ML20135G384
| ML20135G384 | |
| Person / Time | |
|---|---|
| Issue date: | 09/11/1985 |
| From: | NRC COMMISSION (OCM) |
| To: | |
| References | |
| REF-10CFR9.7, REF-GTECI-A-44, REF-GTECI-EL, TASK-A-44, TASK-OR AB38-1-110, NUDOCS 8509180498 | |
| Download: ML20135G384 (54) | |
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ORIGINAL UNITED STATES OF AMERICA f NUCLEAR REGULATORY COMMISSION In the matter of:
COMMISSION MEETING s.
Discussion of Proposed Station Blackout Rule (Public Meeting)
Docket No.
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Location: Washington, D. C. Pages: 1 ~ 41 i
Date: Wednesday, September 11, 1985 l '
t 8509180498 850911 PDR 10CFR PT9.7 PDR l
ANN RILEY & ASSOCIATES Court Reporters y'
i 1625 I St., N.W.
Suite 921 Washington, D.C. 20006 (202) 293-3950
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1 D I SC LA I M ER 2
3 4
5 6 This is an unofficial transcript of a meeting of the
? United States Nuclear Regulatory Commission held on 3 in the Commission's office at 1717 H Street, 9/11/85 9 N.W., Washington, D.C. The meeting was open to public 10 attendance and observation. This transcript has not been 11 reviewed, corrected, or edited, and it may contain
, 12 inaccuracies.
13 The transcript is intended solely for general 14 informational purposes. As provided by 10 CFh 9.103, it is 15 not part of the formal or informal record of decision of the 16 matters discussed. Expressions of opinion in this transcript 17 do not necessarily reflect final determination or beliefs. No 18 pleading or other paper may be filed with the Commission in 19 any proceeding as the result of or addressed to any statement 20 or argument contained herein, excaot as the Cemmission may 21 authorize.
22 23 24 25
i UNITED STATES OF AMERICA 2 NUCLEAR REGULATORY COMMISSION 3
4 DISCUSSION OF PROPOSED STATION BLACKOUT RULE 5
6 PUBLIC MEETING 7 Poom 1130 a 1717 H Street, N.W.
9 Washington, D.C.
u) Wednesday, 11 September 1985 11 The Commission met, pursuant to notice, at 2:38 p.m .
12 COMMISSIONERS PRESENT:
13 NUNZIO PALLADINO, Chairman of the Commission 14 JAMES ASSELSTINE, Commissioner i
U5 FREDERICK BERNTHAL, Commissioner 16 LANDO ZECH, Commissioner 17 THOMAS ROBERTS, Commissioner 18 STAFF AND PRESENTERS SEATED AT COMMISSION TABLE:
19 SAMUEL CHILK l 20 ALAN RUBIN 21 THEMIS SPEIS 22 WILLIAM DIPCKS i
23 HAROLD DENTON l 24 PAT BARANOWSKi 25 HERZEL PLAINE
. 2 2-3 1 PROCEEDINGS 2 CHAIRMAN PALLADINO: Good af ternoon, ladies and 3 gentlemen. Let me apologize for the late start of this 4 meeting but the circunstances that we faced couldn't bring 5 about any other result.
6 Today we have with us members of the staff to 7 discuss the proposed station blackout rule, SECY 85-163 (A) .
8 Existing regulations to establish requirements for the 9 design and testing of onsite and offsite electric power systems.
10 However, as operating exoerience has accumulated a concern 11 has arisen. that the reliability of both the offsite and 12 onsite emergency AC power systems may be less than originally 13 anticipated.
14 Therefore, several years ago a decision was made 15 to initiate a staff study as part of our unresolved safety 16 issues, and identified as A-44, station blackout. Present 17 NRC regulations do not explicitly require that nuclear 18 power plants be designed to withstand the loss of all AC 19 power for any proscribed period of time. However, the staff 20 studies indicate that station blackout can be a significant 21 contributor to overall plant risk.
22 Therefore, the staff is proposing that the NRC 23 regulations be amended to require the plants be capable 24 of withstanding a total loss of AC power for a specified 25 duration, and to maintain reactor core cooling during that l . -- .
4 1 particular period.
2 This meeting was originally scheduled to last 3 an hour and a half. Due to the press of time today, I feel 4 it desirable to limit today's meeting to one hour. Therefore, 5 the staff has been requested to limit their presentation to 6 a half-hour. This will allow the remaining time for 7 Commission discussion and questions on this important subject.
8 At the end of today's meeting I intend to poll 9 the other commissioners to determine whether additional 4
10 staff meetings should be scheduled to discuss station blackout ,
11 or whether sufficient information is available for the 12 Commission to complete its review of SECY 85-163 (a) .
13 Do any of my fellow commissioners have any 14 additional remarks at this time?
15 COMMISSIONER ASSELSTINE: No.
16 COMMISSIONER ZECH: No.
17 CHAIRMAN PALLADINO: All richt then, let me turn 18 the meeting over to Mr. Denton.
19 MR. DENTON: Thank you, Mr. Chairman. The 20 presentation today will be made by Themis Speis, the director 21 of the division of safety technology on Bill's left. We also 22 have at the table today Pat Baranowsky from Research, on 23 my right, who has worked actively in this area for a number 24 of. years. And Alan Rubin who's the project manager for 25 station blackout, who has shepherded the thing through the
. . 5 1 various reviews and peer group efforts, and the meetings with 2 industry that have occurred.
3 You define this issue -- let me just restate it 4 so -- give it my interpretation. It's the loss of all AC 5 at a site. And the cuestion has been, how likely is that.
6 And if it is likely, what kind of capabilities should the 7 plant have to cope with such a loss of all AC.
8 As some of the slides show, there have been losses 9 of offsite power at plants. And there have been failures of to diesels to start at onsite to supply this. Plants do have 11 batteries to provide a capability for some actions in this 12 event of all AC.
13 What we've done in this multi-year study is to 14 look at the probability of losing offsite power, coupled with us the probability of having the diesels not start. One of the 16 major reasons this project has taken so long and cost so 17 much is that we've looked extensively at operating 18 experience.
19 We've got statistics galore that we have published 20 on all these reliability factors. We've used the national 21 labs extensively. We've also taken a hard look at plant Et differences. So this is not a simolified look. We have looked 23 at the plants as individual plants. And our proposed 24 resolution does take into account the different configurations
[ 26 of plants that we've licensed over the years.
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l' One other point I wanted to'make is that we have .;
1, j- 2 = also looked at what the Europeans are doing in this area and
- 3 have taken-some of'their practices into account. I might 4 mention I was at a plant.a few weeks ago in Belgium called 5 Duel, and in addition to having three safety trains and
.a one additional diesel-generator that could swing between the three safety trains, which would be roughly comparable to i
a what*we have here, they had a so-called bunkered system. And
~
e in'their bunkered system they had three 50 percent safety to trains, each one with its own diesel generator. Then they-11 ~ had two additional diesel -generators 'for balance of -plant.
! u So this one plant-had nine diesel generators of i
is various sizes to' provide protection against loss of offsite 14 power.
ui With that introduction : to the problem, we have .about is a dozen slides that we've selected out of this big group 17 that we'd like to focus on and I'll turn it over to Themis.
la MR. SPEIS: Thank you, Harold, Mr.' Chairman,
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1s ' the' Commissioners. The A-44 studies -- slide number two, 20 please.
21 (Slide.)
22' MR SPEIS: The A-44 studies develop insights EB- < into the relative importance of ' the various factors that i
- 24 ' ' affect the risk from station blackout . Land'those insights 25 together with engineering iudgment were used to develon.the 4
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7 1 _ proposed resolution which is embodied in the rule that 2 we're proposing.
3 An important consideration was operating experience ,
4 which has shown that there are practical limits to the 5 reliability of both offsite and onsite AC power systems. And 6 their reliability varies significantly from plant to plant 7 as Harold mentioned already, s Another important consideration is the limited 9 decay heat removal capability without AC power as well as I 10 no containment heat removal without AC power.
11 Based on our work, we feel that.the most effective 12 way to reduce the dominance of the blackout sequence is to 13 have the capability in all plants to be able to cope or 14 withstand a station blackout for a specified duration. In is order to achieve this we have used the information that we 16 were able to put together, and we set up a goal, a numerical 17 goal that we don't want the contribution station blackout 18 to the core melt to be more than 10 to the -5 per reactor 19 year.
20 So this is a kind of a -- it's a goal. It's 21 not a go or not go type of speed limit. And we have used 22 that as a guidance in our work.
23 Slide number three, please.
24 (Slide.
26 MR. SPEIS: As the chairman said, currently
i
- 8 1 there is no requirement that nuclear power plants must be 2 able to withstand the concurrent loss of both the offsite 3 and onsite emergency AC power systems.
4 Conclusions drawn from our extensive review of 5 operating experience and technical analysis indicate that the 6 ability to cope with station blackouts of some duration would 7 keep station blackout from being a significant contributor 8' to total core damage frequency.
9 Slide number four, please.
10 (Slide.)
11 MR. SPEIS: I'm going faster than I can normally 12 talk. The proposed resolution of this USI, what we're 13 proposing is that to put a new rule in place. That plants 14 should be able to cope with a station blackout for a specified 2 duration. And to maintain reactor core cooling during that 16 period.
17 of course, as we have said already, the reason 18 for_this is that our experience has shown that there are 2 practical limits in assuring the reliability of both offsite 2 and onsite AC power systems.
21 In support of the rule we have a regulatory 22 guide which will provide guidance on acceptable station 23 blackout duration to comply with the proposed rule. Guidance 24 -- the guide also includes guidance to evaluate the capability 25 of a clant to cope with a station blackout. It contains-1
g 1 guidance on maintaining minimum emergency diesel generator 2 reliability. And it includes guidance on procedures to 3 . restore offsite power.
4 The guidance on acceptable station blackout 5 duration would deoend on a comparison of specific plant 6 characteristics to those factors that have been identified 7 as the main contributors to risk of station blackout. I 8 summarize some of them. We have found out that these 9 factors 'are the redundancy of offsite -- excuse me, the 10 redundancy of onsite emergency AC power sources *,' the i 11 reliability of those sources. I'm referring to diesels here.
12 As well as the frequency of the loss of offsite oower. And 13 of course, the orobable time needed to restore offsite power.
14 The next -- viewgraph number five, please.
15 (Slide.)
