ML19184A162
| ML19184A162 | |
| Person / Time | |
|---|---|
| Issue date: | 05/16/2019 |
| From: | Michael Snodderly Advisory Committee on Reactor Safeguards |
| To: | |
| Snodderly, M, ACRS | |
| References | |
| NRC-0328 | |
| Download: ML19184A162 (401) | |
Text
Official Transcript of Proceedings NUCLEAR REGULATORY COMMISSION
Title:
Advisory Committee on Reactor Safeguards NuScale Subcommittee Docket Number: (n/a)
Location: Rockville, Maryland Date: Thursday, May 16, 2019 Work Order No.: NRC-0328 Pages 1-263 NEAL R. GROSS AND CO., INC.
Court Reporters and Transcribers 1323 Rhode Island Avenue, N.W.
Washington, D.C. 20005 (202) 234-4433
1 1
2 3
4 DISCLAIMER 5
6 7 UNITED STATES NUCLEAR REGULATORY COMMISSIONS 8 ADVISORY COMMITTEE ON REACTOR SAFEGUARDS 9
10 11 The contents of this transcript of the 12 proceeding of the United States Nuclear Regulatory 13 Commission Advisory Committee on Reactor Safeguards, 14 as reported herein, is a record of the discussions 15 recorded at the meeting.
16 17 This transcript has not been reviewed, 18 corrected, and edited, and it may contain 19 inaccuracies.
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1 1 UNITED STATES OF AMERICA 2 NUCLEAR REGULATORY COMMISSION 3 + + + + +
4 ADVISORY COMMITTEE ON REACTOR SAFEGUARDS 5 (ACRS) 6 + + + + +
7 NuSCALE SUBCOMMITTEE 8 + + + + +
9 THURSDAY 10 MAY 16, 2019 11 + + + + +
12 ROCKVILLE, MARYLAND 13 + + + + +
14 The Subcommittee met at the Nuclear 15 Regulatory Commission, Two White Flint North, Room 16 T2D10, 11545 Rockville Pike, at 8:30 a.m., Gordon R.
17 Skillman and Michael L. Corradini, Co-Chairs, 18 presiding.
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2 1 COMMITTEE MEMBERS:
2 MICHAEL L. CORRADINI, Co-Chair 3 GORDON R. SKILLMAN, Co-Chair 4 RONALD G. BALLINGER, Member 5 DENNIS BLEY, Member 6 CHARLES H. BROWN, JR. Member 7 VESNA B. DIMITRIJEVIC, Member 8 JOY L. REMPE, Member 9 MATTHEW W. SUNSERI, Member 10 11 ACRS CONSULTANT:
12 STEPHEN SCHULTZ 13 14 DESIGNATED FEDERAL OFFICIAL:
15 MIKE SNODDERLY 16 17 18 19 20 21 22 23 24 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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3 1 C-O-N-T-E-N-T-S 2 Opening Remarks . . . . . . . . . . . . . . . . . 4 3 Chapter 14, "Initial Test Program and 4 Inspections, Tests, Analyses, and Acceptance 5 Criteria," DCA . . . . . . . . . . . . . . . . . 7 6 Chapter 14, "Initial Test Program 7 and Inspections, Tests, Analyses, 8 and Acceptance Criteria," SE with 9 Open Items . . . . . . . . . . . . . . . . . . . 62 10 Opportunity for Public Comments . . . . . . . . 111 11 Chapter 3.9.2, "Dynamic Testing and Analysis 12 of Systems, Components, and Equipment," DCA . . 112 13 Chapter 3.9.2 "Dynamic Testing and Analysis 14 of Systems," DCA - . . . . . . . . . . . . . . 168 15 Subcommittee Discussion . . . . . . . . . . . . 259 16 Adjourn . . . . . . . . . . . . . . . . . . . . 263 17 18 19 20 21 22 23 24 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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4 1 P-R-O-C-E-E-D-I-N-G-S 2 8:29 a.m.
3 CO-CHAIR SKILLMAN: Ladies and gentlemen, 4 good morning. This meeting will come to order.
5 This is a meeting of the Advisory 6 Committee on Reactor Safeguards, NuScale Subcommittee.
7 I'm Gordon Skillman, Co-Chairman for today's 8 subcommittee meeting along with Mike Corradini.
9 Members in attendance today are Dr. Michael Corradini, 10 Dr. Joy Rempe, Dr. Vesna Dimitrijevic, our esteemed 11 Mr. Charlie Brown, Matt Sunseri, our Vice Chairman, 12 and Dr. Ron Ballinger. We have our consultant Dr.
13 Stephen Schultz with us, too. Mike Snodderly is the 14 designated federal official for this meeting.
15 The Subcommittee will review the staff's 16 evaluation of Chapter 14, Initial Test Program and 17 Inspections, Tests, Analyses, and Acceptance Criteria, 18 and Chapter 3.9.2, Dynamic Testing and Analysis of 19 Systems, Components, and Equipment of the NuScale 20 Design Certification Application.
21 Today we have members of the NRC staff and 22 NuScale to brief the Subcommittee.
23 I will say in opening that if we are swift 24 in moving through Chapter 14 ITAAC, we will move 25 directly into 3.92 to conserve time and resources.
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5 1 The ACRS was established by statute and is 2 governed by the Federal Advisory Committee Act, FACA.
3 This means that the Committee can only speak through 4 its published letter reports. We hold meetings to 5 gather information to support our deliberations.
6 Interested parties who wish to provide comments can 7 register -- can contact our office requesting time 8 after the meeting announcement is published in the 9 Federal Register. That said, we set aside 10 minutes 10 for comments from members of the public or those 11 listening our meetings. Written comments are also 12 welcome.
13 Important at this point is the comments 14 today represent the comments of individual members, 15 not the ACRS. And the point of this paragraph is that 16 we speak only through our letter reports that come 17 from our Full Committee meetings. So comments today 18 are from individual members.
19 The ACRS section of the U.S. NRC public 20 web site provides our charter, bylaws, letter reports 21 and full transcripts of all Full and Subcommittee 22 meetings including slides presented there.
23 The rules for participation in today's 24 meeting were announced in the Federal Register on May 25 6th, 2019. The meeting was announced as an NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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6 1 open/closed meeting. We may close the meeting after 2 the open portion to discuss proprietary material.
3 Presenters can defer questions that should not be 4 answered in the public session at that time.
5 No written statement or request for making 6 an oral statement to the Subcommittee has been 7 received from the public concerning this meeting.
8 A transcript of the meeting is being kept 9 and will be made available as stated in the Federal 10 Register notice. Therefore, we request that 11 participants in this meeting use the microphones 12 located throughout the meeting room when addressing 13 the Subcommittee. We ask that the participants first 14 identify themselves and speak with sufficient clarity 15 and volume so that they can be readily heard.
16 For those in the meeting room, we ask that 17 you please silence your electronic devices.
18 We have a bridge line established for the 19 public to listen to the meeting. To minimize 20 disturbance the public line will be kept in a listen-21 in mode. To avoid disturbance again I request that 22 all attendees put their electronic devices in the 23 noise-free mode.
24 We will now proceed with the meeting and 25 I'll call on Zach Rad, Director of Licensing of NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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7 1 NuScale, to begin today's presentation.
2 Sir?
3 MR. RAD: Thank you. Carrie's going to --
4 Carrie Fosaaen is going to provide introductions to 5 this presentation.
6 MS. FOSAAEN: Thanks.
7 Good morning. Carrie Fosaaen, NuScale 8 Licensing Supervisor, for Chapter 14. Today we've got 9 Chris Maxwell and Edan Engstrom who will be presenting 10 an overview of our Chapter 14, which is Initial Test 11 Program and ITAAC.
12 Chris?
13 MR. MAXWELL: Good morning. Chapter 14 14 consists of three sections: Section 14.1 contains --
15 CO-CHAIR SKILLMAN: Chris, would you make 16 sure your green light is on?
17 MR. MAXWELL: Both?
18 CO-CHAIR SKILLMAN: Okay. You got stereo.
19 There you go. Thank you, sir.
20 MR. MAXWELL: Yes sir.
21 CO-CHAIR SKILLMAN: Thank you.
22 MR. MAXWELL: So Chapter 14 has three 23 sections: Section 14.1 contains specific information 24 that's to be addressed in the Initial Plant Test 25 Program, Section 14.2 is the Initial Plant Test NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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8 1 Program, and Section 14.3 is the certified design 2 material inspections test analysis and acceptance 3 criteria.
4 CO-CHAIR SKILLMAN: May I make a comment 5 here?
6 MR. MAXWELL: Yes sir.
7 CO-CHAIR SKILLMAN: For 14.3 what I'm 8 going to request is not specifically identified in 9 your slides, but I would like to communicate what we 10 as a committee are interested in.
11 We're interested in the organization of 12 ITAAC. There is Tier 1 ITAAC and Tier 2 ITAAC. And 13 we understand that Tier 1 ITAAC would be material that 14 a future COLA applicant would require use of a 15 departure to change. In other words, Tier 1 is locked 16 in a license changed only by departure and Tier 2 is 17 the governing detail for that particular ITAAC. So 18 there are really two tiers that we're talking about in 19 your application. So we'd like to through this 20 discussion perhaps hear the distinction between those 21 two if that's relevant to what you may be presenting.
22 We're also interested in the different 23 types of ITAAC. There are apparently seven different 24 types of ITAAC. There's as-built analysis, as-built 25 inspection, design acceptance criteria, design NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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9 1 analysis, equipment qualification ITAAC, pre-2 operational test ITAAC, and vendor test ITAAC. We 3 know you can't address all of those now, but to the 4 extent that that discussion may be relevant we'd like 5 to hear about that.
6 MR. MAXWELL: Yes sir.
7 CO-CHAIR SKILLMAN: We also would like to 8 hear about overall accountability. This is a massive 9 application; multiple systems, only a few of very high 10 safety significance. How is the entire application 11 combed to ensure that all ITAAC are accounted for?
12 When one reviews the ITAAC Tier 1 and Tier 2, the 13 ITAAC are in table after table after table leading to 14 the question how do you know that's thorough and what 15 controls are on those data bases to ensure everything 16 that needs to be identified has been identified? And 17 then further, how closeout is going to occur.
18 MR. MAXWELL: Yes sir.
19 CO-CHAIR SKILLMAN: Finally, how is ITAAC 20 accounted for as the design matures? As we saw in the 21 CDF curve yesterday, the CDF has been consistently 22 decreasing by the improvements that have been made in 23 this application. Our sense is the drivers for that 24 reduction in CDF are probably accounted for somewhere 25 down in the design and those items probably rise to NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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10 1 the ITAAC level. How are changes in ITAAC accounted 2 for as the design continues to mature?
3 MR. MAXWELL: Understood.
4 CO-CHAIR SKILLMAN: I's a lot of words, 5 but it really comes down to recordkeeping, 6 accountability, your QA Program oversight on ITAAC and 7 ensuring that when the application is finally ready 8 for approval that the deck is complete.
9 MR. MAXWELL: Yes sir.
10 CO-CHAIR SKILLMAN: With that, proceed.
11 Thank you.
12 MR. MAXWELL: And I'll do my best to 13 address each of those as I go through this where 14 there's an appropriate location to discuss them, but 15 please feel to remind me of any that I fail to discuss 16 as we go through it.
17 CO-CHAIR SKILLMAN: Yes sir. Thank you.
18 MR. MAXWELL: Because Section 14.1 is 19 essentially a list of documents, we'll jump right into 20 Section 14.2, the Initial Test Program.
21 The Initial Test Program consists of three 22 major categories of testing: The first is pre-23 operational testing, startup testing and then first-24 of-a-kind testing. Startup testing can be further 25 broken down into initial fuel loading and pre-critical NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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11 1 testing, initial criticality testing, low-power 2 testing and power-ascension testing.
3 Guidance for the contents of the Initial 4 Test Program come from Regulatory Guide 1.68, and Reg 5 Guide -- regarding pre-operational testing 6 specifically, Reg. Guide 1.68 states that pre-7 operational testing consists of those tests conducted 8 following completion of construction, inspections and 9 tests, but before fuel loading to demonstrate to the 10 extent practical the capability of SSCs to perform the 11 performance requirements to satisfy the design 12 certification.
13 Also in Reg Guide 1.68, Appendix Alpha, 14 there's a list of systems and attributes for each of 15 those systems to be verified or demonstrated during 16 conduct of the pre-operational testing.
17 So NuScale evaluated each of those systems 18 and their attributes for applicability to the NuScale 19 design and incorporated them into our pre-operational 20 testing where appropriate, however, we recognize that 21 the time that Reg Guide 1.68 was written they couldn't 22 anticipate all of the design features and system 23 attributes that would be included in the NuScale 24 design. So we wanted to -- we sought after a method 25 to identify all the functionality to be tested to NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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12 1 ensure that we adequately demonstrated the design.
2 The answer came to us in the Design 3 Reliability Assurance Program, or D-RAP. D-RAP is 4 described in Chapter 17.4, but what D-RAP does for us 5 is it provides a list of all the inter-system 6 functions for each system and then describes those 7 functions in a support-system-to-supported-system 8 relationship, and then finally classifies the risk and 9 safety significance for each of those functions.
10 So what we did was then we took each of 11 those functions and we asked the question is this 12 function testable? And if the answer was yes, we 13 first tried to align it with ITAAC testing 14 requirements. So one of the aspects of ITAAC that you 15 mentioned as there's pre-operational testing.
16 I'm going to step out just a second and 17 kind of go into ITAAC for a second to say that it's 18 not prescribed whether it be an analysis or a pre-19 operational test or equipment qualification test to 20 satisfy the ITAAC, but rather you first identify the 21 design commitment and then identify the appropriate 22 inspection test or analysis to be conducted to 23 demonstrate that you do meet that design commitment.
24 When it's testing sometimes it will line up with pre-25 operational testing.
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13 1 If I need to as part of a design 2 commitment verify that my containment isolation valves 3 stroke closed within a specific time, well, I'm also 4 going to do that as a part of pre-operational testing.
5 So we'll record it in both programs, in both the 6 Initial Test Program and as part of ITAAC, but perform 7 the test once.
8 CO-CHAIR SKILLMAN: Would you go back a 9 slide, please?
10 MR. MAXWELL: Yes sir.
11 CO-CHAIR SKILLMAN: At your first -- the 12 second carat, Reg Guide 168, Pre-operational Testing, 13 for the record as you receive a module -- or let me 14 say it differently. You've got a module that's, if 15 you will, ready for sign off at your manufacturing 16 facility, wherever that might be. My presumption is 17 at that point, that vendor has conducted a series of 18 tests particularly related to ASME and pressure 19 testing and that type of thing. That vendor might 20 have done some additional testing that is the cousin 21 of, the brother or sister of, or the same as what you 22 would insist be completed as part of your pre-23 operational testing.
24 So my question is, where in the supply 25 chain would a vendor conduct tests that satisfy ITAAC?
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14 1 And when that module is in its operating location for 2 its pre-operational test, does the -- or conducted at 3 the manufacturer or waived because they have been 4 conducted at a prior time?
5 MR. MAXWELL: We identify some tests that 6 can be satisfied by the vendor to -- and those tests 7 will demonstrate ITAAC. When it comes to pre-8 operational testing, it's a very limited scope because 9 the purpose of pre-operational testing is to 10 demonstrate really the adequacy of the construction.
11 So there's some factory acceptance testing in the 12 module protection system for instance that will credit 13 for both ITAAC and as a prerequisite to be completed 14 to commencing the pre-operational testing. But that 15 is identified in the pre-operational -- in the initial 16 test program.
17 So it's not a matter of waiving pre-18 operational testing. It's still -- you still conduct 19 all the pre-operational testing. But again, that 20 testing --
21 CO-CHAIR SKILLMAN: Do those records 22 accompany that module?
23 MR. MAXWELL: Yes sir.
24 CO-CHAIR SKILLMAN: Are those records 25 protected under your QA program or your vendor's QA NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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15 1 program?
2 MR. MAXWELL: They'll be the licensee's QA 3 program.
4 CO-CHAIR SKILLMAN: So there will be a 5 chain of custody for those records for that module?
6 MR. MAXWELL: Yes, there will be.
7 CO-CHAIR SKILLMAN: Yes sir. Okay. Thank 8 you.
9 MR. MAXWELL: And kind of going into 10 another question you mentioned was about the closure 11 of that ITAAC. So if I have an ITAAC again for the 12 module protection system or we'll go back to the 13 module itself. If I've got an ASME inspection that's 14 required and it's an ITAAC for the valve, that could 15 be conducted at the manufacturer's location. All the 16 closure paperwork for the ITAAC could be identified 17 and an ITAAC closure notification could be submitted 18 to the NRC to close that ITAAC prior to the module 19 arriving on site.
20 CO-CHAIR SKILLMAN: Okay. Thank you.
21 MR. MAXWELL: Yes sir. So again, when 22 possible, we align pre-operational testing with ITAAC.
23 Then we add those functions. Those testable functions 24 are added to the initial test program and we develop 25 component-level or system-level tests for those NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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16 1 functions as appropriate, again, to demonstrate the 2 ability of the SSC -- the capability of the SSC to 3 meet the performance requirements to satisfy the 4 design criteria.
5 So I'd like to use an example here. This 6 is a D-RAP function that's identified in Chapter 17 7 associated with a reactor building crane.
8 CO-CHAIR SKILLMAN: Just a minute. Would 9 you go back a slide, please. What you have here on 10 the red, orange, yellow, and green, was that 50.69, 11 the four boxes? Is that what that is?
12 MR. MAXWELL: I can't speak to that. It's 13 the D-RAP designation.
14 CO-CHAIR SKILLMAN: I was just curious.
15 I believe that that's what that is. Red is supposed 16 to be, hey, people, this one is really, really 17 important. Orange is kind of important but not as 18 important as red. Yellow is, eh, and green is, don't 19 worry about it. Is that what we're looking at here?
20 MR. MAXWELL: I would not assign that to 21 those colors necessarily, that they have that amount 22 of weight. But rather just to differentiate between 23 safety significant -- I'm sorry, safety related and 24 risk significance.
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17 1 getting at is, is the level of testing change with the 2 -- that's what I thought you were going with it.
3 CO-CHAIR SKILLMAN: Go ahead.
4 CO-CHAIR CORRADINI: But my impression is 5 all of these are just categorized, and then you have 6 to decide what you want to test to demonstrate 7 function below.
8 MR. MAXWELL: Right. What I would say is 9 that with the safety related and risk significant 10 functions, those functions have ITAAC associated with 11 them. The non-safety related, non-risk significant 12 functions may or may not have ITAAC associated with 13 them. However, if the function is testable, it's 14 tested as part of the initial test program. There's 15 no distinction made as far as pre-operational testing 16 but there is for ITAAC.
17 CO-CHAIR SKILLMAN: Are all the reds Tier 18 1?
19 MR. MAXWELL: Every safety related 20 testable -- safety related will be found as an ITAAC.
21 CO-CHAIR CORRADINI: In Tier 1?
22 MR. MAXWELL: That's correct, in Tier 1 --
23 ITAAC for Tier 1.
24 CO-CHAIR SKILLMAN: Thank you.
25 MR. MAXWELL: Yes sir. So again with this NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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18 1 example here, we're actually looking at a non-safety 2 related risk significant function associated with 3 reactor building crane. And as described a moment 4 ago, the D-RAP functions are provided to us in a 5 support system to support the system format.
6 So this function for the reactor building 7 crane is that the reactor building crane supports the 8 NuScale Power Module by providing structural support 9 and mobility while moving from refueling, inspection, 10 and operating bay.
11 Now if we go to the initial test program 12 itself in Section 14.2, we find Table 14.2-52 titled, 13 Reactor Building Cranes Test No. 52. This is the test 14 abstract for the reactor building crane.
15 The D-RAP function, we just discussed. It 16 was identified to be a testable function, and so it is 17 inventoried in this test abstract. Each of the 18 testable functions will be inventoried on that test 19 abstract.
20 In addition to the function, we have the 21 categorization of safety and risk significance as well 22 as a column that lists the test or tests that 23 demonstrate that functionality. And this is where 24 NuScale's test abstracts are significantly different 25 than previous applicants and that we provide this NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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19 1 roadmap so that for each function you can go and look 2 at the test that specifically verify that 3 functionality.
4 Also want to point out to -- there was a 5 question yesterday about pre-operational testing about 6 whether it's performed once or for each module and how 7 that occurs. I'll point out the first line after the 8 title of this test abstract that states that pre-9 operational test is required to be performed once 10 unless otherwise noted in the test. The cue to say, 11 depending on the test will tell you in the details of 12 the test whether or not you need to do it once or more 13 than once. And I'll elaborate on that here in a 14 moment.
15 The next section of the --
16 DR. SCHULTZ: Excuse me, Chris. How do 17 you differentiate -- and the figure wasn't clear. But 18 as you go through the item by item description as an 19 example, how is the differentiation done between 20 what's required for the component test and what's 21 required for the system test?
22 MR. MAXWELL: I'll get to a description of 23 the component systems test here in just a moment.
24 DR. SCHULTZ: Excellent. Thank you.
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20 1 abstract is the prerequisites. The prerequisites are 2 required to be completed prior to commencing the pre-3 operational testing. So we don't find them listed.
4 Here we see for the reactor building crane there's 5 some site acceptance testing that's required to be 6 completed. And then we have some various rated-load 7 tests are required to be completed and approved. And 8 last, a prerequisite that all the instrument 9 calibration for the reactor building crane must be 10 completed prior to commencing pre-operational testing.
11 The next section is component-level 12 testing. Component-level testing is standardized to 13 provide an equal level of detail across the systems.
14 So what you'll find depending on which system you're 15 looking at, we have a standard set of component-level 16 test that we apply to the systems.
17 So you'll find items like verification of 18 remote operation of equipment, manual control of 19 variable speed pumps and fans, verification that pump 20 operation doesn't result in water hammer, equipment 21 response to -- automatic equipment response to signals 22 for plant equipment protection, and verification of 23 instrumentation signals designed to be monitored in 24 the control room.
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21 1 testing, you look at the reactor building crane. And 2 the component-level test that we end up with are the 3 verification of the reactor building crane controls, 4 verification of the response of the system to abnormal 5 condition signals, and a verification of all the 6 reactor building crane instrumentation signals 7 designed to be monitored in the control room.
8 So that's the component-level piece. The 9 next section is --
10 CO-CHAIR SKILLMAN: Chris, what is your 11 estimate of the number of component-level tests that 12 are required for this design?
13 MR. MAXWELL: It'd be hazardous to guess 14 a number. But what I can do is say that for each pump 15 we test the ability to remotely operate that pump if 16 it has remote operation. So in the feed and 17 condensate system, there's six pumps. For each valve 18 that could be remotely operated, we verify that we can 19 stroke that valve remotely. So every valve in each of 20 the systems that's true. The instrumentation signals 21 we verify for every system. The NuScale design has 22 significantly fewer components in it compared to a 23 traditional design. But each of those undergo 24 component-level testing.
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22 1 100, 1,000, 10,000?
2 MR. MAXWELL: You have a number for me, 3 Edan? I'd measure it in thousands.
4 CO-CHAIR SKILLMAN: I'm thinking four or 5 five thousand number.
6 MR. MAXWELL: I think that's a reasonable 7 number.
8 CO-CHAIR SKILLMAN: That's a guess.
9 MR. MAXWELL: I have a database that has 10 that information, but I don't have access to it.
11 CO-CHAIR SKILLMAN: Well, I think that 12 information is important in the context that this is 13 a new design, a very conservative and robust new 14 design. And at least from my experience, you're doing 15 some things that nobody has ever done before. And the 16 devil is in the details.
17 And I think of startups that I've been 18 involved in and the pre-operational testing I've been 19 involved in and how many times two years later we've 20 gone back and said, where's the record for that? We 21 can't find it. And you're in a unique position to be 22 able to have those records for what will be your 23 future customers.
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23 1 that the new owner is going to inherit. And if that 2 new owner has the right paper for each module and for 3 each subsystem, for each CVCS, for each evacuation 4 system, that that customer has a legacy that enables 5 that customer to be successful.
6 And I'm preaching to the choir. But all 7 I'm saying is that number is an important number, and 8 the quality of the information in that pile of paper, 9 the quality of the information is really important.
10 And I should've mentioned Dr. Dennis Bley 11 has joined the team. Dennis, thank you. Please 12 proceed.
13 MEMBER BLEY: Thanks. I mean, you said 14 all the valves, they can be remotely operated or 15 stroked. I haven't seen detailed P&ID. So I don't 16 know where you have manual isolation valves. But 17 there must be some and there must be some on systems 18 you really want to be able to put water through. Are 19 they not part of the test program?
20 MR. MAXWELL: They're part of construction 21 testing. Manual valves were verified as part of 22 construction testing.
23 MEMBER BLEY: But not with flow at that 24 point?
25 MR. MAXWELL: Well, there will be some.
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24 1 There'll be flushing of systems and hydros required 2 through construction testing. But we also have 3 system-level testing where we flow water through the 4 systems --
5 MEMBER BLEY: Okay.
6 MR. MAXWELL: -- or air through the 7 systems.
8 MEMBER BLEY: Okay. So checking on those.
9 MR. MAXWELL: Yes sir.
10 MEMBER BLEY: I've seen -- well, you all 11 know anecdotes. But with all the QA and everything 12 else, we had a valve that wouldn't open and fought it 13 and fought it and fought it. It wasn't right when it 14 was put in. It was a little time later. Finally took 15 it apart and here somebody during construction had 16 stuffed the bonnet full of things that prevented it 17 from moving more than a tiny bit.
18 MR. MAXWELL: Understood. And we're 19 certainly listening to the OE, that we're hearing from 20 AP1000 and incorporating that in our test program.
21 The prerequisite you saw were the prerequisites 22 required. This is the test abstract phase. There's 23 the detailed procedure -- test procedure phase that 24 occurs later from these test abstracts to verify items 25 like you're suggesting to make sure that these valves NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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25 1 operate.
2 MEMBER BLEY: As long as you have full 3 flow. A full system test, I think that covers it.
4 MR. MAXWELL: That's correct.
5 MEMBER SUNSERI: So Chris, let me add. I 6 think you're describing this, but I just want to hear 7 it confirmed, right? So you have the Reg Guide for 8 pre-operational and initial to start up this thing and 9 all that stuff. You guys are following it without 10 exception, right? The NuScale design may be unique, 11 but it's not unique that it has pumps. It's not 12 unique that it has valves. It's not unique that it 13 has breakers. It's not unique that it has control 14 systems. And that's what this, the Reg Guide, 15 describes how to test, right?
16 And so you are following -- so the 17 question is, are you following without exception 18 unless as applicable the Reg Guide for a pre-19 operational test?
20 MR. MAXWELL: Yes sir, we are. What we 21 recognize was the need to go beyond the Reg Guide 22 because again of those unique design features and 23 attributes. You're right, spot on with the pumps and 24 valves. The guidance is clear, and we meet that 25 guidance. We follow it. It's just what we've done in NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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26 1 our test abstracts is look ahead.
2 And because we've had the benefit of 3 having a P&ID, detailed P&IDs and procedures ahead of 4 time, we're able to be a little more -- again that 5 roadmap. We're able to provide that roadmap, a 6 detailed look at how exactly we intend to demonstrate 7 the performance of the system.
8 CO-CHAIR SKILLMAN: Maybe this would be a 9 good place -- no, let's wait till 14.3 and I'll ask my 10 question. Go ahead.
11 MR. MAXWELL: The next section after 12 component-level testing are the system-level tests.
13 And they are used to demonstrate and verify integrated 14 functionality or functionality at the system level 15 rather than just the component level.
16 So we're looking at the first system-level 17 test now for the reactor building cranes. It's 18 System-Level Test 52-1. And to kind of elaborate a 19 little bit the difference between the component 20 testing and the system-level testing. Again, the 21 component-level testing, I'm verifying this pump 22 works, this valve works. Here at the system-level 23 test, now I'm demonstrating the overall capability of 24 the system.
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27 1 I think you mean it is functionally successful for the 2 task intended.
3 MR. MAXWELL: Yes sir, that's much better 4 put. We have a set of parameters, for instance, pump 5 curves that -- or valve stroke times and we verify the 6 components meet those requirements, that design 7 criteria.
8 CO-CHAIR SKILLMAN: Thank you.
9 MR. MAXWELL: For Test 52-1, what you see 10 is a -- it's a test of the ability to install and 11 remove a module from its operating bay. To the 12 discussing whether a test needs to be performed once 13 or multiple times, reactor building crane is a good 14 example of this in that reactor building crane itself 15 has attributes that need only be tested once. In 16 other words, that attribute will be used identically 17 for all 12 modules.
18 But there are other attributes which is 19 installing the module in the bays that are module 20 specific. So I need to be able to demonstrate the 21 capability of the crane to not only correctly lift 22 Module 1 in its operating bay and move it but also 23 Module 6.
24 So what we do in the system-level test, if 25 you see in the test method at the bottom, it says, NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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28 1 repeat this sequence for teach NPM installation. So 2 I'd have to repeat this test 12 times. But in the 3 acceptance criteria, the first four acceptance 4 criteria are specific to the crane. The involve the 5 ability to move the bridge and trolley, verify the 6 speeds of movement and the ability to operate the main 7 hoist and the limitations associated on the hoist.
8 So Acceptance Criteria 1 through 4, 9 there's a note at the bottom. Acceptance Criteria 1 10 through 4 only need to be satisfied for the first 11 performance of this test. Now by satisfied, we mean 12 documented for a completion of this test. You'll 13 still observe those characteristics each time you 14 perform the test. But to document completion for the 15 initial test program, you'll do it for the first test.
16 The Acceptance Criteria 5 and 6 again are 17 that module-specific piece verifying that the module 18 is positioned at the correct location, module-19 specific. So Acceptance Criteria 5 and 6 need to be 20 satisfied for each module.
21 If we go back and look at the reactor 22 building crane function that we were looking at, we 23 see that one of the elements of that function was 24 satisfied by 52-1 -- System-Level Test 52-1 and that's 25 the operating bay portion.
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29 1 The remaining elements of the function are 2 demonstrated in System-Level 52-2 which demonstrates 3 the ability to assemble and disassemble a module.
4 Because this process, once the module is moved to the 5 stands, whether it be the containment or the reactor 6 stand, the functionality of the crane at that point is 7 identical module to module. So the system-level test 8 is performed once.
9 CO-CHAIR CORRADINI: Maybe this you're 10 going to get to, but I'm kind of curious. So you have 11 -- you build out the reactor pool, install all the 12 pieces. You're going to now install Module 1. Is 13 there an estimate for the time it takes to perform 14 both component and system-level testing before --
15 because the time I bring in the module and then 16 actually take it to fuel load? Or I'm asking that 17 wrong because of the way this thing words. Before I 18 take it to bring it to critical?
19 MR. MAXWELL: We're working on those 20 estimates at this time.
21 CO-CHAIR CORRADINI: Given, I guess, the 22 way you describe it, it sounds like it would be 23 potentially longer than what we'd have in a large 24 light water reactor. That's not the case because of 25 differences in number of testing. I'm just trying to NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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30 1 understand. This seems fairly comprehensive to me, 2 but I'm trying to understand.
3 MR. MAXWELL: Understood. I believe 4 significantly shorter than what you would have in a 5 traditional design. The number of components is 6 significantly lower and --
7 CO-CHAIR CORRADINI: Is part of it, to 8 what Dick was asking, relative to factory acceptance 9 testing that is appropriately documented and is in 10 lieu of or is done prior to actually the module 11 arrival?
12 MR. MAXWELL: A portion, very small 13 portion.
14 CO-CHAIR CORRADINI: Okay.
15 MR. MAXWELL: I'd say the module 16 protection system is really one of the larger factory 17 acceptance testing systems.
18 CO-CHAIR CORRADINI: Okay.
19 MR. MAXWELL: But the reason I would say 20 it's a shorter amount of time relative to the other --
21 CO-CHAIR CORRADINI: Is just number?
22 MR. MAXWELL: Number and then complexity 23 of systems and also scale. It's something I have to 24 continuously remind myself of is the scale of these 25 systems is much smaller.
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31 1 CO-CHAIR CORRADINI: But you're going to 2 do it in time?
3 MR. MAXWELL: That's correct. But I would 4 say the design was made with the benefit of operating 5 experience. I'll take, for example, we create testing 6 that the valves -- in a traditional design performed 7 that we create testing, you may have a very large 8 volume that you need to pressurize, allow that volume 9 to stabilize.
10 Where ours, if we're talking about a two-11 inch line with the containment isolation valves 12 integral to the same body with a predesigned 13 connection to accomplish the testing. So the system 14 was designed anticipating the need to perform that 15 testing and get very small volumes to press up and 16 stabilize, significant reductions in test time.
17 CO-CHAIR CORRADINI: Okay. Thank you.
18 MR. MAXWELL: So the -- again, just to 19 close that loop, that the function that we were 20 looking at for the reactor building crane. The 21 remaining elements of that function are verified 22 through the second system-level testing group and the 23 reactor building crane test.
24 Next section after pre-operational testing 25 is the startup testing. Regulatory Guide 1.68 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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32 1 describes startup testing as equipment performance 2 tests completed during and after fuel load and 3 outlines in detail the testing to be performed for --
4 again, for initial fuel load and pre-critical testing, 5 initial criticality, low power testing, and power 6 ascension testing.
7 CO-CHAIR CORRADINI: Is this where the 8 ECCS valves are tested, or is it also in the prior 9 component testing where they're tested?
10 MR. MAXWELL: The answer to your question 11 is yes in both areas. We have pre-operational 12 testing. We do it cold to verify the stroke times of 13 the ECCS valves, then hot functional testing.
14 CO-CHAIR CORRADINI: Which is?
15 MR. MAXWELL: Hot functional testing is 16 without nuclear heat. We use a module heating system 17 and a chemical and volume control system to heat up 18 our module to normal operating pressure and as high a 19 temperature as we can achieve under the module heating 20 system.
21 CO-CHAIR CORRADINI: Okay.
22 MR. MAXWELL: And then in those 23 conditions, we will stroke the ECCS valves again.
24 CO-CHAIR CORRADINI: Okay.
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33 1 for -- I don't know if we stroke ECCS for startup 2 testing.
3 CO-CHAIR CORRADINI: I doubt it.
4 MR. MAXWELL: I do too, not at the normal 5 operating pressure and temperature. We do lower --
6 (Simultaneous speaking.)
7 CO-CHAIR CORRADINI: I see. And then when 8 it's appropriate, I'm kind of curious. So the DHRS is 9 primarily startup testing?
10 MR. MAXWELL: DHRS, we also do the same 11 hot functional testing.
12 CO-CHAIR CORRADINI: Because they're 13 valves?
14 MR. MAXWELL: That's correct. And also to 15 demonstrate to a degree to ability to cool us down 16 below 420 degrees, again in pre-operational space.
17 And then in DHRS, we do in startup testing as well.
18 CO-CHAIR CORRADINI: Okay. Thank you.
19 MR. MAXWELL: So with the very detailed 20 requirements or suggestions, recommendations for 21 testing these various stages of startup testing, 22 again, NuScale evaluated each of those for 23 applicability and added those to our initial test 24 program where applicable. And once again, looked for 25 any differences, something that was not anticipated NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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34 1 for our design. And a good example of that would be 2 an island mode operation which we do for performance 3 as a part of startup testing.
4 CO-CHAIR SKILLMAN: Chris?
5 MR. MAXWELL: Yes sir.
6 CO-CHAIR SKILLMAN: Chris, what is the 7 path forward when a licensee is conducting this 8 testing and the testing does not go as planned? And 9 the root cause is determined to be either the test was 10 not as it should've been. It wasn't accurate or 11 wasn't, if you will, crafted properly or there is an 12 unexpected phenomenon in the NuScale design that led 13 to the failure of the test. What is the path forward 14 from there?
15 MR. MAXWELL: As part of the initial test 16 program, we have a startup administration manual that 17 outlines what procedures and policies are required for 18 the initial test program. One of those is that 19 there's essentially a board that oversees the testing.
20 If you have a failed test and the issue was the test 21 itself, if there needs to be a revision to the test, 22 there's a process for revising that test and approval 23 all the up through the board prior to recommencing or 24 re-conducting that test.
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35 1 that's addressed as part of the startup administration 2 manual. There will be a process for backing out of 3 that test and addressing it with -- I assume with the 4 vendor, with NuScale.
5 CO-CHAIR SKILLMAN: I'm glad you said that 6 because it may be that the only intellectual reservoir 7 of risks in Corvallis for the resolution of that 8 problem, I bring to your attention the condensate 9 return issue that was discovered on the AP1000. When 10 that is finally sorted out, it really does come back 11 to the NSSS vendor. And the NSSS vendor, for better 12 or for worse, has a unique accountability for 13 technical detail that's well beyond the applicant's 14 ability to examine.
15 So I appreciate your saying that may come 16 back to the NSSS vendor. If it does, might that 17 result in a departure because it could be Tier 1 18 information?
19 MR. MAXWELL: Potentially. I can't say 20 with a certainty. But given the detail that is in 21 Tier 1, it absolutely could result in departure.
22 CO-CHAIR SKILLMAN: Okay. Thank you.
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36 1 extent of condition, corrective action, all that kind 2 of stuff?
3 MR. MAXWELL: It would definitely meet the 4 definition of entering the corrective action program.
5 MEMBER SUNSERI: Okay.
6 CO-CHAIR SKILLMAN: One more. If you're 7 in that position -- and this is really theoretical.
8 So excuse me for being -- trying to be clairvoyant.
9 I'm not. I'm just thinking it through.
10 So here you are eight years from now. An 11 applicant is working his or her way through this, and 12 we've discovered a failed test. And it really does 13 call into question, if you will, the function 14 performance requirements or the architecture of the 15 test and it results in some serious questions. Does 16 this get handled through a 50.59-like process where an 17 applicant would say, well, this doesn't really -- it 18 really doesn't cross the line into the license, or, it 19 does and I better go and file the paperwork for 50.59 20 with the NRC?
21 MR. RAD: So the short answer -- this is 22 with the licensing answer -- is it depends. It 23 depends on what changes. So to the extent that the 24 test impacts Tier 2, it may be a departure. And for 25 clarification, changes to the information in Tier 1 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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37 1 would be an exemption because that is the information 2 certified in the design certification rule.
3 CO-CHAIR SKILLMAN: Thank you. Exactly 4 right. Thank you.
5 MR. RAD: So it may be a license amendment 6 request. It may be an exemption to the Tier 1 7 information. Or it may simply be a departure from the 8 Tier 2 information that's handled without prior 9 approval from the NRC if it doesn't meet that 10 threshold.
11 CO-CHAIR SKILLMAN: Great, thank you. And 12 thank you for that clarification.
13 MR. MAXWELL: The test abstracts 14 associated with the startup testing are similar in 15 content but slightly different in layout because of 16 the different nature because there isn't a component-17 level feature to them. Essentially, the startup tests 18 become an individual system-level test if you will.
19 That's what parallels, but although the startup tests 20 involve multiple systems.
21 Example of that we see here is this is 22 Test 81 of Control Rod Assembly Full-Height Drop Time 23 Test contains those elements of the objectives, the 24 prerequisites, test method, and the acceptance 25 criteria for that test.
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38 1 Again, I want to point out that as with 2 each of our test abstracts, the first line, it states 3 that this startup test is required to be performed for 4 each NPM. Not surprisingly, but the control rod 5 assemblies are tested to be module specific.
6 CO-CHAIR SKILLMAN: Why doesn't that 7 communicate for each NPM, comma, for each core?
8 MR. MAXWELL: The initial plant test 9 program is completed prior to initial -- sorry, for 10 your initial startup. And then after that, you're in 11 your in-service testing and you'll have testing 12 associated with control rods and that program.
13 CO-CHAIR SKILLMAN: Okay. Thank you. All 14 right.
15 MR. MAXWELL: Another, also addressed by 16 Reg Guide 1.68 are first-of-a-kind test which Reg 17 Guide 1.68 defines as tests that are new, unique, or 18 special tests used to verify design features being 19 reviewed for the first time by the NRC.
20 We did a comb of our systems, their 21 features, and the components and attributes to 22 identify any first-of-a-kind testing and constructed 23 Table 14.2-110 to list those new design features.
24 Included in those first-of-a-kind type test is like 25 our ECCS valve design first-of-a-kind, a containment NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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39 1 evacuation system, and our island mode operation.
2 CO-CHAIR SKILLMAN: Before you jump in 3 here on 14.3, you've introduced us to, I think, an 4 excellent example with a crane and sufficient 5 reference, if you will, of plumbing systems. You 6 haven't said much about instrumentation and control 7 system ITAAC or electrical system ITAAC. May I ask 8 you to comment on those two categories, please.
9 MR. MAXWELL: Sure. First of all, I want 10 to make a distinction between the initial test program 11 and ITAAC. They really are separate items 12 occasionally that overlap through pre-operational 13 testing. So Reg Guide 1.68 describes the pre-14 operational testing requirements and then we have 15 ITAAC which is a 10 CFR requirement.
16 As far as elements of electrical 17 distribution, all of the functions in our electrical 18 distribution system, AC and DC, are all part of --
19 there's a test abstract for each of them. We test 20 every testable function of those systems. The same is 21 true for our I&C systems, the module control system, 22 plant control system, plant protection system, and the 23 module protection system.
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40 1 testing. Being the digital systems that they -- or 2 being the control systems that they are, that there's 3 an ITAAC also for module protection system in addition 4 to the pre-operational testing. So there's overlap 5 there. But again, we have a test abstract for each of 6 them and the functionality is verified through either 7 factory and site acceptance testing or through a 8 demonstration.
9 When you get to the -- the demonstration 10 comes at the device. The module protection system may 11 have the -- it has a function to close the containment 12 isolation valves. So the factory acceptance testing 13 and the site acceptance testing will demonstrate all 14 the logic, all the input and outputs for the logic.
15 But we still have to verify that given a signal from 16 the module protection system that the actuated 17 component actuates.
18 So the records will be verified to open 19 the containment isolation valves, to close ECCS 20 valves, to get heat removal system actuation valves, 21 all part of our pre-operational testing program also 22 happen to be verified as part of ITAAC.
23 CO-CHAIR SKILLMAN: Thank you.
24 MR. MAXWELL: The final section of Chapter 25 14 is 14.3, Certified Design Material.
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41 1 MEMBER BLEY: Is that just a requirement, 2 or how does it happen that we have these both under 3 pre-op testing and ITAAC?
4 MR. MAXWELL: It's --
5 MEMBER BLEY: It seems like a bit of a 6 burden to track it. Or do you build that right into 7 your pre-op test, the ITAAC verification?
8 MR. MAXWELL: They are two separate 9 requirements, and so they're tracked separately. But 10 like I said, where you can pre-operational test to 11 satisfied an ITAAC, we'll do that. We do that.
12 MEMBER BLEY: I was just thinking how 13 you'll provide this to the COL people. And I would 14 hope that at least somehow the ITAAC -- appropriate 15 ITAAC are tied to the test -- the initial test 16 procedures.
17 MR. MAXWELL: So --
18 MEMBER BLEY: Otherwise, that seems a 19 nightmare of keeping track.
20 MR. MAXWELL: Absolutely. We recognize 21 that. And we have two things that we've done to help 22 with that. The first is that where I say where we can 23 credit a pre-operational test for ITAAC, we do. If 24 you go to that test abstract, the acceptance criteria 25 has the ITAAC number --
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42 1 MEMBER BLEY: Right there?
