ML20046C814
| ML20046C814 | |
| Person / Time | |
|---|---|
| Issue date: | 07/20/1993 |
| From: | NRC COMMISSION (OCM) |
| To: | |
| References | |
| REF-10CFR9.7 NUDOCS 9308120217 | |
| Download: ML20046C814 (82) | |
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1 UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMIS SION
$I6 BRIEFING ON OPTIONS FOR ADDRESSING SHUTDOWN AND LOW POWER RISK ISSUES LOCatiOD' ROCKVILLE, MARYLAND D3Id.
JULY 20, 1993 PE0SS:
68 PAGES NEALR.GROSSANDC0.,INC.
COURT REPORTERS AND TRANSCRIBERS 1323 Rhode Island Avenue, Northwest Washington, D.C.
20005 i
(202) 234-4433
DISCLAIMER
~
This is an unofficial transcript of a meeting of the United States Nuclear Regulatory Commission held on July 20, 1993, in the Commission's office at One White Flint North, Rockville, Maryland.
The meeting was open to public attendance and observation.
This transcript has not been reviewed, corrected or edited, and it ' may contain inaccuracies.
The transcript is intended solely for general informational purposes.
As provided by 10 CFR 9.103, it is not part of the formal or informal record of decision of the matters discussed.
Expressions of opinion in this transcript do not necessarily reflect final determination or beliefs.
No pleading or other paper may be filed with the Commission in any proceeding 'as the result of, or addressed to, any statement or argument contained herein, j
except as the Commission may authorize.
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1 UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION BRIEFING ON OPTIONS FOR ADDRESSING SHUTDOWN AND LOW POWER RISK ISSUES PUBLIC MEETING Nuclear Regulatory Commission one White Flint North Rockville, Maryland Tuesday, July 20, 1993 t
The Commission met in open
- session, pursuant to notice, at 10:00 a.m.,
Ivan
- Selin, Chairman, presiding.
COMMISSIONERS PRESENT:
IVAN SELIN, Chairman of the Commission KENNETH C. ROGERS, Commissioner FORREST J.
REMICK, Commissioner E.
GAIL de PLANQUE, Commissioner 4
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2 STAFF SEATED AT THE COMMISSION TABLE:
SAMUEL J.
CHILK, Secretary JOE SCINTO, Deputy General Counsel for Hearings, Enforcement and Administration JAMES TAYLOR, Executive Director for Operations WILLIAM RUSSELL, Associate Director for Inspection'and Technical Assessment, NRR ASHOK
- THADANI, Director, Division of Systems Technology, NRR ROBERT JONES, Chief, Reactor Systems :iranch, NRR MARK CARUSO, Reactor Systems Branch, NRR l
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P-R-O-C-E-E-D-I-N-G-S 2
10:00 a.m.
3 CHAIRMAN SELIN:
Good morning, ladies and 4
gentlemen.
5 The Commission is meeting at this time to 6
receive a briefing from the staff on the status of.the 7
shutdown risk program. This is an agency-wide program 8
that was begun as a result of international studies on i
9 shutdown risk, as well as the specific concerns that 10 were raised by the incident investigation team that 11 reviewed the 1990 loss of all vital AC power at the 12 Vogtle Nuclear Plant.
We were last briefed on the 13 status of the program September of last year.
14 Today's meeting serves as a means for the 15 staff to update the Commission and the general public 16 on the status of the program by presenting technical 17
- findings, propose generic requirements and-18 recommendations.
19 Of course, copies of the viewgraphs, as 20 usual, are available at the entrance of the room.
i 21 Do we have any comments?
22 Mr. Taylor, would you proceed?
i 23 MR. TAYLOR: Good morning. With me at the 24 table are Bill Russell, Ashok Thadani, Bob Jones and 25 Mark Caruso, all from the Office of NRR.
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'4 1
As you mentioned, Mr. Chairman, really 2
emanating from the Vogtle event several years ago, 3
through various work that the staff has been doing, 4
we've attempted to concentrate on the subject of risk 5
during shutdown.
Today we presented, first a few 6
weeks ago, a paper to the Commission and today we 7
believe, as you will hear in the presentation, that i
8 after a thorough study of the subject that the staff 9
believes that rulemaking is probably the most 10 appropriate way to establish generic requirements 11 which address shutdown risk issues.
12 We will discuss the reasons for 13 recommending that approach this morning and the office 14 of NRR will continue to have the lead in developing 15 the rule and supporting documents with support from 16 the Office of Research and the Office of the General 17 Counsel.
18 With those opening remarks, I'll turn to.
19 Bill Russell to continue.
20 MR.
RUSSELL:
Okay.
I would like to 21 highlight just a little bit from the background 22 because it relates also to the recommendation for 23 rulemaking that we are going to.
That is that the 24 staff has been addressing decay heat removal during 25 shutdown or issues broadly related to shutdown events NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVENUE, N W.
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1 since about 1980.
Between the time frame of 1980 and 1
2 the Diablo Canyon event in
'87, we actually issued l
3 five generic letters addressing these issues.
After 4
the Diablo Canyon event and the Vogtle time frame we 5
issued three additional generic letters addressing 6
these.
We do feel that the generic letter following 7
the Diablo Canyon event addressing mid-loop operation 8
was the most significant of those and it did identify 9
some new insights as to the risk associated with that 10 particular mode of operation of mid-loop.
11 You'd mentioned that we've had bilateral 12 discussions.
The two that-I'd like to highlight that 13 were early on were discussions with the Swedish 14 regulators and the French regulators, principally the -
15 conclusions that they had reached from doing safety 16 assessments using probabilistic techniques and 17 addressing shutdown events.
Those assessments 18 indicated that the core damage frequency associated 19 with shutdown events was approximately comparable to 20 that associated with events from power and that 21 shutdown events were a sig al ficant contributor to core 22 damage frequency when weighted on Average over the 23 year.
24 Those findings, along with the Vogtle 25 event, led to the decision to do a reassessment of the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVENUE. N W.
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l i
{
1 approach we had taken to shut down events.
We 2
concluded early on that this was not an issue that 3
raised questions regarding adequate protection, but 4
rather this would be clearly in the mode of 5
enhancements to our regulations and we viewed this as 6
necessary to take a comprehensive review of both the 7
foreign information, our own event information.
8 To that end we had a task activity that 9
was made up of participants from each of the offices, 10 Nuclear Reactor Regulation, AEOD, Research and the
./
11
- regions, and we addressed operating experience 12 broadly.
We visited plants and we looked at accident.
13 sequence precursor evente as they related to shutdown.
14 We looked at PRA techniques and did a level 1 PRA.
15 It's a screening and did not.have all the uncertainty 16 or sensitivity analyses.
We did special studies on 17 loss of decay heat removal.
The particular event of 18 concern which was identified by the French, which was 19 a boron-dilution event during start-up, was looked at.
20 And then we reviewed carefully our ct.rrent regulatory 21 requirements.
22 In addition, this issuit was receiving a 23 lot of international attention as well.
Through the j
24 OECD Nuclear Energy Agency, the Committee Nuclear 25 Regulatory Activities conducted a special review with NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVENUE, N W.
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1 a meeting that was held in June of
'92.-
That meeting 2
included participants from utilities worldwide and it 3
was at that meeting NUMARC was represented by Mike 4
Wallace from Commonwealth Edison Company.
5 That report was completed in November of 6
'92 and I
believe copies were provided to the 7
Commission. It is a restricted information because it 8
was provided in confidence
- and, in
- fact, the.
9 comparative type of analysis is held closely by-the 10 countries that have participated.
I would like to 11 characterize though that essentially each country 12 views the issues from the same perspective, from a 13 safety standpoint.
Others have gone further in their 14 regulatory requirement., as it relates to permissible 15 activities during shutdown and in particular controls.
16 on mid-loop operation.
But it does indicate what is 17 the current status, at least amongst the Western 18 Countries.
19 CHAIRMAN SELIN:
Why did they hold this l
20 information tightly?
21 MR. RUSSELL: There have been cases in 'the l
22 past where there have been comparisons one country to J
23 the next and that raises questions.
Taken out of I
24 context and without knowing the regulatory process 9
25 that exists within a country, it is not deemed NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVENUE. N W.
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appropriate.
So, one of the ground rules associated 2
with the information exchange was that this 3
information would be held in confidence.
It is.not 4
releaseable outside of the government's --
5 CHAIRMAN SELIN:
So it's not based on 6
proprietary --
7 MR. RUSSELL:
No, it is not.
8 CHAIRMAN SELIN:
-- insensitivity.
9 MR. RUSSELL:
It's sensitivity to program 10 comparisons country to country.
I would point out 11 that the comparison for the U.S., we would be near the 12 bottom of the list with respect to regulatory 13 requirements as it relates to shutdown risk.
The 14 actions that we are proposing are comparable to 15 actions that have already been taken in many of these 16 countries.
17 The program we initiated was a three 18 phrased program.
19 (Slide)
Could I have the first slide, in 20 fact?
21 The three phased program was essentially 22 a program of technical studies.
We have promulgated 23 the results of that work.
It's in NUREG-1449.
It was 24 issued in February of
'92.
We've had a number of 25 technical meetings on it.
It's been reviewed by the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVENUE, N W.
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ACRS and we've received two ACRS letters.
In 2
addition, we've had numerous workshops and discussions 3
both with inspectors and with industry.
We have also 4
issued a temporary instruction, which is guidance to 5
the field for the purposes of conducting inspection 6
activities, focusing on issues related to shutdown 7
risk and it provided guidance to the field in that 8
area.
9 We've interfaced heavily with industry.
10 NUMARC has prepared guidelines which we feel are from 11 a broad policy level and approach level.
They are 12 quite sound. We encourage the implementation of those 13 guidelines.
14 (Slide)
If I could have the next slide, 15 please.
16 The staff last briefed the Commission in 17 September of
'92 and we basically covered.those 18 technical studies and the requirements that we:had 19 under consideration.
In just a moment I'll have Bob 20 Jones summarize both the technical findings and the i
21 recommendations.
That is the specific technical 22 recommendations that we're proposing.
But I would 23 note that the Commission requested us also to address 24 our preliminary regulatory analysis, which has been 25 provided in the SECY
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1 10 1
specifically the pros and cons of rulemaking as 2
compared to a generic letter. That has' been completed 3
and I will be addressing the staff's rationale for 4
recommending rulemaking and I'd like Bob Jones now to 5
summarize the results of the study and our technical j
6 findings.
t 7
COMMISSIONER ROGERS: Just before you move 8
on, Bill, you mentioned that the requirements that you 9
are recommending would bring us more closely to the 10 practices in other countries.
