05000348/FIN-2014005-04
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Finding | |
|---|---|
| Title | Unfused DC Ammeter Circuits Result in an Unanalyzed Condition |
| Description | On February 14, 2014, the licensee submitted an LER documenting the discovery of a condition of non-compliance with the sites fire protection program (FPP). This condition could prevent operators from achieving and maintaining safe shutdown (SSD) of the plant, in the case of a postulated fire. The inspectors performed a detailed review of the information related to the LER. Inspectors reviewed documents, and discussed the event with plant personnel to gain an understanding of the event. The inspectors assessed the licensees compensatory measures and corrective actions to determine if they were adequate. The licensee identified a non-compliance with Farley Operating License Condition 2.C(4) for Unit 1, and 2.C(6) for Unit 2, for the failure to meet requirements for protection of associated circuits. Specifically, the licensee failed to provide short circuit protection for safety-related and nonsafety-related associated circuits. As a result, a postulated fire could result in a secondary fire in another fire area. The secondary fire could adversely affect SSD capability. On December 13, 2013, the licensee conducted a review of industry operating experience (OE) related to unfused DC ammeter circuits. The review determined that certain DC ammeter circuits at Farley lacked short circuit protection. Because these circuits lack short circuit protection, a postulated fire in a fire area containing DC ammeter circuit cabling could result in concurrent shorts in the circuit. Due to the lack of short circuit protection, the resultant excessive current flow in the DC ammeter cable could result in a secondary fire in another fire area. The secondary fire could adversely affect SSD equipment or cables for SSD equipment, and thus, adversely affect SSD capability. Multiple fire areas in the Turbine Building, Service Water Structure, and Auxiliary Building are potentially affected. Section 9B.1.2 of Appendix 9B of the licensees FSAR defines associated circuits of concern as those cables that have a physical separation less than that required by 10 CFR 50 Appendix R, Section III.G.2, and have a common enclosure (e.g., raceway, panel, junction) with the shutdown cables (redundant and alternative) and are not electrically protected by circuit breakers, fuses or similar devices. Section 9B.3 provides the basis for the review that a fire would not negate the safe shutdown of the plant. For associated circuits that share common enclosures with safe shutdown circuits, Section 9B.3.J.4.b(2) states, in part, Nonsafe shutdown circuits as well as safe shutdown circuits are provided with short circuit protection. Nonsafe shutdown circuits which share raceway or other enclosures with safe shutdown circuits are not considered as a potential fire source because short circuit protection is provided. The licensees OE review determined that certain DC ammeter circuits were not provided with short circuit protection, and thus, invalidates the SSD evaluation bases stated in Section 9B.3 of the FSAR. Upon discovery, the licensee entered the condition into the corrective action program (CRs 723304 and 746046), and implemented appropriate compensatory measures in the form of roving fire watches for the affected areas. Plant modifications are currently being developed to provide short circuit protection for the affected DC ammeter circuitry. The licensees failure to provide short circuit protection for DC ammeter circuits is a PD. This PD is more than minor because it is associated with reactor safety Mitigating System cornerstone attribute of Protection Against External Events (i.e., fire). Specifically, not providing circuit protection for associated circuits affects the reactor safety mitigating systems cornerstone objective of ensuring the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. Because this issue relates to fire protection, and this noncompliance was identified as a part of the sites transition to NFPA 805, this issue is being dispositioned in accordance with Section 9.1, Enforcement Discretion for Certain Fire Protection Issues (10 CFR 50.48) of the NRC Enforcement Policy. In order to verify that this non-compliance was not associated with a finding of high safety significance (Red), a bounding phase 3 SDP risk analysis was performed by a regional SRA using the guidance from NRC Inspection Manual Chapter 0609 Appendix F and NUREG/CR 6850 revision 0 and Supplement 1. The analysis used inputs from the licensees NFPA 805 project for ignition frequency and cable routing data. The major analysis assumptions were: a one year exposure period, two proper DC polarity hot shorts required to achieve the high current conditions for secondary fires, and all ignition sources for each affected fire zone assumed to damage the ammeter cables. Based on this bounding risk analysis, the regional SRA determined that this performance deficiency resulted in a CDF increase for each Farley Unit 1 and 2 of less than 1E-4/year (i.e., less than Red). The licensee also performed a risk assessment using their Farley fire probabilistic risk assessment model which also produced a result <1E-4 for each Farley unit. No cross-cutting aspect was applicable to this performance deficiency because this finding was not indicative of current licensee performance. Enforcement. Farley Operating License Condition 2.C(4) for Unit 1, and 2.C(6) for Unit 2 states, in part, Southern Nuclear shall implement and maintain in effect all provisions of the approved fire protection program as described in the Final Safety Analysis Report for the facility, which implements the fire protection requirements of 10 CFR 50.48 and 10 CFR 50 Appendix R. Farleys Fire Protection Program is detailed in Appendix 9B of the FSAR. For associated circuits that share common enclosures with safe shutdown circuits Section 9B.3.J.4.b(2) of Appendix 9B of the FSAR states, in part, Nonsafe shutdown circuits as well as safe shutdown circuits are provided with short circuit protection. Non-safety shutdown circuits, which share raceway or other enclosures with safe shutdown circuits, were not considered as a potential fire source because short circuit protection was provided. Contrary to the above, for associated circuits that share common enclosures with safe shutdown circuits, the licensee failed to provide short circuit protection for associated circuits, in accordance with the FSAR. Specifically, on December 16, 2013, the licensee discovered that circuits for certain DC ammeters did not contain any form of short circuit protection. This condition has existed since original plant design and construction. Upon discovery, the licensee entered the condition into the corrective action program (CRs 723304 and 746046), and implemented appropriate compensatory measures in the form of roving fire watches for the affected areas. This finding affected 10 CFR 50.48, was identified by the licensee, and is a violation of NRC requirements. The licensee has committed to adopt NFPA 805 and change their fire protection licensing bases to comply with 10 CFR 50.48(c), the licensees license amendment request to transition to NFPA 805 is still under NRC review, and the noncompliance is not associated with a finding of high safety significance. Therefore, the NRC is exercising enforcement discretion in accordance with the NRC Enforcement Policy, Section 9.1, Enforcement Discretion for Certain Fire Protection Issues (10 CFR 50.48) and Inspection Manual Chapter 0305. This condition was entered into the licensees corrective action program and immediate corrective actions and compensatory measures were taken. |
| Site: | Farley  |
|---|---|
| Report | IR 05000348/2014005 Section 4OA3 |
| Date counted | Dec 31, 2014 (2014Q4) |
| Type: | Violation: Severity level Enforcement Discretion |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71153 |
| Inspectors (proximate) | W Pursley A Vargas B Caballero C Dykes D Mas J Montgomery K Miller M Coursey M Franke P Niebaum R Kellner W Loo |
| Violation of: | 10 CFR 50.48 10 CFR 50 Appendix R License Condition - Fire Protection License Condition |
| INPO aspect | |
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Finding - Farley - IR 05000348/2014005 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Farley) @ 2014Q4
Self-Identified List (Farley)
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