ML13022A456

Evaluation of Relief Request Number PRR-002, Revision 1 for the Third 10-Year Interval Inservice Testing Program for Fermi 2

ML13022A456
Person / Time
Site:	Fermi
Issue date:	01/31/2013
From:	Mahesh Chawla Plant Licensing Branch III
To:	Plona J Detroit Edison, Co
Chawla M
References
TAC ME8007, PRR-002, Rev 1
Download: ML13022A456 (10)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 January 31,2013 Mr. Joseph H. Plona Senior Vice President and Chief Nuclear Officer Detroit Edison Company Fermi 2 - 200 TAC 6400 North Dixie Highway Newport, MI 48166

SUBJECT:

FERMI 2 - EVALUATION OF RELIEF REQUEST PRR-002, REVISION 1, FOR THE THIRD 10-YEAR INTERVAL INSERVICE TESTING PROGRAM FOR FERMI 2 (ME8007)

Dear Mr. Plona:

By letter dated February 20, 2012 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML12052A043), Detroit Edison Company, (the licensee), submitted Relief Request PRR-002, Revision 1, to the U.S. Nuclear Regulatory Commission (NRC). On June 11,2012, the NRC requested the licensee to submit additional information to support this request. By letter dated July 20,2012 (ADAMS Accession No. ML12205A067), the licensee submitted this additional information. Relief Request PRR-002, Revision 1, is applicable to the third 1O-year inservice testing (1ST) program interval at Fermi 2.

In PRR-002, Revision 1, the licensee requested an extension of the relief, granted by the NRC (ADAMS Accession No. ML1016703517), from certain requirements of the American Society of Mechanical Engineers (ASME) Code for Operation and Maintenance of Nuclear Power Plants (OM Code) requested in the original PRR-002. This request involves testing of the core spray system (CSS) pumps E21 01 C001A, E21 01 C001 B, E21 01 C001 C, and E21 01 C001 D, and is being made to support additional modifications to the CSS pump test lines to allow both ASME OM Code individual pump testing and technical specification (TS) surveillance requirement (SR) pump testing.

Specifically, pursuant to Title 10 of the Code of Federal Regulations (10 CFR) 50.55a(f)(5)(iii),

the licensee requested relief in PRR-002, Revision 1, from certain code requirements on the basis that compliance with the ASME OM Code is impractical. This safety evaluation (SE) supersedes the original SE issued by the NRC staff (ADAMS Accession No. ML1016703517) for the Fermi 2, original request regarding PRR-002.

The NRC staff has completed its review of the submittal and concludes that the licensee has adequately addressed all of the regulatory requirements set forth in 10 CFR 50.55a(f)(6)(i), and is in compliance with the ASME OM Code's requirements. Therefore, the NRC staff grants relief for request PRR-002, Revision 1, at Fermi 2 through the end of refueling outage (RF) 17, except for the use of reference curves as described in alternative testing requirement 1. The use of reference curves may continue until one year after startup from RF17. All other ASME OM Code requirements for which relief was not specifically requested and approved remain applicable.

- 2 If there are any further questions or comments, please contact me @ Mahesh.chawla@nrc.gov or (301) 415-8371.

Sincerely,

£W./lM--

Mahesh L. Chawla, Project Manager Plant Licensing Branch 111-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-341

Enclosure:

Safety Evaluation cc w/encls: Distribution via ListServ

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELIEF REQUEST PRR-002, REVISION 1, FOR THE THIRD 10-YEAR INTERVAL INSERVICE TESTING PROGRAM DETROIT EDISON COMPANY FERMI 2 DOCKET NO. 50-341

