Archive for March, 2010

Get Out Now!

March 26, 2010

Tales from the Nuclear Age:

 Copyright© 2010 by Charles Glassmire

_________________________________________________________________

Mar. 26, 2010

Get Out Now!

          Our fuel irradiation capsule had been cooking nicely in the General Electric Test Reactor (GETR) for about eight minutes. We were testing NERVA nuclear fuel material to determine its stability under high neutron flux. The only strange event had occurred at about five minutes in, when the Containment Air Monitor (CAM) had detected a large spike of radiation activity in the air we were breathing. Then the radiation alarm had promptly disappeared, and the CAM strip chart was now back to outputting normal background levels. Dave and I had breathed a sigh of relief, but the white overhauled shift supervisor seemed still concerned. He had a worried expression on his face, as he stood beside the CAM, sifting the strip chart over and over in his hands, as if still looking for something – we didn’t know what.

          The second floor of the containment vessel was rather chilly on the midnight shift, even for southern California. It was now almost two a.m. and we were both a little bleary eyed. Dave had laid aside his suitcoat, while we monitored the strip chart recorder, and I recorded capsule temperatures in the log. The cooling water flow rate was steady, pushing water down the long flexible metal hose removing heat from the outside of the capsule. The fuel in the capsule deep inside the reactor core was beginning to fission from the high neutron flux, and the temperatures were climbing nicely inside the fuel pellets and the surrounding graphite fixture. Temperatures were recorded on a small thermocouple read-out we had calibrated back at the Westinghouse Astronuclear Lab in Pittsburgh, and subsequently shipped the chart recorder to Vallecitos along with the test capsules.

          I watched the capsule internal temperatures climb through red heat and now were approaching the white heat we predicted by our earlier calculations (above 2100 degrees C). The calculation was a bit tricky but our method had been reviewed and approved by the GETR safety committee. By now this type of computation was a standard technique in the nuclear industry. Every layer of material surrounding the fuel pellets in the capsule had been mathematically exactly modeled, and the temperature drops from center to outside the capsule were computed by solving a complex differential equation. We knew the internal temperatures to within a few Centigrade degrees, including the temperature rise predicted in the cooling water flow around the outside of the capsule. Things were actually beginning to look routine.

          Suddenly, at about nine and a half minutes, the Containment Air Monitor (CAM) came alive again! This time it was a long steady deafening alarm – and it continued without pause. Two technicians were instantly at the machine. The needle was again off scale. They examined the strip chart and began whispering and nodding to each other. They pulled down cloth face masks covering nose and mouth, as Dave and I watched numbly. The alarm continued to sound an ear piercing Brrrrrrrpp!  More technicians appeared on the floor below. They were standing and looking expectantly up at us on the second floor. Still undecided what to do, I began making another entry in the logbook, noting the time. Was I fiddling while Rome burned?

          Then a large fire siren alarm began to sound from the ceiling of the Containment Vessel above us. It was a deafening wailing siren, warbling up and down clearly indicating there was a dangerous condition in the reactor. The siren sounds added overtop of the CAM alarm; Dave and I were afraid to admit what was happening. We looked at each other helplessly, unsure but still hopeful.  White suited men were appearing from everywhere, running, all in different directions but with some seeming purpose to their movements. The alarms did not stop now, and the CAM indicator was off scale and not coming back.

          Now a Klaxon horn began to blare still louder than the other alarms. “Oooogah – ooogah! I was now hearing secondary beeping alarms coming from the first floor experiments below. I knew the Klaxon was a signal that the reactor was about to SCRAM due to an emergency unsafe condition. More men appeared running and hollering to each other. Some carried high radiation meters and others, low level Geiger Counters. They were looking anxiously at the dials of the high range meters as they ran and all now had covered their noses and mouths with white facemasks.  Bizarrely I was reminded of the World War II submarine movies as the sub was about to emergency dive. Men were sliding down the metal stairways 3 and 4 steps at a hop. Some simply grabbed the metal rails and slid down without touching the stairs until they hit bottom. Others were trying to get up the stairs against the flow coming down.  I remember thinking this is how the world will end. Locked in a steel cage listening to desperate men running to fix it.

          Dave grabbed up his suitcoat and looked at me helplessly. We were visitors without direction, and with a rising sense of terror as the seconds dragged into alarming minutes. Should we pull the capsule? If the Reactor SCRAMMED it would ruin the capsule experiment. Suddenly a white suited figure appeared in front of me. He seemed to be eight feet tall as I looked up into his eyes. His face was tense but the eyes were calming. He gestured to the stairway and simply said:

          “Get out NOW”!  Then he disappeared.

