ML20247L057
| ML20247L057 | |
| Person / Time | |
|---|---|
| Issue date: | 05/15/1998 |
| From: | Advisory Committee on Reactor Safeguards |
| To: | |
| References | |
| ACRS-T-3037, NUDOCS 9805220304 | |
| Download: ML20247L057 (163) | |
Text
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. 01G i\\ A OFFICIAL; TRANSCRIPT OF PROCEEDINGS AV ? NUCLEAR REGULATORY COMMISSION-ADVISORY' COMMITTEE ON REACTOR SAFEGUARDS
Title:
, SUBCOMMITTEE ON ADVANCED REACTOR DESIGNS - Docket No.:. {$yf*S$$b1NAL l Tc e M ITE l a M/S T-2E26 l f, 1 c. n 3 0 -Work Order No.: ASB-300-278 i () LOCATION: Rockville, Maryland l DATE: Friday, May 15,1998~ PAGES: 397 - 509 l l 9e052203o4 980515 Ff!fgggfRS PDR () ) l ,,.,.s>* L - ANN RILEY & ASSOCIATES, LTD. lJ 1250 I Street, NW, Suite 300 D. AMSOffilfdiffleia'n for aeCe 0:'the >nm? fen
l l lf lNJ i i l DISCLAIMER i l UNITED STATES NUCLEAR REGULATORY COMMISSION'S ADVISORY COMMITTEE ON REACTOR SAFEGUARDS i l l l 4 l. MAY 15, 1998 i l l The contents of this transcript of the proceeding j of the United States Nuclear Regulatory Commission Advisory Committee on Reactor Safeguards, taken on May 15, 1998, as reported herein, is a record of the discussions recorded at the meeting held on the above date. l This transcript had not been reviewed, corrected and edited and it may contain inaccuracies. I l l i I J
397 l' UNITED STATES NUCLEAR REGULATORY COMMISSION 2 ADVISORY COMMITTEE ON REACTOR SAFEGUARDS 3 4 SUBCOMMITTEE ON 5 ADVANCED REACTOR DESIGNS 6 7 8 U.S. Nuclear Regulatory Commission 9 Two White Flint North 10 11545 R.ockville Pike 11 Rockville, Maryland 20852-2738 12 l 13 Friday, May 15, 1998 r 14 15 The Committee met pursuant to notice at 8:30 a.m. 16 17 MEMBERS PRESENT: 18 JOHN BARTON, ACRS Chairman I l 19 MARIO FONTANA, ACRS Member i I 20 ROBERT SEALE, ACRS Member 21 THOMAS KRESS, ACRS Member 22 DON MILLER, ACRS Member 23 DANA POWERS, ACRS Member 24 WILLIAM SHACK, ACRS Member 25 l i O ANN RILEY & ASSOCIATES, L'IT). j Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034 w__________-_-____________._____
i 398 1 PROCEEDINGS ' () 2 [8:30 a.m.) 3 CHAIRMAN BURTON: The meeting will now come to 4 order. This is a meeting of the ACRS subcommittee on 5 advance reactor designs. I am John Barton, Chairman of the 6 subcommittee. ACRS members in attendance are Mario Fontana, 7 Thomas Kress, Dana Powers, Robert Seale, William Shack. We 8 also have in attendance ACRS consultant James Carroll. 9 The subcommittee will continue its review of the 10 AP600 design. Specifically, the subcommittee will review 11 chapters 3, 6, 14, 16 and 17 of the AP600 safety analysis 12 report, the risk assessment, regulatory treatment of 13 non-safety systems and the associated NRC staff's 14 evaluation. The subcommittee will gather 'nformation, i () 15 analyze relevant issues and facts and formulate proposed 16 positions and actions as appropriate for deliberation by the 17 full committee. 18 Noel Dudley is the cognizant ACRS staff engineer 19 for this meeting. The rules for participation in today's 20 meeting have been announced as part of the notice of this ] l 21 meeting previously published in the Federal Register on 22 April 22, 1998. A transcript of the meeting is being kept 23 and will be made available as stated in the Federal Register 24 notice. It is requested that speakers first identify I 25 themselves and speak with sufficient clarity and volume so i O I I ANN RILEY & ASSOCIATES, LTD. Court Reporters / 1250 I Street, N.W., Suite 300 j Washington, D.C. 20005 i (202) 842-0034 l l i
l 399 1 that they can be readily heard. '( ) 2 We have received no written comments or requests 3 for time to make oral statements from members of the public. 4 This is the third day of a three-day meeting. Today, the 5 subcommittee will hear presentations on and discuss SSAR 6 Chapter 17, quality assurance, and the regulatory treatment 7 of non-safety related systems. 8 Copies of the AP600 SSAR and PRA are available at ) 9 the front of the room for reference. We will now proceed 10 with the meeting, and I call upon Mr. Bryan McIntyre of 11 Westinghouse to begin. 12 MR. McINTYRE: John, we have a leftover item that l 13 maybe Alan Levin could help us with. 14 CHAIRMAN BURTON: What's that, John? I ) 15 MR. McINTYRE: I guess we wanted to further ( 16 explore with Alan the water hammer calculation that he 17 performed, leak before break business. l 18 MR. SHACK: I ask the question, Alan, did you just 19 basically hypothesize that or you actually had some 20 scenarios that would lead to that, the question of the 21 estimating the likelihood of the water hammer that you're l l 22 predicting? l 23 MR. LEVIN: This is Alan Levin from the staff. 24 No, I did not try to estimate the likelihood. I set up a 25 postulated situation where you would have a steam bubble () ANN RILEY & ASSOCIATES, LTD. N-Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
400 1 collapse driven by essentially the operating pressure of the \\ [} 2 feedwater system with the sink pressure, if you will, the \\d 3 pressure on the collapse side of the bubble, being 4 equivalent to essentially whatever the cold water 5 atmospheric pressure, whatever it was, and try to derive a 6 velocity using that driving pressure, and then looked at the 7 impact loading from the slug. Very, very much of a back of 8 the envelope type Joukowsky equation calculation to estimate 9 the load, and not trying to account in any systematic way 10 for frictional effects or other mitigating circumstances. 11 The thing was that with even a fairly modest sort 12 of assumptions and in trying to not be too over-conservative 13 in terms of trying to get a really high velocity. The 14 velocity still came out in the 500 foot per second or more ) 15 range, which gives you an impact load of several thousand 16 psi, and this is not a 2200 psi system. It's not designed 17 for that pressure. It's about 900 psi, and it looked like 18 it was, you know, you couldn't rule out the possibility of 19 something like that happening, and we acknowledge when 20 Westinghouse made their presentation and we discussed this 21 further on, we acknowledged that you would have to have a 22 mismanipulation of several valves in the line to allow the 23 potential for this to get there, but it looked like 24 something that could still happen. Trying to put a 25 probability on it, we never really got to a point where I () ANN RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
l \\ 401 1 felt like that was a meaningful thing to try to do. () 2 CHAIRMAN BURTON: Does that answer your question, 3 John? 4 MR. McINTYRE: Yeah. 5 CHAIRMAN BURTON: Okay, thank you. Mr. McIntyre. 6 I'm glad you showed up today. I introduced you yesterday 7 and found out you were with the chairman. 8 MR. McINTYRE: That's correct. 9 CHAIRMAN BURTON: It was sort of embarrassing. 10 MR. McINTYRE: I do my best. 11 CHAIRMAN BURTON: I should have looked over there 12 before I did that. 13 MR. McINTIRE : My priorities do get frequently 14 rearranged. () 15 I'm going to talk about Chapter 17. Chapter 17 16 is, well, there's four subsections. There's really two 17 parts to it. The first three are the standard things that 18 are in the standard review plan. They're basically our 19 quality assurance program. At the request of the staff we 20 moved the reliability assurance program, the RAP, from what 21 had been Section 16.3 to 17.4. So, I'm going to cover the 22 first three sections. Terry Schultz is going to talk about 23 the reliability assurance program, 17.4. 24 When you are reading through the SSAR -- hopefully 25 this won't confuse things too much. We could have tried to ANN RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
402 1 find all the references to 16.3 and fixed ther. to change to [^)) 2 read 17.4, but what we did is we just took 16.3 out and 'w 3 there's a pointer that says read 17.4 because that was the 4 way that we knew that at least it would be pretty much 5 right, and we probably didn't have any untied-up ends 6 somewhere. 7 The first two parts, Section 17.1 and 17.2, and if 8 you look in the SAR, 17.1 and 17.2 and 17.3 are about two 9 pages long in their entirely, so I now have a seven-page 10 presentation on two pages. The staff wrote about a 14-page 11 SAR on two pages. 12 The first two sections are basically things that 13 the combined license applicant will do that are 14 traditionally not -- this is not something Westinghouse has ) 15 really dabbled with very much because we're designing a 16 whole plant in this case, so basically, these are 17 commitments that the combined license applicant will have 18 quality assurance programs in place, and I'll go through and 19 the staff will review those when your combined license 20 application comes in. 21 For the things.that we do, which is really 17.3, 22 we have the standard Westinghouse -- it still says 23 Westinghouse Electric Corporation because that's what the l 24 document says, even though we're not Westinghouse Electric 25 Company, Jay, since you ask about that periodically. '~) ANN RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
403 1 We have a quality assurance program that we work () 2 through that says wo do things to appendix B and we check 3 our calc notes when we go through that part of the process. 4 For the purposes of the AP600 since it was a 5 bigaer scope than Westinghouse has ever done -- usually 6 we've only had to deal with ourselves -- we have a report, a ) 7 project specific quality assurance program that is basically 8 a supplement that expands as it says for all of our 9 subcontractors here is how we're going to deal with them 10 here, how we're going to deal the things that are in the i 11 scope of AP600 that are not in scope of the standard i 12 corporate document. So, basically, we have -- it kind of 13 looks like two quality assurance programs but it's a quality 14 assurance program then with a supplement, and the staff has (A) 15 reviewed that, and I asr,ume that you're going to be talking 16 about that when I sit down. 17 We have -- if you look through how we did the 18 desigu certification, it was Westinghouse and all of our 19 partners. Originally, we started out with Bechtel and M.K. 20 Ferguson and Chicago Bridge & Iron and somebody that I can't 21 remember. 22 Mk. SCHULZ: Avondale? 23 MR. Mc1NTYRE: Avondale, yes, they're the people 24 in Louisiana. Thanks, Terry. We had to get them to make 25 sure, and particularly when you're working with a shipyard, ()h ANN RILEY & ASSOCIATES, LTD. \\- Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
404 1 nuclear quality assurance was kind of a surprise to them and ([ 2 it was a little bit of a change, and what we did is we made l ' 3 sure that they had a quality assurance program. Basically, 4 we went down, we would audit them and then periodically go 5 back through and look and make sure that they were 6 performing according to our specifications. As the program l 7 went on then, we started to suck in all of the other people l 8 .in Spain, the people in Italy, and it got bigger and bigger l 9 and a bigger organization. Basically, that's the process ) I 10 that we used. Jost like we would on any other vendor, go 11 out and make sure that they're qualified and then do 12 periodic updates on their programs. 13 The staff has come through and performed, it's 3 14 three audits -- two in 1997 and one in 1995. There were () 15 some things that they found in 1995, was primarily on the 16 testing program on how we had done -- their finding had to 17 do with the as-builts on the facilities in Italy, that we 18 hadn't done those exactly according to the procedures. We 19 went back and effectively, it says remeasured. That's what 20 we did. We remeasured and confirmed that the drawings that 21 they had done as as-builts were the as-builts. 22 In November of 1997, the staff came in to an 23 inspection and came up with two nonconformances and an 24 unresolved item. The nonconformance, the first one, there 25 were eight observations as part of that, and I'll summarize ANN RILEY & ASSOCIATES, LTD. ~s Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 l (202) 842-0034 l t
405 1 this. Hopefully, and I'm sure I'll be corrected by the (/ \\ 2 people at the table on the other side there, is that we need s-3 to write better calc notes. We tend to write our 4 calculation notes for ourselves, and you assume that the 5 person who reviews the calc note is familiar with the 6 Westinghouse technology, is familiar with AP6. It basically 7 has a large, built-in database, and a lot of things, the 8 staff found that some of this is also a change in 9 technology, that when we did calc notes all on paper, you 10 expect to look through and see little checkmarks and little, i i 11 you know, hen scratching, and now we have computers. All 12 you see at the end on some of the calc notes is a signature, i l 13 the guy that says yeah, verily, this is okay. So, that's a 14 little different, which is really all .iat Appendix B j (~N I (,) 15 requires that you have, is that second signature on the 16 verification. 17 Things also they found were problems noted that 18 gee, this is an error, but it's okay. Well, it's an error 19 but it's okay. Well, why is it okay? What we found is that 20 you get a guy with 25 years of loca experience and he looks 21 at it and he knows it's okay. Well, how did he make that 22 engineering judgment? This is a comment that's been made 23 not only by the NRC but by some of our customers who have 24 come in who are also audited by the NRC and say you guys 25 need to, if you make an engineering judgment, show how and [~ ) ANN RILEY & ASSOCIATES, LTD. Am/ Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034 L________________..______._____________________
406 1 why and the rationale that goes behind that engineering !X 2 Judgment. 3 What we've done in this case is changed our l 4 procedures that tells the engineers if you make an j 5 engineering judgment, for goodness sakes, please-explain 6 what it was you did and how you did that and how you reached 7 that conclusion. 8 There's one other thing in that first 9 non-conformance. We found that we needed to add a tech spec 10 and an I tech because there was something that had been left 11 out. 12 The second observation, the second nonperformance i 13 had to do with errors that they found in the computer codes, 14 specifically with the gothic, computer code gothic -- review (Of 15 for WGOTHIC computer code which is based on the gothic 16 computer code which was developed by another company. We l l'7 had received a list over 100 errors from this company, and l-18 it wasn't obvious from the documentation we could provide at 19 the time that those had been addressed and signed off by the 20 engineer. He had reached a conclusion that yes, there are t 21 no problems with this or that he could deal with it. 22 They went back subsequent to the audit and found I ( 23 out that yeah, the guy had evaluated them. He had not 24 necessarily documented them according to our procedures, but l t 25 he did have the documentation in his desk drawer, and we ANN RILEY & ASSOCIATES, LTD. Court Reporters l-1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
407 i 1 1 looked at that and we have now provided that to the staff, O 2-D and also done some more remedial training. Hey, guys, if 3 you get these things from the outside vendors and there are 4 more and more things that are billed to outside vendors, 5 that you do need to follow our process. This is a case that 6 we had to process, and it wasn't followed as well as it j 7 should have been. 8 The unresolved item had to do with a concern by 9 the staff that geez, we audited a certain number of calc 10 notes, and it seems to us, we found an inordinate number of l 1 11 small errors, and if that's what we can expect, then you 12 guys may have a more significant problem. 13 Westinghouse went away and did a design assurance l l 14 review where we did a broader subset with our own people and 15 one person from an outside source and looked at a larger i i 16 number of calc notes. They also, as part of this, did a 17 statistical evaluation to look at how many calc notes you l 18 need to look at determine if you had a high confidence that 19 you'd found any big errors that were out there. l 20 I guess the good news -- it's kind of a good news, I 21 bad news story, that the good news in this design assurance 22 review is we didn't find any really glaring errors. The bad 23 news is we found sort of the same things that the staff had 24 found, of you guys don't do as good a job documenting 25 engineering judgements. Things really aren't in hindsight h ANN RILEY & ASSOCIATES, LTD.. 'ul Court Reporters 1250 I Street, N.W., Suite 300 ( Washington, D.C. 20005 j (202) 842-0034 L-----------
l l 408 l 1 quite as clear, particularly when both the author and the () 2 reviewer have now left the company for whatever reasons. 3 When you've got a third party then going in scratching his 4 head kind of saying what the heck we did, it's a l 5 clarification issue. 6 We sent in three documenting our corrective 7 actions on this. We got a letter back from the staff on the 1 8 28th that said yes, the design assurance review resolves 9 that particular concern, and we got a letter on May 6 which 10 says that it's responsive, and I'm not quite sure what that 11 means. We hope it means that it closes out the open item in { 12 the FSER concerning quality assurance. It doesn't say that, l 13 but I'm hoping that Bob Pettis is going tc stand up and say 14 here at the end that it does. 'O l(_j 15 Our conclusion is, at least from -- 16 MR. SEALE: Not surprisingly. i 17 MR. McINTYRE: Well, that we do meet the 18 requirements of Appendix B. We have made some changes to j j 19 improve it as far as the documentation goes, and I'm not 20 sure, like I said, what the staff is going to say or how ] 21 they're going to deal with that specific open item, l 22 That's all I had to say on the first three parts 23 of Chapter 17. If there are any comments or questions, if 24 not, I'll let Mr. Schulz. Yeah, Bob? 25 MR. WILSON: Mr. Chairman, this is Jerry Wilson I l l /~'\\ ANN RILEY & ASSOCIATES, LTD. kl Court Reporters s 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
409 1 from the staff. At the time that the staff issued the () 2 advance version of FSER, we had one open item on design QA 3 resulting from the inspection, as Mr. McIntyre said, and 4 we're prepared to provide a status report on that at this 5 time, if it pleases the chairman. 6 CHAIRMAN BURTON: Yeah, go ahead. 7 MR. WILSON: I'll ask Mr. Pettis to give a 8 presentation. L 9 MR. PETTIS: Good morning. 10 CHAIRMAN BURTON: Good morning. 11 MR. PETTIS: My name is Bob Pettis. I'm with the 12 quality assurance and vendor inspection branch of NRR. I'm 13 going to provide you with kind of a brief overview with 14 respect to the items that were identified during the O (j 15 inspection that will arrive at closure. Can everybody hear 16 me okay? And pretty much follow what Mr. McIntyre has just f 1 17 discussed in probably less detai.~.. I 18 MR. CARROLL: I just got a comment that the QA 19 that doesn't follow procedures bothers me. He didn't put 20 the right title page or any of that on this thing. 21 MR. KRESS: No name, no date. 22 MR. PETTIS: I guess I'm in noncompliance with t 23 that. l 24 MR. CARROLL: I guess you are. 25 MR. PETTIS: Just to follow what Brian had just C ANN RILEY & ASSOCIATES, LTD. Court Reporters l 1250 I Street, N.W., Suite 300 l Washington, D.C. 20005 I (202) 842-0034
410 1 talked about, the staff again had conducted the QA [V} 2 inspections. There were two that were performed, one in the 3 April time frame and one in the November. I had i 4 participated in the November inspection, and basically those 5 inspections identified QA related items, findings that were 6 later documented in several inspection reports and through 7 the normal inspection process, information was gathered, put j 8 in the report, and an exchange of information took place 9 between Westinghouse and the staff to close these items, 10 which today are considered closed. Through the process, 11 there was quite a bit of information, documentation that 12 came back from the staff and Westinghouse, including several 13 meetings in between here at headquarters to provide the 14 staff additional information that would arrive at the O (,/ 15 closure of these open items. 16 The April inspection that was performed at 17 Westinghouse, like was mentioned earlier, identified several 18 nonconformances and unresolved items related to structural 19 design activities, basically concerning basemat issues that 20 I believe arose from a review of the Bechtel San Francisco 21 and Imitec documentation. Imitec was one of the contractors 22 involved in the AP600 process.. I think those were discussed 23 probably previous to this meeting in the Chapter 3 review. 24 Westinghouse performed a sample review of design 25 deliverables from the foreign partners, and resolution was [ \\ ANN RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
l 411 1 documented in the inspection report, 9702. So, through the ~ ) 2 normal exchange of doing inspections and the inspection 3 process, we found some items, Westinghouse responded, and 4 then we accepted that response and documented it in the i 5 inspection report. 6 We went back to do a final QA inspection of 7 Westinghouse in November of '97, and that identified the 8 nonconformances that Brian mentioned, formed the basis for 9 this design assurance review. Basically, these were 10 document quality type issues, quality issues relating to 1 11 calculations and calc notes, the maintenance of those. 12 Again, typically, members of the inspection team normally 13 like to follow design calculations and have some interaction i 14 between the author and the reviewer, but with the way ) 15 business is done today, calculations are kind of vanilla in 16 nature, and all you basically see at the end is just yes, it i 17 was accepted and approved, without the thought process 18 leading up to that decision. 19 The failure to evaluate the computer code errors 1 20 appeared to be something that would be more significant i 21 since we left the inspection. We had no information on 22 that, and then Westinghouse came back and provided the 23 documentation to show that basically these items were 24 reviewed. This was by their third party provider of the 25 gothic code. / ANN RILEY & ASSOCIATES, LTD. \\- Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034 i
