BEATRIX-II, phase II: Data summary report

Abstract

This report was prepared as an account of work sponsored by an agency of the United States Government Neither the United States Government nor any agency thereof, nor any of their employees, make any e t y , exprers or implied, or assums any legal liability or rrsponsiiility for the accuracy, completeness, or usefulness of any information, apparatus, pmduct, or process disdosed, AbstractThe BEATRIX-I1 experimental program was an International Energy Agency sponsored collaborative effort between Japan, Canada, and the United States to evaluate the performance of ceramic solid breeder materials in a fast-neutron environment at high burnup levels. This report addresses the Phase I1 activities, which included two in situ tritium-recovery canisters: temperaturechange and temperature-gradient. The temperatiire-change canister contained a Li20 ring specimen that had a nearly uniform temperature profile and was capable of temperature changes between 530 and 640°C. The temperature-gradient canister contained a LizZr03 pebble bed operating under a thermal gradient of 440 to 1100°C. Postirradiation examination was carried out to characterize the Phase 11 in situ specimens and a series of nonvented capsules designed to address the compatibility of beryllium with lithium-ceramic solid-breeder materials.The results of the BEATRIX-11, Phase 11, irradiation experiment provided an extensive data base on the in situ tritium-release characteristics of Li20 and Li2ZrOg for lithium burnups near 5%.The composition of the sweep gas was found to 'be a critical parameter in the recovery of tritium from both Li20 and Li2ZrO3. In general, increasing the amount of hydrogen in the sweep gas resulted in a transient tritium recovery peak indicative of a decrease in tritium inventory in the specimen. The ability of the Phase 11 temperature-change canister to vary temperature between 530 and 630°C indicated that increasing temperature resulted in. transient tritium-recovery peaks whose magnitude and duration were indicative of a relatively small tritium inventory in the Phase 11 Liz0 ring specimen at these temperatures. Throughout the Phase 1 1 irradiation, the centerline temperature of the Li2ZrOg specimen was nearly constant, inferring that the pebble bed remained physically the same throughout the irradiation.Tritium inventories measured during postirradiation examination confirmed that Li20 and . Li2ZrOg exhibited very low tritium retention during the Phase 11 irradiation. The tritium inventories .in Li2ZrOg after Phase 11 tended to be larger than those found for Li2ZrOg in other in situ experiments, but the larger values may reflect the larger generation rates in BEATRIX-II.A series of 20 capsules was irradiated to determine the compatibility of lithium ceraniics and beryllium under conditions similar to a fusion blanket. The lithium ceramics (Li20, Li2ZrO3, LiA102, and Li4SiO4) in contact with beryllium resulted in no observable chemical interaction for lithium burnups up to 4% and irradiation times up to 500 effective full-power days....

Ceramic breeder materials: Status and needs

“…The liberation of tritium from neutron-irradiated lithium ceramics involves the diffusive motion of the tritium atom within the solid and its subsequent release from the ceramic surface [37][38][39][40][41]. It is important to distinguish the rate-controlling step contributing to tritium release.…”