some details on the criticality in Japan

["Michael C. Baker" <mcbaker@lanl.gov>]

Here is some information that was sent to the criticality safety email list 
on the accident in Japan.

Mike


>---------- Forwarded message ----------
>
>Toshihiro YAMAMOTO <yamamoto@melody.tokai.jaeri.go.jp> on 09/30/99
>11:10:41 AM
>
>To:   VFDean@aol.com
>cc:   Valerie L Putman/VPUTMAN/LMITCO/INEEL/US@INEL
>Subject:  Re: Fwd: Possible Criticality in Japanese Fuel Reprocessing
>       Facility(fwd)
>
>Dear colleague
>
>The following information are very preliminary ones and please
>keep in mind that those may be wrong.
>
>The accident was allegedly caused by putting more fuel
>into a tank than allowed (about 5 times ).
>The fuel is uranyl nitrate solution. The enrichment is
>18.8wt.% The concentration is approximately 370gU/l.
>The nitric acidity may be more than 1 mole/l.
>This fuel is for the test fast breeder reactor JOYO.
>
>The tank inner-diameter is 50 cm and 2.5cm-thickness water coolant is
>surrounding the tank at the side and the bottom. Approximately
>50 liter solution was poured in the tank, which means the solution
>height is approximately 25.5 cm. The tank wall thickness
>is 3 mm and made of stainless steel. My preliminary calculation
>gives keff=1.044 with MCNP and TWODANT. Exactly speaking,
>the bottom of the tank is slightly concave. But, detailed
>information is unknown.
>
>The criticality is probably continuing now even though
>the accident occurred more than 16 hours ago.
>
>If the water coolant is removed, the fuel may or may not be made
>subcritical (approximately keff=1.000).
>
>I hope this information is helpful for you.
>
>------------------------------------------
>Toshihiro YAMAMOTO
>Japan Atomic Energy Research Institute
>Dept. of Fuel Cycle Safety Research
>Criticality Safety Laboratory
>Phone:81-29-282-6743
>Fax:  81-29-282-6798
>E-mail:yamamoto@melody.tokai.jaeri.go.jp
>------------------------------------------



______________________________________________

Michael C. Baker, Ph.D., P.E.
Environmental Technology Group
Environmental Science & Waste Technology Division
Los Alamos National Laboratory
Mail Stop J594, Los Alamos, NM 87545

mcbaker@lanl.gov

(505) 667-7334 (phone)
(505) 665-8346 (fax)
(505) 996-3519 (pager)
______________________________________________

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