2 MR. MAXWELL: -- listed right in the 3 acceptance criteria. That's the first flag. We also 4 have, again, a roadmap from ITAAC and Tier 1 over to 5 Tier 2, Chapter 14.3. For each ITAAC, if there's a 6 pre-operational test associated with it, the 7 description of that ITAAC says, this ITAAC will be 8 verified by pre-operational --
9 MEMBER BLEY: Okay.
10 MR. MAXWELL: -- tests, and points to it.
11 And the second thing that we're doing is ITAAC 12 travelers. So ITAAC can be a many-to-one, one-to-13 many, or many-to-many relationship.
14 I may have -- I'll use containment 15 isolation valves as an example where I have a single 16 ITAAC to verify that I've got a ASME design report for 17 each of the containment isolation valves. So many 18 valves have to have a report to close that ITAAC. We 19 have -- using database, have linked each of the 20 components from our MEL (phonetic) to the individual 21 ITAAC to track closure for that ITAAC.
22 But also for each of the components, a 23 containment isolation valve will have multiple ITAAC 24 it's associated with. So you also can see for a given 25 component all the ITAAC that have to occur for that NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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43 1 component.
2 We also recognize that ITAAC will occur at 3 different phases. Some of them will happen in vendor, 4 like equipment qualification testing. Some of them 5 will happen during the module manufacture. Some will 6 occur during pre-operational testing. And again, the 7 containment isolation valve, that's true, all three of 8 those phases. So we recognize which phase that ITAAC 9 is to occur and our ITAAC travelers it identifies at 10 each phase, which ITAAC --
11 MEMBER BLEY: Somehow, you've --
12 MR. MAXWELL: -- will be completed.
13 MEMBER BLEY: -- built this into a 14 computer-based system, I assume, to help people along.
15 I've heard a lot of complaints from people trying to 16 deal with the massive amount of ITAAC information. I 17 just wondered if the guidance that's out there has 18 gone further than the requirements and if you couldn't 19 do this in a simpler way.
20 MR. MAXWELL: I'm sure. The database 21 helps us, that we use the operating experience from 22 the current plants to inform us and to develop 23 tracking mechanisms to ensure that we don't miss 24 ITAAC.
25 MEMBER BLEY: Okay, sounds good.
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44 1 CO-CHAIR SKILLMAN: Chris, you've touched 2 on several of the key issues that I identified in my 3 opening comments. You just mentioned several 4 different types of ITAAC. You just mentioned how it 5 is captured in your database. Going forward, I will 6 be interested in hearing how ITAAC accountability, how 7 the roundup is certified thorough for the various --
8 appear to be about seven different types. How all of 9 them are called and accounted for so that at the end 10 of the process the license shows completion. So as 11 you proceed, I just would ask you to keep that in 12 mind.
13 MR. MAXWELL: Sure. I think I have a 14 slide that'll help with that. What I want to walk us 15 through is how the detailed design information, that 16 Tier 2 information gets selected to be included in our 17 Tier 1 Design Descriptions, including the design 18 commitments and how those design commitments form our 19 ITAAC.
20 So I'll start with the purpose of Section 21 14.3. One of the purposes is to provide the guidance 22 for selecting that detail design information in Tier 23 2 to be included in the Tier 1 certified design 24 material, including the ITAAC required by 10 CFR 25 25.47(b)(1).
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45 1 As a reminder of what ITAAC is, ITAAC are 2 those inspections, tests, analysis, and acceptance 3 criteria identified in the combined license that are 4 met by the licensee, are necessary and sufficient to 5 provide reasonable assurance that the facility has 6 been constructed and will be operated in conformity 7 with the license, the provisions of the Atomic Energy 8 Act as amended, and the Commission's rules and 9 regulations.
10 MEMBER BLEY: So that sounds as if ITAAC 11 should be a subset of the results of the pre-op 12 testing. Is that always true, or are there some ITAAC 13 that aren't covered in pre-op testing?
14 MR. MAXWELL: The latter. There's a lot 15 of ITAAC that are not covered as a part of pre-16 operational testing that occur long before pre-17 operational testing before the components are 18 installed.
19 MEMBER BLEY: Yeah, that's right. Okay.
20 MR. MAXWELL: So other detailed design 21 information that's contained in Tier 2, only the most 22 safety significant aspects that each of the systems 23 are included in the Tier 1 design descriptions. These 24 aspects -- these safety significant aspects are 25 referred to as top level design features and top level NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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46 1 performance characteristics. To identify what 2 information qualifies for inclusion in Tier 1, we 3 applied a first principle screening process.
4 Section 14.3 provides guidance that the 5 Tier 1 design descriptions are limited to the top 6 level design features of the following categories:
7 safety related SSC, non-safety related SSC that 8 provide protection to safety related components, 9 security system physical SSC, and risk significant 10 non-safety related SSC determined by results of PRA.
11 In those categories, top level design 12 features that fall into these categories, not 13 surprisingly include categories like safety related 14 pressure boundaries and component performance, fuel 15 storage and seismically qualified structures, and 16 physical security.
17 So this is the -- to answer a little bit 18 of the question that's being asked is we've taken the 19 Tier -- all the detailed Tier 2 design information.
20 We apply our first principles to select the 21 information to be included in the design description 22 Tier 1 information. If the information in Tier 2 23 changes, we reevaluate it to see if Tier 1 needs to be 24 updated as we go through the design certification.
25 CO-CHAIR SKILLMAN: Has that occurred?
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47 1 MR. MAXWELL: Yes sir.
2 CO-CHAIR SKILLMAN: What's an example, 3 please.
4 MR. MAXWELL: Well, one of them was the 5 module lift adapter originally was not part of the 6 standardized ITAAC. But through PRA of Chapter 17 7 said it's a risk significant component, and ITAAC was 8 created. It was described in Tier 1, and ITAAC were 9 created for it.
10 CO-CHAIR SKILLMAN: Thank you.
11 MR. MAXWELL: So now with the information 12 selected to be included in Tier 1, we divide that 13 information in two categories. The detailed design 14 information selected for Tier 1 that describes system 15 function, safety classification, and general location 16 make up the system description portion of the design 17 description while the design features such as seismic 18 and ASME classifications and environmental 19 qualification requirements make up the design 20 commitments portion of the system description. And 21 this is important because it's the information in the 22 design description that is verified by ITAAC. This is 23 the basis for our ITAAC.
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48 1 entries are provided. ITAAC themselves are broken 2 into three columns. The first column is the design 3 commitment, and the design commitment contains the 4 text that's to be verified and is extracted directly 5 from the design commitment in the design description 6 in Tier 1.
7 The second column is the inspections test 8 and analysis which includes the method in which the 9 design commitment will be verified. And before I move 10 to the acceptance criteria, so you mentioned before 11 that there was seven categories throughout vendor 12 testing. This is where I think the important 13 distinction here is that we have a design commitment 14 to meet. That's what we have to demonstrate that we 15 meet this design commitment.
16 Now we can go to that pool of possible.
17 Is it a test that will demonstrate an analysis? What 18 is the most appropriate method to demonstrate we meet 19 that design commitment? So it's we don't go to the --
20 we don't start with a list of tests and then build it.
21 So you could have one of those areas where you 22 actually didn't have an ITAAC to utilize that method.
23 I would say that a test is always my first choice.
24 CO-CHAIR CORRADINI: You're starting with 25 a function.
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49 1 MR. MAXWELL: You're right.
2 CO-CHAIR SKILLMAN: Either the credited 3 function or whatever the design feature that must be 4 fulfilled.
5 MR. MAXWELL: A function --
6 CO-CHAIR SKILLMAN: Learning rom that to 7 how do you confirm that.
8 MR. MAXWELL: That's correct. And I'll 9 add, or feature --
10 CO-CHAIR SKILLMAN: Or a feature, yeah.
11 MR. MAXWELL: -- or a requirement. So in 12 the third column is the acceptance criteria. It 13 identifies conditions that you must demonstrate or 14 verify again to demonstrate that you meet -- that the 15 licensee meets the design commitment.
16 So any areas that you wanted me to discuss 17 that I haven't met yet?
18 MEMBER BLEY: I have something I'd like to 19 ask you about. It doesn't really fit here. But if 20 you've been around the last few days, you'd know we've 21 asked a lot of questions about the ECCS valves because 22 that's the one thing. If they somehow don't work the 23 way the reliability you think, it could really change 24 the risk results and put whoever is operating the 25 plant in a more troublesome spot.
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50 1 It strikes me, and I wonder if you guys 2 have thought about this some. It's not a startup 3 issue. It's a later one. And perhaps a more thorough 4 tracking of all the data on all of the ECCS valves 5 over the years as they're stroked and tested to see if 6 there are patterns among the valves and trends over 7 time.
8 And I know you look for that generally.
9 But here we're looking for things that might indicate 10 there's some kind of degradation going on in all of 11 those valves. A real emphasis on that kind of program 12 for after startup, have you talked about that all?
13 Because you can't do all this and manufacturer's test.
14 You can do some accelerated aging, but they don't 15 mimic exactly the conditions in the plant.
16 MR. MAXWELL: We have Gary McGee on the 17 line in Corvallis.
18 MEMBER BLEY: Who is free to speak up. We 19 can't quite hear you.
20 MR. McGEE: Okay. I just need some 21 clarification. What exactly are we --
22 MR. MAXWELL: In service testing.
23 MR. McGEE: What's the question?
24 MR. MAXWELL: In service -- if you could 25 describe in service testing for ECCS valves and how we NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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51 1 plan to track the conditions of the valve to identify 2 potential degradation of the valve over time once the 3 valve is in service.
4 MEMBER BLEY: And not just individual 5 valves. But if there's a plan to see if there's a 6 common aging effect among all of them.
7 MR. McGEE: Well, in service testing is --
8 the whole thing about the OM code is in service 9 testing is a trending program where you just don't 10 look at stroke time. We also -- we're committed to 11 the -- currently committed to OM-2012.
12 But we also take portions of OM-2017 where 13 we take Mandatory Appendix 4 which is AOV testing.
14 But we apply it to both the CIVs and ECCS for 15 performance -- what we call performance of assessment 16 testing. And we take various characteristics of the 17 valve.
18 And so it's not only stroke time but we 19 take the block valve and other characteristics of 20 those valves and do comprehensive testing to -- the 21 great thing about having 12 modules is you do test the 22 same valves. It's like having 12 different plants and 23 you look at those. You trend all those valves and see 24 what each valve is doing.
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52 1 you take a look at all your other valves and see what 2 you got going. And that's what you've done in regular 3 traditional plants as well with your valves. You had 4 your -- you grouped your valves and you look at your 5 different air op valves. And when you have something 6 come up, a bad stroke time in an air op valve, you 7 look at your other ones to see what they're doing.
8 We do the same thing with our ECCS valves.
9 If a valve doesn't stroke correctly or it starts 10 leaking, you look at the other valves and see what 11 you've got going.
12 MEMBER BLEY: Okay. Well, that's kind of 13 the standard approach, and I think that's essential.
14 What I was suggesting is because of the really 15 significant impact of these valves in this particular 16 design, something that perhaps digs a little deeper at 17 trends among the various sets might be useful. Just 18 something to think about. You don't have to answer 19 that at this point.
20 MR. MAXWELL: Thank you, Gary.
21 MR. McGEE: Sure.
22 CO-CHAIR SKILLMAN: Chris, you asked 23 whether there were any other issues.
24 MR. MAXWELL: Yes sir.
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53 1 things, the robustness of NuScale's configuration 2 management program to keep all of this information 3 organized and the NuScale QA program to ensure that 4 the information for your safety equipment is logged 5 and maintained and in a manner that is retrievable for 6 a future user. Yes, please.
7 MR. RAD: Okay. This is Zach Rad. Well, 8 you know that. So just to talk about a couple of 9 things. And so as we mentioned, as Chris did a great 10 job of explaining, Tier 1 is built off of Tier 2.
11 It's important to recognize that both of 12 those documents are built off of a much larger volume 13 of source documentation. And in fact, each statement 14 of fact is required by our process to have a source 15 document that supports it. Those source documents are 16 the controlled documents. And when I say controlled, 17 I mean controlled under our document control which is 18 one provision of the NQA-1 program.
19 So to address the quality assurance 20 requirements, I won't go into the details because I 21 simply can't recite them. But I'll tell you that it 22 meets the requirements of NQA-1 document control and 23 retention. So that is the required standard.
24 CO-CHAIR SKILLMAN: That's sufficient.
25 Thank you.
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54 1 MR. RAD: When it comes to maintaining and 2 controlling what's frequently called configuration, 3 there are a couple ways this happens. And so the 4 design control process requires that when a design 5 change is made, that impacts to other design 6 documents. And other programmatic documents is 7 reviewed. So those are the source documents, the 8 underlying source documents. Any changes that are 9 necessary, conforming changes need to be addressed as 10 part of that design change.
11 Secondarily, that same process, the design 12 change process, drives us to review the licensing 13 basis documents for impacts. There's a configuration 14 management database that links every XY section, every 15 topical report, technical report to its underlying 16 source documents. So there's an immediate reference 17 available.
18 Those impacts are reviewed. If there's 19 changes to Tier 1, those are made. Those are provided 20 currently now during the review to the NRC as updates.
21 If it's post-licensing and it's in the COL, that'll be 22 a departure, an exemption, or a license amendment.
23 It'll be a departure and exemption during the COL 24 licensing process. It'll be a departure, an 25 exemption, or an amendment post-COL license.
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55 1 Let's see. What else is there? Oh, yeah.
2 And then, of course lastly, anything site specific is 3 going to get its own version of inspection tests, 4 analysis, startup testing, et cetera. So if they 5 demand changes in the design that are site specific or 6 there are site specific characteristics that are yet 7 to be fleshed out like EP and security, they'll get 8 their own testing, et cetera, that'll have to be 9 defined in the COL application.
10 CO-CHAIR SKILLMAN: Thank you. Chris, go 11 ahead.
12 MR. MAXWELL: Okay.
13 MR. RAD: One other item. There's one 14 question you raised. You asked if our classifications 15 for SSCs were consistent with 50.69. They're similar 16 to but different. So 50.69 calls out Risk Informed 17 Safety Class 1 through 4, and it calls them safety 18 related that perform safety significant functions and 19 non-safety and safety significant functions and then 20 similar for the 3 and 4, safety related non-safety 21 significant and then non-safety with low safety 22 significant functions. So different wording but 23 similar concept.
24 CO-CHAIR SKILLMAN: Yeah, the color coding 25 on slide 2 or 3 appeared to be almost the same at NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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56 1 50.69 is why I asked the question. Thank you.
2 MR. MAXWELL: So describe how we take the 3 design commitments from the system from the design 4 descriptions in Tier 1 and then those become our 5 ITAAC. We received a letter dated April 8th, 2016 6 from the NRC that provide a set of standardized DCA 7 ITAAC for the site application.
8 So what we did was take all of our design 9 commitments. And where they aligned with the 10 standardized ITAAC, we used the standardized ITAAC.
11 Where there wasn't a representative standardized 12 ITAAC, we created a design specific ITAAC. And that 13 effort resulted in the complete set of ITAAC provided 14 in Tier 1.
15 CO-CHAIR SKILLMAN: I do have that letter, 16 and the letter said, this is a suggestion. Clearly, 17 you used the portion that was a suggestion and added 18 to it or modified it to create the present very 19 thorough listing that you've created. So thank you.
20 I understand.
21 MEMBER REMPE: So I'm a little slow, but 22 you're about -- you're at the end of your 23 presentation. But I was interested in the description 24 of the documentation and traceability that Zach 25 provided. And it sounds good, but people are people.
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57 1 And so what assurances you've got your staff doing it 2 correctly? I mean, do you internally audit as well as 3 the staff been by to check this? And it'd be spot 4 checking but found a few errors and done some 5 corrections and process corrections and decided that 6 it's working well?
7 MR. RAD: Yes. So the programs under the 8 quality assurance program have mandatory audits and 9 surveillance is under the NQA-1 program. And then 10 that same group as well as our internal self-11 assessment program have oversight over the 12 configuration control between design and the licensing 13 basis.
14 MEMBER REMPE: Thank you.
15 DR. SCHULTZ: Chris, one general question.
16 You mentioned -- well, over the last few days, we've 17 been talking about the PRA and its impact on the 18 overall evaluation that has been done. And you 19 mentioned one example of identifying some risk 20 significant items through the PRA recently that caused 21 changes to your testing program.
22 Other examples -- and I have one question.
23 Is there other examples that you may have that have 24 been affected by the work that has been done in the 25 risk and reliability areas? And secondly, have there NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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58 1 also been -- what type of oversight reviews have been 2 done to assure that there's connections between what's 3 been done and the risk evaluation area and the testing 4 program?
5 MR. MAXWELL: The design frankly doesn't 6 include a lot of risk significant components or 7 functions that are also safety related. So the first 8 effort captured the bulk of those. I mentioned the 9 module lift adapter being added later. So I don't 10 have another example from a risk informed position 11 that created additional testing. And then the second 12 part of your questions was?
13 DR. SCHULTZ: Any oversight evaluations 14 that have been done to assure that the overall program 15 -- just to review and assure the overall program has 16 captured what needs to be and to help prioritize the 17 testing functions, the functionality of the test to 18 assure that those things that are most important in 19 the testing program -- the detailed testing program 20 are captured appropriately.
21 MR. MAXWELL: The best method is that we 22 have all of the functions that are risk significant 23 listed in Section 17.4. And we've done a one-for-one.
24 Again, a benefit of having done our pre-operational 25 test abstracts the way we did where we identified the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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59 1 actual function to be tested that we're able to do a 2 one-to-one verification of each of those risk 3 significant functions to verify that they are, in 4 fact, inventoried in an abstract and verified.
5 The staff review of our test program is an 6 example of the oversight to ensure that we do have 7 that alignment between Section 17.4 and Section 14.2, 8 Pre-Operational Testing.
9 DR. SCHULTZ: Good. Thank you.
10 MR. MAXWELL: Yes sir.
11 DR. SCHULTZ: It also was mentioned that 12 you got the benefit of -- with the 12 modules, you got 13 the benefit of gathering substantial data over what 14 one would hope a very quick or very short time frame 15 to validate that the information that you get from the 16 testing program and use that information. And you 17 spoke -- Zach, you spoke to the capability to collect 18 that information and utilize that moving forward.
19 Is that plan pretty much in place, 20 envisioned? Where does that stand at this point?
21 MR. MAXWELL: Well, we have the initial --
22 the in service test program requirements that detail 23 the information that'll be recorded. And this will be 24 gone into a little more detail in the Chapter 3 25 discussion which I'm not sure when that occurs but NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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60 1 later. So I don't have a lot of detail about the in 2 service testing piece.
3 But what I will say is that from a pre-4 operational testing standpoint that absolutely the 5 benefit piece of the 12 where I do the pre-operational 6 test on the first module. I gain instant experience 7 on how to conduct those tests.
8 The issue was or the question was asked 9 earlier how we address if there's a problem with the 10 testing. Well, part of that now I fixed that test for 11 the next 11 modules. And we assume that we'll --
12 well, we know that we'll educate ourselves as we go on 13 to both be more efficient and accurate in our testing.
14 DR. SCHULTZ: The staff is going to 15 address open items that they've identified in the 16 safety evaluation. Any comments that you're prepared 17 to address the status of open item --
18 (Simultaneous speaking.)
19 MR. MAXWELL: I have no open items at this 20 time.
21 DR. SCHULTZ: Okay. Thank you.
22 MEMBER DIMITRIJEVIC: Well, I would like 23 to add something in this connection with PRA and these 24 functions. And I was watching for this crane because 25 there is a different function a component has to NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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61 1 perform what it's designed for and then there is some 2 functions which we are concerning the risk analysis.
3 For the crane function is to move the 4 module from A to B. PRA is concerned that during that 5 movement accidents don't happen. There is normal 6 speed, normal height. And so when I check your test, 7 you do check for those limitations in control.
8 For some functions like these ECCS valves, 9 there is a couple of different functions credited in 10 the PRA. One is they open for the signal and one is, 11 for example, opens without signal in the low delta P 12 conditions or something like that.
13 So when we have multiple considered in the 14 risk analysis, are those multiple functions separated?
15 Like, for example, a good example will be on the ECCS 16 valves opening with the signal and opening without?
17 MR. MAXWELL: Yes, that functionality --
18 that specific functionality is separated. The initial 19 test program will test the function of the valve to 20 open with a signal to open once below the differential 21 pressure threshold of the inadvertent actuation 22 blocking feature but not the condition where there's 23 a malfunction. That's not a piece of the initial test 24 program.
25 MEMBER DIMITRIJEVIC: Okay.
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62 1 MR. MAXWELL: That concludes the 2 presentation for Chapter 14 if there's any questions.
3 CO-CHAIR SKILLMAN: NuScale team, thank 4 you very much. Colleagues around the table, do you 5 have any additional questions for the NuScale team 6 before we move on here? Hearing none, NuScale, thank 7 you.
8 We are in recess for 15 minutes. We're 9 going to take the break early so that we give the NRC 10 staff unbroken time for their portion. Please return 11 at ten minutes after on that clock.
12 (Whereupon, the above-entitled matter went 13 off the record at 9:46 a.m. and resumed at 10:07 a.m.)
14 CO-CHAIR SKILLMAN: We reconvene this 15 meeting, and we welcome Tanny and the NRC staff to the 16 presentation on ITAAC for the NuScale design.
17 Tanny?
18 MR. SANTOS: So, thank you, Dick.
19 First off, I just want to extend my thanks 20 to the Committee members for their accommodating the 21 staff's request to receive the Chapter 14 SER in 22 pieces. It was very helpful to the staff. So, we 23 appreciate your flexibility on that.
24 Again, my name is Tanny Santos. I am the 25 Chapter 14 Project Manager. Sam Lee is the Branch NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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63 1 Chief. He's back there.
2 Listed on this slide are all the technical 3 reviewers who provided input to Chapter 14. As you 4 can see, it is quite a list because of the scope of 5 the information reviewed in this chapter. So, it is 6 a lot. It's not just NRO staff; it is also NRR and 7 NSIR. So, it is really an agency effort for this 8 review.
9 The outline of the staff's presentations 10 is in two parts, similar to what NuScale had 11 presented. SER Section 14.2 is on the initial test 12 program, and that will be led by Taylor Lamb. The 13 second half of the staff's presentation is on 14.3, 14 focused on ITAAC. That will be discussed by myself, 15 Nick Hansing, and BP Jain, to my right.
16 And so, with that, I'll just turn it over 17 to Taylor to begin the discussion on 14.2.
18 MS. LAMB: Hi. My name is Taylor Lamb.
19 I'm in the Quality Assurance Vendor Inspection Branch.
20 I've been working at the NRC for nine years, and I've 21 been the lead technical reviewer for the initial test 22 program. But I would like to note that there was a 23 significantly larger group associated with this 24 review, aside from just me. So, I might point to 25 other people in the room, if you ask any technically-NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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64 1 specific questions.
2 So, with the review, consistent with past 3 submittals, it contained multiple sections, 4 organization and staffing, test procedures, individual 5 test descriptions. This is pretty consistent with 6 what you've seen in the past.
7 Next slide, please.
8 So, the review objectives for this were to 9 review Tier 2, Section 14.2, for completeness and 10 suitability of the development of an ITP by a COL 11 applicant against the guidance in the DSRS Section 12 14.2 and Reg Guide 1.68 by using a risk-informed 13 approach. So, I'd like to focus on the note about the 14 COL applicant developing an ITP.
15 The regulations in 52.47 for Design 16 Certification Application do not stipulate 17 requirements for pre-operational and startup testing.
18 However, 52.79(a)(28) for a COL application does 19 specify requirements for pre-operational and startup 20 testing. The guidance in Reg Guide 1.68 goes over 21 some more specific requirements, as was discussed 22 earlier.
23 So, in order to accomplish the review, 24 especially the risk-informed approach of the review, 25 we utilized SECY-11-0024, the use of risk insights to NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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65 1 enhance the safety focus of small modular reactor 2 reviews in development of our guidance. So, the 3 revised ITP review, it focuses on providing reasonable 4 assurance that the risk-significant structure system 5 and component functions are tested, and a test 6 abstract adequately addressed the design 7 functionality. So, we're just looking at the design 8 functionality of the test abstracts that we did 9 review. So, from that, the DSRS, Section 14.2 was 10 developed, and it provided the general guidance for 11 the NRC staff to review the proposed ITP.
12 Next slide.
13 With that being said, going back to what 14 I stated earlier, the DSRS even notes in the 15 introduction that there is no requirement for a design 16 certification applicant to provide an ITP submitted 17 under 10 CFR Part 52, Subpart B. But the staff did 18 review this, specific test abstracts, under DSRS 19 Section 14.2 and Reg Guide 1.68.
20 So, in order to determine which test 21 abstracts the staff would review in this modified 22 approach, we utilized Table 17.4-1, the D-RAP SSC 23 functions, categorizations, and categorization basis, 24 which stipulated the risk-significant system functions 25 that, I suppose, are -- I'll leave it at that.
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66 1 So, with that, we proposed this to 2 NuScale. NuScale staff, they came back, specifically 3 requested a larger scope of review that included 4 additional test abstracts that might not have been 5 identified via the D-RAP. They discussed a larger 6 scope, and they mentioned the reactor-building crane 7 system, for instance.
8 The NRC approved only those test abstracts 9 listed in 14.2-1 of the SER. so, we separated out the 10 ones that we did review and would approve, and the 11 other test abstracts that are not going to be approved 12 are in Table 14.2-2 of the SER. So, those test 13 abstracts should be addressed by, must be addressed by 14 the COL applicant, since 52.79(a)(28) requires that 15 they provide plans for pre-operational and startup 16 testing.
17 MEMBER BLEY: I got a little confused in 18 your description. When the Applicant requested that 19 you review additional tests, did you review those?
20 MS. LAMB: Yes.
21 MEMBER BLEY: Okay. And they're among the 22 ones you've approved?
23 MS. LAMB: Yes.
24 MEMBER BLEY: Okay.
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67 1 of the SER.
2 CO-CHAIR SKILLMAN: Taylor, does the 3 absence of direction to create an ITP in Part 52, Sub 4 B, constitute a deficiency in the regulation? It 5 sounds like you've gone through an awful lot of effort 6 to create a path forward where one is not prescribed.
7 I'm not an advocate of more regulation, but I'm just 8 wondering if there's a hole in Part 52.
9 MS. LAMB: I do not think that I would be 10 the appropriate individual to answer that question.
11 But I will say that, as the DSRS states, the initial 12 test program is typically reviewed in the design 13 certification stage in order to better prepare for a 14 COL application. I'm not sure if that clarifies the 15 question, but if Kerri Kavanagh --
16 MS. KAVANAGH: Hi.
17 CO-CHAIR SKILLMAN: Hi, Kerri.
18 MS. KAVANAGH: How are you?
19 CO-CHAIR SKILLMAN: Well, thank you.
20 MS. KAVANAGH: This is Kerri Kavanagh.
21 I'm the Chief of the Quality Assurance Vendor 22 Inspection Branch, and now in NRR.
23 You've got to remember that this is for 24 design certification, not the testing of a plant. But 25 most designers in the past, the AP1000s, the ESBWRs, NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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68 1 they wanted as much to be approved in the design 2 certification phase, so that their COL applicants 3 would not have to create that kind of information, 4 because they're the design authority. NuScale 5 followed suit.
6 We do not believe that the regulations are 7 deficient. It's just it's not a requirement in a 8 design cert. It's just a practice that has been done 9 by most vendors for a design certification.
10 CO-CHAIR SKILLMAN: Thank you. Okay.
11 MEMBER BLEY: And the review would have 12 been done in the COL stage under --
13 MS. KAVANAGH: It will still be done in 14 the COL stage.
15 CO-CHAIR SKILLMAN: Go ahead, Taylor.
16 Continue, please.
17 MS. LAMB: Okay.
18 CO-CHAIR SKILLMAN: Thank you.
19 MS. LAMB: So, if the design certification 20 is approved, the staff would recommend that the 21 certification rule include clarifying language that 22 those other test abstracts in 14.2-2 of the SER, that 23 they're outside the scope of the certified design.
24 Next slide, please.
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69 1 open item linked to Test Abstract 14.2-47, "Emergency 2 Core Cooling System Test No. 47". It's Open Item 3 03.09.06-1. So, that is in Chapter 3. Until that 4 item is resolved, we will leave open Test Abstract 5 14.2-47.
6 CO-CHAIR CORRADINI: Can you tell us a bit 7 more?
8 MS. LAMB: Since that is a Chapter 3 item, 9 Tom Scarbrough can speak to that.
10 MR. SCARBROUGH: Good morning. I'm Tom 11 Scarbrough.
12 Yes, in Section 3.9.6, we have an open 13 item for the ECCS valves. Under 50.43(e), NuScale is 14 required to have a design demonstration of this new 15 ECCS valve system. They plan to do demonstration 16 testing in June for that, and we'll be there to 17 monitor that. And we will write a report about that.
18 And once that's all complete, then we'll be able to 19 determine if we can close that open item. Until then, 20 we have kept it open, and they're tracking it in 21 Chapter 14 as well.
22 CO-CHAIR CORRADINI: Thank you.
23 MR. SCARBROUGH: Okay. Thank you.
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70 1 proposed markups to DCA Part 2, Tier 2. Therefore, we 2 have confirmatory item 14.2-1 that will be tracking 3 the incorporation of those proposed changes in future 4 revision of the DCA.
5 With that, the staff concludes, using the 6 information presented in the DCA, and pending the 7 confirmatory and open items, that the Applicant has 8 demonstrated compliance with the NRC regulations and 9 guidance.
10 MR. SANTOS: So, with that, I'd like to 11 move on to SER Section 14.3, ITAAC. This CR section 12 reviews Tier 1 information, all the Tier 1 13 information, including definitions, site parameters, 14 interface requirements, as well as the ITAAC tables.
15 So, the regulatory finding in 14.3 that 16 the staff is making is with regard to 52.47(b)(1) that 17 I think was mentioned earlier in the presentation.
18 This is the requirement that the ITAAC be necessary 19 and sufficient and provide reasonable assurance that, 20 if the inspection test analyses are performed and the 21 acceptance criteria are met, that the plant will be 22 designed and operated in accordance with the design in 23 the NRC's regulations.
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71 1 documents the staff had used. One, of course, is the 2 Standard Review Plan, Section 14.3. The second is the 3 set of standardized ITAAC that the NRC provided 4 NuScale. I think it was referred to in NuScale's 5 presentation back in 2016, provided them a set of 6 draft standardized ITAAC that could be submitted as 7 part of a Design Certification Application. And as I 8 said earlier, NuScale did employ many of those ITAAC 9 in their application.
10 And the third document I'd like to discuss 11 is relatively new. So, I want to spend some time on 12 it. It is SECY-19-0034, which was just issued in 13 April, April 8th I believe. This title is approving 14 design certification content and describes some new 15 general principles for how Tier 1 information should 16 be reviewed as part of a design certification.
17 Now many of the principles described in 18 the SECY are similar to what is in SRP 14.3 now, but 19 there are three new principles that this SECY 20 describes, and I'd like to point these out to you on 21 these slides, these three bullets here.
22 One is that Tier 1 information should be 23 typically at a qualitative or functional level of 24 detail. Tier 1 should also not include any detailed 25 information that would require NRC approval for a NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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72 1 departure from the certified design that would have 2 minimal safety significance. And lastly, the use of 3 numeric information in Tier 1 to try to be minimized.
4 So, the general theme for these three new 5 principles are try to emphasize the importance of 6 avoiding any unnecessary detail in Tier 1, with 7 "unnecessary" implying that an applicant would have to 8 come to the NRC to request a departure or an exemption 9 from something that has a minimal safety significance.
10 CO-CHAIR CORRADINI: Is this a nice way of 11 saying a lesson learned?
12 MR. SANTOS: Yes, sir, this is, I think, 13 a lot from Vogtle --
14 CO-CHAIR CORRADINI: Yes. Fine.
15 MR. SANTOS: -- information from Vogtle, 16 yes.
17 CO-CHAIR CORRADINI: Thank you.
18 MR. SANTOS: You're welcome.
19 As I said earlier, this SECY was just 20 issued in April. And given the timeframe of that, the 21 staff has not really had an opportunity to apply all 22 of these new principles to all of the Tier 1 23 information in the NuScale application, but we plan to 24 do that as part of our phase 4 review.
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73 1 different question.
2 MR. SANTOS: Sure.
3 CO-CHAIR CORRADINI: You have a number of 4 open items.
5 MR. SANTOS: Yes.
6 CO-CHAIR CORRADINI: Would some of these 7 go away, given this?
8 MR. SANTOS: I'm not sure because the 9 number of open items has to do with exemption 10 requests --
11 CO-CHAIR CORRADINI: Okay.
12 MR. SANTOS: -- but they may not impact 13 the --
14 CO-CHAIR CORRADINI: Okay.
15 MR. SANTOS: But it, theoretically, could 16 reduce the amount of information in Tier 1. If it was 17 agreed to that there is some detail in there that 18 could be removed based on this, there could be a 19 reduction in Tier 1 information and/or ITAAC.
20 CO-CHAIR CORRADINI: Okay. Thank you.
21 MR. SANTOS: Yes. So, like I said, we 22 haven't applied this to all of NuScale's application, 23 but there is an attachment to this SECY that 24 describes, as an example, how these new principles 25 could be applied or how these new principles would be NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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74 1 applied to the NuScale review for the structural 2 integrity review only. So, that's an attachment to 3 the SECY paper to come. So, have it done in that 4 area.
5 CO-CHAIR CORRADINI: We received this a 6 week ago, yes. No, two weeks ago. I didn't see the 7 attachment. I have the 10-page, it was the 10-page 8 SECY. Was there an attachment to that? I only had 9 the SECY.
10 MR. SANTOS: Yes, I think there should be 11 an enclosure or an attachment to the --
12 CO-CHAIR CORRADINI: You got it? Okay.
13 then, that's my fault then. Never mind.
14 MR. SANTOS: Okay.
15 CO-CHAIR SKILLMAN: Keep going, Tanny.
16 MR. SANTOS: Okay. So, the next slide.
17 The rest of the staff's presentation is 18 really going to focus on the rest of the SER section 19 in 14.3, but only those that have open items. So, 20 listed here are the six sections of the staff's SER 21 that do not have any open items. So, we don't plan to 22 have any additional discussion or go into any detail 23 about these sections. I will go on with the other 24 sections.
25 CO-CHAIR SKILLMAN: So, Tanny --
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75 1 MR. SANTOS: Yes, sir?
2 CO-CHAIR SKILLMAN: What does that mean?
3 Does that mean that your review of the proposed ITAAC 4 by NuScale is without comment --
5 MR. SANTOS: No.
6 CO-CHAIR SKILLMAN: -- or without 7 suggestion for change?
8 MR. SANTOS: No. There may be, for 9 example, confirmatory items that need to be closed in 10 some of these sections. And the other sections may 11 not have open items, but no conclusion can be met 12 because it may rely on information on another section 13 that has an open item. So, it's just the way that the 14 staff's SER is organized, the ITAAC that falls under 15 these systems has no specific open items in them.
16 There may be confirmatory items associated with them, 17 though.
18 CO-CHAIR SKILLMAN: Fair enough. Okay.
19 Thank you.
20 MR. SANTOS: Okay? So, the first section 21 I'd like to discuss is 14.3.1. This section discusses 22 the selection criteria for Tier 1. I think NuScale 23 described the first principles approach, but the staff 24 has specifically excluded from its review the first 25 principles approach that NuScale is using for NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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76 1 identifying Tier 1 in ITAAC. Their approach is very 2 similar to an approach defined by NEI in 1502 in an 3 NEI white paper. The staff has not endorsed these 4 approaches. We provided comments and discussions and 5 meetings with NEI, but we have not formally endorsed 6 them. So, the staff is not taking a position on this 7 first principles approach in their application.
8 It's described in Section 14.3.2 of their 9 Tier 2 application. So, that would mean that, if and 10 when this were to go to design certification 11 rulemaking, it would not, this section would not be 12 incorporated by reference into the rule because the 13 staff is not taking a position on this particular 14 methodology. Okay.
15 MEMBER BLEY: Ignoring the methodology, 16 you do take positions on the results of the applying 17 the methodology?
18 MR. SANTOS: Yes, sir, we do make a 19 finding on the ITAAC themselves, but not the method 20 for identifying what's in the ITAAC or Tier 1.
21 CO-CHAIR CORRADINI: I mean, this leads to 22 a bunch of ancillary questions. So, in the past 23 design certifications did the past applicants use this 24 methodology or their own individual methodology?
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77 1 has been used in other applications.
2 CO-CHAIR CORRADINI: Okay. Fine.
3 MR. SANTOS: But I could be wrong. But I 4 don't believe this is --
5 MR. WELCH: This is Chris Welch.
6 It hasn't, Tanny.
7 MR. SANTOS: Okay. Thank you, Chris.
8 CO-CHAIR SKILLMAN: So, what does this, if 9 you will, exclusion from incorporation by IBR, do to 10 an applicant? What is the consequence of this 11 position?
12 MR. SANTOS: I don't believe it -- I think 13 the ITAAC would still have to be closed because the 14 staff is making a finding on the ITAAC and the 15 information in Tier 1, not the methodology used to 16 identify what Tier 2 information rises to the level of 17 being Tier 1. There would be an impact. The 18 applicants would still have to follow the Tier 1/Tier 19 2 information that's been approved. If they want to 20 make a change to Tier 1 or Tier 2, follow existing 21 processes.
22 CO-CHAIR CORRADINI: So, what you're 23 saying is how they came to a conclusion you're not 24 going to say positive or negative?
25 MR. SANTOS: Right.
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78 1 CO-CHAIR CORRADINI: You're just going to 2 look at the conclusion and see if it's reasonable?
3 MR. SANTOS: Yes.
4 CO-CHAIR CORRADINI: Fine.
5 MR. SANTOS: I think there are plans by 6 NEI to later submit an update to this guidance 7 document for NRC to maybe eventually approve later.
8 I think that is in the works, but I don't have the 9 schedule for that. But there are plans for that, I 10 believe.
11 CO-CHAIR SKILLMAN: Let me see if I 12 understand it. You're saying NuScale's approach as a 13 process is not endorsed by the NRC, and therefore, it 14 may not be IBRed. But the ITAAC that it identifies 15 must be executed?
16 MR. SANTOS: Yes, the ITAAC itself would 17 be certified.
18 CO-CHAIR SKILLMAN: Got it. All right.
19 Now I understand the logic. Thank you.
20 MR. SANTOS: Okay. The last bullet just 21 states that the remaining Sections 14.3.2 through 22 14.3.13 document the staff's review of the ITAAC or 23 point to another SER section where they're evaluated 24 and a conclusion is found.
25 So, there are two open items in 14.3.1.
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79 1 The first is an open item initially identified from 2 Chapter 17. It has to do with the Design Reliability 3 Assurance Program. And in SECY-18-0093, the staff 4 actually sent a paper to the Commission recommending 5 that the ITAAC to verify the effectiveness of the 6 D-RAP be discontinued. And so, NuScale did not 7 provide an ITAAC for the D-RAP. But the staff is 8 still waiting for the Commission to make a decision on 9 this paper. So, once that is provided to us, if the 10 decision agrees with the staff, then this open item 11 can be closed. But if the Commission decides that 12 ITAAC for D-RAP should still be implemented, staff 13 would be requesting that NuScale provide an ITAAC for 14 this, similar to what was done for other applications.
15 CO-CHAIR CORRADINI: Well, just for 16 everybody, we discuss this when we talk about Chapter 17 17.
18 MR. SANTOS: Thank you.
19 The second open item has to do with a 20 recently-issued RAI that the staff provided just last 21 week to NuScale in a draft form. Similar to what the 22 staff did for the APR1400, the staff reviewed the Tier 23 1 information, focusing on the ITAAC themselves, and 24 review it for clarity and format to make sure that 25 there's no ambiguous acceptance criteria, to make sure NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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80 1 that the design commitment, inspection test analysis, 2 and acceptance criteria are similar in scope, to 3 minimize any possible misunderstand or 4 misinterpretation of the language.
5 Based on that review, the staff issued an 6 RAI requesting NuScale make some language changes to 7 the Tier 1 information and ITAAC. And so, again, a 8 similar request and review was done for the APR1400.
9 Staff still might well engage with NuScale on that 10 because it was just issued last week. So, it's still 11 an open item for the staff's review.
12 CO-CHAIR SKILLMAN: So, is this an 13 administrative item or is this a technical item?
14 MR. SANTOS: It could be technical/legal, 15 to later down the line avoid any misunderstandings or 16 discrepancies on what does this new language mean. If 17 there is language in an ITAAC that could be ambiguous 18 or interpreted multiple ways, this is to try to 19 prevent that from happening by making sure the 20 language is clear, unambiguous, and avoid any problems 21 down the line.
22 CO-CHAIR CORRADINI: And the lawyers are 23 going to solve it?
24 MR. SANTOS: It is a lesson learned 25 from --
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81 1 CO-CHAIR CORRADINI: And the lawyers are 2 going to solve this?
3 MR. SANTOS: They are providing us advice.
4 CO-CHAIR CORRADINI: Okay.
5 MR. SANTOS: I will say that.
6 Okay. So, the next aspect of 14.3.1 is 7 the discussion of interface requirements. The Tier 1 8 information has an interface requirement regarding the 9 failure of a structure that's not within the scope of 10 the certified design, not causing any of the seismic 11 Category I structures that are within the scope of the 12 design to fail.
13 Now this specific interface requirement 14 will be evaluated by the staff in Chapter 3. But 15 there is another requirement in 52.47(a)(26) that 16 states that this interface requirement must be 17 verifiable through ITAAC, right? So, NuScale did 18 provide two ITAAC to verify that, as built, Non-19 Seismic Category I SSCs will not impair the ability of 20 Seismic Category I SSCs. But the staff can't make a 21 finding that this particular requirement has been met 22 yet because of an open item with one of these two 23 ITAAC that BP will discuss in his part of the 24 presentation.
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82 1 plant or a 3-dimensional model, how can you satisfy 2 this ITAAC? I mean, usually, we have done this in the 3 past by a walk-down of the plant and saying that's 4 Seismic II. It's over I. It can fall and hit.
5 MR. SANTOS: Right.
6 MEMBER BLEY: Then, we would have to fix 7 that. Do you have 3D models that you can look at?
8 MR. SANTOS: Not 3D models, but there is 9 a standardized ITAAC that staff provided --
10 MEMBER BLEY: So, you can approve the 11 ITAAC?
12 MR. SANTOS: There's a standardized ITAAC 13 that addresses, I believe, this.
14 MEMBER BLEY: Okay. But the ITAAC cannot 15 be fulfilled until the plant is in place?
16 MR. SANTOS: Yes, until it is built, yes.
17 MR. WELCH: That's correct. This is Chris 18 Welch. It's an as-built ITAAC.
19 MR. SANTOS: Thank you, Chris.
20 And with that, I'll turn it over to BP to 21 talk about this and Section 14.3.2.
22 MR. JAIN: All right. So, we reviewed the 23 structural integrity of the reactor, radioactive 24 waste, and control building, Section 14.3.2 in the 25 SER. And the purpose, the scope of a review, was to NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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83 1 ensure, to make sure that the ITAAC will ensure the 2 final as-built plant structure is built in accordance 3 with the certified design. That was the high-level 4 focus.
