ML20079E668

License Amend Request 91-015 to License NPF-87,revising Centrifugal Charging Pump & Safety Injection Pump Flow Rate Acceptance Criteria in Surveillance 4.5.2.h,Paragraphs 1(a) & 2(a)

ML20079E668
Person / Time
Site:	Comanche Peak
Issue date:	10/01/1991
From:	William Cahill TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20079E669	List: ML20079E668 ML20079E671
References
TXX-91369, NUDOCS 9110070255
Download: ML20079E668 (48)

Text

Log # TXX-91369 e

File # 916 (3/4.5)

Ref. # 10CFR50.90 E E.

10CFR50.92

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1UELECTRIC October 1, 1991 NNNl$$,,',

U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C.

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SUBJECT:

COMANCHE PEAK STEAM ELECTRIC STATION (CPSES) - UNIT 1 DOCKET NO. 50-445 LICENSE AMENDMENT REQUEST 91-015 REVISED ECCS FLOW BALANCE CRITERIA Gentlemen:

Pursuant to 10CFR50.90, TU Electric hereby requests an amendment to the CPSES Unit 1 Operating License (NPF-87) by incorporating the enclosed changes into the CPSES Unit 1 Technical Specifications.

The proposed change involves revising the centrifugal charging pump and safety injection pump flow rate acceptance criteria as provided in surveillanc^

4.5.2.hparagraphs1)a)and2)a).

, provides a detailed description of the proposed change, the basis for the change, and TU Electric's determination that the proposed change does not involve a significant hazards consideration. provides a safety evaluation prepared by TU Electric using input, where appropriate, from Westinghouse. provides the affected Technical Specification pages, marked up to reflect the proposed changes.

TU Electric requests approval of the proposed amendment by November 8, 1991, with implementation prior to entering MODE 4 for Unit 1 cycle 2.

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TXX-91369 Page 2 of 2 c

- Should you have any questions in this matter, please contact Jimmy Seawright at (214) 812-4375.

Sincerely, f

/h William J. Cahill, Jr.

DRW/grp Attachment Enclosures c - Mr. R. D. Martin, Region IV Resident Inspectors, CPSES (2) i Mr. T. A. Bergman, NRR Mr. D. K. Lacker

' Bureau of Radiation Control Texas Department of Public Health 1100 West 49th Street Austin, Texas 78704

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% to TXX-91369 Page 1 of'1 UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION In the matter of Texas Utilities Electric Company Docket No. 50-445 (Comanche Peak Steam Electric Station, Unit 1) 6EFIDAVIT William J. Cahill, Jr. being duly sworn, hereby deposes and says that he is Group Vice President, Nuclear of TV Electric, that he is duly authorized to sign and file with the Nuclear Regulatory Commission this transmittal of License Amendment Request 91-015; that he is familiar with the content thereof; and that the matters set forth therein are true and cntrect to the best of his knowledge, informaticn and belief.

a WiiliamJ.Cahil/l/Jr.

Group Vice Presicent, Nuclear STATE OF TEXAS COUNTY OF SOMERVELL Subscribed and sworn to before me, a Notary Public, on this _lat day of october

, 1991, (Q,j$)

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March 16,1993 Notary Publit j

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.V ENCLOSURE 1 TO TXX-91369 SIGNIFICANT HAZARDS CONSIDERATION REVISED ECCS FLOW BALANCE CRITERIA i

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Enclosure'1?to TXX-91369 Page t of 4-3 SIGNIFICANT' HAZARDS CONSIDERATION

- PROPOSED CPSES UNIT 1 TECHNICAL SPECIFICATION CHANGES REVISED ECCS FLOW BALANCE CRITERIA

' Pursuant-to 10CFR50.92, TU Electric has evaluated the proposed amendment to the CPSES Unit 1 Technical Specifications and has determined that operation of the facility in accordance with the proposed amendment would not involve-significant hazards considerations.

In acco; dance with the three factor test of_10CFR50.92(c),implementationofthepr0posedchangeswouldnot: 1) involve a significant increase in-the probabiliti; or consequences of an accident previously evaluated; 2) create the possibility of a new or different kind of accident from any accident previously evaluated, or;-3) involve a significant reduction in__the margin of safety.

DESCRIPTION _OF PROPOSED CHANGE The proposed change wi11' revise the acceptance criteria provided in the Technical _Specificatiort for the ECCS pump flow balance test. _The purpose of

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this r'evision is to allow a throttle valve adjustment which assures the minimum required ECCS flow while preventing the ECCS pumps from exceeding runout limits. The minimum flov values presently included in the ?echnical Specifications are too high to ensure that runout limits will not be reached.

The specific surveillance of concern is 4.5.2.h, which covers the flow balance test requirements for the centrifugal charging pump lines, the safety injection pump lines and the residual heat removal (RHR) pump lines..The minimum flow values-for the' centrifugal charging pump-lines and the safety injection pump lines need-to be reduced.. Paragraph 1)a) provides a minimum flow value of 333 gpm for the-centrifugal pump lines. The value needs to be reduced to 245 gpm.

Paragraph 2)a)_provides a minimum flow value of 437.gpm for;the safety' injection pump lines. This value needs to be reduced to 400 gpm...Except-for changing these two numbers, the surveillance remains

unchanged.-

DETAILED DISCUSSION OF PROPOSED lECHNICAL SPECIFICATION = CHANGE The detailed evaluation of this change is provided in Enclosures 2.

This evaluation was prepared by TU Electric.using input, where appropriate -from

~ Westinghouse.

MGNIFICANT HAZARDS CONSIDERATION EVALUATION PEC 10CFR5 M 2 JTU, Electric hasievaluated the no significant hazards considerations involved with the proposed changes by focusing'on the three standards set forth in-10CFR30.92(c) as' discussed below:

'Does the proposed change:

(1)-

Inynive a significent increase in the probability or consequences of an

, accident previously evaluated?

The proposed change revises the minimum flow value of certain ECCS

-injection lines. Because the systems function as accident mitigation systems, adjustments in the operation of these systems will not increase

-the probability of an accident previously evaluated.

In addition, no a.,,w

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-s design, material or construction changes are included in this activity.

Thus, no changes have been proposed which affect the probability of an accident.

The primary accidents affected by the reduction in the minimum ECCS flow are the Loss of Coolant Accidents (LOCAs). Evaluations of the analyses of these events have demonstrated that the applicable event acceptance criterion for Peak Cladding Temperature (PCT) continue to be met.

The source term for the analyses of the radiological consequences of a LOCA is predicated on compliance with the PCT acceptance criterion.

Because the PCT acceptance criterion is satisfied, there is no effect on the radiological consequences.

(2)

Create the possibliity of a new or different kind of accident from any accident previously evaluated?

The proposed change does not modify any hardware, material or construction.

Although the flow limits for the ECCS injection lines are revised, no new failure modes are created for any components, systems or structures.

As such, no new accidents are created from any accident previously evaluated.

(3)

Involve a significant reduction in the margin of safety?

The proposed change impacts safety in two basic ways.

First, if the ECCS flow values remain as-is, it is postulated that the centrifugal charging pumps and the safety injection pumps could reach or exceed their runout limits. Although this situation was evaluated and it was concluded that these pumps would perform their safety function for all postulated accidents at CPSES, safety can be enhanced if these pumps are operated in a range that does not reach +.he runout limits.

Such an improvement in safety is the primary purpose of this proposed technical specification change.

Adjusting the opcrating range of these ECCS injection fluw lines results in the second basic impact on safety.

In many accident analyses, the assumed ECCS flow will be lower than previously postulated. Although the primary impact is on the LOCA analyses, all affected analyses were assessed.

The margin of. safety is the difference between the value of the regulated acceptance limit for a particular parameter and the failure value associated with that parameter. The primary parameter of interest affected by the rebalancing of.the ECCS is the PCT calculated in the LOCA analyses. Due to the ECCS rebalancing, the minimum ECCS flow delivered to the Reactor Coolant System during the injection mode of ECCS operation is reduced. As a result, the PCT due to LOCA increases.

However, evaluations of the LOCA analyses have been performed which demonstrate that the PCT acceptance limit, defined in 10CFR50.46, is not exceeded.

Furthermore, because the ECCS flow reduction does not affect the design, material, or construction of the fuel assemblies, there is no effect on the failure limit associated with the fuel.

Because neither the PCT acceptance limit value nor the associated failure value is changed, there is no effect on the margin of safety.

_ _ _ _ _ _ _ _ _ to TXX-91369 Page 4 of 4 Evaluations of the impact of the proposed change on these analyses have demonstrated that the associated acceptance limits are not exceeded.

Furthermore, TV Electric has determined that the reduction in the minimum ECCS flow surveillance criteria allcws the ECCS to be balanced such that the pump runout limits will not be exceeded in the recirculation mode. Therefore, the availability of the ECCS pumps during the post-LOCA, long-term recirculation mode of operation is enhanced.

Although the proposed change will result in higher PCT for some accident enalyses due to the reduced flow rates, the fact that all accidents continue to provide acceptable results and all parameters of concern continue to meet acceptance criteria when coupled with the clear improvanent in safety which results from not exceeding the pump runout limits, leads TU Electric to the conclusion that this proposed change does not involve a significant reduction in the margin of safety.

11GNIFICANT HAZARDS CONSIDERATION DETERMINATION Based on the above evaluations, TV Electric concludes that the activities associated with the above described changes satisfy the no significant hazards consideration standards of 10CFR50.9?(c) and, accordingly, a no significant hazards consideration finding is justified.

ENVIRONMENTAL EVALUAIJDti TU Electric has evaluated the proposed changes and has determined that the changes do not involve (i) a significant hazards consideration, (ii) a significant change in the types or significant increase in the amounts of ar.y effluents that may be released offsite, or (iii) a significant increase in individual or cumulative occupational radiation exposure. Accordingly, the proposed changes meet the eligibility criterion for categorical exclusion set forth in 10CFR51.22(c)(9). Therefore, pursuant to 10CFR51.22(b), ar.

environmental assessment of the proposed change is not required.

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4' ENCLOSURE 2 TO TXX-91369 SAFETY ANALYSIS u

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10 CFR 50.59 EVALUATION D. h Na 91-126 Rev Na 0

CPSES Unit I

Activity

Title:

Rebalancing the ECCS to prevent Charging /SI and HHSI pump runout during recirculation chase Summary:

Charging /SI and HMSI pump flows er.ceed the vendor's endorsed runout flow during recirculation phase l

Based upon the results of this evaluation, implementation of the proposed activity:

l X

Does not involve an Unreviewed Safety Question.

Involves an Unreviewed Safety Question.

X Requires an amendment to the Technical Specifications.

