05000219/LER-1997-004, Adds Oyster Creek Nuclear Generating Station Rwcs Valve V-16-2 to Scope of GL 89-10,suppl 3 Valves IAW Corrective Actions Identified in LER 97-04,dtd 970425.Description Design Basis Conditions Established for RWCU Valve,Encl

Adds Oyster Creek Nuclear Generating Station Rwcs Valve V-16-2 to Scope of GL 89-10,suppl 3 Valves IAW Corrective Actions Identified in LER 97-04,dtd 970425.Description Design Basis Conditions Established for RWCU Valve,Encl

ML20198S645
Person / Time
Site:	Oyster Creek
Issue date:	11/05/1997
From:	Roche M GENERAL PUBLIC UTILITIES CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
6730-97-2246, GL-89-10, NUDOCS 9711140080
Download: ML20198S645 (3)

LER-2097-004, Adds Oyster Creek Nuclear Generating Station Rwcs Valve V-16-2 to Scope of GL 89-10,suppl 3 Valves IAW Corrective Actions Identified in LER 97-04,dtd 970425.Description Design Basis Conditions Established for RWCU Valve,Encl

Event date:
Report date:
2192097004R00 - NRC Website

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CPU Nuclest. inc.

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g U $ Route #9 South l NUCLEAR f,*,*,',*,j',l*j$m m Tel 609-9714:10 0 ,

(609)971 4814 November 5. 1997  !

6730 97-2246 l U.S. Nuc ear Regulatory Commission Attentim: Document Control Desk Washington,DC 205)$

Gentlemen:

Subject:

Oyster Creck Nuclear Generating Station (OCNGS)

Docket No. 50 219 Facility Operating License No. DPR 16 Generie Letter 89 10, Supplement 3 Additional lnformation This letter adds OCNGS Reactor Water Cleanup (RWCU) System valve V-16-2 to the scope of OCNGS Generic Letter (GL) 89-10, Supplement 3 salves in accordance with corrective actions identined in OCNGS Licensee Event Report (LER) 97-04, dated April 25,1997 (6730-97 2124).

The attachment to this letter provides a description of the design basis conditions established for RWCU System containment isolation valve V 16-2. This valve has been modified to allow sufGeient motor actuator torque to enable the valve to isolate an RWCU System high energy line break (llELil) with a full reactor coolant system differential pressure of 1030 psid. The results of this GL 89.10 Supplement 3 assessment confirm that valve V-16 2 is capable of developing sufficient thrust to perfonn its intended safety function under postulated worst case design basis conditions, including nominal and degraded voltage conditions.

If any addi!ional infomiation is required, please contact hir. David J. Distel, Regulatory Affairs, at (20l)316 7955.

Sincerely, w- ,

(or hiichael11. Roche Vice Presidemand Director

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Oyster Creek i hillR/DJD

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/\-OltN 1 Cc: Administrator, Region 1 OCNGS NRC Senior Residentinspector OCNGS NRC Senior Project hianager

[0,1r; r :JRC Region 1-T. Kenny g'gh,N.hk 9711140000 971105 '

POR ADOCK 05000219 P PDR ,

ATTACilMENT Reactor Water Cleanun System Supplv 1 ine Valve V-16 2

. V-l6 2 is a 6 inch,900 lb. solid wedge Ilirata gate valve. The valve disc and body guide material is stainless steel and the disc and body seat materialis stellite.

V-16 2 is a DC powered parallel outboard containmentisolation valve in the reactor coolant system (RCS) supply to Reactor Water Cleanup (RWCU) System. Its normal function is to provide the flowpath to the RWCU Auxiliary pump, which is used to induce flow through the RWCU system at low reactor pressures,when RCS pressure induced flow is inadequate. It is also used at power to fill and pressurire the RWCU system prior to restoring the system to service. This is accomplished by opening V 16 2 prior to opening valve V 1614,to fill the system via the 1 inch Auxiliaryp ump '

Bypass line. The safety function of the valve is to isolate tmon receipt of a Ili Drywell and/or Lo-Lo Water level signal. An additionaldesign safety basis e o isolate on Liquid Poison flow to prevent dilution or loss of baron. The valve also automaticallyisolates upon receipt of the fbilowing signals:

1) Low filter flow

2) Nonregenerative heat exchanger high outlet temperature

3) Cleanup auxiliary pump high cooling water outlet temperature

4) System high pressure in the low pressure piping.

