Moderator design studies for a new neutron reference source based on the $$\mathrm{D}$$–$$\mathrm{T}$$ fusion reaction

Journal Article · Wed Feb 03 00:00:00 EST 2016 · Radiation Physics and Chemistry (1993)

DOI:https://doi.org/10.1016/j.radphyschem.2016.02.004· OSTI ID:1326139

Mozhayev, Andrey V. ^[1]; Piper, Roman K. ^[1]; Rathbone, Bruce A. ^[1]; McDonald, Joseph C. ^[1]

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1. Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)

The radioactive isotope Californium-252 (²⁵²Cf) is relied upon internationally as a neutron calibration source for ionizing radiation dosimetry because of its high specific activity. The source may be placed within a heavy-water (D₂O) moderating sphere to produce a softened spectrum representative of neutron fields common to commercial nuclear power plant environments, among others. Due to termination of the U.S. Department of Energy loan/lease program in 2012, the expense of obtaining ²⁵²Cf sources has undergone a significant increase, rendering high output sources largely unattainable. On the other hand, the use of neutron generators in research and industry applications has increased dramatically in recent years. Neutron generators based on deuterium-tritium (D-T) fusion reaction provide high neutron fluence rates and, therefore, could possibly be used as a replacement for ²⁵²Cf. To be viable, the 14.6 MeV D-T output spectrum must be significantly moderated to approximate common workplace environments. Here this paper presents the results of an effort to select appropriate moderating materials and design a configuration to reshape the primary neutron field toward a spectrum approaching that from a nuclear power plant workplace. A series of Monte-Carlo (MCNP) simulations of single layer high- and low-Z materials are used to identify initial candidate moderators. Candidates are refined through a similar series of simulations involving combinations of 2 to 5 different materials. The simulated energy distribution using these candidate moderators are rated in comparison to a target spectrum. Other properties, such as fluence preservation and/or enhancement, prompt gamma production and other characteristics are also considered.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
• Sponsoring Organization: USDOE Laboratory Directed Research and Development (LDRD) Program
• Grant/Contract Number: AC05-76RL01830
• OSTI ID: 1326139
• Report Number(s): PNNL-SA-113429
• Journal Information: Radiation Physics and Chemistry (1993), Vol. 123; ISSN 0969-806X
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
D–T generator
Cf-252
neutron calibration
workplace neutron spectra
dosimetry