Dangerous design flaw puts future of key nuclear plant in doubt

Is British Energy putting cash before safety?

Investigations by Greenpeace show that the Heysham 2 nuclear plant in Lancashire is facing the same technical problems which have shut both reactors at its sister plant in Torness, Scotland. The problems have been developing over the past decade. The closure of Heysham 2 would cause a further financial shockwave to British Energy which has already suspended trading of its shares and is seeking a massive cash injection from Government. Greenpeace has discovered that Heysham 2 has a history of technical problems with gas circulator impellers [1] - exactly the same problem which has shut Torness. Given that both plants were built by the same company to the same reactor design [2] it has to be assumed that the same technical problems which closed Torness must apply to Heysham 2. Greenpeace has called for the Heysham 2 plant to be closed immediately.

"All the evidence points to Heysham sharing the same design flaw as Torness", said Greenpeace campaigner Emma Gibson. "Why, when both stations are known to suffer from the same problems, is one of these stations running whilst the other is closed? Public safety must come before the financial interests of British Energy. If British Energy won't shut the plant immediately then the Government must intervene to avoid a serious accident."

It is predicted that Torness will be shut for between 6 months and a year at an equivalent cost of half a million pounds a day. The cost of rectifying problems is estimated to be £5 million. In addition, British Energy's Dungeness B in Kent is also currently shut down for unrelated repairs. Together Torness and Dungeness B represent a quarter of British Energy's generating capacity. The additional closure of Heysham 2 (13% of British Energy's capacity) would be another financial disaster for the company.

Torness and Heysham 2 are advanced gas cooled reactors (AGRs) [3] with each station having two reactors, each with 8 gas circulator fans (16 for each station). The 2 metre diameter x 8 metre long metal fans are powered by 7,000 horsepower electric motors and spin at 3,000 revs per minute, pumping carbon dioxide gas at high pressure around the reactor to keep it cool. The circulators are located around the base of the reactor just below the fuel core.

The recent Torness failure involved one incident where a 70kg (150lb) section of the impeller blade sheared off one of the fans probably due to metal fatigue or cracking. Similar unpredictable failure of fan blades or other debris breaking away and being projected into the reactor could lead to a serious release of radioactivity through:

• breaching the reactor boiler system, releasing tonnes of water into the reactor, causing an abrupt pressure change that damages the reactor core;
• the disintegration of the circulator, releasing lubricating oil into the reactor circuit and leading to a fire in the graphite core;
• circulator breaking loose and severely damaging the reactor pressure containment leading to a collapse of reactor pressure, failure of the fuel cladding and a massive radioactive release into the reactor building and beyond.

Nuclear safety expert John Large said, "This is a type of fault which means that every reactor that uses these circulators is at risk. Debris becoming detached could lead to events such as overheating of the reactor fuel and uncontrolled radioactive release to the atmosphere. I am astonished that the NII is content to let Heysham 2 continue in operation under the shadow of such risk".

Greenpeace has written to the Nuclear Installations Inspectorate (NII) raising a series of questions about safety at Heysham 2 and Torness, and to Patricia Hewitt, Secretary of State for Trade and Industry, asking her to take action [4].

Notes to editors:

1. Chronology of Gas Circulator problems at Torness and Heysham 2:
   
   • Now: Torness reactors 1 & 2 shut down. Heysham 2 reactors operating
   • Aug 2002: Torness reactor 1 taken out of service
   • Jul 2002: Gas circulator replaced in Heysham 2
   • May 2002: Torness reactor 2 shut down
   • Feb 2001: NII identifies problem with Torness circulator but not the cause. Yet allows the reactors to continue in service
   • 1997: Heysham 2 gas circulator replaced
   • 1995: Heysham 2 gas circulator suffers unexplained vibration problem
   • June 1994: 4 gas circulators replaced in Heysham 2
   • 1992-1994: Heysham 2 gas circulators suffer unexplained vibration problem

   
   
   Sources: Nuclear Installations Inspectorate & British Energy
   
   

2. The prime contractor for the design and build of Torness & Heysham 2 was the National Nuclear Corporation. Gas circulators for both stations were supplied by James Howden & Company Limited (Renfrew). The stations were built between 1979-88.
   
   
3. All the AGR reactors in UK are owned by British Energy, they are:
   Hinkley Point B (Somerset), Hunterston B (Ayrshire), Dungeness B (Kent), Hartlepool (Cleveland), Heysham 1 & 2 (Lancashire), Torness (East Lothian).
   
   
4. Download copies of letters to the NII and Patricia Hewitt are available