Millstone changes how it measures radiation on workers

A federal regulator has authorized the owner of Millstone Power Station in Waterford to adopt a new method for measuring radiation exposure to workers. The decision by the Nuclear Regulatory Commission also applies to Dominion's fleet of reactors around the country. The approach, established by the Health Physics Society, uses gauges known as dosimeters to measure the dose of radiation a worker has been exposed to in seven different areas of the body, said Neil Sheehan, an NRC spokesman. The measurements are taken in plant locations where higher exposure is likely, he said. A second, traditional method, known as the “deep dose equivalent” measurement, involves using only one dosimeter to measure radiation across the whole body. That standard is used in areas on reactor sites that are not prone to high radiation, he said. In contrast, the HPS method pinpoints exposure to targeted areas of the body. If an employee was working below the reactor vessel during a fuel outage, the more pronounced exposure would be to the head and shoulders, for example, Sheehan said. The HPS approach is more consistent with state of the art procedures for measuring radiation exposure, said Sheehan, and as such, is more accurate. The NRC is considering the adopting the HPS method as a standard that any reactor owner could use. About one-third of the 104 operating commercial power reactors in the U.S. are now using the HPS approach, Sheehan said.

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