Events that occurred late in the evening of April 10th 2003 in the fuel assembly storage tank of the nuclear power plant at Paks were reminiscent of two incidents that have filled the history of civilian nuclear power with foreboding; namely the nuclear disasters at Harrisburg in March of 1979 and at Chernobyl in April of 1986. Inexcusable design flaws, sloppy monitoring, incorrect operating instructions, poor judgment under stressful conditions, and not least of all, a naive trust in highly sensitive technology were all well known problems before that Thursday evening in Hungary, not only from Harrisburg and Chernobyl, but also from the reprocessing plant at the British site in Sellafield, the Monju breeder reactor, the Japanese reprocessing plant in Tokaimura, and also from the German Brunsbüttel plant on the Elbe River. Wherever people work, they can make mistakes. It was just fortunate that the chain of errors, invariably labelled "inexplicable", did not produce consequences as grave as for the Ukraine and its neighbours back in 1986.
In block 2 of the Paks nuclear power plant, which is located 115 kilometres south of the Hungarian capital Budapest, the damage was restricted to overheating and the destruction of 30 highly radioactive fuel assemblies that were transformed into a radiating mass on the floor of a steel tank flooded with water. It remained at the level of a massive release of radioactive inert gas that flowed into the reactor room, from which the operators fled in panic, and which was later blown unfiltered into the outside air at full ventilator strength for a good 14 hours to make the room accessible to personnel in radiation protective gear.
The Paks name represents the most serious accident at a European nuclear reactor since Chernobyl. The highly radioactive material overheated outside the concrete- walled safety containment but beyond the borders of Hungary, however, the world hardly took any notice of the nuclear inferno brewing inside a mobile cleaning facility for fuel elements. To their horror, the Hungarian and foreign specialists who reconstructed the chain of events later that night realised that the outcome could have been much worse.
The lack of worldwide concern about the accident at Paks was not the only new part of the story. This dramatic incident represented yet another first. For the first time, Western and Eastern European reactor teams jointly, and virtually single-mindedly, caused a serious failure due to a cascade of nonchalance, management error, and careless routine. Participants included design engineers and operators from the German/ French nuclear energy group Framatome ANP (a subsidiary of the French Areva and the German Siemens corporations), operating teams at the Soviet-style nuclear power plant in Paks, and experts from the Hungarian nuclear regulatory authority in Budapest. They were all partially responsible and all got off lightly.
The 30 fuel assemblies, which constituted about a tenth of a full reactor core load, did not cool down sufficiently following the chemical cleaning process. They first brought the cooling water in the cleaning tank to the boil, then boiled off all the water, heated up to 1200 degrees Celsius, and finally crumbled like porcelain as the overtaxed operators, after failed attempts to circumvent a catastrophe, unleashed a torrent of cold water on them. According to reactor physicists, a nuclear explosion could have occurred, i.e. a limited but uncontrolled chain reaction. This would have had disastrous consequences for all in the vicinity of Paks and beyond.
 |
 |
 |
 |
|
 |
 |
 |
 |