On 25/01/2020 12:58, newshound wrote:
On 17/01/2020 10:59, Jimk wrote:
The Natural Philosopher Wrote in message:


It not wuite that they couldnt stop making it, it is just that the cost
of keeping it running is so low.

ALL the cost in nuclear is capital, insurance and maintenance. That
happens whether its running or not. Fuel costs are very low.




Oh agreed.

What do we do with electricity if no-one wants it at that moment?
Â* Lightning displays? Build more interconnects ? -must be a
Â* viability constraint(s}?

Wasn't there some blurb on here about the negative effects of
Â* trying to "throttle back" nukes?


It is better to keep them running at full load (as long as that produces
some income) for two reasons. Firstly, it provides the best return on
investment, secondly it reduces thermal cycling. The fuel, core, boilers
and other structural elements have to be assessed for fatigue (as do the
turbines and other conventional plant, of course). I believe the French
plant are regularly load cycled.

It alters the nuclear reactions as well leading to xenon poisoning.

Wiki:
Some of the fission products generated during nuclear reactions have a
high neutron absorption capacity, such as xenon-135 (microscopic
cross-section σ = 2,000,000 b (barns); up to 3 million barns in reactor
conditions)[3] and samarium-149 (σ = 74,500 b). Because these two
fission product poisons remove neutrons from the reactor, they will
affect the thermal utilization factor and thus the reactivity. The
poisoning of a reactor core by these fission products may become so
serious that the chain reaction comes to a standstill.

Xenon-135 in particular tremendously affects the operation of a nuclear
reactor because it is the most powerful known neutron poison. The
inability of a reactor to be restarted due to the buildup of xenon-135
(reaches a maximum after about 10 hours) is sometimes referred to as
xenon precluded start-up. The period of time in which the reactor is
unable to override the effects of xenon-135 is called the xenon dead
time or poison outage. During periods of steady state operation, at a
constant neutron flux level, the xenon-135 concentration builds up to
its equilibrium value for that reactor power in about 40 to 50 hours.
When the reactor power is increased, xenon-135 concentration initially
decreases because the burn up is increased at the new, higher power
level. Thus, the dynamics of xenon poisoning are important for the
stability of the flux pattern and geometrical power distribution,
especially in physically large reactors.

Because 95% of the xenon-135 production is from iodine-135 decay, which
has a 6- to 7-hour half-life, the production of xenon-135 remains
constant; at this point, the xenon-135 concentration reaches a minimum.
The concentration then increases to the equilibrium for the new power
level in the same time, roughly 40 to 50 hours. The magnitude and the
rate of change of concentration during the initial 4 to 6 hour period
following the power change is dependent upon the initial power level and
on the amount of change in power level; the xenon-135 concentration
change is greater for a larger change in power level. When reactor power
is decreased, the process is reversed."

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Nut it is perfectly possible and a LOT cheaper than e.g hydrogen stiores
or anythiung to do with remeable energy

But a guaranteed and reliable "energy storage" option, like hydrogen
generation, off peak heating or EV charging are really well suited to
nuclear generation. Of course aluminium smelting, as was done next door
to Wylfa in Anglesey, is also a form of energy storage.

Hydrogen generation is NOT well suited to anything

I wpould say that synthetic diesel or syngas would be FAR more efficient
and less dangerous.

CCGTs are essentially jet engines modified to run on natural gas., They
could run instead on sythnetic avjet grade fuel.



--
Future generations will wonder in bemused amazement that the early
twenty-first centurys developed world went into hysterical panic over a
globally average temperature increase of a few tenths of a degree, and,
on the basis of gross exaggerations of highly uncertain computer
projections combined into implausible chains of inference, proceeded to
contemplate a rollback of the industrial age.

Richard Lindzen