ML12293A362
| ML12293A362 | |
| Person / Time | |
|---|---|
| Site: | Waterford  |
| Issue date: | 11/08/2012 |
| From: | Markley M Plant Licensing Branch IV |
| To: | Entergy Operations |
| Kalyanam N | |
| References | |
| TAC ME9190 | |
| Download: ML12293A362 (9) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 November 8, 2012 Vice President, Operations Entergy Operations, Inc.
Waterford Steam Electric Station, Unit 3 1726S River Road Killona, LA 700S7 -3093
SUBJECT:
WATERFORD STEAM ELECTRIC STATION, UNIT 3 - RELIEF REQUEST VRR-WF3-2012-1, ASSOCIATED WITH CATEGORY A LEAKAGE TESTING OF AUXILLARY COMPONENT COOLING WATER CHECK VALVE ACC-10BB (TAC NO. ME9190)
Dear Sir or Madam:
By letier dated August 3,2012, Entergy Operations, Inc. (the licensee), submitted a request to the U.S. Nuclear Regulatory Commission (NRC) for relief from certain American Society of Mechanical Engineers (ASME) Code for Operation and Maintenance ofNuclear Power Plants (OM Code) at Waterford Steam Electric Station, Unit 3 (Waterford 3). Pursuant to paragraph SO.SSa(f)(S)(iii) of Title 10 of the Code of Federal Regulations (10 CFR), the licensee requested relief from inservice testing (1ST) items on the basis that the code requirement is impractical during the third 10-year 1ST interval, which began on December 1, 2007, and is scheduled to end on November 30,2017. The NRC staff granted the verbal authorization of this request on August 20, 2012.
The ASME OM Code requires that Category A valves be tested at least once every 2 years to verify that seat leakage is within acceptable limits. This test is required to be performed on check valve ACC-10BB in any plant mode by August 21,2012. Due to a leak in the Auxiliary Component Cooling Water (ACCW) Pump B suction isolation valve, ACC-101 B, the licensee could not test the check valve in the discharge line of ACCW Pump B, ACC-10BB, using the normal testing configuration. The licensee evaluated other possible configurations for testing ACC-10BB and concluded that the alternatives either could not be performed or would result in exceeding the Technical Specification, 72-hour Limiting Condition for Operation limit for the ACCW system being inoperable.
The licensee evaluated the leak-test history for check valve, ACC-10BB, and found the leakage rate to be well within acceptable limits. In addition, ACC-10BB was disassembled, inspected, and successfully tested in 2010 as a Preventative Maintenance (PM) task. Therefore, the licensee requests extending the leakage test interval for ACC-1 OBB by approximately 2 months to be completed prior to startup from the next refueling outage (RFO).
The NRC staff has reviewed the subject request and concludes, as set forth in the enclosed safety evaluation, that it is impractical for the licensee to comply with certain requirements of the ASME OM Code for the ACCW check valve, ACC-10BB. Based on the acceptable historical leak-test performance and recent completion of the valve PM task and subsequent successful post maintenance test, extending the proposed leakage test interval for ACC-10B8,
- 2 by approximately 2 months, from August 21,2012, to the RFO 18, scheduled for October 2012, provides reasonable assurance that ACC-108B will remain operationally ready.
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 of the leakage-rate testing, frequency requirement, detailed in this relief request, until the next refueling outage, RFO 18, which started in October 2012. The 1ST test for check valve, ACC-108B, shall be completed prior to plant restart from RFO 18.
The NRC staffs safety evaluation is enclosed.
Sincerely, Michael T. Markley, Chief Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-382
Enclosure:
Safety Evaluation cc w/encl.: Distribution via Listserv
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555*0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELIEF REQUEST VRR-WF3-2012-1 RELATED TO THE INSERVICE TESTING PROGRAM, THIRD 10-YEAR INTERVAL ENTERGY OPERATIONS, INC.
WATERFORD STEAM ELECTRIC STATION, UNIT 3 DOCKET NO. 50-382
1.0 INTRODUCTION
By letter dated August 3,2012 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML12219A223), Entergy Nuclear Operations Inc. (Entergy, the licensee), submitted relief request, VRR-WF3-2012-1, to the U.S. Nuclear Regulatory Commission (NRC). Request VRR-WF3-2012-1 is applicable to the third 10-year inservice testing (1ST) program interval at Waterford Steam Electric Station, Unit 3 (Waterford 3), which began on December 1,2007, and is scheduled to end on November 30,2017 The licensee requested one-time relief to extend the valve seat leakage test frequency of an Auxiliary Component Cooling Water (ACCW) check valve, ACC-108B, for approximately 2 months. This leakage test is required by the American Society of Mechanical Engineers (ASME) Code for Operation and Maintenance of Nuclear Power Plants (OM Code). Specifically, pursuant to Title 10 of the Code ofFederal Regulations (10 CFR) 50.55a(f)(5)(iii), the licensee requested relief from certain 1ST requirements because compliance is impractical.
