ML12244A272

Relief from the Requirements of ASME OM Code for the Fifth Ten-Year IST Program Interval (TAC Nos. ME8067, ME8088 Through ME8096)

ML12244A272
Person / Time
Site:	Monticello  (DPR-022)
Issue date:	09/26/2012
From:	Istvan Frankl Plant Licensing Branch III
To:	Schimmel M Northern States Power Co
Beltz T
References
TAC ME8067, TAC ME8088, TAC ME8089, TAC ME8090, TAC ME8091, TAC ME8092, TAC ME8093, TAC ME8094, TAC ME8095, TAC ME8096
Download: ML12244A272 (31)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 September 26, 2012 Mr. Mark A. Schimmel Site Vice-President Northern States Power Company - Minnesota Monticello Nuclear Generating Plant 2807 West CDunty Road 75 Monticello, MN 55362-9637

SUBJECT:

MONTICELLO NUCLEAR GENERATING PLANT - RELIEF FROM THE REQUIREMENTS OF THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS CODE FOR OPERATION AND MAINTENANCE OF NUCLEAR POWER PLANTS FOR THE FIFTH 10-YEAR INSERVICE TESTING PROGRAM INTERVAL (TAC NOS. ME8067, ME8088, ME8089, ME8090, ME8091, ME8092, ME8093, ME8094, ME8095, AND ME8096)

Dear Schimmel:

By letter dated September 28, 2011 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML112720137), the Northern States Power Company, a Minnesota corporation (NSPM), doing business as Xcel Energy (hereinafter referred to as the licensee),

submitted nine requests (PR-01, PR-02, PR-03, PR-04, PR-05, PR-06, VR-01, VR-02, and VR-03) to the U.S. Nuclear Regulatory Commission (NRC) for the use of alternatives to certain inservice testing (1ST) requirements of the American Society of Mechanical Engineers (ASME)

Code for Operation and Maintenance of Nuclear Power Plants (OM Code). for the fifth 10-year 1ST program interval at the Monticello Nuclear Generating Plant (Monticello). By letter dated February 28,2012, (ADAMS Accession No. ML12059A402), the licensee submitted an additional request (VR-04) to the NRC. In an e-mail dated August 9,2012 (ADAMS Accession No. ML12223A086), the licensee submitted a response to the NRC staff's requests for additional information and included Revision 1 to PR-06.

Pursuant to Title 10 of the Code of Federal Regulations (10 CFR) Part 50, Section 50.55a(a)(3)(i), the licensee requested to use the proposed alternatives on the basis that the alternatives provide an acceptable level of quality and safety in requests PR-02, PR-04, PR-06, VR-03, and VR-04.

Pursuant to 10 CFR Part 50.55a(a)(3)(ii), the licensee requested to use the proposed alternatives on the basis that complying with the specified requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety in requests PR-01. PR-03, PR-05, and VR-01.

Pursuant to 10 CFR Part 50.55a(f)(6)(i), the licensee requested relief and to use alternative requirements for inservice testing items on the basis that compliance with ASME OM Code requirements is impractical in request VR-02.

M. Schimmel

- 2 The NRC staff has reviewed the subject requests and concludes, as set forth in the enclosed safety evaluation. that the licensee has adequately addressed a" the regulatory requirements set forth in 10 CFR 50.55a(a)(3)(i), 10 CFR 50.55a(a)(3)(ii), and 10 CFR 50.55a(f)(6)(i), for the respective requests. Therefore, the NRC staff authorizes alternative requests PR-01, PR-02, PR-03, PR-04, PR-05, PR-06 Revision 1, VR-01, VR-03, and VR-04. and relief is granted for request VR-02. at Montice"o for the fifth 1 O-year 1ST program interval which begins on September 1,2012, and ends on August 31,2022. All other ASME OM Code requirements for which relief was not specifically requested and approved remain applicable.

If you have any questions, please contact Terry Beltz at (301) 415-3049 or via e-mail at Terry.Beltz@nrc.gov.

Sincerely, OIL Istvan Frankl, Acting Chief Plant Licensing Branch 111-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-263

Enclosure:

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• • • • 1' SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION ALTERNATIVE REQUESTS PR-Ol, PR-02, PR-03, PR-04, PR-05, PR-06 Revision 1 VR-01, VR-02, VR-03, AND VR-04 RELATED TO THE INSERVICE TESTING PROGRAM, FIFTH 10-YEAR INTERVAL NORTHERN STATES POWER COMPANY MONTICELLO NUCLEAR GENERATING PLANT DOCKET NO. 50-263

1.0 INTRODUCTION

By letter dated September 28, 2011 (Agencywide Documents Access and Management System Accession No. ML112720137), the Northern States Power Company (NSPM), doing business as Xcel Energy, the licensee, submitted requests PR-01, PR-02, PR-03, PR-04, PR-05, PR-06, VR-01, VR-02, and VR-03, to the U.S. Nuclear Regulatory Commission (NRC). By letter dated February 28,2012 (Accession No. ML12059A402), NSPM submitted alternative request VR-04 to the NRC. By email datedAugust9.2012(AccessionNo.ML12223A086). the licensee submitted additional information pertaining to the alternative requests, including Revision 1 to PR-06. The licensee proposed alternatives to or requested relief from certain inservice testing (1ST) requirements of the American Society of Mechanical Engineers (ASME) Code for Operation and Maintenance of Nuclear Power Plants (OM Code), for the 1ST Program at the Monticello Nuclear Generating Plant (Monticello) for the fifth 10-year 1ST program interval.

Specifically, pursuant to Title 10 of the Code of Federal Regulations (10 CFR) Part 50, section 50.55a(a)(3)(i), the licensee requested to use the proposed alternatives in PR-02, PR-04. PR-06 Revision 1, VR-03, and VR-04 on the basis that the alternatives provide an acceptable level of quality and safety. Pursuant to 10 CFR Part 50, section 50.55a(a)(3)(ii), the licensee requested to use the proposed alternatives in PR-01, PR-03, PR-05, and VR-01 on the basis that complying with the specified requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety. For proposed alternative VR-02, pursuant to 10 CFR Part 50, section 50.55a(f)(6)(i), the licensee requested relief from certain code requirements on the basis that compliance with ASME OM Code requirements are impractical and the proposed alternative provides reasonable assurance that the components are operationally ready.

2.0 REGULATORY EVALUATION

10 CFR 50.55a(f), "Inservice Testing Requirements," requires, in part, that 1ST of certain ASME Code Class 1, 2, and 3 components must meet the requirements of the ASME OM Code and Enclosure

- 2 applicable addenda, except where alternatives have been authorized pursuant to paragraphs (a)(3)(i), (a)(3)(ii), or (f)(6){i).

In proposing alternatives, a licensee must demonstrate that the proposed alternatives provide an acceptable level of quality and safety (10 CFR SO.SSa(a){3)(i)), compliance would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety (10 CFR SO.SSa(a)(3)(ii)), or conformance is impractical for the facility (10 CFR SO.SSa(f){6)(i)).

Section SO.SSa allows the NRC to authorize alternatives and to grant relief from ASME OM Code requirements upon making necessary findings.

The Monticello fifth 10-year 1ST program interval begins on September 1, 2012, and is scheduled to end on August 31, 2022. The applicable ASME OM Code and addenda for the Monticello fifth 10-year 1ST program interval is the 2004 Edition through the 2006 Addenda.

The NRC's findings with respect to authorizing the alternatives, PR-01, PR-02, PR-03, PR-04, PR-OS, PR-06 Revision 1, VR-01, VR-03, and VR-04, and granting relief noted in VR-02, are given below:

3.0 TECHNICAL EVALUATION

3.1.1 Licensee's Alternative Request PR-01 ISTB-3SS0, "Flow Rate," states, in part, "When measuring flow rate, a rate or quantity meter shall be installed in the pump test circuit. If a meter does not indicate the flow rate directly, the record shall include the method used to reduce the data."

ISTB-S300(a)(1), "Positive Displacement Pumps: Duration of Tests," states, "For the Group A test and the comprehensive test, after pump conditions are as stable as the system permits, each pump shall be run at least 2 minutes. At the end of this time at least one measurement or determination of each of the quantities required by Table ISTB-3000-1 shall be made and determined."

Table ISTB-3000-1 contains the various inservice test parameters for pump tests. The licensee requested alternative testing for Standby Liquid Control (SLC) pumps P-203A and P-203B. The pumps are classified as Group B positive displacement pumps.

Reason for Request

The licensee states that the SLC pumps are designed to pump a constant flow rate regardless of system resistance. The SLC system was not deSigned with a flow meter in the flow loop.

The system was designed to be tested using a test tank where the change in level can be measured over time. This test methodology also limits the pump run time based on the size of the test tank. In addition, the installation of a larger test tank to facilitate pump testing would be a burden because of the design, fabrication and installation changes that would be required.

The ASME OM Code requirements to use flow rate instrumentation and that a two-minute test duration for the comprehensive pump test (CPT) are considered a burden, which would result in a hardship without a corresponding level of quality or safety.

- 3 Proposed Alternative The licensee proposed to determine pump flow rate by measuring changes in tank level over time. After taking an initial pump volume measurement, a SLC pump will be started with suction from the demineralized water system and will discharge to the test tank. After at least two minutes of operation, the pump will be stopped and the change in level over the measured time will be converted to flow rate by the following formula:

Q (gallons per minute [gpm]) = ljJh.L (inches [in])/h.t (seconds [sec])

Where ljJ is a constant which represents tank dimensions and unit conversions, and h.L is the measured change in the liquid level in the tank.

