A failure of these welds could have lead to a significant release of radioactivity into the environment, putting people's health at risk.
Magnox reactors, like the one at Wylfa, are the oldest operating commercial reactors in the world. They were originally designed to run for 20 to 25 years: they are now between 30 and 45 years old. They are owned by the Nuclear Decommissioning Authority and operated by a contractor, British Nuclear Fuels (BNFL), who also operate the infamous Sellafield nuclear site in Cumbria.
The reactors have a history of design and technical problems. As the reactors age, these problems become more acute and are in many cases irreparable. Even the industry's own safety regulator admits that, were these reactors to be built today, they would not be licensed as safe to operate.
The NII was concerned that the defective welds could break open, releasing radioactive contents from the reactor. They asked BNFL to fit 'restraints' to the outside of the pressure vessel to limit radioactive releases if the welds did break open. The welds themselves were never repaired.
The NII allowed BNFL to restart Wylfa in August 2001 despite a high degree of public concern and opposition.
Greenpeace commissioned nuclear engineer John Large to report on how ageing processes might influence safety at Wylfa. His full report can be found here. More documents related to the campaign can be accessed below.
Campaign Documents
English Language Summary
Welsh Language Summary
Wylfa Nuclear Power Stations and the National Assembly for Wales
