Text

Fourth Ten-Year Interval Inservice Inspection (ISI) Program Relief Request 4ISI-06
	ML16053A183
Person / Time
Site:	Columbia
Issue date:	02/17/2016
From:	Javorik A; Energy Northwest
To:	; Document Control Desk, Office of Nuclear Reactor Regulation
References
	GO2-16-027
	Download: ML16053A183 (9)
	v • d • e

ENERGY NORTHWEST FEB 1 7 2016 G02-16-027 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Alex L. Javorik Columbia Generating Station P.O. Box 968, PE04 Richland, WA 99352-0968 Ph. 509-377-8555 I F. 509-377-2354 aljavorik@energy-northwest.com 10 CFR 50.55a

Subject:

COLUMBIA GENERATING STATION, DOCKET NO. 50-397; FOURTH TEN-VEAR INTERVAL INSERVICE INSPECTION (ISi) PROGRAM RELIEF REQUEST 41Sl-06

References:

(1) Code Case N-666-1, 'Weld Overlay of Class 1, 2, and 3 Socket Welded Connections," approved by the American Society of Mechanical Engineers (ASME) on March 13, 2012

Dear Sir or Madam:

Pursuant to 10 CFR 50.55a(z)(2), Energy Northwest hereby requests NRG approval of the following relief request for the fourth ten-year inservice inspection (ISi) program interval at Columbia Generating Station (Columbia) ending December 12, 2025. Energy Northwest has determined that compliance with certain repair requirements of ASME Section XI would result in unnecessary hardship or unusual difficulty without a compensating increase in the level of quality and safety. The details of the 1 O CFR 50.55a request are provided as Attachment 1.

Energy Northwest requests approval one year from the date of this request.

There are no new commitments made in this submittal. If you have any questions or require additional information, please contact Lisa Williams at 509-377-8148.

Executed this //rf day of h /,

, 2016.

Respectfully, A. L. Javorik Vice President, Engineering

Attachment:

(1) 1 O CFR 50.55a Request Number 41Sl-06 cc list: next page

FOURTH TEN-YEAR INTERVAL INSERVICE INSPECTION (ISI) PROGRAM RELIEF REQUEST 4ISI-06 Page 2 cc:

NRC Region IV Administrator NRC NRR Project Manager NRC Sr. Resident Inspector - 988C CD Sonoda - BPN1399 (email)

WA Horin - Winston & Strawn

FOURTH TEN-YEAR INTERVAL INSERVICE INSPECTION (ISI) PROGRAM RELIEF REQUEST 4ISI-06 Page 1 of 7 10 CFR 50.55a Request Number 4ISI-06 Alternative Weld Overlay of Class 1, 2, and 3 Socket Welded Connections Proposed Alternative In Accordance with 10 CFR 50.55a(z)(2)

-- Hardship without a compensating increase in quality and safety --

1. ASME Code Component(s) Affected ASME Code Class:

Class 1, 2 and 3

==

Description:==

Use of American Society of Mechanical Engineers (ASME)

Code Case N-666-1 on socket welded connections requiring repair due to vibration fatigue Examination Category:

IWA-4420 Item Number:

N/A Components Affected:

Socket welded nominal pipe size (NPS) 2 inches and smaller piping and socket welded components of the same NPS

2. Applicable Code Edition and Addenda

The Columbia Generating Station (Columbia) Inservice Inspection (ISI) fourth ten-year interval ASME Section XI Code is the 2007 Edition through the 2008 Addenda.

3. Applicable Code Requirement

ASME Section XI, IWA-4420, Defect Removal Requirements, provides the code requirements for defect removal associated with repair/replacement activities.

4. Reason for Request

Energy Northwest requests the approval to use an alternative to IWA-4420 for defect removal during repair of cracked or leaking socket welds in Class 1, 2, and 3, NPS 2 inches and smaller piping whose failure is the result of vibration fatigue. The additional time required for compliance with IWA-4420 requirements for defect removal will require Columbia Generating Station (Columbia) to remain in Technical Specification (TS)

Required Actions for longer periods of time. This may challenge the the Completion Time requiring further TS Required Actions up to and including plant shutdown. This

FOURTH TEN-YEAR INTERVAL INSERVICE INSPECTION (ISI) PROGRAM RELIEF REQUEST 4ISI-06 Page 2 of 7 would result in a hardship without a compensating increase in the level of safety and quality.

During Columbias third ten-year ISI interval, December 13, 2005 to December 12, 2015, ASME Code Case N-666 was approved for use without conditions by the Nuclear Regulatory Commission (NRC) in Regulatory Guide (RG) 1.147, Revision 16 (Reference 2). Code Case N-666 was applicable to Columbias third ten-year ISI interval ASME Section XI Code of record, the 2001 Edition through the 2003 Addenda.

Code Case N-666 is not applicable to Columbias fourth ten-year interval ASME Section XI Code of record, the 2007 Edition through the 2008 Addenda as specified in the ASME Applicability Index for Section XI Cases, 2015 Edition. Code Case N-666-1 is applicable to the fourth ten-year ISI Code of record, but not approved for use by the NRC in RG 1.147, thus use of Code Case N-666-1 requires a relief request per 10 CFR 50.55a.

5. Proposed Alternative and Basis for Use

In lieu of the defect removal requirements of IWA-4420, Columbia proposes to implement the requirements of ASME Code Case N-666-1, Weld Overlay of Class 1, 2, and 3 Socket Welded Connections,Section XI, Division 1, to restore structural integrity of a cracked or leaking socket weld in Class 1, 2, and 3, NPS 2 inches and smaller piping, resulting from vibration fatigue. Structural integrity may be restored by deposition of weld overlay on the outside surface of the pipe, weld, fitting, or flange.

This weld overlay technique is not applicable to the full or partial penetration weld joining a pipe or fitting of a branch to the run of pipe nor is it applicable to systems containing petroleum products such as lubricating oil or fuel or other substances that create a fire or explosion hazard.

Code Case N-666-1 requirements are as follows:

1 General Requirements a) The weld overlay shall be performed in accordance with a Repair/Replacement Program satisfying the requirements of IWA-4150 in the Edition and Addenda of Section XI applicable to the plant inservice inspection program, or later Edition and Addenda.

b) Use of this Case is limited to Class 1, 2, or 3, NPS 2 and smaller socket welded connections with base material of P-No. 1 Group 1 and P-No. 1 Group 2, or P-No. 8. For water backed welding, the carbon content of P-No. 1 Group 2 materials shall be limited to 0.30% maximum.

FOURTH TEN-YEAR INTERVAL INSERVICE INSPECTION (ISI) PROGRAM RELIEF REQUEST 4ISI-06 Page 3 of 7 c) The structural portion of the weld overlay and seal layers shall be deposited in accordance with a Shielded Metal Arc or a Gas Tungsten Arc Welding Procedure Specification (WPS) qualified in accordance with IWA-4440.

d) The structural overlay shall be performed when the system is at a temperature equal to or less than 200°F. The Owner shall implement measures to prevent separation of the pipe from the fittings or flange when repairs are made with system pressure greater than 275 psig. Prior to performing a repair, the Owner shall verify that the pipe base material adjacent to the socket weld requiring overlay meets the required minimum wall thickness.

e) A socket weld repair may not be overlaid more than one time.

f) The weld overlay shall meet all applicable requirements of IWA-4000, except as stated in this Case.

2 Evaluation a) The Owner shall verify that the socket weld failure is a result of vibration fatigue. This determination shall include review of the design, operating history, including changes in the piping system, and visual inspection of the failed socket weld. Metallurgical analysis of the flaw surface for failure determination is not required.

b) If review of the design, operating history, and changes to the piping system indicates that the current system configuration has not been changed for one or more fuel cycles, the weld overlay shall be acceptable until the next refueling outage, if no action is taken to reduce the vibration to acceptable levels. If corrective action is taken to reduce the vibration to acceptable levels, the weld overlay shall be acceptable for the remaining life of the piping system. If the time to failure of the original socket weld was less than one fuel cycle, corrective action that reduces the vibration to acceptable levels must be taken. Vibration acceptance standards shall be in accordance with ASME-OMb-S/G-2002, Part 3.

c) The evaluations required by this Case shall be documented and maintained in accordance with IWA-6300.

FOURTH TEN-YEAR INTERVAL INSERVICE INSPECTION (ISI) PROGRAM RELIEF REQUEST 4ISI-06 Page 4 of 7 3 Design a) The Owner shall consider, in the suitability evaluation required by IWA-4160, the source of the vibration that caused the original socket weld failure. The completed weld overlay shall meet the dimensional requirements of Figure 1 [of this Case]. The minimum throat dimension shall be 0.77 tn for fittings and 0.98 tn for flanges. This dimension shall be maintained from the seal weld surface and the original socket weld face as shown in Figure 1 [of this Case]. When the fatigue crack is located in the base metal adjacent to the toe of the socket weld, the minimum throat dimensions shall be measured from the location of the crack farthest from the weld toe.

b) The filler metal for the structural portion of the overlay of P-No. 1 material shall be [American Welding Standard] AWS Classification E70XX-X, or ER70S-X.

Filler metal for the structural portion of the overlay of P-No. 8 materials shall be AWS Classification E3XX-XX or ER3XX. The filler metal for the seal weld layers may be any filler metal permitted by a qualified WPS.

c) If the weld overlay is applied to a socket weld, without any other modification to the piping system, stress analysis of the effect of the overlay is not required. If other physical modifications are made to the piping system, the effect of the other physical modifications on the piping stress analysis shall be evaluated. Stress indices and stress intensification factors for the overlaid socket weld shall be the same as the minimum value that would be calculated for a standard socket weld in accordance with the Construction Code selected in accordance with IWA-4220.

