TRIO experiment

Abstract

A~l REFERENCES R-l ACKNOWLEDGMENTS a SECTION I INTRODUCTION I. INTRODUCTION Lithium aluminate, LiA10 2 > is representative of a group of ceramics, called the "Solid Breeders/ , that are candidate materials for use as the tritium breeding medium in fusion reactors. In the past several years, a number of conceptual blanket designs for fusion reactors have used solid breeders, and the data base has been reviewed. Although the data base is limited, experimental programs are in progress and more results are becoming available.25-39 Tne so i±& breeders include Li 2 O, LiA10 2 , LL 2 Zr0 3 , Li^SiOjj, and Li 2 Si0 3 . The ternary oxides, in general, have much better chemical and thermophysical stability than Li 2 O, but owing to its high lithium atom density, Li 2 O has better tritium breeding potential. The TRIO experiment involved the irradiation of IAAIO2 in the Oak Ridge Research Reactor (ORR) under well-defined conditions of temperature, neutron flux, sweep gas flow, and sample configuration. Lithium aluminate was selected for the experiment because of its attractive properties (discussed later). Tritium, in its various chemical forms (and other gases evolved from the LiA10 2 during irradiation), was moved by a sweep gas to an analytical train in which measurements on the composition of the effluent were performed. 1-1 SECTION II PURPOSE II-l determine values of heat transfer coefficients and thermal conductivity of the LiA10 2 and to access the effects of radiation damage upon these values* (4) Measure tritium permeation through primary cladding. A measurable quantity of tritium may permeate through the primary cladding into the gas gap of the breeder capsule. This tritium which permeates will be collected and assayed. (5) Investigate the form of the tritium species (e.g., 'lyJrT, ratio) in the sweep gas stream. The amount of tritium released in each chemical form is to be quantitatively determined. (6) Establish the methodology for in-pile testing. This experiment is the first truly comprehensive test of in-situ tritium recovery from solid breeders. Thus, a methodology for this kind of test will be developed. (7) Measure radioactive species in the sweep gas stream. Certain impurities in the LiA10 2 (e .g., uranium, potassium, sodium, chlorine, etc.) produce volatile radionuclides during irradiation. These will be quantified to ensure that tritium monitoring is not affected. In addition, transport data on other species (mostly nobel gases), which may provide some insight into transport of helium, will be obtained.

UNCLASSIFIED TPBAR RELEASES, INCLUDING TRITIUM TTQP-1-091 Rev 14

“…Tritium release from extracted TPBARs in storage will not exceed 1% of the declared post-extraction residual tritium (Clemmer et al 1984;and Johnson et al 1976). …”

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.…”

Experimental method for investigating helium effects in irradiated vanadium

“…The helium generation rate in vanadium can be conveniently varied over a large range to obtain desired values by adjusting the 6 Li enrichment and/or the precharge tritiim concentration.…”

“…Tritium generation ra^es in lithium can be accurately calculated by current neutronic and dosimetry methods [6]. The total tritium generation rate from the ^Li(n,o)T reaction can be varied by over two orders of magnitude by adjusting the ^Li enrichment (<1 to 90%).…”