l l 412 i MR. KRESS: What kind of computer code errors are i D 2 we talking about? (~J 3 MR. PETTIS: Well, we never actually got to see 4 the extent of each individual error to know exactly what the 5 significance of it was, but typically, I think in this case-j 6 it was NAI, which is Numerical Applications, Incorporated, 7 which is the author / developer of the gothic basic code. 8 They provide that gothic basic code to Westinghouse. 9 Westinghouse then customized it for their own use and calls 10 it WGOTHIC. In that transition, since NAI is almost like a 11 public domain version at that point, they come up with what 12 would be classified as errors, which could be -- 13 MR. KRESS: Who found the errors, NAI? 14 MR. PETTIS: Excuse me? (m) 15 MR. KRESS: Who found the errors? 16 MR. PETTIS: NAI, I believe is Numerical l l 17 Applications, Incorporated. Since Westinghouse is the i 18 purchase of the code -- 19 MR. KRESS: They found errors in their own version 20 or the version that Westinghouse -- 1 21 MR. PETTIS: In their own version. I 22 MR. KRESS: Their own version. 23 MR. PETTIS: In their own version of the coce, 24 which forms the basis for the Westinghouse code. So, there i i 25 may be' items in there that may have some significance that i l i ANN RILEY & ASSOCIATES, LTD. Court Reporters s_ 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
413 1 need to'be evaluated by Westinghouse. {} 2 MR. KRESS: Is Westinghouse apprised of these L 3 errors in some way? 4 MR. PETTIS: Yes, they were apprised of these 5 errors in a letter that basically came from NAI to l 6 Westinghouse. There were -- some were in'the order of 100, 7 120 of the so-called errors, and I guess you have to qualify 8 the term error because it doea have a negative connotation, 9 but it just could be -- it could be an input error. It 10 could be something where if you used this particular feature 11 of the program, you might wind up with erroneous results. 12 It's up to the user to then determine if, in fact, they're 13 using that program in that application, maybe using that 14 load sequence or using that portion of the program. l () 15 MR. KRESS: Well, what does failure to evaluate 16 computer code errors mean? Did they not-correct these l 17 things in their WGOTHIC or -- 18 MR. PETTIS: No, basically at the time of the 19 inspection, we had identified the letter from NAI that 20 basically said we have sent to Westinghouse over 120, 130 21 type " errors." Under the provisions of part 21, the NCFR50, 22 part 21, there was a program within Westinghouse to evaluate 23 the impact of those particular errors. So, one would have 24 to sit down and review the applicability of those errors to 25 the WGOTHIC code. None of them may have any resemblance to l O, ANN RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 i (202) 842-0034 l l l l
414 f ( 1 what Westinghouse is using in WGOTHIC. On the other hand, f)T 2 it may. So, the failure to evaluate, at the time, there was 3 no documentation available at Westinghouse to demonstrate to l 4 us that those items had been reviewed and they had been 5 reviewed for applicability, and there is no problem. So, we 6 wrote that up as an open item of finding, and then j 7 subsequent to that, Westinghouse has basically gone back, j 8 found the documentation, discussed it with the individual, 9 and we've basically closed it out as a result. 10 It says Westinghouse requested to evaluate impact 11 of the findings in Chapters 6 and 15. This was the basis of 12 the design assurance review, which is what Westinghouse 13 undertook to basically look across the board generically at 14 the items that we had identified. Like Brian said, there (~h 15 was an inordinate number of " calculation discrepancies, ,j 16 errors that were found within a limited sample of what we i 17 reviewed. So, the obvious question was, if we're reviewing 18 a small sample and finding a high, or what appears to be a l 19 high error rate, then there needs to be some review of that i l 20 across the board throughout the other facets of the AP600 21 project. 22 In February of '98, Westinghouse's assessment 23 concluded that the root cause of the lack of documentation 24 was that the analysis was basically being prepared for l 25 internal review. Like Mr. McIntyre had mentioned, ) ANN RILEY & ASSOCIATES, LTD. \\~/ Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
415 1 internally within Westinghouse, each person doing the review (~, 2 is cognizant and familiar with that area of expertise and '% J 3 maybe doesn't document it all to the extent that a third 4 party like us would like to see it. 5 The NRC staff concluded that Westinghouse did not 6 address the generic implications, and as a result, 7 Westinghouse initiated the design assurance review to assess 8 the sample of calculations. So, they embarked on a program 9 that basically would look at more calculations, more 10 calculations notes to try to identify if there was a generic 11 problem. As a result, like Westinghouse said earlier, they 12 pretty much concluded that they found the same types of 13 things that we found, although none of them had any impact 14 with respect to SSAR calculations. O(,) 15 April 13, Westinghouse came in to brief the staff 16 on the process, which included a discussion of configuration 17 management control and the results of the tech spec self 18 assessment. Preliminary DAR results, which was a slide 19 presentation that basically showed all of what went into 20 their DAR, Their own DAR identified potentially significant 21 technical and documentation quality issues, but concluded 22 that the calculations did not effect what was in the SSAR. 23 The staff went through those potentially 24 significant issues and basically exchanged more 25 documentation between us and Westinghouse, asking for more rO ANN RILEY & ASSOCIATES, LTD. k-Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
1 416 i 1 clarification, more detailed information to convince the 2 staff that these items, in fact, did not have the potential 3 to cause any reanalysis or invalidate any conclusions that 4 were already in the SSAR. 5 On May 6, the NRC staff I; viewed the DAR scope I 6 objectives and results. Staff concluded that all the open I 7 QA issues had been satisfactorily addressed. The wording 8 that Brian was alluding to, the responsiveness, is pretty 9 much standard practice with the way we responde to licensees 10 and vendors in that you have supplied information to us. 11 That information is responsive and basically meets our needs 12 and responds to the concerns that we have. As a result, all 13 of those open items that were in the inspection report and l 14 nonconformances as of May 6 have been closed out and () 15 formally addressed. 16 MR. GRAHAM: This is Bob Graham from the staff. I 17 I'd like to add, the current open item in the FSER will I 18 similarly be closed out in relationship to Chapter 17 issues i 19 on the basis of the acceptable conclusions of the 20 inspection. 21 MR. PETTIS: Any other questions? 22 CHAIRMAN BURTON: Thank you. Terry -- Mr. Schulz? 23 MR. SCHULZ: Thank you. My name is Terry Schulz. 24 I was involved in the AP600 DRAP program, partially because 25 the systems that I work on are key elements in that, and my [] ANN RILEY & ASSOCIATES, LTD. \\/ Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
417 1 long-time involvement in the RTNSS process, and I was also a ( 2 member on the expert panel that supported the DRAP program. 3 The DRAP program for the AP600 is divided up into 4 three phases. These are talked about in the SSAR. The 5 first phase is basically what we have done in the design 6 certification time frame. The other two phases will be done 7 later. In phase one, it included the selection of the risk 8 significant structures and components. So, you'll find in 9 the SSAR and, in fact, in the presentation, a copy of what 10 is in the SSAR, which is the list of risk significant system 11 structures and components. 12 MR. KRESS: You did that with the PRA, of course? 13 MR. SCHULZ: Pardon me? 14 MR. KRESS: You did that with the PRA? /"N,) i 15 MR. SCHULZ: Well, the selection process included l 16 numerical PRA importance measures, risk achievement worth, l l 17 reduction worth, level 2 insights. It also included an 18 expert panel review, which was, you know, it's kind of a 19 check on this. There's a few deterministic things. The I l j 20 regulations require it, things like that. For the most 21 part, things were captured by these two things, and a lot of 22 the things were captured by the PRA, both from a 23 quantitative importance measure, and in some cases, insights 24 from the PRA. 25 MR. KRESS: What were your risk metrics, CDF? ANN RILEY & ASSOCIATES, LTD. k-- Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034 )
418 1 MR. SCHULZ: Are you talking about the core 2 damage? 3 MR. KRESS: Things you found -- the important 4 solid, the risk metrics. l l 5 MR. SEALE: The risk achievement worths, Terry, 6 and stuff like that. 7 MR. SCHULZ: What the criteria was? 8 MR. KRESS: Not the criteria, no. I want to know 9 what the actual metrics were. Was it CDF that you were 10 looking -- was that your risk? 11 MR. SCHULZ: We looked at both CDF at power and at 12 shutdown -- 13 MR. KRESS: This will be my next question. Does 14 it include shutdown? () 15 MR. SCHULZ: Yeah, and it was the whole PRA 16 quantifications, okay? So, it was at power, at shutdown, 17 core damage frequency, release frequency. 18 MR. KRESS: Condition containment failure? 19 MR. SCHULZ: No. 20 MR. KRESS: That wasn't in there? 21 MR. SCHULZ: No. That was the one element, We 22 did consider the seismic evaluation that was part of but not 23 NL8. 24 MR. KRESS: How do you do a risk worth - with the 25 shutdown PRA? Is that multiple PRA's for different shutdown O ANN RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
419 1 configurations? O(j 2 MR. SCHULZ: 'AP600 has, I think, a unique 3 situation from a shutdown perspective. Because of the fact 4 that the safety systems, the safety-related systems are 5 standby systems, we have a much simpler situation. 6 MR. KRESS: You rarely have any of those out of -- 7 MR, SCHULZ: Well, not only that, but they are not 8 used for shutdown operation, which is a great complication 9 10 MR. KRESS: No, PRA, though, counts all your 11 active systems. 12 MR. SCHULZ: It does count them, but that's not 13 the point I'm trying to make. The point I'm trying to make 14 is that if you have a key safety system like an RHR system ,c, ( 15 that is a low-hit SI system and a shutdown cooling system, 16 and during shutdown modes you have to use it, but also you 17 have to maintain it during shutdown modes, and you're also 18 trying to maintain diesels in shutdown modes, you get into 19 extreme complication of interactions between normal 20 operation for maintenance and then so the permutations, 21 combinations of that get extremely hard to model. 2? MR. KRESS: Yeah, that's what I was concerned 23 about, actually. 24 MR. SEALE: That's the problem. 25 MR. SCHULZ: That's the problem. We don't have i l (~/') ANN RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
420 1 that problem because we don't use any of our passive safety 2 systems for normal operation. So, this interaction between 3 when do you maintain it, does its operational aspects effect 4 the PRA. 5 MR. KRESS: What I think I'm gathering from that 6 -is.your PRA is not a best estimate PRA but a conservative 7 one, where you leave out some of the things that -- you're 8 going to have this problem with your active systems. 9 Whenever you shut down to do anything, you're going to have-10 multiple _ configuration. 11 MR. SCHULZ: Yeah. 12 MR. KRESS: And I don't care whether your active 13 systems or passive systems are there are not. So, you're 14 going to have that: problem. b,r 15 MR. SCHULZ: Going to have that problem to a much y_ 16 less degree because our active systems are much more 17 .important. They are the only thing you have in current 18 plants, and in some modes, you don't have a lot of back-up 19 mid-lube operation and whatever, so it's very critical that 20 those active systems be available and -- 21 MR. KRESS: What you're saying is it a focus PRA, 22 no matter what that configuration of those active systems 23 are, they won't show up on your importance measure very 24 much. l 25 MR. SCHULZ: Very much, they're very low \\; ANN RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
421 l 11 importance. 2' MR. KRESS: That's probably true. 3 MR. SCHULZ: If you look through the results of 4 the -- you know, I don't know how much we get into this. I P 5 got the whole thing here. It's ten ~pages. We may talk 6 about it all. We may talk about one page,'but you see 7 there, some of the active systems get captured. Most of t 8 them get captured by expert panel because they didn't get 9-above the measures, but a few of them did, but they're on 10 the low end of the importance. 11 MR. KRESS: I understand. 12-MR. SEALE: It strikes me that.as a bounding 13 situation, if and when we.ever start looking into the 14 details of what might be required for completeness in a O( jj 15 shutdcwn analysis, that we might want to look at the AP600 16 shutdown analysis as sort of an extreme -- as an extreme. 17 MR. KRESS: A starting point, yeah. 18 MR. SEALE: I wouldn't say a.way to start, but as 19 a bound. 20 MR. KRESS: It's certainly not typical. 21 MR. SEALE: Certainly not typical, yes. 22 MR. SCHULZ: So, that's what we have completed so 23 far. Phase 2 will go on to develop more specific plant 24 maintenance and monitoring activities, and this really has 25 to, in some cases, wait until equipment is purchased so that 4[ \\ ANN RILEY & ASSOCIATES, LTD. \\l Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
422 1 you know what the -- who the vendor is and what the specific () 2 requirements are. Then there's a third phase where the COL 3 applicant will'actually look for site specific things.
- Now, 4
we don't anticipate an AP600 to find any, and-that's again 5 partially related, mainly related'to the unique aspects of 6 'AP600 where we don't have a service water system that's a 7-key safety system, but for completeness, we still have 8 included this in the DRAF program. It's a necessary l 9 element. l 10 The final thing, and this is a bit of an open item 11 yet, is that we have an ITAAC on the DRAP program. The 12 ITAAC is, our approach to that has been a little bit 13 different than the evolutionary plants. One of the key 14 reasons for that was that the list of risk important SSC's () 15 in the SSAR, in our opinion, is the list. It's not an 16 example as it was in evolutionary plants. So, the 17 evolutiont_y' plants, when they got the ITAAC, basically had 18 to commit to a program, a process, because they didn't 19 really have completed anything. They had done some ' 20 preliminary work or example work. 21 So, in our ITAAC, instead of having the first 22 three steps or so of the evolutionary plants was to go 23 through the process to select the SSC's or to reconfirm them 24 or whatever. We put the list of SSC's out of the SSAR into 25 the ITAAC as a table, and then what we did in terms of O ANN RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034 l
423 1 inspections was to assess the reliability of those -- of the [~} 2 as-built components -- this would be, of course, done in the V 3 future by the COL -- verify that the estimated reliability 4 of these components is at least as great as the assumed 5 reliabilities. { 6 MR. CARROLL: How do you go about doing that for, 7 say, a pump? I finally decide I'm going to buy a pump from 8 Pacific Pump that's sitting there. 9 MR. SCHULZ: It will still be done before there's i j 10 any real data on that plant. What we're expecting to happen ) 11 is that you will know who you bought the pump from. 12 MR. CARROLL: Yeah. 13 MR. SCHULZ: That you will assess experience and 14 data from that vendor. 15 MR. CARROLL: Okay. 16 MR. SCHULZ: And again, it's extrapolated from 17 similar applications for similar pumps, but at least that 18 vendor -- so it's more specific than we can be now. Now 19 we're using, you know, generic RHR pump data cr feedwater 20 pump data or whatever, and it's multiple vendors, multiple 21 plants, so it's a little more uncertain. We're getting more 22 certain when we get down to here. 23 We can also get down to dealing with maintenance 1 24 considerations relative to reliability, frequency of 25 rechanging of seals or oi.' or related to the vendor, where '} ANN RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
424 1 we can't really do that now. So, we're taking a step () 2 forward, and it's about all we think yr1 can do relative to 3-prior to starting the plant up, and it is getting more 4 specific and reducing uncertainty from where we are now. 5 MR. CARROLL: At that point, you have established 6 a minimum reliability numerically? 7 MR. SCHULZ: We have now in our PRA reliabilities. 8 MR. CARROLL: Okay. 9 MR. SCHULZ: I wouldn't necessarily call them 10 minimum. 'They're estimated reliabilities. 11 MR. CARROLL: Okay. 12 MR. SCHULZ: So when the DRAP says or the ITAAC 13 says verify that the estimated reliability of the as-built 14 component is greater than the assumed reliability, at that () 15 point in time may be the PRA number or it may be something 16 derived from that. Right now I would assume it would be the 17 PRA number that you're trying to assess that the as-built 18 component is at least as good as what you assumed now. 19 MR. KRESS: That's a pretty hard thing to do, 20 isn't it? l 21, MR. SCHULZ: It's easier to do it in the future 22 than it is now, but -- l l 23 MR. CARROLL: It's easier for the COL applicant to 24 do it, too. 25 MR. SCHULZ: Well, it's more possible. I mean, O ANN RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 l (202) 842-0034
425 1 the key thing is we're not saying we're verifying the s ( \\ 2 reliability. You can't do that. We're estimating the u) 3 reliability based on more specific information than we have 4 now. We think that's about all we can do. Now obviously, 5 once the plant starts up and starts running, they start C accumulating their own data and then they eventually 7 transition presumably into use of their own data as opposed 8 to more generic historical data, and it gets better and 9 better as they go along. Hopefully, we'll have several 10 identical AP600's running, and that's another source of 11 data. 12 MR. KRESS: Let's hope so. 13 MR. SCHULZ: Yes. So, we're still working on 14 this. In fact. we've been exchanging some information the ( 15 last couple days trying to close that out. 16 MR. CARROLL: It reminds me, we talked the other 17 day about first three plants requiring certain testing and l 18 the first one requiring certain testing. How do you count? 19 Suppose we sell a U.S. plant and then two foreign plants? 20 MR. KRESS: Well, those don't count. 21 MR. SEALE: They count for Westinghouse but not 22 for the NRC. 23 MR. KRESS: For U.S. certification. 24 MR. LEVIN: This is Alan Levin. I'd like to 25 address that because I was involved in the ITP review, and b) ANN RILEY & ASSOCIATES, LTD. \\d Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
426 1. Jlan Peralta is not here. Oh, he is? Oh, you're back () 2 there. You want to get up and talk to them? 3 MR. PERALTA: No, you can handle it. 4 MR. LEVIN: We've talked-about it a little bit. 5 Foreign plants, you would have -- Westinghouse would have to 6 be able to, in our view I think, to certify, to document-7- that the foreign plant met U.S. QA requirements all the way 8 down the line in terms of the entire program,. design, 9 construction and so forth, and in performance of an ITP and 10 all of that. If they could demonstrate adequately that the 11 plant that was built was the certified design, was according 12 to the rule and no deviations like that, then I don't think 13 that there would be a problem in taking that as part of the 14 database, but the burden would be on them to be able to () 15 demonstrate that. In fact, the plant was built effectively 16 equivalent to having been built in the United States. 17 MR. CARROLL: Okay. 18 MR SCHULZ: In think what Alan says is -- we 19 would completely agree with in respect to start-up testing. 20 MR. CARROLL: Yeah. 21 MR. SCHULZ: Okay, in thermohydraulics. 22 MR. CARROLL: Right. 23 MR. SCHULZ: Now, if you're asking a question 24 about reliability data -- 25 MR. CARROLL : No, I was asking about -- ANN RILEY & ASSOCIATES, LTD. \\ Court Reporters 1250 I. Street, N.W., Suite 300 Washington, D C. 20005 (202) 842-0034
I 427 1 MR. SCHULZ: Okay, it's a different ( 2 MR. CARROLL: -- about start-up. 3 MR. SCHULZ: The rest of my handout is repetitious 4 of all the 10 pages of the DRAP data out of the SSAR. I was 5 not int'aiing to go through all of it. I.did want to point 6 out a few examples of things from it, and then it's up to 7 you how much we want to talk about it. 8 The general structure of this table is you'll see 9
- a. listing for a system, and a system is listed only if there 10 is some component under it that has been found through the l
g 11 either quantitative PRA measures or the expert panel or i i 12 deterministic criteria to be risk important. The system 13 would be listed, and the components under it are listed, and 14 there's then in the rationale, that basically says why it's 15 captured. 16 So, if you see something that's EP, that's expert panel 17 So, under the -- 18 MR. KRESS: That's risk import lyt if it is needed 19 to meet in the minus four CDF or -- 20 MR. SCHULZ: This did not use the focused PRA. 21 This used the baseline PRA. The measure of risk importance i 22 what not whether or not you needed it to meet the safety l 23 goals. It was the risk achievement worth type number. So, 24 if you made these valves perfectly reliable, how much did I
- 25 the core melt frequency improve?
