Text

Surry, Units 1 and 2 - Proposed License Request, Technical Specification Task Force (TSTF) Traveler TSTF-523, Revision 2, Generic Letter 2008-01, Managing Gas Accumulation, Response to Request for Additional Information
	ML16029A078
Person / Time
Site:	Surry
Issue date:	01/25/2016
From:	Sartain M D; Virginia Electric & Power Co (VEPCO)
To:	; Document Control Desk, Office of Nuclear Reactor Regulation
References
	15-330B, GL-2008-01
	Download: ML16029A078 (11)
	v • d • e

VIRGINIA ELECTRIC AND POWER COMPANYRICHMOND, VIRGINIA 23261January 25, 2016 10CFR50.90 U. S. Nuclear Regulatory Commission Serial No.: 15-330BAttention:

Document Control Desk NL&OS/GDM:

R2Washington, DC 20555-0001 Docket Nos.: 50-28050-281License Nos.: DPR-32DPR-37VIRGINIA ELECTRIC AND POWER COMPANYSURRY POWER STATION UNITSI1 AND 2PROPOSED LICENSE AMENDMENT REQUESTTECHNICAL SPECIFICATION TASK FORCE (TSTF) TRAVELER TSTF-523.

REVISION

2. "GENERIC LETTER 2008-01.

MANAGING GAS ACCUMULATION" RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION By letter dated January 14, 2015 (Serial No.14-485),

Virginia Electric and PowerCompany (Dominion) submitted a license amendment request (LAR) to add a Technical Specifications (TS) Surveillance Requirement (SR) to verify the Surry Power Station(Surry) Units 1 and 2 Safety Injection (SI) Systems' locations susceptible to gasaccumulation are sufficiently filled with water. The proposed change addresses theconcerns discussed in Generic Letter 2008-01, "Managing Gas Accumulation inEmergency Core Cooling, Decay Heat Removal, and Containment Spray Systems."

The proposed amendment is consistent with Technical Specification Task Force (TSTF)Traveler TSTF-523, Revision 2, "Generic Letter 2008-01, Managing Gas Accumulation."

By letters dated August 19 and December 3, 2015 (Serial Nos.15-330 and 15-330A,respectively),

Dominion responded to requests for additional information (RAI) from theNRC technical review staff. On December 23, 2015, Ms. Karen Cotton Gross (NRCProject Manager for Surry) sent an email to Dominion requesting additional information to facilitate the NRC review of the LAR. The requested information is provided in theattachment.

As discussed during a conference call on January 7, 2016, NRC andDominion agreed that a response to Question No. 3 was no longer required as it wouldbe adequately addressed by the information being provided in response to theremaining questions.

The information provided in this letter does not affect the conclusions of the significant hazards consideration or the environmental evaluation included in the January 14, 2015LAR.Sptf1 Serial No. 15-330BDocket Nos. 50-280/281 Page 2 of 3Should you have any questions or require additional information, please contactMr. Gary D. Miller at (804) 273-2771.

Respectfully, Mark 0. SartainVice President

-Nuclear Engineering Commitments contained in this letter: None

Attachment:

Response to NRCAmendment Request,TSTF-523, RevisionAccumulation" Request for Additional Information

-LicenseTechnical Specification Task Force (TSTF) Traveler2, "Generic Letter 2008-01, Managing Gas' .NOTAr~y PUBLIC -Comrnonw~lMth or Vir'ginia

_l* ~~Reg. # .140542 .. My Commission 31, 2058COMMONWEALTH OF VIRGINIA)))COUNTY OF HENRICOThe foregoing document was acknowledged before me, in and for the County andCommonwealth aforesaid, today by Mr. Mark D. Sartain, who is Vice President

-NuclearEngineering, of Virginia Electric and Power Company.

