A fire at a nuclear reactor is serious business. There are many ways to trigger a nuclear accident leading to damage of the reactor core, which can result in the release of radiation. But according to a senior manager at the US Nuclear Regulatory Commission (NRC), for a typical nuclear reactor, roughly half the risk that the reactor core will be damaged is due to the risk of fire. In other words, the odds that a fire will cause an accident leading to core damage equals that from all other causes combined. And that risk estimate assumes the fire protection regulations are being met.
However, a dozen reactors are not in compliance with NRC fire regulations:
- Prairie Island Units 1 and 2 in Minnesota
- HB Robinson in South Carolina
- Catawba Units 1 and 2 in South Carolina
- McGuire Units 1 and 2 in North Carolina
- Beaver Valley Units 1 and 2 in Pennsylvania
- Davis-Besse in Ohio
- Hatch Units 1 and 2 in Georgia
Instead, they are using “compensatory measures,” which are not defined or regulated by the NRC. While originally intended as interim measures while the reactor came into compliance with the regulations, some reactors have used these measures for decades rather than comply with the fire regulations.
The Union of Concerned Scientists and Beyond Nuclear petitioned the NRC on May 1, 2017, to amend its regulations to include requirements for compensatory measures used when fire protection regulations are violated.
Fire Risks
The dangers of fire at nuclear reactors were made obvious in March 1975 when a fire at the Browns Ferry nuclear plant disabled all the emergency core cooling systems on Unit 1 and most of those systems on Unit 2. Only heroic worker responses prevented one or both reactor cores from damage.
The NRC issued regulations in 1980 requiring electrical cables for a primary safety system to be separated from the cables for its backup, making it less likely that a single fire could disable multiple emergency systems.
Fig. 1 Fire burning insulation off cables installed in metal trays passing through a wall. (Source: Tennessee Valley Authority)
After discovering in the late 1990s that most operating reactors did not meet the 1980 regulations, the NRC issued alternative regulations in 2004. These regulations would permit electrical cables to be in close proximity as long as analysis showed the fire could be put out before it damaged both sets of cables. Owners had the option of complying with either the 1980 or 2014 regulations. But the dozen reactors listed above are still not in compliance with either set of regulations.
The NRC issued the 1980 and 2004 fire protection regulations following formal rulemaking processes that allowed plant owners to contest proposed measures they felt were too onerous and the public to contest measures considered too lax. These final rules defined the appropriate level of protection against fire hazards.
Rules Needed for “Compensatory Measures”
UCS and Beyond Nuclear petitioned the NRC to initiate a rulemaking process that will define the compensatory measures that can be substituted for compliance with the fire protection regulations.
The rule we seek will reduce confusion about proper compensatory measures. The most common compensatory measure is “fire watches”—human fire detectors who monitor for fires and report any sightings to the control room operators who then call out the onsite fire brigades.
For example, the owner of the Waterford nuclear plant in Louisiana deployed “continuous fire watches.” The NRC later found that they had secretly and creatively redefined “continuous fire watch” to be someone wandering by every 15 to 20 minutes. The NRC was not pleased by this move, but could not sanction the owner because there are no requirements for fire protection compensatory measures. Our petition seeks to fill that void.
The rule we seek will also restore public participation in nuclear safety decisions. The public had opportunities to legally challenge elements of the 1980 and 2004 fire protection regulations it felt to be insufficient. But because fire protection compensatory measures are governed only by an informal, cozy relationship between the NRC and plant owners, the public has been locked out of the process. Our petition seeks to rectify that situation.
The NRC is currently reviewing our submission to determine whether it satisfies the criteria to be accepted as a petition for rulemaking. When it does, the NRC will publish the proposed rule in the Federal Register for public comment. Stay tuned—we’ll post another commentary when the NRC opens the public comment period so you can register your vote (hopefully in favor of formal requirements for fire protection compensatory measures.)