Important comments on KERMA factors and DPA cross-section data in ACE files of JENDL-4.0, JEFF-3.2 and ENDF/B-VII.1

We have studied reasons of differences of KERMA factors and DPA cross-section data among nuclear data libraries. Here the KERMA factors and DPA cross-section data included in the official ACE files of JENDL-4.0, ENDF/B-VII.1 and JEFF-3.2 are examined in more detail. As a result, it is newly found out that the KERMA factors and DPA cross-section data of a lot of nuclei are different among JENDL-4.0, ENDF/B-VII.1 and JEFF-3.2 and reasons of the differences are the followings: 1) large secondary particle production yield, 2) no secondary gamma data, 3) secondary gamma data in files12–15 mt = 3, 4) mt = 103–107 data without mt = 600 s–800 s data in file6. The issue 1) is considered to be due to nuclear data, while the issues 2)-4) seem to be due to NJOY. The ACE files of JENDL-4.0, ENDF/B-VII.1 and JEFF-3.2 with these problems should be revised after correcting wrong nuclear data and NJOY problems

Problems of TENDL-2015 official ACE files

Recently we tested the official ACE files of TENDL-2015 and found the following problems in the files, a)�� no p-table data except for those of 235U, 235mU and 238U in the neutron sub-library, b) no secondary gamma data for a lot of nuclei in the neutron, proton, deuteron, triton, He-3, and alpha sub-libraries.By a simple calculation, it was demonstrated that effects of the issues were not so small as follows, i) �the effect of no unresolved resonance data in ACE files was large in a special case as pure niobium, ii) secondary gammas produced in neutron-gamma coupling MCNP calculations were not correct because wrong data were used as secondary gamma data. The issues were probably caused by simple mistakes of NJOY processing. Note that the issues also occur partially in the official ACE files of TENDL-2017

Analyses of JAEA/FNS iron in-situ experiment with latest nuclear data libraries

We found ENDF/B-VIII.0 caused the following problems through our analyses of the iron insitu experiment at JAEA/FNS; 1) the neutron flux of 1 - 10 keV is overestimated more in the shallower region of the iron assembly, 2) the reaction rate of 115In (n,n’)115mIn is underestimated more in the deeper region, 3) the neutron flux above 10 MeV is underestimated more in the deeper region. The reasons for these problems were investigated in detail and it was specified that the inelastic scattering data of 56Fe in ENDF/BVIII. 0 mainly caused the first and second problems and that the cross section of the (n,2n) reaction and the angular distribution data of the elastic scattering of 56Fe in ENDF/B-VIII.0 caused the third problem

A negative probability table problem of heating number in FENDL-3.1d ACE file

We found out that probability table (p-table) data for heating number in the FENDL-3.1d ACE files for 33 nuclei included negative values. Thus we investigated its reason in detail. As a result, it was specified that the reason was that partial KERMA factors of the radiative capture reaction became too large, because the energy-balance was broken or NJOY did not treat secondary gammas of a special format. We proposed two solutions for this issue; 1) to modify NJOY so as to calculate partial KERMA factors with the kinematics method, 2) to set p-tables for heating number to “1.0” or average heating numbers. New ACE files of FENDL-3.1d produced with the two solutions had no negative p-tables for heating number

Generation and verification of ORIGEN and ORIGEN-S activation cross-section libraries of JENDL-5 and JENDL/AD-2017

Activation cross-section libraries for the ORIGEN and ORIGEN-S codes have been generated from the latest Japanese nuclear data library JENDL-5 and JENDL Activation Cross Section File for Nuclear Decommissioning 2017 (JENDL/AD-2017) for activation calculations in nuclear facility decommissioning. The ORIGEN activation cross-section libraries of the 200- and 48-group structures were generated with the AMPX-6 code, while the ORIGEN-S activation cross-section libraries with a MAXS format of the 199-group structure were done with the PREPRO2018 code. In order to verify the generated ORIGEN and ORIGEN-S activation cross-section libraries, activation calculations for Japan Power Demonstration Reactor (JPDR) were carried out in detailed with the DORT, ORIGEN and ORIGEN-S codes, the generated activation cross-section libraries, the ORIGEN and ORIGEN-S bundled activation cross-section libraries, and a JPDR partial model. The following comparisons were performed: 1) the ORIGEN calculation results with the generated activation cross-section libraries and bundled ones, 2) the 200-group and 48-group ORIGEN calculations, 3) the ORIGEN-S calculation results with the generated activation cross-section libraries and bundled ones, and 4) the ORIGEN and ORIGEN-S calculations with the JENDL-5 activation cross-section libraries. Most of the differences of the calculation results were less than 20%, which demonstrated that the libraries were generated adequately. The generated libraries have been released with additional programs from the JAEA website

EFFECT OF IAEA PATCH FOR TRANSX2.15

IAEA released two unofficial patches for TRANSX2.15 for the MATXS file of FENDL-2.0 in 1998, but the patches have not been known well. The first patch is for all MATXS files, while the second one is effective only for MATXS files with mixed data types, which are very rare. This paper demonstrates with simple calculations that the first patch is essential because it solves a problem of extremely large neutron fluxes caused by the original TRANSX2.15 code. We hope that the patch will be included in the official TRANSX2.15 release

Problems of DPA cross-sections above 20 MeV in FENDL-3.1d found in A-FNS neutronics analysis

Our detailed investigation on the data of iron nuclei in nuclear data library FENDL-3.1d figured out that residual nucleus production yield data just above 20 MeV had a problem, which caused a sharp spike in the DPA cross-section. In addition, we revealed that the same and similar problems occurred the data in other 73 nuclei FENDL-3.1d selected from TENDL- 2010 or TENDL-2011. Thus, we revised the yield data and verified that the sharp spike just above 20 MeV in the DPA cross-section disappeared using the revised data. Moreover, the DPA cross-section data of 49 nuclei in FENDL-3.1d from JENDL/HE-2007 became much smaller sharply above 20 MeV because the nuclei had no energy distribution data of residual nuclei above 20 MeV. Other problems occurred in 13 nuclei of FENDL-3.1d from JEFF-3.1.1 above several MeV, due to wrong energy distribution data of recoil nucleus in the inelastic scatter- ing to continuum states below 20 MeV and no energy distribution data of residual nuclei above 20 MeV. The DPA cross-section data of more than 70% of nuclei in FENDL-3.1d have problems due to non-physical data in the original nuclear data