Some interesting discussion here:
Message 27232446
From: E. Charters 3/13/2011 10:36:50 AM
Read Replies (1) of 74096
Japan's meltdown. The Three Mile Chernobyl effect.
Pumps that don't work, no back up, bad design, it appears that Nippon should get out of Nuclear Reactor on the Fault Zone Roulette while it still doesn't glow in the dark.
Reactors that are partially melted are not fixable. That means Fukusascreamie has to be concreted in and we say bye-bye for good. If they ever do build again it should be the kind where the cooling/promoter water dumps and it shuts down with scram immediately. Candu can du that in 1/100 of a second. Exposed core has no meaning in the Candu system, as when a crisis hits you drop heavy water, which is held up by compressed air when the reactor is running.
Pumps can fail. If in a Candu the pumps fail, then the core shuts down (scrams) and dumps moderator. When the power fails the reactor dumps heavy water which is the moderator inducing neutrons, and there is auto shut. Power keeps the moderator in place, so if it fails the shutdown in immediate. Scram in all reactors must take place in 4 seconds of heat rise or a runaway takes place. Emergency pumps/pipes failing is classic. Same thing that happened at Three Mile Island. Chernobyl was a shut off sensor and a wrong headed action to reduce temperature. Due to the Chernobyl situation of shut off sensors there was no way to tell if the reactor core was overheating.
No one has come up with a foolproof scram that cannot be blocked by a partially damaged core. If the reactor has overheated sufficiently, most times cadmium rods will not go in the tubes because of warpage and heat expansion. A better way is needed to shut down a runaway reactor. Fukushimwhatever did scram but a weakness in this system has been exposed. The emergency coolant pumps are still critical, and they were out of action. Cracked core? They are not saying. I think they should have a side-slotted reactor with guide slots for rods entering the core from the side, not back to front. If the rods were held in by control power and naturally swung out with weights, with cadmium rods swinging in the same way, it might guarantee a faster, more assured scram. Emergency cooling water would be held back by compressed air, and enter the reactor by gravity on power failure/switch. To cause circulation for up to 4 hours, a solid water tower would siphon water in flex lines into the core and back out, with emergency diesel pumps on line to take over when siphoning ran out. Flex lines into the core would allow pumping boric acid into the core if all else failed.
Better yet, take the reactor off the fault line and above Tsunami level.
Looks like 25,000 dead in the Tsunami/quake and perhaps 800 billion in damage. Kobe never recovered from the 95 quake and it hurt Japan's economy severely. This does not bode well.
EC<:-}
siliconinvestor.com
To: E. Charters who wrote (74076) 3/13/2011 10:44:02 AM
From: Land Shark Read Replies (1) | Respond to of 74097
I believe the Japanese reactor is a GE design? Pretty lousy safety systems IMO. CANDU is infinitely superior there. Makes me proud to be Canadian. The Conservatives want to sell AECL to say GE or any taker. I say keep AECL in Canadian hands.
siliconinvestor.com
To: Land Shark who wrote (74077) 3/13/2011 10:53:29 AM
From: E. Charters Read Replies (1) | Respond to of 74098
The design features of the AECL reactor, the Candu are not properly understood by our administration. They were developed in Canada over a 50 year period and include sensor, generator, and other rebuilds of contractor stuff that the US reactor experts have never dealt with. Most features of the Candu, even other than the core design and deuterium moderation are unique. The engineers who designed much of the unique features, some 15,000 design components, were never paid except for salary. Now Canada wants to give away their brains and hard labour to people who will look at it like a caveman would look at an Accutron wristwatch. It is a safe bet that the Politicians do not understand that a group of money mavens in a second rate electric company stateside have no clue how to run a Candu or rebuild what goes into it. They get a bunch of dry and dusty plans and ignore all the important stuff. Generator bearing metallurgy and design is as important as core design. Another case of selling our birthright for a mess of pottage. Avro Arrow, Candu good bye. It was nice to know ye.
Forgive them for they know not what they do.
EC<:-} |
