ML20126F495

Summary of 921209 Meeting W/Bwrog Regulatory Guide 1.97 Committee in Rockville,Md Re Discussions on Recent Assessment of Adequacy of RPI for post-accident Monitoring. List of Attendees & Handout Matl Encl

ML20126F495
Person / Time
Issue date:	12/21/1992
From:	Menning J Office of Nuclear Reactor Regulation
To:	Office of Nuclear Reactor Regulation
References
RTR-REGGD-01.097, RTR-REGGD-1.097 NUDOCS 9212300352
Download: ML20126F495 (23)

Text

_ _ _ - _ _ _ -

'l '

' # 280

.# o

~g UNITED STATES

['

y c g NUCLEAR REGULATORY COMMISSION WASHINGTON D. C. 20555 December 21, 1992 k ....+ /

BOILING WATER REACTOR OWNERS GROUP MEETING

SUMMARY

OF DECEMBER 9, 1992, MEETING WITH BOILING WATER REACTOR OWNERS GROUP (BWROG) REGULATORY GUIDE 1.97 COMMITTEE TO DISCUSS ADEQUACY OF R0D POSITION INDICATION DESIGN The subject meeting was held on December 9,1992, at the Nuclear Regulatory Commission (NRC) Headquarters at One White Flint North in Rockville, Maryland.

The meeting was requested by the BWROG to discuss their recent assessment of the adequacy of rod position indication (RPI) for post-accident monitoring.

Enclosure 1 is a list of attendees and Enclosure 2 is a copy of the handout material provided by the BWROG.

The BWROG representatives initially discussed the events that resulted in their assessment of RPI. Specifically, all RPI was lost as a result of the failure of a nonsafety-related uninterruptible power supply (UPS) during the incident at Nine Mile Point Unit No. 2 on August 13, 1991. The NRC Incident Investigation Team (IIT) noted that loss of RPI required the operators to enter the anticipated transients without-scram contingency procedures and complicated their response to the incident. The IIT also noted that RPI is vulnerable to single failures such as the loss of a single UPS. NRC staff

? actions resulting from the IIT's investigation of the incident were identified in a remorandum from the Executive Director for Operations dated January 6, 1992. Item 2.c of the NRC Staff Action Plan was related to the IIT's RPI

, observations and required the Office of Nuclear Reactor Regulation to evaluate the need for alternate RFI or for providing safety-grade power to RPI systems.

The BWR0G agreed in discussions with NRC management to independently assess the adequacy of RPI for post-accident monitoring and provide the results of this assessment to the NRC for the agency's use in addressing Itm 2.c. The BWROG completed this assessment and requested the subject meeting to soitcit NRC staff comments on their inethodology prior to prcvidir.g the staff with a final report.

The BWROG representatives subsequently provided an overview of RPI designs, operator uses of RPI, and of the event analysis methodology used in the BWR0G assessment of the adequacy of RPI for post-accident monitoring. In essence, the BWR0G examined a broad spectrum of events within and somewhat beyond design basis. Events examined included transients with scram, accidents with scram, transients without scram, and other occurrences without scram. The importance of RPI to the operator was evaluated for each event by determining the difference in plant response if RPI was or was not available. The assessment used Revision 4 of the Emergency Planning Guidelines (EPGs) as the bases for operator actions. The assessment also considered the impact of the availability or unavailability of the neutron monitoring system-(NMS) on the importance of RPI. ,

The results and conclusions of the assessment of RPI were subsequently i presented by the BWROG. The CWROG determined that RPI is most important for ' y events which appear to involve a failure to scram when in fact a scram did 300029 ETilW TO PJ'B3]J0M CWI!n d 2 /'"i 9212300352 921221 /-l

. _ _ _ _ _ - _ _ _ - _ ._ .d $Y N .

l i--.* .

l 1 -

l i

i i

! BWR OWNERS GROUP MEETING December 21, 1992

, occur. The RPI was also fount to be important for events in which operators i.; have an opportunity to manually insert control rods. The assessment showed that RPI is not important for events where automatic response occurs very- -

rapidly, where it is obvious that a scram did occur,-or where it is relatively apparent that power is in the. decay heat range. The BWROG concluded that loss

of RPI is not a safety concern,

the EPGs adequately address indeterminate

control rod position, and there is no basis for requiring either an alternate

] RPI or safety grade power to RPI systems.;

1

- At the conclusion of the meeting the NRC staff indicated that the overall i methodology describeiby the BWROG seemed reasonable. The staff also stated -

! that they could not comment on the assessment-results and conclusions without completing a detailed review of the report. The NRC staff also suggested that the BWROG consider quantifying the risks of_ losses of RPI.and NHS and

, including these values in the final report. The BWR0G acknowledged the staff's comments and indicated that the final report would-likely be provided -

to the NRC staff in late February 1993. -The BWROG also stated that;they did -

not expect to receive a NRC staff evaluation of _the report-since they would'be j providing the report for the staff's internal use in addressing Item 2.c.