5 In reviewing it, we find that the 6 acceptance criteria for the ITAAC for these three 7 buildings is sort of incomplete in the sense that, in 8 order to meet the goal, it lacks certain details. For 9 example, it does not talk about reconciliation of the 10 deviation between the as-built loads and the assumed 11 constructed load. So, there is a deviation in what 12 you are assume in the design and what you actually put 13 in. So, how to reconcile is not talked about.
14 CO-CHAIR CORRADINI: Is a deviation 15 another way of saying tolerances? I don't understand 16 what a deviation is.
17 MR. JAIN: It doesn't actually have to be 18 a tolerance. It has to be bigger than that. Let's 19 say you're designing the equipment and you assume 100 20 pounds weight in your design. And then, you actually 21 put the equipment back in there and find it's 500 22 pounds.
23 CO-CHAIR CORRADINI: So, it has to be 24 outside of the specified tolerances --
25 MR. JAIN: Yes, yes.
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84 1 CO-CHAIR CORRADINI: -- is considered a 2 deviation?
3 MR. JAIN: Sure.
4 CO-CHAIR CORRADINI: Okay. Fine. Okay.
5 Got it.
6 MR. JAIN: So, if you take the cumulative 7 effect of the change in the loads and our 8 configuration of the plant, that, in fact, is not 9 being addressed in the acceptance criteria. Because 10 you can look at it individually, like we talked about, 11 100 pounds versus 500 pounds. But if you do thousands 12 of those components, it would change those loads. The 13 cumulative effect could be, does need to be addressed.
14 And that has not been in the acceptance criteria.
15 The same thing when you do the demand 16 analysis with this new configuration and the as-built 17 load. You need to address it to make sure that the 18 seismic response of the building is not adversely 19 affected and is bounded still by the certified design 20 because that feeds into the system analysis, the 21 seismic response. So, that aspect is not being 22 addressed in the acceptance criteria.
23 So, those are the basic steps/issues, and 24 we have discussed this with NuScale. And my 25 understanding is that they'll incorporate or they were NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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85 1 in agreement with the staff's findings.
2 CO-CHAIR CORRADINI: So, it's being fixed?
3 MR. JAIN: That is what I heard last time 4 when we spoke about it two weeks ago or so.
5 CO-CHAIR SKILLMAN: Thank you. Keep on 6 going.
7 MR. JAIN: The second open item has to do 8 with the seismic interactions, the Non-Seismic 9 Category Is with the Seismic Category I structures.
10 And this one, the views on this open item, it's really 11 twofold. One, the reactor building ITAAC, that 12 matches with the standardized ITAAC, what the staff 13 proposed in their April 6th letter. But, for the 14 control room building, it does not. For whatever 15 reason, NuScale knows better. So, we discussed that 16 anomaly, if you will, and they said they will fix it; 17 they will make it consistent with the reactor building 18 and the standardized ITAAC. But staff still, when we 19 saw it, you know, that's what our review finding was.
20 CO-CHAIR SKILLMAN: So, are these going to 21 be construction-stage ITAAC for closeout?
22 MR. JAIN: Well, these are not -- this is 23 you do after you have as-built. You have to do it as 24 you go along.
25 CO-CHAIR SKILLMAN: As the construction --
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86 1 okay.
2 MR. JAIN: And then, at the end of the 3 construction, you have to reconcile the deviations --
4 CO-CHAIR SKILLMAN: Okay.
5 MR. JAIN: -- in a global sense.
6 CO-CHAIR SKILLMAN: I think the answer to 7 my question is, yes, these are construction-stage 8 ITAAC that get closed out when there's confirmation 9 that the open item has been satisfactorily addressed?
10 MR. JAIN: Right, on a global basis, 11 though.
12 CO-CHAIR SKILLMAN: Yes. Okay. And are 13 you comfortable that NuScale understands this?
14 MR. JAIN: Yes, from the discussion we had 15 on the May 8th telecon, that's our understanding.
16 CO-CHAIR SKILLMAN: Okay. Thank you.
17 MR. JAIN: Okay.
18 MR. SANTOS: Next is 14.3.3, and that will 19 be presented by Nick Hansing.
20 MR. HANSING: Good morning. My name is 21 Nick Hansing. I was the lead reviewer for Section 22 14.3.3, "ITAAC for Piping Systems and Components".
23 I wanted to highlight one open item on the 24 following two slides. It's entitled, "NPM Valve 25 Installation Verification ITAAC". The ITAAC, as NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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87 1 mentioned earlier, you need to satisfy 2 10 CFR 52.47(b)(1), to provide reasonable assurance 3 that, in this case the NuScale power module, NPM, 4 safety-related valves are constructed and will operate 5 in conformity with the design certification.
6 The NPM valve installation verification 7 ITAAC will require a walk-down inspection of the 8 emergency core cooling system, ECCS, valves; 9 containment isolation valves, and decay heat removal 10 system actuation valves, to ensure that the valves 11 will not be prevented from performing their safety 12 functions.
13 Next slide, please.
14 CO-CHAIR SKILLMAN: Nick, before you move 15 on --
16 MR. HANSING: Yes?
17 CO-CHAIR SKILLMAN: I've got the Safety 18 Evaluation, and I see your Confirmatory Item 14.3.3-1, 19 but also 14.3.3-2 and 3.3-3, having to do with the 20 safety valves.
21 MR. HANSING: Yes.
22 CO-CHAIR SKILLMAN: So, you're addressing 23 just Open Item 3-3-1. How about the other two?
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88 1 acceptable. So, we're just simply tracking those for 2 incorporation into the next version of the DCD.
3 CO-CHAIR SKILLMAN: Understand. Thank 4 you. All right.
5 MEMBER SUNSERI: Is this one of these 6 examples, like NuScale talked about, where they had 7 their initial test program requirement, and then, an 8 ITAAC requirement? I mean, this is an initial startup 9 program, right, or re-operational startup program?
10 MR. HANSING: I believe --
11 MEMBER SUNSERI: So, one test satisfies 12 two requirements?
13 CO-CHAIR CORRADINI: Yes, I don't 14 understand. Is it that it's physically where it's 15 supposed to be or is it that it's been tested? That's 16 what I -- I was reading your words. Is it both?
17 MR. HANSING: So, this ITAAC specifically 18 is for a walk-down inspection of the as-built 19 components to the --
20 CO-CHAIR CORRADINI: But it's physically 21 where it's supposed to be?
22 MR. HANSING: Physically where it's 23 supposed to be, its router where it needs to be.
24 There's accessibility, which I'll get to in the next 25 slide --
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89 1 CO-CHAIR CORRADINI: Okay.
2 MR. HANSING: -- about some of those 3 specific aspects.
4 So, the walk-down inspection will verify 5 installation of the valves previously mentioned and 6 their hydraulic lines, consistent with the 7 specifications for geometric configuration, 8 orientation, accessibility, and line routing, such 9 that each valve can perform its safety functions.
10 So, together with the current ITAAC, the 11 NPM valve installation verification ITAAC will provide 12 reasonable assurance that the ECCS valves, CIVs, and 13 DHRS actuation valves will operate properly to allow 14 core cooling and provide containment isolation under 15 design basis conditions.
16 And the NRC staff held a public 17 teleconference with NuScale on May 8th, 2019, to 18 discuss the path forward to a resolution of this open 19 item.
20 CO-CHAIR SKILLMAN: And what was the 21 result of that conversation?
22 MR. HANSING: NuScale intends to submit 23 ITAAC to resolve this open item.
24 CO-CHAIR SKILLMAN: Thank you.
25 MR. HANSING: You're welcome.
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90 1 Any additional questions?
2 (No audible response.)
3 MR. SANTOS: Okay. So, 14.3.6 reviews the 4 Tier 1 and ITAAC related to electrical systems. This 5 includes equipment qualification for seismic and harsh 6 environments, containment electrical penetrations and 7 lighting.
8 This section has two open items. The 9 first was originally identified as a Chapter 8 open 10 item. It has to do with NuScale requesting exemptions 11 from GDC 17 and 18. So, GDC 17 requires that, well, 12 let's see, systems -- onsite and offsite electrical 13 power systems be provided to permit functioning of 14 SSCs that are important to safety. GDC 18 requires 15 that electrical power systems important to safety be 16 designed to permit appropriate inspection and testing.
17 So, as I said, NuScale requested 18 exemptions from these two GDC. The staff is still 19 reviewing these exemptions. And so, if the exemptions 20 are approved, the ITAAC proposed by NuScale would be 21 sufficient and this open item could be closed. But if 22 these exemptions are not approved, any equipment used 23 to verify the GDC would need to have an appropriate 24 ITAAC to verify the functionality.
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91 1 nest of chapters that are all related to this.
2 MR. SANTOS: Yes, I agree.
3 MEMBER BLEY: Who's actually watching it 4 -- watching it? -- driving the show on this? Is it 5 Chapter 8 people, electricals?
6 MR. SANTOS: Yes. Well, the individual 7 exemptions that are reviewed in other chapters would 8 that, and 14 would track the --
9 MEMBER BLEY: It needs a coordinator of 10 this?
11 MR. SANTOS: Yes, right.
12 MEMBER BLEY: Who is the coordinator, is 13 what I was asking.
14 MR. SANTOS: For? For the exemptions, all 15 the specific exemptions?
16 MEMBER BLEY: Yes.
17 MR. SANTOS: I guess that would be my 18 Branch, us.
19 MEMBER BLEY: Oh, okay. Not the 20 electricals?
21 MR. SANTOS: Well, they're doing the 22 review, but tracking the actual exemptions and 23 ensuring they're closed out is a licensing -- we'll 24 take the lead for that.
25 MEMBER BLEY: Okay.
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92 1 MR. SANTOS: But the actual review for the 2 exemption approvals or not would be the technical 3 staff.
4 CO-CHAIR CORRADINI: So, this would be 5 handled in the next phase of the review? That is, 6 once the Open Item 8.3.1 is closed --
7 MR. SANTOS: Then, it would be closed, 14, 8 yes.
9 CO-CHAIR CORRADINI: Okay. Then, all the 10 other things would cascade down?
11 MR. SANTOS: Yes. There's similar, other 12 similar examples like that.
13 CO-CHAIR CORRADINI: Okay. Fine. Yes.
14 MR. SANTOS: Yes, right.
15 CO-CHAIR CORRADINI: No, Dennis as well --
16 okay, thank you.
17 MR. SANTOS: Right. So, the second open 18 item in this section has to do with just an editorial 19 error the staff found in one of the Tier 2 tables.
20 Table 14.3-1 has some additional information about how 21 an ITAAC is performed or closed out. And there's an 22 incorrect reference to a Chapter 8 section, a Tier 2, 23 Chapter 8, section there that the staff identified, 24 and NuScale agreed should be corrected. So, once 25 that's done, that open item could be closed.
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93 1 The next section is 14.3.8, and that has 2 to do with radiation protection ITAAC and Tier 1. So, 3 again, there's two open items here, but they're both 4 related to the same issue. It's just two different 5 RAIs that led to these two open item numbers. That 6 has to do with borated polyethylene shielding.
7 And now, Tier 1, Table 3.11-1 described 8 reactor building shield wall geometry. It's not the 9 ITAAC table, right? But the ITAAC table has --
10 there's an ITAAC with an acceptance criteria that 11 references this table by saying, no, the thickness of 12 the reactor building shielding barriers is greater to 13 or equal than that value found in 3.11-1.
14 So, what's happened is the bio-shield 15 design has changed. Originally, there was borated 16 polyethylene in the bio-shield. And so, there was an 17 item in Table 3.11-1 for it. When the borated 18 polyethylene shielding was removed from the design, it 19 was removed from the table. But, then, subsequently, 20 it was reincorporated back into the bio-shield design, 21 but not put into the table. So, the staff would be 22 looking for an entry into the 3.11-1 table for that 23 ITAAC acceptance criteria.
24 CO-CHAIR SKILLMAN: Tanny, this is the 25 thing that I was speaking about in my opening NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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94 1 comments, whereas the design is maturing, it is 2 essential to keep the ITAAC --
3 MR. SANTOS: Right.
4 CO-CHAIR SKILLMAN: -- current with 5 inappropriate change.
6 MR. SANTOS: Right.
7 CO-CHAIR SKILLMAN: I mean, let's give 8 them credit.
9 MR. SANTOS: Yes.
10 CO-CHAIR SKILLMAN: What they're trying to 11 do is to protect actually the line-of-sight module 12 people on the other side with this curtain, and also 13 protect against hydrogen.
14 So, here's an exact case where we see the 15 design evolving and the essential nature of keeping 16 the critical licensing documentation consistent.
17 MR. SANTOS: Correct.
18 CO-CHAIR SKILLMAN: To me, that's exactly 19 what this is, and just ensuring that it is accounted 20 for is the important piece.
21 MR. SANTOS: Right. Thank you for that.
22 Okay. The next section is 14.3.9 on 23 "Human Factors Engineering". So, the focus of the 24 staff's review here is to ensure that the as-built 25 human system interface for the MCR is consistent with NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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95 1 that resulting from the HFE design process.
2 And so, that led to an open item that was 3 originally identified in Chapter 18. The staff's 4 concern here is ensuring that the insights from the 5 entire human factors engineering design process are 6 appropriately applied to the as-built human system 7 interface in the main control room. So, the ITAAC 8 provided in NuScale's application had a design 9 commitment for the main control that did not include 10 changes to the HSI design that could occur after the 11 integrated system validation phase. Staff has had 12 subsequent discussions with NuScale since that was 13 identified, and I think we've agreed to some revised 14 ITAAC language that would address the staff's concern.
15 So, I anticipate this open item being closed in the 16 next phase.
17 The second open item has to do with the 18 staff's review of ITAAC looking at the system-level 19 displays, alarms, and controls. There is an ITAAC to 20 verify this for the main control room, but there is 21 not an ITAAC for these displays, alarms, and controls 22 for the remote shutdown station. So, NuScale has 23 submitted a request for an exemption from GDC 19 that 24 requires equipment outside the control room be capable 25 to bring the reactor to cold shutdown if the main NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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96 1 control room is evacuated. If this exemption request 2 is approved, the staff agrees that no ITAAC would be 3 needed because the remote shutdown station is not 4 being credited for meeting GDC 19.
5 CO-CHAIR SKILLMAN: How can it not be 6 credited? I mean, it's identified in their 7 documentation on 7.1.1.2.3. They credit the shutdown 8 station as the go-to when you have to evacuate the 9 control room.
10 MR. SANTOS: But I think they had a 11 subsequent -- in March of this year, they submitted 12 another docketed letter requesting an exemption from 13 GDC 19 that provides markup to Tier 1 and Tier 2, 14 requesting exemption for GDC 19.
15 CO-CHAIR SKILLMAN: I guess I'm -- what's 16 the right word? -- I'm confused. I mean, they've 17 taken credit for the RSS. It seems to be what we 18 would have called your backup, your remote shutdown 19 station.
20 MR. SANTOS: Yes.
21 CO-CHAIR SKILLMAN: It's protected on 22 purpose. Why would they seek an exemption?
23 MR. GREEN: This is Brian Green, Human 24 Factors.
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97 1 there will still be an RSS that will provide 2 information to the operators in the case that they 3 need to go there. However, there will not be control 4 functions at that station; rather, manual actions at 5 the MPS cabinets would be how the operators would 6 perform that function. And this is under review in 7 the exemption request.
8 CO-CHAIR SKILLMAN: And then, would the 9 exemption request include changes in the documentation 10 in their Chapter 7? I would guess so.
11 MR. SANTOS: There are changes to 7. I 12 don't remember -- I think there are changes to 7 in 13 there.
14 MEMBER BLEY: I'm also a little confused 15 because, even if you don't control with switches at 16 the RSS, you're using those instruments to coordinate 17 the manual operations. And why wouldn't you need an 18 ITAAC for the instruments, whether or not you have 19 controls there?
20 MR. GREEN: Yes, I'm not the reviewer 21 conducting that review. So, I can't get into too many 22 of the details. But these are the things that staff 23 is considering as part of this exemption request.
24 CO-CHAIR CORRADINI: Can we get the 25 Applicant to say something?
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98 1 MEMBER BLEY: He's standing up.
2 CO-CHAIR CORRADINI: Oh, good. I 3 recognize him.
4 MR. MAXWELL: So, there are no manual 5 operations --
6 CO-CHAIR CORRADINI: And who are you 7 first?
8 MR. MAXWELL: Sorry. Chris Maxwell, 9 NuScale Power.
10 MEMBER BLEY: Chris, that's for the record 11 when you're not up here.
12 MR. MAXWELL: The equivalent of GDC 19 13 credit is taken for actuations in the MPS rooms 14 themselves that will trip the reactor, isolate 15 containment, initiate DHRS.
16 First, let me back up one step and say 17 that we have switches dedicated to that in the control 18 room. So, the expectation is the operators perform 19 that action prior to evacuating the control room to 20 begin with, but, then, we still provide those 21 actuation switches at the MPS cabinets. That 22 establishes safe shutdown of the modules with no 23 further operator action. So, when the operators take 24 over the remote shutdown station, they do have 25 indications there, but they don't use those NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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99 1 indications to direct manual actions. It's really 2 balance of plan beyond that point.
3 CO-CHAIR SKILLMAN: Well, let me take this 4 on because the text in your application, at least in 5 my mind, is crystal clear. "The RSS provides an 6 alternate location to monitor and to operate." And 7 then, later on three or four paragraphs, "The MPS 8 manual isolation switches are mounted in a Seismic I 9 enclosure. The MCS equipment in the RSS provides an 10 independent alternative shutdown capability that is 11 physically and electrically separate."
12 So, I don't know why you would be asking 13 for an exemption from 19 when you're actually 14 fulfilling it.
15 MR. MAXWELL: That wording has been 16 revised.
17 CO-CHAIR SKILLMAN: 10-4. Okay. This is 18 Revision 2.
19 MR. MAXWELL: Yes, sir.
20 MEMBER BLEY: Well, maybe not 10-4 all the 21 way around the table.
22 CO-CHAIR SKILLMAN: Well, okay, Skillman, 23 10-4.
24 (Laughter.)
25 Go ahead, Dennis.
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100 1 MEMBER BLEY: I agree changes there would 2 make things consistent, but what Chris described is 3 how they expect things to happen.
4 CO-CHAIR SKILLMAN: Yes. I'm just 5 saying --
6 MEMBER BLEY: In a real-world event that 7 drives you out of the control room, maybe they don't 8 happen the way you expect them to happen, and you 9 really need to be able to observe there. The other 10 side, I'm not sure about because it isn't talked about 11 here.
12 At some point in degraded operations, at 13 least at other facilities, control can actually move 14 to the technical support center, where you would, 15 likewise, want instrumentation that's reliable and 16 informative. And you haven't talked about that at 17 all.
18 MR. MAXWELL: Let me elaborate.
19 MEMBER BLEY: Feel free to respond, yes.
20 MR. MAXWELL: The controls, the switches 21 in the control room that we expect the operators to 22 operate, those are safety-related switches with 23 separate divisions controls. The switches at the MPS, 24 that is the location remote from --
25 MEMBER BLEY: No, no.
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101 1 MR. MAXWELL: -- the control room, again, 2 safety-related switches operate to begin to trip the 3 reactor, isolate containment, initiate DHRS. So, 4 there's the redundancy outside the control room. The 5 indications still are provided at the remote shutdown 6 station and at the technical support center.
7 MEMBER BLEY: Yes, but it's the 8 indications at the remote shutdown station that you 9 don't want to have an ITAAC on. And I'm wondering why 10 you don't want an ITAAC on those instruments. They 11 seem essential if you get run out of the control room.
12 Even if it's hands-off, you still want to be able to 13 monitor and make sure everything is working as 14 expected.
15 MR. MAXWELL: I agree, as an operator, I 16 want to monitor, but it is not safety-significant.
17 It's not related to safety.
18 MEMBER SUNSERI: Well, let me ask you, 19 though, you said that you're fulfilling Reg Guide 20 1.68, Pre-operational Test Program. You're going to 21 test all these things then, aren't you?
22 MR. MAXWELL: Yes, the indications will 23 all be tested as part of the pre-operational --
24 MEMBER SUNSERI: And calibrated and 25 verified functional and accurate, and all that stuff?
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102 1 MR. MAXWELL: Yes, all the indications at 2 the remote shutdown station are a subset of the 3 indications provided in the plant control system and 4 the module control system, all verified through pre-5 operational testing. It just doesn't rise to the 6 level of the ITAAC, that significance to safety.
7 MEMBER DIMITRIJEVIC: Well, there is a 8 couple of human actions which are significant for 9 safety not from the internal events, but from shutdown 10 in Level 2, as we learned a couple of days ago. So, 11 there is a couple, like starting the charging system 12 and --
13 MEMBER SUNSERI: They're not safety-14 related.
15 MR. MAXWELL: The important human 16 actions --
17 MEMBER DIMITRIJEVIC: Yes.
18 MR. MAXWELL: -- we don't assume a control 19 room evacuation coincident with another accident.
20 MEMBER DIMITRIJEVIC: No, no, it's not 21 -- I see what you're saying. But, I mean, you know 22 how they defined this, the significance of that is the 23 modeling accidents in many --
24 MR. MAXWELL: And we have ITAAC for those 25 important human actions to verify that the back NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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103 1 jumpers can perform them from the control room. All 2 the indications controls required to inform those 3 actions are available. And actually, again, in pre-4 operational testing, we demonstrate capability to do 5 that. That is a case where the ITAAC and the pre-6 operational testing overlap.
7 MEMBER BLEY: I'm kind of arguing against 8 myself. As I said earlier, there are areas where the 9 pre-op testing and ITAAC overlap in ways that seem 10 inefficient. So, I ought to be happy with this, but 11 the reasoning that gets us there leaves me a little 12 uncomfortable.
13 Thank you.
14 CO-CHAIR SKILLMAN: Let me just close it 15 in my own mind. It sounds like there will be a 16 Revision 3 of Chapter 7 that gives new information on 17 the RSS?
18 MR. MAXWELL: That's correct.
19 CO-CHAIR SKILLMAN: Understand. Thank 20 you.
21 Let's march. Keep on going.
22 MR. SANTOS: Okay. So, the last section 23 we would like to discuss is 14.3.11 on "Containment 24 Systems". There is one open item here regarding 25 integrated leak rate testing. NuScale has requested NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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104 1 exemption from the integrated leak rate test 2 requirement in 10 CFR 50, Appendix J, for the Type A 3 test. So, no ITAAC was provided for this testing.
4 MEMBER BLEY: Can you remind us what the 5 Type A is?
6 MR. SANTOS: Oh, I was afraid you would 7 ask that.
8 CO-CHAIR CORRADINI: That's when you blow 9 up the thing.
10 (Laughter.)
11 MR. SANTOS: "Measure the primary coolant 12 overall integrated leak rate after the containment has 13 been completed and is ready for operation and at 14 periodic intervals thereafter."
15 CO-CHAIR CORRADINI: It's the 100-and-16 something percent of --
17 MR. SANTOS: Overall integrated leak rate 18 as opposed to local leak rate testing or containment 19 isolation valve leakage rates.
20 MEMBER BLEY: I'm still not sure I 21 understand. You have 12 containment vessels --
22 MR. SANTOS: Anne-Marie?
23 MEMBER BLEY: -- and you've got to do the 24 testing on each of those, I assume. And are they 25 interpreting the overall is somehow going beyond the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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105 1 12 individual containments?
2 MS. GRADY: This is Anne-Marie Grady with 3 the NRC.
4 The integrated leak rate test is --
5 CO-CHAIR SKILLMAN: You've got to talk 6 into the microphone.
7 MEMBER BLEY: It's got to be on the 8 record, Anne-Marie. Sorry.
9 MS. GRADY: This is Anne-Marie Grady with 10 the NRC.
11 The integrated leak rate test, the Type A 12 test is to pressurize the containment vessel and show 13 that it doesn't leak beyond its allowable leakage, and 14 that's the exemption request, on that test only. Type 15 B, which are the mechanical penetrations, and Type C, 16 which are the containment isolation valves, still will 17 be tested, and they are not part of the exemption 18 request.
19 MEMBER BLEY: I kind of get it.
20 CO-CHAIR CORRADINI: Well, normally, when 21 you do the containment leak rate test, you test the 22 electrical penetrations, the mechanical penetrations, 23 the isolation valves. Then, you close it all up, 24 pressure --
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106 1 somewhere.
2 CO-CHAIR CORRADINI: -- it at low 3 temperature, at a given pressure --
4 MEMBER BLEY: I know how you do it.
5 CO-CHAIR CORRADINI: Okay. And that's the 6 one they're stopping.
7 MEMBER SUNSERI: For this plant, they're 8 going to be maintaining it under a vacuum all the 9 time.
10 CO-CHAIR CORRADINI: Thank you.
11 MEMBER SUNSERI: So, they'll know if it 12 will hold the vacuum or not, right?
13 CO-CHAIR CORRADINI: Right.
14 MEMBER BLEY: That's the argument.
15 CO-CHAIR CORRADINI: That would be my 16 argument.
17 MEMBER BLEY: Yes.
18 MS. GRADY: We're going to discuss this in 19 Chapter 6 on June 18th --
20 MEMBER BLEY: Oh, we'll look forward to 21 that.
22 MS. GRADY: -- in great detail.
23 (Laughter.)
24 CO-CHAIR SKILLMAN: Can you give us a 25 preview?
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107 1 (Laughter.)
2 MEMBER BLEY: Tom now will want to keep us 3 in suspense, right?
4 (Laughter.)
5 CO-CHAIR SKILLMAN: It works for me.
6 All right. Thank you. Anne-Marie, thank 7 you.
8 MR. SANTOS: So, basically, the open item 9 in 14 was just -- since Chapter 14 was preceding the 10 Chapter 8, Chapter 6, we had an open item in 14 to 11 account for this acceptability of the no ITAAC for 12 this while that review is ongoing. But, like Anne-13 Marie said, we'll discuss in June the acceptability of 14 granting that exemption request. And so, if that 15 exemption request is granted, then this would address 16 this open item and close it for 14.
17 CO-CHAIR SKILLMAN: Okay. Thank you.
18 MR. SANTOS: And so, the last slide is 19 just the conclusion slide, basically. For those 20 sections that have an open item, staff is not able to 21 finalize any conclusions at this point. But, for 22 those six sections that have open items, the staff 23 would conclude that, pending the resolution of any 24 confirmatory items in there, that the 25 10 CFR 52.47(b)(1) requirement has been met.
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108 1 And that concludes the staff's 2 presentation.
3 MEMBER BROWN: Okay. I have a comment, a 4 question.
5 MR. SANTOS: Yes?
6 MEMBER BROWN: You had some backup slides 7 which I finally looked at, since I just got them 8 today. And I noticed that you identify the test 9 abstracts reviewed and it included the Module 10 Protection System Test Abstract, 14.2-63. However, 11 you did not review Test Abstracts 61 and 62, which 12 cover the module control system and the plant control 13 system operations and controls.
14 So, I went off and looked at those two, 15 since I just got it today and saw you didn't see them, 16 and found that -- I've got to get to the right thing 17 here. If I go back to Chapter 14, the two abstracts 18 satisfactorily identify that they will verify 19 communications to the components that they're supposed 20 to control, both the plant control system and module 21 control system. And they also identify, both 61 and 22 62 identify that they will verify their bidirectional 23 interface between the PCS and the MCS, which is, 24 according to the drawing, satisfactory.
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109 1 communication verification from the MCS and PCS to the 2 planet network, which is a deterministic one-way 3 communication device. There's no mention of that at 4 all, which is a critical communication device for 5 verification, which we just went through a final 6 resolution where that would be specified as not just 7 deterministic, but a hardware-based device, not 8 software-configured.
9 So, I guess my question is, they look like 10 they are incomplete relative to the -- and no answer 11 you can give me is going to satisfy me.
12 MR. SANTOS: Well, I'll let Kerri try.
13 MEMBER BROWN: Well, I had to throw that 14 in just to make sure you knew I was serious; that's 15 all.
16 (Laughter.)
17 MS. KAVANAGH: Oh, goodness. This is 18 Kerri Kavanagh again from the Quality Assurance Vendor 19 Inspection Branch.
20 For those test abstracts that we did not 21 review, no finality was provided.
22 MEMBER BROWN: What do you mean by 23 "finality"?
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110 1 for the staff review to have a complete review when 2 they come in under the COL. So, the staff, because it 3 did not meet the criteria for review, for the risk-4 informed review, for this particular application, the 5 staff will review those that did not provide finality, 6 that we did not provide finality on during the COL 7 application.
8 MEMBER BROWN: Why does the risk-informed 9 criteria not include control of every component in the 10 plan?
11 MS. KAVANAGH: I cannot answer that for 12 D-RAP. You will have to ask NuScale as to how they 13 did their D-RAP. And we provided that. The staff did 14 that presentation in 17.4 back in March, I believe we 15 were here. But that's not my group's review.
16 What I'm trying to say is that my group 17 took the results of 17.4, we looked at the safety-18 related, risk-informed components that came out of 19 that analysis, and we did the review of those test 20 abstracts based on that input.
21 MEMBER BROWN: Okay. I thank you for your 22 answer.
23 MS. KAVANAGH: You're welcome.
24 MEMBER BROWN: My conclusion doesn't 25 change though.
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111 1 (Laughter.)
2 CO-CHAIR SKILLMAN: Okay. Understand 3 that. Okay.
4 MEMBER BROWN: I just thought I'd pass 5 that on.
6 CO-CHAIR SKILLMAN: Colleagues, any 7 further questions for the staff? We've got the 8 gentlemen and lady in front of us. Any other 9 questions?
10 (No audible response.)
11 Okay. Before we go to public, Colleagues, 12 any comments, any questions?
13 Yes?
14 CO-CHAIR CORRADINI: Do we need to go to 15 the public comments?
16 CO-CHAIR SKILLMAN: Well, we are at a 17 point where --
18 CO-CHAIR CORRADINI: If we're not going to 19 go to closed session, we can do public comments at the 20 end of the day.
21 CO-CHAIR SKILLMAN: Well, we're going to 22 break into a completely different --
23 CO-CHAIR CORRADINI: Oh.
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112 1 do is to clear public comments in 14. If there are 2 none, then we're a clean shot into 3.9. I do not 3 believe we need a closed session.
4 Colleagues, closed session? I'd say no.
5 Before we go to the phone lines, are there 6 any members of the public in the audience that would 7 like to make a comment? If so, please come to the 8 microphone and make your comment.
9 (No audible response.)
10 Seeing none and hearing none, on the phone 11 line, if there is anyone on the phone line, would you 12 just simply say "hello"?
13 (No audible response.)
14 Hearing none, let's close the phone line.
15 Tanny and staff, thank you. I want to 16 thank the NuScale staff for the Chapter 14.
17 I want to change out and go into NuScale 18 3.9.2. I want to get as much done as we can before 19 1200.
20 (Pause.)
21 Ladies and gentlemen, we will continue 22 this meeting, and this meeting now is focused on 23 NuScale's Chapter 3.9.2, "Dynamic Testing and Analysis 24 of Systems, Components, and Equipment".
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113 1 lead from NuScale.
2 Marty?
3 MR. BRYAN: Thank you.
4 CO-CHAIR SKILLMAN: Yes, sir.
5 MR. BRYAN: Good morning.
6 Yes, I'm Marty Brown. I'm the Licensing 7 Project Manager for NuScale for 3.9.2. And with me I 8 have Dylan Addison, Olivia Hand, and J.J. Arthur. And 9 J.J. is going to take us through the areas we're going 10 to cover today.
11 MR. ARTHUR: Good morning.
12 This morning we will be discussing Section 13 3.9.2, "Dynamic Testing and Analysis of Systems, 14 Components, and Equipment" with a focus on four 15 Technical Reports that are incorporated by reference 16 in this section. These include the NuScale Power 17 Module Seismic Analysis Technical report, two 18 Technical Reports for the Comprehensive Vibration 19 Assessment Program. The first is our CVAP Analysis 20 Technical Report; the second, the CVAP Measurement and 21 Inspection Program Technical Report. And then, 22 finally, the NuScale Power Module Short-Term Transient 23 Analysis Technical Report.
24 So, my colleague Dylan Addison will start 25 with the seismic analysis.
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114 1 MR. ADDISON: All right. Good morning.
2 My name is Dylan Addison. I've been with 3 NuScale for about two years, and most of my work is 4 focused on the seismic methodology and on answering 5 the staff's questions about the seismic methodology.
6 And let's walk right through the way that 7 we qualify the NPM components. This graphic depicts 8 a high-level overview of the seismic methodology. And 9 the purpose of this portion of the presentation is to 10 reacquaint the Committee members with how NuScale gets 11 from a three-field seismic input acceleration. It 12 goes through the soil, through the building, through 13 this very unique feature of the approximately 8-14 million-gallon reactor pool, and then, finally gets to 15 the loads that are applied to the NPM components for 16 ASME stress analysis, which our ITAAC design 17 commitments ensure that we'll complete by the time we 18 put modules into service.
19 So, on the far left of the graphic, the 20 analysis begins with a detailed 3D model of the 21 NuScale power module in a single operating bay. And 22 that ANSYS Model is used to tune the response of an 23 NPM Beam Model, so that the two are dynamically 24 equivalent. And that's performed using a modal 25 harmonic and transient analyses. And why do we need NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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115 1 a 3D model that's dynamically equivalent to a 2D Beam 2 Model? Because we use SASSI for our soil structure 3 interaction analysis, and SASSI requires a simple 5 4 Beam Model representation in order to run in a 5 reasonable amount of time; and also, because SASSI is 6 not capable of explicitly modeling the fluid in the 7 pool.
8 So, what do we do? We take the NPM Beam 9 Model representation, and in this second image, we're 10 showing the SASSI Model, the reactor building with the 11 light blue soil elements on the outside, the dark blue 12 reactor building, and the red Beam Model 13 representations of the NPMs. Twelve copies are 14 inserted into the model, and a soil structure 15 interaction analysis is performed in the frequency 16 domain. And the results are, then, transformed back 17 into the time domain and used as inputs in the next 18 analysis.
19 And what are those results? They are time 20 history accelerations at the NPM supports, which are 21 the containment vessel seismic lugs, the three lugs 22 about halfway up the module and at the containment 23 vessel skirt. And there are inputs to the entire 24 reactor pool -- that is the pool walls and the pool 25 floor -- that are mapped onto to this third model, NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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116 1 this yellow model, which has created in ANSYS of the 2 entire pool. And we do it this way because you have 3 to work from the outside in. You have to perform the 4 SSI analysis first, and we also need to account for 5 how the pool reacts to seismic excitation.
6 CO-CHAIR CORRADINI: So, does ANSYS model 7 the water?
8 MR. ADDISON: That's right. These yellow 9 elements are fluid 30 elements in ANSYS.
10 CO-CHAIR CORRADINI: So, it will try to 11 describe what's happening to the pool as you shake it?
12 MR. ADDISON: That's right.
13 CO-CHAIR CORRADINI: Okay.
14 MR. ADDISON: And the input accelerations 15 from the SSI analysis are mapped onto the whole 16 surface of the pool. And in the corner there, you see 17 in position 6 of 12 is the detailed 3D model of the 18 reactor. And that's the same 3D model that's used 19 initially to tune the Beam Model.
20 MEMBER BLEY: Can you -- well, you'll have 21 to tell us something about the range of earthquakes 22 you'll consider. And when there is a COL, you'll have 23 to redo, I guess, for the specific seismicity at the 24 site. But can any of your calculations show water 25 sloshing out of the pool? And if it does slosh out, NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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117 1 is there an easy path for it to get back or can we 2 lose water?
3 MR. ADDISON: We have analyzed for 4 sloshing, and it's, I think, on the order of about 2.5 5 feet to 3 feet, and it's not, past that analysis, it's 6 not necessary to look at.
7 MEMBER BLEY: Okay.
8 CO-CHAIR CORRADINI: So, since we're onto 9 sloshing, it, then, transmits a load to the vessel, or 10 the containment -- excuse me -- and that's accounted 11 for in terms of it pushing on the vessel as I have a 12 seismic event?
13 MR. ADDISON: So, sloshing is analyzed 14 separately.
15 CO-CHAIR CORRADINI: But it creates a flow 16 past the vessel, the containment vessel, which, then, 17 creates an asymmetric load, yes?
18 MR. ADDISON: It would and --
19 CO-CHAIR CORRADINI: And that analyzes 20 part of the seismic event?
21 MR. ADDISON: And it's analyzed 22 separately. In this model, in this 3D ANSYS Model, 23 we're not looking at sloshing because a separate 24 analysis shows that it's not necessary to look at.
25 MEMBER SUNSERI: Let me --
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118 1 MEMBER BLEY: That's interesting, and we 2 haven't talked about that. But I assume the 3 excitation to the model is much stronger through the 4 mechanical connections?
5 MR. ADDISON: That's right.
6 MEMBER BLEY: I'm sorry, I cut you off.
7 MEMBER SUNSERI: No, I think that was the 8 same question I had. Normally, I mean, the module is 9 still supported to err through the structure, right?
10 But the difference is, instead of being surrounded by 11 air, it's surrounded by water in this case. So, how 12 does that affect the stresses on the support? That's 13 what Dennis just asked.
14 MEMBER BLEY: Right.
15 MR. ADDISON: How does the fact that it's 16 surrounded by water affect it? Well, by virtue of the 17 fact that we model it, we know what the loads end up 18 being. And the acoustic resonances in the pool are 19 accounted for in this analysis.
20 CO-CHAIR CORRADINI: I guess my way of 21 asking my question is, if the water weren't there and 22 it was air, would I see a significant difference in 23 how it shakes?
24 MR. ADDISON: Yes.
25 CO-CHAIR CORRADINI: Okay.
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119 1 MR. BRYAN: So, I think he's just wanting 2 to confirm that in a seismic event the effect of the 3 water is considered.
4 MR. ADDISON: Absolutely.
5 CO-CHAIR CORRADINI: Okay. Fine.
6 CO-CHAIR SKILLMAN: Let me ask this, 7 Dylan: that pool is a fairly long pool. The good 8 news is that each reactor is in its own bay. So, it's 9 in a cell. So, whatever the water conditions might 10 be, it's relatively isolated, each module from the 11 other module.
12 Is the compressibility of the water a 13 factor in this analysis? Does ANSYS assign some, if 14 you will, some compressive characteristic to the fluid 15 as a mechanical transition, a --
16 MR. ADDISON: I believe the fluid is 17 assumed incompressible.
18 CO-CHAIR SKILLMAN: Thank you. All right.
19 MR. ADDISON: Yes.
20 CO-CHAIR SKILLMAN: Thanks.
21 MR. ADDISON: So, the outputs of this 22 entire pool analysis in ANSYS are enveloped and 23 broadened in structure response spectra throughout the 24 module, bounding forces and moments, bounding relative 25 displacements at different locations through use as NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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120 1 seismic anchor motions in piping analysis, for 2 instance, and also, time histories throughout the 3 module. And all those results are used there again as 4 inputs to downstream stress analysis, which is what 5 actually qualifies the components.
6 So, this rather light graphic we included 7 to make clear another unique aspect of the design, 8 which is the refueling area. And because we move the 9 whole module in order to refuel it, an analysis is 10 performed for the scenario in which the lower reactor 11 pressure vessel and the lower reactor pressure vessel 12 internals and the fuel are situated inside the reactor 13 flange tool, the RFT. And that time history analysis 14 ensures that the whole assembly remains upright and 15 the integrity of the fuel is maintained during a 16 seismic event.
17 CO-CHAIR CORRADINI: What is the clearance 18 between the containment and the wall? One individual 19 NPM has got a concrete wall on either side of it.
20 What's the clearance?
21 MR. ADDISON: I don't have that number in 22 front of me. But, just from the scale, on the order 23 of 10 feet or --
24 CO-CHAIR CORRADINI: Oh, 10 feet?
25 MR. ADDISON: -- 8 feet maybe, yes.
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121 1 CO-CHAIR CORRADINI: Oh, I just was 2 looking at it. It looked awful thinner than that.
3 So, that's why I --
4 CO-CHAIR SKILLMAN: Oh, no, they're 5 actually trunnions.
6 MR. ADDISON: Oh, maybe I misunderstand 7 the question, yes.
8 CO-CHAIR SKILLMAN: And it appears as 9 though, based on the drawings that I saw yesterday, 10 that the insert of the module is actually into a slip 11 that ensures there is neither east-west nor north-12 south movement. So, it's actually locked in concrete 13 buttresses that are highly reinforced.
14 CO-CHAIR CORRADINI: That's what it looked 15 like.
16 MR. ADDISON: Yes, I think I misunderstood 17 the question.
18 CO-CHAIR SKILLMAN: And I would say maybe 19 it's pretty close. I mean, it's --
20 MR. ADDISON: The lugs interface directly 21 with corbels on the --
22 CO-CHAIR SKILLMAN: Bingo.
23 MR. ADDISON: -- reactor bay wall.
24 CO-CHAIR CORRADINI: So, there is a 25 structural support about midway up?
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122 1 MR. ADDISON: That's right.
2 CO-CHAIR CORRADINI: Is that what I'm 3 seeing?
4 MEMBER BLEY: That's that thing, yes.
5 CO-CHAIR CORRADINI: Okay. Thank you.
6 MR. ADDISON: Thank you.
7 MEMBER BLEY: Dylan, when you do the 8 analysis for the refueling area, did you look at cases 9 with everything intact or cases where some of the fuel 10 is actually in the process of being moved when the 11 earthquake hits?
12 MR. ADDISON: The only scenario analyzed 13 is where the lower reactor vessel internals are still 14 in place, still bolted on.
15 MEMBER BLEY: So, you would get something 16 different, no doubt, if some rods were moving?
17 MR. ADDISON: Yes, and that would be a 18 highly non-linear analysis that --
19 MEMBER BLEY: Not fair to you, yes.
20 MR. ADDISON: -- is not practical to 21 perform and doesn't make sense to perform in this --
22 MEMBER BLEY: So, when we look at the --
23 it would have been good if we had had this before we 24 had the PRA presentation. When we look at now the 25 seismic margins analysis and later the complete NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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123 1 seismic PRA, this issue of what happens to fuel that 2 might be in the process of being moved is one that has 3 not been addressed as yet, I think. We didn't ask --
4 CO-CHAIR CORRADINI: Can you have a 5 seismic event in transit, during transit?
6 MEMBER BLEY: You don't know when the 7 seismic event is going to hit.
8 CO-CHAIR CORRADINI: I know, but that's 9 what you're asking.
10 MEMBER BLEY: That's what I'm asking.
11 Well, yes, you have it in transit, but also after 12 you're in the refueling bay when you're halfway 13 through the refueling process. See, not everything is 14 where it is assumed to be here, which provides --
15 okay. We'll have to look at that later when we get 16 those people back again.
