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Magpie Country Nukes Headliner

nuclear issues news brief from Japan
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Criticality accident at Tokai uranium processing plant

20th REPORT

ANOTHER 2-DIGIT TRICK!
DOSE WAS 120 RATHER THAN 20;
STA REPORT SAYS MORE PEOPLE RADIATED;
MORE ON RADIOACTIVE IODINE RELEASE

16 October 1999

More sloppy (and outrageous) stories from the JCO Tokai accident.

Earlier, JCO spokesman disclosed individual radiation exposure doses of the workers who had engaged in the dangerous operation to control the criticality (see 10th Report, 12th Report). One member of the first team who approached the building to take photographs of the pipe systems they were going to work on, according to this original JCO statement, was dosed with 20mSv.

Now it is revealed that the workers wore 2-digit type neutron recorders, i.e. the meter is reset to "00" when the count is over 99. Yes, "20mSv" was actually 120mSv! (119.79mSv to be exact; neutron plus gamma, mostly consisting of neutron dose.)

The fact was reported by STA (Science and Technology Agency of the Japanese Government) to the accident investigation unit of NSC (Nuclear Safety Commission of the Japanese Government) yesterday (15 Oct).

The tentative risk assessment we reported earlier (see 16th Report) was based on the earlier data (i.e. 20mSv). So we underestimated the life risk.

In the same report, STA confirmed that the number of the exposed was 69. This figure does NOT include the general public who had stayed very close to the plant for over 5 hours in neutron shower before they evacuated. MagpieNews estimate, though roughly, that some 100 to 150 population was significantly exposed to neutron radiation. (see 19th Report).

At a press conference yesterday (15 Oct), JCO admitted that radioactive iodine-131 was still leaking. They had no filter to trap iodine gas in the exhaust system. They said they would put additional filters today (16 Oct) to reduce the emission of radioactivity into atmosphere.

The problem is that STA knew all this all the time. STA should have ordered JCO to do this much earlier. Critics say that STA and JCO may be expecting to reduce the contamination inside the building by releasing the contaminants out into atmosphere, so that liquidating work can be started as early as possible.

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MagpieNews = Magpie Country Nukes Headliner
editor: Dr K. Hosokawa
fax: +81-952-288709
email:
snail mail: Faculty of Agriculture,
University of Saga, 840-8502 Japan
website: http://itak.ag.saga-u.ac.jp/=magpie/33.html
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