March 23rd, 2011 – Decommissioning Type Information for Ops Center -Entombment Considerations

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From: Scott, Michael
Sent: Saturday, March 26, 2011 2:15 AM
To: LIA02 Hoc
Cc: LIA03 Hoc; Casto, Chuck; Monninger, John; Dorman, Dan
Subject: RE: ACTION – Decommissioning,/Type Information for Ops Center

I think this is more what they were looking for, rather than the licensing discussion previously sent. Please advise me when this is fully vetted and can be released to the Japanese.

Thanks.


From: LIA02 Hoc
Sent: Friday, March 25, 2011 12:25 PM
To: Scott, Michael
Cc: LIA03 Hoc
Subject: FW: ACTION – Decommissioning Type Information for Ops Center

Some more information.

Steve


—-. Original Message —–
From: Richards, Stuart
Sent: Wednesday, March 23, 2011 6:51 PM
To: Camper, Larry; Bowman, Gregory; Rini, Brett
Subject: FW: ACTION – Decommissioning Type Information for Ops Center

fyi – Stu


From: Rahimi, Meraj
Sent: Wednesday, March 23, 2011 5:50 PM
To: Ordaz, Vonna; Benner, Eric; ET05 Hoc; RST01 Hoc; Richards, Stuart
Cc: White, Bernard; Mohseni, Aby; Davis, Jack; Weaver, Doug; Doolittle, Elizabeth; Waters,
Michael; Kinneman, John; Bailey, Marissa; Tschiltz, Michael
Subject: RE: ACTION – Decommissioning Type Information for Ops Center

Here is the proposed SFST/FCCS/HLW coordinated response:

We would not recommend early entombment considerations due to the high thermal loads and associated negative effects on entombment material properties.

In fact, we believe it might not be prudent to entomb at all.

We believe that Japan should consider waiting until the core or spent fuel debris can be cooled sufficiently and then removed similar to TMI. We would initially recommend pumping continuously borated water into the molten core or spent fuel pool.

Longer term, if entombment is considered by Japan, it is our opinion that entombment would be less problematic (with respect to criticality issues) if the entombment is around the molten core or pool, rather than directly onto the fuel and in the primary containment vessel.

We believe that heat transfer will be a significant challenge and thus it would be best if the entombment was built with low and high vents that would enable the transfer of heat through air convection.

If the entombment is considered by pouring some type of material on the molten core or spent fuel pool the system reactivity and heat transfer capability is highly dependent on the material of use.

We believe, the temperature in the reactor core or the dried spent fuel pool is too high for the concrete to cure. Both concrete (especially wet) and sand would be a neutron moderator and could raise criticality concerns.

Whatever is used should be carefully evaluated. Due to the unknown configuration in the core, any medium should conservatively be heavily borated.

Another option maybe the use of sand with boron frits which would turn into glass when contacted with the molten core.

This would immobilize the radionuclides. However, the temperature at which the sand is added must be at the point that the glass can solidified.

This may require longer cooling time.

In the interim while options are considered, it might be advisable to confine the core or the pool with filtered flexible enclosure.

Meraj Rahimi
Chief of. Criticality, Shielding, and Dose Assessment Branch Division of Spent Fuel Storage
and Transportation Office of Nuclear Materials Safety and Safeguard U.S. Nuclear Regulatory
Commission

6003 Executive Blvd., Suite 301
Rockville, MD 20852
Phone: 301-492-3338
Fax: 301-492-3348
e-mail: [email protected]


From: Ordaz, Vonna
Sent: Wednesday, March 23, 2011 3:21 PM
To: Benner, Eric
Cc: White, Bernard; Mohseni, Aby; Davis, Jack; Weaver, Doug; Rahimi, Meraj; Doolittle,
Elizabeth; Waters, Michael; Kinneman, John; Bailey, Marissa; Tschiltz, Michael
Subject: ACTION – Decommissioning Type Information for Ops Center
Importance: High

Eric,

SFST has the lead to coordinate a response with HLW and FCSS, and respond to the Reactor Safety Team, the ET Response Coordinator, and Stu Richards in the Operations Center with a CC to Dan Dorman by 6pm.