O ANN RILEY & ASSOCIATES, LTD. \\w / Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
t i 428 1 MR. KRESS: Okay. [ 2 MR. SCHULZ: Or, there's a couple RRW's here, so \\_- 3 if you made the thing failed, how much did it increase the 4 l 5 MR. KRESS: So you had some delta CDF's for your 6 target? I 7 MR. SCHULZ: Well, realize what that means, is 8 when you're talking core damage frequency on AP600, you're l 9 extremely low numbers. 10 MR. KRESS: Ex&ctly. 11 MR. SCHULZ: And if you get like a one percent 12 increase in that, what does that mean? 13 MR. KRESS: Will you use percentages? 14 MR. SCHULZ: Percentages. ( (,/ 15 MR. KRESS: Ah-hah. 16 MR. SCHULZ: This is what the process is. 17 MR. KRESS: I see, so this is the same as the 18 maintenance rule process? 19 MR. SCHULZ: Yes, basically, yes. So, even though 20 on the RTNSS process is used a different measure of risk 21 importance that was more black and white, and it was related 22 to safety goal and focused PRA. This is the maintenance 23 rule type process. 24 MR. McINTYRE: Now, Terry, before you go on, I 25 wanted to build on something -- this is Brian McIntyre -- (' ANN RILEY & ASSOCIATES, LTD. 's Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
429 1 that. Tom had brought-up. We tried to get credit and have [) 2 different risk achievement worth numbers for the AP600 \\_J. 3 .because it was so low and we thought, because if you look at 4 it on a percentage basis, you're hitting on something that's 5' near and dear to us. 6 MR. KRESS: Yeah, you're criticizing a really good 7 design. 8 MR. McINTYRE: Yeah, exactly, and we tried to get l 9 credit for some better numbers, but the staff said you know, j l 10 this is what'we did on the evolutionary plants and this is ~ 11 what you're going to do too. We went back and forth several i 12 times, and the first list was really kind of short. 13 MR. SCHULZ: Well, it actually didn't make a lot 14 of difference in how many components we capture. It did () 15 make some difference on why we captured them. 16 MR. McINTYRE: Right. -17 MR. SCHULZ: Like the chemical and volume control 18 system, we had captured initially, but only on expert panel, 19 and now we pick up a few on RAW's, but these are down in the 1 20 one percent, two percent range, and we had proposed more 21 like a ten percent range, CEU's to 3-5 percent range. We l 22 .actually are going back to the maintenance rule kind of '23 number. 24 There were a couple of things we did capture that i 25 we otherwish wouldn't have captured, but not very many. I ANN RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street, N.W., Suite 300 I Washington, D.C. 20005 (202) 842-0034 l I r b__________.._____._____.__.__..__
430 1 MR. KRESS: I guess there is a certain rationale [') 2 for using percentage because a lot of the judgments and V 3 decision and regulatory controls and so forth are based on 4 the actual numbers of your risk level, and you know, it may 5 be -- percentages then become an important measure of how 6 far you're deviating away from that absolute value. I can 7 see a rationale for using percentages. 8 M1-McINTYRE: I'm sure it also gets into how good 9 is your PRA. 10 MR. KRESS: Yeah. 11 MR. McINTYRE: And you may not really trust the 12 ten to the minus 7, but you would probably trust the five 13 percent change. 14 MR. KRESS: Okay. r(,) 15 MR. SCHULZ: So, you will see things like the 16 point of cooling water is expert panel. The containment is 17 not really important from a level one point of view. 18 MR. KRESS: Yeah, that's why I was sondering how 19 it even got on there. 20 MR. SCHULZ: Well, it's expert panel. Also level 21 two. This is your -- L2 is level two, so from a containment 22 of activity, it obviously is quantified very important. 23 MR. KRESS: I'm surprised ~that the cooling water l 24 system shows up on level two. 1 25 MR. SCHULZ: This is the active component cooling l O ANN RILEY & ASSOCIATES, LTD. Court Reporters ss 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034 l l
431 1 water system. The passive does. It's in a later stage. ,-~ ( 2 MR. KRESS: Oh, it's not part of the containment 3 system? 4 MR. SCHULZ: No, we -- this is just the structure. 5 MR. KRESS: I see, okay. 6 MR. SCHULZ: And we also throw in the igniters 7 under the containment system. The -- and these are all 8 listed by the alphabetical, by the system official title, so 9 passive containment system is PCS, so it's about page four 10 or five. 11 MR. KRESS: Sprays didn't show up on there? 12 MR. SCHULZ: Sprays do not show up on here. 13 MR. KRESS: I just thought I'd throw that in just 14 for pride. () 15 MR. SEALE: This is your so-called non-safety 16 systems? 17 MR. SCHULZ: Right, the -- 28 MR. SEALE: There's quite a bit of them, l 19 MR. SCHULZ: Quite a bit of them. 20 MR. SEALE: I guess, in fact, if it's considered a 21 nca-safety system, it shows up on this list. 22 MR. SCHULZ: Not because it's non-safety. We 23 would basically put our blinders. The knowledge of safety, 24 non-safety, we take that off. We look at what was modeled 25 in the PRA and then -- I ANN RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
432 1 MR. SEALE: So this list is not inclusive of the [} 2 non-safety systems? G 3 MR. SCHULZ: It includes non-safety systems -- 4 MR. SEALE: But not all of them. 5 MR. SCHULZ: Not all of them. Includes the ones ) i 6 that were considered risk important by the deterministic or 7 PRA qualitative -- 8 MR. SEALE: Or expert panel. 9 MR. SCHULZ: -- or expert panel, right. l 1 10 MR. SEALE: Got you. l 11 MR. CARROLL: And what's CCF? l 1 12 MR. SCHULZ: Common cause failure. When you get 13 into highly redundant systems -- 14 MR. CARROLL: Oh, okay. O) q 15 MR. SCHULL: -- common cause failure can, to some 16 extent, mask importance of something because it tends to l 1 17 make a four-way redundant system rather unreliable, 18 relatively unreliable compared to what it might be without l 19 common cause failure. So, one of the thinking processes 20 that we put into this was that when you get into highly i l 21 redundant systems, maybe we should give a little more 22 consideration to what the reliability might be if common l 23 cause failure wasn't there. You do see it on make-up pumps, 24 and there's only two of those, and that was a very minor -- ) 25 I mean, this whole thing just barely makes the quantitative l [~ ANN RILEY & ASSOCIATES, LTD. l \\- Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 ( (202) 842-0034 u--------.---------_----------
I 433 1 numbers, but that common cause failure is much more l f~) 2 important, especially in the INC systems where you -- or in
- a l
3 an ADS -- 4 MR. McINTYRE: ADS, yeah. 5 THE COURT: -- where you have multiple redundant 6 systems. 7 MR. SEALE: They sort of infest these low pressure 8 water systems, too, don't they? l 9 MR. SCHULZ: The, like IRWST? I 10 MR. SEALE: Yeah. 11 MR. SCHULZ: Yeah, and again, you're talking j 12 four-way redundant kind of pathways, and that's kind of why 13 you see that. I don't know if there's anymore specific 14 things that I would vant to point out here. If you have any s l 15 questions. 16 MR. CARROLL: I guess when I first looked at your 17 PRA, the very low numbers you have, I guess my first 18 reaction was how can they get things that low, given common 19 cause failure. I think.I'm at least semi-convinced that you 20 can. Why don't you give me your take on this. 21 MR. SCHULZ: Let me just show you -- I talked 22 yesterday a little bit about defense in depth and some of 23 the early assessments we did on trying to put on paper, not 24 necessarily a PRA basis but this event matrix. This is, the 25 right-hand column of this is out of a WCAP that we've sent ) ANN RILEY & ASSOCIATES, LTD. s/ Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 2000b (202) 842-0034 l
434 t 1 the staff on this event matrix. The format of this is to () 2 look at events, and I think I said yesterday we looked a 11 l 3 or so at power events, and six or so shutdown events, 4 looking at different modes of initiation of the problem. 5 For each event we looked at, we have an event, and then we 6 look at sort of levels of defense. This gives you a pretty l 7 good picture of why we think it's real that we are much 8 better than existing plants. The loop is loss of outside 9 power. 10 MR. CARROLL: Okay. 11 MR. SCHULZ: The current plant, your primary 12 success, and this -- the black boxes are the safety case 13 that's in the SSAR, which doesn't necessarily have a lot of 14 meaning here because this was more of a PRA real life C) ( 15 assessment, but it's interesting information. 16 So, the automatic start of the auxiliary feedwater 17 system with power from diesels and stuff like that, is the 18 primary success path. If that works, everything's okay, s 19 If that doesn't work, there's typically a feed and bleed 20 backup to that which uses high ADS pumps which would start 21 automatically in the situation. Containment cooling usually 1 22 by spray, sometimes fan coolers. There would be.a manual 23 element to that which would be opening up the vent. That is 24 not automated in current plants. If that works properly, l 25 the core is cooled, although you do put energy into the I ANN RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0024
435 1 containment. If.that doesn't work usually you're into core /I 2 damage scenarios. 'V 3 Now, on AP600, we have'a parallel to the auxiliary 4 feedwater, which is startup feedwater, and that's not as 5' reliable. It's non-safety. It's not our safety case, but l l 6 it does add to the picture, okay, and when'you start going 7 down this, one of the things that you see is that we have 8 some highly diverse, very different ways of doing things, 9 and this is really the crux of why AP600 is very reliable, l 10 we think, because we have -- it's not because we have I 11 passive systems and we have one way of doing things and you 12 'just can't fail. That's not our story. It's.not why we 13- .think it's so good. It's that we have a startup feedwater. 14 We have a passive RHR, and we have several ways of doing () 15 feed and bleed with passive systems. 16 Then it's also important to look at common mode 17. ways of these things failing, like when you start getting ] 18 into here. These things are actuated by the protection 19 system. Well, can that be a common mode failure? Well, yes 20 it can. It is very reliable, but we've also put in diverse 21 ' actuation I&C which provides an independent way of doing 22 this actuation. 23 What about power to components? Well, this non-1E l 24 AC power, non-1E DC power. This is fail safe. No power i I 25 required at all. The passive RHR, valves fail open, the I O ANN RILEY & ASSOCIATES, LTD. I Court Reporters 1250 I Street, N.W., Suite 300 i l Washington, D.C. 20005 (202) 842-0034 L______________________.__
436 1 passive containment valves fail open, containment valves () 2 fail closed. So, if the thing goes black, really black, 3 this works. These require some elements of 1E-DC powerfro 4 1 open ADS valves or IWST injection. In some cases, you even 5 see mixed modes of -- with RNS providing some injection, 6 which minimizes the number of ADS valves needed. In other 7 cases, we need the full depressurization. 8 CHAIRMAN BURTON: A lot of defense in depth. 9 MR. CARROLL: The ADS is common to a lot of that. 10 MR. SCHULZ: It's common to these three elements 11 here, yes. 12 MR. CARROLL: And I guess I always think about the 13 L1011 engine oil drain plugs. Can a maintenance guy where 14 an incorrect spare part defeat ADS, and what happens to that ) 15 chain at that point? 16 MR. SCHULZ: Well -- 17 MR. CARROLL: The fourth stage, for example? 18 MR. SCHULZ: A couple of things. This element 19 doesn't require the fourth stage because of the RNS. This 20 only requires the first three stages. Now, those are motor 21 operated valves. They're completely different technology 22 than the Squib valves. 23 MR. CARROLL: Okay. 24 MR. SCEULZ: So, you know, you see ADS here. It 25 says partial, and what that really means is we only need i O-ANN RILEY & ASSOCIATES, LTD. -Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034 l l
437 1 parts of the first three stages. Down here, yes, we do need p; 2 the fourth stage, but again, you're talking now a couple of 3 the blocks out of -- you have three other ways of doing you 4 don't need. 5 MR. CARROLL: I'm going to do something bad to the 6 MOV's for the first three stages. What does that do? 7 CHAIRMAN BURTON: That leaves you up to the -- 8 MR. SCHULZ: The fourth stage is important. I'm 9 not trying to say it's not important. 10 CHAIRMAN BURTON: Then you rely on the Squibs in 11 the fourth stage. 12 MR. SCHULZ: Right, but you've also got start-up 13 feedwater pumps up here. You've got passive RHR, which is 14 fail-safe here. You know -- (g,) 15 CHAIRMAN BURTON: A lot of things going wrong 16 before you get there. l 17 MR. SCHULZ: You have to feel a lot of things, 18 yeah. Now, when you look at a loca situation, then this is 19 a little different. This whole thing collapses a bit, but 20 you're talking about an event that's less probable, too. 21 This is a more probable event, or if you put loss of main 22 feedwater, you pretty much have the same defense, but it's 23 an event that happens once a year, twice a year. You're 24 talking about a loca that's more like one in a thousand, one 25 'in 10,000 years. You can get away with having less levels l l I ( ANN RILEY & ASSOCIATES, LTD. l Court Reporters s-1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034 lu_
t I L 438 l 1 of defense. You don't need as many. () -2 RMR. KRESS: The opening of the fourth' stage is on =3 a timer after the third stage opened? 4 MR. SCHULZ: No, the fourth stage requires a 5 fseparate level signal out of the core make-up tanks. The l 6-core make-up tanks basically have two ADS set points. One-7. is relatively high,.two-thirds full, and that gets you stage 8 one. Then two and three come off timers from stage one, but 9 we don't get stage four actuation until we get a'20 percent l 10 full kind.of CMT. So, the CMT has to drain down, or you can p 11 do it manually. So, that's basically a long answer to your 12 question. l 13 MR. KRESS: Does that mean that stage one fails to I 14 open, then stages two and three also will fail? () 15 MR. SCHULZ: That is not correct, no. There is no 16 feedback signal-from valve position intc the circuit. 17 MR. KRESS: I see. It's just that the -- 18 MR. SCHULZ: The instrumentation system gets the i i 19 level signal and then it starts timers going. l 20 MR. KRESS: It starts the timer. 21 MR. SCHULZ: So it will go one, two, three, and if 22- 'those valves don't open, it still waits for CMT low, low i 23 level, and it will get four, as long as the pressure is 24 down. There is a pressure interlock on stage four, but as 25 long as the event.with either the loca or passive RHR ANN RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034 - _ _ _ _ = _ _ _ _ _ _. _ _ - _ _ _ _ - _ - - _ - _ - _ _ _ _ _ _ _ _ _ _ _ _ _ - _ _
L 439 l 1 operation gets you down below 1200 pounds or something, then () 2 fourth stage will go off all by i*=e?f. 3 Any other questions? 4 MR. FONTANA: Why is there a pressure interlock on 5 stage four? 6 MR. SCHULZ: It's trying to balance the -- 7 obviously we want it to work when it's supposed to work, but 8 it's very important for it not to work when it's not 9' supposed to work. So, you know, it can create an accident. 10 So, it was our balance of trying to basically optimize the 11 risk of the plant in consideration of initiating events 12 .versus mitigation. 13 We have ways of opening it manually if the 14 pressure is high. We can still do that, but it won't work () 15 automatically if the pressure is high. 16 CHAIRMAN BURTON: Thank you. 17 MR. SCHULZ: You're welcome. 18 CHAIRMAN BURTON: Staff, any other comments on 19 this chapter? -20 MR. WILSON: No. It's Jerry Wilson, NRR. Staff 21 found the design reliability assurance program acceptable, 22 and we're available for committee questions. 23 MR. KRESS: What was your thinking on asking for a 24 percent change in the, say, the CDF as an acceptance 25' criteria on the risk worth measure? O' ANN RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
440 1 MR. CORREIA: Mainly to be consistent with the () 2 evolutionary designs and the maintenance rule process. We 3 found that it was a reasonable process for operating plants 4 to use in maintenance rule space. We adopted it for the 5 evolutionary plants. It seemed to be logical, if you will. l 6 MR. KRESS: Doesn't it strike you as being a bit 7 of a ratcheting? 8 MR. CORREIA: Well, since industry came up with 9 this process and we endorsed it, we didn't think -- I guess 10 I wouldn't consider that. 11 MR. KRESS: It did come straight from industry. 12 MR. CORREIA: Yeah, it was their idea. We adopted 13 it. 14 CHAIRMAN BURTON: It sounds like the industry C 15 ratcheted themselves on this one, Tom. 16 MR. CORREIA: Oh, my name is Rich Correia of the 17 staff. 18 CHAIRMAN BURTON: No other questions. We'll break 19 until ten to ten and pick it ? with Chapter 22. 20 [ Recess.] 21 CHAIRMAN BURTON: We're back in session. SSAR 22 Chapter 22, Terry Schulz. l 23 MR. KRESS: Before we start 24 CHAIRMAN BURTON: Before you start, yeah. 25 MR. KRESS: I looked at this RTNSS stuff, and it (' ANN RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
441 1 struck me that that's probably the best example I've seen of () 2 a risk informed performance based regulation. If you guys 3 want to know what I think a risk informed performance based 4 regulation is, look at this thing. 5 CHAIRMAN BURTON: Read Chapter 22. 6 MR. KRESS: Yeah, that's what I think one is. 7 CHAIRMAN BURTON: You'd better be looking that way 8 when you say that. 9 MR. CARROLL: I didn't think you felt that there 10 was such a thing as a performance based regulation. 11 MR. KRESS: Oh, no, I never said that. I said I 12 didn't like them. t 13 CHAIRMAN BURTON: I thirm he likes this one. 14 MR. KRESS: If you're going to have performance (f 15 based regulation, this one is the way to do it. 16 CHAIRMAN BURTON: Well, you might as well just sit 17 down now, Terry. It's all over. 18 MR. SCHULZ: I'll only get into trouble from this 19 point. Is that okay? Can I sit down? 20 MR. LEVIN: Don't screw around with success, 21 Terry. 22 CHAIRMAN BURTON: Don't open your parachute. 23 MR. SCHULZ: Okay, regulatory treatment of 24 non-safety systems. This whole process got started very 25 early on AP600 with initial contacts with the staff, both in O ANN RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
442 1 the URD requirements and in pre-SSAR submittal discussions l } 2 with Westinghouse. There was a lot of early discussion 3 about get we like the passive systems, but why don't you 4 keep the active systems there. You know, wouldn't that be 5 better. We said no, AP600 is only going to be economically 6 viable if we don't have to duplicate and add layers of 7 safety equipment in the plant. The whole concept is that 8 passive systems are effective. They are capable. They're 9 reliable to do the safety functions. What used to be safety 10 related, such as diesels and start-up feedwater, they no 11 longer have those roles, but there was this remaining 12 question of how important are they. Do they need tech 13 specs? Do they need seismic requirements, fire separation, 14 all those kind of questions. () 15 So, there was a lot of discussion back in the, 16 actually late '80's and early '90's on, trying to define a 17 process that we would use to assess the importance. There's 18 actually several SECY's, but 94084 was a final version of 19 that. It included some other items, but item A talks about 20 RTNSS approach. We have implemented a process for AP600 21 which is in WCAP reference up there, that takes that SECY 22 requirement process and applies it to AP600. 23 What this process is is to basically look at all 24 of the non-safety systems in the plant and to assess their 25 importance and for those systems that are found to have some iO ANN RILEY & ASSOCIATES, LTD. \\s / Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
443 1 importance,.to identify basically the regulatory treatment () 2 that is appropriate for that importance. 'So, there's kind 3 of.three key steps to it. One is a sort of screening 4 process that has both PRA.and deterministic elements to it,. 5~ which I'll talk about in the next page. 6 Then, the second part is for those non-safety 7 features that are found to have -- to be captured by that 8 criteria, to identify what the mission is. That's important 9 because ultimately, the regulatory treatment in our minds-10 and in the agreed process, should relate to what the' system 11 is supposed to do. This helps us all focus on is it some 12 seismic capability that's important? Is it some hazard 13-protection capability, or is it simply a random failure 14 availability of a pump that's important. This goes back to () lL5 why was it captured, and then to relate the specific mission 16 to that and then have the regulatory oversight focus on 17 that. 18 MR. KRESS: This is why I-said this is an ideal 19 example of risk informed, performance based because those l 20 first.two sub-bullets under the second bullet, are you risk ~ t 21 informed part. You got risk acceptance criteria. You do a 22 PRA and you've combined that with deterministic and expert 23 panel to determine what is risk important, and then you 24' identify missions that you deal with in a performance space 25 in terms of whether you accomplish those missions or not. O ANN RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034 L o
444 1 This is what is meant by performance based, risk informed () 2 regulations. Those missions and those processes you go 3 through to assure that you meet those missions are not 4 necessarily relatable to achieving the risk value. They're 5 performance in nature. So, this is what you mean by risk 6 informed, performance based. 7 MR. SCHULZ: Okay. Let's talk a little bit more 8 about what the criteria that was used to determine or assess 9 the non-safety systems again. One key element in the 10 probablistic area was uhat we've called the focus PRA. This 11 is something new and different for AP600 where we took the 12 baseline PRA with the same initiating events and same 13 initiating event frequencies and then stripped out the 14 mitigating effects of the non-safety systems. So, we would ( ) 15 have an event like a small loca, and any non-safety system 16 used, like in our case, the normal RHR we would have modeled 17 in the baseline PRA as being capable of the one branch of 18 success in the tree. Then we would say that is assumed to 19 be failed, period. 20 What we were trying to do there is to meet the NRC 21 safety goals with only the safety systems in the PRA. That 22 was the success criteria. Now, one of the side effects of 23 this, and this is a challenge for risk-based type licensing, 24 is that the baseline PRA became very important. Every 25 equipment reliability, every success criteria definition and l (' ) ANN RILEY & ASSOCIATES, LTD. \\~- Court Reporters l 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
445 1 the TNH work that supported the success criteria. 2 The.'PRA involves a lot of information. It's 3 probably not as mature in a sense as deterministic loca 4 analysis cn single failure criteria assessments are'. So, 5 there's a lot of opportunity for debate about what's right,. 6 and we had a lot of debate in this area. It affected -- -7 I'll show you.in the next slide the way we finally resolved 8 that. 9 A second element that's really in the probablistic 10 area is an assessment of initiating event frequency. As I 11 mentioned when we'did the focus PRA, we maintained from a 12 quantification point of view the baseline initiating event 13 frequencies. However, we all realized that there are 14 non-safety systems that play a role in those initiating 15-event frequencies. However, you can't simply turn those off 16 like you can in the mitigating systems because it becomes { 17 nonsensicle. You have what s the chance of loss of main' 18 feedwater if you have no main feedwater pumps? 19 So, we.never were able to quantify this in a PRA 20 calculation,-the importance of non-safety systems from an 21 initiating event frequency point of view. Instead, we did 22' 'an. evaluation that asked three questions, which are actually 23. shown a, couple of pages back. 1 24 Three questions that end up having some 25' quantification elements to them, but the first question is -I ANN RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034 i
446 1 -- and we do this for every initiating event, so does the IV) 2 initiating event frequency depend at all on non-safety 3 systems? So, if you go into like locus, does the initiating 4 event frequency of a pipe break depend on non-safety 5 systems? Now, on AP600, every loca is the break of a 6 safety-related pipe or, if there's a system like the CDS 7 that eventually gets to a non-safety pipe, we have redundant 8 safety-related valves to isolate the non-safety related 9 equipment. l 10 So, the loca frequency as calculated has no 11 elements there that are non-safety related. So, we wouldn't 12 capture anything else, any non-safety systems.
- However, 13 like loss of main feedwater.
