A Tour of the Perry Nuclear Power Plant
by Scott Teresi
I read over the informative displays (with a mockup of the 12-foot long bundles of rods containing uranium pellets which are the fuel for the reactor core) before the tour started about 10 a.m. with a promotional video. A large Boy Scout group was there with us too. I developed lots of questions throughout the tour, and the tour volunteers were easy to talk to and were more than able and happy to answer all our questions. I asked a lot of questions about radiation. According to the staff and the charts in the displays and brochures, people living nearby only experience 1.5 millirems of radiation per year. Through day-to-day activities, the average person is exposed to 1 millirem per day anyway! Natural sources of radiation include: the sun (280-350 mrems/year), chest x-rays (15 mrems per x-ray), jet plane trips (2-3 mrems per cross-country flight), the television set (1 mrem/year), building materials, food (25-40 mrem/year), soil and rocks (25 mrem/year), radon (200 mrem/year), and smoking (2000 mrem/year). So to the community, radiation effects are unimportant as long as the plant is functioning okay. Sometimes workers have to work in slightly- or highly-contaminated areas. They aren’t allowed to receive more than 5 rems/year by the government, but at Perry, they don’t get more than 2 or 3, I think. They told me that only once did someone have to actually enter the reactor core, and he had to be in a lead basket. They couldn’t tell me how much radiation he got. Another time, someone was working in a contaminated area (a cooling pool) and there was a tear in his waterproof suit. It turned out he didn’t get all that much radiation (a couple hundred mrems, I think). Hiram, the guy I was mostly talking to, has to wear a dosimeter like everyone else in the plant, and so far it hasn’t recorded any radiation dosage for him yet this year.
I was partly so curious because a couple of my friends had expressed concern over being irradiated if they came with me, and I didn’t believe that really should be a concern, since workers have to make their living working there every day. The government seems to have so many regulations, though, and all of them are made to err on the safe side, that I don’t think there’s any day-to-day safety risk at the nuclear plant whatsoever! And this plant in particular seemed to be run very well. They’ve had long periods of time where they’d operated flawlessly and executed procedures perfectly. They’ve been online making electricity at full capacity (nuclear reactors can’t easily be started up or shut down, so they try to run at a constant rate) for 300 days, now. I asked what happened 300 days ago, and they said that was the last time they had to change out some spent rods. They change out one third of the rods every 20 months or so I think. The old rods are stored safely in a pool of water on site. All their high-level radiation waste is being stored on site, and they have enough room to continue to do this until 2011 or 2012, when by then they hope Yucca Mountain will be open.
The reactor works like this. The rods of uranium-235 give off lots of heat while they undergo fission, and control rods are put in between these rods in order to keep the reaction at a safe level. All these rods are completely submerged under waterexcept in the Three-Mile Island disaster in 1979, the worst disaster in U.S. history, where the water level dropped and the rods overheated and melted and they couldn’t pump more water into the tank fast enough. According to the tour guides, people in a 50-mile radius were only subjected to 1.5 mrems of radiation that day, fortunately, so that’s comforting to hear. Anyway, the nuclear reaction happening under water (the rods are actually glowing) causes the water to boil and create water vapor which turns the turbine. Meanwhile, highly-pressurized water is pumped through a separate system of pipes and is used to cool down the water vapor and condense it. When this water is cooled down, by the air, it creates the pure water vapor you see coming out of the cooling tower. This water does get exposed to a little radiation, which enters through the walls of the pipes when it’s cooling the water vapor from the reactor core. However, a lot of this radiation only has a half life of about seven seconds, so it’s gone by the time the water reaches the environment.
Our first stop on the tour was a mockup of the main control room, where they actually run simulations to keep the staff well-trained. The staff undergoes some type of training for forty hours every six weeks or so. There were dials and lights and flow diagrams between the dials and analog meters and big banks of warning lights all neatly packed together in a huge horse shoe shaped bank of panels. They showed us what it’s like if one small valve malfunctions and has to be turned off manually, and they showed us what it looks like if a big problem happens (a reactor scram) and all sorts of lights start flashing and the reactor core has to be immediately cooled (the reaction can be stopped in a matter of seconds). Two or three people are at the control board on twelve-hour shifts all day. And they’re not just sitting there like Homer Simpson; they’re running tests on reactor systems and logging measurements and stuff. They say they’re actually very busy, and they’re highly trained. I can believe them, seeing what people in the navy have to go through to get up to speed and stay on their toes with their tasks. I asked the man there how old the computer were, and he said they were run by a ten-year-old mainframe. But soon they’d be switching to Windows NT! That frustrated and concerned me. A lot of critical government systems are switching to NT.
Next, we walked somewhere else and went to a room where you practice putting on clothes to protect you from contamination. A bunch of kids tried it. They have very strict protocols for behavior in contaminated areas, and they pointed out a bunch of things that were out of place in a mockup situation. Then they showed how you how to take off the clothes carefully, and then check yourself for contamination. They had a little thing that you run over yours hands to check them for tiny spots of radioactivity. What you’re afraid of is getting a tiny radioactive particle on you, smaller than a speck of dust. If that happens, they have various levels of scrubbing you can undergo to get rid of it.
That was about the extent of the tour. They didn’t give us a tour of the protected areasthe cooling tower or the actual buildings involved in the power plant, probably because of the Boy Scouts. I was disappointed! My dad’s class will get a better tour. I was, however, very happy with the tour we got. The tour guides were volunteers, and they just kept giving us tons of information. They were more than happy to talk about radiation and nuclear waste and all the questions that would come into your head while you’re there. They’re really pretty happy with the nuclear plant, too. They said it can operate for another twenty or so years, and will probably easily get a twenty-year extension beyond that. Even though one pellet of uranium (costing $13) produces as much energy as 162 gallons of oil (costing $107) or 1,780 pounds of coal (costing $39), and nuclear reactors, when they’re running well (which this one certainly seems to be, thank goodness), produce zero pollution, I’d be happier if all nuclear reactors were shut down eventually. Even though the risk of a meltdown is very small in the U.S., the risk still exists, and then there’s all the spent fuel that has to be disposed of. There probably isn’t any place that’s good to keep radioactive waste for 10,000 years, and right now it's being kept under somewhat unsafe storage arrangements at each individual reactor.
Well... that's enough reactions to the reactor.
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