Frank Laboratory of Neutron Physics

Nuclear Physics Department

Leader – E.V. Lychagin

Date and Time: Wednesday, 13 January 2020, at 11:00 AM

Venue: online seminar on Zoom, Frank Laboratory of Neutron Physics

1. Seminar topic: «Specifying high energy tail of 235-U, 239-Pu and 252-Cf prompt fission neutron spectra” focused on proposed experiment»

   Speaker: Martin Schulc

   Abstract:
   
   

   A better knowledge of the prompt fission neutron spectrum (PFNS) from Pu-239 neutron induced fission is important for high-burnup fuels and new generation reactors. This is especially true when considering neutron radiation damage from the PFNS high-energy tail, which can be improved thanks to the measurements of spectrum-averaged cross section (SACS) of well-known high-threshold dosimetry reactions. No SACS measurements exist in Pu-239(nth,f) prompt neutron field. In the latest IAEA evaluation, the extrapolation of Pu-239(nth,f) PFNS to outgoing energies above 8 MeV is based on SACS estimated by interpolation between SACS measured in U-233, U-235 and Cf-252 prompt neutron fields. Proposed experiment focuses on the measurement of SACS in Pu-239 PFNS since there are no experimental data. The Research Centre Rez expert team measured and published many SACS in U-235, and Cf-252 prompt neutron fields.




2. Seminar topic: «The use of integral experiments for nuclear data benchmarking focused on our department work»

   Speaker: Michal Kostal

   Abstract:
   
   

   Integral quantities can usually be measured much more accurately than differential nuclear data, so it is tempting to use such data for validation, sometimes even for improvement of differential nuclear data. Such integral data can be spectrum-averaged cross sections or cross section ratios, kinetic parameters or leakage spectra. Nuclear data section of IAEA stated, that experience from the analysis of criticality benchmarks indicates that data adjustments on such benchmarks are not unique. An obvious example is fairly good performance of all major libraries in predicting the criticality of major benchmark cases in spite of relatively large differences in the cross sections, where good performance is achieved mainly due to compensating effects. Similarly, blind application of data adjustment techniques can lead to data files that apparently perform well in selected integral benchmarks, but violate the uncertainties in experimentally measured differential nuclear data. Both LR-0 reactor and 252Cf Lab are suitable for performing of integral experiments suitable for validation of differential quantities.

Link to join the seminar