Obviously the answer to the 14 first question is yes. Main feedwater pumps are non-safety () 15 related, so when you try to figure out the loss of main 16 feedwater frequency, you do consider non-safety systems. 17 Then you get into the same question, is does the 18 availability of non-safety related equipment significantly 19 affect the calculation of the initiating event frequency? 20 Now, here you're starting to get into a key word, 21 significant. What is significant. Again, we had some ] 22 debates with the staff on what's the number to use, 10 23 percent, one percent, these kind of things. 24 There's a third criteria that we said. In some 25 cases, you would answer the question yes here, and then we b ANN RILEY & ASSOCIATES, LTD. \\- / Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
447 1 did another screening that said does the initiating event l l ( 2-significantly affect core damage or large release frequency 3 in the focused PRA. So, they could focus PRA results and 4 say that even if the non-safety equipment wasn't important 5 in calculating initiating event frequency, if the resulting l 6 ' core damage or release frequency was extremely low l-7 percentage-wise, then we would still not worry abo:'t that L 8 initiating event, not the equipment involved in it. 9 So, some examples here. Main feedwater, loss of '10 main feedwater or reactor trip with -- how was that 11. trying to think of it. There's an event we have where main 12 feedwater was involved in the initiating event frequency. 13 It's important in calculating that. When we get down here, 14 it ends up being significant, like more than ten percent of () 15 'the risk, comes from that initiating event. So, we end up 16 saying okay, we should worry about that equipment. So, we 17 capture it and then later on define regulatory treatment for 18 that. 19 MR.-KRESS: It looks like a good approach. In the 20 part where.you defeated the active systems in the earlier 21 part, you used the baseline initiating event frequency? 22 MR. SCHULZ: Yes. 23 MR. KRESS: Irrespective of this? 24 MR. SCHULZ: That's right. 25 MR. KRESS: Because basically, that ought to be O AlRJ RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
448 1 captured. \\,~ (( ) 2 MR. SCHULZ: It ought to be captured? v 3 MR. KRESS: Well, if you had a database or had 4 some reason for having an initiating event frequency, the 5 failure of.the component, any component that affects it 6 ought to be capture in that, but still, this is the process 7 that you have to go to to get the risk worth of this thing. I 8 You have to go back and see what its effect is on that. f 1 l 9 MR. SCHULZ: Yes. I 10 MR. KRESS: So, I think it looks like a good 11 process, to capture it. J 12 MR. SCHULZ: It was -- the only problem we ran 13 into is the finding significant. 14 MR. KRESS: Well, you could probably back that out (n,) 15 of, you know, you go through the baseline PRA and see what 16 contributions each of the -- l 17 MR. SCHULZ: Well, that's to some extent what l 18 we're doing down here. 19 MR. KRESS: Yeah, okay. 20 MR. SCHULZ: We're not modifying the focused PRA 21 but we're getting insights out of it trying to say how 22 important is loss of main feedwater from initiating event 23 frequency from a core damage point of view. How many loss 24 of main feedwaters ultimately lead to core damage or large 25 release. ['} IJR7 RILEY & ASSOCIATES, LTD. A-- Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
449 I i 1 MR. KRESS: Now, in this case you're using actual () 2 risk measures like CDF and CFP? I 3= MR. SCHULZ: Yes. 4 MR. KRESS: So, put percentages under criteria 5 here,.there's a little bit of disconnect, but if you make -6 that percentage -- it's really like, you know, if your CDF h 7 .is really 10 to the minus 7, and your goal that you're i S trying to meet is still a minus 5 or 4 or whatever, then 9 using a percentage really is a conservative way to capture i 10 these. l 11 MR. SCHULZ:.Okay, now those are basically.the 12 focus PRA and initiating event frequency were PRA related. l 13 Now, there was other criteria that we used conclude the 14 ATWAS rule, loss of OAC power rules, post-72 hour actions, h 15 containment performance, adverse interactions between these i 16 non-safety systems we're looking at here and safety systems j i 17 and seismic considerations, 18 MR. KRESS: Remind me what the containment j \\ 19 performance criteria is. 20 MR. SCHULZ: Again, we did not use the conditional 21 failure probability considerations here. We were looking 22-more at level 2 type phenomenological type issues about 23 hydrogen burns or ex-vessel cooling. l ' :2 =4 MR. KRESS: The judgment that this was important l .25 in testing the loads or -- l ANN RILEY & ASSOCIATES, LTD. Court Reporters ~ 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034 l E_---_---__--._-.__.-
l 450 1 MR. SCHULZ: Yes, or -- yes, that kind of things. () 2 You actually see this captured reactor vessel insulation, 3 which is not really considered to be safety related but is 4 important, obviously, in the ex-vessel cooling capability. 5 So, this assessment captured that equipment. 6 MR. SEALE: Was there a systematic process you 7 used to assess adverse interactions? 8 MR. SCHULZ: We tried to be systematic about that, 9 but I don't know how you actually can be because you're 10 trying to, in essence, prove a negative again, okay? We did 11 an extensive evaluation, documented that in a WCAP for staff 12 review. That assessment had a bunch of elements to it, 13 okay, looking at T&H type interactions, things related to 14 operator actions, things related to physical location, and h qj 15 it's -- you kind of sit down and think about it. You can 16 also use some PRA, what is modeled in the PRA. You can get 17 some insights out of the Chapter 15 analysis because the 18 people that do that work are trying to think about what can l 19 make -- what's the worst that can happen. So, they will 20 find some. 21 Excessive start-up feedwater flow in a steamline j 22 break, for example. A reactor coolant pump operation that 23 may impede core make-up tank operation. Now, it turns out 24 in AP600, we seem to have done a very good job over the i years at capturing the adverse interactions and putting in 25 g ANN RILEY & ASSOCIATES, LTD. \\ Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034 L_
l l 451 j I 1-safety.related features to prevent them. So, start-up (} 2 feedwater has safety-related isolation. Even though the j 3-system is not safety related to feed, the isolation is. i 4 Reactor coolant pump trip for CMT operation has j l 5 safety related breakers redundant to terminate the power to l l 6 the pumps so that they will stop., So, when we went through 7 this whole evaluation, we ended up not really finding any 8 non-safety features that were important in adverse 9 interaction prevention. 10-MR. CARROLL: Were we going to get a presentation 11 on that subject at some point? 12 MR. LEVIN: This is Alan Levin from the staff. I 13 have a presentation prepared which focuses on our overall 14 RTNSS evaluation. The-evaluation of' systems interactions I 15 are included in that, but what Mr..Schulz has said 16 accurately reflects the staff's conclusions. 17 MR. CARROLL: Okay. 18 MR. LEVIN: We asked lots of questions, but we 19 basically concluded that their treatment was acceptable. 20 MR. CARROLL: Okay. 21 MR. KRESS: If I were to ask you how defense in 22 depth fits into all this, where would I look for it? l 23 MR. SCHULZ: Defense in depth, I think the basic ~ 24 question of RTNSS is a defense in depth question. It's 25 almost one and the same, okay? Again, though, you always 4 ANN RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034 l
452 1 have to separate the elements of defense in depth that are [)i 2 embodied in the regulations from a safety perspective of 3 trapping activity between the fuel, the RCS and containment. 4 That's one way of thinking about defense in depth. 5 MR. KRESS: Which is automatically covered by your 6 design. 7 MR. SCHULZ: That's right, in the regulations, 8 absolutely. 9 MR. KRESS: And then when you talk about the 10 importance of -- 11 MR. SCHULZ: Non-safeties. 12 MR. KRESS: -- non-safety systems, that's a 13 defensive concept in itself. 14 MR. SCHULZ: That's right, and that gets more into /' (%) 15 what we're talking about here, of what -- how important are 16 these other ways of doing things, these non-safety related j 17 things, and it's trying to look at both from a PRA 18 perspective and sort of other thinking perspective. 19 MR. KRESS: That is a sort of a defense in depth 20 concept. 21 MR. SCHULZ: Yes. 22 MR. KRESS: As well as use an expert panel to pull 23 things in that might not have showed up on PRA. 24 MR. SCHULZ: That's right. 25 MR. KRESS: It's an interesting concept. j O ANN RILEY & ASSOCIATES, LTD. \\d Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
t 453 1-MR. SCHULZ: And there's a lot of ways of slicing () 2 that, and it's hard to do it with one, one way. 3 The next several slides go through the results of 4 the screening and what criteria captured what system. The 5 focus PRA ended up, at least directly, not capturing any 6 systems. The AP600 focus PRA, the core damage frequency 7 increases. Now, this is shutdown and at power lumped 8 together. I'm not trying to get into the details of the 9 PRA, although that's kind of a whole other discussion, but I 10 just wanted to summarize the resultc. l 11 So, the core damage frequency increased 2.6E to 12 the minus 7 to 8.3E to minus 6, so a little more than an 13 order of magnitude -- 14 MR, KRESS: When you defeated all the active ( 15 systems, that's the -- l 16 MR. SCHULZ: Yeah, this is as I talked about it. 17 Same initiating event frequency but no non-safety features 18 versus the NRC goal of 1E to the minus 4. So, in core l 19 damage frequency space, we have pretty good margin relative 20 to the goal. l l 21 The severe release frequency also increased a ) 22 similar amount, but the margin is less. It's a small margin l l i 23 there, and that ended up being a source of contention of ] 24. gee, if you're that close, you know, what happens if the 25 base line's a little bit wrong or the success criteria is a l l l O ANN RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034 4 l
454 1 little bit wrong, could you;go over the goal, and maybe you () 2 need to capture something. I'll talk about uncertainties -- 3 MR. KRESS: Where did this NRC goal of one times 4 4 to the minus 6 show up?? Where'will I. find that. 5 MR. CARROLL: In'the regulations. 6 MR. SCHULZ: I don't know. We kind of volunteered 7 that. 8 MR. McINTYRE: This is. Brian McIntyre. If you.go-. 9 back to the history of RTNE9, this is something that we, the 10 collective we on this, actuall) both sides of the room 11 reached during an ALWR steering committee industry NRC. 12 meeting out'in -- 13 MR. KRESS: It was up in URD maybe? '14 MR. McINTYRE: No, this is what we agreed to do. () 15 Tom Early's comment was -- 16 MR. KRESS: 'But it's not really -- 17 MR. McINTYRE: It's not in the URD. 18 MR. KRESS: It's not really appropriate to call it 19 an NRC goal I don't think. 20 MR, McINTYRE: No, I would say program objective 21 or agreed upon objective. 22_ MR. KRESS:.Okay. 23 MR. SCHULZ: You could, I mean, you notice here, j 24 this is two orders of magnitude different, which is a little 25 O-ANN RILEY & ASSOCIATES, LTD. Court Reporters i 1250 I Street, N.W, Suite 300 Washington, D.C. 20005 ) (202) 842-0034 J
455 'l MR. KRESS: Do I interpret that to mean the CCFP 2 is. 01? 3 MR. SCHULZ: In this whole process we do not deal-4 with conditional containment failure -- 5 DR. KRESS: 'I understand, but that is kind of a l 6 way to think of that. 7 MR. SCHULZ: It is a way of thinking about it and 8 I point that out because you could argue that maybe this 9 should be 10.to the minus 5 or should have been, but this is c 10 hindsight. I don't think I can say any more -- 11 DR. POWERS: -- indicate.01 for the CCFP? 12 Doesn't it -- aren't you looking at the convolution of l 13 conditional vessel failure probability and containment l 14 failure probability here? () 15 DR. KRESS: Yes, yes, and if we talk -- it's not 16 really_ kosher to divide one of those by the other. l 17 DR. POWBRS: If we took the -- 18 DR. KRESS: Unless you have maybe one or two 19 really dominant sequences and then you can do that. 12 0 DR. POWERS: I wonder how the numbers for the SRF 21 would change if we took the probability of -- l 22 DR KRESS.: CDF? 23 DR. POWERS: -- vessel failure given core l l 24 degradation to be one? 25 DR. CARROLL: Vessel meaning reactor vessel? ANN RILEY & ASSOCIATES, LTD. i Court Reporters l 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
456 1 DR. POWERS: Yes, the reactor vessel. 2 MR. SCHULZ: They certainly would go up. They 3 would go up somewhat less here, because one of the things 4 that happens, happened to us, is that when we got into 5 focused PRA, for example the diverse actuation system was 6 assumed to fail, the diverse actuation system is very 7 important in ATWS. 8 A lot of ATWS sequences, as Jim Scobel talked 9 about, lead to types of core damage scenarios that lead to 10 containment failure directly. Now we still have, obvious 1p, 11 in a lot of sequences we still end up with containment 12 working, as we calculated here, and if you assume 13 containment failure on core damage, then obviously this 14 becomes your severe release frequency, so it would go up an n() 15 order of magnitude. 16 But the bottom line right now is if you look at 17 the RTNSS assessment in our WCAP under focused PRA, we did 18 not capture any non-safety systems, except as sort of 19 related to the uncertainty discussion, which I'll get into 20 in a minute. 21 Initiating event evaluation, this is that 22 three-step process, one of the sets of equipment that was 23 captured out of this is the turbine island systems that 24 support power operation whose failure ends up in reactor 25 trip. \\ [/ ANN RILEY & ASSOCIATES, LTD. \\- Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
457 1 It is particular those were transients with main ( 2 feedwater available -- those events were a little bit more 3 likely. 4 This is kind of interesting, because I mean all 5 plants have these systems. They are not less reliable for 6 AP600. They are probably more reliable with all the 7 advances, but this whole process done systematically 8 captures these things. 9 The other thing that it captured was RNS cooling 10 operation during reduced inventory conditions and this is 11 looking out of the shutdown risk aspect when RNS is running 12 and in reduced inventory conditions.you have less redundancy 13 and diversity in the passive systems because the passive RHR i 14 is assumed to be incapable of functioning in this mode, so l'\\) (_, 15 you only have the IRWST feed-and-bleed type cooling. 16 It does pick up the RNS, the cooling water 17 systems, and the AC power that are needed to make RNS work 18 get picked up in this item. 19 Well, let me talk a little bit about 20 uncertainties. 21 DR. KRESS: That is a pretty safe statement there, 22 you know? 23 MR. SCHULZ: Which one? 24 DR. KRESS: Some uncertainties exist. 25 MR. SCHULZ: Probably an understatement to some ANN RILEY & ASSOCIATES, LTD. \\ Court Reporters ss 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
458 1 extent. (J) 2 DR. SEALE: Those two previous bullets -- you are ~- \\ 3 very right in that those are the things that really give you l l 4 indigestion when you look at the traditional assessment of 5 safety systems, the fact that those things are not there. l 6 MR. SCHULZ: Yes. 7 DR. SEALE: And it's nice to see them come out 8 when you take this kind of focused look at things. 9 MR. SCHULZ: It seems to make sense. 10 Now, uncertainties -- the big issue here is how l 11 big are the uncertainties relative to the margin, in 12 reality, so we kind of thought more about the release 13 frequency issue than the core damage frequency issue, but 14 some of these are not -- they get tied together. 7-( 15 You see a few things listed here which we 16 considered to be the more major -- at least points of 17 contention, points of discussions between Westinghouse and 18 the Staff. 19 T&H uncertainty for passive system success 20 criteria -- how many ADS valves do you need? That is really 21 the big question relative to core makeup tanks, 22 accumulators, those kind of interaction. 23 We spent a lot of time trying to resolve that 24 issue by studying T&H analysis, by making it more 25 conservative, to try to bound and limit uncertainty. How /'] ANN RILEY & ACSOCIATES, LTD. 's / Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
459 1 accurate is MAAP is behind this, because we used MAAP to () 2 make 500 runs looking at different break sizes, locations, 3 combinations of ADV valves and all that. That is totally 4 impractical to do with a detailed DBA type code, NOTRUMP -- 5 it would take forever to do it. 6 We ended up benchmarking MAAP against NOTRUMP. We 7 ended up re-running some of the limiting cases with NOTRUMP. 8 We feel we have dealt with this uncertainty. However, it 9 still remained. It never really got taken off the table as 10 an uncertainty. 11 Another element of uncertainty was what is the 12 reliability that we should use for several of the key 13 components? They weren't uncertain because they were key, 14 but they were -- the combination of being important, (m) 15 risk-important, and having some uncertainty is why they are 16 listed here, so this squib valves in particular used an ADS 17 here and the low DP check valves, what their reliability 18 was, and also the reactor coolant pump breakers. They are 19 important because if they don't work then the core makeup 20 tank in some cases doesn't work, and the core makeup tank 21 not working means you need manual ADS, which is less 22 reliable than automatic ADS, so that is kind of the thread 23 there. 24 There was some question -- the severe accident l 25 hydrogen burn really relates primarily to the IRWST events I i '() ANN RILEY & ASSOCIATES, LTD. 's / Court Reporters i 1250 I Street, N.W., Suite 300 j Washington, D.C. 20005 ) (202) 842-0034 i l 1
460 l' =and they-are close'to.the containment and we think that a / h 2 hydrogen diffusion flame coming out there won't fail the V 3 containment but that_was a point of deba'te. 4 The : initiating event importance' criteria -- I l .5 mentioned what "significant" means. We had some 6 discussion -- was it .1 or.01? What level should you use 7 there, and it is hard to make a decision there, to get 8 agreement. 9 The way we ultimately dealt with this in written 10 space was to define or capture some features that we tried 11-to relate to or cover off uncertainties with. The next page l 12 -kind of talks about'how we did that. L 13 Ideally we-tried to find what we called a direct 14 compensation. An example of that is there was some g 15 uncertainty in long-term cooling, T&H, how many ADS valves 16 we needed. One non-safety feature that would reduce the 17 reliance on the passive systems in that mode is the RNS, 18 because if the RNS works in long-term cooling situations, it 19 -is injecting and re-circulating and it's very insensitive to 20 how many ADS valves you would have to have, so the RCS 21 pressure, whether it is 15 psi or 10 psi or even 50 psi, it 22 doesn't matter. The pump can put the water in there, 23 whereas the gravity injection recirculation requires the 24 pressure to be very low. 25 In getting the pressure very low, how many ADS O ANN RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
461 1 valves do you need to work was the uncertainty. ,m ( ) 2 Now there are some situations where there was \\m/ 3 uncertainty, where we couldn't really come up with a 4 nonsafety feature that sert of directly will reduce the 5 significance of that. 6 An example of that would be a direct vessel 7 injection line LOCA and the resulting, again, ADS valves you 8 need for short-term and long-term cooling. In a DVI line 9 break, or any LOCA, the only real nonsafety system that can 10 help you is the RNS in terms of how many ADS valves you 11 need. 12 In a DVI line break, that renders the RNS 13 ineffective -- it fails it basically because it is a 14 hindered system. It's got two injection points and the fN ( j/ 15 whole system spills and you can't do anything about that the 16 way the design is, so there's nothing we could come up with 17 that would directly compensate for that. j 18 However, what we did was said, well, okay, what we i 19 are trying to do here is add margin in the severe release 20 frequency and core damage frequency, so if we put some 21 additional regulatory oversight on a feature that reduces 22 that, even if it is not the direct uncertainty, then it 23 still compensates. 24 In this case, by adding some regulatory oversight 25 over the diverse actuation system, that would reduce core ANN RILEY & ASSOCIATES, LTD. \\~ Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
462 1 damage frequency and severe release frequency and even /%
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\\ 2 though the uncertainty in DVI response remained, we had %_) -3 added margin to the calculated core damage frequencies and 4 release frequencies. 5 We picked DAS in this case because it was 6 relatively important to ATWS. ATWS ended up in focused PRA 7 as being a fairly significant contributor to core damage 8 release frequency kind of numbers so by adding that one 9 feature we got a fairly good improvement. 10 So here you see basically the features that we 11 ended up adding, capturing in this process to try to 12 compensate for uncertainties and it is the DAS -- the DAS 13 has sort of two parts you can think about it. 14 Part of it deals with ATWS mitigation and part of () 15 it dea.'.s with more ESF type functions, and we ended up 16 capturing both of those to deal with T&H uncertainty. 17 R&S injection, again T&H uncertainty as well as 18 some of the squib valve, check valve kind of equipment 19 reliability uncertainties. 20 Onsite AC power -- pretty much for the same reason 21 R&S and in fact they kind of go together. One of the things 22 you don't see here is the cooling water systems that 1 23 normally support RNS -- component cooling water and service 24 water. The reason you don't see that is that the way we 25 approached this problem is because we didn't really capture [ T ANN RILEY & ASSOCIATES, LTL. g \\-) Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034 i \\
463 1 this equipment in focused PRA and we're covering f~) 2 uncertainties, we say we don't really need the whole system. v 3 We will accept as being sufficient one train of the system. 4 Now when you look at a system that is not normally 5 running, you don't even know if you have the one train, so 6 you should do something to put some regulatory oversight to 7 make sure you at least have one train, so the RNS doesn't 8 normally run so you should look at it. The diesels don't 9 normally run so you should look at it. 10 However, to run, to operate AP600 you need one 11 train of component cooling water and one train of service 12 water because they support some normal functions. You can't 13 run the plant without them. j 14 The same is true of the CVS, although.not quite l(Oj 15 the same way -- it doesn't run continuously, but it will be 16 turned on once a week a least to make up for small leaks out 17 of the reactor coolant system and again you really can't run 18 the plant without the CVS. 19 There is some equipment that would have been 20 captured to compensate for uncertainties, but we ended up i s l 21 not capturing because we decided we only needed one train, 4 22 one out of two pieces of equipment, and those equipment 23 normally ran, so they needed to be run. So we didn't feel 24 that we needed to do anything more. And we ended up i 25 capturing hydrogen igniters relative to the burn, especially .f) ANN RILEY & ASSOCIATES, LTD. \\d Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
464 1 around IRWST. ] -s l L' )T 2 DR. CARROLL: Give me an example of i 3 thermal-hydraulic uncertainty? What is it we are 4 compensating for? 5 MR. SCHULZ: Gee. Where do I start? This whole 6 question grew out of -- when you do the PRA and your success l 7 criteria, you need to decide how many ADS valves do I need. 8 That's probably the most important focus. There's other 9 success criteria, but ADS is probably the key. 10 What we did to support that is literally hundreds ) 11 of MAAP runs to look at the different LOCA categories, the 12 min and the max size of those, hot leg, cold leg breaks, 13 with one accumulator or one CMT. Tried to assess whether -- 14 how important ADS stage 1, 2 and 3 was. Was it needed at ) . r~N i
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) 15 all or just 4th stage, how many 4th stage? You get into v 16 operator actions, when they open ADS, or is it automatic? 17 Is containment closure or containment isolation needed or j 18 not? Many, many questions. 19 We used MAAP to run that. There was a lot of 20 uncomfort -- discomfort with using MAAP to assess this. How 21 accurate is MAAP? What about inaccuracies? And so that was 22 the original question, you know. Was our success criteria j 23 accurate? If we had, for example, proposed using DBA 24 success criteria, single failure, it would have gone away, 25 pretty much, I think. But we didn't. We had proposed, l[~D ANN RILEY & ASSOCIATES, LTD. Y_ I Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034 l
i 465 1 because we thought, based on all of our MAAP work, that we 2 could take, in most cases, two four stage failures and still 3 get successful depressurization. 4 Now, we embarked then on an evaluation to try to 5 determine if there was enough uncertainty in the T&H 6 calculations that they would change the success criteria, 7 that maybe we were wrong, maybe we were being optimistic. 8 So we did a benchmarking of MAAP versus NOTRUMP and looked j 9 at -- set up cases where we ran the same transients with-10 both codes, with the same kind of inputs. Because NOTRUMP 11 in Chapter 15 is run with conservative decay heat and all 12 those kinds of assumptions. MAAP, as run for success 13 criteria, was run with best estimate decay heat. And it was ) 14 a lot of those things you had to kind of make equal so that 15-you could have an equal comparison. 16 Then we looked at the results and, of course, the 17 results didn't agree exactly, as you might imagine. We 18 tried to assess whether there were problems, uncertainties. 19 So it was a difficult question to answer. It was one that 20 was very hard to prove that MAAP was adequate, there wasn't 21 uncertainty. Or how much uncertainty, was it enough to 22 change success criteria? 23 After a lot of, lot of work, we think we proved 24 that point but, ultimately, we felt that the fastest way, 25 most reasonable way out of town was to propose some ANN RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
466 1 additional features which were another way of dealing with .I 2 these uncertainties. By saying that I'll put some 3 regulatory oversight on the RNS and that it more likely 4- ..wou)d be available and, therefore, the question of whether 5 you need two or three ADS valves becomes less important. 6 Okay. The deterministic criteria, we also looked-7 at. ATWS Rule, well, that captured the DAS. function that 8 deals with AWTS so the reactor trip, turbine trip, start of 9 passive RHR, those functions are required to meet the AWTS 10 Rule, so they got captured in this criteria. 11 Loss of AC power. The passive systems do a 12 wonderful job.with loss of AC power, so that really wasn't 13 much of a challenge, and we didn't capture anything there. 14 Post-72-hour actions. The equipment that we.have 15 added, the ancillary equipment, two small generators, the 16 PCS water storage tank and transfer up to the tank, some 17 fans for control room, I&C room cooling, those things, are 18 not safety-related. They are non-safety-related equipment, 19 with some enhancements. So because they are, technically I 20 speaking, non-safety-related, we looked at them and this, 21 the RTNSS process, and considered them important to dealiag 22 with the 72-hour long-term shutdown. So they got captured 23 here. 24 Containment performance. We -- and, again, this i 25 is what non-safety features are potentially important. For l ANN RILEY & ASSOCIATES, LTD. l l M Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
467 1 i 1 example, things like the IRWST drain is actually achieved [~ ) 2 through the use of safety-related valves. Now, valves are U 3 safety-related because of containment recirculation for 4 normal design basis operation. However, because of the way 5 they were designed, they also can be used to dump the IRWST. 6 So that aspect of ex-vessel cooling is actually achieved by i 1 7 a safety-related function. And that's true of most of the 8 features that are important in dealing with containment l l 9 severe accident phenomena. One thing we did capture was the 10 reactor vessel insulation. 11 Adverse systems interaction, I have actually 12 talked about a little bit, that we basically did a separate 13 assessment of adverse interaction, systems interactions. 14 And all of the things that we identified there that were i C\\ ( ) 15 potential adverse interactions were dealt with by 16 safety-related features, isolation valves, that kind of 17 thing. And so they don't get involved in this process. 18 Seismic considerations by themselves did not 19 capture any SSCs, although when we end up dealing with these 20 72-hour things, because of their mission, we do get some 21 seismic requirements. But in looking at the seismic margins 22 evaluation out of the AP600, we did not capture any. 23 The next step in the process is to take the SSCs 24 that we captured in our evaluation of what might be 25 important or what is important and to define the mission O() ANN RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
468 1 statement for that. Now, I didn't show all those statements () 2 here, but in the WCAP we actually go through every feature, 3 like the RNS pumps for initiating event frequency, and we 4 talk about what is'important about it. Okay. 5 For example, in that initiating event frequency, 6 capturing of the RNS, it is not important what the start 7 capability of the system is -- of the RNS. It is not 8 important aligning the valves, because they are already 9 aligned. When that system becomes important, it is already 10 operating in the RNS cooling mode. So the question is, what i 11 is important in keeping it running? And that's the kind of 12 thing that we do in this part of the evaluation. 13 The third part then is, well, what is the 14 appropriate regulatory oversight to try to achieve that (~'s q,) 15 mission? And there's many elements to those oversights, it i 16 is not just one thing. The turbine island systems that got j 17 captured for plant transients with loss of main -- with main 18 feedwater available, the secondary side systems, we have 19 basically -- the proposed regulatory oversight is basically 20 what we already have. We have a description in the SSAR 21 that talks about features in those systems, and we think 22 that there is nothing additional. We did not propose any 23 additional oversight. 24 Part of the reason for doing that, again, is these 25 systems are downgraded from current plants. They are (~/ ) ANN RILEY & ASSOCIATES, LTD. Court Reporters w-1250 I Street, N.W., Suite 300 l Washington, D.C. 20005 (202) 842-0034 u--__.-___----_------------___------_--------------_--
l 469 1 1 already in current plants, they are already non-safety (} 2 AP600, they are non-safety. So we weren't doing anything j 3 here to make the systems worse. We also didn't think there 4 was much appropriate that you could do, or needed to do. So 5 in the WCAP on the RTNSS, we say that for the turbine island 6 systems, the SSAR description is sufficient. We do point 7 out in the WCAP some areas where features described in the 8 SSAR are enhanced over current operating plants to give a 9 flavor for -- we think we have improved them, but we really 10 didn't take credit for that. 11 For other -- Excuse me. 12 DR. CARROLL: Philosophically, I don't agree that 13 because the operating plants haven't tech spec'ed them, or 14 provided some regulatory oversight, that that shouldn't be () 15 done on AP600. I can certainly argue that the things in the 16 turbine island could have surveillance requirements, for 17 example, and probably be more reliable. 18 One of the things that has happened in this 19 industry is we have got people so caught up in tech specs 20 are the most important thing in the world, and they often i tend to forget things or not put the focus on things that 21 22 are reliability and safety issues, even though they are 23 called non-safety grade systems. 24 Okay. That's just a comment. 25 MR. SCHULZ: Yeah. I may have slanted that -- [^'} ANN RILEY & ASSOCIATES, LTD. \\/ Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
l 470 1 i i slanted that -- stated that incorrectly in a sense. The I <s {J 2 initiating event frequency used for this transient is based l 3 on historical data. The operating plants have systems that 4 are of the same QA level, the same lack of tech specs. 5 That, plus the fact that we think we have made improvements 6 in the systems, we think is sufficient. So, whereas, in 7 some of the other situations like the loss of RNS during 8 shutdown mode, you could make an argument that, since that 9 system, on AP600, is non-safety-related, maybe it will be l l 10 less reliable than the operating plant RNS systems or RHR j 11 systems which are safety-related. 12 Now, we don't actually think that is true, because 13 we have made a lot of detailed improvements on hot leg level 14 instrumentations and all kind of things to address shutdown f' I (,y) 15 issues. But there still is this remaining kind of question 16 of you made the system non-safety-related from an active l 17 operations point of view, how does affect the reliability of l 18 the system? So we felt that it was appropriate then to do 19 something to that system. 20 Now, the other written systems that were captured, 21 let me talk about sort of the generic things that we have 22 done, or at least pointed to, that exist to help make them 23 reliable. Again, SSAR description, Chapter 3 -- that really 24 should be a comma there. Chapter 3 deals with primarily the 25 codes used to manufacture the equipment, that's really what ANN RILEY & ASSOCIATES, LTD. \\-- Court Reporters I 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034 L________.__.__
471 1 I am relating to here. ( ) 2 Chapter 14, testing. These non-safety systems s_- 3 are, as Gene Piplica talked about two days ago, captured in 4 the Chapter 14 testing. As I talked about this morning, I 5 maybe didn't point out, but all of the RTNSS important 6 systems, as well as others, are captured in the D-REP. So ultimately, the maintenance rule will capture and monitor 8 the sort of long-term reliability, availability of these 9 systems. 10 All of these systems have ITAACs. Now, our ITAAC 11 approach is graded, so the RTNSS important systems don't 12 have quite the level of detail that a safety system does, 13 but we think it does relate to and show the performance of 14 the RTNSS systems for their RTNSS important missions. /~N ) 15 Post-72-hour equipment has a little bit extra. We l 16 have hazard protection against high winds and seismic. This 17 is really why we ended up with this extra equipment, the 18 concern over, if you have a seismic event, that maybe you 19 can't get your transportable equipment from the local { l 20 community, you might have to go further or maybe you can't l 21 get it. The same with, if you had a hurricane that affected 22 the area, there would be a lot of competition for this 23 equipment. So having the hazard protection for these kind 24 of events was an important part of this, so we captured 25 this. [ '} ANN RILEY & ASSOCIATES, LTD. 's / Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034 L_____-____--____-____-_________-______
472 1 Now, we were already doing that, but this closes .[ } 2 .the loop with making sure that it meets the mission that we w l-3 were wanting it to me. 4' DR. CARROLL: How does that statement square with 5 -the fact that you have provided no protection for the diesel 6 generator radiators? 7 MR. SCHULZ: Well, the diesel generator radiators 8 are not involved in this 72-hour story. We have small 9-ancillary diesels which are protected. The bigger diesel 10 generators do not get captured by anything that, in the 11 RTNSS process, that says, hey, they are important from 12 hurricane or post-hurricane type thing. 13 DR. CARROLL: They turned out to be at Turkey 14 Point, a different plant. () 15 MR. SCHULZ: A-different plant. They didn't have 16 a passive containment cooling system, or a passive RHR. 17 Right. And they should be. That's right. I agree. 18 As a final element, because a lot of the missions 19 and reasons for capturing the RTNSS equipment was to make it j 20 reliable, just from a sort of random failure point of view, 21 maintenance point of view, a key element in the proposed 22 regulatory oversight is what we call short-term availability 23 controls. -24 These are like tech specs, but not tech specs. 25 I would like to get into talking about those a Oc ANN RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
473 1 little bit. Well, what are these things? Again, they are () '2 not tech specs. They are not' tech specs because they don't =3 meet the tech spec screening criteria which I talked about 4 yesterday in terms of mitigating design basis accidents or 5 being risk important. 6 Now there is a gray area here. What is risk 7' important that tech specs rating criteria doesn't really say 8 what constitutes risk important. In my mind it would be if 1 9 you really needed something to meet the NRC safety goal, you 10 might consider it being important enough to meet -- to be a .11 tech spec, and we didn't end up capturing any that way. 12 These controls are structured to look like tech 13 specs. Now we originally didn't want to do that because we 14 were afraid that because it looked like tech specs they () 15 would get sucked in to tech specs. 16 DR. SEALE: If it looks like tech specs, it will 17 be tech specs. 18 MR. SCHULZ: Right -- look like, taste like, 19 whatever. 20 But we ultimately decided after talking to the 21 utilities who were going to have to implement these, they 22 said they are trained to understand what the format -- there 23 has been a lot of interaction between the NRC, the utilities 24 to make tech specs understandable to the utilities, so we 25 ultimately said okay, it just makes sense to improve the O ANN RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034 l l ______________a
474 1 communication, to make these-things look like tech specs, () 2 and in doing that, they defined like tech specs the modes of 3 applicability. 4 Now how we picked those modes of applicability 5 relates to the missions that we were trying to deal with, 6 why they are important for RTNSS. 7 So just because we capture RNS for shutdown 8 cooling doesn't mean RNS has to be available all the time. 9 It defines actions and completion times in the 10 same manner as tech specs. However, there's some 11 significant differences. When you are dealing with what to 12 do when the equipment is not available, ultimately tech 13 specs in almost all cases direct you to shut the plant down 14 if you can't meet the other action statements. 15' In the short-term availability controls it doesn't 16 do that. Although it is possible in extreme cases maybe to 17 get there, it's not stated black-and-white required, and I 18 will show you what we do specifically require. 19 DR. KRESS: I am going to ask you a dumb question. 20 Why is Modes capitalized there? 21 MR, SCHULZ: That is tech spec carryover. I even 22 got trapped here myself. 23 DR. SEALE: Baggage. 24 CHAIRMAN BARTON: Looks like and smells like a 25 tech spec, that's why. O ANN RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034 i.
