A. Dulloo, W. Jester, C. Bleistein
1992
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Journal
Transactions of the American Nuclear Society
Abstract
Lithium hydroxide is used to control the pH of coolant water in the primary loop of pressurized water reactors (PWRs). Natural lithium consists of 93.45 wt% [sup 7]Li and 6.55 wt% [sup 6]Li. However, due to the high thermal neutron cross section of the [sup 6]Li(n,[alpha])[sup 3]H reaction, the LiOH compounds used in PWRs are typically enriched to 99.9 wt% [sup 7]Li to minimize the production of radioactive tritium ([sup 3]H). A simple method to measure the [sup 7]Li content of an enriched LiOH compound has been developed. Enriched LiOH is irradiated in a thermal neutron flux, and its resulting [sup 3]H activity is radioassayed and compared to that of natural LiOH, which has been subjected to an identical irradiation. Since the [sup 3]H activity is a linear function of the [sup 6]Li content of the compound, the percentage of [sup 6]Li in the enriched compound can be calculated based on the well-known [sup 6]Li composition of natural lithium. The percentage of [sup 7]Li in the enriched compound is then readily calculated because the lithium consists only of the [sup 6]Li and [sup 7]Li isotopes. This method has been used to compare the [sup 7]Li contents of three enriched LiOHmore » powders sold by different vendors.« less