115 MR. SPEIS: For background here, we think that the 17 proposed rule complies with the policy for new recuirements.
18 If I may quote from the '85 policy and planning guidance, 19 "to the extent practicable, issues which affect numerous 20 licensees should be addressed in the context of rulemaking."
21 And also, "the NRC regulations should allow individual 2t licensees the flexibility to select the most cost-ef fective 23 ways to satisfy NRC objectives."
24 I have a word on the next slide about the backfit 25 rule. We feel that the proposed resolution does comply with
10 1 the final backfit. rule. We feel that there will be a r
2 substantial increase in the overall protection of the public 3 health and safety to be derived from this proposed rule.
4 And the direct and indirect cost of implementation 5 of the proposed rule are justified in view of this increased 6 protection. We have done extensive cost benefit analysis in 7 addition to the analysis that we performed. There is an 8 independent cost analysis group that report directly to 9 Mr. Dircks and they reviewed all our work in detail and they 10 have documented formally the results of their evaluations in 11 a letter to CRGR.
12 Next slide.
13 (Slide.)
14 MR. SPEIS: As Harold said, we looked very carefully
'l is at foreign experience.to see what insights we can draw from 1
16 them. The French have a capability for coping with a station 17 blackout for 20 hours2.314815e-4 days <br />0.00556 hours <br />3.306878e-5 weeks <br />7.61e-6 months <br />. Not only for their new plants, but 18 their backfitting this capability to their 900 megawatt 19 electric plants'.
20 Designed to cope with station blackout -- and the 21 British, the-proposed PWR, the sizewell design is designed 22 to cope with station blackout. In addition it has four 23 onsite emergency diesel generators which provides added 24 reliability.
26 CHAIRMAN PALLADINO: Do they have any particular b :
11 1 time limit on their'--
2 MR. RUBIN: No specific. time.
3 MR. SPEIS: It's substantial. It's more than 4 six or eight hours. Probably as much as 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> or so. We 5 can get you the precise number.
6 The other countries in Europe, the Germans, the 7 Swiss, the Italians and Belgians all h$ve increased their a redundancy on both onsite -- onsite redundancy. As Harold 9 said, one of the plants in Belgium has nine diesel generators.
10 (Slide.)
11 MR. SPFIS: On the next slide I can give an 12 overview of the interactions we had with industry in going 13 through our working towards the resolution of A-44. We had 14 discussions with the IEEE working group, standard committee 15 4.3 on loss of all AC. They have reviewed and commented on 16 the contractor reports on emergency diesel generator 17 reliability and the loss of offsite power analysis that was 18 done by Oak Ridge National Laboratory.
19 We also have interactions with ANS standard so working group 58.12. This group has been workina to develop 21 an industry standard that would provide the methodology for 22 evaluating the capability of LWR's to withstand station 23 blackout. But this work is in limbo right now pending actions 24 by this Commission on this issue.
26 A group that we have been interacting with since i
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..- '. 12 1 June of '84 is the Nuclear Utility Group on Station Blackout.
2 It was formed in June '84 originally by 25 utilities. Now
' most or maybe all utilities'are involved in this effort.
3 4 They _came to us in October 1984 with a prooosed way of 5 integrating all the issues that were relating to the blackout 6 issue. And they came to us this year with some additional
. 7 ' proposals.- .
j g MR. DIRCKS: I might mention this NUGSBO proposal..
g I think this was evidence of a responsible utility _. group that to did come forward with a-proposal. And their proposal went 11 beyond just dealing with the station blackout issue. They 12 had a proposal to integrate the proposal to several problems 13 - in one package.
j 14 I think the staff met several times with them as 4
j/ Hi Themis pointed out. I know I was in on one meeting and, le Harold, you probably were in on more. The difficulty, I i
i 17 think, is the desire on the part of the staff to assure a-t up firmness of a regulatory approach versus the issue of a i
up policy' statement approach on the matte r.
20 But I don't'think any-of us want.to downplay the
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21 fact that this' was a group that did come forward with a n proposal that was:not limited, that was an important proposal.
23 And I think it did evidence some desire on the part of the --
24 CHAIRMAN PALLADINO: But on page two of the SECY 26 paper it stated that rulemaking was not-supported by this
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13 1 group because it wasn't a -- this issue was not a significant 2 contributor to risk. And the staff concluded otherwise.
3 Did they study it enough to draw an independent 4 conclusion?
8 MR. DIRCKS: There was a good deal of interaction.
s I'll let Themis talk about'the study. But I think their 7 concern was more that we try to not move forward ~with a a rule right now, but to encompass it in some sort of a policy s statement that would gather the support of all of the utilities to on this integrated approach.
11- MR. SPEIS: Their approach was focused on enhancing a the AC power reliability'. And I discuss on slide number nine, is I summarize what --
14 CHAIRMAN PALLADINO: But let me just read the one 15 sentence that I was referring to on page two of the SECY le paper it says, "NUGSBO position is that rulemaking is not 17 necessary to resolve USI A-44 because they conclude that is station blackout does not represent a significant risk to is public health and safety."
20 MR. DIPCKS: At this time.
21 CHAIPMAN PALLADINO: ANd I' thought your case was 22 that it did provide ---it was an important contributor. And 23 I was just wondering.how they could prove --
24 MF. DIRCKS: I think the timeliness -- at this time 25 might have been added to this statement, because I think at i
14 1 this point, we're not saying right now at this point there's 2 an imminent safety hazard because of the condition of the 3 grid and so on. But I think they were saying, give us some 4 time and we'll work out some other approach.
5 MR. SPEIS: Well, they wanted to --
6 CHAIRMAN PALLADINO: But this sentence says 7 something different. It says it does not represent a 8 significant risk to public health and safety.
9 MR. DENTON: I guess we just have a difference of 10 opinion there. We were trying to project their view.
11 CHAIRMAN PALLADINO: Okay.
12 MR. DENTON: We don't think there's an imninent 13 action or we would have taken it. And we have taken various 14 actions when diesels fail, and that sort of thing, to increase 15 it. And I think the biggest difference probably, in addition is to some technical disputes about how form the probabilities, 17 was they didn't have all their membership in. And as usual 18 in these things, we're more worried about a handf ul of plants l 19 than we are the great majority of plants.
20 A lot of plants do have a lot of coping capability.
21 So the object of this is to get to those plants where we Zt think this is a real risk. You may remember there was a 23 board decision at St. Lucie where this was required by the l 24 board and we did adjudicate the adequacy of a station blackout 25 at that plant.
15 1 MR. SPEIS: But I think our basic approach is that 2 we feel that based on the work that we have seen that there 3 are limits to the reliability of offsite and onsite. And 4 in order to increase defense in depth we feel that by having 5 -- by plants having the ability to withstand the blackout a for some duration then, you know, you are increasing defense 7 in depth, and you're solving the problem that way.
s And the industry's effort, which I think is very 9 commendable, was in the direction of enhancing AC power.
10 And I summarize their proposal on slide nine. I was going 11 to skip that in the interest of time, but now that it has 12 come up.
13 Proposal for the resolution of A-44, basically 14 they said, implement plant-specific programs to enhance AC 15 power reliability; procedures and training to restore AC is power, evaluation and correction of root causes of losses of 17 AC power sources; reduction in frecuency of emergency diesel is generator cold fast starts; procedures in the event of 19 severe weather; evaluation of procedures and training for so operators to cope with station blackout; industry-wide 21 evaluation of significant events relating to AC power 22 reliability.
23 They also proposed that the Commission issue a 24 policy statement in recognizi'ng those industry initiatives 25 to enhance AC nower reliability, and refrain from rulemaking
16 1 to resolve station blackout.
2 MR. DENTON: We recommended that you issue the 3 proposed rule and that you also issue their proposal and 4 get public comments on both.
5 MR. SPEIS: On page ten I have a summary of our 6 evaluation of --
7 CHAIRMAN PALLADINO: Is that the proprosal in a your-paper?
9 MR. DENTON: Yes.
-10 MR. DIRCKS: Yes. I think they wanted to move 11 to a solution of these generic issues. And their solution.
12 did not envision a rule, but more of a cocoerative, voluntary 13 approach to this problem.
14 I might also add that Newmark INPO has recently is I think sent a letter in where they've indicated that they 16 are forming up an initiative along these lines. So as we 17 go forward I'm sure you're going to be hearing more from these is groups on this issue. To be fair we wanted to make sure you 19 knew that we're not denigrating their proposal.
30 It's a worthwhile initiative to try to integrate 21 many of these issues.
22 COMMIFSIONER ASSELSTINE: Is that the letter to 23 you that talks about their getting involved in designs kinds 24 of questions that some commissioners received?
26 MR. DIRCKS: Yes.
~
3 17 l
1 (Slide.)
2 MR. SPEIS: On slide number ten I have summarized 3 our evaluation of their proposal which is discussed in 4 great detail in the commission that you referred to, Mr.
5 Chairman. We feel that the elements of proposal to enhance 6 AC power reliability are included in staff's proposed -
7 resolution.
8 The NUGSBO used methodology, our staff methodology s to evaluate core damage frequency from station blackout.
10 Their conclusion that rulemaking is not required is based on 11 optimistic assumptions for frequencies of losses of offsite 12 power and diesel generator reliability, and leaves little 13 margin for degradation reliability of these systems.
14 For station blackout to be a small contributor to 15 total core melt frequency, coping capability we feel is 16 necessary. And we feel that without rulemaking there is 17 no basis in our regulations to require capability to cope la with station blackout. So I think it's a clear cut need, is you know, if the Commission decides.-
so If you turn to page 11, approach for resolution 21 of the issue. We have the logic that we have followed in 22 bringing this issue to a close. Determine the likelihood 23 and level of risk due to station blackout for a spectrum of 24 plant designs. This is the big problem always that we have 26 all kinds of plants out there with different systems and
18 1 different capabilities and different characteristics to 2 evaluate.
3 Compare results with other nuclear plant accident 4 risk. Identify dominant factors affecting risk and cost 5 effective improvements, which of course involve the AC power 6 reliability and the ability to cope with extended loss of 7 AC power. And propose new or revise licensing requirements 8 consist with level of risk and cost effectiveness.
9 (Slide.)
10 MR. SPEIS: On page 12 I have summarized all the 11 pertinent factors that were utilized in arriving at the bottom 12 line. You know, if you look at the last line there, estimated 13 range of core damage frecuencies from station blackout, 14 varying from 10 to the -6, to 10 to the -4 per reactor year.
15 It is this number of 10 to the -4 per reactor year that we 16 feel is an outlier that we want to erase, reduce that to 17 10 to the -5 as I said earlier.