The test tank level will be set at approximately the same level at the beginning of each test to ensure repeatability. Use of the demineralized water system ensures a large source at a constant pressure for a stable testing environment. The vibration testing will be performed while recirculating an adequately filled test tank. Therefore, the duration of the test code requirements for vibration testing will be met.

A plant 1ST instrument accuracy calculation determined that the accuracy of SLC flow measurement was less than 2% (approximately 1.4%). This calculation used the dimensions of the tank, the method of measuring the change in depth of water in the tank, and the method of measuring time to evaluate accuracy by a square root of the sum of the squares method.

3.1.2

NRC Staff Evaluation

The ASME OM Code requires a rate or quantity meter be installed in the pump test circuit when measuring the flow rate to determine the extent of any pump degradation. A two minute pump run time is required to achieve stable conditions prior to measuring and recording pump performance parameters. The licensee does not currently have a rate or quantity meter installed in the pump circuit to record the flow rate for SLC pumps P-203A and P-203B as required by the ASME OM Code. As a result, the licensee alternatively proposed the use of tank level to calculate the flow rate for these pumps.

The NRC staff reviewed the licensee's proposed alternative to use tank level to measure flow rate in lieu of installing a flow meter. As part of the review, the NRC staff evaluated whether the proposal would calculate the flow rate as described in Subsection ISTB-3500. To demonstrate the acceptability of the proposed alternative, the licensee identified the calculational method to be used and indicated that the level of accuracy of the SLC pump flow measurement was approximately 1.4%. The calculation would be conducted using the dimensions of the tank, the method of measuring the change in depth water in the tank, and includes the time to evaluate accuracy by a square root of the sum of the squares method.

The NRC staff has determined that the licensee's alternative provides an acceptable calculational method and that the test conditions needed to achieve the required accuracy are consistent with the ASME OM Code requirements. The licensee will set the tank level at approximately the same level at the start of each test to ensure repeatability. Additionally, the

- 4 suction source (from the demineralized water system) is from a large source at a constant pressure providing for a stable test environment. The NRC staff finds that this would allow pump performance parameters to stabilize quickly without a two minute run time before recording data. The licensee will maintain the record for the test method used as required by ISTB-3550. This method will provide reasonable assurance of pump operational readiness when the test tank level is measured in accordance with the accuracy requirements of Table ISTB-3510-1 of the ASME OM Code, and the record includes the method used.

As stated above, the licensee's proposed alternative includes the calculational method and test conditions needed to achieve the required accuracy, which was determined to be better than the ASME OM Code requirement of 2% (1.4%). Testing the SLC pumps per the requirements of ISTB-5300(a}(1} represents a hardship without a compensating increase in the level of quality or safety.

3.2.1 Licensee's Alternative Request PR-02 ISTB-3510, "Data Collection: General," (b)(1), "Range." states, "The full-scale range of each analog instrument shall not be greater than three times the reference value."

The licensee requested an alternative to the full-scale range requirements for the flow transmitters for Residual Heat Removal (RHR) pumps P-202A, P-202B. P-202C. and P-202D, and Residual Heat Removal Service Water (RHRSW) pumps P-109A, P-109B. P-109C. and P-109D. These pumps are all classified as Group A pumps.

Reason for Request

The licensee states that flow transmitters FT-10-111A, FT-10-11'1 B, FT-10-97A. and FT-1 0-97B are each designed to indicate flow while two parallel pumps are operating (RHR or RHRSW).

During 1ST. only one pump operates at a time. The resulting reference value for flow for one pump is less than one-third of the instrument's range. The installed flow transmitters have typically had an as-found accuracy of about 0.25% of full scale. In addition. the system is verified to have an as-found accuracy that is within 2% of the Code-allowed reference value for analog instruments.

The current relevant data for the instruments is shown in Table 3.2-1.

- 5 Table 3.2-1 Instrument Pumps Instrument Span (Range)

Equivalent Reference Value Range to Reference Value Ratio P-109A FT-10-97A 10-50 mA 18.39 mA (40/8.39) =4.77 P-109C P-109B FT-10-97B 10-50 mA 18.57 mA (40/8.57) = 4.67 P-109D Transmitters FT-1 0-111A, FT-10-111 B, and FT-1 0-97 A output signals are read on a millivolt (mV) display with the pump test procedures specifying a reference target range that corresponds one-to-one mV to mA. The transmitter FT-10-97B output signal is converted from a 10-50 mA range to a 4-20 mA range via FY-41 05, RHR SERVICE WATER FLOW ISOL, and read on a mV display with the pump test procedures specifying a reference target range that corresponds one-to-one mV to mA of the converted signal range. The equivalent reference value is the center of this reference flow signal range and is in mA. Dividing the transmitter range by the equivalent reference mA value shows the instrument range to exceed the reference value by more than a factor of 3.

The FY -4105 output equivalent reference value is 7.43 mA. Thus, the range to reference value ratio is also (16/3.43) =4.67 when taken at the FY-4105 output, which is equivalent to the (40/8.57) =4.67 at FT-10-97B output.

The installed flow transmitters typically have an as-found accuracy of 0.25% of full scale. In addition, the system is verified to have an as-found accuracy in accordance with ISTB-3510(a).

ISTB-3510(a) requires that instrument accuracy be within the limits of Table 3510-1, which specifies an accuracy requirement of +/-2% of full-scale for analog flow instruments. ISTB-3510(b)(1) requires that the full range of each analog instrument be not greater than three times the reference value. The combination of these two requirements (i.e., accuracy equal to +/-2% of full scale and full scale being up to 3 times the reference value) yields a permissible inaccuracy of +/-6% of the reference value.

Table 3.2-2 shows the ranges, reference values, range to reference value ratio, and calculated effective accuracies for instruments FT-10-111A, FT-1 0-111 B, FT-1 0-97A, and FT-10-97B. The calculated effective instrument accuracies are much less than the ASME OM Code-required effective accuracy of +/-6%. Therefore, these instruments yield readings at least equivalent to the reading achieved from instruments that meet the ASME OM Code requirements (i.e., up to

- 6

+/-6%) and thus, provide an acceptable level of quality and safety. The effective accuracy of each instrument is also provided in Table 3.2-2.

Table 3.2-2 Instrument FT-10-97A FT-10-97B Pump P-109A P-109C P-109B P-1090 Instrument Range 40 mA 40mA Reference Value (18.39-10)=

8.39 mA (18.57-10)=

8.57 mA Range to Reference Value (40/8.39)=

4.77 (40/8.57)=

4.67 Effective Accuracy with

+/-O.2S% Instrument Accuracy (4.77 x 0.25%) =

+/-1.2%

(4.67 x 0.25%) =

+/-1.17%

Proposed Alternative The licensee proposed to use existing plant instruments to measure pump 1ST parameters. A loop check will be performed on the flow instrumentation for these systems that verifies the as found accuracy to within the 2% accuracy requirement in Table ISTB-3510-1 of the ASME OM Code. The licensee will also ensure that it satisfies the requirement to be within the range of three times the reference value of any RHR or RHRSW pump, and will conduct the required inservice examination as part of a routine calibration task.

3.2.2

NRC Staff Evaluation

Earlier versions of the ASME OM Code specified an instrument range of four times the reference value or less. The instrument range for analog instruments was subsequently changed from four times the reference value to three times the reference value, potentially posing a challenge to the earlier licensed plants. While the NRC staff does not generally consider instrument installation to be an undue burden, the licensee is not relieved of its responsibility to make modifications to comply with changes to 1ST as a result of changes in the ASME OM Code. In order for a licensee to use existing instrumentation, they must ensure that the instruments meet the intent of the ASME OM Code and yield an acceptable level of quality and safety.

The installed flow transmitters typically have an as-found accuracy of 0.25% of full scale. In addition, the system is verified to have an as-found accuracy that is within 2% of the ASME OM Code-allowed reference value for analog flow instruments. ISTB-351 0(b)(1) requires that the full range of each analog instrument be not greater than three times the reference value. Thus,

- 7 when combining the required level of accuracy with the allowed range for the reference value, the effective instrument accuracy is +/- 6% of the reference value.

Table 3.2-2 shows the ranges, references values, range to reference value ratio, and calculated effective accuracies for instruments FT 111 A, FT 111 B, FT 97 A, and FT -1 0-97B. The calculated effective instrument accuracies are much less than the required effective accuracy of

+/- 6%. Consequently, these instruments yield readings at least equivalent to the reading achieved from the instruments that meet ASME OM Code requirements, and continue to provide an acceptable level of quality and safety.

3.3.1 Licensee's Alternative Request PR-03 Table I STB-5121-1, "Centrifugal Pum p Test Acceptance Criteria," indicates a vibration Alert Range of >0.325 to 0.7 inches/second (in/sec) for horizontal centrifugal pumps with a speed

?: 600 revolutions per minute (rpm).

ISTB-6200, "Corrective Action," (a), "Alert Range," states, in part, "If the measured test parameter values fall within the alert range of Table ISTB-5121-1,.... the frequency of testing specified in ISTB-3400 shall be doubled until the cause of the deviation is determined and the condition is corrected."

