Re: Kursk: Potential nuclear hazards

[BERNARD L COHEN <blc+@PITT.EDU>]

On Tue, 4 Sep 2001, Bjorn Cedervall wrote:

>

> Now, on page 15 it says that the reactor is pressurized by gas (argon or

> nitrogen). -Reserve gas? I don't understand how this gas comes into the

> picture. Can anyone explain?



	--In a PWR, the pressure is regulated by the pressurizer which has

water from the reactor in the bottom and gas in the top. The interface is

kept in sight so one knows that the water pressure is equal to the gas

pressure which is easily measured and regulated. The pressurizer gained

notoriety in the TMI accident because it was filled with water and no

interface was visible. The operators interpreted this as meaning that

there was too much water in the reactor and hence they throttled back

(almost shut down) the emergency cooling water. But the reason the

pressurizer was filled with water was that the exit valve was stuck open

so water was pouring out thru the pressurizer. Thus the water was lost and

not replaced.



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