I

k.

' -John E. Menning, P ject Manager Project-Directorate I-1

Division of Reactor Projects - I/II

' Office of Nuclear Reactor Regulation

Enclosures:

1. -Attendance List

2. Handout Material l

i.

4 l

l-l

+

i h

i 4

4 s

i

's e -

- w s-,, ,w ,, . . . . - . , , - . - , , -

,,v, n-v... ,m.m,w,-n.a,,, 4,,,-am w-+-w, w-. w v.mm a-,, - , ,.m,-,..-

ENCLOSURE 1 DECEMBER 9. 1992 BOILING WATER REACTOR OWNERS GROUP MEETING R00 POSITION INDICATION DESIGN ATTENDANCE LIST i

4 Attendees Oraanization 4

H. Garg NRC/NRR/HICB A. Marinos NRC/NRR/HICB

S. Newberry NRC/NRR/HICB J. Menning NRC/NRR/PDl-1 S. Marek Detroit Edison F. Kenny GPU Nuclear G. Stranovsky NYPA R. Patterson Entergy Operations- ,

J. Wolcott TVA C. Tully Southern Nuclear Co.

J. Post General Electric A. Attard NRC/NRR/SRXB L. Lois NRC/NRR/SRXB

• 9

Meeting Between 4

the BWROG Reg Guide 1.97 Committee

, and the NRC e

l Rod Position Information System (RPIS) Issues 4

h i i i December 9,1992 ,

i Rockville, MD  ;>

c O '

5' 5

m 93 A

Agenda ..

t f

8:30 Introductions / Purpose JD Wolcott (TVA)

- 9:00 BWROG Approach agd Analysis JS Post (GE) f 10:30~. Discussion /StatTFeedback BWROG/NRC 11:30 Adjourn t

l JD Wolcott-1

! 12/9/92 i

Introduction ..

l

o. Loss of power event at NMP-2, August 13,1991, led to several Staff

~

concerns regarding reactivity monitoring instrumentation o BWROG/NRC Management discussions led BWROG to agree to  !'

assess. adequacy of RPIS for post-accident monitoring as input to Staff -

n o Concern being addressed by this meeting is NRR Staff Action Plan

. Iten 2c:

i- .

" Evaluate the need to provide an alternate Rod Position Indication (RPI) or safety grade power [to RPI] for BWRs."

i o BWROG is soliciting Staf0 comments on the BWROG approach r

i o Current BWR RPIS designs fully comply with' RG1.97 requirements a for post-accident monitoring (Type B, Category 3 instrument) l JD Wolcoa-2 i

12/9/92 i

Purpose of Meeting ,

o Inform the Staff of the BW,ROG approach: Outline the bases, assumptions, scope, results, and conclusions o Obtain Staff comments on'the BWROG approach

o Discuss Staff schedule and BWROG plans for submittal of the report  ;

9 I

i i.

JD Wolcott-3 12/9/92 ,

2 I-9

BWROG Approach and Analysis .

k l o Summary of Approach o RPIS Description 4

o Use During Normal Plant Operation o Basis for Event Analysis l o Events Analyzed o Results

(

o Conclusions l .

'JS Post-1 12/9/92 1

l

BWROG Approach and Analysis - Summary of Approach .

o Document the RPIS description, design bases, and regulatory .

requirements

o Examine RPIS use by the operator for normal operation and l- post-accident monitoring

i l o - Perform three step event analysis process:

i 1

1. . Determine the impact of RPIS failure on the. plant and operator '

[  : response

2. Use the impact assessment to determine RPIS importance for

[ . post-accident monitoring t

3. Use the importance tojudge if the existing RPIS system design '

is adequate i

JS Post-2 I

12/9/92 i

f

BWROG Approach and Analysis - Summary of Approach (continued) ,

o Same event analysis method as used for the NMS evaluation in NEDO-31558, March 1988:

-- Examine a broad spectrum of events within and somewhat beyond the plant design bases

- Evaluate importance of RPIS to the operator for each event by .

determining the difference in the plant response if RPIS is available or fails

- - Use EPG Revision 4 as bases for operator actions

- Consider the impact of NMS availability / failure on the RPIS importance l

JS Post-3

12/9/92 i

i .