17 MEMBER REMPE: But now, when we know that, 18 I guess, each module is at some location, almost or in 19 contact with something from the bay for each module, 20 the distance does look -- the gap. Can you give us 21 some location? I mean, down low it looks like there's 22 quite a bit of distance, well, a bit more distance, 23 but other places it looks like, well, the cylindrical 24 part of the containment vessel looks fairly close to 25 the concrete wall. How big is that distance? Is it NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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124 1 like 10 inches or something less than a foot? Like 2 right where your hand is right there, how big is that 3 gap?
4 MR. ADDISON: Well, if the whole module is 5 70 feet high or so, then, yes, we are looking on the 6 order of a foot or two.
7 MEMBER REMPE: Okay.
8 MR. ADDISON: Yes.
9 MEMBER BLEY: Is the module anchored on 10 the bottom or just supported by those things that were 11 called trunnions before?
12 MR. ADDISON: It's held at the bottom by 13 a passive support. It's a big ring that the CNV 14 skirt, the containment vessel skirt, sits within.
15 MEMBER BLEY: Okay.
16 MR. ADDISON: All right.
17 MEMBER BLEY: That's part of the analysis, 18 the stresses down there?
19 MR. ADDISON: Right, the CNV skirt is 20 analyzed.
21 So, here we just have an overview of all 22 the Service Level D stress analyses that NuScale has 23 performed and which are under revision, which 24 demonstrate that the loads produced by this 25 methodology are acceptable. And the bottom line here NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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125 1 is that our ITAAC design commitments ensure that NPM 2 components conform to the rules of ASME Section 3.
3 And that brings us to your point from 4 earlier, which is the one COL item relevant to Section 5 3.9. It essentially states that site-specific seismic 6 analysis will be performed and the results will be 7 compared to the results generated for the design 8 certification, and where the results are not bounded, 9 action will be taken to demonstrate how to put margin 10 in or redesign the components.
11 With that, I will turn it over to Olivia 12 Hand.
13 DR. SCHULTZ: Just to follow up on your 14 comment, Dennis. And that is, in this configuration 15 with the 12 modules and refueling, and so forth, even 16 though it's a very difficult analysis, we ought to 17 have some consideration of what the impact would be, 18 given that for about 10 percent of the time during the 19 year you're going to be moving a module, refueling a 20 module. A lot of activity is associated with that, 21 with a module not in its bay.
22 MEMBER BLEY: Yes, it's not and it's a 23 substantial fraction of the time.
24 DR. SCHULTZ: That's right.
25 MEMBER BLEY: Yes.
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126 1 DR. SCHULTZ: It's different than what 2 we're used to thinking about.
3 MS. HAND: Okay?
4 CO-CHAIR SKILLMAN: Yes, please proceed, 5 Olivia.
6 MS. HAND: My name is Olivia Hand, and 7 today I'll be talking about the Comprehensive 8 Vibration Analysis Program and, also, the Short-Term 9 Analysis Methodology.
10 So, the Comprehensive Vibration Analysis 11 Program is designed to look for mechanisms of flow-12 induced vibration in the plant, and to either preclude 13 them by design for the strongly coupled mechanisms or 14 just show that over the design life it's not going to 15 provide any vibration energies that are detrimental to 16 the components.
17 And so, we look at both components in our 18 primary coolant flow path, which, of course, you guys 19 know is natural circulation, and we also look at the 20 secondary side. So, we're analyzing everything 21 inboard of the disconnect flanges, so all the 22 containment components, all of the reactor vessel 23 components.
24 And the analysis program consists of three 25 parts, in accordance with Reg Guide 120, which is to NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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127 1 perform analysis, then perform validation via 2 measurement, and also to inspect. So, the first step 3 of the analysis program, of course, is to screen all 4 of the components. So, we go through every component 5 in the module and we see if it meets a screening 6 criteria for one of the six FIV phenomena that we 7 consider, which are vortex shedding, fluid-elastic 8 instability, acoustic resonance, turbulence, flutter, 9 and gallop.
10 So, an example of this, for example, 11 vortex shedding, we're looking at a component that's 12 bluff body, exposed to crossflow. So, we could use 13 some operational experience to, say, screen out things 14 that we know have been operating in PWRs for many 15 years without issues; for example, maybe thermowells 16 or steam generator tubes.
17 But we take a conservative approach and we 18 just look at straight screening criteria. And if the 19 component meets the screening criteria, we include it 20 in the analysis program.
21 CO-CHAIR SKILLMAN: Does that mean you 22 basically excluded OE as a basis to not consider a 23 component?
24 MS. HAND: We excluded OE, yes, in the 25 case that it would not allow us to analyze it.
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128 1 CO-CHAIR SKILLMAN: Yes. Okay. Thank 2 you.
3 MS. HAND: Because we wanted to be 4 conservative and analyze everything, you know, to come 5 up with a safety margin and prove to ourselves whether 6 or not it is something that needs to be considered in 7 the measurement program for validation. And then, 8 ultimately, everything that gets screened into our 9 analysis program is inspected following initial 10 startup tests. So, we want that level of assurance as 11 well.
12 CO-CHAIR SKILLMAN: I think you're to be 13 commended for that because this unique design would 14 simply invite, "Why didn't you look at that when you 15 had the chance?", if there were to be an incident many 16 years down the road. By taking the high ground and 17 analyzing everything, you've pretty much provided a 18 basis to respond to that challenge.
19 MS. HAND: Yes. Being a first-of-a-kind 20 design, you know, it's not just a design that we're 21 scaling up where we said, okay, well, this is what we 22 did last time, so we'll do the same this time.
23 CO-CHAIR SKILLMAN: It's different.
24 MS. HAND: We needed to start from 25 scratch.
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129 1 CO-CHAIR SKILLMAN: Thank you.
2 MS. HAND: So, that's the approach that 3 was taken.
4 So, as mentioned, we move into the 5 analysis program where we use industry standard 6 methods for coming up with a safety margin, which is 7 defined as either the margin that you have to the 8 onset of a phenomena that's strongly coupled, which is 9 those are the phenomena that we need to preclude by 10 design because, if we're having strongly coupled 11 vibrations, we can't show that we would have 12 acceptable performance over the 60-year design life.
13 Or for turbulence, it's with respect to the fatigue 14 usage factor for the component, based on the 15 alternating stresses.
16 So, we perform the analysis program, and 17 then, any components with a safety margin less than 18 100 percent, we commit to validation via the 19 measurement program. And then, as I mentioned before, 20 all components that are a part of the analysis program 21 will be inspected at the completion of initial startup 22 testing.
23 And then, the figure on the right is just 24 a view of our natural circulation primary flow path 25 for the reactor module. I believe you probably saw NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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130 1 this in Chapter 5. And one thing to point out, this 2 image does not show the primary and secondary coolant 3 piping that's part of the RPV and CNV connection and 4 up to the disconnect flange. So, that's included in 5 our program, but not shown in this figure.
6 We do have some differences compared to 7 recent applicants. So, we're analyzing a lot of 8 components that have not been traditionally the focus 9 of past programs; for example, the steam generator 10 tubes. We also are considering mechanisms that apply 11 to these components like vortex shedding and fluid 12 loss instability; whereas, in the past, applicants 13 have mostly focused on turbulence and associated 14 degradation mechanisms.
15 We have very much lower primary coolant 16 flow rates. The table on this slide provides a 17 comparison of some of the average velocities that we 18 see throughout the module compared to past designs.
19 And if you think about this more in terms of flow 20 rate, that's also provided, and primary coolant loop 21 transit time, which is just the amount of time it 22 would take for a control volume to move from the core 23 all the way through and back. It takes about a minute 24 for us. So, that kind of gives you a feel for the 25 velocities that we're seeing inside of the module.
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131 1 CO-CHAIR CORRADINI: But don't you have 2 higher steam flow rates inside the tubes? Steam mass 3 flux in inside the tubes because you've got this kind 4 of reversed situation?
5 MS. HAND: Yes. So, our secondary coolant 6 is inside of the tubes. I'm not actually sure whether 7 our velocities are higher than primary coolant flow 8 inside of a PWR tube. I've never actually done that 9 comparison.
10 CO-CHAIR CORRADINI: Okay. Well, I'm 11 trying to decide where to worry about things. I'm not 12 worried about the outside of the tube because your 13 Reynolds number has to got to be super-small, but I'm 14 thinking about inside the tubes. So, you're also 15 doing flow-induced vibrations because of inside flow?
16 MS. HAND: We are. We account for that in 17 our turbulent analysis. And we'll have a slide coming 18 up where we show some of our margins where we actually 19 do have the need to validate some of our analysis for 20 flow outside the tubes.
21 CO-CHAIR CORRADINI: Okay.
22 MEMBER BALLINGER: What does "no 23 proprietary scale testing" mean?
24 MS. HAND: It just means that, since this 25 is a first-of-a-kind design, we don't have previous NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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132 1 testing of other reactor designs that we're using to 2 inform our analysis approach. We do have some limited 3 benchmark testing that has been used to help inform 4 our analysis approach, but --
5 MEMBER BALLINGER: So, there would be no 6 proprietary scale testing available? I'm just trying 7 to --
8 MS. HAND: Yes.
9 CO-CHAIR CORRADINI: They don't have 10 anything available.
11 (Laughter.)
12 MEMBER BALLINGER: Yes.
13 MS. HAND: Not available.
14 CO-CHAIR CORRADINI: Lt me ask about those 15 tests because we were told about -- and again, if 16 we're going into something that's got to go to closed 17 session, you stop us. But my understanding is you did 18 -- I can't remember exactly -- but you did what I'll 19 call a single row of tubes for testing in a test 20 facility outside of NuScale or done for NuScale, is 21 that correct?
22 MS. HAND: It's actually two separate test 23 facilities.
24 CO-CHAIR CORRADINI: Right.
25 MS. HAND: So, tubes, yes.
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133 1 CO-CHAIR CORRADINI: But the helical 2 geometry of the testing was done in that test at full 3 flow for the steam, steam production?
4 MS. HAND: Yes.
5 CO-CHAIR CORRADINI: Okay. And it wasn't 6 a complete generator, but it was one column of tubes?
7 Am I remembering correctly?
8 MS. HAND: So, TF-1 test was three single 9 tubes.
10 CO-CHAIR CORRADINI: Right.
11 MS. HAND: Yes. We have some pictures 12 coming up.
13 CO-CHAIR CORRADINI: Okay.
14 MS. HAND: And then, TF-2 is a five-column 15 assembly.
16 CO-CHAIR CORRADINI: Okay. You have 17 pictures?
18 MS. HAND: I do, yes.
19 CO-CHAIR CORRADINI: Okay. Fine. We'll 20 wait then.
21 MS. HAND: Okay. So, just to close out 22 this slide, we're going to be performing the majority 23 of our validation testing prior to startup testing.
24 This is unique and it's something that we're choosing 25 to do just to make sure that we get high-quality, NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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134 1 high-quantity data to close out any of our validation 2 concerns prior to actually building the first module 3 and getting it in place, which would be a more 4 precarious time to find an issue.
5 And we have a larger inspection scope.
6 So, we're inspecting everything that's screened into 7 our analysis program. We're going to be looking at 8 over 50 locations in the module after startup testing.
9 CO-CHAIR SKILLMAN: Before you change, 10 what are you communicating on steam generator gap?
11 MS. HAND: So, the gap velocity is defined 12 as the velocity as it moves through the steam 13 generator tube bundle. So, it's the velocity through 14 the tubes.
15 CO-CHAIR CORRADINI: It's the flow 16 velocity when it's between the two tubes?
17 MS. HAND: In the gap of the tubes.
18 CO-CHAIR CORRADINI: In the gap?
19 MS. HAND: Uh-hum.
20 CO-CHAIR CORRADINI: Think of it as ratio.
21 It's the flow inside the narrow portion, right?
22 MS. HAND: Correct.
23 MEMBER SUNSERI: So, that kind of ratio, 24 it's a ratio that, then, I would think the answer to 25 your question earlier, what's the flow rate inside the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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135 1 tube, it's going to be, you know, a factor higher 2 than --
3 CO-CHAIR CORRADINI: Well, but it's steam.
4 So, the mass flux is going to be much --
5 MEMBER SUNSERI: I mean, it's similar, 6 though, on the -- I mean, it's boiling on the SONGS 7 plant, right? And it's not boiling on the NuScale.
8 CO-CHAIR CORRADINI: Oh, I see what you're 9 saying.
10 MS. HAND: Yes, so this is a comparison 11 for outside the tubes. I don't have a comparison for 12 inside the tubes.
13 CO-CHAIR CORRADINI: But I know what he's 14 asking.
15 MS. HAND: Okay.
16 CO-CHAIR CORRADINI: I know what he's 17 pointing out. I'm with you.
18 CO-CHAIR SKILLMAN: What triggered my 19 question is, I'm pretty familiar with steam 20 generators. That appears to me to be gap tube center 21 line to tube center line minus the halves of the 22 tubes. So, it's the gap between the OD of one tube to 23 the adjacent OD of the next tube. I think that that's 24 what that is. But the 18 on SONGS is the difference 25 between a flat plane of tubes, I think.
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136 1 MS. HAND: So, this is a velocity 2 reported. So, it's in feet per second.
3 CO-CHAIR SKILLMAN: Uh-hum.
4 MS. HAND: So, it's not referring to 5 the --
6 CO-CHAIR SKILLMAN: Geometry?
7 MS. HAND: -- pitch or the diameter, 8 although those feed into this, how it's calculated.
9 CO-CHAIR SKILLMAN: It is the mass flow 10 rate through that gap, the velocity of the steam going 11 through that gap?
12 MS. HAND: And also, the density.
13 CO-CHAIR SKILLMAN: Yes.
14 MS. HAND: And then, the pitch diameter.
15 CO-CHAIR SKILLMAN: Thank you. All right.
16 MS. HAND: Okay. So, this slide has a 17 summary of some of our analysis results. First, just 18 high-level, you know, how we perform our design 19 analysis. Most of these require modal response 20 inputs. So, we determine our frequencies and mode 21 shape. We determine our flow velocities past and 22 through the components of interest. And then, we 23 generally use Appendix N guidelines to help inform our 24 analysis methodologies.
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137 1 positive, which means that FIV is not predicted to 2 occur for the strongly coupled mechanisms or for the 3 case of turbulence. You know, we're not running up 4 against a fatigue factor limit.
5 And our limiting regions, reported in this 6 table, are the helical coil steam generator, in-core 7 instrument guide tubes, the control rod drive shaft, 8 and the decay heat removal system steam piping.
9 CO-CHAIR CORRADINI: Wait. So, the 10 analysis category, what is "TB"?
11 MS. HAND: Turbulent buffeting.
12 CO-CHAIR CORRADINI: Ah, okay. So, vortex 13 shedding behind the tube?
14 MS. HAND: Vortex shedding at the very 15 bottom row of the steam generator tubes.
16 CO-CHAIR CORRADINI: At the very bottom?
17 MS. HAND: Yes. So, vortex shedding won't 18 occur if you have a downstream flow obstruction. So, 19 it's only the very bottom of the tubes that are 20 susceptible.
21 CO-CHAIR CORRADINI: This is the primary 22 flow?
23 MS. HAND: Primary coolant flow, correct.
24 CO-CHAIR CORRADINI: Okay. Thank you.
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138 1 instability. And then, down for the DHRS steam 2 piping, AH is acoustic resonance. So, that's 3 happening in --
4 CO-CHAIR CORRADINI: The what? I'm sorry.
5 MS. HAND: Acoustic resonance which occurs 6 in the flow-occluded cavity. So, when you have high-7 velocity flow, it generates a vortex and it could lock 8 in with an acoustic frequency in the cavity.
9 DR. SCHULTZ: The "most limiting results" 10 refers to what? Is that location? Or can you help 11 describe what that means?
12 MS. HAND: Yes. So, we think about our 13 limiting results in terms of the safety margin, which 14 is the combination of velocities and frequencies and 15 how much margin we have to the onset of the phenomena 16 occurring. So, this table shows that our most 17 limiting location is the helical coil tubes for fluid-18 elastic instability.
19 DR. SCHULTZ: Okay. Thank you. So, 20 location by location.
21 MEMBER BALLINGER: So, is 10 percent 22 considered okay?
23 MS. HAND: We believe so, because we 24 believe we have aspects of our design analysis that 25 are potentially overly conservative.
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139 1 MEMBER BALLINGER: Because Section 3, 2 there's a piece of Section C that says, if you think 3 you're designing within a certain window, you're okay.
4 But if you have reason to believe that you could be 5 outside of the normal sort of database that exists, 6 that you need to do some additional testing, which is 7 one of the things that got SONGS. So, is 10 percent 8 okay?
9 MS. HAND: Well, so we're doing additional 10 testing to demonstrate that 10 percent is okay --
11 MEMBER BALLINGER: Okay.
12 MS. HAND: -- and to validate that safety 13 margin.
14 MEMBER BALLINGER: And that includes all 15 wear issues, and stuff like that, that could exist?
16 MS. HAND: So, when I think of wear at 17 least, I think of that as more of a turbulence 18 lifecycle issue, which is something that we track over 19 the 60-year life of the component through inspections.
20 If fluid-elastic instability occurs, that is 21 degradation that will cause tube damage and leaking.
22 MEMBER BALLINGER: So, is there any 23 likelihood of threshold behavior? Meaning that you've 24 got this 10 percent margin, the fluid-elastic 25 instability, is there anything that's non-linear in NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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140 1 the analysis where, if you get a certain amount of 2 wear, where you increase a gap here and there, you go 3 from a good hair day to a bad hair day?
4 MS. HAND: The analysis is highly non-5 linear, yes.
6 MEMBER BALLINGER: That's what I 7 suspected. So, that's what I keep wondering about 8 this 10 percent business. My wife wouldn't like that.
9 MEMBER SUNSERI: So, let me ask you this, 10 though --
11 MEMBER BLEY: You're worried that it might 12 be kind of cliff edgy?
13 MEMBER BALLINGER: Yes. Well, she said 14 it's cliff edgy.
15 (Laughter.)
16 MS. HAND: But what I will say is 17 NuScale's position is that we've actually biased --
18 MEMBER BALLINGER: Okay.
19 MS. HAND: -- the majority of our inputs 20 to get us to that cliff edge.
21 MEMBER BALLINGER: So, if you do what 22 would amount to --
23 MS. HAND: So, a less conservative 24 analysis would show that we have --
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141 1 to a best estimate analysis, as opposed to all these 2 conservatisms, what do you get? In other words, how 3 big a number does it -- how does it change?
4 MS. HAND: So, we have not provided that 5 yet to the NRC. That's actually part of our pretest 6 prediction work that we do for these two mechanisms 7 for our upcoming TF-3 test. Preliminary results are 8 showing approximately about 80 percent.
9 MEMBER BALLINGER: Eighty percent?
10 MS. HAND: Yes. Those will be 11 submitted --
12 MEMBER BALLINGER: That makes me feel 13 better?
14 (Laughter.)
15 MEMBER SUNSERI: So, the application of 16 the helical coil steam generator to NuScale is unique, 17 but they're not unique in the industry, right?
18 CO-CHAIR CORRADINI: No.
19 MEMBER SUNSERI: So, how does this data 20 compare to industry-available data on the ones that 21 are in service someplace?
22 MS. HAND: We have not actually been able 23 to find much data that would give a parameter like a 24 safety margin. We've used industry data related to 25 helical coil, steam generator Connors' constant NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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142 1 coefficients, which are our design analysis input for 2 fluid-elastic instability. And those compare very 3 favorably with straight tube.
4 CO-CHAIR CORRADINI: What are you 5 comparing again? Could you repeat that, please?
6 MS. HAND: The Connors' constants which 7 are used in the fluid-elastic instability analysis.
8 CO-CHAIR CORRADINI: Oh, okay.
9 MS. HAND: So, they're like an empirical-10 fed coefficient and exponent that you use to come up 11 with the safety margin calculated value. And the 12 helical coil ones provide a much higher safety margin 13 than the straight tube ones, but we have 14 conservatively used the straight tube ones in our --
15 CO-CHAIR CORRADINI: Straight tube meaning 16 this or straight tube meaning crossflow? When you say 17 "straight tube," I'm trying to understand. Is it flow 18 this way over the tubes or is it flow straight in 19 terms of perpendicular crossflow?
20 CO-CHAIR SKILLMAN: Transverse.
21 CO-CHAIR CORRADINI: This way?
22 CO-CHAIR SKILLMAN: Oh, it's linear or 23 transverse? That's the question he's asking.
24 MS. HAND: I think that's correct.
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143 1 a tube that goes like this versus one that goes back.
2 CO-CHAIR CORRADINI: Right, but it's still 3 external to the tube? Am I understanding correctly?
4 MS. HAND: Yes, fluid-elastic instability 5 is only applicable when the flow is on the outside of 6 the tube bundle.
7 CO-CHAIR CORRADINI: Yes. But I'm with 8 you. It's this versus that.
9 MEMBER REMPE: Just to make sure I 10 understand, on the separate effects tests for the 11 steam generator tubes, are you going to be considering 12 all of the different, like different mode shapes, 13 different frequencies, even though it's a little bit 14 of integral test that considers all of the inputs that 15 you want to verify, right?
16 MS. HAND: Yes.
17 MEMBER REMPE: Or are you doing separate 18 effects for each of these things?
19 MS. HAND: No, separate effects in that 20 it's just looking at the steam generator. And then, 21 in that testing, we're doing modal testing and flow 22 testing. So, as a part of the modal testing, we'll be 23 doing both hammer and shaker testing to determine mode 24 shapes, frequencies, and damping. And we'll be 25 performing that both in air and in water to determine NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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144 1 the effect of hydrodynamic.
2 MEMBER REMPE: Okay. Thank you.
3 MS. HAND: If there is nothing else on 4 this slide, I'll move on to the next.
5 CO-CHAIR SKILLMAN: Yes, please do, yes.
6 MS. HAND: So, this actually shows 7 pictures of the test facilities that we've mentioned 8 a bit.
9 So, we have as NuScale these two dedicated 10 benchmark tests, TF-1 and TF-2, that we use to help 11 inform our design analysis. TF-1 is shown on the top 12 left. And as mentioned before, it's actually a test 13 facility with three electrically-heated tubes where 14 we're mainly just focused on the thermal-hydraulic 15 phenomena happening inside of the tube. And tubes 2 16 and 3 were instrumented with acoustic pressure sensors 17 to look at the effect of the turbulence due to the 18 flow and boiling inside the tube. And they were 19 located at five different vertical heights along the 20 tubes.
21 CO-CHAIR CORRADINI: So, I don't 22 understand 3. I mean, we're looking down the throat 23 of it, but is it one column of tubes?
24 MS. HAND: So, yes, in this orientation, 25 actually, both the TF-2 and TF-3 images are shown on NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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145 1 their side. During flow testing, they're lifted to be 2 vertical.
3 CO-CHAIR CORRADINI: And it's essentially, 4 as we see with TF-2, it's a single column? It's a 5 single stacking versus multiple stackings?
6 MS. HAND: So, in the TF-3 image, you're 7 actually looking at two columns installed. So, TF-3 8 will, when it's completely built, consist of the five 9 middle columns.
10 CO-CHAIR CORRADINI: Oh, five?
11 MS. HAND: And it will be full prototypic 12 in height, and those are fully prototypic in the 13 dimensions of the columns and, also, the tube 14 supports. But we modal test. We're modal testing 15 columns 12, 11, and 9. So, that's showing like the 16 extent that is installed to allow modal testing of our 17 first column.
18 CO-CHAIR CORRADINI: Are you allowed to 19 say where is this testing being done?
20 MS. HAND: It's in Piacenza, Italy.
21 CO-CHAIR CORRADINI: Oh, it's still with 22 Ansaldo? Or whatever is the company now?
23 MS. HAND: Yes.
24 CO-CHAIR CORRADINI: Okay.
25 MS. HAND: Yes.
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146 1 MEMBER BALLINGER: Is that 690 tubing?
2 MS. HAND: It's actually not. As an 3 engineering simplification for the testing, we just 4 use stainless steel because the material properties 5 are similar enough for our modal testing and flow 6 testing needs.
7 Okay. So, to go back to TF-2, I guess, 8 TF-2 kind of was the next iteration of testing after 9 TF-1. So, it's a fluid-heated test facility where we 10 had flow on the inside and the outside. It was also 11 five columns and they were toward the outer third of 12 the steam generator, I think between half and two-13 thirds. That kind of corresponds to the bend radius 14 of the tubes.
15 CO-CHAIR CORRADINI: Are we allowed to --
16 how many columns, are you allowed to say, are the 17 full-scale steam generator?
18 MS. HAND: Twenty-one.
19 CO-CHAIR CORRADINI: Twenty-one?
20 MS. HAND: Uh-hum. And in TF-2, we 21 instrumented that facility with strain gauges which 22 were located about a third of the way and two-thirds 23 of the way up on the tube pipes.
24 And one thing to note about the TF-2 test 25 facility, we are still in the design process of NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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147 1 finalizing our steam generator tube support designs.
2 So, the TF-2 tube supports are only located or they 3 support at four radial locations throughout the bend; 4 whereas, the final design support is at eight 5 locations. So, based on that, the TF-2 testing, we 6 expect that those tubes are kind of, you know, have 7 lower frequencies, less stiffness than our final 8 design.
9 We tested up to 200 percent of our 10 licensing basis flow rates for the primary coolant in 11 that test facility, and we did not experience any 12 fluid loss against stability. So, that gives us some 13 good feeling about the results that we expect to see 14 in our final validation tests with our final design 15 tube supports installed.
16 MEMBER BALLINGER: This is just kind of a 17 personal observation. Six ninety, that is going to be 18 the first use of 690 for this kind of configuration, 19 I believe. Has there been any thought to actually 20 using 690 for some of these tests, so that you gain 21 experience from the actual fabrication using 690 in 22 this configuration?
23 CO-CHAIR CORRADINI: You're talking more 24 a fabrication issue.
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148 1 freebie. I mean, if you're building a test facility 2 already anyway --
3 CO-CHAIR CORRADINI: Nothing is free.
4 MEMBER BALLINGER: Okay.
5 MS. HAND: Yes, so I will say that I 6 wasn't directly involved with it, but I know we gained 7 a lot of experience through just the process of making 8 TF-3, regardless of the material that was used.
9 CO-CHAIR CORRADINI: Was TF-1 690 or was 10 it also stainless steel?
11 MS. HAND: I am not sure --
12 CO-CHAIR CORRADINI: Okay.
13 MS. HAND: -- but at that time I can say 14 that we probably had not even selected our material --
15 CO-CHAIR CORRADINI: Okay. Fine.
16 MS. HAND: -- for the steam generator 17 tubes. That testing was many years ago.
18 CO-CHAIR SKILLMAN: Olivia, I've been 19 wanting to ask this question since I saw this design.
20 When the individuals are creating this tube bundle, 21 are the individuals actually in the cylinder on their 22 hands and knees with pads, actually placing the tubes 23 into the locking devices? I say that because I 24 watched the B&W steam generators being assembled.
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149 1 capable, but smaller people to be in there to feed 2 those tubes --
3 (Laughter.)
4 -- all 15,100 of them. I mean, that was 5 a learning experience to fabricate the OTSGs, which 6 are handcrafted just like this. I'm just wondering, 7 is this a handcraft operation or?
8 MR. BRYAN: Let me turn it over to Tamas 9 Liszkai to address the 690 and fabrication part of it.
10 Tamas, are you there?
11 CO-CHAIR SKILLMAN: Okay.
12 MR. LISZKAI: Good afternoon. This is 13 Tamas Liszkai.
14 Yes, just wanting you to know that we kept 15 the mechanical properties. Alloy 690 and stainless 16 steel, for practical purposes, are identical. And 17 it's cheaper to procure that.
18 However, we did do fabrication testing 19 with alloy 690 tubing for our prototypical design.
20 That was a separate project from this one. It's not 21 included in the slides. But we used TCP as our Center 22 for Advanced Manufacturing in Philadelphia, to apply 23 the tubes in full prototypical length, alloy 690 24 tubes, and they used commercially-available banding 25 apparatus to actually do the 3-dimensional banding of NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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150 1 our tubes. The results of that were that everything 2 stays within tolerances.
3 CO-CHAIR SKILLMAN: Thank you.
4 So, how is the tube inserted into the 5 bundle?
6 MR. LISZKAI: This is Tamas Liszkai again.
7 I can answer that. It's not inserted into 8 the bundle. The current fabrication methodology that 9 we employ is column by column, going from the outside 10 in. And so, you would be placing the tubes 11 individually or in a group, slide it up in the 12 annulus. You would sort of uncoil them and insert 13 them down into the feed plenum. And then, you would 14 use these individual support bars to slide them over 15 the T-bar on top of the baffle plate, and just proceed 16 column by column, basically.
17 We have worked with two fabricators to 18 develop the fabrication process of that. And they 19 identified a very similar process of installation.
20 MEMBER BALLINGER: It's a 20-ton piece of 21 jewelry.
22 CO-CHAIR SKILLMAN: Thank you. I think I 23 can go from here. Thank you very much. That was very 24 helpful.
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151 1 again on this fluid-elastic instability. That's, I'll 2 call it, the new known/unknown, made famous here 3 recently by some operating experience. My question 4 is, have you convened any kind of expert panel or 5 anything to think about what other phenomena might 6 occur in this kind of style of steam generator that 7 you should be highlighting as your analysis point?
8 MS. HAND: Well, I guess my comment would 9 be that my personal opinion is that FEI is not an 10 unknown phenomena. It's been documented in literature 11 for years.
12 MEMBER SUNSERI: Yes, I know, but nobody 13 talked about it until more recently, right? I'm 14 overstating that. Okay, I understand that. But my 15 point is still, what about other phenomena that might 16 affect this particular design?
17 MS. HAND: So, I mean, the NuScale 18 approach with this is that in power applications we've 19 had components that looked like this in the past and, 20 essentially, even more limiting operating conditions.
21 I don't think we're going to discover new FIE 22 phenomena of interest. I think a lot of research has 23 been done on that in the past and they are pretty well 24 documented. The important part is to follow the code 25 and to use appropriate design analysis practices to NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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152 1 identify a problem before you get to operation and 2 discover it.
3 MEMBER SUNSERI: Yes, and I don't disagree 4 with that, but I will maybe push on just following a 5 code that's based on current or previous experience 6 may not be sufficient when you're going into first-of-7 a-kind new realms.
8 MS. HAND: Yes, and in that situation, you 9 know, specifically from the steam generator design, 10 that's why we couple our design analysis with 11 validation testing, measurement during startup 12 testing, and inspection following the startup testing, 13 so that we could never get to a similar situation like 14 SONGS of detecting this through primary-to-secondary-15 side leakage.
16 CO-CHAIR CORRADINI: That's the plan.
17 MEMBER SUNSERI: And just a closing 18 thought on that. I mean, if -- "if," and I know it 19 may be remote -- but if you discover a major problem 20 and it's way down the road late, to recover from that.
21 MS. HAND: Yes.
22 CO-CHAIR CORRADINI: You replace the upper 23 part of the NPM because it's integral to the NPM 24 module, upper portion. Yes?
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153 1 something important to point out with this TF-3 2 testing. Part of the reason, other than wanting to 3 collect higher quality and higher quantity of data by 4 having a dedicated test facility -- we could have just 5 said, hey, we're going to perform the string startup 6 testing. But that becomes a very commercially-risky 7 thing for us to do because, if there is a problem, we 8 want to find out years in advance of fabricating the 9 first module.
10 So, actually, commissioning of the TF-3 11 test facility, pictures shown here, modal testing 12 starts this summer. And then, it will be probably 13 about a two-year program to wrap up the flow testing.
14 That will provide us with the technical confidence 15 going into manufacturing phase that we don't have FIV 16 concerns for this part of the design.
17 MEMBER BALLINGER: But you say there 18 wasn't much data out there. I don't recall the exact 19 dimensions and everything, but the Fort St. Vrain 20 steam generators were helical and they had steam being 21 generated on the inside, I think, and gas on the 22 outside. But were the velocity, the parameters and 23 stuff, were they anywhere near what you're dealing 24 with?
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154 1 that because I happen to live in Denver. So, I could 2 visit the plant. But it was just --
3 MEMBER BALLINGER: So, it was colder then.
4 MS. HAND: The design was performed such 5 a long time ago that the documentation doesn't exist.
6 Since it's not still an operating plant, everything 7 has been kind of --
8 CO-CHAIR SKILLMAN: Lost?
9 MS. HAND: -- lost, lost in the shuffle.
10 But if we could get data from Fort St. Vrain, it would 11 be very interesting to compare against, but not 12 important to safety, since we are doing our own 13 testing. We did pursue that, but we couldn't find 14 anything.
15 MEMBER BALLINGER: That was designed using 16 a Commodore 64 computer.
17 (Laughter.)
18 CO-CHAIR SKILLMAN: I don't think there 19 was a Commodore.
20 (Laughter.)
21 MEMBER BALLINGER: Oh, you didn't even 22 have one of those, right? A slide rule.
23 (Laughter.)
24 MEMBER REMPE: Just out of curiosity, did 25 you try General Atomics and some of the people from NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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155 1 GA?
2 MS. HAND: No, we did not.
3 MEMBER REMPE: It might be worth 4 exploring.
5 CO-CHAIR CORRADINI: But your point is 6 you're going to do prototypic testing with a five-7 column generator to document what you are predicting?
8 MS. HAND: Yes. And then, we're going to 9 follow it up with instrumenting the steam generator 10 during the startup testing and inspecting it after 11 startup testing.
12 CO-CHAIR CORRADINI: Okay. Thank you.
13 MS. HAND: So, to move on to the 14 inspection program a bit, any component that's 15 screened for a mechanism will be inspected following, 16 well, both before and after startup testing. First, 17 just to get its initial view of what it looks like, 18 and then, after to see if any damage has occurred.
19 Obviously, turbulence is a lifecycle 20 issue. So, if we are seeing wear at the conclusion of 21 the startup test program, that means that we have a 22 strongly coupled mechanism that we need to look into.
23 And we're going to provide enough flow time at initial 24 startup test conditions to make sure that we provide 25 at least a million cycles of vibration for all of NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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156 1 these components. That should take about two-and-a-2 half days at full flow conditions for our plant. And 3 we'll be performing inspections in accordance with 4 ASME Section 11 guidelines.
5 CO-CHAIR CORRADINI: Is the thinking to 6 run a series of tests, stop, inspect, and then, go 7 back and run a series of tests?
8 MS. HAND: No. We're going to do all of 9 the testing, because this is one aspect that's 10 different for the NuScale design. This will be 11 performed during the initial startup testing after 12 core load.
13 CO-CHAIR CORRADINI: Oh, I'm sorry.
14 Excuse me. So, I thinking -- this is not TF-3?
15 MS. HAND: This is not TF-3, no. This 16 is --
17 CO-CHAIR CORRADINI: Okay. I'm sorry.
18 I'm sorry.
19 MS. HAND: Yes.
20 CO-CHAIR CORRADINI: Okay. Excuse me.
21 CO-CHAIR SKILLMAN: This was the CVAP.
22 This is the real deal.
23 MEMBER BALLINGER: But, presumably, you 24 could tinker with the flow restrictors and stuff like 25 that, if you detect an issue?
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157 1 MS. HAND: Could you explain that a bit 2 more?
3 MEMBER BALLINGER: I think if I'm 4 thinking --
5 CO-CHAIR CORRADINI: No, you got it right.
6 MEMBER BALLINGER: I got it right?
7 CO-CHAIR CORRADINI: Uh-hum.
8 MEMBER BALLINGER: There's individual, 9 well --
10 CO-CHAIR CORRADINI: Tube by tube.
11 MEMBER BALLINGER: Tube by tube almost 12 flow restrictors or maybe there's a different word for 13 it --
14 CO-CHAIR CORRADINI: It's a good word.
15 CO-CHAIR SKILLMAN: Flow restrictor.
16 MEMBER BALLINGER: -- which could be 17 tinkered with, meaning change the geometry a little 18 bit to alter the vibrational frequency that you're 19 having a problem with.
20 MS. HAND: So, yes. It sounds like you're 21 referring to the steam generator in that flow 22 restrictor --
23 CO-CHAIR CORRADINI: That's it.
24 MEMBER BALLINGER: Yes.
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158 1 drop on the secondary side as you're entering the 2 steam generator tube.
3 MEMBER BALLINGER: Yes.
4 CO-CHAIR CORRADINI: Right.
5 MS. HAND: So, that component is 6 susceptible, per our screening rules, to leakage flow 7 instability, and we have a separate effects dedicated 8 test facility where we'll be validating that before 9 initial startup testing --
10 MEMBER BALLINGER: But what I think I'm 11 meaning is, if you detect a vibrational problem in the 12 tubes, you could, in principle, modify the flow 13 restrictor to change that vibrational --
14 MS. HAND: Unless the vibration is coming 15 from the primary flow.
16 MEMBER BALLINGER: Okay.
17 MS. HAND: But, yes, if it's a concern 18 with secondary flow, that is a component that could be 19 modified.
20 Okay. There is one COL item in this area, 21 and that is that, prior to any of these validation 22 tests, we will provide test procedures and submit 23 results, both results of the flow testing and the 24 inspection results testing, in accordance with the Reg 25 Guide. The purpose of this COL item is just to NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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159 1 continue to have engagement with the regulator as we 2 move through this last phase of the CVAP program.
3 If there are no other questions about 4 CVAP, I can move on to the short-term transient 5 analysis. The short-term transient analysis is 6 modeling of the dynamic effects associated with a 7 pressure wave that's generated when you have a breach 8 in a high-energy pressure boundary.
9 CO-CHAIR CORRADINI: To the vessel or to 10 the containment?
11 MS. HAND: Both.
12 CO-CHAIR CORRADINI: Okay.
13 MS. HAND: Yes, both. Although the one 14 going into the vessel is stronger since it's moving 15 through a subcooled fluid. Whereas, the containment 16 is at vacuum conditions or maybe a low-pressure steam 17 condition.
18 CO-CHAIR CORRADINI: Okay.
19 MS. HAND: For this analysis, we use our 20 thermal-hydraulic code, RELAP5, to generate the 21 boundary conditions at the break. So, we take the 22 pressure, the mass flow rate, the density, and we 23 convert that into a fluid acceleration and, also, a 24 thrust force. The fluid acceleration gets applied to 25 acoustic elements in the ANSYS structural model, and NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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160 1 the thrust force gets applied to the structural, 2 pretty much like the diameter of the piping in that 3 model.
4 And then, we use ANSYS to simulate the 5 fluid structure interaction, using a time history 6 analysis, and the outputs are the forces and moments 7 on different structures inside of the NuScale power 8 module. And then, those eventually get used in the 9 component stress analysis, similar to what Dylan was 10 talking about for the seismic results.
11 CO-CHAIR CORRADINI: Is this to help 12 determine restraints or is this to look at --
13 MS. HAND: It's just to generate a design 14 basis load that needs to be considered when you --
15 CO-CHAIR CORRADINI: For restraint, for 16 placing of restraints for the piping, I assume?
17 MS. HAND: No, not really. Just a load 18 that needs to be evaluated for a component. If the 19 load was unacceptable, we would have to come up with 20 a design solution for it.
21 CO-CHAIR CORRADINI: So, let me ask you a 22 question. What if the IAV doesn't work and I start 23 discharging ECCS above the prescribed pressure? Is 24 that analyzed?
25 MS. HAND: Yes.
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161 1 CO-CHAIR CORRADINI: It is?
2 MS. HAND: It is.
3 CO-CHAIR CORRADINI: Okay. So, at the 4 full pressure, you actually look at a discharge of an 5 ECCS valve, both RVV and RRV?
6 MS. HAND: That's correct.
7 CO-CHAIR CORRADINI: Okay.
8 MS. HAND: And that, actually, hadn't --
9 well, it has two notes on that. One, the IAV didn't 10 exist at the time that that analysis was first 11 performed, and then, it was conservative to carry that 12 forward in the future.
13 And the other note, too, is these loads 14 are not very limiting compared to, you know, when 15 you're talking about your 14-inch, double-ended 16 guillotine break in a traditional PWR.
17 So, the first point of this slide, you 18 know, we're analyzing primary coolant lines that are 19 only NPS 2 and we have no double-ended guillotine 20 breaks. So, when the break happens, the wave is 21 traveling into the containment and into the vessel.
22 It can't go into the vessel two ways. Like if you 23 have a break in a traditional PWR, the valves, 24 specifically the vent valve, represents the largest 25 breach --
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162 1 CO-CHAIR CORRADINI: Can you remind me?
2 I apologize. Excuse me. But "NPS" is a designation 3 for a pipe size?
4 MS. HAND: Nominal pipe size, correct.
5 CO-CHAIR CORRADINI: Okay.
6 MS. HAND: Yes. So, about a 2-inch pipe.
7 We also operate at lower pressures than 8 traditional PWRs. We have less sub-cooling, which is 9 important for the change in enthalpy that happens and 10 the power that you see in the rarefication wave.
11 And then, the CNV is a single sub-12 compartment. So, we don't have to do multiple sub-13 compartment analyses for the different rooms in 14 containment and loads that walls are seeing, since we 15 don't have any walls.
16 Legacy codes that you might be familiar 17 with are how applicants have analyzed this problem in 18 the past, but with the more state-of-the-art 19 technology now, we just used our thermal-hydraulic 20 code and ANSYS. So, codes that we were using in the 21 company for other purposes. It allows us to simulate 22 this phenomena a lot more accurately.
23 CO-CHAIR CORRADINI: Let me just make sure 24 I understand what you just said.
25 MS. HAND: Yes.
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163 1 CO-CHAIR CORRADINI: So, with NRELAP, what 2 are you using as the critical flow model that you say 3 is accurate?
4 MS. HAND: We investigated sensitivities 5 with both Henry-Fauske and Ransom-Trapp. And Henry-6 Fauske showed a slightly better comparison to 7 literature.
8 CO-CHAIR CORRADINI: Good.
9 MS. HAND: So, we went with that.
10 CO-CHAIR CORRADINI: Okay. I'm happy.
11 MS. HAND: Okay. So, to move on to the 12 benchmarking and this analysis a bit, we used three 13 different open-source literature test cases to show 14 that our predictions are accurate using this method.
15 The main one we used was the Heissdampf reactor, which 16 was a test facility in Germany in the 1980s. And we 17 were able to obtain a lot of pressure and displacement 18 data.
19 What we did is we used that to kind of 20 determine what parameters we needed to set at what 21 levels to match the experimental data the best way we 22 could. So, what is shown in this image on the upper 23 right is the Heissdampf reactor is experiencing a 24 break in the hot leg and this break is very, very 25 nearly located to the core barrel. And there is a NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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164 1 sensor on the core barrel that measures the 2 differential pressure as a function of time. And 3 again, for these events, we are just looking at a few 4 milliseconds. That's when the important phenomena 5 happens in terms of the forces and moments.
6 So, in this sensitivity case, we looked at 7 different discharge coefficients for our choking 8 model, and really for all of them, they just slightly 9 over-predicted the differential pressure that would be 10 seen across the core barrel, which is appropriate for 11 performing this type of dynamic analysis.
12 So, these parameters that we, you could 13 call it, tuned in terms of our benchmarking problems, 14 were the optimal settings that were used in the 15 NuScale power breach locations. And then, we analyzed 16 all of our breach locations and took the maximum 17 forces and moments determined over the whole spectrum 18 of breaks that we looked at, and we put them in a 19 loading spec. And then, our component stress analysts 20 used them for the ASME code stress evaluations.
