The First-In-A-While Chemical Decontamination in Canadian CANDU Reactor

Abstract

Reducing dose rates for the Major Component Replacement (MCR) outage was a critical step in extending Bruce Power Unit 3 operating life as the estimated high collective worker dose would directly impact the ability to work efficiently with qualified resources. Majority of the dose came from the Reactor Inlet Headers (RIH) and the inlet feeder pipes, as these components had the most magnetite deposits containing Co-60, the main dose contributor. The first-in-a-while (FIAW) chemical decontamination of Canadian CANDU was performed by the Framatome designed, tested and operated Canadian Automated Modular Decontamination Appliance (CAMDA), used in support of Bruce Power’s Unit 3 campaign. The selected chemical technology was CAN-DEREM™, a dilute chemical decontamination process utilizing ion exchange for regeneration. The flow path through the Heat Transport (HT) System utilized the Maintenance Cooling System with the HT System at low-level drain state, excluding the pre-heaters and steam generators. This paper provides a CAMDA design overview, its improved functionalities from previous Canadian CANDU decontamination, and summary of the steps in the chemical decontamination process. Campaign summary is provided where the target dose reduction factor of 5 was achieved and the total amount of ion exchange resin usage was below target.