18 So the information that I have here, the loss of 19 offsite power, the time to restore offsite power, emergency 20 diesel generator reliability statistics, median emergency 21 diesel generator repair time, all these lead to the final 22 number of 10 to the -6, to 10 to the -4 per reactor year, 23 the contribution of station blackout to the total core melt 24 frequency.
26 And of course the range is because of the variation
. . 19 1 in plants, the variation in location, the variation in 9 configuration and other unique characteristics, 3 (Slide.)
4 MR. SPEIS: On the next page I have summarized 5 our findings. I have said some of them already. We have 6 found out that reliability of onsite emergency AC power systems 7 varies corsiderably. It depends on configuration of the 8 diesels. And by that I mean the number of diesels that are 9 available. And of course, how many you need for decay heat 10 removal purposes.
11 Some plants have three and they need one. And 12 some plants have two and they need one. ANd so, it's how 13 many you have and how many you need for decay heat removal 14 systems.
15 of course, the other is the diesel reliability 16 itself, which as shown before, the average is .98 per 17 demand. But it varies somewhere between .9 and 1.
18 The other factor is the frequency and duration of 19 offsite power loss, which of course varies considerably.
20 It's highly dependent on site characteristics. By that I 21 mean weather and grid design. Weather is basically the Zt main contributor to long duration blackouts. Plant factors
%) involve switchyard decign and transmission lines.
24 Extended duration station blackouts which are due 25 to weather can be significant contributors to risk.
20 1 Core damage frequency from station blackout
- 2 varies considerably from plant to plant. Susceptible to 3 station blackout, ability to cope with all AC power. We 4 haven't been able to find a single fix that we can apply 5 uniformly to all the plants that will resolve this issue in 6 a cost effective way.
7 And as you will see, you know, our approach has 8 been a graded one. Some plants will have to cope for longer g periods of time and other ones -- others for shorter periods to of time, in order to meet the goal of 10 to the -5, as well 11 as the other deterministic criteria that we have found out.
U (Slide.)
13 MR. SPEIS: On the next page, recommendations for 14 resolving this issue. We propose to publish the proposed is rule which would' require all plants to be able to withstand 16 and recover from a station blackout of a specified duration.
17 We're proposing adding a new 5063, and also 18 amending GDC 17, 10 CFR 50, Appendix A. And GDC 17 at present 19 deals only with reliability. ,
20 And issue the draft regulatory guide in support of 21 the rule, which it will provide guidelines for all plants, 22 procedures and training to cope with station blackout, 23 minimum diesel generator reliability, and the guidelines will 24 be very careful in considering the plant unique differences.
25 MR. DENTON: I think this concludes our overview
e 21 1 of the issue. I'd like to give Dr. Rubin who worked with 2 this issue for so long a chance just to make a couple of 3 technical points, and this will conclude our presentation 4 perhaps just a few minutes over 30 minutes.
5 MR. RUBIN: Just in the interest of time, there 6 were a number of back-up slides, or slides that we prepared 7 which were going to highlight the technical results and the a rationale that led to our decision or this proposed resolution .
9 I'll cut that down to about four slides and let you ask 10 questions afterwards.
11 (Slide.)
02 MR. RUBIN: Slide number 15 just shows an overview 13 as to the basic flow of the kind of analysis that we've done 14 to resolve the issue.
U5 COMMISSIONER ASSELSTINE: Turn it sideways.
16 MR. RUBIN: We looked at operating experience in 17 losses of offsite power and extensive interactions with 18 industry on those data. And looked at emergency diesel .
19 generator reliabilities and system reliabilities to come 20 up with estimates of station blackout frequencies and 21 durations.
22 And these estimates were then used in probabilistic 23 risk type analyses to look at accident sequences and 24 significant core damage frequency estimates. The results of 25 these studies were then factored into the staff's proposed
22 1_ technical resolution.
2 The following slides we're going to go into a 3 little more detail of some of the input to the technical l
4 resolution, but as I said, we're pressed for time. So let l 5 me go on and just highlight a couple of the very significant 6 points.
7 Slide 16 and 17 just show operating experience on 8 losses of offsite power. Let's continue on maybe to slide g number 21.
10 (Slide.)
l 11 MR. RUBIN: That's not to say that offsite power --
- u offsite power we spent an awful lot of time reviewing the 13 data and those slides we skipped show highlights of the 14 results of that. THey are important.
. 15 In the area of diesel generator reliability, 16 you've already heard that the systems themselves, the 17 configurations vary significantly from plant to plant and is that affects the overall likelihood and frequency of station 19 blackout.
20 The failures of diesels we've studied and found 21 that there's really not one fix that you can recommend that 22 would bring the reliability of diesel generator up to a 23 uniform level for all plants.
24 Let's continue on. Some of these next slides 25 which we'll skip just show the ranges of diesel generator t _ - . _ _ _ .- . _ . - -
' 23 1 reliability. On slide number 26, we'll go to next.
2 (Slide.)
3 MR. RUBIN: This schematically shows the kind of 4 insights we found from the probabilitistic risk assessment 5 analyses. In order to reduce the estimated core damage a frequencies from station blackout, there are several ways 7 that that can occur. One is by increasing the ability of a a plant to cope with station blackout. That leaves more e time to restore AC power, and therefore, a likelihood of d
10 restoring AC power is greater.
)
11 In addition, increasing diesel generator reliabilit /
{ u will reduce the estimated frequency of station blackouts.
13 Increasing numbers of diesel generators will also improve 14 the station blackout risk.
i 15 COMMISSIONER BERNTHAL: You'd never get this 16 figure past me as a referee. What are the units?
17 MR. RUBIN: This is just a schematic diagram. We is have back-up slides in the back of the package that do give is units, which I didn't -- we could go into if you want to.
20 The units here in ability to cope with station blackout are
. 21 in terms of hours. And the estimated core damage frequencies 22 -- this slide shows that there's a wide range from plant 23 to plant. And we have specific estimates for certain diesel i 24 generator configurations.
26 COMMISSIONER BERNTHAL: Well, is this purely
. ._ - _ _ _ _ _ _ . . , . _ _ _ . - - _ , - - _ _ _ _ _ _ . ___ ~ _ _ _ . _ . _ _ . . _ _ . _ _
24 1 schematic then?
2 MR. RUBIN: No, our results -- if we could go to --
3 COMMISSIONER BERNTHAL: What are the numbers on 4 the axes?
5 CHAIRMAN PALLADINO: That's what I want to know.
6 MR. RUBIN: We go to one of the back-up slides 7 for that.
8 CHAIRMAN PALLADINO: The back-up slide package?
9 MR. RUBIN: Back-up slide package.
10 MR. DENTON: How about 5.2, just for the 11 configuration to look at.
12 CHAIRMAN PALLADINO: Slide 5.2?
13 MR. RUBIN: These are actually estimated frequencies 14 of station blackouts lasting longer than a specific duration.
15 This is back-up slide number three. If we could put up 16 back-up slide number three?
17 (Slide.)
18 MR. RUBIN: Okay, you can see the station blackout 19 duration in terms of hours and an estimated frequency of 20 station blackouts. This is for a typical power plant. The 21 diesel generator configuration on top shows a one out of 22 two diesel generator configuration. That means the plant has 23 two diesels and one would be required for core cooling in 24 the event of loss of offsite power.
25 The diesel generator reliability shown on this
25 1 curve is the typical -- is an average diesel reliability of 2 about 98 percent. These ranges of offsite power groups are 3 indications of susceptibility to severe weather as an 4 example. These ranges are defined in staff NUREG 1032. And 5 this figure is taken from page 5-2 of that report.
6 We ran a number of parameters and sensitivity 7 studies for different diesel generator configurations, a different diesel generator reliabilities. They're included g in back-up slides 2, 3 and 4.
to What this basically shows, for example, a typical 11 plant has one out of two diesels, a 95 percent reliability.
12 And the offsite power cluster is represented on average by 13 number seven on this figure. So if a plant has a station 14 blackout coping capability of four hours -- maybe it will l
l ui help if I just go up with the pointer.
16 This was the typical diesel generator configuration 17 and reliability. And this curve number seven represents an 18 average offsite power type group. With a four hour station 19 blackout duration -- I'm sorry, excuse me. The estimated 20 frequency of a station blackout lasting four hours or longer 21 for this plant is on the order of a couple times 10 to the 22 -5 per site year.
23 And you could see, as the station blackout of 24 longer durations are expected to be of lower frequency. If 4
26 a plant were in an area that had susceptibilities to more
26 1 severe storms than an average site, for example, it might 2 be in one of these higher groups.
3 COMMISSIONER BERNTHAL: I have to say, I'm surprise d 4 at a couple of things. One is the limits, and the worst case 5
the apparent worst case number here is as small as it is, 6 when I look at some of your other numbers that would have 7 led me to believe that it would be considerably larger.
8 MR. RUBIN: This is not the worst case limit.
9 This is a representative curve. There are other -- if for 10 example --
11 COMMISSIONER BERNTHAL: I understand that. But 12 your worst case limits which you quote in the paper, and I 13 gather is another limit here, is of the order of 10 to the 14 -4 roughly. And I was under the impression that we had some 15 concern that the real outlier plants may have overall core 16 melt frecuency perhaps as much as ten times that.
17 Is that apparent discrepancy because this is not is the dominant factor in any of those plants that have core 19 melt frequencies that are relatively high?
20 MR. RUBIN: No, there are other curves. Perhaps, 21 this is again, if a plant has a lower redundancy on diesel 22 generators, some plants don't have one out of two diesel 23 generator configurations. For a shared site which has two 24 plants on one site and three diesels at that site, one diesel 25 dedicated to each unit and one swing diesel. That's a lower
1 23 1
1 -diesel generator redundancy.
2 MR. DENTON: Maybe another figure. Pat Baranowsky 3 reminds me there's another one.
4 MR. BARANOWSKY: The next one shows, for instance, 5 when you change the diesel reliabilities on that number seven 6 which was sort of an average type of loss of offsite power 7 frequency --
8 MR. RUBIN: Slide four, if we could. .
9 (Slide.)
10 MR. BARANOWSKY: You can see a significant change 11 here in the frequency of station blackouts lasting a certain 12 time.
13 COMMISSIONER BERNTHAL: What am I looking at?
f 14 MR. RUBIN: Back-up slide four, please. -
J 15 4U1.-SPEIS: Can you put the next one, please?
16 (Slide.)
