JPN-88-036, Responds to NRC Bulletin 88-004, Potential Safety-Related Pump Loss. Summary Rept of Review of safety-related Sys Encl.Commits to Submitting Detailed Calculations for RHR Pumps by 881028 & for Sizing of Min Lines by 890128

Responds to NRC Bulletin 88-004, Potential Safety-Related Pump Loss. Summary Rept of Review of safety-related Sys Encl.Commits to Submitting Detailed Calculations for RHR Pumps by 881028 & for Sizing of Min Lines by 890128

ML20151J384
Person / Time
Site:	FitzPatrick
Issue date:	07/22/1988
From:	Brons J POWER AUTHORITY OF THE STATE OF NEW YORK (NEW YORK
To:	NRC
References
IEB-88-004, IEB-88-4, JPN-88-036, JPN-88-36, NUDOCS 8808020235
Download: ML20151J384 (10)

Text

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Johti C Drom 4# Authority lll1;;;3:3P" July 22,1988 JPN-88-036 U. S. Nuclear Regulatory Commission Mail Station Pl-137 Washington, D.C.

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Attn:

Document Control Desk

Subject:

James A. Fitzpatrick Nuclear Power Plant Docket No. 50-333 i

NRC Bulletin 88-04: Potential Safety-Related Eump_LoEs

Reference:

1. NRC Bulletin 88-04, "Potential Safety-Related i

Pump Loss", dated May 5, 1988.

Dear Sir:

In Reference 1, the NRC asked all licenseed to investigate the potential for dead-heading one or more pumps in safety-relat3d systems.

The systems requiring evaluation utilize a common miniflow line for two or more pumps which does not preclude pump-to-pump interaction.

Licensees have to verify also whether the installed miniflow line capacity is adequate even when a single pump is in operation.

In response to the Sulletin, the Power Authority reviewed i

all the safety-related systems in the Fitzpatrick plant.

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review indicates that the FitzPatrick plant utilizes parallel pumps only in the Residual Heat Removal (RHR) system.

This system employs two pairs of parallel pumps with individual miniflow recirculation lines.

The miniflow lines contain orifices and are connected to a common low pressure discharge line.

This line discharges to the torus and is, therefore, at a relatively low pressure.

In order for an adverse inter-action to occur, the low pressure portion cf the miniflow line downstream of the orifice would have to become pressurized to approximdtely the shutoff head of the ' weak' pump of the pump pair.

Only under this condition would sufficient back pressure in the miniflow line exist to limit miniflow recirculation.

Since the common low pressure line is basically an extension of the torus, this situation is extremely unlikely.

Consequently, parallel pump interaction during miniflow operation is extremely unlikely at FitzPatrick.

However, the Authority will perform calculations to confirm the insensitivity of the RHR pumps to adverse pump interaction.

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For safety-related pumps with minimum flow recirculation l

lines, aGequate sizing of these lines has been proven by the i

j results of the surveillance tests conducted as required by the Technical Specifications.

These results demonstrate proper i

pump performance.

If any pump degradation were to occur due to inadequate minimum flow, it would be apparent from changes 3

observed during these tests, and repairs would have been performed.

Nevertheless, the Authority will perform calculations, and consult with the pump manufacturers, if possible, to confirm the adequacy of the existing minimum flow l

recirculation lines.

The Authority will submit the results of the detailed calculations for the RHR pumps by October 28, 1988 and for sizing of minimum flow lines by January 28, 1989.

A summary report of the review outlined above is enclosed as Attachment I.

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If you have any questions regarding this matter, please contact Mr. J. A. Gray, Jr. of my staff.

Very truly yours,

_3 Jo n C.

