Quantitative Health Objectives in a Performance-based Regulation

In January 2022, Adam Stein submitted the following white paper as a comment disagreeing with the use of Quantitative Health Objectives (QHO) as a risk metric for performance-based assessment. The NRC’s draft Part 53 rule aims to establish a modern, risk-informed, and technology-inclusive licensing framework to facilitate the approval and deployment of advanced nuclear reactors. This new regulatory approach, mandated by Congress through the Nuclear Energy Innovation and Modernization Act (NEIMA), is intended to replace older, prescriptive approaches with performance-based standards that accommodate innovative technologies without compromising safety. However, a significant point of contention surrounding the draft rule is the proposal to incorporate the QHOs as binding regulatory requirements.

QHOs were developed in the 1980s as high-level policy goals designed to express the Commission’s broad safety objectives in numerical terms. For example, one key QHO limits the risk of latent cancer fatalities to two in one million per year within the population surrounding U.S. nuclear plants. Importantly, QHOs were never intended as strict, enforceable regulations for individual facilities; rather, they serve as benchmarks to guide regulatory philosophy and risk communication. Over the decades, the NRC has consistently reaffirmed QHOs as policy guidance distinct from licensing criteria, letting dose limits, engineering requirements, and risk-informed oversight serve as the primary enforceable controls. The approach has balanced robust reactor safety with efficient regulation, encouraging technological innovation while maintaining high safety standards.

The core challenge with using QHOs as licensing requirements is scientific and practical. QHOs rely on projected cancer risks at very low radiation doses with levels far below the detection threshold of current epidemiological methods. The scientific consensus, reflected in studies by the NRC, the EPA, and the National Academies of Science, is that cancer risks from low doses cannot be reliably observed amid normal background variations.

The NRC sponsored a long-term, multimillion-dollar pilot study conducted by the National Academies to investigate cancer risks near nuclear facilities. Despite rigorous scientific design and extensive efforts, the study was ultimately canceled because it was unlikely to yield definitive, actionable results. Reliable detection of excess cancers at QHO levels would necessitate monitoring millions of individuals over multiple decades, a scale and duration incompatible with timely, effective regulatory review. QHOs are neither calculable nor measurable in a manner suitable for performance-based regulations, which demand metrics that can be objectively monitored to assure acceptable performance.

NRC guidelines on performance-based regulation require that metrics must be objectively measurable or calculable parameters that offer timely indicators of licensee performance and safety. Dose limits, engineering standards, and surveillance requirements satisfy these criteria by providing clear, enforceable thresholds based on physical measurement and operational control. QHOs, by contrast, are abstract risk targets constructed from probabilistic models with significant uncertainty, incapable of providing real-time performance feedback. Enshrining QHOs as licensing criteria risks increasing regulatory complexity and burdens by inviting disputes over modeling assumptions and imposing costly compliance demonstrations that add little or no demonstrable public safety benefit.

In addition to regulatory inefficiency, making QHOs enforceable could erode public confidence. The need for extensive and costly epidemiological studies to detect subtle effects implies a level of risk that could alarm the public unnecessarily, undermining trust in the NRC’s oversight. It also risks creating regulatory disparities and delays that disadvantage innovative reactor developers, impeding U.S. leadership in advanced nuclear technology at a time when clean energy development is critical for climate and energy security goals. The optimal path forward is to maintain the current, proven regulatory paradigm: use QHOs as high-level policy aspirations to guide regulatory philosophy and long-term safety vision, while relying on measurable dose limits, robust engineering criteria, and risk-informed, performance-based oversight for licensing decisions.