Patent Number: 
Section: claims

1. A nuclear reactor fuel integrity monitor comprising:a γ-ray detector which detects γ-ray of a specific radionuclide of a subject measurement medium of a nuclear reactor and includes a Ge-semiconductor detector;a sample container which retains the subject measurement medium therein and includes a recess portion into which the γ-ray detector is inserted;a cooling device which cools the γ-ray detector to a temperature as low as that of liquid nitrogen;a degassing device which removes radioactive argon from the subject measurement medium; anda measurement control device which performs a control so that a predetermined amount of the subject measurement medium is introduced into the sample container, and calculates a concentration of the specific radionuclide from γ-ray data per each unit time detected by the γ-ray detector and a volume of the subject measurement medium introduced into the sample container,wherein the sample container is disposed in an upper part of the γ-ray detector such that the recess portion encloses the upper part of the γ-ray detector, andwherein the cooling device is disposed at a bottom of the γ-ray detector. 2. The nuclear reactor fuel integrity monitor according to claim 1, whereinthe subject measurement medium is a coolant of the nuclear reactor and the specific radionuclide is radioactive iodine. 3. The nuclear reactor fuel integrity monitor according to claim 2, whereinan inlet side of the sample container is provided with an activated alumina column, andthe coolant passing through the activated alumina column is introduced into the degassing device.