05000458/FIN-2018002-02
Finding | |
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| Title | Enforcement Action (EA)-18-053: Enforcement Discretion for Tornado-Generated Missile Protection Noncompliances |
| Description | Title 10 CFR Part 50, Appendix A, General Design Criteria for Nuclear Power Plants, Criterion 2, Design Bases for Protection Against Natural Phenomena, states, in part, that systems, structures, and components (SSCs) important to safety shall be designed to withstand the effects of natural phenomena, such as tornadoes. Criterion 4, Environmental and Dynamic Effects Design Basis, states, in part, that SSCs important to safety shall be appropriately protected against dynamic effects including missiles that may result from events and conditions outside the nuclear power unit. Section 3.5.2, Structures, Systems, and Components to be Protected from Missiles, of the Updated Safety Analysis Report (USAR) details the structures that are designed to withstand tornado missile impact.On February 7, 2017, the NRC issued Enforcement Guidance Memorandum (EGM) 15-002, Enforcement Discretion for Tornado-Generated Missile Protection Noncompliance, Revision 1 (ADAMS Accession Number ML16355A286). The EGM referenced a bounding generic risk analysis performed by the NRC staff that concluded that tornado missile vulnerabilities pose a low risk significance to operating nuclear plants. Because of this, the EGM described the conditions under which the NRC staff may exercise enforcement discretion for noncompliance with the current licensing basis for tornado-generated missile protection. Specifically, if the licensee could not meet the technical specification required actions within the required completion time, the EGM allows the staff to exercise enforcement discretion provided the licensee implements initial compensatory measures prior to the expiration of the time allowed by the limiting condition for operation. The compensatory actions should provide additional protection such that the likelihood of tornado missile effects are lessened. The EGM then requires the licensee to implement more comprehensive compensatory measures within approximately 60 days of issue discovery. The compensatory measures must remain in place until permanent repairs are completed, or until the NRC dispositions the non-compliance in accordance with a method acceptable to the NRC such that discretion is no longer needed. Because EGM 15-002 listed River Bend Station as a Group A plant, enforcement discretion expired on June 10, 2018. On May 10, 2018, River Bend Station submitted a request to extend the enforcement discretion period to June 10,
8 2020. On May 31, 2018, River Bend Station submitted asupplement to the May 10 request. On June 6, 2018, the NRC granted an extension to the enforcement discretion until June 10, 2020. The initial conditions of Design Basis Accident (DBA) and transient analyses in the USAR, Chapter 6 and Chapter 15, assume Engineered Safeguards Features (ESF) systems are operable. The AC, DC, and AC vital bus electrical power distribution systems are designed to provide sufficient capacity, capability, redundancy, and reliability to ensure the availability of necessary power to ESF systems so that the fuel, reactor coolant system, and containment design limits are not exceeded.The onsite standby power source for each 4.16 kV ESF bus is a dedicated emergency diesel generator (EDG). An EDG starts automatically on a loss of coolant accident signal (i.e., low reactor water level signal or high drywell pressure signal) or on an ESF bus degraded voltage or under voltage signal. In the event of a loss of preferred power, the ESF electrical loads are automatically connected to the EDGs in sufficient time to provide for safe reactor shutdown and to mitigate the consequences of a DBA such as a loss of coolant accident. Standby service water (SSW) is required by Technical Specification 3.7.1. The ultimate heat sink (UHS) consists of one 200 percent capacity cooling tower and one 100 percent capacity water storage basin. The UHS basin capacity is required by Regulatory Guide 1.27 and USAR 9.2.5 to maintain a minimum of 30 days inventory to mitigate the consequences of a DBA without replenishment. The UHS is designed to perform its safety function assuming a single failure coincident with a loss of offsite power and with respect to the 30 day mission time assuming a single division of SSW is in service.The safety design bases of these SSCs includes ensuring the SSCs are protected from the effects of natural phenomena, such as earthquakes, tornadoes, hurricanes, floods, and external missiles (GDC-2).On May 4, 2018, the licensee identified vulnerabilities in the EDG building, the control building, and the SSW cooling tower where tornado-born missiles could potential render safety-related equipment contained in these buildings inoperable. Potentially affected equipment included all three EDGs, Division II DC electrical power distribution subsystem, residual heat removal (RHR) pumps B and C, SSW pumps A, B, C, and D, Division I standby cooling tower fans, and multiple Division I SSW motor operated valves. These vulnerabilities were identified as part of the licensees review of Regulatory Information Summary 2015-06, Tornado Missile Protection. These issues were entered into the corrective action program as Condition Reports CR-RBS-2018-02687, 02768, and 02775.Corrective Actions: As a result of these issues, the licensee declared all three EDGs, the Division II DC electrical power distribution subsystem, RHR pumps B and C, SSW pumps A, B, C, and D, Division I standby cooling tower fans, and multiple Division I SSW motor operated valves inoperable, complied with the applicable technical specification action statements, initiated Condition Reports CR-RBS-2018-02687, 02768, and 02775, invoked the EGM discretion guidance, implemented initial compensatory measures, and returned the SSCs to an operable- degraded/non-conforming status. The licensee instituted compensatory measures intended to reduce the likelihood of tornado missile effects. These included verifying that guidance was in place for severe weather procedures, abnormal and emergency operating procedures, and FLEXsupport guidelines, verifying that training on these procedures was current, and verifying that a heightened level of awareness of the vulnerability was established.Corrective Action Reference(s) : CR-RBS-2018-02687, CR-RBS-2018-02768, and CR-RBS-2018-02775Enforcement:Violations: Technical Specification 3.8.1 requires, in part, that three diesel generators shall be operable in Modes 1, 2, and 3. Technical Specification 3.8.1.H