Brons l

Executive Vice president Nuclear Generation

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Enclosure STATE OF NEW YORK I

COUNTY OF WESTCliESTER

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Subscribed and Sworn to before me day of $ 4 1988 this 4 buhaAt dAx CIu W Tl b " '***

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U. S. Nuclear Regulatory Commission Region I 475 Allendale Road King of Prussia, PA 19406 Office of the Resident Inspector U. S. Nuclear Regulatory Commission P. O. Box 136 Lycoming, New York 13093 Mr. Harvey Abelson Project Directorate I-l Division of Reactor Projects - I/II U.S. Nuclear Regulatory Commission Mail Stop 14B2 Washington, DC 20555

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i JPN 036 ATTACHMENT I RESPONSE TO IE BULLETIN 88-04 SUM!!ARY New York Power Authority James A. FitzPatrick Nuclear Power Plant Docket No. 50-333 DPR-59

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The safety-related systems for the FitzPatrick plant were reviewed to determine the types and arrangement of all safety t

related pumps in use at the plant.

This review placed the t

various pumps innto three basic categories.

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1. Parallel centrifugal pumps with miniflow recirculation linos.

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2. Single centrifugal pumps with miniflow recirculation f

lines.

3. Single centrifugc1 pumps with no miniflow recirculation lines.

t The following paragrrphs describe the individual pumps and

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their configurations as categorized above.

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1. Eatallel centrifugal Pumps With_Kinillow Recirculation f

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Residual Heat Removal (RHR) pumps 10P-3A, 10P-3B, l

l 10P-3C, 10P-3D are the only pumps with parallel pump operation and miniflow recirculation lines.

These four pumps operate in two independent pairs.

The basic pump configuration is illustrated in Figure 1.

2. Einale Centrifugal Pumps With_Minillow Recirculation hines This category consists of 8 pumps.

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I RhR holding pumps 10P-2A, 10P-2B Reactor Core Isolation Cooling (RCIC) pump 13-P1 1

Core Spray pumps 14P-1A, 14P-1B Core Spray holding pumps 14P-2A, 14P-2B i

High Pressure Coolant Injection (HPCI) pump 23P-1

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These pumps employ miniflow recirculation lines for 2

operation during periods of low flow.

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3. Sin 21m_CentIllu21.1 Pumps _With_HQ_Miniflow RaciJculation Lines This category contains 6 pumps in two service water systems of the plant.

They aret RHR Service Water pumps 10P-1A, 10P-1B, 10P-lC, 10P-1D Emergency Service Water pumps 46P-2A, 46P-2B l

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i These pumps do not have miniflow recirculation lines.

The subject NRC Bulletin is concerned with two basic problems relating to the use of centrifugal type pumps.

These problems are:

1. Pump interaction when units are installed in parallel with common miniflow recirculation lines.

2. Adequate sizing of minimum flow recirculation lines of all installed pumps.

The following descriptions illustrate the FitzPatrick design as it pertains to the concerns prescr.ted in Bulletin 88-04:

Pumo Interaction When Units Are Installed In Parallel With Common Miniflow Recirculation L(nga The FitzPatrick plant design utilizes parallel pumps in the RHR system.

This system employs two pairs of parallel t

pumps with an individual miniflow recirculation line for each pump.

The miniflow recirculation lines for these pump pairs are each separately orificed and discharge to a common low pressure line downstream of each fluw limiting orifice.

Figure 1 illustrates this arrangement.

The flow downstream of each miniflow orifice discharges into a common line connected to the torus, which is main-tained at a relatively low pressure.

This common low pressure header ensures the ind.ividual and isoleted performance of each miniflow recirculation flowpath during periods of relatively low flow.

The use of an individual miniflow orifice for each pump maintains the independence i

of each flowpath to minimize the potential for pump i

interactions as describai in the subject Bulletin.

For an adverse interaction to occur, the low pressure portion of r

the miniflow line downstream of Fae orifice would have to I

become pressurized to nearly the shutoff head of the

' weak' pump of the pump pair.

Only then would sufficient back pressure in the miniflow lin0 exist to limit miniflow t

recirculation to unacceptably low levels.

Since this low pressure line is basically an extension of the torus, this situation is extremely unlikely at FitzPatrick.

However, l

the Authority will perform calculations to verify the f

hydraulic resistance of the low pressure header.

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Adggate Sizina of Minimum Flow Recirculation Lines Of All Installed Pumos This second concern icentified in the subject Bulletin relates to the adequacy of the miniflow recirculation capacities currently employed in the system designs.

