ML093080382

Evaluation of Relief Requests Associated with the Third Inservice Testing Interval (TAC ME0742 - ME0751)

ML093080382
Person / Time
Site:	Limerick
Issue date:	11/17/2009
From:	Chernoff H Plant Licensing Branch 1
To:	Pardee C Exelon Nuclear
Bamford, Peter J., NRR/DORL 415-2833
References
TAC ME0742, TAC ME0743, TAC ME0744, TAC ME0745, TAC ME0746, TAC ME0747, TAC ME0748, TAC ME0749, TAC ME0750, TAC ME0751
Download: ML093080382 (15)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555*0001 November 17, 2009 Mr. Charles G. Pardee President and Chief Nuclear Officer Exelon Nuclear 4300 Winfield Road Warrenville, IL 60555

SUBJECT:

LIMERICK GENERATING STATION, UNITS 1 AND 2 - EVALUATION OF RELIEF REQUESTS ASSOCIATED WITH THE THIRD INSERVICE TESTING INTERVAL (TAC NOS. ME0742 - ME0751)

Dear Mr. Pardee:

By letter dated February 18, 2009 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML090500720), as supplemented by letter dated July 16, 2009, (ADAMS Accession No. ML091970599), Exelon Generating Company, LLC (the licensee) submitted various proposed alternatives to the requirements of Title 10 of the Code of Federal Regulations (10 CFR), Section 50.55a, concerning the third 1O-year inservice testing (1ST) programs at Limerick Generating Station (LGS), Units 1 and 2.

Specifically, the reliefs requested in the February 18, 2009, submittal are as follows:

Relief Request No. Subject NRC TAC No.

Use of Code Case OMN-6, Alternative Rules for GPRR-5, Revision 0 ME07421 ME0743 Digital Instruments Use of Code Case OMN-9, Emergency Service 11-PRR-1, Revision 1 ME07441 ME0745 Water (ESW) Pump Curves Installed Pump Instrumentation Greater than 2 90-PRR-1, Revision 1 ME07461 ME0747 Percent GVRR-5, Revision 3 Series-Parallel Check Valve Testing ME07481 ME0749 Control Rod Drive Scram Valves and Check 47-VRR-2, Revision 0 ME07501 ME0751 Valves In the letter dated July 16, 2009, the licensee submitted additional requested information, withdrew relief request GVRR-5, Revision 3, and revised relief requests 11-PRR-1, Revision 1 and 47-VRR-2, Revision O.

Pursuant to 10 CFR 50.55a(a)(3)(i), relief requests GPRR-5, Revision 0, 90-PRR-1, Revision 1 and 47-VRR-2, Revision 0 are authorized on the basis that the proposed alternative provides an acceptable level of quality and safety. Pursuant to 10 CFR 50.55a(f)(6)(i), relief request 11-PRR-1, Revision 1, is granted based on the impracticality of performing testing in accordance with the American Society of Mechanical Engineers Code for Operation and Maintenance of Nuclear Power Plants, ISTB-5221 and ISTB-5223 test requirements, and in consideration of the burden on the licensee if the code requirements were imposed on the facility.

C. Pardee -2 The third 1O-year 1ST interval begins on January 8, 2010, and is scheduled to conclude on January 7, 2020, for LGS, Units 1 and 2.

Documentation of the NRC staff review and evaluation is contained in the enclosed safety evaluation. If you have any questions, please contact the Limerick Project Manager, Mr. Peter J.

Bamford, at 301-415-2833.

Sincerely, II--//~~

Harold K. Chernoff, Chief / /

Plant Licensing Branch 1-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-352 and 50-353

Enclosure:

As stated cc w/encl: Distribution via Listserv

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555*0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION THIRD 10-YEAR INSERVICE TESTING INTERVAL RELIEF REQUESTS EXELON GENERATION COMPANY, LLC LIMERICK GENERATING STATION, UNITS 1 AND 2 DOCKET NOS. 50-352 AND 50-353

1.0 INTRODUCTION

By letter dated February 18, 2009 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML090500720), as supplemented by letter dated July 16, 2009, (ADAMS Accession No. ML091970599), Exelon Generating Company, LLC (the licensee) submitted various proposed alternatives to the requirements of Title 10 of the Code of Federal Regulations (10 CFR), Section 50.55a, concerning the third 1O-year inservice testing (1ST) programs at Limerick Generating Station (LGS), Units 1 and 2.

