ML050950218

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Station. Supplement to Relief Request RI-01
ML050950218
Person / Time
Site: Vermont Yankee File:NorthStar Vermont Yankee icon.png
Issue date: 03/31/2005
From: Devincentis J
Entergy Nuclear Operations
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
BVY 05-27
Download: ML050950218 (8)
v • d • e


Text

Entergy Nuclear Northeast Entergy Nuclear Operations, Inc.

Vermont Yankee

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Box 0500 185 Old Ferry Road lamp 3EV Brattleboro, VT 05302-0500 Em~o Tel 802 257 5271 March 31, 2005 BVY 05-27 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555

Subject:

Vermont Yankee Nuclear Power Station License No. DPR-28 (Docket No. 50-271)

Supplement to Relief Reguest RI-01 By letter dated October 1, 2003', as supplemented by letters dated December 23, 20032, and January 22, 20043, Vermont Yankee Nuclear Power Station (VY) submitted Relief Request RIl.

Relief Request RI-01 proposed to use various Boiling Water Reactor Vessel Internals Program guidelines as an alternative to certain requirements of Section XI of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code for Inservice Inspection of Reactor Pressure Vessel internal components.

On January 4, 20054, The NRC submitted a Request for Additional Information regarding RI-01.

Accordingly, the attachment provides the response to request for additional information.

There are no commitments contained within this letter.

Please feel free to contact me at (802) 2584236, if there are any questions regarding this subject.

Sincerely,

//

James M. DeVincentis Manager, Licensing Vermont Yankee Nuclear Power Station cc:

USNRC Region I Administrator USNRC Resident Inspector - VY USNRC Project Manager - VY Vermont Department of Public Service Reference VY Letter to USNRC, BVY 03-89, "Supplement 2 to Fourth-Interval Inservice Inspection (ISI)

Program Plan - Submittal of Relief Request RI-01," dated October 1, 2003.

2 Reference VY Letter to USNRC, BVY 03-120, "Supplement to Relief Request RI-0l," dated December 23, 2003.

3 Reference VY Letter to USNRC, BVY 04-07, "Supplement to Relief Request RI-OI," dated January 22, 2004.

4 Reference USNRC Letter to VY, NVY 05-01, "Request for Additional Information - Relief Request RI-01 (TAC No. MC0960)," dated January 4, 2005.

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ATTACHMENT TO BVY 05-27 Supplement to Relief Request RI-01 ENTERGY NUCLEAR OPERATIONS, INC.

VERMONT YANKEE NUCLEAR POWER STATION DOCKET NO. 50-271

On January 4, 2005', The NRC submitted a Request for Additional Information regarding RI-0 1.

Accordingly, the attachment provides the response to request for additional information.

Question 1:

Relief request RI-01 includes the following statement as an all-inclusive technical basis for the proposed alternative inspections:

The NRC has agreed with the BWRVIP approach in principal and has issued Safety Evaluations for these guidelines. Therefore, use of these guidelines, as an alternative to the subject Code requirements, provides an acceptable level of quality and safety and will not adversely impact the health and safety of the public.

The technical basis for the proposed alternative inspection of each component, or group of components, is not specified in the relief request. For each component, or group of components for which relief from the ASME Code is requested, discuss how the proposed alternative inspection method, scope of examination, inspection frequency, and acceptance criteria provide an acceptable level of quality and safety as compared to the ASME Code.

Response to Question 1:

The following paragraphs provide the requested inspection criteria discussion for each group of component based on Code Subsections. Each section includes several examples of components or welds that belong in each Code Subsection.

B13.10 Reactor Vessel Interior Accessible Areas B-N-I The ASME Section XI Code requires a VT-3 inspection of reactor vessel interior surfaces made accessible every three and a third (3 1/3) years during each 10 year interval. This is a non-specific inspection requiring inspection of surfaces made accessible during refueling.

The various BWRVIP Inspection and Evaluation guidelines require, as a minimum, a VT-3 inspection of reactor vessel interior components. Additionally, the BWRVIP guidelines require that many component welds and weld heat affected zones in this category be inspected by a VT-I, EVT-1, or UT. The BWRVIP inspection method meets (VT-3) or exceeds (VT-I, EVT-1, or UT) the inspection method requirements specified by the Code.

The Core Spray piping and sparger is used as an example for comparison between the Code and the BWRVIP inspection requirements.

