ML18100B263
| ML18100B263 | |
| Person / Time | |
|---|---|
| Issue date: | 04/05/2018 |
| From: | Commissioners NRC/OCM |
| To: | |
| References | |
| Download: ML18100B263 (58) | |
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1 UNITED STATES NUCLEAR REGULATORY COMMISSION
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MEETING WITH ADVISORY COMMITTEE ON REACTOR SAFEGUARDS (PUBLIC)
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THURSDAY, APRIL 5, 2018
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ROCKVILLE, MARYLAND
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The Commission met in the Commissioners' Hearing Room at the Nuclear Regulatory Commission, One White Flint North, 11555 Rockville Pike, at 10:00 a.m., Kristine L. Svinicki, Chairman, presiding.
COMMISSION MEMBERS:
KRISTINE L. SVINICKI, Chairman JEFF BARAN, Commissioner STEPHEN G. BURNS, Commissioner
2 ALSO PRESENT:
ANNETTE VIETTI-COOK, Secretary of the Commission MARGARET DOANE, General Counsel ACRS MEMBERS PRESENT:
MICHAEL CORRADINI, ACRS Chairman CHARLES BROWN, JR., Member DANA POWERS, Member JOY REMPE, Member JOHN STETKAR, Member
3 1 C-O-N-T-E-N-T-S 2 PROCEEDINGS 3 10:00 a.m.
4 CHAIRMAN SVINICKI: Okay, so, now we will convene the 5 Commission's meeting with the Advisory Committee on Reactor Safeguards.
6 I ask the presenters of the Committee for today's meeting 7 please join the Commission at the table.
8 While you do that, I will announce the last moving piece that 9 I needed to remember which is that large swaths of the United States this 10 morning are participating in a test of the National Emergency Alert System.
11 This is not the local alerts that you opt into or out of on your 12 phones. So, mobile devices across the country, including the area of 13 Montgomery County is participating in this this morning.
14 So, some -- between now and 11:00 a.m., it is expected that 15 all activated emergent of cell phones, if you leave them on and not in airplane 16 mode or if you don't turn them off, they will active in some form, again, every 17 device will receive this, this is a test.
18 Of course, if they don't receive this alert, then that's very 19 newsworthy as well. It would mean that the test in this region failed. But, this 20 is the National Alert System.
21 Of course, the Nuclear Regulatory Commission has a strong 22 attention and focus on emergency preparedness and emergency planning.
23 So, I'm going to leave it up to every person in the room whether or not you 24 would like to silence your device.
25 If you don't silence it, turn it off or put it in airplane mode.
26 You will be alerted by your own or your neighbor's, but I think there's a good
4 1 chance that some phone will be left active in this room.
2 So, we're going to have a good chance of hearing this, but 3 there's a -- we shall not react with any kind of irritation over it because it's very 4 important, being as our colleagues in Hawaii learned recently these types of 5 things are important.
6 Oh, it's happening? Is it not -- is it a silent activation?
7 Because I don't hear any -- wow, did everyone actually silence their phones?
8 That's kind of phenomenal. Well, it's not very attention getting if it was --Im 9 going to need more than that if I need to run for my life.
10 (Laughter) 11 CHAIRMAN SVINICKI: Okay, all right, well, that was it, 12 okay. So, it happened as I was talking about it.
13 Okay, with that dispositioned then, we can begin the 14 Commission's meeting this morning.
15 It is our semiannual meeting with NRC's independent 16 Advisory Committee on Reactor Safeguards which, again, was created in the 17 original Atomic Energy Act.
18 So, this Committee has a very long history of engaging with 19 the Atomic Energy Commission and now the Nuclear Regulatory Commission.
20 We will hear on a set of topics that are just as subset of the 21 Committee's activities over the time since we last met with them. But, we 22 look forward to that.
23 And, we will begin this morning with the ACRS Chairman.
24 Do either of my colleagues have any introductory remarks?
25 Thank you, Commissioner Baran.
26 COMMISSIONER BARAN: Just briefly, I would note that,
5 1 as the Chairman mentioned, this is really an august body with a long and 2 proud history.
3 And, in recent years, or maybe even in not so recent years, 4 a big part of that was the participation of Dana Powers and John Stetkar. I 5 think this is your last meeting with us.
6 We will do our best to make it memorable for you.
7 (Laughter) 8 COMMISSIONER BARAN: I promised them that that 9 would happen, so thank you.
10 But, let me just say thank you so much for your many years 11 of service and the tremendous contributions you've made over those years.
12 We really appreciate it.
13 Thank you.
14 CHAIRMAN SVINICKI: Thank you.
15 Commissioner Burns? Just you associate yourself with 16 your --
17 COMMISSIONER BURNS: I associate with my colleagues 18 remarks.
19 CHAIRMAN SVINICKI: -- remarks. Okay.
20 All right, well, I'll save the fun stuff for when I do my Q&A.
21 So --
22 (Laughter) 23 CHAIRMAN SVINICKI: -- we'll do that then.
24 So, we will then -- now, I will hand the meeting over to ACRS 25 Chairman, Dr. Michael Corradini, please proceed.
26 DR. CORRADINI: Thank you very much.
6 1 I think those slides will be coming up shortly. Excellent, so 2 I will give you an overview, if we go to the next slide, please.
3 So, since our last meeting with the Commission in October, 4 we've issued 11 reports. We've divided them up into groups.
5 The first five are topics that you'll hear from the individual 6 members, the first being NuScale Power Exemption Request from 10 CFR 50 7 Appendix A which is the General Design Criteria 27, Combined Reactivity 8 Control Systems Capability.
9 This is a SECY address, SECY that's detailing the staff's 10 evaluation for Criteria 2 use for the Exemption Request.
11 The second thing you'll hear about today is our letter report 12 on Revision 3 to the Reg Guide 1.174. This was an expanded discussion 13 and guidance on defense in depth.
14 And, since you've already got ahead of me, this will be given 15 to us by Member Stetkar, which we're quite happy he's here, at least this 16 meeting.
17 The third letter report that we'll discuss with you is State of 18 the Art of Reactor Consequence Analysis, or SOARCA. It's a project on 19 Sequoyah integrated deterministic and uncertainty analyses.
20 This focused on the unique aspects of an ice condenser 21 plant hydrogen control and Member Stetkar will talk about this.
22 Next, a report on the safety aspects of the construction 23 permit application for Northwest Medical Isotopes, LLC, which is a 24 radioisotope production facility. And, Member Powers will discuss this with 25 you.
26 And then, finally, the biennial review and evaluation of the
7 1 NRC Safety Research Program. This, in particular, is interesting because, 2 under Dr. Rempe's leadership, it's a revised reports on review of the RES 3 activities.
4 So, the next slide discusses some of the other reports we've 5 done. One is the Safety Evaluation for Topical Report on AURORA-B, an 6 evaluation model for BWR Application to Transient Accident Scenarios.
7 AURORA-B is a new methodology that has been advanced 8 and we looked at it in relative to transient accident scenarios. In particular, it 9 has the ability to consider thermal conductivity degradation as part of the 10 method.
11 Next one is Safety Evaluation of the NuScale Topical Report 12 on applicability of AREVA fuel methodology for NuScale design. One thing, 13 we're going to keep on mentioning AREVA. AREVA's renamed itself to 14 Framatome, but we skipped over that, so you'll see a lot of AREVA.
15 But, in particular, this one is the methodology since AREVA 16 fuel will be used -- Framatome fuel design will be used in the NuScale 17 proposed reactor design.
18 This is essentially looking at the applicability of fuel analysis 19 methodology.
20 Next slide, please?
21 We've also issued a report on the Safety Evaluation of the 22 Topical Report on the PLUS7 Fuel Design which is to be used for the 23 APR1400.
24 Also, a Safety Evaluation on AURORA-B for its evaluation 25 and BWR is a control rod drop accident. There's additional methodology or 26 analysis capability that we reviewed in this topical report.
8 1 Next slide, please?
2 We also looked at Reg Guide 1.232, Guidance for 3 Developing Principle Design Criteria for Non-Light Water Reactors.
4 I'd only mention here that this is one of a group of topics that 5 staff is bringing in front of us for a non-LWRs, the other being License 6 Modernization Framework and the Functional Containment's Policy paper 7 which we'll mention is something we'll be considering in the future.
8 Next slide, please?
9 So, in this area of design certifications, we are currently in 10 the midst of or finishing up the APR1400. This, we expect to be done with 11 sometime in the summertime.
12 And, we've just begun the NuScale Design Certification.
13 Most of our activity so far has been relative to topical reports which we've 14 received in advance of that and we've issued a few letters, as I've mentioned 15 previously.
16 We're in -- we've just begun looking into the early site permit 17 at Clinch River for Small Modular Reactors. And, this, we've had one 18 information meeting and we will continue to have others in the future.
19 And then, finally, on this slide, I mention that we're going to 20 be discussing Brunswick Units 1 and 2 and their use of -- their proposed use 21 of MELLLA+ methodology.
22 Next slide, please?
23 For license renewals, we're in the midst of three, one being 24 Seabrook, the other being Waterford Unit 3 and then River Bend. And, these 25 will be brought up to us in the next few months.
26 And, finally, for AP1000, there is a new WCAP assessing
9 1 potential debris generation for AP1000 cables and non-metallic insulation, 2 which relates to the GSI-191 methodology that's being -- has to be used for 3 the AP1000. In fact, that topic will be talked about with us at our meeting this 4 week.
