How safe if SAFE?

Saturday, August 27, 1994

A plan to upgrade two nuclear reactors in Solvakia may force Western governments to stop dithering over nuclear safety in Eastern Europe.

Ever since the reactor at Chernobyl exploded in 1986 spewing radioactivity over more than 20 countries, Europeans have lived in fear of another large-scale nuclear disaster. That fear grew when the Iron Curtain fell, revealing the full extent of the problems with nuclear plants in the former Eastern bloc. It also fuelled a fierce debate: should Soviet-designed reactors be shut down or could they be made 'safe'?

Up to now, that debate has been academic. Eastern European governments, struggling with economic hardship and short of power, have not closed a single working reactor. And Western nuclear firms, despite their hunger for new markets, have shied away from upgrading the reactors, for fear of being held liable for any subsequent accidents.

But this autumn, the West must finally decide what to do. A company formed by Electricite de France (EDF), France's state-owned generator, and its Slovak counterpart SEP has applied to the European Bank for Reconstruction and Development for a loan to upgrade and operate two partly-built nuclear reactors at Mochovce in Slovakia. The EBRD is expected to decide on the loan by December - a decision that will need the backing of most of its biggest contributors, which include Britain, France, Germany, the US and Japan.

But there are big concerns over whether the proposed upgrades will provide adequate levels of safety. Present estimates for the cost of improving Mochovce fall far short of a four-year-old estimate for bringing similar reactors in East Germany up to West German standards. There are also questions about the need for the reactors' power. Greenpeace and Eastern European environmental groups say Mochovce will mainly provide cheap electricity for Western European countries, produced at safety standards the West would not allow.

EDF and SEP plan to complete two of four nuclear plants at Mochovce that were abandoned by the Soviets in 1989. Each is a 440-megawatt pressurised-water reactor of a type called VVER 440/213. According to Peter Bossew, a nuclear engineer at the Austrian Ecology Institute in Vienna, these reactors are not as dangerous as earlier models. But they are still not safe.

The model 213 is already operating in other countries, including Russia, Hungary and the Czech Republic. Four were being built at Greifswald in East Germany before unification, and West German electricity companies were interested in taking them over. These reactors - like those at Mochovce - were 90 per cent complete.

In 1990, the GRS, the West German agency responsible for monitoring reactor safety, conducted extensive studies of the reactors. It concluded that they could be upgraded to meet West German standards at a cost of at least DM2 billion ( £830 million) for each reactor. The electricity companies dropped the plan, says Bossew.

Michael Sailer, a nuclear engineer at the Okoinstitut in Darmstadt, Germany, says most of the problems the GRS found in Greifswald also exist at Mochovce. There are, for example, fundamental problems with the cooling system. In the model 213, primary coolant pipes carry water through the reactor to be heated. This heat is then passed to a separate, secondary cooling circuit in which water is turned to steam to drive the turbines and generators.

Both circuits are under pressure. If one broke, heat would no longer be removed from the core and emergency measures would be needed to stop the core melting. The GRS found that at Greifswald, the secondary circuit had no dampers to protect the pipes from damaging vibrations caused by the pressure. Nor was it fitted with emergency pressure release valves to vent steam safely to the outside. Such equipment is required on pressurised-water reactors in the West.

The secondary circuit is made up of six separate sets of pipes. The model 213 has been designed so that five of these can remove heat fast enough from the primary circuit to prevent the core from overheating. The reactor can run even if one pipe is ruptured, says Sailer. However, all six pipelines run side by side. The GRS concluded that if one was to burst, others would probably be damaged. If two pipes burst, the reactor could not be shut down safely. In the West, duplicate pipelines must be separated by walls to stop one failure causing another. The secondary circuit at Mochovce would need to be completely rebuilt to meet these standards.

The GRS also found at Greifswald that electrical cables to pumps, the emergency cooling system and other equipment also run side by side, so a single fire could destroy both main and backup circuits. To meet Western standards much of the wiring at Mochovce would need to be reinstalled.

The worst failing of the model 213, says Sailer, is the lack of containment. In the West this means a strong outer shell capable of withstanding explosive leaks of radioactive gas or liquids. This problem was not dealt with in the GRS study, Sailer says.

Mochovce and Greifswald have a form of containment. Any material released during an accident is supposed to be vented to a building called a bubble tower. It would flow through 12 parallel pipelines, each of which leads to a large water tank. There it would bubble through water intended to cool and deposit any radioactive material.

