Basic experiment on fire-extinguishing of lithium

In order to obtain the engineering data of the lithium target system with is the neutron source of the International Fusion Material Irradiation Facility (IFMIF), design and fabrication of the liquid lithium test loop are being carried out under the Engineering Validation and Engineering Design Activity (EVEDA). Since lithium is specified as a dangerous substance by a Japanese law, the countermeasure against lithium combustion incident is indispensable. This report summarizes the results of basic experiment on lithium fire-extinguishment. In this experiment, the fire-extinguishing behavior of the fire extinguishers to the lithium was experimentally confirmed, and the fire extinguisher for the liquid lithium test loop is proposed. In addition, the fire-extinguishing performance for the determination of the amount of dispositions of the fire extinguisher was experimentally estimated. The major results are as follows: (1) The fire-extinguishing performance of three kinds of fire extinguishers - dryness sand, pearlite and Natrex-L produced by Nippon Dry Chemical Co. Ltd. - to combustion lithium (about 250g) was examined. The fire-extinguishing behavior by Natrex-L was most stable, and no chemical reaction with lithium was observed visually. (2) Effect of the lithium depth on the fire-extinguishing performance of Natrex-L was investigated under the definite area of the lithium combustion surface. It was obtained that the volume (thickness) of fire extinguisher necessary for the fire-extinguishing increased as the lithium depth increased. In this experimental condition (combustion area: 270cm2, lithium depth: 1-2 cm), the minimum thickness of the fire extinguisher was 1.5 times the depth of lithium. (author)