5 Next slide, please?
6 We also had some ongoing reviews of Regulatory 7 Guidance. For example, the Draft Regulatory Guide DG-1327 on reactivity-8 initiated accidents. This is a modification of the ruling -- of the guidance, 9 excuse me, with the rule on RAIs.
10 And then, NUREG on high burnup fuel storage and 11 transportation.
12 And, finally, NUREG/BR-0058. If you forget what this is like 13 I do, what that is, essentially, a guidance on performing cost benefit analysis.
14 And, in particular, this is coming back to us because we'll hear public 15 comments as well as a finishing of the appendices that were affiliated with the 16 NUREG.
17 And then, Advanced Reactors, I've already mentioned the 18 two other things that are going to be coming from us, one actually, this 19 meeting, we'll be talking about the functional containment policy paper which 20 will be going to the Commission.
21 And then, licensing modernization framework which we'll 22 probably hear from in June, at least that's the plan.
23 Next slide?
24 In the area of digital I&C, ISG-06 revision, if you remember, 25 this is a licensing approach for completion of reviews for application of new or 26 installing digital I&C system upgrades into operating plants.
10 1 Secondly, a diversity in defense in depth against common 2 cause failure. We're expected to get an info paper from the staff on this which 3 we'll then be having a meeting and discussing.
4 And then, the ongoing living document of the integrated 5 action plan.
6 Finally, in terms of rulemaking, we're expecting to get 7 something from the staff on Emergency Preparedness for SMRs. And, 8 there's an amendment to the proposed rule for non-power production or 9 utilization facilities such as research reactors.
10 Next slide, please?
11 In thermal hydraulics, we're still with GSI-191. The PWR 12 Owners' Group is going to be coming to us, expected to come to us to discuss 13 new in vessel debris test results.
14 And, finally, with AREVA or Framatome, the AURORA-B 15 methodology is going to be -- come back to us in a topical report applying it to 16 essentially to LOCA analysis. And then, we'll look at that in the next couple 17 months.
18 In metallurgy and reactor fuels, we just actually heard a --
19 we just had a Subcommittee meeting on consolidation of dry cask and dry fuel 20 storage standard review plans.
21 Next slide?
22 And then, finally, for reliability and PRA, we have our 23 ongoing review of the Level 3 PRA. I think our next meeting full, excuse me, 24 Subcommittee meeting on that will be in May.
25 And, we're continuing to follow Human Reliability Analysis 26 methods developed on whether it would be the IDHEAS program or control
11 1 room abandonment risk.
2 So, that's a quick rendition of where we are. So, I'll go to 3 the individual talks. I'm actually on next for GDC-27. So, I'll just simply move 4 on to that one.
5 If we could have that up? Okay.
6 Next slide, please?
7 So, for GDC-27, the general design criteria are the minimum 8 requirements for principle design criteria for water-cooled nuclear plants to 9 provide reasonable assurance that the facilities can be operated safely.
10 And, historically, GDCs were based on the licensing of the 11 early commercial water-cooled reactor plant designs.
12 Since then, staff has acknowledged that fulfillment of some 13 of the GDCs may be -- may not be necessary or appropriate for some designs.
14 And, in particular, NuScale is a bit of a different plant. It's a modular passive 15 water-cooled reactor design with some innovative design features.
16 Next slide, please?
17 So, just to start off with this, the GDC-27 states the reactivity 18 control system shall be designed to have a combined capability in conjunction 19 with poison addition by the emergency core cooling system of reliably 20 controlling reactivity changes to assure that under postulated accident 21 conditions and with appropriate margin for stuck rods, the capability to cool 22 the core is maintained.
23 So, a long-term core cooling is the key here with reactivity 24 control.
25 Next slide, please?
26 So, the staff has historically interpreted the intent of GDC- 12 1 27 to require that the reactor be reliably controlled in normal operation and 2 also achieve and maintain a safe shutdown condition, including subcriticality 3 beyond the short-term using only safety-related equipment following a design 4 basis event with margin for stuck rods.
5 What that really means is, under Chapter 15 assumptions, 6 a DBE scenario is one of the most high worth control rods would fail to insert.
7 There'd be an assumption of loss of offsite AC power and any non-safety 8 system will not work, in particular, the non-safety boron injection system would 9 be unavailable.
10 In the NuScale design, that leads to a return to power above 11 decay heat levels only when you have the moderator temperature coefficient 12 is sufficiently negative and the reactor core temperature gets low enough.
13 So, under those conditions, staff felt there was a need for 14 an exemption request. Staff informed NuScale of that exemption request will 15 be required for its reactor design.
16 Next slide, please?
17 So, NuScale submitted the request for the exemption on 18 GDC-27. The staff came back, or and I should say, it should be recognized 19 that many times, exemptions to current GDCs may be needed as design 20 changes or innovations are proposed.
21 So, staff came back and plans to evaluate whether the 22 NuScale design meets the underlying intent of the GDC and assures public 23 health and safety based on two key criteria.
24 The first being that it demonstrates sufficient core cooling.
25 What this really means is the staff is coming through to assess the results of 26 the NuScale safety analysis of the assumed design basis accident scenarios
13 1 against established, specified, acceptable fuel design limits. I'm going to 2 come back and use the word SAFDL. So, I thought I'd say it at least once.
3 Right?
4 But, essentially, fuel design limits have to be maintained in 5 the long-term.
6 Secondly, the staff felt that the design basis accident 7 sequence of events should not be expected to occur during the lifetime of a 8 module.
9 And, just a parenthetical here, Commission will make the 10 final determination of the acceptability of the NuScale exemption. So, this 11 essentially in preparation for that discussion.
12 Next slide, please?
13 Under the topic of maintaining the long-term core cooling, to 14 assure long-term core cooling, we, that is the ACRS, expect that NuScale will 15 perform an evaluation to ensure the SAFDLs fuel design limits are not 16 exceeded for any of the DBE scenarios considered.
17 And, we think the analyses would conclude consideration of 18 operator actions, estimates of the return to power and the associated 19 strategies to return to a subcritical condition and assurance that the margin 20 does not degrade over the duration of the event.
21 Next slide, please?
22 In terms of low probability of return to power, the staff's 23 evaluation criteria, we came back and felt there should be additional criteria 24 to augment what is proposed.
25 First, that an assessment of the incremental risk to the 26 public health and safety from the hypothetical situation.
14 1 And, secondly, that the risk increase is acceptable but it 2 considers the entire NuScale facility, not just a single module.
3 So, those are the two things that we've come forward to and 4 what we feel ought to be augmented in terms of criteria.
5 I'll only mention here that, inclusion of the risk evaluation or 6 risk acceptance really is line and consistent with Reg Guide 1.174.
7 Next slide, please?
8 So, for low probability of return to power, the non-safety 9 SSCs that provide boron addition should also have certain characteristics.
10 They should not degrade during plant operation and they should function 11 reliably when called upon including operator actions that are needed for 12 startup and their alignment.
13 So, our conclusion and recommendation is to propose 14 criteria reasonable for judging the exemption request provided the following 15 recommendation enhancements are made.
16 One, that we evaluate the overall risk, not just the frequency 17 of the challenge.
18 And, secondly, that the risk consideration should be based 19 on the facility rather than any individual module.
20 Okay? Thank you very much. So, I'll turn now to Member 21 Stetkar and he's up for a couple of discussions with you on topics.
22 MR. STETKAR: Great, thank you.
23 May I have the first slide, please?
24 The first topic I'm going to discuss is Revision 3 to Reg 25 Guide 1.174.
26 This Reg Guide describes the key principles and guidance
15 1 for the use of risk information in regulatory decisions.
2 Over its life, it's become the fundamental reference for use 3 of risk information by both the staff and the industry. So, it's one of the key 4 Reg Guides that this organization has developed.
5 One of those five key principles for integrated decision 6 making is that a proposed change should be, quote, consistent with defense 7 in depth philosophy.
8 And, historically, both industry and the staff have had 9 difficulties with understanding what is needed to demonstrate how that 10 principle has been satisfied.
11 So, the primary impetus for Revision 3 to the Reg Guide is 12 to clarify the guidance for how defense in depth should be considered by both 13 an applicant and the staff.
14 Next slide?
15 As part of the SMR on SECY-15-0168 which was the 16 Commission's SECY -- the Commission's SRM on the recommendations for 17 the risk management regulatory framework in NUREG-2150. I'm sure you're 18 all familiar with these SECY numbers.
19 The staff actually directed the -- the Commission directed 20 the staff to expedite this Revision 3 to the Reg Guide.
21 We conducted four Subcommittee meetings on Rev 3 to the 22 Reg Guide between May 2016 and August of last year. And, we had 23 previously reviewed what is, if you haven't read it, read it, an excellent NUREG 24 knowledge document on the defense in depth philosophy NUREG/KM-0009 25 as part of our deliberations on the risk management regulatory framework.
26 We spent quite a bit of time studying that document. And,
16 1 it is an excellent compilation of the history of defense in depth in this Agency.
2 Next slide?
3 We recommended that Revision 3 of Reg Guide 1.174 4 should be issued. And, in fact, it was issued in January.
5 We noted that it substantially expands and clarifies the 6 guidance for consideration for defense in depth and its integration with the 7 other risk informed decision making principles.
