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Thu 15 Oct, 2009 06:57 am
I've been having trouble hunting down information relating to the design of the vacuum buildings typically installed within CANDU nuclear facilities.
In the event of a melt-down in the reactor, there are specialized buildings designed to capture the waste products of nuclear fission (which are primarily gaseous). Chernobyl didn't have this safety feature, and this is part of the reason why its fallout was so bad.
Uranium-235 when broken apart for energy is shattered into lower forms of matter (which tend to be highly radioactive). Most of the byproducts of U-235 fission are gaseous, but a minute percentage will be solid (particulate).
My question is, in the event of a meltdown of the reactor, are the vacuum buildings intended to carry any particulate waste into the domes to be captured? Or are the vacuum buildings only intended to carry the waste radioactive gas from the fission?
Hypothetically, it would make sense that for anything airborne they would want to contain it via the vacuum buildings and domes, and physically, if there were airborne radioactive particles, they would be sucked in with the gas. But I need some sort of official article stating that particulate radioactive matter is an expected waste that is processed by the vacuum buildings. I just need anything that the vacuum buildings are designed to (or expected to) take in more than just gaseous waste.
Can anyone help me?
Thank you.
Naw . . . he's obviously a Canajun . . .
@RealEyes,
I'm not familiar with the most current designs, but I don't think there are "vacuum buildings" around reactors. The Xe and Kr isotopes from U-235 are fairly short lived (half lives in hours), so all you have to do it contain them for a few days and they no longer pose threats. The real concern is particulate thrown up by boiling water or fire. When I was more active in this, the barriers were first, the fuel casing, second the reactor vessel itself and third, the building which could be sealed down. They didn't "vacuum" the gas anywhere. The issue at Chernobyl was that the graphite core was flamable and the containment building was minimal. Standard modern cores might melt, but they won't burn. When the graphite caught fire, particles were thrown up far and wide.
@RealEyes,
OK, I understand what you are asking now. This is a fairly common design in chemical plants. This building is kept at a very slightly lower pressure, usually with fans so that the natural air flow is from the outside in rather than the inside out. If a leak occurs, the alarms seal the building and in this case sprayers come on to condense the steam and knock and particulate down. Maybe the question is where do the drains go? They would have to have a contaminated liquid holding tank somewhere for the spray down water.
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