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Neutron Data for Thorium Cycle


Measurement and Evaluation of the Thorium Fuel Cycle Neutron Data

Tech Area / Field

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

3 Approved without Funding

Registration date

Leading Institute
FEI (IPPE), Russia, Kaluga reg., Obninsk

Project summary

Measurements of the high priority neutron data for 232Th, 233U to fill the gap in the existing data files. Re-evaluation of the neutron data files for 232Th, 233U and 231,233 Pa on the basis of the new experimental data. Testing of the new data files with benchmark experimental data.
1. Measurements of the inelastic neutron scattering for 232Тh discrete levels in the energy range of 0.2 - 0.6 MeV with an accuracy ~5%.
2. Measurements of relative abundance, periods and absolute total yields of delayed neutrons for neutron induced fission of 232Th, 233U in the energy range from 1.2 MeV to 5 MeV and at 15 MeV.
3. Measurements the total cross section for 232Th and 233U in the energy range from 0.3 to 7 MeV with accuracy 3 - 4% and precise measurements of the neutron leakage spectrum from the 232Th thick sphere with a 252Cf neutron source
4. Evaluation of the neutron data on the basis new experimental data and theoretical models, the test of new evaluations for 232Th,233U and 231,233Pa on available benchmark data.

Technical Approach and Methodology

The measurements of differential nuclear data will be carried out using the electrostatic accelerators and 252Cf as neutron sources. The modern detector systems will be used for this purpose: fast fission chambers, a time-of-flight neutron spectrometer, different neutron detectors and electronics. A modern data acquisition and processing system based on the IBM PC computers will be applied for data measurement and analysis. The experiments will be simulated by Monte-Carlo method.

An experimental data analysis and development of cross sections systematics will be carried out on the basis of available experimental data. A comparison of the microscopic and macroscopic nuclear data with the systematics and cross section calculations will be performed using available models and computer codes. The most reliable input parameters, models and. computer codes will be determined to ensure the best consistent nuclear data description.

Anticipated results

The data for inelastic scattering on the first levels of 232Th will be measured in the energy range of 0.2 - 0.6 MeV with accuracy ~5%. These data allow us to increase the accuracy of the evaluated data library.

The relative abundance, periods and absolute total yields of delayed neutrons will be measured for the neutron induced fission of 232Th and 233U in the neutron energy range from 1.2 MeV to 5 MeV and at 15 MeV.

The total cross section for 232Th and 233U (0.3 - 7 MeV) will be measured and evaluated. The leakage neutron spectra of 252Cf source in energy range of 0.2 - 7 MeV from Th-sphere will be measured as well.

All experimental data obtained will be analyzed on the basis of modem theoretical models. An improved statistical description of the neutron cross sections based on the consistent analysis of all available experimental information will be performed. The neutron cross sections for 232Th, 233U and 231,233Pa will be re-evaluated for all cases where essential contradictions of new experimental data with existing evaluations will be found. The cross sections responsible for production of 232U will be re-evaluated on the basis of the new systematics of the (n, 2n), (n, xf) and (n, g) reactions developed recently in IPPE. The neutron cross sections recommended would be tested against benchmark data on KҐ and Keff obtained for the special Th-U critical assembles developed in IPPE.

Potential Role of Foreign Collaborators

The investigations in the field of the neutron data measurements and evaluation are carrying out in the following organizations: IRMM (Belgium), Tohoku University (Japan), JAERI (Japan), CE Cadarache (France), NDC ENEA (Italy). The collaboration may be useful to exchange the experience in this field.


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