ML22347A188
| ML22347A188 | |
| Person / Time | |
|---|---|
| Issue date: | 11/01/2022 |
| From: | Advisory Committee on Reactor Safeguards |
| To: | |
| References | |
| NRC-2149 | |
| Download: ML22347A188 (1) | |
Text
Official Transcript of Proceedings NUCLEAR REGULATORY COMMISSION
Title:
Advisory Committee on Reactor Safeguards Docket Number:
(n/a)
Location:
teleconference Date:
Tuesday, November 1, 2022 Work Order No.:
NRC-2149 Pages 1-98 NEAL R. GROSS AND CO., INC.
Court Reporters and Transcribers 1716 14th Street, N.W.
Washington, D.C. 20009 (202) 234-4433
NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 1
1 2
3 DISCLAIMER 4
5 6
UNITED STATES NUCLEAR REGULATORY COMMISSIONS 7
ADVISORY COMMITTEE ON REACTOR SAFEGUARDS 8
9 10 The contents of this transcript of the 11 proceeding of the United States Nuclear Regulatory 12 Commission Advisory Committee on Reactor Safeguards, 13 as reported herein, is a record of the discussions 14 recorded at the meeting.
15 16 This transcript has not been reviewed, 17 corrected, and edited, and it may contain 18 inaccuracies.
19 20 21 22 23
1 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 UNITED STATES OF AMERICA 1
NUCLEAR REGULATORY COMMISSION 2
+ + + + +
3 700TH MEETING 4
ADVISORY COMMITTEE ON REACTOR SAFEGUARDS 5
(ACRS) 6
+ + + + +
7 TUESDAY 8
NOVEMBER 1, 2022 9
+ + + + +
10 The Advisory Committee met via 11 teleconference at 1:00 p.m., Joy L. Rempe, Chairman, 12 presiding.
13 14 COMMITTEE MEMBERS:
15 JOY L. REMPE, Chairman 16 WALTER L. KIRCHNER, Vice Chairman 17 DAVID A. PETTI, Member-at-Large 18 RONALD G. BALLINGER, Member 19 VICKI M. BIER, Member 20 CHARLES H. BROWN, JR., Member 21 VESNA B. DIMITRIJEVIC, Member 22 GREGORY H. HALNON, Member 23 JOSE A. MARCH-LEUBA, Member 24 MATTHEW W. SUNSERI, Member 25
2 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 ACRS CONSULTANT:
1 STEPHEN SCHULTZ 2
3 DESIGNATED FEDERAL OFFICIAL:
6 7
8 9
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26
3 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 C-O-N-T-E-N-T-S 1
Page 2
Opening Remarks by the ACRS Chairman...............4 3
Opening Statement..................................6 4
Agenda and Items of Current Interest..............10 5
SECY on Potential Expansion of Current NRC policy 6
on Common Cause Failures (Open)..............10 7
Remarks from the Subcommittee Chairman............11 8
Presentations and discussion with representatives 9
from the NRC staff................................12 10 Regulatory Guide (RG) 1.82, Revision 5, "Water Sources 11 for Long-term Recirculation Cooling following 12 a Loss-of-Coolant Accident" (Open).........72 13 Remarks from the Subcommittee Chairman............72 14 Presentations and discussion with representatives 15 from the NRC staff................................74 16 17 18 19 20 21 22 23 24 25
4 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 P R O C E E D I N G S 1
(1:00 p.m.)
2 CHAIRMAN REMPE: Good afternoon. This 3
meeting will now come to order. This is the first day 4
of the 700th meeting of the Advisory Committee on 5
reactive safeguards.
6 I'm Joy Rempe, Chairman of the ACRS. Other 7
Members in attendance are Ron Ballinger, Charles Brown, 8
Vesna Dimitrijevic, Greg Halnon, Walt Kirchner, Jose 9
March-Leuba, Dave Petti, Matt Sunseri and I believe 10 we're going to be joined soon by Vicki Bier.
11 I note we do have a quorum and today the 12 Committee is meeting in person and virtually. The ACRS 13 was established by the Atomic Energy Act and is governed 14 by the Federal Advisory Committee Act.
15 The ACRS section of the U.S. NRC Public 16 website provides information about the history of this 17 Committee and documents such as our charter, bylaws, 18 Federal Register Notices for meetings, letter reports 19 and transcripts of all full and subcommittee meetings 20 including all slides presented at the open meetings.
21 The Committee provides its advice on safety 22 matters to the Commission through its publicly 23 available letter reports. The Federal Register notice 24 announcing this meeting was published on October 14th, 25
5 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 2022.
1 This announcement provided a meeting 2
agenda as well as instructions for interested parties 3
to submit written documents or request opportunities 4
to address the Committee.
5 The Designated Federal Officer for today's 6
meeting is Ms. Christina Antonescu. A communications 7
channel has been opened to allow members of the public 8
to monitor the open portions of the meeting.
9 Members of the public may use an MS Teams 10 link to these slides and other discussion materials 11 during these open sessions. MS Teams link information 12 was placed in the Federal Register Notice and Agenda 13 on the ACR's public website.
14 We received no written comments or requests 15 to make oral statements from members of the public 16 regarding today's sessions. Periodically the meeting 17 will be open to accept comments from participants 18 listening to our meetings.
19 Written comments may be forwarded to Ms.
20 Christina Antonescu. During today's meeting, the 21 Committee will consider two topics. The SECY on 22 Potential Expansion of Current NRC Policy on Common 23 Cost Failures and Regulatory Guide 1.82, Rev 5, Water 24 Sources for Long-term Recirculation Cooling following 25
6 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 a Loss-of-Coolant Accident.
1 A transcript of the open portions of the 2
meeting is being kept and it is requested the speakers 3
identify themselves and speak with sufficient clarity 4
and volume so they can be readily heard.
5 Additionally, participants should mute 6
themselves when not speaking. So at this time, I'd 7
like to ask other members if they have any opening 8
remarks.
9 PARTICIPANT: Thank you, Madame Chair.
10 MEMBER BIER: Joy, I have no opening 11 remarks, but I just wanted to let you know I'm in 12 attendance. I joined a couple of minutes late.
13 CHAIRMAN REMPE: Thank you, Vicki.
14 Member Kirchner, would you like to --
15 MEMBER KIRCHNER: Yes, thank you, Madame 16 Chair.
17 CHAIRMAN REMPE: Yes.
18 MEMBER KIRCHNER: So today is the 700th 19 meeting of the Advisory Committee on reactor 20 safeguards. And I thought it might be of use and 21 historical value to share some information with you.
22 In 1947, the U.S. Atomic Energy Commission 23 recognized the need for an independent technical group 24 to review and provide advice on reactor safety matters.
25
7 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 And thus, a Reactor Safeguard Committee was formed 1
chaired by Dr. Edward Teller.
2 In 1950, the AEC established a second 3
committee called the Industrial Committee on Reactor 4
Location Problems which was chaired by C. Rogers 5
McCullough.
6 And it was charged with the responsibility 7
of advising on what we would today consider siding 8
issues including seismic and hydrological 9
characteristics of proposed sites.
10 In 1953, the Reactor Safeguard Committee 11 and the Industrial Committee on Reactor Location 12 Problems were combined by the AEC and the ACRS was 13 formally established.
14 There were 13 Members on that original 15 Committee. Mr. McCullough continued as the Chair, four 16 from academies, seven from industry, interestingly 17 enough, one from an insurance company and one from the 18 U.S. Weather Bureau.
19 And they were assisted by a secretary which 20 would be our Executive Director today. And in noting 21 this, I would like to look forward approximately five 22 years from today will be the 750th meeting and I'd like 23 to put a marker down.
24 I think it would be appropriate at that 25
8 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 point under some new Chair to host a conference that 1
would mark ACRS contributions to reactors safety. And 2
hopefully they would invite past members as well to 3
attend.
4 And I would note such a conference was held 5
evidently in concert with the 500th meeting of this 6
Committee. With that, I thank you, Madame Chairman.
7 CHAIRMAN REMPE: Thank you for the 8
historical reminder of the history of this Committee.
9 Any other members have any other opening remarks?
10 So if not, I'd like to ask the Member Charles Brown 11 to lead us in our first topic for today's meeting.
12 MEMBER BROWN: Might be nice if I turned 13 my microphone on. Okay, this is just as, we're going 14 to run through fundamentally what we ran through during 15 the subcommittee meeting. It's whose, NRC, Samir, are 16 you going to be doing the presentation for this?
17 MR. BENNER: Samir will be leading the --
18 MR. BROWN: I can't hear you.
19 MR. BENNER: -- presentation, Member 20 Brown. This is Eric Benner, I'll do the kickoff from 21 our side.
22 MR. BROWN: We've got a -- yes, we can't 23 hear you right now. I guess we've got a technical 24 problem.
25
9 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 CHAIRMAN REMPE: Oh, could you speak 1
again? Let's see, I've increased the volume and I hope 2
that helps.
3 MR. BENNER: Okay. One, two, --
4 MEMBER BROWN: No.
5 MR. BENNER: -- three, four.
6 CHAIRMAN REMPE: Can you also increase 7
your volume.
8 MR. BENNER: My microphone volume? I 9
will, yes.
10 MEMBER BROWN: Yes, you're very faint, 11 Eric.
12 CHAIRMAN REMPE: Yes, that helps. Other 13 people I can hear. And so it's just you, Eric.
14 MR. BENNER: Okay, is that any better?
15 CHAIRMAN REMPE: Maybe just get real close 16 to your mic and I think we'll manage.
17 MR. BENNER: Okay. I, my piece is fairly 18 short so I will speak loudly and then turn it over to 19 people who can better manipulate this equipment.
20 Again, so as Member Brown said, this will largely 21 replicate what we discussed at the subcommittee 22 meeting.
23 I will say in respect for the Committee's 24 time, we have abbreviated some of what I would call 25
10 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 the background and have focused it more on the issues 1
that were raised at the subcommittee meeting both by 2
the subcommittee and in the industry presentation.
3 But we will, we certainly will go anywhere 4
in the discussion where the Committee wants to go.
5 We thank you for your time and with that, I will turn 6
it over to Samir.
7 MEMBER KIRCHNER: Yes, before we continue, 8
Charlie, can you just introduce the topic so it's on 9
the record and transcript?
10 MEMBER BROWN: Oh, okay. This is an 11 expansion of the SECY, get the right date, what's the 12 old one? '83, no, '93-087 on Common Cause Failure and 13 the SRM that the Commission provided providing their 14 additional comments and observations on.
15 And they will go through those as part of 16 this overall presentation point by point through the 17 SECY and the Commission's comments on it. Did I get 18 that correct, Samir?
19 MR. DARBALI: Yes.
20 MEMBER BROWN: Okay, and one observation 21 I would make and I don't, we didn't beat on this as 22 much as we maybe should have, but one of the key points 23 for, if I can find down and see where the right answer 24 is of this expansion of the policy is to address the 25
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(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 diversity, allow risk assessments to address diversity 1
of the design in terms of multiple software, different 2
processors, whatever diversity sort of means that comes 3
into play.
4 While you're going through this and others 5
who are there, just one of the things I like to talk 6
about after you finish the presentation just explores, 7
when you talk about not providing any diverse automatic 8
actuation of safety functions, how do you envision that?
9 What is the thought process as opposed to 10 just the magic words of saying with the risk-informed 11 approach we would be addressing whether you would need 12 diverse automatic actuation of safety functions as has 13 been done for the last 30 years or more.
14 So just keep that in mind until we get to 15 the end. We go through the presentation and other than 16 that, I'll turn it over to you, Samir.
17 MR. DARBALI: Okay. Thank you, Member 18 Brown and thank you, Eric. Oh, alongside me presenting 19 this afternoon will be Steven Alferink and Norbert 20 Carte.
21 And our project managers for this project 22 are BP Jain and Michael Marshall. And we've also had 23 a diverse membership in our working group and a lot 24 of support from NRR and research staff.
25
12 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 Here's the outline for our presentation 1
today. We'll go over the background and key messages 2
from our effort to expand the Digital I&C Common Cause 3
Failure Policy.
4 We'll cover the purpose of the proposed 5
expanded policy described in SECY 22-076. We'll 6
present the Staff's position on the questions the ACRS 7
Digital I&C subcommittee asked the Staff back in the 8
September meeting.
9 We'll go over the new points in SECY 22-076 10 and we'll finish by discussing the next steps. As we 11 know, nuclear power plants continue to install Digital 12 I&C technology which results in increased reliability 13 and safety benefits.
14 However, this use of digital technology 15 can also introduce digital common cause failures. The 16 current policy on Digital I&C CCFs is in Staff 17 Requirements Memorandum to SECY 93-087 which requires 18 a diverse means of a postulated common cause failure 19 could disable a safety function.
20 The diverse means may be an automatic or 21 an action or include manual actions. The Staff has 22 been expanding the use of risk Informed approach as 23 much as is allowed by these SRI.
24 However, the current policy does not allow 25
13 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 for the use of risk informed approaches to determine 1
when a diverse means would not be required. Because 2
of this, the Staff developed SECY 22-076 to allow for 3
greater use of risk-informed approaches to address 4
Digital I&C CCFs for high safety significant systems.
5 The key messages from our presentation are 6
that the proposed expanded policy in SECY-22-076 7
encompasses the current points of SRM-SECY-93-087 and 8
expands the use of risk-informed approaches in Points 9
2 and 3.
10 When taken together, the four points 11 provide criteria for the assessment of diversity and 12 defense and depth against CCFs. Use of risk-informed 13 approaches will be consistent with the Safety Goal 14 Policy Statement, the PRA Policy Statement and 15 SRM-SECY-98-144.
16 The current policy will continue to remain 17 a valid option for applicants and licensees and Point 18 4 regarding dependent and diversity's place in manual 19 controls ensures the health and safety of the public.
20 And it is already risk informed as it 21 focuses only on those critical safety functions needed 22 to ensure the safety of the facility. The purpose of 23 the SECY is to request the Commission, expand the 24 current policy to allow the use of risk-informed 25
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(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 approaches to demonstrate the appropriate level of 1
defense and depth including not providing any diverse 2
automatic actuation of safety functions.
3 This expanded policy would be applicable 4
to new or amended licenses and design approvals for 5
all nuclear power plants, power plant types under Parts 6
50 and 52.
7 The Staff sent the SECY to the Commission 8
in August of this year and we are currently waiting 9
for direction from the Commission on how to move 10 forward. I'm on slide 8 now.
11 The ACRS Digital I&C subcommittee provided 12 some question to the Staff during the September meeting.
13 The first question was if the revised policy would 14 be applicable to advanced reactors.
15 And the answer to this question is yes.
16 The policy would apply to advanced reactors, licensed 17 under Parts 50 and 52. When we get to the third question 18 below, we'll explain how reactor designs that may or 19 may not seem to fit within the policy would be addressed.
20 The second question was related to whether 21 those aspects of the current policy for which the Staff 22 did not request a change carry forward unaltered.
23 This question was focused on Point 4 and 24 the Commission's statement in SRM-SECY-93-087 that 25
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(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 certain requirements in the original SECY were highly 1
prescriptive.