8 Revision 3 also clarifies the staff's intent for determining the 9 technical acceptability of a PRA for use in these types of risk informed 10 decision. And, it enhances the guidance on evaluation and treatment of 11 uncertainties.
12 Next slide?
13 We understand that the staff plans a future Revision 4 of 14 Reg Guide 1.173 to expand the guidance on integrated decision making, and 15 in particular, the use of uncertainly as an input to the decision process.
16 And, in our letter, we also encouraged the staff to consider 17 extending the guidance to address applications of risk information for new 18 reactors which may have much different risk profiles and overall lower levels 19 of risk in currently operating reactors.
20 That concludes my discussion of Reg Guide 1.174. I'm 21 going to continue with the next topic which is the State-of-the-Art Reactor 22 Consequence Analysis project for Sequoyah.
23 Next slide?
24 The first two SOARCA studies were performed for the 25 Peach Bottom and Surry reactors. The original studies used so-called point 26 estimate values in the calculations without an evaluation of the uncertainties.
17 1 Subsequent to publication of the original studies, the staff 2 went back and performed what I'll called focused uncertainty analyses for a 3 small number of selected scenarios in those studies.
4 Next slide?
5 However, in most cases, the uncertainties in those focused 6 studies were retrofit around the point estimate values. In other words, the 7 staff essentially backfit an uncertainty analysis.
8 Those focus studies, however, demonstrated the 9 importance of addressing uncertainties and that consideration of the 10 uncertainties can affect the understanding and overall interpretation of the 11 results. That was an important finding from those focused studies.
12 Next slide?
13 The Sequoyah study does two things, first of all, it extends 14 the scope of the SOARCA project to address a PWR with an ice condenser 15 containment, because it's a much different containment than either of the other 16 two plants that were examined.
17 And, because of that, it's intended specifically to examine 18 the effects of hydrogen generation and release, the timing and locations of 19 ignition and containment vulnerability to failure caused by a highly energetic 20 deflagration. Hydrogen issues have always been a larger concern in these 21 ice condenser type of containment. So, the staff focused primarily on that 22 issue.
23 Next slide?
24 The Sequoyah study evaluates the plant response to one 25 short-term station blackout and one long-term station blackout. And, again, 26 I'm sure you're intimately familiar with this, but a short-term station blackout
18 1 means that all AC power is lost at the beginning of the event and any cooling 2 or injection systems that rely on AC power are also disabled. So, everything 3 is gone at time T0.
4 A long-term station blackout allows equipment that does not 5 rely on AC power to run until, for example, the station batteries are depleted.
6 So, long-term station blackout, you lose core cooling or injection capability 7 anywhere from two to eight hours after the event, depending on the life of the 8 station batteries and so forth.
9 The Sequoyah study assumes that each scenario is caused 10 by a severe earthquake. That's important, the Surry and Peach Bottom 11 studies also did that as just one way of losing electric power.
12 But, in particular, in the Sequoyah study, the models for 13 offsite emergency response explicitly account for that seismic damage to the 14 local infrastructure so that the evacuation planning, there are delays in 15 evacuation planning due to damage to the infrastructure.
16 Local bridges over the rivers in that area are disabled by the 17 earthquake, in fact, in the models within I think it was a 10-mile radius that 18 they used. So, they've explicitly accounted both the onsite and offsite effects 19 from that earthquake which was not done at all in the Surry and Peach Bottom 20 studies.
21 The integrated evaluation of uncertainties for thermal 22 hydraulic is response and offsite consequences were performed for only the 23 station -- the short-term station blackout scenario. So, they didn't do an 24 integrated uncertainty analysis for the long-term blackout scenario.
25 ACRS engagement, we had three Subcommittee meetings 26 on the Sequoyah SOARCA study between May 2016 and October of last year.
19 1 And, we had a separate special Joint Subcommittee meeting in April of last 2 year to be briefed on changes to MELCOR and improvements to modeling in 3 MELCOR that were made specifically to address the hydrogen issues for the 4 Sequoyah study.
5 Next slide?
6 Our first recommendation and conclusion was that the 7 Sequoyah study has significantly advanced our understanding of severe 8 accident progression in a PWR with an ice condenser containment.
9 And, it clearly demonstrates the importance of an integrated 10 assessment of uncertainties about equipment performance from a hydraulic 11 phenomena and emergency planning.
12 Next slide?
13 As I mentioned earlier, the study evaluates site-specific 14 conditional consequences from two station blackout scenarios which have 15 been tailored to examine the effects from hydrogen generation ignition and 16 containment failure vulnerability.
17 It does not examine other scenarios that may be important 18 for containment failure or bypass.
19 Next slide?
20 It does not account for accident mitigation strategies that 21 have already been implemented at Sequoyah. So, therefore, it's a very 22 stylized study for even the Sequoyah plant as its operated today.
23 And, therefore, we noted that the results from this study 24 should not be extrapolated to other PWRs with ice condenser containments 25 and certainly not for other sites.
26 Next slide?
20 1 Our third recommendation was that the Sequoyah report 2 should be published after the staff more clearly documents the following three 3 issues.
4 The first was the treatment of potentially important modeling 5 uncertainties.
6 A better technical justification for failure rates for, in 7 particular, pressurized or safety valves. Those failure rates are the likelihood 8 that a valve that opens remains stuck open. And, if it does remain stuck 9 open, how far does it remain stuck open? And, that's a very important 10 parameter in this particular study.
11 And, a better discussion of the reasons for failures to 12 complete some of the MELCOR simulations that involved an early stuck open 13 pressurizer safety valve, though, that particular condition was found to be very 14 important for the conditional likelihood of an early containment failure.
15 And, a reasonable fraction of the MELCOR runs within that 16 particular regime of the plant response failed to complete. And, we asked 17 that the staff do some better forensics in terms of understanding why and 18 whether or not the runs that failed to complete would affect any overall 19 conclusions from the study.
20 Next slide?
21 We also recommended that the staff should examine and 22 resolve the issues regarding the safety valve failure rates that I just mentioned 23 and this MELCOR performance before any further enhancements are made 24 to the other SOARCA studies at Surry and Peach Bottom in particular.
25 And, finally, the staff has responded to our letter. We've 26 been informed that the final report strongly emphasizes that the study is
21 1 specific to only Sequoyah.
2 The staff has indicated that the report will acknowledge that 3 an evaluation of model uncertainty is outside of the scope of this particular 4 study.
5 The report contains enhanced discussions of the safety 6 valve failure rates and insights from actually quite an extensive amount of 7 forensics that were done on those incomplete MELCOR runs to provide 8 improved assurance that nothing was lurking there that was unexpected.
9 And, the staff has also indicated that they will further 10 address the safety valve failure rate issues in the planned updated Surry 11 uncertainty analyses.
12 That's the end of that topic.
13 DR. CORRADINI: So, we'll turn to Dr. Powers.
14 DR. POWERS: We'll shift gears a little bit and move to the 15 discussion of Northwest Medical Isotopes proposal to build a -- for a 16 construction permit.
17 They propose to develop a facility for producing the medical 18 isotope moly-99. I believe this has been declared a national priority to have 19 a national source for this material to be sure it is one of the most widely used 20 of medical isotope.
21 When you first look at the Northwest Medical Isotope, there 22 seem to be a lot of moving parts in their proposal, almost Rube Goldberg type 23 of strategy.
24 As you get into it and look at it, you say, gee, this process 25 may actually work. And, the reason it may work is that they are not relying 26 on either an engineering or a scientific breakthrough. They have selected a
22 1 variety -- collaboratively selected a variety of established processes.
2 And, though we can't underestimate the challenges of a first 3 of a kind engineering of known processes, it looks like it's a very feasible 4 undertaking.
5 What they have asked for is a construction permit for a 6 facility that will allow them to fabricate uranium targets and subsequently 7 process those targets. The targets themselves will be irradiated at some 8 university research reactor, certainly one in Missouri, maybe one in Oregon 9 and maybe elsewhere.
10 My personal belief is that there are no good ways for 11 chemically processing special nuclear materials. We have found ways that 12 will work, but they require a great deal of discipline and attention to conduction 13 of operations.
14 The hazard of processing special nuclear materials, well, 15 always you have criticality hazards. Northwest Medical Isotopes proposed to 16 handle these with a relatively classic mixture of design and double 17 contingency principle safety strategies.
18 The hazard to the public from this processing facility is the 19 release of radionuclides. They can released radionuclides during the 20 dissolution of the targets after they've been irradiated that will release volatile 21 radionuclides.
22 They propose to capture those on an assembly of activated 23 charcoal and silver modified zeolites. That is a known process that will work.
24 The overall design, of course, is a classic nested loops of 25 contamination zones.
26 The threats to the facility, well, fire. They have fire
23 1 potentials of electronic nature, fire potentials for organic materials. They do 2 have some hydrogen processing materials and have an interesting fire hazard 3 associated with uranium metal upon the receipt of special nuclear material for 4 the fabrication of targets.
5 The external threats to the facility, aircraft impact, seismic.
6 They have an interesting high-frequency seismic that doesn't threaten the 7 structural material structure of the facility but does threat its internals. And, 8 of course, high winds in the area of country where it will be, tornados is a 9 primary concern there. All these seem to be well-addressed.
10 Our review consists primarily of explaining and elucidating 11 how they must finalize their design in order to meet the requirements for 12 licensing.
13 Our conclusion was that it should be possible to construct 14 and operate this processing facility in such a way that it poses no undue risk 15 to the public health and safety and we recommended that they be given a 16 construction permit.