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WyM(pv Eiv" = Walter Boaturi Date 7.2.7/ 9/

~4A M CL-v2-, /s i 10 CFR 50.59 RevievTer whTe G. Choe Date O I 079-9hcM/

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SORC Chairman Date STA 707 2 Rev. No.4 Page 1 of 3

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10 CFR 50.59 EVALUATION Evaluatxr1Na 91-126 lb.Na 0

CPSESUnit I

m_

NOTE:

A written response providing the basis for the answer to each line item in parts I,11.111, and IV below must accompany this form.

I.

BACKGROUND INFORMATION 1.

Describe the activity and explain why the activity is being proposed.

Attached 2.

Identify the structures, systems, or components and/or system parameters that could be affected by implementation of the activity.

Attached 3.

Identify the credible potential failure modes for the affected structuie. system, or component, that could be introduced by implementation of the activity.

Attached 4.

List the documents from which information was taken to complete this evaluation.

Attached IL EFFECT ON ACCIDENTS AND MALFUNCTIONS EVALUATED IN THE LICENSING BASIS DOCUMENTS 1.

List t'ne accidents and malfunctions of equipment important to safety described in the Licensing Basis Documents which involve structures, systems, or components and/or system parameters described in 1.2 that could be afTected by implementation of the activity (refer to FSAR Chapter 15 analyses and the Event Classification and Identi6 cation Section of the10CFR50.59 Review Guide).

Attached 2.

Explain how and why implementation of the proposed activity could or could not affect the radiological consequences cf each accident listed in 11.1.

Attached 3.

List the licensing basis accidents identified in 11.1 for which the failure modes identified in 1.3 could be the initiating event.

Explam,ahhedow and why implementation of this activity will or will not affect the probability Att 4.

of occurrence of the accidents listed in 11.3.

Attaahed 5.

For each of the structures, systems, or components listed in 1.2, which can afTect the events described in 11.1 explain how and why the proposed activity will or will not afTect the probability of failure of the structure, system, or component to perfomt its safety

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function (s).

Attached 6.

Explain how and why implementation of the proposed activity could or could not affect the radiological consequences of each equipment malfunction indentified in 11.5.

Attached III. POTENTIAL FOR CRJATION OF A NEW TYPE OF UNANALY2ED EVENT 1.

Compare the accident analyses listed in 11.1 to the potential failures described in 1.3, and explain how and why the failures identified in 1.3 could or could not create the possibility of an accident different from any accident evaluated in the licensing basis documents.

Attached 2.

Compare the credible potential failures described in 1.3 with the equipment malfunctions described in II.1, and explain how and why the failures identified in 1.3 could or could not create the possibility of a malfunction of equipment important to safety different from any evaluateo in the Licensing Basis Documents.

Attached Rev. No. 4 Page 2 of 3

10 CPR 50.59 EVALUATIQS Evalua:mn No.91-126 gey,go, O

CPSES Unit I

IV.

IMPACT ON TIIE M3RGIN OF SAFID' 1.

Identify the Technical Speci6 cations associated with the systems, structures, components, and/or parameters listed in 1.2 and brie 6y explain the basis for each Technical 3peci6 cation.

Attached 2.

For each Technical Specification discussed in IV.1, identify the acceptance limit associated with the basis for the Technical Speci6 cation and the corr sponding failure r

Attached 3.

Explain how and why implementation of the proposed activity will or will not afTect the acceptance limit (s) and the failure values identified in IV.2.

Attached 4.

Itased on the explanation in IV.3, explain how and why implementation of the proposed l

activity will or will not aiTeet the margin (s) of safety associated with the Technical Specification (s) listed in IV.I.

l Attached V.

EVALUATION

SUMMARY

j NOTE: If the answer to any of the following questions is 'TES", then the proposed activity involves an unreviewed safety questien.

l YES NO 1.

Willimplementation of the proposed activity increase the radiological consequences of a licensing basis accident (refer to 11.2)?

X 2.

Will implementation of the proposed activity increase the X

probability of a licensing basis accident (refer to 11.4)?

3.

Willimplementation of the proposed activity increase the probability of a malfunction of equipment important to safety previously evalaated in the Licensing Basis X

Documents (refer to 11.5)?

1 4.

Willimplementation of the proposed activity increase the radiological consequences of a malfunction of equipment i

l' important to safety previously evaluated in the Licensing X

l Basis Documents (refer to II.6)?

L 5.

Willimpicmentation of the proposed activity create the l

possibility for an accident different from any already evaluated in the Licensing Basis Document (refer to III.1)?

X,_,,,

6.

Willimplementation of the proposed activity create the possibility of a malfunction of equipment important to safety difTerent from any already evaluated in the Licensing Basis Documents (refer to III.2)?

X 7.

Willimplementation of the proposed activity decrease the margin of safety as defined in the basis for any X

Technical Specification (refer to IV.3)?

STA 707 2 Rev. No. 4 Page 3 of 3 l

SE 91-126 I. BACKGROUND INFORMATION 1.

Description of the Proposed Activity and Itf Exnocted Effects The proposed activity is the rebalancing of the ECCS in order to prevent the runout of the Charging /SI (CCPs) and High Head Safety Injection (HHSI) pumps during the recirculation phase of ECCS operation.

As a result of the robalancing of the ECCS, the throttle valves on each of the safety injection branch lines from the discharges of the CCPs and the HHSI pumps, as well as the RCP seal injection throttle valves, will be repositioned.

The total flow delivered to the RCS during the injection phase (ir.cluding the RCP seal injection flow) will be reduced from the current values.

To implement this activity, certain system engineering and operational performance tests will require revision.

Further, because the ECCS pump flow in the injection phase will be reduced, l

Technical Specification 4.5.2.h must also be revised.

A Technical l

Specification change request is required to support this change.

The ECCS flow rebalancing will be performed la Mode 6.

Upon reuurning to operation, at least one CCP is required to be OPERABLE for safety injection for entry to Mode 4, where OPERABLE is defined by Technical Specification 4.5.2.

Further, the HHSI pumps-are l

required by Technical Specification 3.5.2 to be OPERABLE for entry to Mode 3 operations.

Again, OPERABLE is defined by Technical L

Specification 4.5.2.

Thus, for the purposes of this safety evaluation, it is assumed that the change to Technical Specification 4.5.2.h has been approved prior to entry to Mode 4 l

-following the ECCS rebalancing.

l The current Comanche Peak Unit 1 Technical Specification 4.5.2.h paragraphs 1)aj and 2)a) provide the surveillance requirements for the Charging /SI and HHSI pump flow balance test acceptance criteria l

during shutdown.

Currently, for the flow rate through Charging /SI l

pump lines with a single pump running, the sum of the injection i

line flow rates, excluding the highest flow rate, must be greater l

than or equal to 333 gpm.

The revised acceptance criteria will l

reduce this flow rate to 245 gpm.

For the flow rate through HHSI l

pump-lines with a single pump running, the sum of the injection l

line flow rates, excluding tan highest flow rate, must be greater l

than or equal to 437 gpm.

P~w revision to the above acceptance l

criteria will reduce this r_ - rate to 400 gpm.

Compliance with j

the revised acceptance criteria will prevent pump runout,-

cavitation, and loss of function (Ref. (3)).

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l SE 91-126 2.

Affected Structures. Systems, or comoonents and/or System Parameters Implementation of the revised acceptance criteria for Charging /SI h

and the HHSI pump flow balance test repositions the ECCS throttle valves.

The throttling of the ECCS valves results in the reduction

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of the Charging /SI and HHSI pump flow into-the ccid leg of the RCS,'

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-during *be injection phase.

Also, it requires the repositioning of #/If'

/l the RCP seal injection throttle valves.

3.

Identification of Credible Potential Failure Modes The rebalancing of the ECCS as di-sed in Section I.1 of this evaluation does not cause any cre, failure modes.

4.

Referen j

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1. WPT-1-34M, "SI Flow Balance Criteria", Dated: September -29, 1991{

2. W PT-13 9 61, "ECCS Pump Runout", Dated: September 25, 1991

3. W PT-13 9 63, "CPSES Units 1 & 2 Safety Evaluation for Reduced ECCS Flow to Prevent Charging /SI and HHSI Pump Runout During Recirculation (SECL-91-367)", Dated: September 25, 1991

4. WPT-13966, " Reduced ECCS Flows - Impact on ainment Mass &

Energy", Dated September 27,

5. W PT-12 591, "RCP Seal Injection Line Hydr

, Resistance",

Dated: April 4, 1990 6.

RXE-TA-CP1/O-017, Rev.

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" Licensing Basis Steam Generator Tube Rupture Analysis" M </u$ 1/n/

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II. EFFECTS ON ACCIDENTS AND MALFUNCTIONS EVALUATED IN THE LICENSING BASIS DOCUMENTS 1.

Identify Accidents Imoacted by the Imolementation of This Activity The proposed revision to the ECCS balancing criteria reduces the ECCS flows delivered to the RCS during the injection and recirculation phases of safety injection.

Therefore, all postulated accident scenarios in Chapters 3,-6 & 15 of the CPSES Unit 1 FSAR in which the ECCS actuation is credited may be affected..

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SE 91-126

2. Impagt on Radiolocical Consecuences of Accidento Lisj;_qd_lLl LOCA Analysis Evaluation Westinghouse has recalculated the ECCS flows based on the proposed flow rebalancing.

These flows are listed in Reference (3)

(provided in Attachment 1) and are used to assess the offect of the proposed revision on the accident analyses of record.

a.

LOCA Analysqs (FSAR Chapter 15,6.5)

The evaluation provided in Attachment 1 (Ref. [3]) determines the effect of the Charging /SI and HHSI flow reduction on the Large and Small Break LOCA Analyses of record for CPSES Unit 1.

Based on the new ECCS flows calculated by Westinghouse, a PCT penalty of 64.85 F for the small Break LOCA and no PCT penalty for the Large Break LOCA were assessed.

In both cases, the final calculated PCT remains below the limit of 2200 F and complies with the requirements of 10CFR50.46.

b.

Containment Mass and Encrav Release Analysis (FSAR Chanter 6.2)

An ovaluation (Ref.-[4), provided in Attachment 2) of the effect of the reduction in ECCS flow on containment mass and energy releases following a postulated LOCA has been performed.

This evaluation demonstrated no adverse impact on the analysis for the CPSES Unit 1 containment mass and energy releases analysis.

c.

Steam Generator Tube Ruoture (SGTR) Analysis (FSAR Chanter, 15.6.3)

As described in Reference [1], it was assumed that the RCP seal injection flow would be limited to 40 gpm with a differential pressure of 130 psid between the charging hender (PI-120) and the pressurizer.- This information supersedes the flow balance critoria described in Reference (5), wherein it was assumed that the RCP seal injection flow would be limited to 40 gpm with a differential pressure of 110-psid.

Thus, it is inferred that, as a. result of the revised flow balancing, the hydraulic resistance from the charging header to the RCS through the RCP seal injection flow path is greater.

Furthermore, as described

?.n Reference (4], the maximum ECCS performance characteristics are not increased as a result of this modification.

