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Neutron Fission and Capture Data

#0471


Measurements of Actinide Nuclear Data

Tech Area / Field

  • FIR-NOT/Nuclear and Other Technical Data/Fission Reactors

Status
8 Project completed

Registration date
01.11.1995

Completion date
29.10.1999

Senior Project Manager
Ryabeva E V

Leading Institute
Joint Institute of Nuclear Research, Russia, Moscow reg., Dubna

Supporting institutes

  • Kurchatov Research Center, Russia, Moscow\nVNIIEF, Russia, N. Novgorod reg., Sarov

Collaborators

  • European Commission / Joint Research Center / Institute for Reference Materials and Measurements, Belgium, Geel

Project summary

Creation of ecologically pure and wasteless nuclear energy is one of the most acute problems of today. One of the serious approaches towards the solution of this problem is the design of a facility with corresponding technology for the transmutation of radio toxic wastes of nuclear energetics into non-radio toxic waste. A full knowledge of constants of actinide nuclei are required for the development of safe, ecologically pure atomic energy technology with closed (wasteless) fuel cycle. The rates of actinide processing in a transmutor are, first of all, defined by the region of thermal and resonance neutrons, where maximum values of both neutron flux density and cross-sections of neutron induced fission and neutron capture are achieved. The data on these cross-sections for some nuclei (especially the short-lived ones) are either unknown or not fully or precisely determined.

The goal of the project is to obtain new experimental data on neutron cross-sections of fission and capture, on fission neutron multiplicities and the yields of delayed neutrons, depending on the energy of incident neutrons in the interval 1 eV<En<10 MeV for a group of actinide nuclei (from 232Th to 245Cm). The information planned to be obtained corresponds to the first priority request for nuclear data and will allow to create new versions of estimated nuclear constants files or to correct essentially the existing ones. The project include the following tasks:

separation of actinide isotopes and construction of isotope targets for measurements on different facilities; measurements of:

- cross-sections of neutron induced fission snf (En) and average multiplicity of fission neutrons for the following target nuclei: 236U, 242 Pu, 241Am,243Am, 245Cm on the LUE-50 accelerator in VNIIEF;

- effective (integral) fission cross-sections snf for 236U, 242 Pu, 241Am, 243Am, 245Cm target nuclei for precise normalisation of the energy dependent cross-section snf (En) for the each isotope on the critical assemblies and the BIGR reactor in VNIIEF;

- delayed neutron yield in 233Pa and 239Np fission though the 232Th(p,f) and 238U(p,f) reactions and the probability of fission (Pf=stpf/ stp) in the 236U(t,pf) reaction, on the EGP-10 in VNIIEF;

- cross-sections of neutron induced fission anf(En) and the fission width of 234U and 237Np neutron resonances in the sub-threshold area of 1 eV to200 eV and neutron capture cross sections for 237Nр and 232Th on, the IBR-30 booster of JINR;

- cross-sections of neutron induced fission snf (En) and neutron capture sng (En) and the multiplicity of emitted prompt fission gamma-quanta for 236U, 237Np и 239Pu in the sub-threshold area on the FAKEL accelerator of RRC KI;

- delayed neutron yield for short-lived fission fragments (T1/2 < 1 s) in the 237Nр, 239 Pu, 233U fission by slow neutrons on the IBR-2 pulsed reactor of JINR.

In the course of performing measurements on the project, it is supposed to use the available experimental facilities and new methodical developments and devices (multisectional 4p-gammа spectrometer, large liquid scintillator with avalanche fission chamber, pulsed mode of tandem Van der Graaft generator, channel of slow neutrons extracted by the method of scattering on a mirror etc.). This gives reasons to hope that there essential and confident new information will be obtained on the properties of the fissile nuclei under investigation.

Original and attractive aspects of the project are connected particularly with the use of radioactive tritium beams for the measurement of fission cross-sections of the short-lived actinides, and the unique possibilities of the IBR-2 pulsed reactor for studying of delayed neutrons with short delay times.

In carrying out of the project, the leading scientists of Russia and VNIIEF expects in the field of nuclear weapons testing and development will take part. In connection with the moratorium on nuclear explosions, physical investigations in VNIIEF are being concentrated mostly on laboratory methods with the use of the VNIIEF experimental base for implementation of Russian programs for creating safe atomic energy, and related problems of the transmutation of long-lived actinides in high-flux facilities.

The project is open to all potential participants who are interested in obtaining and discussing of the primary experimental results. To realize such possibilities annual meetings open for participation of foreign partners are planned. All other forms of cooperation consistent with the goals and the ISTC's Statute will be welcomed.

Up to now Prof. H. Weignmann (Institute for Reference Materials and Measurements, Geel, Belgium), Prof. Y. Kikuchi (Nuclear Data Center, Dept. of Reactor Engineering, Japan Atomic Energy Research Institute) and Dr. E. D. Arthur (Los Alamos National Laboratory, USA) confirmed they participation in that project.


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