Text

Request for Relief from Qualification Requirements for Dissimilar Metal Piping Welds
	ML033090114
Person / Time
Site:	Nine Mile Point
Issue date:	10/23/2003
From:	Katz P; Constellation Energy Group
To:	; Document Control Desk, Office of Nuclear Reactor Regulation
References
	NMP1L 1780
	Download: ML033090114 (19)
	v • d • e

P.O. Box 63 Lycoming, New York 13093 Constellation Energy Group Nine Mile Point Nuclear Station U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 October 23 2003 NMP1L 1780

SUBJECT:

Nine Mile Point Units 1 and 2 Docket Nos. 50-220 and 50-4 10 Facility License Nos. DPR-63 and NPF-69 Request for Relief from Qualification Requirements for Dissimilar Metal Piping Welds Gentlemen:

By letter dated August 8, 2003, Nine Mile Point Nuclear Station, LLC (NMPNS) submitted inservice inspection relief requests ISI-24A and ISI-24B for Nine Mile Point Unit 1 (NMP1) and Unit 2 (NMP2), respectively. In accordance with a telephone conversation with the NRC staff on August 19, 2003, NMPNS has subsequently conducted a review of contractor inspection capabilities and concluded that relief from ASME Code,Section XI, Appendix VIII, Supplement 10, qualification requirements in the area of flaw depth sizing is not needed. NMPNS, therefore, is submitting revisions to the original relief requests that include only the performance demonstration initiative (PDI) alternative to the Supplement 10 requirements. These revisions are contained in Attachments 1 and 2, and replace the original relief requests in their entirety.

Differences from the original relief requests are identified by "lined through" text accompanied by change bars in the margin. Attachment 3 to the August 8, 2003, submittal remains unchanged and need not be re-submitted.

NMPNS requests NRC approval of the revised relief requests by February 15, 2004, to support examinations planned for NMP2 during the next refueling outage (RFO9).

Very truly yours, Vice President Nine Mile Point PEK/IAA/bjh Attachments AD

Page 2 NMP1L 1780 cc:

Mr. H. J. Miller, NRC Regional Administrator, Region I Mr. G. K. Hunegs, NRC Senior Resident Inspector Mr. P. S. Tam, Senior Project Manager, NRR (2 copies)

ATTACHMENT 1 (Revised Relief Request ISI-24A for Nine Mile Point Unit 1)

NINE MILE POINT UNIT 1 THIRD INSERVICE INSPECTION INTERVAL RELIEF REQUEST ISI-24A A.

COMPONENT IDENTIFICATION System:

Various Systems Class:

Quality Group A, ASME Code Class 1 Component

Description:

Pressure Retaining Piping Welds subject to examination using procedures, personnel, and equipment qualified to ASME Section XI, Appendix Vill, Supplement 10 criteria Component Identification: provides a list of applicable dissimilar metal welds B.

ASME CODE SECTION Xl REQUIREMENTS ASME Section XI, 1995 Edition with 1996 Addenda, Appendix Vil, Supplement 10, Qualification Requirements For Dissimilar Metal Piping Welds."

The following paragraphs or statements are from ASME Section Xl, Appendix Vil, Supplement 10 and identify the specific requirements that are included in this request for relief.

Item 1 - Paragraph 1.1 (b) states in part - Pipe diameters within a range of 0.9 to 1.5 times a nominal diameter shall be considered equivalent.

Item 2 - Paragraph 1.1 (d) states - All flaws in the specimen set shall be cracks.

Item 3 - Paragraph 1.1 (d)(1) states - At least 50% of the cracks shall be in austenitic material. At least 50% of the cracks in austenitic material shall be contained wholly in weld or buttering material. At least 10% of the cracks shall be in ferritic material. The remainder of the cracks may be in either austenitic or ferritic material.

Item 4 - Paragraph 1.2(b) states in part - The number of unflawed grading units shall be at least twice the number of flawed grading units.

Item 5 - Paragraph 1.2(c)(1) and 1.3(c) state in part - At least 1/3 of the flaws, rounded to the next higher whole number, shall have depths between 10% and 30% of the nominal pipe wall thickness. Paragraph 1.4(b) distribution table requires 20% of the flaws to have depths between 10% and 30%.

Item 6 - Paragraph 2.0 first sentence states - The specimen inside surface and identification shall be concealed from the candidate.