2 One of these requirements being that the 3
diversities placed a manner of controls had to be 4
hardwired. The ACR CRL subcommittee noted that the 5
SECY-22-076 was silent on this matter and wanted to 6
know if expanded policy maintain the Commission's 7
direction from the original SRM.
8 The answer to his question is yes, the Staff 9
intended to maintain the Commission's direction 10 regarding this matter.
11 MEMBER BROWN: I guess, this is Charlie, 12 I guess the point being is there is nothing that says 13 that in the 0076 as presently written. At least I 14 didn't find it. Is that correct?
15 MR. DARBALI: Correct. It is --
16 MEMBER BROWN: Okay.
17 MR. DARBALI: It is22-076 did not mention 18 anything specifically from 93-087, then we're carrying 19 that forward.
20 MEMBER BROWN: Okay, go ahead.
21 MR. DARBALI: Okay. And the last question 22 was if different reactor types warrant consideration 23 of different critical safety functions. And the answer 24 is yes.
25
16 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 The expanded policy is intended to be 1
technology neutral, but it does rely on the Staff's 2
licensing experience and assumptions about the design 3
of the facility such as the process of a main control 4
room.
5 We recognize that the critical safety 6
functions listed in the original SECY in SECY-22-076, 7
and in BTP-7-019, may not be the appropriate set for 8
all reactor designs.
9 But the expanded policy provides for the 10 use of existing regulatory tools like extensions and 11 alternatives that, if necessary, can be used to 12 accommodate designs with different critical safety 13 functions.
14 If the Staff encounters a reactor design 15 where the policy would not be applicable, the Staff 16 will engage the Commission as appropriate. Any 17 questions before I continue?
18 All right, here on Slide 9, it's a figure 19 that shows the proposed expanded policy that 20 encompasses the current position in SRM-SECY-93-087 21 with clarifications and provides for risk-informed 22 approaches in Points 2 and 3 to address Digital I&C 23 Common Cause Failures.
24 The current path shown on the left in green 25
17 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 allows for the use of best estimate analysis and diverse 1
means to address a potential CCF. Whereas the 2
risk-informed path on the right allows for the use of 3
risk-informed approaches and other design techniques 4
or measures other than diversity to address a potential 5
CCF.
6 And I know we'll get these towards the end, 7
but we're talking about consideration of whether the 8
CCF can be properly prevented or mitigated. And in 9
the next slides, we'll show each of the four points 10 of the expanded policy.
11 This Slide shows Point 1 of SECY-22-076 12 which calls for a defense in diversity assessment of 13 the facility incorporating the proposed Digital I&C 14 system.
15 This assessment is to be, is to demonstrate 16 that vulnerabilities to Digital I&C CCFs have been 17 adequately identified and addressed. Point 1 does not 18 preclude the use of risk-informed approaches for the 19 D-3 assessment.
20 And the level of rigor of the assessment 21 is to be commensurate with the risk significance of 22 the Digital I&C system. The current guidance in branch 23 technical positions 7-019, Revision 8 supports a 24 greater approach in applying a level of rigor for the 25
18 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 D3 assessment.
1 And we'll continue to refine this guidance 2
if needed. I will now turn it over to Steve Alferink 3
who will go over Points 2 and 3.
4 MR. ALFERINK: Thank you, sir. This is 5
Steven Alferink. As Samir said, I'll discuss Points 6
2 and 3 of the proposed policy. Point 2 contains the 7
requirements for evaluating postulated Digital I&C 8
CCFs.
9 As you can see on the slide, Point 2 10 consists of three paragraphs. The first paragraph 11 requires that Applicants analyze each postulated CCF 12 in the D3 assessment and it allows Applicants to use 13 either best estimate methods or a risk-informed 14 approach.
15 The second paragraph describes the 16 evaluation when using best estimate methods. This 17 paragraph meets the intent of the current Point 2 with 18 some minor wording changes.
19 This paragraph requires that Applicants 20 consider each event evaluated in the accident analysis 21 section of the Safety Analysis report when analyzing 22 each postulated CCF.
23 The third paragraph describes the 24 evaluation when using a risk-informed approach. This 25
19 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 paragraph is in addition to the current Point 2. This 1
paragraph requires the Applicants evaluate the 2
risk-informed approach against the Commission's policy 3
and guidance of risk-informed decision making.
4 This paragraph also specifies that the 5
Staff will review Applications that use risk-informed 6
approaches or consistency with established policy and 7
guidance and risk-informed decision making.
8 In contrast to the evaluation using best 9
estimate methods, the Staff expects the Applicants 10 using a risk-informed approach will consider a broad 11 spectrum of initiating events not limited to only those 12 evaluated in the accident analysis section of the Safety 13 Analysis Report.
14 Next slide please. With respect to Point 15 2, the Staff's goal is that the acceptance criteria 16 for risk-informed approaches for Digital I&C CCFs will 17 be consistent with the NRC's broader practices and 18 guidance for risk-informed decision making and not 19 specific to Digital I&C.
20 As an example, the Staff intends to review 21 license amendment requests that use risk-informed 22 approaches for conformance to the guidance in Reg Guide 23 1.174. The Staff does not envision approaches that 24 are radical departures from existing practices. Next 25
20 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 slide please.
1 MEMBER BROWN: Oh, don't go. Don't leave 2
yet. This is Charlie. How are you going to make a 3
decision that you're not going to accept their approach 4
using a risk-informed decision?
5 MR. ALFERINK: Well I --
6 MEMBER BROWN: You haven't laid out any 7
guidelines for that yet.
8 MR. ALFERINK: That's correct. We still 9
have to develop the implementing guidance. I would 10 say at this point, we're just envisioning that it will 11 not be a radical departure.
12 MEMBER BROWN: Where would you put this 13 implementing guidance? Radical departure and stuff 14 like that, those are critical words. And you mentioned 15 this in the last meeting.
16 MR. ALFERINK: I think the intent is we 17 would like to keep it within the current paradigm.
18 We're not intending to do something that's completely 19 different.
20 MEMBER BROWN: But well, if you don't have 21 a diverse, that's completely different. Isn't it?
22 MR. ALFERINK: I'm talking about the 23 regulatory process for evaluating it.
24 MEMBER BROWN: Okay, my question then is 25
21 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 how do you determine whether you're going to accept 1
the risk-informed approach or not? That you don't have 2
any implementing guidance for?
3 MR. ALFERINK: That's correct. We still 4
have to develop the implementing guidance for that.
5 MEMBER BROWN: So you don't know how you're 6
going to say no?
7 MR. ALFERINK: At this point, the guidance 8
has not been developed so you're correct.
9 MEMBER BROWN: And if --
10 MR. DARBALI: And I believe what Steven 11 is saying is that risk-informed approaches have been 12 used in other disciplines outside of Digital I&C and 13 so we want to maintain consistency with those.
14 MEMBER BROWN: Okay, that's kind of 15 amorphous. All right, I'm making the point just so 16 that Members will, Committee Members will understand 17 that this is a, we have an objective to approach to 18 taking this approach.
19 We didn't say that obviously you're all 20 intending to try to go in that direction. The key issue 21 here is how do you know, how do you make a decision 22 to say no and because you're not saying, you're not 23 requiring them to do something?
24 Everything is now based on the 25
22 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 risk-informed approach. Even Point 1 says has added 1
the word about risk-informed decision making even 2
though there were no real details for that. Two and 3
three were where the meat and potatoes were.
4 So okay that's just something that we need 5
to think about. Go ahead.
6 MR. ALFERINK: Okay so now we should be 7
on Slide 14. So now we'll discuss Point 3 as the 8
proposed policy. Point 3 contains the requirements 9
for addressing postulated Digital I&C CCFs.
10 When discussing Point 3 it is helpful to 11 keep in mind that the current policy requires a diverse 12 means to address postulated CCFs that can disable a 13 safety function.
14 Point 3 also consists of three paragraphs.
15 The first paragraph describes the outcome of the D3 16 assessment. This paragraph requires that applicants 17 demonstrate the adequacy of any design techniques, 18 prevention measures, or mitigation measures other than 19 diversity.
20 This paragraph also requires that the level 21 of technical justification for demonstrating the 22 adequacy of these measures or techniques other than 23 diversity be commensurate with the risk significance 24 of each postulated CCF.
25
23 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 The second paragraph meets the intent of 1
the current Point 3. This paragraph specifies that 2
a diverse means is acceptable to address the postulated 3
CCF.
4 This paragraph also specifies that 5
automatic or manual actuation within an acceptable 6
timeframe is an acceptable means of diverse actuation.
7 I would note that BTP-7-019 Revision 8 provides the 8
Staff guidance for determining if automatic and manual 9
actuations can be performed within an acceptable 10 timeframe.
11 MEMBER BROWN: Okay, I've got a question.
12 Have you accepted other circumstances in the older 13 plans where automatic, where manual actuation is an 14 acceptable diverse actuation method, explicitly 15 accepted it?
16 MR. ALFERINK: I would defer to Samir or 17 Norbert on that one.
18 MR. CARTE: Norbert Carte, I&C. Even in 19 newer plants we've done that so on the digital upgrade 20 for Oconee, basically only two of the functions had 21 a diverse actuation systems high pressure, low pressure 22 safety injection.
23 The other functions were deemed to have 24 enough time to do it manually. Oconee actually 25
24 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 believed they had enough time to do all but one. There 1
was a disagreement about that and we sort of forced 2
them to put in two rather than just one.
3 But they concluded they only need diverse 4
actuation for one. We concluded they needed it for 5
two and we, and they put in for two, but not all safety 6
functions.
7 MEMBER BROWN: What were the two again?
8 MR. ALFERINK: High pressure and low 9
pressure safety injection.
10 MEMBER BROWN: Okay, what about reactor 11 trip?
12 MR. CARTE: So they already have an ATWS 13 system or they already met the ATWS requirements so 14 we didn't impose anything additional for reactive trip.
15 And I see Dinesh has his hand up.
16 MR. TANEJA: Yes, Member Brown. The ABWR 17 design certification that we certified back in mid-90s, 18 the SECY-93-087's origination is really, you know, 19 connected to the review of that design cert application 20 from GE at that time.
21 And when we look at the certified design, 22 this concern was raised, the CCF concern and the 23 solution where we accepted was the worse manual 24 actuation of high pressure injection and low pressure 25
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 injection and the analog display indications of level 1
reactor vessel level for initiating those two functions 2
manually as diverse means.
3 The reactor trip scram function was already 4
available in a manual scram. So those manual actions, 5
you know, as diverse means were what we accepted to 6
satisfy the CCF concern for the ABWR design.
7 And, you know, the SECY paper was really 8
written too in connection with our review of the ABWR 9
design cert application because it was all digital at 10 that time.
11 MEMBER BROWN: You mentioned the Oconee 12 application. You all approved that just as I arrived 13 in 2008 so early '09. We never reviewed that that I 14 know of. I'm not aware of the Committee reviewing that 15 design approach.
16 Go ahead, that one was a little puzzling 17 to me. It just appeared. When I first got here all 18 of a sudden it was approved. So that detail is lost 19 on us somewhat so the memory bank is pretty well drained 20 on that one. All right.
21 MEMBER HALNON: Charlie, I had a question.
22 MEMBER BROWN: Oh, go ahead, Greg.
23 MEMBER HALNON: Yes, this is Greg Halnon.
24 Just to kind of explore this manual a little bit 25
26 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 further. To be acceptable, what is the pedigree behind 1
a manual actuation?
2 There's five parts to a manual actuation 3
when there's a failure detection diagnosis procedure 4
that procedure determination actions and then 5
verification the action taken is, was supposed.
6 So I guess the question is with the 7
training, the knowledge and abilities procedural 8
perspective, what are you looking for to make sure that 9
would be an acceptable --
10 MR. CARTE: Well --
11 MEMBER HALNON: -- means?
12 MR. CARTE: -- so first of all, 603 and 13 279 basically require that for every automatic 14 actuation there's a manual means to do it. Initiate 15 at the system or division level and that needs to be 16 safety related.
17 There are also associated requirements for 18 the display of information association with manual 19 actions. So in terms of equipment design, the I&C 20 review is to ensure the equipment has the capability.
21 The human factors folks review 22 implementation operator training and that sort of thing 23 and I'm less familiar with that.
24 MEMBER HALNON: Okay. All right, the 25
27 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 reason I ask is acceptable timeframe is certainly part 1
of it. But there's also that first part which the 2
pre-emptive should be able to diagnose and detect and 3
determine what you're going to be doing both procedure 4
out, make sure you're doing it by procedure then verify.
5 So I was wondering if there was anything 6
in your thought process behind this allowing a manual 7
actuation beyond just the acceptable timeframe.
8 MR. CARTE: Well so, we generally use the 9
human factors people to evaluate operator responses 10 associated with the D3 analysis. So in terms of the 11 regulatory requirements and that says the means shall 12 be there, whether the, there's sufficient time to do 13 it, to meet the diversity in defense and depth analysis, 14 is a D3 criteria and generally we involve the human 15 factors people to do that review.
16 MEMBER HALNON: Okay. And that would 17 probably be expected to be a deep dive into the training 18 and the abilities of the operator and so forth, so forth.
19 Is that what you're saying?
20 MR. CARTE: Yes, I can't speak much to what 21 they do.
22 MEMBER HALNON: Okay.
23 MR. DARBALI: Yes, this is Samir. And I 24 believe that for the Oconee example, it was determined 25
28 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 in the D3 assessment that those two functions would 1
not be performed in a timely manner. And thus, a 2
diverse actuation system was needed.
3 MEMBER HALNON: Okay. So that just shows 4
that there is a deeper dive somewhere else in the review 5
process.
6 MR. CARTE: Right and in Oconee, it wasn't 7
strictly analysis. They did do some tests with 8
operators in the simulator to support that they could 9
perform the actions.
10 MEMBER HALNON: Okay. That's what I was 11 looking for to see, you know, make sure we were just 12 outside of these words and to some other assessment 13 or inspection or whatever the case may be to ensure 14 that the human factors piece was still there. Thank 15 you. That's it.
16 MEMBER BROWN: I've got a note. Norbert, 17 you quoted 603,19-091, about the requirements, but 18 if you look at the new rule making that's disappeared.
19 So that stuff is not in there explicitly anymore.
20 It's all off in guidance if it's there anywhere.
21 MR. CARTE: New rule, you mean Part --
22 MEMBER BROWN: Part 53.
23 MR. CARTE: Part 53. Okay, I'm less 24 familiar with Part 53 maybe someone can chime in if 25
29 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 I'm wrong, but my understanding is mostly the difference 1
between Part 50, 52 and 53 is that there are different 2
processes and the technical criteria are predominantly 3
in Part 50.
4 So I'm not sure to how much extent Part 5
53 invokes Part 50 technical criteria. But that's the 6
7 MEMBER BROWN: It just --
8 MR. CARTE: -- my general idea.
9 MEMBER BROWN: -- it depends on which 10 framework you're in if I'm not mistaken. Dave, isn't 11 that correct? Or if the, you got the Part Frame B, 12 Frame A and Framework A and B? Framework A is, is that 13 the risk-informed one?
