways to reduce CFF in order to meet regulatory requirements. Not only, it seems to be required a study on the possible safety systems to alleviate the containment failure after the core damage.

Total and fission cross-sections of 239Pu - statistical study of resonance parameters

International Nuclear Information System (INIS)

Derrien, H.; Blons, J.; Eggermann, C.; Michaudon, A.; Paya, D.; Ribon, P.

1967-01-01

The authors measured the total and fission cross-sections of 239 Pu with the linear accelerator at Saclay as a pulsed source of neutrons. The total cross-section was measured in the range from 4 to 700 eV and the best resolution used was 1.5 ns/m; the fission cross-section was measured between 4 eV and 6 keV, the best resolution having been 6 ns/m. The transmission measurements on five samples were made at the temperature of liquid nitrogen, and comparisons made with supplementary experiments at ambient temperature made it possible to determine the Doppler broadening factor (Δ = η√E). The resonances were identified from 4 to 500 eV in the total cross-section; the average level spacing was of the order of 2.4 eV. It would appear that, in this energy range, nearly all the levels were identified. The resonance parameters were determined by analysis of shape in conjunction with a least-squares programme on an IBM-7094 computer. The existence of a large number of broad resonances corresponding to very large fission widths has been shown to exist. Statistical study of the fission widths actually shows the existence of two families of resonances, one corresponding to a mean Γ f of the order of 45 meV and the other to a mean Γ/f of about 750 meV. The authors were therefore able to postulate a classification of resonances in terms of two spin states, the level population ratio in each family being: (2J 1 +1)/(2J 2 +1) = 1/3; J 1 = 0 corresponds to the broad resonances and J 2 = 1 to the narrow ones. The partial widths for radiative capture fluctuate slightly around a mean value of 40 meV. By using a multilevel programme, the authors were able to investigate the extent to which the existence of large fission widths might give rise to fictitious resonances (quasi-resonances) and perturbations and also to make a statistical study of the resonance parameters. (author) [fr

Fifty years with nuclear fission

International Nuclear Information System (INIS)

Behrens, J.W.; Carlson, A.D.

1989-01-01

The news of the discovery of nuclear fission, by Otto Hahn and Fritz Strassmann in Germany, was brought to the United States by Niels Bohr in January 1939. Since its discovery, the United States, and the world for that matter, has never been the same. It therefore seemed appropriate to acknowledge the fifieth anniversary of its discovery by holding a topical meeting entitled, ''Fifty Years with Nuclear Fission,'' in the United States during the year 1989. The objective of the meeting was to bring together pioneers of the nuclear industry and other scientists and engineers to report on reminiscences of the past and on the more recent development in fission science and technology. The conference highlighted the early pioneers of the nuclear industry by dedicated a full day (April 26), consisting of two plenary sessions, at the National Academy of Sciences (NAS) in Washington, DC. More recent developments in fission science and technology in addition to historical reflections were topics for two fully days of sessions (April 27 and 28) at the main site of the NIST in Gaithersburg, Maryland. The wide range of topics covered in this Volume 1 by this topical meeting included plenary invited, and contributed sessions entitled: Preclude to the First Chain Reaction -- 1932 to 1942; Early Fission Research -- Nuclear Structure and Spontaneous Fission; 50 Years of Fission, Science, and Technology; Nuclear Reactors, Secure Energy for the Future; Reactors 1; Fission Science 1; Safeguards and Space Applications; Fission Data; Nuclear Fission -- Its Various Aspects; Theory and Experiments in Support of Theory; Reactors and Safeguards; and General Research, Instrumentation, and By-Product. The individual papers have been cataloged separately

Application of fission track and other new technics in the study of geothermal history for Liaohe Basin

International Nuclear Information System (INIS)

Xia Yuliang; Zhu Jiechen; Zheng Maogong; Zhao Yunlong; Hu Zhenduo; Guo Xiuying; Gao Shangkui

1994-11-01

Mainly based on the study of fission track of the apatites, as well as geochronology, stable isotope composition and inclusion analysis, the principle and method of studying the geothermal history of sedimentary basin have been expounded systematically, and the source of sediment materials, and the geothermal characteristics of five section areas in Liaohe Basin were determined. The results of apatites and zircons U-Pb dating indicate that the materials of Shahejie Group in Liaohe Basin derived from the Shanhaiguan old land, and the record time of fission track of the apatites started at 172 Ma ago. On the basis of the studies of fission track characters of 100 apatite samples, stable isotopes and inclusion analysis, the annealing zone of fission track, oil generation zone and the old geothermal gradient were determined respectively in the western slope, southern part of western depression, Niuju area, Huangjindai area of eastern depression and Shallow sea area. It has provided the important scientific basis of reevaluating oil resources in Liaohe Basin. (2 tabs.)

Nuclear fission induced by heavy ions

International Nuclear Information System (INIS)

Newton, J.O.

1988-09-01

Because the accelerators of the 50's and 60's mostly provided beams of light ions, well suited for studying individual quantum states of low angular momentum or reactions involving the transfer of one or two nucleons, the study of fission, being an example of large-scale collective motion, has until recently been outside of the mainstream of nuclear research. This situation has changed in recent years, due to the new generation of accelerators capable of producing beams of heavy ions with energies high enough to overcome the Coulomb barriers of all stable nuclei. These have made possible the study of new examples of large-scale collective motions, involving major rearrangements of nuclear matter, such as deep-inelastic collisions and heavy-ion fusion. Perhaps the most exciting development in the past few years is the discovery that dissipative effects (nuclear viscosity) play an important role in fission induced by heavy ions, contrary to earlier assumptions that the viscosity involved in fission was very weak and played only a minor role. This review will be mainly concerned with developments in heavy-ion induced fission during the last few years and have an emphasis on the very recent results on dissipative effects. Since heavy-ion bombardment usually results in compound systems with high excitation energies and angular momenta, shell effects might be expected to be small, and the subject of low energy fission, where they are important, will not be addressed. 285 refs., 58 figs

Study on mitigation of in-vessel release of fission products in severe accidents of PWR

International Nuclear Information System (INIS)

Huang, G.F.; Tong, L.L.; Li, J.X.; Cao, X.W.

2010-01-01

Research highlights: → In-vessel release of fission products in severe accidents for 600 MW PWR is analyzed. → Mitigation effect of primary feed-and-bleed on in-vessel release is investigated. → Mitigation effect of secondary feed-and-bleed on in-vessel release is studied. → Mitigation effect of ex-vessel cooling on in-vessel release is evaluated. - Abstract: During the severe accidents in a nuclear power plant, large amounts of fission products release with accident progression, including in-vessel and ex-vessel release. Mitigation of fission products release is demanded for alleviating radiological consequence in severe accidents. Mitigation countermeasures to in-vessel release are studied for Chinese 600 MW pressurized water reactor (PWR), including feed-and-bleed in primary circuit, feed-and-bleed in secondary circuit and ex-vessel cooling. SBO, LOFW, SBLOCA and LBLOCA are selected as typical severe accident sequences. Based on the evaluation of in-vessel release with different startup time of countermeasure, and the coupling relationship between thermohydraulics and in-vessel release of fission products, some results are achieved. Feed-and-bleed in primary circuit is an effective countermeasure to mitigate in-vessel release of fission products, and earlier startup time of countermeasure is more feasible. Feed-and-bleed in secondary circuit is also an effective countermeasure to mitigate in-vessel release for most severe accident sequences that can cease core melt progression, e.g. SBO, LOFW and SBLOCA. Ex-vessel cooling has no mitigation effect on in-vessel release owing to inevitable core melt and relocation.

