March 25th, 2011 – Strong concern about likelihood of very rapid stress corrosion cracking in the reactor primary system

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>Date: Fri, 25 Mar 2011 09:57:48 -0700
>Subject: reactor#3 and others
>From: [email protected]
>To: [email protected]
> — – – – – – — – – – – – –
>Per,

I’m troubled by the report I just heard on CNN, which indicated that Co was in the ocean adjacent to the plant and in the water that burned the three workers. Apparently the workers were exposed to Co-containing water while in the turbine room. The presence of Co at these two locations suggests that water from the core is releasing into the ocean and into the turbine room.

The cause of the leak(s) might be pipes that were cracked during the hydrogen explosions. Alternatively, the leak(s) might be due to corrosion and/or stress corrosion cracking. The possibility of corrosion and scc must be urgently addressed.

The email that I sent to you one week ago was prompted by our parking-lot discussion in which you mentioned the amount of salt water that was being used to cool the reactors. My concern then was that the chloride would cause stress corrosion cracking of the stainless steel cladding that coats the inside of the RPV and of stainless steel piping that is part of the cooling system.

I indicted that an upper limit SCC velocity of about 0.8 cm/day in stainless steel exposed to hot aqueous chloride. Hot aqueous chloride would severely corrode, and possibly crack, low alloy steel and carbon steel, especially if oxygen (from air) is also present.

The only sure way of stopping SCC is to remove the stress. In this case removing the stress might not be possible because the highest stresses are most likely residual. Furthermore, the carbon steel and low alloy steel are susceptible to very high corrosion rates in high temperature aqueous chloride, so if cracks have penetrated the RPV cladding then corrosion of the low alloy steel is as much of a potential problem as is SCC.

The steam lines going from the RPV to the turbine are carbon steel, so hot aqueous chloride can be expected to severely corrode and possibly crack the steam lines.

At this point the best remedial action to take is to get rid of the salt.

Probably the only way to do it is by dilution: flooding the reactor with salt-free water. In my view it is extRemely urgent that the chloride be removed asap. Can you communicate this message to someone in authority?
>Tom
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