BNFL closes old Sellafield reactors

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This is a tough but necessary commercial decision, BNFL’s Chief Executive Norman Askew said.
The four reactors 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.

Magnox problems
All together, BNFL is bringing forward the planned dates for cessation of generation at eight nuclear reactors. Four of these are located at the Sellafield site, representing the Calder Hall plant. The four other reactors, representing the Chapelcross nuclear power plant in Scotland and originally due to start closing in 2008, will now complete a progressive shut down by no later than March 2005.

According to BNFL, the company has been driven to this decision by the continuing low prices in the electricity market, as the income generated by the power stations no longer covers the costs of operation.

Both Chapelcross and Calder Hall are so-called Magnox reactors. BNFL’s announcement follows an economic review of the operation of its whole Magnox reactor fleet. According to the nuclear company, the larger stations have a sound economic basis, but Calder Hall and Chapelcross, with their low output but high overheads, had become loss-making.

Both Calder Hall and Chapelcross have been out of operation the last months after serious fuel handling accidents. Last summer, 24 spent fuel elements fell to the floor at Chapelcross. A similar accident happened at the Calder Hall plant in February.

Two other Magnox-reactors, at the troublesome Bradwell plant, where officially closed down this Easter, after the plant had suffered a series of technical problems.

The bomb producers
Calder Hall and Chapelcross were some of the first industrial reactors in the world, and both were crucial to the United Kingdom’s early nuclear weapons programme. BNFL’ s Chief Executive, Norman Askew, said: —We would continue to run these pioneering workhorses of the nuclear industry while they remain safe and economic. They are still safe but the electricity prices have fallen significantly and to a level that makes them uneconomic.

Calder Hall was opened by Her Majesty Queen Elizabeth II in 1956. Chapelcross began electricity production in 1969. In the 1950s the demand for weapons-grade plutonium was increasing, and together with the four new 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 at Calder Hall have allegedly produced more than two tonnes of weapons-grade plutonium.

16 reactors left
All together there are 16 Magnox reactors in Great Britain, all of them operated by BNFL. This is a special kind of nuclear reactor, cooled by carbon dioxide (CO2). The name Magnox is taken from the fuel used in the reactors. While most current reactors use fuel in the form of uranium oxide (UO2), Magnox reactors use uranium metal, which is encapsulated into a characteristic casing of magnesium oxide, hence the name Magnox.

The metallic fuel Magnox has caused major environmental and security-related problems. Uranium metal corrodes more easily in contact with water than the ceramic uranium oxide. In contact with water, metallic uranium decays into uranium oxide and uranium hydride. Both uranium metal and uranium hydride are phorphyritic, and therefore, corroded fuel represents a huge safety problem.
Today, BNFL reprocesses all the spent Magnox-fuel at the B205 reprocessing plant at Sellafield. It is the reprocessing of this fuel that generates the technetium-99 discharges from Sellafield.

In total there was built 26 Magnox-reactors. After Bradwell was closed down this Easter, 16 remain in operation. With the closure of Calder Hall and Chapelcross there will remain only eight.

Erik Martiniussen