A97010, Requests Authorization for Alternative to One Time Augmented Insp of RPV Shell Welds Set Forth in 10CFR50.55a(g)(6)(ii) (A)(2) Per 10CFR50.55a(g)(6)(ii)(A)(5).Authorization to Use Partial Insp Coverage Requested

Requests Authorization for Alternative to One Time Augmented Insp of RPV Shell Welds Set Forth in 10CFR50.55a(g)(6)(ii) (A)(2) Per 10CFR50.55a(g)(6)(ii)(A)(5).Authorization to Use Partial Insp Coverage Requested

ML20210L374
Person / Time
Site:	Zion  File:ZionSolutions icon.png
Issue date:	08/13/1997
From:	Mueller J COMMONWEALTH EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
IEIN-96-032, IEIN-96-32, ZRA97010, NUDOCS 9708210114
Download: ML20210L374 (9)

Text

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Osmnr new talth I dimn Gimpan)

. 7 ton Generating Station 191 Shiloh lkiules ard

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• 1ci M4774(OWi ZRA97010 August 13,1997 U.S. Nuclear Regulatory Commission Washington, D.C. 20555 Attn: Document Control Desk

Subject:

Zion Nuclear Power Station, Units I and 2 Proposed Alternative to Augmented Reactor Vessel Shell Weld Examination per 10 CFR 50.55a(gX6Xii)(A)(5)

Operating Licenses DPR-39 and DPR-48 NRC Docket Nos. 50-295 and 50-304

Reference:

NRC Information Notice 96-32, " Implementation of 10 CFR 50.55a(g)(6)(ii)(A),

Augmented Examination of Reactor Vessel," dated June 5,1996 Commonwealth Edison (Comed) requests, pursuant to 10 CFR 50.55a(g)(6XiiXAX5),

authorization for an alternative to the one time augmented inspection of the reactor pressure vessel shell welds set forth in 10 CFR 50.55a(g)(6)(ii)(AX2).

Licensees are required by 10 CFR 50.55a(g)(6)(ii)(A)(2) to implement a one time augmented examination of" essentially 100%" of the pressure retaining reactor vessel welds, where " essentially 100%" has been defined as more than 90% of the examination volume of each weld These augmented inspections were performed by a contractor on Zion Unit 1 and Unit 2 reactor vessels in October and November 1993. Due to nozzle geometry and interference by other components, it was not possible for the contractor to achieve 90% examination coverage of two of the r: actor vessel shell welds in each unit as required by the rule.

In June 1996, the NRC issued the referenced Information Notice to alert licensees to certain aspects of the augmented reactor vessel inspection requirements, including the

" essentially 100%" standard. Accordingly, Comed personnel reviewed the augmented reactor vessel inspection data during the latter part of 1996, and became aware that 90%

coverage had not been achieved for all the above noted welds.

Comed is requesting authorization by the Office of Nuclear Reactor Regulation to use partial inspection coverage, as described in Attachment I to this letter, as an alternative to ( f an inspection of" essentially 100%" of the welds. Comed considers that the proposed / C f alternative provides an acceptable level of quality and safety.

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9708210114 970813 ll ll l[!lllll[l]lll PDR ADOCK 05000295 ..

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, ZRA97010, Page 2 of 2 Section (gX6XiiXAX3) of 10 CFR 50,55a would allow the augmented examinations to be completed during the current ISI inspection periods for Unit I and 2. The current inspection periods will end at the completion of the current refueling outage for Unit 1, and at the completion of the next refueling outage for Unit 2, Since the proposed alternative is applicable to both units, Comed is requesting that authorization be provided by the end of current Unit 1 refueling outage.

- Please direct any questions you may have concerning this submittal to this office.

