Global Estimation of Potential Unreported Plutonium Production in Thermal Research Reactors

As of November 1993, 303 research nmctom (research, test, training, prototype, and electricity producing) were operational worldwide; 155 of these were in non-nuclear weapon states. 1 Of these 155 research reactors, 80 are thermal reactors that have a power rating of 1 MW(th) or greater and could be utilized to produce plutonium. A previously published study by T. F. Moriarty and V. N Bragin2 on the unreported plutonium production at six research reactors indicates that a minimum reactor power of 40 MW(tb) is required to make a significant quantity (SQ), 8 kg, of fissile plutonium per year by unreported irradiations. As part of the Global Nuclear Material Control Model effort, we determined an upper bound on the maximum possible quantity of plutonium that could be produced by the 80 thermal research reactors in the non-nuclear weapon states (NNWS). We estimate that in one year a maximum of roughly one quarter of a metric ton (250 kg) of plutonium could be produced in these 80 NNWS thermal research reactors based on their reported power output. We have calculated the quantity of plutonium and the number of years that would be required to produce an SQ of plutonium in the 80 thermal research reactors and aggregated by NNWS. A safeguards approach for multiple thermal research reactors that can produce less than 1 SQ per year should be re-visited and criteria adapted to ensure an appropriate degree of safeguards. This investigation should be conducted in association with further developing a safeguards and design information reverification approach for states that have multiple research reactors.