How long have they had 11 those requirements in place and could you comment as 12 to --
13 MR. RUSSELL:
Yes.
The process --
14 COMMISSIONER ROGERS:
-- how it is that 15 we're behind them because we try to stay in touch with 16 general practice worldwide?
Was there a flurry of 17 activity that led to those over a short period of time 18 and we're just catching up to that or what?
19 MR. RUSSELL: Well, it varies from country 20 to country.
I would say that in general the approach 21 in
- France, for
- example, was more advanced and 22 developed with interaction between the regulator and 23 EDF, addressing issues of shutdown risk and they had 24 been essentially addressing these issues from about 25 the 1985 time frame on, with specific technical NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLANC INENUE, N W.
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requirements early on.
It was enhanced as a result of 2
their PRAs which were comprehensive and addressed 3
shutdown risk.
This is in the 1989/1990 time frame, 4
and there were additional requirements that were t
5 imposed as a result of those findings.
6 In other cases, the countries, Sweden in 7
particular, had done work and was leading.
In fact, 8
that's why we started on our work in 1990.
Between:
9 1990 and 1992, I would characterize there was a lot of 10 activity.
In some countries the mechanisms by which 11 they implement requirements are based upon discussion 12 and mutual agreement as compared to the processes that 13 we use in this country.
I don't think that there has 14 been a significant difference in time frame with 15 respect to recognizing the issues or taking interim 16 actions.
We just have not completed our formal 17 processes. I would characterize that processes in the 18 United States are somewhat unique both from the 19 standpoint of required regulatory analysis and 20 backfitting and the process we go through.
21 So, the technical studies were nearing i
22 completion about the same time.
The report does 23 indicate that some countries are continuing to study.
24 There is an update to that report.
25 MR. TAYLOR:
Bill will be mentioning the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVENUE, N W.
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1 NUMARC guidelines and other actions that will come out 2
of this whole area as a result of the staff.'s generic 3
letters and discussions with industry.
So, the 4
industry has not itself stood still.
5 DOCTOR THADANI:
If I may just add to what r
6 Bill was saying, the process, even internationally, is 7
an evolving one.
Over the years you do see changes in 8
various countries in terms of the way they deal with 9
shutdown risk.
Some countries, France for example, 10 has actually made a number of changes in the more 11 recent years as a result of their studies.
There are 12 countries out there wherein they have paid attention 13 to shutdown conditions for many, many years in terms 14 of requirements for redundancy and diversity of 15 available equipment.
So, what you see generally is 16 better understanding over time, an increased set of 17 requirements in most European countries certainly.
18 MR. RUSSELL:
Okay, Bob.
19 MR. JONES: As part of our evaluation, the 20 staff went and tried to estimate the core damage 21 frequencies during shutdown and low power operations.
22 To a large extent, the analyses that we performed 23 confirmed the findings we found from the international 24 studies, that is that shutdown risks are comparable to 25 those of power operation.
We further confirmed that NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE tSLAND AVENUE, N W.
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the BWR core damage frequencies are approximately a 2
factor of ten lower than PWRs primarily as a result of 3
unique vulnerabilities present in the PWR as 4
associated with mid-loop operation.
5 One of the findings that we came to early 6
on in NUREG-1449 and we worked with the industry on is 7
that effective outage planning and control is 8
extremely important in controlling shutdown risk. The 9
outage plans determine what conditions the reactor 10 coolant system can get into and 3 t also dictates the 11 available equipment to mitigato any events that might 12 occur.
Along these lines, one of the items that we 13 confirmed was that when the reactor cavity is' flooded, 14 the risks are essentially minimal.
15 As a result of the outage planning and 16 control activities, we worked very hard with NUMARC 17 and NUMARC-initiated and issued guidelines, NUMARC 18 06 which helps guide utilities in performing outage 19 planning.
we also found that for both 20 Another 21 reactor types, the PWRs and the BWRs, similar to the 22 Vogtle
- event, losses of off-site power can~ be-23 significant contributors to core damage frequency in 24 shutdown modes.
With the current requirements in 25 general that is out there in the industry for one NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVENUE, N W.
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diesel or one on-site power source, we estimate that 2
a loss of off-site power leads to about 40 percent of 3
the core damage frequencies that we're seeing.
As a 4
result, we have concluded that redundant on-site power 5
capabilities appear necessary when in reduced 6
inventory.
7 CHAIRMAN SELIN:
Does that mean safety 8
level or do you want to talk about that later?
9 MR. RUSSELL:
We'll talk about that in a 10 moment, but we are looking at alternatives as long as 11 it's capable of performing the functions.
So, it 12 would not necessarily require two safety grade on-site 13 AC sources, but it would, for example, allow the use 14 of a station blackout alternate AC source if they're 15 adding a gas turbine or bringing in a portable diesel 16 particularly for the outage to support diesel work in 17 parallel.
I'll talk about how we 're proposing to 18 implement that.
r 19 CHAIRMAN SELIN:
Was there any more to F
20 that fire observation than what you have here?
21 MR. JONES:
Well, I was going to get to 22 that later, but I can do it now.
Basically what we've 23 found in the area of fire is we walked down at one 9
24 plant and did a look see as to how the decay heat 25 removal systems are routed through the plant and what l
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kind of vulnerabilities might exist if there was a 2
fire.
What we found is you can actually reduce or 3
eliminate the redundant ones, redundant capability for 4
decay heat removal in some plant areas and 5
additionally, since many of the plants only require 6
one RHR in certain modes, you can eliminate all of the 7
residual heat removal capability at that time.
8 Additionally, we looked at some of the 9
history over about a year period.
We had about eight 10 fires that we noted.
Seven of these occurred during 11 shutdown.
12 CHAIRMAN SELIN:
That was really my 13 interest, was the second point, did you look at the 14 probability of fire, because you've got a lot of junk l
15 floating around and a lot of people who maybe are less 16 sensitive than your normal --
17 MR. JONES:
We didn't really look in a 18 quantifiable way, but we did look at just generally 19 the transient combustibles and types of 20 vulnerabilities and the fact that there are no 21 regulatory requirements in this mode for fire and we 22 determined that that was a significant vulnerability 23 in that mode that needed to be addressed.
24 MR. TAYLOR:
Particularly on one RHR.
25 MR. JONES:
Particularly on one RHR.
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DOCTOR THADANI:
Right.
Let me expand on 2
that a little bit.
The frequency of fires during 3
shutdown, as Bob noted, is higher.
The severity of 4
fires is not very significant. On the other hand, the 5
current regulations really don't require that once you 6
go below hot shutdown condition towards cold shutdown 7
or refueling, they don't require availability of the 8
two trains of decay heat removal in terms of jf you 9
have a fire in a certain. location.
It could be that 10 during that mode you have a train unavailable for 11 maintenance purposes or something, and the single fire 12 will knock out total decay heat removal capability.
13 So, while we didn't quantify risk, I would 14 expect it could be significant, just when you 15 considered those facts.
16 MR. TAYLOR:
It could be a motor.
17 DOCTOR THADANI:
Yes, indeed.
18 CHAIRMAN SELIN: You know, when I read the 19 fire protect -- you want to talk about fire protection 20 later on?
21 MR. RUSSELL:
I'm going to come back to 22 that when we talk about the approach to l
23 implementation.
24 CHAIRMAN SELIN:
Fine.
Okay.
We'll do r
25 that later.
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MR. JONES: Okay. Finally, the other item 2
noted from our review was that many of the operations 3
that go on during shutdown are performed without the 4
containment closed. That is with the containment open 5
to allow for equipment to be moved then out.
If you 6
do not close containment and have a core damage event, 7
we calculate that the off-site and on-site releases 8
would be quite large and, in fact, comparable to those 9
that would occur from a core meltdown event at power 10 with a containment failure.
11 COMMISSIONER REMICK:
Bob, two questions 12 on that viewgraph, which by the way is not on the 13 screen.
14 MR. JONES:
Oh, excuse me.
15 COMMISSIONER REMICK:
But the first one 16 you give a range of core damage frequencies and I 17 think, Bill, you mentioned they were weighted.
Could 18 you elaborate a little bit more?
I'm not quite sure 19 I appreciate the way you're weighting it.
20 MR.
RUSSELL:
We're talking about two 21 different things.
My comment toward weighting was 22 based upon the analyses that were done overseas where 23 they looked at a typical profile of the number of days 24 in shutdown, the number of days in start-up and the 25 number of days at power and then they weighted it to NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVENUE, N W.
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come up with an overall core damage frequency and then 2
they looked at what the contribution was associated 3
with shutdown periods,. transient start-up shutdown 4
periods and steady state operations.
5 COMMISSIONER REMICK:
And my question --
6 MR. RUSSELL:
So, in that context, that's 7
what I was discussing by weighted.
8 COMMISSIONER REMICK:
Yes.
9 MR. RUSSELL:
We did in our regulatory 10 analysis weight the shutdown periods based upon time 11 in various modes and that's contained in the 12 regulatory --
13 COMMISSIONER REMICK:
And how did you 14 weight it?
Does it mean that the risk was greater 15 during the actual shutdown and if spread out over the 16 year it was less or -- I'm not quite sure I understand 17 the weighting in this case.
18 MR. RUSSELL:
That is correct..There are 19 short periods of time when the risk, if you averaged 20 it over -- if you averaged over a year, the risk would 4
21 be on the order of 10 per year, but the 1 ' A at that 22 time is higher even though it's a shorter period of 23 time.
So, yes, typically if the core damage frequency 24 associated with shutdown is on the same order as at 25 power and you are shutdown for a month to two months NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVENUE, N.W.
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and you're at power for ten or eleven months, the risk 2
associated with shutdown from a time standpoint is 3
higher than the risk during power operation..That's 4
principally because of the controls we have put on 5
availability of equipment, containment for example, 6
decay heat removal equipments that do not exist when 7
you're in the shutdown modes.
8 COMMISSIONER REMICK:
Right.
Now, these 9
numbers on the viewgraph, are those weighted so I can 10 compare them with core damage frequencies in general 11 during operation or is this during the period of 12 shutdown?
13 MR.
RUSSELL:
This is the period of 14 shutdown, but it is per reactor year, not per day.
