Information Notice 2012-16, Preconditioning of Pressure Switches Before Surveillance Testing

Preconditioning of Pressure Switches Before Surveillance Testing

ML120170120
Person / Time
Issue date:	08/29/2012
From:	Dudes L A, McGinty T J Division of Construction Inspection and Operational Programs, Division of Policy and Rulemaking
To:
Beaulieu, D P, NRR/DPR, 415-3243
References
IN-12-016
Download: ML120170120 (5)

ML120170120 August 29, 2012 NRC INFORMATION NOTICE 2012-16: PRECONDITIONING OF PRESSURE SWITCHES BEFORE SURVEILLANCE TESTING

ADDRESSEES

All holders of an operating license or construction permit for a nuclear power reactor under Title 10 of the Code of Federal Regulations (10 CFR) Part 50, "Domestic Licensing of Production and Utilization Facilities," except those who have permanently ceased operations and have certified that fuel has been permanently removed from the reactor vesse All holders of and applicants for a power reactor early site permit, combined license, standard design certification, standard design approval, or manufacturing license under 10 CFR Part 52,

"Licenses, Certifications, and Approvals for Nuclear Power Plants."

PURPOSE

The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice (IN) to inform addressees of recent examples of technical specification-required surveillance testing using procedures that unacceptably preconditioned pressure switches associated with various safety- related function The NRC expects that recipients will review the information for applicability to their facilities and consider actions, as appropriate, to avoid similar problem Suggestions contained in this IN are not NRC requirements; therefore, no specific action or written response is require

DESCRIPTION OF CIRCUMSTANCES

Monticello Nuclear Generating Plant On July 7, 2008, at the Monticello Nuclear Generating Plant, NRC inspectors observed the performance of a surveillance procedure for main steam line isolation instrumentation channel functional tests and calibration, which includes pressure switches that trip on low main steam line pressur The NRC inspectors found that the surveillance procedure unacceptably preconditioned the pressure switches by fully cycling them during test equipment installation, before obtaining the as-found trip setpoin Given that the pressure switch instrumentation line configuration at Monticello is designed with a test equipment connection point that consists of a cap only, with no adjacent isolation valve, the surveillance procedure tested the pressure switches as follows:

1. Isolate the pressure switch to be tested; 2. Uncap the test connection; 3. Connect the test equipment to the test connection; 4. Increase the pressure until the pressure switch resets and record the reset test data; 5. Bleed off the pressure until the pressure switch trips and record the as-found trip setpoint; 6. Remove the test equipment and restore the pressure switch to operatio This testing methodology caused the pressure switch and associated contacts to change their state when the system pressure was relieved in step 2; again when pressure was applied to reset the pressure switch in step 4; then a third time when the pressure was bled off to obtain the as-found trip setpoint in step Relieving system pressure to install test equipment results in the maximum net actuating force on the pressure switch diaphragm which exercises the pressure switch and potentially frees sticking contacts or mechanical bindin This calls into question the subsequent measurement of the as-found trip setpoint and the ability of the surveillance to verify the as-found operabilit The licensee similarly tested approximately 30 pressure switches at Monticello that are relied upon to initiate technical specification-related protective function The NRC inspectors discussed this surveillance with the NRC Office of Nuclear Reactor Regulation staff who issued Task Interface Agreement (TIA) 2009-006, "Unacceptable Preconditioning of Safety-Related Pressure Switches during Required Surveillance Testing at Monticello." This TIA concluded that the licensee's surveillance testing methodology constitutes unacceptable preconditioning of the pressure switch and, absent an engineering evaluation, the current surveillance testing methodology is unacceptable and must be changed so that the applicable pressure switches are not cycled before obtaining as-found trip setpoint dat Licensee corrective actions included developing an engineering evaluation of current surveillance testing methodology to justify the preconditioning as acceptabl Additional information is available in Monticello-NRC Integrated and Power Uprate Review Inspection Report 05000263/2009004, dated October 26, 2009, and can be found on the NRC's public Web site under Agencywide Documents Access and Management System (ADAMS) Accession No. ML092990580, and in TIA 2009-006, dated September 30, 2009 (ADAMS Accession No. ML092730349). Waterford Steam Electric Station, Unit 3 During a 19-month period ending October 27, 2008, Waterford Steam Electric Station, Unit 3 experienced five differential pressure switch failures in the containment vacuum relief system, a safety-related system that provides the means to prevent potential containment failures resulting from a vacuum conditio The first failure occurred during functional testing when a differential pressure switch failed to actuate on two attempts, and on the third attempt, it became unstuck and responded normally to the applied pressur After the first failure, the licensee identified that under normal conditions, the differential pressure switches experienced differential pressures that exceeded the calibration pressure of 150 percent of the design rang The licensee determined that the root cause of the five differential pressure switch failures was that design engineers did not perform a thorough evaluation of the operating conditions in 1987 as part of a technical specification change evaluatio The licensee suspected that preconditioning before 2008 had masked potential sticking during prior functional test The licensee assigned the human performance error related to preconditioning as a contributing caus Additional information is available in Waterford Steam Electric Station, Unit 3 - NRC Problem Identification and Resolution Inspection Report 05000382/2008007, dated December 11, 2008 (ADAMS Accession No. ML083500479).