17 DR. CORRADINI: And, finally, Dr. Rempe.
18 DR. REMPE: Thank you.
19 So, I'd like to discuss our biennial review and evaluation of 20 the NRC's Safety Research Program.
21 The ACRS has provided formal reviews of the NRC's Safety 22 Research Program since 1977. As Mike indicated in his opening remarks, 23 we did change the process that we use as well as the format of our report this 24 year, but we still address all of the items identified in the Commission's 1997 25 guidance to us.
26 We look at the need, scope and balance of the reactor
24 1 safety research program, the progress of ongoing activities and how well the 2 Office of Nuclear Regulatory Research positions the Agency for the future.
3 But, in our 2018 review, we also emphasized the 4 identification and prioritization of new research needs, longer term planning 5 activities by RES and providing the Commission a more succinct report.
6 These additional items were motivated by comments that 7 you provided in our October 2016 meeting as well as our desire to provide a 8 better product to the Agency.
9 The information that you'll find in our 2018 report was 10 developed based on our review of reports issued by the Office of Nuclear 11 Regulatory Research as well as the items listed on this slide.
12 We started with an initial meeting with Mike Webber, the 13 Director of RES.
14 We then held three working group meetings with each 15 director of each division within RES.
16 And then, we had gained insights from our normal ACRS 17 activities, our periodic reviews of research projects of special importance, our 18 reviews of research that impacts regulatory processes and our annual quality 19 reviews.
20 In the next six slides, I'm going to highlight some of the 21 information you'll find regarding the activities being performed within each 22 division within RES.
23 Starting with the Division of Risk Analysis, you'll find several 24 comments about various projects that they have underway.
25 For example, the Level 3 PRA, we observe, is a good 26 example of research that preserve staff skills and Agency tools as well as
25 1 advances to the state-of-the-art with respect to risk assessment.
2 We also provided several comments about the ongoing 3 IDHEAS effort which we followed with periodic reviews during our 4 Subcommittee meetings.
5 In the letter report, we, again, emphasized the guidance that 6 we're giving the staff regarding the need to move forward with developing a 7 coherent articulation of this method that'll provide a unifying basis for human 8 reliability and meet the intent of the SRM issued on this topic.
9 In our comments for each division, you'll find general 10 comments that are actually applicable to all divisions within RES.
11 For example, in our discussion of DRA, we observe it's not 12 clear to us how research priorities accounted for integrated consideration of 13 enterprise risk.
14 And, by this term, we're talking about the need for an 15 integrated evaluation that considers factors such as safety and security, 16 emerging issues, innovative technologies and associated uncertainties, 17 preservation of core competencies and development and maintenance of 18 analysis methods and tools.
19 In our discussion of the Division of Systems Analysis, we 20 first emphasize the importance of the Agency having an independent reactor 21 safety analysis capability.
22 Our letter report describes several ongoing activities to 23 improve and apply DSA computer codes, codes for analyzing fuel 24 performance, FRAPCON, FRAPT as well as evaluating accident progression, 25 TRACE and MELCOR.
26 We noted that, in light of the Agency's heavy reliance of
26 1 severe accident methods, that the Agency should consider identifying and 2 supporting consequence analysis as a core competency.
3 In our discussion of DSA, we observed that, in light of the 4 current and future projects regarding Agency resources, that difficult strategic 5 choices are required to maintain current computational capabilities and core 6 competencies and to anticipate and adapt to future regulatory needs.
7 Our discussion offers several solutions to assist DSA in 8 optimizing resources as they make these difficult choices.
9 And, I would observe that many of those possible solutions 10 are broadly applicable to all divisions in DSA.
11 In our review of the Division of Engineering, we also provide 12 comments regarding ongoing activities.
13 For example, we emphasized the importance of computer 14 codes they've developed for assessing material performance, xLPR and 15 FAVOR, for example.
16 We also encourage the staff to accelerate their reviews of 17 ASME codes and ASTM standards. And, we observed that delays in the 18 reviews and approvals of those codes and standards often leads to additional 19 work by the Agency as well as industry.
20 And, finally, I wanted to emphasize our comments regarding 21 the need for a risk evaluation prior to embarking on any additional spent fuel 22 dry storage cask research.
23 And, this stems from our belief that there is not a risk basis 24 for providing any additional research in that area.
25 Our review of DE also identified several examples that led 26 to general comments.
27 1 For example, we encourage the staff to focus on identifying 2 data that licensees or applicants should provide rather than independently 3 developing such data.
4 We also emphasized the need for an effective process for 5 terminating ongoing research when it ceases to be a high priority.
6 And, finally, I just wanted to highlight our conclusion and 7 recommendations that you'll see in our letter report. They are related to 8 integrated research priorities by the Agency.
9 First, we emphasize that it appears to us that the Safety 10 Research Program is meeting near-term Agency needs.
11 However, we emphasize that a systematic assessment that 12 emphasizes enterprise risk might be improving the processes that is used by 13 the staff in selecting research projects, evaluating as well as determining when 14 they should be terminated.
15 We observe that results from that systematic assessment 16 could assist the Agency in developing longer term strategies to address 17 emerging technical issues, support development to maintenance of needed 18 analytical tools and databases, emphasize activities that improve regulatory 19 efficiency, and identify and preserve needed core competencies.
20 Thank you.
21 DR. CORRADINI: Questions?
22 CHAIRMAN SVINICKI: Thank you for those presentations 23 and for the other letter reports that the Committee produced over the last six 24 months or so.
25 We will begin the Commission's question period with 26 Commissioner Burns. Please proceed.
28 1 COMMISSIONER BURNS: Well, thank you.
2 Thank you for the presentations and the opportunity, again, 3 to engage with the ACRS in the Commission meeting. I find it valuable and I 4 think enjoy the presentations and the dialogue we have both formally in this 5 context as well as in our -- some of our drop-in meetings with the individual 6 members.
7 Maybe I'll just sort of go down the row in the order and I'll 8 start with you, Dr. Corradini.
9 With respect to the NuScale exemption, you know, you 10 noted the Committee's recommendation the staff's evaluation criteria to be 11 augmented to include an assessment of the overall risks of the hypothetical 12 re-criticality scenario and that other risk considerations should be based on 13 the facility rather than a single module.
14 The staff has provided a response. It may well be that 15 you're in the process of reviewing that, but I just -- any point at this time, does 16 the Committee feel that the staff is being responsive to the recommendations?
17 DR. CORRADINI: Yes, I kind of -- we kind of anticipated 18 this might pop up.
19 COMMISSIONER BURNS: Okay.
20 DR. CORRADINI: So, we just got the note back from the 21 EDO on that and the staff and we've not -- in the reconciliation process, we're 22 actually going to go over at this meeting.
23 But, they have basically accepted the idea of adding a 24 criterion in this area and considering the full facility.
25 We haven't seen the revised paper that is the paper you're 26 going to see.
29 1 COMMISSIONER BURNS: Yes.
2 DR. CORRADINI: But, my anticipation is they'll follow 3 through on that. And, we think it's near completion.
4 So, we'll just simply assess that when it comes back and we 5 see the added criterion. The thought process is, is that with the added 6 criterion, we'll just wait for the safety analysis process under Chapter 15 and 7 see how NuScale does the analysis and how staff's safety evaluation of it.
8 But, at least, as far as we can see, staff is okay with our 9 suggestions.
10 COMMISSIONER BURNS: Okay, good.
11 One other area with respect to NuScale, the letter that came 12 back on, I think, GCD-27 issue noted that some members had reservations 13 about the exemption.
14 I think this focused on, and again, I'm not the technical guy, 15 I'm the lawyer, so forgive me on some of this.
16 But, I think the letter discussed the view that re-criticality 17 beyond the short time span of what is currently allowed should not be tolerated 18 under any circumstance.
19 And, is there under the current circumstances for existing 20 currently licensed reactors, are there circumstances in which we allow --
21 DR. CORRADINI: Yes.
22 COMMISSIONER BURNS: -- re-criticality?
23 And, how does this NuScale scenario differ from there?
24 DR. CORRADINI: Okay, so, I'll try parts of this and then I'll 25 get nudged by my colleagues if I stray.
26 COMMISSIONER BURNS: Okay.
30 1 DR. CORRADINI: So, under -- I mean, the one example 2 that immediately pops in my head under current reactors is main streamline 3 break.
4 I can get into a situation where I essentially have a quick 5 cooling event.
6 COMMISSIONER BURNS: Okay.
7 DR. CORRADINI: And, under certain conditions of fuel 8 loading, I can essentially become re-critical, and that's allowed for the short-9 term. Okay? Short's not defined, but we're talking -- we'll say of the order 10 of minutes to --
11 COMMISSIONER BURNS: Yes.
12 DR. CORRADINI: -- okay, less than an hour.
13 COMMISSIONER BURNS: Okay.
14 DR. CORRADINI: In this scenario, under the -- in this 15 situation, with this design under Chapter 15 assumptions, as I kind of went 16 through in terms of essentially no -- only safety-related equipment can be 17 allowed to operate, consider single failure criterion, loss of all offsite power.
18 That, essentially, disables, based on assumption, their non-19 safety grade boron injection system. So, given that they're late in the cycle, 20 given that the low temperature, you would have a return to power and be a 21 modest amount.
22 But, nonetheless, a return to power and you'd be not 23 subcritical. And, they cannot take credit for their boron injection system.
