sci.energy

On Wed, 03 Oct 2007 09:19:52 -0700 someone who may be Alex
wrote this:-

>> UK nuclear power stations don't generate continuous electricity, as /search?hl=en&q=%22british+energy%22+cracks&bt...
>> demonstrates.
>>
>This implies that we should replace them with modern designs, which
>should achieve >95%.

While the Sizewell PWR is not a modern design, it has certainly
operated more reliably than the AGRs and their predecessors.

However, no generator operates all the time. It must be turned off
for planned and unplanned events over its lifetime (which is rather
longer than the "387 days of continuous operation" in the publicity
puff you quoted). Indeed I find the publicity puff mildly amusing.
If they are so proud of 387 days of continuous operation then I
suspect that reveals just how unreliable such plants are compared to
the claims that are made by the nuclear lobby of plants which run
continuously for years and years, if not decades.

>Well the entire barrage will have outages for much of day.

That rather depends on what you mean by "much". I suppose there
could be a design where there will be little or no output for 12
hours a day, but I suspect not. If it does not output for say four
hours a day then I would call that some of the day, not much of the
day.

However, a Severn Barrage would not be the only generating plant.
Given the fact that there are different tide times around the UK a
Severn Barrage might fit in well with tidal stream generation in the
Pentland Firth.

There is also the question of storage. When the fuel is free, as it
is with wind and wave generation, the inefficiencies of storage,
pumped-storage being the only large scale possibility at the moment,
are rather different to when storing electricity generated from
expensive fuels in nuclear, coal and gas stations.

>Further to that, you could still have an outage caused by the
>connections at either end of the barrage,

Simultaneous failure of two widely dispersed connections is
theoretically possible. However, the probability of this happening
is low. As I recollect it, connections on the Welsh and English
sides would be into diverse networks with a number of alternative
routes so that there would be no common point of failure which could
isolate the whole barrage.

Management of all electricity systems is a matter of probabilities,
as making systems to withstand almost any circumstances would be too
expensive.

>or barrage operation might
>need to be scaled down in the event of heavy flood water in the
>Severn.

Or perhaps the second largest coal fired power station in the UK
(and perhaps Europe) might suddenly have to be shut down completely
because a coal conveyor broke. What, this has already happened?
/output/2007/01/22/

The point is that we have a diverse electricity system which is
capable of withstanding such events.




--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
/acts/acts2000/00023-- #54