Tritium Handling Experience in 165MWE Power Generating Station, Fugen

Two heavy water upgraders have been developed and operated in the Fugen Nuclear Power Station to keep the isotopic purity of the moderator around 99.7 wt% and to recover tritium from the degraded heavy water. One of the upgraders is a combined electrolysis catalyst exchange (CECE) process that consists of 90 stages of catalytic water-hydrogen isotopic separation units. This upgrader treats 10 m³/y of degraded heavy water, produces reactor grade heavy water, and lowers the tritium and heavy water in the waste to <3700 Bq/cm³ and <0.1wt%, respectively. The other one is simple electrolysis system and terminated its operation in 1999. Heavy water recycle is completed with these two upgraders in the Fugen. A filter-separation-type tritium monitor was developed. Daughter species of Rn-Tn are separated from sampled gas with hollow fiber filters made of perfluorosulfuric-acid resin before introducing to an ionization chamber. The detection limit of the monitor is 7.4E-03 Bq/cm³-air. The upgraders and monitor contributed to control airborne and liquid tritium releases from the Fugen lower than 18 TBq/y and 11 TBq/y, respectively.