A CHERENKOV THRESHOLD COUNTER USING LIQUID CORE FIBER FOR ESTIMATION OF RADIOACTIVE WASTE INVENTORY

Decommissioning of nuclear power plant will increase a number of radioactive wastes near future. In Japan, some of the radioactive wastes will show high intensity of radiation and must be disposed in underground that deep enough from human activities. Therefore, it is important to estimate the inventory of such intense radioactive wastes. But it is difficult to verify the inventory of such radioactive wastes directly by a radiation counter because its intensity is too high to estimate by conventional pulse counting method In order to verify the inventory of such radioactive wastes directly, we propose a threshold detector with liquid core fiber as a Cherenkov counter which is applicable to high intensity radiation field. As a result of the preliminary experiment using ^<137>Cs and ^<60>Co gamma sources, we have confirmed that the proposal counter worked as the threshold detector. In this paper, we present the principle of this detector and show a preliminary result of detector response to gamma-rays.