475 1- ~MR. SCHULZ: Special terminology in tech specs (-
- 2 like modes.-- I didn't even do it consistently here --
3 Completion Times, are capitalized because they have special-4 meaning in tech specs. That's why. 5, The short-term availability controls include 6 surveillance requirements to assess whether the equipment 7 really is available and there is a bases discussion -- why 8 do we have the spec or contro), short-term availability. 9 control, what is it doing -- just for helping understand. 10 Same kind of reasoning, although it is less extensive than 11' tech specs. 12 These controls, as I mentioned yesterday, are 13 contained in the SSAR, so that adds to their control once '14 the plant starts operating. ) 15 This page is out of the SSAR. It lists all of the 16 components and features that we have place short-term .17 availability controls on and a little bit about what part of 18 the system. In some cases, this is sort of a mode 19 description, although the modes are actually listed over 20 here. 21 Number of trains -- in some cases we require 22 basically the whole system to be available, like in DAS for 23 it'to be functional both trains have to be available because 24 it's two-out-of-two logic, so having one of the trains 25 available doesn't really do much for you. ANN RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
476 1 In other cases like RNS there really are two 2 2 divisions, two trains, and one of them can help you. In 3 some cases we actually require both to be available, and 4 .thisEis relating to the shutdown initiating event frequency 5 condition, which we consider to be more important than this-6 ~ mode of RNS which is at power kind of high-mode injection 7 capability and that was added for uncertainty compensation, '8 so we only required one of them to be available. 9-DR. CARROLL: Now what is the implication of this? 10 I'm sitting there running at full power and all of a sudden 11 I discover my DAS ATWS mitigation. system has conked out -- j l 12 both channels. 13 MR. SCHULZ: Let me talk about that. I have got 14 two examples here. ) 15 DR. CARROLL: Oh, okay. 16 MR. SCHULZ: We can talk about that specific one i 17 if this-doesn't answer your question, but these all end up 18 being -- using a lot of similar terminology and action l 19 statements. 20' I have got two RNS ones to show you. -21 This one is the at-power one where I require one 22 train and when you look at the basis it's because of 23 uncertainty compensation. l [ 24 Modes 1, 2 and 3 are selected because that is when 25 the injection capability is important. When you start
- (s -
ANN RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
477 1 getting into lower modes the system is actually operating ) 2 for RCS cooling so its role as an injection system becomes ( 3 either nonexistent or very unimportant. 4 As in tech specs you would typically have a 5 condition here. If the requircd train is not available, 6 what do you do? 7 We have defined within 72 hours that you would 8 notify the Chief Nuclear Officer for the plant, and what 9 this is in our minds doing is the operating staff has got to ~ 10 tell their high boss that, gee, I have got a problem here i 11 and I haven't been able to get it back online, so it is l 12 going to attract attention to help get this solved. l 13 That happens within a.timeframe that is actually 14 similar to a tech spec, the 72 hours of when equipment would () 15 have to be normally returned to service, and we would expect 16 that often that would get done there. 17 Now within 14 days the equipment would need to be 18 returned to service or you would bump into this next level ~ of activity. 19 20 The next level of activity is that one day after 21 the 14 days you would have to submit a report to the same 22 guy and say, you know, why you didn't get it fixed, what the x 23' interim compensatory measures you are taking to deal with 24 this, and when you are going to get it back online. 25 Ultimately if you get into this, you would have O ANN RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
478 l 1-one' month to place in the plant records justification for 2 the action, so this all makes the utility and the operating L 3 staff subject to sort of post-event review. Did they take l 4 prudent actions /did they not? 5 IMt. KRESS: What happens if you have the condition 6 A -- A.1 is not done. What happens later on down the road?. 7 Is this something that has a compliance nature to 8 it? 9 MR. SCHULZ: These short-term' availability 10 controls are in the SSAR. 1 11 DR. KRESS: They are in the SSAR. 12 MR. SCHULZ: They are in the SSAR, so if you don't 13 take this action -- 14 DR. KRESS: The NRC could -- () 15 MR. SCHULZ: You are operating outside your design 16 basis. 17 CHAIRMAN BARTON: Yes, they could get you for 18 ineffective corrective action or something like that. Sure. 19 MR. SCHULZ: Yes. 20 DR. KRESS: Oh, so these things do have some 21 weight? l 22 DR. SEALE: Oh, yes. They are enforceable, j 23 CHAIRMAN BARTON: Yes, they are. l 24 MR. SCHULZ: That's right. You will see this kind i 25 of language used for virtually all of the availability l I l O ANN RILEY & ASSOCIATES, LTD. l Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034 ( l
j l 479 l l 1 controls. ( 2 The surveillance vary a bit more, depending on 3 the particular system and equipmen' you are dealing with. 4 For the RNS, now again we are talking here in Modes 1, 2 and 5 3 when the RNS is not normally operating so the surveillance j 6 would be once every three months to come in and make sure 1 the pump works -- turn the pump on, run it on its miniflow, 7 8 make Gure it develops some minimum head. 9 Also, verify that these three valves operate and' 10 these valves are valves needed to actually align the system i 11 from the IRWST to the pump suction and back to the RCS. l i 12 There's three valves that would have to be opened and they ) 13 have to be assessed at the same timeframe that they are I 14 operable. () 15 I am not going to read all this, but basically the l 16 bases that you end up for this short-term availability 17 control. It talks about why it is being done. It talks 18 about for example when planned maintenance should be done. l 19 One of the reasons that has been put in here -- 20 this doesn't even occur in tech specs -- one of the reasons 21: it is put in here is because in some cases we end up with. 22 RNS, for example, it being apparently important in all modes 23 of operation, and we are a bit into that trap of tech specs 24 versus current RHR systems, so we have identified here that 25 we actually recommend that planned maintenance on RNS be i O ANN RILEY & ASSOCIATES, LTD. Court Reporters i '1250 I Street, N.W., Suite 300 2 84 - 03 l
480 1 done at power. The system is not normally running then. It m l ) 2 is not required to mitigate design basis accidents, although J 3 it can help. 4 It is more important in shutdown, and this control 5 only requires one division to be operable. That leaves -- 6 at times you can take the other one out to work on it. 7 This control is for, again, the RNS, but in the 8 reduced inventory modes of operation. So we have defined 9 those as -- and this is basically the same kind of wording 10 we used in the tech specs for the similar conditions, mode 5 11 with the RCS pressure boundary open and mode 6 with the 12 internals not yet removed and the cavity not flooded. And 13 in this case we need both RNS pumps to be operable. And if i 14 one pump is not operable, you got 12 hours to initiate (b/ 15 actions to increase the water level, to basically get out of 16 -- start getting out of the reduced inventory condition and, 17 in 72-hours, to actually have completely gotten yourself 18 out, into a mode then when you are not as sensitive to l 19 losing RNS. These kind of actions are the same as you saw 20 for the other. 21 DR. CARROLL: One worry I have about this 22 notifying the chief nuclear officer, it almost invites 23 people on shift to delay until that time. I mean I have 24 been in so many situations where I am not sure what really 25 has happened, one should really err on the side of getting Os ANN RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034 l
481 1 all the brains you'can involved. But I know operators well ! () i 2 enough to know that a lot of times they are going to, you 3 know, say, well, I'll figure this out and I have got 72 4 hours to do it in. l 5 CHAIRMAN BARTON: I think the thing that is 6 different, that you will find in the industry today, with 7 the low threshold of reporting, that you are going to find 8 that people jump -- put these items in their corrective 9 action system, and I'll guarantee that every plant talks 10 about these in the morning at their plan the day meeting 11 what has occurred in the last 24 hours and events. 12 DR. CARROLL: Sure. 13 CHAIRMAN BARTON: And the 72 hours gets you on a 14 weekend, it covers you for a weekend when a plant manager ( 15 ain't there, so -- 16 DR. CARROLL: But you have got somebody on call. 17 CHAIRMAN BARTON: Yeah. 18 DR. CARROLL: According to the tech spec. 19 CHAIRMAN BARTON: That's true. 20 DR. CARROLL: Or according to the -- whatever this 21 is. 22 CHAIRMAN BARTON: But I don't have that concern, 23 because I think today, you know, you know by the next 24 morning or within, you know, within one day, the plant 25 manager is going to know that. l l. ANN RILEY & ASSOCIATES, LTD. I Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034 _ _ _ _ _ _ _ - = _ _ _ - - _ _ _ - _ _ _ _ _ _ _ _ _ _ _
482 1 DR. CARROLL: Okay. () 2 CHAIRMAN BARTON: I really -- I think that happens 3 today. 4 MR. SCHULZ: That was kind of the feedback we were 5 getting. We had a lot of discussions with our utilities 6 that are supporting us on what to do here, because there 7 were all kind of different things you might do. We ended up 8 thinking that this was going to be effective. 9 It also gives the plant a few days to fix the 10 problem. Many cases, the kind of problems you run into are 11 you are not sure it is available or not. Maybe it really 12 is. Or maybe something very minor can be done to fix the 13 problem. So it gives the plant some time to do that. l l 14 The surveillance for this is a little bit () 15 different than the at-power surveillance because the system 16 is normally running in this mode. So, basically, we gave 17 the plant an option of either saying that both pumps are 18 running and the combined flow is greater than some value, or 19 that one pump is in operation and that each pump can l 20 individually circulate at least half of that flow rate, and 21 that this has to be done within one day of entering this 22 mode of operation. So you either have to verify that both ) 23 pumps are running prior to entering these mode of 24 applicability, before getting into reduced inventory, or 25 that, if you have only got one pump running, that the pump l i O-ANN RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
483 1 that wasn't running, or isn't running, has been started (nJ 2 within one day of entering the mode of applicability. 3 And you see a similar set of bases which deal with 4 why this is important and some clarification on what 5 increasing the RCS water inventory really means, that kind 6 of thing. 7 That is the end of my prepared material. i 8 CHAIRMAN BARTON: That's really good. Very good. 9 Very good. 10 MR. SCHULZ: Thank you. 11 CHAIRMAN BARTON: Any questions on this before we 12 hear from the staff on this section? 13 [No response.] f 14 MR. LEVIN: My name is Alan Levin, from Reactor /O (,/ 15 Systems Branch, and I will be making what I think will be J 16 fairly brief presentation on the staff's review of RTNSS. l l 17 Mr. Schulz covered a substantial amount of 18 material that is in my slides. Rather than going through i l 19 everything in detail, since I have only got a few minutes, I ] 1 20 am going to hit the high points for you. I also want to l 21 point out that, as Terry said, this took a lot of time. It l l 22 also took a lot of staff effort. I am up here representing i 23 the work of a great many people who were involved in PRA and i 24 containment systems, and post-72-hour evaluation, and plant 25 systems, without whom this could not have been accomplished. ANN RILEY & ASSOCIATES, LTD. <\\, Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
484 1 This reprises everything really that was in ( 2 Terry's first couple of slides. This is the big issue. 3 What non-safety systems are sufficiently important that they 4 require regulatory control? This is all the stuff he did. 5 I wanted to point out down here that the SECY paper says, 6 once you identify these things, you also have to identify 7 what the appropriate regulatory control is, and it makes 8 some suggestions, without mandating anything. Tech specs, 9 maybe some kind of admin. control, something through the 10 maintenance role, inspection testing requirements, or 11 something else unspecified, or some combination of these 12 things. 13 DR. SEALE: There's one other point that I think 14 worthy of preserving that slide for other purposes, and that ( 15 is that it demonstrates that, for the really comprehensive 16 review of a topic like this, it includes both probabalistic 17 and deterministic determinations. l 18 MR. LEVIN: Absolutely. 19 DR. SEALE: And this is not an either/or process. 20 MR. LEVIN: No, it is not. 21 DR. SEALE: And it makes that point very 22 graphically there, and I think it is very helpful. 23 MR. LEVIN: Thank you. l 24 All right. Terry told you what Westinghouse d.4d. 1 25 The rest of this is going to be concentrated on what the ANN RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034 t
485 1 staff did. Post-72-hours was a separate evaluation. This g 2 was presented in SECY 96-128. The ACRS reviewed the staff's 3 position and supported it. And that was approved by the 4 Commission. So that was taken care of. But it was also 5 folded in as part of the RTNSS process. l 6 DR. KRESS: That was opposed to going down to the I l 7 Home Depot and writing it up. 8 MR. LEVIN: Right. Right. And flying them in. 9 Adverse systems interactions. The short answer is i 10 we didn't identify any systems for RTNSS treatment. That is 11 a very, very simple statement that overlays a great deal of 12 work that was done. We read the report, we asked i 13 Westinghouse lots of questions about various kinds of 14 systems interactions, 50 or 60 of then. at least. We had ) 15 lots of discussions about these kinds of things. 16 We also, since a lot of the adverse systems 17 interactions are based on, say, operator actions to isolate 18 systems as part of the EOPs, to ensure that there are no 19 systems interactions, we went into the EOPs. We did a 20 separate review of the EOPs to make sure that operator 21 actions that were specified in the ASI report were 22 appropriately reflected in the EOPs. We also did some 23 confirmatory testing in ROSA and in the Oregon State 24 University facility to look at the thermal-hydraulics 25 aspects of some of these interactions. So it was a very, l b ANN RILEY & ASSOCIATES, LTD. V Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
486 1 very comprehensive review. () 2 DR. CARROLL: Would Carl Michaelson agree with 3 you? 4 MR. LEVIN: I should hope so. 5 DR. CARROLL: All right. 6 MR. LEVIN: I don't want to speak for other people 7 though, especially Carl. 8 CHAIRMAN BARTON: Smart move. 9 MR. LEVIN: In the seismic, the station blackout, 10 and containment performance, the reactor vessel insulation 11 was picked up. Compliance with ATWS picked up diverse 12 actuation and its non-1E DC power and uninterruptable power 13 supply. Baseline frequency, initiating events involved 14 this. We picked up the ATWS and mid-loop issues identified (h 15 by Westinghouse and were accepted by us. 16 The other big part, and, again, as Terry 17 accurately represented, was the focus PRA evaluation. This 18 was the majority of work, really. 19 The thermal-hydraulic uncertainty, we decided 20 pretty early on that there wasn't really any way that we 21 could reasonably expect to try to quantify thermal-hydraulic 22 uncertainty. And so what we decided on was a margins 23 approach to try to figure out how much margin you had to 24 build into your analyses, let's say, to give you a comfort 25 zone that you would not exceed core damage criteria O ANN RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
l 487. 1 particularly. And this -- this was also difficult, but it () 2 was easier than trying to quantify things. 3 One thing that Terry didn't mention, and I wanted 4 to point out, is by SECY 94-084 Rules, these are the I-5 acceptance criteria, as he pointed out, but it also says -6 that once you apply RTNSS controls to a non-safety system, 7 you can go back and requantify your focus PRA and take 8 credit for that system in the focus PRA. So the focus PRA j 9 is at the first level, all non-safety systems go away. 10 Okay. But at the second level, not level 2, but at the 11-second stage, you can take credit for systems that have been l 12 credited, that have been taken under RTNSS. 23 DR. CARROLL: Has Westinghouse done that, or do 14 they plan to do it? () 15 MR. LEVIN: I'll let Westinghouse answer that. As 16 far as I know, they haven't. 17 MR. McINTYRE: No. We have not that done that, l 18 and we don't plan to. We -- our point is that we made it i 19 without those systems and adding those systems in would only 20 make it better, and it is a time and money issue. j 21 DR. CARROLL: Okay. I 22 MR. LEVIN: Westinghouse used the focus PRA to 23 identify risk-significance -- risk-significant high 24 consequence sequences. They did perform analyses using 25 NOTRUMP to demonstrate margin to core damage based on peak l i g ANN RILEY & ASSOCIATES, LTD. ] Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034 1 1
488 1 clad' temperature. We used the 2200 degrees F PCT as the () 21 core damage criterion. 3 Evaluation of other sequences beyond some of these 4 high consequence sequences were done with MAAP, with MAAP 4, 5 and that was benchmarked against NOTRUMP. We did an 6 evaluation of the benchmark report. Found MAAP and NOTRUMP 7 results were consistent in a lot cases. They.were not 8 consistent in some' cases. A lot of the disagreements were j 9 in timing of safety system actuation and that sort of thing. 10 And sometimes MAAP was earlier and sometimes MAAP was later. 11 They really -- it wasn't a systematic kind of discrepancy j 12 between the two codes. 13 DR. KRESS: Is MAAP for the EPRI version event? 14 MR. LEVIN: As far as I know, yeah. () 15 MR. McINTYRE: As far as I know, yes. 16 MR. LEVIN: What we really got into was a 17 protracted discussion, debate, if you want to, with 18 Westinghouse about assumptions and calculations that really 19 couldn't be ultimately resolved doing this. As I said, we 20 did do some confirmatory integral systems testing. 21 Professor DiMarzo told the Thermal-Hydraulics Subcommittee, 22 and there are some members of that Committee here, about 23 some of that earlier this week. 24 And really what it came down to at the end, the 25 controlling uncertainty, if you will, was adequate O-ANN RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
489 1 depressurization capability. If you can get enough valves ( ) 2 open, enough ADS valves open, there is enough redundancy in 3 the passive safety systems to give you pretty assurance that 4 you are going to get the passive systems to work the right 5 way. But there was a lot of evaluation of what exactly did 6 this comprise and were there scenarios that you could come 7 up with where there was a question about that. And this 8 also proceeded down into long-term cooling, once you got all 9 of the valves open and you had to rely on maintaining ADS-4, 10 enough ADS-4 capability open to allow some cooling to go on, 11 and valve reliability there as well. 12 And we just, we kept churning on these issues, and 13 the only resolution was to see if we could find a way to 14 identify a set of systems for RTNSS controls that would O) ( 15 provide a level of assurance in terms of thermal-hydraulic 16 capability and thermal-hydraulic uncertainty to resolve 17 these questions. And Westinghouse did finally agree in 18 principle to place several systems under RTNSS controls. 19 And I say in principle here, the debate then turned to, 20 well, how are we going to structure these controls? You 21 know, we don't want to make them tech specs, we want to make 22 them administrative controls. What's the best way to do it? 23 We agreed that satisfactory resolution of that 24 question would eliminate the need to spend a great deal of 25 staff resources in trying to get to the root of some of ANN RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034 L__.___