BWR Core Spray Internals Inspection and Flaw Evaluation Guideline (BWRVIP-1 8)

  • The Section XI Code requires a VT-3 each period (3 1/3 years) of each 10 year interval of the Core Spray internal piping and sparger accessible surfaces.
  • The BWRVIP requires either an EVT-lof the core spray pipe creviced welds and weld heat affected zones each refuel outage (1 V2 year) along with 25% of the non creviced weld locations on a rotated basis or UT. If UT is performed on the creviced weld locations, then the frequency is every other Reference USNRC Letter to VY, NVY 05-01, "Request for Additional Information - Relief Request RI-01 (TAC No. MC0960)," dated January 4, 2005.

BVY 05-27, Attachment, Page 1 of 6

outage (3 years). 50 % of the Core Spray sparger welds require a VT-I inspection every other outage (3 years).

The BWRVIP inspection methods are superior to the Code inspection methods. The BWRVIP specifies EVT-I and UT inspections to detect small tight cracks before component functionality is challenged. The BWRVIP inspections are directed to component welds and weld heat affected zones, where experience has shown IGSCC cracks will initiate. The BWRVIP specified EVT-I and UT examination have superior crack detection and characterization capability as compared to the Code VT-3. The inspection of high susceptibility creviced weld locations every outage (visual EVT-1) or every other outage (UT) is superior in crack detection and inspection frequency to the VT-3 examination required every period. The 25%

sampling ensure all welds are inspected in a 10 year interval. The BWRVIP inspection requirements for reactor vessel interior accessible areas provide an acceptable level of quality and safety as compared to the Code requirements by providing an equivalent or in most cases superior inspection methods.

Additional examples of components in this category are:

B 13.20 Interior Attachments Within the Beltline (B-N-2)

  • The ASME Code requires a VT-1 inspection of accessible reactor inside surface attachment welds each 10 year interval.
  • The BWRVIP requires an EVT-I inspection on the majority of attachment welds in the beltline region in the first 12 years and then 25% during each subsequent 6 years.

The Jet Pump Riser Brace inspection requirements are provided to show a comparison between the Code and the BWRVIP inspection requirements.

Jet Pump Riser Braces (BWRVIP-41)

  • The Code requires a 100% VT-I inspection of the Jet Pump riser brace-to-reactor vessel wall pad welds each 10 year interval.
  • The BWRVIP requires an EVT-I inspection of the Jet Pump Beam riser brace-to-reactor vessel wall pad welds the first 12 years and then 25% during each subsequent 6 years.

The Code VT-I examination is conducted to detect discontinuities and imperfections on the surfaces of components, including such conditions as cracks, wear, corrosion, or erosion. The BWRVIP enhanced VT-I (EVT-1) is conducted to detect discontinuities and imperfections on the surface of components, including fatigue cracks and very tight cracks characteristic of inter-granular stress corrosion cracking (IGSCC). General wear, corrosion, or erosion although generally not a concern for stainless steel as it is inherently tough, corrosion resistant material, however, the process of performing an EVT-I inspection would detect such degradation mechanisms.

The Code VT-I visual inspection method requires at a maximum distance of 2 feet a letter character with a height of 0.044 inches can be read. The BWRVIP EVT-I is a visual inspection method where the equipment and environmental conditions are such that they can achieve a 1/2 mil (0.0005 inch) resolution on the inspection surface.

BVY 05-27, Attachment, Page 2 of 6

The ASME Code and the BWRVIP have the same flaw evaluation criteria for detected indications. Both criteria measure the observed surface indication and compare them against acceptable flaw sizes determined by ASME Section Xl.

The BWRVIP inspection method of interior attachments within the reactor vessel beltline has superior flaw detection capability (0.0005" versus 0.044" resolution) compared to the Code. It is judged that the enhanced flaw detection capability of an EVT-1, with a less frequent inspection schedule and the same flaw evaluation criteria, results in the BWRVIP inspection requirement providing the same level of quality and safety to that provided by the ASME Code.

BI 3.30 Interior Attachment Beyond the Beltline Region (B-N-2)

The BWRVIP requires as a minimum the same VT-3 inspection method as the Code for interior attachment welds beyond the beltline region and in some cases specifies an enhanced visual inspection technique EVT-I.

