Third quarter of 2001
The Safety authority gives the green light for the
re-start of Cattenom 3.
(12 pages, 97 Ko)
WISE-Paris, 28 September 2001
After a 7-month shutdown, during which the Operator
discovered damage to the fuel on a scale that had never been experienced
before on any French reactor, Unit 3 at the Cattenom nuclear power station
restarted on 9 September 2001. France's Nuclear Safety Authority actually
gave the green light for its restarting on 31 August 2001, despite the
fact that the enigma of the phenomenon that caused the damage has not
been solved yet.
After intervention by members of the parliament
of Luxembourg, Luxembourg's Minister of Foreign Affairs stressed to
the French authorities "that a meeting of the Joint Franco-Luxembourg
Commission on Nuclear Safety should be convened as quickly as possible."
In all, 92 fuel rods -containing uranium and constituting
the first level of containment of radioactive material- were damaged.
Some were completely broken, allowing radioactive material to be disseminated
into the primary cooling fluid. This represented a "first"
in the numbers of sealing faults, given that five to ten faults are
observed on average per year in all of the 58 reactors in the France.
The usual annual figure of 0.1 rods was multiplied by 1000.
Serious damage to fuel elements can lead to risk of
jamming of the control rods and therefore to loss of control of the
chain reaction, with potentially grave consequences for reactor safety.
In October 1999, just a month after restarting of the reactor, an abnormal
level of radioactivity was detected in its primary cooling water and,
on 6 September 2000, the "Serious Cladding Failure" level
was reached. The safety authorities were only informed of this situation
on 18 October 2000, a delay judged "inadmissible" by the authorities.
In spite of the high level of leakage and recommendations
from the safety authorities to bring forward shutdown of the reactor,
the management of the Cattenom power station preferred to keep it running.
Prior to shutdown of the reactor, the power station's management was
unable to provide an accurate assessment of the number and gravity of
faults. This error of foresight will have long-term repercussions, especially
for radiological protection and management of the Unit 3 buildings.
Several hypotheses have been put forward to explain the appearance of
these faults. In addition to wear and vibration, the presence of a possible
"migrating body" or even the possibility of a "manufacturing
defect" have been suggested. And, while "the immediate cause
linked to vibration fatigue" has been identified, this does not
make it possible to "confirm or exclude potential factors with
In parallel with this situation, EDF informed the
Safety Authority, on 12 March 2001, that it had detected a generic fault
in valves in the emergency cooling system in 12 reactors in the 1300
megawatt-of-electricity (MWe) series (including those of Cattenom);
a fault that could affect their satisfactory operation in case of accident.
More precisely, this flaw affected the re-circulation system supplying
the emergency spray and injection systems, of fundamental importance
in the concept of nuclear safety. EDF's analyses led to the conclusion
that there was a risk of jamming in case of "serious accident or
Shortcomings in the area of nuclear safety on EDF
sites, characterized by a "persistent lack of rigor" have
been observed on numerous occasions by the Safety Authority. The case
of Cattenom appears to constitute a serious example.
To download the briefing in English: 010928BriefCAT-v1-Ang.pdf
(12 pages, 97 Ko)
To download the annexes in French : Part
1 (12 p., 550 Ko) and Part
2 (10 p.,711 Ko)