Year
2014
Abstract
Fukushima Daiichi Nuclear Power Plants (1F) were struck by the earthquake and tsunami on March 11, 2011 and meltdown of the reactor cores of Units 1-3 occurred. Japan decided to recover fuel debris safely and to account adequately for the nuclear material in the fuel debris starting in 2020. Fuel debris contains minor actinides, fission products and structural materials, etc. These materials make it difficult to quantify the nuclear material in the fuel debris by the existing measurement technologies. In order to survey technologies to be developed for nuclear material quantification of fuel debris at 1F, Japan Atomic Energy Agency (JAEA) and United States Department of Energy (DOE) started collaborative research from November 2012. Under the collaborative research, three Working Groups, Gamma Working Group (GWG), Neutron Working Group (NWG) and Source Term Working Group (STWG) were established. The roles of GWG and NWG were for each to identify up to three measurement systems respectively that could be studied further for possible implementation at 1F. The role of STWG was to provide the GWG and NWG an initial estimate of the source term based on their research. Taking into account system cost, system size, measurement time, development period, and potential for applicability to fuel debris, GWG members have identified recommended combinations among the gamma technologies, some of which are supplemented with neutron measurement technologies. The evaluation was mainly carried out by literature search. This paper provides the recommendations of the GWG for measurement systems based mainly on gamma measurement technologies for nuclear material accountancy of fuel debris at 1F.