15 DOCTOR THADANI: This is appropriate. You 16 can compare them, although I will add one thing, that 17 the uncertainties in estimates here are clearly much 18 larger because they're controlled by human actions, 19 essentially all these estimates.
So, I would expect 20 much larger bands about this.
21 COMMISSIONER REMICK:
The question I was 22 going to ask later, but I'll ask it now, and that is 23 the PRA, shutdown risk PRAs are not complete. Are you 24 going to look at your regulatory analysis once you 25 have the PRAs complete? Will you revisit that because NEAL R. GPOSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVENUE, N W.
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you're making certain assumptions now about the risk?
2 MR. RUSSELL:
I would characterize that I 3
believe we've carefully documented the bases for the 4
assumptions and we've performed some sensitivity 5
studies.
We have not carried through on certainty 6
type analyses and it's essentially looking at the 7
reliability of decay heat removal.
So, there are 8
insights that we've gained from the screening PRAs, et 9
cetera.
But to do it in a more quantifiable manner 10 may be difficult and it may not be achievable in the 11 near term.
We have gotten to the point where we've 12 done a fairly significant amount of work.
We've 13 looked at sensitivity studies.
We've attempted to i
14 quantify it.
They are point estimates with 15 sensitivity studies, but it's fairly well documented 16 as to what the assumptions were and we think that 17 they're reasonable assumptions based upon the site 18 visits and the other work that we've done.
19 COMMISSIONER REMICK:
And that's okay if 20 the PRA indicates in the range.
But suppose they 21 aren't.
Would you revisit the regulatory analysis?
22 MR. RUSSELL:
Clearly if it turns out to 23 be substantially different than what we have reviewed 24 here.
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1 go back, there are two -- as you know, there are two 2
PRAs being done for Grand Gulf and Surry.
What you 3
will end up when those studies are completed, I think, E
~
4 is truly an exceptional understanding of those two 5
plants and risk during shutdown for those two plants.
6 We utilize the -- as Bill was saying, from earlier 7
scoping analysis what kinds of scenarios may be 8
important. But if you look at the regulatory analysis 9
here, every attempt was made to make as realistic an j
10 assessment as we could.
I would be very surprised 11 that you would come up with different conclusions.
12 But what you would have once those studies are done 13 would be a much better understanding of those two 14 plants clearly.
15 MR. JONES:
If I could add to that, we do 16 have some point estimate numbers for the Surry 17 analysis. They indicate for.the 3x10-5 roughly for the 18 core damage frequency due to internal events and a 2E-5 19 for the fire.
They have done a fire analysis point 20 estimate.
These are recently made available to us.
21 We are still following that study.
We will 22 incorporate the findings if new information becomes 23 available.
That work is ongoing and should be pretty 24 much through with the internal events, a level 1 PRA, j
25 by the end of this year on both plants.
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i 22 1-COMMISSIONER REMICK:
Okay.
Another-2 question -- yes, Bill.
3 MR. RUSSELL:
I think the important thing 4
to recognize though is that really these issues have 5
been driven, as Ashok mentioned, by human error. That 6
is, in fact it's even more so recently.
In April, 7
AEOD forwarded their review of events and their 8
conclusion was that better than 80 percent involved 9
human error and were avoidable.
The earlier studies 10 had indicated it was on.the order of 60 percent of the 11 events.
When you think about an outage and how it's 22 conducted, you may do initially good planning for the 13 outage, but if the outage gets behind, if something's 14 not done properly, you can lose control of equipment 15 configuration or get into modes where you don't have 16 the defense in depth of the redundancy or the 17 contingency plans.
Those are generally the kinds of 18 issues that we've seen.
19 These are generally avoidable with better 20 planning and we feel that there needs to be a floor 21 described regarding minimum equipment availability and 22 we'll get to the rationale for that.
But we don't see 23 that this is one that significant additional study is 24 going to change the view regarding the importance of 25 this issue and the fact that there is some need for NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVENUE. N W.
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23 1
regulatory control.
We do see it as an enhancement.'
2 These are relatively low probability events, but they 3
are also avoidable events and the way you can control 4
that is by controlling equipment availability 5
administratively, either through tech specs or through 6
other mechanisms.
7 COMMISSIOtJER REMICK:
Another question I 8
had is on containmer..
How important is it to button 9
up the containment from the standpoint of withstanding 10 pressure versus just buttoning up so you don't have 11 diffusion of any possible fission product?
How 12 important is it with an accident at shutdown that it 13 be a pressure closure?
14 MR. JONES:
We believe you need to button 15 it up for pressure retention.
You could clearly get 16 into hydrogen issues with the containment closed or 17 just buttoned up and not pressure retaining, which 18 could lead to a large pulse should you have a fire.
19 Also, low pressurize the containment. There have' been 1
20 some studies done as part of the research PRA which 21 looks at the pressurization rates in containment.
I 22 don't remember the exact numbers now.
I think it's 23 like one and a half PSI or two PSI a minute type 24 pressurizations, but as I said I don't want to be 25 quoted on that.
But it is significant.
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24 1
quite large given one of these events.
2 COMMISSIONER REMICK:
Now, I assume that 3
both of us were talking there about PWRs.
4 MR. JONES:
Yes.
5 COMMISSIONER REMICK:
How about BWRs?-
6 MR. RUSSELL:
We'11 get to that in just a 7
moment.
But the BWRs essentially do not have a 8
containment and if you do not: maintain subcool and 9
decay heat removal, if boiling occurs because of the 10 specific volume of steam when you're at atmospheric r
11 pressure the quantities of steam ar e basically going 12 to make it difficult to recover.
You would'probably 13 fail the secondary containment fairly quickly, on the 14 order of half an hour or so failure or less.
15 COMMISSIONER REMICK:
Fail from what?
16 MR. RUSSELL: Steam pressure generation up 4
17 in the spent fuel pool area, the top of the --
18 COMMISSIONER REMICK:
Even'if you had the 19 standby --
20 MR. RUSSELL:
Yes.
21 COMMISSIONER REMICK:
-- control?
22 MR. RUSSELL:
Standby gas treatment.
23 COMMISSIONER REMICK:
Standby gas 24 treatment, yes.
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Standby gas treatment or NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVENUE, N W.
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refueling area cooling.
It's not sufficient to 2
accommodate the kinds of heat loads that you would get 3
from decay heat.
So, the -- and the heat sinks are 4
not there and it's a relatively small containment, so 5
that there's not the volume to dissipate it.
The 6
analyses showed that secondary containment failure 7
would occur and I recall numbers on the order of 30 8
minutes.
It may have been less.
9 MR. JONES:
That's about the right time.
10 COMMISSIONER REMICK:
But in a BWR you 11 have a lot of water usually normally there when 12 you're --
13 MR.
RUSSELL:
That's correct.
The 14 advantage you have with a BWR is that you do have time 15 and it looks like they have more mechanisms for 16 maintaining subcool decay heat removal.
17 DOCTOR THADANI:
Much lower core damage 18 frequency estimate.
19 MR.
RUSSELL:
By about an order of 20 magnitude.
21 DOCTOR THADANI:
An order of magnitude 22 lower.
23 COMMISSIONER REMICK:
Well, thank you.
24 MR. JONES:
Could I have the next slide?
25 CHAIRMAN SELIN:
This is very important NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVENUE. N W.
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and I want to make sure I understand.
You're saying, 2
roughly speaking, that on the order of half of the 3
risk that comes in a power plant cycle comes during 4
shutdown, maybe a third, even though the shutdown is 5
obviously a much smaller share of the time.
6 MR. RUSSELL:
That's correct.
7 CHAIRMAN SELIN:
And you're saying that 8
roughly 40 percent of the risk that occurs in shutdown 9
is related to fire, at least in these two -- I mean i
10 this is not a generic thing, but you've done the two 11 samples.
Not necessarily caused by
- fire, but 12 exacerbated by fire or --
13 DOCTOR THADANI:
I think it was about 20 14 percent, I believe, for fire.
15 MR. RUSSELL:
Bob quoted the preliminary 16 results from Surry and it would be about 40 percent 17 based upon Surry.
We have not quantified it for 18 other -- in the regulatory analysis we incorporated 19 the approach to fire protection with the broad 20 regulatory analysis as it related to controls.
21 CHAIRMAN SELIN:
So, even if there were no 22 risk of fire in normal operations, the fire risk l
23 during shutdown is still a major contributor --
i l
24 DOCTOR THADANI:
Yes.
(_
25 MR. RUSSELL:
That is correct.
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37 T
1 CHAIRMAN SELIN:
-- to risk.
.I 2
DOCTOR THADANI:
That's correct.
3 CHAIRMAN SELIN:
Okay.
So, a part --
~
4 DOCTOR THADANI:
Our regulations on fire 5
don't cover that mode.
6 CHAIRMAN SELIN:
Right.
So, we've got 7
some work to do even after we're done --
8 DOCTOR THADANI:
Oh, yes.
9 CHAIRMAN SELIN:
-- with the work that's 10 done in here.
11 DOCTOR THADANI:
Yes.
12 CHAIRMAN SELIN:
And we're not talking 13 about fire barriers, we're talking about the broad 14 question of fire prevention.
15 DOCTOR THADANI:
That's right, exactly.
16 MR. RUSSELL:
I'm going to cover that in 17 just a moment as to what the issues are and the 18 approach we're recommending.
19 CHAIRMAN SELIN:
Fine.
Thank you.
20 MR. JONES:
(Slide)
Next slide, please.
21 As a result of the technical findings, we 22 have done a regulatory analysis which we provided a 23 draft version of, which we will be upgrading to 24 reflect our option or conclusion to go to rulemaking.
25 I'd just like to go through what we came out as our NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVENUE. N W.
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proposed requirements.
2 First off, as noted, outage planning and 3
control is just absolutely critical in defining and 4
mitigating shutdown risk.
We believe that licensees 5
should have a program for this that is a controlled
[
6 program which would be similar to those requirements 7
in NUMARC-91-06 which would include such things as
.i 8
having safety principles for outages, define roles and 9
responsibilities for plant personnel during the 10
- outages, contingency planning for responding to 11 events, along with appropriate procedures and operator 12 training.
13 We believe, however, that the NUMARC-91-06 14 guidance needs to be enhanced in the area-of fire 15 protection, as Bill mentioned he will talk more about i
16 our proposed requirements for fire.
But basically 17 what it is is allows plants to perform realistic 18 assessments of fire hazards during shutdown operations 19 and to provide appropriate controls to limit fire 20 loadings durir.g the planning of the outage.
