Re: at least 13 nukes have to fix cracked reactor nozzles

[mark sasser <duke99301@YAHOO.COM>]

I have worked at all of them the are  good safe plants.

lets go out and Buy a bridge next. and make coats out of Baby harp seals

  julian ginniver <julian.ginniver@lineone.net> wrote:

Norm,
Once again I find it difficult to accept statements made by the press
when they contain very significant errors on areas which are not difficult
to check by journalists before submitting their articles for publication.

snip>By raising or lowering rods of neatly stacked cylindrical uranium
pellets,
> > the control rods regulate the intensity of the atomic reaction taking
place
> > inside the reactor core.

Very, very wrong. Certainly what you do not want is a system for
controlling the reactor that would add neutrons to the reactor if it was
inserted. Generally most reactor types rely on insertion under gravity as a
final fail-to-safety measure for control rods. As a result of this you need
a system that removes reactivity (neutrons) from the core when inserted.
The rods Do Not contain Uranium. They contain some form of Ne! utron
Absorber. For Westinghouse type PWRs (I can't say for other types of water
reactor and therefore won't) they contain an alloy called SINCAD. This is a
mixture of Silver, INdium and CADmium (hence the name). In addition some
reactors use Boron Carbide, notably UK Gas reactors and some reactors use
Hafnium (naval PWRs).

snip>Equipment known as control rods pass through the nozzles
> > atop the ``head'' of the reactor.

Once again this is wrong. Although this is not as serious an error as the
first. The Control Rods do not pass through the reactor vessel "head". It
is the Control Rod Drive Mechanism that passes through the head. The
control rods themselves remain inside the vessel. Again I can only speak
specifically about Westinghouse model PWRs. The control rod drive is
operated through an electro-magnetic drive which ensure that during normal
operation there is no requirement for a breach of the reactor pressureboundary.

snip>The plant was scheduled to shut in April for refuelling and maintenance
> > work, but the work was moved up to February at the NRC's request.

Norm how does the above fit with your view that the NRC has a blatant
disregard for the safety of the public and does not provide effective
regulation of the Nuclear Power Industry in the US?

One final point, if my memory is not playing tricks, cracks around control
rod drive penetrations are not a new phenomenon. Both the French and the
Japanese have had problems in this area. The latest generation of French
Nuclear plant (the N4 design) at Chinon etc. had problems in this area. One
of the reasons for the problems I believe was the pre-treatment of the
vessel head to reduce dose-rates and hence doses to personnel during
operation (At last a radiological bit, albeit small). I'm not sure quite
effect this will have on the existing plants. Many people said that SG!
replacement was going to kill off the US nuclear plants due to excessive
costs and yet we seem to have more and more plants undertaking these
upgrades. What is the cost of a replacement vessel head. If my memory
(again) is correct the cost of the complete Reactor Pressure Vessel (RPV)
for Sizewell B in the UK was approximately £20 million (in 1990's money).
This is not prohibitive especially if the plant has been or is going to be
re-licensed for a full 60 years operation. In addition the RPV Head is
designed to be removed and is removed during each statutory refuelling to
allow fuel to be removed and replaced (apologies if I'm labouring the
point). Therfore there would be no requirement for specialist measurement,
modification (de-construction and re-construction) of structure within the
containment building. As such the only constraint may be manufacturing
capability the time taken from order to delivery of such a specialist item
an! d the consequent effects, possibly low power operation, all most certainly
extended inspections during outages, the possibility of mid-cycle outages to
allow inspections (as is required for some degraded steam generators).

Coming back to my original point - I do wish that Journalists (and others)
would take the time and trouble to ensure that they get the very basic facts
of their story straight before going to print.

Regards
Julian Ginniver



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Mark S. Sasser

Against logic there is no armor like ignorance!

I know the answer! The answer lies within the heart of all mankind!
The answer is twelve? I think I'm in the wrong building.
Only the mediocre are always at their best.

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