Item 7 - Paragraph 2.2(b) states in part - The regions containing a flaw to be sized shall be identified to the candidate.

Item 8 - Paragraph 2.2(c) states in part - For a separate length sizing test, the regions of each specimen containing a flaw to be sized shall be identified to the candidate.

Item 9 - Paragraph 2.3(a) states - For the depth sizing test, 80% of the flaws shall be sized at a specific location on the surface of the specimen identified to the candidate.

Item 10 - Paragraph 2.3(b) states - For the remaining flaws, the regions of each specimen containing a flaw to be sized shall be identified to the candidate. The candidate shall determine the maximum depth of the flaw in each region.

R3 ISI24A-1 OF IS124A-8

NINE MILE POINT UNIT 1 THIRD INSERVICE INSPECTION INTERVAL RELIEF REQUEST ISI-24A Item 11 - Table Vil-S2-1 provides the false call criteria when the number of unflawed grading units is at least twice the number of flawed grading units.

Item 12 Paragraph 3.2(b) states Examimatiem proedures, equipment, and per0nroel are qualified for.

depth sizimg whem the RMo e lrrr df he flaw depth easuremets, as compared to the taue flew depths, s les thAn __ equal to _.125 i.

C.

RELIEF REQUESTED Pursuant to 10 CFR 50.55a(a)(3)(i), Nine Mile Point Nuclear Station, LLC (NMPNS) requests relief to use the proposed alternative Performance Demonstration Initiative (PDI) Program described below in lieu of the ASME Code Section Xl, Appendix Vil, Supplement 10 requirements on the basis that the proposed alternative will provide an acceptable level of quality and safety for examination of the affected welds.

A copy of the proposed revision to Supplement 10 is attached as an Enclosure. It identifies the proposed alternatives and allows them to be viewed in context. It also identifies additional clarifications and enhancements for information. It has been submitted to the ASME Code for consideration and as of September 2002, has been approved by the NDE Subcommittee.

In addition, NIMPNZ requests relief from the depth szing lss than or equal to 0.1 25 inch RMS error.

D.

BASIS FOR RELIEF Item 1 - The proposed alternative to Paragraph 1.1 (b) states:

"The specimen set shall include the minimum and maximum pipe diameters and thicknesses for which the examination procedure is applicable. Pipe diameters within a range of % In. (13 mm) of the nominal diameter shall be considered equivalent. Pipe diameters larger than 24 in. (610 mm) shall be considered to be flat. When a range of thicknesses is to be examined, a thickness tolerance of +25% is acceptable."

Technical Basis - The change in the minimum pipe diameter tolerance from 0.9 times the diameter to the nominal diameter minus 0.5 inch provides tolerances more in line with industry practice. Though the alternative is less stringent for small pipe diameters, they typically have a thinner wall thickness than larger diameter piping. A thinner wall thickness results in shorter sound path distances that reduce the detrimental effects of the curvature. This change maintains consistency between Supplement 10 and the recent revision to Supplement 2.

Item 2 - The proposed alternative to Paragraph 1.1 (d) states:

"At least 60% of the flaws shall be cracks, the remainder shall be alternative flaws. Specimens with IGSCC shall be used when available. Alternative flaws, If used, shall provide crack-like reflective characteristics and shall be limited to the case where Implantation of cracks produces spurious reflectors that are uncharacteristic of actual flaws. Alternative flaw mechanisms shall have a tip width of less than or equal to 0.002 In. (.05 mm). Note, to avoid confusion the proposed alternative modifies instances of the term "cracks" or "cracking" to the term "flaws" because of the use of alternative flaw mechanisms."

Technical Basis - As illustrated below, implanting a crack requires excavation of the base material on at least one side of the flaw. While this may be satisfactory for ferritic materials, it does not produce a useable axial flaw in austenitic materials because the sound beam, which normally passes only through R3 ISI24A-2 OF ISI24A-8

NINE MILE POINT UNIT 1 THIRD INSERVICE INSPECTION INTERVAL RELIEF REQUEST ISI-24A base material, must now travel through weld material on at least one side, producing an unrealistic flaw response. In addition, it is important to preserve the dendritic structure present in field welds that would otherwise be destroyed by the implantation process. To resolve these issues, the proposed alternative allows the use of up to 40% fabricated flaws as an alternative flaw mechanism under controlled conditions. The fabricated flaws are isostatically compressed, which produces ultrasonic reflective characteristics similar to tight cracks.

