[ RadSafe ] Melting a reactor?? That a delinquent operator can do more damage from out side is an exaggeration

[parthasarathy k s]

I am surprised to note that the first sentence in the quote went unchallenged. 
All reactors can be shut down quickly if anything goes wrong Modern reactors 
have two fast acting shut down systems in addition to other reliable systems to 
shut them down. Reliability is assured by redundancy and diversity.

Even when the reactor is shut down the heat energy released from the fuel due to 
decay of radionuclides accumulated when the reactor was operating is substantial 
at about 15 % of the full power. It is sufficient to melt the core.

It is not the melted core that damages the containment. The break of the coolant 
channel may cause a loss of coolant accident. The containment is designed to 
maintain its integrity in a design based accident. It can with stand the 
pressure exerted due to rapid release of steam released when the coolant tries 
to quench the heat from a heated nuclear core.

We have to continuously operate the coolant system even when a reactor is shut 
down. Designs of the reactors are fairly standardized. Location of the coolant  
system is not a secret. That a delinquent operator is more equipped to do 
serious damage from outside is an exaggeration.

Over all security measures which are already strengthened will take care of all 
eventuality. Appropriate security clearances for the personnel must be in place. 
While we must analyze all possibilities, we need not go overboard by scary 
conditions described by ill informed columnists.

Regards
Parthasarathy






________________________________
From: Steven Dapra <sjd at swcp.com>
To: radsafe at agni.phys.iit.edu
Sent: Mon, 3 January, 2011 7:45:57
Subject: [ RadSafe ] Melting a reactor??

Jan. 2

    This quote is from an editorial page article written by Charles Faddis and 
published in the NY Times.

"But there's no way to quickly shut off a reactor: the heat that builds up 
inside it is so intense that even if something goes wrong, cooling water must 
continue to circulate through its systems for days before it is safe.

"If the cooling system malfunctions, even if the rest of the plant is operating 
safely, the heat will literally melt the reactor and its concrete containment 
shell, releasing radioactive gas into the atmosphere  in other words, a partial 
nuclear meltdown like that at Three Mile Island in Pennsylvania in 1979."

    Is it true that reactor heat will melt the containment vessel ("shell")?

    The link to the Faddis' NYT article is:

http://www.nytimes.com/2010/05/06/opinion/06Faddis.html?_r=1

Steven Dapra

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