Muon-induced fission

International Nuclear Information System (INIS)

Polikanov, S.

1980-01-01

A review of recent experimental results on negative-muon-induced fission, both of 238 U and 232 Th, is given. Some conclusions drawn by the author are concerned with muonic atoms of fission fragments and muonic atoms of the shape isomer of 238 U. (author)

Nuclear data for neutron emission in the fission process

International Nuclear Information System (INIS)

Ganesan, S.

1991-11-01

This document contains the proceedings of the IAEA Consultants' Meeting on Nuclear Data for Neutron Emission in the Fission Process, Vienna, 22 - 24 October 1990. Included are the conclusions and recommendations reached at the meeting and the papers presented by the meeting participants. These papers provide a review of the status of experimental and theoretical data on neutron emission in spontaneous and neutron induced fission with reference to the data needs for reactor applications oriented towards actinide burner studies. The specific topics covered are the following: experimental measurements and theoretical predictions and evaluations of fission neutron energy spectra, average prompt fission neutron multiplicity, correlation in neutron emission from complementary fragments, neutron emission during acceleration of fission fragments, statistical properties of neutron rich nuclei by study of emission spectra of neutrons from the excited fission fragments, integral qualification of nu-bar for the major fissile isotopes, nu-bar total of 239 Pu and 235 U, and related problems. Refs figs and tabs

Mirror hybrid reactor blanket and power conversion system conceptual design

International Nuclear Information System (INIS)

Schultz, K.R.; Backus, G.A.; Baxi, C.B.; Dee, J.B.; Estrine, E.A.; Rao, R.; Veca, A.R.

1976-01-01

The conceptual design of the blanket and power conversion system for a gas-cooled mirror hybrid fusion-fission reactor is presented. The designs of the fuel, blanket module and power conversion system are based on existing gas-cooled fission reactor technology that has been developed at General Atomic Company. The uranium silicide fuel is contained in Inconel-clad rods and is cooled by helium gas. The fuel is contained in 16 spherical segment modules which surround the fusion plasma. The hot helium is used to raise steam for a conventional steam cycle turbine generator. The details of the method of support for the massive blanket modules and helium ducts remain to be determined. Nevertheless, the conceptual design appears to be technically feasible with existing gas-cooled technology. A preliminary safety analysis shows that with the development of a satisfactory method of primary coolant circuit containment and support, the hybrid reactor could be licensed under existing Nuclear Regulatory Commission regulations

Space Fission System Test Effectiveness

International Nuclear Information System (INIS)

Houts, Mike; Schmidt, Glen L.; Van Dyke, Melissa; Godfroy, Tom; Martin, James; Bragg-Sitton, Shannon; Dickens, Ricky; Salvail, Pat; Harper, Roger

2004-01-01

Space fission technology has the potential to enable rapid access to any point in the solar system. If fission propulsion systems are to be developed to their full potential, however, near-term customers need to be identified and initial fission systems successfully developed, launched, and utilized. One key to successful utilization is to develop reactor designs that are highly testable. Testable reactor designs have a much higher probability of being successfully converted from paper concepts to working space hardware than do designs which are difficult or impossible to realistically test. ''Test Effectiveness'' is one measure of the ability to realistically test a space reactor system. The objective of this paper is to discuss test effectiveness as applied to the design, development, flight qualification, and acceptance testing of space fission systems. The ability to perform highly effective testing would be particularly important to the success of any near-term mission, such as NASA's Jupiter Icy Moons Orbiter, the first mission under study within NASA's Project Prometheus, the Nuclear Systems Program

Fission product and aerosol behaviour within the containment

International Nuclear Information System (INIS)

Beard, A.M.; Benson, C.G.; Bowsher, B.R.; Dickinson, S.; Nichols, A.L.

1990-04-01

Experimental studies have been undertaken to characterise the behaviour of fission products in the containment of a pressurised water reactor during a severe accident. The following aspects of fission product transport have been studied: (a) aerosol nucleation, (b) vapour transport processes, (c) chemical forms of high-temperature vapours, (d) interaction of fission product vapours with aerosols generated from within the reactor core, (e) resuspension processes, (f) chemistry in the containment. Chemical effects have been shown to be important in defining and quantifying fission product source terms in a wide range of accident sequences. Both the chemical forms of the fission product vapours and their interactions with reactor materials aerosols could have a major effect on the magnitude and physicochemical forms of the radioactive emission from a severe reactor accident. Only the main conclusions are presented in this summary document; detailed technical aspects of the work are described in separate reports listed in the annex

Fission track dating method: I. Study of neutron flux uniformity in some irradiation positions of IEA-R1 reactor

International Nuclear Information System (INIS)

Osorio, A.M.; Hadler, J.C.; Iunes, P.J.; Paulo, S.R. de

1993-06-01

In order to use the fission track dating method the flux gradient was verified within the sample holder, in some irradiation positions of the IEA-R1 reactor at IPEN/CNEN, Sao Paulo. The fission track dating method considers only the thermal neutron fission tracks, to subtract the other contributions sample irradiations with a cadmium cover was performed. The neutron flux cadmium influence was studied. (author)

Separation of fission products by the use of recoil; Separation des produits de fission par utilisation du recul

Energy Technology Data Exchange (ETDEWEB)

Henry, R; Beydon, J; Bardy, A [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

1960-07-01

We have studied fission recoil in U{sub 3}O{sub 8} organic solvent mixtures. The organic phase chosen was first naphtalene then terphenyl. Graphite and activated carbon were also tried out as recoil media. We first verified that the fission fragments are ejected from the uranium oxide particles under our experimental conditions. The retention phenomenon observed is due to an adsorption occurring either during irradiation or during the chemical treatment. Using naphthalene or terphenyl, the individual separation of the fission products has made it possible to show the influence of the chemical nature of the recoil medium on the retention of each fission product. We put forward a hypothesis concerning this phenomenon: experiments carried out using 'scavengers', together with kinetic studies make it possible to explain the retention phenomenon and to choose the most favorable conditions for reducing this retention to a low value. The thermal recombination kinetics demonstrate the influence of the fission ion charge on the final value of the retention for a given temperature. The origins of this thermal recombination are discussed. (author) [French] On a etudie le recul de fission dans les melanges U{sub 3}0{sub 8}, phase organique. La phase organique choisie a ete le naphtalene puis le terphenyle. Le graphite et le charbon actif ont egalement ete essayes comme milieux de recul. On a d'abord determine que les fragments de fission sortent des particules d'oxyde d'uranium avec un rendement de 100 pour cent dans nos conditions experimentales. Le phenomene de retention observe est du a une adsorption ayant lieu pendant l'irradiation ou pendant le traitement chimique. Dans le naphtalene et le terphenyle, la separation individuelle des produits de fission a permis de mettre en evidence l'influence de la nature chimique du milieu de recul sur la retention de chaque produit de fission. On avance une hypothese sur ce phenomene: des experiences effectuees avec des 'scavengers

Energy production using fission fragment rockets

International Nuclear Information System (INIS)

Chapline, G.; Matsuda, Y.

1991-08-01

Fission fragment rockets are nuclear reactors with a core consisting of thin fibers in a vacuum, and which use magnetic fields to extract the fission fragments from the reactor core. As an alternative to ordinary nuclear reactors, fission fragment rockets would have the following advantages: Approximately twice as efficient if one can directly convert the fission fragment energy into electricity; by reducing the buildup of a fission fragment inventory in the reactor one could avoid a Chernobyl type disaster; and collecting the fission fragments outside the reactor could simplify the waste disposal problem. 6 refs., 4 figs., 2 tabs

Study of the shielding for spontaneous fission sources of Californium-252

International Nuclear Information System (INIS)

Davila R, I.

