Xcel EnergyB W 55362 - NRC

@ Xcel EnergyB

November 30, 2012

Monticello Nuclear Generating Plant 2807 W County Road 75 Monticello, MN 55362

L-MT-12-094 10 CFR 50.55a(g)

U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001

Monticello Nuclear Generating Plant Docket 50-263 Renewed Facility Operating License No. DPR-22

Subject: In-service Testing (IST) Program Plan for Safetv Related Seismic Restraints (Snubbers) for the Fifth 10-Year Interval

Pursuant to 10 CFR 50.55a(g), Northern States Power Company, a Minnesota corporation, d/b/a Xcel Energy (hereafter "NSPM"), the licensee for the Monticello Nuclear Generating Plant (MNGP), hereby submits the enclosed MNGP in-service testing (IST) program for the fifth 10-year interval applicable to Safety Related Seismic Restraints (Snubbers). The IST snubber program plan describes the programmatic aspects of IST examination and testing of snubbers.

The MNGP IST snubber program was developed in accordance with the requirements of the 2004 Edition, with the OMa-2005 and OMb-2006 Addenda, of the ASME OM Code, Subsections ISTA and ISTD in accordance with 10 CFR 50.55a(b).

The Safety Related Seismic Restraints (Snubbers) section of the IST program for MNGP is within the provisions of the ASME OM Code and requires no NRC approval for implementation.

Summarv of Commitments

This letter makes no new commitments and no revisions to existi,ng commitments.

Document Control Desk L-MT-12-094 Page 2 of 2

Should you have questions regarding this letter, please contact Mr. Randy Rippy at (612) 330-691 1.

Mark A. Schimmel Site Vice President, Monticello Nuclear Generating Plant Northern States Power Company - Minnesota

Enclosure

cc: Administrator, Region Ill, USNRC Project Manager, Monticello, USNRC Resident Inspector, Monticello, USNRC

ENCLOSURE

MONTICELLO NUCLEAR GENERATING PLANT (Unit I ) (Provisional License Granted: September 8th, 1970)

SNUBBER IN-SERVICE TESTING PROGRAM PLAN

FIFTH INTERVAL - REVISION 0 December 13th,2012 THROUGH MAY 31st, 2022

15 pages follow

Operated by: NSP-Minnesota 414 Nicollet Mall

MINNEAPOLIS, MN 55401-1993

Owned by: XCEL ENERGY 414 Nicollet Mall

MINNEAPOLIS, MN 55401 -1 993

MONTICELLO NUCLEAR GENERATING PLANT (Unit 1) (Provisional License Granted: September 8th, 1970)

2807 WEST HIGHWAY 75 MONTICELLO, MINNESOTA 55362

SNUBBER IN-SERVICE TESTING PROGRAM PLAN

FIFTH INTERVAL - REVISION 0 December 13'~, 2012 THROUGH MAY 31St, 2022

Prepared By: SEE PASSPORT AR 1338636 SNUBBER PROGRAM COORDINATOR Date

Reviewed By: SEE PASSPORT AR 1 338636 Date

Approved By: SEE PASSPORT AR 1338636 Date

Monticello Nuclear Generating Plant Revision 0

REVISION INDEX

LIST OF TABLES

Table

1

2

3

4

5

6

Description

LC0 Action

Snubber Program Implementation Procedures

Adopted Code Cases Approved in Regulatory Guide 1 . I 92

Code Cases Submitted through Relief Requests

Relief Requests not associated with Code Cases

10 CFR 50.55a Conditions and Clarifications Regarding the Snubber Program

Page

4

5

8

8

8

9


TABLE OF CONTENTS

SECTION PAGE

REVISION INDEX ...................................................................................................................... i

LIST OF TABLES ....................................................................................................................... i

1.0 INTRODUCTION ........................................................................................................... 2

1.1 Overview .............................................................................................................. 2

1.2 Program Examination and Test Plan ....................... .... .................................. 2

2.0 SCOPE ........................................................................................................................... 3

2.1 Overview .............................................................................................................. 3

2.2 Code Classification .................... ....... ............................................................. 3

2.3 Limiting Condition for Operability (LCO) ............................................................... 4

........................................................................................................ 2.3.1 Action 4

