ML20151B561

Proposes Rev to Confirmatory Action Ltr CAL-RIII-88-17 & Associated Justifications,Per 880705 Telcon.If Item 7 Requirements Applicable,Restart Will Occur Only After Concurrence of NRC

ML20151B561
Person / Time
Site:	Zion File:ZionSolutions icon.png
Issue date:	07/08/1988
From:	Lentine F COMMONWEALTH EDISON CO.
To:	Davis A NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
4906K, CAL-RIII-88-17, IEIN-85-001, IEIN-85-1, NUDOCS 8807210019
Download: ML20151B561 (6)

Text

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.' N Commonwealth Edison '

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[w 1 / . One First Nabonal Plaza. Chica0o. lilinois

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\ v J Address Reply to: Post Omco Box 767 De Chicago, Illinois 60690 0767 110RITY ROU July 8, 1988 iQ -YJ f $~-

Mr. A. Bert Davis Regional Administrator QW {"

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Region III U.S. Nuclear Regulatory Commission

]f1LEM 799 Roosevelt Road Glen Ellyn, IL. 60137

Subject:

Zion Nuclear Power Station Unit 2 Confirmatory Action Letter-CAL-RIII-88-017 NRC Docket No. 50-304 Reference June 30, 1988 letter from A. Bert Davis to Cordell Reed Dear Mr. Davis This letter confirms a July 5, 1988 telephone conversation between T.J. Malman and E.G. Greenman which informed the NRC of Commonwealth Edison's intention to propose modifications to Confirmatory Action Letter CAL-RIII-88-017. That letter was transmitted on June 30, 1988 and specified a course of action concerning the Auxiliary Feedwater (AFW) check valve backleakage.

Representatives from Zion Station, PWR Engineering and Nuclear Licensing departments have reviewed the CAL and have recommended the following changes. The words of the original CAL, the proposed revision to the CAL, and the justification for the revision are provided for each item.

Item 1 A) Original CAL:

Using Standing Order 88-14 dated June 17, 1988, check the casing temperatures of 2B and 2C AFW pumps on an hourly basis using a contact pyrometer, or contact thermocouples with a strip chart recorder. Report any trend to the Zion NRC Resident Inspector.

B) Revised CAL:

Check the casing temperature of 2B and 2C ATW pumps when operable on an hourly basis using a contact pyrometer or contact thermcouples with a strip chart rr, corder. Periodically report results to the Zion NRC reside t inspector- /

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2 C) Justification:

The reference to a~ specific Standing Order number was' deleted because plant conditions might change in such a way_as to necessitate a revision to the Standing Order. The requirement to perform the-surveillance will be enforced by an appropriate administrative mechanism until the requirement is relieved. The surveillance will be temporarily suspended if the pump is removed f rom service for maintenance or otherwise rendered inoperable.

The reference to "report any trend" was modified to-read; "periodically report the results" in order to ensure that the resident inspector is informed of all the data. This change is suggested to remove any ambiquity that may exist in interpretation

'of the word "trend".

Item 2 A) Original CAL:

In the event that the casing temperatures of 2B or 2C AFW pumps reach or exceed 1500f, the pump casing will be cooled to within 100 F of condensate water temperature by using the casing vent valves and/or the pump started using an approved Zion Unit 2 procedure to equalize'the casing temperature.

B) Revised CAL: In the event that the casing temperatures.of 2B or 2C AFW pumps reach or exceed 1500F, the pump casing will be cooled to less than 1500F by using the casing vent valves and/or the pump started using an approved Zion Unit 2 procedure to equalise the casing temperature, l C) Justification: l l

The reference to the 100F value was deleted because of physical l I

constraints in the AFW system. Specifically, the temperature of the water at the pump suction is approximately 750F and the pump j discharge temperature is approximately 940F when the pump is '

operating at full flow. Therefore, it would not be possible to obtain a 100F delta T between pump suction and pump discharge.

Commonwealth Edison has suggested that pump casing temperatures be monitored and corrective action be taken to ensure that pump casing temperatures are maintained at loss than 1500F.

4 i

_3 Item 3 A) Original CAL:

Complete a walkdown of the affected ArW piping systems inspecting for evidence of pipe hanger, penetrations, equipment anchor or other physical or thermal damage and immediately perform a safety analysis, of any damage identiff.ed, for system operability.

Additionally, during this walkdown determine the temperature gradient, as achievable, of the piping down to 2000 from valve 2rWOO69. Upon completion, report the results to the Zion NRC Resident Inspector. In the event of gas formation, pump binding or water hammer indications, subsequent to the initial walkdown, an additional system walkdown and appropriate. analysis shall be performed and reported to the Zion NRC Resident Inspector.

B) Revised CAL:

Complete a walkdown of the affected AFW piping systems inspecting for evidence of pipe hanger, penetrations, equipment anchor or other physical or thermal damage and immediately perform a safety analysis, of any damage identified, for system operability.

