The air purge method is applied to measure a liquid level and its density of a radioactive solution in a tank in the okai reprocessing pla nt. In this method, air purge tubes soaked in nitric acid solution are often blocked bypositing salt of nitrate. Dried air is usually use d for the air purge system and this can be one of the reasons for enerating salt on the tube point. Therefore, a series of experiment usin g a humidifier to humidify the air has been erformed to prevent the blocking with salt, and the...
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Preventive countermeasure of air purge tube blocking using a humidifierin the Tokai Reprocessing Plant

1. 緒言平成21年4月に確認された東海再処理施設の海中放 出設備の漏えい事象は、漏えい箇所が海底埋設の放出 管であった。漏えいの原因は、放出管の施工時に損傷 し、経年変化として損傷箇所に電気防食で発生した水 素が影響したことで水素脆性割れが起こり、き裂が発 生、さらには水素誘起割れによりき裂が進展し貫通し たことによるものと推定した。損傷箇所に水素脆性割れが生じる原因となった水素 は電気防食によるものであり、このときの防食電位と 水素発生の関係等の調査を行った。この結果、損傷が 素が影響したことで水素脆......
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Liquid leakage from the sea release pipe of the Tokai reprocessing plant estigation into the cause of the leak (3): Preventive measures against recurrences and the management metho - Investigation into the cause of the leak (3): Preventive measures against recurrences and the management method

At the Tokai reprocessing plant, release of the low radioactive waste liquid to the ocean is carried out using sea release facilities. It was found that there was a leak point on the sea release facilities. Therefore, surveillance and confirmation were performed and the leak point was identified. The leak part was cut and the part was then collected to investigate the cause of the leak. As a result, it was estimated that the leak oc curred after the pipe was mechanically damaged and a successive metallurg...
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Liquid leakage from the sea release pipe of the Tokai reprocessing plant -Summary of ocean-releasing facilities and the leak phenomenon -

A leakage was found on the sea release pipe of the Tokai reprocessing plant The leak point was discovered in a part buried in the sea floor The damaged part was cut and was collected, and investigation into the cause was subsequently carried out As a result, external force and hydrogen embrittlement were estimated to be the cause that produced a crack on the pipe As restoration of the leak part, a construction method using a coupling technique was proposed considering steady sealability on the restore...
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Liquid leakage from the sea release pipe of the Tokai reprocessing plant- Restoration of the leak point at the see release pipe --

There are plural facilities having a radiation controlled area in the Tokai reprocessing plant, and an interruptible power supply system which considered a blac kout is necessary for the power supply to eachility from the viewpoint of radiological management and nuclear material containment. In addition, at the ne of th e power supplying abnormality, intelligence gathering is necessary for prompt measures and toration. In this report, the intensive monitoring system, which aime d for the unification of the...
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The construction of an intensive monitoring system for power supply stations in the Tokai reprocessing plant