21 CO-CHAIR CORRADINI: So, I don't want to 22 take too much time, but I want to make sure I 23 understand. This is not the steady-state blowdown?
24 You're looking at the initial transient response from 25 a break?
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165 1 MS. HAND: Correct.
2 CO-CHAIR CORRADINI: And all your breaks 3 are either near-saturated conditions or steam 4 conditions, is that correct?
5 MS. HAND: We also had some subcooled 6 breaks, for example, when the reactor recirculation 7 valve opens, because that sees cold leg temperature.
8 CO-CHAIR CORRADINI: Okay. So, did you 9 look at the Marviken experiments?
10 MS. HAND: We did.
11 CO-CHAIR CORRADINI: You did?
12 MS. HAND: We did, yes.
13 CO-CHAIR CORRADINI: Okay. Okay, but 14 these look more limiting in terms of the geometry?
15 That's what I --
16 MS. HAND: So, the Marviken we used just 17 for showing that our boundary conditions were 18 accurate. We did not find helpful force or 19 displacement information as far as impact.
20 CO-CHAIR CORRADINI: They just didn't have 21 the data?
22 MS. HAND: Yes.
23 CO-CHAIR CORRADINI: I see. Okay. Okay.
24 MS. HAND: The Heissdampf reactor was kind 25 of the whole deal. It validated our thermal-NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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166 1 hydraulics and our structural. Marviken we used 2 mostly for thermal-hydraulics and the Bettis hydraulic 3 pressure pulse was mostly for structural.
4 CO-CHAIR CORRADINI: Okay.
5 MS. HAND: So, we kind of looked at a 6 spectrum of things to make sure we were covered for 7 our operating conditions that we were going to be 8 analyzing and the forces and moments that we would be 9 seeing.
10 CO-CHAIR CORRADINI: Thank you. Thank 11 you.
12 MS. HAND: And that's it, and there are no 13 COL items in that area.
14 CO-CHAIR SKILLMAN: How are those results 15 -- your next-to-the-last bullet, "Bounding breach 16 locations analyzed, maximum forces determined," how is 17 that captured so that your documentation demonstrates 18 NuScale components thoroughly fit for duty? How is 19 that captured?
20 MS. HAND: Ultimately, it will be captured 21 in the ASME designer port for each component.
22 CO-CHAIR SKILLMAN: Okay.
23 MS. HAND: And then, in the interim, since 24 we've only really gotten to the final point of 25 generating the loads, those are in the loading spec NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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167 1 which is referenced in all of the design 2 specifications. So, those tables that provide all of 3 the loads you need to consider direct you to go to the 4 loading spec to get this load for a certain component.
5 CO-CHAIR SKILLMAN: Thank you. Okay.
6 Thank you very much.
7 Colleagues, do you, do any of you, have 8 additional questions for our NuScale colleagues?
9 (No audible response.)
10 NuScale, thank you very much.
11 MS. HAND: Thank you.
12 CO-CHAIR SKILLMAN: You are able to leave.
13 A question of protocol to the NRC staff:
14 would you like to begin now or begin at 12:30? Up to 15 you, whichever you choose. We were going to be on 16 break until -- we were going to drive until 12:30, and 17 then, lunch from 12:30 to 1:15. My question is, NRC, 18 would you like to begin now or take an hour for lunch 19 now and come back at 1300? Either, it's up to you, 20 whichever you choose.
21 Lunch? You good?
22 We are in recess for 60 minutes. We will 23 come back at 5 minutes at 1:00 on that clock.
24 (Laughter.)
25 Thank you. NuScale, thank you very much.
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168 1 (Whereupon, the above-entitled matter went 2 off the record at 12:06 p.m. and resumed at 1:02 p.m.)
3 MS. VERA: Good afternoon. Oh, sorry.
4 CO-CHAIR SKILLMAN: Please, go ahead.
5 MS. VERA: Okay. Good afternoon everyone.
6 I'm Marieliz Vera, the Operating Manager for the 7 Chapter 3 of the NuScale DC Application with you.
8 Today we're going to present Section 9 3.9.2, Dynamic Testing and Analysis of System 10 Structures and Components. The rest of Chapter 3 will 11 be presented on June 8 -- in the June 18 subcommittee 12 meeting.
13 For the agenda, we're going to -- I'm 14 going to introduce the staff. We'll have an overview.
15 And then we're going to talk about the NuScale Power 16 Module Level D analysis and the Reactor Internal 17 Comprehensive Vibration Assessment Program, or CVAP.
18 So, the review team is Dr. David Ma, Yuken 19 Wong, and Dr. Steve Hambric, Marieliz, myself, and the 20 lead project manager is Greg Cranston. Now I'm going 21 to turn it over to Yuken Wong so he can say.
22 MR. WONG: My name is Yuken Wong. I'm in 23 the Mechanical Engineering Branch. I'm sorry. My 24 name is Yuken Wong in the Mechanical Engineering 25 Branch in the Division of Engineering Safety Systems NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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169 1 and Risk Assessment in NRO.
2 I'm going to discuss the review of the 3 NuScale DC Application 3.9.2. The review is conducted 4 according to the standard rebuild plan, and the 5 relevant -- and the relevant Reg Guide.
6 Reg Guide 120 is the reactor internals' 7 comprehensive vibration assessment program. Reg Guide 8 1.61 is the damping values for seismic design. Reg 9 Guide 1.122 is the Development of Floor Response 10 Spectra.
11 I'm going to present a review of the 12 following two areas in Section 3.9.2. The first one 13 is a dynamic system analysis of the reactor internals 14 under Level D conditions.
15 Level D is the folder condition involving 16 the simultaneous safe earth down -- safe shut down 17 earthquake and pipe breaking events.
18 And the other is the reactor internals' 19 Comprehensive Vibration Assessment Program, or CVAP.
20 CO-CHAIR SKILLMAN: Dr. Wong, before you 21 proceed, may I please ask our colleague from NuScale 22 for a follow up? Would you permit me to do that, 23 please?
24 MR. WONG: Yes. Thanks.
25 CO-CHAIR SKILLMAN: Dylan, please proceed.
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170 1 Identify your name and your issue.
2 MR. ADDISON: This is Dylan Addison from 3 NuScale. I need to issue a correction to a question 4 you asked, Gordon, about whether the fluid elements in 5 the ANSYS model are designated as compressible or 6 incompressible. They are compressible.
7 That's one of the underlying assumptions 8 of the element formulation.
9 CO-CHAIR SKILLMAN: Thank you, sir. Dr.
10 Wong, please proceed. Excuse me. Thank you.
11 MR. WONG: All right. Thanks. The 12 NuScale power module dynamic analysis under Level D 13 conditions, the DCA application 3.9.2 and Appendix A 14 contain a summary of the dynamic analysis and the 15 NuScale power module seismic analysis and technical 16 report.
17 It contains the detailed analysis methods, 18 including motion, structure, or modeling of major NPM 19 components and analysis results. Including 20 displacement, in structural response spectra, seismic 21 forces, and movements and component interfaces.
22 The staff focused a review on the reactor 23 vessel internals and steam generator components. The 24 review includes structural modeling, analysis methods, 25 low combination, input motion, fluid modeling, fluid NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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171 1 distribution, damping value, depth conditions, stress 2 classification and linearization, ASME Section Three 3 stress acceptance criteria, and stress phase out.
4 The short term transient report provides 5 the pipe break structural loads for reactor vessel 6 internal stress analysis. And the Section 3.9.2 7 reveal is focused on the ANSYS modeling.
8 The -- NuScale's 3D ANSYS NPM model 9 consists of five --
10 MEMBER REMPE: Just a second.
11 CO-CHAIR SKILLMAN: Excuse me. For those 12 who are on the phone line, would you please mute your 13 phone? Please proceed.
14 MR. WONG: Okay. The NuScale 3D ANSYS NPM 15 model consists of five set sub-models. The 16 containment of the model with the reactor pool, the 17 reactor pressure vessel, lower reactor vessel 18 internals, upper reactor vessel internals, and the 19 control rod drive mechanism.
20 These sub-models are connected by coupling 21 nodes, constrained equations, contact elements, and 22 fluid coupling. The connection methods are revealed 23 along with other in fluent aspects such as the 24 adequate number of elements.
25 The 3D ANSYS NPM model is converted to the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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172 1 equivalent beam ANSYS model, and then the equivalent 2 beam SAP2000 model. The SAP2000 model is used for the 3 reactor building SASSI analysis.
4 The dynamic responses of the models are 5 matched through tuning the mass distribution and 6 stiffness. The staff reviewed this tuning process.
7 The 3D ANSYS NPM model is modified to 8 include the entire volume of the reactor pool. The 9 NPM reactor pool model contains the Bay 1 NPM module 10 or the Bay 6 NPM module.
11 Nonlinear time history analysis is 12 performed on the NPM entire pool model by applying the 13 acceleration time history from the SASSI analysis as 14 boundary conditions at the pool floor, walls, and NPM 15 supports.
16 CO-CHAIR SKILLMAN: Why were Bay 1 and Bay 17 6 chosen?
18 MR. WONG: The analysis show the location 19 in Bay 1 and Bay 6 provides the bounding values --
20 CO-CHAIR SKILLMAN: Thank you.
21 MR. WONG: For all other Bays.
22 CO-CHAIR SKILLMAN: Okay. Thank you.
23 MR. WONG: Next slide. I'm going to 24 discuss in the following slides, some of the result 25 issues, as well as the four remaining open items.
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173 1 Next slide, please.
2 In the original analysis, NuScale assumed 3 that 7 percent damping for safe shutdown earthquake in 4 the NPM system and component seismic analysis. This 5 7 percent damping is higher than the damping specified 6 in Reg Guide 1.61, Table Six, for pressure vessels and 7 major pressure boundary components. Which is 8 specified as 3 percent.
9 Reg Guide Table One specifies 4 percent 10 for welded steel or bolted steel with friction 11 connections. Which means no sliding. And specifies 12 7 percent for bolted steel with bearing connections, 13 which allows sliding.
14 NuScale's justification for using 7 15 percent damping are the reactor vessel internal joints 16 allow sliding. Which are similar to the bolted scale 17 structures with bearing connections in Reg Guide 1.61.
18 The recommended values is 7 percent.
19 There are many sliding steam generator to 20 support interfaces which generate large friction of 21 the space at forces. Next slide, please.
22 The staff noted that there are many valve 23 structures in the reactor vessel internals. Such as 24 the weld between the lower core plate and the core 25 barrel. The Reg Guide specifies 4 percent.
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174 1 The steel to steel coefficient of friction 2 is smaller underwater then in dry condition. Because 3 the fluid -- the water film acts as a lubricant. So, 4 the 7 percent damping will not be achieved in the 5 steam generators.
6 In response to the NRC concern, NuScale 7 will use 4 percent instead of 7 percent for the NPM 8 seismic analysis. The staff finds that 4 percent 9 damping acceptable, because the integrated NPM with 10 many connections and internal structures is unlike 11 traditional shell type pressure vessels.
12 And there is additional energy dissipation 13 provided by the connections and internal structures.
14 This issue has been resolved and closed.
15 CO-CHAIR CORRADINI: Sorry. So, the first 16 open item has been resolved?
17 MR. WONG: This --
18 CO-CHAIR CORRADINI: I'm sorry, excuse me.
19 So the first open item that you were discussing with 20 us is resolved?
21 MR. WONG: In the Phase Two of the SE, 22 this is not an open item. It's just that we --
23 CO-CHAIR CORRADINI: Oh.
24 MR. WONG: Yeah. We want to bring it up 25 because this is one of the issues that we raised and NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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175 1 resolved.
2 CO-CHAIR CORRADINI: Okay. Okay. Thank 3 you.
4 MR. WONG: Okay. In the figure it shows 5 the core barrel. And inside the core barrel we factor 6 blocks. And there's a thin fluid gap between that.
7 In the original analysis, this fluid gap 8 was not considered. So the frequency of the core 9 barrel and the reflectors are lower due to the added 10 mass effects of the fluid gap.
11 So in response to the NRC concern, NuScale 12 did a sensitivity study. And found the loads at the 13 upper and lower core barrel are higher if the gap is 14 considered, if the fluid gap is considered.
15 So, they revised the analysis to include 16 the modeling for the fluid gap using ANSYS four year 17 nodes. And the staff finds the approach acceptable, 18 because the dynamic response of two concentric 19 cylinders with a fluid gap in between can be simulated 20 by four year nodes. This issue is resolved.
21 The NuScale NPM modules are submerged in 22 a pool of water. Analyzing the NPM in a pool of water 23 for seismic responses are new and unique to NuScale.
24 Initially NuScale assumed the reflection 25 of acoustic waste energy 100 percent -- excuse me, 100 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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176 1 percent reflection of the acoustic wave energy at the 2 bottom of the pool.
3 So in a seismic analysis when applying 4 frequency shift, the acoustic mode of the pool aligns 5 with the structural mode of the NPM module. And this 6 led to unreasonable and excessive amplification of the 7 structure response.
8 So, in reality, the acoustic wave energy 9 is constantly reflected and passively absorbed by the 10 concrete floor and the surrounding soil. Next slide, 11 please.
12 CO-CHAIR SKILLMAN: No. Not so fast.
13 Back up one. What is the transmitter for the 14 acoustical energy?
15 CO-CHAIR CORRADINI: What creates the 16 initial pulse? The assumption?
17 MR. WONG: The seismic event.
18 CO-CHAIR CORRADINI: Okay.
19 CO-CHAIR SKILLMAN: Oh, okay. Very good.
20 Thank you.
21 MR. WONG: So, in order to estimate the 22 acoustic absorption coefficient at the bottom of the 23 pool, NuScale created two interesting models.
24 The first model is the integrated model 25 including the NPM reactor pool water, reactor NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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177 1 building, and the backfill soil. And a damping was 2 applied to the concrete and backfill soil to dissipate 3 the pool acoustic energy.
4 And Model two is the standard NPM model 5 within NPM and the reactor pool water. Various 6 acoustic absorption coefficients are applied at the 7 bottom of the reactor pool to dissipate the pool 8 energy, the pool via the acoustic energy.
9 One G vertical acceleration was applied at 10 the bottom of the pool of the two models. And then 11 compared the responses at the key NPM locations 12 between the two models.
13 And absorption coefficient of .75 produced 14 the best match between the two models. To verify the 15 acoustic absorption analysis and the -- the NRC staff 16 with the assistance from Dr. Ma and Dr. Hambric 17 performed an audit in December 2018. Next slide, 18 please.
19 During the audit NuScale modified the 20 absorption coefficient from .75 percent to .4 percent.
21 The staff concluded the absorption coefficient of .4 22 percent reasonable, because the damping in the 23 building structure and the surrounding soil dissipates 24 acoustic energy.
25 The staff also compared the impedance NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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178 1 ratio between concrete and water based on the 2 absorption coefficient of .4. And the impedance rate, 3 the actual impedance ratio between concrete and water 4 based on the density and speed of sound.
5 The impedance ratio, based on the 6 absorption coefficient of .4 is higher. Higher 7 impedance ratio leads to more acoustic wave reflection 8 and less obstruction, and is more conservative.
9 Therefore, this issue is resolved and 10 closed. Next slide, please.
11 In Division Zero of the seismic --
12 CO-CHAIR CORRADINI: Can I ask a question?
13 I'm sorry that --
14 MR. WONG: Yes.
15 CO-CHAIR CORRADINI: I was reading it, and 16 I didn't think fast enough. But your initial source 17 is within the ground, right?
18 Or are we thinking of it as horizontal 19 shaking and then a reflection? I'm still trying to 20 figure out where the source is relative to the 21 reflection and transmission.
22 But you're looking at this as essentially 23 at the base of the reactor pool, right? The 24 absorption coefficient?
25 MR. WONG: Yes.
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179 1 CO-CHAIR CORRADINI: Okay.
2 MR. WONG: It's at the base of the pool, 3 yes. Between the --
4 CO-CHAIR CORRADINI: But the seismic wave 5 is coming up from below? Is that -- am I 6 understanding this correctly?
7 MR. WONG: We're looking for the -- at the 8 bouncing of the --
9 CO-CHAIR CORRADINI: Right.
10 MR. WONG: Of the acoustic energy. Which 11 is --
12 CO-CHAIR CORRADINI: Yeah, how much passes 13 through the interface and how much essentially is 14 reflected, right?
15 MR. WONG: Yes.
16 CO-CHAIR CORRADINI: Right, okay.
17 DR. HAMBRIC: Remember, they're using a 18 two-part modeling approach. They've got the big model 19 that generates the loads that are being applied to the 20 reactor.
21 Then you go to the small model with just 22 the water in the pool, and the approximate absorption 23 coefficient, and shake the reactor around.
24 CO-CHAIR CORRADINI: Oh. That's --
25 DR. HAMBRIC: And they needed one of those NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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180 1 to respond appropriately.
2 CO-CHAIR CORRADINI: So now we're shaking 3 the reactor in the water. And this is what it's 4 applied to.
5 DR. HAMBRIC: Yeah. And if you don't put 6 that absorption coefficient on it, you get this crazy 7 amplification.
8 CO-CHAIR CORRADINI: Yeah. Sure.
9 DR. HAMBRIC: Which is, you know, close 10 too real.
11 CO-CHAIR CORRADINI: And .4 is close 12 enough?
13 DR. HAMBRIC: It's --
14 CO-CHAIR CORRADINI: I mean, I would just 15 take the ratio of Row C over Row C and use that. But 16 that's two best estimates?
17 I -- you see my question?
18 DR. HAMBRIC: They're aware of the actual 19 impedance ratio. They have chosen to be conservative 20 and use .4.
21 CO-CHAIR CORRADINI: Okay. Fine.
22 CO-CHAIR SKILLMAN: Which is acceptable.
23 And .4 is more conserv -- is conservative compared to 24 .75?
25 DR. HAMBRIC: Um-hum.
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181 1 CO-CHAIR SKILLMAN: Okay.
2 CO-CHAIR CORRADINI: Okay. Go ahead.
3 Thank you. Sorry.
4 MR. WONG: Okay. In Revision Zero of the 5 seismic chemical report, it states that the in-6 structure response spectra at the location of the 7 equipment supports within the NPM envelope and point 8 according to ASCE 4-13 for component design.
9 ASCE 4-13 is the standard for seismic 10 analysis of safety related nuclear structures. ASCE 11 4-13 permits a 15 percent reduction of the narrow 12 frequency peak amplitude of the in-structure response 13 spectra if certain conditions are met.
14 The staff finds the use of ASCE 4-13 in 15 the generation of ISRS not consistent with Reg Guide 16 1.122. The Reg Guide does not permit the reduction of 17 frequency peak amplitude.
18 In response to the NRC concern, NuScale 19 stated that frequency amplitude reduction was not 20 performed in the generation of ISRS. And removed ASCE 21 4-13 from the description of the generation ISRS and 22 made the revision to the scientific report. So, this 23 issue is resolved and closed.
24 I'm going to discuss the open items in the 25 Phase 2 SE. In the original analysis, NuScale NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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182 1 considered six cases for the seismic analysis. Some 2 of the cases are in nominal or 77 percent nominal NPM 3 stiffness.
4 The staff concern is that it 130 percent 5 of nominal NPM stiffness should be considered to 6 account for the uncertainty in the NPM model input and 7 assumptions. The plus/minus 30 percent stiffness is 8 equivalent to plus/minus 15 percent of frequencies.
9 So, it's a standard practice to perform 10 frequency shift in the seismic analysis. So, if not 11 considering the 130 percent of the NPM stiffness, we 12 will -- it's possible to have a conservative seismic 13 analysis results.
14 So, in response, NuScale performed 12 15 seismic analysis runs, including the 130 percent 16 nominal NPM stiffness. And they have included the 17 result in Revision Two of the Seismic Report.
18 And it's currently under review. Next 19 slide, please.
20 CO-CHAIR CORRADINI: So, can you go back?
21 So, I'm not familiar. So, the 77 percent and the 130 22 percent are equivalent?
23 MR. WONG: Equivalent like plus/minus.
24 CO-CHAIR CORRADINI: That's what I 25 guessed. Okay.
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183 1 MR. WONG: Yeah. Um-hum.
2 CO-CHAIR CORRADINI: All right. Thank 3 you. That's what I didn't catch. Thank you very 4 much.
5 DR. SCHULTZ: And then the -- what is the 6 resolution here? They've performed --
7 CO-CHAIR CORRADINI: They're in the middle 8 of that.
9 DR. SCHULTZ: The evaluation.
10 MR. WONG: They performed additional 11 cases.
12 DR. SCHULTZ: Yes.
13 MR. WONG: Including the 130 percent NPM 14 stiffness, that is equivalent to plus 30 percent, you 15 know, NPM stiffness.
16 DR. SCHULTZ: And now they've included a 17 broader evaluation, including the 130 percent 18 stiffness.
19 MR. WONG: Yeah. They updated seismic 20 analysis. And instead of having six cases originally, 21 now there are 12 cases to consider. Or to finding the 22 boundary values.
23 DR. SCHULTZ: Okay.
24 CO-CHAIR CORRADINI: To find -- thank you, 25 that will help me. To find the boundary line for?
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184 1 MR. WONG: The component response for the 2 stress analysis.
3 CO-CHAIR CORRADINI: Okay. Thank you.
4 DR. SCHULTZ: And that's currently under 5 review? That --
6 MR. WONG: Correct.
7 DR. SCHULTZ: By the staff. Thank you.
8 DR. WONG: Okay. Here's the picture of 9 the reflector blocks on the upper right. The 10 reflector blocks are sitting on the lower core plate.
11 And they are restrained in the horizontal 12 direction, with a long piece. But they are not 13 restrained vertically.
14 And these, as you can see on the lower 15 right, the lower core plate in-structural response 16 spectra shows at the high frequency peak the 17 acceleration exceeds the gravity acceleration.
18 So, the concern is that during a seismic 19 event, the reflector blocks may uplift. And this 20 uplift was not considered in the original seismic 21 analysis.
22 So, in response to the NRC concern, 23 NuScale updated the seismic model, the seismic 24 modeling to include contact elements between the lower 25 core plate and the reflector blocks, to simulate NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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185 1 uplift.
2 And the analysis shows that the uplift 3 distance of the reflector blocks is small. And it 4 will not close the gap between the reflector blocks 5 and the upper core plate.
6 The staff revealed the analysis modeling 7 results, and found the response acceptable.
8 CO-CHAIR SKILLMAN: What are the contact 9 elements that you refer to here?
10 MR. WONG: The contact element is the 11 ANSYS modeling to -- between the reflector block and 12 the lower core plate.
13 CO-CHAIR SKILLMAN: So it is an analytical 14 model?
15 MR. WONG: Yes. It's a modeling technique 16 that can capture the position uplift of the reflector 17 blocks.
18 CO-CHAIR CORRADINI: So they model the 19 interface by using a contact finite element model. Is 20 that -- am I understanding this correctly?
21 MR. WONG: Yes. Using the contact 22 elements between the two --
23 CO-CHAIR CORRADINI: You've got two 24 blocks. And then you have a contact element between 25 them.
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186 1 MR. WONG: Right.
2 CO-CHAIR CORRADINI: But it's -- to get to 3 Member Skillman's question, it's not real. It's a 4 modeling -- it's a modeling approach to try to model 5 the contact between the two blocks?
6 MR. WONG: Correct.
7 CO-CHAIR CORRADINI: Okay. So is the open 8 item closed?
9 MR. WONG: Yes. So this is a Phase 2 SE 10 open item. And it has sense closed.
11 CO-CHAIR CORRADINI: Okay. Thank you.
12 DR. SCHULTZ: And so from what you show 13 acceleration (off mic) 14 CO-CHAIR SKILLMAN: Mike Steve.
15 DR. SCHULTZ: Oh, excuse me. You're 16 showing acceleration. You did mention that the uplift 17 was small.
18 What's small?
19 MR. WONG: Another concern is that the 20 reflector blocks will uplift and impact the upper core 21 plate. So, the uplift distance is small.
22 So, it will not impact the upper core 23 plate.
24 CO-CHAIR CORRADINI: I think he's asking 25 for how small. A millimeter? A centimeter? I think NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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187 1 that's what you're asking.
2 DR. SCHULTZ: Yes. Because --
3 MR. WONG: Then NuScale can speak to it.
4 And I'm not sure. They can discuss the value.
5 MR. ADDISON: This is Dylan Addison from 6 NuScale. The uplift of the reflective blocks from the 7 lower core plate is on the order of a sixteenth of an 8 inch more or less.
9 DR. SCHULTZ: Thank you.
10 CO-CHAIR SKILLMAN: Does that sixteenth of 11 an inch, even though it's small, impose a momentum 12 load when the gap closes?
13 MR. ADDISON: So, when -- Dylan Addison 14 again. When the reflector block impacts with the core 15 plate, it does change the loads on the lower core 16 plate.
17 And those transmit into the fuel. And we 18 are analyzing the fuel for those loads.
19 CO-CHAIR SKILLMAN: Is that load 20 significant or not significant?
21 MR. ADDISON: Well, we think that we have 22 a clear path forward for demonstrating the fuel 23 integrity with those loads. So, it's different then 24 it would be modeled linearly.
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188 1 not yet resolved that you believe you have a success 2 path ahead.
3 MR. ADDISON: And that will be addressed 4 in Chapter 4.
5 CO-CHAIR SKILLMAN: Thank you. All right.
6 Thank you.
7 CO-CHAIR CORRADINI: Hold on. Addressed 8 in Chapter 4 by a subsequent open item because of the 9 fuel -- because the fuels -- the fuel response to a 10 seismic event, is that where we're going?
11 MR. ADDISON: That's correct.
12 CO-CHAIR CORRADINI: Got it. Okay. Thank 13 you very much.
14 MR. WONG: Okay. In this figure it shows 15 in normal operation the NPM modules are in the 16 operating bay. And during refueling the NPM will be 17 in the flange tools for disassembly.
18 NuScale introduced a nonlinear contact 19 elements and the interface between the lower reactor 20 pressure vessel and the refueling flange tube to 21 simulate the uplift of the NPM during a seismic event.
22 And the results are documented in Revision 23 Two of the Seismic Report. And the Seismic Report is 24 currently under review. Next slide, please.
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189 1 to provide a seismic analysis details and Level D 2 stress results for the major NPM components and a 3 steam generator major NPM components.
4 NuScale provided the stress evaluation 5 results in their REI response. However, the results 6 are based on the original six cases without a 130 7 percent NPM stiffness.
8 NuScale will provide the new results using 9 the 12 cases, including the 130 percent NPM stiffness 10 case in a supplemental response. And the staff will 11 review this supplement and the results.
12 CO-CHAIR CORRADINI: But this one, if I 13 understand what you're saying, this is connected to 14 the original one for seismic analysis, where they're 15 going from six to 12 cases.
16 It's the same 12 simulations. And you're 17 using the results to answer these questions. Have I 18 understood this correctly?
19 MR. WONG: The 12 cases generate a new 20 instructive response factor.
21 CO-CHAIR CORRADINI: Right. Okay. Got 22 it.
23 MR. WONG: It's just --
24 CO-CHAIR CORRADINI: I'm with you. Thank 25 you very much.
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190 1 MR. WONG: Okay. Then the next topic is 2 the reactor internals' comprehensive vibration 3 assessment program. Next slide, please.
4 The staff basically reviewed primarily on 5 two technical reports. One is the comprehensive 6 vibration assessment technical report. And the second 7 one is the measurement and inspection plan technical 8 report.
9 The staff also conducted three audits to 10 review the un-docketed information. The staff 11 attended face to face meetings with NuScale and 12 conducted periodic conference calls with NuScale to 13 discuss the issues.
14 And now I'm going to turn over to Dr.
15 Hambric to discuss the CVAP review.
16 DR. HAMBRIC: Okay. Thanks Yuken. This 17 is Steve Hambric from Penn State University. And I've 18 broken this next section up into a couple of parts.
19 The first one is a high level overview 20 with a bottom line up front assessment of the risk 21 areas as we see them. And they're the same as what 22 NuScale showed you.
23 But I'll go into following that in more 24 detail on each of those components. What areas in 25 particular are a concern about, and how we hope to NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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191 1 move forward and resolve them.
2 So here are the big FIV mechanisms that 3 were evaluated. The first one turns out quite benign, 4 turbulent buffeting.
5 That's not benign in traditional reactors 6 because the flow is a lot faster. As NuScale has 7 pointed out to you, their natural circulation reactor, 8 the flow is very low.
9 And turbulent buffeting load scale on an 10 exponent of flow speed. So, it's really not a major 11 concern for them.
12 The other ones are. Things like vortex 13 shedding and lock in of that vortex shedding with the 14 structural residence is of great concern to us.
15 There's a couple of structures we're looking at there.
16 Fluid elastic instability is even worse 17 the vortex shedding. And in particular we're looking 18 at one structure there.
19 Acoustic residence, those are the types of 20 loads that have been causing us trouble with BWRs in 21 the fleet now. Fluids over standpipes generating big 22 high amplitude pressure waves that in the case of BWRs 23 were damaging steam dryers with fatigue failure.
24 And the next two are leakage flow 25 instability, and then flutter and galloping.
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192 1 CO-CHAIR CORRADINI: Which are or aren't 2 of concern?
3 DR. HAMBRIC: Leakage flow instability is.
4 So, there's a couple of components we'll talk about 5 there.
6 Flutter and galloping, we were able to 7 retire that risk. There should be no issue in the 8 NuScale plans for that.
9 As NuScale pointed out, they did screen 10 all their components. And we did check. There was a 11 thorough screening.
12 And the ones in the box are the ones that 13 have less than 100 percent margin. And we'll focus 14 the rest of our time on here today.
15 The helical coil steam generator is not 16 typically reviewed in this chapter. But since it's 17 integral to the reactor here, it is. And so we'll 18 focus here on that quite a bit.
19 The steam generator inlet flow 20 restrictors, as we'll see in a little while, are being 21 looked at for leakage flow instability. Make sure 22 they're not subject to that.
23 Control rod drive shaft and in-core 24 instrument guide tubes, I'll show you some pictures of 25 that in a moment. But they're in cross flow. So NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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193 1 we're looking at them for that.
2 And then really any piping at all that has 3 a side branch, we have been looking at along with 4 NuScale to look for the possibility of acoustic 5 residence.
6 You may have seen in the SE that that box 7 extended down a bit to include the CRAGT. That is no 8 longer a concern of ours. And so we won't talk about 9 it today. But, details of that assessment are in the 10 Phase Two SE.
11 So, risk areas. You've seen that diagram 12 on the right before. It is a natural circulation 13 plant. So the flow heads upward through the center.
14 And then when it reaches the top, it makes 15 a U-turn and heads back down past all the steam 16 generator tubes. Flow is nice and slow. And 17 depending on where you look, the flow rates are say, 18 five to 25 times lower then you might see in a typical 19 PWR.
20 And if you think back to previous design 21 applications, a lot of the reviews that were done, a 22 lot of effort, a significant effort was spent on 23 benchmark and turbulent loading, but because the flows 24 are so fast. And they had to do that because those 25 loads were important and could lead to high NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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194 1 alternating stresses and potentially fatigue.
2 And that's just not the case here. So 3 you're not going to see much of that at all in our 4 review. So, that's a good thing.
5 However, low flow or not, you still have 6 to evaluate flow over other components to look for the 7 things we talked about earlier, vortex shedding, fluid 8 elastic instability, and leakage flow, things like 9 that.
10 Particular in the NuScale plant, you have 11 some very long thin rods and tubes. The ICIGT and 12 CRDS in particular. That's non-typical.
13 And --
14 CO-CHAIR CORRADINI: What's the S --
15 DR. HAMBRIC: Hum?
16 CO-CHAIR CORRADINI: You're talk -- oh.
17 Helium coil steam generator. Okay. Fine.
18 DR. HAMBRIC: Yeah. Right. And an extra 19 high --
20 CO-CHAIR CORRADINI: And what's the ICIGT?
21 DR. HAMBRIC: Inlet core instrument guide 22 tube. Control rod drive shaft. And I should have 23 mentioned, there's a list of all the acronyms towards 24 the back if you want a cheat sheet.
25 CO-CHAIR CORRADINI: But one more time, NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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195 1 ICIGT?
2 DR. HAMBRIC: In core instrument guide 3 tube.
4 CO-CHAIR CORRADINI: Ah. From a --
5 DR. HAMBRIC: You'll see a picture of it 6 in a minute.
7 CO-CHAIR CORRADINI: Okay. Okay.
8 DR. HAMBRIC: Those are long thin 9 structures, and it doesn't take a lot of cross flow to 10 potentially lock into them.
11 Also, it's really impossible to come up 12 with a piping system that has no side branches. And 13 in this case the decay heat removal system piping does 14 have some.
15 And they are potentially subject to 16 acoustic resonance. But NuScale's done everything 17 they can do to mitigate their amplitude.
18 But nevertheless, it is a risk area that 19 we'll talk about. Most regions where leakage flow 20 instability could occur generally are in low pressure 21 difference regions.
22 However, there are a couple of locations 23 we're paying more attention to, the steam generator 24 and the flow restrictors, and maybe a few other 25 locations that we'll talk about later. So, those are NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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196 1 the big ones that you'll be hearing about through the 2 rest of the brief.
3 Now NuScale screening studies used well-4 established methodologies. A lot of them come right 5 out of the ASME Boiler and Pressure Vessel Code, 6 Appendix N, which spends a lot of material on flow 7 induced vibration of tubes.
8 But also two other well recognized names 9 in our area, Blevins Flow and Use Vibration, Second 10 Edition is really a primer on this area. And then 11 M.K. Au-Yang has a nice textbook.
12 It's really a cookbook set of formulas you 13 can use to assess flow and use vibration of power and 14 process line components. So those are all good 15 references to use.
16 But they do require calculations for 17 running those methodologies. Particularly you need 18 flow velocities, you need structural modes, mode 19 shapes, frequencies, mobile masses, and you need 20 damping.
21 So, for two of those, NuScale has used 22 calculation methodologies for the flow speeds.
23 They're using CFD methods.
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197 1 into the system and the steam generator which takes 2 heat out, are highly simplified. They're just sort of 3 modeled as bulk regions.
4 So even they don't get local flow 5 velocities out of those simulations. So, you get a 6 mean flow velocity and then you have to sort of make 7 some assumptions to get to the peak velocities after 8 that.
9 The FE models are generally of individual 10 components, structural models. And simplified 11 boundary conditions are assumed.
12 And these are intended to give you the 13 lowest resonance frequencies. So when we walk through 14 some of these mechanisms that potentially lock into 15 modes, you're really looking for the lowest resonance 16 frequency and the highest excitation frequency. So 17 those are what you're after.
18 Damping, that's very hard to calculate.
19 And in Reg Guide 1.20 we allow 1 percent without any 20 proof. And in general, NuScale is at or below 1 21 percent except in one case, where they're assuming one 22 and a half percent.
23 And the Reg Guide calls for pretty 24 rigorous substantiation of that, because if you 25 increase damping, you're reducing margin -- or you're NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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198 1 increasing your margin. You're reducing the vibration 2 of your structure. So we'll talk about that one 3 instance more coming up.
4 Margins of safety, even with NuScale's 5 conservatisms, are low by FIV standards. Being within 6 10 percent of a lock in is not a great place to be.
7 Here they are for the steam generator.
8 They got 20 percent against vortex shedding and lock 9 in. Ten percent against fluid elastic instability.
10 CO-CHAIR CORRADINI: Would their test 11 program help in removing what is apparent closeness to 12 a margin?
13 DR. HAMBRIC: Absolutely. Yeah, we'll 14 talk about that.
15 CO-CHAIR CORRADINI: Okay.
16 DR. HAMBRIC: And reactor vessel 17 internals, the only two of concern are the control rod 18 drive shaft and in core instrumentation guide tubes.
19 Both coincidentally with about 25 percent margin 20 against vortex shedding.
21 The side branches and the decay heat 22 removal system piping, you have about a 20 percent 23 margin against what I'm going to call primary acoustic 24 resonance. But no margin against secondary. And hold 25 that thought, and we'll get into the details of what NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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199 1 primary and secondary mean in a few slides here.
2 The steam generated in the flow restrictor 3 has low risk. And that's based on some testing that 4 NuScale did of several design concepts.
5 But, the final design so it's unquantified 6 risk. And there's testing pending to hopefully retire 7 that risk.
8 Now, during our review, we did uncover 9 some non-conservatisms that may outweigh the 10 conservatisms that NuScale cited.
11 And all of those are currently being 12 addressed by NuScale via the RAIs. And you'll find 13 them in the open items. And I should have added, 14 there is a list of all the open items at the end of 15 all this that you can refer to.
16 And as I go through the individual 17 components in detail, I've got the open item on the 18 cover sheet. So you can see which goes with which.
19 Now, the non-conservatisms really span 20 most of these components. I didn't link them to a 21 specific component.
22 Instead we just talked about the non-23 conservatisms in general. And so here they are broken 24 down into a flow modeling, structural modeling, and 25 then one extra concern at the end there.
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200 1 So the flow modeling, it is using a course 2 simplified COD model. And there's a couple of things 3 to worry about there.
4 Number one, even though turbulent 5 buffeting, we don't think is a big concern, the 6 empirical forcing functioning models that they 7 employed, call for peak free stream velocities to be 8 used.
9 For example, if you had annular flow in 10 the flow rising up through the core. It's a big pipe 11 flow essentially. And the boundary layers would meet 12 in the center of the pipe.
13 And to estimate wall forcing functions in 14 that sort of flow, you would go to the center peak 15 velocity, plug that into your empirical model along 16 with some other parameters, and estimate a forcing 17 function.
18 NuScale took their CFD solution, averaged 19 it over that region, and that lowered the velocity.
20 Therefore, lowering the forcing functions.
21 So we've been having kind of long debates 22 about that. And we're waiting for an RAI response 23 from that to resolve it.
24 CO-CHAIR CORRADINI: So this is -- this is 25 the way you describe it is taking the peak velocity is NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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201 1 a standard approach?
2 DR. HAMBRIC: That is the approach that 3 the empirical models assume you have done. It's the 4 edge of your boundary layer, the edge of your annual 5 flow.
6 The other one that's a little more of 7 concern, because again, turbulent buffeting, we don't 8 think there's going to be a problem, is the spatial 9 variability of the flow. Particularly around the 10 steam generator.
11 Modeling that is just a bulk region in 12 getting one velocity. We know from past experience, 13 and I'll show an example of that, that the flow can be 14 quite inhomogeneous through steam generators. It goes 15 where it wants to go.
16 And you're going to have regions of high 17 speed flow and regions of low speed flow. And that 18 has not been accounted for yet.
19 In the structural modeling, the meshes we 20 have seen to date are pretty course. And course find 21 it on the structural meshes biases resonance frequency 22 is high.
23 And as we'll see momentarily, what we're 24 after is the lowest resonance frequency and the 25 highest flow excitation frequency. That's a NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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202 1 conservative comparison. And so we've asked them a 2 question about that for analyzing each of their 3 components.
4 There are also some boundary conditions 5 that gave us pause. I'll show you examples shortly.
6 But, some of the structures go through supports. But 7 the supports aren't really supports.
8 And they've assumed idealized somewhat 9 pinned boundary conditions. That gives you shorter 10 structures. That gives you higher resonance 11 frequencies. Again, non-conservative.
12 And also we've had to verify that the 13 fluid loading, that all of these components are 14 sitting in water. Then we have to make sure that the 15 added mass is conservative and drives the frequency as 16 low as is possible.
17 Now the final concern is that if these 18 margins hold up, if you're looking at 10 to 20 percent 19 margin, and by margin we mean, how close is the 20 resonance frequency of the structure to the excitation 21 frequency of the flow.
22 If they're within 10 percent, you really 23 need to do a force response calculation. So for all 24 NuScale has done, is just compare the frequencies and 25 said, if they don't match, we've got margin.
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203 1 CO-CHAIR CORRADINI: So Steve, what do 2 they have to do? I didn't understand.
3 DR. HAMBRIC: So, so far they're just 4 looking for coincidence of excitation frequency and 5 structural response frequency.
6 CO-CHAIR CORRADINI: Right.
7 DR. HAMBRIC: And saying that if they're 8 not coincident, they're good.
9 But if those frequencies start coalescing 10 within 10 percent say, that structure is going to 11 respond to that vortex shedding. It won't lock into 12 it, but it's certainly going to respond.
13 And so far there's been no forced response 14 calculation done. If --
15 CO-CHAIR CORRADINI: So you would have to 16 assume some sort of distribution function to look at 17 how the two things interact. That's your point?
18 DR. HAMBRIC: You'd have to drive the 19 structure with a vortex shedding source, with whatever 20 your frequency offset is. And examine how much 21 further that is.
22 CO-CHAIR CORRADINI: And rule of thumb is, 23 it's got to be how far apart before you can ignore 24 that?
25 DR. HAMBRIC: There's not a great rule of NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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204 1 thumb. It depends. But 10 percent is well within 2 that rule of thumb I'd say.
3 CO-CHAIR CORRADINI: But if it doesn't 4 have --
5 DR. HAMBRIC: I'd do an analysis if it was 6 within 50 just to be sure.
7 CO-CHAIR CORRADINI: Oh. Within 50 8 percent? So then you'd have a --
9 DR. HAMBRIC: That's just Steve Hambric's 10 rule of thumb. There may be other rules of thumb they 11 can cite in the literature as well.
12 CO-CHAIR CORRADINI: But your point is --
13 your point is that you -- the practice that you would 14 do is if you were within a factor of two, you'd want 15 to look at how the two tales interact --
16 DR. HAMBRIC: A factor of 50 percent.
17 CO-CHAIR CORRADINI: Oh. It depends on 18 whether it's in the numerator or denominator. But, 19 okay.
20 DR. HAMBRIC: Right.
21 CO-CHAIR CORRADINI: I'm with you.
22 DR. HAMBRIC: But that's me. And again, 23 everybody has their own rule of thumb. But, I'm not 24 aware of one that's in the literature.
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205 1 design certification applications, such as AP1000, 2 they performed the forced vortex shedding response 3 analysis for the reactor internal components.
4 CO-CHAIR CORRADINI: Say that again, 5 please. I'm sorry. So AP1000, they did what was 6 suggested?
7 MR. WONG: Correct, correct.
8 CO-CHAIR CORRADINI: Okay.
9 DR. HAMBRIC: And I'd like to go on the 10 record as saying that that 50 percent is not a 11 direction to NuScale or anybody else.
12 CO-CHAIR CORRADINI: No.
13 DR. HAMBRIC: That's a response to an ACRS 14 --
15 CO-CHAIR CORRADINI: Just an opinion.
16 DR. HAMBRIC: -- question and opinion.
17 CO-CHAIR CORRADINI: Yeah, okay.
18 DR. HAMBRIC: There has not been a lot of 19 testing done to date. Part of that is because the 20 turbulent buffeting is not a concern for the NuScale 21 plant. So there's less than usual, and the focus is 22 different. In previous plants, there's been a lot of 23 focus on benchmarking, what those forces are, and 24 whether they're being appropriately estimated.
25 Here, we're looking at slightly different NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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206 1 issues. Now, there is a concern. This is a unique 2 new design. There are some interesting innovative new 3 features. And there's no operating history to lean 4 on.