14 CHAIRMAN REMPE: No, it's --
15 MEMBER BROWN: And B is the more 16 traditional.
17 MR. CARTE: Well okay, the other part is.
18 One, this doesn't apply to 53 and two, 53 isn't done 19 so it's a little bit, three, I'm not involved in it 20 so I, it's a little hard to speculate on that.
21 MEMBER BROWN: Yes. One of the next 22 questions is when we talk about manual means, to me 23 manual means are very explicit. I turn a switch, 24 there's a wire going somewhere, operates a circuit 25
30 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 breaker or relay starts a motor, closes a valve, does 1
whatever.
2 In other words, there is no intermediate 3
computer-based system like somebody's touching a touch 4
screen that's says close. And you're depending on 5
another computer system to then process that data and 6
then get it down in trip something else or the same 7
thing that would have been tripped otherwise.
8 It pretty much when you get to the new 9
technology approaches to doing that in terms of what 10 is an acceptable manual means? Does that mean totally 11 divorced from computers or software? Is that clear 12 anywhere or is that you're envisioning it, but it's 13 not stated?
14 MR.
CARTE:
I think there's some 15 flexibility there. And --
16 MEMBER BROWN: That's what I was afraid 17 of.
18 MR. CARTE: We have a Reg Guide 1.62 that 19 discusses that, but I believe that manual means could 20 use safety related display systems to implement the 21 manual actuation.
22 If you look at the current plant designs, 23 there's various levels of independence that the, that 24 a manual switches have. So I believe on combustion 25
31 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 engineering designs the manual switches are just 1
equivalent to a bi-stable input to the voting logic, 2
but then it's relay voting.
3 So when you replace the relay voting system 4
with a digital system, you put your switches into that 5
digital system. That hasn't been decided yet because 6
no one has upgraded a combustion engineering protection 7
system yet.
8 Other facilities, the switches bypass some 9
of the voting logic and go directly to implementation 10 of the function. So it's a little bit design and 11 function specific how much independence the manual 12 switches have.
13 MEMBER BROWN: If I wanted to scram the 14 plant, I certainly wouldn't want to go through the 15 voting units. That doesn't make any sense. You ought 16 to go trip the scram breakers. Period.
17 Or if you wanted to start a pump, a fuel 18 pump if you need fuel systems or if you need some other 19 system, you ought to start the pump. It ought not be 20 voted on. Manual is manual.
21 You don't wait to see if you have two or 22 three or four of them in there. But that's subject 23 to another discussion. I'm just --
24 MR. CARTE: Well right. What gets into 25
32 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 that discussion is how complicated the function you're 1
implementing. So when you're implementing a reactor 2
trip, in effect, you're just moving two breakers.
3 If you're trying to do containment 4
isolation or diesel load sequences, you've got this 5
shed the bus, load the bus and how much independent 6
logic you have associated with the manual push button 7
as opposed to the automatic system.
8 Or they just both provided an input to the 9
diesel load sequencer. And then that diesel load 10 sequencer does what it does. So part of that, it gets 11 complicated depending on the complexity of the 12 implementation function. That's part of the problem.
13 MEMBER BROWN: You know, that's a little 14 bit more back in the other parts of the plant would 15 typically we have focused on the reactor protection 16 side and the engineered safety actuation feature side.
17 Not necessarily diesel generator 18 sequencing. All right, so --
19 MR. CARTE: All right.
20 MEMBER BROWN: -- as much as going to be 21 even more amorphous now. All right. I guess anybody 22 else have any other questions or -- okay, go ahead.
23 MR. ALFERINK: Thank you. So I'll pick 24 up with the third paragraph. The third paragraph 25
33 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 requires that a diverse means be provided if a 1
postulated CCF is risk significant and the D3 assessment 2
is unable to demonstrate that measures other than 3
diversity are adequate.
4 So this paragraph acts as a fallback 5
position. To summarize this Point 63, Point 3 allows 6
measures other than diverse means to be used with 7
appropriate justification.
8 If appropriate justification cannot be 9
provided, then diverse means must be used. Next slide 10 please. With respect to Point 3, the Staff has the 11 following expectations for a license member request.
12 First, the risk significance of postulated 13 CCFs will be determined by any increase in risk to the 14 facility using the traditional measures of increase 15 and core damage frequency or large early release 16 records.
17 Second, this increase in risk would be 18 determined using a quantitative bounding assessment.
19 Current experience is insufficient to establish 20 confidence and quantifying the probability of 21 occurrence of Digital I&C CCFs.
22
- However, current experience may be 23 sufficient to establish founding values that can be 24 used in a quantitative bounding assessment. The Staff 25
34 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 expects the applicants may have flexibility in 1
selecting a bounding value.
2 The choice of a bounding value may vary 3
from system to system depending on the design and it 4
could be less than 1.0 with justification. The Staff 5
has confidence that a bounding assessment can account 6
for the uncertainties in quantifying the probability 7
of occurrence of Digital I&C CCFs. Because --
8 MEMBER BROWN: Just a second.
9 MR. DARBALI: -- of the lack of --
10 MEMBER BROWN: Go ahead. I'll ask after 11 you're finished.
12 MR. DARBALI: Thank you. Because of the 13 lack of confidence and quantifying the probability of 14 occurrence of Digital I&C CCFs, the Staff will not be 15 able to approve risk-informed quantitative approaches 16 based on reducing the probability of occurrence of 17 Digital I&C CCFs through design techniques or for high 18 safety significance SSEs.
19 MEMBER BROWN: All this, all this 20 commentary that you make about your ability to assess, 21 trying to phrase this correctly, that really requires 22 at the design stage if it's a new plant, new application, 23 or a replacement even for back fit that you have a pretty 24 detailed architecture structure from which to make 25
35 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 these judgments.
1 Without that architecture, it's just 2
nothing that people say and what they're going to do 3
without one-line diagram showing the architecture and 4
why they can justify it seems to me somewhere you've 5
got to be expressing that.
6 I know right now it's been introduced in 7
7-019. It's also in the design and review design 8
specific review standards, the last two that have been 9
used. It's not in the SRP yet.
10 But it is in I think ISG-06, the licensing 11 approach that you do pre-licensing submittal. You 12 could argue that with the requirements you had before, 13 but once you go to the risk-informed approach, that 14 you need a more comprehensive architecture from which 15 to make these judgments as to whether they're approached 16 as okay or not. Am I misstating that or do you all 17 disagree?
18 MR. ALFERINK: I have a different way to 19 envision it from my perspective it would be a little 20 bit simpler approach. You don't need all the detail 21 drawings.
22 You just need to have an understanding for 23 what the system will do and how it can interact and 24 then choose a suitably large bounding value for your 25
36 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 risk assessment.
1 MEMBER BROWN: I didn't say detailed 2
drawings, but an architecture can be shown on a single 3
sheet of paper as we have done in all the last three 4
or four design certifications we've run.
5 That's -- those have been detailed enough 6
that you could make that judgment or it would enable 7
you to make that judgment.
8 MR. DARBALI: Though we would still expect 9
to see that level of detailing the architecture. When 10 we may not get to see or an alternate review process 11 application is the software side.
12 MEMBER BROWN: I got that. The 13 architectural protection from the software side if you 14 do it right partially protects you anyway. All right, 15 you can go ahead.
16 MEMBER MARCH-LEUBA: No, no.
17 MR. DARBALI: Yes --
18 MEMBER MARCH-LEUBA: Hold it. I was just 19 going say how --
20 MEMBER BROWN: Please go ahead.
21 MEMBER MARCH-LEUBA: Just to entertain 22 you. Explain to me, I'm having problem understanding 23 this slide. You, you're saying that we have to evaluate 24 the risk to the facility.
25
37 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 And typically risk to the facility is 1
determined as the CDF or the LERF or frequency of 2
something bad happening. And then on the last part 3
you say, but this time doesn't really believe the 4
probability of occurrence of CCF that you calculate 5
anyway.
6 So if we don't have any confidence on the 7
probability of this hidden factor, how do we have 8
confidence on the risk which is the product of that 9
and something?
10 MR. ALFERINK: The intent here is that we 11 will be able to pick a value that's large enough it 12 should encompass all the uncertainty. For example, 13 let's just pick a value, you know, 0.1 for the 14 probability of occurrence of the CCF.
15 I think everyone would likely agree that 16 would be a bounding number. Then we would not have 17 to go into the details to determine is it really 20 18 negative two, negative three, negative four.
19 If we agree that there's a suitably large 20 value then we can perform the risk assessment with that 21 and then not worry about the uncertainty in determining 22 the actual value.
23 MEMBER MARCH-LEUBA: So you can correlate 24 the increase in say callosity assuming a resolutely 25
38 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 high probability of occurrence of the CCF and then you 1
don't --
2 MR. CARTE: Issue the -- I wouldn't use 3
the phrase ridiculously high probability of occurrence.
4 So I would --
5 MEMBER MARCH-LEUBA: You said this in 6
Point 1.
7 MR. CARTE: Well no --
8 MEMBER BROWN:
Zero point one is 9
definitely --
10 MEMBER MARCH-LEUBA: A 10 percent chance 11 of, is a really critically high probability. I mean, 12 or you have a really bad design.
13 MR. CARTE: Well no, I was just looking 14 at a report out of the oil and gas industry yesterday, 15 today. And they were looking at CCFs of transmitters 16 and things like that.
17 And they came up with a range, their 18 estimate for realistic estimate of CCFs for their 19 redundant components was between.1 and.2. If.11 20 was the lowest CCF probability they had and Point 2 21 was the highest.
22 So their CCF range for 61-511,61-508 23 compliant facilities was between.1. That was the 24 realistic estimate. It was between.1 and.2. Now 25
39 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 that didn't include logic solvents.
1 That was just things like the damper, the 2
dampers we'll point to, but values, sensors, and things 3
like that. So between.1 and.2, was the basically 4
oil and gas industry standard for CCF.
5 Based on over 1,400 components analyzed 6
or failures analyzed.
7 MEMBER BROWN: This is a nuclear plant not 8
an oil and gas.
9 MR. CARTE: Right, but --
10 MEMBER BROWN: There's a big difference.
11 I mean you, we had one problem in the country. One 12 problem shut down the entire industry.
13 MR. CARTE: No, I get that, but we've also 14 just approved the commercial grade dedication process 15 where we use 61-508-03 certified components. So it's 16 the same components used in the oil and gas.
17 MEMBER BROWN: Yes, but if they're using 18 an architecture that's well defined, then you can 19 certainly get yourself better than.1.
20 MR. CARTE: Well, yes. Well okay --
21 MEMBER BROWN: That's my point.
22 MR. CARTE: So yes --
23 MEMBER BROWN: That's my point. Norbert, 24 that's my point. You keep nibbling this thing down 25
40 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 to ridiculously low numbers when the focus on all of 1
these safety systems and what we've done at least try 2
to bring ourselves through them has been to make sure 3
we could see that I could mentally and just 4
qualitatively if nothing else, that there's a pretty 5
low probability without going through a math hurricane 6
of some kind.
7 So I'm just, you can't compare oil and gas 8
to a nuclear power plant. If an oil and gas plant say 9
has a catastrophic failure, you're not going to shut 10 down all the, you'll build more.
11 If you do that with a nuclear power plant, 12 you won't build any more. We've already done that '79 13 until now. What is that? Thirty, 42 years, 43 years?
14 The consequences are different even if you, even if 15 they're nebulous.
16 I mean, they were, the consequences were 17 virtually nothing. Then you look what happened. You 18 just got to be careful of the way you throw the 19 comparisons around. That's all I'm saying.
20 The rest of the Committee members can speak 21 out, tell me I'm off the wall, but that's my --
22 MEMBER MARCH-LEUBA: My gut feeling when 23 you tell me 10 percent almost go failure is reasonable 24 and expected. And it's not even covering an abundant 25
41 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 case which is 11 percent. I said you'd better use 1
better components.
2 But going back to my original question 3
then, if I expected all the probability failure is 11 4
percent. What I'm bounding you should use at least 5
20, 25. And then --
6 MR. CARTE: Right, so --
7 MEMBER MARCH-LEUBA: What redundancy you 8
have? I mean, you, don't put two of them, just keep 9
only one. You're not getting anything in that empty 10 space.
11 MR. CARTE: Right. So basically we have 12 an established acceptance criteria yet, but they will 13 have, they would propose and justify a particular 14 bounding value.
15 But we expect it to be relatively large 16 rather than relatively small. It's kind of where we're 17 at today.
18 MEMBER MARCH-LEUBA: But it has to be 19 abundantly obvious to a reviewer familiar with the 20 subject that it is conservative.
21 MR. CARTE: Well --
22 MEMBER MARCH-LEUBA: It's easy when you 23 have thousands of components and you can look at the 24 statistics over the last ten years. We typically don't 25
42 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 have that luxury. Okay, I just put it on the record.
1 I see a little logic failure here when we're going 2
through implementation.
3 MEMBER BROWN: And I would, let me amplify 4
Jose's comment a little bit because our comment on the 5
commercial dedication, we made the point that whatever 6
components you picked in our letter back which you all 7
responded to and that those parts have to be compatible 8
with being incorporated into the architectures we use 9
for the fire plants and you all did that.
10 You did, you converted a few words into 11 regulatory sausage making, but it came out reading okay 12 because you effectively say you have to have an, you 13 have to know what your system looks like and that it 14 will comply with our requirements before you can use 15 the commercially dedicated component.
16 That was a good write up. So anyway, 17 that's our thoughts. Joy, I interrupted you I think.
18 CHAIRMAN REMPE: It's okay. This is a 19 very trivial question that I should have brought up 20 during the subcommittee meeting. But it will, may be 21 help in the future for me to understand something.
22 Why do you have in the SECY six times high 23 safety significance SSEs instead of significant? Is 24 there some reason for this or is it just a typo that 25
43 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 got repeated six times?
1 MR. DARBALI: I, we went through a lot of 2
wordsmithing and that is the term we agreed on.
3 CHAIRMAN REMPE: But what's the meaning?
4 Why do you say significance instead of significant 5
there? Why is that terminology important, that 6
distinction? Because it's really awkward and it gets 7
repeated in other places and I just am curious.
8 MR. DARBALI: I need to check what we said 9
in Branch Technical Position 7-019. Maybe we were 10 looking for consistency, but the intent was the same.
11 CHAIRMAN REMPE: Okay, so again, I can, 12 I get it will be repeated in the future here and I just, 13 it really is an awkward way of wording it and that's 14 why I'm asking that. Thank you.
15 MEMBER MARCH-LEUBA: But I thought you 16 were more concerned, I'm simply more concerned about 17 the modifier side whether you use significance or 18 significant.
19 CHAIRMAN REMPE: Well it doesn't make 20 sense to say significance to me.
21 MEMBER MARCH-LEUBA: Well what doesn't 22 make sense to me is high. High is in the eye of the 23 beholder. It's either a safety significant or it 24 isn't.
25
44 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 CHAIRMAN REMPE: I agree with you on that 1
too, but again I've seen this high safety significant 2
at other places so that didn't (audio interference).
