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August 02, 2011

N.R.C. Lowers Estimate of How Many Would Die in Meltdown

NY Times - The Nuclear Regulatory Commission is approaching completion of an ambitious study that concludes that a meltdown at a typical American reactor would lead to far fewer deaths than previously assumed.

The conclusion, to be published in April after six years of work, is based largely on a radical revision of projections of how much and how quickly cesium 137, a radioactive material that is created when uranium is split, could escape from a nuclear plant after a core meltdown. In past studies, researchers estimated that 60 percent of a reactor core’s cesium inventory could escape; the new estimate is only 1 to 2 percent.



The report is a synthesis of 20 years of computer studies and engineering analyses, stated in complex mathematical terms. In essence, it states that if a prolonged loss of electric power caused a typical American reactor core to melt down, the great bulk of the radioactive material released would remain inside the building even when the reactor’s containment shell was breached.

Big releases of radioactive material would not be immediate, and people within a 10-mile radius would have enough time to evacuate, the study found. The chance of a death from acute radiation exposure within 10 miles is therefore near zero, the study projects, although some people would receive doses high enough to cause fatal cancers in decades to come.

One person in every 4,348 living within 10 miles would be expected to develop a “latent cancer” as a result of radiation exposure, compared with one in 167 in previous estimates.

Dr. Lyman said the earlier estimate was of a different accident, a major pipe break. The new study considered that accident too unlikely to analyze.

Dr. Lyman suggested that in projections of fatal cancer cases, the focus should be on people who live within 50 miles. The average population within 10 miles of an American nuclear plant is 62,000; within 50 miles, it is about five million.

The commission’s old projection of eventual cancer deaths was one for every 2,128 people exposed within 50 miles; the new study projects one cancer death for every 6,250 people exposed, which still comes to hundreds of cancer deaths within the 50-mile circle, in addition to the hundreds of thousands who would be expected to die of cancer from other causes.

None of the work looks at further steps for improving mitigation in the most cost effective ways.

A large inflatable containment dome (maybe 2 to five inflatable domes) could be built and ready for deployment in the event of an incident at any plant.

This is similar to the plan for another Gulf of Mexico oil leak where they now have a large adjustable metal cap that be placed over any leaking oil pipe deep in the ocean. There are thousands of oil wells in the ocean and you never know where one could leak, so it is best to have a suitable but effective band aid/turnicate.

The responding solution matches the timeframe of the potential problem and the fact that there are 435 nuclear reactors in the world (with more being built). Rapid response containment would be able to prevent contamination. If the systems could be effective in fast containment then there might not be the need to evacuate.

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