4

BWROG Approach and Analysis - RPIS Description .

4 i

p o BWR/2-5 Designs:

l -

RPIS is part of the Reactor Manual Control System (RMCS)

Meets plant power generation requirement to know control rod j position i

t - Controllers (Rod Worth Minimizer and Rod Sequence Control l System) used to set / limit control rod positions - RPIS provides

input to controllers 1

! o BWR/6 Designs:  ;

! i RPIS is part of the Rod Control & Information System (RC&IS)

Meets plant power generation requirement to know control rod i L position L -

Two' channel Rod Pattern Controller used to set / limit control rod positions - RPIS designed as a two channel system to y

! provide input to the two RPC channels-f i JS Post-4 1 i

12/9/92 .

BWROG Approach and Analysis - RPIS Description (continued) .

o RPIS Position probe:

e Each position probe is a sealed tube that fits inside the CRD c assembly Tube contains 53 magnetically operated reed switches Switches at each increment (48; every.t1/ree inches), extra switch ,

at full-out, one at beyond full-out, two at full-in (Notch 00), and one at beyond full-in (53 total)

The control rod locks at the even numbered (Notch) positions The magnet is affixed to the hydraulic drive mechanism i

BWR/6 has two independent sets of reed' switches within the ,

position probe forlits two channel system j .i i

! JS Post-5 '

12/9/92 l

- BWROG Approach and Analysis - RPIS Description (continued) .

t o Variety of rod position displays across BWRs:

I - -Full core display with numerical position of each' rod and lights to indicate full-in and full-out

- Full core display with indicating lights only

[-

- Four-rod display to'show the position of a selected rod and the other rods in its immediate vicinity

- Process computer, SPDS displays, etc.

i l 'o Power supply'is typically an UPS i

i o .UPS has a backup power supply of a diesel, station battery, and/or i secondary power supply i

o RPIS power for BWR/6 is typically from a' Class 1E bus, but power for the operator display may be'from an instrument UPS f 4

[

JS Post-6 i 12/9/92 i ,

i I _. - _ _ _ - _ - _ - - - _ _ _ _ - - - - _ . - .____ __ _ _

BWROG Approach and Analysis - Use During Normal Operations .

t o RPIS used repeatedly during normal operations:

Every time a rod is being moved to a new location As input for core burnup, peaking, and core performance calculations To perform various Tech Spec surveillances (e.g. control rod operability, coupling integrity, rod pattern requirements) o Provides an alarm if a rod drifts o RPIS is input to the systems which restrict rod movements to set patterns o Any system faults that occur would likely be discovered and corrected during normal operations o The locking control rod drive mechanism makes a rod unable to

' withdraw once it is locked I

JS Post-7 1 12/9/92 l;

SWROG Approach and Analysis - Basis for Event Analysis .

i

o. Examine operator and plant response if reactivity monitoring instrumentation is available or has failed:

a. Both RPIS and NMS instruments work

b. RPIS fails, but NMS functions correctly

,i

c. RPIS and NMS both fail o Events selection criteria:

I 1. RPIS information is most useful to the operator

- 2. Full spectrum of operator actions related to post-accident shutdown are exercised 1

I

3. Spectrum of conditions the operator must evaluate occur 1 l

4. Impact on plant and operators if RPIS fails are maximized 4

I JS Post-8

12/9/92 4

-- x

.BWROG Approach and Analysis - Basis for Event Analysis (cont.) .

o Use generic BWROG EPG Revision 4 as basis for operator actions Possible post-accident monitoring uses of RPIS by the operator:

o

- Determine that all rods are fully inserted

. - Determine that control rods are sufficiently inserted so that the j

reactor will remain shutdown as reactor state conditions change .

- Determine if the reactor is critical, or the reactor is shutdown

- Determine candidate control rods for rod insertion actions

. following scram failures

- Monitor the effectiveness of rod insertion attempts i

i JS Post-9 '

] 12/9/92

- BWROG Approach and Analysis - Events Analyzed ,,

i a

i o Consider events within and somewhat beyond plant design basis:

Transients with scram o - Feedwater controller failure - maximum demand o Turbine trip with bypass failure Accidents with scram i o Large break LOCA with ECCS division failure '

o Small break LOCA with high pressure makeup failure

! o Control rod drop accident

- Transients without scram ,

o MSIV closure with complete scram failure o Inadvertent open SRV with partial scram failure Other occurrences without scram i o Recire pump seal leakage with manual scram which fails o Loss of drywell coolers, failure to scram 1.

