Re:Indian Point 2 steam release

[Jacques.Read@eh.doe.gov]

Although the NRC Region 1 press release says nothing, the garbled news story
sounds very much like a steam generator tube rupture accident.  Indian Point 2
is a four-loop Westinghouse PWR -- it has four steam generators in which the
primary coolant circulates through a great many small diameter pipes within a
cylindrical pressure vessel-like container.  Outside the small pipes, clean
feedwater - distilled water of high quality - is boiled by receiving heat from
the large surface area of the small pipes.  The clean steam is then taken out of
the containment through large pipes to turn the turbine-generator and produce
electricity.  The advantage over the GE BWR is that the turbine hall, outside
the containment, does not have any radioactivity in its steam or condensate.  If
a small pipe inside the steam generator breaks, or leaks, the primary coolant
contaminates the clean steam, and the plant has to shut down if it doesn't want
to contaminate the turbine.  In practice, PWR steam generators do have little
leaks, but the news release indicates a large amount of primary coolant went
into the steam gemerator.  When this happens, the affected steam generator is
isolated, and flooded, and the excess steam is vented.  Usually, just a little
krypton, xenon and tritium get to leave the site, and the non-gaseous fission
products dissolved in the primary coolant stay on site.

We'll have to wait for the NRC website to post more details to know for sure.

Jacques



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