On Friday, July 29, 2011, Matt Wald of the New York Times published an article titled N.R.C. Lowers Estimate of How Many Would Die in Meltdown that describes a US Nuclear Regulatory Commission project whose results to be widely understood and repeated.

The project was a multi-year modeling effort at the US Nuclear Regulatory Commission titled the “State-of-the-Art Reactor Consequence Analyses (SOARCA) Project.” The main report (DRAFT) is accession number ML11168A034. Here is the BLUF (bottom line up front) from the Conclusions section of the main report documenting the project’s results.

  • Individual early fatality risk is essentially zero
  • Individual latent cancer risk from the selected specific, important scenarios is thousands of times lower than the NRC Safety Goal and millions of times lower than all other cancer risks, even assuming the LNT dose response model.

(Emphasis added.)
The report and its appendices are quite lengthy – this, after all, was a government project where it cannot be called complete until it reaches a certain weight or number of megabytes. In this case, the files add up to about 120 Mbytes (272 pages) of scanned PDF documents. That main report is a 5.4 MB file, but there are three additional files that provide the supporting data – accession numbers ML11192A300 (43.6 MB), ML11192A301 (50.5 MB), and ML11192A302 (22.7 MB). The document has not completed its final reviews; it is not scheduled to be released until April 2012.

However, the UCS filed a Freedom of Information Act (FOIA) request to obtain the current version. They had heard that the study was nearing completion; my guess is that they were interested in getting out in front and controlling the interpretation of the study.

When the NRC issues a response to a FOIA request, they also add the released document to their publicly available document library. My plan is to use the availability of the program documentation and Wald’s article to disarm the opposition by providing access to the study and to interpretations that are not slanted by an organization like the UCS, which has engaged in a multi-decade professional effort to discourage the use of nuclear energy by spreading fear, uncertainty and doubt (FUD) whenever possible.

Aside: I am not sure if it is possible to link directly to documents in the NRC’s Agencywide Documents Access and Management System (ADAMS) database, but here is the link to the web-based ADAMS search page – http://wba.nrc.gov:8080/ves/ . From that page, you can find any publicly available document using a variety of techniques. The simplest way to find exactly what you are looking for is to know the “accession number”, but full text and title searches also work quite well. End Aside.

The UCS’s worrier-in-chief is apparently not calmed by the results from the report; he continues to strive to make people believe that they should worry more about the possibility of a nuclear accident than about the thousands of other more risky influences in their lives. Here is a quote from Matt’s article:

Dr. Lyman suggested that in projections of fatal cancer cases, the focus should be on people who live within 50 miles. The average population within 10 miles of an American nuclear plant is 62,000; within 50 miles, it is about five million.

The commission’s old projection of eventual cancer deaths was one for every 2,128 people exposed within 50 miles; the new study projects one cancer death for every 6,250 people exposed, which still comes to hundreds of cancer deaths within the 50-mile circle, in addition to the hundreds of thousands who would be expected to die of cancer from other causes.

Dr. Lyman obviously believes that if you multiply a tiny, close-enough-to-zero-for-an-engineering-approximation risk probability by a large enough number, you can still come up with a result big enough to expect that people should worry about it. That is the cost of continuing to adhere to the Linear No-Threshold (LNT) Dose rate assumption. Dr. Lyman’s statement is contrary to the guidance given by the Health Physics Society with regard to applying low doses in making consequence calculations.

In accordance with current knowledge of radiation health risks, the Health Physics Society recommends against quantitative estimation of health risks below an individual dose1 of 5 rem2 in one year or a lifetime dose of 10 rem above that received from natural sources. Doses from natural background radiation in the United States average about 0.3 rem per year. A dose of 5 rem will be accumulated in the first 17 years of life and about 25 rem in a lifetime of 80 years. Estimation of health risk associated with radiation doses that are of similar magnitude as those received from natural sources should be strictly qualitative and encompass a range of hypothetical health outcomes, including the possibility of no adverse health effects at such low levels.

There is substantial and convincing scientific evidence for health risks following high-dose exposures. However, below 5–10 rem (which includes occupational and environmental exposures), risks of health effects are either too small to be observed or are nonexistent.

The release of the SOARCA project report should calm a lot of fears, especially since the models can be validated by correlation to the accidental “theory to practice” events at Fukushima. The low probability accident of an extended total loss of electrical power has happened; there are reasonably detailed timelines available. Knowledge of reality can provide a sense of calm and reassurance to replace the fear of the unknown. It is like turning on the light for a child after they have had a scary dream so you can show them that there really is not a monster in their closet.

I have asked some of my technically minded and well-informed friends to help me out with the match between modeled consequences and reality. After spending several hours skimming the report and the appendices this weekend, my initial impression is that the physical consequences and radioactive material releases at Fukushima have been quite close to what the NRC’s state-of-the-art models predicted. Even the time delays seem consistent. I promise to report back after a more detailed evaluation.

Aside: It was darned hot in Virginia this weekend and my wife is visiting relatives. I used up too much vacation time in mid March to make that trip, so I holed up in the air conditioning and spent the weekend reading government reports about reactor accident consequences. Now you do not have to do that yourself unless you really want to. End Aside.

Have an atomic day!

PS – Sometimes in the early morning hours or when engaged in endurance sports, I think about how a given name can exert a strange influence on a person’s career choices. In a long ago era, given names came from the career – a guy who laid bricks would end up with the last name of Mason, a man who grew vegetables would be called Farmer, and a person who grinds wheat would be called Miller. My last name sounds like “atoms” and I became an atomic energy advocate. I wonder if Dr. Lyman ever consciously thinks about the possibility that his name has influenced his career choice as a spreader of FUD about nuclear energy production.