In situ tritium from Li{sub 2}O and Li{sub 2}ZrO{sub 3} irradiated in a fast neutron flux: BEATRIX-II, Phase 1 and 2

Abstract

BEATRIX-I1 was an in situ tritium recovery experiment designed to characterize the behavior of lithium ceramics irradiated to high burnup in a fast neutron flux. This in situ tritium recovery experiment provided data on the performance of Li20 and Li,ZrO, under irradiation conditions covering a range of sweep gas compositions and temperatures. The experiment consisted o f two separate irradiation cycles which in turn included two vented tritium recovery canisters each. while Phase I1 operated for 203 EFPD of irradiation. resulted in lithium burnups in excess of 4%. Phase I operated for 300 Effective Full Power Days (EFPD) Both Phase I and I1 The tritium recovery behavior of Li,O and Li ZrO, was characterized using temperature transients, sweep gas composition changes and reactor power changes to effect changes in the tritium inventory. These parameter changes indicated that increasing temperatures or increasing concentrations of hydrogen in the sweep gas, in general, resulted in a decrease in the tritium inventories in the lithium ceramic. The results of these parameter changes allow comparison not only in the tritium recovery behaviors for Li,O versus Li,ZrO, but between different Li,O microstructures. The high neutron flux level in FFTF resulted in high tritium generation rates which combined with a responsive tritium measurement system allowed detailed observations on the tritium recovery behavior of Li,O and Li,ZrO,. During the course o f the experiment a number o f observations were made which did not appear consistent with a simplified view of the tritium recovery behavior of these materials. These observations included small negative tritium recovery peaks preceding the typical primary positive peaks; and, for specific temperature ranges, changes in tritium inventory which where opposite to the characteristic expected changes. extensive BEATRIX-I1 database o f tritium recovery results provides an opportunity for a better understanding of the tritium release behavior of these two candidates for a fusion solid breeder blanket. This anomalous behavior together with the (a) Pacific Northwest Laboratory is operated for the U. S. Department o f Energy by Battell e Memori a1 Institute under Contract DE-AC06-76RLO 1830,

Surface desorption and bulk diffusion models of tritium release from Li2TiO3 and Li2ZrO3 pebbles

“…[14], Section 13.3). Namely, by setting its width to a few times (1)(2)(3)(4)(5) that frequency at which the power spectrum of the input signal drops by three orders of magnitude from the zero frequency level. The interval to the stop band is set to 0.05-0.2 times the sampling frequency, and the number of taps is set around 105.…”

“…This topic has been the object of various studies, mainly, by means of in-core, continuous cycle irradiation-release experiments [3,4], and by sealed capsule irradiation, followed by out-of-pile release under controlled temperature and purge gas conditions [5] (batch experiments). The experiments in the present work have been conducted in the second fashion.…”

DIFFUSION OF TRITIUM GENERATED IN LITHIUM METATITANATE Li2TiO3 DURING THERMAL NEUTRON IRRADIATION IN REACTOR WWR-K

“…Опубликованные данные не позволяют пока чётко ответить на вопрос о роли сопутствующего облучения керамики быстрыми нейтронами и гамма-излучения. В детальном эксперименте Беатрис II [12] не было обнаружено какого-либо изменения ко-эффициента диффузии трития в Li 2 О вплоть до степеней выгорания лития 5%. До сих пор не предложен механизм влияния внешнего облучения на величину коэффициента диффузии трития в литиевых кера-миках.…”