490 -1 these thermal-hydraulic uncertainty issues because.the 2: additional controls on these key non-safety systems would 3 reduce the importance of thermal-hydraulic uncertainty in j 4 passive systems performance. And I'll describe how that 5 works a.little bit on my next slide. 6 Westinghouse proposed using admin. controls. As 7 they have shown you, the controls are also exclusively tied 8 to the reliability assurance process and also the 9 maintenance rule implementation. And this has been reviewed 10 by the' staff as well to make sure there is consistency in 11 the broad sense all the way across the line here. Juid Terry 12 has gone through the various equipment that is captured in 13 that way. 14 DR. CARROLL: Let me ask a question, Alan. In the 15 evaluation of the reliability assurance process and the 16 maintenance rule, is the reliability assurance process i 17 necessary, or is it totally redundant to the maintenance l 18 rule implementation? 19 MR. LEVIN: Let me ask Rich Correia to address 20 that since he is the maintenance rule expert. 21 MR. CORREIA: This is Rich Correia of the staff. 22 If the design reliability assurance program is design and 23 constructed and implemented correctly, it will be. invisible 24 in maintenance rule space. The maintenance rule will just 25 be the extension, if you will, of RAP. O ANN RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 j (202) 842-0034 i l l
491 1 DR. CARROLL: Okay. Thanks. f~\\ 2 MR. LEVIN: J From the thermal-hydraulic uncertainty 3 point of view, particularly, RNS really got considered to be 4 the key system. It has got supporting systems as well in 5 various modes. You would need AC power to run it, 6 obviously. But its performance is really the key system 7 because it has the versatility to operate both as a backup 8 injection means for, say, post-LOCA. It will inject from 1 9 the IRWST at pressures around 200 psi and less. Which means l 10 if you can get some ADS-1, 2 and 3 valves open, even if 11 ADS-4 is completely ineffective, you can't open any of the 12 valves, if you can get this running, it will -- it can 13 successfully inject. And, in fact, this was tested in both 14 Westinghouse's design certification test program at SPES, C\\ () 15 and it was tested as part of the staff's confirmatory test 16 program as well. And RNS coming on at about 200 psi is an 17 effective way to cool the core. 18 The other thing is that it has the heat removal l 19 capability in shutdown to keep the plant cool. And I also 20 wanted to point out here that tech specs provide some 21 indirect operability controls here as well. There are 22 limiting conditions for operation in several tech specs that 23 specify that the capability to reach cold shutdown has to be 24 maintained, but it doesn't specify the system for doing 25 that, it just says capability. So it -- the RTNSS controls 1 [ ANN RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street, N.W., Suite 300 i l Washington, D.C. 20005 (202) 842-0034 l
492 1 are sort of more specific in that regard, and they () 2: complement the tech spec to a certain extent. 3 And the bottom line is that we have concluded that 4 the identified systems in the format of the RTNSS controls 5-provide additional assurance of plant safety and address the 6 staff's concerns. We don't have any open items in Chapter-7 22 as a result of that. 8 And that concludes what I had prepared. If you 19 have any questions. 10 CHAIRMAN BARTON: Thank you, Alan. 11 MR. LEVIN: Oh, sorry. 12 CHAIRMAN BARTON: I'm sorry. There's a question-j 13 for -- 14 DR. KRESS: Someone at the microphone. l 15 CHAIRMAN BARTON: Yes. We are -- 16 MR. SEBROSKY: This is Jerald Sebrosky of the 17 staff. 18. CHAIRMAN BARTON: The staff wants to address the 19 question that was raised yesterday regarding the leak before 20 ' break on feedwater, and I think it was Jay Carroll asked has 21 there been any experience in the industry on cracks, et 22 cetera. 'I think the staff has done some research and is l 23 prepared to address your question. I 24 DR. KRESS: I have a couple of clarification 25-questions on the RTNSE. Should we wait till after this to l I O ANN RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034 I
493 -1 ask those? [~j 2 CHAIRMAN BARTON: Yeah. This is only going to be %d 3 a couple of minutes, I believe. 4 MR. HOU: I am Shou-nien Hou, Senior Mechanical 5 Engineer, Civil Engineering in the Geo Sciences Branch, 6 Division of Engineering, NRR. 7 DR. CARROLL: Just like yesterday. 8 MR. HOU: Right. I am trying to respond to your 9 questions yesterday about pipe rupture in feedwater line 10 induced by water hammer. After talk with some people and 11 make some literature research, I found two -- four events. 12 Two is early one which occurs in the late '70s or early 13 '80s. I don't have the exact date. But Indian Point 2, I 14 think you are all familiar with. i (~) ( 15 DR. CARROLL: Refresh my memory. Was there a 16 piping failure associated with it? 17 MR. HOU: Yes. Pipe ruptures 180 degrees, Indian 18 Point 2, feedwater line. 19 DR. CARROLL: Align itself. 20 MR. HOU: Align itself. 21 DR. CARROLL: Okay. l 22 MR. SCHULZ: This is Terry Schulz at Westinghouse. 23 I know Indian Point had a significant or several significant 24 water hammers, but I don't believe that the leave was 25 actually attributed to them. It was attributed to corrosion i l [~T ANN RILEY & ASSOCIATES, LTD. \\ Court Reporters s-1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034 L
494 1 and thermal stress effects. [- 2 MR. HOU: The water hammer could cause by many A 3 elements. I am not here to discuss what is the cause, but 4 here just report event. 5 DR. CARROLL: Okty. Now, that is the same event 6 where they tore the penetration loose from the containment? 7 MR. SCHULZ: That event did not have the leak at 8 that time. 9 DR. CARROLL: Right. 10 MR. SCHULZ: The leak occurred later. I am not -- 11 DR. CARROLL: Okay. 12 MR. SCHULZ: I don't know that anybody can say 13 that there wasn't a relationship between the water hammers 14 and the leak, but the leak did not occur when that event 's,) 15 occurred. 1 16 DR. CARROLL: Okay. ] 17 MR. HOU: Now, another event is at Maine Yankee, 18 that also is a pipe rupture in feedwater line. Now, that is 19 an early event. 20 DR. CARROLL: And that was attributed to water 21 hammer? 22 MR. HOU: Attributed to water hammer. j 23 DR. CARROLL: Okay. 24 MR. HOU: Yeah. Now, more recently, the San 25 Onofre - actually, San Onofre, that's more than 10 years I ) ANN RILEY & ASSOCIATES, LTD. N/ Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
495 1 ago. The reason I still consider as more recently because 4 (f 2 in early '80s-NRC have unresolved safety issue task. They 3 ' focus on the water hammer event evaluation. And -- but even-4 after that, that still occurred in the San Onofre 1. But 5 this one I put it on and it is not really a impture, but it 6 is close to rupture. And there is intensive damage. What I 7 mean the damage is the plastic deformation of the pipe. 8 DR. CARROLL: Okay. 9 MR. HOU: And also the -- almost through wall, 10 crack, and also the' damage, the piping support very 11 severely. 12 DR. CARROLL: I'll bet. 13 MR. HOU: Yeah. Now, the one which I like 14 particularly to call your attention is the recent event, ) 15 Oconee 2. That's after we have this unresolved safety issue 16 resolution, and also the industry has to put a joint effort, 17 and so the EPRI and have a report very intensively to 18 investigate the mechanisms of the water hammer, what caused 19 that to occur, and also the mitigation measures. But that 20 still occur just last year, September '96. And that also 1 i 21 occur in a feedwater line, and this is 18 inches line, and j 22 it severely ruptured. l 23 DR. CARROLL: It actually ruptured? 24 MR. HOU: Actually ruptured. Yeah. 25 DR. CARROLL: Okay. It was attributable to only I "#D ANN RILEY & ASSOCIATES, LTD. l %I Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
i 496 1 water hammer. The line hadn't -- b[ T 2 MR. HOU: Water hammer, yeah. 3 DR. CARROLL: The line hadn't had wall thinning 4 due to corrosion or anything like that? 5 MR. HOU: Well, the thing is design and good 6 cleaning only can mitigate to certain degree. But design is 7 not only thing to prevent water hammer, and this one make 8 caused by operation error. 9 DR. CARROLL: Okay. I guess we learned yesterday l 10 that the difference between leak before break and not having 11 leak before break with regard to the AP600 is one humongous l 12 pipe support snubber wouldn't be needed if -- now, by having 13 that, you feel okay about water hammer potential? 14 MR. HOU: Well, the thing is water hammer is so 15 unpredictable. And a feedwater line, and historically, it 16 happens many times, and because the specific environment, 17 cold water meet hot water, these kind of things. And we 18 know Westinghouse have made a tremendous design improvement. j 19 But design not the only thing. The future operation error 20 and operation scheme, they all may contribute to water 21 hammer occurrence. We have to be cautious on these. 22 Especially the last event -- that really caught 23 our eye. I 24 DR. CARROLL: Okay. By any chance did the 25 committee review that event or did the operational -- O ANN RILEY & ASSOCIATES, LTD. 's l Court Reporters 1250 I Street, N.W., Suite 300 l Washington, D.C. 20005 (202) 842-0034 E__
497 l l 1 DR. KRESS: No. (' ) 2 CHAIRMAN BARTON: I remember reading the operating s_/ 3 experience but I don't know whether the committee actually 4 reviewed that in detail. 5 DR. CARROLL: Okay, thank you. l 6 DR. KRESS: Looks like we probably ought to. 7 DR. SEALE: Yes -- and I would kind of like to 8 know something pretty soon. l 9 Cculd you get a copy of the report on that, and 10 maybe get it out to us, Noel? 11 DR. CARROLL: I guess San Onofre wouldn't hurt 12 either. J 13 CHAIRMAN BARTON: Thank you. Tom -- you have got 14 some questions? ) 15 DR. KRESS: Yes. These are for the Staff on the 16 FSER and they are just clarification questions for my own 17 benefit. 18 On page 22.4, the top paragraph, it says that the 19 process of determining risk-significant nonsafety related l 20 features was on the basis of a Level 3 PRA and I just l 21 wondered if that is an adequate representation. 22 I thought it was a Level 2 at most. You know, I 23 was just wondering was that a typographical error or -- 24 DR. SEALE: You did more than we thought you did. 25 DR. KRESS: Yes. [~ ANN RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street, N.W.,. Suite 300 Washington, D.C. 20005 (202) 842-0034
498 -1 DR. SEALE: Well, remember, they said they did a 2 Level -- 3 DR. KRESS: They did a Level 3, butLit looked to 4 me like the RTNSS was based on something other than a Level 5 3. 6 MR. LEVIN: This is Al Levin. This was the -7 original EPRI work that's reflected -- it's a letter from 8 EPRI that is talked about here. I would have to go back and 9 see precisely what that letter says. 10 This material is sort of a historical basis on 11 RTNSS and I think it is taken out of the SECY paper. 12 DR. KRESS: Yes. I see the difference. Yes. 13 It's -- okay, that clarifies that. 14 On the next page, 22.5 and the paragraph under ) 15 Section 22.3.1, it talks about mean values must be used to 16 determine the availability of passive systems and 17 frequencies of core damage in large releases. 18 Just what does that mean? A mean is not very 19 useful without a distribution and I didn't see any 20 distributions on any of these. 21 I don't know exactly what that comment meant to 22 infer, so this is my statement. 23 MR. LEVIN: Our PRA people aren't here, so I am 24 not' a PRA expert. I'll address it as best I can. 25 The mean value is the point estimate using -- the O ANN RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
r 499 1 best estimate values of the availability. / 2 DR. KRESS: That's what I thought'it meant -- \\~)) 3 MR. LEVIN: But then it goes on to talk about 4 uncertainty analyses and sensitivity analyses to look at 5 your distribution. 6 DR. KRESS: Okay -- all my other questions on this 7 got answered during the presentations, I think. 8 There was one -- maybe I'll ask it. On page 22.6, l 9 the last paragraph, it was sort of'a cryptic statement. I 10 didn't know what it meant. 11 It says choose the systems by considering the 12 factors for optimizing the design effect and benefit of 13 particular systems. 14 I don't really know what that -- () 15 MR. LEVIN: Again, this is taken from EPRI and 16 this was the process that they defined. 17 MR. SCHULZ: This is Terry Schulz. I think I can 18 speak a little bit to that. 19 I think the implication there was that if you 20 wanted to add a nonsafety system to the RTNSS -- to the 21 focused PRA, you typically have choices. 22 You basically have a shortfall in some overall 23 safety goal and you want to reduce it and you have a 24 multitude of.nonsafety features that you could -- 25 DR. KRESS: I see. You could choose this one or O ANN RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
-=. 500 1 this one -- () 2 MR. SCHULZ: That's right, so I think what this is ~ 3 saying is that, you know, you should consider sort of the 4 . optimization of which' feature you add, how many. features you 5 add versus the benefits you get. 6 You had a little bit of that when I talked about 7 the adding of the DAS to compensate for DDI -- kind of 13(h) 8 uncertainties. It didn't directly compensate for it but-it 9 was a single feature that provided a fairly important or 10 significant benefit. 11 MR. LEVIN: And the Staff did some of this too -- 12 in review and consideration of various paths that you might 13 go down. 14 For instance, for backup on decay heat removal, ) 15 you could look at RNS. You could-look feedwater for the 16 steam generators, that sort of thing and sort of optimize 17 the system that you pick based on its flexibility, 18 capabilities, whatever. 19 DR. KRESS: Okay, thank you. I believe that's all 20 of them I had, Mr. Chairman. 21 CHAIRMAN BARTON: Thank you, Tom. 22 To kind of wrap up and summarize where we are, we 23 are winding down on the AP600 review and there is one more 24 subcommittee meeting in the middle of June, and at that time 25 we.are to review several FSER chapters that were not 1 O, ANN RILEY & ASSOCIATES, LTD. Court Reporters 1 1250 I Street, N.W., Suite 300 l Washington, D.C. 20005 (202) 842-0034 j
501 l' available when the SEER chapter was reviewed by the 2 subcommittee. 3 The ITAAC will be discussed in that subcommittee 4 as well as Level 1 PRA'and hopefully at that subcommittee'we 5 will close out all the open issues, questions that ACRS has 6 for. Westinghouse. 7 Speaking of open questions, was there anything 8 that came up today that might close out some of the Dudley 9 list?. 10 MR. McINTYRE: The one potential there is 4-1-98, 11 Jay Carroll question -- Westinghouse agreed to provide a 12 presentation on adverse systems interaction. '13 DR. CARROLL: From a curiosity point of view, I 14 guess I would like to hear more about it. l ()
- 15 -
I don't know if it worth the committee's time or 16 not. We just sort of said there was such a-program. 17 -Would others like to get a presentation? 4 18 DR. KRESS: Did we have Gus' review that WCAP? 19 MR. DUDLEY: I am not sure. I don't think so. I 20 can verify that. 21 DR. CARROLL: That would be a good point also, if 22 you did something like that. 23 DR. SEALE: I think Gus has got his hands full l l 24 right now, don't you think? 25 DR. POWERS: Yes, he is fairly busy. 1 ANN RILEY & ASSOCIATES, LTD. i Court Reporters l 1250 I Street, N.W., Suite 300 l Washington, D.C. 20005 (202) 842-0034 i
502 CHAIRMAN'BARTON: Well, what does the c.ommittee () 2 choose to do with this one? 3 DR. SEALE: An_ hour presentation or something? 4 DR. KRESS: I would say we ought to assign 5 individuals to look at that WCAP first and see if we have 6 enough. questions on it to -- l 7 MR. McINTYRE: We could pencil it in for -- 8 DR. SEALE: Yes. I 9 MR. DUDLEY: Who can I can get that WCAP from? 10 MR. McINTYRE: The only question I guess I had, 11 and I think we talked about this offline yesterday, was 12 where we were with the fire protection. 13 CHAIRMAN BARTON: I'll address that, Brian. 14 There will be an interim report that comes out o'. ) 15 this meeting plus your overview on June 3rd, so we do plan 16 to come out with a letter from the full committee at that 17 time. 18 It will address -- we did have a memo from Dana 19 Powers, who is Chair of the Fire Protection Subcommittee, 20 and they have completed their review of the fire protection 21 and there are no outstanding issues, from the memo I got 22 from Dana, so it looks like in this interim report we will 23 be able to close out the fire protection question. 24 MR. McINTYRE: Excellent. 25 DR. KRESS: There is another Thermal Hydraulics O ANN RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street, N.W., Suite 300 i Washington, D.C. 20005 (202) 842-0034 l l
-503 .1. Subcommittee meeting to try to close out the passive () 2 containment _ cooling -- all the. containment issues. 3 -DR. CARROLL: If that is possible. 4 CHAIRMAN BARTON: So this interim report will talk 5 about thermal hydraulics and the fact that there still are 6-several issues open. Tom will hopefully address those and 7' close those out in his subcommittee meeting. That is 8 scheduled for some' time in June? 9 MR. McINTYRE: June'11th and 12th. 10 CHAIRMAN BARTON: Okay. 11 MR. McINTYRE: And longer if necessary. 12 CHAIRMAN BARTON: Yes. 'Where that leaves us, I 13 think, is what do we want to cover in the June 3rd full j 14 committee meeting. () 15' I think we would request that you bring Mr. Schulz 16 -back. 17 I would like to canvass the committee to see what 18 particular issu Hs they would like to cover on June the 3rd. 19 As I go through the last three days, I am going to 20 take a stab at it, and if you don't agree with me, holler t 21 out. L 22 On' Chapter 6, engineered safety features, I think 23 what we need on that is an overview. 24' Chapter 14, initial test program, again a brief 25 overview. O ANN RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street' N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
504 1 The PRA Level 2 and 3, an overview -- () 2 DR. CARROLL: Didn't George have some specific 3 questions on that? 4 CHAIRMAN BARTON: I don't know if he had any from 5 George We got some from Rick Sherry, who reviewed that. 6 Did George agree with Sherry's comments? 7 MR. McINTYRE: George's questions, I think were l 8 Level 1, and we are -- l 9 CHAIRMAN BARTON: You are going to discuss I 10 those -- j 11 MR. McINTYRE: Yes, right. 12 CHAIRMAN BARTON: -- at the next subcommittee 13 meeting. 14 DR. CARROLL: Okay. ) 15 CHAIRMAN BARTON: So I think we just do an 16 overview on Level 2 and 3.. 17 MR. McINTYRE: Fine. 18 CHAIRMAN BARTON: On the severe accidents, an 19 overview, maybe some more discussion on in-vessel retention i 20 of core debris -- I'm sorry, which one? That is external -- 21 severe accidents and external events rate. 22 Chapter 3, design of structures and components -- 23 I say an overview on the structures and components but 24 concentrate on the containment design and the -- let's 25 see -- what would you want to hear on feedwater? [ ANN RILEY & ASSOCIATES, LTD. \\- Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
505 1 DR. SHACK: The LBB discussion. () 2 DR. SEALE: Yes. 3 CHAIRMAN BARTON: Leak Before Break, okay. 4 DR. SHACK: If Westinghouse has some comments on 5 experience -- I think we have heard the arguments about 6 magnitudes of water hammer. Any comments you might want to 7 make on what relevant experience has been and why you think 8 that your probabilities are much lower. 9 MR. McINTYRE: Okay, fine. 10 CHAIRMAN BARTON: Chapter 16, tech specs -- I'd 11 say just an overview. 12 DR. SEALE: Very brief. 13 CHAIRMAN BARTON: Yes, brief. I think what we 14 heard today on Chapter 17 and 22, I would do more than an I 15 overview. I think we'd get into some detail. 16 That is why I asked that Terry come back. I think 17 the members of the full committee that are not here for the 18 subcommittee meeting would be interested in the details of 19 Chapters 17 and 22. 20 DR. SEALE: Especially 22. 21 CHAIRMAN BARTON: Especially 22? Fine. 22 MR. McINTYRE: Mr. Schulz has informed me that he 23 will be in Italy that month. 24 We have -- 25 CHAIRMAN BARTON: You have a Schulz-2? O ANN RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
I 506 1 MR. McINTYRE: We have a Schul:-2. That would be 2 fine. 3. DR. SEALE: Is that t-o-o-? 4 MR. McINTYRE: T-o-o. 5 CHAIRMAN BARTON: That would be fine. Anything 6 else that I 7 DR. KRESS: I think as part of the Thermal 8 Hydraulics Subcommittee meeting, we requested Mike Young 9 give a presentation on how we address the various questions 10 on the primary coolant system and that would be part of the 11 same meeting, I think. 12 MR. McINTYRE: Yes, that is correct. ) 13 DR. KRESS: Ok5 14 DR. SEALE: you may be busy. 15 MR. McINTYRE: It's more than a two hour session. 16 DR. SEALE: One other thing, Mr. Chairman. 17 Noel passed around a draft based on preliminaries 1 18 of the letter and just scanning that, I think it is 19 important that everyone read that pretty carefully i 20 beforehand, and I indicated to you in just a scratch, but I l 21 would just mention to the other members of the committee if 22 we could work some comment into this letter to the effect of 23 Tom's remarks about this constituting an excellent example 24 of what risk-informed performance-based regulation -- j I 25 CHAIRMAN BARTON: This comment on Chapter 22? O ANN RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street, d.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