2.4 MNGP Site Snubber IST Information Base ...................................................... 4

2.5 Implementing Processes ...................................................................................... 4

2.6 Applicable Documents ....................................................................................... 5

................................................................................................ 2.6.1 Procedures 5

3.0 METHOD OF CLASSIFYING SNUBBERS FOR THE IST PROGRAM .......................... 6

4.0 ALTERNATIVE REQUIREMENTS TO THE ASME OM CODE ...................................... 6

....................................................................................................... 4.1 Code Cases 6

4.2 10 CFR 50.55a Requirements - Code Cases ...................................................... 7

........................................................................................ 4.3 Code Case Adoption: 7

4.3.1 Adoption of Code Cases Accepted for Generic Use in Regulatory ............................................................................................... . Guide 1 192 7

4.3.2 Adoption of Code Cases Not Accepted for Generic Use in Regulatory Guide 1 . 192 via Submittal of Relief Requests ......................... 7

.................................................................................................... 4.4 Relief Requests 8

4.5 10 CFR 50.55a Conditions and Clarifications ..................................................... 9

5.0 PROGRAM IMPLEMENTATION ................................................................................. 10

.................................................................. 6.0 PROGRAM CONFIGURATION CONTROL 10

7.0 BASES ......................................................................................................................... 10

Page 1 of 13

Monticello Nuclear Generating Plant

INTRODUCTION

Revision 0

I I Overview

Monticello begins its fifth IST 10-year interval of commercial plant operation on December 13,2012 and ends on May 31, 2022.

10CFR50.55a invokes preservice and inservice testing (IST) of snubbers per ASME OM Code (Code for Operation and Maintenance of Nuclear Power Plants). Part 50.55a establishes the requirements that each nuclear power plant must develop and implement a preservice and inservice examination and testing program for snubbers. Preservice and inservice tests are used to verify operational readiness of snubbers whose function is required for safety. The examinations and tests, conducted during successive 120-month intervals, must comply with the requirements of the latest edition and addenda of the OM Code that has been incorporated by reference in 1 OCFR50.55a 12 months prior to the start of the interval.

Title 10, Part 50.55a of the Code of Federal Regulations invoke, by reference, the requirement for inservice inspection (ISI) of snubbers per Section XI of the ASME Boiler and Pressure Vessel Code with the added condition that, for 2006 and later editions of Section XI, 10 CFR 50.55a(b)(3)(v) requires the use of ASME OM Code, Subsection ISTD.

The snubber preservice and inservice examination and test plan was developed in accordance with the conditions, clarifications and requirements of 10 CFR 50.55a that became effective on July 21, 201 1.

The edition and addenda of the ASME OM Code for the Snubber IST Program for the fifth 10-year interval is the 2004 Edition, with the 2005 and 2006 Addenda, Subsections ISTA & ISTD [the Code], which was the referenced Code in 10CFR50.55a on December 13, 201 1, or 12 months prior to the start of the fifth IST 10-year interval.

Program Examination and Test Plan

Requirement for preservice and inservice examination and testing was first incorporated into the Code of Federal Regulations; the NRC, ASME, and the nuclear industry have provided additional interpretations to the Code requirements. These interpretations have been documented through various mechanisms such as 10 CFR 50.55a Final Rules, Code Cases, Code Interpretations, generic letters, program review meetings, site inspections, and others. It is the intent of the Monticello Snubber Program to:

Establish a set criteria and philosophy for determining the snubber examination and testing scope,

0 Provide criteria and guidance for consistent classification of each plant snubber to support determination of those required to be included in the program.

Document approved alternatives to Code requirements, as applicable

Identify examination and testing required for each snubber, and implementing documents.

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2.0 SCOPE

2.1 Overview

This document describes the Monticello Nuclear Generating Plant (MNGP) lnservice Testing (IST) Program for Dynamic Restraints (Snubbers) for the fifth ten year interval. This program is adjunctive to the "Fifth ten year Interval lnservice Testing Program," for Valves and Pumps.

