ML14128A333
| ML14128A333 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 05/12/2014 |
| From: | Robert Pascarelli Plant Licensing Branch II |
| To: | Gatlin T South Carolina Electric & Gas Co |
| Williams S | |
| References | |
| TAC MF3333 | |
| Download: ML14128A333 (8) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 May 12, 2014 Mr. Thomas D. Gatlin Vice President, Nuclear Operations South Carolina Electric & Gas Company Virgil C. Summer Nuclear Station Post Office Box 88, Mail Code 800 Jenkinsville, SC 29065 ,
SUBJECT:
VIRGIL C. SUMMER NUCLEAR STATION, UNIT 1 -ALTERNATIVE REQUEST REGARDING CLASS 2 AND 3 PUMP TESTING REQUIREMENTS DURING THE FOURTH TEN-YEAR INSERVICE INSPECTION INTERVAL (TAG NO. MF3333)
Dear Mr. Gatlin:
By letter dated January 6, 2014, South Carolina Electric & Gas Company (SCE&G, the licensee), submitted alternative request RR-4-04 to the U.S. Nuclear Regulatory Commission (NRC). The licensee proposed an alternative to certain inservice testing (1ST) requirements of the American Society of Mechanical Engineers Code for Operation and Maintenance of Nuclear Power Plants, for the 1ST program at Virgil C. Summer Nuclear Station, Unit 1 (VCSNS) in the fourth 10-year 1ST program interval. The request covers specific Class 2 and 3 pumps that were inadvertently not included in a previous alternative request that was approved on November 5, 2013. The application was submitted pursuant to Section 50.55a(a)(3)(i) of Title 10 of the Code of Federal Regulations (1 0 CFR), which requires the applicant to demonstrate that the proposed alternatives would provide an acceptable level of quality and safety.
The NRC staff has reviewed the subject request and concludes, as set forth in the enclosed safety evaluation, that SCE&G has adequately addressed all of the regulatory requirements set forth in 50.55a(a)(3)(i), and therefore authorizes the proposed alternative.
T. Gatlin If you have any questions, please contact the Project Manager, Shawn Williams, at 301-415-1009 or via e-mail at Shawn.Williams@nrc.gov.
Sincerely, Robert J. Pascarelli, Chief Plant Licensing Branch 11-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-395
Enclosure:
Safety Evaluation cc w/encl: Distribution via Listserv
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO ALTERNATIVES TO ASME CODE REQUIREMENTS FOURTH TEN-YEAR INSERVICE INSPECTION PROGRAM INTERVAL SOUTH CAROLINA ELECTRIC & GAS COMPANY SOUTH CAROLINA PUBLIC SERVICE AUTHORITY VIRGIL C. SUMMER NUCLEAR STATION, UNIT 1 DOCKET NO. 50-395
1.0 INTRODUCTION
By letter dated January 6, 2014 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML14009A141 ), South Carolina Electric & Gas Company (SCE&G),
the licensee, submitted alternative request RR-4-04 to the U.S. Nuclear Regulatory Commission (NRC). The licensee proposed an alternative 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 1ST program at Virgil C. Summer Nuclear Station, Unit 1 (VCSNS) for the fourth 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 alternative in RR-4-04 on the basis that the alternative provides an acceptable level of quality and safety.
2.0 REGULATORY EVALUATION
10 CFR 50.55a(f), "lnservice 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 applicable addenda.
10 CFR 50.55a(a)(3), states, in part, that alternatives to the requirements of paragraph (f) of 10 CFR 50.55a may be authorized by the NRC if the licensee demonstrates that: (i) the proposed alternative provides an acceptable level of quality and safety, or (ii) compliance with the specified requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
The VCSNS fourth ten-year 1ST interval began on January .1, 2014, and is scheduled to end on December 31, 2023. The fourth interval 1ST program code of record is the ASME OM Code, 2004 Edition through 2006 Addenda.
Based on the above and subject to the NRC's findings with respect to authorizing the proposed alternative to the ASME OM Code given below, the NRC staff finds that regulatory authority Enclosure
exists for the licensee to request and the Commission to authorize the alternative requested by the licensee.
3.0 . TECHNICAL EVALUATION 3.1 Licensee's Alternative Request RR-4-04 ISTB-3300, "Reference Values," states, in part, that "Reference values shall be established within +/-20 percent of pump design flow rate for the comprehensive test," and "Reference values shall be established within +/-20 percent of pump design flow for the Group A and Group B tests, if practicable."
