ML110040896
| ML110040896 | |
| Person / Time | |
|---|---|
| Site: | Bellefonte  |
| Issue date: | 12/22/2010 |
| From: | Arent G Tennessee Valley Authority |
| To: | Document Control Desk, Office of New Reactors |
| Spink T | |
| References | |
| BELLEFONTE.P02.NP, BELLEFONTE.P02.NP.3, TENNVALLEY, TENNVALLEY.SUBMISSION.6, +reviewedmmc1 | |
| Download: ML110040896 (82) | |
Text
CHAPTER 19 PROBABILISTIC RISK ASSESSMENT TABLE OF CONTENTS Section Title Page
19.1 INTRODUCTION
............................................................................... 19.1-1 19.2 INTERNAL INITIATING EVENTS...................................................... 19.2-1 19.3 MODELING OF SPECIAL INITIATORS ............................................ 19.3-1 19.4 EVENT TREE MODELS.................................................................... 19.4-1 19.5 SUPPORT SYSTEMS ....................................................................... 19.5-1 19.6 SUCCESS CRITERIA ANALYSIS..................................................... 19.6-1 19.7 FAULT TREE GUIDELINES.............................................................. 19.7-1 19.8 PASSIVE CORE COOLING SYSTEM - PASSIVE RESIDUAL HEAT REMOVAL .............................................................................. 19.8-1 19.9 PASSIVE CORE COOLING SYSTEM - CORE MAKEUP TANKS.... 19.9-1 19.10 PASSIVE CORE COOLING SYSTEM - ACCUMULATOR ............. 19.10-1 19.11 PASSIVE CORE COOLING SYSTEM - AUTOMATIC DEPRESSURIZATION SYSTEM .................................................... 19.11-1 19.12 PASSIVE CORE COOLING SYSTEM - IN-CONTAINMENT REFUELING WATER STORAGE TANK......................................... 19.12-1 19.13 PASSIVE CONTAINMENT COOLING ............................................ 19.13-1 19.14 MAIN AND STARTUP FEEDWATER SYSTEM.............................. 19.14-1 19.15 CHEMICAL AND VOLUME CONTROL SYSTEM........................... 19.15-1 19.16 CONTAINMENT HYDROGEN CONTROL SYSTEM ...................... 19.16-1 19.17 NORMAL RESIDUAL HEAT REMOVAL SYSTEM ......................... 19.17-1 19.18 COMPONENT COOLING WATER SYSTEM.................................. 19.18-1 19.19 SERVICE WATER SYSTEM ........................................................... 19.19-1 19-i Revision 3
TABLE OF CONTENTS (Continued)
Section Title Page 19.20 CENTRAL CHILLED WATER SYSTEM.......................................... 19.20-1 19.21 AC POWER SYSTEM ..................................................................... 19.21-1 19.22 CLASS 1E DC & UPS SYSTEM...................................................... 19.22-1 19.23 NON-CLASS 1E DC & UPS SYSTEM ............................................ 19.23-1 19.24 CONTAINMENT ISOLATION .......................................................... 19.24-1 19.25 COMPRESSED AND INSTRUMENT AIR SYSTEM ....................... 19.25-1 19.26 PROTECTION AND SAFETY MONITORING SYSTEM ................. 19.26-1 19.27 DIVERSE ACTUATION SYSTEM ................................................... 19.27-1 19.28 PLANT CONTROL SYSTEM........................................................... 19.28-1 19.29 COMMON CAUSE ANALYSIS........................................................ 19.29-1 19.30 HUMAN RELIABILITY ANALYSIS .................................................. 19.30-1 19.31 OTHER EVENT TREE NODE PROBABILITIES ............................. 19.31-1 19.32 DATA ANALYSIS AND MASTER DATA BANK .............................. 19.32-1 19.33 FAULT TREE AND CORE DAMAGE QUANTIFICATION............... 19.33-1 19.34 SEVERE ACCIDENT PHENOMENA TREATMENT ...................... 19.34-1 19.35 CONTAINMENT EVENT TREE ANALYSIS ................................... 19.35-1 19.36 REACTOR COOLANT SYSTEM DEPRESSURIZATION .............. 19.36-1 19.37 CONTAINMENT ISOLATION ......................................................... 19.37-1 19.38 REACTOR VESSEL REFLOODING .............................................. 19.38-1 19.39 IN-VESSEL RETENTION OF MOLTEN CORE DEBRIS ............... 19.39-1 19.40 PASSIVE CONTAINMENT COOLING ........................................... 19.40-1 19.41 HYDROGEN MIXING AND COMBUSTION ANALYSIS ................. 19.41-1 19-ii Revision 3
TABLE OF CONTENTS (Continued)
Section Title Page 19.42 CONDITIONAL CONTAINMENT FAILURE PROBABILITY DISTRIBUTION ............................................................................... 19.42-1 19.43 RELEASE FREQUENCY QUANTIFICATION ................................. 19.43-1 19.44 MAAP4.0 CODE DESCRIPTION AND AP1000 MODELING.......... 19.44-1 19.45 FISSION PRODUCT SOURCE TERMS ......................................... 19.45-1 19.46 NOT USED ...................................................................................... 19.46-1 19.47 NOT USED ...................................................................................... 19.47-1 19.48 NOT USED ...................................................................................... 19.48-1 19.49 OFFSITE DOSE EVALUATION ...................................................... 19.49-1 19.50 IMPORTANCE AND SENSITIVITY ANALYSIS .............................. 19.50-1 19.51 UNCERTAINTY ANALYSIS ............................................................ 19.51-1 19.52 NOT USED ...................................................................................... 19.52-1 19.53 NOT USED ...................................................................................... 19.53-1 19.54 LOW POWER AND SHUTDOWN PRA ASSESSMENT ................. 19.54-1 19.55 SEISMIC MARGIN ANALYSIS........................................................ 19.55-1 19.56 PRA INTERNAL FLOODING ANALYSIS ........................................ 19.56-1 19.57 INTERNAL FIRE ANALYSIS ........................................................... 19.57-1 19.58 WINDS, FLOODS, AND OTHER EXTERNAL EVENTS ................. 19.58-1 19.