ISTB-3400, "Frequency of Inservice Tests," states, "An inservice test shall be run on each pump as specified in Table I STB-3400-1. "

Table ISTB-3400-1, "Inservice Test Frequency," provides the frequency for Group A, Group B, and CPTs.

An alternative vibration alert range was requested for the CPT of High Pressure Coolant Injection (HPCI) pump P-209. HPCI pump P-209 is classified as a Group B pump.

Reason for Request

The licensee states that HPCI pump P-209 consists of a centrifugal main pump, a separate centrifugal booster pump, a speed reducing gear for the booster pump, and a Terry turbine steam driver. During testing, the Terry turbine and main pump operate near 3590 rpm. The booster pump operates at a lower rpm due to the reducing gear. All these components are mounted horizontally along the same drive train. Therefore, there are four independently balanced and aligned rotating assemblies that are coupled together. As a result, the normal (baseline) vibration readings in the horizontal direction on the main pump is approximately 0.423 in/sec. Application of a 0.325 in/sec lower alert range limit would require the HPCI pump to enter an accelerated test frequency each time the pump was tested, because the vibration measurement of one or more of these points measured would exceed this alert range lower limit.

The licensee has many years of 1ST data showing that baseline vibrations at 0.423 in/sec represent acceptable pump operation. The licensee has had these vibration levels analyzed by

- 8 an engineering consultant that specializes in vibration analysis. The consultant's analysis shows that this pump can operate at vibration levels up to 0.700 in/sec.

Component industry history was reviewed for this type of pump. No failures attributed to extended hours of pump operation at vibration levels exceeding 0.325 in/sec were found.

Implementing the alert lower limit of 0.325 in/sec would require the licensee to constantly have the HPCI pump on an accelerated test frequency. This would result in an annual instead of a biennial CPT for this pump. The intent of increased test frequency is to closely monitor a pump that is deteriorating from its baseline values. In this case, the pump is operating at its normal vibration range and no change would be seen. The additional annual test would require a significant amount of time and resources.

Modifying the system in an attempt to reduce the vibration levels, such as installing new shafts and impellers, is extremely expensive and may not reduce the vibration levels. Therefore, requiring an alert range lower limit of 0.325 in/sec for HPCI pump P-209 is an extreme hardship without a compensating increase in public safety. An appropriate alert range lower limit for these vibration data points is 0.500 in/sec. This is based on previous test history, a review of industry data, and the vibration analysis performed.

Proposed Alternative The licensee proposed, as an alternative to the ASME OM Code requirements of Table ISTB 5121-1, a vibration alert range lower limit of 0.500 in/sec for pump horizontal vibration data points. The licensee is not proposing to change the vibration requirement in Table ISTB-5121-1 for the alert range upper limit of 0.700 in/sec, or the required action range high value of > 0.700 in/sec.

3.3.2 NRC Staff Evaluation HPCI pump P-209 consists of a centrifugal main pump, a separate centrifugal booster pump, a speed reducing gear for the booster pump, and a steam turbine driver. Because of this configuration, both pumps must be tested simultaneously. The licensee stated that because of this arrangement, high vibration levels are recorded in the horizontal direction on the main pump. The licensee characterized these high vibration levels as the normal vibration level for the HPCI pump bearings. Therefore, the licensee stated that complying with the ASME OM Code requirements for HPCI pump P-209 would be a hardship without a compensating increase in the level of quality and safety.

ISTB-6200(a) states that if pump vibration velocity levels exceed the alert range lower limit of 0.325 in/sec in Table ISTB-5121-1, the testing frequency shall be doubled until the problem with the pump is determined and corrective action is taken. The ASME OM Code also uses vibration reference values to determine vibration limits, or institutes absolute alert and required action range limits for centrifugal pumps regardless of the magnitude of the vibration reference value.

The licensee proposed raising the alert range lower limit for horizontal vibration for HPCI pump P-209 to 0.500 in/sec. The alert range lower limit for the axial and vertical vibration components would remain at 0.325 in/sec. The licensee stated that they have historical test data showing that the baseline vibrations at 0.423 in/sec represent acceptable pump operation.

- 9 The licensee reviewed component industry history for this type of pump and found no recorded pump failures attributed to extended hours of pump operation at vibration levels exceeding 0.325 in/sec. The pump vibration test data has also been analyzed by an engineering consultant who specializes in vibration analysis, and the consultant's analysis shows that HPCI pump P-209 can operate at vibration levels up to 0.700 in/sec.

The licensee's evaluation of the HPCI pump P-209 vibration issue, coupled with the historical pump vibration data, shows that HPCI pump P-209 normally runs at high levels of vibration and has not experienced any failure to date. Requiring the licensee to meet the ASME OM Code requirements by increasing the frequency of the HPCI pump testing would result in a hardship without a compensating increase in the level of quality and safety. This is because of the additionally testing that would need to be performed on a pump that adequately operates at elevated vibration levels.

The proposed testing with the higher vibration alert range lower limit will provide reasonable assurance of operational readiness because the licensee will continue to test HPCI pump P-209 quarterly, and will maintain the ASME OM Code alert ranges for the axial and vertical components of vibration. Also, the licensee will adhere to the required action range as stated in the ASME OM Code.

3.4.1 Licensee's Alternative Request PR-04 ISTB-3510, "Data Collection: General," (a), "Accuracy," states, in part, "Instrument accuracy shall be within the limits of Table ISTB-3510-1."

ISTB-3510(b)(1), "Range," states, "The full scale range of each analog instrument shall be not greater than three times the reference value."

Table ISTB-351 0-1, "Required Instrument Accuracy," contains the required accuracy for instruments measuring the various pump parameters.

An alternative to the requirement of I STB-351 O(b)(1) was requested for instruments PI-23-116, PI-13-66, and transmitter PT 100 which are used to determine differential pressure for HPCI pump P-209 and Reactor Core Isolation Cooling (RCIC) pump P-207. The pumps are classified as Group B pumps.

Reason for Request

The differential pressure for the HPCI and RCIC pumps is determined by subtracting the indicated suction pressure from the indicated discharge pressure. The HPCI pump suction pressure is read in the control room from instrument PI-23-116, which is sent a 10 to 50 rnA signal from local transmitter PT-23-100. The RCIC pump suction pressure is read locally from instrument PI-13-66. The current instrument ranges exceed three times the current reference values. The relevant data for the instruments is shown in Table 3.4-1.

- 10 Table 3.4-1 Instrument Pump Instrument Range Reference Value Range to Reference Value Ratio PI-23-116 (Note 1)

P-209 30" Hg 100 pounds per square inch (psi) 33.7 psi 114.7/33.7 =3.4 PT-23-100 (Note 2)

P-209 10 - 50 mA 11.8 mA*

40/11.8 = 3.4 PI-13-66 (Note 1)

P-207 30" Hg - 100 psi 33.7 psi 114.7/33.7 = 3.4

• 21.8 mA equates to 11.8 mA on the 40 mA span Note 1: The vacuum range for the pressure indicators was converted to pounds/square inch (psi) for determining the ratio. 30" mercury (Hg) Vacuum = 14.7 psi; thus the range

=100 psi + 14.7 psi. The same principle was applied to the reference value. With a reference value of 19 psi indicated on the instrument, the reference value used for the ratio determination is 19 + 14.7 =33.7 psi.

Note 2: The pressure transmitter has a 10 to 50 mA range, or a span of 40 mA. The ratio for this instrument must be determined by reducing the reference value to its value on the 40 mA span.

ISTB-3510(a} requires that instrument accuracy be within the limits of Table 3510-1, which specifies an accuracy requirement of +/- 2% of full-scale for analog flow instruments for Group B tests. ISTB-3510(b)(1) requires that the full-scale range of each analog instrument be not greater than three times the reference value. The combination of the two requirements (i.e.,

accuracy equal to +/- 2% of full-scale and full scale being up to 3 times the reference value) yields a permissible inaccuracy of +/- 6% of the reference value.

Group B Tests: In accordance with ISTB-3510(b)(1), the licensee proposed to apply three times the reference value for determination of the ASME OM Code equivalent range for the instruments. The +/- 2% Code-required instrument accuracy (see ISTB-3510(a>> for the Group B test is determined from this ASME OM Code equivalent range as described in Table 3.4-2.

Table 3.4-2 Instrument Reference Value Code Equivalent Range 2% of Code Equivalent Range PI-23-116 33.7 psi 3 x 33.7 = 101 psi

+/- 2 psi PT-23-100*

21.8 mA 3 x 11.8 =35.4 mA

+/- 0.7 mA PI-13-66 33.7 psi 3 x 33.7 =101 psi

+/- 2 psi

• 21.8 mA equates to 11.8 mA on the 40 mA span

- 11 The current instrument calibration tolerances are +/- 2 psi for the pressure indicators and

+/- 0.7 mA for the pressure transmitter. The as-found data in the calibration history for these instruments shows that they have been consistently well within these current ASME OM Code equivalent tolerances.

CPTs: The full scale range of pressure transmitter PT 100 is approximately 3.4 times the reference value, which is greater than the ISTB-351 0(b}(1) requirement of three times the reference value.

The licensee proposed that the instrument accuracy requirements of ISTB-3510(a) be demonstrated by determining the loop accuracy using both temporary and in-plant installed instrumentation (PT-23-100). The as-found data in the calibration history for these instruments shows that they have consistently been well within the ASME OM Code equivalent tolerances.