Respectfully, t ) 'h J. H. Mueller Site Vice President Zion Station Attachments cc: NRC Regional Administrator- RIII Zion Station Project Manager - NRR Senior Resident inspector - Zion Station Office of Nuclear Facility Safety - IDNS IDNS Resident Inspector Zion NLA Master Files Reg. Assurance File DCD Licensing i

e ZRA97010 t

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t Attachment 1 1

Page 1 of 4

, ZION STATION UNES I & 2 ALTERNATIVE RPV EXAMINATION WMPONENT IDENTIFICATION:

Code Class: I

Reference:

Table IWB 25001 Examination Category: B-A Item Numbers: Bl.ll and Bl.12

Description:

Limited Volumetric Examination of Reactor Pressure Vessel Shell Welds Units: Zion Units 1 and 2 Component Numbers: Circumferential RPV Weld #2, Weld #5 (for both units)

REOUIREMEN'IS:

10 CFR 50.55a(g)(6)(ii)(A)(2) requires all licensees to augment their reactor vessel examination by implementing once, as part of the inservice inspection interval in effect on September 8,1992, the examination requirements for reactor vessel shell welds specified in Item Bl.10 of Examination Category B A, " Pressure Retaining Welds in Reactor Vessel," in Table IWB-2500-1 of Subsection IWB of the 1989 Edition of Section XI, Division 1, of the ASME Boiler and Pressure Vessel Code, subject to the conditions specified in 10 CFR 50.55a(g)(6)(ii)(A)(3) and (4). For the purpose of this augmented examination, " essentially 100%" as used in Table IWB 2500-1 means more than 90 percent of the examination volume of each weld, where the reduction in coverage is due to interference by another component, or part geometry.

10 CFR 50.55a(g)(6)(ii)(A)(5) states that " Licensees that make a determination that they are unable to completely satisfy the requirements for the augmented reactor vessel shell weld examination specified in Sec. 50.55a(g)(6)(ii)(A) shall submit information to the Commission to support the determination and sha'l propose an alternative to the examination requirements that would provide an acceptable level of quality and safety."

REOUEST:

Pursuant to 10 CFR 50.55a(g)(6)(ii)(A)(5), Zion Station requests approval of partial coverage (UT coverage of less than or equal to 90% of the required examination volume) on Unit I and 2 welds #2 and #5 as an alternative to the rules of 10 CFR 50.55a(g)(6)(ii)(A)(2), on the basis that the proposed alternative would provide an acceptable level of quality and safety.

i .

Pege 2 of 4

. ZION STATION UNTIS I & 2 ALTERNATIVE RPV EXAMINATION HIS1 DRY:

In October and November of 1993, Zion Station conducted ultrasonic examinations (UT) of reactor pressure vessel (RPV) shell welds in Units 1 and 2 to satisfy the requirements of 10 CFR 50.55a(g)(6)(ii)(A). These examinations were in the third inspection period of the second inservice inspection interval. A Westinghouse remote reactor vessel inspection tool with the UDRPS 2 ultrasonic data recording and processing system was utilized to examine the RPV shell welds from the RPV inside (ID) surface. The examinations were performed in accordance with the applicable rules of ASME Section XI,1980 Edition through Winter 1981 Addenda, and USNRC Regulatory Guide 1.150, Revision 1.

In each unit, four (4) circumferential welds (welds #2, #3, #4 and #5) and four (4) longitudinal welds (welds #7, #8, #9, and #10) were examined to satisfy the augmented RPV examination requirement. The augmented RPV examinations detected 52 recordable indicati ons in Unit 1 RPV shell welds, of which, six (6) indications were resized osn.g the

- 50% DAC sizing criteria per Reg. Guide 1.150. In accordance with the rules of ASME Section XI, all recordable indications found in Unit I were categorized as subsurface planar flaws. The augmented RPV examinations detected 21 recordable indications in Unit 2 RPV shell welds. All recor lable indications found in Unit 2 were categorized as subsurface planar flaws in accordance with the rules of ASME Section XI. All of the aforementioned planar flaws were evaluated and found to be acceptable per the applicable acceptance standards of ASME Section XI,1980 Edition through Winter 1981 Addenda.

UT coverage on 100% of the required examination volume was obtained for each of the two (2) circumferential and four (4) longitudinal welds that are located in the beltline region.

However, UT coverage of less than 90% of the required volume was achieved on the two (2) nonbeltline circumferential welds because of interference with other components and part geometry. These nonbeltline welds are the upper shell weld #2 and the lower shell course to bottom head weld #5.

Weld #2 - Upper Shell Weld.

This weld is located on the same elevation of the inlet and outlet nozzles. Because of the nozzle blend radius tapering, a complete perpendicular and parallel scan on the available weld length was not achievable with the Westinghouse manipulator. In Units 1 and 2, UT coverage was achieved on approximately 108 inches of weld length, which resulted in approximately 74% coverage of the required examination volume in each unit.

