Chernobyl Nuclear Accident Congressional Hearings Transcript

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Senator Domenici. I appreciate the answer. Thank you, very
much.
Mr. Taylor, would you do me a favor—probably we could get this
information somewhere else, but nonetheless, if you have it—you
gave us the example of cancer from the high-level radiation resulting
from the bomb. I understand Dr. Beyea thinks it might not be
totally relevant, and I am not going to pass judgment on that.
But, can you furnish us or give us the source of that information
so that someone like myself and other members would be able to
talk about it, examine and see what those numbers mean?
Mr. Taylor. It comes from the U.S. Commission that was designated
to follow up on the survivors of the bombings, and I can give
you the exact terminology, location, and i will do that.
Senator Domenici. Would you do that through our staff, please?
Staff, would you put that together, at least for this Senator and
circulate it if anybody else is interested; I would like to have that
myself, in all events.
What is an inherently safe reactor mean?
Mr. Taylor. I would like to comment. I don't think there is anything
in this world. Senator, that is inherently safe. There has
been a tradition in the nuclear power industry in the United States
to take advantage of intrinsic features in the systems that will
make them more stable and easier to control. The very earliest discover,
with great glee, was that it v/as possible to have a negative
temperature coefficient.
That is, if the temperature of the reactor went up, the reaction
rate went down. So you had built in the physical laws of the
system a tendency to keep stable. We have maintained that as a
very important design feature.
Another one is the natural circulation, the capability for coolants
to, by thermal convection, provide cooling without the need for
pumping, and equipment to move the coolant around.
Another in the liquid metal systems has been what is called the
Dopplar coefficient, an effect, again a physical law in the fuel. As
the power goes up, there is a tendency for the reaction rate to come
down, and the gas-cool reactor, one of the benefits of graphite is
that it represents, in the way it is operated in this country—not
necessarily in the Soviet Union—a large heat sink which captures
excess heat and minimizes the need for people to act immediately.
I think from our experience, we should enlarge on the contribution
of these intrinsic safety features in all our systems; lightwater,
gas-cooled, and liquid metal.
But to say that we could carry them to the point that we have
intrinsic safety, it is a Madison Avenue statement.
Dr. Dean. I agree with much of what Mr. Taylor said, but when
we use the word "inherently" safe, passively safe, this is a reactor
design which has the power limited such that there can be upsets
in the system, that operator action is not required; that no automatic
powered safety systems must come into operation to protect
the health and safety of the public.
For example, if you were to lose feedwater. You lose it, the operators
don't have to worry about reestablishing feedwater to protect
the safety of the public. The reactor is located underground and it
can lose all power, all cooling, except the cooling that naturally