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FRANCE’s image as the world’s leading nuclear nation has been taking
a beating recently. Even before last week’s leak of the Rouvillois report
(see above), which criticised the decisions leading to the country’s present
overcapacity, the president of the country’s electricity supply company,
Electricite de France, had admitted that last year had been ‘disastrous’
from a financial point of view.

Coming on top of all this has been a warning from Pierre Tanguy, chief
inspector for nuclear safety at EDF, about the implications of recent technical
failures at several French nuclear power stations. In a separate report,
published in Paris last week after a member of the French Green Party had
obtained a copy, Tanguy estimates the risk of a serious accident at one
of these stations as being ‘several per cent’ over the next 20 years.

More than 70 per cent of France’s electricity is generated by nuclear
power. EDF finished last year with a deficit of 4 billion francs (Pounds
sterling 400 million), according to its president, Pierre Delapote. One
reason was the lengthy drought, which is being held responsible for the
loss of fr3.1 billion; hydropower output was severely reduced, and several
nuclear plants had to be temporarily shut down because river water was too
warm for effective cooling.

Almost as costly, however, have been the technical problems encountered
with France’s 1300-megawatt reactors, which have resulted in an estimated
loss to EDF of fr4 billion over the past three years.

The generic faults discovered last year are likely to cause continuing
problems. France runs 34 900-MW reactors, and 14 at 1300-MW, each size being
built to a common design; eight large reactors are still under construction,
despite the evidence that France already has more nuclear power than it
needs.

Building the reactors to a common design has helped to cut costs. But
the drawbacks of this strategy have become obvious whenever a major design
error or material fault has found itself multiplied throughout the country’s
nuclear plant.

A typical example has been damage to tubes in steam generators. In April
last year, for example, about 100 such tubes were found damaged in two of
the four steam generators of the Nogent-1 reactor outside Paris. The problem
was the result of corrosive metallic sludge, which had apparently caused
denting of the tubes.

The same phenomenon was later identified at other 1300-MW reactors.
No one has yet been able to identify the origins of the sludge, which leads
to corrosion, cracking and eventually rupturing of the tube. EDF says it
is still ‘mystified by the widespread tube denting’, according to the newsletter
Nucleonics Week.

Michel Laverie, chief of the French safety authority, SCSIN, calls the
tube blockages ‘a technical problem which is easy to handle on the safety
level’. But he admits that they will have a heavy financial impact, both
in terms of repair costs and lost generating time.

As a result of stringent new restrictions imposed by SCSIN, for example,
the reactor Nogent-2 was shut down for a month last autumn to allow a tube
to be plugged after a leak of 3.1 litres per hour had been detected. Nogent-1,
where the tube problem was first discovered, remained shut for almost eight
months before coming back on line on 2 January this year – only to be shut
down again two days later for another six weeks.

None of these technical problems is considered to be particularly serious.
However, since the Chernobyl accident, France’s nuclear authorities have
become aware of the public’s increasing sensitivities to the dangers of
nuclear power.

‘I do not feel that the safety of EDF’s nuclear power stations has been
seriously challenged,’ says Tanguy in his report. ‘However, we must admit
that several operational incidents have occurred over the past 12 months
which deserve serious consideration,’ he says.