Development of Pu standard material Preparation and Characterization Technique in Japan

In order to obtain reliable accountancy analysis results, the Isotope Dilution Mass Spectrometry (IDMS) method is applied at most of the plutonium handling nuclear facilities in Japan. The reference materials, referred to as Large Size Dried spikes (LSD spikes), were developed to allow facilities, regulatory and safeguards organizations to accurately measure and quantify a variety of nuclear materials under potentially difficult handling or measurement conditions. Because of expected difficulties in a stable long term supply of low burn-up plutonium reference materials, which are the main source of plutonium for LSD spikes preparation, the Japan Atomic Energy Agency (JAEA)’s Plutonium Fuel Development Center (PFDC) decided to evaluate the possibility of using domestically available MOX powders as a plutonium source material for LSD spikes. Therefore, PFDC started to prepare and characterize plutonium reference materials that are suitable for source of LSD spikes in cooperation with the US Department of Energy’s New Brunswick Laboratory (NBL), sponsored by the DOE National Nuclear Security Administration’s International Safeguards Engagement Program. At the PFDC, the plutonium contained in MOX powders was separated, purified and characterized to produce plutonium standard material, referred to as MOX-Pu. The latest MOX-Pu standard material preparation was started in 2011 and the characterization analysis, data evaluation, and uncertainty estimation were completed. The intercomparison for verification of this MOX-Pu characterized value was organized and confirmed with all participating laboratories and experts of the safeguards measurements. The detailed preparation procedure and characterization of the MOX-Pu, and results of intercomparison for verification are presented.