Specifically, the reliefs requested in the February 18, 2009, submittal are as follows:

Relief Request No. Subject NRC TAC No.

Use of Code Case OMN-6, Alternative Rules for GPRR-5, Revision 0 ME07421 ME0743 Digital Instruments Use of Code Case OMN-9, Emergency Service 11-PRR-1, Revision 1 ME07441 ME0745 Water (ESW) Pump Curves Installed Pump Instrumentation Greater than 2 90-PRR-1, Revision 1 ME07461 ME0747 Percent GVRR-5, Revision 3 Series-Parallel Check Valve Testinq ME07481 ME0749 Control Rod Drive Scram Valves and Check 47-VRR-2, Revision 0 ME0750/ ME0751 Valves In the letter dated July 16, 2009, the licensee submitted additional requested information, withdrew relief request GVRR-5, Revision 3, and revised relief requests 11-PRR-1, Revision 1 and 47-VRR-2, Revision O. The third 10-year 1ST interval begins on January 8,2010, and is scheduled to conclude on January 7,2020, for LGS, Units 1 and 2.

2.0 REGULATORY EVALUATION

Section 50.55a of 10 CFR, requires that 1ST of certain American Society of Mechanical Engineers (ASME) Code Class 1, 2, and 3 pumps and valves be performed at 120-month (1O-year) program intervals in accordance with the specified ASME Code and applicable addenda incorporated by reference in the regulations, except where alternatives have been authorized, or relief has been Enclosure

-2 requested, by the licensee and granted by the U.S. Nuclear Regulatory Commission (NRC) pursuant to paragraphs (a)(3)(i), (a)(3)(ii), or (f)(6)(i) of 10 CFR 50.55a. In accordance with 10 CFR 50.55a(f)(4)(ii), licensees are required to comply with the requirements of the latest edition and addenda of the ASME Code incorporated by reference in the regulations 12 months prior to the start of each 120-month 1ST program interval. In accordance with 10 CFR 10.55a(f)( 4)(iv),

1ST of pumps and valves may meet the requirements set forth in subsequent editions and addenda that are incorporated by reference in 10 CFR 50.55a(b), subject to NRC approval.

Portions of editions or addenda may be used provided that all related requirements of the respective editions and addenda are met. NRC guidance contained in Generic Letter (GL) 89-04, "Guidance on Developing Acceptable Inservice Testing Programs," provides alternatives to ASME Code requirements which are acceptable. Further guidance is given in GL 89-04, Supplement 1, and NUREG-1482 Revision 1, "Guidance for Inservice Testing at Nuclear Power Plants." ASME Operation and Maintenance (OM) code cases that are approved for use by the NRC are listed in Regulatory Guide (RG) 1.192, "Operation and Maintenance Code Case Acceptability, ASME OM Code," Revision 0, dated June 2003.

The LGS, Units 1 and 2, third 10-year 1ST interval begins on January 8,2010. The program was developed in accordance with the 2004 Edition of the ASME OM Code. By letter dated February 18, 2009, supplemented by letter dated July 16, 2009, the licensee submitted requests for alternatives for the third 1O-year 1ST program interval at LGS, Units 1 and 2.

The NRC's findings, with respect to authorizing alternatives and granting relief relating to the LGS, Units 1 and 21ST program, are given below:

3.0 TECHNICAL EVALUATION

3.1 Relief Request GPRR-5 Revision 0 3.1.1 Code Requirements ISTA-3130 (Application of Code Cases) requires that Code Cases shall be applicable to the edition and addenda specified in the test plan and that Code Cases shall be in effect at the time the test plan is filed.

ISTB-3510 (Data Collection-General) states that digital instruments shall be selected such that the reference value does not exceed 70 percent of the calibrated range of the instrument.

The components affected by this request are all ASME code class 2 and 3 pumps, except skid mounted, in the scope of the LGS, Units 1 and 2, 1ST program.

The licensee's code of record is the ASME OM Code, 2004 Edition. The 1O-year service interval is scheduled to begin on January 8, 2010, and conclude on January 7, 2020.

