Dose-reduction improvements in storage basins of spent nuclear fuel

Spent nuclear fuel (SNF) in storage basins at the Hanford Site has corroded and contaminated basin water which has leaked into the soil; the fuel has also deposited a layer of radioactive sludge on basin floors. The SNF is to be removed from the basins to protect the nearby Columbia River. Because the radiation level is high, measures have been taken to reduce the background dose rate to as law as reasonably achievable (ALARA) to prevent radiation doses from becoming the limiting factor for removal of the SNF in the basins to long-term dry storage. All activities of the SNF project require application of ALARA principles for the workers. On the basis of these principles, dose-reduction improvements have been made by first identifying radiological sources. Principal radiological sources in the basin are basin walls, basin water recirculation piping, and equipment. Second. dose-reduction activities focus on cleaning and coating basin walls, raising the water level, hydrolasing piping, and placing lead plates. In addition, the transfer bay floor will be refinished to make decontamination easier and reduce worker exposures in the radiation field, The background dose rates in the basin will be measured before each task commences and after it is completed; these dose reduction data will provide the basis for cost-benefit analysis.