17 MR. RUBIN: This again shows the different i
18 parameter gained for one out of two diesel generator N configuration. And represented of offsite power group seven 1
20 there's a sensitivity for different diesel generator 21 reliabilities. It's difficult to represent everything on j 22 one figure. We did that in the report and it's a very large j
i 23 number of curves on one figure.
24 COMMISSIONER BERNTHAL: Okay, but then the statemen ,
26 -- and I won't go on here long because I don't think we've l
28 1 got anything close to enough time here -- but on one of the 2 slides we've already been through there's a number, estimated t
3 range of core damage frequency from station blackout, and 4 it flatly says 10 to the -6, to 10 to the -4 per year. So 6 that apparently is not accurate.
6 CHAIRMAN PALLADINO: For a station blackout.
I 7 MR. BkRANOWSKY: I think that's meant to be 8 approximate. You have to recognize that we're talking about --
3 COMMISSIONER BERNTHAL: Within a factor of ten, to you mean.
11 MR. BARANOWSKy: We're talking about uncertainties 12 that are at least a factor of ten here. But I think if I 13 got something that's seven times 10 to the -5 and I say 10 14 to the -4, a probabilistic analyst isn't going to argue that is as being 10 to the -4 roughly speaking. Anyone can think 16 that seven times 10 to the -5 is known so precisely that 17 10 to the -4 isn't a reasonable statement --
r 18 COMMISSIONER BERNTHAL: It sounds to me like it's is 10 to the -4, and possibly 10 to the -3, judging from that so slide there.
21 MR. RUBIN: If I could show another slide maybe 22 we'll cover the point. Back-up slide number 10. It's 8-5 23 from the NUREG 1032.
24 (Slide.)
26 MR. RUBIN: This shows as one of the sensitivities
29 1 the different onsite emergency AC power configurations.
$ 2 CHAIRMAN PALLADINO: Is it page 8-3, figure --
3 MR. RUBIN: This is 8-5 in your back-up slides.
4 CHAIRMAN PALLADINO: Thank you.
5 MR. RUBIN: What this figure shows is a plant with j 6 a station blackout capability, ability to cope with a station 7 blackout of going for four hours and upward, and an estimated
, a core damage frequency. For a representative offsite power e group that we discussed before as "an industry average" and to an average diesel generator reliability with different 11 emergency AC power configurations.
12 This was the one out of two, which means one is diesel out of two. This is a less redundant configuration, 14 two out of three, and you can see for this plant with an is estimated four hours station blackout canability, we're
- 14 getting in the range of around 10 to the -4, upper 10 to
- 17 the -5 core damage frequency estimate per reactor year.
18 If this diesel generator configuration were the
- 13 same but th.e emergency diesel generator reliability were ,
1 30 higher in this curve, estimate would go up. Or likewise, 21 if the offsite power group were -- if the plant were in an 22 area that might be more susceptible to severe storms and 23 therefore, longer duration or more frequent losses of offsite 24 power, also the curve would tend to go uo.
26 COMMISSIONER BERNTifAL: Let me just see if I can
. . I 30 1 get a short answer to put a bound on --
1 2 MR. RUBIN: Sorry this is so long.
t 3 COMMISSIONER BERNTHAL: -- the nature of the problem 1
- 4 here. Since you've said that the reason for promulgating this a rule is to deal with what you expect to be outlier plants, ,
a what values would you expect to find for those outliers plants?
7 Are we talking 10 to the -4, 10 to the -3, 10 to th~e -57 s
a Obviously not. 10 to the -4?
3 MR. RUBIN: 10 to the -4, that order.,
10 COMMISSIONER BERNTHAL: Are we talking damage or 11 blackout?
! 12 MR. DENTON: We don't always know, because that a
13 requires execution.
14 MR. RUBIN: Core damage.
2 MR. DENTON: Until the utilities do their studies is that we've asked them for.
s COMMISSIONER BERNTHAL: I understand.
f 17 N MR. DENTON: So we're always making the decision
) is on partial information.
20 COMMISSIONER BERNTHAL: You're guessing, right.
! l 21 I guess I'm just a little surprised. I thought we had 2t bigger problems out there.
%I MR. DENTON: Well, I think if this were a bigger 4 ,
i 24 problem we would have dealt with it. But we think it's t
26 one that should be dealt with, and not left to lie. All i
- . - -- . = - _. .- .- _ __-___
31 i
1 it takes is one major U.S. blackout in this country to f 2 change statistics a lot.
3 COMMISSIONER BERNTHAL: I understand.
! 4 MR. DENTON: Plus some more diesel failures as 5 we've had. We've had over 500 cases of failing to start .
6 So I think the real key is coping capability. And what the rule asks for is looking at DC battery capability, how long
) 7 8 they will last, compressed air, how long that will be availabl e g in a plant. And making sure there are procedures in the 10 plant to cope with a station blackout.
i 11 And if you can get a coping capability out for j 12 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />, then you've got a fair chance of either getting 13 the offsite power restored or getting your diesels started.
f 14 COMMISSIONER BERNTHAL: I guess the thing that is just surprises me is if it's 10 to the -4, somehow you can't 16 really trust instinct here. But as I peruse some of these 17 numbers, just at first glance, the instinct would be, yes, is this is a serious problem. And that's why I'm surprised that i to it comes out 10 to the -4. And I can't trust gut instinct j 20 to -- you guys have worked out the numbers, but --
21 MR. SPEIS: It's the sequence itself. 10 to the
' 22 -4, the contribution of blackout to the core melt.
I i 23 COMMISSIONER BERNTHAL: I understand.
24 MR. DENTON: plants do have some coping capability ,
! 26 inherently. And it varies a lot. So we have to factor that l
l
. . 32 1 in.
2 COMMISSIONER BERNTHAL: But I've asked you for 3 the outer limit that you more or less expect to find.
4 MR. DENTON: I guess I defer to Al and Pat who 5 have done the studies.
6 MR. SPEIS: One of the things that could be the 7 Achilles heel is the integrity of the seal. You know, the 8 Europeans and the others that have gone out for coping g capabilities to protect integrity of the seal, because if to you lose AC power, as a common mode failure, not only you 11 degrade the seal of the primary coolant pump, but the seal 12 of the other pump that provides water.
13 COMMISSIONER BERNTHAL: Well, what should the 14 target be? 10 to the -57 15 MR. DENTON: We've recommended 10 to the -5, so 16 that this is not a significant contributor to the overall 17 core melt probability.
18 MR. SPEIS: So it doesn't rise above the other up one. We don't want the specific sequence to be so dominating, 20 you know, against the others.
21 COMMISSIONER DERNTHAL: Is that standard going to 22 be broadly applied generally in our rulemaking?
23 MR. DENTON: Well, it depends on what you do, I 24 guess. But we recommend that you keep the individual 25 sequences down in order to comply with the overall total.
33 i
1 And many plants would not be affected by this rule 1
2 significantly.
3 Maybe you should -- if you have a few more slides 4 you want to show about where you think this is going to a come out.
4 MR. RUBIN: This will come in the next slide with - -
7 MR. DENTON: How it will affect the individual 8 plants.
]
l j g MR. RUBIN: I just want to make clear perhaps one 10 Point on these estinates. We've tried to used best estimates, I
i 11 not conservative estimates and have taken a lot of
! 12 conservatisms out of the analysis, and looked at details of l
, 13 losses of offsite power with industry and I won't go into
- 14 the specifics of that. '
4 l 18 (Slide.)
I i
14 The next slide I wanted to do -- to present was
- 17 the proposed rule itself, which is slide number 28 back in
! 1s the main set of slides. This really is the heart of the !
[
- 13 proposed rule. It's an additional paragraph that would be i
! 20 added to Appendix A of GDC 17. And it's fairly straightforward 21 and not a real complex rule saying basically -- it sets the i
se requirements that plants should have come ability to cope
! 23 with a station blackout. f i
j 24 It doesn't specify the duration. That's covered I
! 26 in the regulatory guide that we have also included in the
34 1 Commission package. But also points out which factors are 2 important ones and significant in determining what that 3 station blackout coping capability should be.
4 The staff would provide guidance in the regulatory 5 guide, but there could be other analyses performed by the 6 utilities to come up with their own duration and to justify 7 a duration.
8 So I don't have to read the language. But this e is really the heart of what we are including the in rule, 10 this paragraph.
11 MR. DENTON: Before we conclude our presentation 12 here, we're prepared to answer any questions from -- Pat,
- 13 would you like to add anything?
l 14 CHAIRFAN PALLADINO: Can I ask a cuestion rtbout 15 slide 32 where you give some numbers. Are these --
16 MR. RUBIN: Slide 32, please.
17 (Slide.)
18 CHAIRNAN PALLADINO: Could you explain the meaning 19 of the numbers eight, four, and this is not meant to exclude 20 something between four and eight?
21 !!R. RUBIN: Okay, let me explain, first of all 22 what this is. You've heard the type of f actors that we 23 found are important in terms of risk. The emergency AC 24 power configuration, this is represented with the number of 2 diesels, the one out of two again being the typical plant. 1 1
. . I 35 1 i f
1 Here the less redundant diesel generator configuration and l i
! 2 here more redundant systems, one out of three.
i 3 The offsite power characteristics, number one 1
4 would be a better than average loss of of fsite power group l
- 5 in terms of susceptibility to severe weather or expected a frequencies of losses of offsite power. l
! 7 MR. DENTON: Could you name some areas or plants a so the Commission can have a feel for who f alls in Category 3 9 I and who falls in Category II?
) W MR. RUBIN: To give you a touch of characteristics 1 .
] 11 in this Category I, this would include plants which have i
12 low frequencies of severe storms, plants which have increased r I
l 13 -- two independent switchyards, so they have less likelihood i
! 14 of losing power from the switchyards. Plants that have i
l 2 procedures to restore offsite power if it should be lost, j to procedures to restore power in a short period of time.
17 Category II might be plants that have higher j
I is susceptibility to storms and iust the other factors. Kind '
l 19 of a matrix wo set up here because we foun'd that the plants
. 3D with lower diesel generator redundancy and higher susceptibili:y 21 to loss of of fsite power were at higher ' risk from station j at blackout.
j
! 23 Therefore, we're giving guidance that they have .
1 j S4 a prooosed longer duration coping capability, which means if j 35 they have that coping capability, the likelihood of restoring 1 !
i
)
36 1 offsite power or power from either offsite or onsite sources 2 is increased, as compared to plants which have more diesel 3 generators, or better offsite power characteristics having 4 a lowe r --
5 And we feel most plants should be able to have the 6 capability to cope with four hours station blackout.
7 CHAIRMAN PALLADINO: I guess my question was, 8 suppose some plant comes in and says, look the right answer 9 for us is six hours.
