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From: mvs@meccts.UUCP (Michael V. Stein)
Newsgroups: net.politics,net.sci
Subject: Re:  Nuclear power vs Coal vs Alternatives
Message-ID: <448@meccts.UUCP>
Date: Sat, 12-Jul-86 19:30:08 EDT
Article-I.D.: meccts.448
Posted: Sat Jul 12 19:30:08 1986
Date-Received: Sun, 13-Jul-86 08:21:18 EDT
References: <628@bu-cs.UUCP> <1943@ihlpg.UUCP> <796@whuts.UUCP> <1557@ames.UUCP> <442@meccts.UUCP> <708@riccb.UUCP>
Reply-To: mvs@meccts.UUCP (Michael V. Stein)
Organization: MECC Technical Services
Lines: 74
Xref: watmath net.politics:17314 net.sci:1227

In article <708@riccb.UUCP> jmc@riccb.UUCP (Jeff McQuinn ) writes:
>I'm sorry to differ (especially since I've always been a staunch defender
>of nuclear power) but a steam or chemical explosion is 'blowing up'.  
>What you mean is that it will not produce a nuclear explosion which is true
>however a steam or chemical explosion is capable of breaching containment
>and dispersing radionuclides to the envirnment.  Case in point - Chernobyl.

I wanted to emphasize that there is no physical way for a plant to
blow up like a nuclear bomb.  Since Chernobyl had no containment dome,
it didn't take much for it to start spewing its radioactive inventory
into the environment.  

Nuclear plants in the US of course do of course have containment domes.

>... Three Mile Island
>officials were quite worried about hydrogen build up.  Their calculations
>were showing that IF the temperature was high enough that hydrogen was
>disassociating from water in enough quantity to violate containment if
>ignited.  Fortunately hydrogen wasn't forming but I can't believe it's
>not possible for it to happen.

This is a misconception about Three Mile Island.  I will quote
from the "Staff Reports to the Presidents Commission on The Accident at
Three Mile Island."

	During the period March 29 thru April 1 the NRC became
	concerned over the possibility of the hydrogen in the reactor
	vessel exploding and the damage that would result. ... The
	mechanism psotulated for oxygen formation was the radiolysis
	of water.

	Radiolytic decomposition of water always occurs in water
	reactors, both while they are operating and after they are
	shut down.  Knowledge of this phenomenon and how to deal with
	it was evolved long ago and is discussed in detail in
	textbooks. The usual method (as in TMI-2) is to add hydrogen
	gas to the coolant to react with any oxygen produced and thus
	prevent its accumulation.  Only 0.1 cubic centimeters of
	hydrogen per kilogram of water will suppress the formation of
	oxygen; the hydrogen concentration in the reactor coolant was
	about 200 times this level at TMI-2.  No such explosion was
	possible.

The TMI commission later concluded that the "The basis for the NRC's
concern for an H2 O2 explosion in the reactor vessel apparently
stemmed from their habitual assumption of worst cases rather than
realistic estimates."  The Argonne National Lab review of the 
disaster concluded, "Since the radiolysis of water has been studied 
for decades by radiation chemists, it is hard to understand why 
none of this country's outstanding radiation chemists were contacted..."  

>I guess the real problem for reactors is the risk vrs benefit factor.  Since
>we had no real idea what the price to be paid is if the worst happens we
>have to assume total destruction of the area and a wasteland legacy for
>generations.  If anything is to be learned from Chernobyl, it should be an
>accurate picture of the price to be paid when all hell breaks loose.  

It isn't hard to see that the old Russian graphite reactors like the
ones at Chernobyl are a disaster just waiting to happen.  
From what I can tell, the power density of the Soviet graphite reactors
is so high, that only continuos cooling prevents the temperature 
from rising to the ignition point of the graphite.  (Someone 
correct me if I am wrong here.)  There are many reasons that 
Russian reactors are now  PWR.  

Yet again, the question isn't risk vs benefit - it is risk vs risk.
"Is it safer to produce this power through nuclear plants, or through
other means?" - should be the operative question.

-- 
Michael V. Stein
Minnesota Educational Computing Corporation - Technical Services

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