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| Start date | Reporting criterion | Title | Event description | System | LER | |
|---|---|---|---|---|---|---|
| ENS 49914 | 13 March 2014 20:30:00 | 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | Postulated Hot Short Fire Event That Could Adversely Impact Safe Shutdown Equipment | A review of industry Operating Experience identified that there were unprotected DC control circuits for non safety-related DC motors which are routed from the turbine building to other separate fire areas. Fuses used to protect the motor power conductors appear to be inadequate to protect the control conductors. The concern is that under fire safe shutdown conditions, it is postulated that a fire in one area can cause short circuits potentially resulting in secondary fires or cable failures in other fire areas where the cables are routed. The secondary fires or cable failures are outside the assumptions of the 10 CFR 50 Appendix R Safe Shutdown Analysis. This condition is reportable as an 8-hour ENS report in accordance with 10 CFR 50.72(b)(3)(ii)(B) as an unanalyzed condition. Compensatory measures (fire watches) have been implemented for affected areas of the plant. The NRC Resident Inspector has been notified. . | ||
| ENS 49374 | 20 September 2013 20:00:00 | 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | Potential Design Basis Flooding Issues Related to Battery Room Wall Penetrations and Cable Vault Floor Drains | On 9/20/2013 at 1600 EDT, R.E. Ginna Nuclear Power Plant determined that there was a potential for flooding of both battery rooms during a design basis flood due to unqualified wall penetration material and partially blocked cable vault floor drains. Testing of underground cable vault drain lines failed to demonstrate that they could pass the required flow due to debris accumulation. The penetrations are below grade and approximately five feet above the bottom of the vault floor. During a design basis flood, water could flow through the holes in the vault manhole covers and fill up the vaults to the level of the penetrations. Since the penetration barriers do not appear to be qualified for flooding, leakage into Battery Room B could be expected. Battery Room A and Battery Room B have a normally closed emergency fire door between them that allows water to pass under the door into Battery Room A where a sump pump exists. It is not currently known if the sump pump capacity would have been able to mitigate flooding of both battery rooms. The discovery of this condition is being reported as an unanalyzed condition as defined by 10 CFR 50.72(b)(3)(ii)(B). The 125VDC system is currently Operable. Current weather forecasts do not predict the conditions necessary for flooding. Additionally, compensatory measures have been implemented to provide barriers to water entry into the vault manholes until corrective actions are implemented. The NRC Resident Inspector has been notified of this condition | ||
| ENS 48918 | 12 April 2013 14:10:00 | 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | Unanalyzed Condition - Missing Backflow Preventer | On 4/12/2013 at 1010 EDT, it was determined that a floor drain line between the Turbine Building and Intermediate Building did not have a backflow preventer as expected. Backflow protection is provided to prevent the possible spread of a fire via the drain system. The Turbine Building and the Intermediate Building are considered two different fire areas within the scope of the fire protection program. The discovery of this condition is being reported as an unanalyzed condition as defined by 10CFR50.72(b)(3)(ii)(B). In accordance with the Technical Requirements Manual, an hourly fire watch inspection and fire detector operability verification have been established until an equivalent level of protection is provided or until permanent corrective actions can be implemented. The NRC Resident Inspector has been notified. | ||
| ENS 48333 | 21 September 2012 18:00:00 | 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | Unanalyzed Condition Identified in Appendix R Fire Scenario | On September 21, 2012, a condition was identified where hydrogen may become entrained in the charging pump suction after the credited pump is restarted as part of the alternate shutdown procedure for the Auxiliary Building basement and mezzanine levels. An air operated valve separates the Volume Control Tank (VCT) from the charging pump suction and this valve fails open on loss of air or power caused by the postulated fire. The alternate flow path from the Refueling Water Storage Tank (RWST) fails closed on a loss of air or power. A manual valve is provided to bypass this closed valve. However, due to hydrogen pressure in the VCT and the potential for significant pressure losses in the piping from the RWST to the charging pump suction, insufficient elevation head exists in the RWST to ensure that hydrogen will not become entrained. If this condition is left unmitigated, the credited charging pump is assumed to fail. Due to the location of the postulated fire and its impact on equipment and cables, no other inventory makeup sources are credited. Compensatory Measures have been implemented as follows: 1. All fire detection and suppression systems in the Appendix R fire zones have been verified functional. 2. All Hot Work in the area has been suspended. 3. Continuous Fire Watch has been posted in the Appendix R fire zone. 4. Combustion engine powered vehicles are restricted from entering the Auxiliary Building. 