Somehow, on the afternoon of Tuesday, March 27, it was known at the Pennsylvania Topographic and Geologic Survey’s Harrisburg office, where I worked, that something was slightly awry at T.M.I. My friends John and Bobbie lived in Etters, about 4 miles WNW of T.M.I., so I accordingly sent a Mt. Sopris Scintillometer home with John to monitor gamma radiation levels.
The scintillometer was, in effect, a very sensitive and stable micro-Roentgen meter designed for geologic field use and operated using only two D-cell flashlight batteries. Unfortunately, the meter output was only calibrated to measure in counts per second rather than absolute units appropriate for high energy X-rays and gamma rays. The audio output of the Mount Sopris was tunable so that it would remain silent at any given ambient X-ray plus gamma level for which it was set, but start squealing if there were any increase.
John dutifully took the instrument home and left it running until bedtime, by which time it showed no evidence of even a slight increase in radiation levels. Having a conservationist’s heart, John then shut it off to save the batteries. The next morning, April 28, at approximately 6:00 A.M. when John turned the instrument back on it screamed while still on last night’s setting and all other available, progressively less sensitive settings. John immediately phoned Bob who advised him that he was beyond the measurable limit, which might mean that the ambient gamma flux was anything greater than 2 mR/hr.* (At that point, the instrument had never been calibrated to measure absolute amounts of radiation.) Bob suggested that the John pack, close up their house and leave the area. Bob promptly telephoned his Bureau Director, Dr. Arthur A. Socolow, at the latter’s home and reported that there might be offsite readings of 2 mR/hr. Art then phoned his friend, Thomas Gerusky, then Director of the Pennsylvania Bureau of Radiation Protection, with the Bob’s guesstimated radiation level. Gerusky told Socolow that there were measurements made with properly calibrated instruments of more than 10 mR/hr. at the facility. Dr. Socolow then relayed this Bob.
Bob reported for work in Harrisburg and received permission to record timed and dated gamma flux readings in counts per second on paper 7 ½’ topographic maps using the same Mt. Sopris scintillometer that John Way had returned before leaving the area. Meanwhile, Bob’s wife and two daughters departed their house in Mechanicsburg and headed to Bethlehem, Pa., and enrolled their older, but still very young, daughter in school in that district, just in case. Prior to leaving Mechanicsburg, Bob’s wife contacted their pastor and his wife and provided them with the limited, available information to share it as they discerned best.
Timed and dated gamma flux readings, mainly on the West Shore, were made inside a Jeep CJ-5. Bob drove the Jeep while coworker geologist/mineralogist, J. H. Barnes, navigated and recorded the data. One place where data were collected repeatedly was at a particular spot on John’s concrete driveway and on his vegetable garden. Readings varied unpredictably over time.
At one point on Pines Road, west of Goldsboro, John Barnes realized that when he leaned over the instrument the radiation readings were cut almost exactly in half. Neither of us was pleased about this because it obviously meant that half of the gamma flux was remaining in our heads! A minute later, the radiation levels exceeded the range of the instrument and Bob made a sudden U-turn in retreat. Up to this point, the elevated radiation levels were in distinct, narrow plumes with near normal readings between the plumes. It was becoming apparent that the then-unknown radioactive airborne material was not readily mixing with clean air, nor was it settling to the ground.
Data gathering and recording by the duo continued on Thursday, the 29th. By Friday, radiation levels were in less discrete patterns as the weather turned stagnant, perhaps even “socked in.” Assistant Geologic Survey Bureau Director, Dr. Donald M. Hoskins, was informed that the Jeep did not seem to retain any contamination, so Hoskins requested that all Survey vehicles be dispersed so that they would be usable to continue the field mapping function of the Bureau in the unlikely circumstance that the offices would not be usable after the event. Smith took the Jeep to Bethlehem and paid for gas and an out-of- pocket oil change and filter for the CJ-5 on the assumption that Hoskins would have wanted the vehicle to be returned “field ready.” Based on data collected by others, the Harrisburg area was still having problems with respect to radiation on Saturday and Sunday.
Bob returned to his office Monday morning at 8:00 A.M. and things by then were indeed cooling down. By Tuesday afternoon, the media were reporting that the alleged “hydrogen bubble” inside the T.M.I. Unit Two containment building was down. By Thursday afternoon, Bob resumed his normal geologic field work in the Picture Rocks-Sonestown copper-uranium district of Lycoming and Sullivan Counties with his summer assistant, Pat P. On Sunday, April 8, Bob’s wife and daughters returned to Mechanicsburg. Bob found zero gamma ray emitting residue** at his house and, even more startling, zero on John’s porous concrete driveway (Bob had helped John and Bobbie pour the concrete driveway the previous year and the final skimming was intentionally left coarse to provide a better winter-time grip on the moderate slope.) Even more startling was the lack of gamma emitting contamination in either Bob’s or John’s vegetable garden.
* More than a year after the T.M.I. event, the Pennsylvania Geologic Survey loaned the Mt. Sopris scintillometer to the Centers for Disease Control, Atlanta, (?) for proper calibration. When they properly calibrated the instrument, they learned that the Mt. Sopris scintillometer was particularly sensitive to the gamma flux from the T.M.I. mix of inert gases. With that high sensitivity, the mix of inert gases was able to send instrument off scale at only 2.7 mR/hr. The timed Mt. Sopris readings taken by Barnes and Smith on the paper topographic maps were separately sent with the instrument and factored into the dose model for the event. Smith and Barnes lack any training as a Certified Health Physicists, but the data they obtained certainly seem consistent with the maximum dose to a hatless theoretical individual at the T.M.I Visitor’s Center being 80 mR standing outside during the entire event.
**Startling because the radioactive cloud from a Chinese surface nuclear test on September 26, 1976, eventually “washed out” on the Harrisburg area during a stationary low pressure and left measurable radioactive fallout in tomato plants and especially in places where the high-density radioactive particles accumulated just beyond downspouts from house rain gutters that ended over grass. In response to the Chinese test, homeowner Bob removed a thin shovel blade full of soil from each of the downspouts and buried it deep in clay far from his fruit trees and garden. Unlike the Chinese nuclear test, the evidence seemed to show that the T.M.I. accident did not release anything that settled out onto the ground to permanently contaminate it.