Therefore, the total flow delivered to the RCS during the injection mode (including RCP seal injection flow) will be reduced from the current assumptions.

In the analysis of the steam generator tube rupture (SGTR) event (Ref. [6]), the maximum safety injection flow is assumed in order to increase the primary-to-secondary break flow throughout the event.

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SE 91-126 A reduction in the quantity of safety injection fluid delivered to the RCS would reduce the severity of the calculated consequences of this event.

Hence, tl.e analysis of the SGTR event is not adversely affected by this activity, d.

LOCA-Related Analyses The safoty evaluation of Reference (3) provides the assessment of the effect of ECCS flow reduction on. Blowdown Reactor Vessel and Loop Forces (JSAR Chapter 3.9), the Post-LOCA Long-term Core Cooling (FSAR Chapter 15.6.5), and the Hot Leg Switchover of the ECCS to Prevent Potential Doron Precipitation (FSAR Chapter 6.3).

The ECCS flow reduction does not alter the conclusions of the calculations performed for the above analyses of record.

Egn-LDCA Analysis Evaluation The non-LOCA events which are potentially affected by the reduction in Charging /SI and HHSI flow are ones which use the minimum ECCS flow to mitigate the consequences of the event.

The affected events are secondary side breaks which are analyzed to determine the primary side response or mass and energy released.

The affected events are:

a. Mass & Energy Release Inside Containment from a Steamline Break (FSAR Chapter 6.2.1.4)

b. Mass & Energy Release Outside Containment from a Steamline Break

c. Steamline Break - Core Responsa (FSAR Chapter 15.1.4 & 15.1.5) d.

Feedline Break (FSAR Chapter 15.2.8)

The effect of the Charging /SI and HHSI flow reduction on the 1

non-LOCA licensing basis analyses of record has been evaluated.

This evaluation is documented in Reference (3) and is included in and indicates that the conclusions of the FSAR remain valid.

In addition, the mass and energy releases calculated for both inside and outside containment breaks remain 1alid.

The principal consequence of tne events disqussed in FSAR Chapters 3,

6, and 15 is the offsite doses which must be within the limits of 10CFR100.

Westinghouse has determined, by evaluation summarized in Reference (3), that the proposed reduction in the Charging /SI and HHSI pump flows does not prevent the ECCS from mitigating the consequences of the events analyzed in the FSAR.

Therefore, the conclusions of the analysis of these events remain valid and there is no jncrease in the radiological consequences.

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SE 93-126 3.

Failure Modes in I.3 Which Could De Initiatina Events for Licensina D. asis Accidents in II.1 No credible potential failure modes were identified in 1.3 based on the proposed ECCS rebalancing.

Therefore, no accidents could be initiated by the reduction in ECCS flow.

4. Effect of the Activity on Probability of Occurence of the Accidents Iggntified ir II.3 No accidents were identified in II.3 which could be initiated by the implementation of the proposed activity.

5.

Effect of the Activity on Probability of Failure of the Structure.

System. or ConDonent to Perform its Safety Fungtipn As mentioned in I.2, the proposed activity results in the repositioning of the ECCS throttle valves in shutdown mode which reduces the Charging /SI and HHSI pump flow rates.

This ECCS flow reduction does not challenge the operability and integrity of the ECCS and does not result in a condition where the design, material, and applicable construction standards are altered.

Therefore, the probability of failure of the ECCS in performing its safety

' function in mitigating the consequences of the accidents identified in II.1 is not increased.

6.

E1[gg&_cn Radioloaical Conseauences of Each Eauinment Malfunction Identified-in II.5 No equipment malfunction was identified in II.S.

III. POTENTIAL FOR CREATION OF A NEW TYPE OF UNANALYZED EVENT 1.

Possibility of Creation of a New Accident Different from any_

Accident Evaluated in Licensina Basis Documentq No new type of accidents is created by the proposed revision to Technical Specification.

This activity results in the reduction of the-ECCS pump flow characteristics.

i 2.

Possibility of Malfunction of Eauioment Imoortant to Safctv Different from any Evaluated in the Licensina Basis Documents t

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-The proposed activity results in the repositioning of the ECCS i

throttle valves to reduce the ECCS pump flow rates.

The repositioning of these valves does not result in the malfunction of any equipment inportant to safety different from those evaluated in licensing basis documents. l

SE 91-126 IV. IMPACT ON MARGIN OF SAFETY 1.

Identify the Technical Sppcifications Associated with the Systemst_

Components, and/or Parametqrs Listed in I.2 Technical Specification 4.5.2.h paragraphs 1)a) and 2)a) provide the surveillance requirements for the Charging /SI and HHSI pump flow balance test acceptance criteria during shutdown mode.

Compliance with this Technical Specification prevents ECCS pump cavitation, runout, and potential loss of function and assures the ECCS pump flow characteristics during the injection pnase are consistent with the assumptions used in the accident analyses.

2 Identify the Accentance Limit Associated with the Basis for Igghpical Snecification__and the Correspondino Failure Value The OPERABILITY of two independent ECCS subsystems ensures that sufficient emergency core cooling capability will be available in the event of a LOCA assuming the loss of one subsystem through any single failure consideration.

Either subsystem operating in conjunction with the accumulators is capable of supplying sufficient core cooling to limit the peak cladding temperatures within the regulated limit of 2200 F for all postulated break sizes ranging from the double ended break of the largest RCS cold leg pipe downward.

In addition, each ECCS subsystem provides long-term core cooling capability in the recirculation phase during the accident recovery period.

The surveil tance requirements provided to ensure OPERABILITY of each component ensures that at a minimum, the assumptions used in the safety analyses are met and that subsystem OPERABILITY is maintained.

Surveillance requirements for throttle valve position stops and flow balance testing provide assurance that proper ECCS flows will be maintained in the event of a LOCA.

Maintenance of proper flow resistance and pressure drop in the piping system to each injection point is necessary to: (1) prevent total pump flow from exceeding runout conditions when the system is in its minimum resistance configuration, (L) prc ide the proper flow split between injection peints in accordance w) i the assumptionn used in the ECCS-LOCA analyses, and (3) provide an acceptable level of total ECCS flow to all injection points equal to or above that assumed in the ECCS-LOCA analyses.

Again, the acceptance limit associated with the basis of the surveillance requirements is the compliance with the 2200 F peak cladding temperature acceptance criterion.

In addition, the ECCS is used to mitigate the consequences of come non-LOCA events.

For these events (particularly the main steamline breaks and main feedline breaks), the regulated event-specific acceptance criteria of interest are:

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i SE 91-126

a. No DNB is predicted for the main steamline break event; and,

b. No boiling in the hot legs occur.

Both events are insensit;ve to actual ECCS injection flows.

The failure values associated with these limita are a function of the fuel mechanical design, i

3.

Effect of the_ProDosed Activity on Accentance Limits and Failura i

Values Idgntified in IV.2

)

The implementation of the proposed activity will not affect the acceptance limits or the failure values for LOCA and non-LOCA events.

The calculated PCT for a LOCA event is shown to be below the limit 0

of-10CFR50.46 (2200 F).

The proposed activity does not adversely affect the DNB limit and does not exceed the limit Lor-hot leg boiling.

Further, the failure valuca associated w'.th fuel mechanical design are unaffected by this activity.

The revised i

acceptance limit will prevent the pump cavitation and runout during l

hot and cold-leg recirculation.

4.

Effect of the Proposed Activity on Marcin of Safety Associated with the Technical Soecification in IV.1 Because the calculated PCT meets the requirements of 10CFR50.46 of 2200 F and there is no change in the failure values, the margin of safety as defined in the basis to the LOCA peaking factor Technical Specification would not be reduced.

The margin of safety in non-LOCA accidents is not reduced due to a reduction-in Charging /SI and HHSI pump flows.

The acceptance 1

criteria of minimum DNBR and maximum primary and secondary pressures remain valid.

Therefore,_the same margin of safety exits to design failure point or system limitation.

V.' EVALUATION

SUMMARY

Based on the above evaluation (Section I through IV), the proposed activity does not increase the radiological consequences of a licensing basis accident or the probability of a licensing accident.

This_ activity does not increase the probability of a malfunction of equipment important to safety previously evaluated in the licensing. basis documents or the related probability of an

-increase in-the radiological consequences.

The implementation of the proposed activity does not create the possibility for an accident or a ualfunction of equipment important to safety l

different from any already evaluated in licensing basis document.

Finally, the implementation of the proposed activity does not decresse the margin of safety as defined in the basis for any Technical Specification.

.. 1

SE 91-126 i

ATTACHMENT 1 WPT-13963 (SECL-91-367)

CPSES Units 1 & 2 Safety Evaluation for Reduced ECCS Flow to Prevent Charging /SI and HHSI Pump Runout During Recirculation E

, y-

.:,,,c,

/

WPT 13963 ET.NSL-OPL 11-91-561 Westinghouse Energy Systems g3y g

Electric Corporation.,

September 25, 1991 Mr. W. J. Cahill, Jr., Executive Vice President S.O. No.

TBX 4708 Nuclear Engineering & Operations TV Electric Company P.O. Box 1002 Ref; 1) S 4 318 Glen Rose, Texas 76043

2) WPT-13961 TU ELECTRif COMPANY COMANCHE PEAK STEAM ELECTRIC STATION COMANCHE PEAK UNITS l

"AFETY EVALUATION FOR REDUCED ECCS FLOW TO PREVENT CFARGLNJ/_S1.ND H451 PUMP RUNOUT DURING RECIRCU1.eTlQH T

Dear Mr. Cahill:

Per your request of the above Reference 1, and in support of the concern identified by Westinghouse in Reference 2, please find attached the subject Safety Evaluation.

A Westinghouse Potential item (PI 91 011) documented an issue in which a potential exists for Charging / Safety injection (CH/SI) and High Head Safety Injection (HHSI) pump flow to exceed the vendor's endorsed runout flow during the recirculation phase.

As a result, TV Electric has decided to throttle back the CH/SI and HHSI pumps during the injection phase to assure that these pumps will not exceed the recommendea runout flow during the recirculation phases of a LOCA.

This modification will involve a change to the Technical Specification surveillance requirements.

The attached Safety Evaluation is submitted to provide TU Electric with the documentation necessary to support the Technical Specificaticn change.

Further, the evaluation supports the Westinghouse conclusion that the modification does not represent a potential unreviewed safety question as defined in 10 CFR 50.59.

If there are any questions on the above or attached, please contact Roy Owoe on 412-374-4037.

This letter closes Westinghouse open item No. 10158 2.

