ML13030A401

Request for Additional Information E-mail, Relief Request 49, Alternative to ASME Code Section XI for Reactor Vessel Head Flange Seal Leak Detection Piping, Third 10-Year Inservice Inspection Interval (TAC MF0447-MF0449)

ML13030A401
Person / Time
Site:	Palo Verde
Issue date:	01/30/2013
From:	Lauren Gibson Plant Licensing Branch IV
To:	Roehler R Arizona Public Service Co
Gibson L
References
TAC MF0447, TAC MF0448, TAC MF0449
Download: ML13030A401 (3)

Text

Lent, Susan From: Gibson, Lauren Sent: Wednesday, January 30, 20132:40 PM To: 'Robert. Roehler@aps.com'

Subject:

RAls for RR49 Reactor Vessel Head Flange Seal Leak Detection Piping (TAC Nos. MF0447, 8,9)

Attachments: MF0447 RAls.doc Rob, By letter dated December 19, 2012 (Agencywide Document Access and Management System (ADAMS)

Accession No. ML12361A256), Arizona Public Service Company (APS, the licensee) submitted "Reactor Pressure Vessel Head Flange Seal Leak Detection Piping - Relief Request No. 49" for U. S. Nuclear Regulatory Commission (NRC) review and authorization. The licensee has proposed an alternative to the system leakage test of reactor pressure vessel (RPV) flange leak-off line that is required by the American Society of Mechanical Engineers (ASIVIE) Boiler and Pressure Vessel Code (Code),Section XI, Table IWC 2500-1, Examination Category C-H, at Palo Verde Nuclear Generating Station (PVNGS), Units 1,2, and 3.

Specifically, instead of pressurizing the subject lines to the system leakage test pressure required by IWC-5221, the licensee proposes to pressurize the line using the static pressure head of the refueling water prior to performing a VT-2 visual examination. In order to complete our review, the staff requests the following additional information.

The Nuclear Regulatory Commission (NRC) staff has reviewed the submitted information and determined that the additional information identified in the enclosure is needed to complete its review.

On January 30, you confirmed a response date of February 22, 2013.

Thank you, Lauren Lauren K. Gibson Project Manager Columbia Generating Station Palo Verde Nuclear Generating Station Division of Operatillg Reactor Licensing U.S. Nuclear Regulatory Commission (301) 415-1056 1

REQUEST FOR ADDITIONAL INFORMATION REACTOR VESSEL HEAD FLANGE SEAL LEAK DETECTION PIPING - RELIEF REQUEST NO. 49 ARIZONA PUBLIC SERVICE COMPANY PALO VERDE NUCLEAR GENERATING STATION, UNITS 1,2, AND 3 DOCKET NOS. SO-S28, SO-S29, AND SO-S30 By letter dated December 19, 2012 (Agencywide Document Access and Management System (ADAMS) Accession No. ML 12361A2S6), Arizona Public Service Company (APS, the licensee) submitted "Reactor Pressure Vessel Head Flange Seal Leak Detection Piping - Relief Request No. 49" for U. S. Nuclear Regulatory Commission (NRC) review and authorization. The licensee has proposed an alternative to the system leakage test of reactor pressure vessel (RPV) flange leak-off line that is required by the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (Code),Section XI, Table IWC-2S00-1, Examination Category C-H, at Palo Verde Nuclear Generating Station (PVNGS), Units 1, 2, and 3.

Specifically, instead of pressurizing the subject lines to the system leakage test pressure required by IWC-S221, the licensee proposes to pressurize the line using the static pressure head of the refueling water prior to performing a VT-2 visual examination. In order to complete our review, the staff requests the following additional information.

1. What are the scheduled end dates for the PVNGS, Unit 1,2, and 3 third 10-year inservice inspection interval?

2. The proposed alternative is being submitted pursuant to Title 10 of the Code of Federal Regulations, Part SO (10 CFR SO), paragraph SSa(g)(S)(ii), revised inservice inspection program for a facility conflicts with the technical specification for the facility, but cites the provisions of 10 CFR SO.SSa(a)(3)(ii), hardship without a compensating increase in the level of quality and safety. Please confirm that the relief request is being submitted pursuant to 10 CFR SO.SSa(a)(3)(ii).

3. Provide a brief description of the operation of the RPV flange seal leak detection system, i.e., how the pressure in the leak-off line is measured and monitored, how the operators are alerted to a leakage condition and how they respond.

a. If O-ring leakage trips the leak-off alarm and rapid depressurization of the leak-off line subsequently occurs, does the control room annunciator continue to show an indication?

b. Are there other control room indications of O-ring leakage?

4. Provide a piping and instrumentation diagram (P&ID) and a piping isometric drawing showing the RPV flange seal leak detection piping.

S. What is the material of construction of the leak-off line?

ENCLOSURE

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6. Describe PVNGS experience with degradation (corrosion, stress corrosion cracking, fatigue, etc.) of the RPV flange seal leak detection piping.

7. Potential O-ring leakage during service is detected with a pressure element in the leak off line. The proposed alternative would utilize the static fluid head of the refueling water to pressurize the leak-off line prior to a VT-2 examination.

a. What is the fluid head pressure that exists in the line when the refueling cavity has been filled to its normal refueling water level?

b. What is the trip pressure for the O-ring leakage alarm indication in the control room?

8. Discuss whether a system leakage test of the RPV flange seal leak detection piping could be performed at a pressure higher than that of the refueling water fluid head prior to removing the head at the beginning of the refueling outage. Describe any hardship associated with this sequence.

9. In order for a fluid leak in a pressurized line to be observed with a VT-2 examination, sufficient time must have elapsed between the time that the line was pressurized and the time that the examination is performed. Specify the minimum time between the time that the line is pressurized and the time that the VT-2 examination is performed for both uninsulated lines and insulated lines (as appropriate). Provide a technical justification based on the pressure in the leak-off line during the leakage test for the hold time.