ML20204H249

Application for Amend to License NPF-3,revising Tech Specs to Delete Requirement for Auxiliary Feed Pump Turbine Inlet Steam Pressure Interlock

ML20204H249
Person / Time
Site:	Davis Besse
Issue date:	11/05/1984
From:	Crouse R TOLEDO EDISON CO.
To:
Shared Package
ML20204H239	List: ML20204H236 ML20204H249 ML20204H257
References
TAC-56793, NUDOCS 8411120229
Download: ML20204H249 (6)

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APPLICATION FOR AMENDMENT TO FACILITY OPERATING LICENSE NO. NPF-3 FOR DAVIS-BESSE NUCLEAR POWER STATION

', UNIT NO. 1

- Enclosed are forty-three (43) copies of the requested changes to the Davis-Besse Nuclear Power Station Unit No. 1 Facility Operating License No. NPF-3, together with the Safety Evaluation for the requested change.

The propcsed changes include Section 4.7.1.2.d.

ny /s/ R. P. Crouse Vice President, Nuclear Sworn and subscribed before me this 5th day of November, 1984.

/s/ Laurie A. Hinkle, nee (Brudzinski)

Notary Public - State of Ohio My Comission Expires May 16, 1986 SEAL t' b 8411120229 841105 PDR ADOCK 05000346 P- PCR

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Docket No. 50-346 License No.-NPF-3 Serial No. 1096 November 5, 1984 Attachment

Si . I._ Changes to Davis-Besse Nuclear Power Station Unit 1, Appendix A

Technical Specifications Section.4.7.1.2.d.

A.- Time required to Implement. This change is to be effective upon NRC approval.

"B. . Reason for Change (Facility Change Request 84-146 Rev. A).

Interpretation of SRP 3.6.2 allows evaluation of the high energy steam inlet line to a moderate energy line under certain criteria, which the~AFPT steam linlet linas meets, thereby deleting the requirement for the interlock. Also, the removal of the Al?T inlet' steam pressure interlock will increase the AFW system reliability.

C. Safety Evaluation

-(See Attached)

D. Significant Hazard Consideration (See Attached)

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SAFETY EVALUATION This amendment. request is'for'the deletion of the low pressure switch

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2 Linterlocks;in the main steam-lines to the Auxiliary Feedwater Pump J [ Turbine' (AFPT) ' inlets. . The safety- function .of these switches is to Ldetect;a' high energy pipe break in their respective lines and initiate

' isolation of the break.

.M LThe'effect of removing the pressure' switches is to eliminate a valve

closure signal and: isolation of the line-due to low pressure in the

line. 'As currently designed PSL-106A,B.C.D and PSL-107A,B C.D provide

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1cnr pressure sensing in the EBD-1911ine .(Main Steam Supply to the AFPT)

Land initiate a ' signal l for valves _ MS-106,106A.and MS-107,107A to

close. During normal plant operation these valves are closed and the lines between these valves'and the AFPT are depressurized. - Upon an

- lAuxiliary Feedwater System _(AFWS) actuation MS-106 and MS-107 receive

-faniopen signal and,-ti.ereby, establish a single flow path from each steam generator to the corresponding AFPT. If there is insufficient

/ pressure-in the'line after a time delay, implying that there.is a break fV Linlthe line, the pressure switches initiate a signal to close the

. proper valves and, thereby, isolate that segment of the-line.

. The steam 'line to the. AFPT inlet has been considered as a high energy

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fluid system per the;FSAR/USAR_ commitments which were based upon the information presented in the'Giambusso letter of December 15, 1972.

-Initially the AFPT inlet was installed with steam pressure interlocks

, to mitigate the effects'of a high energy pipe rupture. Standard Review

. Plan <(SRP)'3.6.2 titled " Determination of Rupture Locations and Dynamic

-Effects Associated with the Postulated Rupture of Piping" and its

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attached Branch Technical Position (BTP) MEB 3-1. indicate that this ipiping may. now be evaluated with moderate energy postulated = pipe breaks

-instead of high' energy, based on~ operational time. This SRP and BTP were issuad in November, 1973,.after Davis-Besse Unit I was designed.

