SPECTRAL-AVERAGE CROSS SECTION VALIDATION IN LR-0 REACTOR SPECTRUM OF ~(55)MN(N,2N),~（90）ZR(N,2N) AND ~（127）I(N,2N) REACTIONS

摘要

This article deals with the validation of spectral averagecross-sections (SACS) of ~(55)Mn(n,2n)~(54)Mn, ~(90)Zr(n,2n)~(89)Zrand ~(127)I(n,2n)~(126)I reactions in well-defined LR-0 reactorspectrum. The measurement of SACS for selected reactionsis of high interest because they are used for the practicalreactor dosimetry and also for refinement of prompt fissionneutron spectra of ~(235)U in the region of higher energies.Various experiments for description of neutron fieldin reactor and detector characterization, which are necessaryfor validation, are described. The spectral averagecross-sections are derived from Net Peak Areas of irradiatedsamples measured using a semiconductor high puritygermanium detector. The spectral average cross sectionin ~(235)U prompt fission neutron spectrum was experimentallydetermined to be 0.239 ± 0.015 mb for ~(55)Mn, 1.209± 0.052 mb for ~(127)I and 0.107 ± 0.005 mb for ~(90)Zr. Theobtained results were compared with MCNP6 calculationsusing ENDF/B-Ⅷ.0, ENDF/B-Ⅷ.1, JEFF-3.1, JEFF-3.2,JENDL-3.3, JENDL-4, ROSFOND-2010, CENDL-3.1 andIRDFF-1.05 nuclear data libraries. Notable discrepancieswere found in ~(90)Zr(n,2n)~(89)Zr and ~(127)I(n,2n)~(126)I reactions.