3 Anyway, go ahead.
4 MEMBER DIMITRIJEVIC: Well this is Vesna.
5 This is a better terminology. I mean this comes from 6
the, you know, 50.69 that you defined the recent numbers 7
actually which define I mean there is a risk measures.
8 And the values of these measure define is 9
this kind or loss if it is significant component so.
10 You know, you remember these four quadrants. You know 11 12 CHAIRMAN REMPE: But Vesna, I get what the 13 50.69, but that's the high and the low, but didn't they 14 use significant with a "t" instead of --
15 MEMBER DIMITRIJEVIC: Well they use the 16 significance so that's a different in that.
17 CHAIRMAN REMPE: Yes.
18 MEMBER DIMITRIJEVIC: But I mean that this 19 is not a value we hold that is clear criteria for these 20 measures that I mean what is the high significance based 21 on this contributing factor or factor vastly so.
22 MEMBER BROWN: There, I can help you out.
23 I just looked at BTP-7-019 and there's a section in 24 there that says acceptance of safety significance 25
45 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 determinations, the following criteria applies.
1 High safety significance or safety related 2
SSEs are performed safety significant functions, work 3
on that one for a few minutes. SSCs in this category 4
have one or more of the following characteristics.
5 And then there are three bullets that 6
follow up. They're credited in the FSAR to perform 7
design functions that contribute significantly to plant 8
safety.
9 They're relied upon to initiate and 10 complete control actions essential to maintaining plant 11 perimeters within acceptable limits established for 12 a DBE or to maintain a plant in a safe state after it 13 reach safe shutdown or their failure to directly lead 14 to accident conditions that may have unacceptable 15 consequences exceeding site doses limits of the DBE.
16 So it is defined somewhere as to what a 17 high safety significance is in one of the BTPs. I'm 18 glad I looked it up. I had totally forgotten that.
19 CHAIRMAN REMPE: So basically we're 20 repeating some bad grammar from the PT meetings that 21 we've --
22 MEMBER BROWN: I, if this is Rev 8, this 23 was reviewed in 2021.
24 CHAIRMAN REMPE: Okay.
25
46 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 MEMBER BROWN: And it was in the last 1
revision so we are compatriots in messing with something 2
that's vague.
3 MR. CARTE: Norbert Carte, I&C. There's 4
also another dimension about whether you're talking 5
about a binary perimeter or some sort of continuous 6
so if we say commensurate with safety significance, 7
that gives you, the flexibility to have a more grated 8
scale.
9 If it's safety significant or not it's a 10 binary scale. And to be risk informed, we sort of need 11 a graded scale, not just a binary scale or we want a 12 graded scale and that could also be part of what, when 13 any of those discussions, although I don't remember 14 them right now.
15 MEMBER BROWN: Well, I'll tell you some 16 more. Right after the high significance safety, 17 there's another B as lower safety significance then 18 they define safety related SSCs that is some other lower 19 safety.
20 And then there's a C which is lower, I just, 21 worst lowest safety significance so we've got high, 22 lower and lowest. They are defined at least in the 23 branch technical position whether those have meaning 24 for if not there is something, there is a basis for 25
47 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 saying what those mean.
1 And there is a gradation. It's almost like 2
the graded approach type thought process based on what 3
Norbert just said. You can argue --
4 MEMBER DIMITRIJEVIC: So --
5 MEMBER BROWN: -- what the, where the 6
defining lines are between those is, could be 7
interesting. Go ahead, Vesna. I'm sorry.
8 MEMBER DIMITRIJEVIC: No, that's all 9
right. I just want to say, is the, how that's defined 10 it's not resistant which is actually risk-informed 11 content that you approaches as they exist, you know, 12 in that couldn't practices.
13 That's something new. I mean and 14 obviously this great a preductal with something new 15 and defined here so. I mean, you know, here the 16 presenters are true risk-informed content of approach 17 that those, you know, the risk-informed content that 18 the project as defined in Reg. Guide 1174.
19 Or you know, this inform ranking is 20 improving the 10-65-5069 at different than what Charlie 21 just said.
22 MEMBER BROWN: Any other questions or 23 comments? Samir? Take the spear out of your chest 24 and you can proceed.
25
48 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 MR. DARBALI: Steven are you on, still on 1
Slide 15 or are you done?
2 MR. ALFERINK: I have finished Slide 15.
3 I was going to turn it back to you.
4 MR. DARBALI: Okay, thank you. We are now 5
on Slide 16 to talk about Point 4. So Point 4 of 6
SECY-22-076 maintains the intent from SRM SECY-93-07 7
regarding the need for independent and diverse manual 8
control room displays and controls for the plant's 9
critical safety functions.
10 These diverse displays and controls may 11 be credited to meet Point 3 and that was part of the 12 discussion before on the manual controls. Point 4 is 13 essential in the Staff's ability to conclude with 14 reasonable assurance that a proposed Digital I&C design 15 does not adversely affect an operator's ability to 16 manually control critical safety functions.
17 The Staff's position is that Digital I&C 18 systems should not be able to take control of the 19 facility away from the operator under all plant 20 conditions whether they be anticipated or unanticipated 21 plant conditions.
22 Point 4 is consistent with the application 23 of existing regulatory requirements for the 24 independence that are incorporated into the regulation.
25
49 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 Point 4 already incorporates an explicit 1
element of risk informing as it is only applicable to 2
critical safety functions and does not require the 3
diverse displays and manual controls to be safety grade 4
or hard wired.
5 MEMBER BROWN: What's GDC 22 again? I 6
forgot. Does anybody remember?
7 MEMBER MARCH-LEUBA: You're very far away 8
from the microphone. It's hard to hear?
9 MEMBER BROWN: Oh, what's GDC 22?
10 MR. DARBALI: Remember you got that on top 11 of your head right now?
12 MR.
CARTE:
- Yes, reliability and 13 testability I think.
14 MEMBER BROWN: And --
15 MR. CARTE: It has that statement about 16 design technique such as diversity so you'd be used 17 to the extent practical.
18 MEMBER BROWN: Okay.
19 MR. CARTE: To prevent loss of tech 20 disfunction. That's the last sentence of the --
21 MEMBER BROWN: Okay, 50.55a(h) has got 22 603-1991 in it. Right?
23 MR. CARTE: Yes.
24 MEMBER BROWN: If I remember correctly.
25
50 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 That's the architecture is in the principles of design, 1
et cetera. Okay, all right. Thank you.
2 MR. DARBALI: And now on Slide 18, so this 3
graphic is intended to depict the risk-informed scope 4
of Point 4 which is shown in the green shaded area.
5 As you can see, Point 4 is only applicable to those 6
critical safety functions performed by the digital 7
system.
8 Point 4 is not applicable to all of the 9
critical safety functions performed by the system, only 10 those that are those critical safety functions 11 performed by the system and it's all, Point 4 is also 12 not applicable to critical safety functions that are 13 not performed by the Digital I&C system.
14 In other words, critical safety functions 15 aren't performed by various systems in the plants where 16 only focusing on the scope of the modification. Again, 17 we recognize that the critical safety functions listed 18 in the SECY and BTP-719 may not be the appropriate set 19 for all reactor designs.
20 And the SECY does provide for the use of 21 existing regulatory tools like extensions and 22 alternatives to accommodate the signs with different 23 critical safety functions, any of the Staff unconscious 24 or reactor design where the policy would not be 25
51 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 applicable, the Staff would engage the Commission as 1
appropriate.
2 MEMBER MARCH-LEUBA: This is Jose, can you 3
give me an example so I can think of it of a safety 4
function where it will be good in your mind of the 5
digital system locks the operator and lesson lender 6
breakthrough in at all which is what No. 34 is. Right?
7 I mean, is a classic idea of you flying 8
a plane and the auto pilot is fighting you, your 9
joystick. Pulling up his point. Give me a safety 10 function with locking my joystick would be reasonable.
11 MR. DARBALI: And we can't think of one.
12 MEMBER MARCH-LEUBA: Me neither.
13 MR. DARBALI: Right, so and maybe that left 14 side of the box that says plant safety, you know, let 15 me --
16 MR. MARCH-LEUBA: It should, the left side 17 of the box should be an empty set.
18 MR. DARBALI: Right.
19 MR. MARCH-LEUBA: Even if no set.
20 MR. DARBALI: Right. A safety system is 21 going to have various levels, it's going to perform 22 a lot of functions and some are considered critical 23 safety functions.
24 Those are the ones like you said, you don't 25
52 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 want your pilot to not have control of the plane. So 1
those are the ones that we are focusing on. If the 2
safety system performs other functions that because 3
they can be mitigated in some other way or they have 4
some, there are some preventive measures or the risk 5
of that function is not considered risk significant 6
than they would fall outside of those critical safety 7
functions.
8 MEMBER MARCH-LEUBA: Yes, let me give you 9
an example to focus many, if I'm driving one of these 10 modern cars and a cab breaks in front of me very 11 suddenly, that should release the brakes for me which 12 is good.
13 I mean it's a, the whole system takes 14 control of my action, but if I want to brake more, I 15 can. I can and then the moment you touch the brake, 16 the safety function disconnects itself and then you 17 can release the brake.
18 You just have to skid into -- anyway, I 19 think I said enough. I don't see the point of having 20 this caveat. I would, I don't see it would be applied 21 anywhere.
22 MR. DARBALI: Which caveat specifically?
23 MEMBER MARCH-LEUBA: The plant safety 24 functions not counting where the control system can 25
53 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 take control from the operator and won't allow the 1
operator override it.
2 MR. DARBALI: But is that a comment 3
specific to the language in Point 4?
4 MEMBER MARCH-LEUBA: No, it's a comment 5
on your slide.
6 MR. DARBALI: Okay, understood. It may 7
not have been clear. Okay. Now on Slide 19. So Point 8
4 has not been an amphetamine to modern digital control 9
room designs.
10 For example, all recently approved designs 11 meet this Point 4 including the new scale control room 12 design and the AP-1000 control room design used at both 13 units 3 and 4.
14 Licensees that want to use risk information 15 to reduce the requirements for manual controls can 16 request an exception or an alternative and the Staff 17 would inform the Commission before approving or denying 18 such exceptions and alternative.
19 The Staff has had several meetings with 20 stakeholders to better understand their perspectives 21 and believes that industry's concerns can be adequately 22 addressed in implementing guidance.
23 MEMBER BROWN: What does that mean? Go 24 so high tech that it would blow your brains out? Touch 25
54 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 screens, all kinds of good stuff like that, eliminate 1
all the switches, nothing but glass and -- it seems 2
to me you got to be careful about how principles might 3
be bypassed when we go these paths. That's all. It's 4
the --
5 MR. DARBALI: Understood. And that's why 6
we, you know, that's the value we see in Point 4.
7 MEMBER BROWN: Let me ask you one other 8
associated question then. We've got Reg Guide 1.152 9
is coming in for a review by the subcommittee on the 10 17th of November.
11 And that's been extensively revised, but 12 it seems to me that is another one of the main players 13 relative to how you address what's being allowed by 14 the second.
15 Is that, I'm just about to start on that 16 so I do know it's been revised extensively along with 17 the ATP-7-19. Somehow this has got to be integrated 18 with the stuff we've got out there right now.
19 And it's a little bit difficult to see.
20 Are we going to have to revise 7-19 and ISG-6?
21 MR. DARBALI: So --
22 MEMBER BROWN: And then that design 23 specific review standards, et cetera, et cetera, et 24 cetera to be in compliance or to respect or to reflect 25
55 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 what's in this SECY?
1 MR. DARBALI: Right, so ISP-06 and the 2
design specific review standards point to currently 3
they point to SRM-SECY-93-087.
4 MEMBER BROWN: Yes.
5 MR. DARBALI: And so at least for ISO-06 6
its final resting place should be part, formalized as 7
part of the SRP so it eventually will not be an ISG 8
so and as we are performing a licensing reviews, we 9
are gathering lessons learned.
10 So eventually the contents of ISG-06 will 11 be updated and whatever comes out of the Commission 12 on this SECY and the implementing guidance would be 13 reflected in our licensing review guidance. Does that 14 15 MEMBER BROWN: Any other questions on this 16 slide?
17 MEMBER KIRCHNER: Yes, Charlie, this Walt.
18 MEMBER BROWN: Go ahead, Walt.
19 MEMBER KIRCHNER: Could you give us some 20 examples of what industry concerns might be? Are you 21 talking about new advanced non-LWR designs where the 22 BTP critical safety functions might be somewhat 23 different or what's the industry concern that we --
24 MR. DARBALI: So from our stakeholder 25
56 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 engagements, we've received feedback from the industry.
1 On the critical safety functions, I don't believe that 2
is a major aspect of Point 4.
3 I believe what industry is trying to say 4
is that if you're not crediting the manual actions in 5
Point 3, then you shouldn't be looking at Point 4.
6 What we've tried to explain is that Points 1 through 7
3 are intended to address the CCF.
8 How does the facility cope with the CCF.
9 So Point 1 and 2 you do your D3 Assessment. In Point 10 3, you identify ways of addressing that postulated CCF.
11 Point 4 has a different safety concern 12 which is to allow the operators to be able to perform 13 the manual actions. And that's why it requires the 14 displacing controls and many of the controls to be 15 diverse from your system so that your CCF doesn't take 16 out, your CCF doesn't take out both your system and 17 your manual controls for those critical safety 18 functions.
19 I believe industry's argument is that the 20 quality of new digital systems is very high and the 21 reliability is very high where you would not consider, 22 you would not even consider that CCF and you would not 23 need to have the need for the operator to have manual 24 controls.
25
57 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 Also, I believe the future that some in 1
industry are envisioning is a, what we call a glass 2
control room. Everything is a flat panel display run 3
by the same software and so that would not need Point 4
- 4.
5 And so we think that you can have a control 6
room made out of flat panel displays, but you're going 7
to have to run those manual (audio interference) diverse 8
software for those controls or whether they be 9
hardwired.
10 But they have to be, our position is they 11 have to be diverse from your safety system.
12 MEMBER KIRCHNER: Okay, that's good.
13 What you're saying, it doesn't leap out of the language 14 to me.
15 MR. DARBALI: Okay.
16 MEMBER KIRCHNER: I'm very encouraged by 17 what you just said, but I can imagine certainly with 18 some of the new advanced designs, their thinking is 19 probably that scenario you just played out where it's 20 entirely glass.
21 It would be important to, it goes back to 22 Charlie's point about architecture. Make it very clear 23 that you can go that route, but you would actually have 24 two different systems in the control room and they 25
58 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 wouldn't share any comments off of their site to achieve 1
those critical safety functions. And --
2 MEMBER HALNON: This is Greg Halnon.
3 MEMBER KIRCHNER: -- and that would be --
4 MEMBER HALNON: You wouldn't necessarily 5
be in the control room if you had adequate time to get 6
to a remote location and actuate them. Correct?