24 So, that's what led the staff to say they cannot, under their 25 interpretation of GDC-27, allow for without an exemption request.
26 COMMISSIONER BURNS: Okay.
31 1 DR. CORRADINI: Now, after that point, we, the 2 Committee, has not seen any analysis of the details of that. We've heard 3 from both staff and from the applicant that there's various, I'll call possibilities 4 and sequences where this can occur.
5 But, I think on both sides, it's a low power event. The 6 feeling is, is, and again, I'm just going to go back to the letter, to the extent 7 that you can show long-term cooling and removal of the heat and satisfy in the 8 specified acceptable fuel design limits, then you should be okay.
9 That's the staff's criteria going into the analysis.
10 COMMISSIONER BURNS: Okay, okay, good.
11 DR. CORRADINI: I'm going to look to other members to --
12 because there were members that felt that, under all circumstances, it doesn't 13 matter, it's got to be subcritical.
14 COMMISSIONER BURNS: Oh, okay, all right, thanks.
15 And, I'll move on to John Stetkar here.
16 And, one of the discussions on the Reg Guide 1.174, the --
17 you talk about the Committee's recommendations regarding future revisions, 18 including consideration of extending the guidance to new reactors, or I guess, 19 advanced reactors, we don't have that dichotomy in some respects.
20 If -- are there any general principles or general criteria you 21 think the staff might follow in considering future changes to address that new 22 set of reactors or the advanced reactors?
23 Given what, you know, part of the pitch we're getting is the 24 assumably, presumably lower risk profile for them?
25 MR. STETKAR: I think that, and we've actually written on 26 this a few years ago in the context of reactor oversight process for new
32 1 reactors.
2 The basic principles of risk informed decision making should 3 read, in my opinion, should remain unchanged. They're fundamental 4 principles, so there's nothing that's unique to a new reactor.
5 The difference is that, if you look at the risk, I don't want to 6 call them acceptance criteria, if you're familiar with the Reg Guide, there are 7 two figures in the Reg Guide that look at change in core damage frequency 8 versus absolute core damage frequency and change in large early release 9 frequency as a function of large early release frequency.
10 And, if you're within certain margins, you're allowed a larger 11 margin if you have a lower core damage frequency. If you have a higher core 12 damage frequency, you're allowed less margin.
13 Those criteria, those, not criteria, were developed based on 14 an understanding of kind of the risk of currently operating reactors.
15 So, for example, they don't extend to very low absolute 16 frequencies and it's not clear how you would extrapolate those margins to new 17 plants that have very low projected core damage frequencies or large release 18 frequencies.
19 So, the primary impetus from our recommendation is to get 20 the staff to think down in those smaller regimes. And, in fact, we've already 21 heard from -- we've written a letter on this -- from NuScale where they're 22 proposing certain criteria using Reg Guide 1.174 --
23 COMMISSIONER BURNS: Okay, okay, yes.
24 MR. STETKAR: -- as a basis for what are their accepted 25 marginal criteria down in very low core damage frequency ranges?
26 So, it's an area that's ripe as we come into new reactor
33 1 designs. We've seen experience from NuScale, we've seen experience from 2 some of the existing completed design certifications where different applicants 3 have applied different interpretations of what those marginal criteria may 4 mean.
5 And, if you're not careful, you're going to get into a situation 6 where you'll have individual assessments based on ad hoc reviews on a case 7 by case basis.
8 So, our recommendation is focused in that way. You get 9 the staff and the industry thinking about exactly how those margins will be 10 extrapolated to very low frequency areas.
11 COMMISSIONER BURNS: Okay, and thank you, that's 12 helpful.
13 I don't have any particular questions on the Northwest 14 Medical Isotopes. We are, as a body, we have it -- we had our mandatory 15 hearing that, obviously, took into account staff testimony, applicant testimony, 16 and the ACRS considerations before us. But, I do appreciate the 17 Committee's work on that.
18 I think it's interesting, we mentioned it this week since the 19 NRU reactor up in Canada, I think, closed down over the weekend or just early 20 this week. So, the issue, and I think I've mentioned before when I was at 21 OECD, this whole question on, you know, the -- on isotopes, you know, 22 availability across the world for medical applications. It's an important one.
23 DR. POWERS: It's an exciting area.
24 COMMISSIONER BURNS: Yes.
25 DR. POWERS: And, just surprises you how ubiquitous the 26 use of this isotope is for --
34 1 COMMISSIONER BURNS: Yes.
2 DR. POWERS: -- medical imaging.
3 And, here, you have a proposal for doing it, interesting and 4 --
5 COMMISSIONER BURNS: Yes.
6 DR. POWERS: -- imaginative, cleverly done. But, they're 7 a long ways away from a finalized design, but it looks promising to us and it 8 can be done safely.
9 COMMISSIONER BURNS: Thank you, Dr. Powers.
10 And, if I could, with my colleagues indulgence, I just want to 11 ask Dr. Rempe, I appreciate the report.
12 I know, you know, this is a first shot in terms of trying to do 13 a refined report. Were there any sort of lessons learned or particular 14 challenges you all had in this different formatting?
15 Obviously, the first time you do anything like this, you're 16 trying to breakaway but any sort of insights from the work of coming up with 17 this version?
18 DR. REMPE: Well, these are my comments, not --
19 COMMISSIONER BURNS: Sure, sure.
20 DR. REMPE: -- discussed it as a Committee.
21 COMMISSIONER BURNS: That's fine.
22 DR. REMPE: But, from my perspective, I think it was useful 23 because more of the ACRS members became knowledgeable about the 24 research.
25 COMMISSIONER BURNS: Oh, good.
26 DR. REMPE: It was more a consensus comments and
35 1 recommendations. And, I think, again, it's not -- I've been on the Committee 2 now almost eight years, but I think it's more helpful for Committee members 3 to learn about that research and do this more as a collegial body.
4 I also, I didn't have -- I was afraid I'd run out of time, but I 5 really think we should thank the staff of RES. They were willing to come meet 6 with us and have frank discussions about their research. And, I think that 7 that's something that's necessary for this approach to work.
8 COMMISSIONER BURNS: Great, thank you.
9 Well, again, I thank Dr. Powers and John Stetkar for their 10 service on the Committee and appreciate all the work that you've done as well 11 as your colleagues in the presentation -- discussing the presentations today.
12 Chairman?
13 CHAIRMAN SVINICKI: Well, thank you.
14 I will go next. And, again, I appreciate all the presentations 15 and letter reports that have been produced. I will focus, I think, on the 16 presentations that have been given here today.
17 I'll begin with the NuScale exemption request. I -- this is a 18 little bit of a variation on what my colleague had talked about.
19 He did talk about the statement in the letter report that some 20 of the members had serious reservations about granting an exemption and 21 felt that it shouldn't really be tolerated under any circumstances.
22 But, I would also note that the letter report itself, in the 23 discussion section, states that it's been recognized for some time now that 24 exemptions to the current general design criteria may be needed as design 25 innovations are proposed based on improved knowledge and decades of 26 reactor operating experience.
36 1 Such exemptions must be possible if reactor technology is 2 to advance.
3 So, of course, I reviewed the letter report in light of the 4 specific matter which is the NuScale particular exemption request. But, it's 5 hard not to reflect more broadly on both the NuScale design aspects of design 6 innovation and novelty that it presents in addition to the exemption request.
7 And then, to pivot more broadly to truly advanced reactors.
8 And, we make this distinction that, in comparison to some of what is 9 contemplated in truly advanced reactor space, the NuScale design is actually 10 a bit mundane and humdrum and rather conventional in light of what NRC may 11 have to confront in the future.
12 I have read the staff's response to the ACRS comments, but 13 I find the additional views of ACRS Member Dimitrijevic having a closer 14 alignment, I think, with where I am on this. And, I think that she cautions us 15 with some peril about approaches to innovation and the technology.
16 And, actually, pulling way back reflecting on her views, the 17 letter report and, broadly, the advanced reactor space where the Commission 18 has constant engagement with members of Congress, with policymakers, 19 broadly, those looking at the energy future of the United States.
20 I encounter, and I think my colleagues do as well, often 21 concerns about NRC's ability to pivot appropriately from some of the 22 paradigms of large light water reactors and the very, very comfortable body of 23 knowledge that we've grown up around that and apply our nuclear safety and 24 security paradigms to what is likely to come before us in advanced reactor 25 space.
26 And, I thought that Member Dimitrijevic was cautioning us
37 1 about that, to the effect, she didn't have a dissenting view, she just had 2 additional comments. But, I shared her cautions and concerns and not her 3 view, but my own, as I thought about all of this was, and thought about Dr.
4 Powers and Mr. Stetkar leaving the Committee.
5 And so, there are Committee members of long service that 6 I've engaged with over the course of my time on the Commission made me 7 wonder about your predecessors going back to the Atomic Energy 8 Commission, and if they had held to some of the paradigms that I think are 9 reflected in the members who say, no exemption from a GDC is ever 10 appropriate.
11 If they had held that view, I question whether the United 12 States would ever have had a nuclear power program.
13 Because, the body of knowledge at the time was such that 14 they had to seek the fundamental levels of confidence that would allow us to 15 be assured of the safety of the American public.
16 But, I don't think that they had the luxury of continuing to 17 tack down all the tail end curves of risk that we, I think, have grown 18 accustomed because we have been regulating for some decades now large 19 light water reactors and its technology that we've become so familiar with.
