ML13015A396

RAI Regarding Relief Request I3R-09, Alternative to VT-2 Visual Inspection of Combustible Gas Control System Piping

ML13015A396
Person / Time
Site:	Clinton
Issue date:	01/29/2013
From:	Joel Wiebe Plant Licensing Branch III
To:	Pacilio M Exelon Generation Co
Joel Wiebe, NRR/DORL/ 415-1115
References
TAC ME9428
Download: ML13015A396 (5)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 January 29, 2013 Mr. Michael J. Pacilio Senior Vice President Exelon Generation Company, LLC President and Chief Nuclear Officer (CNO)

Exelon Nuclear 4300 Winfield Road Warrenville, IL 60555

SUBJECT:

CLINTON POWER STATION, UNIT NO.1 - REQUEST FOR ADDITIONAL INFORMATION REGARDING RELIEF REQUEST 13R-09, ALTERNATIVE TO VT-2 VISUAL INSPECTION OF COMBUSTIBLE GAS CONTROL SYSTEM PIPING (TAC NO. ME9428)

Dear Mr. Pacilio:

By letter to the U.S. Nuclear Regulatory Commission (NRC) dated August 23, 2012 (Agencywide Documents Access and Management System (ADAMS) Accession No.

rvlL12236A405), Exelon Generation Company, LLC submitted a reliefrequest 13R-09, proposing an alternative to the American Society of Mechanical Engineers Boiler and Pressure Vessel Code,Section XI, paragraph IWC-5220, system leakage test VT -2 visual examination requirements for the Clinton Power Station, Unit No.1.

The NRC staff is reviewing your submittal and has determined that additional information is required to complete the review. The specific information requested is addressed in the enclosure to this letter. During a discussion with your staff on January 8, 2013, it was agreed that you would provide a response by February 8, 2013.

The NRC staff considers that timely responses to requests for additional information help ensure sufficient time is available for staff review and contribute toward the NRCs goal of efficient and effective use of staff resources.

M. Pacilio -2 If circumstances result in the need to revise the requested response date, please contact me at (301) 415-6606.

Sincerely,

, ~hV;;t (Joel S. Wiebe, Senior Project Manager Plant Licensing Branch 111-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-461

Enclosure:

Request for Additional Information cc w/encl: Listserv

REQUEST FOR ADDITIONAL INFORMATION REGARDING CLINTON POWER STATION, UNIT NO.1 RELIEF REQUEST 13R-09, ALTERNATIVE TO VT-2 VISUAL INSPECTION OF COMBUSTIBLE GAS CONTROL SYSTEM PIPING DOCKET NO. 50-461 (TAC NO. ME9428)

In reviewing the Exelon Generation Company's submittal dated August 23,2012 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML12236A405), in which the licensee proposes to perform local leak rate testing (LLRT) of the Combustible Gas Control system piping at Clinton Power Station, Unit 1, (CPS) as an alternative to the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code),Section XI, paragraph IWC-5220, system leakage test VT-2 examination required by Table IWC-2500-1, Examination Category C-H, the U.S. Nuclear Regulatory Commission staff has determined that the following information is needed in order to complete its review:

1. When is the scheduled end of the CPS third 10-year inservice inspection interval?

2. The column "Pressure Drop Test Duration" in the Table of the proposed alternative might imply that the LLRT is a pressure decay test. Is the LLRT a flow test or is it a pressure decay test? Provide a brief description of the LLRT surveillance procedure CPS 9861.02.

a. If a flow test is being proposed where gas flow rate into the pressurized test volume is measured, what are the pressure stability limits and flow rate stability limits during the test? What is the measurement accuracy of the pressure and flow instrumentation?

b. If a pressure decay test is being proposed where the test volume pressure decay is monitored while the test volume is isolated and since the volume of the lines and components is relatively large, what is the sensitivity of the test? How is the leakage rate determined from the pressure decay test? What is the instrumentation measurement accuracy?

3. Provide a brief description of the procedure used for differentiating in-line leakage of valves from through-wall leakage using Test Sets A, B, and C.

4. The LLRT administrative limits of 1000 standard cubic centimeters per minute (sccm) for Train 'A' and 500 sccm for Train 'B' are significantly below the overall secondary containment bypass limit of 28,882 sccm, but are significantly above the practical leak test sensitivity of a VT-2 examination using a soap solution. What is the technical basis for these LLRT administrative limits?

5. The proposed alternative specifically requires ASME Code-compliant repair or replacement of safety-related components in which through-wall leakage is found, but

does not address repair or replacement of components that are nonsafety-related. If a leak in a pressure boundary that is nonsafety-related were detected during performance of an ASME Code-compliant VT-2 examination, would the nonsafety-related component or piping be repaired or replaced in accordance with the applicable ASME Code requirements? Discuss the disposition of such a leak if it is detected as the result of the LLRT.

6. Has there been a history of degradation or leakage of the subject piping at CPS? What was the cause of any degradation or leakage?

'.. ML13015A396 OFFICE LPL3-2/PE LPL3-2/LA LPL3-2/BC LPL3-2/PM NAME CFaria SRohrer MDudek JWiebe DATE 01/09/13 01/23/13 01/29/13 01/29/13