Estimation of Sm-151 from measured Pm-147

Technical Report · Thu Aug 25 04:00:00 EDT 1988

OSTI ID:7026376

Dewberry, R A

The attached procedure is a derivation to estimate Sm-151 activity in DWPF glass product and glass melter feed samples. Sm-151 is one of the radioactive fission product species in the glass product which will contribute greater than 0.05% of the total activity, and thus its content must be reported. We will not routinely perform elemental separation of Sm from Pm in the DWPF samples as they are received, but rather will report the Sm-151 activity as a constant fraction of the measured Pm-147 activity. Since Sm-151 decays with a 76 kev ..beta..-endpoint energy and is difficult to chemically separate from Pm, the direct measurement of Sm-151 content is technically very difficult. This document derives the multiplicative constant which will be used to estimate Sm-151 content from measured Pm-147 content, and the error which will be reported for each sample. A rigorous separation of Sm from Pm will be performed on selected samples to assure that the routine DWPF samples do not contain Sm-151/Pm-147 relative activities which deviate from the relationship derived here. Since both Sm-151 and Pm-147 can both be considered to be direct fission products with no other production pathway contributing, their relative production rate can be estimated from the U-235 fission yield curve. Ignoring burnup by neutron capture in a reactor irradiation, the relative activities of the two species is a function only of the decay rates. Sm-151 activity can then be estimated from measured Pm-147 activity, if some knowledge of irradiation time and decay time is available. The attached procedure explains the derivation and discusses the error obtained in the estimation.

• Research Organization: Savannah River Lab., Aiken, SC (USA)
• DOE Contract Number: AC09-76SR00001
• OSTI ID: 7026376
• Report Number(s): DPST-88-796; ON: DE89001411
• Country of Publication: United States
• Language: English

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