Characterization Of The Radiochemical Activity In Candu® Steam Generators

Abstract

The scope of mid-life refurbishment activities at some CANDU® plants includes replacement of the existing steam generators. Shipment of the discarded steam generators for interim storage, intact disposal or for recycling via metal melting requires an assessment of the inventory of radionuclides within the components and also dose rates.

Kinectrics was contracted by Bruce Power to develop radionuclide inventory and dose rate data for steam generators from its four-unit Station A located in Kincardine, Ontario, Canada. Units 1 & 2 are currently being refurbished while Units 3 & 4 are planned for refurbishment in 2016. The scope of the refurbishment activities for all units includes replacement of the existing steam generators. Those from Units 1 & 2 have already been placed into interim storage at the Western Waste Management Facility (WWMF) which is also located on site but operated by Ontario Power Generation.

This paper presents the detailed methodology employed to develop radionuclide inventory and dose rate data for radionuclides within (characterize the steam generators that are) both in-service and out-of-service (in-storage) steam generators. The data were developed as follows: a) archived tube sections from various steam generators were characterized and scaling factors for Difficult-to-Measure radionuclides were derived from the measured data, b) in-situ gamma spectrometry (using germanium and cadmium zinc telluride detectors) and dose rate surveys were performed at various steam generators and c) a detailed assessment of the tritium inventory in various primary and secondary side components was performed.