(E Mechanical fatigue crack A

in Base material Item 3 - The proposed alternative to Paragraph 1.1 (d)(1) states:

"At least 80% of the flaws shall be contained wholly in weld or buttering material. At least one and a maximum of 10% of the flaws shall be in ferritic base material. At least one and a maximum of 10%

of the flaws shall be in austenitic base material."

Technical Basis - Under the current Code, as few as 25% of the flaws are contained in austenitic weld or buttering material. Recent experience has indicated that flaws contained within the weld are the likely scenarios. The metallurgical structure of austenitic weld material is ultrasonically more challenging than either ferritic or austenitic base material. The proposed alternative is therefore more challenging than the current Code.

Item 4 - The proposed alternative to Paragraph 1.2(b) states:

Detection sets shall be selected from Table Vil-S1O-1. The number of unflawed grading units shall be at least one and a half times the number of flawed grading units."

Technical Basis - Table VIII-Sl 0-1 provides a statistically based ratio between the number of unflawed grading units and the number of flawed grading units. The proposed alternative reduces the ratio to 1.5 times to reduce the number of test samples to a more reasonable number from the human factors perspective. However, the statistical basis used for screening personnel and procedures is still maintained at the same level with competent personnel being successful and less skilled personnel being unsuccessful. The acceptance criteria for the statistical basis are in Table Vil-S10-1.

Item 5 - The proposed alternative to the flaw distribution requirements of Paragraph 1.2(c)(1) (detection) and 1.3(c) (length) is to use the Paragraph 1.4(b) (depth) distribution table (see below) for all qualifications.

Flaw Depth Minimum M% Wall Thickness)

Number of Flaws 10-30%

20%

31-60%

20%

61-100%

20%

ISI24A-3 OF ISI24A-8

NINE MILE POINT UNIT 1 THIRD INSERVICE INSPECTION INTERVAL RELIEF REQUEST ISI-24A Technical Basis - The proposed alternative uses the depth sizing distribution for both detection and depth sizing because it provides for a better distribution of flaw sizes within the test set. This distribution allows candidates to perform detection, length, and depth sizing demonstrations simultaneously utilizing the same test set. The requirement that at least 75% of the flaws shall be in the range of 10 to 60% of wall thickness provides an overall distribution tolerance yet the distribution uncertainty decreases the possibilities for testmanship that would be inherent to a uniform distribution. It must be noted that it is possible to achieve the same distribution utilizing the present requirements, but it is preferable to make the criteria consistent.

Item 6 - The proposed alternative to Paragraph 2.0 first sentence states:

"For qualifications from the outside surface, the specimen Inside surface and Identification shall be concealed from the candidate. When qualifications are performed from the Inside surface, the flaw location and specimen identification shall be obscured to maintain a "blind test."

Technical Basis - The current Code requires that the inside surface be concealed from the candidate.

This makes qualifications conducted from the inside of the pipe (e.g., PWR nozzle to safe end welds) impractical. The proposed alternative differentiates between ID and OD scanning surfaces, requires that they be conducted separately, and requires that flaws be concealed from the candidate. This is consistent with the recent revision to Supplement 2.

Items 7 and 8 - The proposed alternatives to Paragraph 2.2(b) and 2.2(c) state:

"... containing a flaw to be sized may be identified to the candidate."

Technical Basis - The current Code requires that the regions of each specimen containing a flaw to be length sized shall be identified to the candidate. The candidate shall determine the length of the flaw in each region (Note, that length and depth sizing use the term "regions" while detection uses the term "grading units" - the two terms define different concepts and are not intended to be equal or interchangeable). To ensure security of the samples, the proposed alternative modifies the first "shall' to a "may" to allow the test administrator the option of not identifying specifically where a flaw is located.

This is consistent with the recent revision to Supplement 2.

Items 9 and 10 - The proposed alternative to Paragraph 2.3(a) and 2.3(b) state:

"... regions of each specimen containing a flaw to be sized may be identified to the candidate."

Technical Basis - The current Code requires that a large number of flaws be sized at a specific location.

The proposed alternative changes the "shall" to a "may" which modifies this from a specific area to a more generalized region to ensure security of samples. This is consistent with the recent revision to Supplement 2. It also incorporates terminology from length sizing for additional clarity.

R3 IS124A-4 OF IS124A-8

NINE MILE POINT UNIT 1 THIRD INSERVICE INSPECTION INTERVAL RELIEF REQUEST ISI-24A Item 11 - The proposed alternative modifies the acceptance criteria of Table Vil-S2-1 as follows:

10 TABLE VIII-S2-1 PERFORMANCE DEMONSTRATION DETECTION TEST ACCEPTANCE CRITERIA Detection Test Acceptance Criteria No. of Flawed Minimum Detection Grading Units Criteria False Call Test Acceptance Criteria No. of Unfiawed Grading Units Maximum Number of False Calls - - -

-.6- -4 -e-

-46

_ -46--

10 1

12 13 14 15 16 17 18 19 20 8

9 9

10 10 11 12 12 13 13 14 e

15 22-17 24 18 26 20 26-21 6e 23 6EA 24 84 26 2

6 3 83 4 3 6-3 6 3 6-4 6 4 27

% 29 4

30 5

Technical Basis - The proposed alternative is identified as new Table Vil-SI 0-1 above. It was modified to reflect the reduced number of unflawed grading units and allowable false calls. As a part of ongoing Code activities, Pacific Northwest National Laboratory has reviewed the statistical significance of these revisions and offered the revised Table Vil-Sl 0-1.

Item 12 The proposed alternative t Paragraph 3.2(b) states:

"Examinatiem procedures, equipment, and persenel are qualified for depth siuing when the RMS erro of the flaw depth measurements, s5 compared t the true flaw depths, is less than or equal t 0.125 in."

Technial Basis The industry i i the prcess f qualifying personnel t Supplement 10; however, as of Mah 14, 280, m Mile Pt Nuelear Stat was Wrminr that parsomme! qualifyin t th Supplement 10 procedures have met been 3ucee33ful i achieving the 0.125 inch MS criteria for depth sizrig. Industry personnel have only been capable f achieving an accuracy f 0.155 i. RMC.

IS124A-5 OF IS124A-8

NINE MILE POINT UNIT 1 THIRD INSERVICE INSPECTION INTERVAL RELIEF REQUEST ISI-24A E.

ALTERNATIVE EXAMINATIONS As an alternate to the requirements of ASME Section XI, 1995 Edition, 1996 Addenda, Appendix Vil, Supplement 10, NMPNS proposes to use the PDI Program alternative as described in the Enclosure.

NMrrC also proposes that f a flaw is dteated during the perfercce of an ultresenie exemnetiam, the flaw will b sed1 isirg the dat _ _ _

A d

15ep5 ireh MS value dtermired duig the Pei performarnce demonstration. In addtion P4MPC4 proposes to take intoe acctunt the ncrease ir allowable depth sizing error, by adding the differece between the ASME Gade required 0.125 ineh RMS error and the demonstrated 0.155 ich FMS error to measurements acquired from actual flaw siting. Specifically, 0.030 iches will be added to the measured flaw size when petforming fracture nechanics calculations.

F.

IMPLEMENTATION SCHEDULE The remainder of the Third Ten-Year Inservice Inspection Interval for Unit 1 (December 26, 1999 through December 25, 2009)

G.

ATTACHMENTS List of Applicable Dissimilar Metal Welds Enclosure Comparison of the ASME Code, Section Xl, Supplement 10 current requirements to the proposed changes.