But the design has never been tested, says Sailer: 'Nothing guarantees that the steam will flow into the tanks in 12 equal parts.' More steam in one tank would overwhelm it. Moreover, the system is designed only to handle steam and not the denser mixture of gas and liquid that can spew from an exploding mixture.

Jean-Alain Veaujour, head of EDF's Central and Eastern European operations, says he is not familiar with the details of the GRS study of Greifswald. His company has decided it can make two of the reactors at Mochovce safe without major changes to the design, or adding more containment. It estimates that upgrading both reactors will cost 4 billion francs ( £500 million), which is less than a third of what the GRS said it would cost to upgrade two reactors at Greifswald to West German standards. It is not clear whether the discrepancy in cost is due to differences in labour and construction costs between Germany and Slovakia or whether the upgrades at Mochovce will not be as extensive as those recommended for Greifswald.

EdF has not made public the precise changes it wants to make at Mochovce, but Morris Rosen, an assistant director-general of the International Atomic Energy Agency, which has approved the plans, says the modifications will centre on improving the reactors' control and monitoring systems. This is unlikely to mean rebuilding wiring systems and the secondary cooling circuit.

Veaujour says a joint study for the French nuclear safety agency IFPN, and Germany's GRS, also 'broadly approved' EDF's plans for Mochovce last month. 'They want better fire and seismic protection, and some reorganisation of the control procedures, but such things are completely normal,' he says. 'There were no surprises.'

Veaujour says the containment system of the model 213 may not be the same as in the West, but that IAEA studies 'show it is valid'. But Rosen is not so certain. He says there is still 'some concern' over bubble tower performance.

Anthony Churchill, who retired in June as head of industry and energy at the World Bank, does not think the model 213 can be made safe. It 'lacks an acceptable containment structure', he says. 'Under no circumstances,' says Churchill, 'can such plants be brought up to acceptable international standards.' He says they should be 'shut down as soon as possible'.

But the EBRD is taking Mochovce seriously. Tim Murphy, head of environmental appraisal at the EBRD, says the reactors should be brought up to the safety standards that would be applied in the West 'for the backfitting of existing facilities.' Since there is nothing like model 213 in the West, precisely what this means is unclear, but Murphy describes it as 'a term that is understood'.

The EBRD also insists that once Mochovce is running, which EDF expects in 1997, two older VVER 440/230 plants in Slovakia should be shut. The two plants, at Bohunice, have been repeatedly criticised internationally. 'We regard this as a nuclear safety proposal,' says Murphy. It will replace unsafe plants at Bohunice with safer ones at Mochovce.

But, it is not clear yet that Slovakia will shut Bohunice as soon as Mochovce is running. Murphy says the date is 'being negotiated'. Bernard Ses-trienka, head of energy for the Slovak Ministry of Economics, has told the German press that with Mochovce, Slovakia could export electricity at only 60 per cent of its price in the West. And two German electricity companies, Bayernwerk and Preussen Elektra, are keen to buy this power.

Slovakia may need to sell electricity abroad to pay its share of Mochovce. EDF wants a quarter of the cost of the project to be paid by the EBRD. More loans are expected from Euratom, the nuclear arm of the European Union, which was granted permission by the EU last spring to spend money on reactors in Eastern Europe.

EDF is not worried about liability for Mochovce. Slovakia is expected to sign the Vienna Convention, which absolves builders of nuclear plants from liability for accidents. Neighbouring Austria, however, has not signed the convention. Austrian representatives at the EBRD oppose Mochovce, and Austrian authorities have told Slovakia they will sue anyone involved in a nuclear accident affecting Austria.

One important question left unanswered is whether upgrading reactors at Mochovce is the best investment for Slovakia to make in order to solve its energy problems. The EBRD is performing studies to see whether the scheme is a 'least-cost alternative', says Murphy. Energy analyses in Eastern Europe have repeatedly found that improved energy efficiency would be more cost-effective than new power plants. A senior bank official says the least-cost studies will not be made public.

If the EBRD approves the Mochovce venture, Murphy denies that it automatically means that other nuclear plants in Eastern Europe will be upgraded. But Veaujour is optimistic. 'If we can start in Slovakia, we won't stop there.' The next step, he says, is to finish the nuclear plants Ukraine says must be running before it can shut Chernobyl.

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