The Generic Letter (GL) 89 10 design basis lbr this valve is revised such that it must also isolate in the event of a high energy line break (llELB)in the system piping outside the drywell. The worst case operating condition for V-16 2 is the postulated !!ELB of the RWCU piping outside containment during normal operation with V 16 2 open to fill and pressurize the RWCU system.

An additional single failure of V-16-1 in the open position is assumed which produces a differential pressure across V-16-2 of 1030 psid.

The fbilowing modificationsto V-16 2 have been completed:

1) Bypass torque switch in closing direction to beyond flow isolation.

2) Bypass the thermaloverload heater.

These modificationsensure full operator capability is available to isobte an RWCU llELB and optimizes the available operator torque by reducing the voltage drop to the motor.

V-16-2 has the capability ofisolating a RWCU llELB at valve factors less than or equal to 0.96 when considering the as measured stem friction coefficient based on latest available test data, adjusted ihr rate ofloading, and as-measured valve running load. Ilowever,in order to meet the 60 second stroke time criteria,the maximum valve factor capabilityis 0.88. Avmlable EpRl/INEL test data fbr valves subjected to hot blowdown conditions similar to those which might exist for V-16-2 (1030psid,520 F) indicate a maximum apparent valve factor of 0.86 to flow isolation (EpRI data based on highest value observed. INEL data based on first blowdown valve stroke). Therefore, V 16-2 (as modified)is capable ofisolating a RWCU 1IELB under blowdown conditions since the available valve factor bounds EpRl/lNEL test data.

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. To issess the new design basis requirement Ihr V 16 2 ofI11!!.11 isolation (higher valve factor and DP thrust requiremein), credit is taken for voltage supplied by the battery charger at isolation and accoun:s fbr voltage drop to 'he motor terminals. This is supported by the following bounding accident scenarios:

1) For isolation under Gli Sil 604 conditions (ItWCl.' 111!!.11 with Feedwater that does not '

result in an automatic reactor scram), the battery charger voltage of 129VDC is considered available. This is acceptable because the scenario dictates that offsite power remains available(in order to drive the Fecdwater pumps). For this Design liasis Accident (Dil A)it is reasonable to consider that the battery charger is operating per design. IIxisting plant procedures maintain this voltage.

2) For d.e lil!! Il scenario concurrent with a 1,oss of Of fsite Power, the Itattery Charger will automaticallyrestart upon return of AC power via liDGs. This scenario was analyzed based on 124,49 VDC, livent specific plant tests show a voltage recovery to greater than 127 VDC.

For this scenario, the valve could begin stroking while poucred from the battery and the battery charger would be restored prior to the valve achieving flow isolation,thus assuring the valve can perfbrm its design basis isolation function.

For both conditions,the battery charger is available to supply the necessary voltage to support the valve seating requirements. Voltages taken credit Ihr in the above analysis assume only one DC valve is closing. Therefbre, valves V 16 2 and V-1614 are presently resisted administratively from both being open while the 11WCU system downstream is susceptible to a l1111.11.

The design basis capability fbr V-16-2 is demonstrated using a dynamic stem friction coeflicient of 0.099. This value is based on the as left static stem friction coeflicient based on the latest static test (0.053)and is adjusted to account for rate of loadingusing the !! Pill Peribrmance Prediction Methodology (!! Pit! Tit 103237."l! Pill MOV Perfonnance Prediction Program Topicaliteport").

The above assessment demonstrates the design basis capability of11WCU isolation valve V-16 2 to close against Ihll 11CS pressure under hot blowdown conditions.

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