PY-CEI-NRR-2428, Submits Resolution to Seventh Question Proposed within NRC 980615 RAI Relating to Cooling Water Sys That Serve Containment Air Coolers & Assessment,Post Accident,Of Potential Water Hammer & two-phase Flow Conditions

Submits Resolution to Seventh Question Proposed within NRC 980615 RAI Relating to Cooling Water Sys That Serve Containment Air Coolers & Assessment,Post Accident,Of Potential Water Hammer & two-phase Flow Conditions

ML20212C322
Person / Time
Site:	Perry
Issue date:	09/16/1999
From:	Jeffery Wood CENTERIOR ENERGY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GL-96-06, PY-CEI-NRR-2428, TAC-M96850, NUDOCS 9909210235
Download: ML20212C322 (3)

Text

9s - k FenoC Perry Nuclear Power Plent i

i Pe ,o 4408 Jahrs K. Woont 440 280 5224 Vke President, Nuclear Fax:440-280u8029 September 16,1999 PY-CEl/NRR-2428L United States Nuclear Regulatory Commission Document Control Desk Washington, D.C. 20555 Perry Nuclear Power Plant Docket No. 50-440 Final Resolution of Generic Letter 96-06 issues (TAC No. M96850)

Ladies and Gentlemen:

In a letter dated June 15,1998, the NRC issued a Request for Additional Information (RAl) conceming the response to Generic Letter (GL) 96-06, " Assurance of Equipment Operability and Containment Integrity During Design Basis Accident Conditions" for the Perry Nuclear Power Plant (PNPP). The RAI is related to the cooling water systems that serve containment air coolers and the assessment, post accident, of potential water I hammer and two-phase flow conditions. The PNPP staff responded to this letter on August 31,1998 (PY-CEl/NRR-2320L). In this RAI response letter a commitment was made to provide resolution to the seventh question at a later date.

Attachment 1 documents the resolution of the seventh question proposed within the RAI ,

letter referenced above. Attachment 1 also provides an explanation of the resolution of l the GL 96-06 issue of thermally-induced pressurization of piping runs which penetrate the PNPP containment.

There are no new regulatory commitments contained in this letter or its attachment.

, if you have any questions or require additional information, please contact Mr. Gregory A. Dunn, Manager - Regulatory Affairs, at (440) 280-6305.

Ve truly yours, ,

/

Attachment cc: NRC Region 111 NRC Resident inspector h0 NRC Project Manager sh nf, 9909210235 990916 PDR ADOCK 05000440' P PDR

_ _ __ ____ - ___________-_A

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Attrchmtnt 1 PY-CEl/NRR-2428L Page 1 of 2 I

RESOLUTION OF RAI- QUESTION 7 Question 7 from an NRC letter dated June 15.1998

" Describe in detail any plant modifications or procedure changes that have been made or are planned to be made to resolve the water hammer and two-phase flow .

issues, and provide schedules for completing these actions."

Oriainal response to Question 7. from Auaust 31.1998 Letter to the NRC "An appropriate engineering analysis should be completed to address the conditions associated with a postulated pipe rupture in the NCCS, post accident, or in lieu of

' this analysis, the associated step of the PEls to bypass the isolation interlock for the Nuclear Closed Cooling System will be removed or appropriately modified. The analysis or the instruction change will be completed by 6/1/99."

The response to Question 7 above was considered to be a regulatory commitment.

l Resolution of Question 7

)

An engineering analysis to address the conditions associated with a postulated pipe rupture in the Nuclear Closed Cooling System (NCCS) as referenced in the above commitment has been completed. An engineering calculation has determined that at Drywell temperatures below 250' F, the potential for a NCCS pipe rupture from water hammer or two-phase flow phenomena is eliminated. The basis for this conclusion is that the minimum saturation temperature at post accident conditions is greater than 250 F. Therefore, post accident, if the Drywell temperature is determined to be below 250' F, the NCCS is not subject to conditions conducive to the development of a vapor void in the piping, and the NCCS supply isolation interlock may be bypassed.

- As a result of this engineering analysis, the associated step of the Plant Emergency Instructions (PEls) to bypass the isolation interlock for the NCCS, post accident, has been modified to require a Drywell temperature below 250 F to permit use of the bypass.

r PLANT MODIFICATIONS INCORPORATED TO RESOLVE THE GL 96-06 ISSUE OF THERMALLY-INDUCED PRESSURIZATION OF PIPING RUNS PENETRATING CONTAINMENT ,

in a May 30,1997 letter to the NRC (PY-CEl/NRR-2174L), it was noted that eleven

-(11) piping penetrations would be modified to eliminate their susceptibility to thermally-induced overpressurization. These modifications were completed prior to  ;

the start of PNPP's Refuel Outage 7 to address the containment overpressurization I concern, in lieu of heat transfer and/or structural analysis of the associated pipe segments.

l

, .. L Attachm:nt 1 PY-CEl/NRR-2428L Page 2 of 2 The following table outlines the plant piping systems impacted and the methods employed to address the GL 96-06 issue of therme!!y-induced overpressurization.

System System Penetration Resolution Method Designation Designation Condensate 1 Transfer and Storage P11 P111 Procedurally Drained  ;

2 Fuel Pool Cooling installed Pressure and Cleanup G41 P301 Relief Device Mixed Bed Water Demineralizer and installed Pressure i 3 Distribution P22 P309 Relief Device Nuclear Closed Installed Pressure 4 Cooling P43 P311 Relief Device Containment 5 Vessel and Chilled Installed Pressure Water P50 P405 Relief Device 6 Fire Protection P54 P406 Procedurally Drained Reactor Post 7 Accident Installed Pressure Sampling /Drywell Relief Device /

Sump Sampling P87 P413* Procedurally Drained Liquid Radwaste Installed Pressure 8 Sumps G61 P417 Relief Device Liquid Radwaste Installed Pressure 9 Sumps G61 P418 Relief Device Liquid Radwaste Installed Pressure 10 Disposal G50 P420 Relief Device Reactor Water Installed Pressure 11 Clean-Up G33 P424 Relief Device

• Penetration P413 contains two post accident sampling lines impacted by GL 96-06 i

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