Very truly yours, R. H. Owoc J. L. Vota, Manager Comanche Peak Projects 1

~

WPT 13963 ET NSL-0PL.II 91-561 cc:

W. J. Cahill, Jr.

IL, lA J. W. Beck IL, IA C. 8. Hartong it 1A A. 8. Scott IL, lA CCS ll, lA, lAR J.- W. Muf fett IL, lA J. J. Kelley ll, lA T. Elkins ll, IA S.-C. Wood IL, IA VETIP Coordinator IL, lA H. D. Bruner ll, lA

-C.-8. Hogg IL, IA M. R. Blevins ll. lA S. S. Lo

-IL, IA

_D. Walling IL, lA D. Woodlan IL, IA C. W. Rau (Bechtel Site IL,.lA G. Ashley (Unit 2 On1 )

IL R.-Jackson (Unit 2 On1 )

IL, IA S. S. Chitnis (Unit 2 Only)

IL

.P. Raysirear (Unit 2 Only)

IL S. Lakdawala-- (Unit 2 Only)

IL, IA R. Braddy.

(Unit 2Only)

IL R.-Withrow (Unit 2Only)

IL J. Meyer ll, IA l

l l

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ET-NSL-0PL-II 91 561 J.L.Vota(WECW232) 2L, IA P. F. Mickey (WiCW 232)

IL D. Wieland_ (TBX/TCX Site Mgr.)

2L, 2A H. C. Calton (TBX/TCX Site Mgr.)

ll, IA C. Benton (WECW 232)

IL, IA S. J. Hyde (WECW-232) ll, I A M.A.Olson(WECW-232)

IL S. D. Rupprecht (WECE 4170)

IL R. H. Owoc (WECE-413) ll, lA R. M. Waters (TBX/TCX Site) ll, IA L. Gum.

(WECE416OPLFile) ll, lA H. Gutzman (TBX Site Mgr.)

IL, IA 1

L. F. Dougherty (TCXSite) ll, IA

-T. A. Miller _(WECE-410) lL, IA T. F. Timons (WECE-4298)

IL, IA M. P. Osborne (WECE-423A) ll, IA C. M, Thompson (WECE 429) ll, IA R. K. Nydes (WECE-423)

IL, lA S. Swantner (WECE 472)_

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SECL-91-367 CustomerReferenceNo(s).

I N / A __ _

Westinghouse Reference No(s).

S # 318 -

WESTINGHOUSE NUCLEAR SAFETY EVALUATION CilECK LIST

1) NUCLEAR PLANT (S)

COMARCHE PEAK UNITS 1 AND 2

2) CHECK LIST APPLICABLE TO REDUCED ECCS FLOV__T0_ PREVENT CHARGINGISI AND (Subject of Change)

MiSI PUMP RUNOUT DURING RECIRCULATION AND RESUlilNG TECHNICAL SPECIFICATION MODIFICATIONS

3) The written safety evaluation of the revised procedure, design change, or modification required by 10 CFR 50.59 has been prepared to the extent required and is attached.

If a safety evaluation is not required or is incomplete for any reason, explain on Page 2.

Parts A and B of this Safety Evaluation Check List are to be completed only on the basis of the safety evaluation performed.

CHECK LIST PART A - 10 CFR 50.59(a)(1) 3.1)

Yes.J._,No A change to the plant as described in the FSAR?

3.2) Yes _ No X A change to procedures as described in the FSAR?

3.3) Yes_ No_L A test or experiment not described in the FSAR7 3.4) Yes. L No A change to the plant technical specifications?

(See Note on Page 2)

4) CHECK LIST PART B - 10 CFR 50.59(a)(2) (Justification for Part B answers must be included on Page 2.]

4.1) Yes _ No X Will the probability of an accident previously evaluated in the FSAR be increased?

4.2) Yes_ No L Will the consequences of an accident previously evaluated in the FSAR be increased?

4.3} Yes No X May the possibility of an accident which is different than any already evaluated in the FSAR be created?

4.4)

'as _ No X Will the probability of a malfunction of equipment important to safety previously evaluated in the FSAR be increased?

4.5) Yes_ No X Will the consequences of a malfunction of equipment important to safety previously evaluated in the FSAR be increased?

4.6) Yes No.JL May the possibility of a malfunction of equipment important to safety different than any already evaluated in the FSAR be created?

4.7) Yes No X Will the margin of safety as defined in the bases to any technical specification be reduced?

1 Page 1 of 25

SECL-91-367 NOTESt If the ansiefs to any of the above questions are unknown, indicate under

5) REKARKS and explain below.

If the answer to cuestion 3.4) of Part A or any of the questions in Part B cannot be answerec in the negative, based on the written safety evaluation, the change review requires an application for license amendment as stated in 10 CFR 50.59(c) and must be submitted to the NRC purssant to 10 CFR 50.90.

5) REKARKS The following sumarizes the justification based upon the written safety evaluation (1) answers given in Part A 3.4) and Part B of this Safety Evaluation Check List:

SEE ATTACHED (1) Reference to document (s) containing written safety evaluation:

91-367-A. 91-367-D. 91-367-E FOR FSAR UPDATE Section:

Pages:

Tables:_

Figures:

Reason for/ Description of Change:

NO FSAR REVISION SAFETY EVALUATION APPROVAL LADDER Prepared by (Nuclear Safety): R. H. Owoc.

A Date:

f/

A Date:

$) 9/

Reviewad by (Nuclear Safety): A. M. Sicari G

j Nuclear Safety Group Manager: M. J. Proviano Date:

f Page 2 of 25

SECL-91-367 COMANCHE PEAX STEAM ELECTRIC STATIONS UNITS NO. 1 & 2 SAFETY EVALUATION FOR REDUCED ECCS FLOW TO PREVERT CHARGING /SI AND HHSI PUMP RUNOUT DURING RECIRCULATION 1.0 SACKGROUND INFORMAIION AND

SUMMARY

Westinghouse has identified a concern for Charging /SI and HHSI pump flow to exceed the vendors endorsed runout flow during recirculation via Reference 11.

During the recirculation phase, the Charging /S! and HHSI pumps receive their suction from the RHR pumps. The RHR pumps actually boost these high pressure pumps, pushing these pumps beyond the vendors endorsed runout flows with the potential to cavitate the pumps, potentially leading to pump failure. As a result, TU Electric (TVE) has decided to throttle back the Charging /SI and HHSI pumps during the injection phase to assure that these pumps will not exceed the pump vendor's recommended runout flow during the 'ecirculation )hases of a LOCA. The modification to prevent pump runout will involve a c1ange to the Technical Specification surveillance requirements. The intent of this i

evaluation is to provide TU Electric with the documentation necessary to support this change.

l The following evaluation supports the Westinghouse conclusion that-the Technical Specification modifications (mark-ups attached) do not represent.

potential unreviewed safety question as defined in 10 CFR 50.59, The scope of this evaluation is limited to the following functional areas which L

are provided a: separate sections:

Section 2.0, The safety significance of the proposed modification to the ECCS Technical Specification surveillance requirement 4.5.2.h, with respect to system and pump operability.

Section 3.0, The effect of the reduced Charging /SI and HHSI flow rates on both the large and small break LOCA calculation for both Comanche Peak units.

Section 4.0, The safety significance of the proposed modification on the non-LOCA events which are potentially affected by the centrifugal charging pump (CCP) degradation.

Please note that the following areas were not evaluated as part of this effort as they are beyond the Westinghouse contractual scope:

Steam Generator Tube Rupture Analysis Probabilistic Risk Assessment Setpoints used in the Emergency Operating Procedures (EOPs)

It is important to point out that although not in Westinghouse scope, the above areas were reviewed for potential impact. Westinghouse suggests that these areas be considered by TU Electric for inclusion into your final "No Page 3 of 25

SECL-91-367 Signif 8 ant Hazards Determination." Specifically, the reduced $1 flows (Table 4 of kPT-13927) may have an impact en RCS subcooling setpoints used in the 50Ps.

2.0 LCCS TECHNICAL SpfCIFIG110N SURVEILLANCE RE001RUQTS H00l_FICATION 2.1 LICENSING BAS 15 Title 10 of the Code of Federal Regulations, Part 50, Section 59 (10 CFR 50.59) allows the holder of a license, cuthorizing operation of a nuclear power facility, the capacity to investigate and disposition a change to the normal plant configuration Prior Nuclear Regulatory Comission (HRC) approval is not reouired to implem et a change provided that the propose change does not involve an uterovieweri safety question or result in a c. r.6 to the plant technical saecificAtions.

It is the obligation of the.u ansre to maintain a o

record of t'.e changes or modifications to the faci \\ d;,, tu the extent that such 5

changes impact the Final Safety Analysis Report (FSAR). The code further stipulates that these records shall include a written safety evaluation that provides the basis for the determination that the change does not itvolve an unroviewed safety question.

It is the purpose of this document to support the requirencent for a written saftty evaluation. The license holder who desires a change in their Technical Sperifications is required to submit an application for a licet;se amendment pursuant to 10 CFR 50.90.

This 50.90 license amendment application is outside the scope of responsibility of Westinghouse but is tupported by t5is document.

2.2 EVALUATION The ECCS,s designad to cool the reactor core, as well as to provide additional shutdewn ',apability following LOCA conditions. The ECCS is operated in two distinct modes:

injection and recirculation. During the injection mode, following a loss of reactor coolant, the Residual Heat Removal System (RHRS) and !ritemediate Head Scfsty injection (IHSI) pumps deliver flow to the Reactor N

Coolant System (RCS) via the accumulator injection lines. The Charging / Safety injection (CH/SI) pumps deliver through the boron injection tank directly into the RCS cold lags. During the recirculaticn mode, the RHRS pam;s take suction from the containwnt sump. The CH/SI and HHSI pumps receive suction flow f rom the RHRS pumps or

circulation pumps during this recirculation mode.

Prior to initial plant startup and plant startup following any ECCS modification, Plant Operations is required to perform tests to assure adequate 5

system performance. These tests assure adequate Safety Injection (SI) performance, which includes total pump flow, branch line flow balance, or verification of system flowrata distribution. Technical Specification survelliance requirement 4.5.2.h defines the balance test acceptance criteria.

This specification provides a requirement for the minimum total flow through all 51 branch lines, excivding the highest flow line. The highest flow IIne is assumed to have ruptured and will spilt its flew into the containment or spill its flow against RCS backpressure, depending upon the postulated size and Page 4 of 25

)

i

SECL-91-367 lo ation of the pipe break.

In addition, the specification provides a requirement for the maximum flowrate to preclude pump runout.

'h The aforementioned Westinghouse Information Letter (Reference 11) addresses an l

issue regar6 ng runost imits for the ECCS pumps. As part of the assessment of the runout issue, the pump vendor and Wettinghouse developed guideHnes for determinirg the amount of margin available for the pumps, which may be more limiting than the assumptions used in past runout margin assessments.

Test data that was recorded during the Comanche Peak Unit I start-up indicated that tne Charging / Safety Injection (CH/51) pumps and the High Head Safety injection (HHSI) pumps may operate at runout flows that exceed the maximum limits I

established in the generic limits issued in the Westinghouse Information Letter.

