Gary said, Thanks for sharing these responses ahead of the meeting. I do have some follow up questions here in blue.
Answers to Gary’s questions and yours (Dan Stetson's) here in red type:
1. Can you find out if Canister #72 is the one that got hung up on the download?
No. Multipurpose canister (MPC) 067, stored in location #22, is the MPC that hung up. MPC067 had no scratches with measurable depth. When the MPC hung up, it was resting on the 3” thick base plate. The MPC base plate being wedged against the shield ring, in and of itself, does not lead to scratching. MPC072 is stored in location 44. MPC072 had the deepest measured scratch of the 8 MPCs inspected in 2019, at 0.026”.
I would think that if you had one of eight canisters with such severe damage you would automatically want to inspect all canisters. How much damage was discovered on the other 7 canisters inspected? Do we know what caused the gouge and the corrosion on MPC072? Besides having less wall thickness from gouging, doesn't that also accelerate corrosion between two different metals being in contact with each other? It seems like damaged canisters should take priority for inspections and be more frequently monitored. At what point is the decision made to actually try to repair a canister like this one with the spray on nickel plating technique, or is this too big of a scratch to repair that way?
2. Do the steel cylinders that the canisters are lowered into have metal floors or do they sit on the lower concrete slab?
The MPC rests on a 2” tall stainless-steel pedestal ring.
What purpose does the stainless steel ring provide?
Are there any barriers or sealants to water intrusion that are something other than concrete and steel joints?
And my question (Dan's), is canister #19 on the schedule to be inspected at some point?
Dry storage canister (DSC) 019, referenced by Mr. Busnardo, is a TN canister in the horizonal NUHOMS storage system. After insertion, material from the DSC shell was retrieved and sent to an offsite laboratory to measure the thickness of embedded layers. The laboratory found the maximum depth of the scratch was 0.012”. For the 2021 inspection, SCE selected two canisters most susceptible to chloride induced stress corrosion cracking for inspection. SONGS and industry inspections have found no degradation in the area of scratches caused during insertion (what do you call the visible damage to #72 ?). For the scheduled 2026 inspection, “the oldest and coldest” canister (inspected in 2021) and a second—not previously inspected—canister will be selected for inspection. SCE has not yet selected the second canister to be inspected.
We all heard Mr. Busnardo say "the engineers pencil whipped it until it was determined to be safe". Not much confidence there.
Can we use the latest robot technology to actually measure the depth of the gouge rather than relying on the shavings retrieved and repair the canister if needed?
I think I understand the principle behind inspecting "the oldest and coldest" canisters, because they are cool enough to attract more corrosive moisture over the longest period. But is there other criteria used for selecting and monitoring canisters based on known damage that already occurred?
What are the warning signs that a canister might fail from gouging or cracking? More heat, more radiation or other indicators to look for before it is too late?
What recourse and equipment is on hand for trained personnel to deal with anything greater than nickel plating can handle?
The most pertinent question is will you support or at least not object to the Coastal Commission looking more closely at this situation?
The scientists they rely on are telling them that more research is needed at San Onofre.
Patrick Barnard says, "A site specific engineering study would need to be conducted to fully evaluate the local hazard, but the work Kristina and I have done should demonstrate the GW hazards are potentially just as significant as overland flooding hazards and cannot be ignored."
Katrina Hill says, "This San Onofre site needs attention, since it's only a matter of time before salts migrate up into the concrete below the canisters."