He has affirmed before me that he isduly authorized to execute and file the foregoing document in behalf of that company, and thatthe statements in the document are true to the best of his knowledge and belief.Acknowledged before me this d2I"" day * ,t 2016.My Commission Expires:

--5 3i I -Notary Public Serial No. 15-330BDocket Nos. 50-280/281 Page 3 of 3cc: U.S. Nuclear Regulatory Commission

-Region IIMarquis One Tower245 Peachtree Center Avenue, NE Suite 1200Atlanta, GA 30303-1257 State Health Commissioner Virginia Department of HealthJames Madison Building

-7th floor109 Governor StreetSuite 730Richmond, VA 23219Ms. K. R. Cotton GrossNRC Project Manager-SurryU.S. Nuclear Regulatory Commission One White Flint NorthMail Stop 08 G-9A11555 Rockville PikeRockville, MD 20852-2738 Dr. V. Sreenivas NRC Project Manager -North AnnaU.S. Nuclear Regulatory Commission One White Flint NorthMail Stop 08 G-9A11555 Rockville PikeRockville, MD 20852-2738 NRC Senior Resident Inspector Surry Power Station Serial No. 15-330BDocket Nos. 50-280/281 Attachment RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION LICENSE AMENDMENT REQUEST.

TECHNICAL SPECIFICATION TASK FORCE(TSTF) TRAVELER TSTF-523.

REVISION

2. "GENERIC LETTER 2008-01,MANAGING GAS ACCUMULATION" Virginia Electric and Power Company(Dominion)

Surry Power Station Units I and 2 Serial No. 15-3308Docket Nos. 50-280/281 Attachment Page 1 of 7Response to NRC Request for Additional Information License Amendment Request.

Technical Specification Task Force (TSTF) TravelerTSTF-523.

Revision

2. "Generic Letter 2008-01.

Managing Gas Accumulation" Surry Power Station Units I and 2By letter dated January 14, 2015 (Serial No.14-485),

Dominion submitted a licenseamendment request (LAR) to add a Technical Specifications (TS) Surveillance Requirement (SR) to verify the Surry Power Station (Surry) Units 1 and 2 SafetyInjection (SI) Systems' locations susceptible to gas accumulation are sufficiently filledwith water. By letters dated August 19 and December 3, 2015 (Serial Nos.15-330 and15-330A, respectively),

Dominion responded to requests for additional information (RAI)from the NRC technical staff. On December 23, 2015, Ms. Karen Cotton Gross (NRCProject Manager for Surry) sent an email to Dominion requesting additional information to facilitate the NRC review of the LAR. The requested information is provided below.As discussed during a conference call on January 7, 2016, NRC and Dominion agreedthat a response to Question No. 3 was no longer required as it would be adequately addressed by the information being provided in response to the remaining questions.

1. The December 3, 2015 Dominion document stated that the containment spray (CS)suction piping from the refueling water storage tank (RW.ST) involved in the quarterly pump tests consisted of a 4 ft horizontal pipe, a 6 ft vertical downward pipe, a 20 fthorizontal pipe, a 20 ft vertical upward pipe, and a 5 ft horizontal pipe for a total of 43ft. The stated 43 ft total appears to be inconsistent with the individual lengths.Please explain.Dominion ResponseThe 20 feet vertical upward pipe length noted in the response to Question No. 1 inDominion's December 3, 2015 letter should have been 8 feet. The corrected configuration of the CS pump suction piping from the RWST is as follows:

ahorizontal run of 4 feet, a vertical downward run of 6 feet, a horizontal run of 20 feet,a vertical upward run of 8 (versus 20) feet, and a horizontal run of 5 feet for a total of43 feet. As noted in the December 3, 2015 letter, these dimensions areapproximate.

2. The December 3, 2015 Dominion document stated that a Froude number (NFR) >0.55 was sufficient to sweep any gas out of the system during tests. This isconsistent with the NRC safety evaluation (SE) of NEI 09-10 for horizontal andconnected vertically upward pipes, but is inconsistent for a downcomer, where NEI09-10 and the SE concluded that NFR < 0.8 may not remove gas. A similarobservation applies to the Dominion NFR = 0.75 statement.