1991-06-01

A shielding study is made to attenuate, until maximum permissible levels, the neutrons radiation and photons emitted by spontaneous fission coming from a source of Californium-252. The compound package by a database (Library DLC-23) and the ANISNW code is used, in it version for personal computer. (Author)

Radiation damage studies of mineral apatite, using fission tracks and thermoluminescence techniques

International Nuclear Information System (INIS)

Al-Khalifa, I.J.M.

1988-01-01

In a uranium (/thorium)-rich mineral sample which has not suffered a recent geological high-temperature excursion, the fossil fission track density (FFTD) will give a good indication of its natural radiation damage, provided that its U/Th ratio is known. From our studies of FFTD and thermoluminescence (TL) properties of several samples of apatite from different locations, and containing varying degrees of natural-radiation damage, an anti-correlation is observed between FFTD and TL sensitivity. It is also found that an anti-correlation exists between TL sensitivity and the amount of damage produced artificially by bombarding apatite crystals with different fluences of ∼30 MeV α-particles from a cyclotron. These results indicate that the presence of radiation damage in this mineral (viz., fluorapatite) can severely affect its TL sensitivity (i.e. TL output per unit test dose). The effect of crystal composition on the thermoluminescence and fission track annealing properties of mineral apatite is also reported. We have found that fission track annealing sensitivity and TL sensitivity are both significantly lower in samples of chlorapatite than in samples consisting predominantly of fluorapatite. (author)

Modelling animal group fission using social network dynamics.

Directory of Open Access Journals (Sweden)

Cédric Sueur

Full Text Available Group life involves both advantages and disadvantages, meaning that individuals have to compromise between their nutritional needs and their social links. When a compromise is impossible, the group splits in order to reduce conflict of interests and favour positive social interactions between its members. In this study we built a dynamic model of social networks to represent a succession of temporary fissions involving a change in social relations that could potentially lead to irreversible group fission (i.e. no more group fusion. This is the first study that assesses how a social network changes according to group fission-fusion dynamics. We built a model that was based on different parameters: the group size, the influence of nutritional needs compared to social needs, and the changes in the social network after a temporary fission. The results obtained from this theoretical data indicate how the percentage of social relation transfer, the number of individuals and the relative importance of nutritional requirements and social links influence the average number of days before irreversible fission occurs. The greater the nutritional needs and the higher the transfer of social relations during temporary fission, the fewer days will be observed before an irreversible fission. It is crucial to bridge the gap between the individual and the population level if we hope to understand how simple, local interactions may drive ecological systems.

Investigation of delayed fission gas release

International Nuclear Information System (INIS)

Cayet, Nicolas

1996-05-01

The study of the fission gas release process in the high burnup rig IFA-562 has revealed a particular fuel behaviour: a delay in the fission gas release process. It appeared that an important release of gas was measured by the pressure transducers once the power had decreased, whereas, during steady-state operation, the pressure did not increase very much. After examinations, the gap size has been concluded to be the main parameter involving this delay. However the burnup could have been a potential factor, its role is mainly to close the gap by swelling. The observations of low burnup rods have shown the same delayed fission gas release, the gap being small by design and closed essentially by thermal expansion. The study of the kinetics has demonstrated the time-independency of the phenomenon. Thus the proposed mechanism driving this delayed fission gas release would involve three consecutives stages. During steady-state, the gas is released into the interlinkage network of grain boundary bubbles and cracks. Due to the closed gap, the gas is trapped in some void volumes, unable to escape the pellet. During power reduction, the gap and some old/new cracks open, immediately providing a path for the gas to the pressure transducers and explaining this delay in the fission gas release. (author)

Fission dynamics of hot nuclei

Indian Academy of Sciences (India)

2014-04-05

Apr 5, 2014 ... across the fission barrier is very small or in other words, the fission barrier is much ... of this shape evolution, the gross features of the fissioning nucleus can be described ..... [7] Y Abe, C Gregoire and H Delagrange, J. Phys.

Dynamic of fission and quasi-fission revealed by pre-scission neutron evaporation

International Nuclear Information System (INIS)

Hinde, D.J.

1991-06-01

The dependence of pre-scission neutron multiplicities (ν-pre) on the mass-split and total kinetic energy (TKE) in fusion-fission and quasi-fission has been measured for a wide range of projectile-target combinations. the data indicate that the fusion-fission time scale is shorter for asymmetric splits than for symmetric splits, whilst there is no dependence on TKE. For quasi-fission reactions induced using 64 Ni projectiles, ν-pre falls rapidly with increasing TKE, indicating that these neutrons are emitted near to or after scission. A new interpretation of both neutron multiplicities and mean energies (the neutron clock-thermometer) allows the extraction of time scales with much less uncertainty than previously, and also gives information about the deformation from which the neutrons are emitted. 15 refs., 13 figs

Measurements of fission cross-sections and of neutron production rates; Mesures de sections efficaces de fission et du nombre de neutrons prompts emis par fission

Energy Technology Data Exchange (ETDEWEB)

Billaud, P; Clair, C; Gaudin, M; Genin, R; Joly, R; Leroy, J L; Michaudon, A; Ouvry, J; Signarbieux, C; Vendryes, G [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1958-07-01

a) Measurements of neutron induced fission cross-sections in the low energy region. The variation of the fission cross sections of several fissile isotopes has been measured and analysed, for neutron energies below 0,025 eV. The monochromator was a crystal spectrometer used in conjunction with a mechanical velocity selector removing higher order Bragg reflections. The fissile material was laid down on the plates of a fission chamber by painting technic. An ionization chamber, having its plates coated with thin {sup 10}B layers, was used as the neutron flux monitor. b) Measurement of the fission cross section of {sup 235}U. We intend to measure the variation of the neutron induced fission cross section of {sup 235}U over the neutron energy range from 1 keV by the time of flight method. The neutron source is the uranium target of a pulsed 28 MeV electron linear accelerator. The detector is a large fission chamber, with parallel plates, containing about 10 g of {sup 235}U (20 deposits of 25 cm diameter). The relative fission data were corrected for the neutron spectrum measured with a set of BF{sub 3} proportional counters. c) Mean number {nu} of neutrons emitted in neutron induced fission. We measured the value of {nu} for several fissile isotopes in the case of fission induced by 14 MeV neutrons. The 14 MeV neutrons were produced by D (t, n) {alpha} reaction by means of a 300 kV Cockcroft Walton generator. (author)Fren. [French] a) Mesures de sectionficaces de fission a basse energie. Nous avons mesure et analyse la variation de la section efficace de fission de divers isotopes fissiles pour des neutrons d'energie inferieure a 0,025 eV. Le monochromateur est constitue par un spectrometre a cristal auquel est associe un selecteur mecanique destine a eliminer les diffractions de Bragg d'ordre superieur au premier. Le materiau fissile est contenu dans une chambre a fission sous forme de depots realises par peinture; une chambre d'ionisation a depots minces de B{sub 10

Theory of nuclear fission: a review

International Nuclear Information System (INIS)

Mosel, U.

1976-01-01

General properties of nuclear fission are reviewed and related to our present knowledge of fission theory. For this purpose the basic reasons for the shape of the fission barriers are discussed and their consequences compared with experimental results on barrier shapes and structures. Special emphasis is put on the asymmetry of the fission barriers and mass-distributions and its relation to the shells of the nascent fragment shells. Finally the problem of calculating fission cross sections is discussed

Study of fission product γ spectra in the band 2-500 keV

International Nuclear Information System (INIS)

Rousseau, A.