3.1.2 Licensee's Basis for Requesting an Alternative The licensee states:

Pursuant to 10 CFR 50.55a, "Codes and standards," paragraph (a)(3)(i), relief is requested from the requirement of ASME OM Code ISTB-3510(b)(2). This request

-3 is to allow the use of ASME Code Case OMN-6, "Alternate Rules for Digital Instruments."

OMN-6 allows reading up to 90 percent of the calibrated range of the instrument versus the referenced applicable requirement of 70 percent from the ASME OM Code, 2004 Edition, Paragraph ISTB-351 O(b)(2). OMN-6 permits the use of a greater usable range of the permanently installed instruments at LGS, Units 1 and 2.

NUREG-1482, Revision 1, Section 5.5 states that "The NRC has accepted Code Case OMN-6 as specified in [Regulatory Guide] RG 1.192, which allows each digital instrument to be such that the reference values do not exceed 90 percent of the calibrated range of the instrument."

3.1.3 Licensee's Proposed Alternative Testing The licensee states:

Use of Code Case OMN-6, approved by the NRC in RG 1.192, will provide at least equivalent instrumentation accuracy requirements for the required pump testing parameters to be measured in the 1ST program and will provide results consistent with the code requirements. This will provide adequate assurance of acceptable pump performance.

3.1.4 Evaluation Pursuant to 10 CFR 50.55a(f)( 4)(ii), the LGS 1ST program will be based on the ASME OM Code, 2004 Edition. In accordance with the recommendations of NUREG-1482, Revision 1, Section 5.5, the licensee desires to apply Code Case OMN-6 in lieu of the ISTB-351 O(b)(2) Code requirements.

Paragraph ISTB-351 0(b)(2) requires that the reference value of digital instruments not exceed 70 percent of the calibrated range of the instrument. The ASME OM Code Case OMN-6 allows licensees to use digital instruments such that the reference value does not exceed 90 percent of the calibrated range of the instrument.

Application of ASME OM Code cases is addressed in 10 CFR 50.55a(b)(6) through reference to RG 1.192, which lists acceptable and conditionally-acceptable Code Cases for implementation in 1ST programs. RG 1.192 (June 2003), Table 1, approves the use of Code Case OMN-6, and references the version of the Code Case that was issued with the 1999 Addenda of the Code.

This version of Code Case OMN-6 issued with the 1999 Code Addenda, states that it is applicable to ASME OM Code - 1990 Edition through ASME OMb - 1997 Addenda. It also states that the Code Case shall expire on September 28,2001, unless previously annulled or reaffirmed.

Paragraph ISTA-3130 (Application of Code Cases) of the ASME OM Code, 2004 Edition delineates two requirements that cannot be met by the licensee and therefore require relief or an alternative. Specifically, paragraphs 1STA-3130(b) and (c) require that Code Cases be applicable to the edition and addenda specified in the test plan and that Code Cases be in effect at the time the test plan is filed. As stated above, the approved Code Case version is not applicable to the ASME OM Code, 2004 Edition and is expired.

-4 In accordance with 10 CFR 50.55a(a)(3), proposed alternatives to the stated code requirements may be authorized provided the applicant demonstrates that the proposed alternative provides an acceptable level of quality and safety. The provisions and requirements of Code Case OMN-6 provide an acceptable level of quality and safety because the requirements from the ASME OM Code -1990, Edition, paragraph ISTB 4.6.1 (b)(2), through OMb 1997, paragraph ISTB 4.7.1(b)(2) have no material difference as compared to OM Code 2004 Edition paragraph ISTB-351 O(b)(2).

Furthermore, Code Case OMN-6 was amended and issued with the ASME OM Code 2006 Addenda. This version of the Code Case expanded the applicability to include the ASME OM Code - 1990 and later editions and addenda through the OMa 2005 Addenda, and it was given a new expiration date of March 30, 2007. While this version of the code case is not approved by inclusion in RG 1.192 and is expired, it does continue to support the technical basis of the proposed change, namely that allowing reference values for digital instruments that do not exceed 90 percent of the calibration range of the instrument maintains sufficient accuracy and margin for properly monitoring pump performance.

Based on the above discussion, Code Case OMN-6 provides an acceptable level of quality and safety for pump testing and is an acceptable alternative for use in the licensee's 1ST program.

