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Thursday, 1 November, 2001, 22:21 GMT
Nuclear industry 'prepared for attacks'
The nuclear industry believes the fears about terrorist strikes on power stations and their ability to withstand such assaults have been overstated.
They say the level of over-engineering that has gone into the construction of western power stations means their reactor cores are unlikely to be exposed, even if the buildings in which they are housed take a direct hit from a plane.
The robustness of such engineering was demonstrated in 1989 when, in a joint US-Japanese crash test, a F-4 Phantom jet was flown at 800 km/h, straight at a concrete block. The plane, which completely disintegrated, penetrated just a few centimetres into the four-metre-thick block.
Critics, however, have pointed out that the energy imparted by a passenger jet fully laden with fuel would be considerably greater than that from the impact of a fighter-bomber.
One calculation in the aftermath of the 11 September attacks suggested the kinetic energy of the planes that hit the World Trade Center totalled about two billion joules (one joule is roughly the energy it takes to lift an apple from the floor to table height).
The energy released by the burning aviation fuel was 10 times as great again.
Nevertheless, the industry is confident - publicly at least - that the reactor buildings themselves would stand up well.
Defence in depth
Clearly, some power stations would fair better than others; not all plants are built to the same design.
US reactors are typically protected by an outer shell, or containment building, made of steel-reinforced concrete more than a metre thick. This shell will also have a steel lining about 10 centimetres thick.
The reactor itself will be inside a pressure vessel made from steel perhaps up 30 centimetres thick. The fuel at the heart of the power station will be encased in zirconium alloy rods.
This is the so-called defence-in-depth safety strategy. It also means nuclear plants must be able to protect themselves from direct assault by armed groups who might want to force their way into a power station and set off a bomb.
In Europe, governments have been very reluctant to divulge the details of extra security measures implemented at nuclear facilities after the 11 September attacks.
France, which has the largest nuclear programme in the EU, made the high-profile statement of placing ground-to-air missiles near the plant at La Hague. France said it was prepared to use warplanes to shoot down hijacked aircraft.
In the UK, last weekend, two Tornado fighter jets were reported to have been scrambled to patrol the sky above the Sellafield plant in northwest England for several hours in response to a telephone threat.
La Hague and Sellafield could be prime targets for terror groups because they store waste fuel, which has more concentrated, higher levels of radioactivity.
British Nuclear Fuels Limited (BNFL), which operates Sellafield, declined to comment on its security arrangements on Thursday but said it had put in place whatever measures were required by the nuclear watchdog, the Office for Civil Nuclear Security (OCNS).
"We do what we're told by our regulator. For security reasons, we cannot give details of measures taken," said a BNFL spokesman.
Last month, when it was asked to comment directly by New Scientist Magazine on the possibility of a plane strike on the Sellafield complex, BNFL said: "Major nuclear facilities, including for example reactors and highly active waste stores, are constructed to extremely robust engineering standards and incorporate large quantities of reinforced concrete as an integral part of the construction."
It added: "These facilities are resistant to many terrorist threats including aircraft impact. Safety cases and contingency plans take these events into account."
But John Large, an independent nuclear consultant in the UK, believes the nuclear industry is making claims about the integrity of its buildings it cannot possibly support.
"Some of the British plants are now 40 to 50 years old. Back then a direct terrorist attack with an aircraft would have been inconceivable. And even in the 50s and 60s when [the plants] were designed and built, aircraft were much smaller, the fuel loads were much smaller, so they do not have built-in features that are resistant to aircraft crashes."
However, Mr Large said a would-be suicide pilot would still need information about the most vulnerable parts of a power station to hit, and he suggested that it would be prudent if public access was temporarily denied to detailed plans on nuclear installations until a thorough security review had been carried out.
The IAEA said there should be better control over radionucleotides used in medical, industrial, and food processing equipment.
The concern is that this material could be used to make so-called "dirty bombs", in which radioactive isotopes are mixed with conventional explosives. These bombs would not cause nuclear explosions, but could distribute radioactive debris over a wide area.
"The effects of a dirty bomb would not be devastating in terms of human life. But contamination in even small quantities could have major psychological and economic effects," said IAEA official Abel Gonzalez.
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