Last week, just before the United States began its recess for the July 4 holiday, the Nuclear Regulatory Commission (NRC) proposed a new rule that would change the way it regulates radiation exposure. The Trump administration has been pushing to restart construction of nuclear power plants in the United States, and many nuclear energy advocates have complained about existing regulations in the United States, presenting them as the main barrier to the industry flourishing. Therefore, it seemed likely that major revisions were coming.
Instead, the NRC’s proposed new rules support the science behind its current rules and suggest that any problems lie largely in the vagueness of the terminology it has been using. So instead, it supports standards that aim to achieve the same goal, but avoids using some of the language on which it was based. Probably the clearest indication of the evolutionary change at play is that the NRC estimates that the rule change will save the industry (not just energy, but also medical and research applications) only about $9.5 million a year.
LNT and ALARA
There are two technical abbreviations at the heart of US nuclear regulations. The first is LNT, which stands for “linear no threshold.” It concerns the question of whether there is any level of radiation that is so low that it no longer produces harmful biological effects: the “threshold” in LNT. “Non-threshold” implies that it doesn’t, and that’s in line with biology, which has shown that even single particles or photons of radiation can damage DNA and that the mechanisms cells have to repair that damage are inherently error-prone. The “linear” in LNT simply describes how the impact of radiation increases directly with dose.