The staff finds that the criteria in Code Case OMN-6 are technically adequate, are applicable to the licensee's program, and provide reasonable assurance of the operational readiness of the affected pumps.

3.1.5 Conclusion Based on a review of the information provided by the licensee, the staff concludes that the licensee's proposed alternative to use Code Case OMI'J-6 in lieu of the requirements of Code paragraph ISTB-351 O(b)(2), is authorized pursuant to 10 CFR 50.55a(a)(3)(i) for the third 10-year interval, on the basis that the alternative provides an acceptable level of quality and safety.

3.2 Relief Request 11-PRR-1 Revision 1 3.2.1 Code Requirements The licensee requested an alternative to ISTB-5221(b) and ISTB-5223(b) which require the resistance of the system be varied until the flow rate or differential pressure equals its reference value. Then the other parameter, differential pressure or flow rate, is determined and compared to its reference value.

An alternative was requested via 10 CFR 50.55a (a)(3)(i) for the following emergency service water (ESW) pumps:

ESW OAP548 ESW OBP548 ESW OCP548 ESW ODP548 The licensee's code of record is the ASME OM Code, 2004 Edition. The 1O-year service interval is scheduled to begin on January 8, 2010, and conclude on January 7, 2020.

-5 3.2.2 Licensee's Basis for Requesting an Alternative The licensee states that the ESW system contains many variable heat loads that vary depending on plant conditions and seasonal variations. Attempting to establish specific flow or differential pressure conditions at any fixed reference point is extremely difficult without adversely affecting the system flow balance and would require multiple manual operator actions. Additionally, these manual operator actions require multiple entries into the Radiological Controlled Areas, e.g.

access to the Emergency Core Cooling System room coolers and other safety related equipment, resulting in additional dose to plant operators. Additionally, the ESW pumps must be tested in a manner that ensures the service water loop remains properly flow balanced during and after the testing and each supplied load remains fully operable per LGS, Units 1 and 2, Technical Specifications (TSs) to maintain the required level of plant safety during plant operation.

3.2.3 Licensee's Proposed Alternative Testing The licensee requests approval to use the guidelines set fourth in Code Case OMN-16, "Use of a Pump Curve for Testing," in lieu of the ISTB-5221 and ISTB-5223 requirements for ESW pumps OAP548, OBP548, OCP548, and ODP548. Code Case OMN-16 allows the use of reference curves to determine pump performance, however, it is not listed as an acceptable code case in RG 1.192, "Operation and Maintenance Code Case Acceptability, ASME OM Code." Current pump performance is established by measuring the pump flow, discharge pressure, and suction pressure, and then calculating dynamic head. The test data is then compared to the reference curves and determined whether it is within the acceptable range of Table ISTB-5221-1.

The reference pump curves for LGS, Units 1 and 2 were created during flow balancing activities before the operational start of Unit 2. The curves include data points encompassing shutoff head to approximately 1.5 times the maximum flow rate required for safe shutdown or accident conditions. According to the licensee, the curves exceed the requirements of Code Case OMN-16.

The licensee will obtain vibration readings according to ISTB-3540. The licensee claims the pumps show little variation in vibration over their normal operating range and their acceptance criteria for the testing complies with the requirements of Table ISTB-5221-1.

3.2.4 Evaluation As discussed in OMN-16, in cases when testing a centrifugal or vertical line shaft centrifugal pump where adjustment to a specific reference value is impractical, the establishment of additional pump curves for reference values of flow rate and differential pressure is acceptable.

OMN-16 has been reviewed by the NRC staff. The staff determined that OMN-16 is the same as OMN-9 (and has incorporated the staffs caveats to OMN-9 listed in Regulatory Guide (RG) 1.192), which expired on November 25, 2006. OMN-16 is basically a replacement for OMN-9, although it has not yet been incorporated into RG 1.192. The staff finds that OMN-16 provides an acceptable level of quality and safety for testing the subject pumps, and is an acceptable replacement for OMN-9 which was previously approved for use in RG 1.192.

In the case of the LGS ESW pumps OAP548, OBP548, OCP548, and ODP548, it would be impractical to throttle the system in order to achieve a fixed reference value, as resistance is varied in response to the heat loads of the plant, which are seasonally dependent and can vary

-6 significantly. Varying the flow rate presents the potential for loss of adequate flow and cooling to the heat exchangers. This is an impractical condition as defined in NUREG-1482, Revision 1.

3.2.5 Conclusion Based on the above evaluation that determined that compliance with the Code requirements is impractical for the pump testing, and considering the burden on the licensee if the Code requirements are imposed, relief is granted from the Code requirements and the alternative is imposed, pursuant to 10 CFR 50.55a(f)(6)(i). The staff concludes that the proposed testing provides reasonable assurance that the components are operationally ready. No additional requirements beyond the Code Case are imposed by the staff. The relief granted is authorized by law and will not endanger the common defense and security and is otherwise in the public interest, giving due consideration to the burden upon the licensee if the Code requirements were imposed on the facility. This alternative is authorized for the LGS Units 1 and 2 third 1a-year 1ST interval. Use of this ASME Code Case is authorized until such time as the ASME Code Case is published in a future version of RG 1.192 and incorporated by reference in 10 CFR 50.55a(b). At that time, if the licensee intends to continue implementing this Code Case, it must follow all provisions of ASME OM Code Case OMN-16 with conditions as specified in RG 1.192 and limitations as specified in 10 CFR 10.55a(b)(4), (b)(5), and (b)(6), if any.

3.3 Relief Request 90-PRR-1 Revision 1 3.3.1 Code Requirements The licensee requested a proposed alternative to the following code requirements from ASME OM Code 2004 Edition paragraph ISTB 3510, "Data Collection":

ISTB-351 O(a) - requires that instrument accuracy be within the limits of Table 3510-1 which specifies an accuracy requirement of +/- 2 percent of full-scale for analog flow instruments.

ISTB-351 O(b)(1) - requires that the full-scale range of each analog instrument be not greater than three times the reference value.

Components affected:

Pump(s): Main Control Room Chilled Water OAP162 OBP162 Type: Centrifugal Driver: Motor Group: B Code Class: 3 The licensee's code of record is the ASME OM Code, 2004 Edition. The 1a-year service interval is scheduled to begin on January 8,2010, and conclude on January 7,2020.

3.3.2 Licensee's Basis for Requesting an Alternative The licensee states that pursuant to 10 CFR 50.55a, "Codes and standards," paragraph (a)(3)(i),

an alternative is requested to the requirement of ASME OM Code ISTB-3510(a). For instruments to be in compliance with the Code, both requirements stated above must be met, individually, for

-7 each instrument. The combination of the two requirements (Le., accuracy equal to +/- 2 percent if full-scale and full-scale being up to 3 times the reference value) yields a permissible inaccuracy of

+/- 6 percent of the reference value.

The permanently installed flow instruments shown in the table below are calibrated to an accuracy greater than the +/- 2 percent full-scale limit.

3.3.3 Licensee's Proposed Alternative Testing The licensee states that as an alternative, LGS, Units 1 and 2 proposes to use the currently installed analog instruments for measurement of 110w for the identified equipment. Although these instruments do not meet Code requirements, they provide better indication accuracy at the reference value than that which is permitted by the Code.

Section 5.5.1 of NUREG-1482, Revision 1, states that the staff may grant relief when the combination of the range and accuracy yields a reading at least equivalent to the reading achieved from instruments that meet the Code requirements (Le., up to +/- 6 percent).

The following table shows the instrument accuracy and full-scale range of the flow instruments used to conduct 1ST of the pumps listed above. The resulting instrument tolerance and indicated accuracy are calculated and also listed in the table. The indicated accuracy at the reference value is shown to be within the permissible +/- 6 percent.

Instrument Reference Instrument Range Instrument Instrument Indicated Number Value (Full Scale) Accuracy Tolerance Accuracy FI-90-034A 600 0-800 3.08 24.64 4.11 percent percent FI-90-034B 600 0-800 3.04 24.32 4.05 percent percent The licensee states that based on Section 5.5.1 of NUREG-1482, Revision 1, and the information provided herein, the existing permanently installed pump instrumentation is considered acceptable in meeting the intent of the ASME OM Code-2004 Paragraphs ISTB-351 O(a) and ISTB 3510(b)(1).