5 The other thing we've asked them early on 6 is the possibility of some pre-operational FIB 7 testing. But that's just not feasible, because 8 there're no pumps to pump the flow through. It's a 9 natural circulation design. However, I'll say it 10 again. The turbulent buffeting benchmark just really 11 isn't necessary.
12 So we're taking an alternate approach, but 13 we believe it's a valid alternate approach. And that 14 is looking at some preliminary validation testing 15 which is focusing on the key FIB mechanisms we're 16 talking about here that have low margins of safety and 17 high uncertainty. And I'll go into the details 18 shortly.
19 And additional startup testing, instead of 20 being a benchmarking test, is really focused on 21 disaster insurance, making sure nothing bad is going 22 on in there. We've seen past best intentions lead to 23 unexpected flow induced vibration at nuclear plants 24 before. We don't want it to happen here.
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207 1 anyway, to instrumenting the inside of the plant to 2 look for unexpected surprises and, if those surprises 3 occur, to be able to localize them so they know what 4 component to go back and examine more closely and 5 hopefully fix. We've not seen any of that yet, that's 6 pending. But that's one of our open items.
7 CO-CHAIR CORRADINI: So, Steve, could you 8 please -- I'm sorry, go on.
9 MEMBER SUNSERI: I thought the plant has 10 a module heating system that they use to get the 11 natural circulation flow going initially when the core 12 is cold. And you can't use that to get some flow 13 data?
14 DR. HAMBRIC: I'll let NuScale address 15 their reasons for why they don't think hot functional 16 testing is reasonable.
17 MS. HAND: So this is Olivia Hand. The 18 module heat up system is really just to heat the plant 19 up and to get enough flow so we can mix boron. Flow 20 rates that we're talking about here are up against our 21 maximum mechanical design allowable velocities.
22 So we're, you know, like, operating this 23 regime maybe we could get to about, like, 20 percent 24 of those velocities. But it wouldn't give us any 25 spill vibration information.
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208 1 CO-CHAIR CORRADINI: And if you did that, 2 extrapolating that extra factor of five is 3 inappropriate? In other words, I seem to remember by 4 some other curve, which I think is in the open, 5 somewhere around 15 or 20 percent you can switch over, 6 go critical, and away you go.
7 So at 20 percent of that, that's still not 8 enough to give you some indication that what you ---
9 I'm looking more of a benchmark of what you calculate, 10 I assume that's where Matt was going, what you 11 calculate versus what you see.
12 MS. HAND: So similar to what Steve was 13 saying, you know, having the module instrumented 14 during initial startup testing, we kind of have been 15 referring to it as go/no go testing.
16 We're not going to be able to collect, you 17 know, vibration information that's going to 18 necessarily validate these safety margins. Because 19 vortex shedding is either going to occur or it's not 20 going to occur. So we're hoping to just measure 21 that's not occurring.
22 You know, you need to be able to increase 23 velocities to the point that it does occur in order to 24 collect meaningful vibration data which would be per 25 our design analyses above our licensing basis maximum NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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209 1 flow rates.
2 CO-CHAIR CORRADINI: Okay.
3 MS. HAND: So as you extrapolate down to 4 the lower power conditions, you're going to just move 5 further away from that.
6 CO-CHAIR CORRADINI: Okay, thank you.
7 DR. HAMBRIC: And just to preview, the 8 testing they are proposing outside of the plant but in 9 prototypic conditions, we like it because they're 10 going to go well above their design flow speeds.
11 They'll find where these mechanisms occur and show us 12 how much margin they've actually got.
13 CO-CHAIR CORRADINI: So TF-3 helps?
14 DR. HAMBRIC: TF-3 helps, and what they're 15 going to do with the steam generator in the flow 16 restrictor also helps.
17 CO-CHAIR CORRADINI: Okay.
18 DR. HAMBRIC: Being able to run at super 19 high speeds to tell us what margin they've got will 20 definitely be an improvement over trying to do hot 21 functional testing.
22 CO-CHAIR CORRADINI: But I wanted to make 23 sure. Does that, at least for the steam --- I'm 24 looking back to your list of all of your areas of 25 worry. This essentially deals with the steam NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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210 1 generator tubes, but it doesn't deal with the reactor 2 vessel internals.
3 DR. HAMBRIC: It will.
4 CO-CHAIR CORRADINI: How so?
5 DR. HAMBRIC: Oh, being able to run at a 6 higher speed. Yeah, we couldn't run it at higher 7 speed. But the reactor vessel internals, other than 8 the steam generator, steam generator and the flow 9 restrictor, CRDS, ICIGT, we don't have significant 10 concerns about.
11 CO-CHAIR CORRADINI: Oh, I see. Okay.
12 All right, so it more actually is the margin from the 13 steam generators?
14 DR. HAMBRIC: Yeah, that would be 15 determined with outside testing. And really, the 16 initial startup testing is meant for disaster 17 insurance. Nothing else is going on that we might 18 have missed, in spite of our best intentions.
19 DR. SCHULTZ: Just so it's clear, the 20 staff proposed the following for reasonable assurance.
21 Where, in fact, do things stand in terms of the 22 program that NuScale is going to perform?
23 DR. HAMBRIC: We'll go through all those 24 details coming up.
25 CO-CHAIR CORRADINI: That's coming up.
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211 1 DR. HAMBRIC: Why we think they're valid.
2 DR. SCHULTZ: Okay. Thank you.
3 DR. HAMBRIC: Okay, so that's the 4 overview. And now I've got short sections on each of 5 the key areas with a header sheet on each one and the 6 open items associated with it.
7 So the first one is looking at vortex 8 shedding and lock-in but of two components, the 9 reactor vessel internals, it's actually two in that, 10 and the helical coil steam generator tubing.
11 So this is vortex shedding. I pinched 12 this off the Internet. So the picture you're looking 13 at is --
14 CO-CHAIR CORRADINI: It's not your 15 experiment? I'm shocked.
16 DR. HAMBRIC: It is not my experiment. It 17 is actually a simulation. I used to have the citation 18 for it, but I left it out of here. I probably should 19 have added it. But that's flow over a cylinder. And 20 this is problem that's been studied to death for many, 21 many, decades now.
22 But what you're looking at is, at a 23 certain flow speed, the vortices that are building up 24 behind it, remember just how they're really kind of 25 moving up and down. And it's probably a little bit NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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212 1 harder to see, but they're also pushing back and 2 forth. And so that's a magic flow condition where 3 those vortices are out of phase with each other and 4 drive that cylinder both up and down, and backwards 5 and forwards.
6 By itself, that's nothing to worry about.
7 If that cylinder starts moving, and I don't have an 8 animation of that, but I'll use an example in a 9 minute, if the cylinder starts moving, either shaking 10 up and down or going back and forth, it's going to 11 reinforce the strength of those vortices, make them 12 even stronger.
13 That in turn makes the structure vibrate 14 more which in turn strikes as a vortices, and you end 15 up with this feedback. Eventually, there's a limit, 16 but that limit is not someplace you want to be.
17 CO-CHAIR CORRADINI: That's when the two 18 ---
19 DR. HAMBRIC: This is when they coincide.
20 CO-CHAIR CORRADINI: Okay, that's what I 21 thought.
22 DR. HAMBRIC: If they're a little bit off 23 in frequency, that cylinder's still going to move and 24 vibrate, but not nearly to the point where it will if 25 they coincide.
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213 1 CO-CHAIR CORRADINI: And if I'm outside of 2 the, I'm trying to remember all your acronyms, if I'm 3 talking about the control rod drives and the in ---
4 (Simultaneous speaking.)
5 DR. HAMBRIC: Yeah.
6 CO-CHAIR CORRADINI: -- this is calculable 7 once I do a screening.
8 DR. HAMBRIC: Exactly.
9 CO-CHAIR CORRADINI: That's your point.
10 DR. HAMBRIC: Yep.
11 CO-CHAIR CORRADINI: Okay.
12 DR. HAMBRIC: We'll get to all of that.
13 So the classic example of this is not really a 14 cylinder. It's like Tacoma Narrows Bridge which 15 collapsed in 1940, classic vortex shedding, lock-in 16 problem that nobody paid attention to going in.
17 CO-CHAIR CORRADINI: And everybody's seen 18 the movie.
19 DR. HAMBRIC: Everybody's seen the movie.
20 Look it up online, it's engineering disasters 101. So 21 we don't want that to happen.
22 Now, how can that happen? It takes more 23 than just a coincidence of the frequencies. It also 24 takes a low impedant structural node. That means low 25 mass, or low damping, or both. So we'll talk about NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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214 1 ASME criteria for that in a minute.
2 Now, the curious thing about this vortex 3 shedding phenomena, I've got this little plot over 4 here on the right. The transverse forcing, what I'm 5 going to call the lift, and this is over time, it's at 6 a higher frequency, or excuse me, a lower frequency 7 than the unsteady drag force.
8 So the drag force is loading this thing at 9 twice the frequency. Why does that matter? Because 10 you're getting closer to the structural nodes. So 11 it's actually the drag frequency you're mostly worried 12 about here, intentionally lock in to a structural 13 frequency.
14 Now, the good news is this has been 15 studied so much we've got a nice formula that 16 everybody uses that you can back out the velocity at 17 which you're going to have vortex shedding or the 18 frequency. And it's a Strouhal number. That's what 19 the ST is. It happens to be a quarter.
20 F is frequency, D is the diameter, which 21 you know, and U is your velocity. So if you know your 22 flow velocity, you know your diameter, you can back 23 out the frequency of that excitation and compare it to 24 the structural resonance frequency and see how close 25 you are. And that's your initial screening, really.
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215 1 And so here are the reactor vessel 2 internals we're concerned about. And we'll talk about 3 helical coil steam generator in a minute. But on the 4 left is the array of ICIGTs, and these are just half 5 of them. There's a symmetry plane about the middle.
6 And up at the top, in the boxes, is where 7 the rods are in cross flow. So over on the left, CFD 8 analyses and the DUN (phonetic) are the flow speeds up 9 at that top region, And those four velocities are 10 compared to the diameters. Look at the 11 Strouhal number, you've got a frequency of vortex 12 shedding, both in the lift and in the drag direction.
13 CO-CHAIR CORRADINI: But I'm not putting 14 the whole rod -- the whole rod is not seen. I'm 15 seeing 10 or 15 percent of the length. That is not 16 considered in the Strouhal number rule of thumb.
17 DR. HAMBRIC: Correct. So it'd just be 18 over that top section which is a good thing. It means 19 ---
20 CO-CHAIR CORRADINI: Right, I was going to 21 say ---
22 DR. HAMBRIC: -- it'll be less likely to 23 lock in, we're hoping, is the case.
24 CO-CHAIR CORRADINI: So the rest of this 25 acts essentially as a long anchor relative to these NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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216 1 things wiggling up at the top when the flow turns on 2 you.
3 DR. HAMBRIC: Well, let's talk about that.
4 CO-CHAIR CORRADINI: Okay.
5 DR. HAMBRIC: Over on the right you've got 6 the control rod drive shaft, bigger tubes. All of 7 these rods are going through little holes in the 8 support drills. So if you look, you can see these 9 little kind of grills showing up.
10 CO-CHAIR CORRADINI: Yeah.
11 DR. HAMBRIC: And they've got to 12 periodically space throughout the riser. And they've 13 got different holes for the ICIGTs and different holes 14 for the control rod drive shaft.
15 NuScale is assuming that those gaps are 16 small enough that they can represent them as pinned 17 boundaries.
18 CO-CHAIR CORRADINI: Pinned?
19 DR. HAMBRIC: Pinned.
20 CO-CHAIR CORRADINI: P-I-N-N-E-D?
21 DR. HAMBRIC: Yes.
22 CO-CHAIR CORRADINI: So is this ---
23 DR. HAMBRIC: Not exactly pinned, but kind 24 of close. They're restraining in plain motion at 25 those boundaries. They're allowing vertical motion.
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217 1 They're restraining in flow (phonetic) motion. What 2 it effectively does is limit your mode shapes to 3 between the supports which shortens your length, which 4 increases your resonance frequency, which gives you 5 potentially biased margin.
6 The ICIGT gaps are pretty small. So that 7 may be true, but we've seen nothing to really confirm 8 that. You get a squeeze film effect that could cause 9 a pinned condition.
10 Control rod drive shaft, the gaps are much 11 bigger. These things have to be able to drop. So we 12 really can't argue that point for the CRD shaft holes.
13 They're much larger gaps. So we view the worst case, 14 the most conservative resonances as due to the longer 15 sections, lower frequencies, more of a chance of 16 locking in. So that's a open item that NuScale is 17 busy addressing.
18 The helical coil steam generator tubing, 19 the only ones we have to worry about are down near the 20 bottom. Here, the boundaries are those blue sections.
21 Those are the supports, and so looking at the 22 unsupported lengths of tubing and the flow over those 23 lengths of tubing.
24 The supports are these little clips. And 25 There's little schematics of them over on the right.
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218 1 And there are clearances about maybe 10,000, a little 2 bit less. You have to have clearance, otherwise you 3 can't put it together. So they're supposed to kind of 4 snap in there.
5 The argument NuScale is making, and we're 6 waiting for calculations to substantiate this is, when 7 you turn the heat on, the thermal expansion of 8 everything should lock it all together. If that's the 9 case, some good things happen.
10 Number one, there really shouldn't be any 11 cause to worry about an inactive support, if any of 12 those clips are just --- the boundary clearance is too 13 big, then you've got a tube that's just got a floating 14 space which means that you're unsupported length is 15 longer, your resonance frequency is lower, you have 16 more risk for locking into the vortex shedding. So if 17 all the supports are fully active, we're in excellent 18 shape.
19 NuScale is also assuming their supports 20 are pinned, but if you look on the upper right, 21 they've set the clips up cleverly so that each tube 22 really has two supports on one side and one on the 23 other. And it sort of alternates as you go through 24 the tubes.
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219 1 restricting translational motion but moments as well.
2 And that's a stiffer boundary condition which 3 hopefully drives the resonance frequencies higher.
4 But we have not seen proof of that yet, and we're 5 hoping to get that proof in this new testing they're 6 doing that we're going out to have a look at in about 7 a month.
8 CO-CHAIR CORRADINI: You'll go and 9 actually see the test rig?
10 DR. HAMBRIC: Yes.
11 CO-CHAIR CORRADINI: Okay.
12 DR. HAMBRIC: So let's talk about lock-in 13 avoidance criteria. ASME provides us with some very 14 concrete criteria in the pressure vessel and piping, 15 Appendix M. And here it is. I'm going to walk 16 through this and then lead up to a pretty important 17 parameter that we also need confirmation of, and 18 that's damping.
19 So the hatched region is the bad region.
20 This is where flow over a cylindrical cross section 21 could lock in and lead to synchronized response, and 22 really high vibration amplitudes, and potential 23 impacting of the nearby supports which we don't want.
24 That would mean a lot of wear over time and potential 25 failure.
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220 1 So the vertical axis is speed. So down at 2 the bottom is no flow. And then when you crank the 3 flow up, you're going faster, faster, faster, faster.
4 And eventually, you hit the bottom of this cross-5 hatched region. And that's where the structural 6 resonances start locking in.
7 This is a non-dimensional velocity, it's 8 maybe called a critical velocity. It's actually the 9 inverse of the Strouhal number. But they're dividing 10 by the resonance frequency restructure and the 11 diameter of your tube.
12 CO-CHAIR CORRADINI: Say that again 13 please, slower.
14 DR. HAMBRIC: Yes. That is the inverse of 15 the Strouhal number.
16 CO-CHAIR CORRADINI: Where you're not 17 computing the frequency, you're actually --
18 DR. HAMBRIC: Right.
19 CO-CHAIR CORRADINI: So using the first 20 mode resonance frequency of the structure.
21 DR. HAMBRIC: Plug that in, plug your 22 diameter in, and you'll get a critical velocity which 23 is, in fact, what they did.
24 CO-CHAIR CORRADINI: Okay, got it.
25 DR. HAMBRIC: So they want to see if NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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221 1 they're in that cross-hatched region. Now, here's 2 this structural impedance parameter. It's actually 3 called a mass damping parameter. And this has been 4 around for a long time, suggested by people that have 5 done vortex shedding, lock-in over cylinders.
6 And there's two terms that they're after.
7 One is the non-dimensionalized mass, so that's the 8 modal mass of your structure. So if you have a big, 9 heavy tube, you have a big heavy mass. But it's non-10 dimensionalized by essentially the mass of your 11 forcing function which is this density of the fluid 12 times the diameter squared. So that's the effective 13 mass of the water displaced by the structure. So if 14 you're in a heavy fluid, that gives you a smaller mass 15 parameter.
16 The delta is damping. That's why they 17 call it mass damping, mass times damping. Now, good 18 things happen when mass goes up, when we slide over to 19 the right. And good things happen when damping goes 20 up, and we slide over to the right. We escape that 21 synchronized range, completely.
22 If you look in the ASME guidance, there 23 are criteria A through D. And I've got them in the 24 appendix if you want to look them up. Three of those 25 criteria pretty much say the same thing. It's make NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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222 1 sure your frequencies don't align. You don't want the 2 excitation frequency to align with the structural 3 frequency. And that's these guys.
4 And I'm not going to go over them at all.
5 Just try to make sure your flow velocity is as low as 6 possible and your resonance frequencies are as high as 7 possible. But for the helical coil steam generator, 8 NuScale assumed the damping of one and a half percent.
9 Okay, so there's a couple of things on 10 Criteria B. And that just says make sure your mass 11 damping is above 32. Now, NuScale went and computed 12 their critical velocities, their reduced velocities 13 for the modes in the helical coil steam generator.
14 And that's that up and down error.
15 This is the range they're in. Sometimes 16 they're well below this range, but there are a few 17 modes that are above it. However, if you see one and 18 a half percent damping, and you come to the end of 19 that synchronization region, all is well. There's no 20 way that structure can possibly lock in to the vortex 21 shedding. It's just got too much damping to do it.
22 If you go back and use one percent 23 damping, as we do in Reg Guide 1.20, that slides over 24 to the left, right, your mass damping parameter is 25 down by 50 percent. And then some of your modes are NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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223 1 falling in that synchronization range. That doesn't 2 mean they'll lock in, but it means they could.
3 CO-CHAIR CORRADINI: This is where you're 4 saying that past applicants essentially did an 5 analysis of excitation versus structural resonance 6 routes?
7 DR. HAMBRIC: No. This is just looking at 8 whether you have a shot at locking in.
9 CO-CHAIR CORRADINI: No, I understand.
10 But ---
11 DR. HAMBRIC: Oh, oh, if that happens, yes 12 --
13 CO-CHAIR CORRADINI: If that happens the 14 next recommendation would be to do a more detailed 15 analysis.
16 DR. HAMBRIC: Right.
17 CO-CHAIR CORRADINI: Okay, all right. I 18 got it.
19 DR. HAMBRIC: So I'll jump forward a bit 20 to what they're trying to do with this next testing.
21 If they can confirm that the resonance frequencies 22 that they've been assuming so far are, in fact, 23 conservatively low, and that their bounding conditions 24 are, in fact, stronger, and the resonance frequencies 25 go up, I come over here, and I put in a bigger NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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224 1 resonance frequency, the F of N gets bigger. That 2 slides down. My reduced velocity comes down and goes 3 out of the synchronization range. So there's two 4 paths to success.
5 CO-CHAIR CORRADINI: This way or down?
6 DR. HAMBRIC: One, get the resonance 7 frequency as high as you can and prove to us that 8 that's where they're going to be in the real plant.
9 Two, if you've really got one and a half percent 10 damping, prove it. And if they can prove it, we'll 11 accept it. And we can retire that risk.
12 Okay, so that's vortex shedding. Next up 13 is just the helical coil steam generator but now 14 looking at something called fluid elastic instability 15 which is worse than vortex shedding.
16 So this involves not only a lock-in 17 between a flow excitation mechanism and a structural 18 resonance, but the lock-in with multiple structural 19 resonances which all influence the flow.
20 So I don't know if anybody's seen an 21 animation, I should have probably tried to bring one, 22 of an array of tubes experiencing FEI. But it's 23 pretty dramatic. Probably ought to find them on the 24 Internet sometime.
25 But this is just an example of many NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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225 1 measurements that have been done in this phenomena.
2 It's an array of four tubes, up here in the upper 3 right. And these little paths you're seeing here, 4 kind of clockwise and counter-clockwise motion, that's 5 what happens when you get full on, fluid elastic 6 instability of that array.
7 All of those cylinders start vibrating out 8 of phase with the others. So if you look at one, it 9 might be moving clockwise, the one next to it will be 10 counterclockwise, and the next two are clockwise. And 11 as they do that, they're all grabbing hold of the 12 fluid and shaking it around and reinforcing the flow 13 excitation.
14 It's the same sort of mechanism just 15 different. If this starts happening, then it's 16 serious trouble. So this is an example of a 17 measurement over several different tube types. This 18 time, I've got flow speed on the bottom. But here's 19 increasing flow. And this time I've got to vibration 20 amplitude in the Y Axis.
21 So all the measurements start out with low 22 flow, and they measure the vibration of the cylinders.
23 And it starts going up, and in this particular case, 24 this is a vortex shedding.
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226 1 it does not lock in. The amplitude comes back down 2 again. They keep increasing the flow, and then this 3 coupled phenomenon, where all the tubes are moving and 4 combining when the flow excitation kicks in.
5 And it doesn't take much to go up to ---
6 this is a factor of six up here, just monstrous 7 vibration amplitude. It becomes unbounded until these 8 cylinders start hitting each other. And then 9 everything goes non-linear, and who knows what happens 10 after that. But that's not a position you want to 11 find yourself in.
12 So the good news is, people have done a 13 lot of measurements on these tubes. NuScale mentioned 14 Connors. He really did the most famous ones. And his 15 constants are used to this day in all of the cookbooks 16 that you'll find on avoiding this mechanism.
17 And these were tube arrays in cross flow, 18 different amounts of mass, different amounts of flow 19 speed, different diameters, different damping. And 20 the reason they did all of these ranges of tests was 21 to try to come up with a universal design criteria 22 that you could use.
23 S.S. Chen went through and did the same thing, 24 but with helical coil steam generators many years 25 later. And I cite that as well in a review. And it NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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227 1 comes down to that same mass damping parameter all 2 over again. And so here is the magic formula. This 3 is the critical velocities. So it's velocity 4 normalized by the resonance frequency. So you go off 5 --
6 CO-CHAIR CORRADINI: And the critical 7 velocity is the highest velocity as it goes through 8 the gap?
9 DR. HAMBRIC: Yes, in this case, yeah.
10 That's what you're looking for. What is your gap 11 velocity?
12 CO-CHAIR CORRADINI: Okay.
13 DR. HAMBRIC: And the critical velocity, 14 different investigators kind of pick different 15 threshold points. It's just when things start going 16 bad. So it's not when you've reached horribly bad, 17 it's just the beginning of it. So that buys you a 18 little bit of margin. It's not much, but eventually 19 some. So I've got a little arrow pointing down here.
20 They marked this as the beginning of critical loss.
21 So again, you get that by your known 22 diameter and your structural resonance frequency. You 23 can back out a critical velocity.
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228 1 is in the backup, is they'll make all these 2 measurements and plot critical velocity versus that 3 parameter. And they'll just eyeball a curve through 4 it following this functional form.
5 And there's two empirical constants if you 6 back out. One is just a constant that is an 7 amplitude, that's the C. And over here, this Alpha is 8 an exponent. And that's it.
9 Subsequent to that, more people have tried 10 to come up with more involved terms, but this is 11 conservative, it's fine. And it's what we're using 12 here.
13 Now, there are two terms, one from 14 Connors, which is straight tubes, and another from 15 Chen, which is more prototypic to that, which is the 16 helical coil steam generator.
17 So NuScale went through and looked at 18 their tubes, assuming the conservative simply 19 supportive bounding conditions, or pinned bounding 20 conditions. I shouldn't call it pinned, because they 21 do a lot of sliding through their support.
22 CO-CHAIR CORRADINI: We're talking the 23 tubes, where there is one tab and two below?
24 DR. HAMBRIC: Yes.
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229 1 they were just held like this?
2 DR. HAMBRIC: Which is conservative.
3 CO-CHAIR CORRADINI: Okay.
4 DR. HAMBRIC: Gives you a lower resonance 5 frequency.
6 They also had to estimate the mass damping 7 of each mode. And to do that you need the modal mass 8 of each mode shape, the water mass that it displaces, 9 it's that ratio. And for damping, usually they put it 10 at one and half percent which needs to substantiated.
11 Over on the right is a schematic of the 12 results. This red box is the range of their critical 13 velocities. And this is for frequencies up to 30 Hz, 14 because above 30 Hz there's really no risk of FEI 15 occurring.
16 If you use Connors' constants, the line to 17 meet is a critical velocity of 2.15. They're 18 underneath that. If you use S.S. Chen's constants, 19 and in particular Chen's constants, which span 95 20 percent of his data, so it gives you some certainty 21 there, 95 percent certainty, I get a critical velocity 22 of one and a half, putting you in the danger zone.
23 CO-CHAIR CORRADINI: I've got to ask, 24 because I thought when this was presented by NuScale 25 I got the inference that, by using the straight tube NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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230 1 data, it was better. Am I misremembering?
2 DR. HAMBRIC: Yeah, and that's the blue on 3 the top. Straight tube data is 2.15 on the top.
4 That's Connors.
5 CO-CHAIR CORRADINI: And it's the angle of 6 attack that's causing it, or the fact that cross flow 7 versus parallel flow --
8 DR. HAMBRIC: We really don't all ---
9 CO-CHAIR CORRADINI: -- that causes the 10 2.15 versus 1.5?
11 DR. HAMBRIC: We really don't know. All 12 we know is that Chen measured it, and that's what he 13 got.
14 CO-CHAIR CORRADINI: Okay.
15 DR. HAMBRIC: There's been a lot of 16 speculation as to what's going on there.
17 CO-CHAIR CORRADINI: But once again, the 18 TF, whatever the name of the experiment is, we should 19 be able to verify --
20 DR. HAMBRIC: Yep.
21 CO-CHAIR CORRADINI: Okay.
22 DR. HAMBRIC: That's why it's so critical 23 to put this to rest. So we still view this a risk 24 area. And that is motivating the TF3 testing.
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231 1 the thermal expansion is not sufficient to lock all of 2 those tubes into all those supports, you might have 3 some tubes that are just kind of floating through 4 those tabs which means a much longer unsupported 5 region, which means a lower resonance frequency, which 6 means more chance of locking in.
7 We mentioned earlier there hasn't been any 8 mesh conversion studies presented to date. So that 9 means the resonance frequencies that they're 10 predicting could be biased high.
11 Also flow velocities, they did an analysis 12 assuming all active supports and came up with one set 13 of critical velocities. And then they went and did an 14 analysis assuming some inactive supports and said 15 we're going to use average velocity instead of gap 16 velocity for that, which we cannot understand why. So 17 that's an RAI to them. That doesn't make sense to us.
18 And the final thing, I mentioned this 19 earlier, is that assuming that the flow velocities are 20 uniform through the entire section does not bear up.
21 If you look at past measurements, this comes out of 22 the Chen paper, this is a cross section of 23 measurements that he made of the gap velocities at 24 various regions through his steam generator array.
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232 1 per second. That's up on the top. And then if you 2 squint, you can look at all the other velocities. But 3 they vary quite a bit, some lower, some higher, but 4 certainly not uniform.
5 And so we believe that, to be safe, some 6 sort of an upper bound ought to be considered for this 7 sort of assessment. But again, the proof will be in 8 the flow testing that they do.
9 So testing to date, NuScale showed you 10 earlier that the first sets of tests were for single 11 tube internal flows. And they did various conditions.
12 They had just water. They had water that was starting 13 to boil, and then they had water that was boiling and 14 converting to steam halfway up, so a lot of 15 conditions.
16 The ones that stood out to us are the ones 17 that showed this unexpected high spectral peak in the 18 pressure specter that they measured. We don't know 19 what this is. But it so far has not been included in 20 the NuScale assessments of the forced response of 21 their tubing. So it's the secondary flow, boiling, or 22 transitioning to boiling, inside the tubing.
23 CO-CHAIR CORRADINI: Can you say that 24 again. I don't think I understand.
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233 1 spectrum measured inside the tubing of the secondary 2 flow.
3 CO-CHAIR CORRADINI: Pressure spectrum 4 inside the tubing.
5 DR. HAMBRIC: Yeah, so it's the wall 6 pressures.
7 CO-CHAIR CORRADINI: Yeah.
8 DR. HAMBRIC: Those are the pressure 9 pulsations inside the secondary flow.
10 CO-CHAIR CORRADINI: Oh, pulsations.
11 DR. HAMBRIC: As measured in the TF1 12 testing.
13 CO-CHAIR CORRADINI: So what is the Y axis 14 again, one more time?
15 DR. HAMBRIC: Amplitude.
16 CO-CHAIR CORRADINI: Amplitude.
17 DR. HAMBRIC: That's the spectral peak 18 that you're looking at there. It's high pressures.
19 CO-CHAIR CORRADINI: Oh, this is the 20 frequency spectrum.
21 DR. HAMBRIC: Yep.
22 MEMBER BALLINGER: It's like a formation 23 and collapse of the hose itself?
24 DR. HAMBRIC: We don't know. Where I 25 found this before is in the oil and gas industry.
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234 1 They spent a lot of time looking at upwardly moving 2 boiling flow. And you go through these different 3 regimes of flow where it's all just sort of aggregate.
4 And then you get these bubbles forming and slugs. And 5 the slugs can kind of generate something like this.
6 And eventually, you wind up with two-phase 7 flow where you've got water in the walls and steam in 8 the middle. And then things are okay again. But in 9 that intermediate region, you can see stuff like this 10 in the literature, these big peaks.
11 CO-CHAIR CORRADINI: And has NuScale, I'm 12 sorry, I was trying to find your plot, NuScale has 13 analyzed this or has not?
14 DR. HAMBRIC: They are in the process of 15 analyzing it, and we're awaiting their forced response 16 results.
17 CO-CHAIR CORRADINI: Ah, okay. Fine.
18 DR. HAMBRIC: But there's an RAI out to 19 them, hey, what is this doing? Is this something to 20 worry about or not?
21 CO-CHAIR CORRADINI: I guess my only guess 22 is it's bubbly to annular flow transition.
23 DR. HAMBRIC: Yeah, could be.
24 CO-CHAIR CORRADINI: Yeah, okay.
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235 1 pretty high frequency for that. But I have no idea 2 what the state of the fluid is, what the actual flow 3 velocities are. It all depends on that, right.
4 CO-CHAIR CORRADINI: They could analyze it 5 with anything, even RELAP is a tube, it's one 6 dimensional for all intents and purposes.
7 MEMBER SUNSERI: And is the -- so on the 8 left side it looks like it's coming down real --- is 9 that just measurement, or is that something real?
10 DR. HAMBRIC: Oh, the zero Hz, yeah, 11 that's just, like, static behavior.
12 MEMBER SUNSERI: Okay.
13 DR. HAMBRIC: They also had something 14 called density wave oscillation in there. That'll 15 cause that as well. And that's the whole point of 16 their steam generator and the flow restrictors. That 17 gets rid of that.
18 CO-CHAIR CORRADINI: To get rid of that.
19 DR. HAMBRIC: Yeah. But in their testing 20 here, it showed up sometimes. There's nothing to 21 really worry about. So that's an outstanding item.
22 CO-CHAIR CORRADINI: And your red wasn't 23 shown in TF2. TF2 did not see what they saw in --
24 DR. HAMBRIC: No.
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236 1 supported? I don't remember now. It's just one 2 wiggly tube?
3 DR. HAMBRIC: Yeah. I don't think there 4 was a significant structural support. It was just, 5 sort of, they held it in place so it wouldn't go 6 anywhere.
7 Yeah, neither of these were meant to be 8 FIV tested.
9 CO-CHAIR CORRADINI: Understood.
10 DR. HAMBRIC: They just took the 11 opportunity to piggyback and get some data to help 12 them out.
13 CO-CHAIR CORRADINI: I see.
14 DR. HAMBRIC: Now TF2, as Olivia showed 15 you, was a non-prototypic early version of all of 16 this, again, not intended for FIV, limited 17 instrumentation and really short acquisition time. So 18 it was hard to see much in it.
19 But I've got that in green, because we did 20 spend a lot of time going through this with them. We 21 see some resonant peaks, but nothing that's all that 22 concerning. There's no evidence of, with increasing 23 flow speed, some non-linear increase that would 24 indicate lock-in.
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237 1 sufficient. And due to our concerns about the non-2 conservativisms potentially in their analyses, and the 3 low margins, that's really putting a lot of importance 4 on this TF3 test.
5 CO-CHAIR SKILLMAN: Steve, what is the 6 image, that lower image?
7 DR. HAMBRIC: Oh, that's a zoom of the 8 tubing and the supports in the TF2 test, right. So 9 those are the supports they had there, kind of these 10 long chunks of metal with grooves cut out of them 11 which is, again, not what they're using now.
12 CO-CHAIR SKILLMAN: So is that 13 prototypical for production? Or is that ---
14 DR. HAMBRIC: No, no. That's just a test 15 they did, again, primarily for thermal hydraulics.
16 CO-CHAIR SKILLMAN: Thank you. All right, 17 thanks.
18 DR. HAMBRIC: Yeah, what's more prototypic 19 is what I showed you earlier and what's in this 20 picture here.
21 So they're putting together five columns 22 which should be enough to deal with this. They're 23 heavily instrumented. We have no qualms whatsoever 24 about what they're doing with the instrumentation, 25 lots of sensors.
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238 1 There's two sets of tests, one, that are 2 going to help us in the near term and support our 3 final safety evaluation report. And that is the modal 4 dynamic test where they're going to go around and 5 excite these tubes in various ways and try to back out 6 resonance frequencies and damping factors.
7 The resonance frequencies they can use to 8 go back and fine tune their modeling procedures. Once 9 those procedures are fine-tuned, then they can apply 10 them to their actual design and show us, here's what 11 the real resonance frequencies are. And the hope is 12 they're much higher than what they have in their 13 current design application which gives us margin.
14 The tough one is going to be structural 15 damping. Because they can't really heat this thing up 16 to emulate thermal expansion effects. So they've come 17 up with a methodology to kind of press all these tubes 18 into the supports.
19 But this exercise they're busy going 20 through now is trying to estimate how much force do we 21 need to emulate what's really going to happen in 22 thermal expansion. So we're waiting for that from 23 them to convince us that what they're doing is 24 prototypic.
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239 1 verbally, but we've got nothing in writing to that 2 effect. We don't know when they're going to happen.
3 Given the deadlines for the final SE, it would be 4 highly unlikely that you're going to have flow data to 5 support it.
6 So the best we can do is work rigorously 7 with NuScale to ensure their flow test procedures are 8 robust, that they're going to go across a wide enough 9 range of flow speeds, be careful enough for their 10 measurements, commit to resolving issues if they show 11 up unexpectedly, things like that, try to make it as 12 solid as we can so that we have reasonable assurance 13 that nothing bad will happen in the actual plant when 14 they go to prototype testing.
15 And once again, we'll be out there in a 16 month looking at the first component of this which is 17 the modal testing.
18 CO-CHAIR SKILLMAN: Steve, you mentioned 19 several times the importance of fit of the tube into 20 the clip. Is the fabrication process intended to 21 spring load the tube so that when the tube is released 22 it actually finds its way into its, if you'll clamp, 23 into its support notch?
24 DR. HAMBRIC: It's supposed to snap into 25 those little triads of clips, right.
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240 1 CO-CHAIR SKILLMAN: Now, does that occur 2 because the bending process, if you will, compresses 3 the hoop so that when the hoop is released, under 4 manufacturing, the tube snaps into the clip?
5 DR. HAMBRIC: That I don't know. See, in 6 spite of NuScale's best efforts, I still don't have a 7 great grasp on this whole thing hangs together. And 8 that's a reason for going out and looking at it. I 9 think once we see it, and they explain it to us, 10 it'll make more sense. But, you know, we've got all 11 these diagrams of clips, and supports, and it sounds 12 great when they discuss it with us, but I'm still not 13 making the connection mentally with how it's being put 14 together.
15 CO-CHAIR CORRADINI: But as I heat up, I 16 would expect things to essentially lock in better.
17 DR. HAMBRIC: That is their argument, 18 right.
19 CO-CHAIR CORRADINI: Yeah.
20 CO-CHAIR SKILLMAN: Unless you get enough 21 of them and heat them all, you may get an outboard 22 compressive force that is greater than you anticipated 23 for the support members that are placed vertically 24 through that steam generator.
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241 1 force necessary to find the clip -- to find the tube 2 seated the way you want it seated, and having so many 3 tubes expanding, when you use the modular heating 4 system, that you actually injure a portion of the 5 structure, because you've got so many tubes.
6 DR. HAMBRIC: That would be a question for 7 NuScale in a different chapter, I'm afraid.
8 CO-CHAIR SKILLMAN: And it may be even 9 being proprietary, so I don't fully understand that.
10 DR. HAMBRIC: It probably is, yeah.
11 MEMBER BALLINGER: You need to remember 12 that the difference between San Onofre Unit 2 and Unit 13 3 was simply the fit.
14 DR. HAMBRIC: It's an important question.
15 And we're still waiting for them to get back to us in 16 a thermal expansion analysis which presumably should 17 include all of that, right.
18 CO-CHAIR CORRADINI: But the fact, well, 19 okay.
20 CO-CHAIR SKILLMAN: Maybe we'll discover 21 this when we go out there in July.
22 CO-CHAIR CORRADINI: Well, keep in mind 23 their testing is in Italy.
24 MEMBER BALLINGER: Well, maybe we should 25 go to Italy.
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242 1 (Laughter.)
2 CO-CHAIR CORRADINI: I don't think the 3 invited us there.
4 CO-CHAIR SKILLMAN: I just know that 5 there's some magic in steam generator fabrication. I 6 worked for B&W for a long time, and there's a lot 7 that's written and a lot that's craft. But there is 8 magic in these steam generators. I know that for a 9 fact.
10 DR. HAMBRIC: I cannot comprehend how 11 they're putting this thing together. I guess that is 12 beyond my mental ability to geometrically visualize 13 it. But I'm taking them at their word.
14 MR. LISZKAI: I apologize, this is Tamas.
15 Maybe I can clarify some of these questions that ---
16 DR. HAMBRIC: Please.
17 MR. LISZKAI: So the result of the thermal 18 expansion, and the thermal expansion of the tubes, and 19 components that are interacting in the steam 20 generator, currently SME codes, which is the federal 21 regulation, we will have to evaluate them. We are 22 evaluating the thermal point pressures associated with 23 thermal expansion and relative displacement of these 24 components.
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243 1 we're not exceeding any design stresses that will be 2 damaging to these tubes as a result of thermal 3 stresses. But that's really not on the review of the 4 CVAP program. And it belongs in another chapter in 5 our ACRS. I believe it's Chapter 5 ---
6 CO-CHAIR CORRADINI: Yeah, we discussed 7 this under five.
8 MR. LISZKAI: And that has been addressed 9 under that.
10 CO-CHAIR CORRADINI: So let me ask 11 NuScale, is the firm that is doing the testing and 12 manufacturing of your prototypic testing the same firm 13 that's going to build your steam generators?
14 MR. LISZKAI: No, they are not.
15 CO-CHAIR CORRADINI: Is there a transfer 16 of -- well, okay. That answers the question I wanted.
17 That's fine. Thank you.
18 DR. HAMBRIC: Okay. So those are actually 19 the more complicated structures. And we've got a 20 couple more to go, but they're a little simpler. The 21 next one is looking at the acoustic resonances and 22 particular in the decay heat removal system piping.
23 There are some side branches to be careful of there.
24 And here is what happens when you've got 25 a flow instability locking into an acoustic resonance.
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244 1 So it's the exact same phenomenon, just different 2 equations. Here the flow instability is flow over the 3 opening, and this is a side branch up here. And the 4 certain magical speed you wind up with an instability 5 exciting the opening there.
6 There are screw hole numbers that go with 7 this which I'll show you in a minute. And by itself, 8 there's nothing to worry about. If the frequency of 9 that instability aligns with an acoustic resonance 10 frequency in that fluid column, then you've got the 11 potential for feedback. The acoustic mode reinforces 12 the instability which reinforces the acoustic mode and 13 the infinite loop to some sort of a limit cycle which 14 you don't want to be at.
15 This is an example down at the bottom 16 here. This is what we call a spectrogram, so it's not 17 a frequency spectrum. There's frequency on this axis.
18 Here's amplitude over here. This collection of little 19 peaks here keeps growing, because on the axis on this 20 side I've got increasing flow velocity.
21 So we increase the flow, and you get this 22 huge non-linear increase in amplitude until you 23 eventually hit some sort of limit usually associated 24 with the damping in your system.
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245 1 to crack and fatigue fail. Believe it or not, the 2 acoustic pulsations were strong enough to break apart 3 a building. And that's how big they were. So we've 4 got to watch out for them.
5 I mentioned earlier we have primary 6 instabilities. Those are the ones that are generally 7 the strongest. They're in phase across this opening.
8 It's a half wavelength across the opening. So it's 9 like a big piston source driving the acoustic --
10 They're also at twice, excuse me, at half 11 the flow sped of the primary, so I slow the flow speed 12 down, and I get a full wavelength across that opening.
13 So it's like a dipole. I'm getting this pulsation on 14 the opening. It's still trying to drive the acoustic 15 mode, but it just doesn't do as good a job of it.
16 CO-CHAIR CORRADINI: You're most worried 17 about the steam side, not the water side?
18 DR. HAMBRIC: I'm worried about anything.
19 CO-CHAIR CORRADINI: No, but I meant ---
20 what I was trying to get at though was your analogy 21 with BWR concerns is essentially the steam side of the 22 DHRS.
23 DR. HAMBRIC: Right.
24 CO-CHAIR CORRADINI: Because the 25 frequencies there would be lower ---
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246 1 DR. HAMBRIC: Correct.
2 CO-CHAIR CORRADINI: -- relative to the 3 water side.
4 DR. HAMBRIC: Yeah. And they evaluated 5 everything.
6 CO-CHAIR CORRADINI: Okay.
7 DR. HAMBRIC: And there's plenty of margin 8 in general on the water side. There was only two that 9 we're still worried about that they'll be 10 instrumenting to look for.
11 So even though the secondary excitation is 12 weaker, it still has a potential to lock in. We've 13 seen excitations on dryers before at the secondary 14 flow instability, believe it or not. So it is 15 something to be concerned about. Anything higher than 16 that, like third order, we don't care about but first 17 and second order, we do.
18 So the range of screw hole numbers, that's 19 that frequency times diameter of the opening divided 20 by flow speed, is wider here. And generally, we have 21 to pick the most conservative one. And NuScale goes 22 through and estimates these for all their openings.
23 And after their big screening, they really 24 found only two locations that they didn't have great 25 margin for. One had about a 20 percent margin against NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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247 1 the primary number, so here their calculated Strouhal 2 number is 0.75 compared to the upper bound here where 3 they got about a 20 percent margin.
4 A better location, I'll show you both of 5 these in a second, has a lot higher margin, like a 6 factor of two. But for the secondary instability, cut 7 that in half, and now you're getting close again.
