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."

Re:Good, good.

[thermopile]

Very glad to see the US NRC, despite all of its recent antics [politico.com], was still able to approve a new reactor design.

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 [nuclearstreet.com]. It's just astounding.

why isn't thorium being developed?

[DevotedFollower]

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 [telegraph.co.uk] The US and their history with thorium and further thorium info: http://www.youtube.com/watch?v=P9M__yYbsZ4 [youtube.com]

Re:Progress

[Anonymous Coward]

Is an even older plant than Chernobyl.

Re:why isn't thorium being developed?

[thermopile]

Thorium isn't being developed in the US for 2 reasons:

1. Current uranium-based reactors are more affordable than thorium reactors.

2. The path for licensing a thorium-based reactor in the US is exceedingly uncertain.

While a thorium-based fuel cycle may be a good idea, it's just not going to be done by any commercial enterprise today. The costs and risks are too high. When staring at a $5B initial investment cost, any electrical utility is going to favor the known route ... which, frankly, could just as easily mean building 10 natural-gas fired plants instead of 1 big nuke.

India, however, is going full-bore on a thorium-based fuel cycle, and has already built a few reactors that are capable of accepting thorium. Copied shamelessly [world-nuclear.org] from world-nuclear.org:

India's plans for thorium cycle

With huge resources of easily-accessible thorium and relatively little uranium, India has made utilization of thorium for large-scale energy production a major goal in its nuclear power programme, utilising a three-stage concept:

Pressurised heavy water reactors (PHWRs) fuelled by natural uranium, plus light water reactors, producing plutonium.

Fast breeder reactors (FBRs) using plutonium-based fuel to breed U-233 from thorium. The blanket around the core will have uranium as well as thorium, so that further plutonium (particularly Pu-239) is produced as well as the U-233. Advanced heavy water reactors (AHWRs) burn the U-233 and this plutonium with thorium, getting about 75% of their power from the thorium. The used fuel will then be reprocessed to recover fissile materials for recycling.

This Indian programme has moved from aiming to be sustained simply with thorium to one 'driven' with the addition of further fissile plutonium from the FBR fleet, to give greater efficiency. In 2009, despite the relaxation of trade restrictions on uranium, India reaffirmed its intention to proceed with developing the thorium cycle.

A 500 MWe prototype FBR under construction in Kalpakkam is designed to produce plutonium to enable AHWRs to breed U-233 from thorium. India is focusing and prioritizing the construction and commissioning of its sodium-cooled fast reactor fleet in which it will breed the required plutonium. This will take another 15 â" 20 years and so it will still be some time before India is using thorium energy to a significant extent.

Is it designed around passive nuclear safety?

[mark-t]

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.

Re:Is it designed around passive nuclear safety?

[Trepidity]

Sort of. Unlike Fukushima-style reactors, it doesn't require an external power source (like the DC generators that failed there) to cool the core following a shutdown, but it's not a purely passive system. Wikipedia's summary [wikipedia.org] is decent.

That ship sailed long ago

[dbIII]

if it doesn't want to be buying technology off China 10-20 years down the line

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.

Re:Progress

[AK Marc]

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.

Re:Progress

[Anonymous Coward]

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.

Re:Progress

[MightyYar]

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

Re:Progress

[CnlPepper]

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.

Re:That ship sailed long ago

[Anonymous Coward]

Westinghouse employee here. The AP1000 final design certification was approved in 2006 [nrc.gov], and the design (including the predecessor AP600) began long before that (mid 90s).

Toshiba acquired Westinghouse in late 2006 [mediaroom.com]. Prior to that, Toshiba had partnered with our domestic rival, General Electric to build plants in Japan. We sell Pressurized Water Reactors (PWRs), they sell Boiling Water Reactors (BWRs). They're pretty different.

Even now that they own us, there is very little technical collaboration between our two entities. If there's a technological connection between Westinghouse and Toshiba that predates any of that, I'm certainly not aware of it.

Re:but

[MightyYar]

It only needs to be as safe as automobiles, and it far exceeds that.

Re:Progress

[Anonymous Coward]

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.

Re:Progress

[CnlPepper]

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.

Re:Progress

[Omniscient Lurker]

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.

Re:Progress

[HiddenCamper]

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.

Re:Is it designed around passive nuclear safety?

[HiddenCamper]

Nuclear engineer here The plant actually runs on generator power under normal conditions. Nuclear plants have 4 AC power sources. The normal source is taking generator power BEFORE it goes out to the power grid in through the auxiliary transformers and then using internally for 4160 and 6900V power. Because this power hasn't gone to the grid yet, we don't "pay" for it. Additionally, when we are shut down, we can disconnect the generator and backfeed power in through the aux. transformers for power. This is typically an emergency/contingency action or an outage action to allow us to work on the reseve power system. The standby source comes in from a different grid (or a different part of the same grid), and comes in from the reserve auxiliary transformers (sometimes called startup transformers). Because this is bringing power in from the grid, we "pay" for it (we get billed by the grid). The emergency reserve transformer (sometimes called backup transformers) comes from a completey different grid than everything else. They power ONLY safety systems. Normal systems cannot use it. The diesel generators are safety seismic and environmentally designed backup power systems. There is 1 DG for each primary safety division which has a decay heat removal function, and an additional DG for coolant injection. Most plants also have a fourth or fifth DG for DC power chargers only. There is enough fuel on site for a minimum of 1 week for all generators running 2% above maximum theoretical load of all equipment under worst case design conditions. The reality is you can probably get another 2-3 days past that since it assumes that like, air coolers and air heater are both on at the same time in the same area, and once you've stabilized an accident or emergency condition you can put most of the redundant safety systems into standby to conserve fuel.

Re:Progress

[HiddenCamper]

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.

Re:Progress

[HiddenCamper]

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.