Panic on the 18th Floor?

, senior scientist | April 9, 2011, 4:42 pm EDT
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Several years ago the Nuclear Regulatory Commission started a research program known as the “State of the Art Reactor Consequence Analyses,” or SOARCA, which I discussed in a post on April 6. SOARCA’s mission is to assess the consequences of “severe accident scenarios” at nuclear power plants that might release radioactivity into the environment.

UCS has long been concerned that the NRC imposed constraints on the SOARCA program that would significantly skew its results to ensure an outcome suggesting the public has little to fear from severe nuclear plant accidents. In 2006, to bolster confidence in the process, UCS requested that the NRC publicly release its guidelines for the program, the constraints it imposed on it, and the assumptions underlying the program’s assessment of accident scenarios as well as its justifications for them.

The NRC refused to release that information, despite the fact that the NRC plans to make SOARCA’s results public and, earlier in 2006, NRC Commissioner Gregory Jaczko—now the agency’s chairman—called for the agency to release the material UCS requested.

UCS just discovered from a new set of FOIA documents that in March 2010 Chairman Jaczko again asked the NRC to release the SOARCA materials. The agency still has not done so.

One reason UCS questioned the SOARCA process was that around the time the program was created, NRC staff and at least one commissioner repeatedly asserted that a previous study of this type—the 1982 Calculation of Reactor Consequences (CRAC2) study conducted by Sandia National Laboratory—overstated the potential severity of nuclear accidents. UCS was concerned that the NRC may have shaped the SOARCA study to produce results that cast the nuclear power industry in a more positive light.

For instance, in 2007, an NRC staff member provided preliminary SOARCA results to the Advisory Committee on Reactor Safeguards (ACRS) that concluded a long-term station blackout at the Peach Bottom nuclear power plant in Pennsylvania would result in zero early fatalities from acute radiation exposure and zero latent cancer fatalities if new “B.5.b” safety measures were taken into account (see April 6’s post). If these measures were not included, the preliminary results found, there would still be zero early fatalities, and 25 latent cancer fatalities.

The staff member pointed out that these were far fewer fatalities than were projected by the 1982 CRAC2 study, which found 92 early fatalities and 2,700 latent cancer fatalities. These results differ by so much one would expect the NRC to fully explain what changes in the analysis or assumptions in the SOARCA assessment led to such a different estimate. But it did not release the underlying details of the analysis.

Notes from this same 2007 meeting show that ACRS participants questioned the restrictions the NRC placed on SOARCA’s analysis of accident scenarios. The notes state that although the NRC staff agreed that a more comprehensive analysis of the kind the ACRS participants recommended “would certainly be desirable, performing such a study would go well beyond the scope described in the Commission’s Staff Requirements Memo” that set the terms of SOARCA analysis. This implies that the ACRS participants at that meeting, like UCS, were concerned about the limits the NRC placed on SOARCA.

The ACRS participants also called into question how the SOARCA program was including the potential for human errors in its analysis, and asked for additional justification for the number used in the analysis of the probability of core damage, which is central to the study because it is used to screen out the consideration of accidents that the NRC asserts are too improbable.

NRC staff members have consistently maintained that SOARCA has determined that there would be no fatalities from acute radiation syndrome under any circumstances from severe accidents. So it was notable that one of the emails the NRC released in response to UCS’s February FOIA request indicated that talk of SOARCA’s analysis finding a non-zero number for such fatalities caught some NRC staff members’ attention and set off some alarms. In a February 3, 2011, email, a member of the NRC staff expressed consternation about a recent development in SOARCA:

[T]hanks for the status update. I had heard unconfirmed information that [the NRC Office of Research] was now suggesting that there is some increase to the estimated hypothetical number of fatalities (early or late?) from some of the SOARCA assessed scenarios. If true, this would be a change from previous results that our office would like to know about well before the staff publishes the SOARCA report for public comment.

A few days later, the staff member had his answer, and notified the commissioner he works under:

FYI: I mentioned last week that the SOARCA project has some emergent issues. A number of “120” early fatalities has circulated up here on 18 [the 18th floor of One White Flint North, NRC’s headquarters]. I will find out more but my sense is any number above zero for acute radiation syndrome effects would be suspect.

These emails might be construed as a staff member simply wondering why the new results seemed out of line with the old results. But in light of the discussion above and our concerns about the SOARCA program, it sounds to us like the kind of meddling by the politically appointed NRC in the work of the agency’s Office of Research that we suspected was happening all along.

The email quoted above goes on to say that a number of early fatalities “above zero” would be suspect because Chernobyl led to fewer than 120 early fatalities. Such a comparison, however, is not relevant.

The modeling code used by SOARCA calculates doses received by people off-site, based on timing of the release, plume modeling, population characteristics, and evacuation modeling. The studies do not estimate risks to on-site personnel. Thus the number of fatalities among Chernobyl emergency worker is not directly comparable with the early public fatalities SOARCA computed.

And why might one expect off-site residents to die from acute radiation syndrome from an accident at a U.S. light-water reactor when none died at Chernobyl?

In the case of Chernobyl, the radioactive plume’s extreme height, due to the initial violent explosion and subsequent hot graphite fire, dispersed much of the radioactive material far from the site, sparing the areas immediately surrounding the site from high radiation concentrations. The NRC came to the same conclusion in its 1989 study of Chernobyl, finding that “the high initial plume height contributed to relatively low initial dose rates in the immediate vicinity.” Most accidents at light-water reactors, however, would not result in such a high plume, and could therefore result in higher doses to nearby residents if they are not evacuated in a timely fashion.

In any event, it’s news that SOARCA studies are apparently showing there would be early fatalities from acute radiation exposure in a nuclear plant accident. To our knowledge, that has never before been disclosed.

It will be interesting to see how many acute fatalities are estimated in the draft SOARCA study when the NRC releases it publicly.

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