1 21 In addition --
i 22 COMMISSIONER de PLANQUE:
A quick 23 question.
Are you looking at an assessment that's-24 done on a one time basis or for each outage?
25 MR. JONES:
We're leaving that option up 5
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29 1
to the licensees.
2 Finally, we have had experiences in the
.l 3
recent years on use of instrumentation, available 4
instrumentation in the plant where you can control or 5
we desire to maintain temperature indications in PWRs j
6 while in. lower loop inventory and yet they have to be 7
disconnected when you go and put on and take off the 8
reactor vessel head. We would like to have procedures 9
on the use of that instrumentation to minimize the 10 time period that you would have such instrumentation 11 not available.
12 COMMISSIONER REMICK:
To what extent --
13 what's the staff's assessment of to what extent these 14 things are being done now as a result of the interest i
15 over i - last couple of years in shutdown?
16 MR.
JONES:
We are seeing the NTMARC 17 guidance is being implemented out in the field.
We 18 have done five shutdown team inspections.
Clearly 19 people are starting to plan their outages better.
J 20 However, we are also seeing problems with maintaining i
21 safety principles throughout an outage as part of i
22 those inspections such that the controls in place as j
i 23 emerging work comes into the outage is not necessarily l
24 very well done.
In addition, we are continuing to see 25 events out there and we are still seeing licensees NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVENUE. N.W.
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plan outages wherein they are not, for example, 2
maintaining re:lundant on-site power supplies'during 3
mid-loop operation, which is what was recommended in 4
the INPO guidances, for example.
We are seeing them-5 all the time.
In fact, we-may have one today that 6
we're going to be discussing with the licensee.
7 MR. RUSSELL: I would characterize it that-8 the NUMARC guidelines are at a top level.
Below that 9
are some INPO guidelines that are more specific.
We-10 have seen cases where utilities believe that they are 11 following the guidelines broadly and we have looked at 12 those and have concluded that they were not and have 13 asked to have management meetings to understand how 14 the conditions that they're proposing are acceptable 15 in fact meet those guidelines.
This is continuing.
16 It has been identified through our inspection 17 activities.
Some have been escalated to discussion' 18 with Headquarters.
19 The issue that seems to be the most 20 contentious is the redundant on-Jite AC power 21 availability, whether it be a portable diesel that's:
22 brought' in or using a gas turbine.
It's not redundant 23 safety-related AC power, but that appears to.be an 24 issue for some utilities.
It's not'even consistent 25 within a company. We've seen cases where one plant of NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVENUE, N.W.
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l 1
a company's organization takes a very aggressive 2
approach to it and controls it well and another 3
f acility within the same organization basically hadn't 4
gotten the word and was planning its outage and we 5
concluded that they weren't consistent with the 6
guidelines.
j 7
So, we do feel that it's necessary to 8
establish a
floor level.
Operators and others 9
understand technical specifications.
These are 10 clearly modes which have some significance to risk and 11 we feel should be controlled at that level.
12 CHAIRMAN SELIN:
I actually had a couple 13 questions for you now.
one is a very general one, 14 one's a specific one.
The specific one is when we do 15 an analysis of the potential contribution of a third 16 safety-related diesel to risk, is that just done in 17 the operational modes or does that include. shutdown 18 risk?
I've often asked why do we stop at two diesels 19 and the answer is the third doesn't contribute much 20 for risk.
But does that include giving a second 21 diesel when a third is under maintenance?
I 22 i
MR. RUSSELL:
I can address that from the l
23 standpoint of what we're doing now on the new designs 24 because that is an issue that's being looked at and we i
25 are specifically addressing shutdown risk.
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general, they have proposed three trains of decay heat 2
removal with on-site sources.
That gives them 3
significant flexibility from the standpoint of being
~
4 able to do maintenance.
Essentially they can meet the-5 goals with two available.
There is not a-built in 6
spare that could be used.
So, with a three train 7
system you have significant flexibility.
But 8
essentially you would need, we believe, two.
What-9 we're saying is we're not going to require those be 10 safety related, but we are looking-at functional 11 capability to have sufficient power.
12 CHAIRMAN SELIN:
That two sources be 13 available at all times even when maintenance is 14 going --
15 MR. RUSSELL:
That's correct.
The only 16 time we would allow less than two sources is when 17 you're flooded up to 23 feet above the vessel flange 18 when the canal is flooded and then'you don't have the 19 same timing requirements.
In that instance we.would t
20 allow them to go to a single decay heat removal --
21 CHAIRMAN SELIN:
What about any existing 22 diesels.
I mean existing - -
23 MR. RUSSELL:
Most plants have -- because 24 of the GDCs, they have redundant RHR capability with 25 on-site as well as with off-site.
That's from the NEAL R. GROSS 3
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1 general design criteria.
So they have generally two 2
methods of doing that.
Some overseas facilities have 3
made modifications such that spent fuel pool ccoling 4
could be used in addition to the two trains to give 5
them some capability. But in general, U.S. facilities 6
do not have that kind of capability.
So they're 7
generally two train.
8 DOCTOR THADANI:
If I may add to that 9
though. As a result of the station blackout rule some 10 facilities in this country did add an additional 11 either diesel generator or a combustion turbine safety 12 grade or, in many cases in fact, not safety related.
13 So, there are a number of plants that have, in fact, 14 three on-site sources of power for single unit sites.
15 And they do take credit during power operation in 16 terms of the third source of power. What we're saying 17 during shutdown condition is that for a limited time-18 period, a period where we're most concerned because if 19 something goes wrong the available time is limited.
[
l 20 For that period,.we want to be sure that there are at 21 least two sources of on-site power, safety or non-22 safety, and off-site power should be available.
This 23 is driven by trying to get an understanding of risk 24 significance of what we ought to do.
25 That's the focus, this approach.
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34 1
CHAIRMAN SELIN: There's a small number of 2
plants that have fewer than two diesels per unit, two 3
sources per unit.
Oconee has got that funny hydro --
4 DOCTOR THADANI:
That's correct.
5 CHAIRMAN SELIN: Have we done the shutdown 6
PRA for these?
7 MR. RUSSELL:
We've not looked at shared 8
systems. It's been essentially for single unit sites.
9 But shared systems generally have sufficient capacity 10 to handle with one diesel both units at power or one 11 at shutdawi and one at power.
So, it does relate.
In 12
- fact, a shared diesels becauce they have to-be 13 available to support operation of the unit at power-14 may be beneficial.
Generally we would encourage and-15 have through the station blackout rule
.the 16 additional -- adding additional sources to' those, 17 either where there's a swing diesel that is shared 18 between two units or where there are only two diesels 19 for two units that are larger diesels.
20 DOCTOR THADANI:
Except ' for Oconee, I
21 believe, if I remember - correctly,.all plants where 22 they have, for example, two unit sites with three 23 diesels, shared diesels, they're all adding additional 24 sources of power.
25 CHAIRMAN SELIN: They are? Okay. Now, on
.l NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVENUE, N.W.
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the general question, I understand why a licensee 2
might want to cut corners and not keep the redundant 3
energy source, but I don't understand why they don't 4
want to plan their outages in detail anyway.
My 5
general understanding was that very carefully planned 6
and controlled outages are cheaper and faster and not 7
just safer.
Am I missing something or are you just 8
trying to get people to do what in a better world they 9
would realize is in their best interest anyway?
10 MR. TAYLOR:
Well, our outage planning 11 covers specific aspects of protection during the 12 shutdown condition, whereas more broadly what you say 13 is true, good outage planning usually means the 14 utility --
t 15 CHAIRMAN SELIN:
Part of Mr.
Jones' 16 comments --
17 MR. RUSSELL:
This is, in fact, a win-win i
18 situation. By doing better outage planning we've seen 19 that the outages have been shorter, which is an 20 improvement from what has been the case in the past j
21 where they've not been as effectively planned, and it i
22 also improves the safety because they're able.to 23 manage equipment configuration and equipment 24 availability during the outage.
25 COMMISSIONER ROGERS:
That isn't so clear P
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to me though, that the outage planning has included 2
the safety aspects.
3 MR. RUSSELL:
It has not in the past.
4 COMMISSIONER ROGERS:
And that, in fact, 5
it is cheaper.
I mean because they're more limited 6
when they take into account the loss of certain 7
functions during the outage from a safety point of 8
view.
They may not be able to turn off two different 9
pieces of equipment to work on them at the same time 10 and that may, in fact, result in a more costly outage 11 than if they could do that.
So, it isn't clear that-12 it's cheaper necessarily, but it's certainly safer.
13 MR. RUSSELL: But we've also found in some 14 cases that, for example, offloading the core such that 15 you can conduct activities in parallel --
16 MR. TAYLOR:
May be the answer.
17 MR. RUSSELL:
-- may be part of the answer 18 and more utilities are proceeding to offloading the 19 core rather than staying in mid-loop for extended 20 periods of time. There are things that can be done to 21 plan around them.
We do feel it's appropriate to
]
22 ensure that there is minimum equipment available 23 during particular modes of operation-that have risk 24 significance.
25 So, there clearly are tradeoffs, but in NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVENUE, N W.
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general we've not seen that this program has resulted 2
in lengthening outages.
It requires better-3 preplanning for the outages and then when they.are
~
4 better planned they are generally executed.
In f act, S
the overrun of the outages are generally less.
That 6
is if you look at days planned versus days 7
accomplished and how much overrun you have, a well 8
planned outage has had generally less overrun.
9 CHAIRMAN SELIN:
I've heard rumors you 1G actually have a prepared briefing.
I apologize for 11 that.
12 MR.
JONES:
I think the technical 13 specifications in the area of operability of redundant 14 equipment we've covered pretty much already in our 15 comments.
The other item that we are adding would be 16 the PWR containment integrity requirement, which we 17 would put in only to early in the outage to have the 18 containment close when you have basically lost the 19 steam generators as a heat sink.
So you.-have a 20 fission barrier should you have a core damage event.
21 CHAIRMAN SELIN:
Would you be kind 22 enough -- I'm sorry, I should know this, but I don't.
23 What's the background for saying that you have a 24 containment during PWR but you don't during BWR during l
25 shutdown?
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MR. RUSSELL:
You have to open the top of 2
the dry well on the BWR, which is a breach of 3
containment, in order to do a refueling.
So, the BWR 4
is open. Basically you have the secondary containment 5
and --
6 CHAIRMAN SELIN:
And the BWR you can keep 7
closed except for tae convenience of just opening 8
hatches if you want to get --
9 MR. RUSSELL:
Basically, yes.