The Comanche Peak Unit 1 startup test data indicates that during the recirculatbn mode of operation, the CH/SI pumps 01 and 02 would operate at a flow rate of $92 gpm and SSO gpm, respectively, which exceeds the generic runout limit of $80 gpn.

In addition, the HHS! pumps 01 and 02 would operate l

at a flow rate of 685 gpm and 695 gpm, respectively, which exceeds the generic runout limit of 673 spm.

Thes0 conditions could lead ta cavitation and potentially loss of function.

Based on Westinghouse estimati the Comanche Peak Unit 1 CH/S! pumps will cavitate at RCS pressures below 2.)0 osig and the HHS! will cavitate when aligned to the RCS hot legs at RCS pressures less than 250 psig.

Further, an assessesnt of pump operability was performed by Westinghouse and reviewed by Dresser / Pacific Pumps, which indicated that the CH/S! pumps could pes form their function for at least three odys and the HHS! pumps could perfora their functior. for at least one month. Operability beyond these limited periods could not be confirmed. These conditions were considered in an evaluation of the various break locations and break sizes.

In sll cases, adequate core cooling was shown during the recirculation phases such that the calculated PCT would remain below the values documented in the Comanche Peak Unit 1 FSAR.

Further, adequate hot leg rtetrculation flows exist to praent high boric acid concentrations resulting in boron precipitation. Based on these findings, a Justification for Continued Operation (Reference 11) was provided to address the recirculati n mode runout concerns. TV Electric has subsequently proposed

nodifying the Technical Specification limits to prevent pump tunout beyond the pump vendor's generic ru7ut limit during hcs and cold leg recirculation.

The current Technical S *cificetion surveillance requirement 4.5.2.h requires flow balancs testing, dring shutdown, following co.apletien of modifications to the ECCS subsystems th t alter the subsystems flow characteristics, to verify that:

1)

For centrifugal char,ing pump lines, with a single pump running:

a) The sum of the irdestion line flowrates, excluding the highest flowrate, is greater than or equal to 333 gpm, and b) The total pump flowrate is less than or equal to 560 gpm.

I Page 5 of 25

5ECL-91-367 2)

For safety injection pump lines, with a single pump running:

I a) The sum of the injection line flowrates, excluding the highest flowrate, is greater than or equal to 437 gpm, and b)

The total pump flowrato is less than or equal to 675 gpm.

As stated in the Basis of the ECCS Technical S>ecifications, the surveillance requireiaents ensure that proper 51 flows will >e maintained in the event of a i.

LOCA.

The LOCA analysis assumes the most limiting conditions and, therefore.

envelopes all other potential accidents. Maintenance _of proper flow resistance and pressure drop in the piping system to each injection point is necessary to:

i 1) prevent total pump flow from eAceeding runout conditions when the systr.,a is in-its minimum resistance configuration; 2) provide the proper flow split between injection points in accordance with the assumptions used in the ECCS LOCA analyses; and 3) provide an acceptable. level of total ECCS flow to all injection points equal to or above the flow assumed in the ECCS-LOCA analyses.

Note, the Technical Specification surveillance requirements represent the

" actual", not " indicated", flowrates. The " actual

• flowrates are used to model

-the ECCS during performance analysis.

Westinghouse has completed the ECCS perfomance evaluation for Comanche Peak Units l'and 2, to rethrottle the ECCS to preclea runout during hot and cold leg recirculation.

The ECCS performance evaluation included conservatisms to address flow measurement insecuracies.

Based un the engineering evaluation, it was detemined that Technical Specification surveillance requirement 4.5.2.h can be revised for both units by reducing the minimum flow of the three branch 1ines for the CH/S! subsystem from 333 gpm down to 245 gpm and from 437 gpm down to 400 gpm for the IHS!

subsystem. These reduced flows represent ' indicated

• flows since conservatisms have been added to these flows to address flow measuroment inaccuracies.

These-indicated flows will bound the use of actual flows.

E 3.0 EFFECT OF THE REDUCED CHARCING SI AND HHSI FLOW RATES ON THE LARGE ANO-P"'IJREAK LOCA ANALYSES 3.1 LICENSING BASIS The following documents and information were used as a basis for the Units 1 and 2 LOCA and LOCA-related Evaluations:

Page 6 of 25

$[CL-91-367 Comanche Peak Electric Station Updated F5AR - Section 15.6.5 10 CFR 50.46; " Acceptance Criteria for Emergency Core Cooling Systems for Light Water Nuclear Power Reactors' CPSES-1LARGEB.R(&K51 FLOWS CHG PUMPS (1)

HHSl(1)

RHR(1)

TOTAL (LBM/SEC)

(LBM/SEC)

(LBM/$EC PRESSURE (PSIG1 E jl _NEW Ql.!L.,MjL NO CHAMG1)

(LBM/SEC)

_0LD NEW.

0 41.10 33.80 60.77 55.27 393.4 495.27 482.47 20 40./5 33.61 60.38 54.27 369.8 470.93 457.68 40 40.41 33.42 59.98 53.27 344.4 444.79 431.00 100

-39.38 -32.87 58.81 52.77 103.8 201.99 189.44 140 38.69 32.50 57.67 51.71 0.0 96.36 84.21 200 37.66 31.93 55.97 50.11 93.63 82.04-400 34.10 30.01 50.37 44.48 84.47 74.49 600 30.39 28.03 43.60 38.28 73.99 66.31 1000 22.36 23.07 25.70 21.25 43.06 44.32 1600 8.30 16.02 0.0 0.00 8.30 16.02 2800 0.00 0.00 0.0 0.00 0.0 0.00 0.00 CRSES-2 LARGE BREAX $1 FLOWS CHG PUNP5(2)

HHS!(2)

RHR(1)

TOTAL (LBM/SEC)

(LBM/SEC)

(LBM/SEC)

(LBM/SEC)

PRES 5URE (PSIG)

,,qLQ,,

NEW

.j10 R

NO CHANa[

,,Q1Q,,,,

NEW 0

65.82 44.67 80.76 68.64 427.45 574.03. 540.76 20 65.46 44.47 80.14 68.11 246.61 392.21 359.19 40 65.11 44.28 79.52 67.60 193.6 338.23 305.48 100 64.04 43.71 77.68 66.03 0.0 141.72 109.74 140 63.31 43.30 76.34.64.92 0.0 139.65 108.22 200 62.22 42.70 74.34 63.26 136.56 105.96 400 58.48 40.54 67.10 57.34 125.58 97.88 600 54.58 38.28 59.06 50.61 113.64 88.89 1000 46.18 33.41 38.85 33.87 85.03 67.28 1600 31.21 24.86 0.0 0.00 31.21 24.86 230u 0.00 0.00 0.0 0.00 0.0 0.00 0.00 Page 7 of 25

SECL-91-367 1

CPSES-1 SMAll BREAX Sl_,f.L M CHO PUMPS (l)

HHS!(1)

TOTAL (LBM/SEC)

(LBM/SEC)

(LBM/SEC)

A PRESSURE (PSIG1

.,J.LQ_ E L A Q.

NEW

,_Qa,.,31L PERCENT 0

41.09 33.80 60.4 55.27 101.48 89.07

-12.23%

100 39.38 32.87 58.2 53.24 120 39.04 32.68 57.7 52.82 200 37.66 31.93 55.9 51.15 300 35.88 30.98 53.6 48.96 400 34.10 30.01 51.1 46.71 500 32.27. 29.03 e8.5 44.25 80.77 73.28

-9.27%

600 30.39 28.03 45.7 41.66 76.09 69.69

-8.41%

700 28.46 27.01 42.8 38.92 71.26 63.93

-7.48%

800 26.48 25.96 39.7 36.07 66.18 62.03

-6.27%

900 24.45 24.83 36.2 -32.94 60.65 57.77

-4.74%

1000 22.36 23.70 32.4 i.9.05 54.76 53.20

-2.85%

1200 18.00 21.33 22.7 20.66 40.70 41.99

+3.17%

1300 15.72 20.13 15.9 15.15 31.62 35.28 til.57%

1400 13.34 18.89 4.3 5.95 17.64 24.84

+40.82%

1500 10.88 17.60 0.0 0.00 10.88 17.60

.+61.76%

1600 8.30 16.02 8.30 16.02

+93.01%

1800 2.50 12.05 2.59 12.05

+365.2%

2000 0.00 6.78 2100 0.00 3.75 CPSES-2 SKALL BREAK SI FLOWS CHO PUMPS (l)

HHSl(l)

TOTAL (LBN/SEC)

(LBM/SEC)

(LBM/SEC)

A PRESSURE (PS!Q

,,,QQ, EL

_,Q Q,,J.[ L AQ,,

,NR, PERCENT 0

45.93 33.80 60.4 55.27 106.33 89.07

-16.23%

100 44.23 32.87 58.29 53.24 120 43.58 32.68 57.84 G2.82 200 42.50 31.93 56.02 51.15

.300 40.74 130.98 53.64 48.96 400 38.94 30.01 47.46 46.71 500 37.11 29.03 48.54 44.75 85.65 73.28

-14.11%

-600 35.23 28.03 45.70 41.66 80.93 69.69

-13.88%

700 33.30 27.01 42.86 38.29 76.16 65.03

-13.43%

-800 31.33. 25.96 39.56 36.07 70.89.62.03

-12.50%

900 29.29 24.83 36.26 32.94 65.55 57.77

-11.87%

1000 27.21 23.70 32.14 29.50 59.35 53.20

-10.36%

1200 23.99 21.33 21.31 20.66 45.30 41.99

-7.31%

1300 22.88 20.13 15.89 15.15 38.77 35.28

-8.89%

1400 18.19 18.89 4.33 5.95 22.52 24.84

+10.30%

1500 15.73 17.60 0.00 0.00 15.73 17.60

+11.89%

1600 13.14 16.02 13.14 16.02

+21.92%

1800 7.43 12.05 7.43 12.05

.+62.18%

2000 0.00 6.78 2100 0.00 3.75 0.00 0.00 t

Page 8 of 25

SECL-91-367 4

3,2 LOCA EVALUATION 3.2.1 Unit F targe Break LOCA 1he large break analysis of record for Comarche Peak Unit 1 (CPSES-1) was performed using the Westinghouse FEB78 evaluation model (Reference 1). This calculation resulted in a PCT of 2010.7'F. Safety evaluations perfomed under 10 CFR 50.59 and ECCS model changes have resulted in an additional PCT increase of 55.7'F leading to a current large break LOCA PCT of The changes to the performance of the Charging Si 2065.7'r (Reference 2)d in the table above, would result in a reduction in SI and HHS!, as documente flow delivery of about 13.70 lbm/sec (9 40 psig) at large break pressure conditions. However, the large break LOCA analyses for CPSES-1 was performed using only one train of $1. Since the most limiting single failure is loss of an RHR only, the current analysis is conservative with respect to the limiting single failure requirement.