1.0 INTRODUCTION

By letter dated February 20,2012 (Agencywide Document Access and Management System (ADAMS) Accession No. ML12052A043), Detroit Edison Company (the licensee), submitted Relief Request PRR-002, Revision 1, to the U.S. Nuclear Regulatory Commission (NRC). On June 11, 2012, the NRC requested the licensee to submit additional information to support this request. By letter dated July 20, 2012 (ADAMS Accession No. ML12205A067), the licensee submitted this additional information. Relief Request PRR-002, Revision 1, is applicable to the third 10-year inservice testing (1ST) program interval at Fermi 2. In PRR-002, Revision 1, the licensee requested an extension of the relief, granted by the NRC (ADAMS Accession No. ML1016703517), from certain requirements of the American Society of Mechanical Engineers (ASME) Code for Operation and Maintenance of Nuclear Power Plants (OM Code) requested in the original PRR-002. This request involves testing of the core spray system (CSS) pumps E2101C001A, E2101C001B, E2101C001C, and E2101C001D, and is being made to support additional modifications to the CSS pump test lines to allow both ASME OM Code individual pump testing and technical specification (TS) surveillance requirement (SR) pump testing.

Specifically, pursuant to Title 10 of the Code of Federal Regulations (10 CFR) 50.55a(f)(5)(iii),

the licensee requested relief, in PRR-002, Revision 1, from certain Code requirements on the basis that compliance with the ASME OM Code is impractical.

This safety evaluation (SE) supersedes the original SE issued by the NRC staff (ADAMS Accession No. ML1016703517) for the Fermi 2, original request regarding PRR-002.

2.0 REGULATORY EVALUATION

In 10 CFR 50.55a(f), "Inservice Testing Requirements," it requires, in part, that 1ST of certain ASME Code Class 1, 2, and 3, pumps and valves be performed in accordance with the specified ASME OM Code and applicable addenda incorporated by reference in the regulations.

Enclosure

-2 Exceptions are allowed where alternatives have been authorized or relief has been requested by the licensee and granted by the NRC pursuant to paragraphs (a)(3)(i), (a)(3)(ii), or (f)(6)(i) of 10 CFR SO.SSa.ln proposing alternatives or requesting relief, the licensee must demonstrate that: (1) the proposed alternatives provide an acceptable level of quality and safety (10 CFR SO.SSa(a)(3)(i>>; (2) 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 (3) 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 Code requirements upon making necessary findings.

The Fermi 2, third 10-year 1ST program interval began on February 17, 2010, and is currently scheduled to end on February 16, 2020. The applicable ASME OM Code edition and addenda for the Fermi 2, third 10-year 1ST program interval is the 2004 Edition (no Addenda).

The NRC staffs findings, with respect to granting relief to the ASME OM Code associated with, PRR-002, Revision 1, are given below:

3.0 TECHNICAL EVALUATION

3.1 Licensee's Request and Proposal for Relief In ISTB-3200, "Inservice Testing," it states, in part, "Inservice testing of a pump in accordance with this Subsection shall commence when the pump is required to be operable."

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

In Table ISTB-3400-1, "Inservice Test Frequency," it notes that Group A tests shall be performed quarterly and comprehensive pump tests shall be performed biennially.

In ISTB-S121, "Inservice Testing: Group A Test Procedure," it states, in part, "Group A tests shall be conducted with the pump operating at a specified reference point" In Table ISTB-5121-1, "Centrifugal Pump Test Acceptance Criteria," it defines the required acceptance criteria for centrifugal pumps for Group A, Group B, and comprehensive pump tests.

The CSS protects the reactor core in the event of a large-break loss-of-coolant accident (LOCA) if the feedwater (FW), control rod drive (CRD), reactor core isolation cooling (RCIC), high pressure coolant injection (HPCI), or residual heat removal (RHR) systems are unable to maintain reactor water level. The system consists of two independent,100 percent capacity divisions, each containing two parallel pumps. Each pump is capable of providing SO percent of the required flow for that division. Both pumps in a division are required to be operable in order for the division to be considered operable (Pumps A and C comprise Division 1; pumps Band D comprise Division 2).