          I needed no further instructions. Dave and I both headed for the stairs to the first floor. The Airlock was located on that floor. It was the only way out. As we pushed down the stairs I heard the reactor control rods slamming into place putting a stop to all fission processes in the core, and bringing the reactor power level down to zero within a few milliseconds. The Emergency Cooling System then kicked in to remove the latent heat from the core, preventing any core meltdown conditions.

          The inside of the Containment Vessel Airlock door was wide open, and the Airlock was rapidly filling with technicians. There was room for several dozen people in the airlock. It occurred to me as I ran up to the big steel door that, if the door was closed early, any personnel inside the containment would be trapped inside, and could receive dangerous exposures. I took up a position holding the big door open while others rushed by me to enter the lock. Suddenly, the same white clad angelic figure appeared beside me, with the same calming eyes. I looked up tentatively. He placed his right hand above me to hold the door, and silently gestured for me to move on into the airlock. I was quite happy to do so. He clearly knew the drill and wasn’t going to trap anybody inside. Finally the great door was closed and dogged down to vacuum seal the chamber. My ears cracked as the air was scrubbed with safe air and equalized to the outside pressure.

          Slowly the heavy outside door of the airlock swung open to allow us to exit, but we were not out of the woods yet. A dozen suited and masked radiological monitor personnel were waiting for us with Geiger Counters. We were not permitted to leave the wooden shed we were herded into until we had been certified clean, and not carrying any radioactive materials into the outside.

          Each person stepped up, spread his feet apart and raised his arms straight out to the sides. A monitor carefully ran a Geiger Counter Probe over every inch of the person, listening for the rapid clicking in the headphones, which indicated Beta or Gamma contamination. When declared clean, a 3 inch white cardboard diamond on a string was threaded around a shirt button, allowing him to exit. Once in a while a person was flagged and told to remove his overhauls and put them into a yellow painted oil drum with the magenta colored radiation flower symbol on the side. Each persons hair and shoe bottoms were given special attention; also the sweaty underarms. Luckily, when my turn came, I passed inspection with flying colors. Due to my special paranoia, I had watched every move I made in the containment, and was careful not to touch anything not needed. I never sat down, but stood the entire time we were in the Containment Vessel.

          Dave was not so lucky. I noticed he was wearing his suitcoat again. It was an expensive suit – he looked like a million in it and he was clearly proud of the way he looked. When the Radsafe monitor got to the seat of his pants he paused, then went back more slowly, running the probe over the back of the pants. Finally he shook his head.

          “I’m sorry – I’m going to have to have those pants. Please step over here and remove them”.

Dave was flabbergasted, then annoyed, then angry.

          ”This is an expensive suit! “ he protested.

          The monitor said they would keep the pants in hot cell storage to see if there was a short half life to the fission products. They might be able to release the pants some time in the future. But in the meanwhile, the technician smiled,

          “We can give you Westinghouse guys a pair of blue General Electric overhauls to wear back to the motel…sorry that’s all we can do…”

          As we drove back to the motel the sun was rising; we tried to remember where Dave had sat or picked up the contamination. Dave was a mixture of anger and acute embarassment as he walked through the motel lobby wearing a pair of blue overhauls displaying a hugh circle logo across the back proudly showing the words “General Electric” in big white letters. The pretty desk clerk behind the counter stared curiously at him but was wise enough to ask no questions…

 (to be continued…)

Radiation Alarm

March 14, 2010

Tales from the Nuclear Age:

 Copyright © 2010 Charles Glassmire

_________________________________________________________________

Mar. 14, 2010

 Radiation Alarm

           We were in southern California at the General Electric Test Reactor, irradiating some NERVA rocket fuel. We wanted to see the damage neutrons might create in the nuclear fuel material. We were up on the second floor on the graveyard shift in the big three story high steel containment vessel which housed the GE reactor.

          I was rather amazed at the inside of the containment. It was inches thick steel, and designed to confine any radiation which might be released during the testing. This didn’t happen often, but reactors were designed to resist most possible accidents in the safest possible way. Designers created whole departments whose only job was to investigate possible accidents, computer model what might happen, and design in safeguards to prevent accidental releases to the environment. 

