MOST of Sellafield could be closed down if it continues to fail to make its
high-level radioactive waste safer. Attempts to store the waste in glass at
Britain鈥檚 main reprocessing plant are being thwarted because vital equipment is
corroding and failing faster than expected, according to documents leaked from
the UK Atomic Energy Authority (AEA).
High-level waste, which comes from the reprocessing of spent fuel from
nuclear power stations and military reactors, is the longest-lived, hottest and
most dangerous of all the radioactive debris produced by the industry. About
1000 cubic metres of it is stored as a liquid in 21 constantly cooled tanks at
the Cumbrian site.
Two years ago, a study warned that an accident in the tanks could force the
Irish government to evacuate half a million people from Dublin
(This Week, 15 June 1996, p 6),
and a scientific report highlighting the risk of an accident is
due to be published next week by antinuclear local authorities.
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Because of the dangers of keeping the waste in the cooling tanks, the
government鈥檚 Nuclear Installations Inspectorate urged British Nuclear Fuels
(BNFL), which runs the Sellafield plant, to make the waste more containable by
solidifying it into glass blocks for permanent storage 鈥渁s soon as practicable鈥�.
A crucial part of this process is the vitrification plant that BNFL has been
operating at Sellafield since 1990.
But internal memoranda from the AEA, whose waste is treated by BNFL, reveal
that the vitrification plant suffers from 鈥渃ontinued poor performance鈥�.
Crucibles in which glass is melted have averaged only 900 hours of use, instead
of the 2500 hours expected. This is due, says the AEA, 鈥渢o a combination of
fatigue, corrosion and creep鈥�.
Replacing the defective crucibles is also problematic. To remove them from
the plant they must be cut into pieces, but according to the AEA the saws bought
by BNFL for the task are 鈥渋neffective鈥�. BNFL is now suing the French company
that supplied the saws.
The leaked AEA memos warn that failure to solidify enough high-level waste
could prompt the nuclear inspectorate to prevent any more from being separated
by withdrawing permission for reprocessing spent fuel. This would shut down most
of Sellafield.
Gordon Thompson from the Institute for Resources and Security Studies in
Massachusetts, the author of the upcoming local authorities鈥� report into the
consequences of an accident in Sellafield鈥檚 waste tanks, points out that delays
in vitrification will increase the amount of waste stored in the crucibles.
鈥淭his will exacerbate the danger,鈥� he says. 鈥淰itrification is dramatically
蝉补蹿别谤.鈥