I

P:ge 3 of 4 i ZION STATION UNTIS 1 & 2 ALTERNATIVE RPV EXAMINATION lilS'IT)RY (Cont.h Weld #5 - Lower Shell Course To Bottom Head Weld.

This welo is located on the elevation just below that of the core support lugs. The six core support lugs limited the combined UT coverage for weld #5 to approximately 81% of the required examination volume in each unit. There was approximately 543 inches of weld #5 available for examination in each unit.

Table I summarizes the augmented RPV examination results for Units I and 2.

JUSTIFICATION:

The examinations of welds #2 and #5 were completed within a few percent of the maximum extent achievable at the time of these examinations, using the Westinghouse examination tool from the RPV inside surface. Access for examination from the outside surface of these welds is restricted due to the concrete structure and insulation surrounding the RPV. The limited cicarance between the RPV outside surface and the nonremovable insulation prevents access for examination from the RPV outside surface.

Although UT coverage of less than 90% of the required examination volume for welds #2 and

1. 5 was achieved, the reduced coverage still provides and acceptable level of quality and safety for the following reasons:

1. The UT results that were obtained for nonbeltline weld #2 and weld #5 adequately represented the structural condition of the subject welds because more than half of each weld length was fully examined, and these results confirmed the absence of rejectable service induced flaws. Additional UT data obtained on the six (6) beltline shell welds further confirmed the absence of service induced degradation mechanism.

Each of these beltline welds received 100% UT coverage on the required examination volume. These beltline welds are expected to be more susceptible to neutron embrittlement or pressurized thermal shock condition than the nonbeltline welds. The combined percentage of all required examination volumes (eight RPV shell welds per unit) that received Ur coverage was approximately 93% for each unit.

2. Periodic VT-3 visual examination of RPV interior (in accordance with Section XI, Category B N-1) was conducted, using a remote camera system, on the ID surface areas above and below the beltline region at the end of the second interval. No recordable indications were identified during this examination

3. Periodic VT-2 visual examinations are conducted during refueling outages on the RPV while under at least nominal operating pressure in accordance with Section XI, Category B-P. These examinations provide additional verification of the structural integrity of the RPV.

Page 4 of 4 TACLE1 .

Zion Unit I and 2 RPV Aug.w,2d Erannisation Resmits ,

Code Pmposed Weld  % Total Nasaber of Untitanees Unit Zion Weld .

Identificance item Alternative length Volsene Recordable .

Requessed (in) Coreinge Indications Achieved Identirmt YES 14.1 74 % 0 Nozzle 1 #2 Bl.Il Geometry NO 543 100 % 7 None I #3 Bl.Il NO 543 100 % 14 Noac 1 #4 Bl.Il YES 543 *81% 9 Core I #5 Bl.Il Support Lugs Bl.12 NO 92 100 % 4 None

! #7 i

Bl.12 NO 92 100 % 2 None i #8 NO 92 100 % 8 None 1 #9 B l.12 l

Bl.12 NO 92 100 % 8 Nonc 1 #10 YES 145 74 % 1 Nozzle 2 #2 Bl.Il Geometay  ;

NO 543 100 % 2 None 2 #3 Bl.ll B 1.11 NO 543 100 % 9 None 2 #4 YES 543 '81% 3 Core 2 #5 Bl.Il Support Lugs 2 #7 Bl.12 NO 92 100 % 2 None j Bl.12 NO 92 100 % 2 None 2 #8 .

Bl.12 NO 92 100 % 0 None 2 #9 NO 92 100 % 2 None 2 #10 Bl.12 l

• At least 57% of the volume covered received two angle and two directional coverage.

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G S

ZRA97010 4

Attachment 2 0

Attachment 2 - ZRA97010 Page1ofI 13at of Commitments Identified in this Relief Reauest The following table identifies those actions committed to by Comed in this document.

- Any other actions discussed is this submittal represent intended or planned actions by Comed. They are described to the NRC for the NRC's information and are not regulatory commitments. Please notify Mr. Robert Godley, Zion Station Regulatory Assurance Manager, of any questions regarding this document or any asaociated regulatory commitments.

Commitment Committed Date or Outage None NA

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