GP: RE: Re: green-power Digest 10 Feb 2002 18:52:23 -0000 Issue 39

["Weststeijn, Andries" <Andries.Weststeijn@essent.nl>]

Gentlemen,

Please let me add a comment or two into the ongoing discussion:

Mr Stephen Bray writes: Friday, February 15, 2002 10:15 AM
	Britain's nuclear plants are privatized. They are
	mostly owned by a privatised company called British
	Energy who are currently having some issues in Britain
	with the political climate which seems to be edging
	towards this policy of greener energy.

To the best of my knowledge these nuclear plants are still government owned.
Simply since the conventional power plants in the UK were privatized (split
off) in two private companies. And neither of them liked to take on the
financial risks of the old Magnox reactors. Mind you, I say financial risk
(incl insurance risk), I don't say technical of safety risk.

Mr Bray continuous:
	This was supposedly put in place because
	of the inability of nuclear power stations to fluctuate
	their output as traditional coal and gas fired plants
	can.

In general, this "inability" has been an easy way of avoiding the
requirement to lower power output at nights, which would decrease the
kilowatthours produced and raising the cost of capital in the kilowatthour
price. No reactor operator wants to see his extraordinary expensive factory
to lay partly idled.
Remember in the nuclear power world the variable cost of fuel is LOW, but
the fixed cost of capital is HIGH.

Now, just as an example: how does France manage to get by at nights with
almost 80% of the power generation being nuclear, and the power load of the
grid at night going down to 50% of the day time peak?
Right on: by throttle ling those nukes back in a timely manner.
Or think of the aircraft carriers with variable speeds: in principle not
much different.
I.e. it can be done.

But a nuclear WATER-cooled reactor as in France and the US is a low
temperature operation. 
A coal or gas plant is a high temperature operation.
This difference, by the way explains most of the difference in thermal
efficiency, i.e. relatively low for nuclear. 

A nuclear GAS-cooled reactor as in the UK is also a high temperature
operation (sounds good, but eats its own high efficiency by its own high
compressor power use).
I expect this type of reactor can react quite quickly to fluctuating power
requirements. But the high temperature regime might require common prudence
in the rate of change in temperature, like all high temperature applications
(think of the cold engine of your car in the morning).
Since I don't know exactly what the Magnox reactors can handle in terms of
temperature variability, it would be interesting to hear from somebody
informed.