Proposed Alternative The licensee's proposed alternatives to the ASME OM Code requirements of ISTB-351 0(b)(1) are described below:

Group B Tests: The licensee will calibrate instruments PI-23-116, PT-23-100, and PI-13-66 to

+/- 2% of the ASME OM Code equivalent range for Group B tests. The Code equivalent range will be calculated by multiplying the current test parameter reference value by three.

CPTs: The licensee will demonstrate the instrument accuracy requirements of ISTB-351 O(a) by determining the loop accuracy using both temporary and in-plant installed instrumentation (PT 23-100).

3.4.2

NRC Staff Evaluation

The NRC staff reviewed the licensee's alternative to the Group B tests required under the ASME OM Code to apply three times the reference value to the equivalent range identified in Table 3.4-2 above. Based upon the proposed alternative ASME OM Code equivalent range, the licensee would apply the accuracy requirement of +/- 2% to the established equivalent range (Le.,

3 x 33.7 = 101 psi for the instruments and 3 x 11.8 =35.4 mA for the transmitter). The two pressure indicators are calibrated to an accuracy of +/- 2 psi. The pressure transmitter is calibrated to +/- 0.7 mAo The +/- 2% ASME OM Code instrument accuracy requirement equates to

+/- 2 psi for the pressure indicator and +/- 0.7 mA for the pressure transmitter. The reading given by the licensee's installed instrumentation results in the actual variance having a value essentially equal to the maximum variance in the reading allowed by the ASME OM Code.

Therefore, the installed instrumentation has sufficient accuracy because the variance in test results is essentially equal to the variance allowed if the ASME OM Code requirements are met.

Therefore, these instruments yield readings at least equivalent to the readings achieved from instruments that meet ASME OM Code requirements (Le., up to +/- 6%) and, thus, provide an acceptable level of quality and safety.

The NRC staff reviewed the licensee's alternative to the CPT required under the ASME OM Code to use the loop accuracy to assess potential degradation of the pump to confirm its

- 12 operational readiness. The current instrument calibration tolerances are +/- 2 psi for the two pressure indicators and +/- 0.7 mA for the one transmitter. As a result, the licensee has committed to conservatively calibrate these instruments to within +/- 2% of the proposed ASME OM Code equivalent range of three times the reference value. The NRC staff finds that the proposed calibration of instruments, commitment to establishing an ASME OM Code equivalent range, and implementation of loop accuracy for the CPT to be consistent with the recommendations in NUREG-1482 and, thus will provide an acceptable level of quality and safety.

3.5.1 Licensee's Alternative Request PR-05 ISTB-3510, "Data Collection: General," (e), "Frequency Response Range," states, "The frequency response range of the vibration-measuring transducers and their readout system shall be from one-third minimum pump shaft rotational speed to at least 1000 Hz."

An alternative to the frequency response range of vibration-measuring transducers was requested for SLC pumps P-203A and P-203B. The pumps are classified as Group B pumps.

Reason for Request

The nominal shaft rotational speed of SLC pumps P-203A and P-203B is 280 rpm, which is equivalent to approximately 4.7 Hertz (Hz). Based on this frequency and ISTB-3510(e), the required frequency response range of instruments used for measuring pump vibration is to be 1.56 to 1000 Hz. Procurement and calibration of instruments to cover this range to the lower extreme (1.56 Hz) is impractical due to the limited number of vendors supplying such equipment (and replacement parts), the level of equipment sophistication, and the difficulty of the instruments to meet the required accuracy at low frequencies.

These pumps are of a simplified reCiprocating (piston) positive displacement design with rolling element bearings, Model Number TD-60, manufactured by Union Pump Corporation. Union Pump Corporation has performed an evaluation of the pump design and has determined that there are no probable sub-synchronous failure modes associated with these pumps under normal operating conditions. Furthermore, there are no known failure mechanisms that would be revealed by vibration at frequencies below those related to shaft speed (4.7 Hz.).

Based upon the absence of a credible failure mode, no useful information is obtained by testing below the 4 Hz frequency, nor will any indication of pump degradation be masked by instrumentation unable to collect data below this frequency. The requirement to measure vibration with instruments with response to 1/3 shaft speed comes from the need to detect oil whip or oil whirl associated with journal bearings. In the case of these pumps, there are no journal bearings to create these phenomena, thus satisfying the ASME OM Code requirements of ISTB-3510(e) would serve no significant purpose. The significant modes of vibration, with respect to equipment monitoring, are as follows:

One Times Crankshaft Speed - An increase in vibration at this frequency may be an indication of rubbing between a single crankshaft cheek and rod end, cavitations at a single valve, or coupling misalignment.

- 13

• Two Times Crankshaft Speed - An increase in vibration at this frequency may be an indication of looseness at a single rod bearing or crosshead pin, a loose valve seat in the fluid cylinder, a loose plunger/crosshead stub connection, or coupling misalignment.

Other Multiples of Shaft Speed - An increase in vibration at other frequencies may be an indication of cavitation at several valves, looseness at multiple locations, or bearing degradation.

Based on the foregoing discussion, it is clear that monitoring pump vibration within the frequency range of 4 to 1000 Hz will provide adequate information for evaluating pump condition and ensuring continued reliability with respect to the pumps' function.

Proposed Alternative Vibration levels of the SLC pumps P-203A and P-203B will be measured in accordance with the applicable portions of the ASME OM Code Section ISTB, with the exception of the lower frequency response limit for the instrumentation listed in ISTB-3510(e). The frequency response range for vibration measurement for the SLC pumps shall be 4 to 1000 Hz instead of the ASME OM Code required range of 1.56 to 1000 Hz.

3.5.2

NRC Staff Evaluation

The NRC staff reviewed the licensee's basis for claiming that compliance with the inservice testing pursuant to the code would present a hardship without a compensating increase in the level of safety. The licensee indicated that if it wanted to replace the instrumentation to measure vibration levels within the range necessary to comply with ISTB-3510(e) that only a few vendors could potentially supply the instrumentation and replacement parts to cover the lower end of the range (1.56 Hz). Consequently, the licensee believes that trying to acquire the necessary instrumentation and replacement parts when needed from the limited pool of vendors' places a hardship on them. Furthermore, Union Pump Corporation, the pump manufacturer, performed an evaluation and determined that there is no probable sub synchronous failure modes associated with the pumps under normal operating conditions. In addition, there are no known failure mechanisms that would be revealed by any potential pump vibration at frequencies below a shaft speed of 4.7 Hz.

The licensee identified the frequencies where high vibration would provide an indication of pump degradation as "one times pump running speed," "two times pump running speed," and "multiples of pump running speed." The types of problems that could be encountered at these frequencies were also identified. The frequency spectrum of the signals generated is characteristic of each pump and constitutes a unique pattern. Analysis of the pattern allows identification of vibration sources, and monitoring of change over time permits evaluation of the mechanical condition of the pump.

Just as important, the level of sophistication and the difficulty of the instruments to meet the required accuracy at low frequencies according to the licensee is impractical to cover the lower extreme of the determined range (1.56 Hz). Consequently, the NRC staff found that complying with the requirements of ISTB-3510(e) for the SLC pumps would represent a hardship without a

- 14 compensating increase in the level of quality or safety, and the current instrumentation would provide an adequate assessment of the operational readiness for the pumps.

3.6.1 Licensee's Alternative Request PR-06, Revision 1 ISTB-5122(a), "Centrifugal Pumps (Except Vertical Line Shaft Centrifugal Pumps): Group B Test Procedure," states, "The pump shall be operated at nominal motor speed for constant speed drives or at a speed adjusted to the reference point (+/-1 %) for variable speed drives."

ISTB-5122(c) states, "System resistance may be varied as necessary to achieve the reference point."

ISTB-5123(a), "Centrifugal Pumps (Except Vertical Line Shaft Centrifugal Pumps):

Comprehensive Test Procedure," states, "The pump shall be operated at nominal motor speed for constant speed drives or at a speed adjusted to the reference point (+/-1 %) for variable speed drives."

ISTB-5123(b) states, in part, "For centrifugal and vertical line shaft pumps, the resistance of the system shall be varied until the flow rate equals the reference point. The differential pressure shall then be determined and compared to its reference value."

Alternative testing was requested for HPCI pump P-209. The pump is classified as a Group B centrifugal pump.

Reason for Request

The licensee states that in order to perform accurate trending and data analysis, the use of an accurate reference value is very important. The complexities of the flow control system used for HPCI make it difficult to exactly duplicate the reference points. Additionally, iterative manipulation of the control system equipment to refine the hydraulic and speed parameters contributes additional wear to system components. As alternative testing is allowed under the provisions of 10 CFR 50.55a, the licensee proposed an alternative test method for the comprehensive and Group B HPCI pump P-209 test, as required by the ASME OM Code, Subsection ISTB.

As stated in NUREG-1482, Revision 1, Section 5.2, some system designs do not allow for testing at a single reference point or a set of reference points. In such cases, it may be necessary to plot pump curves to use as the basis for variable reference points. Code Case OMN-16, "Use of Pump Curves for Testing," is included in the issuance of ASME Code OMb-2006, "Addenda to ASME OM Code-2004." This Code Case has not been accepted by NRC staff for inclusion in NRC Regulatory Guide (RG) 1.192, "Operation and Maintenance Code Case Acceptability, ASME OM Code;" however, Code Case OMN-9, "Use of Pump Curves for Testing," has been conditionally accepted by NRC staff for inclusion in RG 1.192.