The current design of the test line for each division will permit full flow testing of two pumps simultaneously as required by TS SR 3.S.1.8. However, it is impractical to test the pumps of a given division individually, as required by the ASME OM Code, since the test lines and test valves are sized for two-pump testing. The test line flow control valves are throttled

-3 approximately 13 percent open (Division 1) or 9 percent open (Division 2) to control two-pump test flow. The existing flow control valves are not capable of throttling low enough (less than 5 percent open) to accommodate single pump operation without experiencing unstable operation, cavitation, and severe vibration. Significant damage to the test line valves occurred during attempts to throttle for single-pump operation during plant initial startup testing.

Further, due to the oversized test lines and test valves, it is impractical to throttle to a fixed reference value during two-pump testing. The flow control valves are opened to a point in their travel in which small changes in valve position result in large changes in flow rate. Thus, it presents an unnecessary challenge to both the equipment and the plant operators to attempt to return to a specific fixed reference value at each pump test.

At the time the original PRR-002 was submitted, a modification was planned in which several reducing orifices would be installed in each test line. This modification would have allowed for individual pump testing as well as providing enhanced throttling capability, allowing for standard pump testing with fixed reference values. This original test line modification was to be performed during the Fermi 2 refueling outage (RF)15, which was scheduled to start on March 30, 2012, and end on April 30, 2012.

Although this originally proposed modification would have enabled single core spray pump testing in accordance with the ASME OM Code requirements, full-flow testing of the two pumps simultaneously, as required by TS SR 3.5.1.8, would no longer be feasible since the reducing orifices would reduce flow limits in the test lines so that the required two-pump flow could not be achieved. The licensee planned to submit a license amendment request (LAR) to replace the core spray subsystem testing requirement in SR 3.5.1.8 with an individual pump test requirement. Subsequently, a decision was made to revise the scope of the original modification to the test lines. The revised modification scope precludes the need for an LAR by maintaining the current capability of performing full-flow divisional core spray pump testing (two pumps in parallel) while also allowing the performance of individual pump tests.

This new modification would replace the existing throttle valves in the test lines, with new style "drag" operated valves that incorporate multi-stage pressure reducing elements. However, due to the lead time involved in ordering these valves and the required revision to the dynamic analysis for the suppression pool-attached piping, installation can no longer be completed by RF 15 as originally proposed in PRR-002. Instead, the revised modification is now planned to be completed by the 1ih RF17 scheduled for the spring of 2015.

In the interim, the licensee has requested relieffor CSS centrifugal pumps E2101C001A, E21 01 COO'I B, E21 01 C001 C, and E21 01 C001 0, from the requirements of the following three ASME OM Code paragraphs:

• Relief is requested from ASME OM Code ISTB, Inservice Testing of Pumps, in order to perform quarterly testing of both core spray pumps in each division simultaneously in parallel. That is, both pumps are to be run together and be treated as a single component rather than being tested individually. This relief is requested through the end of RF17, which is currently scheduled in the spring of 2015.

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• Relief is requested from ASME OM Code ISTB-5121, in order to utilize a flow reference curve, rather than a single-fixed reference value for flow. This relief is requested until one year after startup from RF17 to allow for one additional year to assess system flow throttling capability following completion of the plant test line modifications.

• Relief is requested from ASME OM Code ISTB-3400, in order to delay the first performance of the biennial comprehensive pump test (CPT) required for each core spray pump.

Specifically, it is requested that the due date for the performance of the first CPT on these pumps be extended through the end of RF17.

Until the test line modifications for the pumps are complete, the licensee has proposed the following alternative testing:

1. Quarterly Group A type testing will be performed for both core spray pumps in each Division in parallel. Hydraulic acceptance criteria will be based on flow reference curves rather than reference points. Reference curves will be established for each division.

2. Group A type testing will be performed at nominally full-flow conditions of greater than or equal to 6,600 gpm per division.