1959-01-01

In the study of the γ spectrum of uranium fission products, particular attention has been given in this note to the part of the spectrum ranging between 0 and 500 keV after a given pile operating programme and the evolution of this spectrum with time after a pile shutdown has been followed. The study be related to the fission products which appear in the pile as a whole or on those produced in a uranium sample assumed to have been placed in the pile. The latter case has been envisaged here. The spectrum determination is based partly on theory and partly on experiment. The pile operating conditions are different in the two cases, which widens the range of validity of the spectra traced here. (author) [fr

Properties of neutron-rich nuclei studied by fission product nuclear chemistry

International Nuclear Information System (INIS)

Meyer, R.A.; Henry, E.A.; Griffin, H.C.; Lien, O.G. III; Lane, S.M.; Stevenson, P.C.; Yaffe, R.P.; Skarnemark, G.

1979-09-01

A review is given of the properties of neutron-rich nuclei studied by fission product nuclear chemistry and includes the techniques used in elemental isolation and current research on the structure of nuclei near 132 Sn, particle emission, and coexisting structure in both neutron-poor and neutron-rich nuclei. 35 references

A new neutron counter for fission research

Energy Technology Data Exchange (ETDEWEB)

Laurent, B., E-mail: benoit.laurent@cea.fr [CEA, DAM, DIF, F-91297 Arpajon (France); Granier, T.; Bélier, G.; Chatillon, A.; Martin, J.-F.; Taieb, J. [CEA, DAM, DIF, F-91297 Arpajon (France); Hambsch, F.-J. [EC-JRC Institute for Reference Materials and Measurements (IRMM), Retieseweg, 2440 Geel (Belgium); Tovesson, F.; Laptev, A.B.; Haight, R.C.; Nelson, R.O.; O' Donnell, J.M. [Los Alamos Neutron Science Center, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

2014-05-01

A new neutron counter for research experiments on nuclear fission has been developed. This instrument is designed for the detection of prompt fission neutrons within relatively high levels of gamma and neutron background. It is composed of a set of {sup 3}He proportional counters arranged within a block of polyethylene which serves as moderator. The detection properties have been studied by means of Monte Carlo simulations and experiments with radioactive sources. These properties are confirmed by an experiment on neutron-induced fission of {sup 238}U at the WNR facility of the Los Alamos Neutron Science Center during which the mean prompt fission neutron multiplicity, or ν{sup ¯} has been measured from 1 to 20 MeV of incident neutron energy.

Brief description of out-of-pile test facilities for study in corrosion and fission product behaviour in flowing sodium

International Nuclear Information System (INIS)

Iizawa, K.; Sekiguchi, N.; Atsumo, H.

1976-01-01

The experimental methods to perform tests for study in corrosion and fission products behaviour in flowing sodium are outlined. Flow diagrams for the activated materials and fission products behaviour test loop are given

Simulation of fission products behavior in severe accidents for advanced passive PWR

International Nuclear Information System (INIS)

Tong, L.L.; Huang, G.F.; Cao, X.W.

2015-01-01

Highlights: • A fission product analysis model based on thermal hydraulic module is developed. • An assessment method for fission product release and transport is constructed. • Fission products behavior during three modes of containment response is investigated. • Source term results for the three modes of containment response are obtained. - Abstract: Fission product behavior for common Pressurized Water Reactor (PWR) has been studied for many years, and some analytical tools have developed. However, studies specifically on the behavior of fission products related to advanced passive PWR is scarce. In the current study, design characteristics of advanced passive PWR influencing fission product behavior are investigated. An integrated fission products analysis model based on a thermal hydraulic module is developed, and the assessment method for fission products release and transport for advanced passive PWR is constructed. Three modes of containment response are simulated, including intact containment, containment bypass and containment overpressure failure. Fission products release from the core and corium, fission products transport and deposition in the Reactor Coolant System (RCS), fission products transport and deposition in the containment considering fission products retention in the in-containment refueling water storage tank (IRWST) and in the secondary side of steam generators (SGs) are simulated. Source term results of intact containment, containment bypass and containment overpressure failure are obtained, which can be utilized to evaluate the radiological consequences

Nuclear isomerism in fission fragments produced by the spontaneous fission of {sup 252}Cf; Isomerisme nucleaire dans les fragments de fission produits dans la fission spontanee du {sup 252}Cf

Energy Technology Data Exchange (ETDEWEB)

Gautherin, C

1997-09-01

This thesis is devoted to the study of the nuclear structure of neutron-rich nuclei, via the search of isomeric nuclear states. Neutron-rich nuclei were produced in the spontaneous fission of {sup 252}Cf. The experimental study of isomeric states in these nuclei was performed with the {gamma}-array EUROGAM II, coupled to an additional and original fission fragment detector composed by photovoltaic cells, SAPhIR. The photovoltaic cells are well adapted to detect low energy heavy ions and have good energy and time resolutions to obtain a good fission fragment detection. This experiment led to the discovery of new isomeric states in {sup 135}Xe, {sup 104}Mo, {sup 146,147,148}Ce and {sup 152,154,156}Nd, with lifetimes between 60 ns and 2 {mu}s. Level schemes of these nuclei have been completed. An interpretation of the isomeric states in the nuclei {sup 154,156}Nd and {sup 156,158}Sm was performed by Hartree-Fock-Bogolyubov calculations using the DIS Gogny force with two quasi-particles excitations. The confrontation with the experimental results led to an interpretation of these isomeric states as K-isomers. (author)

The multi-step prompt particle emission from fission fragments

International Nuclear Information System (INIS)

Zhivopistsev, A.; Oprea, C.; Oprea, I.

2003-01-01

The purpose of this work is the study of non-equilibrium high-energy gamma emission from 252 Cf. In the framework of the formalism of statistical multi-step compound processes in nuclear reactions. A relation was found between the shape of the high-energy part of the gamma spectrum and different mechanisms of excitation of the fission fragments. Agreement with experimental data for different groups of fission fragments was obtained. The analysis of the experimental high-energy part of gamma spectra yields information about the mechanism of excitation of fission fragments. The influence of dissipation of the deformation excess on intrinsic excitation of fission fragments was studied. (authors)

Micro plate fission chamber development

International Nuclear Information System (INIS)

Wang Mei; Wen Zhongwei; Lin Jufang; Jiang Li; Liu Rong; Wang Dalun

2014-01-01

To conduct the measurement of neutron flux and the fission rate distribution at several position in assemblies, the micro plate fission chamber was designed and fabricated. Since the requirement of smaller volume and less structure material was taken into consideration, it is convinient, commercial and practical to use fission chamber to measure neutron flux in specific condition. In this paper, the structure of fission chamber and process of fabrication were introduced and performance test result was presented. The detection efficiency is 91.7%. (authors)

Mechanisms of fission neutron emission

International Nuclear Information System (INIS)

Maerten, H.

1991-01-01

The time evolution in fission is the starting point for discussing not only the main mechanism of fission neutron emission, the evaporation from fully accelerated fragments, but also possible secondary ones connected with dynamical features of nuclear fission. ''Asymptotic'' conditions as relevant for describing the particle release from highly excited, rapidly moving fragments are defined. Corresponding statistical model approaches to fission neutron emission, based on the adequate consideration of the intricate fragment occurrence probability, reproduce most of the experimental data. The remarkable influence of fission modes on neutron observables is analyzed in the framework of a macroscopic-microscopic scission point model consistent with energy conservation. Finally, chances and deficiencies for solving the mechanism puzzle are summarized. (author). 87 refs, 21 figs

Development of a “Fission-proxy” Method for the Measurement of 14-MeV Neutron Fission Yields at CAMS

Energy Technology Data Exchange (ETDEWEB)

Gharibyan, Narek [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2016-10-25

Relative fission yield measurements were made for 50 fission products from 25.6±0.5 MeV alpha-induced fission of Th-232. Quantitative comparison of these experimentally measured fission yields with the evaluated fission yields from 14-MeV neutron-induced fission of U-235 demonstrates the feasibility of the proposed fission-proxy method. This new technique, based on the Bohr-independence hypothesis, permits the measurement of fission yields from an alternate reaction pathway (Th-232 + 25.6 MeV α → U-236* vs. U-235 + 14-MeV n → U-236*) given that the fission process associated with the same compound nucleus is independent of its formation. Other suitable systems that can potentially be investigated in this manner include (but are not limited to) Pu-239 and U-237.