On August 20, 2012, the NRC staff verbally authorized the use of Request VRR-WF3-2012-1, which was documented on August 21,2012 (ADAMS Accession No. ML12234A635).
2.0 REGULATORY EVALUATION
The regulations in 10 CFR 50.55a(f), "Inservice testing requirements," require, 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 incorporated by reference in the regulations. Exceptions are allowed where alternatives have been authorized or relief has been granted by the NRC pursuant to paragraphs (a)(3)(i), (a)(3)(ii), or (f)(6)(i) of 10 CFR 50.55a.
In proposing alternatives or requesting relief, the licensee must demonstrate that (1) the proposed alternatives provide an acceptable level of quality and safety (10 CFR 50.55a(a)(3)(i>>;
(2) compliance would result in hardship or unusual difficulty without a compensating increase in Enclosure
- 2 the level of quality and safety (10 CFR SO.SSa(a)(3)(ii>>; or (3) conformance is impractical for its 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 Waterford 3 third 10-year 1ST interval began on December 1,2007, and is scheduled to end on November 30, 2017. The applicable ASME OM Code edition and addenda for the third 10-year 1ST interval is the 2001 Edition through the 2003 Addenda.
3.0 TECHNICAL EVALUATION
The NRC staff has evaluated the information provided by the licensee in support of the request for relief from the ASME OM Code requirements and the bases for disposition are documented below.
3.1 ASME OM Code Requirements ISTC-3610, "Scope of Seat Leakage Rate Test," states, in part, that "Category A valves shall be leakage tested, except that valves which function in the course of plant operation in a manner that demonstrates functionally adequate seat leak-tightness need not be additionally leakage tested."
ISTC-3630, "Leakage Rate for Other Than Containment Isolation Valves," states, in part, that "Category A valves with a leakage requirement not based on an Owner's 10 CFR SO, Nonmandatory Appendix J program, shall be tested to verify their seat leakages within acceptable limits."
ISTC-3630(a) "Frequency," states that, "Tests shall be conducted at least once every 2 years."
3.2 Component for which Relief is Requested The licensee requested relief for check valve, ACC-10BB, in the discharge line of ACCW Pump B. ACC-10BB is a Class 3, Category A,C valve in the Waterford 31ST Program.
3.3 Licensee's Reason for Relief Request In its letter dated August 3,2012, the licensee stated, in part, that ACC-10BB is a spring-loaded check valve in the discharge line from Auxiliary Component Cooling Water (ACCW) Pump B, and must open to allow flow to the Component Cooling Water (CCW) heat exchanger when the ACCW system
[safety function] is required to be operable. The Waterford 3 Technical Specifications [(TSs)] require the ACCW system to be operable in Modes 1, 2, 3, and 4. With ACCW Pump B secured, non-safety ACC Jockey Pump B is designed to keep ACCW system Train B full during normal operations with ACC-10BB closed. ACC-10BB closes when ACCW Pump B is secured to prevent draining portions of ACCW Train B, which are at higher elevations than the ACCW B basin. This precludes a hydraulic transient and preserves system structural integrity when ACCW Pump B starts automatically on the Emergency
- 3 Diesel Generator (EDG) 8 following a Loss of Offsite Power (LOOP) event. In addition, a combined maximum allowable leak rate limit of one gallon per minute (gpm) for ACC-10B8, ACC-10458, and ACC-1148 has been determined based on the acceptable void size in the ACCW System, and the 27 second interval immediately following a LOOP during which time the ACCW pump would remain idle (10 seconds for the EDG to come up to speed plus 17 seconds to load the ACCW pump on the EDG). Based on the size of ACC-10B8 relative to the other two valves, ACC-10BB is assigned an administrative leakage limit of 0.667 gpm.
The Waterford 3 test procedure facilitates seat leakage testing of ACC-10B8 by draining the piping between ACC-1018 (ACCW Pump B Suction [Line] Isolation
[20" manual butterfly] Valve) and ACC-10BB, and measuring the leakage past ACC-10BB at an upstream drain valve. The test procedure requires that the draining process prior to the leak test allow for removal of the existing water between ACC-1 OB8 and ACC-1 01 8 until the visible drain flow reduces to (near) zero leakage, in order to measure the leakage past ACC-10B8.