BACKGROUND

Related NRC generic communications include the following:

• NRC IN 96-24, "Preconditioning of Molded-Case Circuit Breakers before Surveillance Testing," dated April 25, 1996 (ADAMS Accession No. ML031060110). This IN discusses the detrimental effect that preconditioning of molded-case circuit breakers could have on the diagnostic validity of surveillance test

• NRC IN 97-16, "Preconditioning of Plant Structures, Systems, and Components before American Society of Mechanical Engineers (ASME) Code Inservice Testing or Technical Specification Surveillance Testing," dated April 4, 1997 (ADAMS Accession No. ML031050353). This IN discusses the potential for maintenance activities performed before surveillance testing ("preconditioning" or "grooming") to adversely affect the validity of the surveillance test results for structures, systems, and components (SSCs) or equipmen

DISCUSSION

Criterion XI, "Test Control," of Appendix B, "Quality Assurance Criteria for Nuclear Power Plants," to 10 CFR Part 50 requires nuclear power plants to establish a test program to ensure that all testing required to demonstrate that SSCs will perform satisfactorily in service is performe This IN discusses test procedures that did not ensure pressure switches would operate satisfactorily in service because the test procedures unacceptably preconditioned the pressure switches by fully cycling them before obtaining an as-found trip setpoin NRC Inspection Manual, Part 9900 Technical Guidance, "Maintenance - Preconditioning of Structures, Systems, and Components before Determining Operability," defines unacceptable preconditioning as the alteration, variation, manipulation or adjustment of the physical condition of SSCs before or during technical specification surveillance testing or ASME code testing that will alter one or more of the SSC's operational parameters, which results in acceptable test result Such changes could mask the actual as-found condition of the SSC and possibly result in an inability to verify the operability of the SS In addition, unacceptable preconditioning could make it difficult to determine whether the SSC would perform its intended function during an event in which the SSC might be neede Preconditioning of pressure switches, as described above, could potentially mask existing conditions, such as sticking contacts, mechanical binding, or setpoint drif The pressure switch instrumentation line configuration at Monticello is designed with a test equipment connection point that consists of a cap only, with no adjacent isolation valv Therefore, to install test equipment, upstream isolation valves must be closed, which also isolates the pressure switch, causing it to depressurize when the cap is removed to connect the test equipmen However, the Monticello engineering evaluation listed three plants that are able to avoid pressure switch preconditioning because the plant is designed with a test equipment connection point that consists of a cap, as well as an adjacent isolation valve, which allows them to connect the test equipment and pressurize it to system pressure before opening the isolation valve, thus maintaining system pressure at the pressure switc These three plants avoid pressure switch preconditioning by using an isolation valve (original or installed through modification) at the test equipment connection point or by using an alternate connection point, such as a drain line that already had an installed isolation valv Criterion 21, "Protection System Reliability and Testability," of Appendix A, "General Design Criteria for Nuclear Power Plants," to 10 CFR Part 50 states, "The protection system shall be designed for high functional reliability and inservice testability commensurate with the safety functions to be performed." Preconditioning is a factor in inservice testability and, as such, requires consideration commensurate with the safety functions to be performe However, there is no explicit regulatory requirement to modify the plant to add an isolation valve to avoid preconditioning of pressure switche