i 1

i 4

j j JS Post-10 j l 12/9/92 t

1

BWROG A~pproach and Analysis - Events Analyzed (continued) i Operator- Impact of Impact of Add'nl Event Use of RPIS- RPIS Failurg NMS Failure FWC-Max Confirm all Enter ATWS EOP, Delay RPV E Demand rods in few actions req'd cooldown  :

TT with ditto ditto ditto  ;

., Bypass Failure

. Large ditto ditto' Possible boron

! LOCA indection i

Small ditto Enter ATWS EOP, Expected boron

. LOCA terminate and injection and

prevent indection water level prior to ADS reduction CRDA ~ ditto None None i

i JS Post-11 ,

12/9/92 .

4

BWROG Approach and Analysis - Events Analyz .? (continued) -

Operator Impact of Impact of Add'nl Event Use of RPIS RPIS Failure NMS Failure MSIV Determine None None Closure- rod pattern ATWS SORV Determine Less effective Accelerate boron Partial rod pattern, in driving rods injection ATWS prioritize rods to drive 4 Recirc ditto ditto .None - boron pump seal -injection not leakage required l ATWS Loss DW- ditto ditto ditto Coolers ATWS JS Post-12 12/9/92

BWROG- Approach and Analysis - Results ..

t o RPIS most important for events which may appear to have a scram failure when in fact a scram did occur j i

o RPIS also important for events with an opportunity to drive control rods t

t o RPIS not important for events where the automatic response occurs very rapidly, where it is obvious a scram did not occur, or where it is relatively apparent that power is in the decay heat range t

4 lL

! JS Post-13

12/9/92 i

BWROG Approach and Analysis - Conclusions .

1 i

. o Loss of RPIS is not a safety concern i

j o EPGs adequately address indeterminate control rod position r

o No basis for. requiring either an alternate RPIS or safety grade power to RPIS 4

4 .

3 i 1  ;

i b

t i

j t

i JS Post-14 l 12/9/92 h

BWR OWNERS GROUP MEETING - December 21, 1992 i

)

occur. The RPI was also found-to be important for events in which operators

- have an opportunity to manually insert _ control rods. The assessment showed

[ that RPI is not important for events where automatic- response occurs very 1 rapidly, where it is obvious that a scram did occur, or where it is rel_atively  ;

j apparent that power is in the decay heat range. The BWROG concluded that loss-

of RPI is not a safety concern, the EPGs_ adequately address indeterminate control rod position, and there is no. basis for requiring either an alternate i RPI or safety grade power to RPI systems.

1 At-the conclusion of the meeting the NRC staff indicated that the overall

methodology described by the BWROG seemed reasonable. The staff also stated i that they could not comment on the assessment results and conclusions without

completing a detailed review of the report. The NRC staff also suggested that

the BWROG consider quantifying the risks of-losses of RPI and NMS and i including these values in- the final report. .The BWROG acknowledged the i staff's comments and indicated that the final report would likely be provided .

i to the NRC staff in late February-1993.- The BWROG also stated that.they did

!- not expect to receive a NRC staff evaluation of the report since they would be l

providing the report for the staff's internal use in addressing. Item 2.c.

f Original Signed By:

l John E. Menning, Project Manager

Project Directorate 1-1

< Division of Reactor Projects - l/II

Office of Nuclear Reactor Regulation ,

l

Enclosures:

-t j 1. Attendance List <

2. Handout. Material "

l Distribution:

See next page

! PDI-1:LA-- PDI-1:PM- PDI-1:0 DRCH o //- DRC.

CVogan 02 JMenning:M 'RACapra F N nd SNdberry

j. M/ /92 h/ L4 /92 . FL /0 /92 /Z- //M92 IP/ ?>/92 /. /

L OFFICIAL. RECORD COPY-

!- FILENAME:-NM2BWROG.MTS i-l 4 n

.} .

BWR OWNERS GROUP MEETING DME: December 21. 1992 DISTRIBUTION: (w/ enclosures)

Central File NRC & Local PDRs P01-1 Reading

. T. Murley/F. Miraglia,12/G/18 .

J. Partlow, 12/G/18  !

S. Varga J. Calvo R. A. Capra

J. Menning C. Vogan OGC E. Jordan, MNBB 3701 H. Garg, 8/H/7 E. Marinos, 8/H/7 S. Newberry, 8/H/7 A. Attard, 8/E/23 L. Lois, 8/E/23 ACRS (10)

V. McCree, 17/G/21 C. Cowgill, RGN-I B. Boger, 13/E/4 R. Jones i

+

l 1