SL-1 (part 2)

Tales from the Nuclear Age:

 Copyright © 2010 by Charles Glassmire

___________________________________________________________

July 2, 2010

SL-1 (part 2)

           The Army Stationary Low Power Nuclear Reactor number 1 (SL-1) had been safely generating electricity since 1958 in a remote part of the Idaho Reactor Testing Station (IRTS). On the night of January 3rd, 1961, three men were working on top of the reactor core. The reactor had been shut down before Christmas for annual maintenance, and the water level in the reactor had been lowered two feet to expose the top of the core. The SL-1 had a unique design. It operated with only one main control rod, located in the center of the core. Approaching 9 p.m., it was the task of the three night crewmen to lift up this main control rod and reattach it to its control rod drive mechanism above the core.

          This required Army private Jack Byrnes to physically lift the main rod three inches out of the core, so it could mate with the controller above for reattachment. This was a safe movement distance used several times before; not enough to initiate a chain reaction. Private Byrnes’ wife had called him on the telephone at work about 7 p.m. that evening, to tell him their marriage was ended and she wanted a divorce. She told him not to come home, ever.

          At 9:01 p.m. that evening the IRTS fire alarm system alerted the main fire station that there was a fire at the SL-1 reactor. Fireman soon arrived in the 17 degrees below zero weather, to find no sign of the evening work crew. The place seemed deserted, no fire was evident but radiation alarms were sounding throughout the facility building. Upon entering the adjacent control room it was observed to be empty, but three lunch pails were seen lined up on a table awaiting their owners. When personnel crossed the yard and approached the reactor building, their low range radiation meters went off scale. The fire crew quickly retreated back to safer ground and called for assistance.

          Sixteen minutes later a Health Physics technician arrived. He carried a higher range meter and, together with a fireman, both wearing full body coveralls and Scott Air Paks again approached the stairs. The Air Pak has a backpack Oxygen tank and hose to a facemask. It keeps a positive pressure inside the face mask in case of a leak. The mask was to prevent inhaling fission products. (Note: There is no “suit” which protects against gamma radiation, short of a suit of lead armor which would be far too heavy to allow walking around.) Mounting the stairs again with a fireman, the HP’s meter registered a dose rate of 25 Röntgens per hour. Again they beat a hasty retreat.

          To put this in perspective, we live in a radioactive world. Cosmic rays from space, radioactive decay products in the air all give us a natural background radiation exposure. Many with below ground basements have small amounts of Radon gas decaying in the basement air. Even eating a banana gives our bodies a tiny dose from Potassium 40. (Truckloads of bananas crossing the border from South America often set off the border radiation detectors due to the radiation from banana Potassium.) So the ordinary population in the United States receives a radiation dose which averages 0.36 Röntgens per year. Current international standards (in 2010) allow radiation workers in the commercial industry to accumulate a maximum annual dose of five Röntgens. (Army personnel fall under different Army regulations. ) So the SL-1 rescue workers, in a radiation field of 25 R/hour would receive the maximum permissible annual dose in about 12 minutes of whole body exposure. This would require them to retire immediately and not work with radioactive materials for the rest of the year. In the worst case emergency, a short term whole body radiation dose of 450 Röntgens is sufficient to kill 50 percent of those persons exposed.

          By this time, a search of the peripheral buildings determines there are no workers anywhere else on the site. It’s concluded the three missing crew members must be located in the main Reactor building, evidently in a high radiation field.

          A few minutes later two HP techs arrive in full coveralls bearing very high range meters, capable of sensing 500 R/hr. Two firemen and the HP ascend the stairs watching the meter. At the top of the stairs they can see serious damage on the top of the core inside and no personnel. There the meter records a dose rate higher than 500 R per hour, a lethal dose rate. The Health Physics in charge orders all to withdraw. Meanwhile the Combustion Engineering and Idaho authorities are notified.

          John Horan, Director of Health and Safety leaves his home in Idaho Falls for his office where he takes charge of the situation via radio to the NRTS. A “Class One” Emergency (local and isolated) is declared. Medical personnel, higher authorities, local police and fire units, the Atomic Energy Commission Headquarters are all alerted. The Radiological Assistance Plan is activated, alerting still more area complexes. Local highways and local desert sagebrush are monitored for contamination, in case a cloud of radiation has escaped. Civil aircraft are notified to begin aerial site radiation surveys.

          Two supervisor personnel and HP devise a plan which has become rather standard in high radiation events. Personnel would be allowed to run into the radiation field, do a small amount of work and retreat quickly, to be followed by another crewman who does a little more work etc. Each run time is calculated to give only a small dose over a very short period. The worker is accompanied by a HP who’s job is simply to watch a stop watch and signal retreat when the time limit has been reached. In this high radiation field, dwell times are limited to one to two minutes, including the run in and exit times. Each person wears a small Dosimeter resembling a pencil which clips on a pocket. It will record  the accumulated dose when the worker leaves the field. The dose (by law) is recorded in the employer’s records, which are periodically inspected to verify accumulated doses are within legal limits.

          Using this method, the allowed time is one minute. Two military and a HP race up the stairs. Entering the second floor, they see two bodies, one badly mutilated and one moving slightly. There is no sign of the third man. The equipment in the room is a shambles, as is the top of the reactor core. The radiation field inside the door is 1,000 R/hr. They quickly exit. On the next relay five men race in with a stretcher to recover the moving body. The floor is covered with inches of water which was inside the reactor core. Scattered under the water are the round shielding steel pellets which cause them to slip and slide in the radioactive water. While the (moving) body is put on the stretcher, two others check the second  body and determine he is probably dead.  There is no sign of the third man …

 (to be continued…)

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5 Responses to “SL-1 (part 2)”

  1. lee silverman Says:

    Can’t wait for the next installment.

    • Charles Glassmire Says:

      Lee;

      Thank you for the very nice comment. I try to get one out every two weeks or so. Glad you enjoy it.

      Tell your friends and stay tuned. There are more tales to come…

      Chuck Glassmire

  2. Anne Morgan Says:

    Hi – has part 3 been posted and I just don’t see it? Your article is fascinating. I am related to Richard Legg.

  3. Jonathan Says:

    I’m working on an article on this event. Wondering if anyone know the birth date for Richard Legg?

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