Thanks,
Vonna


From: Ordaz, Vonna
Sent: Wednesday, March 23, 2011 3:13 PM
-To: Richards, Stuart; Weaver, Doug; Mohseni, Aby; Davis, Jack
Cc: RSTO1 Hoc; Bowman, Gregory; Hickman, John; Lee, Richard; Rini, Brett; Case, Michael;
McConnell, Keith; Watson, Bruce; Camper, Larry; Deegan, George; Waters, Michael
Subject: RE: Decommissioning Type Information

Thanks, Stu. We’ll get back to you.

Vonna


From: Richards, Stuart
Sent: Wednesday, March 23, 2011 2:32 PM
To: Weaver, Doug; Mohseni, Aby; Davis, Jack
Cc: RST01 Hoc; Bowman, Gregory; Hickman, John; Lee, Richard; Rini, Brett; Case, Michael;
McConnell, Keith; Watson, Bruce; Camper, Larry; Deegan, George; Ordaz, Vonna; Waters, Michael
Subject: RE: Decommissioning Type Information
Importance: High

Dan Dorman has asked the Ops Center to respond to a number of questions related to the
Japanese event.

Can NMSS respond to the following?

8. What should they be considering with respect to criticality prevention and decay heat
removal during the entombment period?

The goal is to provide the response to the Ops Center by 6 pm tonight.

I will forward you the original request, which may help.

Thanks
Stu


From: Deegan, George
Sent: Wednesday, March 23, 2011 2:05 PM
To: Richards, Stuart; Camper, Larry
Cc: RST01 Hoc; Bowman, Gregory; Hickman, John; Lee, Richard; Rini) Brett; Case, Michael;
McConnell, Keith; Watson, Bruce
Subject: RE: Decommissioning Type Information

Stu- As your email came in, Brett Rini and I were speaking with one another. I indicated that FSME will be working on #7 (licensing requirements) and #9 (whatever relevant info we can pull together from the TMI event), but that the best shop for criticality type issues (Question #8) is probably NMSS.


From: Richards, Stuart
Sent: Wednesday, March 23, 2011 1:51 PM
To: Camper, Larry
Cc: Deegan, George; RST01 Hoc; Bowman, Gregory; Hickman, John; Lee, Richard; Rini, Brett;
Case, Michael
Subject: RE: Decommissioning Type Information

Larry

RES might be able to help you with Question #8. Richard Lee in DSA is our POC on this one.

We’can provide you some thoughts on enclosures, but I agree that a good answer will take a lot of time and a lot more information on the status of the units.

Stu


From: Camper, Larry
Sent: Wednesday, March 23, 2011 12:49 PM
To: Dorman, Dan
Cc: Deegan, George; RSTO1 Hoc; Bowman, Gregory; Hickman, John
Subject: Decommissioning Type Information

Dan,

Greetings! Trust you are holding up well over there! Regarding your message of earlier today, we will be able to provide feedback on Question number 6 today by the 18:00 timeframe.

Questions 6,8 and 9 will require a bit of review and interface with RES but we will start that process today.

Standby for a better timeline on those.

The staff did some work on the entombment issue via a couple of SECY’s but the approach died out because it became clear that industry was not going to utilize it in the US.

Of course, the situation in Japan is quite different etc.

Regardless, our earlier work should be of some benefit but we just have .to resurrect it and review etc. In thinking ahead just a bit,

I suspect that we will need to put together some sort of Task Force or think tank type group to analyze possible paths forward for the overall decommissioning of the site and for the related waste management etc.

Of course, we have some time to think about this issue but not too long etc.


Decommissioning Type Information for Ops Center – Pages From C142449-02E-5

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