ML17334B684

Forwards Addl Info Re CAL Item 3,involving Ability of Plant to Be Cooled Down in 36 H,Per NRC 980109-23 Insp

ML17334B684
Person / Time
Site:	Cook
Issue date:	01/29/1998
From:	Fitzpatrick E INDIANA MICHIGAN POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
AEP:NRC:1260G8, CAL, NUDOCS 9802120308
Download: ML17334B684 (9)

Text

CATEGORY 1 ~

REGULATOR INFORMATION DISTRIBUTIO?PKYSTEM (RIDS)

ACCESSION NBR:9802120308 DOC.DATE: 98/01/29 NOTARIZED: NO FACIL'50-315 Donald C.

Cook Nuclear Power Plant, Unit 1, Indiana M

650-316'onald C.

Cook Nuclear Power Plant, Unit 2, Indiana,M AUTH.NAME AUTHOR AFFILIATION FITZPATRICK,E.E Indiana Michigan Power Co.

RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)

SUBJECT:

Forwards confirmatory action resporise validation insp for RAI re item 3, "36 Hour Cooldown.

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TITLE: Immediate/Confirmatory Action Ltr (50 Dkt-Other Than Emergency Prepar NOTES:

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Indiana Michigan Power Company 500 Circle Drive Buchanan, Ml 49107 1395 INSlANA N1CNESSl N PQWM January 29, 1998 AEP:NRC:1260G8 Docket Nos.:

50-315 50-316 U.S. Nuclear Regulatory Commission ATTN:

Document Control Desk Mail Stop 0-Pl-17 Washington, D.C.

20555-0001 Gentlemen:

Donald C.

Cook Nuclear Plant Units 1 and 2

CONFIRMATORY ACTION RESPONSE VALIDATIONINSPECTION

RESPONSE

TO REQUEST FOR ADDITIONAL INFORMATION REGARDING ITEM 3, "36 HOUR COOLDOWN" During the time period January 9,

1998, through January 23,

1998, the NRC conducted a confirmatory action letter (CAL) followup inspection.

During the exit meeting for the inspection, on January 26,

1998, we were requested to docket additional information regarding CAL item 3, involving the ability of the plant to be cooled down in 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.

Attachment 1 to this letter contains the information requested.

Attachment 2 contains a flow chart depicting the information in attachment 1.

Sincerely, EF~pm E. Fitzpatrick Vice President

/vlb Attachments J.

A. Abramson A. B. Beach MDEQ -

DW fc RPD NRC Resident Inspector J.

R.

Sampson 9802i20308 980i29 PDR ADQCK 050003i5

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ATTACHMENT 1 TO AEP:NRC:1260G8 ADDITIONAL INFORMATION RELATED TO 36 HOUR COOLDOHN CONFIRMATORY ACTION LETTER ITEM 3

Attachment 1 to AEP:NRC:1260G8 Page 1

Introduction Item 3 of the confirmatory action letter (CAL) dealt specifically with the 36 hour4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> cooldown.

During the CAL validation inspection, several concerns were raised by the NRC relating to this issue.

This letter is provided to assist with the characterization of

'hose concerns.

From August 4, 1997, through September 12, 1997, the NRC conducted an architect engineering (AE) inspection at Cook Nuclear Plant.

During that inspection, several deficiencies were identified related to the component cooling water (CCW) system.

Two such deficiencies were:

the 36 hour4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> cooldown analysis completed by Westinghouse for Cook Nuclear Plant contained

errors, and no maximum cooling flow limits existed to protect the components cooled by CCW from high, potentially damaging flow rates.

Subsequently, concurrent efforts were undertaken to correct the cooldown analysis and establish maximum flow limits.

On August 29,

1997, condition report (CR) 97-2378 was written to capture the AE inspector's concern that maximum flow limits for the CCW system did not exist.

The condition report investigation was completed on December 20, 1997.

As part of that investigation, technical reviews were completed that established an upper flow limit for each of the components cooled by the CCW system.

A commitment was made in that CR response to incorporate the upper flow limits into the updated final safety analysis report (UFSAR).

The due date for that commitment is April 1999.

The April 1999 date corresponds to the next planned revision of the UFSAR.

As part of the process of updating the

UFSAR, a

10 CFR 50.59 evaluation is performed.

On September 19, 1997, the NRC issued a CAL to Cook Nuclear Plant.

