Evaluation of the Shielding Design of the Primary Cooling System in the Prototype FBR Monju

Abstract

As part of the start-up tests of the prototype fast breeder reactor Monju, the activities of 24Na and 22Na, which are generated by neutron irradiation of the primary sodium, were measured. The gamma-ray dose rates resulting from these nuclides inside the primary heat transport system cell were also measured. This paper presents an outline of the measurement methods and results, the design requirements and the design margins, which were evaluated by comparing the measurements with the calculations based on FBR shielding analysis methods.