Chernobyl Nuclear Accident Congressional Hearings Transcript

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QUESTION 10. (Continued) - 7
supplies have been located outside the containment, which results
in flow paths for highly contaminated water that can effectively
bypass the containment. Core power densities have been driven to
the limits of materials capabilities such that, in the event of a
loss of coolant" accident, external water supplies must be rapidly
injected into the core to keep it from melting. And, the balance
of plant is designed to lower standards than the reactor systems
to minimize the costs. These competitive forces are what led to
the level of safety achieved in the current generation of nuclear
power plants and are in part responsible for the poor performance
of some of our plants.
Taking the above together and absent fundamental changes in the
nuclear industry and in the Nuclear Regulatory Commission, I
believe we should expect to see a severe core damage accident at a
U.S. plant within the next 20 years.
However, a core melt accident does not automatically mean that
there will be significant offsite releases of radioactivity.
According to the NRC staff one cannot preclude the release of
large fractions of the core inventory. Using extrapolated data,
release magnitudes at Chernobyl were, according to the NRC staff,
similar to those in the Reactor Safety Study {WASH-1400) release
categories PWR 1, 2 or BWR 1, 2. However, uncertainties in
atmospheric transport, dispersion, measurements, and other
possible release scenarios are such that one cannot preclude