The licensee asserted that the required ASME OM Code leakage test on check valve ACC-10BB cannot be performed due to gross leakage identified past valve ACC-101B. Plant process data has reflected a rise in a site Waste Tank level and corresponding lowering of the "B" Wet Cooling Tower 8asin due to leakage from the basin through ACC-101 B. Repeated attempts to obtain a tight seal on ACC-1 01 8 have been unsuccessful. In order to repair ACC-1 018, draining of the "B" Wet Cooling Tower Basin would be required, which is not practical with the plant online.
In addition, in its letter dated August 3, 2012, the licensee stated, in part, that Alternative test methods were evaluated to identify ways in which to monitor the ACCW Train B for leakage past check valve ACC-10BB. Due to the piping arrangement, the specification of wafer type butterfly valves at system interconnections, and the ACCW system cross connection with the CCW system, minor system in-leakage from the CCW [into the ACCW] occurs as indicated by CCW surge tank level trends. Due to the impracticality of securing the CCW system while the facility is in mode 1, this ingress [from CCW] will mask leakage past ACC-10B8 and preclude performing a water level decay test, using either ultrasonic examination, or a clear tubing level indicator. Methods for partial draining of the ACCW Train 8 piping downstream of ACC-10B8 were considered; however establishing required initial conditions for a successful test are uncertain due to the large amount of horizontal system piping at the ACCW Train 8 upper elevation, and due to ingress/egress of water at interconnecting wafer butterfly valves.
Other means of isolating the ACCW Train 8 suction piping were evaluated, including inserting a bladder at the suction opening inside the basin and potential use of a freeze seal. Due to the piping arrangement, a freeze seal cannot be employed because of proximity to butt welds, penetrations, and/or branch connections. The ACCW Train.B pump suction piping opening in the wet basin is 20" in diameter and cut on a 45 degree bias (parallel with the basin floor), Per
- 4 the vendor representative [contacted by the licensee], a bladder cannot be successfully installed in the suction entrance due to the pipe size, sealing area surface, and the basin head present.... In addition, removing the Wet [Cooling]
Tower B basin water volume, as required to facilitate testing of ACC-10BB with ACC-101 B leakage would exceed [an ACCW TS], 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> Limiting Condition for Operation (LCO) limit that would require [the unit to be in] Mode 3 within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.
3.4 Licensee's Proposed Relief and Basis The inability to complete the inservice leakage test on ACC-1 OBB within the required test frequency would result in declaring the ACCW Train B inoperable and a 72-hour LCO action statement would need to be entered, ultimately requiring the unit to shut down. TS 3.7.3, "Component Cooling Water and Auxiliary Component Cooling Water Systems," requires that at least two independent CCW and associated ACCW trains shall be OPERABLE in MODES 1, 2, 3, and 4.
The licensee proposes to perform the Category A seat leakage test of ACC-1 OBB prior to returning Waterford 3 to operation from refueling outage (RFO) 1B. This would defer the 2-year frequency leakage test with its allowed 25 percent extension, from August 21,2012. to sometime in October or November of 2012 (Le. approximately 2 additional months).
The licensee stated that it is impractical to perform the 1ST type "AI> leakage test on check valve, ACC-10BB, due to excessive leakage on manual isolation butterfly valve. ACC-1 01 B, which is used to establish test conditions in the current plant conditions (Mode 1). The licensee explained that ACC-10BB was successfully tested in 2002,2004,2006, 200B, and 2010. In addition, ACC-10BB was disassembled and inspected in 2010 as part of a 12-year disassemble/inspection preventive maintenance (PM) task.