507 1 DR. SEALE: Yes -- on Chapter 22. I think that () 2 might be very helpful. 3 I would hate for that to get lost in the shuffle 4 because it really does hit the point. 5 DR. KRESS: It is interesting from the viewpoint 6 that that process was kind of put in place before we ever 7 got into this risk-informed performance-based -- 8 DR. SEALE: Yes. 9 CHAIRMAN BARTO'.. That is a good comment, Bob. 10 DR. CARROLL: Did Bob just volunteer to write 11 that? 12 DR. KRESS: I think he was volunteering me. 13 CHAIRMAN BARTON: He volunteered to suggest that 14 Tom write -- I 15 DR. SEALE: I'll write something on it. 16 CHAIRMAN BARTON: All right, so we will get some 17 comment on that for this letter. 18 Good point you brought up on the letter. Please 19 to look at it and feedback comments to Noel so that we can 20 have in place prior to the June 3rd meeting a pretty 21 detailed draft. 22 There are eight or nine letters on our plate 23 scheduled for the June meeting, so if we can kind of get 24 this one in pretty good shape, so we are not spending a lot 25 of time on it in the June meeting that would help us. O ANN RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
508 1 We also have got some more comments that goes in () 2 this -- got some comments from Dana this morning on the 3 in-vessel retention -- core debris -- that we will factor in 4 here, so we will get another draft of this out to all the 5 members in the next couple days. 6 Any other comments at this time? Questions, et 7 cetera? A motion to adjourn? 8 DR. CARROLL: I see Jim Lyons over there. He was 9 supposed to bring back a couple of answers to us. 10 One had to do with the status of the chilled water 11 system in the present version of the Standard Review Plan. 12 MR. LYONS: Actually, at the last subcommittee 13 meeting, I think you had left Ly then. Then I came back and 14 talked about that a little bit. ) 15 As part of the Standard Review Plan update we 16 provided that comment to the people that were working on the 17 Standard Review Plan and it was not incorporated basically 18 due to priorities and money because they truncated the 19 program but it is part of their documentation that that was 20 an issue that was raised, that we should look at the need 21 for an additional Standard Review Plan or inclusion in the 22 Standard Review Plan for chilled water systems, to look at 23 the refrigeration systems. 24 DR. CARROLL: -- the refrigeration system. l 25 MR. LYONS: Right. O ANN RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034
509 1 DR. CARROLL: Okay -- and were you going to tell () 2 me why you don't think generator rotor forge ends need to be 3 bored? 4 MR. LYONS: Actually, I did not get the answer to 5 that question. I will get that for you. 6 The materials people are the ones that look at 7 that and I will get them to answer that question. 8 DR. CARROLL: Okay, thank you. 9 CHAIRMAN BARTON: Any other questions, comments? 10 DR. SEALE: I think it's been a good week. 11 CHAIRMAN BARTON: Very good, Covered a lot of 12 good material. 13 Do I have a motion to adjourn the subcommittee? 14 DR. FONTANA: So move. ) 15 DR. SEALE: Second. 16 DR. KRESS: You don't have to have a motion for 17 that. 18 CHAIRMAN BARTON: I want to make sure all you guys 19 are happy before we leave here though. 20 DR. CARROLL: Hey -- no. That's not a good idea. 21 [ Laughter.] l 22 CHAIRMAN BARTON: We are adjourned. 23 [Whereupon, at 11:49 a.m., the meeting was 24 concluded.] 25 l l [N-ANN RILEY & ASSOCIATES, LTD. Court Reporters 1250 I Street, N.W., Suite 300 Washington, D.C. 20005 (202) 842-0034 (
REPORTER'S CERTIFICATE This is to certify that the attached proceedings before the United States Nuclear Regulatory Commission in the matter of: NAME OF PROCEEDING: SUBCOMMITTEE ON ADVANCED REACTOR DESIGNS CASE NUMBER: PLACE OF PROCEEDING: Rockville, MD were held as herein appears, and that this is the original transcript thereof for the file of the United States Nuclear Regulatory Commission taken by me and thereafter reduced to typewriting by me or under the direction of the court reporting company, and that the transcript is a true and accurate record of the foregoing proceedings. \\rrs\\ J)nHundley N Official Reporter Ann Riley & Associates, Ltd. L
O hcn d a n e r o c B i u t d s a n e lu ON S c i r n g TO N e r e e ei R G m ec N EI r OE S m n s o ogt i a ge T T E h n c I nGia r TD e E r e AI e &eR t l TMR a a 3 w cgnr 9 NMO nige 7 nia i n E O T a nl 2 r o eEc 5 S C h e u O E C y c nf 1 A eioN 4 r R B i E ue Mg f ) q n n o 1 r P U R u o S nt u rEie 0 o sc 3 p o i F D ou 8 il ( H nii FS i vvf t r 9 eiif E AR er 9 n SCDO C se 1 e O TC N nt i a 5 n N SA o E A pw 1 u L L REV sd y o T E e e a h RHD Rf I e M S T T NTA S S R R R E E E
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T T C N N N E E E E J E S S S B T E E E O U A R R R S D P P P
l3 O eru tp n ur o r ye rt iau qw nd ie Se F RC d ) O 5 e Ac 8 / o u 1 ) 2 6 t d / 9 en 1 / i 1 4 s ( n 2 e 2 re e s 1 / t t 9 opm n k n e ( n e r i 2 o a v o f sm e s P Y e n e a t R h n n e t e O n r e a n ne n o i e v d a c a c i t e n M e S O a r I r W e e i l r ra o E M O
O NRR STAFF PRESENTATION ACRS ADVANCED REACTOR DESIGNS SUBCOMMITTEE
SUBJECT:
REGULATORY TREATMENT OF NON-SAFETY SYSTEMS (RTNSS) DATE: MAY 15,1998 PRESENTER: ALAN E. LEVIN O SENIOR REACTOR ENGINEER REACTOR SYSTEMS BRANCH DIVISION OF SYSTEMS SAFETY AND ANALYSIS OFFICE OF NUCLEAR REACTOR REGULATION TEL. NO.: (301)415-2890 0
REGULATORY TREATMENT OF NON-SAFETY SYSTEMS j FUNDAMENTAL ISSUE l WHAT, IF ANY, NON-SAFETY SYSTEMS IN THE AP600 ARE SUFFICIENTLY IMPORTANT IN ENSURING PLANT SAFETY THAT THEY REQUIRE REGULATORY CONTROLS 7 RTNSS PROCESS DEFINED IN SECY-94-084 1 CONSISTS OF SEVERAL INDEPENDENT EVALUATIONS TO IDENTIFY RTNSS SYSTEMS PROBABILISTIC " FOCUSED" PRA (ASSUMPTION OF COMPLETE j UNAVAILABILITY OF NON-SAFETY SYSTEMS) - INITIATING EVENT FREQUENCY ASSESSMENT O DETERMINISTIC - PASSIVE SYSTEM THERMAL-HYDRAULIC RELIABILITY (PROVIDES INPUT TO FOCUSED PRA EVALUATION) - ADVERSE SYSTEM INTERACTIONS ASSESSMENT - POST-72-HOUR SUPPORT - ATWS - STATION BLACKOUT - SEISMIC EVALUATION - CONTAINMENT PERFORMANCE FOLLOWING IDENTIFICATION OF ANY SYSTEMS FOR CONSIDERATION UNDER RTNSS, STAFF MUST DETERMINE WHAT COMPRISE APPROPRIATE REGULATORY CONTROLS OVER SUCH SYSTEMS, E.G., - TECHNICAL SPECIFICATIONS - ADMINISTRATIVE CONTROLS - MAINTENANCE RULE - INSPECTION / TESTING REQUIREMENTS (E.G., IST PROGRAM) O - OTHER77 l 2 l
STAFF REVIEW OF RTNSS POST-72-HOUR EVALUATION DETERMINED NECESSARY EQUlPMENT SHOULD BE MAINTAINED ON-SITE: POSITION WAS PRESENTED IN SECY-96-128, REVIEWED BY ACRS, AND APPROVED BY COMMISSION ADVERSE SYSTEMS INTERACTIONS REPORT REVIEWED; NO SYSTEMS WERE IDENTIFIED FOR RTNSS TREATMENT SEISMIC / STATION BLACKOUT / CONTAINMENT PERFORMANCE GOALS RTNSS EVALUATIONS COMPLETED REAQTOR VESSEL INSULATION CREDITED IN POST-SEVERE-ACCIDENT EVALUATION NO OTHER SYSTEMS SPECIFICALLY IDENTIFIED FOR RTNSS CONTROLS COMPLIANCE WITH ATWS RULE REQUIRES RTNSS TREATMENT OF DIVERSE ACTUATION SYSTEM, NON-1E DC POWER AND UPS Q PRESERVATION OF BASELINE INITIATING EVENT FREQUENCIES DURING MID-LOOP OPERATION REQUIRES RTNSS CONTROLS ON OFFSITE/ONSITE AC POWER, DIESELS, RNS (NORMAL RHR), AND SUPPORT SYSTEMS (SERVICE WATER AND COMPONENT COOLING WATER) ATWS AND MIDLOOP ISSUES IDENTIFIED BY WESTINGHOUSE AND ACCEPTED BY STAFF FOCUSED PRA EVALUATION PERFORMED (OGETHER WITH PASSIVE SYSTEM RELIABILITY ASSESSMENT (THERMAL-HYDRAULIC UNCERTAINTY) EVALUATION OF THIS AREA CONSTITUTED THE MAJORITY OF THE STAFF'S RTNSS ASSESSMENT i T/H UNCERTAINTY EVALUATED USING " MARGINS" APPROACH RATHER THAN EXPLICIT QUANTIFICATION OF UNCERTAINTY ACCEPTANCE CRITERIA: FOCUSED PRA CDF LESS THAN 1E-4 AND LERF LESS THAN 1E-6; ANY SYSTEMS IDENTIFIED FOR RTNSS TREATMENT AS A RESULT OF THIS EVALUATION CAN BE CREDITED IN O FOCUSED PRA 3
9 8 FOCUSED PRA AND T/H UNCERTAINTY WESTINGHOUSE USED " FOCUSED" PRA TO IDENTIFY RISK-SIGNIFICANT, HIGH-CONSEQUENCE SEQUENCES ANALYSIS PERFORMED USING NOTRUMP TO DEMONSTRATE ADEQUATE MARGIN TO CORE DAMAGE (BASED ON PEAK CLAD TEMPERATURE) EVALUATION OF OTHER SEQUENCES TO ESTABLISH " SUCCESS" (NO CORE DAMAGE) PERFORMED WITH MAAP4, WHICH WAS BENCHMARKED AGAINST l NOTRUMP' STAFF ASSESSMENT RAISED SIGNIFICANT ISSUES REGARDING WESTINGHOUSE ASSUMPTIONS / CALCULATIONS THAT COULD NOT BE RESOLVED USING ABOVE METHODOLOGY STAFF EVALUATION INCLUDED CONFIRMATORY INTEGRAL SYSTEMS TESTING (ROSA AND OSU) AND ANALYSES ADEQUATE DEPRESSURIZATION CAPABILITY (AND RELATED UNCERTAINTIES) IDENTIFIED AS SINGLE MOST CRITICAL FACTOR IN ABILITY OF PLANT TO COPE WITH BEYOND-DESIGN-BASIS EVENTS O 4
RESOLUTION OF RTNSS ISSUE WESTINGHOUSE AGREED IN PRINCIPLE TO PLACE SEVERAL SYSTEMS UNDER RTNSS CONTROLS STAFF AGREED THAT THIS WOULD ELIMINATE THE NEED TO PERFORM AN IN-DEPTH ASSESSMENT OF THERMAL-HYDRAULIC UNCERTAINTY WESTINGHOUSE PROPOSED USING " ADMINISTRATIVE CONTROLS" TO SPECIFY NON-SAFETY SYSTEM AVAILABILITY AND RELIABILITY, FORMATTED SIMILAR TO TECHNICAL SPECIFICATIONS, BUT WITHOUT LIMITING CONDITIONS FOR OPERATION l CONTROLS ALSO TIED EXPLICITLY TO RELIABILITY ASSURANCE PROCESS AND MAINTENANCE RULE IMPLEMENTATION RTNSS APPLIED TO THE FOLLOWING SYSTEMS l DAS ATWS MITIGATION (MODE 1) DAS ESF ACTUATION IN ALL MODES i RNS INJECTION CAPABILITY (MODES 1,2,3) RNS DECAY HEAT REMOVAL (MODES 5,6) COMPONENT COOLING WATER AND SERVICE WATER TO SUPPORT RNS DECAY HEAT REMOVAL (MODES 5,6) HYDROGEN IGNITORS (MODES 1,2, 5,6) AC POWER (ALL MODES) NON-1E DC POWER FOR DAS (ALL MODES) POST-72-HOUR EQUIPMENT (PER SECY-96-128) O 5
RESOLUTION OF RTNSS ISSUE (CONT'D) RNS CONSIDERED TO BE THE " KEY" SYSTEM UNDER RTNSS: PROVIDES ALTERNATIVE MEANS OF DECAY HEAT REMOVAL, AND CAN BE ALIGNED TO PUMP WATER FROM IRWST TO RCS AT PRESSURES LESS THAN ABOUT 200 PSIA LATTER CAPABILITY MEANS THAT PLANT DOES NOT HAVE TO BE FULLY DEPRESSURlZED TO ESTABLISH IRWST INJECTION--PROVIDES BACKUP CAPABILITY IF ADS IS ONLY PARTIALLY SUCCESSFUL (E.G., INSU,FFICIENT NUMBER OF STAGE 4 VALVES) TECH SPECS ALSO INDIRECTLY PROVIDE OPERABILITY CONTROLS ON RNS AND ITS SUPPORT SYSTEMS--CAPABILITY TO REACH COLD SHUTDOWN MUST BE MAINTAINED (LCO 3.0.3, 3.5.4, 3.5.5), WITHOUT EXPLICIT SPECIFICATION OF SYSTEMS REQUIRED Q STAFF HAS CONCLUDED THAT IDENTIFIED SYSTEMS AND FORMAT OF RTNSS CONTROLS PROVIDE ADDITIONAL ASSURANCE OF PLANT SAFETY AND ADDRESS STAFF'S CONCERNS V O 6
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SSAR Table 17.4-1 (Sheet 1 of 10) RISK SIGNIFICANT SSCs WITHIN THE SCOPE OF D-RAP t2 System, Structure, or Rationale ) Insights and Assumptions Component (SSC)m System: Component Cooling Water (CCS) CCS Pumps EP nese pumps provide cooling of the normal residual heat removal system (RNS) and the spent fuel pool heat exchanger. Cooling the RNS heat exchanger is RTNSS-important during shutdown reduced-inventory conditions. CCS valve realignment is not required for reduced. inventory conditions. j System: Containment System (CNS) Containment Vessel EP,L2 ne containment vessel provides a bamer to steam and radioactivity released to the atmosphere following accidents. Hydrogen Igniters EP,L2, ne hydrogen igniters provide a means to control H 2 f Regulations concentration in the containment atmosphere, consistent with the hydrogen control requirements of 10 CFR 50.34f. System: Chemical and Volume Control System (CVS) CVS Makeup Pump Suction RAW nese CVS check valves are normally closed and have to and Discharge Check open to allow makeup pump operation. Valves CVS Makeup Pumps RAW /CCF nese pumps provide makeup to the RCS to accommodate leaks and to provide negative reactivity for shutdowns, steam line breaks, and ATWS. System Diverse Actuation System (DAS) Turbine Impulse Pressure RAW nese sensors provide signals used as permissives for the Transmitters 001 and 002 DAS automatic reactor mp function. Containment Isolanon EP,L2 These conuunment isolation valves are important in limiting Valves Controlled by DAS offsite releases following core melt accidents. f3 V Revision: 22 April 6,1998 17-16 W85tiflgh00$8
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Table 17.4-1 (Sheet 2 of 10) RI'iK SIGNIFICANT SSCs WITHIN THE SCOPE OF D RAP System. Structure, o - Rationale (2) Insights and Assumptions Component (SSC)(3 DAS Actuation Hardware RAW The DAS is diverse from the PMS and provides automanc (sensor input through actuauon of selected plant features including control rod control output and insertion, turbine trip passive residual heat removal (PRHR) indication) hea: exchanger actuation, core makeup tank actuation, isolation of critical contair. ment lines, and passive containment cooling system (PCS) actuation. Control Rod MG Set Field RAW These breakers open on a DAS reactor tnp signal demand Breakers to de-energize the control rod MG sets and allow the rods to drop. Distnbuuon Panels RAW These panels distnbute power to the DAS equipmerit. EDSI EA 14 and EDS2 EA 14 System Main ac Power System (ZCS) Ancillary Diesel Generators EP For post-72 hour actions, these generators are available to provide power for Class IE monitonng. MCR lighting and i for refilling the PCS water storage tank. System: Main and Startup Feedwater Sys.em (FWS) Startup Feedwater Pumps EP The stattup feedwater system pumps provide feedwater to the steam generator. This capability provides an alternate core cooling mechanism to the PRHR heat exchangers for non loss-of-coolant accidents or steam generator tube ruptures. System: GeneralI&C* Low Pressure /DP Sensors RAW /CCF The m containment refueling water storage tank (IRWST) - IRWST level ssnsors level sensors support PMS and DAS funcuons. They are uuhzed in automatic actuation and they provide mdications l to the operator. IRWST level supports IRWST recirculation l actions. 1 e Revision: 22 Y W8Silflgh0058 17 17 April 6,1998
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Table 17.4-1 (Sheet 3 of 10) l l RISK SIGNIFICANT SSCs %TTHIN THE SCOPE OF D RAP System, Structure, or Rationale (2) Insights and Assumptions Component (SSC)"3 High Pressure /DP Sensors RAW /CCF ne following sensors are included in this group. These - main feedwater flow sensors support PMS, DAS and PLS functions. ney are - startup feedwater flow unlized in reactor trip and ESF functions, and provide - pressurizer pressure indications to the operator. Main feedwater flow sensors and level support startup feedwater actuation and startup feedwater steam generator wide-flow sensors support PRHR actuation. The hot leg level and narrow-range level sensors automaucally actuate the IRWST and provide - RCS hot leg level and information to the operator for manual xtuauon of the steamline pressure automatic depressunzation system (ADS). System: Class IE DC Power and Uninterrupnble Power System (IDS) 125 Vdc Distnbunon Panels RAW nese panels distnbute power to componems in the plant that require IE de power support. 125 Vdc 24. hour Battenes. RAW /CCF ne batteries provide power for the PMS and safety-related Inserters, and Chargers valves. The chargens are the preferred source of power for Class lE de loads and are the source of charging for the battenes. The inverters provide uninterrupuble ac power to the ItC system. Fused Transfer Switch Box RAW ne fused disconnect switches connect the different levels of Class IE distnbution panels. 125 Vac Motor Control EP These buses provide power for the PMS and safety-related Centers valve operation. O Revision: 22 April 6,1998 17 18 W WestirighouS8
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Table 17.41 (Sheet 4 of 10) RISK SIGNIFICANT SSCs WITHIN THE SCOPE OF D RAP System. Structure, or Rationale (2) Insights and Assumptions Component (SSC)m Main Control Room (MCR) RAW /CCF Dis includes the Class IE PMS (QDPS) and DAS displays Displays and System Level and controls. It also includes the PLS displays and controls Control Mechanisms to associated with CVS reactor makeup. RNS reactor injection Support Operator Actions from the IRWST. spent fuel cooling, component cooling of RNS and SFS heat exchangers, service water cooling of CCS heat exchangers, standby diesel generators, and hydrogen igniters. These displays and system level control mechanisms provide important plant indications and variables to allow the operator to monitor and control the plant dunng normal conditions and during design basis accidents. Reactor Coolant Pump RAW /CCF nese breakers open automatically to allow core makeup Circuit Breakers tank operation. System: Passive Containment Cooling System (PCS) PCS Air-Operated Drain EP Dese valves apen automatically to drain water from a water Isolation Valves storage tank onto the outside surface of the contamment shell. This water provides evaporative cooling of the containment shell following accidents. PCS Water Storage Tank EP Dese pumps provide the motive force to refill the PCS Recirculation Pumps water storage tank dunng post-72 hour support actions. System: Plant Control System (PLSI PLS Actuation Hardware RAW /CCF Dis common cause failure event is assumed to disable all logic outputs from the PLS associated with CVS teactor makeup. RNS reactor injection from the IRWST. spent fuel cooling, component cooling of RNS SFS heat exchangers, service water coolmg of CCS heat exchangers, standby diesel generators and hydrogen igmters. PLS Logic Cabinet RAW /CCF This is the distnbuted controller that suppons the CVS Supporung CVS Functions funcuon. e Revision: 22 [ WeStingh00Se A ril 6,1998 P 17-19
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Table 17.41 (Sheet 5 of 10) RISK SIGNIFICANT SSCs %TTHIN THE SCOPE OF D RAP System Structure, or Rationalem Insights and Assumptions Component (SSC)W System: Protection and Safety Monitoring System (PMS) CMT Level Sensors RAW /CCF These level sensors provide input for automatic actuation of the ADS. ney also provide indicariou to the operator. PMS Actuation Software RAW /CCF He PMS software modules include field input signal l processing, control board signal input processing, actuation logic algonthms and output logic functions. Reactor Trip Switch Gear raw /CCF These breakers open automatically to allow insertion of the control rods. PMS Actuation Hardware RAW /CCF The PMS hardware includes the following: IPC Reactor Trip Subsystems IPC ESF Subsystems ESF Actuation Cabinets Protection Logic Cabinets Manual Input Multiplexer System: Passive Core Cooling System (PXS) Containment Recirculauon EP,L2 The cor.:ainment recirculauen hnes provide long term core Isolauon MOVs cooling following a loss-of-coolant accider.t (LOCA). The motor-operated valves open automatically to allow containment recirculation when the IRWST level is reduced to about the same level as the containment. The motor-operated valves also allow long-term core cooling to be provided by the RNS pumps. These valves together with the IRWST recirculation squib valves can provide a rapid flooding of the containment to support in vessel retention dunng a severe accident. O Revision: 22 April 6,1998 17 20 W Westinghouse 8
1
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Table 17.4-1 (Sheet 6 of 10) RISK-SIGNIFICANT SSCs WITHIN THE SCOPE OF D RAP System, Structure, or Rationale
- Insights and Assumptions Component (SSC)m IRWST Check Valves RAW /CCF The containment recirculation lines provide long. term core cooling following a LOCA. These check valves open when the IRWST level is reduced to approximately the same level as the containment level.
IRWST Injection Squib RAW /CCF ne IRWST injection lines provide long. term core cooling Valves following a LOCA. These squib valves open automatically to allow injection when the RCS pressure is reduced to below the IRWST injection head. IRWST Screens RAW /CCF The IRWST injecuon lines provide long-term core cooling following a LOCA. These screens are located inside the IRWST and prevent large particles from being injected into the RCS. ney are designed so that they will not become obstructed. e Containment Recirculation RAW /CCF The contamment recircuiauon lines provide long. term core Squib Valses cooling following a LOCA. These squib valves open automatically to allow containment recirculauon when the IRWST level is reduced to about the same level as the containment level. These squib valves can also allow long-term core cooling to be provided by the RNS pumps. These squib valves together with the containment recirculation motor-operated valves can provide a rapid flooding of the containment to suppon in. vessel retention during a severe accident. Containment Recirculauon RAW /CCF The containment recirculacon lines provide long.tenn core Screens cooling following a LOCA. The screens are located in the containment and prevent large particles from being injected into the RCS. They are designed so that they will not become obstructed. IRWST Gutter Bypus EP These valves direct water collected in the IRWST gutter to Isolation Valvas the IRWST. This capability extends PRHR heat exchanger operation. Accumulator Discharge RAW /CCF These check valves open when the RCS pressure drops Check Valves below the accumulator pressure to allow accumulator injection. Revision: 22 [ Westinghouse 8 17-21 April 6,1998
l l
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l Table 17.4-1 (Sheet 7 of 10) ) RISK SIGNIFICANT FSCs WTTHIN THE SCOPE OF D RAP i System, Structure, or Rationale
- Insights and Assumptions Component (SSC/D CMT Discharge Isolation RAW /CCF Hese air-operated valves automatically open to allow core Valves makeup tank injection.