58.3 CONCLUSION
........................................................................... 19.58-1 19.
58.4 REFERENCES
.......................................................................... 19.58-1 19.59 PRA RESULTS AND INSIGHTS ..................................................... 19.59-1 19.59.10.5 Combined License Information ............................................ 19.59-1 19.59.10.6 PRA Configuration Controls................................................. 19.59-3 19.59.11 REFERENCES .......................................................................... 19.59-6 19-iii Revision 3
TABLE OF CONTENTS (Continued)
Section Title Page APP. 19A THERMAL HYDRAULIC ANALYSIS TO SUPPORT SUCCESS CRITERIA ............................................................19A-1 APP. 19B EX-VESSEL SEVERE ACCIDENT PHENOMENA ................19B-1 APP. 19C ADDITIONAL ASSESSMENT OF AP1000 DESIGN FEATURES ............................................................................19C-1 APP. 19D EQUIPMENT SURVIVABILITY ASSESSMENT ....................19D-1 APP. 19E SHUTDOWN EVALUATION ..................................................19E-1 APP. 19F MALEVOLENT AIRCRAFT IMPACT ..................................... 19F-1 19-iv Revision 3
LIST OF TABLES Number Title 19.58-201 External Event Frequencies for BLN 19-v Revision 3
CHAPTER 19 PROBABILISTIC RISK ASSESSMENT
19.1 INTRODUCTION
This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.1-1 Revision 3
19.2 INTERNAL INITIATING EVENTS This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.2-1 Revision 3
19.3 MODELING OF SPECIAL INITIATORS This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.3-1 Revision 3
19.4 EVENT TREE MODELS This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.4-1 Revision 3
19.5 SUPPORT SYSTEMS This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.5-1 Revision 3
19.6 SUCCESS CRITERIA ANALYSIS This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.6-1 Revision 3
19.7 FAULT TREE GUIDELINES This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.7-1 Revision 3
19.8 PASSIVE CORE COOLING SYSTEM - PASSIVE RESIDUAL HEAT REMOVAL This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.8-1 Revision 3
19.9 PASSIVE CORE COOLING SYSTEM - CORE MAKEUP TANKS This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.9-1 Revision 3
19.10 PASSIVE CORE COOLING SYSTEM - ACCUMULATOR This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.10-1 Revision 3
19.11 PASSIVE CORE COOLING SYSTEM - AUTOMATIC DEPRESSURIZATION SYSTEM This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.11-1 Revision 3
19.12 PASSIVE CORE COOLING SYSTEM - IN-CONTAINMENT REFUELING WATER STORAGE TANK This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.12-1 Revision 3
19.13 PASSIVE CONTAINMENT COOLING This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.13-1 Revision 3
19.14 MAIN AND STARTUP FEEDWATER SYSTEM This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.14-1 Revision 3
19.15 CHEMICAL AND VOLUME CONTROL SYSTEM This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.15-1 Revision 3
19.16 CONTAINMENT HYDROGEN CONTROL SYSTEM This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.16-1 Revision 3
19.17 NORMAL RESIDUAL HEAT REMOVAL SYSTEM This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.17-1 Revision 3
19.18 COMPONENT COOLING WATER SYSTEM This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.18-1 Revision 3
19.19 SERVICE WATER SYSTEM This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.19-1 Revision 3
19.20 CENTRAL CHILLED WATER SYSTEM This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.20-1 Revision 3
19.21 AC POWER SYSTEM This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.21-1 Revision 3
19.22 CLASS 1E DC & UPS SYSTEM This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.22-1 Revision 3
19.23 NON-CLASS 1E DC & UPS SYSTEM This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.23-1 Revision 3
19.24 CONTAINMENT ISOLATION This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.24-1 Revision 3
19.25 COMPRESSED AND INSTRUMENT AIR SYSTEM This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.25-1 Revision 3
19.26 PROTECTION AND SAFETY MONITORING SYSTEM This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.26-1 Revision 3
19.27 DIVERSE ACTUATION SYSTEM This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.27-1 Revision 3
19.28 PLANT CONTROL SYSTEM This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.28-1 Revision 3
19.29 COMMON CAUSE ANALYSIS This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.29-1 Revision 3
