Only a moth after BNFL announced they would close down the Calder Hall Nuclear power plant, in March next year, three of the four reactors are already closed down. The four reactors was originally due to start closing in 2006. Now the company admits that three of the four reactors never will operate again. The last reactor will be closed in eight months’ time.

Safety problem
According to the locally based newspaper Whitehaven-News it its no longer viable to run all four reactors due to the cost of preventing radiation-induced graphite shrinkage – a potentially serious problem which develops in the chargepans used to guide the highly-radioactive fuel rods into place.

Calder’s sister station at Chapelcross in Scotland has already experienced the chargepan problem. On July 5. 2001, problems arose when a container with 24 used fuel rods hit the floor at the Chapelcross plant. Quick reactions from staff prevented a major nuclear fire. As a result of this accident, BNFL introduced a temporary halt of all fuel transmitters at Chapelcross and Calder Hall, which both use the same systems to transmit fuel.

As a result Calder Hall was shut down for about six months while investigations where carried out and it was estimated to be costing BNFL an £30,000 per day in lost production for each reactor.

No solution
Reactor 1 was returned to power last month and BNFL planned to bring Reactor 4 and possible Reactor 2 back on line as well. However BNFL announced this week: ”This plan relied on developing an engineering solution to the chargepan issue first identified in the one of the Chappelcross reactors. This solution will not now be ready on a timescale that will make it economically practical to return them to service before next March”.
 
Reactor 3 is already shutdown for maintenance ant this will not be re-started either.  
 
A Sellafield-spokes-man told Whitehaven-news it was practical to operate Reactor 1 because, having been off line for a time in earlier years, its core had not been exposed to as much radiation.

Investigations though showed there has been some movement in the reactor chargepan.  
 
Magnox-reactors
The four reactors at Calder Hall where opened by Her Majesty Queen Elizabeth II in 1956. It was the world’s first industrial-scale nuclear power station, and crucial to the United Kingdom’s early nuclear weapons programme.

In the 1950s the demand for weapons-grade plutonium was increasing, and together with four reactors at Chapelcross in Scotland, the reactors in Calder Hall were to supply the necessary quantity of weapons-grade plutonium. It is assumed that two of the reactors at Calder Hall were utilised to produce weapons-grade plutonium in 1978 and 1979. Moreover it is believed that as recently as 1986-1989, the reactors produced 400 kilograms of weapons-grade plutonium, which was reprocessed in B205 and delivered to the British Army. In sum, the four reactors have allegedly produced more than two tonnes of weapons-grade plutonium.

The reactors at Calder Hall were the first of a new generation of British reactors that later came to be called Magnox reactors. In total, 26 such reactors were built in the United Kingdom. Except for Calder Hall and its sister power plant, Chapelcross, all of the reactors were constructed in the period between 1960 and 1970.

With the closure of Calder Hall and Chapelcross, only eight Magnox-reactors will remain in operation. Chapelcross, originally due to start closing in 2008, will now complete a progressive shut down by no later than March 2005.