Nuclear power

macaque_2

kittypimms, comments in blue.

kittypimms wrote: »

The EPR (Proposed UK NB design) has active and passive protection systems; I'm afraid I've nicked this from Stickypedia, but it's more eloquent than I...:

• Four independent emergency cooling systems, each capable of cooling down the reactor after shutdown (i.e. 300% redundancy). 300% redundency does not count for much in the event of common mode failure. For example, cooling water is often dosed with treatment chemicals (anti fouling agents, oxygen scavangers etc). If someone connects the wrong dosing chemical (not uncommon), severe damage to an entire cooling system can happen within a very short time. Welders have been known to leave things in pipes. These can take months or years to move but out of the blue, they plug up a valve. Then there is alway catastrophic failure of a heat transfer pipe. The list is alarmingly long.
• Leaktight containment around the reactor. Leaktight is leaktight until its not leaktight
• An extra container and cooling area if a molten core manages to escape the reactor That is a meltdown!
• Two-layer concrete wall with total thickness 2.6 meters, designed to withstand impact by airplanes and internal overpressure. That is encouragingly thick but presumably there are holes and joints in this wall. Holes and joints where pressure systems usually fail.

Back in Pimmswords, if you look at the proposed locations for the UK NB (Hinckley, Seascale), you will notice that they are next to the sites of current/ in the process of decomms Nuke reactors, and that they have had an awful lot of investigation done on the above risks (flood etc). As Nuke plants are best to be built on coastlines, flooding and stability is a large consideration!

kittypimms

ninky wrote: »

okay kittypimms but how are the coolant systems supplied and how is that supply protected? this issue here has not just been the pumps but lack of suitable coolant and supply network.

Oh crikey, I feel like I'm back in my exams!
I can explain, but would need to go into moderators, physics and all that good stuff, which my brain can't take at this hour! For homework, please have a butchers at the EdF UK EPR pages, which has pretty cool cutaway graphics (and a video which explains the safety systems really well).
Coolant for the EPR is light water (normal water), which fortunatley is available in abundance on the coast - as in Japan. I think one of the issues there was the gennies breaking down, and being unable to get feedwater back into the reactors.

One of the mian diffs between the Japanese BWR, and the EPR is that in the EPR the nuclear, and non nuclear parts of the system are completely separate. In the BWR, the whole system is potentially radioactive. This is probably not a salient point at present, but I thought i'd mention it anyway.

1984ReturnsForReal wrote: »

Good post. I suppose they tested reactors rigorously also.


Anyway, you see that big crack that starts in Fort William & runs all the way to Inverness (well, I am sure it runs further but under the sea)?

http://maps.google.co.uk/maps?hl=en&client=firefox-a&rls=org.mozilla:en-US:official&q=map+of+scotland+fault+line+fort+william+to+inverness&um=1&ie=UTF-8&sa=N&tab=wl

I did not know that was a fault line. *makes note to learn more geography* apologies if you are correct

Either way, i'm sure some clever person somewhere has decided that scotland is not going to half fall off, and for C10MW potential it's safe to sink some snakes into the Firth (safer than the existing Nuke plant and Submarine depot one would assume...). Heck, if they survive the Haal, they'll survive anything...

I bid you goodnight chaps, and look forward to catching up tomorrow.

ninky_2

Kohoutek wrote: »

The "control mechanism" worked fine, all the reactors shut down immediately after the tsunami. It's the pumps that supply water to cool the reactors' cores that are broken.

the coolant mechanism is part of the control mechanism. you need the coolant mechanism to control the temperatures of the fuel even after the reactor is shut down.

1984ReturnsForReal_2

kittypimms wrote: »

I did not know that was a fault line. *makes note to learn more geography* apologies if you are correct

I am correct. I always wanted to [STRIKE]walk[/STRIKE] drive it but haven't got around to it yet.

Night.

1984ReturnsForReal_2

Apparently that fire is where they dump the spent fuel.

But hey, all under control

Kohoutek

ninky wrote: »

the coolant mechanism is part of the control mechanism. you need the coolant mechanism to control the temperatures of the fuel even after the reactor is shut down.

I wasn't aware that "control mechanism" referred to that.

ninky_2

kittypimms wrote: »

Oh crikey, I feel like I'm back in my exams!
I can explain, but would need to go into moderators, physics and all that good stuff, which my brain can't take at this hour! For homework, please have a butchers at the EdF UK EPR pages, which has pretty cool cutaway graphics (and a video which explains the safety systems really well).
Coolant for the EPR is light water (normal water), which fortunatley is available in abundance on the coast - as in Japan. I think one of the issues there was the gennies breaking down, and being unable to get feedwater back into the reactors.

.

but it still needs to circulate by means of some sort of pipework and make its way back to a cooling tower, no? this stuff has been damaged in japan and could be in the new designs i would have thought. there are many conceivable (and inconceivable probably) events which could cut off the supply of light water / coolant.

1984ReturnsForReal_2

5 & 6 are now heating up.

ninky_2

1984ReturnsForReal wrote: »

5 & 6 are now heating up.

yes that was reported a while ago. let's not get hysterical though....

1984ReturnsForReal_2

ninky wrote: »

yes that was reported a while ago. let's not get hysterical though....

Time to move the hosepipe along.