19.30 HUMAN RELIABILITY ANALYSIS This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.30-1 Revision 3
19.31 OTHER EVENT TREE NODE PROBABILITIES This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.31-1 Revision 3
19.32 DATA ANALYSIS AND MASTER DATA BANK This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.32-1 Revision 3
19.33 FAULT TREE AND CORE DAMAGE QUANTIFICATION This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.33-1 Revision 3
19.34 SEVERE ACCIDENT PHENOMENA TREATMENT This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.34-1 Revision 3
19.35 CONTAINMENT EVENT TREE ANALYSIS This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.35-1 Revision 3
19.36 REACTOR COOLANT SYSTEM DEPRESSURIZATION This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.36-1 Revision 3
19.37 CONTAINMENT ISOLATION This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.37-1 Revision 3
19.38 REACTOR VESSEL REFLOODING This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.38-1 Revision 3
19.39 IN-VESSEL RETENTION OF MOLTEN CORE DEBRIS This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.39-1 Revision 3
19.40 PASSIVE CONTAINMENT COOLING This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.40-1 Revision 3
19.41 HYDROGEN MIXING AND COMBUSTION ANALYSIS This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.41-1 Revision 3
19.42 CONDITIONAL CONTAINMENT FAILURE PROBABILITY DISTRIBUTION This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.42-1 Revision 3
19.43 RELEASE FREQUENCY QUANTIFICATION This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.43-1 Revision 3
19.44 MAAP4.0 CODE DESCRIPTION AND AP1000 MODELING This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.44-1 Revision 3
19.45 FISSION PRODUCT SOURCE TERMS This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.45-1 Revision 3
19.46 NOT USED This section was not required for DCD and is not used by DCD and FSAR.
19.46-1 Revision 3
19.47 NOT USED This section was not required for DCD and is not used by DCD and FSAR.
19.47-1 Revision 3
19.48 NOT USED This section was not required for DCD and is not used by DCD and FSAR.
19.48-1 Revision 3
19.49 OFFSITE DOSE EVALUATION This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.49-1 Revision 3
19.50 IMPORTANCE AND SENSITIVITY ANALYSIS This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.50-1 Revision 3
19.51 UNCERTAINTY ANALYSIS This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.51-1 Revision 3
19.52 NOT USED This section was not required for DCD and is not used by DCD and FSAR.
19.52-1 Revision 3
19.53 NOT USED This section was not required for DCD and is not used by DCD and FSAR.
19.53-1 Revision 3
19.54 LOW POWER AND SHUTDOWN PRA ASSESSMENT This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.54-1 Revision 3
19.55 SEISMIC MARGIN ANALYSIS This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.55-1 Revision 3
19.56 PRA INTERNAL FLOODING ANALYSIS This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.56-1 Revision 3
19.57 INTERNAL FIRE ANALYSIS This section of the referenced DCD is incorporated by reference with no departures or supplements.
19.57-1 Revision 3
19.58 WINDS, FLOODS, AND OTHER EXTERNAL EVENTS This section of the referenced DCD is incorporated by reference with the following departures and/or supplements.
19.
58.3 CONCLUSION
Add the following information at the end of DCD Subsection 19.58.3:
SUP 19.58-1 Table 19.58-201 documents the site-specific external events evaluation that has been performed for BLN Units 3 and 4. This table provides a general explanation of the evaluation and resultant conclusions and provides a reference to applicable sections of the COL where more detailed supporting information (including data used, methods and key assumptions) regarding the specific event is located.
Based upon this evaluation, it is concluded that the BLN Units 3 and 4 site is bounded by the High Winds, Floods and Other External Events analysis documented in DCD Section 19.58 and APP-GW-101 (Reference 201) and no further evaluations are required at the COL application stage.
19.
58.4 REFERENCES
201. Westinghouse Electric Company LLC, AP1000 Probabilistic Risk Assessment Site-Specific Considerations, Document Number APP-GW-GLR-101, Revision 1, October 2007.
202. NUREG/CR-4461, Tornado Climatology of the Contiguous United States, Revision 2, February 2007.
203. Texas Tech University, Wind Science and Engineering Center, A Recommendation for an Enhanced Fujita Scale (EF-Scale), June 2004.
