- Criticality accident at Tokai uranium processing plant
- 15th REPORT
- AT A LOSS WHAT TO DO WITH EXTREME CONTAMINATION; FALLOUT
RADIOACTIVITY DETECTED; THE ACCIDENT FAR FROM OVER
- Is the Tokai accident over?
- No way!
- First of all, nobody knows what is the physical condition
inside the buildin g in which the criticality took place. The radiation
(now mainly gamma) leve l is too high so that there is no access for the
- At least we are 100% certain that there is a good lot
of fission products (i .e. radioactive materials) in that building, namely
what JCO calls the Re-co nversion Test Building.
- This means at least two things:
- * We do not know whether there is physical destruction
of the building struc ture through which the fission products can escape
- * A large number of workers prepared for radiation exposure
is needed for li quidation of the site.
- There is an alternative, of course, of doing no liquidation
work and just sh ield the entire building with concrete and/or some other
material, i.e. cons truction of a Chernobyl-type sacrophagus although the
size is much smaller.
- At the moment, the site has been walled with a make-shift
shield of piled sa ndbags actuallyu containing alminium powder that absorbs
neutrons and dry co ncrete that blocks gamma.
- The following is an inventory of fission products detected
within 3km of the accident site. The figures were taken from newspapers
and TV reports, and ha s been compiled by CNIC.
- * strontium-91 --- 0.021Bq/m*3 in air, 900m southeast
of the site
- * strontium-91 (krypton-91) --- unknown amount, location
- * iodine-131 --- 54.7Bq/kg from mugwort leaves, 100m
from the site
- * iodine-133 (krypton-91) --- unreported amount, 100m
from the site
- * cesium-137 --- unreported amount, 7 locations
- * sodium-24 --- 64Bq/kg, 300m west from the site
- * sodium-24 --- 1.7Bq/kg, 3km west from the site
- * xenon-139 --- from the vomit of the exposed workers
- * krypton-91 --- from the vomit of the exposed workers
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