Three Mile Island and the Vigilant Professor

 By Russell Dupree


 Three Mile Island and the Vigilant Professor

    Thirty years ago, April 1, 1979, on the rooftop of a building at the University of Southern Maine in Portland, a nuclear radiation recording device went from being relatively quiescent to rapidly recording extremely high levels of beta radiation, 100 times the normal background levels.

    The equipment had been set up by USM physics professor Charles Armentrout a few days earlier as a teaching project for his students to see if any fission products from the Three Mile Island power plant accident could be detected in Maine. It was a rainy Sunday, five days after the partial meltdown at the power plant just southeast of Harrisburg, Pennsylvania.


    In Portland the wind had been from the southwest and then shifted to come in off the ocean. It was then that the professor's pulse frequency counter began to go crazy. A second counter brought to the roof did the same thing, so Armentrout knew his readings were real. This was equipment that had required him to obtain federal and state licences to operate and which he was also required to have periodically calibrated at the state's radiology lab in Augusta.

    Overnight, the counters recorded further bursts of furious activity, each lasting from 10 to 15 minutes. On Monday morning Armentrout called the state's Civil Emergency Preparedness Office to report his findings and asked if it were agreeable to them that he release the information to the press. There was no objection, and at 6 p.m. Armentrout went before the cameras at WGAN-TV News and gave an interview in which he suggested that the radiation he'd found might be from Three Mile Island. In the following weeks he never took a stronger position. However, the cat was out of the bag and local individuals and agencies – including the governor's office – entered the dialogue. All of them embraced the assurances of the federal government's Nuclear Regulatory Commission that no radiation of the kind Armentrout found had escaped the plant.

    What was most disturbing about the information these people provided to the public was the irrelevance of part of it: The lead headline of the April 3, 1979  Portland Evening Express read, "No radiation reached Maine, data show," but the article by staff writer John Lovell largely contradicted the headline. Of the three monitoring stations cited as the source of the data, one – the National Weather Service's at the Portland Jetport – had been shut off the entire time Armentrout was getting his high readings. 

    A second station was in Augusta, 50 miles northeast and at least 25 miles from the coastline, and a third station, belonging to the Portsmouth Naval Shipyard in Kittery, was on the coast 40 miles southwest of Portland; The latter two stations, because of their distant location, could not disprove another station's findings without demonstrating, very refinedly, that they were on the same weather track as it. This wasn't done, and the public was being allowed to believe the opposite.

      But maybe there was some relevant data from Kittery afterall: According to Lovell, state authorities had said that the shipyard station originally confirmed Armentrout's findings, only later reversing itself to say it had found nothing unusual. 

    The argument for "It didn't happen" was primarily being made by two individuals quoted in the local press; Thomas Hess, a physics professor and radiation specialist at U. Maine, Orono, and Pat Dostie, Director of the Maine Dep't of Human Services' Engineering Office in Augusta. Hess and Dostie relied on statements by the Nuclear Regulatory Commission that only Xenon gas, eight times heavier than air and giving off only alpha emissions, had escaped in the accident, and so they argued that Armentrout's readings, because they were beta, could not have come from the crippled plant.

    Perhaps under the influence of the NRC's "Xenon only" claim, Hess advanced a natural-causes theory to explain Armentrout's readings. To a non-scientist it was the most compelling argument against identifying TMI out of hand as the culprit. Hess maintained that naturally-occuring radon gas, rising from the soil as a by-product of the decay of uranium and the source of most of the backgroud radiation we experience, had accumulated in enough quantity in the atmosphere and then been precipitated by rain to give those high beta readings in Portland.

     Less was known about radon in those days, but its range of levels in the atmosphere had already been studied as early as 1962, 17 years before, with no evidence to support such an extreme scenario as 100 times background. 

Today, Bernard Cohen, a radiation scientist at the University of Pittsburg and a proponent of nuclear power, delivers a definitive blow to Hess's theory in a treatise about atmospheric radon: Radon, he says, only emits alpha rays. Of its seven decay products, four emit beta rays – only two significantly, and these two contribute typically 60-70% to a reading of total radon activity in the air. The rest of the reading – 30 percent – would be in alpha rays. Thus, if you're looking at a beta reading 100 times normal and trying to attribute it to radon, the total radon activity (alpha plus beta) would have to be 130-140 times normal in a typical situation. Only in extreme cases would the beta producers' percentage of the total radon activity approach 100 percent.

    This latter extreme would be the model for Hess's theory, and according to Cohen it could only be expected to increase the radon emanations from the soil by a factor of about 20, and it would require a very large drop of barometric pressure and relatively stagnant air conditions for a considerable period of time. Portland's air, April 1 -- 3 was Turbulent with athmospheric winds of 50-60 MPH.. 

    A gleaning of some other radon literature on the internet turned up a 1999 study (by Steck, Field, and Lynch of St John's University in Minnesota) of outdoor and indoor radon samplings taken over several years in Minnesota. The study found a maximum range between the highest and lowest individual samplings of outdoor radon at different locations to be a difference of 15 times, which would tend to confirm Cohen's projection.

    An extreme example of radon concentration found in the study was one indoor reading 66 times the study's lowest indoor reading. But even such an extreme of trapped, stagnant air wasn't extreme enough to come up to the level of Hess's conjecture for Portland. Rain can increase the level of readings (as was the case with Professor Herbert Clark and his students at Rensselaer Polytechnic Institute in 1953 when they detected fallout from an AEC bomb test), but the info on ambient radon doesn't provide evidence for any 100-times-background radon events, rainout or no rainout.

     One further radon phenomenon bears mentioning: Every day, from very late at night until just before sunrise, ambient radon normally increases – sometimes by a factor of 10 – because of nocturnal air inversion. But Professor Armentrout's first high readings were taken during the daytime.

    Eleven months after the first days of the Three Mile Island accident, scientists at the New York Department of Health's research lab in Albany reported in Science Magazine that the radioactive gas, Xenon 133, had reached Albany during the first week of April 1979. They examined the direction of the winds from TMI to Albany using air trajectories provided by NOAA's Air Resources Laboratory and determined that "From 29 to 31 March, southwesterly winds prevailed at increased speed" from TMI, and that, "The mean transport layer forward trajectories for this period passed 80 to 160 km south of Albany." 

They'd determined that the wind responsible for the Xenon entering Albany had traveled at a different level of height than "the mean transport layer", the principal wind passing over TMI; and if one placed a point 80 km south of Albany to track this latter wind, it landed almost exactly along a straight southwest-to-northeast line drawn between Three Mile Island and Portland. This suggestive piece of meteorology wasn't lost on Professor Armentrout when he read the article.

     As to how much radiation was released by Three Mile Island, Gordon Edwards of the Canadian Coalition for Nuclear Responsibility recounts that he was told by Norman Rasmussen "without hesitation that no one had any idea because the radiation monitors were all off-scale for most of the two-and-a-half day period before things were brought under control." Some of that radiation passed over Portland, Maine, and its detection by Professor Armentrout demonstrates the need for independent and incorruptible monitoring, in continuous operation, as long as we have nuclear power plants, weaponry, and waste in our environment.


Russell DuPree may be reached at