The conditions imposed on OMN-9 as stated in RG 1.192 have been incorporated into OMN-16.

In addition, Code applicability for the use of OMN-16 includes the ASME OM Code 2004 Edition through the 2006 Addenda, which is the fifth interval Code of Record for the Monticello 1ST Program.

- 15 Proposed Alternative As an alternative to the testing requirements of ISTB-5122 and ISTB-5123, the licensee will assess pump performance and operational readiness through the use of reference pump curves per the guidelines provided in Code Case OMN-16. Flow rate and pump differential pressure will be measured during 1ST in the as-found condition of the system and compared to an established reference curve. The following elements will be used in the development of the reference pump curves.

During comprehensive and quarterly HPCI pump testing, pump differential pressure and flow rate will be evaluated using a reference point derived from a pump curve. The licensee submitted representative pump curves for Group B and comprehensive testing. The reference point test pump curve will be restricted to an operating range that is representative of accident conditions, or conservative conditions that are the most sensitive indicator of pump degradation.

Appropriate upper and lower acceptance criteria limits for differential pressure will be established for the Required Action and Alert range limits, as applicable, for Group Band comprehensive testing.

These limits will be scalar multiples of the reference pump curve. For determination of whether the 1ST acceptance criteria are met, the licensee submitted proposed tables to be used to analyze the data. These acceptance criteria satisfy the requirements specified in Code Case OMN-16, paragraph 16-6200(a), "Alert Range," and paragraph 16-6200(c), "Required Action Range."

The licensee will follow the stipulations established by Pump Relief Request PR-03, "HPCI Pump Vibration," for the vibration alert levels and the Code-established limits for the Action Required levels over the reference value curve range for comprehensive testing.

The vibration data from the test was reviewed and no adverse correlation was evident between flow rate and vibration at the nominal reference point speed. Therefore, the licensee will not establish new vibration reference values and related allowable limits over the reference value curve at this time.

If future requirements necessitate the need for re-generation of a new pump reference curve, the licensee will obtain vibration readings across the expected operating test range of the pump.

The alternative testing described above provides an acceptable level of quality and safety because the method will provide increased accuracy in trending and data analysis. Since the methodology utilized is consistent with the NRC staff guidance provided in NUREG-1482, Revision 1, Section 5.2 and Code Case OMN-16, it will provide reasonable assurance of pump operational readiness.

3.6.2

NRC Staff Evaluation

As discussed in ASME OM Code Case, OMN-16, when testing a centrifugal pump where adjusting the pump to a specific reference value is impractical, the establishment of additional pump curves for reference flow rates and differential pressures and vibration is acceptable.

- 16 OMN-16 has been reviewed by the NRC staff. Although this code case has not yet been incorporated into RG 1.192, OMN-16 is a replacement for Code Case OMN-9. OMN-9 is currently an authorized alternative for setting reference values, as required by ISTB-5122 and ISTB-5123. Additionally, OMN-16, from the 2006 Addenda of the ASME OM Code, has incorporated the NRC staff's conditions for OMN-9, as listed in RG 1.192. The NRC staff finds that OIVlN-16, from the 2006 Addenda of the ASME OM Code, provides an acceptable level of quality and safety for testing the subject pump. and is an acceptable replacement for OMN-9, which was previously approved for use in RG 1.192.

Based on a review of the information provided by the licensee, the NRC staff finds that for HPCI pump P-209, it is not practical to return to the same flow configuration for each inservice pump test. It would be impractical to manipulate the flow control system used for HPCI in order to achieve a fixed reference value. Also, iterative manipulation of the control system equipment to refine the hydraulic and speed parameters contributes additional wear to the system components. The pump will be tested in a range of flows, and the results will be compared to the acceptance criteria based on a portion of the pump curve and on the hydraulic and vibration acceptance criteria specified in ISTB-5123. The stipulations established by Pump Relief Request PR-03, "HPCI Pump Vibration," will be followed for the vibration alert levels and the Code-established limits for the Action Required levels over the reference value curve range for comprehensive testing. The licensee's proposed alternative testing complies with the requirements of ASME Code Case OMN-16, from the 2006 Addenda of the ASME OM Code.

3.7.1 Licensee's Alternative Request VR-01 ISTC-3510, "Exercise Test Frequency," requires active Category C check valves to be exercised nominally every 3 months. If exercising every 3 months is not possible then exercising shall be performed during cold shutdowns or refueling outages as permitted by ISTC 3522, "Category C Check Valves."

ISTC-3522, "Category C Check Valves," states, in part, that, "Each check valve exercise test shall include open and close tests."

ISTC-5221 (a)(2), "Check Valves: Valve Obturator Movement," requires 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 safety function(s), and verified closed.

The licensee proposed an alternative to certain ASME OM Code 1ST requirements pertaining to testing of control rod drive (CRD) scram discharge header check valves, CRD-114.

Reason for Request

The subject check valves, CRD-114, are a simple ball-check design. There are no internal parts in the check valves that are susceptible to rapid degradation and sudden failure. In addition, the control rods are infrequently scrammed and these valves are thus subjected to few stress/wear cycles. It is not practical to perform the close exercise test on-line.

- 17 Furthermore, the valves are welded into the line and it is not practicable to perform a disassembly and inspection of each valve in accordance with ISTC-5221 (c). There is no provision for routine access for direct visual examination of the ball and body seats or for indirect examination of internals using remote viewing aides such as a boroscope. In order to observe that the obturator has traveled would require a complete disassembly and inspection of the check valve, and an additional valve would require disassembly.

NUREG-1482, Revision 1, Section 4.4.6, "Testing Individual Scram Valves for Control Rods in Boiling-Water Reactors," provides an approved alternative. NUREG-1482 requires that those ASME Code Class valves that must change position to provide the scram function should be included in the 1ST program and be tested in accordance with the requirements of ISTC except where relief has been granted in a previously issued safety evaluation. Bi-directional exercise testing of check valves is required by the 1996 Addenda to the ASME Code (and later editions and addenda).

NUREG-1482, Revision 1, Section 4.4.6 further states, in part:

The control rod drive system valves that perform an active safety function in scramming the reactor are the scram discharge volume vent and drain valves, scram inlet and outlet valves, scram discharge header check valves, charging water header check valves, and cooling water header check valves. With the exception of the scram discharge volume vent and drain valves, exercising the other valves quarterly during power operations could result in the rapid insertion of one or more control rods... for those control rod drive system valves for which testing could result in rapid insertion of one or more control rods, the rod scram test frequency identified in the facility TSs [Technical Specifications] may be used as the valve testing frequency to minimize rapid reactivity transients and wear of the control rod drive mechanisms. This alternative test frequency should be clearly stated and documented in the 1ST program document.

The proper operation of these check valves is demonstrated during scram time testing. During scram time testing, scram insertion time is measured for each CRD. Monticello's TS 3.1.4 provides a specific time for individual CRD scram insertion. If a particular CRD's scram insertion time is less than the specified time, the above check valves are functioning properly.

Monticello's TS surveillance requirement (SR) 3.1.4.1 requires verification that each control rod scram time is within the limits of TS Table 3.1.4-1 with reactor steam dome pressure 2800 pounds per square inch gauge (psig) prior to exceeding 40% rated thermal power after each reactor shutdown ~120 days.

Monticello's TS SR 3.1.4.2 requires verification, for a representative sample, that each tested control rod scram time is within the limits of TS Table 3.1.4-1 with reactor steam dome pressure 2800 psig each 200 days cumUlative operation in Mode 1.

The scram discharge header check valves (CRD-114) have a safety function to open. The check valve must open to provide a flow path from the overpiston area of the CRD to the scram discharge header during a scram. This check valve's closed function is to prevent backflow

- 18 from the scram discharge volume (SDV) to the overpiston area of the drive when a scram is reset. Flow from the CRD to the SDV occurs throughout the entire scram stroke of the control rod and continues until volume pressure equals reactor vessel pressure. There would normally be no demand for check valve closure until after the rod is fully inserted and latched.

Additionally, any condition that would require check valve closure would prevent further control rod insertion regardless of the position of this check valve. Therefore, failure of the scram outlet check valves to close would not prevent the system from performing its safety function.

Proposed Alternative The licensee considers that the proper operation of each of these check valves is demonstrated during scram time testing where each drive scram insertion time is measured. As previously discussed, Monticello's TS 3.1.4 provides a specific time for CRD scram insertion. If a particular scram insertion time is less than the specified time scram, then the related valves are functioning properly. The successful scram time of a CRD also represents the successful full stroke exercising of these check valves. The licensee proposed to perform testing of the CRD scram discharge header check valves consistent with the alternative testing provided in Section 4.4.6 of NUREG-1482, Revision 1. Therefore, the closed function of the scram discharge header check valves would not be tested as required by ISTC-3522. Using the provisions of this request as an alternative to the test requirements specified in ISTC-3510, ISTC-3522, and ISTC-5221 (a)(2) is an acceptable alternative method of detecting degradation of the check valves and provides an acceptable level of quality and safety for determining the check valves are functioning properly.

