You can be Sure…

Tales from the Nuclear Age:

 Copyright © 2010 Charles Glassmire

_________________________________________________________________

Apr. 9, 2010

You Can Be Sure…

          We arrived back in Pittsburgh after the strange experience of having our first irradiation capsule experiment destroyed. The General Electric Test Reactor (GETR) had suffered a reactor SCRAM in the middle of the night shift and ruined the data on our test. Dave traveled back on the airplane still wearing the blue coveralls supplied by the reactor health physics team. It had the large white GE logo on the back, which he tried unsuccessfully to cover up with a sweater. The reactor team had confiscated the pants to his suit because they were contaminated with fission products. It looked pretty weird; blue coveralls and an orange sweater (with a football letter on the side). Needless to say, I refrained from laughing out loud. The pants were being held in a hot cell to measure the radiation half life, to see if they would ever become safe to release and wear.

            There were, of course many questions to be answered, and meetings and explanations to be made back at the Astronuclear Laboratory. GE and our Westinghouse team needed to know exactly what had happened to cause the emergency before we could plan to continue testing the other capsules.  Something very unusual had caused the reactor to SCRAM, and the GE Safety Committee would not allow the reactor to be restarted until a thorough investigation was made. The Operators Logbook would be examined, and records of every radiation detector in the system would be scanned to determine the origin and progress of the emergency. Many dollars had been lost and experiments ruined.

            A reactor SCRAM is not a usual event. The phrase “reactor SCRAM” had its curious origin back in the days of the Manhattan Project. In 1942 it was determined there would not be enough Uranium made in time for a second bomb. The second device was decided to be Plutonium, the first non-natural element recently discovered by Glen Seaborg at Berkley. Its existence was top secret and the element was referred to only by the code name “49”. Many names were considered for this new element, and the names of the planets were high on the list. Also considered, jokingly, was the name “Pandemonium”. It was rejected for the planet Pluto; yielding “Plutonium” instead.

            Plutonium 239  is made by bombarding U238 with neutrons. It’s not found in nature. You can’t dig it up out of a mine anywhere. So a big neutron source was needed to bombard Uranium and create enough Pu for the second bomb. (There was plenty of U238 around – it’s the principal isotope in natural Uranium). So Enrico Fermi was given a blank check to create a giant neutron source to bombard U238. He experimented at Columbia by stacking up graphite (a neutron moderator) bricks with U plugs in each brick, into a big pile and measuring the parameters. It came to be called just that, a “pile”.

          But where to put it? The University of Chicago had recently abandoned their football team, leaving them with a useless football stadium, Stagg Field, and an abandoned Squash Court under the West bleachers. It was the last place a spy might look to find a secret project.  So Fermi and his team of scientists constructed a pile there in the empty space of the squash court.

            By late 1942 the pile was ready to be tested. The device was named “Chicago Pile One” or CP-1 for short. Nobody had ever tried a controlled self sustaining chain reaction inside a pile of Uranium bricks before. Fermi’s team did the calculations, but theory and experiment often seriously diverge. So on Wednesday morning, December 2, 1942, a group of nervous scientists gathered at the Chicago Squash Court for the experimental start-up of the first nuclear reactor in history. 

            There was concern that the chain reaction might run out of control. One big control rod could be moved by hand to stop the reaction. If this failed, there were actually three guys in the court balcony with buckets of liquid Cadmiun salts (neutron absorbers) to throw onto the reactor bed. Finally, if this failed, a fellow named Norman Hilberry stood on top of the pile with a fire axe. If all else failed, he would use the axe to cut a rope which would allow a gravity driven “zip” rod to fall home into the reactor core to stop the reaction! Rube Goldberg had never imagined a better set of devices. Norman’s job title called him the “Safety Control Rod Axe Man”, or SCRAM man. But the pile start-up was flawless, and enough Plutonium was produced in the ensuing months without operation of the axe. The SCRAM acronym has stuck to this day in reactor operations, although the system is automatic now, and the fire axe for nuclear control has long disappeared into the annals of history.

            So back at Vallecitos, the GETR Safety Committee traced records on the progress of the SCRAM, and soon determined that the origin of the fission product release was in the Trail Cable Facility, releasing radioactive gases back up the tube and into the second floor air of the Containment; thus starting a cascade of alarms ending in an emergency reactor shutdown. Our own capsule had been the source of the problematic release!

            When the telephone call came in, we all were dumbfounded! What could have possibly gone wrong? The GE people were quite nice about the whole thing, but insisted we had to find the source of the problem before any more experiments could be run in our test series. They also told Dave that his “hot pants” had a relatively short half-life, and they would be releasable in a matter of months. Meanwhile, the GETR had been cleaned up and decontaminated and the reactor was now operating nicely once again. Decon was a relatively easy process in the steel interior of the Containment Vessel, and it wasn’t a rare occurrence in the test reactor.

            The failed capsule in question was now highly radioactive, so we had to examine it in a Hot Cell to shield from the radiation. We shipped it to a Metallographic Hot Cell facility, which is capable of doing close up photography of radioactive metals. Back during the assembly, the capsule had been sealed except for a small nipple and hole on the very end. It was then placed in a vacuum chamber and all gases pumped out. Then the hole had been carefully welded shut in vacuum by an experienced welder to preserve the vacuum inside. Upon polishing through this sealed weld and photographing each step of the way, a large crack was observed under the surface of the weld. This crack had opened up as the capsule heated up to white heat. This allowed fission product gases to escape into the cooling water flow in the Trail Cable tube, and out into the second floor air. It seemed our welder hadn’t been quite experienced enough. But it was a tough job on a tiny piece of metal in a vacuum chamber filled with the blinding welding arc. Mea Culpa.

            Several months went by, and one day an innocuous package wrapped in brown paper and tied with a string, arrived from Vallecitos California, addressed to Dave. I walked it to his cubicle puzzled as to the contents. He took the package, and slowly unwrapped the paper, revealing his long lost suit pants! He happily shook them out and stood up to measure the condition, proudly holding the pants against his waist. Putting his hand in the pocket, he discovered a piece of note paper. He unfolded the note and read out loud in a disgusted voice the words

“YOU CAN BE SURE – IF IT’S WESTINGHOUSE! (From your friends at GE)”…

(to be continued…)

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3 Responses to “You can be Sure…”

  1. Mary Hart Says:

    This is wonderful, Chuck! I love the title- I remember the commercial from my childhood.

  2. lou goldszer Says:

    exciting,realistic,anxiously awaiting next blog thanks

    • Charles Glassmire Says:

      Lou;

      Thanks for the very nice words. Keep reading. there’s more tales to come.

      Chuck Glassmire

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