3. The following Group A hydraulic acceptance criteria will be used in order to enhance the ability to detect degradation of a single pump:

Acceptable AP Range - 0.94 to 1.06 APr Alert AP Range - 0.92 to < 0.94 llPr Required Action llP Range - Low < 0.92 APr and High> 1.06 llPr (Where APr equals the differential pressure reference value)

The acceptance criteria are more stringent than those otherwise specified in Table ISTB 5121-1.

4. The monitoring, analysis, and evaluation requirements of ISTB-6000, "Monitoring, Analysis, and Evaluation," will apply using the modified hydraulic acceptance criteria above.

(Performance trending of the CSS pumps will include normalization of the llP data to a fixed reference value to eliminate scatter within the llP data caused by test flow values above or below a nominal fixed reference flow to provide the ability to detect degradation).

5. When a reference curve may have been affected by repair, replacement, or routine servicing of a pump, a new reference curve will be determined or an existing reference curve will be reconfirmed.

6. The vibration acceptance criteria of Table ISTB-5121-1 are applicable and will be applied to each pump individually. A single Alert criteria and a single Required Action criteria will be used over the range of the pump curve. Individual vibration reference values for all four pumps were taken during baseline testing in 1984. These reference values range from a low of 0.131 to a high of 0.315 and were relatively consistent over the test flow range. As a result, the Code maximum limits of 0.325 in.lsec. Alert and 0.700 in.lsec. Required Action will be used for all monitoring points on all four pumps.

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7. The first CPT will be performed on each of the core spray pumps by the end of RF17. The second CPT will be performed two years following the first CPT in accordance with ISTB 3400-1 test frequency requirements.

3.2 NRC Staff Evaluation The CSS at Fermi 2 is a unique design which includes two divisions with two pumps in each division. If one of the two pumps in either division is declared inoperable, then that division is inoperable. There are no functions of the CSS for single-pump operation in either division. The CSS also includes a test line that is used to test both pumps in each division simultaneously while the plant is at power. Both pumps are required to operate in order to achieve the TS flow rate specified in SR 3.5.1.8 of at least 6350 gpm at a system head corresponding to a reactor pressure of 2:100 psig.

The ASME OM Code requires in Section ISTB that pumps must be tested individually to detect a deviation in hydraulic and mechanical performance at points of operation readily duplicated during subsequent tests. These points of operation, referred to as reference values, are the baseline points from which the acceptance criteria are established. When maintenance on a pump has the potential to affect an individual reference value or a set of reference values, new reference values must be established. If the deviation in hydraulic performance of an individual centrifugal pump falls within the required action range, the pump is declared inoperable until the cause of the deviation is determined and the condition is corrected.

The design of the CSS at Fermi 2 is such that each train is capable of being tested at substantial flow conditions, but it is impractical to test each pump in the train individually because the test flow loop (specifically, the flow control valve) is sized to test both pumps simultaneously. In order to test a pump individually, the flow control valve would be open less than 5 percent of valve stem travel. Operation at this valve setting would be accompanied by unstable operation, cavitation, severe vibration, and possible system damage. Operation of the CSS pumps individually for testing is, therefore, impractical within the limitations of the current system design.

In ISTB-5121 it requires that pumps must be throttled to a specific hydraulic reference point (either flow or differential pressure) for testing. Because of the design of the test line and the sizing of the flow control valve, small changes in valve position result in large changes in flow rate presenting a challenge to both the equipment and the plant operators to throttle to a specific reference point. It is, therefore, impractical within the limitations of the current system design to obtain a repeatable reference value in accordance with ASME OM Code requirements.

