Slashdot Mirror
NRC Approves New Nuclear Reactor Design
hrvatska writes "The NY Times has an article about the U.S. Nuclear Regulatory Commission approval of the design of Westinghouse's AP1000 reactor for the U.S., clearing the way for two American utilities to continue the construction of projects in South Carolina and Georgia. The last time a nuclear power plant in the U.S. entered service was 1996. The AP1000 was discussed on Slashdot a few years ago."
If you haven't seen, the scale of construction on these projects is mind-bogglingly large. See here for some juicy pictures of the site under construction. It's just astounding.
"Diplomacy is something you do until you find a rock." --Richard Pound
The NRC should approve some more thorium reactors if it doesn't want to be buying technology off China 10-20 years down the line. From what I understand Thorium (especially LFTRs) are far safer. They are "walk away safe". My suspicion is that it is too late for the US to catch up though. As the article mentions..China already has a bunch these coming online in 2013...while it just got approved in the US. China is also filing more patents...they are progressing much fast than the states at this point. China and thorium: http://www.telegraph.co.uk/finance/comment/ambroseevans_pritchard/8393984/Safe-nuclear-does-exist-and-China-is-leading-the-way-with-thorium.html The US and their history with thorium and further thorium info: http://www.youtube.com/watch?v=P9M__yYbsZ4
Is an even older plant than Chernobyl.
Passive design reactors are, by far, the safest type of reactor in the world (in fact, a meltdown is virtually impossible, because even catastrophic failure results in the core cooling down instead of heating up), and IMO, building *ANY* other type of reactor is just setting yourself up for a possible incident that's going to lead to eventual regret.
File under 'M' for 'Manic ranting'
Almost all of the post 1970s technology in the AP1000 came directly from the nuclear division of Toshiba in Japan after merging with Westinghouse. It's technology bought off Japan instead of China but still looks like what you are worried about.
India is leading with Thorium at the moment and appear to have taken the US advances and added a couple of decades of development. Accelerated Thorium (mixed fuel such as expired weapons material or used uranium fuel rods in addition to thorium) holds paticular promise.
The passive designs have been proven unsafe as well (they age into unstable configurations, even - or especially - the pebble bed ones). The only "safe" passive ones are the ones used in satellites where no runaway fission is even possible because it is relying on the native radioactivity, and not some amplified chain reaction.
Learn to love Alaska
There exist no reactor in the western world that is capable of having runaway, "amplified" chain reaction. If you have done any research, you would realize that positive void coefficient reactors are even illegal in the US and almost no one builds them. (CANDU is the only one that has a small positive void coefficient mostly due to Pu during course of running the reactor, but that is accounted for).
The problem is ALL reactors produce enough power that they can cause the reactor to melt.
Fukushima reactors were OFF. There was NO nuclear reaction. They melted because of something called daughter elements produced in fission. I guess one can say, the meltdown occurred precisely due to the scenario you are talking about
The only "safe" passive ones are the ones used in satellites where no runaway fission is even possible because it is relying on the native radioactivity
DING DING! That is exactly why Fukushima had a melt down.
I also question your understanding of AP-1000. The design is clearly passively safe. It requires no moving parts to maintain cooling of the native radioactivity of the daughter elements.
Then what generated the heat that caused the meltdown?
Radioactive decay, not fission.
It still has a cooling system with moving parts. Why?
I am by no means a nuclear expert, but my understanding is that:
(a) the passive cooling is for when the reactor is shut down but cooling off (think Fukushima), not while operating
(b) normally you need to move the heat over to the turbines in the most efficient way possible
W..w..W - Willy Waterloo washes Warren Wiggins who is washing Waldo Woo.
I'm astonished you compared averages and attempted to use this to backup your argument. Go and have a look at the distribution of power produced by each of those coal plants. You'll see that the majority of the 42% comes from a few large scale coal plants, equivalent in scale to the nuclear installations.