CONTACT

This IN requires no specific action or written respons Please direct any questions about this matter to the technical contacts listed below or the appropriate Office of Nuclear Reactor Regulation (NRR) or Office of New Reactors project manage /RA by JLuehman for/ /RA/ Laura A. Dudes, Director Timothy J. McGinty, Director Division of Construction Inspection Division of Policy and Rulemaking and Operational Programs Office of Nuclear Reactor Regulation Office of New Reactors

Technical Contacts: Stephen Wyman, NRR Kenneth Riemer, Region III 301-415-3041 630-829-9628 E-mail: stephen.wyman@nrc.gov E-mail: kenneth.riemer@nrc.gov Note: NRC generic communications may be found on the NRC public Web site, http://www.nrc.gov, under NRC Librar The pressure switch instrumentation line configuration at Monticello is designed with a test equipment connection point that consists of a cap only, with no adjacent isolation valv Therefore, to install test equipment, upstream isolation valves must be closed, which also isolates the pressure switch, causing it to depressurize when the cap is removed to connect the test equipmen However, the Monticello engineering evaluation listed three plants that are able to avoid pressure switch preconditioning because the plant is designed with a test equipment connection point that consists of a cap, as well as an adjacent isolation valve, which allows them to connect the test equipment and pressurize it to system pressure before opening the isolation valve, thus maintaining system pressure at the pressure switc These three plants avoid pressure switch preconditioning by using an isolation valve (original or installed through modification) at the test equipment connection point or by using an alternate connection point, such as a drain line that already had an installed isolation valv Criterion 21, "Protection System Reliability and Testability," of Appendix A, "General Design Criteria for Nuclear Power Plants," to 10 CFR Part 50 states, "The protection system shall be designed for high functional reliability and inservice testability commensurate with the safety functions to be performed." Preconditioning is a factor in inservice testability and, as such, requires consideration commensurate with the safety functions to be performe However, there is no explicit regulatory requirement to modify the plant to add an isolation valve to avoid preconditioning of pressure switche

CONTACT

This IN requires no specific action or written respons Please direct any questions about this matter to the technical contacts listed below or the appropriate Office of Nuclear Reactor Regulation (NRR) or Office of New Reactors project manage /RA by JLuehman for/ /RA/ Laura A. Dudes, Director Timothy J. McGinty, Director Division of Construction Inspection Division of Policy and Rulemaking and Operational Programs Office of Nuclear Reactor Regulation Office of New Reactors

Technical Contacts: Stephen Wyman, NRR Kenneth Riemer, Region III 301-415-3041 630-829-9628 E-mail: stephen.wyman@nrc.gov E-mail: kenneth.riemer@nrc.gov Note: NRC generic communications may be found on the NRC public Web site, http://www.nrc.gov, under NRC Librar ADAMS Accession No.: ML120170120 TAC ME7680 OFFICE DRP/RIII Tech Editor EICB/NRR BC:DRP/RIII NAME CScott CHsu SWyman KRiemer DATE 1/18/12 06/26/12 e-mail 7/27/12 e-mail 1/18/12 OFFICE BC:EICB/NRR D:DE/NRR LA:PGCB:NRR NAME JThorp PHiland MCheok forCHawes DATE 7/27/12 e-mail 8/6/12 8/7/12 OFFICE PM:PGCB:NRR BC:PGCB:NRR D:DCIP/NRO D:DPR:NRR NAME DBeaulieu DPelton TAlexion forLDudes (JLuehman for) TMcGinty OFFICE 8/6/12 08/14/12 8/23/12 8/29/12 OFFICIAL RECORD COPY