7 MEMBER KIRCHNER: Well yes, that's 8
probably predates Digital I&C. That's my --
9 MEMBER HALNON: Well --
10 MEMBER KIRCHNER: -- experience where you 11 had a, yes, a separate analog system for the shutdown 12 function.
13 MEMBER HALNON: Well I'm just saying you 14 had to actuate a pump, you can go locally and turn the 15 pump on if you had adequate time to meet that we talked 16 about earlier as far as manual actuation.
17 Also, there's some requirements prior 18 protection that have diverse ability to operate outside 19 the control room as well. So there's some synergies 20 there that will probably be built on.
21 MEMBER KIRCHNER: My point, Charlie is 22 that what was just said by the Staff makes eminent good 23 sense, but it doesn't leap out of the language to me.
24 But --
25
59 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 MEMBER BROWN: It's varied.
1 MEMBER KIRCHNER: -- because, yes.
2 MEMBER BROWN: The whole thing when you're 3
running down that path, they have to have the ability 4
to say no. And that's --
5 MEMBER KIRCHNER: Yes.
6 MEMBER BROWN: -- my biggest concern for 7
all of this when you introduce this risk-informed 8
approach to how you, you know, diverse and nondiverse 9
or whatever.
10 You now, you have to prove the opposite.
11 They can come in and say this is what we want to do 12 and it's so good that we'll never have a problem. And 13 then you have to prove the negative for the Staff to, 14 I mean you could apply that to the entire application 15 of risk-informed approaches or the entire parts of the 16 plant which they're already going and doing.
17 So now this is one of the logical extensions 18 that they're nibbling down to the grass roots and now 19 it's down to the instrumentation control systems where 20 people are turning switches and doing various things 21 like that as opposed to the more of the other.
22 I'm still trying to figure out how risk 23 informed the operation of an amplifier. You know, it 24 either it trips or it doesn't trip. You know, if it's 25
60 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 a vice saver.
1 It, you risk inform the parts, but you don't 2
buy such good parts and make them out of cruddy parts.
3 It's an interest conundrum to have to deal with.
4 I think as a Committee, this is just an 5
opinion that it would be difficult for us to walk through 6
seeing something that didn't have adequate manual 7
backup regardless of the circumstances under which it 8
was being said to be needed.
9 That's just kind of a hard spot and from 10 personal experience, I can, and very personal 11 experience. If it hadn't been for manual backup, it 12 would have been some severe consequences.
13 MEMBER HALNON: This is Greg. A question 14 again back I guess, Samir. You mentioned that the 15 digital systems are hard quality and, you know, the 16 industry's saying that the uncommon causes shouldn't 17 even have to be considered.
18 Doesn't that get flushed out in the D3 19 assessment early on to where you wouldn't have to 20 consider them if the quality and frequency and, you 21 know, probability of these things having a common cause 22 failure is so far out there we don't have to worry about 23 it?
24 MR. DARBALI: Yes, I think that's part of 25
61 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 what Steven was talking about. But again, the point 1
of Points 1, 2 and 3 is exactly that. How do you cope 2
with the loss of the safety function because of a CCF 3
whereas the intent of Point 4 is you want to ensure 4
that your operator has the ability to perform those 5
manual actions and so that, and that a CCF doesn't take 6
out those, that ability.
7 It's more about maintaining that function.
8 We're not at a point yet where we feel comfortable 9
saying, yes, you can say that your CCF is unlikely so 10 you don't need to do any diversity for your digital 11 system and also you don't need to do anything to ensure 12 operators have the means to perform manual actions.
13 MEMBER HALNON: Okay. Do you see us ever 14 getting there? I mean, how do we credit the better 15 quality of electronics and digital systems? It had, 16 if it doesn't matter, then you have to consider every 17 CCF possible. But what is the risk-informed pieces?
18 MR.
DARBALI:
Well
- again, the 19 risk-informed piece is for, again, for your Point 3 20 which includes critical safety functions and 21 non-critical safety functions.
22 That's where you get the advantage of the 23 risk-informed approaches. And you know, even for 24 critical safety functions licensees can determine how 25
62 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 they want to meet Point 3.
1 But for those critical safety functions, 2
Point 4 needs to ensure that those diverse, that those 3
controls and displays are independent and diverse.
4 So I agree, you know, when you think about it, you know, 5
where do you get that benefit?
6 It's more likely on those functions 7
performed on the system that are not critical safety 8
functions.
9 MEMBER HALNON: Okay, thanks.
10 MR. BENNER: Even more, those functions, 11 you can use the risk information to not need adapts 12 diverse actuation systems.
13 MR. DARBALI: Right.
14 MR. BENNER: So you know there are elements 15 of where the risk informing plays out, but I think it 16 does go back to for these functions deemed to be the 17 most critical safety functions the Staff's current 18 position is that a CCF shouldn't lock the ability of 19 the manual -- of the operators to take manual control 20 of those actions.
21 Now for a single failure. Right? The 22 code, the standards do require, you know, the manual 23 capability. But that manual capability that can't be, 24 shouldn't be able to be taken out by a single failure.
25
63 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 But it could be taken out by a common cause 1
failure and that's why the, you know, the policy and 2
the standards were in concert with one another.
3 MR. DARBALI: Thank you, Eric.
4 MEMBER BROWN: The complications with CCFs 5
software is wide range. This software that's been 6
software based systems that we've seen has lots and 7
lots and lots and lots of the compliance code for one.
8 I mean you're talking hundreds of thousands 9
of lines of code. And they are interrupt driven and 10 the interrupts are there to do things that the vendor 11 that designs the software he's trying to accomplish 12 to approve something is okay or not okay as it goes 13 through.
14 If you're trying to execute a safety 15 function and it all of a sudden gets interrupted, that's 16 a problem. If the interrupt doesn't come back ask them.
17 If it doesn't, you know, go back to where it was, that's 18 a problem.
19 And it gets very, very complicated to prove 20 that without having, you try to compensate for that 21 by, you know, typically due to corrupt data of some 22 kind that stops and wants to stop something.
23 You have a synchronous performance so that 24 none of the channels are operating in the same sync.
25
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(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 You have different detectors for everything so it's 1
the same data that might be corrupt doesn't get to all 2
of them because it's just sensors never ever read the 3
same thing for all of them.
4 There is a lot of ways you can try to justify 5
that, but you can't prove any of it. But there's just, 6
they're feel goods that makes your stomach not turn 7
over.
8 Non-interrupt driven systems are more 9
predictable. That's where you process everything in 10 a straight line. You never deviate and then you come 11 back and start over again with a new set of data.
12 That's for each process, for each channel.
13 These systems we've seen are not like that. The FPGA 14 ones are a little bit closer. They're like an analog 15 computer. You reprogram it and it's there.
16 You can have it individual keys fail 17 inside, but it's unlikely to have it fail in the other 18 one. And I would buy in on that. I don't know whether 19 I'm right or wrong, but I would buy in on that. That's, 20 we've accepted that.
21 So there's a lot of stuff that goes into 22 trying to figure out what is a CCF in a computer-based 23 system. So that's my speech for this part. Never pass 24 up an opportunity.
25
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(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 MR. CARTE: Norbert Carte, I&C. So 1
there's something very interesting in your speech, 2
Charlie. So what we're really talking about is --
3 MEMBER BROWN: You going to tell me I'm 4
wrong?
5 MR. CARTE: No. I'm going to tell you 6
you're right. What we're really taking about is 7
reliability of the I&C system. And a lot of these 8
peripheral discussions have been about the adequacy 9
of the control room design.
10 So these criteria aren't really a back door 11 or control room design requirements. And they're not 12 necessary and sufficient for control room design. What 13 we're really aiming for is the reliability of the I&C 14 equipment and for the points you mentioned it's in some 15 cases it may be possible to show that your manual 16 controls don't need to be independent or diverse.
17 But in reality, it's more efficient and 18 effective to have simple independent diverse manual 19 controls. Although we allow this policy allows some 20 flexibility, but this is more about equipment 21 reliability.
22 The equipment being able to perform a 23 safety function when needed rather than on appropriate 24 criteria for a control room design. Because obviously 25
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(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 this isn't enough for a control room design.
1 And you have to think balance what the 2
non-safety system does and what the safety system does 3
and it's a control systems design problem, control room 4
design problem not an I&C equipment design problem.
5 We just want to make sure the equipment 6
is reliable and that's what Point 4 is about. And it's 7
not about the control room design.
8 MEMBER BROWN: Yes, Norbert, but also the 9
architecture and the backup manuals all contribute to 10 that reliability. That's a fundamental piece of that 11 control room design for liability.
12 That's in my mind. Any other comments from 13 the Members? You want to go on to the next slide 14 whichever one that is, 20?
15 MR. DARBALI: Yes, so Slide 20 are the key 16 messages that we presented back on Slide 6 so I won't 17 repeat them here. And Slide 21 is our next steps.
18 If the Commission approves the recommended expanded 19 policy our next steps are to update the existing 20 implementation guidance.
21 BTP-7-019 is one of the guidance documents 22 we're considering for updating. And also to continue 23 to engage stakeholders and the pubic to seek comments 24 on our implementation.
25
67 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 MEMBER BROWN: Why not 1.52 and 1.62, I 1
think it's, did I get that other number right? I've 2
forgotten what 62 is.
3 MR. CARTE: Yes, it's 1.152 and 1.62.
4 MEMBER BROWN: Yes, those are the 5
computer, kind of the computer based Reg Guides.
6 MR. CARTE: 1.62 is the manual controls 7
Reg Guide.
8 MEMBER BROWN: Yes, okay, got it. All 9
right, thank you. And 1.152 is the general application 10 of computer systems.
11 MR. CARTE: It's design criteria to 12 augment and supplement 603.
13 MEMBER BROWN: Yes. Which we're going to 14 work on some more. Okay, so if you go forward with 15 1.152 and with this current revision you're working 16 on, you're going to have to do that again if this thing 17 gets accepted by the Commission. Is that correct?
18 So you're going to do it twice?
19 MR. DARBALI: Well --
20 MEMBER BROWN: I'm asking you, my question 21 is why are you doing 1.152 before you know where this 22 Commission's going to do, what they're going to do with 23 this.
24 MR. NGUYEN: Yes, Charlie. This is Khoi 25
68 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 Nguyen. I'm the one who prepared Reg Guide 1.052 which 1
is the deterministic guidance.
2 MEMBER BROWN: Yes.
3 MR. NGUYEN: And it's for common cause 4
failure we clarify the endorsement with the reference 5
to BTP-7-19. So I don't think 1.52 necessary to revise 6
to reflect the new SECY paper, but BTP-7-19 should be.
7 MEMBER BROWN: Yes, I noticed that. I 8
took a quick look at it and I noticed it was, some 9
references. There were some other good stuff in it.
10 There was some other not so good stuff in it. But 11 we'll deal with that on the 17th.
12 MR. NGUYEN: Thank you.
13 MEMBER BROWN: All right. Any other 14 comments from the Committee Members?
15 MR. DARBALI: That's our presentation so 16 thank you for the comments and are open to answer any 17 other questions.
18 MEMBER BROWN: No more questions, Joy, 19 I'll turn it back over to you.
20 CHAIRMAN REMPE: I think we need to ask 21 if any members of the public --
22 MEMBER BROWN: Oh.
23 CHAIRMAN REMPE: -- would like to make a 24 comment.
25
69 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 MEMBER BROWN: Well that's a good point.
1 Thank you. We finished our part of the meeting. Is 2
there anybody, members of the public who would like 3
to make some comments on this presentation?
4 MR. DARBALI: I see Alan --
5 CHAIRMAN REMPE: I see a hand -- whoever's 6
got their hand up, you're welcome to unmute themselves 7
and speak. Alan Campbell.
8 MR. CAMPBELL: Hi, good afternoon this is 9
Alan Campbell with NEI. So I'll keep my comments brief 10 here. But NEI would like to thank the NRC for hearing 11 the industry needs to allow risk insights to be applied 12 to Digital I&C design and the licensing activities as 13 it's been applied in other technical areas.
14 We truly appreciate the engagement and the 15 urgency in which the NRC Staff has responded. NEI and 16 our members believe that Points 1 through 3 provide 17 the policy Staff change needed to allow risk insights 18 to be considered.
19 And we're looking forward to future 20 implementation guidance that further clarifies the 21 application of these principles. We also believe that 22 Point 4 remains overly prescriptive both in the scope 23 and location requirements.
24 We fully agree with the Staff that manual 25
70 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 actions credited with responding to a CCF concurrent 1
with a design basis event should not be subject to the 2
same CCF.
3 However, to maintain the principle of 4
simplicity and design, the scope of those manual actions 5
should be driven by plant or application specific 6
analysis not prescriptive policy requirements.
7 We believe the results of the CCF coping 8
and D3 analyses provide reasonable assurance of 9
adequate protection while responding to this beyond 10 design basis event.
11 Additionally, existing human factors 12 engineering approaches described in SRP Chapter 18 13 Appendix Alpha to that SRP Chapter and the associated 14 New Regs provide adequate guidance for specific 15 features including the location requirements for these 16 credited manual actions.
17 So again, thank you to both the NRC Staff 18 and the ACRS full Committee and we ask that the ACRS 19 full Committee consider these requirements while 20 deliberating your action. Thank you.
21 CHAIRMAN REMPE: Thank you.
22 MEMBER BROWN: Is there anybody else that 23 would like to make a comment? Excuse me. Is there 24 anybody else on that would like to make a comment?
25
71 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 Hearing no response, back to you, Joy, now.
1 CHAIRMAN REMPE: Thank you.
2 MEMBER BROWN: Thank you for reminding me.
3 CHAIRMAN REMPE: No problem. Okay, I know 4
you have a letter that you'd like to read in and so 5
at this point, I'd like the Court Reporter, I'd like 6
to go off the record and invite the Court Reporter to 7
return at 3:45 p.m. East Coast Time and then, thank 8
you.
9 (Whereupon, the above-entitled matter 10 went off the record at 2:26 p.m. and resumed at 11 3:45 p.m.)
12 CHAIRMAN REMPE: Okay, it's 3:45 p.m. and 13 we're back in session. And at this time, I'd like to 14 ask (audio interference).
15 MEMBER MARCH-LEUBA: Thank you, Ms.
16 Chairman. We're going to be talking about Reg Guide 17 1.82 which deals with sources of water for SECS and 18 other safety functions after LOCAs.
19 And at this point, I'd like to give the 20 floor to the Staff. I believe Jim, you're going to 21 make a presentation, an introduction?
22 MR. STRECKEL: Yes. Can you hear us okay?
23 MEMBER MARCH-LEUBA: Yes, we can.
24 MR. STRECKEL: Okay, good. Yes, I'll just 25
72 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 do a real brief introduction and turn it over to the 1
technical staff to do the body of the presentation.
2 So let me introduce myself. My name is Jim Steckel.
3 I'm a Program Manager in the office of 4
Research, Division of Engineering and our branch does 5
all of the work or of the PM work, the project management 6
work on the regulatory guide system.
7 I'm also here with Ahsan Salman, he's the 8
Senior Nuclear Engineer in NRR Division of Safety 9
Systems. He'll be talking later on Appendix B of this 10 Reg Guide Revision and also Steve Smith, Senior Plant 11 Systems Engineer.
