On 13/04/2012 09:42, Nightjar wrote:

Even when it was built, the RBMK reactor was known to be a poor design
with serious safety flaws, particularly being the only design built
without a containment vessel. Three Mile Island was essentially the same
type of accident and the containment vessel there prevented anyone
getting more than a minimal exposure to radiation.

Not quite fair. In PWRs, the primary circuit pressure relief valve on
top of the pressuriser is expected to lift routinely under various
conditions, and the "containment" is then the last barrier.

The point about the RBMK was that it was scalable, and could be
assembled on site with only "shipbuilding" type welding, the pressure
tubes being factory-built. When you've got Ukranian weather and your
standard of living is constrained by energy supply it didn't seem such a
bad compromise. The people who designed it knew exactly where the
operational limits were, they just made the mistake of assuming that
people in a Socialist Republic, where they were not under pressure from
the profit motive, would never do something silly.

It would never have got licensed for the UK of course, indeed it was
reviewed and rejected in the mid 70's (in one of our many "nuclear
reviews").