204. ASCE Standard ASCE/SEI 7-05, Minimum Design Loads for Buildings and Other Structures, 2006 19.58-1 Revision 3
Part 2, FSAR TABLE 19.58-201 (Sheet 1 of 7) 19.58-1 EXTERNAL EVENT FREQUENCIES FOR BLN Applicable to Event Category Event Explanation of Applicability Evaluation site? (Y/N)1 Frequency High Winds EF0 Tornado Y The Texas Tech University (TTU) research Publication, A Recommendation for an Enhanced 8.89E-04 Fujita Scale (EF-Scale), (Reference 203) correlates the Fujita-Scale wind speeds with the events/yr EF-Scale wind speeds, and states that a tornado rated according to the Fujita Scale will have the EF1 Tornado Y 8.89E-04 same F-Number in the EF Scale, e.g. F3 translates into EF3, although the wind speed ranges events/yr are different. Accordingly, the tornado classifications are presented using the EF scale for EF2 Tornado Y consistency with APP-GW-GLR-101 (Reference 201). 8.89E-04 events/yr EF3 Tornado Y Tornado activity for the seven county region around the BLN site is provided in FSAR 8.89E-04 Table 2.3-208 from 1950 through 2005. The information in this table provides an adequate events/yr sample size for the BLN tornado analysis. The combined area of the seven neighboring counties EF4 Tornado Y No Recorded represented in the table is 4,447 square miles which is slightly larger than a 1-degree box centered on the site (3,943 square miles). NUREG/CR-4461 (Reference 202), states that Events EF5 Tornado Y 1-degree boxes should only be used if the number of events is large enough to ensure reliable statistics. NUREG/CR-4461, Appendix C, indicates that a minimum of 10 events and 20 or more events are desirable. FSAR Table 2.3-208 provides 151 events for the seven counties.
Therefore, the NUREG/CR-4461 criterion for sample size is met.
The strike probability is determined using the methodology for large structure strike probability in NUREG/CR-4461, Section 4.2. Note, tornados with zero length were addressed by giving them average lengths based on other tornados in the same class and county. Also, EF0 tornados with zero lengths for Marshall and Franklin county were given a 2 mi length, because 2 mi is the highest average length for EF0 tornados amongst the seven counties. Additionally the No Recorded characteristic dimension is taken from NUREG/CR-4461, Section 4.2 as 0.0379 miles. Events BLN has conservatively assumed that the strike probability for a tornado of a given intensity is equal to the overall strike probability for any tornado. These event frequencies are bounded by the limiting initiating event frequencies given in Table 3.0-1 of APP-GW -GLR -101.
Therefore, the safety features of the AP1000 are unaffected and the CDFs given in APP-GW-GLR-101 Table 3.0-1 for these events are applicable to BLN Units 3 and 4.
19.58-2 Revision 3
Part 2, FSAR TABLE 19.58-201 (Sheet 2 of 7) 19.58-1 EXTERNAL EVENT FREQUENCIES FOR BLN Applicable to Event Category Event Explanation of Applicability Evaluation site? (Y/N)1 Frequency High Winds Cat.1 Hurricane Historical data for tropical weather is archived by the National Coastal Services Center, and
<1E-02 (cont.) Y dates back to 1851. This data was used to analyze the occurrence of tropical weather traveling directly over Jackson County, or near enough to Jackson County to have a substantial impact Cat.2 Hurricane Y <1E-02 (perimeter distance defined as 100 miles).
Cat.3 Hurricane Y <1E-02 Cat.4 Hurricane Y Figure 6-1B of ASCE/SEI 7-05 (Reference 204) shows the basic wind speed for the eastern part <1E-02 of the Gulf of Mexico, including the state of Alabama. BLN is located in the northeast part of the Cat.5 Hurricane Y <1E-02 state beyond the 90 mph contour. Thus, it is concluded that BLN is not located in a Hurricane Prone Region.
There were no recorded events for hurricanes. However, a conservative event frequency of
<1E-02 was assigned for these events, consistent with APP-GW-GLR-101 for Category 4 and 5 hurricanes (Reference 201).
Tropical Storm Y The event frequencies for tropical storms, depressions, and cyclones are based on the number 8.23E-02 of recorded events over the 158 year period of historical data archived by the National Coastal Tropical Depression Y 1.01E-01 Services Center.
Extratropical Y 1.90E-02 Cyclones The maximum wind speed of these storms is less than 65 mph. As documented in FSAR Table 2.0-201, the BLN site characteristic operating basis wind speed (96 mph) is below the DCD site characteristic operating basis wind speed of 145 mph and bounds the maximum wind speed identified above (65 mph).
Therefore, it is concluded that the safety features of the AP1000 are unaffected by high wind events and the resultant CDFs given in Table 3.0-1 of APP-GW-GLR-101 (Reference 201) for these events are applicable to BLN Units 3 and 4.
19.58-3 Revision 3
Part 2, FSAR TABLE 19.58-201 (Sheet 3 of 7) 19.58-1 EXTERNAL EVENT FREQUENCIES FOR BLN Applicable to Event Category Event Explanation of Applicability Evaluation site? (Y/N)1 Frequency External Flood External Flood Y As discussed in FSAR Subsection 2.4.2, the maximum flood elevation at the BLN site is 622.5 ft. Note 2 msl. Coincident wind waves would create maximum waves of 5.41 ft. (trough to crest) and produce maximum flood levels of 624.03 ft. msl, including wind wave setup and run-up. The BLN plant grade of 628.6 ft. msl is above the worst potential flood considerations.
