'Why the NRC Must Act Decisively on July 1, 1999
Power_Grid
Date:
1998-10-17 10:27:50
Subject:
Why the NRC Must Act Decisively on July 1, 1999
Comment:
The Nuclear Regulatory Commission has told nuclear power
companies that they must be compliant by July 1, 1999. I had not
understood why until I received this letter. The NRC faces a
technologically imposed deadline: it takes six months to cool the
cores. It takes electrical power to do this. In short, it takes the grid
to enable the plants to shut down safely.
So, I have been wrong. I have said that the NRC would have to act
by late 1999. Now I see that the NRC must act on its official
schedule. This will be a cricual deadline. If the NRC backs down,
then either (1) the plants will be dangerous in 2000 as they cool
down on diesel generator power; or (2) the NRC is blowing smoke;
it will not shut down the plants in 2000.
* * * * * * *
As a nuclear engineer, I read with great interest the article about the
NRC mandate for all nuke plants to be compliant or else shut-down.
I was discussing the article with a couple of friends of mine who are
also nuclear engineers. We were musing about the NRC's
deadline---July 1, 1999.
At first we could not understand why the plants needed to be
shut-down six months in advance. Then it hit us. A 1000 electric
megawatt nuclear plant generates about 3000 megawatts of heat
energy. That is 3 BILLION watts of heat energy. When a plant is
scramed, the nuclear fission stops almost instantaneously, however
the core still generates a tremendous amount of heat. This heat is
called residual heat and is a result of the natural cooling-off of the
core. under normal circumstances, special pumps called Residual
Heat Removal pumps circulate water through the core to keep it cool
and remove excess heat. Emergency diesel generators can supply
power to these RHR pumps whenever power to the plant is lost.
Also under normal circumstances, it takes approximately 4 months
(depending on the operating power of the core) to cool a core to the
point that loss of cooling will not damage the core. In other words,
nuclear plants need six months to ensure their cores are cool enough
and won't melt if power to the plant is permanently lost.
Imagine the ensuing mess if nukes can't cool their cores.
Nicholas Vrettos |