3.7.2

NRC Staff Evaluation

There is one CRD-114 scram discharge header check valve on each of the 121 hydraulic control units (HCUs). For all control rods to scram, all of the CRD-114 check valves must open along with other CRD system valves. ISTC-3510 of the ASME OM Code requires that check valves be exercised every 3 months to verify that they fulfill their safety function. ISTC-3221 allows that if exercising is not practicable during plant operation and cold shutdown, it shall be performed during the refueling outage. The subject check valves, CRD-114, are a simple ball check design. There are no internal parts in the check valves that are susceptible to rapid degradation and sudden failure. In addition, the control rods are infrequently scrammed and these valves are thus subjected to few stress/wear cycles. Furthermore, the valves are welded into the line and it is not practicable to perform a disassembly and inspection of each valve in accordance with ISTC-5221 (c). The licensee proposed to demonstrate the proper functioning of each CRD-114 check valve in conjunction with the scram time testing as required by Monticello's TS SR 3.1.4.1 and TS SR 3.1.4.2, which are performed at least once during each operating cycle.

The CRD scram discharge header check valves do not have a safety-related function in the closed direction. These check valves must open throughout the entire scram stroke of the control rod and continues until volume pressure equals reactor vessel pressure. This check valve's closed function is to prevent backflow from the SDV to the over piston area of the drive when a scram is reset. Exercising these CRD check valves quarterly during power operations is not practicable because it could result in the rapid insertion of one or more control rods. The

- 19 scram time test frequency of at least once during each operating cycle identified in the TS for use as the valve testing frequency is equivalent to that required by the ASME OM Code when testing is not practical during normal plant operation and cold shutdown. This frequency also minimizes rapid reactivity transients and wear of the CRD mechanisms.

If a particular scram insertion time is less than the specified scram time, then the related valves are shown functioning properly. The successful scram time of a CRD also represents the successful full stroke exercising of these check valves. Therefore, verifying that the associated control rod meets the scram insertion time limits defined in the TSs is a viable alternative method of detecting degradation of the check valves. Trending the scram stroke times is unnecessary because they are indirectly stroke timed and no meaningful correlation between scram time and valve degradation can be obtained.

Testing of the scram discharge header check valves per the requirements of ISTB-3510, ISTC-3522, and ISTC-5221 (a)(2) represents a hardship without a compensating increase in the level of quality or safety. The NRC staff finds that the proposed alternative from the exercise and frequency requirements of ISTC-3510, ISTC-3522, and ISTC-5221 (a)(2) for the CRD scram discharge header check valves, located on each CRD HCU, provides reasonable assurance of the operational readiness of these valves.

3.8.1 Licensee's Relief Request VR-02 ISTC-3510, "Exercise Test Frequency," requires active Category B valves to be exercised nominally every 3 months. If exercising every 3 months is not possible, then exercising shall be performed during cold shutdowns or refueling outages as permitted by ISTC-3520, "Exercising Requirements. "

ISTC-5131, "Pneumatically Operated Valves: Valve Stroke Time Testing," requires active valves to have their stroke times measured when exercised in accordance with ISTC-3500 and limiting values to be specified by the Owner.

ISTC-5132, "Pneumatically Operated Valves: Stroke Time Acceptance Criteria," requires test results to be compared to the reference values developed in accordance with ISTC-3320.

ISTC-5133, "Pneumatically Operated Valves: Stroke Time Corrective Action," requires valves that exceed the limiting values of full stroke time to be immediately declared inoperable, or valves with measured stroke times that do not meet the acceptance criteria of ISTC*5132 shall be immediately retested or declared inoperable.

The licensee proposed an alternative to certain ASME OM Code 1ST requirements pertaining to testing of air-operated valves (AOVs), CV-1728 and CV-1729, associated with RHRSW system.

Reason for Request

ISTC-5131 requires that a limiting value of full stroke time be established for a power operated valve (POV) and that the stroke time be measured whenever such a valve is full stroke tested. Performing full stroke time testing of these valves is impractical based on the

- 20 control scheme design of the valves, adverse plant impact, and the functional requirements of the valves.

ISTC-2000 defines the full stroke time as the time interval from initiation of the actuating signal to the indication of the end of the operating stroke. The control scheme design of these valves does not receive an actuation signal (neither by manual hand switch nor by automatic logic) to stroke to the position required to fulfill their safety function.

RHRSW valves CV-1728 and CV-1729 are air-operated control valves on the outlet line of the RHRSW side of the "A" and "8" RHR heat exchangers, respectively. These control valves maintain a differential pressure between the RHRSW process stream and the RHR process stream during RHRSW system operation. The valves are controlled by a positioner, which is controlled by a differential pressure-indicating controller (DPIC). The DPIC senses pressure on the RHRSW discharge line and the RHR inlet line to the RHR heat exchanger.

The desired differential pressure control point, and thus the desired valve position for system flow, is manually set by the operator. The valve positioner modulates the valve position as necessary to maintain this control point. Stroke time testing or full stroke exercising of these valves on quarterly basis is not consistent with the design of the valve's control scheme and is not in the interest of plant safety.

These valves are interlocked to receive a closed signal when the RHRSW pumps are de energized. This interlock is provided to ensure that system water inventory is not lost during system shutdown. Stroke time testing of valves CV-1728 and CV-1729 when the RHRSW pumps are de-energized would result in the loss of liquid fill for a significant portion of the RHRSW system as well as require the bypassing of an interlock designed to minimize the potential for water hammer. Such testing increases the possibility of an adverse water hammer during startup of the RHRSW system as well as requires filling and venting of the system following the stroke time testing. In addition to the adverse impact on the plant operation, such testing can result in system or component damage.

Stroke time testing or full stroke exercising of the valves during RHRSW pump operation negates the loss of system fill concern; however, this testing would also have an adverse impact on plant safety and equipment integrity. Stroke time testing or full stroke exercising during pump operation would require the valve be initially in the closed position during pump operation. Establishing the initial test conditions of a closed valve during pump operation would result in an undesirable deadheading of the pump. Subsequent opening of the valve to perform stroke time testing or full stroke exercising will result in pump run out if a single RHRSW pump is in operation, an undesirable condition which adversely impacts pump integrity and performance. The pump runout concern can be addressed by stroke timing the valve open during operation of both RHRSW pumps; however, this exacerbates the pump deadheading concerns and would result in undesirable transients on the system and could cause system or component damage.

Proper stroke time testing or full stroke exercising would require the plant to modify the control logic of the valves. The activity associated with performing this modification is not offset by an increase in public safety. The proposed alternative testing is an effective

- 21 means to ensure the valves perform their safety function and is consistent with other valve category test requirements, such as check valve exercising. By extension, if stroke time testing is not performed, the requirement of ISTC-5132 for establishing stroke time acceptance criteria is impractical. Similarly, if there are no stroke time limits applicable, then the requirement of ISTC-5133 for corrective action when stroke time limits are exceeded is not applicable when performing ASME OM Code required testing.

Proposed Relief The licensee proposed using ISTC-3530 for demonstrating the necessary valve disk movement by observing indirect evidence (such as changes in system pressure, flow rate, level, or temperature), which reflect stem or disk position. The most representative test of the capability of valves CV-1728 and CV-1729 to perform their intended function is performed during 1ST of the RHRSW pumps. Quarterly testing of the RHRSW pumps verifies the capability of the valves to operate properly to pass the maximum required accident flow, as well as the valve position necessary to achieve required flow conditions. In addition, per ISTC-5131 (d), any abnormality or erratic action shall be recorded and an evaluation shall be made regarding need for corrective action. Testing of the valves in this manner demonstrates valve performance capability and provides a means to monitor for valve degradation. It should be noted that these valves are within the scope of Monticello's AOV Program. As such, the valves receive diagnostic testing per the AOV Program.

3.8.2

NRC Staff Evaluation

According to Monticello's Updated Final Safety Analysis Report (UFSAR), Section 10.4.2.3, the differential pressure control valve is interlocked with the RHRSW pumps such that the valve actuator instrument air solenoid is energized only when a pump is in service. Valves CV-1728 and CV-1729 are closed and the solenoid is de-energized during normal plant operation when the RHR system is not in service. These valves are also interlocked to receive a closed signal when the RHRSW pumps are de-energized. This interlock is provided to ensure that system water inventory is not lost during system shutdown. Stroke time testing of these valves when the RHRSW pumps are de-energized would result in the loss of liquid fill for a significant portion of the RHRSW system, as well as require the bypassing of an interlock designed to minimize the potential for water hammer. Such testing increases the possibility of adverse water hammer during startup of the RHRSW system, and would require filling and venting of the system following the stroke time testing. In addition to the adverse impact on the plant operation, such testing could result in system or component damage. Proper stroke testing or full stroke exercising would, therefore, require the plant to make major modifications of the control logic of the valves.

Stroke time testing or full stroke exercising during pump operation would require either of the valves to be initially in the closed position during pump operation. Establishing the initial test conditions of a closed valve during pump operation would result in an undesirable deadheading of the pump. Subsequent opening of the valve to perform stroke time testing or full stroke exercising could result in pump runout if a single RHRSW pump is in operation, an undesirable condition which adversely impacts pump integrity and performance. The pump runout concern can be avoided by stroke timing the valve open during operation of both RHRSW pumps;

- 22 however, this exacerbates the pump deadheading concerns and would result in undesirable transients on the system that could cause system or component damage.