5. Within 24 hours remove all non-attended transient combustible materials from Appendix R fire zones. The NRC Resident Inspector has been notified. * * * RETRACTION FROM REISNER TO SNYDER ON 9/28/12 AT 1415 EDT * * * This is a retraction of ENS report 48333 that was submitted at 2028 EDT on Friday, September 21 , 2012. A 10 CFR 50.72(b)(3)(ii)(B) ENS notification was made due to a condition that was identified where hydrogen may become entrained in the charging pump suction after the credited pump is restarted as part of the alternate shutdown procedure in the event of a fire in the Auxiliary Building basement and mezzanine levels. A subsequent engineering evaluation calculated the amount of gas that will be entrained into the charging pump suction flow and the duration of the entrainment. This evaluation demonstrates that for the most limiting Appendix R scenario that the charging pump will entrain a minimal amount of gas for a short duration, and is unaffected by this condition. Inventory control for the reactor coolant system is maintained throughout the scenario. Based on the above information the 'Unanalyzed Condition' ENS notification made on September 21, 2012 is being retracted. The licensee notified the NRC Resident Inspector. Notified R1DO (Bellamy). | Reactor Coolant System | |
| ENS 47167 | 18 August 2011 14:00:00 | 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | Unanalyzed Condition That Could Potentially Impact Both Trains of 480V Safeguards Buses | During NFPA-805 Fire PRA (Probabilistic Risk Assessment) model development, Ginna Station identified a non-compliance with the Appendix R requirement to maintain one train of systems that are necessary to achieve and maintain hot shutdown and remain free from fire damage. A fire in the Turbine Building could cause a loss of 4160V power to the 480V safeguards buses while disabling control power to the 480V bus normal supply breakers and preventing both diesel generator output breakers from closing. Since the non-safety related 4160V buses are located in the same area of the turbine building, this could potentially impact both trains of AC power. This was determined to be an unanalyzed condition reportable in accordance with 10CFR50.72(b)(3)(ii)(B). Compensatory measures have been established to provide interim guidance to identify the condition and locally trip the bus supply breaker prior to closing the diesel generator output breaker. The licensee has notified the NRC Resident Inspector. | ||
| ENS 46735 | 6 April 2011 19:30:00 | 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | Degraded Fire Barrier | During walk downs for a planned site modification on April 6, 2011 at 1530 EDT, two degraded fire barrier seals were identified in the wall between the Auxiliary Building Basement and the Charging Pump Room. The wall is listed as an Appendix R wall between Fire Area (FA) ABBM and FA CHG. The wall separates redundant safe shutdown equipment. Two cylindrical six inch penetrations through the wall did not contain the required material to conform to a 3-hour fire rated barrier. This has been identified as a missing fire barrier such that the required degree of separation for redundant safe shutdown trains is lacking. A fire watch was established as a compensatory measure on 4/6/11. The discovery of this non-compliance is being reported as an unanalyzed condition as defined by 10 CFR 50.72(b)(3)(ii)(B). The NRC Resident Inspector has been notified of this event.
The purpose of this report is to retract the event discussed in Emergency Notification System report #46735 submitted on April 6th, 2011. The ENS notification reported an inadequate fire barrier penetration seal discovered on April 6th, 2011 when maintenance inspected the penetration in preparation for a modification. Initial investigation concluded that the fire barrier penetration seal between the Charging Pump room and Auxiliary Building Basement was inoperable because there was inadequate seal material to provide the required three hour barrier rating. It appeared that when looking in the penetration sleeve that a fire board from the opposite room was visible and no foam material was present. Subsequently, an engineering review of the penetration has been completed. The review determined that a minimum of 8 inches of foam is required to maintain a 3-hour rating. Engineering identified that the design also requires a fire board on each side of the foam. Upon measurement it was confirmed that at least 11 inches of the penetration was filled, with a fire board on each side. Based on these measurements, the fire barrier met design requirements and was operable. The individuals performing the initial investigation did not recognize the thickness of the wall. On April 7th, Maintenance proceeded to penetrate the fire barrier for the modification and it was confirmed that foam was behind the fire board. With a 24 inch thick wall, a large portion at the penetration sleeve can be void of material and still meet the 3 hour rating. As such, the April 6th, 2011 event is being retracted. The licensee notified the NRC Resident Inspector. Notified the R1DO (Caruso) | ||
