First, is this Surry's first experience with drying a dry shielded canister? In other words, did the problem start with the 32-PTH? Hard to imagine the poison used for the canister would influence the rate at which gas is released.
SONGS is still using a 24PT4 canister with Boral poison. We're close to finalizing the design for a 32-cell DSC with metal matrix composite (MMC) poison. We're scheduled to start using the 32PTH2 (MMC) in 2014.
Our vacuum drier discharges to a poly bottle. A vacuum with HEPA filter sucks on the poly bottle. The vacuum discharges to the voluminous spent fuel building; it is not connected directly to the vent stack.
If our vacuum dryer were connected directly to the vent stack, I wouldn't be surprised if we observed increases, or spiking, on the effluent monitor. I believe the HEPA filter and huge volume of the spent fuel building dilutes the gas to point of being undetectable, or barely detectable. We've dried some gory fuel in the past (all the old failed fuel is in dry storage); Operations has never told us to stop because a monitor has alarmed.
Hope this helps.
Jeff Carey
U2/3 Health Physics Supervisor
x87545/87722
Pony mail: J72
From: Erik P Simon <[email protected]>
To: "[email protected]" <[email protected]>
Date: 08/17/2011 04:47 AM
Subject: Powernet: NUHOMS loading failed fuel
Sent by: [email protected]
Surry Power Station wants to know if anyone has had to deal with loading failed fuel into NUHOMS casks specifically the 32-PTH metal matrix type? We have recently loaded 4 of 32 assemblies with known leakers and are experiencing difficulties in vacuum drying the DSC due to high levels of Kr-85. Our current configuration has the vacuum drying system directly discharging to the Vent Stack 2 ( Vent Vent), there is no let down or delay prior to the radiation monitor.
Thanks,
Erik
Erik Simon
Health Physics Shift Supervisor
Radiation Protection, Surry Power Station
Dominion Generation
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