Exelon Braidwood Station recently saw very good dose reduction with their dry cask campaigns by utilizing NPO T-Flex® Annulus Gap Shielding. This was designed to fit in the annulus gap between the canister and transfer cask and had a fire blanket covering specified by Braidwood. The annulus gap shielding, in addition to more NPO dry cask shielding, made for a near record low dose campaign. Below is the Braidwood shielding survey that compares the annulus gap dose rates and the two types of NPO supplied shielding.
“I cannot express my happiness at the dramatic improvement (from 800mrem/hr-to-500-150 [8,000 μSv/hr to 5,000-1,500 μSv/hr]see attached survey from Braidwood) we have made with the annulus gap shielding recently. The shielding for CPS will have a few tweaks to make it easier to use by the welders, and maybe nudge the dose reduction down a little more as well. Much thanks to all who have helped with this effort.”
—John Burns, DCS Project Coordinator
“Thanks very much got the shielding yesterday just in time to use!! It also fit perfectly. We got a large gamma reduction, with the old shielding in place it was 500/120 mr/hr [5,000/1,200 μSv/hr] gamma and with the new shielding it went to 100/55 mr/hr [1,000/550 μSv/hr] reduction … That fire blanket makes for a smooth in set in the annulus area.”
—Donna Fay, RP ALARA