CMT Discharge Check nese check valves are normally open. They close dunng Valves rapid accumulator injection. PRHR Heat Exchanger RAW /CCF The PRHR heat exchangers provide core cooling following Control Valves non-LOCAs, steam generator tube ruptures, and anticipated transients without scram. He air-operated valves automatically open to initiate PRHR heat exchanger operation. System: Reactor Coolant System (RCS) ADS Stages 1/2/3 EP,L2 The ADS provides a controlled depressunzation of the RCS O Motor Operated Valves following LOCAs to allow core cooling from the C accumulator, IRWST injecuon. and containment recirculation. The ADS provides " bleed" capability for feed / bleed cooling of the core. The ADS also provides depressurization of the RCS to prevent a high-pressure core melt sequence. ADS 4th Stage Squib RAW /CCF The ADS r.rovides a controlled depressurization of the RCS Valves following LOCAs to allow core cooling from the accumulator, IRWST inja: tion. and containment rectreulation. The ADS provides " bleed" capability for feed / bleed cooling of the core. The ADS also provides depressurizauon of the RCS to prevent a high pressure core melt sequence. Pressunzer Safety Valves EP These valves provide overpressure protection of the RCS. O Revision: 22 April 6,1998 17 22 W W6Stirigh00S8
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Table 17.41 (Sheet 8 of 10) RISK SIGNIFICANT SSCs WTITIIN THE SCOPE OF D-RAP System, Structure, or Rationale (2) Insights and Assumptions Component (SSC)U) Reactor Vesse! Insulation EP Tnese devices provide an engineered flow path to promote l Water Inlet and Steam Vent in-vessel retention of the core in a severe accident. I Devices l Reactor Cavity Doorway EP This device provides a flow path to promote in-vessel l Damper retention of the core in a severe accident. System: Normal Residual Heat Removal System (RNS) RNS Pumps EP These pumps provide shutdown cooling of the RCS. They also provide an alternate RCS lower pressure injection capability following actuation of the ADS. The operation of these pumps is RTNSS-important during shutdown reduced-inventory conditions. RNS valve realignment is not required for reduced-inventory conditions. RNS Motor Operated RRWiFVW These MOVs align a flowpath for nonsafety-related makeup Valves to the RCS following ADS operation. System: Spent Fuel Cooling System (SFS) SFS Pumps EP These pumps provide flow to the heat exchangers for removal of the design basis heat load. e Revision: 22 3 W85tiflgh00$8 17 23 April 6,1998
y se a= 1
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1 n o.a w 0 Table 17.4-1 (Sheet 9 of 10) i RISK SIGNIFICANT SSCs HTTHIN THE SCOPE OF D RAP l l System Structure, or Rationalem Insights and Assumptions ~ Component (SSC)* System: Steam Generator System (SGS) Main Steam Isolation RAW He steam generator main steam isolation valves provide Valves isolation of the steam generator following secondary line breaks and steam generator tube rupture. l 1 Main Steam Safety Valves EP ne steam generator main steam safety valves provide overpressure protection of the steam generator. They also provide core cooling by venting steam from the steam generator. System: Service Water System (SWS) 1 Service Water Pumps and EP These pumps and fans provide cooling of the CCS heat Cooling Tower Fans exchanger which is RTNSS-important during shutdown j q reduced-inventory conditions. Service water system valve ) realignment is not required for reduced inventory conditions. System: Nuclear Island Nonradioactive Ventilation System (VBS) VBS MCR and I&C Rooms EP For post-72 hour actions. these fans are available to provide B/C Ancillary Fans cooling of the MCR and the two !&C rooms (B/C) that i provide post accident monitonng. System: Chilled Water System (VWS) VWS Low Capacity RAW /CCF This VWS subsystem provides chilled cooling water to the Subsy stem CVS makeup pump room. The motor dnven pumps, chillers and unit cooler fans are important components of the VWS. System Onsite Standkv Power System (ZOS) Nonsafety relaasd Standby EP These diesels provide ac power to support operauon of Diesel Generators nonsafety related equipment such as the stattup feedwater pumps. CVS pumps. RNS pumps. CCS pumps. SWS pumps. and the PLS. Providing ac power to the RNS and the l equipment necessary to support its operation is RTNSS-important for reduced inventory conditions. Revision: 22 April 6,1998 17 24 W Westingh0058
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i Table 17.41 (Sheet 10 of 10) { RISK SIGNIFICANT SSCs WITHIN THE SCOPE OF D RAP I System, Structure, or Rationalem Insights and Assumptions Component (SSC)m Standby Diesels Room EP These fans provide cooling of the rooms containing the Cooling Fans standby diesel generators. Nuclear Fuel SMA The nuclear fuel includes the fuel pellets, fuel cladding, and associated support structures. This equipment, which provides a first barrier for release of radioactivity and allows for effective core cooling, had the least margin in the seismic margin analysis. Notes: 1. Only includes eqvipment at the component level. Other parts of the SSC or support systems are not included unless specifically listed. 2. Definition of Rationale Terms: CCF Common Cause Failure (for the SSCs whose inclusion rationale is RAW /CCF. the RAW is = based on common cause failure of two or more of the specified SSCs. EP Expert Panel = RAW = Risk Achievement Worth RRW Risk Reduction Worth = SMA Seismic Margin Analysis = 3. Maintenance / surveillance recommendations for equipments are documented in each appropnate SSAR 5ection. 4 This category captures instrumentauon and control equipment common cause failures across systems. I O Revision: 22 3 Westiflghouse 17 25 April 6,1998 a
me ts y S s d e r e y at 2t t uigm 2 e em f r a fao es S c b tpn r g o u n Si a o g t t n c e as hN i r e e8 en z RigM Cf l e9 u n9 h i s5 o g1 c n e S E 5 n oD Rt 1 1 An L s e y r ma eo3 Se T eM t t 1 t c t may Sm i sy e a t S mRM o 0 a Cd e 0 e r y c 6 T ro n s a P v vd Ary i d A A o ta luge 3 R 1 89 /2 / 5 SLT
sC SS t 65 s n 8 C a tr A3 sS o mS 1 s p s mP edCm mteA s eSi t eiC yt ASS sl t s4W et S y8 d r nN S0 n e -ytaT t i d4 at r R e o 0 l e9 t 0 ef apr r o aY6 s mf -y leCP ni t t nS REA eo n f r a S es y-S nN mn o et tenf n o t d o aT ai i f t s a s R e st e n r s r t o i nn n t r oe e a oym l p l mf r N mm od f i h o s e e e c S n af t f i r oip a e ol l u cSi ut i tnqm o nN s gn r eei pati e e s r d r m e pt R m r i t d s Ao er aeu py y s o f f en o S miioF t t h Si n n p r i f Teg N s ee or yd n T sd d P i r t oCs R eI I c taR e 0 c S uNW 0A l S g 6 e P N R A T R I
de tae f s e m sd e tn s ts s e m y C v e ) s S et 36 d s S g y e n s 0 t n 5 a d i t e ad o e l ei R t i r t t a t n a a F i l y e lel C u t i R er a e f y-m y-v 0 a ) e 1 s t t 2 ( e a e e f sf y 6 e ch a ac 0l ni t s h s n s u aw 5 r t n n n e i r s ms o o wou R e n r i N n q F nt oo A e wif oa n R yr aCot r t r i t e a bf c e c t r 0 papai ai P i d r n n e1 c r t eA e oei( au nt n t r s r t ot R ni v e r pi Pl aeClel oe n o t r i mC e g u ah mic l d si g c 2 n e c I r c eaint t i f sBMisS o7i si Si ar m ts t i Si u e anWs st t s s n vi Nil c i i t mT oood e b o i T aF n AL PCAS r Rb e I t o yr e S iP D f t S n e N d I TR
e m b k r r a a eyy l t e s// a s r i 46 y v n b sEE a o P y1 1 i Wod aC ni t tel l aa Fi t n iR f r aoo Mao e s gg r c is t n h e r e oCC py c v t i nRR w or l o s a NN r t s v fo s en e t ss nwe c c e vv v ci r s eo n pi u c u67 s s e i EE nr d r t ao e A m/ u T ad o 3. 8 r f RneS c r i t h 88 d u Pit nes gsWr t r wtoo o ed i sRuio t r y r f er 0 a r i t e0 b c u r aEE meqS w6 m s78 s l e/ vS ne p l CoPFiD ec o er pars gns g 6. 3 sR ts c eS a (A o s ai 23 ymr ah t y r r s o Ap yd o temm ef st t y pi dt r s a oo sgs nRoih f i l sf f n asinloiPf b m ny t r r l t un soCssisd lodisd yan t i ol t i t l e n eet nonxened ei i RaRs t a r e s e a caesia c vy i u uNaal nl ut t nl eeaisSS s c r nce o as e vbi NNi o e ea gt r r vt c c r t f c e u e nmenl it e e n n nRRnio a ei uAmFF n sb ss at u pr t i t i t i e ag i l t eH uvie e er es r aR DRvr ur oev/qeir t vP 0 n E 0CSeuTuL ciTESI t d6 gp p na t t c eP na a ul e its sA C C eR i t u a ic m i l i t b o o S aF n i S I S bor N P TR =
O Unavailatnlity of Cettorion 1 the associated Are nonsafetym SSCs consideredin nonsafety related the calculation of the irbtisting event SSCs is not hespaency? Important to the focused PRA Yes Unevallability of Cetterlon 2 the 6 Does the unevelletuitty of the nonsafety. N "'N related SSCs signifluently affect the h SSCs k not calculation of theinitiating event important to the m _ -. _ _ _. 9 ~' t m PnA Yes Unavestabinty of Crtterion 3 the associated Does the initiating event significantly nonemety related sHoct core damage frequency and large SSCa le not se frequency for the focused PRA important to the focused PRA Yes Identify nonsafetydated SSCs, proposed miselons, and proposed regulatory oversight. O Figure 31 Evaluation of Nonsafety related SSCs Impact on Initiating Event Frequency WCAP-13856 Revision: I oA3984w.l.wpf:I M 10598 120rw 3,g4
t e l n i n p o o ia m o l c tr o d e c n c m a n y r y e y t l u t t t n c H e g n ia i r n a t / i y r T d t o r e t n e c l g oi n t a d c n i t n n u l er a u o e y n l o b c t y y r c an nt t u in l b i l u ai i m a i a b t vH r e a/ et a n r r e i T c e l t e g e n c r o g r n aV s u n r I t e u n d o sD iH e y n/y h l t r er f uf ar l m iTi t r o o b p n i t t i o i s as a u y r e ee ef i q t l c n e e n t f t a a n or i s y r a s Ui t t t t n e n an o r r f e f e p ap ot e e u s c s c m f e n m n m eap yu i l n o n oo t pt i on c on c aF u n r sS q pi o u af i i t oSt oS n e ai a E st r N s nA e s t s a r r er n sR n nD pd o mnf yec o en e e; wni t t ph e oan n pee;mwl u a oio g mpl CSi apHi p p t t om m cd m owc c/ n o r t ee T Co a ea Tjc a e c t y x c s x d Ai n e n gg ncE eUE e ut n o t t r e sSS slod i i r iar d U AN i H/n o y S eD t i r n sDRTOcH I S c C n S N U S TR 1
O tca XH R H R n P o i d tn n e a te T r T le T ss R e )7 e g v 7 d n y n4 l i p 4 i i l v op f o po u o1 rp u c s t P roA e e y r h d d k r aa pCd e O c e r v l w e i h omio pWr i l u u u w c t r p s( t r n p p e ac n n p s s a o a t t n c h a l ae oic u o c w m i t y ct c s s s i C la i h or n t s aCnC e r R o wry oaau r s a ms eS oS p S r l l i t n S n sl Cc l r n nSiS t o S oCic& n oi a i yi y r A af V st et i S nI t r t t a D ecS a/e eR mfed e u a p eaia fa t s sS Ri st s l a s r st s n v e r n u eC C n n es n o r r y E e c o o uPMOe u s oCo u ut a nh l mt n t cr pl p pe c t al o2 a n i as oio a 7 sS C N C aCr N mN i i e nW s t t s s s n v i i S mT o o o d e P C A S A L r S e te N D - O T R
o c r e t t n o o r c p y d t i r l a i P b z A a a l R h a i D e v s v a C ,g a S n h m r S i t s e s t n n e C t t a S t r o m d 4 S o i h tc e o 1 t s nt p p n s sf y m a a e u v t s h r I Ct S n e S s c o a a p h ah S h m s 3 St t r N p C i t of S S npo T n Ca a n n R o Sh S S i sS c t r t r o r pC N ct i o o i i pSt f S n s Ti n r t r mS o t sS a n R ma c t o s r N p h et r t I o3 g nie i ST a sd n ot p p o s is api mRt SR e r ,m1 i r t mc c r N ci eeA ois ads r si Tf u vt i sS OyS pS e r n iqe e ys mS d s uiS R c CowN R i r r e NR rop f s y od vS TA Ah h T t n aS RS A2 gR l se n aa h N SIT 7i e nh o l l H us ot y gi yTh m t c s ss a eenR a o o i l seM R nOr E P S i n ib e Mf i er h e s u t S nD e oT O p S if o e r N D P T R = a
O ec e n lb a a n l i e a tn va ia S m o t n L de s O i nn n R a o l i T a p c t i r r n y N e os u t i t f ef l O i i r b s c d me s a eis C lo g d a ni l t r n n n c wal eo o v o t L n n i r ymin d at o e n i I t t O A C ec e s u eo3 t ml i l r e t p nh a c i V y c p b o 6 S ac mios r t s l t i 1 i A t t s a c eo c n n v n l i c ni b eh op r c a a oao l a pci pSdl M l l i a S et apm mtc i aaE n T c i D ad eer e v R A en oOs ei d es h if r c t k u n mu ot E m Tl mSMoe qt r ei R T k E e s oA r i r T ce o mD st r e t c ehsS e et T eelooOd a c d o c S n r t pmo eMlud u n r ao n R oS t c el ol f c l i h t v eni ruiD e s O S n i h od o d nI c n er v e e r pf q r s i H oe n t T ou e e u ai Dt mD R SB a S h cI cT u n t aO r o S oN S C t r S pp N A O TR
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- 16. Technical Specifications e
Table 16.3-1 i LIST OF INVESTMENT PROTECTION SHORT TERM AVAILABILITY CONTROLS Systems, Structures, Components Number MODES Trains (a) Operation (b) 1.0 Instrumentation Systems 1.1 DAS ATWS Mitigation 2 1 1.2 DAS ESF Actuation 2 1,2,3,4,5,6 (3) 2.0 Plant Systems 2.1 RNS 1 1,2,3 2.2 RNS - RCS Open 2 5,6 (2,3) 2.3 CCS - RCS Open 2 5,6 (2,3) 2.4 SWS - RCS Open 2 5,6 (2,3) 2.5 PCS Water Makeup - Long Term Shutdown i 1,2,3,4,5,6 (4) 2.6 MCR Cooling - Long Term Shutdown 1 1.2.3,4,5,6 2.7 I&C Room Cooling - Long Term Shutdown 1 1,2,3,4.5,6 2.8 Hydrogen Ignitors 1 1,2,5,6 (2,3) 3.0 Electrical Power Systems 3.1 AC Power Supplies 1 1,2,3,4.5 3.2 AC Power Supplies - RCS Open 2 (1) 5,6 (2,3) 3.3 AC Power Supplies.- Long Term Shutdown 1 1,2,3,4,5,6 3.4 DC Power Supplici-DAS 2 1,2,3,4,5,6 (3) AIDhs Notes: (a) Refers to the number of trains covered by the availability controls. (b) Refers to the MODES of plant operation where the availability controls apply. Notes: (1) 2 of 3 AC power supplies (2 standby diesel generators and I offsite power supply). (2) MODE 5 with RCS open. l (3) MODE 6 with upper internals in place or cavity level less than full. (4) MODES 5 and 6 with the calculated core decay heat greater than 6 MWt. Revision: 22 April 6,1998 16.3-4 Westingh00S8
- 16. Technical Specifications Table 16.3-2 (Cont.)
b INVESTMENT PROTECTION SHORT TERM AVAILABILITY CONTROLS 2.0 Plant Systems 2.1 Normal Residual Heat Removal System (RNS) OPERABILITY: One train of RNS injection should be operable APPLICABILITY: MODE 1, 2, 3 ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME A. One required train not A.1 Notify [ chief nuclear officer) or 72 hours operable. [on-call altemate]. AND 3 A.2 Restore one train to operable status 14 days %) l B. Required Action and B.1 Submit report to [ chief nuclear 1 day associated Completion officer) or [on-call alternate) Time not met. detailing interim compensatory measures, cause for inoperability, and schedule for restoration to OPERABLE. AND l l B.2 Document in plant records the 1 month justification for the actions taken to restore the function to l OPERABLE. .: :==. b) Revision: 22 3 Westinghouse 16.3-11 April 6,1998
l I6. Technical Specifications l Table 16.3 2 (Cont.) INVESTMENT PROTECTION SHORT TERM AVAILABILITY CONTROLS l SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY l SR 1.1.1.1 Verify that one RNS pump develops a differential head of 92 days [330) feet on recirculation flow l l l SR 1.1.1.2 Verify that the following valves stroke open 92 days { l RNS V011 RNS Discharge Cont. Isolation { RNS V022 RNS Suction Header Cont. Isolation ] RNS V023 RNS Suction from IRWST Isolation l l 1 t I ) Revision: 22 April 6,1998 16.3 12 3 WSStingh00S8
- 16. Technical Specifications Table 16.3-2 (Cont.)
p l 'Q INVESTMENT PROTECTION SHORT TERM AVAILABILITY CONTROLS 2 0 Plant Systems I l 2.1 RNS I BASES: The RNS injection function provides a nonsafety-related means of injecting IRWST water into the ) RCS following ADS actuations. The RNS injection function is important because it provides margin in the PRA sensitivity performed assuming no credit for nonsafety-related SSCs to mitigate at-power and shutdown events. The margin provided in the PRA study assumes a minimum availability of 90% for this function during the MODES of applicability, considering both maintenance unavailability i and failures to operate. One train of RNS injection includes one RNS pump and the line from the IRWST to the RCS. Three of the valves in the line between the IRWST and the RCS are normally closed and need to be opened l to allow injection. This equipment does not normally operate during MODES 1,2,3. Refer to SSAR section 5.4.7 for additional information on the RNS. l The RNS injection function should be available during MODES 1,2,3 because decay heat is higher l p and the need for ADS is greater. U Planned maintenance on redundant RNS SSCs should be performed during MODES 1,2,3. Such maintenance should be performed on an RNS SSC not required to be available. The bases for this recommendation is that the RNS is more risk important during shutdown MODES when it is normally operating than during other MODES when it only provides a backup to PXS injection. Planned maintenance on non-redundant RNS valves (such as V011, V022, V023) should be performed to minimize the impact on their RNS injection and their containment isolation capability. Non-pressure boundary maintenance should be performed during MODE 5 with a visible pressurizer level t or MODE 6 with the refueling cavity full. In these MODES, these valves need to be open but they do l not need to be able to close. Containment closure which is required in these MODES can be satisfied by one normally open operable valve. Pressure boundary maintenance can not be performed during MODES when the RNS is used to cool the core, therefore such maintenance should be performed during MODES 1,2,3. Since these valves are also containment isolation valves, maintenance that renders the valves inoperable requires that the containment isolation valve located in series with the l inoperable valve has to closed and de-activated. The bases for this recommendation is that the RNS is l more risk important during shutdown MODES when it is normally operating than during other MODES when it only provides a backup to PXS injection. In addition, it is not possible to perform pressure boundary maintenance of these valves during RNS operation. Revision: 22 [ Westingh0tlS8 16.3-13 April 6,1998 L___ __ _ _ _
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- 16. Technical Specifications g
Table 16.3-2 (Cont.) INVESTMENT PROTECTION SHORT TERM AVAILABILITY CONTROLS 2.0 Plant Systems 2.2 Normal Residual Heat Removal System (RNS) - RCS Open OPERABILITY: Both RNS pumps should be operable for RCS cooling APPLICABILITY: MODE 5 with RCS pressure boundary open, 1 MODE 6 with upper internals in place or cavity level less than full ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME I A. One pump not operable. A.1 Initiate actions to increase the 12 hours I water inventory above the core. I I AND G i l A.2 Remove plant from applicable 72 hours l MODES B. Required Action and B.1 Submit report to (chief nuclear I day associated Completion officer) or (on-call alternate] Time not met. detailing interim compensatory measures, cause for inoperability, and schedule for restoration to OPERABLE. AND B.2 Document in plant records the I month justification for the actions taken to restore the fonction to OPERABLE. Revision: 22 April 6,1998 16.3-14 W85tingh0USS 4
- 16. Technical Specifications Table 16.3-2 (Cont.)
INVESTMENT PROTECTION SHORT. TERM AVAILABILITY CONTROLS s SURVEILLANCE REQUIRILMENTS SURVEILLANCE FREQUENCY SR 2.2.1 Verify that one RNS pump is in operation and that each Within i day prior to RNS pump operating individually circulates reactor entering the MODES coolant at a flow > [900] gpm of, applicability OR Verify that both RNS pumps are in operation and circulating reactor coolant at a flow > (1800] gpm i r l Revision: 22 [ W85tingt100$e 16.3 15 April 6,1998 ( i l
- 16. Technical Specifications Table 16.3-2 (Cont.)
INVESD1ENT PROTECTION SHORT TERM AVAILABILITY CONTROLS 2.0 Plant Systems 2.2 RNS - RCS Open BASES: The RNS cooling function provides a nonsafety-related means to nonnally cool the RCS during shutdown operations (MODES 4,5,6). This RNS cooling function is important during conditions when the RCS pressure boundary is open and the refueling cavity is not flooded because it reduces the probability of an initiating event due to loss of RNS cooling and because it provides margin in the PRA sensitivity performed assuming no credit for nonsafety-related SSCs to mitigate at-power and I shutdown events. De RCS is considered open when its pressure boundary is not intact. The RCS is also considered open if there is no visible level in the pressurizer. He margin provided in the PRA study assumes a minimum availability of 90% for this function during the MODES of applicability, considering both maintenance unavailability and failures to operate. The RNS cooling of the RCS involves the RNS suction line from the RCS HL, the two RNS pumps and the RNS discharge line retuming to the RCS through the DVI lines. The valves located in these lines should be open prior to the plant entering reduced inventory conditions. One of the RNS pumps g has to be operating; the other pump may be operating or may be in standby. Standby includes the capability of being able to be placed into operation from the main control room. Refer to SSAR section 5.4.7 for additional information on the RNS. Both RNS pumps should be available during the MODES of applicability when the loss of RNS cooling is risk important. If both RNS pumps are not available, the plant should not enter these conditions. If the plant has entered reduced inventory conditions, then the plant should take action to i restore full system operation or leave the MODES of applicability. If the plant has not restored full I system operation or left the MODES of applicability within 12 hours, then actions need to be initiated I to increase the RCS water level to either 20% pressurizer level or to a full refueling cavity. Planned maintenance affecting this RNS cooling function should be performed in MODES 1,2,3 when the PRS is not normally operating. The bases for this recommendation is that the RNS is more risk imporW.t during shutdown MODES, especially during the MODES of applicability conditions than during other MODES when it only provides a backup to PXS injection. O Revision: 22 April 6,1998 16.3-16 [ W85tingh0058 >}}