12 He is also in NRR's Division of Safety 13 Systems. Today we'll present in summary fashion the 14 main changes to Rev 5 of Reg Guide 1.82. These updates 15 will be discussed by the Technical leads and will 16 include the following: a) GSI-191, this issue 17 constitutes the main body of the Reg Guide and Appendix 18 A.
19 And included in this will be Reg Guide 1.82 20 Rev 5 status with respect to GSI-191 and some brief 21 points about FLEX equipment strategies and defense in 22 depth.
23 In Item B, a discussion will be presented 24 on the use of Containment Accident Pressure, CAP, in 25
73 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 determining the net positive suction head margin for 1
ECCS pumps and containment heat removal pumps.
2 This is the main purpose for Appendix B.
3 I would now like to allow the presentation to continue 4
by Steve Smith.
5 MR. SMITH: All right, thanks, Jim. We're 6
going to go ahead and we'll turn our camera off now 7
that you've gotten a chance to get a look at us and 8
we will start presenting our slides. We have picked 9
the right ones. Yes.
10 MR. STECKEL: Yes, you did.
11 MR. SMITH: Okay, so this is just our title 12 slide. I'm going to move along to Slide 2 which just, 13 it tells the major change that we made to the Reg Guide.
14 With respect to GSI-191, what we did was 15 we added -- the biggest change that we added in vessel 16 guidance and some other references that had been 17 developed since the last revision.
18 The other major change to the Reg Guide 19 is the addition of Appendix B for the use of CAP and 20 NPSH calculations and I believe that ACRS is familiar 21 with both of these topics.
22 They've been around for quite a while.
23 I'm going to move along to Slide 3. And this slide 24 lists the major changes made in Rev 5 that are related 25
74 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 to GSI-191.
1 If you have questions on any of these, just 2
stop, I'm not going to go through them. We went through 3
them in more detail in the subcommittee meeting. Let 4
me know if you have questions on these or --
5 MEMBER MARCH-LEUBA: Yes, this is Jose 6
just for the record. All you're doing, we have an echo.
7 MR. SMITH: Mine's off.
8 (Audio interference.)
9 MEMBER MARCH-LEUBA: How do you want to 10 do this?
11 CHAIRMAN REMPE: Let's try again. I don't 12 hear an echo. Can you hear us?
13 MEMBER MARCH-LEUBA: We muted everybody 14 so you have to mute yourself.
15 MALE PARTICIPANT: Yes, we can hear you.
16 DR. SCHULTZ: I can hear you now on the 17 line.
18 MEMBER MARCH-LEUBA: Okay, sorry about 19 that. Technical difficulties. So the question is, 20 the updates to the Guide are all there. Are they all 21 consistent with the GSI-191 resolution of the issue 22 that we have reviewed it for? Just for the record.
23 MR. SMITH: Yes, they're all consistent 24 with what has been reviewed. Oh, I'm sorry. Yes, this 25
75 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 is Steve Smith again with the Staff and yes, all the 1
changes we made to the Reg Guide in Rev 5 are consistent 2
with what we have presented to the ACRS in the past.
3 MEMBER MARCH-LEUBA: Thank you. Keep 4
going.
5 MR. SMITH: Okay, sorry about that. All 6
right, so I'm going to move on to Slide 4. And this 7
is the status of the Reg Guide with respect to DSI-191.
8 We don't anticipate any significant 9
changes to the Reg Guide in the future for GSI-191 issue 10 where things can come up that are not to assume, but 11 at this point, we believe that Rev 5 is and that some 12 of the information that is in Rev 5 is a complete 13 guidance document for this topic.
14 Now we still have the tendency of R50.46(c) 15 Rulemaking which is currently with the Commission which 16 could have us add or remove some risk informed guidance 17 that is currently referenced in this.
18 It will either be finalized or maybe it 19 will be removed. We're not really sure. We're waiting 20 for the Commission to tell us what they want to do with 21 the 50.46C rule.
22 Slide 5 has a lot more information on it 23 just because this is a little bit more complicated.
24 I don't want to spend -- even though there's a lot of 25
76 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 worries here, I don't want to spend a lot of time on 1
this slide so because it's not related directly to the 2
revision.
3 But if you're interested or have got some 4
interest in the FLEX equipment and its ability to 5
provide defense and depth. So this slide talks a little 6
bit about the defense and depth that may be available 7
from FLEX.
8 And these for the issues that we're talking 9
about today which would be a loss of MPSH margin either 10 due to a CAP issue or due to a strainer clogging issue.
11 The one thing to note is the FLEX strategies 12 were not developed or reviewed by the NRC for response 13 populated accidents like the ones that we are talking 14 about when we talk about drainer clogging or CAP.
15 They were developed for basically wide, 16 large scale, you know, natural disaster type things 17 so there's some differences between those type of events 18 and what we are actually talking about in the pro-temp 19 gap and these cooling issues.
20 So there are some differences between BWR 21 and PWR FLEX equipment the way it's installed. PWRs 22 have high volume direct RCS injection points that are 23 either they're configured, they're not hooked up, but 24 they can be readily connected to the pumps and can pump 25
77 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 directly into the RCS.
1 PWR only had low volume direct RCS 2
injection and basically those are to make up either 3
for a shutdown condition or if you had a say a RCP seal 4
leak or something like that. That's what those are 5
designed for the PWRs.
6 Now the PWRs may be able to reconfigure 7
the high volume steam generator pump will eject to the 8
RTS, but that's not something that's been pre-planned 9
and pre-thought out.
10 It appears that the PWR FLEX strategies 11 are more even applied than PWRs for these scenarios.
12 The PWRs would take longer for I guess a high-volume 13 concept up to the RTS if they could do it at all.
14 So that's the bottom line on the potential 15 defense and depth that's been provided by the FLEX 16 equipment. I'll just pause there and see if there's 17 any questions that are on that slide.
18 MEMBER MARCH-LEUBA: This is Jose. Yes.
19 Just a comment that I'm the one that asked you to 20 include this slide on the presentation. Because since 21 there are Reg Guide 182 deals with availability of water 22 sources during this extended event, obviously FLEX is 23 one of those water resources.
24 And it's good to know that BWRs will 25
78 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 probably improve to the significantly and PWRs that 1
have been there with it or without it so. Thank you 2
for presenting that.
3 MR. SMITH: Yes, I agree. I agree that 4
what you said sounds correct to me. Okay. Then 5
starting with the next slide, Ahsan is going to discuss 6
the use of CAP for the MPSA margin calculations. Go 7
ahead.
8 MR. SALMAN: Okay, thank you. This is 9
Ahsan Salman. I'm a Senior Nuclear Engineer in the 10 Nuclear Performance Systems Branch and the Regional 11 Safety Systems.
12 I'll talk about the use of containment 13 accident pressure in determining the NPS stretch of 14 the containment here to move pumps and the ECCS pumps.
15 There's this slide shows some background on the use 16 of CAP.
17 This issue was highlighted about 15 years 18 ago when NRC received EP applications from Browns Ferry 19 and then from Monticello. Both were using CAP in their 20 NPSH analysis.
21 At that time, the only published guidance 22 was Reg Guide 1.1 which stated that CAP should not be 23 used for NPS as how are some licensees were using CAP 24 and NRC had approved its use.
25
79 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 The EPR reviews of the Browns Ferry and 1
the Monticello were discontinued and put on hold. The 2
Staff prepared a white paper documenting its position 3
to ACRS.
4 Also, the BWR Owners Group submitted a 5
topical report providing a standard approach for 6
requesting user CAP. In return ACRS provided 7
recommendations in a letter to EDO.
8 And the main one of them which were accepted 9
also are mentioned in here, the licensee should use 10 guidance in Reg Guide 1.82 so that's why the Reg Guide 11 1.1 was merged into Reg Guide 1.82.
12 And then operator actions to control CAPs 13 should be reliable. Risks should be small. Support 14 Staff for the SERS meant of problem with NPSHa the, 15 variable NPSH less than NPSHr.
16 And then the SERS agreed with the owners 17 group, BWR owners group tested the statistical 18 calculations to calculate margin. And the last one 19 which was also included in this Reg Guide was the margin 20 between the available NPSH.
21 And the required NPSH should consider 22 uncertainty in that the required NPSH. So then the 23 Staff SECY paper was issued. In this SECY paper there 24 was a Staff position for the use of CAP deterministic 25
80 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 analysis is used.
1 And the recommendation from ACRS was to 2
use deterministic analysis and a plant specific PRA, 3
but when it went to the Commission, the vote for the 4
Commission was an Option 1 which was to just use a 5
deterministic analysis, conservative analysis and 6
include all those SER recommendations that I just 7
listed.
8 MEMBER MARCH-LEUBA: This is Jose. Let 9
me summarize what you said in my own words. And you 10 tell me if it's correct.
11 MR. SALMAN: Okay.
12 MEMBER MARCH-LEUBA: In lesson C the wants 13 to determine whether there is an ECCS pumps have 14 sufficient operating margin, let's call it MPSH.
15 MR. SALMAN: Yes.
16 MEMBER MARCH-LEUBA: Will perform a 17 dynamic calculation of the locker or what their event 18 will concern with.
19 MR. SALMAN: Yes.
20 MEMBER MARCH-LEUBA: And as a function of 21 time after the accident, you will calculate the 22 pressures of the containment is at --
23 MR. SALMAN: Okay.
24 MEMBER MARCH-LEUBA: -- foregoing the 25
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(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 accident as it's supposed to develop or if you set those 1
minutes, hours after the accident.
2 MR. SALMAN: Yes.
3 MEMBER MARCH-LEUBA: And it will impose 4
conservative bounding numbers for the assumptions which 5
are described in Appendix B of the Regulatory Guide 6
7 MR. SALMAN: Yes.
8 MEMBER MARCH-LEUBA: -- so that when we 9
are at the end calculate what is the pressures high 10 containment as function of time with a ten minute that 11 pressure is higher than that required to have the pumps 12 operating.
13 MR. SALMAN: Right.
14 MEMBER MARCH-LEUBA: Is that correct?
15 MR. SALMAN: That is correct. And also, 16 calculate the suppression pool of the sump water 17 temperature conservative analysis for that so that the 18 NPSH available is conservatively calculated based on 19 the available, based on the temperature of the pool 20 21 MEMBER MARCH-LEUBA: All right.
22 MR. SALMAN: -- because one of the terms 23 in NPSH and negative term, the NPSH is the vapor pressure 24 at the pool temperature.
25
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(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 MEMBER MARCH-LEUBA: Yes, and for my point 1
of view, ACRS' main concern and which we still have 2
differences, is that they should be plant specific risk 3
analysis performed that this containment operation has 4
been performed every percent reality.
5 I mean, you have to add additional failures 6
like somebody alliance about in the incorrect position 7
or containment had leakages before you had the accident 8
and therefore you cannot hold the pressure.
9 MR. SALMAN: Yes.
10 MEMBER MARCH-LEUBA:
Our Members 11 agreement with the Staff, ASRC' agreement with the Staff 12 was that this is likely to be very plant specific 13 dependent and it would be wise to have a plant specific 14 risk analysis.
15 MR. SALMAN: Exactly. Yes, that was only 16 difference the, all the deterministic analysis 17 calculation methods were incorporated in this Reg 18 Guide.
19 And the only difference was the PRA that 20 when a licensee whose CAP for an EPU or some other 21 purpose they should present a plant specific PRA for 22 that.
23 MEMEBER MARCH-LEUBA: Yes, and the ACRS 24 position also was that and which you have accepted and 25
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(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 implemented into the Reg Guide is that a licensee should 1
look first for how are changes that we give you the 2
NPSH margin before taking credit for CAP.
3 MR. SALMAN: Yes, the changes that I have 4
listed here, one of the major changes is the NPSH 5
required should consider the uncertainty because the 6
required NPSH is calculated or is determined by testing 7
at the plant vendor and the pump vendor I mean.
8 And the differences between the test 9
conditions and the plant conditions there should be 10 an uncertainty so that is, that makes a required MPS 11 at higher than the 3 percent --
12 MEMBER MARCH-LEUBA: Right.
13 MR. SALMAN: -- factory estimate so --
14 MEMBER MARCH-LEUBA: Yes.
15 MR. SALMAN: -- that is another margin 16 uncertainty considered in this Reg Guide.
17 MEMBER MARCH-LEUBA: Yes, but my point is 18 that some of the EPU applicants that wanted to use CAP 19 credit ended up making some minor reasonable 20 modifications to the plant.
21 Some did heaters changer, some did 22 alignment of pumps, so that after those modifications, 23 they did not require a CAP. So what --
24 MR. SALMAN: That -- what I think the Reg 25
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(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 Guides says is the Staff will either reviews a CAP 1
application should consider that there are no 2
reasonable, the licensee has performed a sufficient 3
scope analysis that no original modifications can be 4
implemented.
5 MR. SALMAN: Yes, yes. The one, this is 6
one of the summary that if the plant, first of all, 7
the plant should consider modification. If the 8
modification is impractical, then they can apply 9
reusing this amount, this much amount of a CAP. And 10 that is included in the Guidance and the --
11 MEMBER MARCH-LEUBA: Excellent.
12 MR. SALMAN: And the last slide of this 13 presentation, there's a summary and that includes that, 14 but the plants, the EPU that were discontinued at that 15 time were Monticello and Browns Ferry.
16 And both of them they were using CAP but 17 without all these requirements that are now in the Reg 18 Guide. So finally it ended up that one of the plants 19 I remember was Peach Bottom.
20 They did hardware modifications, plant 21 modification by using two heat exchangers to reduce 22 the pool temperature, the suppression pool temperature 23 and so that there was no CAP used.
24 And another plant Browns Ferry first 25
85 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 obligation which was I think 2005 they were using CAP, 1
but then afterwards, the applications submitted in 2015 2
they did not use CAP, but they approved the performance 3
of the heat exchangers so that the pool temperature 4
goes down and the vapor pressure is suppressed.
5 MEMBER MARCH-LEUBA: Okay, thank you.
6 You can continue.
7 MR. SALMAN: Okay. So I go to slide, next 8
slide which this is stating what is the margin. The 9
margin is calculated by the available NPSH minus the 10 effective NPSH which the effective NPSH is the 3 percent 11 that is a test done by the hydraulic institute standard 12 and that includes uncertainties.
13 So that is one of the major changes before 14 this Reg Guide was issued. And for special events for 15 the BWR which is a space station blackout or Appendix 16 R or the aqueous events, the Reg Guard allows the user 17 the 3 percent which is without the uncertainties and 18 use realistic inputs for the calculation of containment 19 accident pressure in the pool temperature.
20 Another point here is the negative NPSH 21 margin is acceptable if tests demonstrate that proper 22 performance safety function and that is, that were 23 highlighted in the previous meeting, what are the 24 different requirements for a negative NPSH. And if 25
86 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 you want to go, I have to open my slide before.
1 MEMBER MARCH-LEUBA: No, no. We can look 2
at a transcript of the SUCO meeting unless a member 3
wants to ask about it.
4 MR. SALMAN: Yes, yes. We, I have to open 5
the other. So anyway, the Monte Carlo analysis was 6
recommended in the BWR owners group report to calculate 7
the margin.
