Fabrication and operation of HFIR-MFE-RB spectrally tailored irradiation capsules

The objective of this work is to fabricate and operate irradiation capsules for irradiating magnetic fusion energy (MFE) candidate first-wall materials in the High Flux Isotope Reactor (HFIR) removable beryllium (RB*) positions. Fabrication and operation of four HFIR-MFE RB* capsules (60, 200, 330, and 400 C) to accommodate MFE specimens previously irradiated in spectrally tailored experiments in the ORR are proceeding satisfactorily. With the exception of the 60 C capsule, where the test specimens are in direct contact with the reactor cooling water, specimen temperatures (monitored by 21 thermocouples) are controlled by varying the thermal conductance of a thin gas gap region between the specimen holder and containment tube. Irradiation of the 60 and 330 C capsules was started on July 17, 1990. As of March 31, 1992, these two capsules had completed 17 cycles of their planned 22-cycle (formerly 28-cycle) irradiation to a damage level of approximately 17.5 displacements per atom (dpa). Assembly of the 200 and 400 C capsules is scheduled for completion in August, 1992; operation of these two capsules will follow the first two (60 and 330 C)