Neutron source and field characteristic measurements for JAERI/USDOE Phase-II experiments on fusion blanket neutronics

Abstract

Measurements on the D-T source and field characteristics were carried out to provide data for verifying the calculation of the source term used in subsequent analysis for Phase-II experiments of the JAERI/USDOE collaborative program on fusion blanket neutronics. Neutron flux distributions inside of the Phase-II closed system were measured by activation foils distributed on the Li 2 CO 3 enclosure as well as on the front surface of Li 2 O testing zone. The multi-foil activation technique, a small sphere NE213 spectrometer, and a proton recoil counter were applied to measure the neutron spectrum on the front face of the testing zone. The results showed good symmetry of the neutron flux distribution on the surface of the test region as well as in most parts of the cavity. It was proved that the Li 2 CO 3 enclosure with polyethylene served as a good insulator between fields inside and outside of the system. As an attempt, the neutron source position and strength were estimated utilizing the mapped activation reaction rates. Values estimated were in good agreement with the actual source position and the source strength determined by the associated a particle counting method. It was suggested that this approach based on the foil activation technique is promising for the determination of D-T source strength and mean source position in a plasma.