10 MR. RUBIN: This is guidance and --
11 CHAIRMAN PALLADINO: It would be acceptable. I 12 mean, it could be acceptable.
13 MR. RUBIN: It could be acceptable.
14 CHAIRMAN PALLADINO: But now do I also get the 15 implication that if they came in with less than four hours 16 they're going to have a tough time justifying?
17 MR. RUBIN: That could be justified also.
18 MR. SPEIS: Initially we had a very big matrix, 19 you know, but kind of compressed it down.
30 COMMISSIONER ASSELSTINE: Let me just clarify that.
21 You say you're prepared to accept less than four hours?
22 MR. SPEIS: If somebody comes with 3.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> and
%I enough judgment there to -- procedures.
24 MR. RUDIN: There might be plants that have four 26 diesels on a site, something we didn't factor into this
i 4 . .
37 j 1 table, or real high diesel reliability that they can -- this ,
2 diesel reliability there, by the way, for example, is 95 I
I 3 percent, .05 failures per demand, that's below the industry
! 4 average of 98 percent.
t i
i 5 If they came in with improved reliability to try ,
e to say, here we don't need as long a duration of station
- 7 blackout duration. THat's a possibility.
j s CHAIRMAN PALLADINO: Were you going to add something i
j 9 more, Harold?
i l 10 MR. DENTON: This concludes our presentation unless i
I 11 Pat wanted to add anything.
I 12 MR. BARANOWSKY: No, I don't have anything to add.
13 MR. DENTON: Well, we were almost one hour exactly.
1 i j 14 CHAIRMAN PALLADINO: I've asked my two questions, I '
l un my two basic questions along the way. Let me ask if other
! 14 commissioners have questions.
17 COMMISSIONER ROBERTS: I've got a question, page is 16, over 500 emergency diesel generator failures during 4
to testing and actual demands in that, what, six-year period?
I j so can you give me some sense of how many actual test and i ,
4 21 demands were there? I'm asking what the average reliability i
{ tt rate is, I guess.
i i 23 MR. BAPANOWSKY: We have a table, if I can look i
j 34 it up I can tell you what it was. I can't remember the 26 statistics offhand.
i 1
. . I 38 1 COMMISSIONER ROBERTS: 500 failures. I want to 2 know to compare it to.
3 MR. RUBIN: Well, it's an average reliability of 4 98 percent. So two failures out of 100, which is what we 5 presented before.
6 COMMISSIONER ROBERTS: But the average is 98
'7 percent?
8 MR. RUBIN: Yes.
9 MR. BARANOWSKY: Yes, we had about 100 demands in 10 diesel generators when either loss of of fsite power or 11 loss of an onsite power bus occurred. Out of that we had 12 eight failures of which three of them were auto starts. In 13 other words, they could have been started by manual operation 14 rather than they weren't automatically started.
15 So we had five cases that were not started, 14 auto start or any other way. And three additional cases where 17 the operator actually had to hit the button to start it out 18 of 100. That's through 1982, I believe. We don't have the 19 statistics for '83 and '84 yet.
20 And about the same kind of experience has occurred 21 -- actually a little better for safety injection actuations 22 in which we had 539 in this time period. That's safety 23 injection actuations resulting in a demand on the diesel 24 generators.
26 MR. DENTON: So just to clarify, you're saying an
- 39 1 actual, when it was called upon to work there were five 2 cases out of 100 in which it did not auto start. All the 3 rest of the ones were under testing conditions.
4 MR. BARANOWSKY: Pight.
8 COMMISSIONER ROBERTS: Okay, that's all.
6 CHAIRMAN PALLADINO: Any others?
7 COMMISSIONER ASSELSTINE: I -- and I suspect Fred a may be in the same situation -- have a whole slew of questions .
g And I take it we've got another meeting. Maybe I can ask to just a couple and then, I don't know what --
11 CHAIR!!AN PALLADINO: It may turn out that -- the 12 problem is we have the regional administrators here for the 13 next meeting and one of them has to make a plane. Now the 14 other --
18 COMMISSIONER BERNTHAL: I think we need another 14 meeting.
17 COMMISSIONER ASSELSTINE: Maybe that's the best is way to do it.
13 CHAIRMAN PALLADINO: Yes, that's what I was going 30 to poll at the end of the meeting, should we go ahead and 21 schedule another meeting.
22 COMMISSIONER ASSELSTINE: But given the time 23 constraints maybe that's the best thing to do because I must 24 have 15 questions at least.
26 CHAIRPAN PALLADINO: Well, is there any one of them
k -
- 40 1 .
1 1 that you want to --
3 MR. DIRCKS: Maybe you want to give them -- at the
- 3 next meeting, if you'd like to give them to us we can start i
1 4 preparing answers to them and be prepared at the next meeting ,
I
! 5 to go into them in depth.
! 6 COMMISSIONER ASSELSTINE: Okay, or I can even sit
' down -- I did this once already on this issue -- just sit 7
4 i
s down -- ,
3 CHAIRMAN PALLADINO: It is valuable to have your, 6 10 I think, questions because when they answered them --
I l 11 MR. DIRCKS: Well, we can circulate the answers to 12 all the commissioners.
COMMISSIONER ASSELSTINE: Okay.
l 13 14 COMMISSIONER BERNTHAL: Well, I have a number of un questions too, and there's no way we're going to get through i is them. I'm particularly curious about, for example, about I
17 the errors that you attached, the uncertainties attached l
18 to your rather bare two to one cost effectiveness calculation.
19 But let's not go through all that. There just isn't time.
l l 20 CHAIRMAN PALLADINO: Okay, i
- 21 COMMISSIONER ZECH: I have a couple questions too, l It but I'll be happy to give them to the staff. Also I think 23 it would be helpful to me to hear from Vic Stello, at least 24 get his experience in reviewing the generic requirements as i 26 part of the staff presentation. But I'll be happy to give l l t I
s !
, . 41 1 you my questions in. writing.
i 2 COMMISSIONER ASSELSTINE: I think we can do better !
l l 3 justice to them that way then to try to rush through.
4 CHAIRMAN PALLADINO: Okay, well, why don' t you i s submit the questions in writing would be helpful, then we e all see the questions. And if you answer them in writing, i
. 7 we all see the answers. And at agenda planning we'll set s up another meeting on this subject.
9 MR. DIRCKS: You may want to hear from the NUGSBO i 10 group.
! 11 CHAIRMAN PALLADINO: Well, for a while I thought
! 12 they had asked, but apparently they didn't. But that's !
i j 13 a possibility.
i i 14 Okay, well, maybe that serves as good background i
is to raising the cuestion, and perhaps the best thing to do 14 now is to adjourn, take five minutes to sort out our papers !
i l 17 and come back.
i j
j 18 COMMISSIONER ASSELSTINE: Given the time limits
}
1e I think the staff did real good in getting through a long 30 and complex subject that I know a lot of you spent a lot of I
21 time on.
I J 22 CHAIRMAN PALLADINO: Yes, they did very, very well.
l 23 So thank you very much, we stand adjourned.
! 24 (whereupon, at 3:31 p.m., the commission meeting 26 was adjourned.)
i l
' CERTIFICATE OF OFFICIAL REPORTER 1
2 3
4 4
5 This is to certify that the attached proceedings 6 before the United States Nuclear Regulatory Commission in the 7 matter of COMMISSION MEETING e
9 Name of Proceeding: Discussion Of Proposed Station Blackout Rule (Public Meeting) 11 Docket No.
12 P l ace ? tlashington, D. C.
ta cate: Wednesday, September 11, 1985 14 15 were held as herein appears and that this is the original 16 transcript thereof for the file of the United States Nuclear 17' Regulatory Ccm ission.
13 (Signature) g (TypedNameofReporter,)s.(/PanelaBriggl&-
to 21 i
22 23 Ann Miley & Associates, Ltd.
24 25
- . . . . . _- . = - _- _ _ __ . _ . -_ - . . .
- s i
4 1
l PRESENTATION TO THE COMMISSION ON STATION BLACK 0UT (UNRESOLVED SAFETY ISSUES A-44) 1 i
J j BY
.i j H. DENTON, T. SPEIS AND A. RUBIN i
0FFICE OF NUCLEAR REACTOR REGULATION U. S. NUCLEAR REGULATORY COMMISSION SEPTEMBER 11, 1985
]
i i
- i
)
- e e
DEFINITION OF ISSUE DEFINITION OF STATION BLACK 0UT THE COMPLETE LOSS OF AC POWER FROM BOTH THE OFFSITE AND ONSITE EMERGENCY AC POWER SOURCES.
OBJECTIVE OF USI A-44 IDENTIFY THE LIKELIHOOD AND POTENTIAL ACCIDENT RISK 0F STATION BLACK 0UT.
SHOULD ADDITIONAL PREVENTIVE AND/0R MITIGATIVE MEASURES BE REQUIRED?
CONSIDERATIONS FOR RESOLVING USI'A-44 i
OPERATING EXPERIENCE PRACTICAL LIMITS ON RELIABILITY OF 0FFSITE AND ONSITE AC POWER SYSTEMS i -
. AC POWER RELIABILITY VARIES SIGNIFICANTLY FROM PLANT I TO PLANT POTENTIALLY SEVERE CONSEQUENCES 4
LIMITED DECAY HEAT REMOVAL CAPABILITY W/0 AC POWER NO CONTAINMENT HEAT REMOVAL W/0 AC POWER RISK REDUCTION ALL PLANTS SHOULD BE ABLE TO COPE WITH A STATION BLACK 0UT FOR A SPECIFIED DURATION NEED GUIDELINE TO DETERMINE DURATION A CORE MELT FREQUENCY FROM STATION BLACK 0UT OF
! 10-5/RY WOULD RESULT IN LOSS OF ALL AC POWER BEING A SMALL CONTRIBUTOR TO OVERALL RISK l
l l
O
CURRENTLY, THERE IS N0' REQUIREMENT THAT NUCLEAR POWER PLANTS MUST BE ABLE TO WITHSTAND A CONCURRENT LOSS OF BOTH THE OFFSITE AND ONSITE EMERGENCY AC POWER SYSTEMS.
CONCLUSIONS DRAWN FROM EXTENSIVE REVIEW 0F OPERATING l!