8 CO-CHAIR CORRADINI: Why would you worry 9 about the secondary instability?
10 DR. HAMBRIC: Again, we've seen it in 11 plants before. It'll excite modes and ---
12 CO-CHAIR CORRADINI: So a higher mode.
13 DR. HAMBRIC: Yeah. So they have been 14 there.
15 So they're instrumenting, in particular 16 this location, and these are the DHRS actuation 17 valves. They're down at the bottom there. And if you 18 take a look, you can see side branches and Ts, and all 19 of that other stuff. So flow over those regions are 20 what we're concerned about.
21 And they put together a nice list of 22 instrumentation. It really doesn't take much. If 23 this thing locks in, you'll hear anything, strain 24 gage, accelerometer, pressure transducer, it'll be 25 everywhere.
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248 1 The other concern is, if it does lock in, 2 you want to look at your valves. The other thing that 3 happened in Quad City is the valves failed just 4 because of the amplitude of the excitation. It's 5 obviously not something you want either.
6 But their approach makes sense. They're 7 going to do this testing during initial startup. So 8 when they turn the actual plant on, so we'll know 9 whether there's a problem or not. And if it's 10 significant, they've committed to resolving it.
11 CO-CHAIR CORRADINI: So how would we 12 resolve it? Change the inlet flow condition or the 13 location of the --- because the dead end portion of 14 the valve is pretty well fixed just by design. So it 15 has something to do with the inlet to the location?
16 DR. HAMBRIC: Change the diameter of the 17 opening, you can change the ---
18 CO-CHAIR CORRADINI: So in other words --
19 DR. HAMBRIC: -- size of the side branch, 20 the length of it? Yeah. Just change anything, 21 really.
22 CO-CHAIR CORRADINI: But some of these 23 things are kind of tough to ---
24 DR. HAMBRIC: Yeah, once they lock in, 25 they can be annoying.
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249 1 MEMBER REMPE: So when you talk about 2 proposed instrumentation for initial startup, is that 3 on the first module or ---
4 DR. HAMBRIC: Yes.
5 MEMBER REMPE: -- all 12 every time? Or 6 just ---
7 DR. HAMBRIC: No, no. They're prototype 8 modules.
9 MEMBER REMPE: First one, okay.
10 DR. HAMBRIC: And we'll talk more about 11 the other instrumentation in a second. But his is a 12 big part of what they're going to be measuring in 13 initial startup. And if nothing happens, great.
14 We've retired that risk for good.
15 All right, last one, leakage flow 16 instability, there's a couple of open items here. And 17 leakage flow instability, differed flow phenomenon, 18 but now either locking in with a structural resonance, 19 which is more typical, or in some cases an acoustic 20 one. But here we're mostly interested in structural 21 resonances.
22 But this happens in gap flow. So these 23 are images I pinched from Tom Mulcahy's report from 24 ANL about, boy, 30-something years ago. The reason he 25 wrote that report is this stuff happens in reactors.
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250 1 You don't want it to, but it happens.
2 A classic example is control rods and 3 guide tubes. So these are all examples of structures 4 inside tubes and the flow trying to squeeze by the 5 gap. And there's other examples of this in turbo 6 machinery with centrifugal pumps. You've got a 7 suction adaptor, we get back flow and that leakage 8 flow can increase and shake the pump around. It 9 happens quite a bit.
10 And the issue is this. If I've got the 11 flow, kind of sneak around here, actually that looks 12 like it's the middle figure here. All right, the 13 flow's coming in, and it's trying to squeeze around.
14 And what happens is you wind up with an equal and 15 opposite pressure loading on each side of the 16 structure that starts shaking it up and down.
17 So the structure starts vibrating, and if 18 things go wrong, the pressure on either side happens 19 to be in phase with the structural motion. So the 20 structure moves up, the pressure goes down. On the 21 other side, as the gap opens, the pressure goes up 22 which is the opposite of what you want.
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251 1 you go. It's banging against the wall, and squealing, 2 and doing all sort of bad things. This can occur even 3 with low flow rates. Is just depends on the geometry, 4 and the gap size, and everything else.
5 The one great qualitative guideline that 6 came out of Mulcahy's report is aim all of your 7 obstructions downstream. And the good news is, for 8 the steam generator and the flow restrictors, that's 9 exactly what NuScale did. It's oriented in the right 10 direction. So we're happy with that.
11 The other guidance from Mulcahy is every 12 situation is unique. Measure it to assess the risk.
13 So trying to come up with analytical approaches for 14 this particular design is just not really worth it.
15 So here is the structure we're talking 16 about. This is a big array of inlet flow restrictors.
17 So you get one of these going into every steam 18 generator tube. And the whole point of this is to try 19 to mitigate this density of density wave oscillation, 20 the super low frequency sloshing that can occur all 21 the way up and down your tubes if you don't do 22 something like this. This essentially damps all this 23 out and keeps it from happening. You lose some head 24 flow, but that's okay. It's factored into the design.
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252 1 analyze this, at least not anything that would take 2 you less than multiple years and a lot of scrutiny on 3 our part.
4 So what they did instead is came up with 5 a bunch of possible designs and stuck them in a bunch 6 of holes, and drove flow through those holes at way 7 higher than prototypic flow rates, measured 8 everything, discarded the ones that shook around a 9 bit, and kept the ones that had no sign of leakage 10 flow instability, and then picked their favorite one, 11 tweaked the design, and are moving forward with a 12 follow-up test to prove to us that this final design 13 is safe.
14 It's not going to be in initial startup 15 testing, it's going to be in its own little side test.
16 It's a validation test. But the benefit of that is, 17 as we mentioned before, it can really crank up the 18 flow to well above prototypic rates, find where 19 leakage flow actually happens, if it does at all, and 20 say here's how much margin we've got. We're safe, 21 nothing to worry about. So it's a design validation 22 test.
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253 1 from the initial tests, which they used to evaluate 2 their designs, and applied that to their proposed 3 validation testing.
4 Sadly, we will not get the results until 5 after design certification. I hope we get to see them 6 at some point, because it's a good final proof that 7 all will be well. But thus far, we're just going with 8 reasonable assurance that things should be safe.
9 CO-CHAIR SKILLMAN: Those who are on the 10 public line, or on the Corvallis line, would you put 11 your phone on mute. Excuse me.
12 DR. HAMBRIC: That's fine. Okay, so 13 that's our assessment of leak in the flow restrictor.
14 We have one more leakage flow instability topic to get 15 to, and that is of general reactor vessel internals.
16 The few locations we kind of looked at and 17 wondered about, some of them have been resolved, and 18 others we have ongoing assessments at NuScale which 19 we're auditing.
20 The one on the lower left, remember that 21 NuScale puts their upper and lower risers together 22 with sort of a press fit. And that's that tapered 23 region. You've got kind of a bellows up above all of 24 that which gives you some flexibility. But you've got 25 high pressure inside, you've got lower pressure in the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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254 1 steam generator region so we wondered, can leakage 2 flow kind of squeeze through that gap?
3 And they went through an assessment of 4 what they're calling the hold down force just due to 5 weight, and pressure, and just prove to us that the 6 pressure difference is way smaller than the hold down 7 force. And they just do not expect any flow sneaking 8 through that gap at all. So we're happy with that.
9 The other components are the ones we 10 talked about before, the ICIGTs, CRDSs, they're all 11 being kind of snaked through these holes and these 12 support structures. As the flow rises, it's going to 13 try to squeeze through those holes and potentially 14 shake those structures against the holes causing a 15 leakage flow instability.
16 They've gone through and found some nice 17 open literature references that assess that situation.
18 And they're performing calculations using the gap 19 widths, the flow speeds, and the pressure drops and 20 try to show us if they've got margin as leakage flow 21 for both of those cases.
22 There's also cases for the CRAGT over on 23 the right. There're some flow gaps there as well.
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255 1 hopefully before we submit our final SER.
2 Okay, plant measurements and inspections, 3 we mentioned a couple of these already. But just to 4 finalize it, these are all described or will be 5 described in the measurement inspection program. The 6 version we have now is incomplete, but the new version 7 should cover everything.
8 We're still awaiting the final TF3 flow 9 testing plan. And our path forward is to try to be as 10 rigorous as we can to give us reasonable assurance 11 that, when they're done, they will have found and 12 mitigated any issues if they show up at all.
13 They will provide follow-up 14 instrumentation and pre-test predictions. I think the 15 pre-test predictions are pretty simple. They don't 16 expect anything to happen. For initial startup 17 testing in the prototype, these are limited in scope 18 from what you may have seen in previous applications.
19 But again, that's fine. We're really not trying to 20 validate anything here other than nothing bad is going 21 to happen.
22 But the instrumentation should be 23 sufficient in breadth and location to capture and 24 localize any unexpectedly high vibrations, so they can 25 find it and mitigate it if that does occur.
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256 1 CO-CHAIR SKILLMAN: Steve, would you go 2 back a slide, please?
3 In this image, you show the control rod 4 drive lead screws or extensions. You show the in-core 5 instrument guide tubes and the control rod assembly 6 guide tubes. And your focus has been on the fluid 7 hydraulic interaction at what are basically the sleeve 8 supports. What attention is given to the horizontal 9 members?
10 DR. HAMBRIC: For the ICIGT?
11 CO-CHAIR SKILLMAN: Yeah. I mean, the 12 horizontal members, at least, appear to be fragile to 13 what is transverse flow.
14 DR. HAMBRIC: Yep?
15 CO-CHAIR SKILLMAN: What attention is 16 given to them?
17 DR. HAMBRIC: Yeah, we argued about that 18 quite a bit, actually, just because the flow through 19 there is so poorly understood. There's been really no 20 calculation of it. But we were able to resolve that 21 a couple of different ways.
22 Number one, those are structures they 23 actually have operating history for. The design is 24 based on a previous design which has been subjected to 25 much higher flow rates than what they're going to get NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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257 1 in their plant.
2 They also went through an analysis using 3 very conservative assumptions and showed that they 4 expected a very minimal amount of wear over the life 5 of the plant. And all of that is written up in the 6 SE. So you can find their evaluation and our 7 justification for why we think they're okay there.
8 CO-CHAIR SKILLMAN: Thank you.
9 DR. HAMBRIC: Okay. And I think you can 10 ---
11 MR. WONG: Okay, thanks, Steve. The 12 NuScale inspection plan is provided in the measurement 13 and, sorry, NuScale provided the measurement and 14 inspection plan in the measurement inspection 15 technical report.
16 The components evaluated in the analysis 17 program are inspected before and after the initial 18 start test for any evidence of loose parts or wear as 19 a result of vibration.
20 Components most susceptible to FIV are 21 examined in limiting and representative locations such 22 as load bearing elements, restraints, locking and 23 building components, and contact surfaces.
24 Visual inspections are performed using 25 VT-1 and VT-3 per ASME Boiler and Pressure Vessel Code NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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258 1 Section 11. VT-1 is for examining cracks and wear.
2 And VT-3 is for determining the general mechanical and 3 structural condition of components. The staff finds 4 the inspection method and areas consistent with other 5 design certification applications in Reg Guide 1.20.
6 These are just a summary of the issues for 7 each open item. And Steve has addressed those issues 8 in detail. And I'm not going to go over these again.
9 Next one, please. Again, these are the 10 open items.
11 Next one, please. So next up, Steve 12 already mentioned we're going to audit the SIET test 13 facility in Italy in the summer of 2019. We're going 14 to reveal the RAI responses, as well as the updated 15 CVAP report, and the measurement and inspection 16 report. And we're going to make a finding on the 17 component design against the FIV.
18 And also, we need to make a decision 19 regarding deferring the steam generator to a TF-3 test 20 to after design certification. And this is the end of 21 the presentation.
22 CO-CHAIR SKILLMAN: Gentlemen, thank you 23 very much for a very thorough presentation.
24 Members, do you have any questions for the 25 staff and the staff consultant?
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259 1 (No audible response.)
2 CO-CHAIR SKILLMAN: No? Thank you very 3 much.
4 MR. SNODDERLY: Dick, this is Mike 5 Snodderly. I had one thing I just wanted to clarify.
6 So for the full committee meeting, Marieliz, what it 7 your intent that we wouldn't cover 392 in June, we 8 would do 392 with all of Chapter 3 in July? Would you 9 remind me again, what did you want?
10 MS. VERA: We're doing full committee June 11 5th.
12 MR. SNODDERLY: Okay. All right.
13 MS. VERA: So it's with the same group 14 that --
15 (Simultaneous speaking.)
16 MS. VERA: -- presented this.
17 MR. SNODDERLY: Okay. I just wanted to 18 confirm the availability of, okay. So then, okay, 19 we'll do this June. Great.
20 CO-CHAIR SKILLMAN: Thank you. Let's 21 first --- would you make sure the phone line is open, 22 if it is, please?
23 PARTICIPANT: Yes.
24 CO-CHAIR SKILLMAN: Is there any 25 individual in the room that would like to make a NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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260 1 comment, please?
2 (No audible response.)
3 CO-CHAIR SKILLMAN: Seeing none, we're 4 checking on the phone line.
5 MR. SNODDERLY: Is there anybody on the 6 bridge line that would like to make a comment from 7 the public?
8 CO-CHAIR SKILLMAN: Hearing none, thank 9 you. I would like to thank the staff for their work 10 and for the presentation. I want to thank NuScale for 11 your travel, for your presentation, for your follow-up 12 regarding compressibility of the fluid. Members, any 13 final comments before we adjourn?
14 Dr. Schultz, thank you for coming down.
15 To the members, thank you.
16 CO-CHAIR CORRADINI: So you're asking, I 17 do have something.
18 CO-CHAIR SKILLMAN: You do? Oh.
19 CO-CHAIR CORRADINI: Yes, I do. I'm 20 sorry.
21 CO-CHAIR SKILLMAN: Please.
22 CO-CHAIR CORRADINI: My recommendation for 23 the full committee, if you're going to have this as 24 part of the June meeting, is that there is -- the 25 particular size that you guys went through, I'm going NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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261 1 to talk --- I think in NuScale's case, they did a nice 2 job of compressing it into a frame. So I'm not going 3 to make a suggestion.
4 With all due respect, yours was a tad 5 lengthier than I expected. My suggestion is there 6 were three or four slides, I think they were slides 20 7 through 25, where you summarized the physical 8 phenomena issues and the structures where you were 9 concerned about the physical phenomena issues. I 10 think that would be, for the members that aren't here, 11 we lost a few, about half of us will want to hear 12 that, in particular, Dr. Riccardella.
13 So my suggestion is, at the very least, 14 hone in on those half dozen slides where you've 15 actually said what's the phenomena and where are the 16 structures that you're worried about. And then I 17 leave it to you to, kind of, how you want to weave in 18 the open items. I think, Professor, I think it 19 started with 20, reactor internals comprehensive 20 vibration.
21 DR. HAMBRIC: Right here?
22 CO-CHAIR CORRADINI: Yeah, 23 DR. HAMBRIC: Yeah, so this bottom line up 24 front was what we're --
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262 1 talked about the physical phenomena --
2 DR. HAMBRIC: Yeah.
3 CO-CHAIR CORRADINI: -- where they occur, 4 and what your worries were.
5 DR. HAMBRIC: Yeah.
6 CO-CHAIR CORRADINI: That would be my 7 recommendation to help the rest of the members.
8 DR. SCHULTZ: But then some summary 9 associated with the tie-in to the testing program --
10 CO-CHAIR CORRADINI: Correct.
11 DR. SCHULTZ: -- and how there is a path 12 for resolution. The timing may be different than what 13 one might like, but there is a path, a program that's 14 planned.
15 CO-CHAIR CORRADINI: Correct, thank you 16 very much. That sounds perfect. But that would be my 17 recommendation. Because we have, for all chapters, 18 392, 14, 19, and 21, we have only a half a day. So we 19 have to be somewhat Spartan as to what we can present 20 to the rest of the committee.
21 DR. HAMBRIC: Sure.
22 CO-CHAIR CORRADINI: That would be my 23 recommendation.
24 CO-CHAIR SKILLMAN: Yep.
25 CO-CHAIR CORRADINI: but I thought you NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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263 1 guys did a great job, both NuScale and the staff, and 2 consultants.
3 CO-CHAIR SKILLMAN: Yep, me too.
4 Colleagues, anything else?
5 (No audible response.)
6 CO-CHAIR SKILLMAN: Safe travels, 7 everybody. We're adjourned.
8 (Whereupon, the above-entitled matter went 9 off the record at 2:51 p.m.)
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LO-0519-65507 May 08, 2019 Docket No.52-048 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk One White Flint North 11555 Rockville Pike Rockville, MD 20852-2738
SUBJECT:
NuScale Power, LLC Submittal of Presentation Materials Entitled ACRS Subcommittee Presentation: NuScale FSAR Chapter 14, Initial Test Program and Inspections, Tests, Analyses, and Acceptance Criteria, PM-0519-65457, Revision 0 The purpose of this submittal is to provide presentation materials for use during the upcoming Advisory Committee on Reactor Safeguards (ACRS) NuScale Subcommittee meeting on May 16, 2019. The materials support NuScales presentation of Chapter 14, Initial Test Program and Inspections, Tests, Analyses, and Acceptance Criteria, of the NuScale Design Certification Application. is the nonproprietary presentation entitled ACRS Subcommittee Presentation: NuScale FSAR Chapter 14, Initial Test Program and Inspections, Tests, Analyses, and Acceptance Criteria, PM-0519-65457, Revision 0.
This letter makes no regulatory commitments and no revisions to any existing regulatory commitments.
If you have any questions, please contact Carrie Fosaaen at 541-452-7126 or at cfosaaen@nuscalepower.com.
Sincerely, Zackary W. Rad Director, Regulatory Affairs NuScale Power, LLC Distribution: Robert Taylor, NRC, OWFN-7H4 Michael Snodderly, NRC, TWFN-2E26 Gregory Cranston, NRC, OWFN-8H12 Samuel Lee, NRC, OWFN-8H12 Cayetano Santos, NRC, OWFN-8H12 : ACRS Subcommittee Presentation: NuScale FSAR Chapter 14, Initial Test Program and Inspections, Tests, Analyses, and Acceptance Criteria, PM-0519-65457, Revision 0.
NuScale Power, LLC 1100 NE Circle Blvd., Suite 200 Corvallis, Oregon 97330 Office 541.360-0500 Fax 541.207.3928 www.nuscalepower.com
LO-0519-65507 :
ACRS Subcommittee Presentation: NuScale FSAR Chapter 14, Initial Test Program and Inspections, Tests, Analyses, and Acceptance Criteria, PM-0519-65457, Revision 0.
NuScale Power, LLC 1100 NE Circle Blvd., Suite 200 Corvallis, Oregon 97330 Office 541.360-0500 Fax 541.207.3928 www.nuscalepower.com
NuScale Nonproprietary ACRS Subcommittee Presentation:
NuScale FSAR Chapter 14 Initial Test Program and Inspections, Tests, Analyses, and Acceptance Criteria May 16, 2019 1
PM-0519-65457 Revision: 0 Copyright 2019 by NuScale Power, LLC.
Template #: 0000-21727-F01 R5
Presenters Chris Maxwell Senior Reactor Operator 4 Edan Engstrom Senior Reactor Operator 4 Zack Rad Director, Regulatory Affairs Carrie Fosaaen Supervisor, Licensing 2
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14 Verification Programs 3
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14.2 Initial Plant Test Program 4
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14.2 Initial Plant Test Program
- Preoperational testing
- Startup testing
- Initial fuel loading and pre-critical testing
- Initial criticality testing
- Low-power testing
- Power-ascension testing
- First-of-a-kind testing 5
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14.2 Initial Plant Test Program
- Preoperational Testing
- From Regulatory Guide 1.68:
Preoperational testing, as used in this regulatory guide, consists of those tests conducted following completion of construction inspections and tests, but before fuel loading, to demonstrate, to the extent practical, the capability of SSCs to meet the performance requirements to satisfy the design criteria.
- RG 1.68, Appendix A, A-1 Preoperational Testing
- Design Reliability Assurance Program (D-RAP)
- Described in Chapter 17.4 of the NuScale FSAR
- Functions were developed to describe each system
>> Functions described in a support system to supported system format
>> Functions were classified by safety and risk significance 6
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14.2 Initial Plant Test Program Safety-Related Safety-Related Nonsafety-Related Nonsafety-Related Risk Significant Not Risk Significant Risk Significant Not Risk Significant Can the function be tested?
ITAAC Testing Evaluate for Required ITAAC Testing Component-Level Test System Level Test 7
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14.2 Initial Plant Test Program
- Testable D-RAP functions 8
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14.2 Initial Plant Test Program
- Testable D-RAP functions 9
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14.2 Initial Plant Test Program
- Table 14.2-52: Reactor Building Cranes Test #52 10 PM-0519-65457 Revision: 0 Copyright 2019 by NuScale Power, LLC.
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14.2 Initial Plant Test Program
- Reactor Building Crane Test Abstract - Functions
- Each testable function is listed on the test abstract, and the tests used to verify the functions are specifically identified.
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14.2 Initial Plant Test Program
- Reactor Building Crane Test Abstract - Prerequisites
- The prerequisites required to be completed prior to commencing preoperational testing are listed.
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14.2 Initial Plant Test Program
- Test Abstract - Component Level Tests
- Used to demonstrate and verify system functionality at the component level.
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14.2 Initial Plant Test Program
- Test Abstract - System Level Tests
- Used to demonstrate and verify integrated functionality at the system level.
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14.2 Initial Plant Test Program 15 PM-0519-65457 Revision: 0 Copyright 2019 by NuScale Power, LLC.
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14.2 Initial Plant Test Program
- Test Abstract - System Level Tests
- One element of the system function is demonstrated and verified by Test #52-1.
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14.2 Initial Plant Test Program
- The remaining elements of the system function are demonstrated and verified by Test #52-2.
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14.2 Initial Plant Test Program
- Startup Testing
- From Regulatory Guide 1.68:
Initial startup testing, as used in this regulatory guide, consists of equipment performance tests completed during and after fuel loading.
These performance tests are normally completed during fuel loading, pre-critical, initial criticality, low power and power ascension phases to confirm the design bases and demonstrate, to the extent practical, that the plant will operate in accordance with design and that it is capable of responding to anticipated transients and postulated accidents as specified in the FSAR.
- RG 1.68, Appendix A
- A-2 Initial Fuel Loading and Pre-Critical Tests
- A-3 Initial Criticality
- A-4 Low-Power Testing
- A-5 Power Ascension Testing 18 PM-0519-65457 Revision: 0 Copyright 2019 by NuScale Power, LLC.
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14.2 Initial Plant Test Program
- Test Abstract - Startup Testing
- Different layout than the preoperational testing test abstracts, but include the same elements:
- Test Objectives
- Prerequisites
- Test Method
- Acceptance Criteria 19 PM-0519-65457 Revision: 0 Copyright 2019 by NuScale Power, LLC.
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14.2 Initial Plant Test Program 20 PM-0519-65457 Revision: 0 Copyright 2019 by NuScale Power, LLC.
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14.2 Initial Plant Test Program
- Test Abstract - First-of-a-Kind (FOAK) Tests
- Regulatory Guide 1.68, Appendix A, A-6
- FOAK tests are new, unique, or special tests used to verify design features that are being reviewed for the first time by the NRC.
- Listed in Table 14.2-110, ITP Testing of New Design Features, and includes features such as:
- ECCS valve design
- Containment evacuation system
- Island mode operation 21 PM-0519-65457 Revision: 0 Copyright 2019 by NuScale Power, LLC.
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14.3 Certified Design Material and ITAAC 22 PM-0519-65457 Revision: 0 Copyright 2019 by NuScale Power, LLC.
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14.3 to ITAAC Flowpath Tier 2 Detailed Design Information Tier 2 Section 14.3 First Principles Tier 1 Design Description Information ITAAC Inspections, System Design Design Acceptance Tests, and Descriptions Commitments Commitments Criteria Analyses 23 PM-0519-65457 Revision: 0 Copyright 2019 by NuScale Power, LLC.
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14.3 Certified Design Material and ITAAC
- Provides guidance regarding the certified design material (CDM) in Tier 1, including Inspections, Tests, Analyses, and Acceptance Criteria (ITAAC) required under 10 CFR 52.47(b)(1).
- ITAAC - Those inspections, tests, analyses, and acceptance criteria identified in the combined license that if met by the licensee are necessary and sufficient to provide reasonable assurance that the facility has been constructed and will be operated in conformity with the license, the provisions of the Atomic Energy Act, as amended, and the Commissions rules and regulations.
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14.3 Certified Design Material and ITAAC
- Detailed design information is contained in Tier 2.
- Tier 1 Design Descriptions include only the most safety-significant aspects of each of the systems described in the Tier 2 information.
- Top-level design features
- Top-level performance characteristics
- A first principles approach was used to select Tier 2 information for inclusion in the Tier 1 design descriptions.
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14.3 Design Description First Principles
- Tier 1 Design Descriptions are limited to the top-level design features of the following:
- Safety-related SSC
- Nonsafety-related SSC that protect safety-related components
- Security system physical SSC
- Risk-significant, nonsafety-related SSC determined by results of probabilistic risk assessment 26 PM-0519-65457 Revision: 0 Copyright 2019 by NuScale Power, LLC.
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14.3 Design Description First Principles
- The top-level design features contained in Tier 1 design descriptions are:
- Reactor coolant pressure
- Safety-related component boundary performance
- Containment pressure
- SSC providing protection of boundary safety-related components
- Seismic Category I Reactor
- Safety-related protection systems and Control Buildings
- Components providing radiation
- Radwaste Category RW-IIa protection for personnel and Radioactive Waste Building safety-related equipment
- New and spent fuel storage
- Safety-related equipment
- Security system physical qualification components 27 PM-0519-65457 Revision: 0 Copyright 2019 by NuScale Power, LLC.
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Tier 1 Design Descriptions
- With the information selected to be included in the Tier 1 Design Description, the information is further divided into categories which include:
- System Descriptions: a concise description of system functions, safety classification, and general location.
- Design Commitments: a list of design features, such as seismic and ASME Code classifications, Class 1E equipment designation, and environmental qualification requirements.
- Only the design features described in the Design Commitments are verified by ITAAC.
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Tier 1 ITAAC
- For each system with Design Commitments, a table of ITAAC entries is provided.
- ITAAC consists of three columns:
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Standardized ITAAC
- In a letter dated April 8, 2016, the NRC sent NuScale a set of standardized DCA ITAAC for use in a design certification application.
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Portland Office Richland Office 6650 SW Redwood Lane, 1933 Jadwin Ave., Suite 130 Suite 210 Richland, WA 99354 Portland, OR 97224 541.360.0500 971.371.1592 Arlington Office Corvallis Office 2300 Clarendon Blvd., Suite 1110 1100 NE Circle Blvd., Suite 200 Arlington, VA 22201 Corvallis, OR 97330 541.360.0500 London Office 1st Floor Portland House Rockville Office Bressenden Place 11333 Woodglen Ave., Suite 205 London SW1E 5BH Rockville, MD 20852 United Kingdom 301.770.0472 +44 (0) 2079 321700 Charlotte Office 2815 Coliseum Centre Drive, Suite 230 Charlotte, NC 28217 980.349.4804 http://www.nuscalepower.com Twitter: @NuScale_Power 31 PM-0519-65457 Revision: 0 Copyright 2019 by NuScale Power, LLC.
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Presentation to the ACRS NuScale Design Certification Application Review Safety Evaluation with Open Items: Chapter 14 INITIAL TEST PROGRAM AND ITAAC May 16, 2019
Staff Review Team
- Technical Reviewers Aaron Armstrong Chang Li Joe Ashcraft Amanda Marshall Clinton Ashley Ryan Nolan John Budzynski Jonathan Ortega-Luciano Alexander Chereskin Paul Prescott Nan Chien Sheila Ray Jorge Cintron-Rivera Robert Roche-Rivera Timothy Drzewiecki Fanta Sacko Greg Galletti Tom Scarbrough Joe Giacinto Maurin Scheetz Anne-Marie Grady Alex Siwy Zach Gran Angelo Stubbs Nick Hansing Edward Stutzcage Raul Hernandez Dinesh Taneja BP Jain Boyce Travis Nadim Khan Alexander Tsirigotis Taylor Lamb Bob Vettori Ronald LaVera Hanry Wagage Pete Lee Yuken Wong
Outline of Presentation
Technical Topics of Interest:
Section 14.2 Tier 2, Chapter 14, Subsections:
14.2.1 - Summary of Initial Test Program and Objectives 14.2.2 - Organization and Staffing 14.2.3 - Test Procedures 14.2.4 - Conduct of the Test Program 14.2.5 - Review, Evaluation, and Approval of Test Results 14.2.6 - Test Records 14.2.7 - Test Programs Conformance with Regulatory Guides 14.2.8 - Utilization of Reactor Operating and Testing Experience in Test Program Development 14.2.9 - Trial Use of Plant Operating Procedures, Emergency Procedures, and Surveillance Procedures 14.2.10 - Initial Fuel Loading, and Initial Criticality 14.2.11 - Test Program Schedule and Sequence 14.2.12 - Individual Test Descriptions 4
Technical Topics of Interest:
Section 14.2 Review Objectives
- Reviewed Tier 2, Section 14.2 for completeness and suitability for development of an ITP by a COL applicant against the guidance in the DSRS Section 14.2 and RG 1.68 by using a risk-informed approach.
Staff Review
- SECY-11-0024, Use of Risk Insights to Enhance the Safety Focus of Small Modular Reactor Reviews, dated February 18, 2011, requested Commission approval of the staffs recommendation to develop a risk-informed and integrated framework for the review of the iPWR designs. On May 11, 2011, the Commission approved staffs approach.
Revised ITP review focuses on providing reasonable assurance that risk significant SSC functions are tested and a test abstract adequately addresses design functionality.
- NuScale DSRS Section 14.2, Initial Plant Test Program - Design Certification and New License Applicants, dated July 11, 2016, provides guidance to the NRC staff for review of the proposed NuScale ITP in accordance with the approved approach.
5
Technical Topics of Interest:
Section 14.2 Staff Review Continued
- The DSRS noted that there is no requirement for a DC applicant to provide an ITP submittal under 10 CFR Part 52, Subpart B, Standard Design Certifications, but the staff has reviewed the test abstracts provided by previous DC applicants for completeness and suitability for development of an ITP by a COL applicant against the guidance in the Standard Review Plan Section 14.2 and RG 1.68.
- The staff utilized Table 17.4-1, D-RAP SSC Functions, Categorizations, and Categorization Basis, in the DCA to determine the set of test abstracts to review using the risk-informed approach and for efficiency.
NuScale staff requested a larger scope of review.
- NRC approved only those test abstracts listed in Table 14.2-1 of the SER
- Test abstracts not approved are listed in Table 14.2-2 of the SER Must be addressed by a COL applicant If design certification is approved, staff would recommend that the certification rule include clarifying language that these test abstracts are outside the scope of the certified design.
6
Technical Topics of Interest:
Section 14.2 Staff Conclusion
- Open Item 03.09.06-1: The staff will keep open test abstract 14.2-47, Emergency Core Cooling System Test #47 while the Chapter 3 open item is being resolved.
- Confirmatory Item 14.2-1: NuScales response to the staffs review of the test abstracts in Table 14.2-1 of the SER included proposed markups to DCA Part 2, Tier 2. Therefore, the staff is tracking the incorporation of the proposed changes in these letters into a future revision of the DCA
- The staff concludes, using the information presented in the DCA, and pending the confirmation of the confirmatory item and closure of the open item, that the applicant has demonstrated compliance with NRC regulations and guidance.
7
Technical Topics of Interest:
Section 14.3 (ITAAC) Overview
- Review of Tier 1 information including definitions, significant site parameters, interface requirements, and ITAAC tables
- Regulatory Bases 10 CFR 52.47(b)(1)
SRP Section 14.3 Standardized ITAAC in letters dated April 8, 2016 and June 21, 2016 SECY-19-0034, Improving Design Certification Content, describes revised general principles for the review of Tier 1
- Tier 1 should typically be at a qualitative and functional level of detail.
- Tier 1 should not include detail that could necessitate NRC approval for departures from the certified design that have minimal safety significance.
- Numeric values in Tier 1 should be minimized.
8
Technical Topics of Interest:
Section 14.3 (ITAAC) Overview
- 14.3 subsections with no open items 14.3.4 - Reactor Systems 14.3.5 - I&C 14.3.7 - Plant Systems 14.3.10 - Emergency Planning 14.3.12 - Physical Security 14.3.13 - External Flooding 9
Technical Topics of Interest:
Section 14.3.1 - Selection Criteria for Tier 1
- Staff excluded from its review NuScales First Principles approach for determining the scope of Tier 1 and ITAAC NuScales approach similar to NEI 15-02, Industry Guideline for the Development of Tier 1 and ITAAC under 10 CFR Part 52 and NEI white paper, First Principles for Use in Developing Design Certification Tier 1 ITAAC, which NRC has not endorsed DCA Part 2, Tier 2, Section 14.3.2 would not be incorporated by reference into a design certification rule
- Sections 14.3.2 through 14.3.13 document the staffs review of the ITAAC or reference other SER Chapters containing ITAAC evaluation 10
Technical Topics of Interest:
Section 14.3.1 - Selection Criteria for Tier 1
- Open Item 17.4-1 In SECY-18-0093 staff recommended the use of ITAAC to verify effectiveness of D-RAP be discontinued and is awaiting Commission decision No ITAAC provided for the D-RAP
- Open Item 14.3.1-1 Staff conducted review of Tier 1 for form and clarity and requested that NuScale make changes (RAI 9681) 11
Technical Topics of Interest:
Section 14.3.1 - Selection Criteria for Tier 1
- Tier 1 Interface requirement evaluated in SER Section 3.7 Failure of any structures not within the scope of the certified design will not cause any of the Seismic Category I structures within the scope of the certified design to fail 10 CFR 52.47(a)(26) requires that interface requirements be verifiable through ITAAC Two ITAAC verify that as-built non Seismic Category I SSC will not impair the ability of Seismic Category I SSCs Staff cannot make a finding that the 10 CFR 52.47(a)(26) requirement has been met because of Open Item 14.3.2-2 12
Technical Topics of Interest:
Section 14.3.2 - Structural and Systems Engineering
- Open Item 14.3.2-1 The ITAAC for the structural integrity of the reactor, radioactive waste, and control buildings are incomplete.
The application did not (i) address the deviations between assumed design loads and as-constructed loads, nor did it address the changes in demand resulting from these deviations, (ii) state that the design report will document the demand analysis using the same methodology used for the certification
- Open Item 14.3.2-2 The ITAAC for the seismic interaction of seismic category I SSCs with non-seismic category SSCs of the control building are not consistent with the ITAAC for RXB and are not in conformance with the Standardized DCA ITAAC acceptance criteria 13
Technical Topics of Interest:
Section 14.3.3 - Piping Systems and Components
- Open Item 14.3.3-1: NPM Valve Installation Verification ITAAC ITAAC need to satisfy 10 CFR 52.47(b)(1) to provide reasonable assurance the NuScale Power Module (NPM) safety-related valves are constructed and will operate in conformity with the design certification.
NPM Valve Installation Verification ITAAC will require a walkdown inspection of the emergency core cooling system (ECCS) valves, containment isolation valves (CIVs), and decay heat removal system (DHRS) actuation valves to ensure the valves will not be prevented from performing their safety functions.
14
Technical Topics of Interest:
Section 14.3.3 - Piping Systems and Components Walkdown inspection will verify installation of the ECCS valves, CIVs, and DHRS actuation valves and their hydraulic lines consistent with the specifications for geometric configuration, orientation, accessibility, and line routing such that each valve can perform its safety functions.
Together with the current ITAAC, NPM Valve Installation Verification ITAAC will provide reasonable assurance that the ECCS valves, CIVs, and DHRS actuation valves will operate properly to allow core cooling and provide containment isolation under design-basis conditions.
NRC staff held a public telecon with NuScale on May 8, 2019, to discuss the path forward for resolution of this open item.
15
Technical Topics of Interest:
Section 14.3.6 - Electrical Systems
- The staff reviewed the NuScale design to determine whether the applicant established appropriate Tier 1 design commitments for the electrical systems and that they are verified by ITAAC.
Equipment Qualification for Seismic and Harsh Environment Containment Electrical Penetrations Lighting
- Open Item 8.3-1 The completion of the staffs review is awaiting for the completion of a Chapter 8 open item related to the GDC 17 and 18 exemptions.
- Open Item 14.3.6-1 The staff identified editorial errors in Tier 2, Table 14.3-1.
16
Technical Topics of Interest:
Section 14.3.8 - Radiation Protection
- Open Items 14.3.8-1 and 14.3.8-2 Borated polyethylene shielding in Tier 1, Table 3.11-1.
The applicant revised the bioshield design several times.
Borated polyethylene was originally provided on the top of the bioshield to shield neutrons. This shielding was also identified in Tier 1, Table 3.11-1. The applicant removed borated polyethylene from the top of the bioshield and from Tier 1, Table 3.11-1. Later, the applicant incorporated borated polyethylene into the front of the bioshield faceplate but did not add the faceplate borated polyethylene into Tier 1, Table 3.11-1.
17
Technical Topics of Interest:
Section 14.3.9 - Human Factors Engineering
- Focus: The as-built Human System Interfaces (HSI) in the Main Control Room (MCR) will be consistent with the HSI resulting from the applicants Human Factors Engineering design process. ITAAC exist for the verification of system level displays, alarms and controls in the as-built MCR and Remote Shutdown Station (RSS).
- Open Item 18-22 The Design Commitment for the MCR does not include changes to the HSI design that could occur after Integrated System Validation.
- Open Item 14.3.9-1 The applicant did not include ITAAC for RSS displays, controls and alarms because there is no manual control of safety-related equipment from the RSS. Acceptability of this approach depends on the staffs approval of a partial exemption from the portion of GDC 19 requiring equipment outside the control room with a potential capability for subsequent cold shutdown of the reactor when the control room is evacuated.
18
Technical Topics of Interest:
Section 14.3.11 - Containment Systems
- Open Item 14.3.11-1 NuScale requested an exemption from the integrated leak-rate test requirement for the containment vessel (10 CFR 50 Appendix J, Type A) so no ITAAC was provided for Type A testing SER Section 6.2.6 evaluation recommends granting this exemption so Open Item 14.3.11-1 is closed
- SER Chapter 6 will be presented during a future meeting 19
Section 14.3 Conclusions
- For those sections with open items, staff is unable to finalize its conclusions
- For those sections without open items, pending the resolution of any confirmatory items, the staff finds that the NuScale DCA contains the proposed ITAAC that are necessary and sufficient to provide reasonable assurance that, if the inspections, tests, and analyses are performed and the acceptance criteria are met, a facility that incorporates the certified design has been constructed and will be operated in conformity with the applicable portions of the design certification, the AEA, and the NRCs rules and regulations.
20
Backup Slides (14.2)
Test Abstracts Reviewed Abstract Test Title Table 14.2-4 Pool Surge Control System Test #4 Table 14.2-5 Ultimate Heat Sink #5 Table 14.2-9 Auxiliary Boiler System Test #9 Table 14.2-18 Control Room Habitability System Test #18 Table 14.2-19 Normal Control Room HVAC [Heating, Ventilation, and Air Conditioning] System Test #19 Table 14.2-20 Reactor Building HVAC System Test #20 Table 14.2-24 Balance-of-Plant Drains Test #24 Table 14.2-25 Fire Protection Systems Test #25 Table 14.2-33 Turbine Generator Test #33 Table 14.2-35 Liquid Radioactive Waste System Test #35 Table 14.2-36 Gaseous Radioactive Waste System Test #36 Table 14.2-38 Chemical and Volume Control System Test #38 Table 14.2-41 Containment Evacuation System Test #41 Table 14.2-42 Containment Flooding and Drain System Test #42 Table 14.2-43 Containment System Test #43 Table 14.2-44 Control Rod Drive System Flow-Induced Vibration Test #44 Table 14.2-45 Reactor Vessel Internals Flow-Induced Vibration Test #45 Table 14.2-46 Reactor Coolant System Test #46 Table 14.2-47 Emergency Core Cooling System Test #47 Table 14.2-48 Decay Heat Removal System Test #48 Table 14.2-51 Fuel Handling Equipment System Test #51 Table 14.2-52 Reactor Building Cranes Test #52 Table 14.2-60 Plant Lighting System Test #60 Table 14.2-63 Module Protection System Test #63 Table 14.2-66 Safety Display and Indication Test #66 Table 14.2-68 Communication System Test #68 Table 14.2-70 Hot Functional Testing Test #70 Table 14.2-72 Steam Generator Flow-Induced Vibration Test #72 Table 14.2-73 Security Access Control Test #73 Table 14.2-74 Security Detection and Alarm Test #74 Table 14.2-76 Initial Fuel Load Test (Test #76) 21
Backup Slides (14.2)
Test Abstracts Reviewed Abstract Test Title Table 14.2-77 Reactor Coolant System Flow Measurement Test (Test #77)
Table 14.2-78 NuScale Power Module Temperature Test (Test #78)
Table 14.2-79 Primary and Secondary System Chemistry Test (Test #79)
Table 14.2-80 Control Rod Drive System - Manual Operation, Rod Speed, and Rod Position Indication Test (Test #80)
Table 14.2-81 Control Rod Assembly Drop Time Test (Test #81)
Table 14.2-81a Control Rod Assembly Ambient Temperature Full-Height Drop Time Test #81A Table 14.2-82 Pressurizer Spray Bypass Flow Test (Test #82)
Table 14.2-83 Initial Criticality Test (Test #83)
Table 14.2-84 Post-Critical Reactivity Computer Checkout Test (Test #84)
Table 14.2-86 Determination of Zero-Power Physics Testing Range Test (Test #86)
Table 14.2-87 All Rods Out Boron Endpoint Determination Test (Test #87)
Table 14.2-88 Isothermal Temperature Coefficient Measurement Test (Test #88)
Table 14.2-89 Bank Worth Measurement Test (Test #89)
Table 14.2-91 Core Power Distribution Map Test (Test #91)
Table 14.2-92 Neutron Monitoring System Power Range Flux Calibration Test (Test #92)
Table 14.2-93 Reactor Coolant System Temperature Instrument Calibration Test (Test #93)
Table 14.2-94 Reactor Coolant System Flow Calibration Test (Test #94)
Table 14.2-95 Radiation Shield Survey Test (Test #95)
Table 14.2-96 Reactor Building Ventilation System Capability (Test #96)
Table 14.2-97 Thermal Expansion Test (Test #97)
Table 14.2-98 Control Rod Assembly Misalignment (Test #98)
Table 14.2-99 Steam Generator Level Control Test (Test #99)
Table 14.2-100 Ramp Change in Load Demand (Test #100)
Table 14.2-101 Step Change in Load Demand Test (Test #101)
Table 14.2-102 Loss of Feedwater Heater Test (Test #102)
Table 14.2-103 100 Percent Load Rejection Test (Test #103)
Table 14.2-104 Reactor Trip from 100 Percent Power Test (Test #104)
Table 14.2-105 Island Mode Test for NuScale Power Module #1 (Test #105)
Table 14.2-106 Island Mode Test for Multiple NuScale Power Modules (Test #106)
Table 14.2-108 NuScale Power Module Vibration Test (Test #108) 22
Backup Slides (14.2)
Test Abstracts Not Reviewed Abstract Test Title Table 14.2-1 Spent Fuel Pool Cooling System Test #1 Table 14.2-2 Pool Cleanup System Test #2 Table 14.2-3 Reactor Pool Cooling System Test #3 Table 14.2-6 Pool Leak Detection System Test #6 Table 14.2-7 Reactor Component Cooling Water System Test #7 Table 14.2-8 Chilled Water System Test #8 Table 14.2-10 Circulating Water System Test #10 Table 14.2-11 Site Cooling Water System Test #11 Table 14.2-12 Potable Water System Test #12 Table 14.2-13 Utility Water System Test #13 Table 14.2-14 Demineralized Water System Test #14 Table 14.2-15 Nitrogen Distribution System Test #15 Table 14.2-16 Service Air System Test #16 Table 14.2-17 Instrument Air System Test #17 Table 14.2-21 Radioactive Waste Building HVAC System Test #21 Table 14.2-22 Turbine Building HVAC System Test #22 Table 14.2-23 Radioactive Waste Drain System Test #23 Table 14.2-26 Fire Detection System Test #26 Table 14.2-27 Main Steam System Test #27 Table 14.2-28 Feedwater System Test #28 Table 14.2-29 Feedwater Treatment System Test #29 Table 14.2-30 Condensate Polishing System Test #30 Table 14.2-31 Feedwater Heater Vents and Drains System Test #31 Table 14.2-32 Condenser Air Removal System Test #32 23
Backup Slides (14.2)
Test Abstracts Not Reviewed Abstract Test Title Table 14.2-34 Turbine Oil Storage System Test #34 Table 14.2-37 Solid Radioactive Waste System Test #37 Table 14.2-39 Boron Addition System Test #39 Table 14.2-40 Module Heatup System Test #40 Table 14.2-49 In-core Instrumentation System Test #49 Table 14.2-50 Module Assembly Equipment Test #50 Table 14.2-53 Process Sampling System Test #53 Table 14.2-54 13.8kV [kilovolt] and Switchyard System Test #54 Table 14.2-55 Medium Voltage AC [alternating current] Electrical Distribution System Test #55 Table 14.2-56 Low Voltage AC Electrical Distribution System Test #56 Table 14.2-57 Highly Reliable DC [direct current] Power System Test #57 Table 14.2-58 Normal DC Power System Test #58 Table 14.2-59 Backup Power Supply System Test #59 Table 14.2-61 Module Control System Test #61 Table 14.2-62 Plant Control System Test #62 Table 14.2-64 Plant Protection System Test #64 Table 14.2-65 Neutron Monitoring System Test #65 Table 14.2-67 Fixed-Area Radiation Monitoring System Test #67 Table 14.2-69 Seismic Monitoring System Test #69 Table 14.2-71 Module Assembly Equipment Bolting Test #71 Table 14.2-75 Initial Fuel Loading Precritical Test #75 Table 14.2-85 Low-Power Test Sequence Test #85 Table 14.2-90 Power Ascension Test #90 Table 14.2-107 Remote Shutdown Workstation Test #107 24
LO-0519-65368 May 7, 2019 Docket No.52-048 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk One White Flint North 11555 Rockville Pike Rockville, MD 20852-2738
SUBJECT:
NuScale Power, LLC Submittal of Presentation Materials Entitled FSAR Section 3.9.2: Dynamic Testing and Analysis of Systems, Components, and Equipment, PM-0419-65367, Revision 0 The purpose of this submittal is to provide presentation materials to the NRC for use during the upcoming Advisory Committee on Reactor Safeguards (ACRS) NuScale Subcommittee Meeting on May 16, 2019. The materials support NuScales presentation of Section 3.9.2 Dynamic Testing and Analysis of Systems, Components, and Equipment, of the NuScale Design Certification Application.
