Conceptual design analysis of 4 K irradiation facility in Korean HANARO research reactor

A conceptual design of a 4 K irradiation test facility has been conducted in support of the International Thermonuclear Experimental Reactor (ITER) magnet development program. A new research reactor designated as HANARO at the Korea Atomic Energy Research Institute has a Cold Neutron Source (CNS) port that is identified to be suitable for the fast neutron irradiation of metals and insulation materials for superconducting magnets at 4 K. A 40 hours of irradiation at full power will produce 2.5 x 1017 n/cm2 of the ITER magnet design neutron fluence with energy above 0.1 MeV. A material testing laboratory of Irradiated Materials Evaluation Facility (IMEF) that is located next to HANARO has been equipped with 77 K test machines and fracture analysis microscopes for radioactive specimens which can be upgraded for 4 K test without any intermediate warming. CNS radiation spectrum determined by Monte Carlo method is found to be more favorable for metal irradiation than for insulation materials with absorbed gamma dose that is 7-10 times the fast neutron dose. A lead-shielded irradiation capsule design with a 1 cm diameter specimen in 3 cm cold-bore diameter and 18 cm height will require about 120 watt cooling capacity at 4.6 K