The CAL detailed eight specific items that require resolution prior to restart, one of which is the 36 hour4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> cooldown issue.

In our letter AEP:NRC:1260G3, dated December 2, 1997, we provided our CAL response to the NRC.

From January 9,

1998, to January 23,

1998, the NRC conducted a CAL validation inspection to review and verify the CAL response.

Discussion During the validation inspection, the NRC reviewed CAL Item 3, 36 hour4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> cooldown.

The review was two-fold.

First, the NRC reviewed the actual plant cooldown calculation completed by Westinghouse, as well as the supporting documentation that had been compiled by both us and Westinghouse.

That documentation included Westinghouse's safety evaluation check list (SECL)97-189, and our 10 CFR 50.59 evaluation completed for the 36 hour4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> cooldown. It was determined

that, during a 36 hour4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> cooldown, the CCW supply temperature may exceed the previously analyzed 95~ F and reach a maximum of 120~ F.

As part of design change 12-DCP-855, the necessary technical reviews and plant modifications were completed to allow the CCW

Attachment 1 to AEP:NRC:1260GB Page 2

supply temperature to reach 1204 F.

In this letter, the 10 CFR 50.59 evaluation that was completed for 12-DCP-855 is referred to as the 36 hour4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> cooldown safety evaluation.

Upon reviewing the Westinghouse cooldown calculation, the NRC questioned two of the inputs used in the analysis.

One question dealt with the total CCW flow. In the analysis, the total CCW flow rate was 8,000 gpm (i.e.,

4.0E6 lb./hr.).

This value was taken directly from table 9.5-3 of the UFSAR.

The NRC expressed concern that there was no margin between the analysis input value and the UFSAR value.

To address the concern, a 10 CFR 50.59 evaluation was expedited to revise the UFSAR to allow 9,000 gpm of total CCW flow through a single CCW heat exchanger.

As discussed

above, the need for this 10 CFR 50.59 review had already been recognized and committed to as part of the investigation of CR 97-2378.

It is important to recognize that the analysis input of 8,000 gpm was taken directly from the UFSAR and that the 9,000 gpm value is to be added to the UFSAR to show that margin exists in the cooldown analysis.

Another question dealt with the CCW cooling flow to the residual heat removal (RHR) heat exchangers.

This value was 5,000 gpm in the cooldown analysis.

The NRC inquired whether instrument uncertainty had been applied to the flow value.

The NRC commented that at other plants it was not uncommon to see a flow uncertainty on the order of 1,000 gpm.

To address the concern, we provided the NRC with information showing that the uncertainty in the flow indication loop was only on the order of p200 gpm.

Additionally, the CCW flow to the RHR heat exchanger is on our critical parameters list.

Per a previous commitment made to the NRC in our letter AEP:NRC:1260G3, dated December 2,

1997, instrument uncertainty will be incorporated into the operating procedures for each value on the critical parameters list.

This commitment has a

due date of December 31, 1998.

Thus, the issue about uncertainty in the CCW cooling flow rate to the RHR heat exchangers is already scheduled to be addressed under a pxevious commitment. to the NRC.

In addition to reviewing the actual cooldown calculation, the NRC also reviewed the supporting documentation.

Included in that documentation was SECL 97-189 completed by Westinghouse to support operation of the CCW system at. the elevated supply temperature of 1204 F.

In their

SECL, Westinghouse stated the control valve.

regulating the CCW flow to the letdown heat exchanger will go full open during a 36 hour4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> cooldown.

The NRC noted that Westinghouse

assumed, with the valve full open, a total CCW flow of 1,000 gpm through the letdown heat exchanger.

The inspector pointed out that table 9.5-2 of the UFSAR lists the design CCW flow to the letdown heat exchanger as 984 gpm and questioned why the apparent discrepancy was not called out in the safety review.

The following explanation was provided.

The actual design cooling flow rate for the letdown heat exchanger is 492,000 lb./hr. - a mass flow rate, not a volumetric flow rate.

This is shown in table 9.2-3 of the UFSAR.

The flow rate of 984

gpm, as shown in table 9.5-2 of the

UFSAR, is the volumetric flow rate that corresponds to 492,000 lb./hr. at standard conditions.

The flow rate of 1,000

gpm, as shown in the

SECL, is the volumetric flow rate that corresponds to 492,000 lb./hr.

at the CCW return temperature expected during a

36 hour4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> cooldown.