The scope of the Snubber IST Program includes snubbers required to perform a specific function in shutting down the reactor to a safe shutdown condition, in maintaining the safe shutdown condition, or in mitigating the consequences of an accident in accordance with ASME OM Code 2004 Edition with the OMb-2006 Addenda, subsection ISTA, paragraph ISTA-1100.

This program was developed to encompass system safety requirements defined in 10 CFR 50.55a as well as snubber functions required in response to the abnormal operational transients and accidents defined in the MNGP Updated Safety Analysis Report (USAR), with classifications as determined using Regulatory Guide 1.26, and NUREG-0800. The program is not limited to the postulated accidents of UFSAR Chapter 15. The MNGP USAR, Technical Specifications, and related design basis documents are the primary references used to determine which snubbers are required to perform specific functions related to the spectrum specified in ISTA-1100. MNGP defines the "Safe Shutdown" and the "Mitigating Consequences of an Accident" in paragraphs 1.4 and 1.5 respectively of the Fifth Ten Year lnservice Testing Program, (ISTP5).

Snubbers excluded from this program are those installed on non-safety related systems, and then only if their failure, or failure of the system on which they are installed, will have no adverse effect on any safety related system.

2.2 Code Classification

The quality group classification system for water, steam, and radioactive waste containing components important to the safety of water-cooled nuclear power plants is established by NRC Regulatory Guide 1.26 in conjunction with 10 CFR 50.55a.

Regulatory Guide 1.26, "Quality Group Classification and Standards", defines the Quality Group Classification System consisting of four Quality Groups, A through D. Quality Group A is defined as "Reactor Coolant Pressure Boundary" by 10 CFR 50.2. The definitions of Groups B, C, and D (Class 2, Class 3 and non-classed, respectively) are provided by Regulatory Guide 1.26.

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Limitins Condition for Operabilitv (LC01

In accordance with the Monticello Technical Specification, paragraph 3.0.8, each safety related snubber shall be operable. Non-safety related snubbers whose failure or failure of the associated system(s) would adversely affect any safety related system shall be operable. The applicability of the LC0 is whenever the supported system is required to be operable.

2.3.1 Action

Separate condition entry is allowed for each individual snubber. The following applies to each condition

Table 1 LC0 Action

2.4 MNGP Site Snubber IST lnformation Base

In the Snubber IST lnformation Base each snubber to be tested in accordance with the requirements of the Code is listed. The Snubber IST lnformation Base contains, as a minimum, the following information about each snubber:

Snubber identification (snubber number, model number, and serial number)

COMPLETION TIME

Immediately

CONDITION

A. One or more required snubber(s) inoperable

Applicable plant system

REQUIRED ACTION

A l . Enter LC0 3.0.8

o ASME Code class

Snubber location information

Test or examination method

0 Test and examination history

Reference 4 Awl-09.04.07, Snubber IST Procedure, Fig 5.6, for a listing of snubbers tested and examined in accordance with this plan. The list provides basic information about snubbers under this plan. The snubber list is maintained up-to-date for the defined snubber population.

2.5 lmplementina Processes

Program inservice examinations and tests required by the Code are implemented by the Snubber IST Program procedures. The Snubber ISP Procedures provide acceptance criteria for the Examinations, Tests and Service Life Monitoring. As a result of the performed examinations and tests, any identified corrective actions and subsequent retests shall be made per the requirements of the Code and the ASME Section XI RepairIReplacement Program.

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In conjunction with the Snubber Program Test Procedure, other Monticello site documents detail Code requirements and implementation processes.

The CAP Action Request (AR) process at Monticello provides a method to document material deficiencies and engineering evaluations required to comply with the Code. Work orders initiated by the AR process will be used to implement corrective maintenance on snubbers identified for Inservice Testing and will allow for recording and tracking component history.

2.6 Awlicable Documents

The details of the Snubber IST Program referenced in this Program Plan are contained in documents that are available at Monticello. These documents include, but are not limited to, piping and instrumentation diagrams, piping isometric drawings, component support drawings, and procedures that support implementation of the Snubber IST Program.

2.6.1 Procedures

Table 2 lists applicable Snubber IST Program Implementation Procedures.

Table 2 Snubber Program Implementation Procedures

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PROCEDURE NUMBER

0251

0255-1

0331

4580-01

4581

4903

PROCEDURE TITLE

SNUBBER OPERABILITY TEST

SNUBBER INSPECTION

SNUBBER RECORDS REVIEW

SNUBBER MAINTENANCE

SNUBBER TRAVELER

SNUBBERCHANGEOUTPROCEDURE


3.0 METHOD OF CLASSIFYING SNUBBERS FOR THE IST PROGRAM

MNGP equipment databases and system design basis documents were reviewed to determine which systems include snubbers that encompass system safety requirements defined in 10 CFR 50 as well as snubbers required in response to the abnormal operational transients and accidents as defined in paragraph 2.1.

Each system was reviewed in the following manner:

The P&ID for each system was reviewed to identify the system boundaries for each class of snubbers that are subject to a specific function in shutting down a reactor to the safe shutdown condition, maintaining the safe shutdown condition, or in mitigating the consequences of an accident.

Each snubber was reviewed for design and arrangement to include allowance for adequate access and clearances for conduct of examination and tests.

4.0 ALTERNATIVE REQUIREMENTS TO THE ASME OM CODE

This section lists the alternative requirements to the Code for specific portions of the Snubber IST Program. The alternative requirements identified meet the rules for alternative requirements that are defined in the Code.

4.1 Code Cases

Code Cases to be used during a preservice or inservice tests and examinations shall be identified in the Snubber lnservice Testing Program Plan. [ISTA 3130(a)]

Code Cases shall be applicable to the edition and addenda specified in the Snubber lnservice Testing Program Plan. [ISTA 3130(b)]

Code Cases shall be in effect at the time the Snubber lnservice Testing Program Plan is filed. [ISTA 3130(c)]

Code Cases issued subsequent to filing the Snubber lnservice Testing Program Plan may be proposed for use in amendments to the test plan by requesting a relief and approval from the NRC. [ISTA 3130(d)]

Superseded Code Cases approved for use may continue to be used for the duration of the Snubber lnservice Testing Program Plan. [ISTA 31401

Code Cases approved for use may be used after annulment for the duration of the Snubber lnservice Testing Program Plan, unless 10CFR50.55a specifically prohibits further use of the annulled Code Case. [ISTA 31501

Endorsement of Regulatory Guide 1 .I92 "Operation and Maintenance Code Case Acceptability, ASME OM Code", does not commit Monticello to all code cases listed therein, but rather allows for selection of applicable code cases. The purpose of this endorsement is to identify all code cases that could potentially be incorporated into the Snubber IST Program.

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4.2 10 CFR 50.55a Requirements - Code Cases

10 CFR 50.55a(b)(6) addresses the application of Code Cases and states the following criteria:

Licensees may apply the ASME Operation and Maintenance Nuclear Power Plants Code Cases listed in Regulatory Guide 1.192 without prior NRC approval subject to the following:

When a licensee initially applies a listed Code Case, the licensee shall apply the most recent version of that Code Case. The Code Case must be applicable to the current Code edition and addenda for the IST program.

If a licensee has previously applied a Code Case and a later version of the Code Case is incorporated, the licensee may continue to apply, to the end of the current 120-month interval, the previous version of the Code Case as authorized or may apply the later version of the Code Case, including any NRC-specified conditions placed on its use

Application of a not approved Code Case is prohibited unless a licensee previously applied the listed Code Case prior to it being listed as not approved in Regulatory Guide 1.193. If a licensee has applied a listed Code Case that is later listed as not approved in Regulatory Guide 1.193, the licensee may continue to apply the Code Case to the end of the current 120-month interval, unless 10CFR50.55a specifically prohibits further use of the not approved Code Case.

4.3 Code Case Adoption:

4.3.1 Adoption of Code Cases Accepted for Generic Use in Regulatory Guide 1.192.

Code Cases that are designated "Acceptable" or "Conditionally Acceptable" for generic use in Regulatory Guide 1.192 (latest revision) and are listed in Table 3 below may be adopted by MNGP for use during the fifth ten year interval. All conditions or limitations delineated in Regulatory Guide 1 . I92 for applicable Code Cases will apply.

4.3.2 Adoption of Code Cases Not Accepted for Generic Use in Regulatory Guide I . 192 via Submittal of Relief Requests.

Adoption of Code Cases that have been approved by the ASME Board of Nuclear Codes and Standards, but that have not been accepted for generic use in Regulatory Guide 1.192, may be submitted in the form of a relief request in accordance with 10 CFR 50.55a(a)(3). Once approved, these relief requests will be available for use by Monticello. The approved Relief Request may be used until the end of the 10-year interval in which it was approved.

Table 4 lists those Code Cases for which relief requests have been submitted. In addition to the requirements stated in the Code Cases, criteria MAY be stipulated in the relief request or may be agreed upon

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through subsequent correspondence with the NRC. Monticello will implement these additional requirements as applicable.

Table 3 Adopted Code Cases Approved in Regulatory Guide 1 .I 92

Code Case Title

Table 4 Code Cases Submitted Through Relief Requests

Code Case Title

4.4 Relief Requests

Relief from the requirements of the OM Code shall be requested where full compliance with the Code will not be achieved. Relief requests are submitted to the NRC for approval pursuant to the requirements of 10 CFR 50.55a.

Table 5 provides a listing of additional relief requests, not associated with a Code Case, that have been written in accordance with 10 CFR 50,55a(a)(3) when specific inservice snubber examinations or testing requirements are considered impractical. If other examination or testing requirements are determined to be impractical during the course of the interval, relief requests may be submitted in accordance with 10 CFR 50.55a.

Table 5 Relief Requests Not Associated With a Code Case

Affected Program

Area Relief Request Subject

NONE

(1) Relief Request No. (2) Correspondence No. (3) Relief Request Date


4.5 10 CFR 50.55a Conditions and Clarifications

Certain paragraphs in 10 CFR 50.55a list the conditions and lor clarifications to the implementation requirements of the Code. The paragraphs in 10 CFR 50.55a applicable to the Snubber IST Program at Monticello are included by reference in Table 6.

Table 6 CODE OF FEDERAL REGULATIONS 10 CFR 50.55a

(A) Licensees may use Subsection ISTD, " Preservice and lnservice Examination and Testing of Dynamic Restraints (Snubbers) in Light-Water Reactor Power Plants," ASME OM Code 1995 Edition through the latest edition and addenda incorporated by reference in paragraph (b)(3) of this section, in place of the requirements for snubbers in the editions and addenda up to 2005 Addenda of the ASME B&PV Code, Section XI, IWF-5200(a) and (b) and IWF-5300(a) and (b) by making appropriate changes in their technical specifications or licensee-controlled documents. Preservice and lnservice examinations must be performed using the VT-3 visual examination method described in IWA-2213.

(B) Licensees shall comply with the provisions for examining and testing snubbers in subsection ISTD of the ASME OM Code and make appropriate changes in their technical specifications or

nd addenda of Section

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5.0 PROGRAM IMPLEMENTATION

The MNGP Snubber IST Program Procedure details program implementation based on the Code and alternate requirements of the Code.

Snubber program preservice and inservice examinations and tests required by the Code shall be implemented in accordance with the Snubber IST Program Procedure. The Snubber IST Program Procedure shall be used to identify the examination and test methods for verifying operational readiness of the snubber, to identify the frequency of the required examinations and tests, to establish plant conditions for performing examinations and tests, to document the results of snubber examinations and testing, and to monitor service life. The examinations and tests act as the record of testing required by the Code. CAP AR process is an integral part of the snubber program and is implemented in accordance with stations procedures and ISTA-3300 and ISTD-5280.

Reference Table 2 for a listing of the applicable Snubber IST Program implementing procedures.

6.0 PROGRAM CONFIGURATION CONTROL

As a minimum, the snubber IST program will be reviewed and revised as necessary for compliance with the Code in effect as referenced by 10 CFR 50.55a 12 months prior to the end of the fifth 120-month interval of commercial operation. Additionally, the scope of the program is subject to revision due to changes in system design, changes in design that affect the snubber safety function, or revisions to the applicable code requirements through Alternate Requirements to the Code. In order to accommodate these changes, Monticello reserves the right to submit program revisions that will enhance or improve the program at any time within the effective interval.

