Nuclear Archaeology for Heavy Water Reactors to Distinguish Plutonium and Other Isotope Production Modes

Several nuclear archaeology techniques have been proposed to determine historic plutonium production indedicated production reactors. Some of these techniques have been successfully demonstrated, inparticular, those using the isotope-ratio method in graphite-moderated production reactors. More recently,similar techniques have also been proposed to monitor plutonium production in operating reactors, whichcould complement traditional safeguards approaches. These methods rely on sampling materials from thereactor core or specially designed monitor tags that would be inserted into the core, to examine suitedisotopic ratios. These would be used to assess the cumulative neutron fluence, quantifying the amount ofplutonium produced. However, some production reactors can be used to produce other isotopes thanplutonium, such as tritium or other (medical isotopes). If a reactor production mode has been declared tobe a tritium production mode, it must be verified that this was the case and that the reactor was not used toproduce plutonium instead. In this paper, we examine to which extent nuclear archaeology techniques canbe extended to detect different modes of reactor operation such as tritium versus plutonium production.