Recent advances in heavy-ion-induced fission

International Nuclear Information System (INIS)

Plasil, F.

1984-01-01

Three topics are discussed. The first deals with results that have been published recently on angular-momentum-dependent fission barriers. They are discussed because of the significance that we attach to them. We feel that, after a decade of study and controversy, we have arrived at a quantitative understanding of the competition between heavy-ion-induced fission and particle emission from compound nuclei at relatively low bombarding energies. The second topic concerns the extension of our heavy-ion-induced fission studies to higher energies. It is clear that in this regime the effects, both of fission following incomplete fusion and of extra-push requirements, need to be considered. Finally, discussed are our recent conclusions concerning the fissionlike decay of products from reactions between two 58 Ni nuclei at an incident energy, E/A, of 15.3 MeV, as well as the impact of our findings on the conclusions drawn from previous, similar measurements. 39 references

Progress in fission product nuclear data

International Nuclear Information System (INIS)

Lammer, M.

1981-06-01

This is the seventh issue of a report series on Fission Product Nuclear Data (FPND) which is published by the Nuclear Data Section (NDS) of the International Atomic Energy Agency (IAEA). The purpose of this series is to inform scientists working on FPND, or using such data, about all activities in this field which are planned, ongoing, or have recently been completed. The present issue contains also a section with some recent references relative to fission product nuclear data, which were not covered by the contributions submitted. The types of activities being included in this report are measurements, compilations and evaluations of: fission product yields (neutron induced and spontaneous fission); neutron reaction cross sections of fission products; data related to the radioactive decay of fission products; delayed neutron data of fission products; and lumped fission product data (decay heat, absorption etc.). The sixth issue of this series has been published in June 1980 as INDC(NDS)-113/G+P. The present issue includes contributions which were received by NDS between 1 August 1980 and 25 May 1981

Hybrid simulation of reactor kinetics in CANDU reactors using a modal approach

International Nuclear Information System (INIS)

Monaghan, B.M.; McDonnell, F.N.; Hinds, H.W.T.; m.

1980-01-01

A hybrid computer model for simulating the behaviour of large CANDU (Canada Deuterium Uranium) reactor cores is presented. The main dynamic variables are expressed in terms of weighted sums of a base set of spatial natural-mode functions with time-varying co-efficients. This technique, known as the modal or synthesis approach, permits good three-dimensional representation of reactor dynamics and is well suited to hybrid simulation. The hybrid model provides improved man-machine interaction and real-time capability. The model was used in two applications. The first studies the transient that follows a loss of primary coolant and reactor shutdown; the second is a simulation of the dynamics of xenon, a fission product which has a high absorption cross-section for neutrons and thus has an important effect on reactor behaviour. Comparison of the results of the hybrid computer simulation with those of an all-digital one is good, within 1% to 2%

The study of prompt neutron spectra of 238U fission induced by fast neutron

International Nuclear Information System (INIS)

Li Anli; Bai Xixiang; Wang Yufeng; Wang Xiaozhong; Men Jiangchen; Huang Shengnian

1990-01-01

The measurements of prompt neutron time-of-flight spectra of U fission induced by 11 MeV neutrons were carried out at HI-13 Tandem Van de Graaff Accelerator Laboratory in 1989. The block diagram of the electronics is shown. A fission neutron TOF spectrum for the sixth section of the fission plates and the left detector at low bias is given. The data accumulation time is 60 h

Nuclear structure via isomer tagging of fission fragments

Science.gov (United States)

Wu, C. Y.; Cline, D.; Simon, M. W.; Stoyer, M. A.

1997-10-01

The high efficiency for detecting high-fold γ rays by large Ge arrays makes it possible to study the detailed spectroscopy of many neutron-rich nuclei produced by fission. Major progress has been made using sealed spontaneous fission sources. Considerable improvement in selectivity is provided, with an open source, both by gating on isomers and by detection of both fission fragments in coincidence with the deexcitation γ rays (see the preceding contribution). The reconstructed kinematics allows a measure of fragment mass and the Doppler shift correction of γ rays. In a recent experiment, fission fragments were detected using half of the CHICO array and an annular PPAC in coincidence with deexcitation γ rays detected by the Rochester array of eight Compton-suppressed Ge detectors. The annular PPAC was located only 1.0" from a 3.7 μCi ^252Cf source for efficient isomer tagging. The correlation was studied between delayed, within a time window between 150 ns and 10 μs after a fission occurring, and prompt γ rays. Several prominent feeding patterns to isomers in the mass region around 100 and 130 are identified by such correlation study. Experimental details and results will be presented.

Signatures of Coulomb fission: a theoretical study

International Nuclear Information System (INIS)

Oberacker, V.; Kruse, H.; Pinkston, W.T.; Greiner, W.

1979-01-01

Evidence for Coulomb fission (CF) is noted first. Then the Hamiltonian is set down and explained, and an expression for the CF probability of CF is obtained. Results are summarized. Figures show the CF probability of 238 U as a function of projectile charge number and the excitation functions for CF of 238 U by 184 W and 136 Xe. 3 figures

Ternary fission of spontaneously fissile uranium isomers excited by neutrons

International Nuclear Information System (INIS)

Makarenko, V.E.; Molchanov, Y.D.; Otroshchenko, G.A.; Yan'kov, G.B.

1989-01-01

Spontaneously fissile isomers (SFI) of uranium were excited in the reactions 236,238 U(n,n') at an average neutron energy 4.5 MeV. A pulsed electrostatic accelerator and time analysis of the fission events were used. Fission fragments were detected by the scintillation method, and long-range particles from fission were detected by an ionization method. The relative probability of fission of nuclei through a spontaneously fissile isomeric state was measured: (1.30±0.01)·10 -4 ( 236 U) and (1.48±0.02)·10 -4 ( 238 U). Half-lives of the isomers were determined: 121±2 nsec (the SFI 236 U) and 267±13 nsec (the SFI 238 U). In study of the ternary fission of spontaneously fissile isotopes of uranium it was established that the probability of the process amounts to one ternary fission per 163±44 binary fissions of the SFI 236 U and one ternary fission per 49±14 binary fissions of the SFI 238 U. The substantial increase of the probability of ternary fission of SFI of uranium in comparison with the case of ternary fission of nuclei which are not in an isomeric state may be related to a special nucleon configuration of the fissile isomers of uranium

Fission and r-process nucleosynthesis in neutron star mergers

International Nuclear Information System (INIS)

Giuliani, Samuel Andrea

2018-01-01

Fission plays a crucial role for the r-process nucleosynthesis in neutron star mergers. Due to the high neutron densities achieved in this astrophysical scenario the sequence of neutron captures and beta decays that constitutes the r process produces superheavy neutron rich nuclei that become unstable against fission. Fission determines thus the heaviest nuclei that can be produced by the r process and the fission yields shape the abundances of lighter nuclei. But despite the key role of fission the sensitivity of the r-process nucleosynthesis to uncertainties in fission predictions has not been explored. Nowadays there are only few set of fission rates suited for r-process calculations and most of them rely on a simplified treatment of the fission process. In this thesis we go beyond these approximations and compute the fission properties of r-process nuclei using the energy density functional approach. Fission is described as a tunneling process where the nucleus ''moves'' in a collective space characterized by coordinates describing the nuclear shape. Thus fission depends on the evolution of the energy with the deformation but also on the inertia due to the motion in the collective space. This is analogous to the quantum mechanical tunneling of a particle inside a potential well. In our study the relevant quantities for the description of the fission process are consistently computed for 3642 nuclei following the Hartree-Fock-Bogolyubov theory with constraining operators. We perform an extensive benchmark against the available experimental data and explore the variations of the fission properties along the superheavy landscape. We find that while collective inertias have a strong impact in the fission probabilities of light nuclei their role becomes less relevant in r -process nuclei. Within the statistical model we compute the neutron induced stellar reaction rates relevant for the r-process nucleosynthesis. These sets of stellar reaction

Progress in fission product nuclear data

International Nuclear Information System (INIS)

Lammer, G.