8 In the conservative
- analysis, the 9
deterministic analysis, it will only say that heavy 10 are doing terminist analysis, which is conservative, 11 but the question from ACRS was always so what is the 12 margin?
13 So in order to determine margin in the 14 conservative
- analysis, this Monte Carlo 95-95 15 calculations was recommended by the ACRS also and it 16 is included in the, in this Reg Guide that any plant 17 who is using CAP above the vapor pressure should 18 determine what is the margin, what, how much is, what 19 is a conservatism in the deterministic analysis?
20 Another item is if the CAP up to the vapor 21 pressure, the pool temperature can be used without Monte 22 Carlo analysis. So that is most BWRs, there is some 23 temperature is
- higher, much higher than the 24 atmospheric.
25
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(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 Then so those plants, they can use CAP up 1
to the vapor pressure of the pool temperature without 2
any Monte Carlo analysis. And if it is more than that 3
vapor pressure the whole temperature, then the Monte 4
Carlo analysis and another item in this is the plant 5
should monitor a pre-existing leak during normal 6
operation.
7 This was done also by Monticello. Yes, 8
they agreed or in the EPO application and the Staff 9
SER it was Staff required them to monitor a pre-existing 10 leak in the containment during operation.
11 MEMBER HALNON: So this is Greg. One 12 quick question back on the safety side. The test, does 13 it demonstrate promptly performed safety function?
14 This kind of brings me back to a mission time type 15 discussion that seems to be in circular motion in the 16 industry.
17 Is it, is the guidance clear enough that 18 we're not going to run into that problem of arguing 19 about what the mission time will be for these tests 20 that have to demonstrate a safety function for a 21 degraded system?
22 MR. SALMAN: Are you, I'm sorry, are you 23 talking about a negative margin when the --
24 MEMBER HALNON: Yes.
25
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(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 MR. SALMON: When the -- yes, there are 1
requirements. Let me read what are the requirements.
2 I have the subcommittee presentation here. And those 3
requirements are important. Yes, the slide in this 4
previous presentation with respect to the margin 5
section --
6 MEMBER MARCH-LEUBA: Yes, on this issue 7
while you look for it, if a slide is --
8 MR. SALMAN: Okay, use of CAP --
9 MEMBER MARCH-LEUBA: -- presented in the 10 meeting, it is part of the record. Right?
11 (Simultaneous speaking.)
12 (Audio interference.)
13 MEMBER MARCH-LEUBA: Okay?
14 MR. SALMAN: Yes, that is, we have a report 15 and safety, does the pump has a negative margin and 16 the red light says it is acceptable if the tests are 17 done to demonstrate the actual pump or a similar pump, 18 will perform at for a limited time duration less than 19 hundred hours.
20 Actual pump or similar model pump is 21 tested, tested at the same speed as at the plant site 22 and tested at actual predicted available NPSH and the 23 test duration is for the time you're in this NPSH margin 24 is negative.
25
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(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 And the flow and discharge help should be 1
greater than that required for the safety analysis.
2 MEMBER MARCH-LEUBA: This is Jose, the 3
mission time is that of or the result of the calculation, 4
the continuing calculation that we perform to determine 5
that CAP was needed.
6 So the time where the MPSH is violated is 7
calculated, there is no argument about it.
8 MEMBER HALNON: Okay so the test durations 9
for the period for negative margin is that test 10 continued and because the pump is now a degraded state 11 because of the potential capitation in your 12 interpretation and during the tie?
13 MEMBER MARCH-LEUBA: The pool temperature 14 finally cool down and now you recover NPSH.
15 MEMBER HALNON: Okay.
16 MEMBER MARCH-LEUBA: And I suppose it 17 demonstrates that the pump didn't break up that much.
18 MEMBER HALNON: That's a generalized 19 statement when you just said it had to be plant specific 20 so.
21 MEMBER MARCH-LEUBA: No, it has to be.
22 This completion is plant specific.
23 MEMBER HALNON: Okay. I just wanted to 24 make sure we weren't going to get into a circular 25
90 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 discussion about mission time. It looks like you've 1
got that covered so I'm okay with --
2 MR. SALMAN: Okay, so containment leakage, 3
that's another item in this slide which the licensee 4
should demonstrate loss of containment, integrity and 5
loss of containment isolation cannot occur and monitor 6
leakage during operation.
7 And quantifying of the NPSH margin for the 8
DBA LOCA the calculation should use considerable 9
debonding inputs and to demonstrate margin, they can 10 use real estate and Monte Carlo analysis to determine 11 the conservatism.
12 And require NPSH should include uncertain.
13 So that's for DBA LOCA, but for special events, the 14 NPSHr may use without uncertainty. The next slide is 15 a guidance summary which I talk most of these points 16 and already talk, but if you want to go through it again, 17 I'm willing to, I'll be willing to.
18 CHAIRMAN REMPE: This is Joy and I do have 19 a question and I apologize, I had communication issues 20 during the subcommittee meeting and I tried to hone 21 in on this, but basically on the loss of containment, 22 integrity venting for example shouldn't occur during 23 CAP use.
24 And if I look at the guidance on Page 83 25
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(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 out of 88, it does talk about the fact you shouldn't 1
allow them to be venting and using CAP at the same time.
2 But I'm thinking again about what happened 3
after Fukushima and so if an applicant comes in with 4
an LAR and they are trying to say, okay, we can use 5
CAP and they try and justify it. Are you guys going 6
to try and implement this guidance?
7 Are you going to say, let us see your severe 8
accident management guidance so we know that you're 9
going to check and see that you don't need CAP before 10 you go to early venting?
11 Because I mean, that's I would want to see 12 that if I were checking into it and how will the 13 regulators know how to check? Because the severe 14 accident guidance isn't really required to review, you 15 know, to be submitted as part of this. I mean, how 16 are you going to implement this?
17 MR. SALMAN: Well when a licensee submits 18 an application for the use of CAP, that application 19 should be consistent. The analysis for the usage of 20 CAP should be consistent with the procedure they're 21 using for the DBA LOCA.
22 And that's how this guidance is written.
23 This does not consider any severe accident procedure 24 in this Reg Guide.
25
92 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 CHAIRMAN REMPE: Okay, but then during a 1
real event, where they have a long-term station blackout 2
and maybe they tried to use CAP during that event and 3
things went south, shouldn't somebody be checking to 4
make sure that during the severe accident that they 5
basically don't need the CAP anymore to run the pumps 6
before they vent?
7 And, I mean, how will that interface be 8
taken care of is what I'm asking? And it seems like 9
somebody ought to be checking that.
10 MEMBER KIRCHNER: By definition, if the 11 pumps function -- I shouldn't answer for the Staff.
12 My logic would be the following: if you're in design 13 basis accident space after 15, you do the dynamic 14 analysis to ensure you have sufficient and net positive 15 substantive head on those cooling pumps.
16 If they function, then you shouldn't have 17 a severe accident. If you lose CAP and you lose the 18 functioning of the pumps, then you're in trouble 19 obviously and your gone beyond the design basis 20 accident.
21 So I think the Staff guidance is, revolves 22 around a design basis event, not a severe accident.
23 CHAIRMAN REMPE: So --
24 MEMBER KIRCHNER: Once you get into severe 25
93 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 accident space then the correct --
1 CHAIRMAN REMPE: So let's think of --
2 MEMBER KIRCHNER: -- both of those other 3
things, but for purposes of analyzing design basis 4
accidents, the presumption is in my mind that if you 5
have sufficient capacity and net positive suction CAD 6
for the pumps, then you're going to deliver the ECCS 7
cooling and containment cooling necessary to prevent 8
the severe accident.
9 CHAIRMAN REMPE: So --
10 MEMBER KIRCHNER: So you haven't moved on 11 to Chapter 19 yet.
12 CHAIRMAN REMPE:
- Okay, so during 13 Fukushima, --
14 MEMBER KIRCHNER: Well that's --
15 CHAIRMAN REMPE: -- for example, they 16 didn't know how high the water was in the core. They 17 didn't know it was a severe accident. And when I tried 18 to bring this up and I had communication issues during 19 the subcommittee meeting, Dennis tried to hone in on 20 it by saying the operators don't have a little gauge 21 in the control room saying I'm in a design basis event 22 versus --
23 MEMBER KIRCHNER: Okay.
24 CHAIRMAN REMPE: -- a severe accident.
25
94 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 And so if I were wanting to be very --
1 (Simultaneous speaking.)
2 CHAIRMAN REMPE: You'd hope so.
3 MEMBER KIRCHNER: -- in trouble.
4 CHAIRMAN REMPE: Yes, but I mean basically 5
there were some, an intended venting due to expansion 6
of the seals on the PCV and things so again temperatures 7
and pressures are dictating when people start to think 8
about we need to start doing early venting because they 9
don't want to have a problem.
10 But I, what I'm back to is if I wanted to 11 be thorough, I might say, this means I need to think 12 about what's in the severe accident management guidance 13 to make sure that this will not occur.
14 And that was actually in one of our letters 15 about GSI-191. In the past we said, well no, I'm trying 16 to remember. Maybe it was one of the post-Fukushima 17 letters I guess.
18 They said, you know, this seems okay, but 19 we need to think, it was in one of our prior letters 20 where we said, think about, maybe it was the Monticello 21 letter when we approved their EPU that we said, you 22 know, you may need to think about this --
23 MEMBER MARCH-LEUBA: I was going to --
24 CHAIRMAN REMPE: -- what can happen in 25
95 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 severe accidents. And I can pull up that letter. But 1
that's why I think it's important to kind of, and I 2
know it's in your draft letter to think about this.
3 MEMBER MARCH-LEUBA: Yes. I was going to 4
give you a hint, a preview that the letter makes that 5
accommodation.
6 CHAIRMAN REMPE: Yes, it's --
7 MEMBER MARCH-LEUBA: And I think it's wise 8
to do.
9 CHAIRMAN REMPE: Yes, it --
10 MEMBER MARCH-LEUBA: And the Staff should 11 look at it during the review, but as one more checkmark 12 to do, nothing showstopper.
13 CHAIRMAN REMPE: Because they don't 14 usually look at the severe accident management guidance 15 and that type of thing.
16 MEMBER MARCH-LEUBA: Yes.
17 CHAIRMAN REMPE: Okay, but anyway, I just 18 think I've homed in on my point of what I was trying 19 to make and I had some communication issues the last 20 subcommittee meeting.
21 MR. SALMAN: One of the requirements in 22 this Reg Guide is the loss of containment integrity.
23 And but then in parenthesis it says venting should 24 not occur during CAP.
25
96 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 So if a licensee is presenting an analysis 1
for the use of CAP and they have this venting in the 2
analysis and then they are asking to use CAP, then the 3
analysis should cover that.
4 CHAIRMAN REMPE: So again, I'm looking at 5
your guidance on Page 83 where you have that section 6
and it's focused on design basis events. And --
7 MR. SALMAN: Right.
8 CHAIRMAN REMPE: -- what I'm saying is that 9
the world isn't so cut and dried and so I think that 10 means going into the severe accident --
11 MR. SALMAN: Right.
12 CHAIRMAN REMPE: It's a process too.
13 MR. SALMAN: So if you've got --
14 CHAIRMAN REMPE: Sometimes people don't 15 have a fine or they tend to segregate this and they 16 think only one way because that's what they're supposed 17 to think on that topic.
18 MR. SALMAN: So the CAP analysis that they 19 present to us if it includes venting, then the analysis 20 should consider that venting and then calculation of 21 CAP and the pressure and the containment.
22 CHAIRMAN REMPE: Okay, but then I think 23 also that it would behoove the Staff to think about 24 severe accident guidance or make the applicant 25
97 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 demonstrate that this won't cause problems in severe 1
accidents is all --
2 MR. SALMAN: Okay.
3 CHAIRMAN REMPE: -- I'm trying to say.
4 MR. SALMAN: Yes, the procedure should be 5
then consistent with analysis.
6 CHAIRMAN REMPE: And see --
7 MEMBER MARCH-LEUBA: That is an excellent 8
phrase. You should frame it and put it in your wall.
9 I believe you finish your presentation, Ahsan?
10 MR. SALMAN: Yes, that is all. If there 11 is any question on the guidance summary which I 12 mentioned before all these points, please let me know 13 so we can answer the questions.
14 MEMBER MARCH-LEUBA: Members, you have any 15 more questions for the Staff? Hearing none, any 16 members of the public that would like to make a comment?
17 Unmute yourself and do so right now.
18 We don't have any comments from the 19 members. Chair, you are --
20 CHAIRMAN REMPE: Okay.
21 MEMBER MARCH-LEUBA:
it's your 22 microphone.
23 CHAIRMAN REMPE: Okay. Thank you very 24 much. Thanks to the Staff. At this point, it's not 25
98 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433 been going that long so how about we just take a few 1
minutes until Sandra can come back and bring up your 2
letter and let's not have an official break or you want 3
to have a ten-minute break?
4 MEMBER MARCH-LEUBA: I don't need it.
5 CHAIRMAN REMPE: Okay, so as soon as we 6
can, we'll resume with letter writing and then --
7 MEMBER MARCH-LEUBA: Yes, and then --
8 CHAIRMAN REMPE: -- stay tuned all of you.
9 MEMBER MARCH-LEUBA: -- we're off the 10 record and what time?
11 CHAIRMAN REMPE: Oh, yes. Thank you very 12 much. I'd like to also ask to go off the record and 13 ask the Court Reporter to come back tomorrow morning 14 at 8:30 a.m. Okay? Whether it's you or someone else 15 from your organization. Okay. Yes, thank you very 16 much.
17 (Whereupon, the above-entitled matter 18 went off the record at 4:20 p.m.)
19 20 21 22 23 24 25
1 Reg Guide 1.82, Revision 5 Advisory Committee on Reactor Safeguards November 1, 2022 Ahsan Salman Steve Smith
2 RG 1.82 Changes in Rev. 5
- GSI-191 (Main body of RG and Appendix A)
Updated to include new information on the effects of debris on long-term core cooling
Major change was to add information and references regarding the in-vessel effects of debris
- Use of CAP (Appendix B)
Added new Appendix B - guidance on the use of CAP in determination of NPSH margins
RG 1.1 states only containment pressure prior to LOCA should be used in NPSH calcs
RG 1.1 withdrawn (4/2015); new CAP guidance is now included in RG 1.82, Rev 5.
