金沙开户注册官网:Lid blown off Dounreay's lethal secret

2019-02-28 05:02:10

By Rob Edwards EARLY in the morning of Tuesday 10 May 1977 there was a loud explosion at the Dounreay nuclear plant on the north coast of Scotland. The UK Atomic Energy Authority, which runs the plant, had dumped at least 2 kilograms of sodium and potassium down a 65-metre shaft packed with radioactive waste and flooded with seawater. The results were dramatic. The sodium and potassium reacted violently with the water. The explosion blew off the shaft’s huge concrete lid, threw its steel top plate 12 metres to one side, badly damaged the 5-tonne concrete blocks at the mouth of the shaft, and blasted scaffold poles up to 40 metres away. An eyewitness reported a plume of white smoke blowing out to sea. And, as government watchdogs revealed for the first time last week, the ground around the shaft was littered with radioactive particles hot enough to injure and kill. Over the past 18 years, almost 150 such particles have been found on Dounreay’s beaches. The accident is the most serious ever at Dounreay, and the particles it spewed out perhaps the most dangerous ever released by the British nuclear industry. Despite this, the Scottish Office’s Industrial Pollution Inspectorate is reluctant to prosecute Dounreay because it fears it may not be able to prove that the plant was the source of the particles, even though the UKAEA itself does not deny it. But the government’s Nuclear Installations Inspectorate says it is investigating the possibility of legal action. In 1987 the UKAEA was asked by the Committee on the Medical Aspects of Radiation in the Environment (COMARE), which advises the Department of Health, to list all its “unplanned discharges” from Dounreay. This was part of its investigation into a cluster of cases of childhood leukaemia around Dounreay. The UKAEA made no mention of the explosion, on the grounds that nothing dangerous had ended up beyond its fence. But the UKAEA’s internal “incident reports” immediately after the explosion – the contents of which were revealed only last week – say that contaminated “items” were retrieved from outside the site boundary. In 1987, COMARE also asked where the radioactive particles found on the foreshore had come from. The UKAEA claimed that they had leaked from a damaged storm drain containing the remains of a radiation spillage from 1965, although this was only one of several theories being considered at the time. The UKAEA told COMARE that the Industrial Pollution Inspectorate had concluded that “in radiological terms the protools gave no grounds for concern”. But according to Tom Wheldon, head of COMARE’s special beach contamination working group, “if you ingested one of the hottest particles and it lodged in your gut, you would probably be dead from gastrointestinal burns within the week”. Elsewhere in the body, most of the particles could irradiate the bone marrow enough to significantly increase the risk of leukaemia. One of the particles that has been found contained 200 million becquerels of radioactivity, while the majority ranged between 1 and 10 million becquerels. In a report published jointly with the Radioactive Waste Management Advisory Committee (RWMAC) last week, COMARE says that a single particle contained as much radioactivity as the total that the UKAEA originally claimed had leaked. COMARE criticises the UKAEA’s lack of “rigorous scientific investigation” and expresses doubts about its “veracity”. However, Dounreay’s director, John Baxter, insists that there was never any intention to mislead. For its part, the RWMAC concludes that the waste shaft, which was used between 1959 and 1977 to dump unknown amounts of radioactive debris such as irradiated fuel elements and contaminated glove boxes, is “not an acceptable model for the disposal of radioactive waste”. The committee suggests that the UKAEA should retrieve, repackage and dispose of the waste elsewhere “over a relatively short timescale”. This conflicts with a report commissioned by the Scottish Office in 1990 from R. M. Consultants of Abingdon, which says that such an operation would be “without precedent, costly and potentially dangerous”. The UKAEA, which is reviewing what to do, says it could cost up to £200 million and take more than 10 years. The consultants’ report also warns that the possibility of an other sodium-potassium-water reaction “cannot be ruled out”. The particles found on the beach are typically a millimetre across and contain uranium, aluminium, caesium and plutonium. They were originally part of fuel elements used in Dounreay’s Materials Testing Reactor in the 1960s (This Week, 26 November 1994). Swarf from milling the elements was poured into small screw-top aluminium cans, which were then dropped down the waste shaft. Every year since 1983, the UKAEA has found an average of 12 particles on the Dounreay foreshore, a rocky area which until recently was accessible to the public. In 1984, one particle containing 100 000 becquerels of radioactivity was found on Sandside Beach, an attractive bay west of Dounreay often visited by the public. Although COMARE believes that there could be more particles there, it regards the likelihood of any member of the public coming in contact with them as “very small”. It concludes that the particles are “most unlikely to explain the observed excess of childhood leukaemia in the Dounreay area”. However, there was no comprehensive monitoring for particles at Sandside until seven years after the explosion. The RWMAC believes these particles are worn away by sand after two or three years. Wheldon points out that if the kind of particles found on the Dounreay foreshore had been present on Sandside Beach, they would easily explain the excess in the number of cases of childhood leukaemia. It is, he says,