Please address theseobservations with respect to the Dominion conclusions that the CS quarterly testswill sweep gas voids out of the system. See also Item 5, below, and describe theflow path involved in the quarterly tests.

Serial No. 15-330BDocket Nos. 50-280/281 Attachment Page 2 of 7Dominion ResponseAs stated in Dominion's Nine-Month Response to Generic Letter 2008-01, datedOctober 14, 2008 (Serial No. 08-0013B),

regarding the CS system:"During normal operation the entire CS pump suction line and the discharge lineup to the normally closed isolation motor-operated-valve (MOV) are maintained sufficiently full of water at RWST head. Return to service and/or quarterly IST[in-service testing]

of the pumps at design basis flow further ensures that the CSpump suction piping is maintained full immediately following return to serviceand/or quarterly IST flow testing.

There are no external sources for gas to beintroduced into the CS system on either the pump suction or discharge sideduring normal operation.

In conclusion, the CS pump suction lines are notsusceptible to gas accumulation or entrainment, and the CS pumps are notsusceptible to gas intrusion."

Since the RWST is not drained below the RWST CS suction downward turnedelbow, there is no mechanism for gas to be introduced into the system. Additionally, due to RWST head pressure, there is no degassing, and the solubility effects boundpotential temperature increase effects.The return-to-service procedure and system quarterly tests are performed to ensuredesign functionality and performance.

While the tests provide a minimum NFR of0.75 in the suction piping, versus the NEI 09-10 acceptance criteria value of 0.80, nogas intrusion mechanism exists for the CS systems, and even if any gas voids wereto exist in the system following the return-to-service and/or quarterly tests, theywould be of negligible size.A sketch of the general layout of the CS suction piping configuration is shown inFigure 1 below.CS PumpRWSTSuctionFigure 1Containment Spray Suction Piping Configuration Serial No. 1 5-330BDocket Nos. 50-280/281 Attachment Page 3 of 7If a gas intrusion mechanism were present, the only location that voids couldplausibly exist would be between the two elbows in the short horizontal piping.However, turbulence would occur inside the piping due to the short horizontal pipingconnected to the entrance elbow and the subsequent downward turned elbow. Eventhough the minimum postulated NFR is 0.05 below the NEI 09-10 acceptance criteriavalue, which equates to ~100 gpm, the void would be negligible following eitherreturn-to-service or quarterly testing.A review of the recent CS system test data from November 2015 provided in thetable below indicates the CS system flow rate is approximately 1600 gpm (the lowestmeasured flow rate was 1586.5 gpm, NFR=0.794), which would be sufficient tosweep gas and prevent gas accumulation.

CS Pump Test Sat Range Total Flow Rate NFRMark Number (gpm) (gpm) (Dimensionless) 1-CS-P-lA 1520 to 1636 1586.5 0.7941-CS-P-ilB 1520 to 1640 1596.9 0.7992-CS-P-l1A 1520 to 1839 1676.0 0.8382-CS-P-lB 1530 to 1870 1676.0 0.8383. The December 3, 2015 Dominion document stated that the flow rate during the CSsystem quarterly test was 1500 gpm with NFR = 0.75. Maximum assumed CSsystem flow rate from the RWST following a large loss-of-coolant accident (LOCA) is4500 gpm to which must be added a safety injection (SI) system flow rate of perhaps2500 gpm for that part of the suction piping where flow is shared from the RWST.This appears to result in a condition where the system quarterly test may not removea high point void at the RWST exit pipe but flow initiation following a large breakL OCA would move the void toward the SI and CS pumps. Please address thispotential condition.

Include actions to eliminate the void following an outage thatmay have resulted in void generation.

Dominion ResponseAs discussed during the January 7, 2016 conference call, NRC and Dominionagreed that a response to Question No. 3 was no longer required as each CS pumphas a separate suction tap from the RWST, and the Safety Injection (SI) System hasa separate and independent suction tap. This configuration is shown in Figure 2below.

