Reconstructing nuclear histories: a field study

Reconstructing how much fissile material was produced in nuclear facilities could become a key element in the verification of future arms control or disarmament agreements. The past production of plutonium can be modelled with reactor simulations, using information on both reactor design and operating history. That information is typically provided by the inspected state and must be independently verified. In a first step, the available documentation of the reactor program can be thoroughly examined, for instance by studying its self-consistency. In a second step, forensic measurements, e.g., of samples from inside the reactor core, can be used to verify the documentation. For both these methods, questions remain, especially related to the practical application: How can one handle the potentially large amount of archived operating-history documentation? How to deal with gaps in the documentation? How can the document analysis be effectively combined with forensic measurements? To answer those questions, systematic approaches need to be developed. We explore a real-world scenario with the former nuclear research program from Karlsruhe, Germany, for which we gained access to the archives containing documentation of the operational histories and facility designs. The nuclear research program included a pilot reprocessing plant and the heavy water reactors FR-II and MZFR, which were operated between 1961 and 1984. While the program was used for civilian purposes only, the fact that the reactors were moderated by heavy water makes them ideal candidates for this study as this type of reactor is elsewhere used to produce plutonium. This presentation will show first results on how the documentation of a past nuclear reactor program can be used to develop and test approaches to nuclear archaeology.