The RHR pumps, in addition to the 14 pumps from categories 2 and 3, are the subject of this consideration.

These safety-related pumps operate in accordance with the Technical Specification requirements as evidenced by the surveillance test results which demonstrate proper pump performance.

Pump degradation would be apparent from c' anges evidenced during routine surveillance tests, and repairs would have been performed.

Nevertheless, a verification review of pump design conditions will be made in consultation with the various pump vendors.

Justification for Continued Operation Continued operations of the Fitzpatrick plant until further evaluations are completed, is justified for the following reasons:

Little time is spent at minimum flow during normal plant operation.

As a consequence, very little time is available during which pump excessive wear or performance degradation could occur.

Surveillance testing regularly confirms proper pump operation to ensure pump operability.

System operation in the minimum flow mode is limited to pump startup for surveillance testing and LOCA signal.

Fitzpatrick has parallel pump operation only in the RHR nystem.

During a loss of coolant accident (LOCA), the potential for dead-heading exists when the pumps are operating in the mininium flow condition.

For the RHR/LPCI mode of operation, the design basis events that would lead to palmps running in the minimum flow mode and/or dead-heading are events that result in an Emergency Core Cooling (ECC) system initiation signal.

These events are normally small break LOCAs and the reactor is at high pressure (above pump shutoff head).

Once initicted, the RHR pumps operate in the minimum flow mode for a short duration.

This is derived from postulated small break LOCAs, where reactor depressurization to below the shutoff head of these > umps is delayed.

For large break LOCAs, where the full complement of ECC system is more fully i

atilized, the reactor inherently depressurizes through tha break.

The present minimum flow bypass lines are expected to provide adequate protection for these pumps for compliance with ECC system requiren.ents for the short durations postulated during both the small and large break r

LOCAs.

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Conclusisma:

The concerns presented in NRC Bulletin 88-04 have been reviewed for their applicability to the FitzPatrick plant.

Prelim! nary review indicates that no safety concerns exist.

The Authority plans further evaluation and analysis to verify the results of the Authority's initial review.

These analyses will consist of the following specific actions:

1.

Perfort as built hydraulic calculations to verify the insensitivity of the RHR pumps to adverse pump inter-actions.

2.

Review the safety-related pumps in categories 2 and 3 to determine the adequacy of the existing miniflow line capacities and arrangements.

Consultation with the original pump manufacturers, where possible, will be used to develop the required minimum flow values.

Calculations will be performed to determine the 'as built' miniflow rates.

This effort will verify the existing miniflow designs or illustrate the need for design changes to the existing miniflow circuits.

A schedule for the above actions is as follows:

Item 1 - Perform as b* tilt hydraulic calculations for the RHR pump miniflow c' aits - this work will be completed by October 28, 1986 Item 2 - Review sad perform calculations for the existing miniflow circuits on the remaining safety-related pumps -

this work will be prioritized in the following manner:

1.

Core Spray, HPCI pumps - these pumps will be evaluated first, since these pumps are the pumps likely to be operated at minimum flow conditions during an accident.

Work for these pumps will be completed by October 28, 1988.

2.

Work for the remaining 11 pumps listed below will ba completed by January 28, 1989.

These pumps are not likely to be operated at minimum flow conditions during an accident.

Consequently, no immediate need to evaluate these pumps exists; These pumps are:

RHR holding pumps 10P-2A, 10P-2B l

RCIC pump 13-P1 Core Spray holding pumps 14P-2A, 14P-2B RHR Service Water pumps 10P-1A, 10P-lD, 10P-lC, 10P-lD l

Emergency Service Water pumps 46P-2A, 46P-2B

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i The previous discussions in conjunction with the abose actions i

and surveillance test results to date, adequately demonstrate

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j that the concerns of Bulletin 88-04 do not present a safety t

concern for the FitzPatrick plant.

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LJ NEW YORK POWER AUTHORITY JAMES A.

FITZ P ATRIC K NUCLEAR POWER PLANT SK-8804 7-7-88 RHR P LJ M P ARRANGEMENT

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