20 So, I caution us along those lines. I think it's important to 21 remember, if had been the NRC staff, I might have resisted your 22 recommendations and it doesn't matter, because they've taken a view. But, 23 I, and has other members of the Commission have to -- I confront --
24 This is the one that's developed a little folklore and I'm not a 25 car person, so I might get it wrong.
26 But, it is, you know, I think NRC is going to require that
38 1 Teslas, you have catalytic converters or carburetors or whatever component 2 of vehicles today that's not relevant to Teslas. You pick your flavor, we get 3 variations on that.
4 And, where the staff is demonstrating that they are not going 5 to require Teslas to have things not relevant to Teslas, I think that that is a 6 needed approach that I'm afraid that the ACRS advice kind of beats them back 7 from exhibiting that kind of openness to innovation in science and technology 8 which is imperative if the country is to have nuclear going forward.
9 So, that's my comment on that.
10 Dr. Powers talked about how exotic the Northwest Medical 11 Isotopes, that and also the SHINE technology the staff, the NRC staff had to 12 exhibit a lot of applied approaches of the regulatory framework.
13 And, you know, risk informing has been described to me, I 14 don't know how you all talk about it and risk is not my -- really my background 15 or my resume, but it's kind of this set of questions. It is, what can go wrong?
16 How likely is it? And, what are the consequences if does happen?
17 I mean, I don't know, we've got all kinds of elaborate 18 expertise around it, but at bottom, those are the sets of questions that the staff 19 has to answer, whether it be for Northwest Medical Isotopes or NuScale or for 20 truly exotic things to come.
21 And so, I appreciate that work that's been done on the 22 updating of 1.174. I think we continue to move forward.
23 But, the staff has some uncomfortable paradigms to shift 24 going forward. And, I think that, you know, the Committee's role is the 25 Committee's role. But, maybe if you were to look deep back into the ACRS's 26 history, I think that your predecessors might have had to confront what you
39 1 and ACRS members going into the future might have to confront which is, how 2 do we find the elusive sweet spots of confidence and risk informing ourselves 3 that allow technology to be innovated and advanced going forward?
4 So, Dr. Rempe, I'll just conclude by noting that you -- one of 5 the conclusions in the research review was that consequence analysis should 6 be a core competency.
7 I don't know if imbedded in that is this kind of a euphemistic 8 way that the Committee shares some of these concerns about answering the 9 third question of the risk triplet which is, how significant is it if it occurs? I 10 don't if that was what was intended by consequence analysis as the core 11 competency. Perhaps you could give me some feedback on that.
12 DR. REMPE: Absolutely. I'm referring to our ability to use 13 the MACCS Code to look at the effects of a radiological release, health and 14 safety doses, et cetera.
15 CHAIRMAN SVINICKI: Okay, thank you.
16 And then, broadly, I do appreciate that the Committee took 17 on modifying the format of the research review.
18 After I made comments about that in 2016 and then 19 engaged with you directly when the Committee decided it had an interest in 20 looking at the format of the much more detailed report that had previously 21 been written.
22 I was -- I met with -- well, he's here today, our current 23 Director of Nuclear Regulatory Research, Mike Webber. And, he reminded 24 me that another audience for the ACRS's research review has always been 25 the Research staff and the NRC staff more broadly, that they take in the 26 insights of the ACRS in the more detailed report had provided.
40 1 Are you confident that, in your engagement with the 2 Research staff you haven't lost their ability to take away benefit from the 3 Committee's broader insights, even if they're not necessarily captured in the 4 report itself?
5 DR. REMPE: So, I won't know until we hear back from the 6 staff with their official comments to the report.
7 But, I personally believe that a lot of that 80-page document 8 was boilerplate. I don't think the staff needs to have us describe what their 9 research projects are.
10 And so, I think we still do provide the recommendations that 11 were imbedded in that report. But, again, we'll hear back from the staff. It 12 was a first year -- or two year effort. It's the first time we've tried it.
13 And, I believe actually when I met with Commissioner 14 Baran, he said, you know, don't expect to get it right the first time. So, if we 15 hear some comments otherwise, we'll adjust accordingly.
16 CHAIRMAN SVINICKI: Okay, thank you.
17 Chairman Corradini, did you want to say something about 18 risk?
19 DR. CORRADINI: No, I mean, you were --
20 CHAIRMAN SVINICKI: There's a lot of byplay between 21 you and Mr. Stetkar.
22 DR. CORRADINI: You -- I was -- I didn't know if there was 23 a question coming in there. But, can I interject one piece of personal opinion?
24 You said something about the non-light water reactors in the 25 NuScale. I do think there's a principle that we've been asking NuScale, and 26 we're probably going to ask, if we ever get around to these new advancing, is
41 1 we're looking for either a combination of integral testing. And, it's in --
2 actually, it's in the Research report. Joy made a good point of it in the 3 Research report.
4 There's going to be times when there's going to be a lack of 5 data. We've got to get that experimental data.
6 Now, the experimental data doesn't have to be NRC's 7 directed data, but it's got to be there so that we're very clear that with these 8 advanced designs, whether it be the, I'll use your words, I liked them, the 9 humdrum NuScale version or the, we'll call them the supercharged non-light 10 water reactor versions, you've got to get the experimental data that validates 11 what we expect to be the required performance.
12 And, that's probably one of the things that's -- I don't think 13 Joy mentioned in her discussion, but it's definitely in the Research report, that 14 it's important.
15 CHAIRMAN SVINICKI: I appreciate that. And, it is good 16 we talked about the need for those documents.
17 DR. CORRADINI: But, meant you didn't do it orally here, 18 but it's in the report.
19 DR. REMPE: Actually, it was mentioned today.
20 (LAUGHTER) 21 DR. REMPE: It's under DE discussion, yes.
22 CHAIRMAN SVINICKI: Okay, well, I appreciate that.
23 And, I think, in future engagements between the Commission and the ACRS 24 and the ACRS and the staff, there are a lot of questions being asked about 25 how much independent research does the NRC have to actually conduct going 26 forward?
42 1 I think that that's -- there's' broad uncertainty about the time 2 that it would take, the necessity of it and the -- just the overall scope of what 3 NRC will want to redo independently when it comes to that.
4 And then, a prong of that is the development of NRC Codes 5 by themselves as opposed to just doing validation work with Codes that are 6 utilized by others.
7 So, I think not a topic for today, but I think that that will be 8 an active area for the ACRS to look at the staff to develop approaches and 9 then the Commission to decide its level of comfort with that.
10 DR. CORRADINI: It's funny you mention that, I was going 11 to -- I didn't say that earlier, but I think you're point here is important which is 12 that, if there are new advances by industry or the DOE in some collaborative 13 way, I think we've got to look at them, whether it be in thermal hydraulics or in 14 reactor physics, et cetera, so that we understand if there's some advance, 15 then we have to understand how good it is and how it can be applied.
16 CHAIRMAN SVINICKI: Okay, thank you.
17 And, with the indulgence of my colleagues, after 18 Commissioner Baran gives his remarks, I would like to request that Member 19 Stetkar and Member Powers share any thought that they would like to share, 20 and I might ask you to think along the lines of, is there any caution that you 21 would you would offer the broad enterprise going forward as you leave your 22 service on the ACRS?
23 Thank you.
24 Commissioner Baran?
25 COMMISSIONER BARAN: Thanks.
26 Well, I think the discussion so far on the NuScale reactivity
43 1 control exemption request has been interesting. I have a few follow up 2 questions on that.
3 Taking a step back, the issue, as I understand it, is that 4 under certain design basis event scenarios, namely there's a loss of offsite 5 power and you have a single stuck control rod that fails to insert.
6 The reactor would shut down safely, but then return to 7 power potentially for an uncertain period of time so that you could have a 8 situation where, under those circumstances, the reactor wouldn't stay 9 completely turned off. Is that essentially the issue?
10 DR. CORRADINI: Under Chapter 15 assumptions, that 11 possibility does exist, yes.
12 COMMISSIONER BARAN: And, the Chairman talked a 13 little bit about the need to, particularly in advanced reactors, there's a whole 14 look at the GDC and what are the principle design criteria that would make 15 sense in a non-light water reactor context versus what we had with the light 16 water reactors.
17 Here, I'm not sure I really see that as being the situation 18 because there's nothing about the NuScale design that would make reactivity 19 control unimportant, is there? I mean, that's still a relevant factor for a 20 NuScale design, the general design criteria generally?
21 DR. CORRADINI: I guess this is -- I want to stay with the 22 letter report, so I'm going to simply state it this way which is to the extent that 23 you can remove decay heat or thermal power and maintain core coolability or 24 cool -- core cooling, that's the -- that's essentially the criteria the staff is 25 addressing in terms of their criteria comparing it to the NuScale design.
26 COMMISSIONER BARAN: Okay. And, there was a --
44 1 you had some discussion with Commissioner Burns about cases where there 2 have been -- the staff's found acceptable short-term in the range of minutes, 3 less than an hour, reactivity.
4 Are there any cases where NRC has licensed a power 5 reactor that might not remain subcritical beyond the short-term? Is this -- is 6 that aspect of it new in the NRC experience?
7 DR. CORRADINI: I'm not familiar of anything.
8 COMMISSIONER BARAN: And, the Committee's letter 9 said that basically, the reactor, in this scenario if it were to occur, would remain 10 critical until an alternate means of reactivity controls actuated.
