RE: £300k all-electric SLS only months away

[Gary C]

KDIcarmad said:

Chernobyl was people braking the rules, they were try to find out how long it took for the reactor to go critical. Not long!

Actually they were performing a coast down test on the turbine to prove how long it would continue to produce power after a reactor trip. They then operated the reactor below the given safety limits allowing Xenon to build in the fuel. Once the Xenon had built up, to keep the reactor operating, virtually all of the rods were withdrawn. Next came several effects, as the power increased, it reduced the Xenon inventory, which allowed power to increase, which reduced Xenon etc
Operating at too low a load, the feed flow was much to high, so the boiling level was high in the fuel channels leading to an over moderated core. As the power increased, the temperature increased and the boiling level fell so the moderation reduced, so the power increased, so the temperature increased (the positive void coefficient)
Finally, the control rods had none boron steed guides on the end of them. As the operators attempted to shutdown the reactor, the guides displaced more moderator from the active core without adding any neutron adsorber and so increased the reaction.

Power increased rapidly, boiled all the water, melted the zirconium tubes, which in the presence of water forms hydrogen, the hydrogen exploded and the rest as they say is history.

KDIcarmad said:

Do you know how many reactor there are in the UK, 16 operational nuclear reactors at nine plants and have this every gone bang like Chernobyl!

For fairness I must point out that the UK had the winscale fire long before TMI, Chernobyl and Fukushima.

Edited by Gary C on Tuesday 25th September 00:33

[ctallchris]

Pistonwot said:

Nuclear Power gives us Chernobyl and Fukushima.
Fission fusion and fission reactor plants are fairly uncontrolled with these 2 shining examples a testament to this.
So that leaves us coal and oil/gas which pollutes more than cars.
Why no mention of Hydro?

I'm sorry but you clearly dont have a clue what you're talking about.

There has never been a nuclear fusion and never will be a nuclear fusion accident with the technology available.

In nuclear fission there is a neutron cascade nwhich had to be controlled in order to prevent meltdown. It is possible to build pebblebed style reactors which cannot melt down due to the design of the reactor chamber.

NUclear fusion requires a huge ammount of energy to be thrown into the reaction contsatly just to keep it going. Pull the plug and there is no more reaction.

Basically stop taking your knowledge about science from movies. they lie

[JonnyVTEC]

KDIcarmad said:

Chernobyl was people braking the rules, they were try to find out how long it took for the reactor to go critical.

The fact it had a positive temperature coefficient of reactivity didn't help matters either compared to a more modern water reactor where as the opposite happens and as things warms up the reaction decreases due to the water atoms moving further apart.

[Gary C]

JonnyVTEC said:

The fact it had a positive temperature coefficient of reactivity didn't help matters either compared to a more modern water reactor where as the opposite happens and as things warms up the reaction decreases due to the water atoms moving further apart.

Though in the uk most reactors are graphite moderated. These have a fast negative fuel coefficient and a very slow positive moderator coefficient. All none soviet water reactors are under moderated as you say so an increase in temperature tends to a reduction in reactivity. The nuclear sub reactor is a prime example as its virtually self regulating.

All reactors have the risk presented by the decay heat. At trip a reactor continues to produce heat which must be removed as demonstrated in Japan.

Visited Smolensk RBMK in 2005. Spooky to stand on the pilecap of a sister of chernobyl.

[KimZ]

Gary C said:

For fairness I must point out that the UK had the winscale fire long before TMI, Chernobyl and Fukushima.

Edited by Gary C on Tuesday 25th September 00:33

Very interesting posts Gary C ~ Ta for sharing!

[KDIcarmad]

Gary C said:

KDIcarmad said:

Chernobyl was people braking the rules, they were try to find out how long it took for the reactor to go critical. Not long!

Actually they were performing a coast down test on the turbine to prove how long it would continue to produce power after a reactor trip. They then operated the reactor below the given safety limits allowing Xenon to build in the fuel. Once the Xenon had built up, to keep the reactor operating, virtually all of the rods were withdrawn. Next came several effects, as the power increased, it reduced the Xenon inventory, which allowed power to increase, which reduced Xenon etc
Operating at too low a load, the feed flow was much to high, so the boiling level was high in the fuel channels leading to an over moderated core. As the power increased, the temperature increased and the boiling level fell so the moderation reduced, so the power increased, so the temperature increased (the positive void coefficient)
Finally, the control rods had none boron steed guides on the end of them. As the operators attempted to shutdown the reactor, the guides displaced more moderator from the active core without adding any neutron adsorber and so increased the reaction.

Power increased rapidly, boiled all the water, melted the zirconium tubes, which in the presence of water forms hydrogen, the hydrogen exploded and the rest as they say is history.

KDIcarmad said:

Do you know how many reactor there are in the UK, 16 operational nuclear reactors at nine plants and have this every gone bang like Chernobyl!

For fairness I must point out that the UK had the winscale fire long before TMI, Chernobyl and Fukushima.

Edited by Gary C on Tuesday 25th September 00:33

Thank you for correcting and adding to what I said. I had forgotten the Winscale fire.