Design of a Subcritical Assembly for Conducting Neutron Activation Analyses in the Field
| Autor: | James Weldy, Mark S. Jarzemba, English C. Pearcy |
|---|---|
| Rok vydání: | 1999 |
| Předmět: |
Neutron transport
Materials science 010308 nuclear & particles physics 0211 other engineering and technologies 02 engineering and technology Natural uranium 01 natural sciences Subcritical reactor Neutron temperature Nuclear physics Nuclear Energy and Engineering 0103 physical sciences Neutron cross section Neutron Research reactor 021108 energy Neutron activation |
| Zdroj: | Nuclear Science and Engineering. 131:275-281 |
| ISSN: | 1943-748X 0029-5639 |
| DOI: | 10.13182/nse131-275 |
| Popis: | Two subcritical assemblies (consisting of a subcritical reactor plus a neutron emitter such as 252 Cf) designed for conducting neutron activation analyses in the field are described. The size of the assemblies has been minimized (compared to conventional, graphite-moderated assemblies) to allow for field portability. Although less powerful than using a research reactor as the source of neutrons, these assemblies will provide an adequate source of neutrons for detecting gold concentrations in rock or soil samples down to the limits of economic importance. Using afield-portable source of neutrons eliminates the need for shipping samples back to the reactor for analysis, which may be important for reasons of sample security and measurement turnaround time. The two subcritical assemblies are composed of natural uranium metal as the multiplying material and high-density polyethylene as the moderator, and they have k eff approximately equal to 0.8 for the smaller assembly (∼692-kg assembly mass) and 0.9 for the larger assembly (∼3059-kg assembly mass). The larger assembly was found to be more desirable from a neutronics standpoint; however, it may be too massive to maintain field portability. It was found that the optimal location for the irradiation facility (a 4.0-cm-high, 2.0-cm-diam right cylinder) in the subcritical assemblies is the grid location as close to the neutron emitter location as possible. It was also found that the total, epithermal plus thermal (i.e., neutron energy |
| Databáze: | OpenAIRE |
| Externí odkaz: |
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