Additionally, as discussed in FSAR Subsection 2.4.2, the maximum water level due to the local PMP event without drainage is 627.53 ft. msl in the vicinity of the safety-related structures, which is below plant grade. Therefore, no external flood protection measures are required for BLN Units 3 and 4.
As discussed in FSAR Subsection 2.4.3.5, the maximum flood elevation at BLN was determined to be 622.1 ft. msl, produced by the 21,400 sq. mi. storm and coincident overtopping failure of the west saddle dike at Watts Bar Dam and the north embankment at Nickajack Dam. Chickamauga Dam is overtopped but was assumed not to fail. However, proposed dam safety modifications to allow overtopping at Chickamauga Dam have not been performed. Without the dam safety modifications at Chickamauga Dam, the maximum flood elevation was determined to be 622.5 ft.
msl. The BLN safety-related structures are located at elevation 628.6 ft. msl and are unaffected by flood conditions.
As discussed in FSAR Subsection 1.2.2, the BLN plant grade elevation of 628.6 ft. msl corresponds to DCD grade elevation 100 ft. Based upon the quantitative evaluations performed, the BLN site is not susceptible to any external floods which would adversely impact safe operation of BLN Units 3 and 4.
This is consistent with the evaluation presented in Section 4.0 of APP-GW-GLR-101 (Reference 201), which states that the AP1000 is protected against floods up to the 100 level.
Therefore, it is concluded that the resultant CDF of 5.85E-15 events per year given in APP-GW-GLR-101, Section 4.0 is bounding.
19.58-4 Revision 3
Part 2, FSAR TABLE 19.58-201 (Sheet 4 of 7) 19.58-1 EXTERNAL EVENT FREQUENCIES FOR BLN Applicable to Event Category Event Explanation of Applicability Evaluation site? (Y/N)1 Frequency Transportation Aviation Y As discussed in FSAR Subsection 3.5.1.6, a calculation performed in accordance with the 8.8E-07 and Nearby (commercial/ guidelines of Standard Review Plan (SRP) Section 3.5.1.6, determined the total probability of an events/year Facility Accidents general/ military) aircraft crash into the plant to be 8.8E-07 per year. The probability of aircraft from the Scottsboro Municipal Airport crashing into the site is 7.8E-07 per year. This meets the criterion provided in APP-GW-GLR-101 (Reference 201) that sites that can demonstrate an aviation event frequency less than or equal to 1.21E-06 events/yr for small aircraft accidents are bounded by this evaluation.
The probability of a crash from the high altitude airway J73 is conservatively estimated to be 1.0E-07 per year. This meets the commercial aircraft aviation event frequency of 1.0E-07 events per year provided in APP-GW-GLR-101.
Therefore, it is concluded that the evaluation provided in APP-GW-GLR-101 remains applicable.
Marine (ship/barge) Y As discussed in FSAR Subsection 2.2.3.1.1.1, a calculation was done to quantify the risk to the 1.9E-08 BLN site from barge accidents on the Tennessee River involving either explosions or flammable events/yr vapor clouds. The results of the detonation risk assessment (to the site) show a risk value less than 1.9E-08 per year.
As discussed in FSAR Subsection 2.2.3.1.2, an evaluation determined no deflagrations would be expected at the BLN site resulting from a delayed ignition of a vapor cloud released from a postulated barge accident.
Based upon the quantitative consequence evaluations performed, no risk-important events related to marine transportation have been identified for BLN Units 3 and 4. This is consistent with the evaluation provided in Subsection 5.4 of APP-GW-GLR-101 (Reference 201). Therefore, because no risk-important consequences were identified in the evaluation, the potential for hazards from these sources are minimal and will not adversely affect safe operation of BLN Units 3 and 4.
Pipeline (gas/oil) N As stated in FSAR Subsection 2.2.2.3, there are no major pipelines within 5 miles of the BLN Note 1 site.
19.58-5 Revision 3
Part 2, FSAR TABLE 19.58-201 (Sheet 5 of 7) 19.58-1 EXTERNAL EVENT FREQUENCIES FOR BLN Applicable to Event Category Event Explanation of Applicability Evaluation site? (Y/N)1 Frequency Transportation Railroad Y As discussed in FSAR Subsection 2.2.3.1.1.1, the potential hazard resulting from railroad cars Note 2 and Nearby was evaluated using the methodology of RG 1.91. The maximum probable cargo based on Facility Accidents RG 1.91 was used along with a conservative TNT equivalency, which resulted in a safe standoff (cont.) distance which was less than the distance from the nearest approach of a railroad line to the site boundary.
As discussed in FSAR Subsection 2.2.3.1.2, unconfined vapor clouds with delayed ignition were also evaluated for various energetic combustible materials, and were determined to pose no hazard to the plant.
Based upon the quantitative consequence evaluations performed, no risk-important events related to rail transportation have been identified for BLN Units 3 and 4. This is consistent with the evaluation provided in Subsection 5.4 of APP-GW-GLR-101 (Reference 201). Therefore, because no risk-important consequences were identified in the evaluation, the potential for hazards from these sources are minimal and will not adversely affect safe operation of BLN Units 3 and 4.
Truck Y As discussed in FSAR Subsection 2.2.3.1.1.1, the potential hazard resulting from trucks was Note 2 evaluated using the methodology of RG 1.91. The maximum probable cargo based on RG 1.91 was used along with a conservative TNT equivalency, which resulted in a safe standoff distance which was less than the distance from the nearest highway to the site boundary.
As discussed in FSAR Subsection 2.2.3.1.2, unconfined vapor clouds with delayed ignition were also evaluated for various energetic combustible materials, and determined to not result in any significant damage to the plant.
Based upon the quantitative consequence evaluations performed, no risk-important events related to truck transportation have been identified for BLN Units 3 and 4. This is consistent with the evaluation provided in Subsection 5.4 of APP-GW-GLR-101 (Reference 201). Therefore, because no risk- important consequences were identified in the evaluation, the potential for hazards from these sources are minimal and will not adversely affect safe operation of BLN Units 3 and 4.
19.58-6 Revision 3
Part 2, FSAR TABLE 19.58-201 (Sheet 6 of 7) 19.58-1 EXTERNAL EVENT FREQUENCIES FOR BLN Applicable to Event Category Event Explanation of Applicability Evaluation site? (Y/N)1 Frequency Transportation Nearby Facility Y FSAR Subsection 2.2.3.1.1.3 discusses potential design basis events associated with accidents Note 2 and Nearby Accidents at nearby facilities. FSAR 2.2.3.2 concludes that the effects of events from these facilities on the Facility Accidents safety-related components of the plant are insignificant. Therefore, because no risk-important (cont.) consequences were identified, the potential for hazards from these sources are minimal and will not adversely affect safe operation of BLN Units 3 and 4 Other events A number of external Based on the evaluations below, these events do not pose a credible threat to the safe operation events beyond those of the station. Thus, these events are not considered to be risk-important and it can be concluded evaluated in DCD that the BLN Units 3 and 4 site is within the bounds of the Floods and Other External Events Subsection 19.58 analysis documented in DCD Section 19.58 and APP-GW-GLR-101 (Reference 201).
and APP-GW-GLR-101 (Reference 201) were evaluated for the BLN site. These events are discussed below.
External Fires Y FSAR Subsection 2.2.3.1.4 discusses external fires and concludes fires originating from Note 2 accidents at nearby facilities or transportation routes, and brush and forest fires will not endanger the safe operation of the station. This subsection also states fire and smoke from accidents at nearby homes, industrial facilities, transportation routes, or from area forest or brush fires, do not jeopardize the safe operation of the plant. Therefore, because no risk-important consequences were identified, the potential for hazards from external fires are minimal and will not adversely affect safe operation of BLN Units 3 and 4.
19.58-7 Revision 3
Part 2, FSAR TABLE 19.58-201 (Sheet 7 of 7) 19.58-1 EXTERNAL EVENT FREQUENCIES FOR BLN Applicable to Event Category Event Explanation of Applicability Evaluation site? (Y/N)1 Frequency Other events Toxic Chemical Y Based on the evaluations provided in FSAR Subsections 2.2.3.1.3 and 6.4.4.2, release of toxic Note 2 (cont.) Releases chemicals from stationary industrial sources and mobile sources in the vicinity of BLN does not pose a credible threat to the control room operators. Thus, these events are not considered to be risk-important.
Notes:
- 1. All events that are physically possible are considered to be applicable and are discussed. Those events that are physically not possible are considered not applicable to the site.
- 2. A specific event frequency for this event has not been determined. A deterministic quantitative consequence evaluation has been performed that has demonstrated that the event does not adversely impact the safe operation of BLN Units 3 and 4. Additional details are provided in the "Explanation of Applicability Evaluation" along with references to the applicable FSAR Subsections.
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19.59 PRA RESULTS AND INSIGHTS This section of the referenced DCD is incorporated by reference with the following departures and/or supplements.
19.59.10.5 Combined License Information COL A review of the differences between the as-built plant and the design used as the 9.10-1 basis for the AP1000 seismic margins analysis will be completed prior to fuel load.
A verification walkdown will be performed with the purpose of identifying differences between the as-built plant and the design. Any differences will be evaluated and the seismic margins analysis modified as necessary to account for the plant-specific design, and any design changes or departures from the certified design. A comparison of the as-built SSC high confidence, low probability of failures (HCLPFs) to those assumed in the AP1000 seismic margin evaluation will be performed prior to fuel load. Deviations from the HCLPF values or assumptions in the seismic margin evaluation due to the as-built configuration and final analysis will be evaluated to determine if vulnerabilities have been introduced.
The requirements to which the equipment is to be purchased are included in the equipment specifications. Specifically, the equipment specifications include:
- 1. Specific minimum seismic requirements consistent with those used to define the Table 19.55-1 HCLPF values. This includes the known frequency range used to define the HCLPF by comparing the required response spectrum (RRS) and test response spectrum (TRS). The range of frequency response that is required for the equipment with its structural support is defined.