The large 10 dry has much more capability.
In fact, we have 11 requirements to have containment integrity set when i
12 you're handling fuel in a PWR.
There are ventilation 13 systems, et cetera, that are required for BWRs for the 14 same fuel handling accident, but there you don't have 15 the forcing function driving it to require the 16 pressure integrity.
But if you lose decay heat 17 removal and you have boiling in the BWR, that same 18 small volume above the refueling _ floor would be 19 quickly pressurized and would fail.
20 CHAIRMAN SELIN: I see. Okay. Thank you.
21 MR. JONES: Finally we have identified the 22 need for an additional level instrument for PWRs for 23 mid-loop operation.
Effectively what we are finding 24 in spite of our enhancements as a result of Generic 25 Letter 88-17 to add level instruments' to more NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVENUE, N W.
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accurately measure water level to control mid-loop 2
operations, we are continuing to have problems.
It's 3
primarily related to use of a DP cell and the delta Ps 4
around the system because of the way they're arranged.
5 We believe that a diverse level indication is needed, 6
primarily something like an ultrasonic device we 7
believe is a means of accomplishing this.
Some 8
licensees have implemented it already in response to 9
Or additionally, we have had 10 some licensees actually put in a system such that they 11 cannot drain the system down below the mid-loop 12 elevation that would be a -- we would consider that on 13 a case by case basis.
14 CHAIRMAN SELIN:
Do I perceive that what 15 you would really like to do is to tell people not to e
16 do mid-loop operations at all and just offload or are 17 there so many special factors from one reactor to 18 another that --
19 MR.
RUSSELL:
That's an option for a 20 planned outage for refueling when you're otherwise 21 going down where you can offload the core.
But if you 22 were to have a reactor coolant pump seal problem or if 23 you had an unplanned outage associated with steam 24 generator tube leakage, it's really not practical or 25 prudent to do that.
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'l 40 1
CHAIRMAN SELIN:
How about just refueling i
2 outages?
3 MR. RUSSELL:
For refueling outages it is 4
an approach.
We have not specified "Tb c shalt not go 5
into mid-loop," because there are activities that can 6
be done and can be done safely as long as you maintain 7
equipment availabilities, et cetera.
The ones-that 8
I'm more concerned about from a safety standpoint 9
personally is the unplanned outage where you've got a 10 contingency where you're going into mid-loop, you're 11 in a hurry to get there because it's not planned, you 12 want to get down quickly, you've got a high decay heat 13 load, it has not had the same degree of planning and l
14 those are the. conditions under which we'd like to 15 maintain the redundant decay heat removal capability, 16 containment closure set in advan o, et cetera.
17 So, it's that mode that I believe has risk 18 significance as compared to where they've got a longer 19 outage because you can manage the steps earlier in the 20
- outage, maintain the equipment
.available and 21 potentially just offload.
22 CHAIRMAN SELIN: But you're also not doing 23 diesel maintenance during unplanned
- outages, et 24 cetera.
I mean by definition they're unplanned 25 outages, so you're not doing --
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1 MR. RUSSELL:
Our guidance would indicate 2
that they should not.
Whether that's happened in the 3
past or not, we have had that issue come up.
~
4 CHAIRMAN SELIN:
I see.
Thank you.
5 MR. RUSSELL:
Let me shift now to the 6
bases for the staff's recommendations.
7 (Slide)
If I could have slide 5, please.
8 The first point I'd like to emphasize is 9
that we are continuing to see significant precursor 10
- events, loss of decay heat removal.
They are 11 continuing.
We feel that there is a lack of control 12 both by licensees and regulatory control on entering 13 circumstances which are likely to be a challenge and 14 those circumstances have often had minimum equipment 15 and containment integrity has not been established.
16 I mention that this has been reaffirmed in an April 17
'93 AEOD report.
.18 We've also talked about core damage 19 frequency.
We have not talked about consequence from 20 the standpoint of radiological release.
This t
21 similarly is comparable in magnitude to a severe 22 accident from power initiation. -This is true where i
23 the containment is not available.
It's even more of 24 a concern for the PWRs because.if you'do not have 25 containment you're likely to have a ground level NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVENUE. N.W.
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1 release and the near field consequences are, in fact, 2
somewhat more severe.
But these are fairly 3
significant. person REM exposures comparable to that 4
which you'd get from a severe accident from power.
5 The regulatory analysis that we've done, 6
I'd like to point out, would support either approach 7
to implementation.
That is we - chose to do the 8
regulatory analysis to support either rulemaking.or a 9
generic letter approach so that the regulatory 10 analysis itself is not determinative as to which 11 approach you would take.
12 We did conclude that the. activities 13 associated with outage planning and administrative 14 controls and fire protection were cost beneficial for 15 the PWR and even with the sensitivity analyses we're 16 still very cost beneficial, on the order of $52.00 per 17 person rem avoided.
For the PWR instrumentation, it 18 was $280.00 per person rem avoided.
For the BWR it 19 was above the threshold-of $1,000.00 per person rem 20 when you only considered core damage.
It was at 21
$1600.00, but again this is an issue for which you do 22 not have a containment and so we don't feel that 23 that's appropriate by itself.
You ought to look at --
24 CHAIRMAN SELIN:
Would you stop for a 25 second?
l NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVENUE, N W.
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MR. RUSSELL:
-- large release.
2 CHAIRMAN SELIN:
You don't have a
3 containment if you're refueling.
4 MR. RUSSELL:
That's correct.
5 CHAIRMAN SELIN:
But if you have 6
unscheduled outages you normally keep containment 7
integrity in a BWR?
8 MR.
RUSSELL:
It depends upon the-9 activities that you would go into.
It is'possible, 10 yes, that in an unplanned outage for a BWR if you had 11 primary leakage in excess of, say, three to five 12 gallons per minute and you needed to make a dry well 13 entry to find that.
You could go in and find a 14 problem and repair it.
15 The issues that were most.significant for 16 the BWR were essentially loss of inventory when you 17 were on decay heat removal.
By losing inventory you 18 lose the capability of maintaining subcool decay heat 19 removal.
That gets back to maintenance activities.
20 For example, maintenance on drain lines on the vessel l
21 associated with reactor water cleanup system have the
]
22 potential for draining inside the jet pump shroud area 1
23 and so you - can. actually drain the vessel in those
]
24 circumstances.
So, it's more loss of inventory, loss 25 of AC power are the dominant ones for the BWR and it's NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVENUE, N W.
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not as much an issue of containment integrity.
If 2
containment integrity were there in an outage, it-3 would clearly be a benefit for the BWR.
4 COMMISSIONER REMICK:
In
- fact, any 5
unplanned outage that was of short duration, a BWR you 6
would probably --
7 MR. RUSSELL:
It would be unlikely to do 8
that because you would not want to lift the shield 9
plugs, pull a containment head, et cetera.
So, an 10 unplanned outage --
11 COMMISSIONER REMICK:
By definition it's d
12 all an outage?
13 DOCTOR THADANI:
I think that's right.
14 MR. RUSSELL: I think we're really talking 15 about longer outages for BWRs.
16 CHAIRMAN SELIN:
So your remarks about 17 what makes you most nervous are really more'toward 18 PWRs?
19 MR. RUSSELL:
That's correct.
The risk 20 for Ps are higher because of the concerns for mid-loop 21 operation.
The advantage you have with the P is that 22 containment, if containment integrity is set you 23 essentially have a non-problem from the standpoint of 24 public risk.
You do have still a significant problem 25 as it relates to core damage.
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CHAIRMAN SELIN:
Okay.
2 MR. RUSSELL:
The staff is recommending 3
rulemaking.
We evaluated both implementation by 4
generic letter and by rulemaking.
The approach we 5
looked at for generic letter was essentially a
6 voluntary submission of information that is a
7 commitment to a program that would address outage 8
management, a
voluntary request for technical 9
specification amendments to implement model technical 10 specifications, to perform a fire hazard analysis and 11 look at contingency plans and how they would manage 12 decay heat removal in light of fires during shutdown 13 conditions, and for PWRs to address the reliability of 14 existing instrumentation and to propose an additional 15 diverse instrument for mid-loop operation.
16 This process, while it may be somewhat 17 quicker to get a generic letter out, would result in 18 significant case by case reviews. We feel it would be 19 more resource intensive and it would likely take 20 longer to implement for all plants. in that you're 21 always going to get to a few plants'at the end where 22 you have a lot of debate and it may even require the 23 staff going to 50.109 with a plant-specific backfit 24 analysis and implementing by order and, of. course, 25 there are rights when you get into ordering such NEAL R_ GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVENUE, N W.
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activities.
2 We also felt it was not as formal and, in 3
fact, we feel that the risk significance associated 4
with shutdown operations or its formal treatment 5
through a regulatory process in the long-term.
6 CHAIRMAN SELIN:
I actually happen to 7
think that this is almost a red herring, that this is 8
a standard case'for rulemaking.
It's not emergent, 9
it's not et cetera.
But I do have a question about 10 interim activities because this is a long --
11 MR. RUSSELL:
That's my next slide.
12 MR. SCINTO:
I just wanted to indicate 13 that the General Counsel's Office supports rulemaking 14 in this case.
We really think this is a rulemaking 15 case and we would make the notation that-orders in 16 this case, if for example you went through the generic 17 letter process and you did get recalcitrant licensees 18 and you went to an order process, it would mean -- the 19 way some of this stuff has been characterized, it 20 would be very difficult to get immediate effective 21 order.
It didn't sound like the stuff you're talking 22 about immediate effective order.
Indeed, sometimes 23 some of the language used sounds like we're talking 24 about enhancements and sometimes it sounds like 25 adequate protection.
But if we're really talking NEAL R GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVENUE, N W.
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about enhancements, it can be very difficult ~ to 2
sustain an order for a safety enhancement if. we 3
concede that it is not necessary for adequate 4~
protection.
That's a tough order to sustain.
5 MR. RUSSELL: I would also point out that, 6
as I mentioned earlier, we've had eight earlier 7
generic letters that we've issued related to this and 8
the problems have continued.
So, we think it's time 9
to now formalize it by rulemaking.
10 We think it's important though.to allow 11 for flexibility and implementation in the rulemaking.
12 What I'd like to do is discuss the approach that.we 13 would recommend.
We are envisioning essentially two 14 rules.
The first rule would be a rule which would 15 require outage planning,.
would establish broad 16 requirements for redundancy of decay heat removal 17 capability when in shutdown modes.