As described in the table provide in BVY-03-89 Attachment 2 (Reference 1), the following components have the same VT-3 method of inspection, the same scope of inspection (accessible welds), the same inspection frequency (each 10 year interval) and ASME Section XI flaw evaluation criteria. Therefore, the level of quality and safety provided by the BWRVIP requirements are equivalent to that provide by the ASME Code. Examples of component attachment welds in this category are:

  • Surveillance Specimen Holder Brackets (BWRVIP-48)

Additionally, there are interior attachment welds outside the beltline region that the BWRVIP requires an EVT-l inspection instead of the Code required VT-3 inspection. The inspection frequency for EVT-I is every 6 years. The Code VT-3 examination is conducted to detect component structural integrity by ensuring components general condition is acceptable.

An enhanced EVT-I is conducted to detect discontinuities and imperfections on the inspection surfaces, including such conditions as tight cracks caused by IGSCC. Therefore, with the EVT-I inspection method, the same inspection scope (accessible welds), an increased inspection frequency (6 years instead of 10 years) and the same flaw evaluation criteria (Section XI), the level of quality and safety provided by the BWRVIP criteria is superior than that provided by the Code.

The Core Spray piping bracket-to-vessel attachment weld is used as an example for comparison between the Code and BWRVIP inspection requirements.

Vessel ID Attachment Weld Inspection and Flaw Evaluation (BWRVIP-48)

  • The Code inspection requirement is a VT-3 inspection of each weld every 10 years.

The BWRVIP examination method EVT-I has superior flaw detection and sizing capability, the inspection frequency is greater than the Code requirements and the same flaw evaluation criteria are used.

Therefore the BWRVIP inspection criteria will provide a superior level of quality and safety as provided by the Code.

BVY 05-27, Attachment, Page 3 of 6

B1 3.40 Integrally Welded Core Support Structure-Shroud Support (B-N-2)

  • The Code requires a VT-3 of accessible surfaces each 10 year interval.
  • The BWRVIP requires as a minimum the same inspection method VT-3 as the Code for integrally welded Core Support Structures or either an enhanced visual inspection technique EVT-l or volumetric examination UT.

As described in the Table provide in BVY 03-89 Attachment 2, the following components have the same VT-3 method of inspection, the same scope of inspection (accessible surfaces), the same inspection frequency (each 10 year interval) and the same flaw evaluation criteria.

Therefore the BWRVIP requirements provide a level of quality and safety equivalent to that provide by the ASME Code. An example of a component in this category is:

  • Core Shroud Repair Tie-rods The BWRVIP may also require either an EVT-I or UT of core support structures. The core shroud is used as an example for comparison between the Code and BWRVIP inspection requirements.

BWR Core Shroud Inspection and Flaw Evaluation Guideline (BWRVIP-76)

  • The Code requires a VT3 of accessible surfaces every 10 years.
  • The BWRVIP requires an EVT-I of each core shroud design reliant weld every 10 years or an ultrasonic examination every 6 years.

This BWRVIP examination methods (EVT-1 or UT) are superior to the Code required VT-3 for flaw detection and characterization. The BWRVIP inspection frequency is equivalent to or greater than the inspection frequency required by the Code. The superior flaw detection and characterization capability, with an equivalent or greater inspection frequency and the same flaw evaluation criteria, results in the BWRVIP criteria providing a level of quality and safety equivalent to or superior to that provided by the Code requirements.

Question 2:

The licensee should provide an explanation on the term "number" shown under "Table Key" in Table 1 of BVY 04-07, Attachment 2 of the submittal dated January 22, 2004. For example, in Table I under the column 2007, the planned inspection for Control Rod Drive Guide Tube Body Welds is EVTI (4). It is understood that 4 welds will be inspected for this component. However, there is no information on the total number of welds that exist in the subject component. Provide the total population of the welds for each component.

Response to Question 2:

The number following the inspection method listed in Table I of BVY 04-07, attachment 2 represent the number of components to be inspected that outage. This "number" does not represent the number of welds on each component. For example in 2007 "4" distinct control rod guide tube locations will be inspected. Each control rod guide tube location has 4 welds and a pin that are required to be inspected by BWRVIP-47, Table 3.2-1. Two of these four welds are examined by EVT-I and the other two welds by BVY 05-27, Attachment, Page 4 of 6

VT-3. Table I below identifies every component in the program and provides the total number of welds in each component.

TABLE I Reactor Internal Component BWRVIP Reference Number of Document Welds/Component or loop Control Rod Drive Guide Tube BWRVIP-47, Table 3.2-1 2

Body Welds Control Rod Drive Guide Tube BWRVIP-47, Table 3.2-1 2

Lug and Pin Core Plate Rim Hold-Down Bolts BWRVIP-25, Table 3-2 30 Bolts Core Shroud Horizontal Welds BWRVIP-76, Figure 2-3 3

(HI, H2, H3)

Core Shroud Horizontal Welds BWRVIP-76, Section 3.2 4

(H4-H7)

Core Shroud Vertical Welds BWRVIP-76, Figure 3-3 10 Core Shroud TG Ring Segment BWRVIP-76, Section 3.4 3

Welds Core Shroud CP Ring Segment BWRVIP-76, Section 3.4 3

Welds Core Shroud Flange Ring BWRVIP-76, Section 3.4 3

Segment Welds Core Shroud Tie-Rod Repair BWRVIP-76, Section 3.5 4 Tie Rods Core Shroud Support Welds (H8, BWRVIP-38, Figures 34, 3-5 2

H9)

Core Spray Thermal Sleeve BWRVIP-1 8, Section 3.2.4 3 per loop (2 loops)

Welds (Hidden).

Core Spray Piping Welds (except BWRVIP-1 8, Figure 3-3 22 per loop (2 loops)

P9)

Core Spray P9 Welds BWRVIP-1 8, Section 3.2.4 2 per loop (2 loops)

Core Spray Sparger Large Circ BWRVIP-1 8, Figure 3-4 7 per loop (4 loops)

Welds Core Spray Sparger Nozzle Welds BWRVIP-1 8, Figure 34 61 nozzles per loop (4 loops)

Core Spray Piping Brackets BWRVIP-1 8, Section 3.3.3 2 per loop (2 loops)

Core Spray Sparger Brackets BWRVIP-18, Section 3.3.3 6 per loop (2 loops)

Feedwater Sparger Tee Welds NUREG 0619 2 per loop (4 loops)

Feedwater Sparger End Bracket BWAVIP-48, Table 3-2 2 per loop (4 loops)

Attachment Feedwater Sparger Piping and NUREG 0619 2 brackets per loop Brackets (4 loops)

Jet Pump Beams BWRVIP-41, Table 3.3-1 20 Jet Pump Thermal Sleeve Welds BWRVIP-41, Table 3.3-1 3 per Jet Pump (Hidden)

(10 Jet Pumps)

Jet Pump Riser Welds (RS-1, BWRVIP-41, Table 3.3-1 3 per Jet Pump RS-2, RS-3)

(10 Jet Pumps)

Jet Pump Riser Welds (RS4, BWRVIP41, Table 3.3-1 8 per Jet Pump RS-5, RS-8, RS-9)

I_(10 Jet Pumps)

BVY 05-27, Attachment, Page 5 of 6

Jet Pump Riser Brace Welds BWRVIP41, Table 3.3-1 12 per Jet Pump (10 Jet Pumps)

Jet Pump Inlet Bolted Connection BWRVIP-41, Table 3.3-1 2 per Jet pump (10 Jet Pumps)

Jet Pump Restrainer Wedges BWRVIP-41, Table 3.3-1 2 per Jet Pump (10 Jet Pumps)

Jet Pump Mixer Weld MX-l BWRVIP-41, Table 3.3-1 2 per Jet Pump (10 Jet Pumps)

Jet Pump Mixer/Diffuser Welds BWRVIP-41, Table 3.3-1 14 per Jet Pump (above shell)

(10 Jet Pumps)

Lower Plenum (CRD, Core BWRVIP47 89 CRDs Shroud Support) 14 shroud support legs Miscellaneous Vessel Internal BWRVIP48, Table 3-2 12 Attachments Orificed Fuel Support Castings BWRVIP-47, Table 3.2-1 89 SLC Nozzle-to-Safe End Weld BWRVIP-27, Section 3.3.1 1

Steam Dryer Support Bracket BWRVIP-48, Table 3-2 4

Top Guide Aligner Assemblies BWRVIP-26, Table 3-2 4

Top Guide Hold-down BWRVIP-26, Table 3-2 4

Assemblies Top Guide Grid Beams BWRVIP-26, Section 3.2.2 24 BVY 05-27, Attachment, Page 6 of 6

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