requires entry into LimitingCondition for Operation 3.0.3 when three or more required AC sources are inoperable. Limiting Condition for Operation 3.0.3 requires that action shall be initiated within one hour to place the unit in Mode 2 within 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br />, in Mode 3 within 13 hours1.50463e-4 days <br />0.00361 hours <br />2.149471e-5 weeks <br />4.9465e-6 months <br />, and in Mode 4 within 37 hours4.282407e-4 days <br />0.0103 hours <br />6.117725e-5 weeks <br />1.40785e-5 months <br />.Contrary to the above, prior to May 4, 2018, three diesel generators were not operable, and action was not initiated to place the unit in Mode 2 within 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br />, in Mode 3 within 13 hours1.50463e-4 days <br />0.00361 hours <br />2.149471e-5 weeks <br />4.9465e-6 months <br />,and in Mode 4 within 37 hours4.282407e-4 days <br />0.0103 hours <br />6.117725e-5 weeks <br />1.40785e-5 months <br />. Specifically, the EDG building was not designed to withstand the effects of natural phenomena, such as tornadoes. The licensee initiated a condition report, invoked the enforcement discretion guidance, implemented initial compensatory measures, and returned the SSCs to an operable- degraded/non-conforming status. The inspectors verified through inspection sampling that the EGM 15-002 criteria were met and that the issue was documented in Condition Report CR-RBS-2018-02687. Therefore, EGM 15-002 enforcement discretion was applied to the required shutdown actions associated with this technical specification.Technical Specification 3.8.9 requires, in part, that the Division II AC and AC vital bus electrical power distribution subsystems shall be operable in Modes 1, 2, and 3. Technical Specification 3.8.9.D requires the station to take action to place the unit in Mode 3 within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> when one or more AC or AC vital bus electrical power distribution subsystems have been inoperable for more than 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />. Contrary to the above, prior to May 4, 2018, the Division II AC and AC vital bus electrical power distribution subsystems were not operable for more than 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />, and action was not initiated to place the unit in Mode 3 within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. Specifically, the control building was not designed to withstand the effects of natural phenomena, such as tornadoes. The licensee initiated a condition report, invoked the enforcement discretion guidance, implemented initial compensatory measures, and returned the SSCs to an operable- degraded/non-conforming status. The inspectors verified through inspection sampling that the EGM 15-002 criteria were met and that the issue was documented in Condition Report CR-RBS-2018-02768. Therefore, EGM 15-002 enforcement discretion was applied to the required shutdown actions associated with this technical specification.Technical Specification 3.5.1 requires, in part, that each emergency core cooling system (ECCS) injection subsystem shall be operable in Modes 1, 2, and 3. Technical Specification 3.5.1.D requires the station to take action to place the unit in Mode 3 within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> when two ECCS injection subsystems have been inoperable for more than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. Contrary to the above, prior to May 4, 2018, two required ECCS injection subsystems that included RHR pumps B and C were inoperable for more than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, and action was not initiated to place the unit in Mode 3 within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. Specifically, the control building was not designed to withstand the effects of natural phenomena, such as tornadoes.The licensee initiated a condition report, invoked the enforcement discretion guidance, implemented initial compensatory measures, and returned the SSCs to an operable- degraded/non-conforming status. The inspectors verified through inspection sampling that the EGM 15-002 criteria were met and that the issue was documented in Condition Report CR-RBS-2018-02768. Therefore, EGM 15-002 enforcement discretion was applied to the required shutdown actions associated with this technical specification.Technical Specification 3.7.1 requires, in part, that two SSW subsystems shall be operable in Modes 1, 2, and 3. Technical Specification 3.7.1. H requires the station to take action to place the unit in Mode 3 within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> when both pumps associated with one SSW subsystem have been inoperable for more than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. Contrary to the above, prior to May 4, 2018, SSW pumps P2B and P2D, associated with SSWsubsystem B, were inoperable for more than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, and action was not initiated to place the unit in Mode 3 within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. Specifically, the SSW cooling tower was not designed to withstand the effects of natural phenomena, such as tornadoes. The licensee initiated a condition report, invoked the enforcement discretion guidance, implemented initial compensatory measures, and returned the SSCs to an operable- degraded/non-conforming status. The inspectors verified through inspection sampling that the EGM 15-002 criteria were met and that the issue was documented in Condition Report CR-RBS-2018-02775. Therefore, EGM 15-002 enforcement discretion was applied to the required shutdown actions associated with this technical specification.Severity/Significance: Not ApplicableBasis for Discretion: The NRC exercised enforcement discretion in accordance with EGM 15-00, Revision 1, because the licensee implemented initial compensatory measures in accordance with the EGM. |
| Site: | River Bend  |
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| Report | IR 05000458/2018002 Section 1R15 |
| Date counted | Jun 30, 2018 (2018Q2) |
| Type: | Violation: Severity level Enforcement Discretion |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.15 |
| Inspectors (proximate) | J Sowa B Parks J Kozal |
| Violation of: | 10 CFR 50 Appendix A 10 CFR 50 Appendix A GDC 2 10 CFR 50 Appendix A GDC 4 Technical Specification |
| INPO aspect | |
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Finding - River Bend - IR 05000458/2018002 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (River Bend) @ 2018Q2
Self-Identified List (River Bend)
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