1976-05-01

The purpose of this series is to inform scientists working on Fission Product Nuclear Data, or using such data, about all activities in this field which are planned, ongoing, or have recently been completed. This report consists of reproductions of essentially unaltered original contributions which the authors have sent to IAEA/NDS. The types of activities being included in this report are measurements, compilations and evaluations of: fission product yields; neutron cross-section data of fission products; data related to β-, γ-decay of fission products; delayed neutron data; and fission product decay-heat

Dating by fission track method: study of neutron dosimetry with natural uranium thin films

International Nuclear Information System (INIS)

Iunes, P.J.

1990-06-01

Fission track dating is described, focalizing the problem of the decay constant for spontaneous fission of 238 U and the use of neutron dosimetry in fission track analysis. Experimental procedures using thin films of natural uranium as neutron dosimeters and its results are presented. The author shows a intercomparison between different thin films and between the dosimetry with thin film and other dosimetries. (M.V.M.). 52 refs, 12 figs, 9 tabs

Status of fission yield measurements

International Nuclear Information System (INIS)

Maeck, W.J.

1979-01-01

Fission yield measurement and yield compilation activities in the major laboratories of the world are reviewed. In addition to a general review of the effort of each laboratory, a brief summary of yield measurement activities by fissioning nuclide is presented. A new fast reactor fission yield measurement program being conducted in the US is described

Influence of the cosmic-ray induced fission tracks on the fission track of extraterrestric minerals via the 238U spontaneous fission

International Nuclear Information System (INIS)

Damm, G.; Thiel, K.

1977-01-01

The age determined by counting fission tracks of lunar and meteorite materials is obviously falsified by additional fission track parts not to be accounted for by the spontaneous fission of uranium 238. For this p and n induced fissions of U, Th and other hreavy elements through the cosmic radiation come into consideration. In order to determine the possible part of such interference factors, a simulation experiment at the proton synchrocycloton (CERN, Geneva) has been carried out and independently of this, the production rates for the p and n induced U, Th, Bi, Pb and Au in the surface-near regolith layers of the moon were calculated. It could be seen that the irradiation age as well as the spacial distribution of the heavy metals in the samples to be dated must be considered. (RB) [de

Progress in fission product nuclear data

International Nuclear Information System (INIS)

Lammer, M.

1983-08-01

This is the ninth issue of a report series on Fission Product Nuclear Data (FPND) which is published by the Nuclear Data Section (NDS) of the International Atomic Energy Agency (IAEA). The purpose of this series is to inform scientists working on FPND, or using such data, about all activities in this field which are planned, ongoing, or have recently been completed. The main part of this report consists of unaltered original contributions which the authors have sent to IAEA/NDS. The present issue contains also a section with some recent references relative to fission product nuclear data, which were not covered by the contributions submitted. The types of activities being included in this report are measurements, compilations and evaluations of: Fission product yields (neutron induced and spontaneous fission); Neutron reaction cross sections of fission products; Data related to the radioactive decay of fission products; Delayed neutron data of fission products; and lumped fission product data (decay heat, absorption etc.). The eighth issue of this series has been published in July 1982 as INDC(NDS)-130. The present issue includes contributions which were received by NDS between 1 August 1982 and 25 June 1983

Properties of Fission-Product decay heat from Minor-Actinide fissioning systems

International Nuclear Information System (INIS)

Oyamatsu, Kazuhiro; Mori, Hideki

2000-01-01

The aggregate Fission-Product (FP) decay heat after a pulse fission is examined for Minor Actinide (MA) fissiles 237 Np, 241 Am, 243 Am, 242 Cm and 244 Cm. We find that the MA decay heat is comparable but smaller than that of 235 U except for cooling times at about 10 8 s (approx. = 3 y). At these cooling times, either the β or γ component of the FP decay heat for these MA's is substantially larger than the one for 235 U. This difference is found to originate from the cumulative fission yield of 106 Ru (T 1/2 = 3.2x10 7 s). This nuclide is the parent of 106 Rh (T 1/2 = 29.8 s) which is the dominant source of the decay heat at 10 8 s (approx. = 3 y). The fission yield is nearly an increasing function of the fissile mass number so that the FP decay heat is the largest for 244 Cm among the MA's at the cooling time. (author)

Symmetric and asymmetric ternary fission of hot nuclei

International Nuclear Information System (INIS)

Siwek-Wilczynska, K.; Wilczynski, J.; Leegte, H.K.W.; Siemssen, R.H.; Wilschut, H.W.; Grotowski, K.; Panasiewicz, A.; Sosin, Z.; Wieloch, A.

1993-01-01

Emission of α particles accompanying fusion-fission processes in the 40 Ar + 232 Th reaction at E( 40 Ar) = 365 MeV was studied in a wide range of in-fission-plane and out-of-plane angles. The exact determination of the emission angles of both fission fragments combined with the time-of-flight measurements allowed us to reconstruct the complete kinematics of each ternary event. The coincident energy spectra of α particles were analyzed by using predictions of the energy spectra of the statistical code CASCADE . The analysis clearly demonstrates emission from the composite system prior to fission, emission from fully accelerated fragments after fission, and also emission during scission. The analysis is presented for both symmetric and asymmetric fission. The results have been analyzed using a time-dependent statistical decay code and confronted with dynamical calculations based on a classical one-body dissipation model. The observed near-scission emission is consistent with evaporation from a dinuclear system just before scission and evaporation from separated fragments just after scission. The analysis suggests that the time scale of fission of the hot composite systems is long (about 7x10 -20 s) and the motion during the descent to scission almost completely damped

Monte carlo sampling of fission multiplicity.

Energy Technology Data Exchange (ETDEWEB)

Hendricks, J. S. (John S.)

2004-01-01

Two new methods have been developed for fission multiplicity modeling in Monte Carlo calculations. The traditional method of sampling neutron multiplicity from fission is to sample the number of neutrons above or below the average. For example, if there are 2.7 neutrons per fission, three would be chosen 70% of the time and two would be chosen 30% of the time. For many applications, particularly {sup 3}He coincidence counting, a better estimate of the true number of neutrons per fission is required. Generally, this number is estimated by sampling a Gaussian distribution about the average. However, because the tail of the Gaussian distribution is negative and negative neutrons cannot be produced, a slight positive bias can be found in the average value. For criticality calculations, the result of rejecting the negative neutrons is an increase in k{sub eff} of 0.1% in some cases. For spontaneous fission, where the average number of neutrons emitted from fission is low, the error also can be unacceptably large. If the Gaussian width approaches the average number of fissions, 10% too many fission neutrons are produced by not treating the negative Gaussian tail adequately. The first method to treat the Gaussian tail is to determine a correction offset, which then is subtracted from all sampled values of the number of neutrons produced. This offset depends on the average value for any given fission at any energy and must be computed efficiently at each fission from the non-integrable error function. The second method is to determine a corrected zero point so that all neutrons sampled between zero and the corrected zero point are killed to compensate for the negative Gaussian tail bias. Again, the zero point must be computed efficiently at each fission. Both methods give excellent results with a negligible computing time penalty. It is now possible to include the full effects of fission multiplicity without the negative Gaussian tail bias.

