Talk:AP1000

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Contents 1 Passivity 2 Merge 3 Future of artices 4 AP600 5 Passively Safe? 6 Article Organization 7 Safety Concerns 8 American-ness 9 Article Renaming 10 The US government links here 11 Biggest contract

[edit] Passivity

It is my understanding that while the AP1000 has advanced passive features, it is not a fully passively-safe design in that some operator action is necessary to shut it down safely. However I do not have a source for this, and Westinghouse did not respond to my inquiry.

Westinghouse Electric Company 4350 Northern Pike Monroeville, PA 15146-2887 http://www.westinghousenuclear.com 412-374-4111

Simesa 19:45, 23 July 2006 (UTC)

[edit] Merge

Please discuss this in Talk:Advanced Pressurized Water Reactor

[edit] Future of artices

I should have seen that this article had been created. My apologies for the confusion. Now, do we keep both articles but cross-reference, or do we merge?

Also, what about the European Pressurized Reactor? Shouldn't we discuss how it is or isn't "advanced"?

Simesa 19:53, 23 July 2006 (UTC)

Well Mitsubishi also has a reactor called the APWR. Maybe I'll write an article about that one which should help add to the confusion.

wagsbags 16:30, 28 July 2006 (EST)

I think the Mitsubishi reactor you mention is the Mitsubishi/GE ABWR. DMWard 12:06, 2 March 2007 (UTC)

Nope, Mitsubishi US-APWR. It is mentioned here http://www.nrc.gov/reading-rm/doc-collections/fact-sheets/new-nuc-plant-des-bg.html

wagsbags 16:30, 23 April 2007 (EST)

[edit] AP600

Alright, my edits aren't incredible, but you really needed something more about this one. I think it's looking pretty good, next I would say go for pictures and then an actual description of the plant features. theanphibian 23:27, 10 April 2007 (UTC)

[edit] Passively Safe?

Many common sources refer to the AP1000 as passively safe, yet I have heard differently. See [1] section 7.4 (page 7-48 etc.). The limiting event for a PWR typically is Station Blackout, and it appears the AP1000 isn't passively safe in this event (see 7.4.2 first paragraph). I will continue to research this. Simesa 06:19, 21 April 2007 (UTC)

BrucePower Open House Appendix B2 has a Westinghouse flyer that says "AP1000 is an advanced reactor incorporating passive safety systems and a simplified plant design." and "Safety systems use only natural forces .... IN MOST CASES, these valves are fail-safe, that is, they require power to remain in their normal, closed position. No safety support systems such as AC power, HVAC, or cooling water are necessary." So Westinghouse doesn't claim that the AP1000 is fully passively-safe, and in the event of a Station Blackout some valves won't operate. I still don't regard this as conclusive. I'll cahnge the text to say "incorporates passive safety features". Simesa 06:44, 21 April 2007 (UTC)

To my expert knowledge, the AP1000 meets or exceeds all requirements set out by the NRC's Nuclear Power 2010 Program which will make it a Generation III+ reactor along with GE's ESBWR. I believe, though am not absolutely certain, that the NRC requirement for Generation III+ designs mandates complete and total passive safety systems (i.e. the plant shall be maintained in a safe-state by solely passive means in the event of design basis events). That leaves the open question of "what is a design basis event?" which probably has an extremely complicated answer. I AM certain however, that a loss of off-site power (the correct industry term) IS a design basis event. In the event of a loss of off-site power, the dedicated safety control system engages automatically from battery backup. This so-called safety system (which is quadruply redundant per NRC regulation) automatically takes the necessary control action to put the plant into the safe state. No pumps are required to maintain safe state. Any valves that must be opened are squib valves (exploding) that are deployed by the safety system. Any safety related valves that must be closed, which I do not think there are any, would have dedicated battery backup power. This should be investigated further, and the public NRC documents regarding the AP1000 (of which there are many volumes) should be sourced to provide an accurate yet neutral article. I am 100% confidant that the AP1000 meets or exceeds all NRC requirements for passive safety--this is publicly documented in the 2005 Final Design Certification documentation. Lwnf360 06:57, 10 September 2007 (UTC)