Serial No. 1 5-330BDocket Nos. 50-280/281 Attachment Page 4 of 7Figure 2Refueling Water Storage Tank4. The flow diagrams and related drawings, including information provided in theDecember 3, 2015 Dominion

document, are not sufficient for the Reactor SystemsBranch staff to evaluate the void-related information that Dominion has provided.

Therefore, please provide isometric drawings that include all valves and piping highpoints that are identified in the Dominion documents submitted in relation to theTSTF-523 license amendment request.

Include the suction piping configuration inside the RWS T.Dominion ResponseAs discussed during the January 7, 2016 conference call, Dominion's response toGL 2008-01 provided the results of the plant system analyses performed byDominion for those systems subject to GL 2008-01.

The NRC technical staffreviewed the GL 2008-01 response documentation, determined that Dominion hadacceptably addressed the GL requests, and indicated the only portion of Serial No. 1 5-330BDocket Nos. 50-280/281 Attachment Page 5 of 7Question No. 4 requiring a response is the last sentence.

(Reference NRC letterdated August 12, 2011; ML110880718)

The suction piping configuration inside the RWST for each CS pump has adownward turned elbow with an enlargement nozzle as shown in the pictureprovided below.Containment Spray Pump Suction Piping in RWSTThe SI System pumps' suction piping connection is a pipe welded to the RWST wallwith no interior piping.5. Does the normal reactor coolant system (RCS) makeup process result in an SIsystem pressure that prevents RCS and accumulator back-leakage into the SIsystem?Dominion ResponseThe SI System lines are designed to independently connect to the RCS System asindicated in the bottom right corner of Figure 3 below. Each RCS loop has aseparate accumulator line connection independent of the High Head Safety Injection (HHSI) and Low Head Safety Injection (LHSI) lines connected to the RCS loop.

Serial No. 15-3308Docket Nos. 50-280/281 Attachment Page 6 of 7Consequently, the accumulators cannot cause back-leakage into the rest of theSI System.Each accumulator is connected to the RCS by a 12-inch line that includes an MOVand two in-series swing check valves. During normal RCS operation (above1000 psig), the MOV is opened and its associated breaker is locked open with thepower removed.

Each accumulator contains a minimum of 975 cubic feet of boratedwater and is pressurized to at least 600 psia with nitrogen.

The two swing checkvalves in each accumulator's injection line prevent back-leakage from the higherpressure RCS into the accumulators.

As stated in the response to Question 4 inDominion letter dated December 3, 2015 (Serial No. 15-330A),

accumulator level istrended to verify there is no leakage from the RCS into the accumulators.

The LHSI and HHSI pumps both discharge into each RCS loop through a 6-inch linethat includes multiple check valves and MOVs. At Surry, the centrifugal chargingpumps also serve as the HHSI pumps. The discharge pressure from the chargingpumps is approximately 2500 psig during charging operations to ensure flow can beinitiated through the charging lines into the RCS system, which is pressurized to2235 psig. The HHSI lines are not flowed during normal charging operations because the HHSI isolation valves are closed. Since the normal charging and HHSIlines are pressurized above RCS pressure, RCS back-leakage into these linescannot occur.The LHSI pumps do not initiate flow into the RCS unless RCS pressure is below 200psig. Since the LHSI System pressure is maintained below the pressure of the RCS,the LHSI pumps' discharge lines are protected from RCS back-leakage by twoin-series swing check valves. Surry performs quarterly ultrasonic testing of the LHSIpumps' discharge lines to check for potential gas accumulation.

The proposed TSsurveillance primarily addresses this section of piping.

Serial No. 1 5-330BDocket Nos. 50-280/281 Attachment Page 7 of 7HotsLogs~-I-~*-kFromRHRt -. cFigure 3Safety Injection System VIRGINIA ELECTRIC AND POWER COMPANYRICHMOND, VIRGINIA 23261January 25, 2016 10CFR50.90 U. S. Nuclear Regulatory Commission Serial No.: 15-330BAttention: