ML20076C833

Response to Request for Additional Information (E-mail Dated 3/16/2020) Alternative Request IR-4-03 for Use of Alternative Non-Code Methodology

ML20076C833
Person / Time
Site:	Millstone
Issue date:	03/16/2020
From:	Sinha S Dominion Energy Nuclear Connecticut
To:	Richard Guzman Division of Operating Reactor Licensing
Guzman R
References
EPID L-2020-LLR-0038
Download: ML20076C833 (4)

Text

From: Shayan.Sinha@dominionenergy.com To: Guzman, Richard

Subject:

[External_Sender] RE: Millstone Unit 3 - REQUEST FOR ADDITIONAL INFORMATION: Alternative Request IR 03 For Use of an Alternative Non-Code Methodology to Demonstrate Structural Integrity [EPID: L-2020-LLR-0038]

Date: Monday, March 16, 2020 1:02:51 PM Attachments: Attachment to RAI for RR IR-4-03 (SN 20-110) MPS3 Service Water Piping-weld Sketch.pdf

Rich, Please find DENCs response below:

DENC Serial Number 20-110 Request for Additional Information for RR IR-4-03 NRC RAI question In the licensees relief request under Compensatory Actions, it states that ultrasonic testing (UT) will be used to verify that the degradation of the piping base metal adjacent to and under the reinforcement pad fillet weld and the reinforcing pad base metal is within the bounds of the structural integrity determination provided in Attachment 2. Please define the acceptance criteria which will be used for the UT examinations as described in your compensatory actions. Please clarify that if the structural integrity determination does not meet the bounds of the analysis, the licensee will repair the location in accordance with the ASME Code immediately.

DENC Response An acceptance criterion of 0.215 inches is being applied to the UT thickness measurements for each of the following components: the reinforcing pad, branch pipe, and main pipe. The acceptance criterion was determined by recalculation of the Code stress equations for an increased unreinforced tee stress intensity factory (SIF), per ASME Code Section III figure NC 3672.9(a)-1. The acceptance criterion of 0.215 inches is based on the weld thickness which is most limiting. Should UT measurements determine any thickness less than that analyzed in Attachment 2, the A train of Service Water will be declared inoperable.

NRC RAI question Please provide a sketch which provides the location of the portion of joint that will be monitored by UT for structural integrity. Identify the potential leak paths, system water flow, and areas to be examined by UT as part of your compensatory actions.

DENC Response Attached is a sketch of typical reinforced Branch to Pipe connections including the potential leak paths, system water flow and areas to be examined by UT.

The circumference of the main pipe and branch pipe have been and will continue to be scanned using a zero-degree transducer from the toe of the fillet weld outward over a two-inch wide band.

The integrity of the base metal under the main pipe and branch pipe to reinforcing pad fillet welds has been and will continue to be evaluated using a 70-degree angle beam transducer scanning perpendicular to the fillet weld. For the main pipe, this examination covers approximately 2 inches of piping base metal that extends under the reinforcing pad.

For the branch pipe, the angle beam exam covers the base metal under the fillet weld to the butt weld joining the branch run to the main run. These angle beam exams are informational and intended to assist in locating degradation. Angle beam cannot be used to quantify material thickness. The determination of acceptability is based on the zero-degree UT reading for degradation extending beyond the toe of the reinforcement pad to fillet welds.

The zero degree and 70-degree examinations performed on the main piping cover all but approximately 16 inches of the circumference of the pipe. This limitation occurs where the main run flange proximity to the branch run piping limits access.

The reinforcing pad integrity is evaluated using a zero-degree transducer at selected locations across the reinforcing pad.

From: Guzman, Richard <Richard.Guzman@nrc.gov>

Sent: Sunday, March 15, 2020 7:15 PM To: Shayan Sinha (Services - 6) <Shayan.Sinha@dominionenergy.com>

Subject:

[EXTERNAL] Millstone Unit 3 - REQUEST FOR ADDITIONAL INFORMATION: Alternative Request IR-4-03 For Use of an Alternative Non-Code Methodology to Demonstrate Structural Integrity [EPID: L-2020-LLR-0038]

Shayan, The NRC staff is reviewing the information provided in the subject alternative request dated March 14, 2020, and has determined that additional information is needed to complete its review. Shown below is the NRC staffs request for additional information (RAI) question.

Please provide your response as soon as possible, in support of DENCs requested approval date as specified in the submittal. Please contact me if you have any questions.

~~~~~~~~~~~~

Rich Guzman Sr. PM, Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Office: O-9C7 l Phone: (301) 415-1030 Richard.Guzman@nrc.gov REQUEST FOR ADDITIONAL INFORMATION (RAI)

DOMINION ENERGY NUCLEAR CONNECTICUT, INC.

MILLSTONE POWER STATION, UNIT 3 ALTERNATIVE REQUEST IR-4-03 FOR USE OF AN ALTERNATIVE NON-CODE METHODOLOGY TO DEMONSTRATE STRUCTURAL INTEGRITY OF CLASS 3 MODERATE-ENERGY PIPING DOCKET NO. 50-423 By letter dated March 14, 2020, Dominion Energy Nuclear Connecticut, Inc. (Dominion, the licensee) submitted relief request (RR) IR-4-03, to use a non-code methodology in lieu of repair allowed by the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code,Section XI, IWA-4000, in order to address a through-wall leak in a reinforced branch connection of the service water system at Millstone Power Station, Unit 3 (Millstone 3). Specifically, the licensee requested NRC verbal authorization of the alternate method for evaluating structural integrity of the through-wall leak condition identified on the Millstone 3 A train service water header. The NRC staff is reviewing the submittal and has determined that additional information as requested below is needed to support completion of its review.

Request for Additional Information for RR IR-4-03 In the licensees relief request under Compensatory Actions, it states that ultrasonic testing (UT) will be used to verify that the degradation of the piping base metal adjacent to and under the reinforcement pad fillet weld and the reinforcing pad base metal is within the bounds of the structural integrity determination provided in Attachment 2. Please define the acceptance criteria which will be used for the UT examinations as described in your compensatory actions. Please clarify that if the structural integrity determination does not meet the bounds of the analysis, the licensee will repair the location in accordance with the ASME Code immediately.

Please provide a sketch which provides the location of the portion of joint that will be monitored by UT for structural integrity. Identify the potential leak paths, system water flow, and areas to be examined by UT as part of your compensatory actions.