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Health Physics Technicians
Nuclear reactor containment buildings are cracked open every 16 to 18 months to be re-fueled. Things atrophy over time, so during the 4 to 6 week re-fueling process, nuke workers would repair whatever needed to be fixed. These guys were mostly made up of union pipe fitters, painters, and electricians. These craftsmen knew how to do their trade specific jobs, but didn’t necessarily know the dangers of radiation exposure. So, they in turn were supported by Health Physics Technicians (HPTs).
An HPT’s job is to make sure that personnel weren’t being exposed to something that was not deemed safe by the DOE and the NRC. We collected dosimeter data, took readings off tools with a Geiger counter to verify the decontamination was satisfactory, and roped off or shielded areas that were just too hot (radioactively) for anybody to go near them.
After I dropped out of WSU, my Dad suggested I get into the nuke biz as an HPT. I could travel the country and the pay was good. So, I went through a specialized training program in Maryland to become one. The course only lasted for a few months, and by the time I was certified, I was tutoring other students on formulae, how far to stay away from a radioactive source given the inverse square of a specific dosage at a distance, shielding, the types of radiation we’d be dealing with (alpha, beta, and gamma), and the physical damage these isotopes could do to you either by simple exposure or by ingesting it.
When I did start working on nuclear sites the pay was great! I was 19 years old, making $80,000 dollars a nine month year and there was nontaxable per diem to boot! The holy grail of this type of work was to decon the Space Shuttle. This had to be done after every re-entry due to the fact the shuttle’s skin would pick up radioactive particles while in orbit. The guys working that gig must have known somebody at the top. Their pay was $125 an hour, $75 per diem, and round trip plane tickets from Florida to anywhere their families lived every other week. If you didn’t have family to fly home to, or decided not to use the plane tickets if you did have family, they gave you a check equivalent to what it would cost to fly you there!
OK, back to refueling/repairing the reactor core etc.
Hot Spots
The most radioactive areas in a reactor containment building are the fuel rods which resided in the reactor core where that entire assemblage was submerged in a deep pool of heavy water (deuterium oxide D2O). Heavy water resembles regular (light water) except that the two hydrogen atoms are replaced with two deuterium atoms (D2O) which are hydrogen isotopes that have a mass double that of hydrogen. Why, you ask? The heavy water absorbs fewer neutrons than regular water, so there’s less neutrons being absorbed which enables more energy being released in the fission process.
Valves are hot spots too. There are lots of little nooks and crannies in valves where radioactive particles can be trapped when light or heavy water carrying these particles passes through them. It’s just a matter of time for enough build-up to occur to make that valve something you want to stay away from. If the Geiger counter pegs when you point it at a valve, tape that area off. Anywhere there is a bend, elbow, or joint in the in the system, particles can and most likely will be trapped.
Steam Generators
In pressurized water nuclear reactors, there exist structures called steam generators that are composed of up to 15,000 three quarter inch tubes and can be up to 50 feet or taller. The primary tube coolant side of the steam generator passes through the reactor core to absorb heat. The water in the primary side of the generator is under tremendous pressure to prevent boiling. It’s not uncommon to have 500 degree liquid water in the primary side of the steam generator which passes through the closed secondary tube system of water on the shell side (that contains clean water) to produce steam that turns the turbines that generates electricity.
As I said before, things atrophy when left alone for a while. In the case of steam generators, this means that the integrity of the high pressure/temperature in the primary tube side could be breeched whereby leaking contaminated water into the secondary steam generating side. Not good. When this happens, the leaks need to be patched by an experienced steam generator welder. These leaks are sometimes so small you can’t see them because they could be as small as a pin hole and the 500 degree pressurized water immediately turns to an invisible vapor laser when it passes from the high pressure zone to the low pressure zone.
The guys that fix these leaks are in a very dangerous and radioactive environment. They are only allowed to work in thirty minute shifts to gain access to, weld the leaks shut, then get out alive. In five hours of work (ten thirty minute shifts) you could make about $1000 an hour – and that was 25 years ago. It’s a quick 10 grand, but you’re dosed out for the rest of the year. Meaning no more nuke work for you for 12 months. (Check out my *5(n-18)…* article which describes how much radiation you can be exposed to per year).
Locating the Leaks
OK, if you can’t see the leak, how can you repair it? The technique I’m about to describe is one of the most specialized procedures I’ve seen in such a high tech environment as a nuclear containment building – so read carefully to follow along.
Grab yourself a broom with the handle part sticking way out in front of you. Begin waving the broom handle up and down as you slowly walk around the perimeter of the steam generator. When the tip of the broom handle suddenly drops off, you’ve found the leak! The immediate transformation of a pinhole size ultrahigh pressurized 500 degree stream of liquid water flashing into a vapor stream the thickness of a needle has enough energy to sever an inch thick stick of wood. No shit!
I can’t imagine what this would do to a human body if you walked into it.
I'm hooked on etymology, folklore, writing, live music, and making movies. I jam the axe and I'm currently learning how to beat the skins. I write cool software and meaningful screenplays.
I like to drive fast with the top down in the rain with the music cranked.
My tastes in TV, music, film, and literature are broad but obscure. I keep a journal, write screenplays, compose music, take many pictures, and create software.
When camping at night, you can find me staring into the campfire either playing the guitar or telling a spooky story under the moonlight. I love thunder storms, Friday is my favorite day and my favorite number is 9. 
Terrific work! This is the type of information that should be shared around the web. Shame on the search engines for not positioning this post higher!