Junk Plant Browns Ferry: Snowballing Back To Pre Pre 2011 Red Finding Attitude?

The "Safety Relief Valve" green finding is grossly not appropriate. It tells me the industry still does not have control of the SRV reliability...

05000259/2016003, 05000260/2016003, 05000296/2016003; 07/01/2016–09/30/2016; Browns Ferry Nuclear Plant, Units 1, 2 and 3; (Equipment Alignment, Fire Protection, Licensed Operator Requalification and Performance, Operability Determinations and Functionality Assessment, Problem Identification and Resolution, Follow-up of Events and Notices of Enforcement Discretion).  

The report covered a three-month period of inspection by resident and regional inspectors.  Six non-cited violations (NCVs) and one licensee-identified Severity Level IV NCV were identified.  The significance of inspection findings is indicated by their color (Green, White, Yellow, Red) using Inspection Manual Chapter (IMC) 0609, "Significance Determination Process" (SDP) dated April 29, 2015.  Cross-cutting aspects are determined using IMC 0310, “Components Within the Cross Cutting Areas” dated December 4, 2014.  All violations of NRC requirements are dispositioned in accordance with the NRC’s Enforcement Policy dated August 1, 2016.  The NRC's program for overseeing the safe operation of commercial nuclear power reactors is described in NUREG-1649, "Reactor Oversight Process," Revision 6.

Cornerstone:  Initiating Events

• Green.  An NRC identified non-cited violation (NCV) of Renewed License Number DPR-52, condition 2.C.(14) was identified for the licensee’s failure to implement and maintain in effect all provisions of the approved fire protection program that comply with 10 CFR 50.48(a) and 10 CFR 50.48(c).  Specifically, the licensee failed to establish a compensatory roving fire watch, within 1 hour of rendering the spray systems that protect the Main 500kV transformer 2B and Unit Service Station Transformer (USST) 2B nonfunctional.  As an immediate corrective action, the licensee established the required fire watch and entered the violation into the licensee's corrective action program as CR 1203990.

The performance deficiency was more-than-minor because it was associated with the protection against external factors (Fire) attribute of the Initiating Events cornerstone and adversely affected the cornerstone objective to limit the likelihood of events that upset plant stability and challenge critical safety functions during shutdown as well as power operations.  This finding was evaluated in accordance with NRC IMC 0609, Appendix F, Fire Protection Significance Determination Process, dated September 20, 2013.   The inspectors determined the finding was Green because the finding did not affect the reactor’s ability to reach and maintain the fuel in a safe and stable condition.  The inspectors determined that the finding had a cross-cutting aspect in the Human Performance area of Change Management (H.3) because leaders failed to clearly establish the control room's ownership of Fire Protection Requirements Manual (FPRM) usage as part of the NFPA 805 transition. (Section 1R05)

• Green.  A self-revealing Non-cited Violation (NCV) of Technical Specification (TS) 5.4.1.d, Fire Protection Program Implementation, was identified for the licensee’s failure to maintain the integrity of the high pressure fire protection piping.

The licensee’s immediate corrective action was to isolate the leak and entered this issue into their corrective action program as CR 1102016. This performance deficiency was more than minor because it adversely affected the Initiating Events cornerstone objective of protection against external factors such as fire.  Specifically, the high pressure fire protection system piping was unable to maintain the required pressure during a system demand.  This finding was evaluated in accordance with NRC IMC 0609, Appendix F, Fire Protection Significance Determination Process, dated September 20, 2013.   The inspectors determined the finding was Green because the finding did not affect the reactor’s ability to reach and maintain the fuel in a safe and stable condition.  The inspectors assigned a cross cutting aspect of Operating Experience because there was a similar occurrence of a fire protection piping break at Browns Ferry caused by heavy construction vehicle traffic in 2014 (P.5).  (Section 1R15)

Cornerstone:  Mitigating Systems

• Green.  An NRC identified non-cited violation (NCV) of 10 CFR Part 50, Appendix B, Criterion V, "Instructions, Procedures, and Drawings" was identified for the licensee's failure to ensure sufficient clearance was available following a replacement of the Core Spray minimum flow valve actuator motors.  Modifications personnel failed to identify that the resulting clearances were less than permitted by TVA procedure MAI-4.10 “Piping Clearance Instruction” and that they required an engineering evaluation.  As an immediate corrective action, the licensee cut away portions of floor grating to establish an acceptable amount of clearance for the valves.  The violation was entered into the licensee's corrective action program as CRs 1161330 and 1169591.

The performance deficiency was more-than-minor because it was associated with the Design Control attribute of the Mitigating Systems cornerstone and adversely affected the cornerstone objective to ensure the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences (i.e. core damage).  Specifically, the inadequate clearance resulted in an analysis showing that ASME code allowable design stresses would be exceeded under accident conditions.  Exceeding design stresses created a reasonable doubt on the operability and reliability of loop 2 of the Core Spray system for Units 2 and 3.  This finding was evaluated in accordance with NRC IMC 0609, Appendix A, Exhibit 2, Mitigating Systems Screening Questions, dated June 19, 2012.  The inspectors determined the finding was Green because the finding was a deficiency affecting the qualification of the Core Spray loop.  Operability was maintained because an engineering evaluation demonstrated, through the use of alternative analytical methods, that the piping stress criteria in Appendix F of Section III of the ASME Boiler and Pressure Vessel Code was satisfied and that the stresses in the valve would not cause distortions of a magnitude that would prevent operation of the valve.  The inspectors did not assign a crosscutting aspect because the performance deficiency was not reflective of present licensee performance since it occurred more than three years ago.  (Section 1R04)

• Green.  An NRC identified NCV of 10 CFR Part 50, Appendix B, Criterion XVI, "Corrective Action" was identified for the licensee's failure to promptly identify conditions adverse to quality associated with the prompt determination of operability (PDO) for CR 1061051.  As an immediate corrective action, the licensee entered the violation into the licensee's corrective action program as CR 1193943.  

The performance deficiency was more-than-minor because it was associated with the Human Performance attribute of the Mitigating Systems cornerstone and adversely affected the cornerstone objective to ensure the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences (i.e. core damage).  Specifically, had the deficiencies in the PDO been identified, engineers would have recognized that the resulting stresses exceeded allowable design stresses in the valve vendor's weak link analysis and approached the yield strength of the stem material.  As a result, the practice was permitted to continue until the valve stem catastrophically failed. This finding was evaluated in accordance with NRC IMC 0609, Appendix A, Exhibit 2, Mitigating Systems Screening Questions, dated June 19, 2012.  The inspectors determined the finding required a detailed risk evaluation because the finding represented a loss of system function and/or function for the high pressure coolant injection (HPCI) system.  Senior Reactor Analyst performed a detailed risk evaluation using the Standardized Plant Analysis Risk (SPAR) model for Browns Ferry Unit 1.   The HPCI system was modeled as unavailable for a conservative exposure period of 7 days.  The delta CDF estimate was less than 1E-6/yr range, which represents a finding of very low safety significance (Green).  The dominant core damage sequence was an inadvertent open relief valve, failure of HPCI, and failure to depressurize.   The availability of additional injection sources helped minimize the risk significance. The inspectors determined that the finding had a cross-cutting aspect in the Design Margins area of the Human Performance aspect (H.6), because engineers did not demonstrate the behavior of carefully guarding margins to ensure that safety related equipment was operated and maintained within design margins.  (Section 4OA2.5)

• Green. A self-revealing NCV of TS 3.5.1, Emergency Core Cooling Systems, Condition E in that an inoperable Automatic Depressurization System (ADS) valve function existed longer than the allowed technical specification time.  The licensee implemented corrective actions by declaring the affected component inoperable per technical specifications, identified preventative maintenance procedures as the cause, repaired the breaker stabs to restore the circuit, and re-performed the surveillance to establish operability.  This issue was entered into the licensee's corrective action program as CR 1161991.

The performance deficiency was more than minor because it adversely affected the Mitigating Systems cornerstone attribute of equipment performance.  Specifically, one of the TS required ADS valves opening capability was not fully qualified.  Using NRC IMC 0609, Appendix A, Exhibit 2, Mitigating Systems Screening Questions, dated June 19, 2012,  the inspectors determined the finding was of very low safety significance (Green) because the finding did not represent a loss of system safety function as the other five Main Steam Relief Valve (MSRV) ADS functions were still available.  The inspectors assigned a cross cutting aspect of Identification since the licensee had not taken sufficient post maintenance actions to verify function of the alternate breaker for the ADS valve 3-PCV-001-0022. (P.1) (Section 4OA3.1)

• Green.  A self-revealing NCV of TS 3.4.3, Safety Relief Valves was identified for two required MSRVs being inoperable longer than the allowed outage time and follow on action completion time.  The licensee’s immediate corrective action was to replace all Unit 3 MSRV pilot valves prior to the completion of the refueling outage.  This issue was entered into the licensee’s corrective action program as CR 1157981. 

The performance deficiency was more than minor because it adversely affected the Mitigating Systems cornerstone attribute of equipment performance.  Specifically, two required MSRVs were not able to lift within their required pressure band.  This performance deficiency was screened using NRC IMC 0609, Appendix A, Exhibit 2, Mitigating Systems Screening Questions, dated June 19, 2012.   This performance deficiency screens to Green because although the system was inoperable for greater than its allowed outage time and follow on action completion time, the system maintained its safety function.  The inspectors assigned a cross cutting aspect of Resolution since the licensee has not taken sufficient corrective actions to address the continued  out of tolerance lift results caused by corrosion bonding of the MSRV pilot valve seats. (P.3) (Section 4OA3.3)   A violation of Severity Level IV that was identified by the licensee has been reviewed by the NRC.  .  Corrective Actions taken or planned by the licensee have been entered in the licensee’s corrective action program.   The violation and corrective action tracking numbers are listed in Section 4OA7 of this report.