05000482/FIN-2014008-03
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Finding | |
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| Title | Licensee-Identified Violation |
| Description | On October 9, 2013, Licensee Event Report 05000482/2013-009 described an unanalyzed condition wherein a fire in fire areas containing certain unprotected, shunt, direct current ammeter circuits could result in secondary fires outside the initial fire area. This condition can occur only under specific circuit fault conditions wherein a fire causes a short to ground on cables associated with the DC ammeters, concurrent with a short to ground on a safety-related 125V DC circuit on the negative side of the same battery source. This condition is known as a ground equivalent hot short. The ammeter circuits are not overcurrent protected and, consequentially, could overheat and ignite anywhere along the route of the associated ammeter cables. The licensee determined in a cause analysis and extent of condition review that the only affected circuits were the eight DC ammeters associated with the safety-related 125V DC batteries and battery chargers. The team determined the routing of the affected cables involved five fire areas. The five fire areas were switchboard rooms/battery rooms FA C16, locked cable chase FA C18, locked cable chase FA C24, lower cable spreading room FA C21, and control room FA C27. The team evaluated the various scenarios of where the primary fire could start and where the secondary fire(s) could develop. The team determined that there were no normal ignition sources (electrical cabinets or equipment) in the two locked cable chases or the lower cable spreading room. Transient combustibles in these areas were strictly controlled by Procedure AP 10-102, "Control of Combustible Materials," Revision 18, and the cable chases are protected by a wet pipe automatic sprinkler system and automatic smoke detection alarms in the main control room. A fire in the switchboard rooms/battery room FA C16 is the area where the ammeter shunts are located and a primary fire there would not result in a secondary fire outside this area. The only remaining fire area to evaluate was the control room FA C27, which had a low combustible loading, all cables entering the control room are IEEE 383 rated, and the cables and cable trenches were protected by an automatic halon extinguishing system and automatic smoke detectors. While a primary fire in the control room could cause a secondary fire to develop along the cable route, the team determined that in the event that a secondary fire did occur that the impact would be limited to the same train as the primary fire. Therefore, the redundant post-fire safe shutdown success path would be unaffected by the fire. License Condition 2.C(5)(a) specifies, in part, that the licensee implement and maintain in effect all provisions of the approved fire protection program as described in the Standardized Nuclear Power Plant System Final Safety Analysis Report through Revision 17, the Wolf Creek site addendum through Revision 15, and as approved in the Safety Evaluation Report through Supplement 5, Amendment No. 191, Amendment No. 193, and Amendment No 205. Section 4.4.1.1 of the Fire Hazards Analysis states that "only one fire is postulated to occur at any one time and multiple fires are not postulated." Contrary to the above, since initial construction until November 6, 2014, the licensee failed to implement the fire protection program that ensured only one fire will occur at one time. Specifically, the licensee failed to ensure that direct current ammeter circuits were properly protected to prevent secondary fires from initiating in other areas of the plant. The performance deficiency was more than minor because it was associated with the protection against external factors attribute of the Mitigating Systems Cornerstone and it adversely affected the cornerstone objective of ensuring the availability, reliability, and capability of systems that respond to initiating events (fire) to prevent undesirable consequences. The finding was evaluated for safety significance using NRC Inspection Manual Chapter 0609, Appendix F, "Fire Protection Significance Determination Process," dated September 20, 2013. Since the finding was related to the ability to achieve safe shutdown and safe shutdown would be unaffected, the inspectors determined the finding had a very low safety significance (Green). Specifically, no secondary fires resulting from a primary fire could prevent the reactor from achieving safe shutdown. The licensee documented this issue in their corrective action program as Condition Report 00074959. This violation is also discussed in Section 4OA3. |
| Site: | Wolf Creek  |
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| Report | IR 05000482/2014008 Section 4OA7 |
| Date counted | Dec 31, 2014 (2014Q4) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | Licensee-identified |
| Inspection Procedure: | |
| Inspectors (proximate) | G Pick G Werner J Mateychick J Watkins S Alferink |
| Violation of: | License Condition - Fire Protection License Condition |
| INPO aspect | |
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Finding - Wolf Creek - IR 05000482/2014008 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Wolf Creek) @ 2014Q4
Self-Identified List (Wolf Creek)
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