An analysis of the additional fission product release phenomena

International Nuclear Information System (INIS)

Takeda, Tsuneo; Nagai, Hitoshi

1978-09-01

The additional fission product release behavior through a defect hole on the cladding of fuel rods has been studied qualitatively with a computer program CODAC-ARFP. The additional fission product release phenomena are described as qualitative evaluation. The additional fission product release behavior in coolant temperature and pressure fluctuations and in reactor start-up and shut-down depends on coolant water flow behavior into and from the free space of fuel rods through a defect hole. Based on the results of evaluations, the experimental results with an inpile water loop OWL-1 are described in detail. The estimation methods of fission product quantity in the free space and fission product release ratio (quantity released into the coolant/quantity in the free space before beginning of release) are necessary for analysis of the fission product release behavior; the estimation method of water flow through a defect hole is also necessary. In development of the above estimation methods, outpile and capsule experiments supporting the additional fission product release experiments are required. (author)

New fission valley for 258Fm and nuclei beyond

International Nuclear Information System (INIS)

Moeller, P.; Nix, J.R.; Swiatecki, W.J.

1986-01-01

Experimental results on the fission properties of nuclei close to 264 Fm show sudden and large changes with a change of only one or two neutrons or protons. The nucleus 258 Fm, for instance, undergoes symmetric fission with a half-life of about 0.4 ms and a kinetic energy peaked at about 235 MeV whereas 256 Fm undergoes asymmetric fission with a half-life of about 3 h and a kinetic energy peaked at about 200 MeV. Qualitatively, these sudden changes hve been postulated to be due to the emergence of fragment shells in symmetric fission products close to 132 Sn. A quantitative calculation that shows where high-kinetic-energy symmetric fission occurs and why it is associated with a sudden and large decrease in fission half-lives. The study is based on calculations of potential-energy surfaces in the macroscopic-microscopic model and a semi-empirical model for the nuclear inertia. The implications of the new fission valley on the stability of the heaviest elements is discussed. 33 refs., 12 figs

Systematics of Fission-Product Yields

International Nuclear Information System (INIS)

Wahl, A.C.

2002-01-01

Empirical equations representing systematics of fission-product yields have been derived from experimental data. The systematics give some insight into nuclear-structure effects on yields, and the equations allow estimation of yields from fission of any nuclide with atomic number Z F = 90 thru 98, mass number A F = 230 thru 252, and precursor excitation energy (projectile kinetic plus binding energies) PE = 0 thru ∼200 MeV--the ranges of these quantities for the fissioning nuclei investigated. Calculations can be made with the computer program CYFP. Estimates of uncertainties in the yield estimates are given by equations, also in CYFP, and range from ∼ 15% for the highest yield values to several orders of magnitude for very small yield values. A summation method is used to calculate weighted average parameter values for fast-neutron (∼ fission spectrum) induced fission reactions

Systematics of Fission-Product Yields

Energy Technology Data Exchange (ETDEWEB)

A.C. Wahl

2002-05-01

Empirical equations representing systematics of fission-product yields have been derived from experimental data. The systematics give some insight into nuclear-structure effects on yields, and the equations allow estimation of yields from fission of any nuclide with atomic number Z{sub F} = 90 thru 98, mass number A{sub F} = 230 thru 252, and precursor excitation energy (projectile kinetic plus binding energies) PE = 0 thru {approx}200 MeV--the ranges of these quantities for the fissioning nuclei investigated. Calculations can be made with the computer program CYFP. Estimates of uncertainties in the yield estimates are given by equations, also in CYFP, and range from {approx} 15% for the highest yield values to several orders of magnitude for very small yield values. A summation method is used to calculate weighted average parameter values for fast-neutron ({approx} fission spectrum) induced fission reactions.

Decay Curves and Half-Lives of Gamma-Emitting States from a Study of Prompt Fission Gamma Radiation

Energy Technology Data Exchange (ETDEWEB)

Albinsson, H [Chalmers Univ. of Technology, Goeteborg (SE)

1971-04-15

Measurements were made on the time distributions of the prompt gamma radiation emitted from fragments in the thermal-neutron induced fission of 235U. The gamma radiation emitted during different time intervals after the fission event was studied with the help of a collimator, the position of which was changed along the path of the fragments. In this way decay curves were obtained from which half-lives could be estimated. Time components with half-lives of 7.5, 18 and 60 ps were found and their relative intensities were calculated. Half-lives and associated intensities are in good agreement with earlier data from uranium and californium fission. Problems involved in this type of study are discussed. The collimator technique has proved to be effective for determination of half lives down to less than 10 ps

Asymmetry in ternary fission induced by polarized neutrons and fission mechanism

International Nuclear Information System (INIS)

Bunakov, V.E.; Gennenvajn, F.; Dzhessinger, P.; Mutterer, M.; Petrov, G.A.

2003-01-01

The results of measuring the P-odd, P-even (right-left) and T-odd asymmetries of the charged particles emission in the double and ternary fission, induced by the polarized neutrons, are considered. It is shown, what kind of information on the mechanism of the ternary nuclear fission may be obtained from the theoretical analysis of these data [ru

Simulation of Fission Product Liftoff Behavior During Depressurization Transients

International Nuclear Information System (INIS)

Tak, Nam-il; Yoon, Churl; Lee, Sung Nam

2016-01-01

As one of crucial technologies for the NHDD project, the development of the GAMMA-FP code is on-going. The GAMMA-FP code is targeted for fission product transport analysis under accident conditions. A well-known experiment named COMEDIE considered two important phenomena, i.e., fission product plateout and liftoff, for fission product transport within the primary circuit of a prismatic high temperature gas cooled reactor. The accumulated fission products on the structural material via the plateout can be liftoff during a blowdown phase after a pipe break accident. Since the fission product liftoff can increase a radioactivity risk, it is important to predict the amount of fission product liftoff during depressurization accidents. In this work, a model for fission product liftoff is implemented into the GAMMA-FP code and the GAMMA-FP code with the implemented model is validated using the COMEDIE blowdown test data. The results of GAMMA-FP show that the GAMMA-FP code can reliably simulate a pressure transient during blowdown phase after a pipe break accident. In addition, a reasonable amount of fission product liftoff was predicted by the GAMMA-FP code. The maximum difference between the measured and predicted liftoff fraction was less than a factor of 10. More in-depth study is required to increase the accuracy of prediction for a fission product liftoff

$\\beta$-delayed fission in proton-rich nuclei in the lead region

CERN Document Server

AUTHOR|(CDS)2085005; Huyse, Mark; Popescu, Lucia

Nuclear fission is the breakup of an atomic nucleus into two (sometimes three) fragments, thereby releasing a large amount of energy. Soon after its discovery in the late 1930’s, the gross properties of the fission phenomenon were explained by macroscopic nuclear models. Certain features however, such as asymmetric fission-fragment mass distributions in the actinide region, require the inclusion of microscopic effects. This interplay of the microscopic motion of individual nucleons on this macroscopic process is, until today, not yet fully understood. The phenomenon of fission has therefore been of recurring interest for both theoretical and experimental studies. This thesis work focuses on the $\\beta$-delayed fission ($\\beta$DF) process, an excellent tool to study low-energy fission of exotic nuclei, which was discovered in 1966 in the actinide region. In this two-step process, a precursor nucleus first undergoes $\\beta$-decay to an excited level in the daughter nucleus, which may subsequently fission. Rec...