ISTB-3400, "Frequency of lnservice Tests," states that "An in service test, shall be run on each pump as specified in Table ISTB-3400-1."
- Table ISTB-3400-1, "lnservice Test Frequency," specifies that Group A and Group B tests be performed quarterly and a comprehensive test be performed biennially for Group A and Group B pumps.
Table ISTB-351 0-1, "Required Instrument Accuracy," specifies the instrument accuracies for Group A, Group B, comprehensive, and preservice tests.
Table ISTB-5121-1, "Centrifugal Pump Test Acceptance Criteria," defines the required acceptance criteria for Group A, Group B, and comprehensive tests for centrifugal pumps.
ASME OM Code Case OMN-18, "Alternative Testing Requirements for Pumps Tested Quarterly within +/-20% of Design Flow" states, in part, that "the Group A test maybe performed quarterly within +/-20% of pump design flow rate, with instrumentation meeting the requirements of Table ISTB-3510-1 for the comprehensive and preservice tests, and no comprehensive test is required."
Reason for Request
The ASME OM Code committees have approved ASME Code Case OMN-18, Alternate Testing Requirements for Pumps Tested Quarterly within +/- 20 percent of Design Flow. This code case has not yet been approved for use in Regulatory Guide 1.192, "Operation and Maintenance Code Case Acceptability, ASME OM Code," June 2003.
This code case allows the owner to not perform the Comprehensive Pump Test (CPT) with the associated acceptance criteria, if the quarterly test is performed at +/- 20 percent of design flow and the instrumentation meets the accuracy requirements of Table ISTB-3510-1 for the comprehensive and preservice tests. The basis for the testing strategy in this code case is that a quarterly Group A pump test, performed at the CPT flow rate with more accurate instrumentation, is more effective in assessing a pump's operational readiness than a standard Group A test in conjunction with a biennial CPT.
Additionally, ISTB allows the owner to categorize the pumps in their program. As such, an owner could categorize a pump that otherwise meets the requirements of Group B, as a
Group A (or AB) pump, and test according to the provisions of ASME Code Case OMN-18. In doing this, the owner is obtaining additional data (vibration and flow or differential pressure) quarterly, rather than once every two years.
As a result of the increased requirements on the parameters imposed by the proposed alternative during applicable quarterly tests, there is no added value in performing the biennial comprehensive test on the subject pumps.
Proposed Alternative VCSNS is proposing to utilize the provisions of ASME Code Case OMN-18 and perform a:
modified Group A test in lieu of performing the ASME OM Code-required CPT. The modified Group A test will be run at+/- 20 percent of the pump's design flow rate using +/- 0.5 percent accurate digital gauges or better to determine the pump differential pressure. Vibration tests will be performed with the same vibration acceptance criteria as the standard Group A pump test.
Additionally, VCSNS will utilize an Acceptable Range High limit of 106 percent or lower for quarterly testing, which is also consistent with the planned ASME OM Code change applicable to CPT.
The use of more accurate pressure gauges and a more limiting Acceptable Range during every modified quarterly Group A test compensates for the elimination of the CPT. The CPT has a more limiting Acceptable Range upper bound for differential pressure of 103 percent. Regular testing with more accurate instrumentation and tighter acceptance criteria will provide for better trending of pump performance. Instead of performing seven tests with pressure instruments with :+/- 2 percent accuracy and then performing the eighth test with pressure instruments with a minimum of+/- 0.5 percent accuracy, all eight tests will be performed with the same+/- 0.5 percent accurate digital instruments or better. Due to the improved accuracy, consistent testing methodology, and the addition of quarterly vibration monitoring on Group AB pumps, deviations in actual pump performance indicative of impending degradation are more easily recognized during quarterly performance trending activities.
The provisions ofthis request as an alternative to the requirements of ISTB-3400 and Tables ISTB-3400-1 & ISTB-5121-1 provides a reasonable alternative to the ASME OM Code requirements based on the determination that the proposed alternative will provide adequate indication of pump performance, permit detection of component degradation, and continue to provide an acceptable level of quality and safety. Therefore, pursuant to 10 CFR 50.55a(a)(3)(i), VCSNS requests approval of this alternative to the specific ISTB requirements identified in this request for the following pump:
- XPP0048C, HVAC Chilled Water Pump, (Centrifugal/ Group A I Class 3)
3.2 NRC Staff Evaluation A similar alternative request was previously submitted and approved for the HVAC Chilled Water Pumps at VCSNS, Unit 1, but the request neglected to include all applicable pumps.
(Reference ADAMS No. ML13301A767 for the safety evaluation approving alternative request RR-4-02 for the use of code case OMN-18 on VCSNS Unit 1 HVAC Chilled Water Pumps XPP0048A & B.)
The licensee is proposing to perform a quarterly 1ST for the pump listed above in accordance with a modified Group A test procedure in lieu of quarterly Group A tests and a CPT every two years.
The ASME OM Code requires that for Group A pumps, a Group A test be performed every quarter, and a CPT be performed biennia:lly. The Group A test is performed within +/-20 percent of the pump design flow rate and the pressure instrument accuracy is +/-2 percent. The upper limit for the "Acceptable Range" for flow rate and differential pressure is 110 percent of the reference values, and the high value for the "Required Action Range" for flow rate and differential pressure is greater than 11 0 percent of the reference values. The CPT is performed within +/-20 percent of the pump design flow rate, the pressure instrument accuracy is
+/- 1/2 percent, and the high value of "Required Action Range" is greater than 103 percent of the respective reference values. Vibration monitoring is performed during both the Group A tests and the CPTs.
The licensee proposes that for the pump listed above, a modified Group A quarterly test will be performed using ASME OM Code Case OMN-18, with modified "Required Action" ranges, and the biennial comprehensive test will not be performed. The modified Group A quarterly test would be performed within +/-20 percent of the pump design flow rate, using more accurate pressure instrumentation (i.e. instrument accuracy required for a CPT (+/-1/2 percent instead of
+/-2 percent)). The licensee will use a more limiting high value of 106 percent for the "Required Action Range" in lieu of 110 percent that is normally required by the ASME OM Code for Group A tests. However, the high value 106 percent is greater than the high value of 103 percent for the biennial CPT. Using more accurate pressure gauges and a more limiting "Required Action Range" (compared to the Group A test "Required Action Range") d.uring every modified quarterly Group A test compensatesfor the elimination of the CPT with its more limiting "Required Action Range" high value of 103 percent.
OMN-18 was published in the 2009 Edition of the ASME OM Code. This Edition of the ASME OM Code has not yet been incorporated by reference into 10 CFR 50.55a, and OMN-18 has not been incorporated into Regulatory Guide (RG) 1.192. However, the NRC staff has reviewed OMN-18, and currently has no concerns with its usage, providing that the high values of the Group A test "Required Action Range" for flow (Q) and differential pressure (~P) are greater than 106 percent of the respective reference values. The NRC staff considers the proposed alternative acceptable because all of the tests will be performed with pressure gauges with
+/-1/2 percent accuracy. The elimination of the CPT, with its more limiting "Required Action Range" upper bound of 103 percent of the reference value, is compensated for by using more accurate pressure gauges on every quarterly test. Regular testing with more accurate instrumentation and tighter acceptance criteria will provide for better trending of pump
performance. Therefore, the NRC staff finds that the proposed alternative provides an acceptable level of quality and safety.
4.0 CONCLUSION
As set forth above, the NRC staff finds that the proposed alternative described in RR-4-04 provides an acceptable level of quality and safety for the affected pump. 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). Therefore, the NRC staff authorizes alternative request RR-4-04 at VCSNS for the fourth ten-year 1ST interval which began on January 1, 2014, and is scheduled to end on December 31, 2023.
All other ASME OM Code requirements for which alternatives or relief was not specifically requested and approved in the subject request remain applicable.
Principle Contributor: John Billerbeck, NRR
T. Gatlin If you have any questions, please contact the Project Manager, Shawn Williams, at 301-415-1009 or via e-mail at Shawn.Williams@nrc.gov.
Sincerely,
/RAJ Robert J. Pascarelli, Chief Plant Licensing Branch 11-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-395
Enclosure:
Safety Evaluation cc w/encl: Distribution via Listserv DISTRIBUTION:
Public LPL2-1 R/F JBillerbeck, NRR RidsAcrs_AcnwMaiiCTR Resource RidsNrrLASFigueroa Resource RidsNrrDoriDpr Resource RidsRgn2MaiiCenter Resource RidsNrrPMSummer Resource RidsN~rDeEpnb Resource ADAMS Accession No.: ML14128A333 *By E-mail OFFICE LPLII-1/PM LPLII-1/LA DE/EPNB/BC
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