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Title: Recent Progress on Fission Nuclear Data

Abstract

This report describes LANL's recent progress on nuclear fission.

Authors:
 [1]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1373514
Report Number(s):
LA-UR-17-26492
DOE Contract Number:
AC52-06NA25396
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; Atomic and Nuclear Physics

Citation Formats

Kawano, Toshihiko. Recent Progress on Fission Nuclear Data. United States: N. p., 2017. Web. doi:10.2172/1373514.
Kawano, Toshihiko. Recent Progress on Fission Nuclear Data. United States. doi:10.2172/1373514.
Kawano, Toshihiko. 2017. "Recent Progress on Fission Nuclear Data". United States. doi:10.2172/1373514. https://www.osti.gov/servlets/purl/1373514.
@article{osti_1373514,
title = {Recent Progress on Fission Nuclear Data},
author = {Kawano, Toshihiko},
abstractNote = {This report describes LANL's recent progress on nuclear fission.},
doi = {10.2172/1373514},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2017,
month = 7
}

Technical Report:

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  • A study was made of the high-temperature fission product trapping capabilities of various charcoals and metal-charcoal combinations in an attempt to develop a satisfactory trap for use in gas-cooled reactors. Tests of the iodine and tellurium trapping capabilities of silver and copper coated charcoal at temperatures up to 900 deg F were conducted. It was observed that metal coated charcoal exhibits much better holdup characteristics compared to metal mesh or turn ings alone. The capacity for delaying radioiodine was measured in terms of "Reactor Equivalent Delay" (in days) to give an indication of how long a particular iodine atom enteringmore » one of the traps could be expected to remain. It was found that coconut charcoals exhibited greater delay characteristics than charcoals of coke origin. A strong dependence of delay time on temperature was observed. Silver coatings caused a longer delay than copper. (M.C.G.)« less
  • The fission cross sections of U/sup 235/, U/sup 234/, U/sup 236/, and U/ sup 238 were measured in terms of the U/sup 235/ cross section from a few kev, or the effective threshold, to 4 Mev. Monoenergetic neutrons were from the V(p,n), Li(p.n), and T(p,n) reactions produced by protons accelerated by electrostatic generators. The published cross sections of U/sup 234/ and U/sup 236/ are compared with the cross section of U/sup 235/. The results for U/sup 233/ differ somewhat from values reported in the literature. The absorption cross sections of U/sup 235/ and Fu/sup 239/ were measured at six energiesmore » in the 5 to 50 kev energy range. Neutrons from the reaction V/sup 51/(p,n)Cr/sup 51/ were used in spherical shell transmission measurements. The results show, in general, a decrease in absorption cross section with increasing energy up to about 30 kev and then a nearly constant value (up to 50 bev) of about 2.8 b for U/sup 235/ and 2.2 b for Pu/sup 239/. The variation of nu for U/sup 235/ with incident neutron energy was studied for the energy range 0 to 5 Mev. Neutrons were produced by the T(p,n) and the D(d,n) reactions. Fission neutrons were detected with a shielded recoil counter in coincidence with fission fragment pulses from an annular fission chamber placed around the recoil counter. The measurements were calibrated in terms of thermal nu by performing the experiment with essentially thermal neutrons. The results show an increase of nu of about 30% at 5 Mev. This is in fair agreement with the original prediction of this effect which was based on a phenomenological theory of evaporation of neutrons from the excited fission fragments. (auth)« less
  • Topics covered include: studies of (n, charged particle) reactions with 14 to 15 MeV neutrons; photoneutron cross sections for /sup 15/N; neutron radiative capture; Lane-model analysis of (p,p) and (n,n) scattering on the even tin isotopes; neutron scattering cross sections for /sup 181/Ta, /sup 197/Au, /sup 209/Bi, /sup 232/Th, and /sup 238/U inferred from proton scattering and charge exchange cross sections; neutron-induced fission cross sections of /sup 245/Cm and /sup 242/Am; fission neutron multiplicities for /sup 245/Cm and /sup 242/Am; the transport of 14 MeV neutrons through heavy materials 150 < A < 208; /sup 249/Cm energy levels from measurementmore » of thermal neutron capture gamma rays; /sup 231/Th energy levels from neutron capture gamma ray and conversion electron spectroscopy; new measurements of conversion electron binding energies in berkelium and californium; nuclear level densities; relative importance of statistical vs. valence neutron capture in the mass-90 region; determination of properties of short-lived fission products; fission yield of /sup 87/Br and /sup 137/I from 15 nuclei ranging from /sup 232/Th to /sup 249/Cf; evaluation of charged particle data for the ECPL library; evaluation of secondary charged-particle energy and angular distributions for ENDL; and evaluated nuclear structure libraries derived from the table of isotopes. (GHT)« less