The Contribution of and Uncertainty Associated with Self-Multiplication when Assaying Plutonium in Waste by Passive Neutron Coincidence Counting
- Canberra Industries Inc., Meriden, CT (United States)
When Pu is present in waste items as lumps, the Reals neutron coincidence signal may be bolstered by virtue of self induced fission events. This gives rise to a positive bias to the assay result and leads to a one sided contribution to the total measurement uncertainty. In the general it is not feasible to determine to magnitude of this effect experimentally and allowance for it must therefore be estimated using separate ad hoc rules. In this paper we to develop a simple model for the self-multiplication enhancement in small lumps allowing the importance of the effect in waste assay to be quantified. In addition, an approach is suggested for how to propagate an uncertainty contribution in to the final result. In conclusion: By introducing a generic scheme we have taken the first pragmatic steps to accounting for multiplication effects in the TMU in the determination of Pu-240 eff-mass by PNCC in waste. We have used a simple physical model to derive the underlying relationships needed. A first order expression suitable for small, dense lumps was set out, primarily for instructive reasons, but this is not a restriction of the method. The method is readily scaleable to material of different isotopic composition, density and a. Numerical parameters suitable for practical applications have been established and we feel the approach is fit for the intended purpose reflecting operational experiences and the general state of knowledge of waste items. (authors)
- Research Organization:
- WM Symposia, 1628 E. Southern Avenue, Suite 9 - 332, Tempe, AZ 85282 (United States)
- OSTI ID:
- 21326145
- Report Number(s):
- INIS-US-10-WM-08386; TRN: US10V0581067510
- Resource Relation:
- Conference: WM'08: Waste Management Symposium 2008 - HLW, TRU, LLW/ILW, Mixed, Hazardous Wastes and Environmental Management - Phoenix Rising: Moving Forward in Waste Management, Phoenix, AZ (United States), 24-28 Feb 2008; Other Information: Country of input: France; 20 refs
- Country of Publication:
- United States
- Language:
- English
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