The debate over making post-Fukushima Daichi improvements to American reactors is getting down into the details, and one focus is pressure relief vents.
The idea behind venting a nuclear plant is that if a reactor overheats, chemical reactions will produce steam and gases that could overpressurize the containment building. The containment is a major line of defense against the release of radioactive materials, and rather than let it burst like an overfilled balloon, the idea goes, it would be more sensible to let the reactor dump a little bit of slightly radioactive gas into the environment.
Continue reading at The Nuclear Industry and Venting, Round 2