Posts tagged environment

In an effort to offset the inputs from the media talking heads I am forwarding comments from a friend that worked at several US nuclear plants and whose views I respect. The real tragedy of the Japanese earthquake and tsunaimi have been completely overshadowed by the events at the reactors. The current loss of life due to radiation is zero. Contrast that with the current death toll of over 10,000 that will likely run up closer to 25,000 when all are accounted for!    Bill

http://www.world-nuclear-news.org/default.aspx
http://www.nukeworker.com/
http://pajamasmedia.com/blog/fear-the-media-meltdown-not-the-nuclear-one/?singlepage=true

Yes, media coverage is particularly bad on this one.  I happened to have
spent a couple of years working in the bowels of Browns Ferry NP which
are identical units to those in Japan.  GE Mk I BWRs.

To sum it up in a few sentences, this is essentially identical to TMI.
A Loss of Coolant Accident followed by failed fuel and probably
substantial fuel melt (there was at TMI).  The huge hydrogen production
is from the zircalloy fuel cladding actually burning in the steam
environment, stripping the oxygen atom from water and releasing the
hydrogen.  Same thing happened at TMI and there was a hydrogen
explosion, though since with a PWR, the entire reactor building is the
containment, the explosion was contained within the reactor building.

At TMI the core remained uncovered for about 24 hours, long enough for
the fuel to reach its maximum temperature and equilibrate with its
surroundings.  The fuel that did melt simply flowed out of the core and
quenched in the water that remained below the fuel.  It did not melt
through the reactor vessel.  In fact it didn’t even scar the inside
surface of the vessel.

This is what I see happening in Japan.  There has been partial or
complete fuel failure in both units.  That is indicated both by the huge
hydrogen production and by the trace of Cs-137 and I-131 detected on the
outside.

There is a very large inventory of both isotopes in an operating
reactor.  The plant design assumes that both are released as gases
during an accident and plan accordingly.  That didn’t happen at TMI.
Once things cooled off enough that we could enter the containment, what
we found was that the Cs and I had reacted chemically to form cesium
iodide, a solid material.  Most of it stayed in the reactor.  Some came
out into the containment building and settled out on surfaces.  A very
tiny amount escaped during the initial containment venting at TMI.

Again, the same thing is happening in Japan.  The trace of Cs and I that
has been detected on the outside, if chemically analyzed, will be found
to be the compound cesium iodide.  This compounding is why there is but
a tiny bit of material released despite practically constant containment
venting.

I don’t quite understand the pumping of sea water.   That’s kind of a
last ditch decision because the salt in the seawater destroys the
stainless steel in the plant.  Normally there are a few million gallons
of demineralized water on-site for emergency cooling.  Maybe it got
contaminated by the tsunami.  Maybe the piping from the storage tank(s)
got broken in the shake.  I certainly can’t second-guess the on-site people.

I did see mention in one news report that they were using large diesel
construction pumps to pump the water.  That indicates to me that the
plant is still completely blacked out.  It’s possible that this is the
reason for using seawater – that none of the electric pumps in the plant
are working.

When all the dust has settled, I predict this to be identical to TMI.
An unmitigated disaster for the utility.  No significant off-site
radiation exposure and no off-site contamination.  In other words, a
non-event as far as the public is concerned.  The massive evacuation
will prove to have been precipitous and un-necessary.

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Thank God they’re using good old fashioned traditional units
of dose (the Roentgen) instead of the execrable Sievert. (1 Sievert is
100 R) The only advantage that I have is my experience at Browns Ferry
and TMI.

I don’t quite understand why they’re trying to fill the #3 reactor
building with water unless they’re assuming a failed reactor vessel and
primary containment.  Otherwise water from the reactor building could
not get through the primary containment boundary.  Bombing the spent
fuel pit with water I can understand but not the reactor building.

The radiation readings at the plant boundary and that one value quoted
at a distance from the plant are from the noble gases, primarily at this
point Xe-133.  It’s a rich gamma emitter with a high specific activity.
Fortunately it only has a 5.25 day half-life and so will decay quickly.

The other, at this point minor, contributor is Kr-85.  It’s mostly a
beta emitter with a rare gamma.  With about a 10.5 year half life it
will be the principle source of radiation around and inside the
containment vessels in the days to come.

Fortunately its low probability gamma means that it can be vented with
little consequence.  At TMI we vented a few million curies prior to the
first reactor building entry and there was no change in the background
radiation level at the plant site boundary.

I’d give anything to be at the plant site boundary with a gamma
spectrometer.  With that I could tell you want was going on in the core
and what was being emitted and how much.  I’ll guarantee you that there
are people there from some agency doing just that.  I don’t know why
that information isn’t filtering out.

John