C) Justification:

The station has performed a walkdown of the affected system and did not identify any damage that could be attributable to the check valve leakage.

Determination of the temperature gradient of the piping would be difficult and of little practical valve. Multiple simultaneous measurements would have to be taken along with entire routing of the AFW piping over the full range of operating conditione. Some of this piping is located in inaccessible, radiologically controlled areas in the auxiliary building and containment. For the reasons described in item 4, Commonwealth Edison has proposed to assess the possible effect of thermal cycling by performing  ;

direct NDE examination, in lieu of theoretical stress analysis.

Therefore, temperature gradient data is not needed.

Item 4 A) Original CAL:

Complete a safety analysis of possible thermal stress affects on the affecting ArW systems and components for system operability including the thermal cycles and number of pump starts since the last startup. Upon completion, report the results to the Zion NRC Resident Inspector.

. . 4 B) Revised CAL:

' Assess the possible effect of thermal cycling by performing NDE-examination of the limiting ArW components. This inspection will be performed during the Fall of 1988, Unit 2 refueling outage.

C) Justification:

There are a number of factors that make performance of theoretical stress analyses less than desirable. In addition to the difficulty in obtaining accurate. thermal gradient data described in item 3, there has been no formal record keeping of the number of thermal cycles experienced by ArW components or their time dependence. The lack of accurate historical data would necessitate the use of excessively conservative bounding assumptions and analytical models, which would limit the usefulness of the results. The preferred approach is to examine directly using appropriate NDE techniques the components determined to be most vulnerable to the effects of thermal cycling. These components will be selected  !

following engineering review and the inspection will be planned for the Fall, 1988, refueling outage.

Item 5 A) Original CAL Determine and report to Region III your criteria related to temperatures pressures, pump starts, etc., which if exceeded will be used to establish unit shutdown requirements.

B) Revised CAL: ,

If the ATW pump casing reaches a sustained temperature of 1500 or greater, the ATW pump will be declared inoperable, and the appropriate sections of the existing Technical Specifications will apply.

Justification:

The temperature of the ATW pump casing was determined to be the most limiting parameter and one that could be monitored on an ongoing basis. Therefore, Commonwealth Edison has informed Operating personnel that a sustained pump casing temperature of 1500r or greater will be used to declare the pump inoperable.

Once the pump is declared inoperable because of temperature or any other parameter that affects operability, then the appropriate sections of the existing Technical Specifications will be applied to determine continued operation of the af fected unit.

Item 6 A) Original CAL:

Repair or replacement of valve 2rWOO33 shall commence no later than July 15, 1988.

B) Revised CAL:

Repair or replacement of. valve 2rWOO33 shall commence no later than July 15, 1988.

C) Justification:

No change-to original CAL.

Item 7 A) Original CAL:

If Unit 2 should be shutdown for any reasons and repairs are not completed to valvec 2FWOO32, 2FWOO33, and 2rWOO69 notify RIII prior to restart of the unit.

B) Revised CAL:

If Unit 2 should be shutdown for any reasons and repairs are not completed to valves 2rWOO33 and 2rWOO69, then notify RIII prior to restart of the unit.

C) Justification Zion Station does not have any evidence to indicate that check valve 2rWOO32 is a major contributor to the leakage. Also, any leakage that may exist through check valve 2rWOO32 could be masked by the present leakage through check valve 2rWOO33. After repairs to 2rW0033 are completed, then an assessment of leakage through 2rN0032 would be possible.

Iter 8 A) Original CAL:

Item not addressed i

j B) Revised CAL:

After the repair of FWOO33, continue the surveillances that are' prescribed in Items 1 and 2 until the station determines that it is appropriate to suspend those additional surveillances. The routine surveillances that have normally been performed will remain in effect.

C) Justification:

For some time the statien has been performing routine surveillances of'AFW pump casing temperature, including the qualitative assessments prescribed in IE Bulletin 85-01, "Steam Binding of Aux Feedwater Pumps." These surveillances are considered to be an acceptable ongoing monitoring program. ,

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Commonwealth Edison understands that if the requirements of Item 7 of the revised CAL are applicable, then a restart of Unit 2 will occur only after concurrence of the Regional Administrator or his designee. -

Also, Commonwealth Edison will provide a report of our review, '

analysis and corrective actions that were performed in cor. junction with the CAL.  ;

i In conclusion, Corwonwealth Edison proposes that CAL-RIII-88-017 be  ;

amended as described herein. Please advise us if the conditions as outlined  !

in the proposed revisions are acceptable to your office. (

Please direct any questions th;t you may have to the Nuclear ,

Licensing Department.

Very truly yours, l

F. G. Lentine l PWR Licensing Supervisor

/klj [

cc J.A. Norris-NRR j T.J. Malman j G.J. Pliml i Resident Inspector-Zion 4906K i

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