- 2. Hardware enhancements that were determined in previous test programs and/or analysis programs will be implemented.
COL A review of the differences between the as-built plant and the design used as the 9.10-2 basis for the AP1000 PRA and DCD Table 19.59-18 will be completed prior to fuel load. The plant specific PRA-based insight differences will be evaluated and the plant specific PRA model modified as necessary to account for plant-specific design and any design changes or departures from the design certification PRA.
As discussed in Section 19.58.3, it has been confirmed that the Winds, Floods, and Other External Events analysis documented in DCD Section 19.58 is applicable to the site. The site-specific design has been evaluated and is 19.59-1 Revision 3
consistent with the AP1000 PRA assumptions. Therefore, Section 19.58 of the AP1000 DCD is applicable to this design.
COL A review of the differences between the as-built plant and the design used as the 9.10-3 basis for the AP1000 internal fire and internal flood analysis will be completed prior to fuel load. Plant specific internal fire and internal flood analyses will be evaluated and the analyses modified as necessary to account for the plant-specific design, and any design changes or departures from the certified design.
COL The AP1000 Severe Accident Management Guidance (SAMG) from 9.10-4 APP-GW-GLR-070, Reference 1 of DCD Section 19.59, is implemented on a site-specific basis. Key elements of the implementation include:
- SAMG based on APP-GW-GLR-070 is provided to Emergency Response Organization (ERO) personnel in assessing plant damage, planning and prioritizing response actions and implementing strategies that delineate actions inside and outside the control room.
- Severe accident management strategies and guidance are interfaced with the Emergency Operating Procedures (EOP's) and Emergency Plan.
- Responsibilities for authorizing and implementing accident management strategies are delineated as part of the Emergency Plan.
- SAMG training is provided for ERO personnel commensurate with their responsibilities defined in the Emergency Plan.
COL A thermal lag assessment of the as-built equipment required to mitigate severe 9.10-5 accidents (hydrogen igniters and containment penetrations) will be performed to provide additional assurance that this equipment can perform its severe accident functions during environmental conditions resulting from hydrogen burns associated with severe accidents. This assessment will be performed prior to fuel load and is required only for equipment used for severe accident mitigation that has not been tested at severe accident conditions. The ability of the as-built equipment to perform during severe accident hydrogen burns will be assessed using the Environment Enveloping method or the Test Based Thermal Analysis method discussed in EPRI NP-4354 (DCD Section 19.59, Reference 3).
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Add the following new information after DCD Subsection 19.59.10.5:
SUP 19.59.10.6 PRA Configuration Controls 9-1 PRA configuration controls contain the following key elements:
- A process for monitoring PRA inputs and collecting new information.
- A process that maintains and updates the PRA to be reasonably consistent with the as-built, as operated plant.
- A process that considers the cumulative impact of pending changes when applying the PRA.
- A process that evaluates the impact of changes on currently implemented risk-informed decisions that have used the PRA.
- A process that maintains configuration control of computer codes used to support PRA quantification.
- Documentation of the PRA.
PRA configuration controls are consistent with the regulatory positions on maintenance and upgrades in Regulatory Guide 1.200.
Schedule for Maintenance and Upgrades of the PRA The PRA update process is a means to reasonably reflect the as designed and as operated plant configurations in the PRA models.The PRA upgrade process includes an update of the PRA plus a general review of the entire PRA model, and as applicable the application of new software that implements a different methodology, implementation of new modeling techniques, as well as a comprehensive documentation effort.
- During construction, the PRA is upgraded prior to fuel load to cover those initiating events and modes of operation contained in NRC-endorsed consensus standards on PRA in effect one year prior to the scheduled date of the initial fuel load for a Level 1 and Level 2 PRA.
- Prior to license renewal the PRA is upgraded to include all modes of operation.
- During operation, PRA updates are completed as part of the upgrade process at least once every four years.
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- A screening process is used to determine whether a PRA update should be performed more frequently based upon the nature of the changes in design or procedures. The screening process considers whether the changes affect the PRA insights. Changes that do not meet the threshold for immediate update are tracked for the next regulatory scheduled update. If the screening process determines that the changes do warrant a PRA update, the update is made as soon as practicable consistent with the required change importance and the applications being used.
PRA upgrades are performed in accordance with 10 CFR 50.71(h).
Process for Maintenance and Upgrades of the PRA Various information sources are monitored to determine changes or new information that affects the model assumptions or quantification. Plant specific design, procedure, and operational changes are reviewed for risk impact.
Information sources include applicable operating experience, plant modifications, engineering calculation revisions, procedure changes, industry studies, and NRC information.
The PRA upgrade includes initiating events and modes of operation contained in NRC-endorsed consensus standards on PRA in effect one year prior to each required upgrade.
This PRA maintenance and update incorporates the appropriate new information including significant modeling errors discovered during routine use of the PRA.
Once the PRA model elements requiring change are identified, the PRA computer models are modified and appropriate documents revised. Documentation of modifications to the PRA model include the changes as well as the upgraded portions clearly indicating what has been changed. The impact on the risk insights is clearly indicated.