18 COMMISSIONER REMICK:
Excuse me, Bill.
19 You say you would require outage planning.
Do you 20 mean that or that in outage planning you would 21 consider the safety of the risks and so forth?
22 MR. RUSSELL:
Yes.
.I used the shorthand.
23 When I talk ~about outage planning I'm talking about 24 outage planning as it relates 'to safety as we've 25 described.
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48 1
COMMISSIONER REMICK:
I don't want the 2
perception to be lef t that people aren't doing outage 3
planning.
4 MR. RUSSELL:
No.
The issue is a safety 5
perspective on that outage planning to control 6
equipment configuration and availability during 7
various modes which have been shown to be significant 8
to risk.
9 We would envision a broad rule with a 10 regulatory guide which we feel that the regulatory 11 guide may, in fact, be based upon, if not endorse, 12 many of the items that are within the NUMARC I
13 guidelines at this point in time.
We think we would 14 also have to have a generic letter that would forward 15 model technical specifications for the equipment 16 availability during shutdown.
To that end we have 17 developed model technical specifications as a part of 18 the technical specification improvement program.
We 19 have corresponded with the' owners' groups and we are 20 going to start the dialogue on those technical 21 specifications at the end of this month.
22 COMMISSIONER REMICK:
- Bill, that's 23 something I didn't understand.
Why a generic letter 24 to give model tech spec changes versus a reg guide 1
25 giving model tech spec?
I'm not quite sure I NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS I
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understand the significance there.
2 MR. RUSSELL: Okay. At the point we're at 3
right now we have been using basically model tech 4
specs which have been issued as NUREG documents and 5
have been under the staff's control. Now that we have 6
shifted with the tech spec improvement program we have 7
done basically the same thing.
We have a set of model 8
specs which are in the process of implementation that 9
we have interacted back and forth with the industry on 10 those model specifications. I would characterize that 11 probably the bulk of the language within those 12 specifications is language, in fact, proposed by 13 industry which the staff has found acceptable.
14 In the advanced reactor approach we will 15 have the equivalent model specifications as a part.of 16 the design certification in what we've called tier 2.
17 So, in each case there has been a set of model 18 specifications that you would then tailor to a
19 particular design, put in your set points, et cetera, 20 or address availabilities of equipment.
21 COMMISSIONER REMICK:
But my question is 22 why do that through a' generic letter versus a reg guide or a NUREG? I don't understand why the emphasis 23 24 on generic-letter to provide people with model. tech 25 specs.
If there's significance in.the generic letter NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVENUE, N W.
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in this case, I don't understand it.
I'm not again 2
it, I'm trying to understand.
3 MR. RUSSELL:
I would say that the basis 4
is just past practice.
I'm not sure that the -- at 5
least I'm not aware that the question has come up 6
before.
Generally regulatory guides have not 7
addressed tech specs.
Tech specs flow from 50.36 and 8
the requirement in an application for an applicant to 9
submit proposed tech specs which we have then reviewed 10 and evaluated and we've had standard tech specs for 11 years that provide a model that an applicant can use 12 in proposing technical specifications.
13 COMMISSIONER REMICK:
But you're not i
14 helping me because you said we did it by NUREG in the 15 past and I thought reg guides were a way of conveying 16 to people one way of doing it.
I interpret that's
.j 17 what you're saying for the generic letter, but maybe 18 there's more into it than I understand.
If-there's no 19 answer, let's just drop it at the moment.
20 MR.
SCINTO:
I f ' we have a regulation 21 basis, which we're planning to have, to require people j
22 to carry out this function, then a use of a regulatory-23 guide to give them guidance as to how to fulfill that 24 regulation or to refer to a NUREG as another document 25 giving guidance as to how to carry it out or a generic NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVENUE, N W.
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- letter, those are all reasonable alternatives.
2 They're all guidance as to how to carry out a l
3 regulatory requirement which is framed in a rule.
4 COMMISSIONER REMICK:
Right or wrong, I 5
give some special significance to a generic letter i
6 over a reg guide.
It's just consistency in my mind, 7
I guess.
l 8
MR. RUSSELL:
In any event, we do feel a 9
need to provide model specifications.
We were going 10 to follow the practice that we had followed with the 11 owners group.
In this case we have identified the 12 minimum equipment availability based upon safety-13 related equipment because we do not know the specifics 14 of what alternative equipment they may have at their 15 facilities that is not safety related.
So, we are 16 specifically encouraging the owners groups to identify I
i 17 alternative approaches to the' safety-related 18 equipment.
19 We've had discussion of what we'll call 20 contingent tech specs with some licensees.
21 Philadelphia Electric is'an example where they are
'22 putting in a tie to Conowingo Dam and going to use the 23 Conowingo. facility as the alternate AC source for a 24 station blackout.
This would provide them relief on 25 their limiting conditions for operation for their NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVENUE N W.
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diesels.
That same contingency being available could 2
be factored into the shutdown specs so that it could 3
be written that either Conowingo is available or on-4 site safety-related source is available.
But that's 5
the approach we're taking and we're looking at a 6
demonstration that it's capable of performing the 7
- function, but not necessarily requiring routine 8
surveillance on these non-safety equipments.
That is 9
showing it's capable of performing the function prior 10 to relying on it at the time it's needed.
So, if you 11 had a portable diesel you brought in, you would need 12 to demonstrate that the portable diesel is capable of 13 performing the function providing power to the buses, 14 but there would not be a surveillance activity that 15 would be continuing.
16 The other area that we're looking at 17 rulemaking is in the fire hazards analysis and in 18 instrumentation.
I said that we would get back to the 19 fire hazards analysis or the scope of the fire 20 protection program.
We think that.there needs to be 21 an analysis of fire hazards with respect to decay heat 22 removal during cold shutdown and refueling with some 23 modifications from what we've done in the past.
We 24 believe it should be a realistic fire based upon 25 combustibles in the area, transient materials and NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVENUE. N.W.
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53
)
1 ignition sources.
2 We think that only you need not 3
consider a loss of off-site power except in those 4
cases where the loss of off-site power results from 5
the fire in the area.
We think that there ought to be 6
repair capability to restore decay heat removal within 7
about 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
So that means that you have to look 8
at the capabilities to implement that restoration. We
]
I 9
think alternate methods of decay heat removal must be 10 available during that 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> period of repair.
This 11 is a contingency approach that would be taken.
12 You'd asked the question
- earlier, 13 Commissioner de Plangue, regarding whether this could 14 be a one time review or an each outage review.
I 15 think that's a function of the type of analysis that 16 a
license would propose.
If they propose hard 17 equipment or physical separation and they modify the 18 facility to accommodate that, then that would not 19 require them to do an outage by outage evaluation.
If 20 on the other hand they have not taken that approach 21 and they address what they're going to do by way of 22 control of transient material, ignition sources.and.
23 contingency planning and the contingency methods of 24 decay heat removal vary from outage to outage based 25 upon what work is going on, then they would be in the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVENUE, N W.
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latter mode.
Either option would be available under 2
the rule.
3 We think that they need to consider such 4
things as how they would make up to the reactor 5
coolant system by way of water makeup, what decay heat 6
removal functions are available, electrical power 7
needs and instrumentation needs.
We think that these 8
issues would be covered with the minimum allowed 9
equipment by technical specification so that there is 10 a tie between this and the redundant decay heat 11 removal capabilities.
We'd like to have-a fire only 12 impact, a train during this period of time.
So, if 13 there are fire areas that impact redundant 14 capabilities, whether it be service water or decay 15 heat removal, then there would need to be some 16 contingency set so that if there were a fire in that 17 area you're still able to perform the function.
18 This is not proposed to be a change to 19 Appendix R.
We feel that these approaches are more 1
20 realistic and it provides flexibility in planning 21 activities during outages and we are not proposing 22 that there be a physical separation _ required, which 23 would be the case if you were to apply it to Appendix 24 R.
25 CHAIRMAN SELIN: Is there anything to just NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVENUE, N W.
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try to prevent the fires in the first place, good 2
housekeeping and control of combustibles?
MR. RUSSELL: That's clearly a part of the 4
- program, what they're going to do by way of 5
controlling.
But, in fact, that part of the program 6
should be in place now.
7 DOCTOR THADANI:
That should be in place 8
now.
9 MR. RUSSELL:
They establish fire watches 10 for hot work and they have requirements to have fire 11 watches or take other action when the barriers are 12 breached.
The problem is that the design essentially 13 looks at the capability of removing decay heat when 14 you're hot.
Our events started from power and this is 15 an area where our regulatory framework did not require 16 an evaluation of the capability to remove decay heat 17 when in shutdown, when you're in subcool modes.
18 DOCTOR THADANI: And, Mr. Chairman,- if you 19 look at the data, what you find is that the frequency 20 of fires is actually going down, significant fires is j
21 clearly going down over the years.
)
-i 22 CHAIRMAN SELIN: In shutdown or across the-I 23 board?
24 DOCTOR THADANI:
No, across the board.
)
25 Frequency during shutdown is higher, but across the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVENUE, N W.
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board the frequency is going.down.
2 MR. RUSSELL:
(Slide)
If I could have 3
slide 6, please.
f 4
COMMISSIONER REMICK:
Bill, I guess I had 5
a question before you go onto that.
On page 4 of'the i
6 SECY document you indicate an option for dealing with' 7
fire protection in shutdown modes by revising existing 8
regulations to include deto led supplemental r
9 requirements.
The word " detailed" caught my eye 10 because to me that might mean prescription and it 11 reminds me of Appendix R,
which from a
biased 12 viewpoint I don't think was our shining hour.
How 13 detailed?
14 MR.
RUSSELL:
That's why I tried to 15 describe some of the approach that we had in mind.
16 COMMISSIONER REMICK:
Those were the 17 approaches you had in mind.
18 MR. RUSSELL: This is the approach that we 19 have in mind.
20 COMMISSIONER REMICK:
Okay.
21 MR.
RUSSELL:
We are not down to 22 specifying fires in fire zones of mechanisms that i
23 would be very severe. We're proposing realistic.
So, 24 this is a modification from the approach we've taken 25 in Appendix R.
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57 4
1 COMMISSIONER REMICK: Yes. So, by details 2
were the things.you just went over.
That's what you i
3 had in mind?
^
4 MR. RUSSELL:
That's the scope of what 5
we're proposing to address.
6 COMMISSIONER REMICK:
Okay.