4 Procedure a) Prior to welding, the location and approximate extent of cracking shall be determined visually.

b) The crack shall be sealed by depositing one or more weld beads. Seal welds may be deposited on wet surfaces. Peening may be used in combination with welding to seal the crack.

c) The seal weld, remaining socket weld, and adjacent base material that will be overlaid shall be examined using VT-1 visual examination.

(1) The procedure and personnel performing this visual examination shall meet the requirements of 5(a)(2) and 5(a)(3) [of this Case].

FOURTH TEN-YEAR INTERVAL INSERVICE INSPECTION (ISI) PROGRAM RELIEF REQUEST 4ISI-06 Page 5 of 7 (2) The examination surfaces shall be acceptable when no cracks or evidence of leakage are detected and the surfaces are suitable for overlay.

d) At least two structural overlay layers shall be deposited around the entire circumference of the fitting, weld, and pipe. The weld sequence shall be from the fitting to the pipe for the overlay of toe cracks and shall be from the pipe to fitting for the overlay of root cracks. The completed weld overlay shall meet the dimensional requirements of Figure 1 [of this Case]. The throat dimensions shall not include the seal layers deposited in accordance with (b).

e) As-welded surfaces are permitted; however they shall be sufficiently free of coarse ripples, grooves, overlaps, and abrupt ridges and valleys to permit interpretation of the required nondestructive examinations.

5 Final Examination and Testing a) Visual and nondestructive examination of the final structural overlay weld shall be performed in accordance with (1) through (3):

(1) VT-1 visual examination shall be performed on the completed weld overlay. In addition, the weld overlay shall be nondestructively examined in accordance with the Construction Code identified in the Repair/Replacement Plan. The method and extent of nondestructive examination shall be as specified for a socket weld.

(2) The VT-1 visual examination shall be performed using a procedure that meets the requirements of IWA-2210 and shall be capable of resolving text with lower case characters (e.g., a, c, e, o) not exceeding a height of 0.044 in. at the examination distance. The maximum direct VT-1 distance shall not exceed 2 ft.

(3) Personnel performing VT-1 visual examinations shall be qualified in accordance with IWA-2300 and shall receive additional training in examination of weldments for fabrication conditions, including dimensional requirements and fabrication flaws.

(4) Visual indications shall be evaluated using the acceptance standards in (-a) through (-e).

(-a) Cracks and incomplete fusion are unacceptable.

FOURTH TEN-YEAR INTERVAL INSERVICE INSPECTION (ISI) PROGRAM RELIEF REQUEST 4ISI-06 Page 6 of 7

(-b) Concavity and convexity of the surface of the overlay and craters are acceptable provided the criteria for weld size can be satisfied.

(-c) Undercut at the toe of the weld on the pipe side is unacceptable. Undercut at the toe of the weld on the fitting side shall not exceed a depth of 1/32 in.

(-d) Only surface porosity whose major dimension exceeds 1/16 in.

shall be considered relevant. Overlay welds that contain surface porosity are unacceptable if a pore diameter exceeds 1/8 in. or the sum of diameters of random porosity exceeds 3/8 in. or if four or more pores are aligned and the pores are separated by 1/16 in. or less, edge to edge.

(-e) Arc strikes on the weld overlay or in the adjacent pipe are unacceptable.

b) The completed weld overlay shall be dimensionally inspected to verify compliance the criteria of 4(d) [of this Case].

c) A system leakage test shall be performed in accordance with IWA-4540.

6 Documentation Use of this Case shall be documented on an NIS-2 Form.

Performing defect removal and code repair in lieu of implementing this 10 CFR 50.55a request would in some cases necessitate longer periods in TS Required Actions which challenge the TS Completion Time, putting the plant at higher safety risks than warranted compared to the time required to install a weld overlay. Without the use of this Code Case in some situations, plant shut down may be necessary to perform a code repair/replacement activity.

Based on the above discussion, Columbia has concluded there is reasonable assurance that the application of weld overlays per Code Case N-666-1 will provide adequate structural integrity providing an acceptable level of quality and Safety.

FOURTH TEN-YEAR INTERVAL INSERVICE INSPECTION (ISI) PROGRAM RELIEF REQUEST 4ISI-06 Page 7 of 7

6. Duration of Proposed Alternative

The duration of this request is for the fourth inservice inspection interval ending December 12, 2025 or until Code Case N-666-1 is approved by the NRC in Regulatory Guide 1.147. At that time, Columbia will use Code Case N-666-1 as approved by the NRC with any conditions identified.

7. Precedents

There are no precedents for this request.

8. References

1. Code Case N-666-1, Weld Overlay of Class 1, 2, and 3 Socket Welded Connections, approved by the American Society of Mechanical Engineers (ASME) on March 13, 2012

2. Nuclear Regulatory Commission Regulatory Guide 1.147, Inservice Inspection Code Case Acceptability, ASME Section XI, Division 1, Revision 17, August 2014