Therefore, flow from the additional train having one Charging and one HHSI pump can ce credited to the analysis. The extra flow provided by the additional charging and SI pump would be about 25.19 lbs/sec greater (@ 40 psig, determined by comparing the CPSES-1 and CPSES-2 tables provided in this evaluation, Westinghouse Fluid Systems has cmfimed that.

these new ECCS flows apply equally to both CPSES units), thus ffsetting the reduction in 51. A previous evaluation also took credit for sovue of the margin provided by the additional-Charging /SI and HHS! (Reference 4). This evaluation and the previous evaluations have used 13.70 + 6.7 and 3.03 or 23.43 lbm/sec of the existing 25.19 lbm/see margin.

Since there is remaining SI flow margin to the analysis assumption, there is no penalty for the large break FCT as a result of the reduction in Charging /SI and HHS! to preclude runout of these

- pumps dur'ng the recirculation phase of a LOCA.

3.2.2 Unit 2 Large Break LOCA The large break analysis of record for Comanche Peak Unit 2 (CPSES-2) was performed using the Westinghouse 1981 evaluation.nodel (Reference 5).

This calculation resulted in a PCT of 1808.41'F.

Safety evaluations performed under 10 CFR 50.59 and ECCS model changes have resulted in an additional PCT increase of 73.0'F leading to a current large break LOCA PCT of 1881.47'F (Reference 2'. The current CPSES-2 large break LOCA analysis calculated the most *1miting conditions when maximum ECCS flows were used in the analysis. The changes to the charging /S! and HHSI do not affect maximum ECCS assumptions, ano, t.Wafore, the PCT associated with the maximum ECCS assumption will not-change. However, the minimum Si case must be evaluated to determine if the most limiting condition will switch between maxiaium and minimum SI. The changes to the performance of the Charging /S! and HHSI, as documented in the table above, would result in a reduction in minimum SI flow delivery of about 32.75 lbs/sec (9 40 psig) at large breat pressure conditions. - This reduction in ECCS flows would increase PCf by about 31.95'F based on Westinghouse sensitivity studies. This increase, when added to the DECLG with Cd=0.6 minimum SI case, results in a PCT of 1803.56 +

31.95 - 1835.51'F. Additionally, PCT changes of 73.0'F (Reference 2) previously calculated for 50.59 evaluations and ECCS models must be added to this PCT.

Thus, the new PCT for the minimum SI case will be 1908.51'F.

This results in the minimum 51 case becoming more limiting than the maximum $1 case. However, sufficient margin exists to the 10 CFR 50.46 limits such that no regulatory limits would be exceeded.

Page 9 of 25

1 SECL-91-367 i

3.2.3 Unit 1 Small Break LOCA The small break LOCA analysis of record is a W-Flash (Reference 6) calculation which resulted in a PCf of 1787.5'F.

Safety evaluations performed under 10 CFR 50.59 and ECCS model changes have increased the small break PCT to 1969.7'F (Reference 2). A review of the new S1 flows for CPSES-1 small break reveal that the SI flows improve above a pressure of about 1000 psig.

Thus, the effect of the new Si flows must a:curately account for the small break transient-and the effect of varying RCS pressure on SI flow.

To accurately determine the change in SI, the pressure transient from the most limiting break (a 4-inch cold leg break) was used to calculate an integrated average $1 flow from the inception of $1 to PCT time.

This effort had two conclusions.

First, the new Si flows reptesent a redu: tion in $1 of about 3.22% over the flow evaluated in Reference 4.

Secondly, the evaluation performed in-Reference 4 had evaluated a 10% reduction in SI flows and the integrated flows calculated by this evaluation determined that the-flows are 3

actually 14.5% lower. Thus,- the Reference 4 evaluation was non-conservative by 4.5% in flow.

Therefore, this evaluation will account for a total reduction in SI flows of 4.5 + 3.22-or 7.72%. Westinghouse internal sensitivities have documented the effset of reductions _in high pressure SI on small break PCTs calculated by W-Flash. The reduction in the CPSES-1 Charging /SI and HHSI flow of 7.72% has resulted an increase in PCT of about 64.85'F. This reduction is baswd on the flows given in the table above for flow between 1400 psig and 600 psig. The new PCT is now 2034.55'F so that margin exists to acconnodate the potential increase in PCT without exceeding the 10 CFR 50.46 limit of 2200*F.-

3.2.4 Unit 2 Small Break LOCA The small break LOCA analysis of record is a W-Flash (Reference 7) calculation which resulted in a PCT of 1290.3'F. Safety evaluations perfomed under 10 CFR 50.59 and ECCS model changes have increased the small break PCT to 1338.3*F(Reference 2). A recent technical review by TUE of the CPSES 2-LOCA analyses revealed that the CPSES-2 call break LOCA analysis contains errors and was not-typical of-small break behavior for Westinghouse PWRs.

Therefore, this analysis was determined to be unacceptable for licensing purposes and efforts to replace this analysis are currently on going internal to Westinghouse and TUE. Therefore, the new CPSES-2 small break ECCS flows cannot be evaluated due to the lack of a base case small break analysis.

However, the potential effect en PCT can be assessed to support an estimate of the effect on any CPSES-2 small break LOCA anclysis. Westinghouse internal sensitivities have documented the effect of reductions in high pressure SI on small break PCTs calculated-by W-Flash. A review of the new SI flow for CPSES-2.small break reveal that the SI flows improve above a pressure of about 1300 psig. Reviewing the change in small break flows between 600 and 1400 psig show the potential for a net reduction in 51 flows of 11.095 which would increase PCT by.as much as 93.16*F. Using CPSES-1 as a standard for comparison (since CPSES-1 1 2 are very similar) this increase-in PCT has baen Page 10 of 25 L

.i.

-..... i

I SECL-91-357 judged to not result in an increase which would exceed the 10 CFR 50.46 2200'F criterion.

Further, this increase is small compared to the margin expected to be detemined by any new CPSES-2 small brJak LOCA analysis; therefore, the proposed changes to the SI flows are deemed acceptable by Westinghouse.

3.2.5 LOCA-Related Analyses (THE Foll0 WING EVALUATIONS FOR LOCA RELATED LICENSING REQUIREMENTS ARE APPLICABLE TO BOTH COMANCHE PEAK UNITS.)

3.2.5.1 Blowdown Reactor Vessel and Loop Forces - FSAR Chapter 3.9 The performance of the ECCS is not modelled in this analysis since the maximum loads occu' before there is any possibility for the ECCS to respond. Thus changes in ECCS performance cannot influence the results of calculations perfomed to determine the forces on vessel internals or RCS loop piping as a result of a hypothetical LOCA.

Therefore, the reduction in the charging /SI and HHS! will have no effect on the blowdown reactor vessel forces and RCS piping forces found in FSAR chapter 3.

3.2.5.2 Post-LOCA Long-Tem Core Cooling - FSAR Chapter 15.6.5 WCAP-8339 (Reference 8) presents the Westinghouse licensing comitment to keep the reactor core subcritic01 All control Rods Out (ARO) following a hypothetical large break LOCA on the boren provided by the ECCS. WCAP-8339 is cited in the Comanche Peak Steam Electric Station FSAR Chapter 15.6.5 and is part of the licensing basis for the Comanche Peak Steam Electric Stations. A change in Charging /S1 and HHSI pump performance will not change the total volume of water injected from the RWST, and, therefore, the mass of water residing in the containment sump post-LOCA will remain unchanged. The volume of water injected from the RWST is a function of the RWST LO-Level and LO-LO Level setpoints and operator action. Thus, minor changes in Charging /SI and HHSI pump perfomance will not affect the post-LOCA sump boron concentration.

Since this licensing comitment is checked by Westinghouse on a cycle-by-cycle basis, compliance with this requirement is assured independent of this safety evaluation.

3.2.5.3 Hot leg Switchover of the ECC5 to Prevent Potential Boron Precipitation - FSAR Chapter 6.3 The calculations perfomed to determine the time (post-LOCA) at which the boren concentration in the reactor vessel would exceed the solubility limit do not require modelling of the pumped ECC5 flow rates. However, an evaluation is required to assure that adequate ECCS flow is provided to prevent boron precipitation following the switchover to hot leg recirculation. The minimum time for hot leg switchover for CPSES-1 was calculated to be 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> based on large break LOCA assumptions.

The calculated core bollaff rate at 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> would be approximately 20 lbm/sec, The minimum ECCS flow required for delivery to the het legs following switchover is 1.5 times the boiloff rate for a large Page 11 of 25

SECL-71-367 break LOCA or approximately 30 lbr../sec.

These va kes are judged to apply te CPSES-2, since.CPSES-2 has a slightly larger core volume than CPSES-1. Since the low head $1 is the major contributor to hot leg rectreulation flows following a hypothetical large break LOCA, the 30 lbm/sec requirement would easily be satisfied. During a small break LOCA, the RCS pressure will be considerably higher than the pressure following a large break LOCA. The RCS pressure for a small break LOCA at the hot leg switchover time of 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> can conceivably be as high as the highest steam generator safety valve setpoint (approximately 1250 asia). Conditions for a small break LOCA differ significantly from tiose fo* a large break LOCA such that the requirements to prevent boron precipitation are much less restrictive than those for a large break LOCA. Thus under small break LOCA conditicos, ECCS flow to both the hot

~

and cold legs can be considered in satisfying the boiloff requirement. The total delivery from the Charging and Safety injection purips mest meet or exceed 30 lbm/sec at 1250 psia in order to satisfy the boiloff requirt nent for a small break LOCA. A review of the proposed changes to the Charging, ! and HHS! pump performance shows that the necessary ECCS flows will be proviceo for both large and small break LOCAs during hot leg recirculation.

Thus, the proposed reduction in Charging / Safety injection and HHS1 pump flows at CPSES-1 & 2 do not alter the conclusions of calculations performed to determine the time necessary to switchover the ECCS from cold leg recirculation to hot leg recirculation.

4.0 $_AFETY SIGNIFICM([ OF THE DEGMSE IN T)iE SI CHARGING FLOW RAlfJf UON-LOCA EVffUS 4.1 LICENSING BASIS The non-LOCA events which are potentially affected by the rentrifugal Charging Pump (CCP) degradation are ones which may utilize Safety injection (SI) flow to help mitigate the consequences of the event.

The events are secondary side breaks which are analyzed to determine the primary side response or the mass and energy released.

The licensing basis for these events are documented in FSAR See. tion 6.2.1.4 (Mass and Energy Release inside Containment from a Steamline Break), WCAP-lll84 (Mass and Energy Celease Outside Containment from a Steamline Break), FSAR Sections 15.1.4 and 15.1.5 (Steamline Break - Core Response),andFSARSectio,15,2.8(FeedlineBreak). Typically, the analyses of these accidents take credit for minimum flow from one CCP to help mitigate the consequences of the event.

