But at Maine Yankee and many other plants, the impetus is to move ahead. One reason is cost, which tends to increase with time. Another is a characteristic of nuclear projects that owners have learned to fear: changing rules. Just as shifting regulationscaused major delays in plant construction, they could lead to delays in tearing them down. A related concern is whether low-level waste repositories will be available when the time comes. If one or more of the three now in operation in the U.S. were to shut and not enough new ones were to open, prices could rise steeply or disposal could become unavailable. Disposal costs today already can run $600 per cubic foot.

In fact, rule changes have already occurred since the shutdown of Maine Yankee, and the regulatory challenges have grown. In 1997 the challenge was to meet the NRC’s standard for unrestricted release of a property, but new rules are stricter.

The NRC standard is “as low as reasonably achievable” but no more than 25 millirem a year in additional radiation (above the background exposure in that area) to the average member of a critical, or vulnerable, group. The Environmental Protection Agency has a standard for sites that are chemically contaminated, based on a one-in-a-million chance of an additional cancer. It works out to 15 millirem per year, with no more than four millirem of that amount coming from groundwater.

The millirem is an odd unit to get a handle on. It is not directly a unit of radiation but one of biological damage. It derives from the roentgen, a measure of the ionizing power of gamma rays. But the three dominant types of radiation—alpha, beta and gamma—differ in their biological potency; the rem, which is short for “roentgen equivalent man,” integrates the three into a single number.

The NRC asserts that its standard is sufficiently protective. For the moment, it is the federal standard. But it is also rapidly losing relevance. That is because the ultimate arbiters of health and safety, the states, are stepping in. In 2000 the Maine legislature cut the amount to 10 millirem, with no more than four from groundwater. Massachusetts, New York and New Jersey took similar steps, although so far the last two states do not have any reactors ready for full decommissioning.

The number is a key parameter because cleanup becomes more complicated as standards tighten. When it comes to radiation, it seems, almost no standard is stringent enough.

Some people think the Maine law sets a bad precedent. “What we ought to do is set standards for cleanup based on sound science and protection of health and safety,” says Marvin S. Fertel, a senior vice president of the Nuclear Energy Institute, the industry’s trade association. “The Maine standard goes well below it, and it’s not a good use of societal resources.”

James D. Werner, who was the Energy Department’s director of long-term stewardship during the Clinton administration, observes that nuclear cleanup requirements are debated “in a world of ideologues. On one hand, you have people saying, ‘It’s so safe you can put it in your Wheaties,’ ” he expounds. “And there are others saying, ‘My baby is going to die,’ or at least, ‘My investors will be nervous.’ There is bad karma associated with these sites. These are emotional, not rational, responses. We’d be in bad shape if people had these responses to gas pipelines or electric cables.”

A less technical evaluation, but one in better touch with the public’s mood, comes from John W. O’Connell, the Wiscasset interim town manager: “I think the only acceptable level is zero.”

Arguably, 25 millirem and 10 millirem are effectively the same: to use a technical term, zip. Worse, the significance of even 25 millirem is largely unknown. The idea that this amount has a health effect is part of a crucial but unproved assumption about radiation exposure—that unlike many chemical hazards, there is no threshold below which it is harmless. In fact, the mathematical model used to draw up safety regulations assumes that a given increment of exposure, 10,000 person-rem of collective dose, will cause one to eight fatal cancers no matter how applied. The 10,000 person-rem could be the result of exposing 10,000 people to one rem each, or 100,000 people to a tenth of a rem each, or a million people to a hundredth of a rem each. This is in contrast to individual dose; without medical treatment, a dose of about 350 rem will kill half of those exposed in what the regulators call “prompt death,” as opposed to the “latent cancer fatalities” from collective doses.

On the other hand, health physicists argue that no effects have been demonstrated below 10 rem. Acute effects, such as nausea and hair loss, do not turn up until an individual has absorbed tens of rem.

There are some other yardsticks. For example, the federal government estimates that the average American’s annual dose from all sources, including cosmic rays, radon gas and medical x-rays, is about 360 millirem. That would mean that 25 millirem from a decommissioned nuclear reactor is nearly an additional one-month dose every year. A resident of Wiscasset, which is at sea level, would get roughly the same extra increment of radiation by moving to Denver, which, at 5,260 feet above sea level, is less shielded by the atmosphere from cosmic rays. (The difference in natural background radiation is one reason that the limit on radiation exposure is set in terms of additional dose from a given human activity, not total dose. Otherwise, a strict standard could make living in Denver illegal.) Los Alamos National Laboratory estimates that cosmic radiation at sea level is 25 to 30 millirem a year; at an elevation of about 9,000 feet, it is 90 millirem.

In contrast to the 25-millirem maximum from decommissioned reactors, operating nuclear plants are allowed to expose people who live near them to 100 millirem a year, although actual exposures are far lower. Nuclear plant workers are limited to five rem a year, although operators aim for a maximum of two rem a year, and most employees get far less.

In addition, to reduce public exposure to radiation through the process of decommissioning, workers will soak up more of the dosage. The Maine Yankee project has a “budget” for worker exposure, 1,115 person-rem over the course of the work, for on-site activity. That compares with 440 person-rem in the year of the reactor’s last refueling outage.

1 Comments

1. 1. eco-steve 06:32 AM 12/2/09

   It would be scientifically necessary to see a fully independant report by an international commission on this subject before the results could be accepted as refereed and sound.
   
   

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