Reducing radiological exposure: Dominion Engineering’s president weighs in

Defining CRE: Marks kicked off his presentation by defining collective radiation exposure (CRE) as an industry metric for radiation exposure of plant personnel. He noted that between boiling, pressurized, and light water reactors, the average collective dose has decreased significantly over the past two decades—though that progress has stalled in the past ten years.

As such, the industry is currently looking for new methods and technology to overcome this plateau and continue driving CRE even lower.

Source term: The basic strategy for mitigating CRE is increasing distance, increasing shielding, and decreasing time spent near a source. Marks acknowledged the value of these measures but said they ignore the fact that source term (the magnitude and mix of the radionuclides released from the fuel) can itself be lowered. So, Marks explained, if source term mitigation is pursued alongside distance, shielding, and time, “all those measures become more effective, and you need less of them to achieve the same benefit.”

He added that reductions in source term can provide unique benefits that other methods cannot provide. “For example,” he explained, “if there is extended time to do a repair or maintenance activity within a radiation field, lowering the source term protects you against that, even if it is unanticipated.”

In discussing how to go about reducing source term, Marks said that it is a job that overlaps with almost every department in a nuclear power plant. “There are chemistry aspects, there are operational aspects, [radiation protection] obviously needs to be involved,” he said. Other departments involved include procurement, outage management, and reactor engineering.

Considering the multidisciplinary complexity of the job, source term mitigation always starts with a technical assessment that is benchmarked against similar plants and can be achieved through a variety of methods and technologies.

Go deeper: To hear more about those technologies, watch the full webinar on ANS’s YouTube channel.