3.3.4 Evaluation The licensee requests an alternative to ASME OM Code paragraphs ISTB-351 O(a) and ISTB 3510(b)(1) for the Main Control Room Chilled Water pumps discharge flow measuring instruments. ASME OM Code paragraph ISTB-3510(a) states that flow measuring instrumentation accuracy must be within +/- 2 percent full-scale. ASME OM Code paragraph ISTB 3510(b)(1) states that the full-scale range of each analog instrument shall be not greater than three times the reference value. The licensee proposes to use existing installed analog instrumentation FI-90-034A and FI-90-034B which currently do not meet all of the code requirements.

Table ISTB-3510-1 requires the instrument accuracy to be within +/- 2 percent of full-scale, while paragraph ISTB-351 0(b)(1) requires the full-scale range of each instrument be no greater than

-8 three times the reference value. The combination of these two requirements results in an effective accuracy requirement of +/- 6 percent of the reference value.

NUREG-1482, Revision 1, Section 5.5.1 states that relief may be granted when the combination of the range and accuracy yields a reading that is at least equivalent to that achieved using instruments that meet the Code requirements (i.e., up to +/- 6 percent for Group A and B tests, and

+/- 1.5 percent for pressure and differential pressure instruments for Preservice and Comprehensive tests).

In this request for an alternative, the full-scale range of the installed flow measuring instruments is within the required three times the reference value. However, the instrument accuracy is greater than the required +/- 2 percent of full scale. Considered together, the indicated accuracy achieved from the installed flow measuring instrumentation FI-90-034A and FI-90-034B is 4.11 percent and 4.05 percent respectively. This meets the intent of the Code and yields an acceptable level of quality and safety.

3.3.5 Conclusion Pursuant to 10 CFR 50.55a(a)(3)(i), the NRC staff authorizes the licensee's proposed alternative on the basis that the alternative provides an acceptable level of quality and safety. This alternative is authorized for the LGS, Units 1 and 2 third 10-year 1ST Interval.

3.4 Relief Request 47-VRR-2 Revision 0 3.4.1 Code Requirements ISTC-3510 - states that active Category A, Category B, and Category C check valves shall be exercised nominally every 3 months, except as provided by ISTC-3520, ISTC-3540, ISTC-3550, ISTC-3570, ISTC-5221, and ISTC-5222.

ISTC-3560 - states that valves with fail-safe actuators shall be tested by observing the operation of the actuator upon loss of valve actuating power in accordance with the exercising frequency of ISTC-3510.

ISTC-5131(a) - states that active valves shall have their stroke times measured when exercised in accordance with ISTC-3500.

ISTC-5221 (a)(2) states that check valves that have a safety function in only the open direction shall be exercised by initiating flow and observing that the obturator has traveled to either the full open position or to the position required to perform its intended function(s) (see ISTA-1100), and verify closure.

Components Affected:

XV-47-1-26 (all 185 Hydraulic Control Units (HCU)) -Inlet Scram Valve XV-47-1-27 (all 185 HCUs) - Outlet Scram Valve XV-47-2-26 (all 185 HCUs) - Inlet Scram Valve XV-47-2-27 (all 185 HCUs) - Outlet Scram Valve 47-1-14 (all 185 HCUs) - Scram Discharge Riser Check Valve 47-2-14 (all 185 HCUs) - Scram Discharge Riser Check Valve

-9 The alternative testing is proposed for the third 1O-year interval for LGS Units 1 and 2, which is scheduled to begin on January 8,2010, and conclude on January 7,2020. The applicable code edition for this duration is the ASME OM Code, 2004 Edition.

3.4.2 Licensee's Basis for Requesting an Alternative The licensee has provided the following information regarding this request.

Each of the valves listed above represents 1 of 185 Control Rod Drive (CRD) HCU valves.

In order to exercise the valves in accordance with ISTC-351 0, and test the fail safe actuators as required by ISTC-3560, the air operated inlet and outlet valves would need to be exercise tested at power nominally every 3 months. The air operated inlet and outlet scram valves, XV-47-1(2)-26 and XV-47-1(2)-27, open on a signal from the Reactor Protection System to permit rapid insertion of the control rods (scram). These valves can only be tested by scramming the CRD.