11 And, I -- is that likely that there would be operator actions to 12 actuate the non-safety related boron injection system that's --
13 DR. CORRADINI: It wouldn't require -- if I might just --
14 COMMISSIONER BARAN: Yes.
15 DR. CORRADINI: -- clarify.
16 So, under Chapter 15 assumptions, you can't take credit for 17 that.
18 COMMISSIONER BARAN: Right.
19 DR. CORRADINI: But, automatically, you would 20 essentially initiate that, assuming it was available.
21 COMMISSIONER BARAN: Okay. So, this is a case in 22 which potentially a conservatism in the way you can take credit. You couldn't 23 take credit for it because it's not safety related. But, we think that's the thing 24 that they would turn to immediately in this situation?
25 DR. CORRADINI: He's jumping up and down.
26 COMMISSIONER BARAN: He wants to get in.
45 1 DR. POWERS: Yes, I may have a couple of things here.
2 Absolutely, you're running into a -- you set up some very 3 conservative requirements for your Chapter 15 analysis, and you're finding 4 you're running afoul of those. They're forcing you into a very conservative 5 position.
6 On the other hand, the licensee has gotten himself into this 7 position because he doesn't want to make his boron injection system safety 8 grade.
9 I mean, there's a conflict between advertising and 10 conservatism here.
11 It's --
12 COMMISSIONER BARAN: So, if it were safety related, 13 you could take credit --
14 DR. POWERS: -- kind of silly to get into --
15 COMMISSIONER BARAN: -- for it and you wouldn't have 16 this issue?
17 DR. POWERS: Yes, and certainly, we have many times 18 said that when the Chapter 15 analysis forces us into a very conservative 19 position and we are required to violate some rules for a short period of time 20 and not very badly, that's okay because they're very conservative. We've 21 done on several occasions.
22 Here, I think it's one that -- it's, you know, people want to 23 make -- say a plant is passive and so they absolutely refuse to make 24 something safety grade because they want it to be passive.
25 Well, that's silly and -- even there can be silliness on both 26 sides of this equation is my point.
46 1 COMMISSIONER BARAN: One of the Committee's 2 recommendations was to take a look at the incremental risk of all of this.
3 Do we, at this point knowing what we know today, does the 4 Committee or does the NRC staff have a good sense of what the probability 5 of this type of scenario is?
6 DR. CORRADINI: So, we -- so, the Director answers no.
7 COMMISSIONER BARAN: Okay.
8 DR. CORRADINI: For us, because we have not heard that 9 -- we haven't seen that analysis. That's the direct answer.
10 Elaborating on that, we've already started asking NuScale 11 to come in to give us a detailed discussion of their whole system because we 12 don't really know what, in detail, what the system is and how it responds.
13 And, we got a short snow curtailed meeting on the PRA 14 where we started getting some estimates.
15 But, I'll be very frank with you, we're early in the game and 16 so we've yet to completely understand the system and we've yet, at all, to 17 know the details of the PRA.
18 But, that's why, if I might just go back to the letter, that's why 19 some of us felt it's important that there ought be a risk calculation, an 20 incremental risk decision to make sure that, if we allow this, it's down in the 21 region, as John was saying, of low frequency. All right? As well as low 22 consequence for the whole facility.
23 COMMISSIONER BARAN: Is there -- I think it's the case 24 that there are some domestic and international operating experience of single 25 stuck rods not inserting because of an earthquake or an equipment issue.
26 And, you would expect that that would feed into this analysis --
47 1 DR. POWERS: It happens a lot.
2 COMMISSIONER BARAN: -- and probability of that.
3 DR. POWERS: I mean, if you look over the integrated 4 history, it has happened. And, the problem with looking at any single 5 sequence from a risk perspective, any single sequence, very low risk 6 significance.
7 You have to look at the integration of your design and what 8 you're trying to achieve. Chapter 15 and risk are kind of orthogonal on their 9 nature.
10 But, you've got to look at what does that give you is a 11 boundary condition on your risk assessment by having these divergent 12 capabilities.
13 Because, when you do the risk assessment, now you're 14 going to give them credit for non-safety functioning boron injection system with 15 some prescribed reliability on it.
16 COMMISSIONER BARAN: Did you want to add something 17 or you just standing right -- okay.
18 DR. CORRADINI: We could go on about this, you're 19 reliving the discussion into the letter. So, good.
20 COMMISSIONER BARAN: Well, let me ask then, the one 21 last part of it that I wanted to hear.
22 Either we've had -- the letter refers to some of the members 23 of the Committee who have the view that they have serious reservations about 24 this.
25 Does someone want to -- we've been talking about these 26 folks and their views, but I'd be interested in hearing from someone who has
48 1 that view or to articulate that point of view and explain why --
2 DR. POWERS: Well, I'm not one of the adamants. I was 3 actually the author of the same -- of the sentence that says we have to allow 4 deviations from the general design criteria.
5 But, I understand where they're coming from is that, since 6 the caveman ages of nuclear, shutdown means shutdown. It does not mean 7 kind of shutdown.
8 And, the problem is, the colligative processes of nucleonics 9 are just very, very hazardous if they get out of hand.
10 And so, yes, we -- you're more tolerant of, okay, it's hot and 11 I can extract heat and things like that, but the fact that we're having chain 12 reactions going on here is anathema to everybody who's been educated in 13 nuclear engineering from day one. That's what you learn, shutdown means 14 shutdown with margin.
15 And, that's the point that the people that I would say are 16 adamant on this. It's bred to the bone when you learn about nucleonics 17 because of the threshold kind of nature of a nuclear -- sustained nuclear 18 fission is one that you, you know, just never want to mess with that. And, 19 when you do --
20 On the other hand, if you take an ironclad -- when the 21 general design criteria were set up, our knowledge base was much less than 22 what it is now. And so, they took some conservative positions because we 23 didn't know.
24 We didn't even know what kind of reactors we ought to be 25 building. We tried a lot of different designs. Some you'd shake your head at 26 now -- and I shake my head at them all the time now anyway.
49 1 But, if you deny progress by edict, you'll never have any 2 progress.
3 DR. CORRADINI: I think he characterized it well.
4 COMMISSIONER BARAN: The whole discussion back at 5 -- both sides.
6 (LAUGHTER) 7 COMMISSIONER BARAN: Does anyone else want to add 8 anything? I mean, anyone think they can top that?
9 Yes, please, you don't have to top it, you can just share your 10 view.
11 MR. BROWN: Hi, I'm Member Brown. I happen to be 12 probably the most vocal dissident on this particular subject in our meetings.
13 My background, if you don't remember, which you probably 14 don't, I was in the naval nuclear program for 35 years. And, re-criticality was 15 anathema to us for any shipboard operation or concern that we had to deal 16 with as well as our prototypes, and we had nine or ten prototypes in service 17 training for decades.
18 So, we came down to -- I come down largely on the side of, 19 there are some principles that you have to set a pretty high standard to vary 20 from or to deviate from.
21 My background, other than just the Naval program was in 22 reactor instrumentation and control as well as well as all the safety analysis I 23 was responsible for for 22 years as well as the earlier years on my specific 24 projects.
25 So, I was deeply involved with not only the materials, the 26 reactor engineering, the physics and safeguards aspects of those plants.
50 1 And, re-criticality and one other one, largely the containment type issues, were 2 very, very seriously high level principles for us.
3 Based on my I&C world and all the analysis work that I was 4 involved in, I also developed a healthy respect for the fact that if you did not 5 have exceptions, you wouldn't need rules.
6 It's a matter of how you vary from those rules and the 7 information you develop and require to make that decision of what is critical to 8 the path that you proceed down.
9 In this particular circumstance, the probabilities are low. It 10 requires a number of different things to be in place in order to allow this power 11 to continue for not just minutes or an hour, but for hours or days in 12 circumstances.
13 We've always had the decay -- deal with decay heat. I 14 mean, that starts off at, you know, 6 or 7 percent power, somewhere in that 15 ball park, gets to a fairly low level after 10 or 11, 12 days, whatever it is, but 16 it's always there for a long time.
17 This seems to be now we are putting ourselves in a position 18 of saying, a low power return to critical for days and days in addition to the 19 decay heat we deal with, now puts the operators in a condition that they don't 20 have control over what they're dealing with, the heat.
21 So, you are dependent on now long-term ability to maintain 22 systems that aren't safety grade in order to put -- to proceed.
23 This is the forum in which that decision is the right place to 24 be made. It shouldn't be made at our level or the staff level, it has to be made 25 at the Commission level. And, that's what all this angst is about.
26 So, I just -- the idea, to me, was principle and I think that
51 1 principle should, for re-criticality, short periods, you can't avoid that, it's just --
2 I mean, we had that -- we had to face that issue with our plants that were little 3 burps that you had to deal with as you first shutdown in any accident scenario.
4 But, they were literally seconds to minutes and then it would 5 then -- you did require operator intervention to do it.
6 So, my recommendation is to think long and hard before you 7 -- I fully agree with the Chairman's point on Tesla and putting catalytic 8 converters -- I love the analogy, it was very, very appropriate. That's totally 9 out of whack and we don't want to get in that condition.
10 But, I still think this principle of re-criticality is a very, very 11 critical one to start thinking very thoughtfully about how we proceed with it.