4.2 NON-LOCA AMALYSES EVALUATION The following evalu W an is based on the non-LOCA licensing basis impact identified in Section 4.1.

4.2.1 Steamline Break Mass / Energy Releases - Inside Ccntainment (FSAR Chapter 6.2.1.4) i l

For the steamline break mass and energy releases inside containment, sensitivities conducted for other plants have shown that small changes in the Page 12 t,( 25 l

~ ~ - -.. - - _. -. - _. - -

SECl.-91-367 charging flow rates, actuation delays, or 1:,rge changes in boron concentration (e.g., BIT removal studics) have little effect on the mass and energy releases.

Thus,*the charging flow reduction will have a negligible effect on the Comanche peak steamline break mass and energy releases 'nside containment.

4 4.2.2 Steamline Break Miss/ Energy Releases - Outside Containment Sensitivittas performed for the steamline break. superheated steam mass and energy releases outsido containment, contained in Reference 12. show that the results are rot sensitive to large changes in charging flow.

Therefore, a small change in the charging flow has a negligible impact on the results.

4.2.3-SteamlineBreak-CoreResponseAnalysis(FSARChapters15.1.4and 15.1.5) 2 for these. events, the bounding case is the 1.4 ft hypothetical break with offsita power presented in F5AR Section 15.1.5. This case is analyzed to show that the core remains intact and in place and that the radinttor doses do not excced the guidelines of 10 CFR100.

This is demonstrated by showing that the DNE design basis is met, even though DNB and possible clad parforation are not necessarily unacceptable for certain fsilure cases.

The transient ' analysis for this event conservatively assumes a small impact on the core reactivity due to the boron delivered by one charging pump.

Because of this, the CCP flow reduction identified in section 1.0 does not have a large impact on the results.

In addition, the intermediate head SI pumps are not credited in the analysis.

If the total safety injection flow from the charging and 51 pumps is considered, more boron is delivered to the RCS than is assumed in the licensing basis analysis. Therefore, the conclusions of the Comanche Peak FSAR remain valid.

4.2.4 feedwaterSystemPipeBreak(FSARChapter15.2.8)

The-feedwater rupture _ transient is a Conditien IV transient and is also analyzed to show that the core remains intact and in place and that the radiation doses do not exceed the guidelines of 10 CFR100. This is demonstrated by showing that bulk boiling does not occur in the hot leg of the RCS. Therefore, a pus' tive margin to the hot leg saturation temperature must be maintained.

l-This transient assumes the actuation of one charging pump to provide flow l-following a low steamline pressure SI signal. The charging flow provides an additional heat sink to remove decay heat and stored energy from the RCS. Once l

steamline isolation occurs, the RCS pressure begins to rapidly increase.

l-

- Within several minutes, the RCS pressure increases to the pressurizer safety L

-valve set pressure, which is higher than the effective shutoff head for the L

charging system. This occurs well before the point of turn-around which is defined as the time when the secondary heat removal capability exceeds the primary side heat generation.

The reduced CCP flow identified in Section 1.0 has been evaluated based on generic sensitivities. The impact on the minimum margin to hot leg saturation Paga-13 of 25

.__.1,___..____.._-._

e SECL-91-367 has been detemined to be stall; the licensing basis analyses contain sufficieat margin to accomodate the slight impact.

Therefore, the conclusions i

of the Comanche peak FSAR remain valid.

5.0 DETERMINAl_ ION OF UNQyl[', LED SAFETY OUESTIM 5.1 Will the probability of an accident previously evaluated in the FSAR be increased?

The evaluation of the proposed modifict. tion to the Technical Specification surveillance requirement 4.5.2.h indicates that pump operability and system integrity is not challenged.

The Technical Specification modifications do not result in a condition where the design, material, and construction standards of the ECCS that were applicable prior to the Technical Specification modification are altered.

In addition, the safety function of the ECCS, which is related to accident mitigation, has not been altered.

Therefore, the probability of an accident is not increased by the Technical Specification modifications.

Further, the ECCS is an accident mitigator and as such cannot increase the proDability of any accident previously evaluated in the FSAR.

Additionally, there are no non-LOCA accidents which would be more likely to occur due to a change in the CCP flow rate since the flow dagradation does not change the likolthood of the event to occur and no new failure mechanisms are introduced.

5.2 Will the consequences of an accident previously evaluated in the FSAR be increased?

The Technical Spocification modifications do not affect the integrity of the ECCS such that its function in the control of ddiological consequences is affected.

In addition, the Te:hnical Specification 1

modifications do not affect any fission barrier.

Therefore, consequences of an accident previously evaluated in the FSAR are not expected to be increased.

Further, the principal LOCA result is the calculated PCT. The principal l

LOCA consequence is offsite dose. The calculated doses are based in the TID source terms, and as long as the LOCA criteria of 10 CFR 50.46 are r.;et, this source tem is applicable.

Since PCT and other criteria were met, there is no increase in LOCA consequences.

The decrease in minimum CCP ficw did not result in a violation of the acceptance criteria for any event.

This includes the ON8 design basis, the hot leg saturation limit, and the mass / energy releases.

Thus, the radiological consequences for these events do not increase as a result of l

the CCP flow degradation, i

l Page 14 of 25

.- ~-.

4-SECl-91-367 5.3 May the possibility of an accident which is different than any already evaluated in the FSAR be created?

The Technical Specification modifications do not cause the initiation of

-any accident nor create any new credible limiting single failure.

The Technical Specification modifications do not result in sny event previously deemed incredible being made credible. As such, it does nnt create the possibility of an accident different than any evaluated in the i

FSAR.

Since adequate ECCS flows were demonstrated, there is no accident that could be created which is different than already evaluated in the FSAR.

$.4 Will the probability of a malfunction of equipment important to safety previously evaluated in the FSAR be increased?

The Technical Specification modifications do not create any new failure modes for the ECC i or other safety-related equipment.

The Technical Specification modifications do not result in any original design specification to be altered.

In addition, the Technical Specification modifications do not result in equipment used in accident altigation to te exposed to an adver:e environment. Therefore, the Technical Specification modifications will not increase the probability of a malfunction of equipmeat important to safety previously evaluated in the FSAR.

This changr. is being implemented to preclude runout of the Charging /SI and HHSI pumps during the recirculation phase.

Thus, the probability of ECCS pump failure due to cavitation has been reduced, not increased.

CCP flos is used in non-LOCA analyses to help mitigate the consequences of secondary side breaks.

There is rio known mechanical or electrical change to the CCPs which weuld increase the probability of the equipment to malfunction.

5.5 Will the consequences of a malfunction of equipment important to safety previouslj evaluated in the FSAR be increased?

The Technical Specification modifications do not result in an ECCS response to accident-scenarios different than that postulated in the FSAR. The ECCS performance and component integrity is not affected so l

that centrol of radiological. consequences is unimpaired. No new equipment malfunctions have been identified that will affect fission product barrier integrity., Therefore, the Technical SpecificaN modifications will not increase the consequences-of a malfunction of eqJipment important to safety previously-evaluated in the FSAR.

l l

Thore are no changes to the non-l.0CA analyses as a result of the reduction in ECCS flow which would impact radiological consequences because all applicable criteria continue to be met.

The evluation has shown that the reactor core and mass and energy releases are not adversely inspected by tho.CCP flow degradation.

Page 15 of 25 L

i a.

SEcl M -367 5.6 May the possibility of a malfunction of equipment important to safety different,than any already evaluated in the FSAR be created?

The Technical S acification modifications do not have any significant impact of the a)ility of the ECCS to perform its intended safety functions. The Technical Sper fication modifications do not create failure modes that could adverselv impact safety-related equipment.

Therefore, it will not create th possibility of a malfunction of equipment im;ortant to safety different than previously evaluated in the FSAR.

5.7 Will the margin of safety as defined in the BASES to any technical specification be reduced?

The Technical' Specification modifications will not have any significant effect on the availability, operability, or performance of the ECCS.

Therefore, the Technical Specification modifications will not red 9ee the margin of safety as described in the bases to any technical specification.

Since the calculated PCT will remain urder the NRC acceptance limit of r

2200*F, the margin _of safety as defined in the BASES to the LOCA peaking factor Technical SpNification would not be reduced.

The margin of safety in non-LOCA accidents is not reduced riue to the change in CCP flow.

The acceptance criteria of minimur DN8R and maximum primary and secondary side pressures remain unchanged and are met.

Therefore, the same margin exists to the design failure point or system limitation.

For non-LOCA mass and energy release results which have no explicit acceptance criterion, the magnitude of the change due to the revised CCP flow rates is insignificant so that the margin to safety is not impacted.

6.0 CONCLUSION

S Based on the evaluation of the ECCS and pump operability concern:, the modifications of the Technical Specification surveillance requirements are acceptable. The minimum flow of the three branch lines for the CH/SI subsystem is to be revised from 333 gpm down to 245 gpm and fr.om 437 gpa down to 400 gpm for the IHSI subsystem. The operability of the ECCS will not be challenged by these pressures and flowrates.

Additionally, the reduction in-Charging /S! and HHS! necessary to prevent runout during ECCS recirculation has been evaluated against the LOCA-related licensing-criteria for large breale, small break, LOCA hydraulic forcing functions, Post-LOCA long-term core cooling, and hot log switchover criteria.

In each case, the necessary LOCA requirements were satisfied.

Also. 'a reduction in the charging flow rate will not affect the conclusions of the non-l.00A analyses presented in the FSAR.

Further, the steamline break mass' and energy release data for outside containment remains valid.

Page 16 of 25 L

4 SECL 91-367 Therefore, the conclusion reached as a result of the above evaluation is that the Technical $pecification modifications do not represent a potential unreviewed safety question, as defined in 10 CFR 50.50 for the items in Westinghouse scepe.

7.0 REFERENCES

1)

WCAP-9220-P-A, ' Westinghouse ECCS Evaluation Model February 1978 Version',

febiuary 1978, Proprietary.

2)

Letter WPT-13635, J. L Vota (E) to M. J. Cahill, Jr. (TVE), "ECCS

'nluation Model Changes", 06/20/91 3)

WCAP-12368 (Rev.1), hon-Proprietary, ' Comanche Peas. nit 1 Accident Analysis Assumptions Checklists", August 1990.

4)

Letter WPT-12588, J. I Vota (W) to M. J. Cahtil, Jr. (TUE) Revised Charging flow Evaluation", 4/2/90 5)

WCAP-9220-P-A, Revision 1

" Westinghouse ECCS Evaluation Model 1981 Version', February 1982, Proprietary.

6)

WCAP-B200 Rev. 2 (Proprietary) and WCAP-8261 Rev. 1 (Non-Proprietary),

• WFLASH - A fortra.i-IV Computer Program for Simulation of Transients in a Multi-Loop PWR", June 1974 7)

WCAP 8970 (Proprietary) and WCAP-8971 (Non-Proprietary), ' Westinghouse Emergency Core Cooling 5/ tem Small Break October 1975 Model", April 1977.