Thus, the volumetric flow rates of 984 gpm and 1,000 gpm are both correct as they are both derived from the design mass flow rate specified for the letdown heat exchanger.

Attachment 1 to AEP:NRC:1260G8 Page 3

As a follow up question to the one above, the NRC asked how much CCW flow is expected to pass through the letdown heat exchanger with the control valve full open.

A preliminary calculation determined with the control valve full

open, approximately 1,400 gpm would pass through the letdown heat exchanger.

The NRC further questioned why the flow rate, which is greater than the value listed in the

UFSAR, was not evaluated in the 36 hour4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> cooldown safety evaluation.

To address the immediate concern, a

10 CFR 50.59 evaluation was expedited to evaluate twice the design cooling flow rate through the letdown heat exchanger (approximately 2,000 gpm).

As discussed

above, the need for this 10 CFR 50.59 review had already been recognized and committed to as part of the investigation of CR 97-2378.

Although the letdown heat exchanger cooling flow rate of 1,400 gpm was not specifically addressed in the 36 hour4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> cooldown safety review, a bounding analysis had been completed and a commitment to revise the UFSAR already existed. It is important to recognize

that, although the increased CCW flow rate to the letdown heat exchanger is a consequence of the higher CCW supply temperature, it is not an input in the cooldown analysis.

ATTACHMENT 2 TO AEP:NRC:1280G8 FLOW CHART DEPICTING INFORMATION PROVIDED IN ATTACHMENT 1

hccacbsienc 2 so AEP/NRCI126008.

QUESTION: The cakuhtion assumes 5000 gpm of CCW coohng flowto the RHR heat exchanger.

Was hstrument uncertainty appfied?

ANSWER: The CCW ihw to the RHR heat exchangers is on the critical parameters gsL All procedures which reference the 5000 gpm used in the analysts wfllbe revised to account for instrument uncertainty. This ls a gbbal comnitment to the NRC which is due by the end of 1998.

r NRC/AE,INSPECTION August-September 1997 CALITEM¹3 36 Hour Cooldown I

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NRC Inspector Reviewed Westinghouse Plant Cooldown Analysis NRC Inspector Reviewed Westinghouse SECL and Our Safety Evaluation QUESllON; The cooldown analysis assumes a total COW lhwof8000 gpm. The FSAR aflaws a total CCW flawof809 gpm through the COW heat exchanger.

Wiryis there no margin between the osculation hpul and the phot design basis?

QUESTION: Westinghouse stated that the COW control valve for the letdown heat exchanger wgl go fuflopen.

Using a CCW flaw rate of 1000 gpm to the letdown heat exchanger, they cahuhted the magnum letdown temperature.

The FSAR states that the CCW Ihwto the letdown heat exchanger Is 984 gpss Why wasnl this addressed in lhe safety evahation?

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I RESOLUTION: The 50.59 review to aflaw 9000 gpm through the CCW heat exchanger was expedited.

(Comphted 1/23/98)

RESOLUTION: As shawn h the FSAR, the design flawfor the letdown heat exchanger is 492,000 ib/hr. This is equfiratent to 984 gprn at 76 'F and 1000 gpm at 120'F.

Westinghouse correcfly used 492,000 Ib/hr to cahutate Ihe temperature.

'0 Subsequent to the hspection, a technkst review was completed to determine a maximum aflowabh caofing ihw rate for each component served by CCW. (CR 97-2378)

The maxhxrm aflawabfe ihwthrough the CCW heat exchanger is 9000 gpm.

Completed 12/2N97, The maximum aflawable llaw through cooflng fhw through the letdown heat exchanger Is twice design (l.e. 984,000 lb/br).

ted 12/20/97.

Apart F convnitment was made In corxfitian report 97-2378 to hcorporate the maximum flaw fimitshto the FSAIL Commitment made:

11/23I97 Commitment due: Apnl 1999 QUESTION: Ifthe control valve does go fuflopen, what wiflbe the CCW fhwrate to the letdown heat exchanger?

ANSWER With the control valve fullopen, the CCW flow wg be approxhnatety 1400 gpm..This Is greater than the design fhwrate shown h the FSAIL RESOLUTION: The 50.59 review to aihw twice design flawrate through the letdown heat exchanger was expefited.

(Completed 1/23lg