[edit] Article Organization

This article seems to imply that only Westinghouse designs qualify as "Advanced PWRs" which isn't really fair. It can certainly be argued that Westinghouse's designs are the only new PWRs that are passive but it seems like Mitsubishi's APWR and Areva's EPR would both be considered "Advanced" PWRs. I recommend that this article be modified to discuss APWRs in general and a separate article can be made for the AP1000 and AP600. The overall topic of passive nuclear safety is covered in the article "passive nuclear safety" which contains a list of passive reactors.

wagsbags 19:31, 23 April 2007 (UTC)

Agreed in a way. The "Advanced PWR" (APWR) is a proprietary (possibly trademarked) design by Mitsubishi, not a description of technology. This article is to be about the Westinghouse AP1000 which is NOT an APWR--they are in-fact competing designs. Your edits to this article to include information regarding the APWR should (and will) be moved to a separate page about the APWR. Overview of "advanced" (as understood by the industry) reactor designs is available at the Generation IV reactor page. The Westinghosue AP1000, and GE ESBWR reactors are Generation III+ designs as part of the Nuclear Power 2010 Program. I do not know, and neither does the NRC, weather or not the Mitsubishi APWR will satisfy the necessary NRC criteria to be a Generation III+ design. Lwnf360 07:07, 10 September 2007 (UTC)

[edit] Safety Concerns

Most scientific experts in the field of core meltdown simulations are of the opinion that the AP1000 is anything but safe.

The cornerstone of the AP1000's safety is the claim that natural convection cooling is good enough to prevent a breakout of corium out of the reactor vessel after a meltdown. Due to this, Westinghouse did a lot of handwaving since a core meltdown is now "safe". Unlike the EPR, their design did not go the extra leg to prevent a core melt at all costs.

For static cases, the numbers look good and the steel vessel should be cooled sufficiently so that the pressure vessel can't rupture. BUT, there are multiple problems once one starts looking at the dynamic mechanics of a core meltdown. One issue for example is so called "iron rain" puncturing the colder corium crust and causing much hotter liquid corium to burn through the reactor vessel.

Since a rupturing of the pressure vessel is "impossible", the conrete foundations of the AP1000 are unusually weak for a PWR. Hence the results of a corium leak would be much more catastrophic than in a current nuclear power plant. --Dio1982 14:14, 14 May 2007 (UTC)

Interesting reading, but you don't mention a single source and it doesn't fit reality as I've been reading it. I've never seen any claim by either Westinghouse or Areva that a vessel rupture is impossible. No existing U.S. plant has a foundation designed to be a "core catcher". I'm going to have to research these claims now - if I find something from a reputable source, I'll change the article. Simesa 00:37, 15 May 2007 (UTC)

The problem is that you won't find any scientific papers on this subject proving that Westinghouse is talking bollocks. Something about not biting the hand that feeds you. I can give you names of professors involved in meltdown simulations, who will repeat my opinion. You can also browse topics on core meltdown mechanics in [Nuclear Engineering and Design]. The principal Editor btw, and most of the editing board share the same opinion about the safety of the AP1000. IMHO, try contacting the principal editor. He is a very chatty and nice guy and might even be able to give you proper references. Also, unlike me, he is an expert on that area. --Dio1982 15:07, 15 May 2007 (UTC)

Edit:

Yeah, no US reactor has their foundations designed as a core catcher, BUT in a lot of cases of a core meltdown, thier foundations are strong enough to not let the corium melt completely through. In other cases, it will melt through... --Dio1982 15:10, 15 May 2007 (UTC)

Sir, I find your ideas to be facinating, though mostly unsourced. To say that the information we have on the next generation of reactors is one-sided would be an understatement. You really don't have much of a basis to compare two things until someone has sufficiently criticized them, and in this case there just hasn't been enough time for that to come out yet I think.

Still, I have a good idea of what they're shooting for with the PRA. You kind of have a list of things that can go wrong and probabilities associated with them, so you investigate the case where one thing goes wrong and then go through the list again, looking for double failures and evaluate the severity of each along with the cumulative probability (which I'm sure is all done by throwing it in a simulation), then you'll get a CDF and some other numbers. Then you tweak the design until the number goes down. I've heard people talk about this process with the International Reactor Innovative and Secure, which is another Westinghouse (mostly) project.