8)

WCAP-8339 (Non-Prorpiutary), 'Westinghosue Caergency Cort Cooling System Evaluation Model - Sunnary', June 1974.

9)

Comanche Peak, Units 1 and 2. Updated Final Safety Analysis Report, (Revision 10, July 1990.]

WPT-13927, 'CPSES Unit I and 2 Minimum ECC5 Performarice Data,' S. Swantner 10) and R. Tiskus, September 20, 1991,

11) WPT-13961, ' Emergency Core Cooling System Pump Runout Margin Issues".

Vota to Cahill, September 25, 1991.

12) WCAP-11184 Rev.1, 'Steamline Break Mass / Energy Releases ior Equipment Environmental Qualification Outside containment,' October 1985.

l l

l l

i Page 17 of 25

l R

SECL-91-367 t

TABLE 1 Safety Eval'uetions for the Comanche Peak Unit 1 Large Break LOCA Analysis 1;Lerence

[y3]yationDescriotion i

D Penalty _

l.

0.0'F CWS-TBX-895 Reduced $1 flow would reduce spilling, with no impact on core or downcomer levels durf ng reflood.

2.

0.0'F SED-SA-296 Bottom of core recovery delayed less than 0.02 sec. Later,-

downcomer filled slightly earlier due to higher flow. Supersedes evaluation number 1.

3, 6.2'F SED-SA-340 Modified steam generator bypass

flow, increase in initial core inlet temperature.

4.

0.0'F SED-SA-774 Revised 51 flow tech. spec.

Increased 51 is a bor,efit since Comanche Peak 1 is not a max-S!

pl ant.

5.

10.0'F SED-5A-884 Reduced cccumulator water volume by 6 cubic feet.

6.

0.0'F SED-SA-1048 Reduced auxiliarj feedwater flow.

7.

0.0'F SECL-88-705 Increased the signal processing delay time from 1 sec. to 2 sec.

o 8.

0.0'F SECL-89-210 Installed heated junction themocouples and ;nrouds.

9.

18.6'F SECL-89-594 Rev 1 Increase in 5/G tub. pluggMg.

2.1% area correction and 1% SGTP.

10.

SECL-89 494 Steam generator feedwater flow split. Same as evaluation 3.

i 11.

1.0'F SECL-89-432 Reduced RHR flow due to delay in isolating the mintflow lines.

=12.

0.0'F SECL-89-672 increased the main steam safety valve blowdown.

t Page 18 of 25

SECL-91-367 TABLE 1 cent.

Safety Eval'uations for the Comanche Peak Unit 1 Large Break LOCA Analysis PCT Pennity Referetice Evaluation De.1sIjption 13.

0.0'F SECL-89-10ll increased the upper nitrogen pressure limit for the accumulatort.

14.

0.0'F SECL-89-964 increased the AFW purge volume used to calculate the time to switchover to the lower enthalpy.

15.

0.0'F WPT-lll68 Comanche Peak Steam Electric Station Setpoint $tudy infenaation. Pressurizer Low Pressure $1 at 1700 psig and containment Hi-1 at 5.0 psig.

16.

0.0'F SICL-90-135 Automatic AFW Controller Safety Evaluatioa.

17.

0.0*F SECL-90-195 Revised Charging Flow Evaluation.

IP.

0.0'F SECL-90-215 Reevaluation of the e#rset on small break LOCA for reduct:sns in Charging Si and HHSI. This evaluation rescinds SECLs90-135, 195 and SED-SA-2S6.

19.

0.0'F SECL-90-293 Increased AFW purge volumes due to check valve back leakage.

20.

12.0'F Thimble tube modeling penalty, NRC GENERIC LETTER 86-016.

21.

0.0*F SECL-90-329 Revised Auxiliary Feedwater purge volumes.

22.

0,0*F SECL-90-352 Increased Main Feedwater Isolation time.

23.

0.0*F SECL-90-545 Increased Auxiliary Feedwater flow from 625 gpm to 1225 gpm, entire purge volume assumed to be at 440*F.

l Fage 19 of 25

i SECL.91 367 l

TABLE I cont.

Safety EvaTuttians for the,omanene Peak Unit 1 Large Break LOCA Analysis r

ECT Penalty--

BehrJAce_

Evaluation _Descriotion 24.

0.0'F SECL 91-CB80 increased start time for the steam driven turbino auxiliary feedwater l

pump.

The PCT change is based on an assumed total auxiliary feedwater flow rate of 1290 gpm compared to the SECL.90 545 assumption of 1225.5 gpm.

3 25.

7.2'r WPT.13635 Permanent changes to the ECCS evaluation model.

26.-

0.0*F SECL-91-3070 ECCS Flow changes to prevent runout of the Charging /S! and HHSI during post-LOCA recirculation.

55.0'F Total PCT penalty for 10CFR50.59 changes and permanent ECCS model changes.

2010.7'F Limiting Case PCT 2065.7'F-Total Limiting Case PCT I.

Page '20 of: 25 L

_ _... _ ~.

T SECL-91-367 TABLE 2 Safe;y Evaluttions for the Comanche Peak Unit 1 Small Break LOCA Analysis PCT PennitY_

Seferente LYJLlyation Descriotion 1.

0.0*F CWS 18X-595 New data more conservative because more Si flow delivered before time of PCT.

2.-

68.0'F SED-SA-296 4.4% shortfall is Si flow delivered over time period of interest,

't supersedet evaluation number 1.

3.

0.0'F SED-SA-77s Revised $1 flow tech. sDec.

Increased Sl is a benefit.

4.

II 0'F SED-SA-1048 Reduced auxiliary feedwater flow from 1410 to 1290 gpm.

5.

9.0'F SECL-88-706 increased the signal processing delay time from I sec. to 2 sec.

6.

0.0'F SfCL-89-210 Installed heated juncticn thermocouples and shrouds.

7.

0.0'F SECL-89-594'Rev. 1 Increase in 9/G tube plugging.

2.1% area correction and 1% SGTP.

8.

0.0*F SECL-89-494 Steam generator feedwater flow split.

9.

0.0'F SECL-89-432 Reduced RHR flow due to delay in isolating the miniflow lines.

I 10.

0.0*F SECL-89-672 increased the main steam safety valve blowdown.

11.

0.0'F SECL-89-1011 Increased the upper nitrogen pressure limit for the accumulators.

12.

53.0'F SFCL-89-964 Increased the. AFW purge volume used l

to caleillate the time to switchover to the lower ant!.sipy. -

13.

2.0'F WPT-11168 Comanche Paak Steam Electric Station Setpoint Study l

Information. Pressurizer Low Pressure Si at 1700 psig.

l Page 21 of 25

SECL-91-367 TABl.E 2 cent.

Safety Eval'uations for the Comanche Peak Unit 1 Small Break LOCA Analysis PCT Penalty =

fLtitLtaC.t _

lytluttQa_Qtscrhtjen 14.

75.5'F SECL-90 135 Automatic AFW Controller Safety Evaluation.

15.

84.0'F SECL-90-195 Revised Charging Flow Evaluation.

16.

121.0'F

.SECL-90-215 Reevaluation of the effect on small

-88.0'F break LOCA for reductions-in

-75.0'F Charging Sl and HHSI. This

-84.0'F evaluation supersedes SECLs 90 135, 195 and SED-SA-296.

-126.0'F 17.

19.2'F SECL-90-293 Increased AFW purge volumes due to check valve back leakage.

18.

0.5'F SECL-90-329 Revised AFW se volumes.

-lI.0'F Supersedes eva dation performed in 0

SED-5A-1046 (07/01/85). The 11 F penalty has been removed since the analysis value of.615 gpm is conservative when comoared to the CPSES Unit-No.) Aux feed flow of-

-1290 gpe.

19.

0.0'F SECL-90-352 increase in the Main Feedwater I

! solation time.

20.

' -25.0'F SECL-90-545 Increase in the Auxiliary Feedwater flow rate for 625 gpm to 1225.5 gpm, entire purge volume assumed to 0

be at 440 F.

21.

2.0'F SECL-90-545 Adjustment to the small break analysis results for the correction to the Zire/ Water. error.

22.

0.0'F SECL-91+0680 Increased start time for the steam-driven turbine auxiliary feedwater pump. The PCT change is based on an assumed total auxiliary feedwater flow rate of 1290 gpm compared to the SECL-90 545 assumption of 1225.5 gpm.

Page 22 of 25 1

SECL-91 367 TABLE 2 cent.

Safety Evaluations for the Comanche Peak Unit 1 Small Break LOCA Analysis PCT Denalty B;h.regs 11aluntion Descrietion 23.

0.00'F WPT-13635 Permanent changes to the ECCS evaluation model.

24, 64.85'F SECL 91-3670 ECCS Flow changes to prevent runout of the Charging /SI and H451 during post-LOCA recirculation.

247,05'F Total PCT penalty for 10CFR50.59 changes t.nd permanent ECCS raodel changes.

1787.5'F Limiting case PCT 2034.55'F Total Limiting tase PCT Page 23 of 25

i i

SECL-91-367 l

4 I

f TABLE 3 Safety Evaluations for the Comanche Peak Unit 2 Large Break LOCA Analysts fiU.csh Rtfa m e Eva1uation Deserietion i

1.-

12.0'F Thimble tube modeling penalty, NRC GENERIC LETTER 86-016.

1 2.

61.00*F WPT-13635 ECCS permanent model changes, i

3.

31.95'F SECL.91 367 ECCS Flow changes to prevent runout of the Charging /S! and HHS! during post.LOCA recirculation.

104.95'F Total PCT penalty for 10CFR50.59 changes and permanent ECCS mode)-

changes.

1803.56 Limiting Case PCT

........'F.....

.......a.......

1 1908.51*F Total Limiting Case PCT l

l-l l

l i

l l:

l:

l 1-l Page 24 of 25

~

. ~

_ _ _ _ _ ~ _ _

SECL-91-367 TABLE 4 Safety Eval'uitions for the Comanche Peak Unit 2 Small Break LOCA Analysis PCT Penalty Reference

[nluation_Descriotion 1.

11.0'F SED-SA-1048 Aalliary feedwater Flow evaluation.

l 2.

37.0'F WPT-13635 Permanent changes to the ECCS evaluation model.

3.

93.16'F SECL-91-367 ECCS Flow changes to prevent runout of the Charging /S! and HHS! during l

post-LOCA recirculation.

l 141.16*F Total PCT penalty for 10CFR50.59 changes and permanent ECCS model changes.

'F Currently there is no acceptable small break LOCA analysis CPSES-2 i

'F Total Limiting Case PCT (Analysis is scheduled and underway and will be completed prior to receipt of l

an Operating License) l i

L Page 25 of 25

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