ML18331A205

NRR E-mail Capture - Formal Release of RAIs Ref: Callaway Relief Request EPID L-2018-LLR-0051

ML18331A205
Person / Time
Site:	Callaway
Issue date:	11/27/2018
From:	John Klos Plant Licensing Branch IV
To:	Elwood T AmerenUE
References
L-2018-LLR-0051
Download: ML18331A205 (3)

Text

NRR-DMPSPEm Resource From: Klos, John Sent: Tuesday, November 27, 2018 10:18 AM To: 'Telwood@ameren.com' Cc: Klos, John

Subject:

Formal release of RAIs Ref: Callaway Relief Request EPID L-2018-LLR-0051

Tom, By letter dated April 9, 2018, (Agencywide Documents Access and Management System (ADAMS) Accession Number ML18099A120) Union Electric Company (Ameren Missouri) requested relief from the inspection frequency requirements of Inspection Item A-2. Unmitigated butt weld at Hot Leg operating temperature 625°F (329°C), and Inspection Item B, Unmitigated butt weld at Cold Leg operating temperature, as incorporated by reference in 10 CFR 50.55a(g)(6)(ii)(F),

of ASME Code Case N-770-2 for the mitigated dissimilar metal butt welds by water jet peening at Callaway Plant Unit 1.

The Nuclear Regulatory Commission (NRC) staff has reviewed the submittal has determined that requests for additional information (RAI) are needed to complete its technical review and make a regulatory finding regarding this relief request.

The licensee has indicated that a clarification call is not required and the RAIs below are now release formally with a 60 day calendar response time; thereby, these RAIs are due on Monday January 28, 2019.

REQUEST FOR ADDITIONAL INFORMATION RELIEF REQUEST I4R-05 ALTERNATE EXAMINATION OF REACTOR VESSELNOZZLE DISSIMIARL METAL WELDS CALLAWAY PLANT Unit 1 DOCKET NO. 50-483 By letter dated April 9, 2018, (Agencywide Documents Access and Management System (ADAMS) Accession Number ML18099A120) Union Electric Company (Ameren Missouri) requested relief from the inspection frequency requirements of Inspection Item A-2. Unmitigated butt weld at Hot Leg operating temperature 625°F (329°C), and Inspection Item B, Unmitigated butt weld at Cold Leg operating temperature, as incorporated by reference in 10 CFR 50.55a(g)(6)(ii)(F),

of ASME Code Case N-770-2 for the mitigated dissimilar metal butt welds by water jet peening at Callaway Plant Unit 1.

To complete its evaluation, the Nuclear Regulatory Commission requests the following addition information.

1. Provide refueling outage and date that the water jet peening was applied to the subject dissimilar metal welds.

2. Section 5.2.2 of the relief request discusses peening process. Discuss deviations between the field application and the performance (mock-up) demonstration and/or peening procedure qualification.

1

3. In the mockup, the weld residual stress (WRS) measurement is taken from the plate location instead of the weld.

Provide basis for acceptability of WRS measurement on the plate near the weld to effectively address residual stresses in the weld and to verify compression in the weld to meet the performance criteria of the peening process.

A) Address the following issues in the discussion; (1) Difference in the uncertainties caused by the measurements in the calibration method and the measurements in a mockup.

(2) Difference in microstructure between the plate material and weld material that would demonstrate the residual stress in the plate is valid to represent the residual stress in the weld (3) Potential differences in residual stress profiles of the weld versus the plate (4) How is the error in the residual stress measurement on the plate as compared to the error of similar analytical residual stress values in the weld material?

(5) How do the original tensile stresses in the plate mockup compare to stresses in the weld in the field?

B) Provide the tabular data used to demonstrate compliance with the criteria for depth of compression in the mockup, including error associated with measurement.

C) Does the number of water jet peening applications used in the mockup equal the number of applications used in the field at Callaway for the subject welds?

D) Discuss whether the peening qualification was performed on a mock up that is the same size as in the field (i.e., same pipe diameter and wall thickness). If not, discuss the impact of this difference on the peening applied to the mock-up specimens, and how it will provide the same results as peening on the welds in the field.

E) Page 8 of 14 of the relief request states that the test coupons are thinner than the actual pipe wall thickness, but it is thick enough. Discuss whether this statement is verified and validated based on the testing on mockup of the actual pipe wall thickness and the thinner test coupon.

4. Section 5.2.2, (Page 5 of 14) of the relief request states that It is also suitable for surfaces covered by the normal, thin oxide layer that forms under operating conditions in primary coolant. Therefore, no preparations of the surfaces to be peened are required before peening is performed... (a) Describe whether during qualification tests a thin layer of oxide is applied to the mockup so that qualification test is performed to mimic the field condition. If not, justify why a thin oxide layer was not removed prior to peening in the field. (b) Discuss whether peening qualification tests were performed to show that the thin oxide layer does not change the peening effect on the subject weld. If not, discuss how the qualification tests are sufficient to demonstrate the compressive effect of peening in the field.

John Klos DORL Callaway, Columbia Project Manager U.S. NRC, Office of Nuclear Reactor Regulation, Division of Operating Reactor Licensing, O9D22 NRC/NRR/DORL/LPL4, MS O9E3 Washington, DC 20555-0001 301.415.5136, John.Klos@NRC.gov 2

Hearing Identifier: NRR_DMPS Email Number: 683 Mail Envelope Properties (DM5PR0901MB2375DA8661788E46E4D969D1E3D00)

Subject:

Formal release of RAIs Ref: Callaway Relief Request EPID L-2018-LLR-0051 Sent Date: 11/27/2018 10:17:58 AM Received Date: 11/27/2018 10:17:58 AM From: Klos, John Created By: John.Klos@nrc.gov Recipients:

"Klos, John" <John.Klos@nrc.gov>

Tracking Status: None

"'Telwood@ameren.com'" <Telwood@ameren.com>

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