By John Hallam
Bulgarian nuclear reactors "are an accident waiting to happen", according to International Atomic Energy Agency officials,
Bulgaria has — or had — five VVER nuclear plants in operation (Kozloduy1-5), with Kozloduy 6 due to be started up this year, and Belene 1 & 2 also under construction. The Bulgarian VVERs were among the first to be built outside the USSR.
Kozloduy 1-4 are VVER-440 plants of early design. Kozloduy 5 & 6 are of a more recent design that's assumed to be much safer.
There isn't any reason why VVER-440 plants can't be operated as successfully as any Western plant — if the performance of some Western plants could be said to constitute success. Both the Finns and the Hungarians, with elderly VVER-440 plants, have been held up as shining examples of successful reactor management.
The IAEA assessment said that the condition of the Kozloduy VVER plants is so bad that they should be shut down immediately. This would make life very difficult for Bulgaria, which obtains 40-50% of its electricity from those plants.
Bulgaria has said that it will continue to operate the units unless it is given replacement power.
Much of the problem seems to stem from complete lack of maintenance. The IAEA inspection team found unsafe electrical cables, cables pulled out, hand wheels missing from valves, and lots of oil, steam and water leaks. There was a danger that leaking oil could ignite on contact with hot pipes.
Power cables were unsealed, ground wires and control indicators were missing, equipment wasn't labelled, and the emergency core cooling system was leaking to such an extent that it was doubtful that it would work if called needed.
The IAEA identified a work culture that included "lack of safety culture, poor work practices, industrial safety hazards, poor radiation protection, lack of operator training, incomplete operating procedures, and core design limits unknown to Bulgarian staff".
Under the heading of "design deficiencies", the IAEA listed: "Core design limits not known to Bulgarians, insufficient protection of the emergency feedwater system against common cause failures, insufficient segregation of redundant equipment in the safety injection and spray systems, no environmental and functional qualification of safety injection equipment, unit 2 reactor pressure vessel needs to be annealed, confinement leakage very high, accident analysis of limited scope incomplete".
The IAEA did not suggest that the Kozloduy plants be decommissioned. What it did suggest strongly was that the plants be refitted with improved confinement systems, upgraded steam generators and improved emergency core cooling systems.
In response to the report, German environment and nuclear safety minister Klaus Toepfer did call for the permanent closure of Kozloduy. Germany had already decided to shut down its own VVER plants at Griefswald, in the ex-GDR, rather that try to refit them. At a July meeting in Vienna, an "action package" for Bulgaria was discussed, with the Bulgarians demanding help in refitting Kozloduy and in starting up Kozloduy 6.
On July 17, the EC announced a $13 million program of "quick refits and repairs" for Kozloduy, lasting six months. Bulgaria had said a month previously that to "rebuild" the Kozloduy plants adequately would require US$1.5 billion, so the EC sum was quite inadequate. The EC plan included the transfer of operators and spare parts from the decommissioned Griefswald plants.