Hanford Single-Pass Reactor Fuel Storage Basin Demolition
J. A. Armstrong
The Hanford fuel storage basins (FSB) served as underwater collection, storage, and transfer facilities for irradiated fuel elements discharged from the reactors. The FSB is approximately 22 m by 25 m by 6.1 m (72 ft by 82 ft by 20 ft) deep. The deactivation of the FSBs began in the 1970s. Deactivation involved pumping water out until 0.6 m (2 ft) of water and sediment remained, placing material (e.g. fuel baskets, fuel spacers, process tubes, wooden floor decking, and handrails) in the FSB and then backfilling with fine streambed sand. It was also suspected that spent nuclear fuel (SNF) elements remained in the FSB at the time of deactivation. Demolition of the FSB offered many unique radiological control challenges and innovative approaches to demolition. Demolition was performed in primarily two stages. Stage I involved removing the top 5.3 m (17.5 ft) of fill material and Stage II involved removing the bottom 0.8 m of fill material. Based on characterization and historical data of the upper fill material, it was possible to perform Stage I demolition using modern heavy equipment and radiological instrumentation. Stage II, however, had the possibility of containing several SNF element fragments, several hundred fuel baskets and spacers, and no Stage II characterization data were available. This paper describes how total effective dose equivalent and contamination were controlled, how the use of a remote operated excavator was employed to remove high dose rate material, and how wireless technology was used to monitor changing radiological conditions.
This abstract was presented at the 35th Annual Midyear Meeting, "Decommissioning and Environmental Restoration", Controlling Dose 2 Session, 2/17/2002 - 2/20/2002, held in Orlando, FL.