Critique of Holtec’s Dry Casks

Oscar Shirani worked for Commonwealth Edison & Excelon. He blew the whistle on the defects of Holtec’s dry casks. He was blacklisted by the industry. (He died in 2008.) Here is a summary of Oscar Shirani’s allegations against the Holtec dry cask, and support from Dr. Ross Landsman, NRC’s Region 3 dry cask inspector (the hand written notes are Shirani’s own):

Donna Gilmore has done a lot of research on dry cask storage of high level radioactive waste. Her research is posted on her webpage You can listen to a podcast of an interview with Donna on Vermont Yankee, released July 1, 2014 on Nuclear Hotseat podcast Donna’s interview begins almost half-way through. Host Libbe Libbe HaLevy runs through this week’s nuclear news first. If you are short on time, scroll ahead to under the S in the red LISTEN above it.

She looked at the power point by Holtec International’s CEO Dr. Kris Singh, presented at the last NDCAP meeting, and wrote us this email:

I found a lot of holes in Holtec’s slide presentation.

Holtec: A leak-tight confinement that renders the likelihood of radiation leakage in long term storage non-credible.
DG: ignores stress corrosion cracking of the thin canister.  Ignore there are air vents in the concrete overpack.

Holtec: No loaded canister of Holtec’s has ever leaked in long term storage
DG: There has never any in long term storage; notice he doesn’t mention whether any of them have cracks, since he cannot inspect them. And he doesn’t mention they cannot be repaired, even if they could find the cracks.

Holtec: As the pie chart shows, the HI-STORM MPC System is the most widely used canister system in the world.
DG: But not the most widely used storage system — thick metal casks up to 20″ thick are — not the Holtec thin (1/2″) canisters.

Holtec: In addition to the US, countries with active terrorist cells, such as Spain and Ukraine, have selected Holtec’s HI-STORM for their spent fuel storage needs.
DG: The system has not yet been installed in the Ukraine and they are using a different design, but one that is still inferior. Holtec has sold them a double wall thin canister system.  Outer is 3/8″ and inner is 1/2″ thick stainless steel.  They are still subject to stress corrosion cracks, so are not designed for long term use and are not inspectable or maintainable. And just because they are using them doesn’t make it a good decision or prove it will be good protection from terrorists.

Additional DG comments:
Not designed for inspection or maintenance of the concrete or the thin steel canister.No seismic rating for cracked canisters.No early warning monitoring system.  Will only know AFTER leaks radiation.Bolted lid thick casks have pressure monitoring system and double seals, so if there is any change in pressure there is instant notification, so the problem can be dealt with (e.g., change seals).  The ductile cast iron casks have two independent bolted lids, each with double seals.  If one seal or lid fails, the other is fully functional.  This is true defense in depth.  The Holtec thin systems do not have this.No mention that the Holtec thick over pack has air vents (needed for cooling the thin canister), so the single point of failure is the thin canisters.Regarding the concrete, I haven’t researched using concrete without rebar. According the the tech specs the concrete doesn’t provide structural support.

By enclosing the concrete in steel, you cannot inspect the concrete for degradation.   There are numerous degradations mechanisms for concrete.  The key is to be able to inspect the concrete.  The Holtec design makes that impossible.  I have a section on the nuclear waste page of my website that addresses concrete degradation of spent fuel storage systems.

A news article said there was 2″ thick steel.  Not sure what this applies to.  It doesn’t apply to the 1/2″ thin canister.  The Overpack has a 3/4″ steel exterior and a 1 1/4″ steel interior. Is this what they were referring to? See FSAR (PDF page 156).

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