            I looked around the inside of the containment, and realized the entire thing had been made from metal. Stairways, handrails, tables, steel beams at the top of the curved roof, even the sparse furniture were all made from metal. I felt like we were inside some giant kind of factory manufacturing the future of a new age. But it was a safe approach and the easiest to decontaminate in the event some fission products got scattered around and had to be cleaned up.  Dave had taken off his suit coat and rolled up his sleeves (we both wore white shirts and ties in those days), and now he announced we were ready to insert the fuel capsule. The first capsule was about the size of several Coke cans but a little bigger in diameter. A sixty foot metal hose welded to the top delivered cooling water to prevent overheating as the fuel inside generated fission heat.

            We uncoiled the metal hose, and gently inserted the capsule into the Trail Cable tube. The Trail Cable Facility was a long metal tube which coiled down into the reactor core three floors below us. It was used for insertion tests of special materials which were somewhat smaller than the big irradiation experiments which had to sit directly in test ports inside the reactor and “cook” for long periods of time.

          As I entered notations in the test logbook I started the stopwatch and we both noted the time, and I ignored the sexual implications of what we were doing to the insides of this reactor.  The capsule was slipped gently down the long tube to a precise depth where we knew exactly what neutron flux it would be exposed to. The coolant hose was marked off in three inch intervals so we knew exactly where it was positioned below. While being irradiated, the neutrons would travel right through the double stainless steel cans and cause fissions in the enriched Uranium fuel pellets inside. The energy generated would heat the capsule to around 2,300 degrees Centigrade (white heat and more).

            Once the capsule reached position in the core, there was nothing to do but wait.  Dave and I didn’t say much, it was the culmination of nine months of design and assembly work and a lot of money spent back at the Astronuclear Laboratory, and inside we were both quite excited. But we maintained stoic faces during the wait.

            The capsule had been inserted for about five minutes of the forty-five minute run, when suddenly the Containment Air radiation Monitor (CAM) burped with an ear splitting alarm. Brrrrrrrrrrrrrrrp.  It sounded for several seconds and then promptly shut off.  Immediately a white suited technician appeared (the Shift Supervisor) from nowhere and ran over to the machine, and Dave and I were right behind.  It was spilling out a long paper strip chart of the room air radiation level readings. They showed normal background levels up until the prior few seconds. Then suddenly there was a peak in the tracing, and the needle had gone off the top of the chart!  A few inches later in time, the needle had returned down to normal levels, and the CAM chart now sat calmly spewing out continuous readings of normal background levels saying everything was quite OK.  The three of us looked at each other with puzzled concerned faces. Could some experiment deep in the core have emitted a burst of fission products into the second floor air? The CAM had definitely picked up something in the environment. 

            There are strange critters living in and around nuclear reactors.  The radiation levels are constant and ongoing high levels, and eventually the higher forms of life are destroyed.  Rats and mice no longer scavenge at night. The survivors have lower level nervous systems, oblivious to the radiation. Cockroaches live on nicely in the “hot” environment; they run all around the insides of the containment vessel. So they often stray overtop of the radiation sensors and set off alarms, since their body is covered with fission products. It has proven impossible to eliminate them entirely from the environment. So occasionally they drive the operating staff to distraction by setting off detectors in the floors and ceilings of the reactor.  Yes, in the event of a massive nuclear attack, so the myth goes, only the cockroaches would survive. This, of course, isn’t really true even in this worst case scenario, but it makes a nice story. The reality is that many millions would survive an attack – but that’s a different tale.

            Still staring at the chart he held in his hands, the Supervisor told us it wasn’t a concern, things sometimes happened like this, and waved us away. I went back to the log and entered the event, together with the CAM times and readings. It was probably nothing, but I noticed the Supervisor stayed at the CAM, still peering intently at the chart readings as they slowly pumped out of the machine. Something didn’t feel quite right to me, and I felt strangely ill at ease…

(to be continued…)

California Dreamin’

March 1, 2010

Tales from the Nuclear Age:

 Copyright© by Charles Glassmire

_________________________________________________________________

Mar. 1, 2010

California Dreamin’

           We were flying to California to irradiate some Nuclear Rocket fuel in the General Electric Test Reactor. Dave was quite excited about California from his earlier trips there, and he talked about it continuously. As we walked across the tarmac in San Francisco the Sun was so brilliant I had to squint. Dave inhaled a deep breath and told me to “just smell the air here – it’s so different from Pittsburgh” – and it was. We had a motel in Hayward, which was down the coast halfway between San Francisco and Vallecitos, where the reactor site was located. But first Dave had promised to take us to one of the best restaurants in town. We took the rental car up and down San Francisco’s hills to Alfredo’s, and the meal was very special. The trip down the coast went quickly; the 101 freeways were six and eight lanes wide. Spectacular views of the ocean on our right.

