Measurement of fission product yields in the quasi-mono-energetic neutron-induced fission of 238U

Abstract

The cumulative yields of various fission products in the 6. 35, 8.53, 9.35 and 12.52 MeV quasi-monoenergetic neutron induced fission of 238 U have been determined by using the off-line γ -ray spectrometric technique. The mass chain yields were obtained from the fission product yields by using charge distribution correction. From the mass yield data, the peak-to-valley (P/V) ratio, the average value of light mass ( A L ), heavy mass ( A H ) and thus the average number of neutrons ( υ expt ) were obtained in the 238 U(n, f ) reaction for the above mentioned four neutron energies. The present and literature data in the 238 U(n, f ) and 238 U (γ, f ) reactions at various energies were compared to arrive at the following conclusions. (i) The yields of fission products for A = 133-134, A = 138-140, and A = 143-144 and their complementary products in the 238 U(n, f ) and 238 U(γ, f ) reactions are higher than other fission products, which has been explained from the point of even-odd effect and standard I and standard II asymmetric mode of fission. (ii) The yields of symmetric products increase and thus the peak-to-valley (P/V) ratios decrease with excitation energy, whereas the ν expt values increase with excitation energy. (iii) The variation of A L , A H and υ expt values with excitation energy behave differently in between 238 U(n, f ) and 238 U(γ, f ) reactions, which may be due to the different types of reaction mechanism for the neutron and photon with 238 U. = 6. 35, 8.53, 9.35 and 12.52 MeV; measured fission product yields, mass yield distributions, off-line γ -ray spectrometric technique, peak-to-valley (P/V) ratio, average number of neutrons ( υ expt ), average light mass ( A L ), average heavy mass ( A H )

Tests of ionization chambers for future photofission experiments

“…EPJ Web of Conferences 193, 04006 (2018) https://doi.org/10.1051/epjconf/201819304006 FISSION 2017 respectively. These values are in good agreement with data taken by other groups [13]. The missing corrections influence in particular the heavy fission fragment, which loses more energy, resulting in a slightly broadened peak.…”

Determination of 238U(n, γ) and 238U(n, f) reactions cross-section in the neutron emission spectrum of 241Am-Be source

“…( ) is the average fission yield of the product in the energy interval between E i and E i+1 . was calculated as Y 8 = 4.2 ± 0.3% based on data points taken from [47,48,50,[56][57][58][59]. There were few data concerning 238 U(n, f) 134 I and 235 U(n, f) 134 I which are related to the decay to 134 Te as an accumulative mass range.…”

Cumulative fission yield measurements with 14.7 MeV neutrons on 238U*

“…With the development of a thorium uranium circulating reactor and a fast neutron breeder reactor, the knowledge of 238 U(n, f) fission reaction induced by a 14 MeV neutron is significant. For example, 147 Nd plays a key role in nuclear fuel burnup monitoring, and there is a 11.86% discrepancy in previous measured data [3].…”

“…Although nuclear fission was discovered more than 80 years ago, experimental and theoretical studies on it are still far from being complete [1,2]. Detailed data on the fission cross section, fission-fragment mass, kinetic energy distributions, fission neutron spectrum, and γ-ray spectrum are urgently needed for generation-IV reactor modeling of fuel inventory, reactor decay heat estimation in accident scenario modeling, nuclear material safeguard monitoring, and exploration of nuclear fission theory [3]. Because 238 U is associated with 235 U in a conventional reactor and with 239 Pu in a fast reactor, the fission product yields (FPYs) of 238 U at different neutron energies are important for both conventional and fast reactors [4,5].…”