2018 - 01 - 03 Mothers for Peace comments to NRC on thin-walled canisters for waste storage

San Luis Obispo Mothers for Peace urges the NRC to order Diablo Canyon and all nuclear plants in the United States to use safer, thick-walled canisters for the storage of high level radioactive wastes. Currently the NRC allows canisters with walls only 1/2 to 2/3 of an inch in thickness, whereas in Germany and Japan the casks are between 6 and 9 inches thick.


Comments to NRC Docket ID NRC-2017-0211, NUREG-2215
NRC Standard Review Plan for Spent Fuel Dry Storage Systems and Facilities Draft, November 2017

San Luis Obispo Mothers for Peace (SLOMFP) has deep concerns regarding the ability of the NRC to meet its goal:"to ensure adequate protection of public health and safety and the environment" based on its acceptance of thin-walled welded canisters for storage of highly irradiated used nuclear fuel at ISFSI sites across the nation, including the Diablo Canyon nuclear plant near San Luis Obispo, CA. 

*The thin-walled canisters currently being used cannot be fully inspected, nor can they be maintained.

*The NRC suggests no method to repair a canister that has been damaged by a through-wall crack.

*The NRC has not defined a method to detect cracking prior to a through-wall crack.

*SLOMFP is not aware of any plan to deal with a leak of radiation in an ISFSI. 

SLOMFP has grave concerns about the willingness of NRC to approved the use of these one-half to five-eighths inch-thick canisters because they may be onsite at nuclear facilities into the long-term future - a least 60 years - according to NRC documents. The canisters are certified for twenty years' use. 

NRC staff states that chlorine-induced stress corrosion cracking could be the dominant life- limiting phenomenon for welded austenitic stainless steel canisters in some environments. "CISCC is a known degradation phenomenon for austenitic stainless steel and has been observed in piping exposed to environmental conditions that may exist at some sites. This is especially true for coastal sites where chloride-containing salts are present and can deliquesce (form an aqueous solution) under certain conditions of humidity and temperature. Thus, the assumption is that CISCC may affect a canister." (https://www.nrc.gov/docs/ML1610/ML16102A167.pdf) Diablo Canyon's canisters meet the conditions for chlorine-induced stress corrosion cracking, and, in fact, a canister was found to meet the conditions for cracking in 2014. 

For these reasons, SLOMFP requests an extension of the comment period and requests to be informed of all decisions regarding canister selection in the future.


Linda Seeley

Spokesperson, SLOMFP