          A phone call from the motel revealed the capsules had arrived safely at the Reactor. Since we were new customers, the irradiation would be done on the graveyard shift. That’s when they ran the “far out” stuff. So it was dark when we first drove to the site. I remember as we passed through the sugar loaf brown foothills approaching the test site that Dave wasn’t saying much. I began to feel a strange sense of detachment and loneliness – some kind of alienation and foreboding about what was to come. The lines of a song kept bothering me, something about

“Scooted out of ‘Frisco

over route 101,

got a hitch as far as San Hose.

Rode aboard a Greyhound

till I ran out of dough,

bid the bus goodbye at Monterey.”

           It was a dream of loneliness and loss in the California hills, and as I looked out the car window at the lighted up homes drifting by us like ships in some alien night sea, I fantasized floating out of the car and knocking on someone’s door. They would open and I would see a smiling mother and father. They would invite me in and welcome me as if I belonged, and the ship would sail away into the darkness, with me living there forever. But I didn’t.

          We arrived and met Al, our customer engineer. He gave us the two dollar tour. The reactor was housed within a giant steel dome three stories high, called the “Containment Vessel”. The idea was if anything went wrong, the vessel was air tight, and problems would be confined inside the vessel, thus no radiation would be released to the outside. This was not an unusual occurrence in test reactors. They were always testing new and experimental designs for fuel rods and other nuclear components, and every once in a great while something went a little wrong. There was never any danger of a nuclear explosion, but if things got too hot there could be a steam explosion, for instance, from fluids overheating. The GE Team had a safety committee which carefully reviewed every experimental design before it was cleared to be placed in the reactor. Our test plan and design had passed the committee nicely.

          Our irradiation was to use what was called the “Trail Cable” facility. This rig was located on the second floor of the containment vessel. It was actually a long tube which curved down two floors into the actual reactor core. The main reactor was a hugh thing which sat inside a swimming pool of water for cooling. When the reactor used up its Uranium fuel rods, they were off loaded and placed in a special section of the swimming pool to cool down and eliminate the highly active fission products as they died off. On the tour Al pointed out the cooling fuel rods underwater.

          I leaned over and peered into the water and saw an unearthly blue glow surrounding the fuel. It was called “Cerenkov radiation”. As the fuel emitted electrons into the water, they Cerenkov radiation from Advanced Test Reactortraveled faster than light velocity in the water. A photon (light) was ejected which couldn’t move fast enough to get “out of the way”. It was rather like a jet plane exceeding the speed of sound in air. The sound vibes from the wing can’t get away fast enough, so they pile up on the wing edge like a physical barrier. The glow was creepy. It actually passed through the fuel rods and made them translucent. You could  see through the rods as you moved your head from side to side.

          Nature had some kind of balance of energy in its design. The most active and dangerous fission products spat out lots of dangerous radiation as they decayed. But the very “hot” active ones decayed very quickly down to a reasonably safer level. The less dangerous isotopes put out less radiation, but often had very long “half lives” (the time for 50% of the atoms to decay into something else. After one half life you had half as many atoms, therefore half the amount of radioactivity emitted.) The isotopes decayed on a logarithmic scale, and we used a rule of thumb that after seven half lives, the amount of the isotope remaining was less than one percent. BUT the half life could be hundreds of years! Or only a few seconds.

          Our capsule was to be lowered into the trail cable tube to a precise position inside the reactor, so we knew exactly the neutron flux it was exposed to. There was a long corrugated metal hose attached to our capsule which delivered cooling water, so the capsule wouldn’t overheat and melt, or worse. The technicians brought out the capsule and hose and laid them out on the floor of the second level. Dave was busy measuring off distances on the corrugated hose and marking the lengths, so we could tell just how much had been inserted into the Trail Cable. It was after midnight, and he had taken off his suitcoat and laid it aside as he worked.

          We started up the Coolant Air Monitor, called the “CAM”. It was a radiation monitor device on a big four wheeled cart. It had a large diameter hose attached continually sucking on the air from the second floor. With a loud vacuum cleaner roar, the air was pushed through the radiation detector and checked for any radiation which might have bubbled up out of the reactor pool. This rarely happened but it was a reassuring safety device nevertheless.

          Finally Dave finished up the measurements, brushed off his hands and shouted to me that we were ready to insert the capsule into the reactor…

  (to be continued…)