Engineering news
Nuclear experts have played down the chances of an incident similar to that taking place at the Fukushima plant in Japan ever occurring on these shores.
Workers at the stricken Japanese nuclear plant are frantically attempting to cool down the reactors at the plant following the earthquake and tsunami, which damaged the power stations and led to a series of blasts and fires.
As the world waits for an outcome at Fukushima, Keith Parker, chief executive ofthe UK’s Nuclear Industry Association, stressed that UK plants had been designed and built to withstand seismic activity well above and beyond anything ever experienced here.
He said: “The chances of a similar earthquake and tsunami happening in Northern Europe are thankfully extremely remote. The science behind these assumptions is well understood. To put it into perspective the largest-ever recorded earthquake in Northern Europe is many thousand times smaller than the earthquake in Japan.
“All UK operating plants are seismically qualified and are built or modified to withstand seismic activity well above and beyond anything ever experienced in the UK.
“Independent nuclear regulation in the UK is extremely stringent. The regulator has said that it is confident that the UK’s fleet of nuclear power reactors and operators are prepared appropriately for any seismic activity that could be anticipated in the UK.”
At Fukushima, workers who were dousing the reactors with sea water were withdrawn after radiation levels became too high, but they have since returned to carry on the work. Dr Ian Haslam, head of radiation protection at the University of Leeds, said moving the workers away from the plant after more radiation leaked from the site was a “desperate measure” in response to dangerously high levels of radiation. But he said the danger of radiation was a local issue.
Laurence Williams, professor of nuclear safety at the John Tyndall Institute for Nuclear Research, said measures of radioactivity outside the plant were not significantly raised.
He also said levels had spiked, allowing workers back in, which suggested that the higher radiation was the result of another release of radioactive steam beingvented from the reactor to relieve pressure - rather than sustained releases from a damaged core.
Water is being pumped into the reactor to cool the nuclear rods but high temperatures are leading to high pressures of steam and gas which need to be released.
Williams said there was no sustained release of radioactive material, which showed the Japanese workers were doing a good job of controlling what was happening at the plant.
“The longer they can keep some degree of cooling past the fuel rods, sooner or later the temperatures will get to a level where they can flood the core with water,”he said.
Currently temperatures are too high to flood the reactor as the water would just turn tosteam, but when they can, it will effectively shut the reactor down and give the company time to decide how to eventually decommission the ageing plant.
He said: “We’ve got a few critical days. If you can keep this going for two,three, four days, as soon as you can remove more heat than is being produced, temperatures come down and you can flood the core.”
Energy secretary Chris Huhne has asked the chief nuclear inspector, Dr Mike Weightman, to produce a thorough report on the implications of the situation in Japan and the lessons that can be learned from it for this country. Huhne is expecting an interim report by mid-May and the final review to be completed within six months.
Last year the government gave the green light for eight sites for new power plants to supply nuclear energy, which currently provides 18% of the UK’s electricity. The Health and Safety Executive and the Environment Agency are currently compiling the generic design assessment of the safety cases for the two reactor designs under consideration – Areva’s UK European Pressurised Reactor and Westinghouse’s AP1000. That work, which has been ongoing for the past couple of years, is expected to be completed by 30 June.
But the events at the Fukushima plant have prompted UK green groups to call for a rethink on the plans and for ministers to focus on renewable power to cut greenhouse gas emissions and secure energy supplies.