ML20073Q023

Responds to 830208 Generic Ltr 83-10C Re Resolution of TMI Action Item II.K.3.5, Automatic Trip of Reactor Coolant Pumps. Plan for Demonstrating Compliance Submitted

ML20073Q023
Person / Time
Site:	Beaver Valley
Issue date:	04/22/1983
From:	Woolever E DUQUESNE LIGHT CO.
To:	Eisenhut D Office of Nuclear Reactor Regulation
References
TASK-2.K.3.05, TASK-TM 2NRC-3-019, 2NRC-3-19, GL-83-10C, NUDOCS 8304280089
Download: ML20073Q023 (6)

Text

e I-2NRC-3-019 (412)787 - 5141 m

(412)923 - 1960 Telecopy (412) 787-2629 Nuclear Construction Olvision April 22,1983 Robinson Plaza, Building 2, Suite 210 Pittsburgh, PA 15205 United States Nuclear Regulatory Commission Washington, DC 20555 ATTENTION:

Mr. Darrel G. Eisenhut, Director Division of Licensing Of fice of Nuclear Reactor Regulation

SUBJECT:

Beaver Valley Power Station Unit No. 2 Docket No. 50/412 Response to Generic Letter 83-10c

" Resolution of the TMI Action Plan Item II.K.3.5 -

Automatic Trip of Reactor Coolant Pumps" Gentlemen:

INTRODUCTION The criteria for resolution of 'IMI Action Plan Item II.K.3.5,

" Automatic Trip of Reactor Coolant Pumps" were stated in let ters from Mr. Darrel G.

Eisenhut of the Nuclear Regulatory Commission (NRC) to all Applicants with Westinghouse (W) designed Nuclear Steam Systems (Generic Letter 83-10c) dated February 8,

1983, and received by Beaver Valley Project Office on February 22, 1983.

The following represents the plan for demonstrating compliance with those criteria.

In order to avoid confusion, the overall philosophy and plan will first be stated.

Then, each section of the attachment to NRC letter 83-10c will be addressed as to how the overall plan responds to each NRC criteria.

OVERALL PLAN In the four years that have passed since the event at Ihree Mile Is land (TMI), W and the Westinghouse Owners Group (WOG), of which Beaver Valley Power Station Units Nos. I and 2 are members, have held steadfastly to several positions relative to post accident reactor coolant pump (RCP) operation.

First, there are small break IOCA's for which delayed RCP trip can result in higher fuel cladding temperatures and a greater extent of zircalloy-water reaction.

Using the conservative evaluation model, analyses for these IDCA's result in a violation of the Emergency Core Cooling System (ECCS) Acceptance Criteria as stated in 10CFR50.46.

The currently approved W Evaluation Model for small break IDCA's was used to perform these analyses and found acceptable for use by the NRC in letter 83-10c.

Therefore, to be consistent with the conservative analyses performed, the RCP's should be tripped if indications of a small break IDCA exist.

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Mr. Darrel G,fEi'senhut, Director Page 2 Secondly,3W, Beaver Valley Power Station Unit No. 2 -(BVPS-2), and WOG have always : felt c that the.RCP's -'should. remain'- operational for. non-LOCA - tran--

sients and ' accidents where their operation is beneficial to accident miti-

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' gation Cand.~ recovery.

This - position was taken even though a _ design basis for the: plant is a loss' of of f-site power.. Plant ; safety is demonstrated in

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BVPS-2 Final Safety Analysis Report (FSAR) = Chapter 15; for trans ient s : and -

accidents using' the most conservative assumption for ' reactor coolant pump operatiion.

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_ In keeping _with these two positions, a low RCS pressure (symptom based) RCP trip criterion was' developed'that provided an indication to the operator to

. trip the RCP's fors small. break LOCA but - would not indicate a need to. trip

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the RCPl'for the more_.likely non-LOCA transients and accidents where continued RCP operation is desirable.

.The. basis for this criterion is

' included in; the generic Emergency Response Guideline (ERG). Background Document-(E-0 Basic Revision, Appendix-A).

Thirdly,-lit has always been the position of W, BVPS-2, and the WOG that if there is doubt as to.what type of transient:ol accident is in progress, the RCP's ' should. be tripped.