7 MR. RUSSELL:
What I'd like to do now is 8
address essentially the rationale for why-the staff i
9 believes that there is time to implement rulemaking i
10 given the.
.is is going to stretch out for a couple 11 of years.
12 First we have seen improvement in the 13 implementation of the industry initiative,' NUM72C i 14 06.
There are a few isolated cases where it's still 15 raising questions regarding minimum equipment 16 availability during shutdown for particular modes. Ne 17 are addressing that through our inspection activities.
18 We he,ve issued a temporary instruction and that 19 enhanced activity is in place basically looking at the 20 conditions that are present and what type of outage 21 planning has been put in place and contingency 22 planning.
23 CHAIRMAN SELIN:
The thing I had in my --
24 the idea I had in my question was roughly speaking 25 you're talking about two kinds of things in the rule.
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one is a set of - operat.donal steps you'd like to see
~
2 taken.
The second is a set of material, capital steps 3
you'd like to see taken.
Is there a convenient way to 4
encourage the operational steps to be taken faster?
5 Obviously we wouldn't want to. force people to make 6
capital investments on a rule that might be changed 7
significantly in the process.
But the control steps 8
and the planning steps, which are relatively low cost 9
steps, do you think your plan adequately takes account 10 of the desirability of these being implemented i
11 somewhat earlier than the major capital cost things?
12 MR. RUSSELL:
I believe that in fact the 13 answer to that is yes.
In fact, some of it is going 14 on now on a voluntary basis by industry as a result of 15 their initiative.
Their activities in 91-06 16 essentially address the issues of outage planning and 17 control, contingency plans to ensure minimum equipment 18 availabilities.
It does not have a floor level and it 19 does have a regulatory base.
That is there are not 20 clear, specific minimums that have been established.
21 The areas where there are weaknesses are 22 in fire protection and the redundant hardware 23 instrumentation for mid-loop operation that Bob 24 mentioned for the PWR.
Those would be new areas to be 25 addressed.
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CHAIRMAN SELIN:
My own personal view is i
2 it's not appropriate to try to get people to put in 3
instruments until you've gone through the rulemaking.
^
4 That's the whole idea of a rulemaking, et cetera.- I'm 5
not clear on the fire protection, how much of that is 6
better operations and planning and how much of that is 7
capital investment.
8 DOCTOR THADANI:
Essentially all planning 9
basically.
I would be surprised if there's any 10 significant hardware modification.
I 11 MR. RUSSELL: But there are choices. They 12 could go through the planning process for each outage 13 and address it on an outage-specific basis or they 14 could do it one time with some capital improvements 15 and --
16 CHAIRMAN SELIN:
Oh, I see.
17 MR.
RUSSELL:
provide physical 18 separation.
So, that's an option that's available.
19 What we would encourage would be better addressing of 20 fire hazard and risk administratively in'the interim 21 period, looking at control of combustibles, alerting i
22 people to the importance of this and the significance
)
23 of some fire areas.
24 CHAIRMAN SELIN:
Through information
-l 25 notices or --
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DOCTOR THADANI:
And the key is 2
maintenance.
3 CHAIRMAN SELIN: 'Is this basically through 4
information notices as oppcccd to a gencric letter or '
5 something?
6 DOCTOR THADANI:
It would be information 7
notices.
8 MR. RUSSELL:
We have, in fact, provided 9
this information in that the NUREG with the technical 10 rational and the concerns has been available for some 11 time.
We've had a number of workshops that we have 12 participated in on shutdown risk.
We've had regional 13 briefings, et cetera.
So, I believe that we've done 14 a reasonable job of getting the word out.
15 CHAIRMAN SELIN:
But. you don't have a 16 document that says that the Commission would encourage 17 this or something.
I mean there is no such document.
18 I mean it's not appropriate to have such a document.
19 MR. RUSSELL: The guidance in the past has 20 been that we should ensure 'the soundness of our 21 regulatory base before we arm-twist, et cetera.
22 DOCTOR THADANI:
I would go back and say 23 information --
24 MR. RUSSELL:
We are cautious in doing 25 that.
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1 DOCTOR THADANI:
-- notices is the level 2
at which we could go.
3 CHAIRMAN SELIN:
Okay.
4 MR. RUSSELL:
I would like to point out 5
though that we also believe that the regulatory 6
analysis, which this I think is a good test case where 7
we have looked at the Commission safety goals in 8
making judgments about screening and that is addressed 3
9 in the regulatory analysis.
These events are not 10 10 events.
We would not be at this table proposing this 11 kind of a schedule if we were looking at something 12 that was a 10-3 per reactor year event.
4 4
13 It is in the range of 10 -to 10 when you 14 address the sensitivity studies and the uncertainty.
15 It is very dependent upon human error probability.
16 But from a risk perspective, we think it's one that 17 warrants going forward on a reasoned basis and would 18 support rulemaking.
So, we feel that the combination 19 of the industry initiative, what we're doing by way of 4
20 inspection and our findings regarding risk, would say 21 that we do have time and should proceed in an orderly.
22 manner to rulemaking.
23 (Slide)
If I could have slide 7, please.
24 We have received all of the comments on j
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We're going to revise that and issue it NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVENUE N W.
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final with our recommendations to proceed to 2
rulemaking. We expect to issue that in August of '93.
3 The actual development of the draft rule, associated 4
regulatory guide and supporting information we think 5
will take us to about December of 1993. We anticipate 6
that this will take more than one CRGR meeting and it 7
may take more than one additional ACRS meeting.
But 8
following CRGR review and ACRS review and Commission 9
approval, 'we anticipate that we would be able to issue 10 a proposed rule for public comment in May of
'94.
11 Following
- that, we would conduct a
12 workshop with industry and the public to receive 13 comments on the proposed rule in addition to the 14 written comments that normally come in in response to 15 a rulemaking.
We're anticipating it would take about 16 a year from the time of the proposed rule to the final 17 rule and it's principally based upon the ' technical 18 information having been available for some time and 19 the approach having been identified such that we would 20 be able to proceed relatively quickly with a
21 rulemaking.
22 That completes the staff presenution and 23 we're ready to take additional questions.
j 24 CHAIRMAN SELIN:
Commissioner Rogers?
25 COMMISSIONER ROGERS:
Does the EPRI NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RMODE ISLAND AVENUE. N.W.
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63 1
requirements document address these
- issues, the 2
advanced light water reactor requirements document?
3 MR. RUSSELL:
In the context that they 4
have additional requirements on systems and those 5
additional requirements have resulted in additional 6
redundancy, principally for flexibility and r
7 operations, yes, it does.
We have had dialogue with 8
the evolutionary plant vendors and we provided them 9
copies of the draft NUREG report and'we have been 10 performing analyses to look at the capability of the 11 new designs to handle shutdown events.
We have also 12 sent to General Electric the model specifications for 13 shutdown events and it appears at this point from the 14 analyses they've done that they are able to meet the 15 goals of essentially assuring highly reliable decay 16 heat removal during shutdown.
That is maintain 17 subcool and decay heat removal _and that they have 18 sufficient and significantly better equipment for 19 doing that from the standpoint of redundancy and 20 additional capability.
21 COMMISSIONER ROGERS:
That's all.
22 CHAIRMAN SELIN:
Commissioner Remick?
23 COMMISSIONER REMICK:
I agree that 24 rulemaking is the proper route, but just a question of 25 curiosity.
In a country like France when they have NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVENUE, N W.
' (202) 734-4433 WASHINGTON. D C 20005 (202) 234 4433
64 1-something like this do they impose these'by license t
2
' condition or through change of regulations?
I'm just 3
picking out France as one example because you said 4
there, or Sweden is another.
5 MR. RUSSELL:
Possibly the best thing to 6
do would be to give you the comparative analysis that 7
was done for each country because it describes the 8
approaches that were taken and how they were 9
implemented.
It is a combination.
They did have 10 technical specifications that addressed shutdown 11 conditions, but then they also have requirements that 12 are essentially in each outage requirement where 13 information is submitted to the regulatory authorities 14 prior to the outage that addresses both the planned i
15 activities, modifications to be made and what are the 16 significant safety aspects associated with the outage.
17 In France, for example, for mid-loop, each 18 time mid-loop is entered it requires a specific 19 approval of the regulator.
20 COMMISSIONER REMICK: But did they do this 21 by equivalent of a condition on the individual plant 22 licenses or is it done as a regulation?
23 MR.
RUSSELL:
I would characterize it 24 varies from country to country.
Generally it is not 25 done at the level of a regulation.
It is more of a NEAL R. GROSS COURT REPORTERS AND TRANSCRIBER 3 1323 RHODE ISLAND AVENUE. N.W.
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65 1
cooperative relationship that exists between the 2
regulator and the regulated.
3 COMMISSIONER REMICK:
I would expect that'
~
4 in Japan too.
5 MR. RUSSELL: That's very much the case in 6
Japan.
It's mostly a consensus process and then the 7
action is taken.
8 COMMISSIONER REMICK:
- Now, the' SECY-'
9 document refers to low power operation, but we really 10 haven't discovered low power operation.
Is there 11 anything unique in low power operation that we haven't 12 discussed in the shutdown risk area?
13 MR.
RUSSELL:
The issues that were of 14 concern associated with low power operation were 15 essentially some boron dilution events due to losses 16 of power during start-up that could result in pure 17 water slug in a loop with the subsequent initiation of 18 recirculation by recovering AC power.
We found that 19 those events were not as significant, but We did 20 address the entire scope and there are conditions when 21 draining down, for example, and going into mid-loop.
22 That's of concern.
But we addressed the entire scope, 23 but most of our focus has been on mid-loop and decay 24 heat removal during modes 5 and 6 or 4 and 5.
25 COMMISSIONER REMICK:
One time I NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVENUE, N.W.
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thought -- a year or so ago when you started you were 2
looking up to 15 percent power or something like that.
3 MR. RUSSELL:
Yes, we were.
4 DOCTOR THADANI:
Yes, we were.
5 MR.
RUSSELL:
That was more for-6 completeness.
7 COMMISSIONER REMICK:
Yes.
8 MR. RUSSELL:
We did not find significant.
9 issues that required additional action on our part.
10 DOCTOR THADANI:
If I may go back to your 11 earlier question.
12 COMMISSIONER REMICK:
Yes.
13 DOCTOR THADANI:
I've been looking at the 14 table that we have for various countries.
It looks 15 like most of the countries are imposing these 16 requirements through technical specifications, most 17 countries.
