Critical mass of {sup 237}Np

Journal Article · Mon Dec 01 04:00:00 EST 1997 · Transactions of the American Nuclear Society

OSTI ID:552498

Sanchez, R ^[1]

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1. Los Alamos National Lab., NM (United States)

The criticality of {sup 237}Np is governed by several factors. For instance, it is well known that nuclides with an even number of neutrons, such as {sup 237}Np, exhibit a sharp threshold in their fission cross section. For {sup 237}Np, the threshold occurs at {approximately}500 keV. Above this neutron energy, the fission cross section is comparable to that of {sup 235}U. On the other hand, below this energy threshold, the fission cross section is quite low. Thus, the criticality of {sup 237}Np can only occur in a fast neutron spectrum. Another factor that affects the critical mass of this element is the inelastic scattering cross section of {sup 237}Np. A low inelastic scattering cross section in a fast spectrum will enhance criticality since fewer neutrons will scatter below the fission threshold where they will be unable to cause more fissions. The purpose of the experiments described herein is to estimate the critical mass of {sup 237}Np based on {sup 237}Np worth measurements performed in the Flattop assembly.

• OSTI ID: 552498
• Report Number(s): CONF-971125--
• Journal Information: Transactions of the American Nuclear Society, Journal Name: Transactions of the American Nuclear Society Vol. 77; ISSN 0003-018X; ISSN TANSAO
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
66 PHYSICS
CRITICAL MASS
CRITICALITY
INELASTIC SCATTERING
NEPTUNIUM 237
NEUTRON SPECTRA