The primary safety function of valves, CV-1728 and CV-1729, is to remove decay heat from the RHR system when it is in shutdown cooling or containment spray/cooling mode. In the case of an emergency core cooling system (ECCS) initiation signal, the RHRSW pumps will automatically trip, thereby de-energizing the differential pressure control valve solenoid. Once the ECCS condition has cleared and reactor water level is being maintained, the RHRSW system must be manually started and flow established by the operator using the DPIC located in the control room. There is no fixed-time requirement for this system to be placed into operation following a design basis loss of coolant accident condition since at least eight hours are available before the containment design pressure is reached. Therefore, stroke time testing of these valves does not indicate their ability to perform the safety function described in the UFSAR.

The licensee requested relief from the requirements of ISTC-5131, ISTC-5132, and ISTC-5133 of the ASME Code because of impractical test conditions during power operation. Further, stroke time testing of these control valves on a quarterly basis is not consistent with the design of the valve control scheme. ISTC-5131 requires that all POVs be full stroke time tested with a frequency specified in ISTC-3500. ISTC-5132 requires that test results be compared to the reference values established in accordance with ISTC-3300, ISTC-3310, or ISTC-3320.

ISTC-5133 provides corrective action statements for those valves which exceed the stroke time acceptance criteria.

The licensee proposed using quarterly RHRSW pump testing for demonstrating the necessary valve disk movement by observing indirect evidence (such as changes in system pressure, or flow rate) which reflects stem or disk position. Quarterly testing of the RHRSW pumps verifies the capability of the valves to operate properly to pass the maximum required accident flow, as well as the valve position necessary to achieve the required flow conditions. Testing of the valves in this manner demonstrates valve performance capability and provides an indirect means for monitoring valve degradation. Measuring the stroke times as required by the ASME OM Code is not possible because they are indirectly stroke timed and no meaningful comparison between tests and valve degradation can be obtained. In addition, these valves are within the scope of Monticello's AOV Program. As such, the condition of the valves will also be monitored by diagnostic testing per the AOV Program.

Therefore, the NRC staff finds that requiring stroke time testing and full stroke exercising per ISTC-5131, ISTC-5132 and ISTC-5133, for AOVs CV-1728 and CV-1729, is impractical. The proposed relief request, to verify valve disc movement during quarterly RHRSW pump testing, provides reasonable assurance of the operational readiness of these control valves.

3.9.1. Licensee's Alternative Request VR-03 Paragraph ISTA-3130, "Application of Code Cases," (b) states that "Code cases shall be applicable to the edition and addenda specified in the test plan."

- 23 Paragraph ISTC-5121, "Motor-Operated Valves: Valve Stroke Testing," (a) states that "Active valves shall have their stroke times measured when exercised in accordance with ISTC-3500."

ISTC-3700, "Position Verification Testing," states, in part, that "Valves with remote position indicators shall be observed locally at least once every two years to verify that valve operation is accurately indicated."

ASME OM Code Case OMN-1, Revision 1, (OMN-1-1), "Alternative Rules for Preservice and Inservice Testing of Active Electric Motor-Operated Valve Assemblies in Light-Water Reactor (LWR) Power Plants," which provides periodic exercising and diagnostic testing for use in assessing the operational readiness of motor-operated valves (MOVs). Regulatory Guide (RG) 1.192 allows licensees to implement ASME Code Case OMN-1, Revision 0, in accordance with the provisions in the RG as an alternative to the Code provisions for MOV stroke time testing in the ASME OM Code 1995 Edition through 2000 Addenda.

The licensee requested to use Code Case OMN-1-1 as an alternative to certain ASME OM Code 1ST requirements pertaining to testing of MOVs currently in Monticello MOV Program.

Reason for Request

NUREG-1482, Revision 1, Section 4.2.5 states, in part, that as an alternative to MOV stroke time testing, ASME developed Code Case OMN-1, Revision 0, "Alternative Rules for Preservice and Inservice Testing of Certain Electric Motor-Operated Valve Assemblies in LWR Power Plants," which provides periodic exercising and diagnostic testing for use in assessing the operational readiness of MOVs. Section 4.2.5 recommends that the licensees implement ASME Code Case OMN-1, Revision. 0, as accepted by the NRC (with certain conditions) in the regulations or RG 1.192, as an alternative to the stroke time testing provisions in the ASME OM Code for MOVs. RG 1.192 allows licensees to implement ASME Code Case OMN-1,

Revision 0, in accordance with the Code provisions for MOV stroke time testing in the ASME Code 1995 Edition through 2000 Addenda.

Proposed Alternative and Basis for Use Pursuant to the guidelines provided in NUREG-1482, Revision 1, Section 4.2.5, and the conditions stated in RG 1.192. NSPM proposes to implement Code Case OMN-1, Revision 1. in lieu of the stroke time provisions specified in ISTC-5121 for MOVs as well as the position verification testing in ISTC-3700.

There are no significant differences between the version of Code Case OMN-1 that is in the 1999 Addenda of the ASME OM Code currently approved for use in RG 1.192, Revision 0 and the Revision 1 of the Code Case (OMN-1-1) in 2009 Edition of the ASME OM Code.

The use of Code Case OMN-1-1 by a licensee permits the licensee to replace stroke time and position verification testing of MOVs with a program of exercising MOVs every refueling outage and diagnostically testing on longer intervals.

- 24 The proposed alternative is considered to be acceptable because Code Case OMN-1-1 provides a superior method than the stroke timing method required by the ASME OM Code for assessing the operational readiness of MOVs.

3.9.2

NRC Staff Evaluation

Application of 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, Table 2, conditionally approves the use of Code Case OMN-1 and states that the code case is applicable to the 2000 Addenda and earlier editions and addenda of the Code. Licensees are allowed the option of using Code Case OMN-1 as an alternative to the ASME OM Code requirements for MOV stroke time and position verification testing. Code Case OMN-1 was revised in the 2006 Addenda to the ASME OM Code. Most of the revisions are enhancements such as clarification of valve remote position indication requirements and ball/plug/diaphragm valve test requirements. and the expansion of risk-informed provisions.

The NRC staff finds that there are no significant differences between the version of Code Case OMN-1 that is currently approved for use in RG 1.192, and the Code Case OMN-1-1 in the 2009 Edition of the ASME OM Code.

There are recognized weaknesses in the stroke time testing requirements for MOVs in the ASME OM Code. and the use of Code Case OMN-1-1 by a licensee resolves these weaknesses. Code Case OMN-1-1 permits licensees to replace stroke time and position verification testing of MOVs with a program of exercising MOVs every refueling outage (not to exceed 2 years) and diagnostically testing on longer intervals. The NRC staff considers the proposed alternative to be acceptable because Code Case OMN-1-1 provides a superior method than the stoke-timing method required by the ASME OM Code for assessing the operational readiness of MOVs. The NRC staff has recommended that licensees implement Code Case OMN-1 as an alternative to the MOV stroke time and position verification testing provisions in the ASME OM Code. Since there are no significant differences between the version of Code Case OMN-1 that is currently approved for use in RG 1.192 and the version of Code Case OMN-1-1 in the 2009 Edition of the ASME OM Code, the NRC staff finds that use of Code case OMN-1-1 with the conditions specified in RG 1.192, provides an acceptable level of quality and safety for testing all MOVs in the Monticello MOV program.

3.10.1 Licensee's Alternative Request VR-04 Mandatory Appendix I, Section 1-1320. "Test Frequencies. Class 1 Pressure Relief Valves," (a) requires that Class 1 pressure relief valves be tested at least once every five years.

ASME OM Code Case OMN-17, "Alternative Rules for Testing ASME Class 1 Pressure Relief/Safety Valves." provides an alternative test frequency for Class 1 pressure relief valves provided that the licensee disassembles and inspects each valve after as-found set-pressure testing to verify that parts are free of defects resulting from timed-related degradation or service induced wear.

- 25 The licensee requested to use Code Case OMN-17 as an alternative to certain ASME OM Code 1ST requirements pertaining to testing of the following main steam Safety/Relief Valves (S/RVs):

RV-2-71A. Main Steam S/RV (Class 1)

RV-2-71 B. Main Steam S/RV (Class 1)

RV-2-71 C. Main Steam S/RV (Class 1)

RV-2-71D. Main Steam S/RV (Class 1)

RV-2-71E. Main Steam S/RV (Class 1)

RV-2-71 F. Main Steam S/RV (Class 1)

RV-2-71G. Main Steam S/RV (Class 1)

RV-2-71 H. Main Steam S/RV (Class 1)

Component/System Function The Nuclear Boiler System provides reactor pressure vessel overpressure protection by opening the S/RVs. The valves must open in order to prevent over pressurization of the reactor coolant system, thereby preventing failure of the reactor system due to overpressure. The overpressure relief operation is self-actuated. The valves will open automatically or manually by the air operator during depressurization operation.

Certain valves are a designated part of the Automatic Depressurization System (ADS) and must open to provide automatic reactor depressurization as a result of a small break in the nuclear system coincidental with a failure of the HPCI System. Rapid depressurization is necessary so that the Low Pressure Coolant Injection and the Core Spray systems can operate to protect the fuel cladding. ADS is automatically actuated after receipt of simultaneous RHR or Core Spray pump running and low-low reactor water level signals.

In addition to the above. certain valves are designated as part of the S/RV Low-Low Set System and are set to open automatically at a set-point lower than the mechanical self-actuated set point to prevent the reopening of a non-low-low set S/RV following a reactor isolation transient.

