“Discrete exposure savings listed at 41 mrem [410 μSv]. However, the shielding also provided critical radiological configuration control during this high profile first time evolution.”
-Timothy Bigler, Point Beach Nuclear
Point Beach was set to perform a Vertical Storage Cask inspection and required shielding for the VCC/MSB gap created when the shield ring was removed. The need for this shielding became an urgent issue with the inspection rapidly approaching, but NPO was able to design, manufacture, and deliver an effective shielding system in under two weeks. The resulting shielding featured 1″ (25 mm) thick curved layers of borated polyethylene and T-Flex® Tungsten to fit the gap. This shielding also featured steel handles that were tall enough to ensure no piece would accidentally fall into the gap itself and create and FME concern.
The shielding was estimated to provide 63% gamma and 75% neutron reduction. The overall effectiveness ended up being greater than originally estimate, producing dose rates with an average of 95% reduction. Overall, 41 mRem (410 μSv) was saved over the course of the inspection.