3 GSI-191 Related Changes
- In-Vessel Guidance Updates
- Penetration Testing Guidance
- Improved Clarity and Detail
- Updated Knowledge Base Report
- BWR Evaluation of Lessons Learned
- Updated Jet Testing
- Test Debris Preparation Guidance
- Risk-Informed Resolution - Draft RG 1.229
4 RG 1.82 Status With Respect to GSI-191
- Revision 5 to RG 1.82 was made after the closure of GSI-191
- RG 1.82, Rev 5 is a complete guidance document for the effects of debris on long-term core cooling
- Additional risk-informed guidance may be issued as the result of the 10CFR50.46c rulemaking currently with the Commission
5 FLEX Equipment - Defense-in-Depth FLEX strategies are designed for beyond-design-basis external events initiated by natural phenomena
- Not intended or reviewed for response to postulated accidents Flex equipment and strategies are different between BWRs and PWRs
- BWR FLEX includes equipment for direct connection to the RCS and the ability to vent containment
- PWR FLEX RCS injection only has low volume pumps with connections to the RCS For Shutdown or low leakage only, includes borated water supply Decay heat is removed via the steam generators with higher volume pumps Connecting steam generator FLEX pumps to the RCS may be possible for some plants but has not been pre-planned or verified to be feasible in general No pre-determined strategy for containment pressure reduction BWRs FLEX strategies are more suited to provide DID for cooling by direct connection to the RCS PWRs FLEX strategies may be less effective as DID for long-term cooling
- Effectiveness depends on plant-specific equipment capacities, layouts, connections, etc.
- No boration available at higher flow rates
- Lower flows could be adequate if it takes a long time for strainer blockage to occur
RG 1.82, REVISION 5, APPENDIX B GUIDANCE FOR THE USE OF CONTAINMENT ACCIDENT PRESSURE IN DETERMINING THE NET POSITIVE SUCTION HEAD MARGIN FOR EMERGENCY CORE COOLING SYSTEM PUMPS AND CONTAINMENT HEAT REMOVAL PUMPS IN BOILING WATER REACTORS AND PRESSURIZED WATER REACTORS
CONTENTS
- 1.
Background
- 2.
Use of CAP in Determining NPSH Margin
- 3.
Containment Isolation and Containment Leakage
- 4.
Quantifying NPSH Margin
- 5.
Guidance Summary
- 1.
Background
- ACRS recommendation in letter to EDO included in RG Licensees to use guidance in RG 1.82 to demonstrate positive NPSH margin Operator actions to control CAP should be reliable, risk should be acceptably small Before CAP credit, licensees to justify impractical to modify plant o Modification not needed for small CAP credit Support staff reassessment of problems with NPSHa NPSHr Agree with BWROG statistical calcs to calculate margin.
Margin (NPSHa - NPSHr) to consider uncertainty in NPSHr
- SECY-11-0014, Commission voted for Option (1)
- Commission directed staff to credit CAP using guidance in SECY-11-0014, Enclosure 1
- RG 1.82, Revision 5, Appendix B is based on SECY-11-0014, Enclosure 1
- 2.
Use of CAP in Determining NPSH Margin
- NPSH margin = (NPSHa - NPSHreff), where NPSHreff = NPSHr3% + uncertainties
- For BWR special events, NPSHr3% and realistic inputs may be used
- Negative NPSH margin is acceptable if tests demonstrate pump will perform safety function(s),
Monte Carlo analysis 95/95 lower limit to demonstrate margin in deterministic analysis
- CAP up to the vapor press at the pool temperature can be used without Monte Carlo analysis
- CAP above vapor press at pool temperature, Monte Carlo, pre-existing leak monitoring necessary
- 3.
Containment Isolation and Containment Leakage
- If CAP is used, the licensees should demonstrate loss of containment integrity and loss of containment isolation cannot occur, monitor leakage during operation.
- 4.
Quantifying NPSH Margin
- DBA LOCA-Conservative bounding inputs, realistic and Monte Carlo analysis to determine conservatism, NPSHr should include uncertainty.
- BWR special events - realistic analysis, NPSHr may be used without uncertainty
- 5.
Guidance Summary
- For BWR special events, NPSHr3% may be used to calculate margin
- Maximum flow rate for NPSHa analysis flow rate used in safety analysis
- Loss of containment integrity (venting) should not occur during CAP use
- NRC-approved operator action to control CAP is acceptable.
- Negative NPSH margin if tests on same or similar pump demonstrate adequate performance
- Propose a method to determine pre-existing leakage rate during plant operation
- BWRs - follow NEDC-33347P-A/NEDO-33347-A
- PWRs - use the vapor pressure corresponding to the sump water temperature or use a procedure a statistical process similar to the BWROG.
- Mission time for pump using CAP to include recovery time from the accident.
Advisory Committee on Reactor Safeguards November 1, 2022 SECY-22-0076 Expansion of Current Policy on Potential Common-Cause Failures in Digital Instrumentation and Control Systems
Technical Staff Presenters
- Samir Darbali - Electronics Engineer, NRR/DEX
- Steven Alferink - Reliability and Risk Analyst, NRR/DRA
- Norbert Carte - Senior Electronics Engineer, NRR/DEX Digital I&C Project Managers
- Bhagwat Jain - Senior Project Manager, NRR/DORL
- Michael Marshall - Senior Project Manager, NRR/DORL 2
Working Group Members
- NRR/DEX
- NRR/DRA
- NRR/DSS
- Charley Peabody 3
- Ming Li
- Michael Marshall
- NRR/DORL
- RES/DE
- Sergiu Basturescu
Presentation Outline 4
- Introduction
- Background and Key Messages
- Purpose of SECY-22-0076
- Staff Position on ACRS Questions
- Proposed Expanded Policy
- SECY-22-0076 Points
- Next Steps
=
Background===
- Nuclear power plants continue to install digital I&C technology
- SRM-SECY-93-087 directs that, if the D3 assessment shows that a postulated CCF could disable a safety function, then a diverse means be provided to perform that safety function or a different function
- The staff developed SECY-22-0076 which provides recommended language for an expanded policy that allows for greater use of risk-informed approaches to address DI&C CCFs for high safety significance systems 5
Key Messages
- The proposed expanded policy in SECY-22-0076 encompasses the current points of SRM-SECY-93-087 (with clarifications) and expands the use of risk-informed approaches in points 2 and 3
- The four points when taken together provide criteria for the assessment of diversity and defense in depth against CCF
- Use of risk-informed approaches will be expected to be consistent with the Safety Goal Policy Statement, PRA Policy Statement, and SRM-SECY-98-0144
- The current DI&C CCF policy will continue to remain a valid option for licensees and applicants
- Point 4 ensures the health and safety of the public and already incorporates an implicit element of risk informing as it focuses only on those critical safety functions needed to ensure the safety of the facility 6
SECY-22-0076 Purpose
- To request that the Commission expand the current policy for digital I&C CCFs to allow the use of risk-informed approaches to demonstrate the appropriate level of defense-in-depth, including not providing any diverse automatic actuation of safety functions.
- This expanded policy would apply to requests for new or amended licenses and design approvals, for all nuclear power plant types, under 10 CFR Part 50, Domestic Licensing of Production and Utilization Facilities, and 10 CFR Part 52, Licenses, Certifications, and Approvals for Nuclear Power Plants.
7
Staff Positions on ACRS DI&C Subcommittee Questions ACRS Question 1: Would the revised policy be applicable to advanced reactors?
Answer: The proposed expanded policy would apply to requests for all nuclear power plant types licensed under 10 CFR Part 50 and 10 CFR Part 52, including advanced reactors.
ACRS Question 2: Do aspects of the policy for which the staff did not request a change carry forward unaltered?
Answer: Yes ACRS Question 3: Might different reactor types warrant consideration of different critical safety functions?
Answer: While the expansion of the policy is intended to be technology neutral it relies on the staffs licensing experience to date and assumptions about the design of the facility, such as the presence of a main control room. The staff acknowledges that the critical safety functions listed in the SECY and BTP 7-19 (reactivity control, core heat removal, reactor coolant inventory, containment isolation, and containment integrity) may not be the appropriate set for all reactor designs. The staff has existing regulatory tools (exemptions and alternatives), if necessary, to accommodate designs with different critical safety functions and, if the staff encounters a reactor design where the policy would not be applicable, the staff will engage the Commission as appropriate.
8
Proposed Expanded Policy to Address DI&C CCFs 9
Point 2 Risk-Informed Approach Point 3 Risk-Informed Approach Point 2 SRM-SECY-93-087, Point 2 (Clarified)
Point 3 SRM-SECY-93-087, Point 3 (Clarified)
Current Path Risk-Informed Path Proposed Expanded Policy to Address Digital I&C CCFs The Current Path allows for the use of best estimate analysis and diverse means to address a potential DI&C CCF The Risk-Informed Path allows for the use of risk-informed approaches and other design techniques or measures other than diversity to address a potential DI&C CCF Point 4 SRM-SECY-93-087, Point 4 (Clarified)
Point 1 SRM-SECY-93-087, Point 1 (Clarified)
SECY-22-0076: Point 1 The applicant shall assess the defense in depth and diversity of the facility incorporating the proposed digital I&C system to demonstrate that vulnerabilities to digital CCFs have been adequately identified and addressed.
The defense-in-depth and diversity assessment shall be commensurate with the risk significance of the proposed digital I&C system.
10
SECY-22-0076: Point 1 Commentary
- Allows the defense-in-depth and diversity assessment to be commensurate with the risk significance of the proposed digital I&C system.
- This clarifying aspect of point 1 would be implemented consistent with the review guidance for graded approaches to digital I&C CCF in BTP 7-19, Revision 8.
11
SECY-22-0076: Point 2 In performing the defense-in-depth and diversity assessment, the applicant shall analyze each postulated CCF. This assessment may use either best-estimate methods or a risk informed approach.
When using best-estimate methods, the applicant shall demonstrate adequate defense in depth and diversity within the facilitys design for each event evaluated in the accident analysis section of the safety analysis report.
When using a risk-informed approach, the applicant shall include an evaluation of the approach against the Commissions policy and guidance, including any applicable regulations, for risk-informed decision-making. The NRC staff will review applications that use risk-informed approaches for consistency with established NRC policy and guidance on risk-informed decision making (e.g., Regulatory Guide (RG) 1.174, An Approach for Using Probabilistic Risk Assessment in Risk Informed Decisions on Plant Specific Changes to the Licensing Basis).
12
SECY-22-0076: Point 2 Commentary
- Staffs goal is that the acceptance criteria for risk-informed approaches for digital I&C CCFs will be consistent with the NRCs broader (i.e., not specific to digital I&C) practices and guidance for risk-informed decision making.
- For example, the NRC staff will review license amendment requests for conformance to the guidance in RG 1.174 for applications employing risk-informed approaches.
13
SECY-22-0076: Point 3 The defense-in-depth and diversity assessment may demonstrate that a postulated CCF can be reasonably prevented or mitigated or is not risk significant. The applicant shall demonstrate the adequacy of any design techniques, prevention measures, or mitigation measures, other than diversity, that are credited in the assessment. The level of technical justification demonstrating the adequacy of these techniques or measures, other than diversity, to address potential CCFs shall be commensurate with the risk significance of each postulated CCF.
A diverse means that performs either the same function or a different function is acceptable to address a CCF, provided that the assessment includes a documented basis showing that the diverse means is unlikely to be subject to the same CCF. The diverse means may be performed by a system that is not safety-related if the system is of sufficient quality to reliably perform the necessary function under the associated event conditions. Either automatic or manual actuation within an acceptable timeframe is an acceptable means of diverse actuation.
If a postulated CCF is risk significant and the assessment does not demonstrate the adequacy of other design techniques, prevention measures, or mitigation measures, then a diverse means shall be provided.
14
SECY-22-0076: Point 3 Commentary
- The staff expects that for a license amendment request, the risk significance of CCFs will be determined by any increase in risk to the facility from a postulated digital I&C CCF and that this risk increase would be determined using a quantitative bounding assessment.
- Current experience is insufficient to establish confidence in quantifying the probability of occurrence of digital I&C CCFs.
- The NRC staff will not be able to approve risk-informed quantitative approaches based on reducing the probability of occurrence of digital I&C CCFs through design techniques for high safety significance SSCs.
15
SECY-22-0076: Point 4 Main control room displays and controls that are independent and diverse from the proposed digital I&C system (i.e., unlikely to be subject to the same CCF) shall be provided for manual, system-level actuation of critical safety functions and monitoring of parameters that support the safety functions. These main control room displays and controls may be used to address point 3, above.
16
SECY-22-0076: Point 4 Commentary
- Point 4 is essential in staffs ability to conclude with reasonable assurance that a proposed digital I&C design does not adversely affect an operators ability to manually control critical safety functions
- The staffs position is that the digital I&C system should not be able to take control of the facility away from the operator under all plant conditions (anticipated or unanticipated)
- Point 4 is consistent with the application of existing regulatory requirements for independence that are incorporated into the regulation (10 CFR 50.55a(h) and GDC 22)
- Point 4 already incorporates an implicit element of risk informing (in both SRM-SECY-93-087 and SECY-22-0076).
- Point 4 is only applicable to critical safety functions (defined in SECY-93-087 and SECY-22-0076) and not to all the safety functions performed by the digital I&C system.
- The diverse displays and manual controls do not have to be safety-grade or hardwired.
17
SECY-22-0076: Point 4 Commentary (contd.)
18 Plant Safety Functions Plant Critical Safety Functions reactivity control core heat removal reactor coolant inventory containment isolation containment integrity Digital I&C Functions within the Scope of Point 4 Functions Performed by the Digital I&C System The diverse manual controls and displays for critical safety functions ensure the safety of the facility.
Point 4 only applies to:
The critical safety functions performed by the digital I&C system.
Point 4 does not apply to:
All safety functions performed by the digital I&C system.
Critical safety functions not performed by the digital I&C system.
SECY-22-0076: Point 4 Commentary (contd.)
- Point 4 of SECY-22-0076 has not been an impediment to modern digital control room designs
- e.g., the NuScale and Vogtle 3 & 4 designs meet the current Point 4 of SRM-SECY-93-087
- Licensees that want to use risk information to reduce the requirements for manual controls can request an exemption or an alternative to 10 CFR 50.55a(h) and the staff would inform the Commission before approving or denying such exemptions and alternatives
- The staff believes industry concerns can be addressed in implementing guidance 19
Key Messages
- The proposed expanded policy in SECY-22-0076 encompasses the current points of SRM-SECY-93-087 (with clarifications) and expands the use of risk-informed approaches in points 2 and 3
- The four points when taken together provide criteria for the assessment of diversity and defense in depth against CCF
- Use of risk-informed approaches will be expected to be consistent with the Safety Goal Policy Statement, PRA Policy Statement, and SRM-SECY-98-0144
- The current DI&C CCF policy will continue to remain a valid option for licensees and applicants
- Point 4 ensures the health and safety of the public and already incorporates an implicit element of risk informing as it focuses only on those critical safety functions needed to ensure the safety of the facility 20
Next Steps
- If the Commission approves the expanded policy, the staff will:
- update the existing implementation guidance to address digital I&C CCFs, and
- continue to engage stakeholders and the public to seek comments on the staffs implementation of the expanded policy.
21
Questions?
BTP Branch Technical Position CCF Common Cause Failure D3 Defense-in-Depth and Diversity DI&C Digital Instrumentation and Control ESFAS Engineered Safety Features Actuation System GDC General Design Criteria I&C Instrumentation and control NEI Nuclear Energy Institute Acronyms NRC Nuclear Regulatory Commission PRA Probabilistic Risk Assessment RG Regulatory Guide RPS Reactor Protection System SAR Safety Analysis Report SECY Commission Paper SRM Staff Requirements Memorandum