R3 IS124A-6 OF IS124A-8

NINE MILE POINT UNIT 1 THIRD INSERVICE INSPECTION INTERVAL RELIEF REQUEST ISI-24A List of Applicable Dissimilar Metal Welds System Weld Weld Description System Weld Weld Description Identification Identification 00.0 RV-WD-01 1 Nozzle N7A to Flange 32.0 Reactor 32-WD-208 Nozzle N2E to Safe End Closure Head Recirculation 00.0 RV-WD-013 Nozzle N7B to Flange 32.0 Reactor 32-WD-002 Nozzle N1A to Safe End Closure Head Recirculation 00.0 RV-WD-015 Nozzle N7C to Flange 32.0 Reactor 32-WD-045 Nozzle N1B to Safe End Closure Head Recirculation 00.0 RV-WD-017 Nozzle N70 to Flange 32.0 Reactor 32-WD-085 Nozzle N1C to Safe End Closure Head Recirculation 00.0 RV-WD-019 Nozzle N7E to Flange 32.0 Reactor 32-WD-125 Nozzle N1 D to Safe End Closure Head Recirculation 00.0 RV-WD-021 Nozzle N7F to Flange 32.0 Reactor 32-WD-1 67 Nozzle NI E to Safe End Closure Head Recirculation 00.0 RV-WD-023 Nozzle N7G to Flange 33.0 Reactor Water 33-WD-004 Pipe to Pipe Bend Closure Head Clean-Up 00.0 RV-WD-025 Nozzle N7H to Flange 33.0 Reactor Water 33-WD-014 Pipe to Pipe Closure Head Clean-Up 00.0 RV-WD-027 Nozzle N7J to Flange 36.0 Reactor 36-WD-003 Nozzle N13A to Safe End Closure Head Instrumentation 00.0 RV-WD-029 Nozzle N7K to Flange 36.0 Reactor 36-WD-073 Nozzle N13B to Safe End Closure Head Instrumentation 00.0 RV-WD-031 Nozzle N7M to Flange 36.0 Reactor 36-WD-141 Nozzle N14A to Safe End Closure Head Instrumentation 00.0 RV-WD-033 Nozzle N7N to Flange 36.0 Reactor 36-WD-315 Nozzle N148 to Safe End Closure Head Instrumentation 00.0 RV-WO-035 Nozzle N7P to Flange 36.0 Reactor 36-WD-538 Nozzle N15A to Safe End Closure Head Instrumentation 00.0 RV-WD-037 Nozzle N7R to Flange 36.0 Reactor 36-WD-705 Nozzle N15B to Safe End Closure Head Instrumentation 00.0 RV-WD-039 Nozzle N7S to Flange 36.0 Reactor 36-WD-1000 Nozzle N16B to Safe End Closure Head Instrumentation 00.0 RV-WD-041 Nozzle N7T to Flange 36.0 Reactor 36-WD-924 Nozzle N16A to Safe End Closure Head Instrumentation 00.0 RV-WD-043 Nozzle N7U to Flange 36.0 Reactor 36-WD-1074 Closure Head Nozzle N7L Closure Head Instrumentation to Flange 32.0 Reactor 32-WD-042 Nozzle N2A to Safe End 36.0 Reactor 36-WD-1136 Nozzle N178 to Safe End Recirculation Instrumentation 32.0 Reactor 32-WD-082 Nozzle N2B to Safe End 37.0 Reactor Head 37-WD-002 Nozzle N8 to Flange Recirculation Vent 32.0 Reactor 32-WD-122 Nozzle N2C to Safe End 39.0 Emergency 39-WD-002 Nozzle N5A to Safe End Recirculation Condenser R3 IS124A-7 OF IS124A-8

NINE MILE POINT UNIT 1 THIRD INSERVICE INSPECTION INTERVAL RELIEF REQUEST ISI-24A List of Applicable Dissimilar Metal Welds System Weld Weld Description System Weld Weld Description Identification Identification 32.0 Reactor 32-WD-164 Nozzle N2D to Safe End 39.0 Emergency 39-WD-090 Nozzle N55 to Safe End Recirculation Condenser 40.0 Reactor 40-WD-039 Nozzle N6A to Safe End 42.1 Uquid Poison 42.1 -WD-034 Nozzle N12 to Safe End Core Spray 40.0 Reactor 40-WD-080 Nozzle N6B to Safe End 44.1 Control Rod 44.1-WD-017 Nozzle N9 to Safe End Core Spray Drive

.1. _____________

1 A.

A.

R3 IS124A-8 OF S124A-8

ATTACHMENT 2 (Revised Relief Request ISI-24B for Nine Mile Point Unit 2 )

NINE MILE POINT UNIT 2 SECOND INSERVICE INSPECTION INTERVAL RELIEF REQUEST SI-24B A.

COMPONENT IDENTIFICATION System:

Various Systems Class:

ASME Code Class 1 Component

Description:

Pressure Retaining Piping Welds subject to examination using procedures, personnel, and equipment qualified to ASME Section Xi, Appendix Vil, Supplement 10 criteria Component Identification: provides a list of applicable dissimilar metal welds B.

ASME CODE SECTION Xi REQUIREMENTS ASME Section XI, 995 Edition with 1996 Addenda, Appendix Vil, Supplement 10, Qualification Requirements For Dissimilar Metal Piping Welds."

The following paragraphs or statements are from ASME Section Xi, Appendix Vil, Supplement 10 and identify the specific requirements that are included in this request for relief.