The set-points of the low-low set S/RVs ensure that they will be the first S/RVs to open and the last to close. After opening and closing of a lOW-low set S/RV. a time delay relay prevents the operator or the low-low set logic from immediately re-opening the S/RV to allow the water leg in the S/RV discharge line to recede. The valves will open as part of the S/RV Low-Low Set System in the event of a reactor SCRAM with reactor pressure greater than the lOW-low setpoint and the S/RV low-low set hand switch in the auto position.

Reason for Request

Monticello transitioned from an 18-month fuel cycle to a 24-month fuel cycle on September 30, 2005. via License Amendment No. 143. Prior to transitioning to the 24-month fuel cycle. ASME Code requirements could be satisfied by removing and testing approximately one-third of the eight S/RVs each refueling outage in order to comply with the five-year test interval requirements for Class 1 pressure relief valves imposed by the ASME OM Code of Record during that time. Since transitioning to the 24-month fuel cycle. NSPM must remove at least one-half of the subject relief valves each refueling outage for off-site testing. The removal of approximately half of the eight valves versus approximately a third of the valves each outage

- 26 requires the removal of additional insulation, instrumentation, and other interferences. This additional work results in an undesirable increase in radiation exposure to maintenance personnel. The ASME Code Committee has recently developed Code Case OMN-17, "Alternative Rules for Testing ASME Class 1 Pressure Relief/Safety Valves," which was published in the 2009 Edition of the ASME OM Code. This Code Case has not been approved for use in RG 1.192, "Operation and Maintenance Code Case Acceptability, ASME OM Code,"

dated June 2003. The Code Case allows the Owner to extend the test frequencies for Class 1 pressure relief valves to a 72-month (six-year) test interval providing all the requirements of the Code Case are satisfied. The Code applicability specified in the Code Case is, in part, ASME OM Code 2001 Edition through the 2006 Addenda of Appendix I, Section 1-1320. This is consistent with the fifth interval Code of Record for Monticello. NSPM currently meets or exceeds all the requirements specified in Code Case OMN-17.

Proposed Alternative As an alternative to the ASME OM Code-required five year test interval per Appendix I, paragraph 1-1320(a), the licensee proposed that the subject Class 1 pressure relief valves be tested at least once every three refueling cycles (approximately six years or 72 months) with a minimum of 20% of the valves tested within any 24-month interval. This 20% would consist of valves that have not been tested during the current 72-month interval, if they exist. The test interval for any individual valve would not exceed 72 months except that a six month grace period is allowed to coincide with refueling outages to accommodate extended shutdown periods.

After as-found set pressure testing, the valves shall be disassembled and inspected to verify that parts are free of defects resulting from time-related degradation or service induced wear.

As-left set pressure testing shall be performed following maintenance and prior to returning the valve to service. Each valve shall have been disassembled and inspected prior to the start of the 72-month interval. Disassembly and inspection performed prior to the implementation of Code Case OMN-17 may be used.

The relief valve testing and maintenance cycle at Monticello consists of removal of the S/RV complement requiring testing and transported to an off-site test facility. Upon receipt at the off site facility the valves are subject to an as-found inspection and set pressure testing. Prior to the return of a complement of SRNs for installation in the plant, the valves are disassembled and inspected to verify that internal surfaces and parts are free from defects or service induced wear prior to the start of the next test interval. During this process, anomalies or damage are identified and dispositioned for resolution. Damaged or worn parts, springs, gaskets and seals are replaced as necessary. The valve seats are relapped, if necessary. Following reassembly, the valve's set pressure is recertified. This existing process is in accordance with ASME OM Code Case OMN-17 paragraphs (d) and (e). The licensee has reviewed the as-found set point test results for all of the S/RV's tested since 1996. The average as-found set pressure is 1100.4 psig. The licensee did not have any as-found tests since 1996 that exceeded the TSs as-found

+ 33.2 psig acceptance criteria. The licensee stated that the proposed alternative of increasing the test interval for the subject Class 1 pressure relief valves from five years to three fuel cycles (approximately six years, or 72 months) would continue to provide an acceptable level of quality and safety while restoring the operational and maintenance flexibility that was lost when the 24

- 27 month fuel cycle created the unintended consequences of more frequent testing. This proposed alternative will continue to provide assurance of valve operational readiness and provides an acceptable level of quality and safety pursuant to 10 CFR 50.55a(a)(3)(i).

3.10.2 NRC Staff Evaluation Mandatory Appendix I, Paragraph 1-1320(a) requires that Class 1 pressure relief valves shall be tested at least once every five years. In lieu of the five-year test interval required by Paragraph 1-1320(a), the licensee proposed to implement Code Case OMN-17, which allows a test interval of six years plus a six-month grace period.

A major difference between the current testing required by Paragraph 1-1320(a) and the proposed alternative is that the alternative results in less frequent testing of the S/RV components, but requires additional disassembly and inspection of the relief valves and additional testing if relief valves in the test group exceed the setpoint acceptance criteria. The Code Case imposes a special maintenance requirement to disassemble and inspect each valve to verify that parts are free from defects resulting from time-related degradation or maintenance induced wear prior to the start of the extended test frequency. The purpose of this maintenance requirement is to reduce the potential for set pressure drift. Code Case OMN-17 has not been added to Regulatory Guide 1.192, "Operation and Maintenance Code Case Acceptability, ASME OM Code," or included in 10 CFR 50.55a by reference. However, the NRC has allowed licensees to use OMN-17, provided all requirements in the code case are met. Consistent with the special maintenance requirement in Code Case OMN-17, each S/RV will be refurbished to a like-new condition prior to the start of each 6.5-year test interval. Critical components will be inspected for wear and defects, and the critical dimensions will be measured during the inspection.

Components will be reworked to within the specified tolerance or replaced if found to be worn or outside of specified tolerances. Furthermore, Code Case OMN-17 is performance based in that it requires SJRVs be tested more frequently if test failures occur. For example, OMN-17 requires that two additional valves be tested when a valve in the initial test group exceeds the set pressure acceptance criteria. All remaining valves in the group are required to be tested if one of the additional valves tested exceeds its set pressure acceptance criteria. Therefore, the SfRV test frequency would be equivalent to the current test frequency, if test failures occur. In addition, the licensee has had no setpointfailures of the valves since 1996. Therefore, the NRC staff finds that the proposed testing frequency, with additional OMN-17 requirements, provides adequate periodic verification of valve operation.

The NRC staff determined that the proposed alternative testing conditions, and frequencies of the S/RVs and associated components provide reasonable assurance that the valves will continue to operate when called upon to perform their safety-related function and provides an acceptable level of quality and safety.

4.0 CONCLUSION

As set forth above, the NRC staff determined that for requests PR-02, PR-04, PR-06 Revision 1, VR-03, and VR-04, the proposed alternatives provide an acceptable level of quality and safety.

- 28 All other ASME OM Code requirements for which relief was not specifically requested and approved in the subject requests remain applicable.

As set forth above, the NRC staff determines that for requests PR-01, PR-03, PR-05, and VR-01, the proposed alternatives provide reasonable assurance that the components are operationally ready. All other ASME OM Code requirements for which relief was not specifically requested and approved in the subject requests remain applicable.

Accordingly, the NRC staff concludes that the licensee has adequately addressed all of the regulatory requirements set forth in 10 CFR 50.55a(a)(3)(i) for requests PR-02, PR-04, PR-06 Revision 1, VR-03, and VR-04, and 10 CFR 50.55a(a)(3)(ii) for requests PR-01, PR-03, PR-05, and VR-01, and is in compliance with the ASME OM Code requirements. Therefore, the NRC staff authorizes alternative requests PR-01, PR-02, PR-03, PR-04, PR-05, PR-06 Revision 1, VR-01, VR-03, and VR-04, at Monticello for the fifth 10-year 1ST program interval which begins on September 1,2012, and ends on August 31,2022.

As set forth above, the NRC staff determined that for request VR-02, granting relief pursuant to 10 CFR 50.55a(f)(6)(i) is authorized by law and will not endanger life or property or the common defense and security, and is otherwise in the public interest giving due consideration to the burden upon the licensee that could result if the reqUirements were imposed on the facility. All other ASME OM Code requirements for which relief was not specifically requested and approved in the subject request remain applicable. Therefore, the NRC staff grants relief for request VR-02 at Monticello for the fifth 10-year 1ST program interval which begins on September 1,2012, and ends on August 31,2022.

Principle Contributors: John Huang, NRR Robert Wolfgang, NRR Date: September 26, 2012

M. Schimmel

- 2 The NRC staff has reviewed the subject requests and concludes, as set forth in the enclosed safety evaluation. that the licensee has adequately addressed all the regulatory requirements set forth in 10 CFR 50.55a(a)(3)(i). 10 CFR 50.55a(a)(3)(ii), and 10 CFR 50. 55a(f)(6)(i), for the respective requests. Therefore, the NRC staff authorizes alternative requests PR-01, PR-02, PR-03, PR-04, PR-05, PR-06 Revision 1, VR-01, VR-03, and VR-04, and relief is granted for request VR-02, at Monticello for the fifth 10-year 1ST program interval which begins on September 1, 2012, and ends on August 31,2022. All other ASME OM Code requirements for which relief was not specifically requested and approved remain applicable.

If you have any questions, please contact Terry Beltz at (301) 415-3049 or via e-mail at Terry.Beltz@nrc.gov.

Sincerely, IRAJ Istvan Frankl, Acting Chief Plant Licensing Branch 111-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-263

Enclosure:

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