7.0 BASES

7.1 Background

Component standard supports are those metal supports which are designed to transmit loads from the pressure-retaining boundary of the component to the building structure. Although classified as component standard supports, snubbers require special consideration due to their unique function. Snubbers are designed to provide no transmission of force during normal plant operations, but function as a rigid support when subjected to dynamic transient loadings. Therefore, snubbers are chosen in lieu of rigid supports where restricting thermal growth during normal operation would induce excessive stresses in the piping nozzles or other equipment. The location and size of the snubbers are determined by stress analysis. Depending on the design classification of the particular piping, different combinations of load conditions are established. These conditions combine loading during normal operation, seismic loading and loading due to plant accidentsltransients. The actual loading included in each of the conditions, depends on the design classification of the piping. The calculated stresses in the piping and other equipment, for each of the conditions, must be in conformance with established design limits.

All safety related snubbers are required to be OPERABLE whenever the supported system is required to be OPERABLE. The Technical Requirements for Operation is

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based on ensuring that the structural integrity of the reactor coolant system and all other safety related systems is maintained during and following a seismic or other event initiating dynamic loads. Snubbers excluded from this inspection program are those installed on non-safety related systems and then only if their failure or failure of the system on which they are installed would have no adverse effect on any safety related system.

7.2 Applicable Design Bases

The specific design and service loading combinations used for the design of supports in safety-related systems provides assurance that, in the event of an earthquake or other service loadings due to postulated events or system operating transients, the resulting combined stresses imposed on system components will not exceed allowable stress and strain limits for the materials of construction. Limiting stresses under such loading combinations provides a conservative basis for the design of support components to withstand the most diverse combination of loading events without loss of structural integrity or supported component OPERABILITY.

7.3 Limitins Condition for Operation (LC01

Snubbers are required to be OPERABLE to ensure that the structural integrity of the Reactor Coolant System and all other safety-related systems is maintained during, and following, a seismic event or other event initiating dynamic loads. All safety-related snubbers are required snubbers for this LCO. Additionally, snubbers installed on non-safety- related systems are required snubbers for this LC0 if their failure, or failure of the system on which they are installed, would have an adverse effect on any safety-related system.

Individual snubbers may be removed from service for functional testing within the limits established herein without violating these requirements, although the Required Action and Completion Time still applies.

7.4 Applicabilitv

Each safety related snubber and non-safety related snubber (whose failure, or failure of the associated system(s), would adversely affect any safety related system) shall be OPERABLE whenever the supported system is required to be OPERABLE.

In MODES 1, 2, and 3, this LC0 applies since safety related systems supported by snubbers are required to mitigate the consequences of a design basis accident to protect the reactor core and prevent the release of radioactive material to the environment. In MODES 4 and 5, only selected safety-related systems are necessary to ensure adequate coolant inventory and sufficient heat removal capability, or to mitigate the effects of a fuel handling accident. Therefore, only snubbers on systems required to be OPERABLE in MODES 4 and 5 are required to be OPERABLE in these MODES. In any of these MODES, any non-safety related snubbers whose failure, or failure of the associated system(s), would adversely affect any safety related system shall be OPERABLE.

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7.5 Actions

The ACTIONS Table is modified by a Note indicating that a separate Condition entry is allowed for each snubber. This is acceptable, since the Required Actions for each Condition provide appropriate compensatory actions for each inoperable snubber. Complying with the Required Actions may allow for continued operation, and subsequent inoperable snubbers are governed by subsequent Condition entry and application of associated Required Actions.

With one or more required snubbers inoperable, the ability of the affected piping system(s) to withstand dynamic loadings due to seismic events or system operating conditions is degraded. Required Action A. 1 and the associated Completion Time requires LC0 3.0.8 to be entered immediately when one or more required snubbers are inoperable. This is acceptable because LC0 3.0.8 establishes the conditions under which systems are considered to remain capable of performing their intended safety function when associated snubbers are not capable of providing their associated support function(s). LC0 3.0.8 states that the supported system is not considered to be inoperable solely due to one or more snubbers not capable of performing their associated support function(s). This is appropriate because a limited length of time is allowed for maintenance, testing, or repair of one or more snubbers not capable of performing their associated support function(s).