Everyone accepts the CDF as a paper number. What you're talking about above is different though, meltdown is WAY beyond core damage. I don't think the companies spend much time on that scenario because they hope it never happens. -Theanphibian ^{(talk • contribs)} 07:21, 6 July 2007 (UTC)

Erroneous. The claim made by Westinghouse is that the reactor can be maintained in the safe state through the use of only passive systems. The safe state is defined as:

1) reactor tripped (shut down);

2) core cooled adequately to prevent damage to the fuel assemblies;

This is what Westinghouse did the “handwaving [sic]” about. No one has ever maintained that a core meltdown is either safe or “impossible”.

What you refer to is a “beyond design basis accident” (a meltdown). Westinghouse has engineered safety features to mitigate beyond design basis accidents, but makes no guarantees. Westinghouse has separate PRA analysis and calculations regarding beyond design basis accidents. Westinghouse’s primary goal with beyond design basis accidents is “in-vessel retention” of molten core material (corium is a term fabricated by the anti-nuclear movement and is only used by Areva SA within the industry…gives me a hint as to whom you might work for and why your tone is overtly anti-Westinghouse).

In-vessel retention is exactly what it sounds like; molten core material is to be kept inside the reactor vessel. Westinghouse has demonstrated mathematically via PRA that in-vessel retention of molten core debris is extraordinarily likely for the AP1000. Three Mile Island provides an excellent empirical example of how commercial reactor cores behave in meltdown scenarios. The molten core material at TMI was retained in-vessel (which was not specifically designed with in-vessel retention in mind). Further, the accident barely damaged the liner of the reactor vessel let alone coming anywhere close to melting through it. See this excellent (content, not video quality) video of the TMI defueling for irrefutable proof of TMI’s in-vessel retention and an excellent look at how uncatastrophic the damage really was: http://www.libraries.psu.edu/tmi/video/. Basically, as vividly illustrated by TMI, if you keep the core covered with water, it will not melt.

Even taking the worst-case scenario of Chernobyl where the molten core material was not contained by its housing (RBMK reactors do not have the thick steel reactor vessels found in PWR and BWR designs) it only melted its way down into the basement before dissipating to the point of sub-critically. The necessity of specialized foundational features for the dispersion of molten core material has been disproved by the counter-examples of both TMI and Chernobyl. The EPR’s “corium spreader” underneath the reactor vessel adds no real safety benefit to the plant’s design as the molten core debris will have escaped into containment (rendering it forever useless and uninhabitable) and would have effectively dissipated on its own as evidenced by Chernobyl. The so-called corium spreader is an unneeded marketing gimmick, and a very poor one at that. Areva would do better to focus design efforts on in-vessel retention for its EPR.

Further, the foundations of the certified AP1000 design fully meet the NRC’s E1 qualification (which is essentially earthquake proofing). It is laughable to suggest that they are unsound. They meet or exceed the current NRC requirements which are more stringent than they were when existing plants were built.

Your tone indicates that you are either an anti-nuclear proponent, (in which case your opinions on nuclear power can be expressed in the Anti-nuclear movement article or best, in a forum other than Wikipedia) or an Areva SA employee/proponent attempting to discredit the claims made by Westinghouse regarding the AP1000 (in which case, you are violating the NPOV policy). Either way, your comments are unhelpful, unsourced, and inadmissible for this article. Lwnf360 08:38, 10 September 2007 (UTC)

[edit] American-ness

Does anyone else think this statement:

Examples include Westinghouse's AP600 and AP1000, Areva's EPR and Mitsubishi's US-APWR.

Seems a little American-centric, you know, considering that there is simply an APWR in existance? I'll work a little on this. -Theanphibian ^{(talk • contribs)} 07:37, 6 July 2007 (UTC)

[edit] Article Renaming

[edit] The US government links here

See [2]. And they're referring to the MHI design, so we should probably point this there. -Theanphibian ^{(talk • contribs)} 00:36, 19 December 2007 (UTC)

[edit] Biggest contract

It is strange to see that this $8 billion is the biggest contract ever... Look at the EPR page: http://en.wikipedia.org/wiki/European_Pressurized_Reactor#China —Preceding unsigned comment added by 193.195.186.14 (talk) 12:18, 5 June 2008 (UTC)