LPreviously, no criteria existed in qualifying high energy fluid systems with regard to operational time. MEB 3-1 provides this criteria and

-stipulates that if a system is subjected to high energy temperature _and 4 pressure criteria less than 2% of.the plant operating time, moderate energy criteria may be applied to-thatEline. This steam line is ANSI ~B31.1, is seismically' analyzed, is nuclear safety related, is not used during normal plantLoperation,:is not used during normal plant

- startup or shutdown, and is not operated more than 2% of the time. It,

, therefore.: meets the requirements of MEB~3-1. Therefore, moderate energy critical ~ pips cracks may be postulated rather than a high' energy cline rupture as currently' postulated and no high energy pipe break

protection is now required. -Room environment created by postulated 1 moderate energy critical cracks has been evaluated and would not be as

severe as the previously evaluation environment created by high energy line breaks with automatic line isolation.

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. Failures of these pressure switches and their associated components will increase the failure rate of the-AFWS. The pressure switches are no

-longer required for detection of postulated high energy line breaks and it is, therefore, desirable to eliminate these unnecessary pressure switches

to. increase the availability of the AFWS.

' Pursuant to the above,-there is no unreviewed safety question.

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"[ ,a ', r. e ~ l SIGNIFICANT HAZARD CONSID'ERATION

This amendment'~ request for-deleting the: Auxiliary Feed Pump Turbine

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-(AFPT).1 Inlet Steam Pressure, Interlocks surveillance requirement does not represent a.Significant Hazard.

3 The AFPT inlet steam pressure interlocks were installed to-isolate the steam line due to low pressure (rupture of AFPT steam line). Upon an

< Auxiliary Feedwater System (AFWS) actuation, the steam inlet valves ireceive an open signal. to provide -steam to' .the AFPT. If there is insufficient pressure in the line after a time delay, the pressure switches initiate a signal to close the appropriate steam inlet valve.

lthereby isolating.that segment of line.-

1The criterion for isolation of the AFPT steam inlet is that these lines-4 ?have been considered a high energy fluid system. This was based on

,;information presented in the Giambusso letter of December 15, 1972.

This resulted in our classification of the AFWS steam inlet lines as a

~high energy line and the: interlocks were installed to mitigate the effects of a high energy' pipe rupture.

" Toledo Edison has reviewed the Standard Review Plan (SRP) 3.6~.2,

" Determination of Rupture Location and Dynanic-Effects Associated with the Postulated' Rupture of Piping" and its attached Branch Technical Position;(BTP) MEB 3-1 as it relates to the AFPT steam line. The BTP stipulates that if a system is subjected to high energy temperature and t pressure criteria less than two percent (2%) of the operating time,

. moderate' energy criteria'may_be applied to that line.- With the appli-cation of the criterion in BTP, the AFPT steam line'may be evaluated using moderate energy line criteria. With this-definition the need for automatic: isolation is no longer required.

This amendment request results from a a' review of the SRP which-specifies whenl moderate energy criteria may be utilized for selective high energy lines.- The pressure interlocks were installed cs a protection in case

'of a rupture of the steam line. With removal'of the interlocks the operator would close the steam inlet valve.upon indication of low RPM of the AFPT and Low Steam Generator outlet pressure. Also, thic will

-increase the overall availability of the AFWS System due to removal of a fpotentiallfailure of an interlock ~and isolation of-an AFPT.

'The' Commission has provided guidance concerning the application of the standards in 10CFR50.92 by providing'certain examples (48FR14870).

0ne of the examples of action involving no significant hazards consider-ations related to's change which either may result in some increase to the

probability or? consequences of a previously-analyzed accident or may reduce ~in some way a safety margin, but where the results of the change are clearly within all. acceptable criteria with respect to the system or component specified in the Standard Review Plan: for example, a change resulting from the application of a small refinement

ofca:previously used calculation model or design method (example vi).

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The potential for increase, probability or consequences of a previously-analyzed accident is very small. The use of the BTP contained in the SRP defines the criterion which did.not exist at the time of original definition of the AFPT steam inlet line. The operator can take appropriate action to mitigate a failure of the steen line.

Based.on the above information, this amendment request would not (1) involve

,a significant increase in the probability or consequences of an accident -

previously evaluated; or (2) create the possibility of a new or different Ekind of accident from any accident previously evaluated; or (3) involve a significant reduction-in a margin of safety.

C Therefore, based on the above, the requested license amendment does not present.a Significant Hazard.

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