12 And so, that's about all I would have to say.
13 Thank you.
14 COMMISSIONER BARAN: It's a good way to conclude 15 this discussion on that. Thank you very much.
16 CHAIRMAN SVINICKI: Well, again, I -- that is a great 17 discussion and I'm very glad that Member Brown came to the microphone so 18 we have insights into your deliberative process.
19 We are a deliberative body as well. And so, I view it as 20 evidence of a very good culture of batting back these perspectives on your 21 Committee.
22 And, that only raises my confidence in your letter reports 23 because, if that is the kind of broad, philosophical engagement going on 24 behind them, then they are -- they have a strong foundation.
25 My colleague stated that he wasn't the technical guy, I think 26 he said he was the lawyer. Well, having been trained as a nuclear engineer,
52 1 I understand that nuclear is not a religion and often I have to remind people of 2 that. It's not a theology, it's a technology.
3 As someone who was trained in that technology, to the 4 extent there are sacred things in nuclear. Criticality is one of them and I 5 acknowledge that. So, I acknowledge that this is something that needs to 6 rest heavily on the shoulders of the members of the Commission to either 7 affirm the staff's approach or not.
8 And, it's worth thinking long and hard about. I agree with 9 that as well. So, I appreciate that we've had an opportunity in this meeting to 10 more fully characterize that.
11 I do want to return to see if either of the members who are 12 concluding their term of service want to take me up on an opportunity.
13 I will just say, if Dr. Powers is coming to the microphone, I've 14 already discerned that you cautioned us against silliness. I think that was 15 something that you've already indicated, just said there's the tendency for 16 silliness on either side of a question. And, you cautioned against that.
17 But, I will just say that I'm a little bit familiar with your 18 resume. I do appreciate your long service on the ACRS. I knew the day 19 would come when the current Chairman of the ACRS at the time would inform 20 me that Dr. Powers' family had decided it was time for him to spend more 21 family time.
22 And he would be tapped on the shoulder and it would be 23 suggested to him -- no, okay. So, I'm getting a big no, I either wasn't 24 supposed to admit that they told me that or it's not true.
25 But, either way, I do, you know, you have engaged in the 26 course of your time, including as a student with many of the kind of the lions
53 1 of nuclear science and the legendary figures that makes you a very legendary 2 figure and a lion of this science by association, if nothing else, but also by your 3 own accomplishment.
4 So, in all -- and I know I've always enjoyed teasing you about 5 this and that, but it just makes me feel kind of full of myself to be able to tease 6 someone with all of the gravitas that you bring to nuclear science and 7 technology.
8 But, we did know this day would come, as sad as it is, so if 9 there are any, either serious or glib parting of thoughts you'd like to make, I 10 certainly welcome you to do that.
11 DR. POWERS: Well, I'm a little surprised you haven't 12 gotten a call from my wife insisting that you reappoint me. So, I think she 13 enjoys the monthly respite from having me around a little bit.
14 On the other hand, there does come a time when you need 15 to allow younger people to come and see if they can do a better job than all 16 the mistakes I have made.
17 You pose the question, are there any things that I think I 18 would communicate to you for the future. And, I guess I do have a concern 19 that we are not taking aggressive enough use of this marvelous risk 20 technology that has emerged.
21 And, that we are settling back to what we always feared is 22 that we would stack risk analysis on top of the deterministic analysis rather 23 than allowing it to supplant some of the deterministic analysis.
24 And, I also fear that you've written a position that says, gee, 25 we ought to use risk in other parts of the regulatory world than just reactors.
26 You have to be careful about that because many, many of your licensees are
54 1 in no position to do risk assessment they've had.
2 But, some areas, particularly, in the waste areas and 3 whatnot are in a position to take advantage of risk. And, we ought to risk 4 inform our regulations in those areas.
5 The problem is, it can't be done because you have not 6 pushed your staff to generate the necessary risk information that you have to 7 have to risk inform things.
8 Remember, the concept of risk emerged probably in 1974, 9 '76, but before we could use it, we spent two decades developing a body of 10 risk information.
11 We did it first by the NRC study of five representative 12 reactors. And then we asked all the licensees to examine all of their reactors 13 and give us another body of risk information before we could make any real 14 use of it, before we could write Reg Guide 1.174, before we could make the 15 ROP. We had to have that body of risk information.
16 Well, you're not giving to tools that kind of body of 17 information to your organizations outside the reactor community to follow up 18 on your proclamation that they ought to use risk information where ever they 19 can.
20 And, we've just -- just on Wednesday, we met with some of 21 the staff and saw how much of a handicap that it was for them to move into 22 the risk information.
23 So, I guess the caution I'm saying is, don't let this evolution 24 in being able to use risk information, as appropriate, a flag, that don't let it 25 become an add-on on top of the deterministic only.
26 And, don't say go use risk information elsewhere in the Reg
55 1 Guide and not give them the tools that they need in order to do that risk 2 information. Because it will be very different. They can't come borrow the 3 reactor databases and run over and do them in every case.
4 They can in some and, in fact, Mr. Stetkar pointed out to the 5 staff, that the wind and tornados and falling aircraft, don't know what they're 6 falling on or slamming into, whether it's a facility, a repository or the reactor 7 and you can use it. But, by and large, they can't. And, by and large, they 8 need a -- it takes a huge body of experiential information to bring any new 9 technology to bear.
10 CHAIRMAN SVINICKI: Thank you for those insights.
11 Mr. Stetkar?
12 MR. STETKAR: I'm tempted to say what he said. But --
13 (LAUGHTER) 14 MR. STETKAR: -- no, it's amazing, I'm sitting here sort of 15 scribbling down notes and I think he read them.
16 One thing that --
17 DR. POWERS: After all these years, we're mentally 18 connected.
19 (LAUGHTER) 20 MR. STETKAR: We've -- and believe me, that's scary on 21 so many levels.
22 (LAUGHTER) 23 MR. STETKAR: You don't even want to go there.
24 I certainly echo everything that Dana said about 25 consideration of risk going forward.
26 Thinking about it, one thing I'd like to add is that, I don't know
56 1 how many years ago it was, the paper that elaborated the differences between 2 a structuralist and a rationalist approach to life, I think it was '99.
3 We had a, I think it was an ACRS fellow who's the primary 4 author of it.
5 It's a very interesting paper.
6 DR. POWERS: No, it was the product of an ACRS retreat 7 held at MIT.
8 MR. STETKAR: Was it?
9 DR. POWERS: And, Dr. Apostolakis and I went nose to 10 nose.
11 MR. STETKAR: I think the thought that I was going to 12 leave you with is, and it's pertinent to a lot of the discussion that we had today 13 on NuScale and other technologies is that, traditionally, in my opinion, the 14 NRC and the industry, and especially if we go way back, as the Chairman 15 mentioned, to the early days of nuclear power, developed a very structuralist 16 viewpoint of regulation.
17 You established criteria that you believed were 18 conservative. You ensured that applicants design, constructed and operated 19 their facilities according to those criteria and, ipso facto, they were safe.
20 We've developed now a technology risk assessment 21 technology that challenges a broader spectrum of scenarios, a broad 22 spectrum of conditions. What can happen? Not, this shall happen with 23 these predefined no offsite power, predefined no operator actions, predefined 24 single failure and no double failure.
25 And, we've learned a lot from that process. That's more of 26 the rationalist thinking in terms of asking a broader spectrum of what can
57 1 happen? How likely is it? And, what are the consequences?
2 Structuralist said, as long as you follow the rules, it isn't 3 going to happen.
4 Now, going forward, I believe that following that rationalist 5 approach using risk information more extensively, provides the opportunity for 6 you to look systematically at those old notions of criteria, do you meet in a 7 specific set of criteria and, if you don't, you're not safe, if you do, you are safe.
8 And, it gives you that opportunity to move forward in a more 9 informed position. It is -- it's not an ad hoc position, it's an informed position 10 because you're challenged to systematically examine for a particular design 11 and even for a particular site what can happen and what are the sources of 12 risk and deal with those in an informed manner.
13 That doesn't mean that risk is the answer to everything 14 because risk, as we know, attempts to quantify uncertainties. In many cases, 15 those uncertainties are very large and, in many cases, it's very difficult to even 16 adequately try to assess the range of uncertainty.
17 People have brought up the glib term of the unknown 18 unknowns.
19 So, there is still, I believe, in the regulations and the staff 20 reviews a place for those, you call them deterministic, I'll call them structuralist 21 backstops. I tend to think of them in terms of defense in depth 22 considerations, but not necessarily, and Dana mentioned it, as risk is an 23 adjunct to that structuralist viewpoint.
24 I'd flip it around. I'd say, take the rationalist standpoint and 25 make sure that you still maintain an awareness of those structuralist 26 requirements in areas, especially where you have very, very large
58 1 uncertainties and where the risk, both frequency and consequences, could be 2 substantial.
3 Not where the risk where you have confidence that it's very 4 small, we don't need to make something extremely small much smaller, as 5 long as we have confidence that it is, indeed, small.
6 That's going forward, I'd just try to challenge, in particular, 7 the Commission, from a top down to try to drive the staff that way. I think it's 8 a way of getting past a lot of these -- the types of discussions we were having 9 today about, you know.
10 CHAIRMAN SVINICKI: Okay, well, thank you both for your 11 long service.
12 I thank all the members of the Committee for their work.
13 And, we are adjourned.
14 (Whereupon, the above-entitled matter went off the record 15 at 11:39 a.m.)