PRA Quality Assurance Maintenance and upgrades of the PRA are subject to the following quality assurance provisions:
Procedures identify the qualifications of personnel who perform the maintenance and upgrade of the PRA.
Procedures provide for the control of PRA documentation, including revisions.
For updates of the PRA, procedures provide for independent review, or checking of the calculations and information.
Procedures provide for an independent review of the model after an upgrade is completed. Additionally, after the PRA is upgraded, the PRA is reviewed by 19.59-4 Revision 3
outside PRA experts such as industry peer review teams and the comments incorporated to maintain the PRA current with industry practices. Peer review findings are entered into a tracking system. PRA upgrades receive a peer review for those aspects of the PRA that are upgraded.
PRA models and applications are documented in a manner that facilitates peer review as well as future updates and applications of the PRA by describing the processes that were used, and provide details of the assumptions made and their bases. PRA documentation is developed such that traceability and reproducibility is maintained. PRA documentation is maintained in accordance with Regulatory Position 1.3 of Regulatory Guide 1.200.
Procedures provide for appropriate attention or corrective actions if assumptions, analyses, or information used previously are changed or determined to be in error.
Potential impacts to the PRA model (i.e., design change notices, calculations, and procedure changes) are tracked. Errors found in the PRA model between periodic updates are tracked using the site tracking system.
PRA-Related Input to Other Programs and Processes The PRA provides input to various programs and processes, such as the Maintenance Rule implementation, reactor oversight process, the RAP, and the RTNSS program. The use of the PRA in these programs is discussed below, or cross-references to the appropriate FSAR sections are provided.
PRA Input to Design Programs and Processes The PRA insights identified during the design development are discussed in DCD Subsection 19.59.10.4 and summarized in DCD Table 19.59-18. DCD Section 14.3 summarizes the design material contained in AP1000 that has been incorporated into the Tier 1 information from the PRA. A discussion of the plant features important to reducing risk is provided in DCD Subsection 19.59.9.
PRA Input to the Maintenance Rule Implementation The PRA is used as an input in determining the safety significance classification and bases of in-scope SSCs. SSCs identified as risk-significant via the Reliability Assurance Program for the design phase (DRAP, Section 17.4) are included within the initial Maintenance Rule scope as high safety significance SSCs.
For risk-significant SSCs identified via DRAP, performance criteria are established, by the Maintenance Rule expert panel using input from the reliability and availability assumptions used in the PRA, to monitor the effectiveness of the maintenance performed on the SSCs.
The Maintenance Rule implementation is discussed in Section 17.6.
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PRA Input to the Reactor Oversight Process The mitigating systems performance indicators (MSPI) are evaluated based on the indicators and methodologies defined in NEI 99-02 (Reference 201).
The Significance Determination Process (SDP) uses risk insights, where appropriate, to determine the safety significance of inspection findings.
PRA Input to the Reliability Assurance Program The PRA input to the Reliability Assurance Program is discussed in DCD Subsection 19.59.10.1.
PRA Input to the Regulatory Treatment of Nonsafety-Related Systems Programs The importance of nonsafety-related SSCs in the AP1000 has been evaluated using PRA insights to identify SSCs that are important in protecting the utilitys investment and for preventing and mitigating severe accidents. These investment protection systems, structures and components are included in the D-RAP/MR Program (refer to Subsection 17.4), which provides confidence that availability and reliability are designed into the plant and that availability and reliability are maintained throughout plant life through the maintenance rule. Technical Specifications are not required for these SSCs because they do not meet the selection criteria applied to the AP1000 (refer to Subsection 16.1.1).
MOV Program The MOV Program includes provisions to accommodate the use of risk-informed inservice testing of MOVs (Subsection 3.9.6).
19.59.11 REFERENCES Add the following text to the end of DCD Subsection 19.59.11:
201. NEI 99-02, Nuclear Energy Institute, Regulatory Assessment Performance Indicator Guideline, Technical Report NEI 99-02, Revision 5, July 2007.
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APPENDIX 19A THERMAL HYDRAULIC ANALYSIS TO SUPPORT SUCCESS CRITERIA This section of the referenced DCD is incorporated by reference with no departures or supplements.
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APPENDIX 19B EX-VESSEL SEVERE ACCIDENT PHENOMENA This section of the referenced DCD is incorporated by reference with no departures or supplements.
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APPENDIX 19C ADDITIONAL ASSESSMENT OF AP1000 DESIGN FEATURES This section of the referenced DCD is incorporated by reference with no departures or supplements.
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APPENDIX 19D EQUIPMENT SURVIVABILITY ASSESSMENT This section of the referenced DCD is incorporated by reference with no departures or supplements.
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APPENDIX 19E SHUTDOWN EVALUATION This section of the referenced DCD is incorporated by reference with no departures or supplements.
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APPENDIX 19F MALEVOLENT AIRCRAFT IMPACT This section of the referenced DCD is incorporated by reference with no departures or supplements.
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