Again, the plants' are designed to mitigate the effects. of all transients and accidents even without RCP operation while maintaining ~ a large. margin of safety 'to the public.

BVPS-2 emergency operating' procedures are planned to reflect this design approach.

Lastly, it. remains.the position of %, BVPS-2, and _ the WOG that RCP trip can be achieved safely and reliably-by The operator when required. An adequate amount = of - time ' exists for. operator action.for the small break LOCA's of interest.

The operators will be trained on the need for RCP trip and the

' emergency operating-procedures will give clear instructions on this matter.

W and the WOG will undertake a two part program.to address the requirements

_of NRC letter 83-10c based on the aforementioned positions for the purpose of.- providing more uniform RCP trip criteria and methods.of determining those criteria.

In the first part of the program, revised RCP trip criteria will be developed which provides an indication to the operator to c trip the RCP's for small break LOCA's requiring such action but will-allow

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continued RCP operation for steam generator tube ruptures,' less than or equal _ to a double-ended tube ruptura.

The revised RCP trip criteria will also be evaluated against other non-LOCA transients and accidents where continued RCP operation is desirable in order to demonstrate that a need to itrip the RCP's will not be indicated to the operator for the more likely Since this study is to be utilized for emergency response guideline cases.

development, _ better estimate assumptions will be applied in the considera-tion of the more likely scenarios.

The - first part of the program will be completed and ircorporated into Revision 1 of the ERG developed by W for the WOG.

The set eduled date for completion of Revision 1 is July 31, T983.

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The second part of the program is intended to provide the required justifi-cation for manual RCP trip.

This part of the program must necessarily be i

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~Mr. Darrel'G. Eisenhut,-Director Page~3 done af ter - the completion. of the first _ part of ' the program.

The schedule for completion of: the second = part'of the program is the end of 1983.

L The: preferred < and_ safest method of pump operation following a smal1l break

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LOCA.~ is 1 to ' manually'_ trip the :RCP's before ~ signific' ant: system voiding:

' occurs.- No attempt will be made in-this program to demonstrate the' accep-tability, of ' continued-RCP: operation during a small break LOCA. - Further, no-

request. for1an ' exemption to 10CFR50.46 will: be made-to allow continued RCP i

operation during;aismall break.LOCA.

DETAILED RESPONSE TO NRC LETTER 83-100-Each of the requirements stated: in the attachment to NRC letter 83-10c will now be' discussed indicating clearly how. they will be ad dres s'ed.

The organization of this section of the report parallels the attachment to NRC letter 83-10c.

1.

Pump Operation Criteria which can Res' ult in RCP Trip during Transients and Accidents 1.

Setpoints for RCP Trip

The WOG response to this section of requirements will be contained in Revision 1 to ' the ERG scheduled for July 31, 1983.

BVPS-2-will review, the ERG's Revision 1 for developing its own plant specific emergency operating procedure (EOP).

BVPS-2 plans on having plant specific E0P's drafted by August 1, 1984.

a '.- As stated above, W and the WOG are developing revised RCP trip criteria which will assure that the need. to trip the RCP's will be indicated to the operator for LOCA's where RCP trip is considered necessary.. The criteria will also ensure continued forced RCS flow for:

1.. steam generator tube rupture (up to the design bases, double-ended tube rupture)'

2.

the other more likely non-LOCA transients where forced

. circulation is~ desirable (e.g., steam line breaks equal to or smaller than one stuck-open PORV)

The criteria being considered for RCP trip are:

1.

RCS wide-range pressure < constant 2.

RCS subcooling < constant 3.

Wide-range RCS pressure < function of secondary pressure

a.

2

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Unitid'StctesNuclotrfRsguletoryCommission:

Mr..Darrel!G.'Eise'nhut, Director..

.; Page - 4 L s

t Instrument uncertainties will be accounted for; Environmental'

~ uncertainty will be included 'if appropriate. ! No ' partial. or staggered RCP trip ; schemes willLbe considered.- Such schemes-1 are. unnecessary and : increase x the requirement ? for training,.

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- procedures,. and. decision making by the operator : duringi tran- -

sients'and accidents.-

~b. ' The RCP trip ; criteria' selected ~ will be such that the operator' will'be instructed to trip ;the RCP's before voiding occurs at the RCP.

c.