18 COMMISSIONER REMICK: I 5:.:0.
Okay. Thank 19 you.
20 CHAIRMAN SELIN:
Commissioner de Planque?
21 COMMISSIONER de PLANQUE:
Just one 22 question cn the containment integrity issue.
You 23 mention in the paper the possibility of installing 24 containment closure manifolds. This is rather costly.
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67 1
that?
2 MR. RUSSELL:
I think we'd have to get 3
back.
It is one of the possibilities.
I. personally 4
believe it's probably easier to set containment 5
integrity.
That's done now for handling fuel and to 6
set it in advance rather than to go to significant 7
design modifications.
We'll have to get back to you 8
to give you that eatimarc.
9 COMMISSIONER de PLANQUE:
Okay.
That's 10 all.
11 CHAIRMAN SELIN:
- Well, the Commission I
12 thanks you for the presentation.
Obviously this is 13 not a topic which I personally and some of the rest of 14 us are familiar as some others.
So, it was 15 particularly educational in going through the 16 discussions. This is an information meeting, although 17 there's some significant. policy issues.
It's pretty 18 clear that the sense is that if there's action to be 19 taken, it should be taken through a rule.
I mean as 20 the General Counsel's deputy said, this is a pretty 21 standard case.
22 I'm still personally interested in the 23 operational questions because although you've all 24 correctly stated that the contribution to risk isn't j
4 25 very large, the cost isn't very large either.
So, NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVENUE. N W.
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68 t
1 those seem to be ideal questions for the industry to 2
move out smartly and just take care of and not let the 3
discussions concentrate on the higher cost items.
^
4 So, anyhow, we thank you very much for the 5
presentation.
Very well done.
It does continue to 6
show the importance of the overall fire program.
You 7
know, it's a general risk of getting involved between 8
fire barriers and fire protection, the one being 9
something we have to clean up our act on, but it's not 10 essential.
The other is really a central issue on 11 what we do and I would hope that the attention that 12 goes to fire barriers doesn't detract from the real 13 attention on protecting against fire in power plants.
14 DOCTOR THADANI:
No.
In
- fact, Mr.
15 Chairman, the program that we have does look at all 16 aspects, where we have perhaps gone too far and where 17 we may not have gone far enough.
18 CHAIRMAN SELIN:
Right.
Fine.
Thank you 19 very much.
20 (Whereupon, at 11:20 p.m.,
the above-21 entitled matter was concluded.)
22 23 24 e
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVENUE, N.W.
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CERTIFICATE OF TRANSCRIBER This is to certify that the attached events of a meeting of the United States Nuclear Regulatory Commission entitled:
TITLE OF MEETING: BRIEFING ON OPTIONS FOR ADDRESSING SHUTDOWN AND LOW POWER RISK ISSUES-PLACE OF MEETING: ROCKVILLE, MARYLAND DATE OF MEETING:
JULY 20, 1993 were transcribed by me. I further certify that said transcription is accurate and complete, to the best of my ability, and that the transcript is a true and accurate record of the foregoing events.
j M
44 1-J g
Reporter's name:
Peter Lynch b
.1
.i 1
9 1
l HEAL R. GROSS i
cover apaavans me in4Mscamans 1333 AM005 ISLAND AVINUE, N,W, (302) 234-4433 WASDONSTON, DA 20005 (202) 232 4 000
NRC STAFF PRESENTATION TO THE COMMISSION JULY 20,1993 1
SHUTDOWN RISK PROGRAM L
WILLIAM T. RUSSELL,
-ASSOCIATE DIRECTOR, INSPECTION AND TECHNICAL ASSESSMENT OFFICE OF: NUCLEAR REACTOR-REGULATION ROBERT C. JONES, CHIEF, REACTOR _ SYSTEMS BRANCH-
L SHUTDOWN RISK PROGRAM BACKGROUND BROAD AGENCY-WIDE PROGRAM INITIATED IN 1990
- VOGTLE EVENT AND INTERNATIONAL STUDIES RAISED l
NEW CONCERNS l
- PREVIOUS REVIEWS HAD ADDRESSED ISSUES INDIVIDUALLY THREE PHASE: PROGRAM
- COMPLETE TECHNICAL STUDIES
- IDENTIFY, AND EVALUATE ISSUES
- RESOLVE ISSUES INTERFACED WITH lNDUSTRY TECHNICAL FINDINGS DOCUMENTED IN NUREG-1449 DRAFT =FOR COMMENT FEBRUARY 1992 1
SLIDE 1 (W. RUSSELL) i
1 BACKGROUND STAFF BRIEFED THE COMMISSION 09/17/92 REQUIREMENTS UNDER CONSIDERATION PRELIMINARY REGULATORY ANALYSIS COMMISSION REQUESTED:
PROS AND CONS OF RULEMAKING VERSUS GENERIC LETTER BASIS FOR STAFF'S COST / BENEFIT EVALUATION STAFF REQUIREMENTS MEMORANDUM ISSUED 09/30/92 COMMISSION PAPER SUBMITTED IN RESPONSE TO SRM (SECY-93-190)
. SLIDE 2 (W RUSSELL)
TECHNICAL FINDINGS CORE DAMAGE FREQUENCY ESTIMATED TO RANGE FROM 1E-4/RY (PWRs) TO 1E-5/RY (BWRs) i l
VULNERABILITIES:
PWR--LOSS OF RESIDUAL HEAT REMOVAL SYSTEM BWR--LOSS OF COOLANT VIA DRAINING EFFECTIVE OUTAGE PLANNING AND CONTROL CAN SUBSTANTIALLY REDUCE SHUTDOWN RISK
[
RESIDUAL HEAT REMOVAL SYSTEM MAY BE VULNERABLE TO FIRE 1
REDUNDANT ON-SITE POWER CAPABILITY SIGNIFICANTLY REDUCES RISK DURING REDUCED INVENTORY OPERATION RISKS ARE MINIMAL.WHEN REACTOR -CAVITY FLOODED CORE DAMAGE WITHOUT CONTAINMENT CLOSURE RESULTS IN LARGE OFFSITE AND ONSITE RELEASES SLIDE 3 (R JONES)
~
PROPOSED GENERIC REQUIREMENTS 4
SUMMARY
OUTAGE PLANNING AND CONTROL l
- REQUIRE THAT LICENSEE HAVE PROGRAM l
- PROGRAM SHOULD COVER:
- NUMARC 91-06 GUIDANCE
- FIRE PROTECTION
- PROCEDURES FOR USE OF INSTRUMENTATION TECHNICAL SPECIFICATIONS l
i
- REQUIRE OPERABILITY OF REDUNDANT DHR, ECCS, I
EDG WHEN REFUELING CAVITY NOT FILLED (PWR & BWR)
(INCLUDING REDUNDANT SUPPORT. SYSTEMS)
- PWRs ADD DIVERSELLEVEL INDICATION FOR MID-LOOP SLIDE 4.(R JONES) s
..-......,4..
.i..
. -. +,.,
..m.,
+...,,,,,
J.,,
STAFF RECOMMENDATION STAFF RECOMMENDS RULEMAKING
- SHUTDOWN OPERATIONS NOT FULLY 1
ADDRESSED IN CURRENT REGULATIONS
- RULEMAKING FACILITATES IMPLEMENTATION y
OF GENERIC REQUIREMENTS AND ENSURES l
THEY ARE LEGALLY BINDING j
4
-SUDE.5 (W RUSSELL)
L
=
SHUTDOWN RISK PROGRAM STATUS
- lMPLEMENTATION OF INDUSTRY INITIATIVE I
LNUMARC 91-06 COMPLETE?
l
- TEMPORARY INSTRUCTION FOR ENHANCED INSPECTION l
.DURING EACH OUTAGE REMAINS IN PLACE
- DRAFT REGULATORY ANALYSIS COMPLETED WHICH SUPPORTS IMPOSITION OF COST-JUSTIFIED SAFETY IMPROVEMENTS SLIDE f 6-(W RUSSELL) nu
...w -
__,,_,,-w--g
.~
SHUTDOWN RISK PROGRAM FUTURE ACTIVITIES 4
ISSUE NUREG-1449 IN FINAL FORM WITH PUBLIC COMMENTS ADDRESSED (AUGUST 1993)
DEVELOP DRAFT RULE AND ASSOCIATED REGULATORY i
GUIDE (DECEMBER 1993)
+w.
FOLLOWING COMMISSION AND CRGR' APPROVAL, ISSUE PROPOSED RULE FOR PUBLIC COMMENT (MAY 1994)
CONDUCT WORKSHOP WITH INDUSTRY AND PUBLIC TO RECEIVE COMMENTS ON PROPOSED RULE ISSUE FINAL RULE WITH APPROVAL OF ACRS, CRGR LAND COMMISSION (MAY 1995)
SLIDE 7 -(W RUSSELL)
CALCULATED RELEASES AT POWER AND SHUTDOWN i
OPERATING PERSON-REM PERSON-REM PLANT CONDITION AT 50 MILES ONSITE.
i SURRY SHUTDOWN 3.1 E + 06 2.0 E + 05 SURRY POWER 1.7 E + 06 GRAND GULF SHUTDOWN 8.0 E + 05 2.0 E + 05 GRAND GULF POWER 3.1 E + 05 ZION POWER 5.0 E + 06 a
GENERIC SHUTDOWN 2.0 E + 06 2.0 E + 05 -
t BACK-UP SLIDE 1
.=
OUTAGE PROGRAM DESIRED ELEMENTS o
COVERED IN NUMARC GUIDANCE TO UTILITIES
- CLEAR SAFETY PRINCIPLES l
- CLEAR ORGANIZATIONAL ROLES AND RESPONSIBILITIES t
- CONTROLLED PROCEDURE FOR PLANNING PROCESS
- PRE-PLANNING FOR ALL OUTAGES
- STRONG TECHNICAL INPUT FROM ANALYSIS
- INDEPENDENT SAFETY REVIEW OF THE PLAN AND MODS L
- REAL TIME SAFETY INFORMATION DURING OUTAGE
- CONTINGENCY PLANS AND BASES
- REALISTIC CONSIDERATION OF STAFFING NEEDS
- TRAINING i
- FEEDBACK OF EXPERIENCE TO PLANNING PROCESS l
l o
NOT COVERED IN NUMARC GUIDANCE TO UTILITIES l
- FIRE PROTECTION
- PROCEDURES FOR USING EXISTING INSTRUMENTATION BACK-UP SLIDE 2 l
.