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Children living near the site of Tomsk-7 are being evacuated as the
International Atomic Energy Agency revealed that plutonium was released
by the explosion at the Siberian nuclear plant earlier this month.

Meanwhile, it emerged that France has been paying Russia more than $20
million a year to treat French nuclear waste at the uranium enrichment plant
at Tomsk.

On 6 April a tank exploded at a reprocessing plant at Tomsk, sending
a cloud of radioactive particles into the air (This Week, 17 April). The
IAEA initially called it a ‘level three incident’, in which no radiation
was released outside the plant.

This week, after a team of inspectors had visited the site the IAEA
reported an ‘external radiological hazard’ that ‘seems minimal’. It says
the tank contained 25 cubic metres of uranium, plutonium, ruthenium, zirconium
and niobium in solution, the remnants of a fuel element undergoing reprocessing.
Caesium and strontium had already been removed. An operator was adding nitric
acid to remove more impurities when the mixture exploded.

The IAEA says such a mixture must be stirred to prevent solvent accumulating
at the top, and reacting explosively with nitric acid. ‘Either this was
not done, or was not done with sufficient intensity. Human error was the
cause of the accident.’

According to the IAEA, the tank contained 8773 kilograms of uranium
and 310 grams of plutonium. Some 7000 kilograms of uranium were blown out
of the tank by the explosion, and ‘228 grams of plutonium are not accounted
for’. Some went into the plant’s ventilation system, then out through a
chimney. The ventilation ‘was rearranged within a short time’ to stop this,
says the IAEA. It calculates that only 7.5 per cent of the material in the
tank was released through the stack.

The IAEA’s report does not make clear how it made this calculation,
but if it is correct then 23 grams of plutonium may have escaped. ‘That
is still a lot of plutonium,’ says John Large, an independent British nuclear
engineer. If the stack was not shut as quickly as the IAEA believes, much
more plutonium could have escaped.

No one has any reliable measurements of plutonium outside the plant.
Burton Bennett, the British nuclear engineer who headed the IAEA’s inspection
team, says he ‘could do no more than get a general impression’, using a
gamma spectrometer to scan the area quickly from the air.

The IAEA says there is one village of 200 people, Georgievka, in the
contaminated area. The children have been sent out of the village for two
months ‘as a precautionary measure’, says Bennett. Radiation dosages ‘were
reported’ to have reached 30 microsieverts an hour in Georgievka. The international
safety limit for radiation workers is 50 millisieverts per year.

Bennett says that despite heavy damage to the plant, plutonium production
is continuing ‘on a reduced scale’. Tomsk may still be operating because
it earns foreign exchange. Nikolai Yegorov, Russia’s deputy minister for
atomic power, told deputies of the Russian parliament that the country imports
between 300 and 400 tonnes a year of uranium reclaimed from reprocessed
French fuel. It turns this into enriched uranium, to be re-used in fuel,
earning between $20 and $30 million per year.

Cogema, the state-owned company that handles France’s nuclear fuel,
says that it has a contract with the Russian atomic ministry to do such
work but that it does not know where exactly the work is done. Damon Moglen
of Greenpeace says Yegorov told him the enrichment is done in Tomsk.