EXPERIENCE AND TECHNICAL ANALYSIS INDICATE THAT THE i ABILITY TO COPE WITH STATION BLACK 0UTS OF SOME DURATION i
WOULD KEEP STATION BLACK 0UT FROM BEING A SIGNIFICANT CONTRIBUTOR TO TOTAL CORE DAMAGE FREQUENCY.
s I
l i
i
- I
l l
l
- PROPOSED RESOLUTION OF USI A-44, STATION BLACK 0UT PROPOSED RULE GENERAL REQUIREMENT THAT PLANTS SHOULD BE ABLE TO COPE 4
WITH A STATION BLACK 0UT FOR A SPECIFIED DURATION i
DRAFT REGULATORY GUIDE .
GUIDANCE ON ACCEPTABLE STATION ELACK0UI DURATION TO COMPLY WITH PROPOSED RULE.
GUIDANCE TO EVALUATE CAPABILI 'l :F .' FLANT TO COPE WITH A STATION BLACK 0UT.
GUIDANCE ON MAINTAINING MINIMUM EMERGENCY DIESEL GENERATOR RELIABILITY.
- l GUIDANCE ON PROCEDURES TO RESTORE OFFSITE POWER.
l I
-- N -
1985 POLICY AND PLANNING GUIDANCE PROPOSED RULE COMPLIES WITH POLICY FOR NEW REQUIREMENTS "T0 THE EXTENT PRACTICABLE, ISSUES WHICH AFFECT NUMEROUS LICENSEES SHOULD BE ADDRESSED IN THE CONTEXT OF RULE-MAKING OR STANDARD ORDERS AS OPPOSED TO CASE-BY-CASE REVIEW."
"NRC REGULATIONS SHOULD ALLOW INDIVIDUAL LICENSEES THE' FLEXIBILITY TO SELECT THE MOST COST-EFFECTIVE WAYS TO SATISFY NRC SAFETY OBJECTIVES, PARTICULARLY FOR PLANT SPECIFIC REQUIREMENTS."
l
\
G)
, . e FINAL BACKFIT RULE PROPOSED RESOLUTION COMPLIES WITH THE FINAL BACKFIT RULE THERE WOULD BE A SUBSTANTIAL INCREASE IN THE OVERALL PROTECTION OF THE PUBLIC HEALTH AND SAFETY TO BE DERIVED FROM THE PROPOSED RULE. .
THE DIRECT AND INDIRECT COSTS OF' IMPLEMENTATION OF THE PROPOSED RULE ARE JUSTIFIED IN VIEW 0F THIS INCREASED PROTECTION.
o
FOREIGN EXPERIENCE STATION BLACK 0UT CAPABILITY OF 20 HOURS FOR FRENCH PLANTS, DESIGN TO COPE WITH STATION BLACK 0UT AND FOUR ONSITE EMERGENCY DIESEL GENERATORS FOR BRITISH SIZEWELL PWR, INCREASED REDUNDANCY OF ONSITE AC POWER SYSTEMS IN GERMANY, SWITZERLAND, NETHERLANDS, ITALY AND BELGIUM, e
INTERACTIONS WITH INDUSTRY ON USI A-44 IEEE WORKING GROUP SC-4.3, LOSS OF ALL AC FEB 1982 TO PRESENT ANS STANDARD WORKING GROUP 58.12, DESIGN FOR LOSS OF ALL AC POWER FORMED JUNE 1983 DRAFT STANDARD FOR COMMENT MAY 1984 NUCLEAR UTILITY GROUP ON STATION BLACK 0UT FORMED JUNE 1984 PROPOSED INTEGRATION PLAN TO NRC OCT 1984 PROPOSAL FOR RESOLUTION OF USI A-44 MAY 1985 PRESENTATIONS TO INDUSTRY CONFERENCES 1982 TO PRESENT AND SEMINARS (IEEE, ANS, NUS, USI REVIEW SEMINAR) a
5
, NUCLEAR UTILITY GROUP ON STATION BLACK 0UT (NUGSBO)
PROPOSAL FOR THE RESOLUTION OF USI A-44 IMPLEMENT PLANT-SPECIFIC PROGRAMS TO ENHANCE AC POWER RELIABILITY .
PROCEDURES AND TRAINING TO RESTORE AC POWER EVALUATION AND CORRECTION OF ROOT CAUSES OF LOSSES OF AC POWER SOURCES REDUCTION IN FREQUENCY OF EMERGENCY DIESEL GENERATOR COLD FAST STARTS j PROCEDURES IN THE EVENT OF SEVERE WEATHER EVALUATION OF PROCEDURES AND TRAINING FOR OPERATORS TO COPE WITH STATION BLACK 0UT INDUSTRY-WIDE EVALUATION OF SIGNIFICANT EVENTS l RELATING TO AC POWER RELIABILITY 4
ISSUE A COMMISSION POLICY STATEMENT L
RECOGNIZING INDUSTRY INITIATIVES TO ENHANCE AC POWER RELIABILITY REFRAINING FROM RULEMAKING TO RESOLVE STATION BLACK 0UT i
~
i .
l l l
1 L
NUGSB0 PROPOSAL (CONTINUED)
C0 ORDINATE RESOLUTION OF POWER-RELATED ISSUES B-56, DIESEL GENERATOR RELIABILITY GENERIC ISSUE 23, REACTOR COOLANT PUMP SEAI.S USI A-45, SHUTDOWN DECAY HEAT REMOVAL A-30, DC POWER SUPPLIES j
e f
i
1 STAFF EVALUATION OF NUGSB0 PROPOSAL ELEMENTS OF PROPOSAL TO ENHANCE AC POWER RELIABILITY ARE INCLUDED IN STAFF'S PROPOSED RESOLUTION.
NUGSB0 USED STAFF METHODOLOGY TO EVALUATE CORE DAMAGE FREQUENCY FROM STATION BLACK 0UT.
NUGSBO'S CONCLUSION THAT RULEMAKING IS NOT REQUIRED IS
- BASED ON OPTIMISTIC ASSUMPTIONS FOR FREQUENCY OF LOSSES OF l OFFSITE POWER AND DIESEL GENERATOR RELIABILITY AND LEAVES l LITTLE MARGIN FOR DEGRADATION IN RELIABILITY OF THESE SYSTEMS.
FOR STATION BLACK 0UT TO BE A SMALL CONTRIBUTOR TO TOTAL CORE MELT FREQUENCY, COPING CAPABILITY IS NECESSARY.
WITHOUT RULEMAKING, THERE IS NO BASIS IN NRC'S REGULATIONS TO REQUIRE CAPABILITY TO COPE WITH STATION BLACK 0UT.
i I
i
APPROACH FOR RESOLUTION OF ISSUE DETERMINE CURRENT LIKELIHOOD AND LEVEL OF RISK DUE TO STATION BLACK 0UT FOR A SPECTRUM OF PLANT DESIGNS.
COMPARE RESULTS WITH OTHER NUCLEAR PLANT ACCIDENT RISKS.
IDENTIFY DOMINANT FACTORS AFFECTING RISK AND COST l EFFECTIVE IMPROVEMENTS.
AC POWER RELIABILITY ABILITY TO COPE WITH EXTENDED LOSS OF AC POWER (CAPABILITY AND RELIABILITY).
PROPOSE NEW OR REVISED LICENSING REQUIREMENTS CONSISTENT WITH LEVEL OF RISK, AND COST EFFECTIVENESS.
F Il t
SUMMARY
OF STATION BLACK 0UT PROGRAM TECHNICAL RESULTS LOSS OF 0FFSITE POWER AVERAGE 0,1 PER SITE-YEAR RANGE O To 0.4 PER SITE-YEAR TIME TO RESTORE OFFSITE POWER MEDIAN 1/2 HOUR 90% RESTORED 3 HOURS EMERGENCY DIESEL GENERATOR RELIABILITY AVERAGE 0.98 PER DEMAND RANGE 0.9 TO 1.0 PER DEMAND i
MEDIAN EMERGENCY DIESEL GENERATOR REPAIR TIME 8 HOURS ESTIMATED RANGE OF EMERGENCY AC POWER SYSTEMS UNAVAILABILITY 10-4 TO 10-2 PER DEMAND ESTIMATED RANGE OF STATION BLACK 0UT FREQUENCIES 10-5 TO 10-3 PER YEAR 1
- l. ESTIMATED RANGE OF CORE DAMAGE
, FREQUENCIES FROM STATION BLACK 0UT 10-6 TO 10-4 PER YEAR I 12
SUMMARY
OF STAFF FINDINGS RELIABILITY OF ONSITE EMERGENCY AC POWER SYSTEMS VARIES CONSIDERABLY CONFIGURATION REDUNDANCY EMERGENCY DIESEL GENERATOR (EDG) RELIABILITY FREQUENCY AND DURATION OF 0FFSITE POWER LOSS VARY CONSIDERABLY SITE CHARACTERISTICS (WEATHER, GRID)
PLANT FACTORS (SWITCHYARD DESIGN, TRANSMISSION LINES)
EXTENDED DURATION STATION BLACK 0UTS (>2 HOURS) CAN BE SIGNIFICANT CONTRIBUTORS TO RISK CORE DAMAGE FREQUENCY FROM STATION BLACK 0UT VARIES CONSIDERABLY FROM PLANT TO PLANT SUSCEPTIBILITY TO STATION BLACK 0UT ABILITY TO COPE WITH LOSS OF ALL AC POWER NO SINGLE FIX APPLIED UNIFORMLY TO ALL PLANTS WILL RESOLVE THIS ISSUE IN A COST-EFFECTIVE MANNER 13
RECOMMENDATIONS FOR RESOLVING USI A-4h PUBLISH PROPOSED RULE WHICH WOULD REQUIRE ALL PLANTS TO BE ABLE TO WITHSTAND AND REC 0VER FROM A STATION BLACK 0UT OF A SPECIFIED DURATION, ISSUE DRAFT REGULATORY GUIDE IN SUPPORT OF RULE l
GUIDELINES FOR ALL PLANTS PROCEDURES AND TRAINING TO COPE WITH STATION BLACK 0UT MINIMUM EDG RELIABILITY GUIDELINES CONSIDERING PLANT DIFFERENCES HOW TO DETERMINE ACCEPTABLE TIME TO WITHSTAND STATION BLACK 0UT a
l 1
TW
El.EMENTS OF STATION BLACK 0UT PROGRAM OPERATING EXPERIENCE RELEVANT TO STAT!.0N BLACK 0UT LOSS OF 0FFSITE POWER l'
FREQUENCY AND DURATION ESTIMATED ACCIDENT SEQUENCE PROPOSED STATION CHARACTERISTICS :s TECilNICAL 6 BLACK 0UT 2 AND CORE MELT RESOLUTION FREQUENCY FREQUENCY AND (DOMINANT EMERGENCY AC POWER :
DURATION ACCIDENT SEQUENCES)
RELIABILITY
SUMMARY
OF OPERATING EXPERIENCE RELEVANT TO FROM 1968 - 1983:
47 TOTAL LOSS OF 0FFSITE POWER EVENTS OF A FEW MINUTE DURATION UP TO 9 HOURS FROM 1976 - 1982:
OVER 500 EMERGENCY DIESEL GENERATOR FAILUR DURING TESTING AND ACTUAL DEMANDS; 46 INSTANCES INVOLV MULTIPLE FAILURES DUE TO COMMON CAUSE OR DOU FROM 1968 - 1983:
SEVERAL STATION BLACK 0UT PRECURSORS INV TOTAL LOSS OF 0FFSITE POWER AND UNAVAILABI OF ONE OR MORE EMERGENCY AC POWER SUPPLIES.