In ISTB-3400 it requires that the core spray pumps be tested (1) quarterly per the Group A test procedure, and (2) biennially per the CPT procedure. Procedurally, the CPT is essentially the same as the Group A test, except that the CPT seeks to identify relatively smaller changes in hydraulic performance than the Group A test, through the use of higher preCision instrument accuracy in the differential pressure measurement. However, testing the core spray pumps in parallel (Le., measuring the combined hydraulic performance of both pumps) has the potential to mask small performance changes in either pump individually, thus defeating the intent of the CPT. Performance of the CPT is, therefore, impractical within the limitations of the current system design.

-6 The future CSS test line modification will allow for individual pump testing, as well as provide enhanced throttling capability, allowing for standard pump testing with fixed reference values.

This modification, when complete, should eliminate the impracticalities discussed above and should, therefore, obviate the need for relief from these ASME OM Code requirements.

In the original submittal of this relief request, the licensee described plans to install a modification in which several reducing orifices would be placed in each test line. This modification would allow for individual pump testing, as well as enhanced throttling capability, allowing for use of a single-fixed reference value in the test acceptance criteria. The modification was planned to be installed during the 15th RF15 scheduled for the spring of 2012.

Although the original proposed modification would enable single CSS pump testing in accordance with the ASME OM Code requirements, full-flow testing of two pumps simultaneously, as required by TS SR 3.5.1.8, would no longer be feasible since the reducing orifices would reduce flow limits in the test lines such that the required two-pump flow would not be achieved. The licensee, therefore, had planned to submit an LAR to replace the core spray subsystem testing requirement in TS SR 3.5.1.8 with an individual pump test requirement.

Subsequently, a decision was made to revise the scope of the test line modifications for the pumps. The revised modification scope precludes the need for an LAR by maintaining the current capability of performing a full-flow divisional CSS pump testing (two pumps in parallel) while also allowing the performance of individual pump tests.

The revised modification would replace the existing throttle valves in the test lines with new style "drag" operated valves that incorporate multi-stage pressure reducing elements. However, due to the extra lead time involved in ordering these valves, and the required revision to the dynamic analysis for the suppression pool-attached piping, it presents a hardship to complete the installation by RF15; instead, the modification is now planned to be completed by the 17th RF17, scheduled for the spring of 2015.

The NRC staff notes that the revised modification, even conSidering its delayed implementation schedule, has advantages over the original modification proposal. The revised modification will provide a more comprehensive test capability for the CSS, in that the pumps will be testable individually for ASME OM Code purposes, as well as being testable in parallel operation for TS SR and overall system operability purposes.

In the interim, for CSS centrifugal pumps; E2101C001A, E2101C001B, E2101C001C, and E2101C0010, it would be impractical to test each pump individually, perform Group A testing at a single-fixed reference value for flow, or perform CPT on these pumps. Therefore the NRC staff has determined that trying to meet the noted ASME OM Code ISTB requirements represents an impractical condition.

6. CONCLUSION As set forth above, the NRC staff determined that it is impractical for the licensee to comply with certain requirements of the ASME OM Code for pump testing on CSS pumps; E2101C001A, E2101C001B, E2101C001C, and E2101C0010. The proposed CSS pump testing, specified above, provides reasonable assurance that these CSS pumps will remain operationally ready.

-7 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. Accordingly, the NRC staff concludes that the licensee has adequately addressed all of the regulatory requirements set forth in 10 CFR 50.55a(f)(6)(i), and is in compliance with the ASME OM Code's requirements. Therefore, the NRC staff grants relief for request PRR-002, Revision 1, at Fermi 2 through the end of RF17, except for the use of reference curves as described in alternative testing requirement 1. The use of reference curves may continue until one year after startup from RF17. All other ASME OM Code requirements for which relief was not specifically requested and approved remain applicable.

Principle Contributor: John Billerbeck Date of issuance: January 31, 2013

If there are any further questions or comments, please contact me @ Mahesh.chawla@nrc.gov or (301) 415-8371.

Sincerely, IRAJ Mahesh L. Chawla, Project Manager Plant Licensing Branch 111-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-341

Enclosure:

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