Relevance of environmental concerns in contemplating development of fission fusion hybrids: a personal view

International Nuclear Information System (INIS)

Holdren, J.

1974-01-01

A brief comparison of hybrids to pure fusion systems with respect to timing and economics is given. The relevance of environmental concerns is discussed along with environmental criteria for hybrid designs. (U.S.)

Potentials of fissioning plasmas

International Nuclear Information System (INIS)

Karlheinz, Thom.

1979-01-01

Successful experiments with the nuclear pumping of lasers have demonstrated that in gaseous medium the kinetic energy of fission fragments can be converted directly into non-equilibrium optical radiation. This confirms the concept that the fissioning medium in a gas-phase nuclear reactor shows an internal structure such as a plasma in nearly thermal equilibrium varying up to a state of extreme-non-equilibrium. The accompanying variations of temperatures, pressure and radiative spectrum suggest wide ranges of applications. For example, in the gas-phase fission reactor concept enriched uranium hexafluoride or an uranium plasma replaces conventional fuel elements and permits operation above the melting point of solid materials. This potential has been motivation for the US National Aeronautics and Space Administration (NASA) to conduct relevant research for high specific impulse propulsion in space. The need to separate the high temperature gaseous fuel from the surfaces of a containing vessel and to protect them against thermal radiation has led to the concept of an externally moderated reactor in which the fissioning gaseous material is suspended by fluid dynamic means and the flow of opaque buffer gas removes the power. The gaseous nuclear fuel can slowly be circulated through the reactor for continuous on-site reprocessing including the annihilation of transuranium actinides at fission when being fed back into the reactor. An equilibrium of the generation and destruction of such actinides at fission when being fed back into the reactor. An equilibrium of the generation and destruction of such actinides can thus be achieved. These characteristics and the unique radiative properties led to the expectation that the gas-phase fission reactor could feature improved safety, safeguarding and economy, in addition to new technologies such as processing, photochemistry and the transmission of power over large distances in space

Material synergism fusion-fission

International Nuclear Information System (INIS)

Sankara Rao, K.B.; Raj, B.; Cook, I.; Kohyama, A.; Dudarev, S.

2007-01-01

In fission and fusion reactors the common features such as operating temperatures and neutron exposures will have the greatest impact on materials performance and component lifetimes. Developing fast neutron irradiation resisting materials is a common issue for both fission and fusion reactors. The high neutron flux levels in both these systems lead to unique materials problems like void swelling, irradiation creep and helium embitterment. Both fission and fusion rely on ferritic-martensitic steels based on 9%Cr compositions for achieving the highest swelling resistance but their creep strength sharply decreases above ∝ 823K. The use of oxide dispersion strengthened (ODS) alloys is envisaged to increase the operating temperature of blanket systems in the fusion reactors and fuel clad tubes in fast breeder reactors. In view of high operating temperatures, cyclic and steady load conditions and the long service life, properties like creep, low cycle fatigue,fracture toughness and creepfatigue interaction are major considerations in the selection of structural materials and design of components for fission and fusion reactors. Currently, materials selection for fusion systems has to be based upon incomplete experimental database on mechanical properties. The usage of fairly well developed databases, in fission programmes on similar materials, is of great help in the initial design of fusion reactor components. Significant opportunities exist for sharing information on technology of irradiation testing, specimen miniaturization, advanced methods of property measurement, safe windows for metal forming, and development of common materials property data base system. Both fusion and fission programs are being directed to development of clean steels with very low trace and tramp elements, characterization of microstructure and phase stability under irradiation, assessment of irradiation creep and swelling behaviour, studies on compatibility with helium and developing

History of the discovery of uranium fission by neutrons

International Nuclear Information System (INIS)

Simane, C.

1989-01-01

The history is briefly described of the discovery of uranium fission by neutrons, based on the texts of original scientific studies, memories or biographies of those who participated in the discovery and of their contemporaries. Obstacles that stood in the way of the discovery are discussed. It is stated that only a few scientists contributed to the discovery of uranium fission. The fission process itself still remains subject of physical research which studies its detailed laws. (Z.M.). 2 tabs., 16 refs

Self-Organized Fission Control for Flocking System

Directory of Open Access Journals (Sweden)

Mingyong Liu

2015-01-01

Full Text Available This paper studies the self-organized fission control problem for flocking system. Motivated by the fission behavior of biological flocks, information coupling degree (ICD is firstly designed to represent the interaction intensity between individuals. Then, from the information transfer perspective, a “maximum-ICD” based pairwise interaction rule is proposed to realize the directional information propagation within the flock. Together with the “separation/alignment/cohesion” rules, a self-organized fission control algorithm is established that achieves the spontaneous splitting of flocking system under conflict external stimuli. Finally, numerical simulations are provided to demonstrate the effectiveness of the proposed algorithm.

Fission-product source terms

International Nuclear Information System (INIS)

Lorenz, R.A.

1981-01-01

This presentation consists of a review of fission-product source terms for light water reactor (LWR) fuel. A source term is the quantity of fission products released under specified conditions that can be used to calculate the consequences of the release. The source term usually defines release from breached fuel-rod cladding but could also describe release from the primary coolant system, the reactor containment shell, or the site boundary. The source term would be different for each locality, and the chemical and physical forms of the fission products could also differ

Correlated prompt fission data in transport simulations

Science.gov (United States)

Talou, P.; Vogt, R.; Randrup, J.; Rising, M. E.; Pozzi, S. A.; Verbeke, J.; Andrews, M. T.; Clarke, S. D.; Jaffke, P.; Jandel, M.; Kawano, T.; Marcath, M. J.; Meierbachtol, K.; Nakae, L.; Rusev, G.; Sood, A.; Stetcu, I.; Walker, C.

2018-01-01

Detailed information on the fission process can be inferred from the observation, modeling and theoretical understanding of prompt fission neutron and γ-ray observables. Beyond simple average quantities, the study of distributions and correlations in prompt data, e.g., multiplicity-dependent neutron and γ-ray spectra, angular distributions of the emitted particles, n - n, n - γ, and γ - γ correlations, can place stringent constraints on fission models and parameters that would otherwise be free to be tuned separately to represent individual fission observables. The FREYA and CGMF codes have been developed to follow the sequential emissions of prompt neutrons and γ rays from the initial excited fission fragments produced right after scission. Both codes implement Monte Carlo techniques to sample initial fission fragment configurations in mass, charge and kinetic energy and sample probabilities of neutron and γ emission at each stage of the decay. This approach naturally leads to using simple but powerful statistical techniques to infer distributions and correlations among many observables and model parameters. The comparison of model calculations with experimental data provides a rich arena for testing various nuclear physics models such as those related to the nuclear structure and level densities of neutron-rich nuclei, the γ-ray strength functions of dipole and quadrupole transitions, the mechanism for dividing the excitation energy between the two nascent fragments near scission, and the mechanisms behind the production of angular momentum in the fragments, etc. Beyond the obvious interest from a fundamental physics point of view, such studies are also important for addressing data needs in various nuclear applications. The inclusion of the FREYA and CGMF codes into the MCNP6.2 and MCNPX - PoliMi transport codes, for instance, provides a new and powerful tool to simulate correlated fission events in neutron transport calculations important in