SEVERAL OF THESE INCIDENTS INVOLVED LOSS OF ALL AC POW BLACK 0UTS
PRECURSORS TO STATION BLACK 0UT 1968 SWITCHING ERROR CAUSED LOSS OF OFFSITE POWER (PLANT AT 100% POWER); DIESELS STARTED AND LOADED BUT TRIPPED OFF (4 MIN, W/0 AC: 25 MIN. TO RESTORE OFFSITE POWER),
1976 UNDERV0LTAGE TRIP CAUSED LOSS OF 0FFSITE POWER (PLANT '
! AT 100% POWER): DIESELS STARTED BUT UNDERVOLTAGE CAUSED LOADS TO TRIP FROM SAFETY BUS (5 MIN, W/0 AC).
1983~ SEVERE WEATHER (SNOWSTORM) CAUSED LOSS OF 0FFSITE POWER (PLANT SHUTDOWN); ONE DIESEL OUT FOR MAINTENANCE SECOND DIESEL WAS BEING PARALLELED; LOAD-SHEDDING RELAY FAILURE RESULTED IN LOSS OF ALL
- AC POWER FOR 25 MIN, 4
1984 DURING LOSS OF 0FFSITE POWER TEST, OPERATORS MISTAKENLY SWITCH OFF DC CONTROL POWER KHICH .
PREVENTED EMERGENCY AC POWER SUPPLY OPERABILITY OR RETURN OF NORMAL POWER. ALL AC POWER UNAVAILABLE FOR 10 MINUTES, m
w h
SUMMARY
OF LOSS OF 0FFSITE POWER EXPERIENCE (1968 THROUGH 1983)
MEDIAN FREQUENCY DURATION CATEGORY N0. EVENTS (PER SITE-YEAR) (HOURS)
PLANT-CENTER 5D 33 0.056 0.3 GRID 11 0.020 0.7 SEVERE STORM 6 0.011 2.6 TOTAL 47 0.088 0.5 9
0
. _ . __ . - . - . =.
FREQUENCY OF LOSS-OF-0FFSITE-POWER EVENTS '
EXCEEDING SPECIFIED DURATIONS (INDUSTRY AVERAGE)
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Estimated Range of Frequency of Loss of Offsite Power Events Exceeding Specified Duration for Plants with Different Switchyard Design, Grid Reliability, and Susceptibility to Severe Weather
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FAILURE CONTRIBUTION BY DIESEL GENERATOR SUBSYSTEM !
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ELEMENTS OF STATION BLACK 0UT PROGRAM OPERATING EXPERIENCE RELEVANT TO STATION BLACK 0UT LOSS OF 0FFSITE POWER FREQUENCY AND DURATION
- ESTIMATED ACCIDENT SEQUENCE PROPOSED STATION CHARACTERISTICS :r TECilNICAL
{ BLACK 0UT AND CORE MELT RESOLUTION FREQUENCY ' FREQUENCY AND (DOMINANT EMERGENCY AC POWER 31 DURATION ACCIDENT SEQUENCES)
RELIABILITY
, INSIGHTS GAINED FROM RESULTS OF STATION BLACK 0UT PRA ANALYSES DOMINANT ACCIDENT SEQUENCES ESTIMATES OF TIME TO CORE MELT IF AC POWER IS NOT
- RESTORED.
- IMPORTANT SYSTEMS NECESSARY TO COPE WITH STATION BLACK 0UT SIGNIFICANT PARAMETERS THAT IMPACT CORE MELT FREQUENCY l FROM STATION BLACK 0UT
- l 1 -
0FFSITE POWER SUSCEPTIBILITY TO LOSSES OF 0FFSITE POWER l LIKELIHOOD OF RESTORING OFFSITE POWER EMERGENCY ONSITE AC POWER SYSTEM I
INDIVIDUAL DIESEL GENERATOR RELIABILITY
- EDG CONFIGURATION f -
ABILITY TO COPE WITH STATION BLACK 0UT l
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Plant's Ability to Cope with Station Blackout (hours)
PRESENT REQUIREMENTS AND GUIDANCE RELATED TO STATION BLACK 0UT PRESENTLY NO REQUIREMENTS TO COPE WITH STATION BLACK 0UT GDC 17 - REDUNDANCY OF 0FFSITE AND ONSITE EMERGENCY AC POWER SYSTEMS REGULATORY GUIDE 1.108 - DIESEL GENERATOR TESTING ACTIONS FLOWING FROM ST. LUCIE - GENERIC LETTER ON PROCEDURES FOR STATION BLACKOUT NUREG-0737, ITEM II.E.1.1 - AC INDEPENDENCE OF AUXILIARY FEEDWATER SYSTEM
PROPOSED RULE
. ADDITIONAL PARAGRAPH TO APPENDIX A, GDC 17
~
THE REACTOR CORE AND ASSOCIATED COOLANT, CONTROL, AND l PROTECTION SYSTEMS, INCLUDING.THE BATTERIES, SHALL PROVIDE SUFFICIENT CAPACITY AND CAPABILITY TO ASSURE THAT THE CORE IS COOLED AND CONTAINMENT INTEGRITY IS MAINTAINED IN THE EVENT OF A STATION BLACK 0UT FOR A SPECIFIED DURATION, THE FOLLOWING FACTORS SHALL BE CONSIDERED IN SPECIFYING THE STATION BLACK 0UT DURATION: (1) THE REDUNDANCY OF THE ONSITE EMERGENCY AC POWER l SOURCES, (2) THE RELIABILITY OF THE ONSITE EMERGENCY AC POWER SOURCES, (3) THE EXPECTED FREQUENCY OF LOSS OF 0FFSITE POWER, AND (4) THE PROBABLE TIME NEEDED TO RESTORE OFFSITE POWER.
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IMPLEMENTATION OF PROPOSED RULE LICENSEES SUBMIT STATION BLACK 0UT DURATION, DESCRIPTION OF PROCEDURES AND FACTORS LIMITING ABILITY TO COPE.
NRC REVIEW PROPOSED DURATION.
NRC AND LICENSEES MUTUALLY AGREE ON SCHEDULE FOR EQUIPMENT MODIFICATIONS, IF NEEDED.
4
PROPOSED STATION BLACK 0UT RULE (I) (II) (III) (IV)
DETERMINE TIME DETERMINE PLANT CAN COPE DESCRIBE IDENTIFY MINIMUM
- => + =
WITH STATION PROCEDURES LIMITING ACCEPTABLE BLACKOUT (T1 ) FACTORS STATION BLACK 0UT DURATION (T2 )
(
IS Ty>T? 2 N0
- IMPLEMENT PLANT MODIFICATIONS TO EXTEND CAPABILITY TO COPE WITH STATION BLACK 0UT YES V
l NO PLANT MODIFICATIONS NECESSARY
DRAFT REGULATORY GUIDE ONSITE EMERGENCY AC POWER SYSTEMS RELIABILITY PROGRAM TO MAINTAIN EDG RELIABILITY MAXIMUM EDG FAILURE RATE PROCEDURES FOR RESTORING EMERGENCY AC POWER OFFSITE POWER PROCEDURES TO RESTORE OFFSITE POWER AND USE NEARBY OFFSITE POWER SOURCES.
ABILITY TO COPE WITH STATION BLACK 0UT EVALUATION OF ABILITY TO COPE WITH STATION BLACK 0UT SELECTION OF MINIMUM ACCEPTABLE STATION BLACK 0UT DURATION CAPABILITY MODIFICATIONS TO PLANT (IF NECESSARY)
PROCEDURES AND TRAINING 4
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ACCEPTABLE STATION BLACK 0UT DURATION CAPABILITY (HOURS)
EMERGENCY AC POWER CONFIGURATION GROUP 1/3 1/2 2/3 0FFSITE POWER MAXIMUM EDG FAILURE RATE PER DEMAND 1
DESIGN CHARACTERISTICS 0.05 0.025 0.05 -0.025 I 4 4 4 4 II 4 4 8 8 e
IMPORTANT ITEMS TO MEET PROPOSED DURATION GUIDELINES CAPACITY OF SYSTEMS AND COMPONENTS DC BATTERIES CONDENSATE STORAGE TANK COMPRESSED AIR REACTOR COOLANT PUMP (RCP) SEAL INTEGRITY AC-INDEPENDENT CHARGING PUMP FOR RCP SEAL COOLING IF RCP SEAL INTEGRITY CANNOT BE VERIFIED FOR THE STATION BLACK 0UT DURATION, 4
VALUE/ IMPACT
SUMMARY
POTENTIAL PLANT MODIFICATIONS EXTEND DC CAPACITY EXTEND CONDENSATE STORAGE TANK / COMPRESSED AIR CAPACITIES VERIFY RCP SEAL INTEGRITY IMPROVE EDG RELIABILITY ESTIMATED COST AVERAGE $600,000/ PLANT RANGE $200,000 - $4 MILLION TOTAL COST TO INDUSTRY - APPR0XIMATELY $40 MILLION RISK REDUCTION 80,000 MAN-REM VALUE/ IMPACT RATIO 2,000 MAN-REM /$1 MILLION
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t USI A-44 CHRONOLOGY TASK ACTION PLAN APPROVED JULY 1980 DRAFT TECHNICAL RESOLUTION COMPLETED APRIL 1983 (W/0 RULEMAKING)
LETTER FROM ACRS JULY 1983 DRAFT TECHNICAL RESOLUTION COMPLETED NOVEMBER 1983 (W/RULEMAKING)
PROPOSED RESOLUTION TO CRGR MARCH 1984 CRGR REVIEW COMPLETED MAY 1984 NUCLEAR UTILITY GROUP ON JUNE 1984 STATION BLACK 0UT FORMED
[
LETTER FROM ACRS MARCH 1985 l
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PROPOSED RULE TO COMMISSION MAY 1985 [
t FOLLOW-UP COMMISSION PAPER ON SEPTEMBER 1985 NUGSB0 PROPOSAL '
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With EDG Common Cause Fadute
Without EDG Common Cause Failure
. Emergency AC Configuration (2 of 3)
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I I I I 0.92 0.94 0.96 0.98 EDG RELIABILITY Figure 4.' Generic emergency AC power unavailability as a function of emergency diesel generator (EDG) reliability NUREG-1032 4-16
. . - . _ _ . _ - - . ._ .. . _ _ .- - - _ . .- - - . - . _ = - . , _ . _ . .