The criteria. developed in It em ' la above is not expected to lead to.RCP. trip for the more likely non-LOCA and SGTR tran-sients.

However,. since ~ coctinued RCP operation cannot ' be guaranteed, the emergency response guidelines -provide guidance for the use of alternate methods for depressurization.

d.

The ERG contains specific - guidance for detecting, managing and removing - coolant voids that result. from flashing.

The symp-tons of such a situation are described in these guidelies and in ~ detail in.the background document-for' the guidelines.

Additionally, explicit -guidcnce for operating the plant with a vaporous: void. in the' reactor vessel head is provided in

' certain. cases wh'ere such operation is needed.

BVPS-2 will addre'ss these issues in their.EOP's draf t ' scheduled for August 1, 1984.

e.

Water services essential for RCP operation will be re-estab-lished as described in BVPS-2's FSAR, Section 6.2.4.

Guidance for Justification of Manual RCP Trip

2..

a.

A significant number of. analyses have been performed by W. for the WOG using the currently approved W Appendix K Evaluation Model for small break LOCA.

This Evaluation Model uses the W FLASH Code.

These analyses demonstrate for small. _ break tripped 2 minute's fol-LOCA's of concern, if the RCP's are lowing the onset of reactor conditions corresponding to the l

RCP trip setpoint, the predicted transient is nearly identical i

to those presented in the Safety Analysis Reports (SAR) for BVPS-2, Chapter 15.

Thus, BVPS-2 FSAR demonstrates compliance with requirement 2a.

The analyses performed for the WOG will be used to demonstrate the validity of this approach.

b.-

Better estimate analyses will be performed for a limiting W design plant using the W FLASH computer code with better esti!

mate assumptions.

These analyses will be used to determine l

' the minimum time available for operator action for a range of 2

l break sizes such that the ECCS acceptance criteria of 10CFR

Unitcd St&tss Nuclecr Rrgul'ctcry Commission' Mr. Darrel'G. Eisenhut, Director'.

Page 5 50.46 are not exceeded. It is: expected that the - minimum. time available -for. manual RCP. trip will. exceed the guidance contained in Draft. ANSI Standard N660..This will.-justify manual RCP - trip for all plants._

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~Other Considerations a.

BVPS-2'will respond'to the' criteria upon completion of the WOG report and its review.~-

b.

The ERG ' contains guidance. ' for the timely restart of. the.

reactor coolant pumps _ when conditions which will support safe pump start-up and operation are established.

II.. Pump Operation Criteria which~ will not Result in RCP Trip during-Tran-sient and Accidents The -preferred and safest method of operation following a small br' eak

.LOCA is to manually trip the RCP's.

Therefore, there is no need to

-address the criteria contained in this section.

DUQUESNE LIGHT COMPANY B

E. Q/ Molever Vice President SDH/wjs cc:

Mr..G. Walton, NRC Resident Inspector Ms. L. Lazo, NRC Project Manager t-SUBSCRIBED AND SWO TO EEFORE ME ON THIS j[

AY

, 1983.

MY d

/

Notary Public

/

ELVA G. LESONDAK, NOTARY PUBLIC RGBiNSON TOWNSHIP, ALLEGHENY COUNTY MY COMMISSION EXP!RES OCTOBER 20,1986

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_ U it'4d-StatGs Nuclsar R:gulctory Commission-Mr. Darral' G. ' Eieschut,' Dirgetor Page 6 +

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. COMMONWEALTH OF PENNSYLVANIA )

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SSi COUNTY'OF ALLEGHENY

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[On this d j ay of

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, befor'e me, a Notary Public in and for said Commonwealth -and County, _ personally appeared' E. J.

'Woolever, who being duly sworn, deposed and said that ' (1) he is Vice President. of Duquesne Light,- (2) he is duly ' authorized to exe-

- cute and _ file the foregoing -Submittal on behalf of said Company, and '(3) the statements set forth ~ in the Submittal are true -and correct to the best of-his knowledge.

Notarf Public ELVA G. LESONDAK, NOTARY PUBLIC ROBINSON TOWNSHIP, ALLEGHENY COUNTY MY COMMISSION EXPIRES OCTOBER 20,1985

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