January 1961: SL-1 Explosion Aftermath
At 9:01 pm on January 3, 1961, the first indication of trouble at SL-1 was received at Atomic Energy Commission Fire Stations. The alarm, which was triggered by one of several measured parameters at the plant, was immediately broadcast over all National Reactor Testing Station radio networks.
By 9:10 pm, fire trucks and security personnel had arrived at the site. The firemen were wearing emergency breathing devices and carrying radiation survey instruments. They first went through the administrative and support areas, finding no people, fire or smoke.
At 9:17 pm, two men attempted to investigate the reactor building itself. Their progress was halted when they encountered a radiation field measuring 25 REM/hr at the foot of the stairs leading to the operating floor of the reactor building. So far, they had seen no signs of the three men believed to be on duty. Calls to other installations on the NRTS site confirmed that the three men had not evacuated to a different installation.
The response team called for back-up support, including additional survey equipment with higher radiation detection ranges. By 9:35 pm key people associated with SL-1 and the NRTS had been notified of the accident. Many of the people began the 41 mile trip from town to the site immediately.
Plant Operators
It took a little more than an hour to assemble a team of people with appropriate equipment for entering a high radiation field. Two men, both employees of Combustion Engineering, entered the reactor operating level at 10:35 pm and found two men, one moving and one apparently dead. The two men left the high radiation area immediately to obtain additional assistance. With the help of two others, they put the still moving operator onto a stretcher and moved him outside of the reactor building.
The survivor was put into a panel truck taken to a point where he could be put into an ambulance and moved to a roadblock that had been established at the junction of Highway 20 and Filmore Avenue. There, an AEC doctor met the ambulance and pronounced the patient dead. The ambulance was returned to the site to await a decision on disposition of the body.
While the man was alive, he was accompanied by a nurse, who received a substantial dose of radiation from her efforts to treat the victim. A survey of the body conducted early the next morning yielded radiation dose rates ranging from 100 to 400 rem/hr after clothing was removed.
Meanwhile, a second group of responders had entered the reactor building to find the third man. They discovered that he was lodged in the ceiling above the reactor in a place where radiation levels were later determined to be more than 1000 rem/hr. He was not moving and was presumed to be dead. No attempt was made to remove him at that time because of the high radiation levels.
Radiation Releases
People began monitoring for radiation releases from the site almost immediately. Calculations completed later indicate that approximately 10 curies had been become airborne by early morning on January 4, 20 curies by the morning of the 5th and a total of 50 more curies between January 6 and January 30, 1961.
According to calculations conducted at the time, approximately 99.99 per cent of the total fission product inventory in the core was retained inside the reactor building, even though it was not designed as a containment.
Body Recovery
On January 4th, following an extensive brief and several rehearsals, a team of six military operators and two AEC health physicists entered the reactor building and removed the body of the operator who was not lodged in the ceiling. Their exposures for this effort ranged between 1 and 13 rem.
Removal of the third and final body took even more planning because of its difficult location and the high radiation field in the area. By January 9th, at 2:31 am, the last body was removed.
During the recovery period, 23 people received radiation doses greater than 3 rem. Of those, three received total whole body dose in excess of 25 rem, but none received enough to display any near term symptoms.
Rescuers
From all indications, the response to this accident went as might be expected in an accident occurring at an experimental site with a large contingent of highly trained emergency response teams.
No one rushed into dangerous areas without taking appropriate safety precautions. Prudent risks were taken when there was a chance to save lives, but once that phase had passed, response team leaders wisely determined that it would be best to regroup and plan further action.
Though no formal study seems to have been made of the health effects on the fire fighters and emergency response teams, Idaho Falls is a small town and people keep in touch with each other. According to several different sources of first-hand information, only one of the responders, the nurse who tried to revived the sole survivor, later developed a disease thought to be related to the radiation dose received as a result of the SL-1 rescue operations.
Additional links:
- SL-1 chapter from “Proving the Principle” – this is a 9.4 MB PDF with some excellent photos. Well worth the download time.
Originally published – July 1996
Reformatted February 20, 2009