In its letter dated August 3,2012, the licensee described the inspections on check valve ACC-10BB, which stated, in part, that The disassemble/Inspection task frequency of 12 years is based on inputs from plant and component operating experience, component criticality, service environment, and duty cycle. The internal inspection included checking for debris and damage to seat, hinge arm, and disk; inspection for loose, damaged, or missing parts; verifying the check arm and disk assembly moves freely and easily; inspection for damage, unusual wear, cracked, or missing disk pin or post; inspection of the disk arm disk post hole and disk hinge pin hole for unusual wear; checking for erosion and corrosion of the valve body, disk, disk arm, and hinge pin; checking for proper alignment of the disk assembly and the seat; inspection for cracked, chipped, or distorted seats; inspecting for crud build up; cleaning all parts as required; and checking for evidence of leakage around or near the valve body cover gasket, hinge pin cover, valve position indicators, fasteners, pipe flanges and connections. The 2010 [PM] task confirmed that the check valve stroked freely from full open to full closed and had disc to seat contact. The 2010 inspection found acceptable conditions (visual and dimensional) of the internals, stop pin, hinge pin, disc plates, seat, and body, and
- 5 some wear of the internal spring and bushing. The spring and bushings were replaced. Additionally, the [PM] task documents an acceptable 50 [millimeters per minute (mllmin)] seat leakage rate was measured by bench testing [ACC 10S8], at 40-50 pounds per square inch gauge (psig).
Therefore, the licensee explained that the acceptable test results and disassembly/inspection as-found conditions, provide evidence that support this request for delaying testing until RFO 1S, which began October 2012.
3.5
NRC Staff Evaluation
The ASME OM Code requires that Category A valves shall be tested to verify that seat leakage is within acceptable limits. The leakage test shall be conducted at least once every 2 years.
Due to a leaking manual isolation butterfly valve, ACC-1018, the licensee is unable to leak test ACC pump 8 discharge line check valve, ACC-10S8, per the normal testing configuration. The licensee considered other possible configurations for testing ACC-10S8 and concluded that the alternatives either could not be performed or would result in the licensee exceeding the TS, 72-hour LCO limit for the ACCW system being inoperable, thus requiring a plant shutdown. Due to the inability to obtain proper test conditions in MODE 1 of operation, completion of the ASME OM Code requirements for leak testing ACC-1 OS8 are impractical.
Evaluation of the previous 1 O-year leak-test history for check valve, ACC-10S8, shows that the leakage rate has been well within acceptable limits. Also, ACC-10S8 was rebuilt in 2010 and had a successful post-maintenance test. Review of the leak-test history and the PM task and successful post-maintenance test from 2010, supports a minor extension (I.e., a couple of months) of the leak-test interval and provides reasonable assurance or the operational readiness of the ACCW check valve, ACC-10S8.
4.0 CONCLUSION
8ased on the above, the NRC staff determined that it is impractical for the licensee to comply with certain requirements of the ASME OM Code for the ACCW check valve, ACC-10S8.
8ased on the excellent historical leak-test performance and recent completion of the valve PM task and subsequent successful post-maintenance test, extending the proposed leakage test interval for ACC-10S8, by approximately 2 months, from August 21,2012, to RFO 1S (October 2012) still provides reasonable assurance that ACC-10S8 will remain operationally ready.
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.
- 6 Therefore, the NRC staff grants relief of the leakage-rate testing, frequency requirement, detailed in this relief request, until the next refueling outage, RFO 18, which started in October 2012. The 1ST test for check valve, ACC-108B, shall be completed prior to plant restart from RFO 18.
Principal Contributor: Michael Farnan, NRR Date: November 8, 2012
- 2 by approximately 2 months, from August 21, 2012, to the RFO 18, scheduled for October 2012, provides reasonable assurance that ACC-1 08B will remain operationally ready.
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 of the leakage-rate testing, frequency requirement, detailed in this relief request, until the next refueling outage, RFO 18, which started in October 2012. The 1ST test for check valve, ACC-1 08B, shall be completed prior to plant start-up.
The NRC staffs safety evaluation is enclosed.
Sincerely, IRA!
Michael T. Markley, Chief Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-382
Enclosure:
Safety Evaluation cc w/encl.: Distribution via Listserv DISTRIBUTION:
PUBLIC RidsNrrLA~1Burkhardt Resource LPLIV rlf RidsNrrPMWaterford 3 Resource RidsAcrsAcnw _MailCTR Resource RidsOgcRp Resource RidsNrrDeEptb Resource RidsRgn4MailCenter Resource RidsNrrDorlDpr Resource MFarnan, NRRIDE/EPTB RidsNrrDorlLpl4 Resource ADAMS Accession No.: ML12293A362
- SE email dated 8/17/2012 i OFFICE I NRRlLPL4/PM NRR/LPL4/PM NRR/LPL4/LA NRRIDE/EPTB/BC NRRlLPL4/BC
- NAME
!JRankin NKalyanam JBurkhardt AMcMurtray*
MMarkley
,DATE 1 11/5/12 i 1116112 11/5/12 8117/12 11/8/12 OFFICIAL RECORD COpy