FABRICATION OF 12% ²⁴⁰PU CALORIMETRY STANDARDS*

Throughout the DOE complex, laboratories are performing calorimetric assays on items containing high bum-up plutonium. These materials contain higher isotopic range and higher wattages than materials previously encountered in vault holdings. Currently, measurement control standards have been limited to utilizing 6% 240Pu standards. The lower isotopic and wattage value standards do not compliment the measurement of the higher burn-up material. Participants of the Calorimetry Exchange (CALEX) Program have identified the need for new calorimetric assay standards with a higher wattage and isotopic range. This paper will describe the fabrication and verification measurements of the new CALEX standard containing 12% 240Pu oxide with a wattage of approximately six to eight watts.