7.6 Surveillance Requirements

In-service examination and testing of each safety related snubber is required to be performed in accordance with the Snubber In-service Testing Program (IST). The frequency and interval of examination and testing is in accordance with the IST Program.

7.7 Snubber In-service Testinq (IST) Proqram

Visual in-service examination and operational readiness testing frequencies and intervals for snubbers are based upon performance and maintaining a constant level of snubber protection to systems.

Visual examinations will be performed at the time snubbers are removed for maintenance or testing in accordance with ISTD-4230, ISTD-4250 as modified by Code Case OMN-13 (Reference 2). The visual inspection frequency basis is described in the 2004 Edition of the ASME Operation and Maintenance (OM) Code, OMa-2005 through OMb-2006 Addenda, Subsections ISTD and lSTA (Reference 1) as modified by the incorporation of ASME OM Code Case OMN-13 (Reference 2), which has been approved by the NRC (Reference 3). Monticello has reviewed and meets all of the criteria to adopt Code Case OMN-13 allowing visual inspections to be performed at the time the snubber is removed for maintenance and testing.

When the snubber is classified as unacceptable during visual in-service examination, the cause of the snubber condition is clearly established and remedied for that snubber and for any other snubbers that may be generically susceptible and verified acceptable by functional testing. Acceptable results from functional testing will exempt the snubber from being counted as inoperable.

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If at any time during an examination interval in accordance with Code Case OMN-13 the cumulative number of unacceptable snubbers exceeds the applicable value from Column B in Table ISTD-4252-1, the current examination interval shall end, and all remaining examinations must be completed within the current fuel cycle. The duration of the subsequent examination interval shall be reduced in accordance with Table ISTD-4252-1, using the examination interval prior to implementing Code Case OMN-13 as the base interval. The beginning of the subsequent fuel cycle shall be the starting date for the new examination interval.

The basis for operational readiness testing of snubbers is described in 2004 Edition of the ASME OM Code, OMa-2005 through OMb-2006 Addenda, Subsections ISTD and ISTA (Reference 1). A 10% testing sample plan is used in accordance with ISTD-5300. A representative sample of 10% of the installed, safety related snubbers will be functionally tested during plant refueling outages at intervals of no more than 24 months. Inoperable snubbers in these samples will require operability testing of additional units. A sample size of one-half of the initial test sample is described in Paragraph ISTD-5312 of Subsection ISTD of the ASME OM Code (Reference 1).

When a snubber is found inoperable, an engineering evaluation or inspection is performed, in addition to the determination of the snubber mode of failure, in order to determine if any safety-related component or system has been adversely affected by the inoperability of the snubber. The evaluation or inspection will determine whether or not the snubber mode of failure has imparted a significant effect or degradation on the supported component or system.

In accordance with paragraph ISTD-6000, the service life of a snubber is evaluated via manufacturer input and through consideration of the snubber service conditions and associated installation and maintenance records (newly installed snubber, seal replacement, spring replacement, in high radiation, in high temperature area, etc.). The requirement to monitor the snubber service life is included to ensure that the snubbers periodically undergo a performance evaluation in view of their age and operating conditions. These records will provide statistical bases for future consideration of snubber service life.

7.8 Bases References

1. ASME OM Code 2004 Edition with OMa-2005 through OMb-2006 Addenda, "Code for Operations and Maintenance of Nuclear Power Plants." Subsections ISTD, Preservice and lnservice Examination and Testing of Dynamic Restraints (Snubbers) in Light Water Reactor Power Plants" and ISTA, "General Requirements."

2. ASME OM Code, 2004 Edition, Code Case OMN-13, "Requirements for Extending Snubber lnservice Visual Examination Interval at LWR Power Plants."

3. US NRC Regulatory Guide 1.192, "Operations and Maintenance Code Case Acceptability, ASME OM Code."

4. 4 Awl-09.04.07, Snubber IST Program Procedure, Rev 0.

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