An Update on Two Competing Models of Radiation: Linear No-Threshold vs Hormesis

The author of one of my favorite nuclear blogs, Rod Adams, found a new and compelling document explaining the beneficial health effects of low doses of radiation. The document has generated quite the number of comments at his site and I could see why. Here are some good quotes and background info from the paper (pdf):

In the early stages of nuclear development, more than 60 years ago, the world regulatory agencies (e.g. ICRP) had little understanding of the mechanisms by which nuclear radiation interacts with living things. They observed an excess incidence of cancer death following high dose exposures and measured a linear relationship between dose and cancer mortality in the high dose range. They were unable to observe excess cancers in the low dose range, so they assumed that excess cancer is proportional to dose in that range, all the way down to zero dose. That is, they made a linear extrapolation from evidence in the high range down through the low range, where there is no evidence of harmful effects. This is called the Linear No-Threshold (LNT) model. (p.4)

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So what levels of radiation are harmful and what levels are not? Based upon human data, a single whole body dose of 150 mSv (15 rem) is safe. The high background of 700 mSv/year (70 rem/year) in the city of Ramsar, Iran, is also a safe dose limit for continuous chronic exposure. Both dose limits are also beneficial. However, our regulations limit exposure to human-made radiation to only 20 mSv/year (2 rem/year) for workers- and 1 mSv/year (0.1 rem/year) for the public. Why have these limits been set so low? (p. 6)

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There is considerable evidence that exposure to a low dose or a low dose rate of radiation has a stimulatory effect on all living organisms. The immune system is stimulated by a short-term radiation dose. The body has built-in adaptive defences against higher levels of exposure after having been exposed to low-dose or low dose rates of radiation. This is called radiation hormesis. The extensive scientific evidence of the beneficial effects following low dose or low dose rate exposure (e.g. 192 studies in UNSCEAR 1994) and the scientific explanations for the effects appear to have been ignored by the government regulatory authorities (ICRP, NCRP). (p. 7)

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The doses or dose rates of radiation received in the nuclear industry and by the public living near nuclear plants are within the range of natural background radiation levels and far below the levels where harmful effects have been observed. Radiobiological evidence supports the radiation hormesis model: beneficial health effects for low-dose or low dose rate radiation exposures and harmful effects for high-dose or high dose rate exposures. (p. 9) ...

It'll be interesting to watch how the regulators and public react as more and more evidence like this comes out explaining that radiation maybe isn't as bad as they think. Like I said before, radiation saves lives.

Activists' Claims Distort Facts about Advanced Reactor Design

Below is from our rapid response team . Yesterday, regional anti-nuclear organizations asked federal nuclear energy regulators to launch an investigation into what it claims are “newly identified flaws” in Westinghouse’s advanced reactor design, the AP1000. During a teleconference releasing a report on the subject, participants urged the Nuclear Regulatory Commission to suspend license reviews of proposed AP1000 reactors. In its news release, even the groups making these allegations provide conflicting information on its findings. In one instance, the groups cite “dozens of corrosion holes” at reactor vessels and in another says that eight holes have been documented. In all cases, there is another containment mechanism that would provide a barrier to radiation release. Below, we examine why these claims are unwarranted and why the AP1000 design certification process should continue as designated by the NRC. Myth: In the AP1000 reactor design, the gap between the shield bu...

How many nuclear plants does it take to meet the world's energy needs?

Several weeks ago Joshua Pearce at Clarion University in Pennsylvania released a study titled “ Thermodynamic limitations to nuclear energy deployment as a greenhouse gas mitigation technology .” In the study he stated... nuclear energy production would have to increase by 10.5% per year from 2010 to 2050 to both replace fossil-fuel-energy use and meet the future energy demands. This line, of course, made the headlines and has been picked up by several outlets and blogs . When looking into his calculations for this statement, he made one assumption error that overstated the above sentence by nearly a factor of three. Page 121, Section 4.1 of the study states: Richard Smalley pointed out that in 2004, the global economy consumed the equivalent of 220 million barrels of oil per day, which converted into electricity terms is the equivalent of 14.5 TeraWatts (TW), or 14,500,000 MegaWatts (MW) (2005). … With a nuclear plant having about 1000 MW (1 GW) of capacity, we would need 14,500...

What Happens During a Refueling Outage?

You may have noticed over the past few weeks that a number of nuclear plants are shut down for refueling outages or are resuming operations after just returning from one. This type of routine outage usually occurs in the spring or fall when electricity demand is low so that nuclear reactors can replace about one-third of the spent fuel rods with new fuel and conduct other routine maintenance and repairs at the plant. To get a better sense of how refueling works at a nuclear energy facility, I spoke with Marcus Nichol, NEI’s senior project manager for used fuel storage and transportation, and asked him to explain the basics. Why does a nuclear plant need to replace one-third of its fuel? Nichol: The main purpose of a refueling outage is to replace older fuel that is depleted—meaning it can no longer efficiently produce energy from nuclear fission reactions—with new fuel. This “used fuel” has typically been used in the reactor for four-and-a-half to six years before it is pe...

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