By Renfrey Clarke
MOSCOW — Was this to be the next Chernobyl — only 100 kilometres from Russia's second largest city? Early in the morning of March 24, a steam pipe ruptured in the third reactor block of the Sosnovy Bor nuclear power plant outside St Petersburg. Pressure built up in the container vessel, and safety devices were triggered. To avoid an explosion, radioactive gases were released into the atmosphere.
The reactor was shut down, and the Russian nuclear energy establishment went into damage control mode. The level of radioactivity in the steam that escaped was not high, a spokesperson from the Sosnovy Bor technical staff claimed, and no threat was posed to the health even of the people at the station.
No special measures, it was said, needed to be taken outside the reactor building. By the morning of March 25, radiation levels around the plant were reported to be normal.
The incident was among at least 10 "irregular situations" during the past 12 months at the Sosnovy Bor plant. In this case, the Russian State Committee on Emergency Situations reported that the maximum allowable daily release of radioactive materials into the environment was exceeded by 10 times for iodine, and by six times for inert gases.
The total quantity of radioactivity released was about 3000 curies. In St Petersburg, alarmed rumours circulated of a radioactive cloud over the Gulf of Finland.
Despite the assurances, there was nothing minor about the March 24 "irregularity". Specialists at the Kurchatov Atomic Energy Institute in Moscow said that the incident rated at 3 or even 4 on the seven-point international scale used for describing nuclear reactor accidents. By comparison, the accident at Three Mile Island in the US was rated at 5, and Chernobyl at 7.
Only six days earlier, Izvestia had published a letter in which the director of the Sosnovy Bor plant, along with other scientists and officials, disputed the conclusion of a group of Swedish experts that reactors of the type at Sosnovy Bor — and Chernobyl — were hundreds of times more dangerous than modern western plants. The letter claimed that since the Chernobyl disaster, modifications to the first block of the Sosnovy Bor plant had reduced the likelihood of a serious accident there by a factor of 100.
For some days after March 24, the debate on the dangers of Soviet-built nuclear power plants was on the front pages. The head of the Division of Atomic Energy Safety at the Kurchatov Institute pointed out that the Chernobyl-type reactors did not meet even the lax requirements adopted in the USSR in 1982, not to speak of current international standards.
Ivan Selin, the head of the US Nuclear Regulatory Commission, described these reactors as posing a "colossal danger", and urged t down. Despite modifications, Selin argued, the danger of a serious accident in the three remaining reactors at Chernobyl had "diminished only by half" since the period immediately before the catastrophe in 1986.
There are particular dangers from these reactors, which a group of German experts recently described as "bombs, temporarily giving off electricity".
Nuclear power accounts for about 12% of total electricity generation in the Russian Federation, and there are also nuclear power plants in Lithuania, the Ukraine and Armenia.
The RBMK-type reactors at Chernobyl and Sosnovy Bor represent the first generation of Soviet nuclear power reactors, designed more than 30 years ago. Plants of this kind, which were intended to produce both electricity and plutonium for the Soviet nuclear weapons program, provide some 40% of the nuclear power generated in the former Soviet Union. Of 41 nuclear power reactors on the territory of the former USSR, 16 are of the RBMK type; apart from Chernobyl and Sosnovy Bor, the others are at Kursk and Smolensk in Russia, and at Ignalina in Lithuania.
Though primitive, these reactors are huge in size and output. The two RBMK-1500 reactor blocks at Ignalina are reportedly the most powerful in the world.
In a basic technical respect, the RBMK plants are unlike almost all western nuclear power reactors, having what is known as a positive coefficient of reaction. In most western nuclear power plants, if the reaction speeds up and produces more heat than is required, the process is automatically slowed by a "negative feedback" mechanism. But in RBMK plants, the more heat, the more vigorously the reaction proceeds. As a result, these plants are exceptionally prone to run out of control.
The Sosnovy Bor plant began producing electricity in 1973. It consists of four reactor blocks. The third, which was the scene of the latest "irregularity", came on stream in December 1979; the trade union paper Trud recently published chilling excerpts from the press of the time, hailing the "shock work" that had brought the reactor block into operation ahead of schedule.
With construction methods such as these, it is not surprising that Sosnovy Bor has a reputation as one of the least reliable of Soviet nuclear power plants. The recent release of radioactivity from the plant was not the first; a similar incident occurred in 1975. Swedish experts who recently examined a number of nuclear power plants in the former USSR were sharply critical of the safety methods employed at Sosnovy Bor and Ignalina. In particular, fire prevention mechanisms were described as inadequate.
All of the RBMK reactors clearly need to be taken out of operation as quickly as possible. The complexities of such a move are daunting. In Lithuania, for example, the effect would be to cut total electricity generating capacity by more than 55%. Shutting down Sosnovy Bor would leave Leningrad province, with its nearly 7 million people, critically short of energy. Enterprises would be forced to close, and unemployment would rise steeply.
But as Chernobyl showed, leaving plants of this type in operation cannot be regarded as a cheap option.
The task of ending the worst dangers created by the Soviet nuclear power program is not one exclusively for the states of the former USSR. After all, the Chernobyl disaster dumped radioactivity on Scandinavia as well.
To protect their own citizens, western governments must contribute to the cost of creating alternative energy systems in the former Soviet republics. Not without self-interest, a group of western power engineering firms has now urged that an international fund of US$7.5 billion be established to cover the cost of shutting down the RBMK plants, and of improving safety provisions in other nuclear power stations in the former USSR.