Information Notice 2009-03, Solid State Protection System Card Failure Results In Spurious Safety Injection And Reactor Trip
| ML083080368 | |
| Person / Time | |
|---|---|
| Issue date: | 03/11/2009 |
| Revision: | 0 |
| From: | Dorman D H, McGinty T J NRC/NMSS/FCSS, Division of Policy and Rulemaking |
| To: | |
| C HAWES | |
| References | |
| IN-09-03 | |
| Download: ML083080368 (4) | |
ML083080368 March 11, 2009 NRC INFORMATION NOTICE 2009-03: SOLID STATE PROTECTION SYSTEM CARD FAILURE RESULTS IN SPURIOUS SAFETY INJECTION ACTUATION AND REACTOR TRIP
ADDRESSEES
All holders of operating licenses for nuclear power reactors, except those who have permanently ceased operations and who have certified that fuel has been permanently removed from the reactor vessel, as well as licensees and certificate holders of nuclear fuel cycle facilitie
PURPOSE
The Nuclear Regulatory Commission (NRC) is issuing this information notice (IN) to inform addressees of an event at North Anna Power Station, Unit 2, involving a solid state protection system (SSPS) card failure that resulted in a spurious actuation of the "B" train safety injection (SI) and a reactor tri 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
On June 29, 2007, North Anna Power Station, Unit 2, experienced a spurious actuation of the
"B" train SI caused by a Zener diode failure on a "B" train SSPS car The spurious SI caused main feedwater system isolation, a turbine trip, and a reactor trip, along with emergency core cooling system water flow into the reactor coolant system (RCS). Because of the nature of the failure, the licensee could not reset from the control room the actuation signal for some "B" train SI equipment, which resulted in overfilling the pressurizer and multiple actuations of a pressurizer power-operated relief valve (PORV) to limit RCS pressur RCS inventory from the PORV discharged to the pressurizer relief tank (PRT), rupturing one of the PRT rupture disks, which allowed RCS water to reach the containment basemen Plant personnel successfully defeated the malfunctioning SI logic train and terminated the S The licensee reset and deenergized the malfunctioning "B" train SI logic by placing the SSPS into TEST, locally delatching some relays, and deenergizing the circuit by pulling fuse Procedures did not address manually resetting the partial SI in the presence of the SSPS card failur The SSPS card failure was mitigated by securing and resetting the SI signal using operator knowledge and the information in several different procedures that were not specifically developed to address the inability to reset a SI signa The licensee determined that the most probable cause of the diode failure on the "B" train SSPS card was either age-related degradation or a random failur The diode failed as a short circuit actuating certain "B" train master relays and resulting in the invalid actuation of the "B" train S This same failure also prevented "B" train SI from being reset from the control room, which required operations and maintenance staff to take local action A contributing cause of the failure was that the licensee had not implemented a program to detect and correct age-related degradation of the SSPS card Licensee corrective actions for this event included (1) establishing a preventive maintenance program to remove, test, and repair these cards, along with cards in other sensitive systems, at periodic intervals, (2) developing an abnormal operating procedure to reset SI locally, and (3) implementing life-cycle management for SSPS card Additional information is available in the document "North Anna Power Station - NRC Special Inspection Report 05000339/2007009," dated August 27, 2007, which can be found on the NRC's public Web site in the Agencywide Documents Access and Management System (ADAMS), under Accession No. ML07241035 See also North Anna Power Station, Unit 2, Licensee Event Report 50-339/2007-003-00, dated August 27, 2007 (ADAMS Accession No. ML072480671).
DISCUSSION
The SSPS card failure at North Anna resulted in a complicated reactor trip response that required manual actions outside the control room to secure SI flow and restore other equipment that actuated from the signa This event revealed the lack of procedure guidance to reset the SI after SSPS card failure, which was an obstacle to mitigating the even Power reactor licensees rely on circuit cards such as SSPS cards being operable in systems as specified in technical specification Industry operating experience shows that circuit cards are susceptible to age-related component failure Power reactor licensees can address this by establishing periodic preventive maintenance of circuit card Similarly, licensees and certificate holders of fuel cycle facilities are required to perform inspection, testing, calibration, and maintenance of certain systems and components as delineated in applicable sections of Title 10 of the Code of Federal Regulations, Parts 70 and 7
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 project manager in the Office of Nuclear Reactor Regulation (NRR). /RA/ /RA/
Timothy J. McGinty, Director Daniel H. Dorman, Director Division of Policy and Rulemaking Division of Fuel Cycle Safety and Safeguards Office of Nuclear Reactor Regulation Office of Nuclear Material Safety and Safeguards Technical Contacts: Jim Dodson, Region II Subinoy Mazumdar, NRR 404-562-4655 301-415-2904 e-mail: Jim.Dodson@nrc.gov e-mail: Subinoy.Mazumdar@nrc.gov Note: NRC generic communications may be found on the NRC public Web site, http://www.nrc.gov, under Electronic Reading Room/Document Collection
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 project manager in the Office of Nuclear Reactor Regulation (NRR). /RA/ /RA/
Timothy J. McGinty, Director Daniel H. Dorman, Director Division of Policy and Rulemaking Division of Fuel Cycle Safety and Safeguards Office of Nuclear Reactor Regulation Office of Nuclear Material Safety and Safeguards Technical Contacts: Jim Dodson, Region II Subinoy Mazumdar, NRR 404-562-4655 301-415-2904 e-mail: Jim.Dodson@nrc.gov e-mail: Subinoy.Mazumdar@nrc.gov Note: NRC generic communications may be found on the NRC public Web site, http://www.nrc.gov, under Electronic Reading Room/Document Collection ADAMS Accession Number: ML083080368 OFFICE R2:BC:RPB5 TECH EDITOREICB:DEBC:EICB:DE NAME JDodson e-mail HSpencer SMazumdar WKemper DATE 10/30/2008 11/10/2008 01/29/2009 1/29/2009 OFFICE D:DE BC:RER2D:FCSS NAME PHiland RAuluck DDorman DATE 1/29/2009 11/05/2008 03/02/2009 OFFICE PGCB:DPR PGCB:DPRBC:PGCB:DPRD:DPR NAME DBeaulieu CHawes MMurphy TMcGinty DATE 2/3/2009 2/17/2009 2/18/2009 03/11/2009 OFFICIAL RECORD COPY