| ENS 42831 | 7 September 2006 02:00:00 | 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | Historical Unanalyzed Condition Identified | On September 6, 2006, an unanalyzed condition was identified during the review of a previous issue discovered on April 18, 2005. The current review was being performed in response to NRC inspection questions regarding the previous issue. On April 18, 2005, while at 100% power, both trains of standby auxiliary feed water (AFW) flow transmitters were found isolated. The plant had entered Mode 3 on April 8, 2005 for a routine startup after a refueling outage. The transmitters were restored to their normal operational alignment promptly when the condition was identified. These two standby AFW trains are in addition to the typical safety-related AFW motor driven pump trains and turbine driven pump train, for a total of five safety-related AFW pump trains at the site. The two standby AFW trains are designed to address a high energy line break (HELB) event which would disable the other three AFW pump trains. Both of the flow transmitters perform several functions including control room indication of standby AFW discharge flow and valve control functions for the pump discharge valve and pump recirculation valve. With the flow transmitters isolated in both trains of the standby AFW system, an unanalyzed condition existed due to the following: During a postulated HELB, the inoperable flow transmitters would result in the recirculation valve and the pump discharge valve being both full open. Under a steam generator low pressure condition, (as a result of the HELB) with flow through both the open discharge valve and the open recirculation valve, the pump would be in a high flow rate condition until the steam generator level was recovered. The operators would have no indication of flow through the discharge valves and would be operating the system based on steam generator level. During the time assumed for the intact steam generator level recovery, the breaker for the pump motor could be expected to exceed it's time delayed current protection setpoint and trip the motor, preventing delivery of feed water to the steam generator. Both trains of the standby AFW system are allowed by Technical Specifications to be concurrently inoperable for a period of up to 7 days. The actual inoperability occurred over 10 days while the flow transmitters were isolated. Ginna did not report the event at the time the isolated transmitters were discovered because the transmitters' control function was not recognized to interact in an unanalyzed manner with the resulting unavailable control room indication, concurrent with the low pressure steam generator condition associated with the HELB event. The licensee notified the NRC Resident Inspector. | Steam Generator Auxiliary Feedwater | |
| ENS 42588 | 18 May 2006 19:00:00 | 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | Unevaluated Failure of Charging Pump in Fire Scenario | On May 18, 2006, it was determined that a previously unevaluated failure mode of charging pumps during a certain 10 CFR 50 Appendix R fire scenarios existed. Charging pumps are credited for specific fire scenarios to be available to make up inventory and provide reactivity control in the reactor coolant system. The engineering evaluation determined that an Appendix R fire scenario could potentially result in the failure of a circuit which would cause the credited charging pump to be tripped and held tripped by the undervoltage protection circuitry. The postulated failure would require diagnosis and manual actions to operate the charging pump. A preliminary analysis of the core damage risk associated with this condition was performed, taking into account the frequency of fires in all of the affected areas, the potential failure of fixed and/or manual fire suppression systems, and the required manual operator actions (with assumed failure likelihoods). The results indicate that the additional core damage frequency (CDF) associated with this condition is approximately 1.2E-07/yr. Procedures changes to address this issue are being developed. The NRC Resident Inspector was notified of this event by the licensee. | Reactor Coolant System | |
| ENS 40893 | 22 July 2004 13:42:00 | 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | Gap Discovered in Control Room Envelope | During Control Room Boundary investigations a gap in the control room envelope was discovered that exceeded the assumptions of the plant toxic gas analysis. The assumptions for the control room radiological analysis were met with the consideration for the use of Kl. The gap size was determined to be approximately 103 square inches versus an analysis assumption of 58.9 square inches. The gaps were immediately repaired. The licensee suspects that the gap has existed for 20 or more years and was discovered during a control room heating, ventilation, air-conditioning (HVAC) upgrade. The license has notified the NRC Resident Inspector of this event. | HVAC Control Room Envelope | |
| ENS 40184 | 19 September 2003 22:00:00 | 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | Unanalyzed Condition | While shutdown in Mode 5, containment recirculation sump 'B' was inspected for sump screen bypass flow paths in accordance with the requirements of NRC Bulletin 2003-01. Inspection results showed that approximately 25 square inches of space is available for recirculation flow to bypass the sump screens. This condition has the possibility of affecting the containment spray, safety injection and residual heat removal systems. The plant is stable in a refueling outage at approximately 95 degrees F, with normal residual heat removal in service and loop levels at 72 inches. The licensee notified the NRC Resident Inspector.
The licensee is retracting this event after performing an extensive evaluation had determined that equipment required to mitigate the event, though found to be in a degraded condition, would have performed their functions. This event has been discussed with the NRC Resident Inspector and he was informed of the event retraction. Notified Reg 1 RDO(Rogge) | Residual Heat Removal Containment Spray |