ISTC-5131(a) applies to air operated inlet and outlet scram valves XV-47-1(2)-26 and XV-47-1(2)

27. Stroke timing is impractical since they are not equipped with indication of the open and closed positions. Insertion of the control rod is verified by control room panel lights and not valve position. Accordingly, code compliant stroke time testing cannot be performed to meet the ISTC 5131(a) requirement.

ISTC-3510 and ISTC-5221 (a)(2) apply to the scram discharge riser check valves 47-1(2)-14. The scram discharge riser check valve is flow actuated as a result of XV-47-1(2)-27 opening. These valves can only be tested by scramming the CRD in order to demonstrate that the safety function is exercised.

For all components, exercise testing at power will result in rapid insertion of control rods causing potential reactivity transients and wear of the CRD mechanisms.

3.4.3 Licensee's Proposed Alternative Testing According to the licensee, as a proposed alternative, the valve testing will be performed in accordance with LGS, Units 1 and 2 TSs, Surveillance Requirement (SR) 4.1.3.2 which states:

The maximum scram insertion time of the control rods shall be demonstrated through measurement and, during single control rod scram time tests, the CRD pumps shall be isolated from the accumulators:

a. For all control rods prior to thermal power exceeding 40% of rated thermal power with reactor coolant pressure greater than or equal to 950 psig, following core alterations or after reactor shutdown that is greater than 120 days.

b. For specifically affected individual control rods following maintenance on or modification to the control rod or CRD system which could affect the scram insertion time of those specific control rods in accordance with either "1" or "2" as follows:

1.a Specifically affected individual control rods shall be scram time tested at zero reactor coolant pressure and the scram insertion time from the fully

- 10 withdrawn position to notch position 05 shall not exceed 2.0 seconds, and 1.b Specifically affected individual control rods shall be scram time tested at greater than or equal to 950 psig reactor coolant pressure prior to exceeding 40% of rated thermal power.

2. Specifically affected individual control rods shall be scram time tested at greater than or equal to 950 psig reactor coolant pressure.

c. For at least 10% of the control rods, with reactor coolant pressure greater than or equal to 950 psig, on a rotating basis, and in accordance with the Surveillance Frequency Control Program.

Scram time testing of the control rods demonstrates that the valves identified in the relief request will perform their safety function. These valves are required to open to provide drive water and create an exhaust path for insertion of the control rods. Failure of a valve to open would result in the control rod not scramming in accordance with the TS requirements. It is noted that TS SR 4.1.3.2.a is performed at least once per refueling cycle, TS SR 4.1.3.2.b is performed following maintenance or modification to the control rod or CRD system, and TS SR 4.1.3.2.c is performed once per 120 days of power operation in conformance with the Surveillance Frequency Control Program. GL 89-04, Position 7 states that the rod scram test frequency identified in the TS may be used as the valve testing frequency to minimize rapid reactivity transients and wear of the CRD mechanisms.

Pursuant to 10 CFR 50.55a, "Codes and Standards," paragraph (a)(3)(i), an alternative is requested to use the guidance provided in GL 89-04, Position 7. GL 89-04, Position 7 discusses alternative testing of individual scram valves for control rods in Boiling Water Reactors (BWRs).

Position 7 states that use of these alternatives to satisfy valve testing requirements should be documented in the 1ST Program. NUREG-1482, Revision 1, Section 1.3, states that specific relief is required to implement the positions of GL 89-04.

3.4.4 Evaluation The licensee has requested a proposed alternative testing program for certain valves found in the CRD HCU. There are 185 HCUs in the CRD system. Inlet and outlet scram valves XV-47-1(2) 26, XV-47-1(2)-27, and scram discharge riser check valve 47-1(2)-14 represent only one each of 185 HCUs. The proposed alternative testing shall apply to all HCUs and their associated valves.

Scram inlet valve XV-47-1(2)-26 and scram exhaust valve XV-47-1(2)-27 are air operated valves with an air to close - fail open design. Valve 47-1(2)-14 is a check valve located in the scram discharge riser line which is flow actuated as a result of XV-47-1(2)-27 opening. These valves are required to be tested in accordance with subsection ISTC of the ASME OM Code 2004 Edition.

The following are paragraphs from section ISTC that are applicable to this request for an alternative:

• Paragraph ISTC-3510 requires that active Category B and Category C check valves shall be exercised nominally every 3 months.

