Closing the Gap on Greater-Than-Class-C Waste

The United States has gone nearly four decades without a generic licensing pathway for disposing of Greater-Than-Class-C (GTCC) radioactive waste. The NRC’s proposed Integrated Low-Level Radioactive Waste Disposal rule would finally begin to close that gap, allowing certain waste that exceeds the existing Class C concentration limits to be evaluated for land disposal through site-specific, dose-based criteria rather than relying only on waste classifications developed decades ago. BTI supports the rule's efforts to remedy this gap. 

GTCC waste sits between ordinary commercial low-level radioactive waste and spent nuclear fuel. GTCC is also not a single, uniform category of waste. Different waste streams, disposal sites, engineered barriers, and geologic conditions can produce very different risks. The proposed rule recognizes that reality by allowing licensees to develop site-specific waste acceptance criteria supported by a performance assessment, while also requiring a safety case and defense-in-depth. BTI supports those tools, but recommends clearer boundaries around how they are applied so that a flexible framework does not become an open-ended one.

BTI's principal concern is how the rule treats defense-in-depth. The NRC says every credited layer of defense should make a definite contribution to isolating waste, but the proposal does not establish a way to determine when a barrier is adding little or nothing to safety. That especially matters for disposal analyses extending 10,000 years or more, where some uncertainty cannot realistically be eliminated through more testing or site characterization. Without a stopping point, uncertainty can continually justify adding more barriers even when the modeled safety outcome does not materially improve.

Ultimately, the rule cannot be finalized in isolation. Several concurrent NRC rulemakings amend the same regulations and cross-reference one another. The rule also needs greater clarity about who licenses GTCC disposal and how states participate. 

The NRC has an opportunity to replace a longstanding licensing gap with a workable, risk-informed disposal framework. Doing so requires more than creating a new pathway: the final rule should make clear where regulatory requirements begin and end, how federal and state responsibilities fit together, and how the new framework interacts with the rest of the NRC’s regulatory overhaul.