I I I 1.'2 EDG Configuration
, 0.975 EDG Reliability i O
> 10'5 -
5 5
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STATION BLACKOUT DURATION (Hours) I e
j Figure 5.1 Estimated frequency of station blackout exceeding specified durations for several representative offsite l
power clusters
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5-2 i i
I I i Offsite Power Cluster 7 1/2 EDG Configuration i
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- 0.9 i
-0,95
- 0.975 j 10'7 -
- 0.99 1 I i 0 4 8 12 16 STATION BLACKOUT DURATION IHoursi Figure 5.2 Estimated frequency of station blackout exceeding specified durations for several EDG reliability levels l
NUREG-1032 5-3 l
I I i Offsite Power Cluster 7 10'd - ' ""* "'Y l
5 10 0
3 4
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g AC Power w Configuration c
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, , , -1/3 0 4 8 12 16 l STATION BLACKOUT DURATION (Hourst Figure 5.3 Estimated frequency of station blackout exceeding specified durations for several emergency AC power configurations NUREG-1032 5-4
Table 6.1 Effects of station blackout on plant decay heat removal functions Plant Functions (systems) Functions (systems)
Type remaining lost PWR Shutdown heat removal Shutdown heat removal (motor-4 (steam-driven AFWS, ADVs) driven AFWS)
- Long-term heat removal (RHR) i Instrumentation and control (DC power / converted AC Reactivity control (chemical .
power, compressed air volume and control system reservoir)
RCS makeup (high pressure 3
injection system)
Pressure and temperature control (pressurizer heaters /
spray and pilot-operated relief j
valves) i
, , Support systems (service / component cooling water systems, HVAC, station air compressors)
~
BWR, Shutdown heat removal Long-term heat removal (RHR) 2/3 (isolation condenser, fire
- water system) Reactor coolant system makeup i
(low pressure core spray system, feedwater coolant injection system)
Instrumentation and control Support systems (DC power / converted AC (service / component cooling power, compressed air water systems, HVAC, station reservoirs) air compressors)
BWR, Shutdown heat removal and Long-term heat removal l 4-6 reactor coolant system makeup (shutdown cooling system, (HPCI or HPCS/RCIC systems) low pressure coolant ,
recirculation system, Instrumentation and control suppression pool cooling (DC power / converted AC system) power, compressed air reservfors) Support systems (service / component cooling water systems, HVAC, station air compressors) i f
1 l
) NUREG-1032 6-2 1
ll Table 7.2 Summary of potentially dominant core damage accident sequences -
E!
[ Time in which AC power g; Generic
-plant Sequence must be recovered Typical core DHR system / component contributors to avoid core damage, hr damage frequency PWR TML B Steam driven AFWS unavailable 1 to 2 5x 10 6 (all)
TML2B2 DC power or condensate exhausted 4 to 16 1x 10 5 TMQ2B2 Reactor coolant pump seal leak 4 to 16 1x 10 5 BWR TMU B Isolation condenser unavailable 1 to 2 2x 10 6 w/ isolation condenser TMQB Stuck-open relief valve 1 to 2 3 x 10 6 TMQ2B 2 Reactor coolant pump seal leak 4 to 16 2 x 10 5
][ BWR TMU B HPCI/RCIC unavailable 1 to 2 2 x 10 6 c,
w/HPCI-RCIC TMU22 8 DC power or condensate exhausted, 4 to 16 2 x 10 5 component operability limits i exceeded (HPCI/RCIC)
BWR TMui 8 HPCS/RCIC unavailable 1 to 2 5 x 10 7 w/HPCS-RCIC TMU22 B HPCS unavailable, DC power or 4 to 16 1 x 10 6 condensate exhausted, component operability limits exceeded (RCIC) 0 I i
_ _ . _ , . , _ , , , , , , _ _ , _ . , . _ . _ - - . _ ~ . , , _ _ _ , . _ _ _- -. _ - . _ - __ ,
10**
l l l 1/2 AC Conhgurcina 0.975 EDG Reliability i
4 AC Independent DHR Systern 1 Train
--2 Trains a
3 y 10-8 - h
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N 4
o
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E m 10.s -
\_ 4 c
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$ 10 7 - N - 2
\
10.s l l l 0 4 8 12 16 STATION BLACKOUT CAPABILITY (Hours)
Figure 8.1 Sensitivity of estimated station blackout-core damage frequency to offsite power cluster, AC-independent decay heat removal reliability, and station blackout coping j capability NUREG-1032 8-3
t l l l Off sete Power Cluster 7 1/2 AC Power Configuration t
f 5
AC. independent DHR System 1 Train U - 2 Trains a
3: 10.s _
g EDG Reliability i
f w
\\\ \
w i \\ \
N 0.9 0
10.a -
\%
~
0.95 i \ N N 0.975 0.99
\N NN 10-7 l [ g 0 4 8 12 16 STATION BLACKOUT CAPABILITY (Hours)
Figure 8.2 Sensitivity of estimated station blackout-core damage frequency to emergency diesel generator reliability, AC-independent decay heat removal reliability, and station blackout coping capability NUREG-1032 8-4
i i
' l Offsite Power Cluster 7 10-* -
0.975 EDG Releability i
AC independent DHR System 1 Train
--2 Trains e 10.s -
U f \ AC Power Configuration a \T\\
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\ 2/3 0 10-s - \
< T 3 \ 1/2 a
w
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l i 10 7 -
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1/3 xN io.s 1 I I 0 4 8 12 16 STATION BLACKOUT CAPABILITY (Hours) l i
Figure 8.3 Sensitivity of estimated station blackout-core damage frequency to emergency AC power configurations, AC-independent decay heat removal reliability, and station blackout coping capability NUREG-1032 8-5
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l I
RELATIONSHIP TO OTHER ISSUES B-56, DIESEL GENERATOR RELIABILITY IMPROVEMENT PROGRAM B-23, RCP SEALS A-45, SHUTDOWN DECAY HEAT REMOVAL REQUIREMENTS l
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F mi - _ _ _ _ _ _ - _ _ _ _ . _ _ _ _ _ _ . _ _ _ _ . _ _ _ _ _ _ _ _ . _ - _ _ _ _ _ . _ _ _ _ . . _ . _ _ _ _ . _ _ . _ . _ _ _ _ . . _ _ _ _ . _
1
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RELATIONSHIP BETWEEN A-44 AND 8-56 A-44 B-56
- PROVIDES EXAMPLE RELIABILITY DEPENDING ON DG PERFORMANCE TECHNICAL CONFIGURATION AND STATION SPECIFICATION TO MEET BLACK 0UT DURATION. A RELIABILITY G0AL OF 0.95
- RELIES ON 8-56 TO MAINTAIN
- REQUESTS DESCRIPTION OF LICENSEE'S PROGRAM TO MAINTAIN DG RELIABILITY.
- WILL REVIEW RESPONSES AND TAKE APPROPRIATE PLANT-SPECIFIC ACTIONS TO UPGRADE OUTL'IERS.
l RELATIONSHIP BETWEEN A-44 AND B-23 A-44 B-21
- RECOMMENDS GUIDELINES ON RCP SEAL INTEGRITY FOR SPECIFIC STATION BLACK 0UT DURATIONS .
- IF SEAL INTEGRITY CAN NOT BE DEVELOPS DATA TO DETERMINE VERIFIED, THAN PLANT MAY NEED AC- RCP SEAL BEHAVIOR W/0 INDEPENDENT CHARGING SYSTEM FOR COOLING SEAL COOLING d
9 O
t PELATIONSHIP BETWEEN A-44 AND A-45 A-44 A-45 SCOPE DHR SYSTEM ADEQUACY DHR SYSTEM OVERALL i
W/0 AC POWER ADEQUACY ISSUE SHOULD PLANTS BE ABLE ARE ADDITIONAL DHR TO WITHSTAND STATION MEASURES NEEDED TO BLACK 0UT? IF S0, FOR ASSURE DHR RELIABILITY HOW LONG? FOLLOWING TRANSIENTS, ACCIDENTS, OR SPECIAL EMERGENCIES MAJOR CONSIDERATIONS CONCURRENT LOSS OF DHR SYSTEM RELIABILITY, OFFSITE AND ONSITE AC INITIATING TRANSIENTS, POWER; AC-INDEPENDENT INITIATING ACCIDENTS, DHR SYSTEM RELIABILITY; SABOTAGE, FIRE, FLOOD REC 0VERY OF AC POWER POSSIBLE SYSTEM EXTEND CAPACITY OF DC FEED AND BLEED: ADD-0N MODIFICATIONS BATTERIES, CST AND SUPPRESSION POOL COMPRESSED AIR COOLING: DEDICATED DHR CHARGING PUMP FOR RCP SYSTEM W/ DIESEL
< SEAL COOLING GENERATOR SCHEDULE ISSUE RESOLUTION FOR C0f1 MENT 09/35 EARLv 1986 ISSUE FINAL RESOLUTION 12/86 1987 CA F%
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TRANSMITIAL 'IO: ny, w nt Control Desk, 016 Phillips ADGNCED COPY 'IO: // We Public Document Bom DATE: // 3 /((, cc: C&R j
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Attached are copies of a Otmission meeting transcript (s) and related meeting docment(s) . Wey are being forwarded for entry on the Daily Accession List and pinmt in the Public Doceent Ibm. No other distribution is requested or required. Existing DG identification numbers are listed on the individual documents wherever known.
Meeting
Title:
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