• Paragraph ISTC-3521 (c) says that if exercising is not practicable during operation at power, it may be limited to full-stroke exercising during cold shutdown.

- 11

• Paragraph ISTC-3560 requires that valves with fail safe actuators shall be tested by observing the operation of the actuator upon loss of valve actuating power in accordance with the exercising frequency of ISTC-351 O.

• Paragraph ISTC-5131(a) requires pneumatically operated active valves shall have their stroke times measured when exercised.

• Paragraph ISTC-5221 (a)(2) requires that check valves that have a safety function in only the open direction shall be exercised by initiating flow and observing that the obturator has traveled either the full open position or to the position required to perform its intended function(s), and verify closure.

In lieu of ASME OM Code test requirements, the licensee requests testing the valves in accordance with LGS Units 1 and 2 TS SR 4.1.3.2 "Control Rod Maximum Scram Insertion Times" in conformance with the Surveillance Frequency Control Program.

GL 89-04, Position 7, and NUREG-1482, Revision 1, discuss the testing of the inlet and outlet scram valves and the scram discharge riser check valve found in CRD systems in BWR design plants. A review of these documents finds that they are applicable to LGS, Units 1 and 2. The NRC staff agrees that exercising these valves quarterly during power operations could result in rapid insertion of one or more control rods. The scram time testing frequency of once per refueling cycle, per LGS TS SR 4.1.3.2.a, is equivalent to that required by ASME OM Code when testing is impractical during normal plant operation and cold shutdown. This frequency also minimizes rapid reactivity transients and wear of the CRD mechanisms. Verifying that the associated control rod meets the scram insertion time limits defined in the plant's TSs is an acceptable alternative method of detecting degradation of these valves. Monitoring and trending the stroke times of the inlet and outlet scram valves is unnecessary because they are indirectly stroke timed and no meaningful correlation between the scram time and valve stroke time can be obtained.

The NRC staff finds that the LGS, Units 1 and 2, proposed alternative testing is consistent with NUREG-1482, Revision 1, and GL 89-04, Position 7, and that these documents are applicable to the LGS, Units 1 and 2 plant design. The NRC staff concludes that the proposed alternative from the exercise frequency, actuator fail safe testing, and stroke time requirements detailed in paragraphs ISTC-3510, ISTC-3560, ISTC-5131(a) and ISTC-5221 (a)(2) for the inlet and outlet scram valves and scram discharge riser check valve located on each CRD HCU provides an acceptable level of quality and safety and is therefore, acceptable.

3.4.5 Conclusion Pursuant to 10 CFR 50.55a(a)(3)(i), the NRC staff authorizes the licensee's proposed alternative, as specified in request 47-VRR-2 Revision 0 on the basis that the alternative provides an acceptable level of quality and safety. This alternative is authorized for the LGS Units 1 and 2 third 10-year 1ST Interval.

4.0 CONCLUSION

The NRC staff has reviewed the licensee's submittal and concludes that, pursuant to 10 CFR 50.55a(a)(3)(i), relief requests GPRR-5, Revision 0, 90-PRR-1, Revision 1, and

- 12 47-VRR-2, Revision 0 are authorized on the basis that the proposed alternative provides an acceptable level of quality and safety. Relief request 11-PRR-1, Revision 1, pursuant to 10 CFR 50.55a(f)(6)(i), is granted based on the impracticality of performing testing in accordance with the ASME OM Code, ISTB-5221 and ISTB-5223 test requirements and in consideration of the burden on the licensee if the code requirements were imposed on the facility. All other ASME OM Code requirements for which relief was not specifically requested and approved remain applicable.

Principal Contributors: R. Lake M. Farnan M. Orenak P. Bamford Date: November 17, 2009

C. Pardee -2 The third 1O-year 1ST interval begins on January 8, 2010, and is scheduled to conclude on January 7, 2020, for LGS, Units 1 and 2.

Documentation of the NRC staff review and evaluation is contained in the enclosed safety evaluation. If you have any questions, please contact the Limerick Project Manager, Mr. Peter J.

Bamford, at 301-415-2833.

Sincerely,

/raj Harold K. Chernoff, Chief Plant Licensing Branch 1-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-352 and 50-353

Enclosure:

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