The enclosure to this letter is the nonproprietary version of the presentation titled FSAR Section 3.9.2:
Dynamic Testing and Analysis of Systems, Components, and Equipment, PM-0419-65367, Revision 0.
If you have any questions, please contact Marty Bryan at 541-452-7172 or at mbryan@nuscalepower.com.
Sincerely, Zackary W. Rad Director, Regulatory Affairs NuScale Power, LLC Distribution: Robert Taylor, NRC, OWFN-8H12 Michael Snodderly, NRC, TWFN-2E26 Samuel Lee, NRC, OWFN-8H12 Gregory Cranston, NRC, OWFN-8H12 Marieliz Vera, NRC, OWFN-8H12
Enclosure:
FSAR Section 3.9.2: Dynamic Testing and Analysis of Systems, Components, and Equipment, PM-0419-65367, Revision 0 NuScale Power, LLC 1100 NE Circle Blvd., Suite 200 Corvallis, Oregon 97330 Office 541.360-0500 Fax 541.207.3928 www.nuscalepower.com
LO-0519-65368
Enclosure:
FSAR Section 3.9.2: Dynamic Testing and Analysis of Systems, Components, and Equipment, PM-0419-65367, Revision 0 NuScale Power, LLC 1100 NE Circle Blvd., Suite 200 Corvallis, Oregon 97330 Office 541.360-0500 Fax 541.207.3928 www.nuscalepower.com
NuScale Nonproprietary ACRS Subcommittee Presentation:
NuScale FSAR Chapter 3.9.2, Dynamic Testing and Analysis of Systems, Components, and Equipment May 16, 2019 1
PM-0419-65367 Revision: 0 Copyright 2019 by NuScale Power, LLC.
Template #: 0000-21727-F01 R5
Presenters J.J. Arthur, P.E.
Manager, Structures and Design Analysis Dylan Addison NuScale Mechanical Engineer Olivia Hand, P.E.
NuScale Mechanical Engineer 2
PM-0419-65367 Revision: 0 Copyright 2019 by NuScale Power, LLC.
Template #: 0000-21727-F01 R5
FSAR 3.9.2 Subject Areas
- The NuScale Power Module Seismic Technical Report, TR-0916-51502 addresses the requirement to perform dynamic analysis of the systems, components, and equipment
- The NuScale Comprehensive Vibration Assessment Program technical report, TR-0716-50439, and the NuScale Comprehensive Vibration Assessment Program Measurement and Inspection Plan technical report address the requirement for flow induced vibration assessment.
- The NuScale Power Module Short-Term Transient Analysis technical report, TR-1016-51669 addresses transients caused by failure/actuation of valves and HELB 3
PM-0419-65367 Revision: 0 Copyright 2019 by NuScale Power, LLC.
Template #: 0000-21727-F01 R5
NPM Seismic Qualification
- Confirms functional integrity and operability of SC-1 mechanical equipment after a seismic event
- Overview of methods addressed in FSAR Sections 3.7, 3.10, 3.12, and App 3A:
NPM Beam Model SSI Analysis Detailed 3D Analysis Stress Analysis (dynamically equivalent to (Reactor Building SASSI model) (full pool ANSYS model) (SSE loads applied) detailed 3D ANSYS model) 4 PM-0419-65367 Revision: 0 Copyright 2019 by NuScale Power, LLC.
Template #: 0000-21727-F01 R5
NPM Seismic Qualification 5
PM-0419-65367 Revision: 0 Copyright 2019 by NuScale Power, LLC.
Template #: 0000-21727-F01 R5
NPM Seismic Qualification
- The methodology is utilized for generating seismic loads for use in stress analyses
- Section 3.8.2 addresses stress analysis of the CNV, including the SSE
- Service Level D stress analysis for the RPV has been assessed and found acceptable
- Service Level D stress analyses for the RVIs are currently being updated (tracked as SER open item 03.09.02-11)
- ITAAC design commitments ensure that NPM components conform to the rules of construction of ASME BPVC Section III 6
PM-0419-65367 Revision: 0 Copyright 2019 by NuScale Power, LLC.
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NPM Seismic Qualification COL Item COL Item 3.9-12:
A COL applicant that references the NuScale Power Plant design certification will perform a site-specific seismic analysis in accordance with Section 3.7.2.16. In addition to the requirements of Section 3.7, for sites where the high frequency portion of the site-specific spectrum is not bounded by the CSDRS, the standard design of NPM components will be shown to have appropriate margin or should be appropriately modified to accommodate the site specific demand.
7 PM-0419-65367 Revision: 0 Copyright 2019 by NuScale Power, LLC.
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NPM CVAP Overview
- Addresses components subject to natural circulation primary coolant or secondary coolant flow in the NPM
- Consists of analysis, measurement, and inspection programs:
- Screens all NPM components for six FIV phenomena
- Evaluations based on industry standard analytical approaches and benchmark testing
- Validation testing is performed for components with safety margin less than 100%
- Inspection of all components regardless of analytically-predicted safety margin 8
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Template #: 0000-21727-F01 R5
Program Differences Compared to Recent CVAPs More components evaluated (not limited to RVI)
More FIV mechanisms considered in the analysis program Significantly lower primary coolant flow rates:
Average Velocity (ft/s) Primary Maximum Steam Upper Coolant Loop Design (Note 1) Design Flow Generator Downcomer Core Internals Transit Time Rate (lbm/s)
Gap Cross Flow (seconds)
NuScale 1.2 1.7 3.6 1.5 1,456 60.8 EPR 24 16 30 55,000 9.9 AP1000 19 16 40 34,800 10.3 US-APWR 23 14 30 54,092 12.6 SONGS 18 - - - - -
First of a kind design, no proprietary scale testing Performing majority of validation testing prior to the start-up testing program (SG assembly and inlet flow restrictor)
Larger inspection scope 9
PM-0419-65367 Revision: 0 Copyright 2019 by NuScale Power, LLC.
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NPM CVAP Design Analysis Summary
- Determine calculation inputs
- Component modal response
- ASME Appendix N guidelines
- Flow velocities
- All safety margins are positive (i.e., FIV is not predicted to occur). The most limiting results are shown in table below:
Analysis Safety Major Inputs to be Component Testing Phase Category Margin Verified FEI ~10% Frequencies Helical SG tube TB ~80% mode shapes Separate Effects vibration amplitude VS ~20%
VS ~25% fundamental frequency Factory ICIGT TB 100% N/A N/A VS ~25% fundamental frequency Factory CRD shaft TB 100% N/A N/A DHRS steam piping AR ~20% vibration amplitude Initial Startup 10 PM-0419-65367 Revision: 0 Copyright 2019 by NuScale Power, LLC.
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CVAP Measurement Program Summary TF-1 TF-2 (above)
TF-3 (right)
- Benchmarking using TF-1, TF-2 and TF-3 build-out test results for the SG assembly, and SG IFR testing
- Post-DCA validation testing using TF-3, SG IFR, and initial startup testing (steam piping)
- Initial startup testing sensors provided to confirm lack of vibration, supplementing the CVAP inspections following initial startup testing 11 PM-0419-65367 Revision: 0 Copyright 2019 by NuScale Power, LLC.
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CVAP Inspection Program Summary
- Components that screen for an FIV mechanism will be inspected before and after initial start-up testing to look for mechanical wear or signs of vibration-induced damage
- Purpose of inspection is to confirm results of analysis and validation programs
- Initial start-up testing provides for 1 million cycles of the most limiting (lowest fundamental frequency) component, helical SG tubes
- Inspections are performed using VT-1, VT-3 and general visual inspections defined in ASME Section XI, Subsection IWB-2500 12 PM-0419-65367 Revision: 0 Copyright 2019 by NuScale Power, LLC.
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CVAP COL Item
- COL applicant to provide test procedures prior to start of testing and will submit test and inspection results in accordance with RG 1.20 13 PM-0419-65367 Revision: 0 Copyright 2019 by NuScale Power, LLC.
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NPM Short Term Transient Analysis
- Purpose is to determine time-history structural response of NPM to the pressure wave resulting from a breach in the pressure boundary
- NRELAP5 is used to Heissdampf reactor (HDR) structural and acoustic model generate thermal hydraulic boundary conditions (thrust force, fluid acceleration)
- ANSYS is used to simulate the fluid structure interaction and resulting forces and moments on structures HDR time history core barrel deformations 14 PM-0419-65367 Revision: 0 Copyright 2019 by NuScale Power, LLC.
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Program Differences Compared to Previous PWR Designs and Legacy Analysis Methods
- No large diameter primary coolant piping (NPS 2).
- Valves represent the largest possible breaches in the reactor coolant pressure boundary
- Lower operating pressures, less sub-cooling, CNV is a single sub-compartment
- Legacy codes like MULTIFLEX and CRAFT2 generally use homogeneous equilibrium,1D fixed mesh, simplified or no FSI to simulate blowdown loading
- With availability of more modern codes and computing power, use of non-equilibrium, 3D models, and simulation of FSI via acoustic elements provides for enhanced prediction of pressure wave phenomena and resulting NPM loading 15 PM-0419-65367 Revision: 0 Copyright 2019 by NuScale Power, LLC.
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NPM Short Term Transient Analysis Benchmarking
- Analysis method is benchmarked against Heissdampf reactor, Marviken and Bettis Hydraulic pressure pulse experiments to demonstrate ability to accurately simulate the thermal hydraulic and structural time histories.
- Sensitivity studies were performed to determine optimal analysis settings for NPM breach locations.
- Bounding breach locations analyzed and maximum forces at moments and pressure vessel and interface locations are determined for use in NPM component stress analysis.
- No COL Items for this analysis area.
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Acronyms AR acoustic resonance ASME American Society of Mechanical Engineers BPVC Boiler and Pressure Vessel Code CFR Code of Federal Regulations CNV containment vessel COL combined license CRD Control Rod Drive CSDRS Certified Seismic Design Response Spectra CVAP Comprehensive Vibration Assessment Program DCA Design Certification Application DHRS Decay Heat Removal System EPRI Electric Power Research Institute FEI fluid elastic instability 17 PM-0419-65367 Revision: 0 Copyright 2019 by NuScale Power, LLC.
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Acronyms (continued)
FIV flow-induced vibration FSAR Final Safety Analysis Report FSI fluid-structure interaction GDC General Design Criteria HELB high energy line break ICIGT In-Core Instrument Guide Tube NPM NuScale Power Module NPS nominal pipe size RAI request for additional information RVI reactor vessel internals RXB reactor building SC-I Seismic Category I SER Safety Evaluation Report 18 PM-0419-65367 Revision: 0 Copyright 2019 by NuScale Power, LLC.
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Acronyms (continued)
SG steam generator SSI soil-structure interaction TB turbulent buffeting TF SIET test fixture 19 PM-0419-65367 Revision: 0 Copyright 2019 by NuScale Power, LLC.
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Portland Office Richland Office 6650 SW Redwood Lane, 1933 Jadwin Ave., Suite 130 Suite 210 Richland, WA 99354 Portland, OR 97224 541.360.0500 971.371.1592 Arlington Office Corvallis Office 2300 Clarendon Blvd., Suite 1110 1100 NE Circle Blvd., Suite 200 Arlington, VA 22201 Corvallis, OR 97330 541.360.0500 London Office 1st Floor Portland House Rockville Office Bressenden Place 11333 Woodglen Ave., Suite 205 London SW1E 5BH Rockville, MD 20852 United Kingdom 301.770.0472 +44 (0) 2079 321700 Charlotte Office 2815 Coliseum Centre Drive, Suite 230 Charlotte, NC 28217 980.349.4804 http://www.nuscalepower.com Twitter: @NuScale_Power 20 PM-0419-65367 Revision: 0 Copyright 2019 by NuScale Power, LLC.
Template #: 0000-21727-F01 R5
Safety Evaluation with Open Items:
Section 3.9.2, Dynamic Testing and Analysis of Systems, Structures, and Components NuScale Design Certification Application ACRS Subcommittee Meeting May 16, 2019 May 16, 2019 ACRS Subcommittee Presentation on 1
Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
Agenda
- NRC Staff Review Team
- Overview
- NuScale Power Module (NPM) Level D Analysis
- Reactor Internals Comprehensive Vibration Assessment Program (CVAP)
- Abbreviations May 16, 2019 ACRS Subcommittee Presentation on 2
Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
NRC Staff Review Team
- Technical Staff
- Yuken Wong, NRO
- Dr. Stephen Hambric, (Consultant)
- Dr. David Ma (Consultant)
- Project Management
- Marieliz Vera, Project Manager
- Greg Cranston, Lead Project Manager May 16, 2019 ACRS Subcommittee Presentation on 3
Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
Overview
- RG 1.20, Rev. 3, Comprehensive Vibration Assessment Program for Reactor Internals during Preoperational and Initial Startup Testing
- RG 1.61, Rev. 1, Damping Values for Seismic Design of Nuclear Power Plants
- RG 1.122, Rev. 1, Development of Floor Design Response Spectra for Seismic Design of Floor-Supported Equipment or Components
- Reviewed the following areas in Section 3.9.2:
- Dynamic system analysis of the reactor internals under service level D conditions
- Reactor internals comprehensive vibration assessment program (CVAP)
May 16, 2019 ACRS Subcommittee Presentation on 4
Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
NuScale Power Module Dynamic Analysis Under Service Level D Conditions May 16, 2019 ACRS Subcommittee Presentation on 5
Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
NuScale Power Module Dynamic Analysis and Level D Stress Evaluation Staffs review Scope:
- DCA Part 2, Tier 2, Section 3.9.2.5, Dynamic System Analysis of the Reactor Internals Under Service Level D Conditions
- DCA Part 2, Tier 2, Appendix A, Dynamic Structural Analysis of the NuScale Power Module
- TR-0916-51502, Rev. 1, NuScale Power Module Seismic Analysis
- NuScale power module (NPM) seismic analysis
- NPM component Level D stress evaluation
- Reactor vessel internals (RVI)
- Steam generators (SG)
- TR-1016-51669, Rev. 0, NuScale Power Module Short-Term Transient Analysis - ANSYS modeling only May 16, 2019 ACRS Subcommittee Presentation on 6
Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
NPM Seismic Models Reviewed
- 3D ANSYS NPM model
- CNV submodel
- RPV submodel
- Lower RVI submodel
- Upper RVI submodel
- CRDM submodel
- Equivalent beam ANSYS model
- Equivalent beam SAP2000 model
- 3D NPM Entire Pool ANSYS Model May 16, 2019 ACRS Subcommittee Presentation on 7
Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
Review of NPM Seismic Analysis
- Resolved major issues:
- System damping
- Fluid gap
- Acoustic absorbing coefficient
- Generation of instructure response spectra (ISRS)
- Four open items:
- NPM seismic analysis cases
- Uplift of reflector blocks
- Reactor flange tool (RFT)
- RVI and SG stress evaluation May 16, 2019 ACRS Subcommittee Presentation on 8
Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
System Damping RAI 202-8911, Question 03.09.02-46
- Concern: Applicant assigned 7% damping in the NPM system and component seismic analysis
- RG 1.61, Table 6 (mechanical and electrical components) specifies 3%
for pressure vessels.
- Table 1 (Structural material) specifies 4% for welded steel or bolted steel with friction connections
- Table 1 specifies 7% for bolted steel with bearing connections
- Applicants justifications of using 7% damping include:
- RVI joints are analogous to bolted steel structures with bearing connections (7% - RG 1.61, Table 1).
- Many sliding SG tube-to-support interfaces generate large frictional dissipative forces.
May 16, 2019 ACRS Subcommittee Presentation on 9
Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
System Damping (Contd)
- The staff noted that there are welded structures in the RVI.
- RG 1.61, Table 1 specifies 4%
- 7% damping may not be achievable in the SGs.
- The steel/steel coefficient of friction is smaller underwater than that in dry condition.
- Applicant response: Instead of 7% damping, 4% is used for the NPM system and component seismic analysis.
- Staff finds that using 4% damping in the NPM systems and component seismic analysis is reasonable.
- The integrated NPM with many connections and internal structures is unlike traditional shell type pressure vessels.
- There is additional energy dissipation provided by the connections and internal structures.
- RAI 202-8911, Question 03.09.02-46 is resolved and closed.
May 16, 2019 ACRS Subcommittee Presentation on 10 Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
Fluid Gap RAI 410-9310, Question 03.09.02-70
- Concern: The core barrel and reflector are separated by a thin fluid gap. The fluid gap was not considered in the analysis.
- With presence of fluid gap, frequencies of the core barrel and reflector are lower due to added mass effect of the fluid gap.
- Applicant response: The lower RVI submodel was updated to capture the added mass effect of the fluid gap using the ANSYS Fourier node method.
- The staff finds the response acceptable and will review the updated lower RVI submodel in TR-0916-51502 Revision 2
- RAI 9310 Question 03.09.02-70 is resolved.
May 16, 2019 ACRS Subcommittee Presentation on 11 Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
Acoustic Absorption Coefficient
- In the NPM seismic analysis, NuScale initially assumed 100%
reflection of the acoustic wave energy at the bottom of the pool.
- Results in excessive and unreasonable amplification of NPM response.
- In reality, the acoustic wave energy is partially reflected and partially absorbed by the concrete floor and surrounding soil.
May 16, 2019 ACRS Subcommittee Presentation on 12 Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
Acoustic Absorption Coefficient (contd)
- NuScale built two ANSYS models to estimate the acoustic absorption coefficient.
- Model 1: Integrated model including an NPM, reactor pool water, RXB and backfill soil.
- Applied damping to concrete and backfill to dissipates pool acoustic energy.
- Model 2: Standard model with an NPM and reactor pool water (without the RXB and backfill). Various acoustic absorption coefficients are applied at bottom of the reactor pool to attenuate the pool acoustic energy.
- Applied a 1g vertical excitation at bottom of the pool water of the two models.
- Compared the responses at key NPM locations between the two models.
- An absorption coefficient of 0.75 produces the best match between the two models.
- The staff performed an audit on the acoustic absorption analysis on December 19, 2018.
May 16, 2019 ACRS Subcommittee Presentation on 13 Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
Acoustic Absorption Coefficient (contd)
- During the audit, NuScale proposed to use an absorption coefficient of 0.4 in the NPM seismic analysis.
- Staff concluded that absorption coefficient of 0.4 is reasonable and conservative based on:
- The attenuation of the acoustic energy by the building structure and surrounding soil
- Relative acoustic impedances of concrete and water (Higher impedance ratio leads to more acoustic wave reflection and less absorption).
- Actual impedance ratio between concrete and water is about 5.
- Absorption coefficient of 0.4 yields impedance ratio of 7.9.
- This issue is resolved and closed.
May 16, 2019 ACRS Subcommittee Presentation on 14 Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
Generation of Instructure Response Spectra RAI 202-8911, Question 03.09.02-38
- Concern: TR-0916-51502-P, Rev. 0, states that ISRS at locations of equipment supports within the NPM are enveloped and broadened according to ASCE 4-13 for component design.
- ASCE 4-13, Seismic Analysis of Safety-Related Nuclear Structures and Commentary
- ASCE 4-13 permits a 15 percent reduction of the narrow frequency peak amplitude of the ISRS if certain conditions are met.
- The staff finds that the use of ASCE 4-13 in ISRS generation is inconsistent with RG 1.122, Rev. 1 (no reduction of frequency peak amplitude).
- Applicant response: TR-0916-51502, Rev. 1 was updated to remove the reference to ASCE 4-13.
- The staff finds the applicants response acceptable.
- RAI 202-8911, Question 03.09.02-38 is resolved and closed.
May 16, 2019 ACRS Subcommittee Presentation on 15 Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
NPM Seismic Analysis Cases Open Item 03.09.02-8 (RAI 202-8911, Question 03.09.02-43)
- The NPM entire pool model was analyzed for six cases with the following scenarios:
- NPM 1 or 6
- Uncracked or cracked concrete condition
- Nominal or 77% nominal NPM stiffness
- Concern: 130% nominal NPM stiffness should also be considered to account for uncertainty in the NPM model input and assumptions.
- Applicant response: Performed 12 NPM runs, including 130% nominal NPM stiffness.
- Details of the updated NPM seismic analysis are documented in TR-0916-51502-P, Rev. 2.
May 16, 2019 ACRS Subcommittee Presentation on 16 Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
Uplift of Reflector Blocks Open Item 03.09.02-9 (RAI 202-8911, Question 03.09.02-45)
- Concern: The reflector blocks are stacked and not restrained in the vertical direction.
- Lower core plate vertical ISRS acceleration at high frequency end exceeds gravity acceleration.
- Uplift of the reflector blocks from the lower core plate during an SSE was not considered in the original NPM analysis.
- Applicant response: The 3D ANSYS NPM model was modified to include ANSYS contact elements between reflector block and lower core plate to simulate uplift of the reflector blocks.
- Staff finds response acceptable.
May 16, 2019 ACRS Subcommittee Presentation on 17 Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
Reactor Flange Tool Open Item 03.09.02-10
- The applicant introduced nonlinear contact elements at the interface between lower RPV and RFT to simulate uplift of the NPM
- Documented the results in the NPM Seismic Report TR-0916-51502, Revision 2.
- The staff is reviewing the RFT modelling in NPM Seismic Report, Rev. 2.
May 16, 2019 ACRS Subcommittee Presentation on 18 Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
RVI and SG Stress Evaluation Open Item 03.09.02-11 (RAI 202-8911 Question 03.09.02-18)
- The applicant was requested to provide the seismic analysis details and Level D stress evaluation results of major RVI and SG components.
- Applicant response:
- Provided seismic analyses and Level D stress evaluation of the RVI and SG components in the RAI response.
- The analyses used the ISRSs generated from the original 6 seismic runs (i.e., not considering 130% NPM stiffness cases).
- Updated seismic analyses and Level D stress evaluation of RVI and SG components using ISRS generated from the 12 seismic runs (i.e., 130%
NPM stiffness case) will be submitted as an RAI supplement.
- The staff will review the updated RVI and SG stress evaluation in the supplemental response.
May 16, 2019 ACRS Subcommittee Presentation on 19 Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
Reactor Internals Comprehensive Vibration Assessment Program May 16, 2019 ACRS Subcommittee Presentation on 20 Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
Documents Evaluated
- Docketed documents
- TR-0716-50439, Rev. 1, NuScale Comprehensive Vibration Assessment Program Technical Report (ML18022A221)
- TR-0918-60894, Rev. 0, NuScale Comprehensive Vibration Assessment Program Measurement and Inspection Plan Technical Report (ML18341A337)
- Undocketed documents
- Audit 1: May, 16 - November 2, 2017 (ML18023A091)
- Audit 2: September 5 - October 4, 2018 (ML18333A221)
- Audit 3: 1 March 2019 - TBD May 16, 2019 ACRS Subcommittee Presentation on 21 Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
FIV Mechanisms Evaluated
- Turbulence buffeting (TB)
- Vortex shedding (VS) lock-in with structural resonances
- Fluid-elastic instability (FEI)
- Acoustic resonance (AR)
- Leakage flow instability (LFI), and flutter and galloping (F/G)
May 16, 2019 ACRS Subcommittee Presentation on 22 Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
Components Evaluated
- Helical Coil Steam generator (HCSG) tubes
- Upper core plate and support
& supports
- Pressurizer spray nozzle
- SG inlet flow restrictors (SGIFR)
- SG steam plenum
- Control rod drive shaft (CRDS)
- Core barrel
- In-core instrument guide tube (ICIGT)
- Lower core plate
- Primary and secondary coolant piping up to
- Lower riser the NPM disconnect flanges including the
- Reflector Blocks isolation valves.
- Upper rise and hanger
- CRAGT and CRAGT support
- CVS Injection line
- CRDS support
- Flow diverter
- Control rod assembly (CRA) card May 16, 2019 ACRS Subcommittee Presentation on 23 Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
Risk Areas
- Natural circulation, low power operating levels, flow rates 5-25 times lower than those in typical PWRs
- TB loads are much lower
- Components normally evaluated for TB are not susceptible to damage in NuScale design
- However, some structural components may be susceptible to FIV in spite of lower flow velocities
- Long, thin rods and tubes
- HCSG
- ICIGT
- CRDS
- AR also possible in DHRS piping side branches
- LFI unlikely in most regions due to low pressure differences
- Exception: SG inlet flow restrictors designed and evaluated by testing May 16, 2019 ACRS Subcommittee Presentation on 24 Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
NuScales Screening Studies
- Methodologies from the following sources
- ASME B&PV Code III Appendix N-1300 (Flow induced vibration of tubes)
- Blevins, Flow-induced vibration, 2nd edition
- Au-Yang, Flow-induced vibration of power and process plant components
- Computational fluid dynamics (CFD) analyses of flow velocities
- Simplified model to support thermal hydraulic analyses; structural details (including steam generator and core) not included
- Finite element (FE) models of individual components with simplified boundary conditions to estimate lowest resonance frequencies
- Damping assumptions vary, ranging from 0.5% to 1.5%
- Per RG 1.20 damping above 1% needs rigorous substantiation because higher damping will artificially increase margin May 16, 2019 ACRS Subcommittee Presentation on 25 Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
Low Margins of Safety
- HCSG tubing
- <10% margin against FEI
- <20% margin against VS
- RVI
- CRDS < 25% margin against VS
- ICIGT < 25% margin against VS
- DHRS piping ~ 20% margin primary AR
- No margin for secondary AR
- SG inlet flow restrictor - low, but unquantified LFI risk
- Design chosen based on testing of several concepts
- Issue: there are non-conservatisms in the FIV analyses that may outweigh the conservatisms
- Currently being addressed by NuScale via RAIs May 16, 2019 ACRS Subcommittee Presentation on 26 Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
General Analysis Concerns
- Flow modeling
- Non-conservative flow velocities assumed
- Empirical forcing function models call for peak (free stream) velocities, not the average velocities used by NuScale
- Spatial variability possible, ignored so far
- Structural modeling
- Coarse meshing (biases resonance frequencies high)
- Idealized pinned boundary conditions at interfaces with non-negligible clearances, fluid loading must be conservative
- If VS does occur, forced response analyses are needed to assess possible impacting and wear
- Stress amplifications/weld factors not included
- Average crossing frequency used for impact and wear assessments sometimes lower than first structural resonance frequency May 16, 2019 ACRS Subcommittee Presentation on 27 Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
General Testing Concerns
- Less benchmarking and testing than usual for a DCD
- Unique new design with no operating history or similar predecessor
- Pre-operational FIV testing infeasible due to natural circulation design
- However, turbulent buffeting benchmarking unnecessary due to very low flow rates
- Staff proposed the following for reasonable assurance against significant FIV
- Preliminary/validation testing focuses on key FIV mechanisms with low margins of safety and high uncertainty
- Initial startup testing will focus on identifying any unexpectedly high FIV
- Not intended for specific mechanisms or benchmarking May 16, 2019 ACRS Subcommittee Presentation on 28 Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
HCSG Tubing and RVI Vortex Shedding and Lock-In Open Items 03.09.02-01, 02, 03 May 16, 2019 ACRS Subcommittee Presentation on 29 Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
Vortex Shedding/Lock-In
- Occurs when:
- Vortex shedding (VS) frequency aligns with a structural resonance, and
- Impedance of the structural resonance is low
- Low damping, low modal mass (Damping Parameter)
- Maximum VS frequency for NuScale cylinders: St = fD/U ~ 0.25
- At lock-in, vibration amplitude can exceed cylinder diameter
- CRD shafts and ICIGTs would strongly and repeatedly impact supports
- ASME N-1324.1 provides criteria (a) - (d) for lock-in avoidance Drag, 2x Lift freq Lift May 16, 2019 ACRS Subcommittee Presentation on 30 Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
CRDS and ICIGT VS (OI 03.09.02-03)
Top sections of ICIGT and CRD Shafts exposed to cross flow; vortex shedding/lock-in is possible CFD analysis of flow speeds Resonances computed with FE models assuming pinned in-plane supports May 16, 2019 ACRS Subcommittee Presentation on 31 Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
HCSG Lower Tubing VS (OI 03.09.02-01)
Bottom SG tubes exposed to cross flow, vortex shedding/lock-in is possible 0.009 nominal clearances specified, operating clearances unknown NuScale assumes fully active supports for FIV analyses May 16, 2019 ACRS Subcommittee Presentation on 32 Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
ASME VS/Lock-In Avoidance Criteria NuScale 1.5% damping assumption requires verification (b)
(Inverse of Strouhal Number)
NuScale range with 1% damping with 1.5% damping (d)
(c)
(a)
(=0.5Cn)
May 16, 2019 ACRS Subcommittee Presentation on 33 Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
HCSG Tubing Fluid Elastic Instability Open Items 03.09.02-1 and 03.09.02-2 May 16, 2019 ACRS Subcommittee Presentation on 34 Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
HCSG Fluid-Elastic Instability
- Occurs when:
- Vortex field around multiple tubes couples constructively with structural motion
- Flow velocity exceeds critical value
- Extremely high displacements, usually Vibration amplitude limited by contact with nearby tubes
- Estimate reduced critical velocity via empirical fit with two constants C and a to measured data for different tube array types
- Critical velocity depends on mass-damping Critical velocity May 16, 2019 ACRS Subcommittee Presentation on Increasing flow 35 Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
HCSG Fluid-Elastic Instability
- NuScale computes critical velocities for first 50 modes of HCSG tubes V/fD
- Estimates resonance frequencies and mass-damping of each mode
- Considers Connors (straight tube array) and Chen, 1983 (helical array) empirical constants 2.15
- Critical velocities are compared to gap NuScale SG 10-30 Hz Reduced Critical velocities estimated from CFD bulk flow and Velocities blockage of tubes 1.5
- HCSG reduced critical velocities (V/fD) with fully active supports range from ~ 1.5 - 2 for modes with resonance frequencies less than 30 Hz
- Connors reduced critical velocity is 2.15, so small margin exists
- Actual reduced critical velocity should be around 1.5 per Chen; tubes may experience onset of FEI between 10 and 30 Hz Resonance Frequency May 16, 2019 ACRS Subcommittee Presentation on 36 Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
HCSG Fluid-Elastic Instability
- If any supports are inactive, longer sections means lower resonance frequencies, so more modes will be susceptible to FEI
- Non-conservatisms:
- SG tube damping is assumed to be 1.5%, greater than RG 1.20 specified 1%
- No mesh convergence studies, biasing resonance frequencies higher
- Lower (non-conservative) average velocity through region used for analyses with partially inactive supports
- Actual flow velocities will vary throughout the annulus; regional velocities may be higher:
Chen, JSV, 91 (4),
539-569, 1983 May 16, 2019 ACRS Subcommittee Presentation on 37 Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
HCSG SIET FIV Testing
- Previous HCSG tests primarily for thermal-hydraulic assessments, but limited FIV data also acquired
- TF single tube internal flow
- Unexpectedly high internal loading peak, not yet accounted for in FIV analyses
- TF tube arrays, but with limited instrumentation and non-prototypic supports
- Encouraging data show no indications of FEI (or VS)
- Due to low VS and FEI margins,TF-3 Design Validation Testing Underway May 16, 2019 ACRS Subcommittee Presentation on 38 Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
HCSG SIET FIV Testing
- Prototypic construction
- Heavily instrumented
- Modal dynamic tests (near term, will support final SER)
- Staff goal: on-site audit of testing and results to ensure:
- Structural boundary condition modeling is appropriate
- Structural damping assumptions are substantiated
- Flow tests (unknown time frame, will likely not support final SER)
- Staff goal: ensure flow test procedures are sufficiently robust to provide reasonable assurance any VS/lock-in or NuScale SIET TF3 FEI will be found and mitigated
- Decision for TF-3 results for DC review May 16, 2019 ACRS Subcommittee Presentation on 39 Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
DHRS Piping Acoustic Resonances Open Item 03.09.02-4 May 16, 2019 ACRS Subcommittee Presentation on 40 Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
Piping Acoustic Resonances
- Occur when:
- A flow instability over a cavity opening locks into an acoustic resonance (usually within the cavity)
- Instabilities occur in harmonics
- Primary (and strongest): half wavelength across cavity
- Secondary (weaker): full wavelength across cavity
- Occurs at half the flow speed of primary
- Higher harmonics generally too weak to lock-in
- Resulting acoustic pressures can be severe Increasing flow speed May 16, 2019 ACRS Subcommittee Presentation on 41 Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
DHRS Piping Acoustic Resonances
- Per test data in open literature, AR is possible if 0.35 < fD/U < 0.62
- f is the acoustic cavity resonance frequencies
- D is the cavity diameter
- U is the flow rate
- Two possible AR locations:
- Closed side branch from containment system steam tee to the DHRS actuation valve
- fD/U=0.75, ~ 20% margin
- DHRS condensate line from SG system feedwater tee to DHRS passive condenser
- fD/U=1.33, high margin against primary instability May 16, 2019 ACRS Subcommittee Presentation on 42 Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
DHRS Piping Acoustic Resonances
- Proposed instrumentation for initial startup testing
- Will monitor both primary and secondary shear layer instabilities
- RAI response acceptable May 16, 2019 ACRS Subcommittee Presentation on 43 Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
Leakage Flow Instability (LFI)
Open Items 03.09.02-05 and 03.09.02-06 May 16, 2019 ACRS Subcommittee Presentation on 44 Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
Leakage Flow Instability
- Occurs in:
- Narrow gaps between components with significant pressure drops
- Control rods in guide tubes
- Inlet flow restrictors
- Damage occurs when flow instability locks in to structural resonance(s)
- Occurs even with low flow rates
- Has been significant in existing reactors
- e.g., control rods in guide tubes
- Guidance from ANL report (Mulcahy, ANL-83-43)
- Qualitative: obstructions should be downstream
- Quantitative: every situation unique, requires measurements to assess risk May 16, 2019 ACRS Subcommittee Presentation on 45 Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
Leakage Flow Instability
- Individual flow restrictors will be placed within each SG tube inlet
Purpose:
mitigate another instability: Density Wave Oscillation (DWO) within SG tubes
- No analysis of LFI mechanisms
- However, multiple designs tested by NuScale May 16, 2019 ACRS Subcommittee Presentation on 46 Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
Leakage Flow Instability
- Design least susceptible to LFI chosen
- Test results show no sign of LFI or any other significant FIV
- Minor changes made to final design
- Design Validation testing planned prior to initial startup in separate facility
- Test plan provided in MIP, reviewed by staff and found to be reasonable
- Lessons learned from design tests will be applied to validation testing
- Report with results will be issued to the NRC after Design Certification - May impose license condition or COL item May 16, 2019 ACRS Subcommittee Presentation on 47 Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
LFI - Other Components
- Other NuScale RVI with potential leakage flow paths indicated to have very low pressure differentials
- Analyses are ongoing for CRDS, ICIGT, and CRAGT flow gaps
- Hold down forces on upper/lower riser tapered joint preclude any gap flow
- Instrumentation being developed for initial startup testing to detect any unexpected LFI, or other strong FIV May 16, 2019 ACRS Subcommittee Presentation on 48 Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
Planned Measurements and Inspections Open Item 03.09.02-07 May 16, 2019 ACRS Subcommittee Presentation on 49 Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
Measurements
- Described in MIP
- Awaiting final SIET TF-3 flow testing plan
- Ensure sufficient rigor to provide reasonable assurance there will be no significant VS and/or FEI in HCSG in prototype and subsequent plants
- Awaiting instrumentation and pre-test predictions for initial startup testing
- Limited in scope due to low risk of significant FIV
- Goal: capture and localize any unexpectedly high FIV so that it may be mitigated May 16, 2019 ACRS Subcommittee Presentation on 50 Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
Inspections
- Components evaluated in the analysis program are inspected
- Components most susceptible to FIV are examined in limiting and representative locations
- Staff finds the inspection methods and areas are consistent with RG 1.20 May 16, 2019 ACRS Subcommittee Presentation on 51 Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
Summary of Open Items
- 03.09.02-01 (RAI 427-9408, Question 03.09.02-74, HCSG)
- Address design concerns for HCSG tube supports, cantilevers, and welds
- Analysis concerns
- Non-conservative flow velocities used for HCSG FIV analyses
- Provide FE mesh convergence studies
- Justify idealized structural boundary conditions
- Substantiate assumed damping higher than 1% (associated with tube boundary conditions and assumed tightness of fit)
- Clarify if simplified random analysis methods used
- Analysis results
- Justify average crossing frequencies much lower than fundamental resonance frequencies
- Provide VS forced response/fatigue calculations
- SIET Testing
- Account for strong spectral peaks in secondary flow pressures in TF-1 measurements
- Address resonance peaks in TF-2 measurements
- Provide TF-3 testing plans May 16, 2019 ACRS Subcommittee Presentation on 52 Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
Summary of Open Items
- 03.09.02-02 (RAI 386-9316, Question 03.09.02-52 Modeling procedures and SIET TF1 and TF2)
- Validate FE modeling procedures, perhaps using SIET TF1 and/or TF2 measurements
- 03.09.02-03 (RAI 427-9408, Question 03.09.02-73, CRDS and ICIGT)
- Lack of testing to assess possible VS/lock-in
- Non-conservative flow velocities used for ICIGT and CRDS FIV analyses
- Lack of mesh convergence studies
- Justification of idealized boundary conditions
- Clarify if simplified random analysis methods used
- Average crossing frequencies much lower than fundamental resonance frequencies
- VS forced response/fatigue calculations not provided
- Provide test plan for factory testing May 16, 2019 ACRS Subcommittee Presentation on 53 Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
Summary of Open Items
- Assess possibility of AR due to second order shear instabilities (NOW RESOLVED)
- 03.09.02-05 (RAI 386-9316, Question 03.09.02 SGIFR LFI)
- Provide test plan for final SGIFR testing (NOW CLOSED) - May impose COL item or license condition to review final design test results
- 03.09.02-06 (RAI 427-9408, Question 03.09.02 RVI LFI)
- Provide details of LFI screening of RVI
- 03.09.02-07 (RAI 427-9408, Question 03.09.02 Initial startup testing)
- Provide expected vibration levels, complete instrumentation, specifications, final test conditions, pretest predicted vibration and pressure levels, and acceptance criteria May 16, 2019 ACRS Subcommittee Presentation on 54 Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
Next Steps
- On-site audit of HCSG SIET TF-3 build-up and dynamic testing
- Summer 2019
- Evaluation/closure of RAI responses
- Review of updated CVAP
- Will include revised FIV margins of safety
- Review of updated MIP
- Will include finalized test plans:
- SIET TF-3
- SGIFR
- Initial Startup Testing instrumentation and pre-test predictions May 16, 2019 ACRS Subcommittee Presentation on 55 Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
Abbreviations ACRS - Advisory Committee on Reactor Safeguards AR - Acoustic Resonance ASCE - American Society of Civil Engineers CRDS - Control Rod Drive Shaft/System CVAP - Comprehensive Vibration Analysis Plan CRAGT - Control Rod Assembly Guide Tube COL - Combined License DC - Design Certification DCA - Design Certification Application DHRS - Decay Heat Removal System ECCS - Emergency Core Cooling System FE - Finite Element FEI - Fluid-Elastic Instability FIV - Flow-Induced Vibration May 16, 2019 ACRS Subcommittee Presentation on 56 Nonproprietary NuScale DCA Part 2, Tier 2, Section 3.9.2
Abbreviations (contd)
- HCSG - Helical Coil Steam Generator
- ICIGT - In Core Instrumentation Guide Tube
- ISRS - Instructure Response Spectra
- LFI - Leakage Flow Instability
- MIP - Measurement and Inspection Plan
- RG - Regulatory Guide
- RXB - Reactor Building
- RVI - Reactor Vessel Internals
- SER - Safety Evaluation Report
- SGIFR - Steam Generator Inlet Flow Restrictor
- TB - Turbulent Buffeting