It only needs to be as safe as automobiles, and it far exceeds that.
W..w..W - Willy Waterloo washes Warren Wiggins who is washing Waldo Woo.
I'd call it "automated"
That's the first I've seen anyone characterize gravity as automation.
Since you appear to believe you have some credibility defining these terms, we should compare your thinking to those that actually do. To a nuclear engineer designing an emergency cooling system passive means no pumps, no power and no control. By that criteria the AP600/1000 designs are passive.
Everything about this emergency cooling system design relies on the integrity of containment. Containment, in this case, is a large free standing steel shell (as opposed to stressed concrete.) Threats to this vessel include kinetic impingement and corrosion. The former was the cause of a recent AP1000 design modification the NRC insisted on, based on a hypothesized attack involving an airliner. The latter can only be addressed through diligent and costly surveillance of the vessel throughout its lifetime ... just the sort of thing that tends not to survive bean counters.
The point is that there are plenty of legitimate criticisms that one can make of the design. Kibitzing about your peculiar notion of 'passive' isn't a very good one.
I think it is worth noting that the AP1000 design would have prevented core damage and radioactive release at Fukushima. The AP1000 design is exactly suited to the 'blackout' conditions that prevailed in Japan.
No-one said passive systems were easy, in fact they are quite difficult to design and required modern computational power to produce. That is the stark difference between the old designs and the new designs such as the AP1000 - computing power. We can now model the nuclear, thermal, chemical and structural processes to a degree that was impossible when the first and second generation nuclear designs were produced. This is one of the reasons we can much more confident in the generation III+ reactors.
Nuclear Engineering (student) here.
>The decay was an atom splitting into two smaller atoms and energy, which is fission.
Fission in the context of engineering refers to the use of neutrons to force atoms to split, not to naturally decaying isotopes.
>The question was of why would fukishima need active cooling when passive cooling is so "easy" to do.
Because it wasn't designed to use passive cooling. Passive cooling requires your reactor to be designed to facilitate it (all gen 3+ are designed like thisâ"I believe the NRC refuses to certify anything that is nonpassive). Passive cooling refers to not requiring power to run the coolant pumps or anything. The AP1000 is designed to using convection of steam inside the containment building to cool the reactor.
Nuclear engineer here. Decay is not Fission. Fission is splitting the atom. Decay is the act of a radioactive atom to reduce itself closer to a stable groundstate. Fission is controllable and is directly related to neutron population, and if we stop neutron production with control rods, fission stops. Decay is not controllable, and happens all the time no matter what until the material reaches a stable ground state. All light water plants, except the AP1000, need active cooling. (The GE ESBWR doesnt need active cooling either, but its design isnt approved or even completed yet). After shutdown the core is still boiling about 600 gpm of water at 1000 pounds pressure (in a BWR). this is due to the radioactive WASTE products decaying. The fuel isn't doing anythign after shutdown, but the waste products are trying to become stable again.
Sattilites use RTGs, not nuclear reactors. And RTG makes use of decay heat and the seebeck effect to generate a voltage difference. Very different from a nuclear reactor. As for nuclear power plants, the chain reaction is not "amplified", it is a chain reaction, nothing more or less. We actually control it using control rods and neutron absorbers. These plants can shutdown in less than 3 seconds, and only once has a plant failed to scram when called upon, and the backup scram system automatically did the job instead.
The problem is the NRC notices this stuff. I'm going to take a guess you've never been questioned by the NRC, but I have (nuclear engineer). They get on top of even the smallest hint of bullshit or mistake in logic or even poor quality packages. They would have already known that you are missing a safety system which they REQUIRED you to have and you LEGALLY COMMITED to have and you would have your project stopped and reviewed again which would caost MUCH MORE than 15% to get the project moving forward again. We are told to never ever challenge our NRC commitments or requirements, because the cost of messing up is a LOT more than what you 'could' gain by cutting something.