ML13200A396
| ML13200A396 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 07/19/2013 |
| From: | Point Beach |
| To: | NRC/RGN-III |
| References | |
| EA-13-125 | |
| Download: ML13200A396 (30) | |
Text
Point Beach Nuclear Plant Regulatory Conference July 22, 2013
Opening Remarks Larry Meyer Site Vice President 2
Agenda
- Opening Remarks - Larry Meyer
- Performance Deficiency - Rich Wright
- Point Beach Postulated Flooding Overview - Rich Wright
- Engineering Analyses - Rudy Gil
- Risk Significance - Anil Julka
- Station Response - Steve Bowe
- Conclusions - Rich Wright
- Closing Remarks - Larry Meyer 3
4 5
Attendees
- Larry Meyer, Site Vice President
- Rich Wright, Plant General Manager
- Rudy Gil, Corporate Engineering Manager
- Steve Bowe, Operations Shift Manager
- Anil Julka, Fleet Risk and Reliability Manager
- Steve Catron, Fleet Licensing Manager
- Ron Seizert, Site Licensing Supervisor
- Jim Petro, Managing Attorney - Nuclear
- Sandy Dinzeo, Enercon Engineering Lead
- Jemie Dababneh, Rizzo Associates Technical Director 6
Performance Deficiency Rich Wright Plant General Manager 7
Performance Deficiency
- Licensee failed to establish procedural requirements to implement external flooding wave run-up protection design features as described in the FSAR.
- Cause Analysis
- In 1996 we changed our strategy for flood barrier protection
- Installation of barriers was not required to be validated by procedure
- Corrective Actions
- Barrier installation requires validation process
- Location was improved with new concrete pads and berms 8
9 Engineering Rudy Gil Corporate Engineering Manager 10
Engineering Analyses
- Performed detailed storm surge/wave run-up analyses
- Analyses start with same lake still water level established in the IPEEE
- DELFT3D model was used to calculate the storm surge level at the site due to wave effects
- The water level at the Turbine Building, including wave effects, is calculated using FEMA and USACE formulae
- Analyses performed by experienced vendor and independently reviewed by third party expert Rigorous analyses determined the water level at the Turbine Building; provides appropriate technical input for risk significance determination 11
Engineering Analyses
- Review of analysis model (DELFT 3D)
- DELFT3D is a sophisticated modeling software used in the US and more than 70 countries world-wide
- DELFT3D has been rigorously validated against hydraulic lab testing and compared to field observations
- Has been used for six separate site COLA evaluations and is currently being used for Fukushima flooding reevaluations
- The model was thoroughly validated to ensure stability; over 40 runs with varying inputs show consistent results
- The model incorporates actual verified topographic and bathymetric site configuration The software used for the analysis is well recognized and has undergone rigorous benchmarking 12
Engineering Analyses
- Analyses inputs and assumptions
- Deep water wave characteristics that produce the highest wave effects were used
- 40 iterations run by varying starting lake level, wind direction, wave period, and barrier configuration
- The maximum model output near the Turbine Building was used to determine the average water based on run-up
- Yard drains capable of draining water back to the Lake are assumed blocked.
Analyses use conservative inputs and assumptions to maximize wave effect at the site 13
Engineering Analyses Storm Surge/Wave Run-up Analyses Comparison to IPEEE Parameter IPEEE Updated Analyses Still Lake Water Level 587 ft 587 ft State of the Art Model Storm Surge Model Approximate calculations (DELFT3D)
FEMA and USACE Average Water Level at TB Conservative Estimates calculation methods Conservative estimate of Actual Bathymetric /
Shoreline Topography lake bottom Topographic Survey Data 3 different directions; Wind directions and speed Not provided most conservative used speed bounded Rip rap (Considered, but Rip rap Wave Protection Features not modeled) Discharge flumes 14
Engineering Analyses The 4.2E-6 event results in < 4 of water outside the Turbine Building; at higher frequencies no water reaches the Turbine Building 15
Engineering Analyses
- Conclusions
- The updated analyses provide the appropriate information for assessing the significance of the degraded flood barrier performance deficiency
- The results of the updated analyses show that the water level outside of the Turbine Building would be less than 4
- The equipment impacted by this water level for the PRA would be the Residual Heat Removal system
- Although the calculated water levels at the Turbine Building are assumed to immediately equal water levels inside the building, analyses show that the transition is relatively slow Revised rigorous analyses conclude that the effects of the external flooding event are less severe than those estimated in the IPEEE 16
Risk Significance Anil Julka Nuclear Risk and Reliability Manager 17
Beneficial Risk-Significant Plant Improvements
- Risk Significant Changes
- Added two additional emergency diesel generators at elevation 608.2 ft
- Relocated B-Train 4,160 V switchgear to elevation 608.2 ft
- Added two additional battery banks at elevation 606.2 ft
- Added three additional battery chargers at elevation 606.2 ft
- Added two additional 125 VDC distribution panels at elevation 606.2 ft 18
Historical Internal Events CDF Risk Profile
- Significant Improvements in Plant Design as Measured by the Internal Events CDF 1.5E-04 Direction of 1.4E-04 Plant used in Decreasing IPE and Risk 1.3E-04 IPEEE.
1.2E-04 Added two new 1.1E-04 Emergency Diesel Added two new New plant data MDAFPs, 24-hr air Core Damage Frequency (/yr)
Generators 1.0E-04 update (reliability on AFW pump mini-Added backup recirc valves, and air-9.0E-05 cooled service air air/N2 to AFW 8.0E-05 pump mini-recirc Various model changes to more 7.0E-05 accurately New plant data 6.0E-05 update (reliability and 5.0E-05 unavailability).
RG 1.200 model.
4.0E-05 3.0E-05 2.0E-05 1.0E-05 0.0E+00 1990 1993 1996 2001 2002 2004 2005 2006 2007 2008 2009 2011 2013 19
Inputs to PRA Evaluation
- Annual Flood Exceedance Frequency
- Used annual flood exceedance frequencies based on still water elevations from IPEEE
- Wave Run-up
- Calculated water levels at the turbine building based on updated engineering analyses
- Equipment Impacted
- Detailed assessment to identify flood heights in plant where equipment is wetted and assumed to fail
- Calculated change in risk (with and without barriers protecting to 589.2 ft. IGLD-1955) 20
Inputs to PRA Evaluation Starting Still Water Lake Level Calculated Water Level at Turbine Building Turbine Building Floor NRC Value Used in SDP Direction of 591.0 Increasing Frequency 590.0 NRC Value Calculated Water Used in SDP 589.0 Level at Turbine Building Turbine Building Floor 588.0 Elevation (ft, IGLD-1955) 587.0 587.0 586.0 585.0 Starting Still Water Lake Level 584.0 7.3E-4 583.0 4.2E-6 5.4E-5 1.4E-2 9.9E-7 582.0 1.0E-07 1.0E-06 1.0E-05 1.0E-04 1.0E-03 1.0E-02 1.0E-01 Flood Frequency (/yr) 21
PRA Evaluation Results
- By incorporating the calculated wave run-up analyses into our evaluation, the significance of this issue has lowered
- Updated PRA evaluation more precisely evaluates risk by calculating CCDP and CDF at various flood levels and summing all the CDFs
- The results are as follows:
Without Barriers With barriers CDF (/yr) CDF (/yr) CDF (/yr) 2.83E-07 2.76E-07 7.E-09 22
Conclusions of PRA Evaluation
- Overall risk from external flooding event is very low
- Calculated External flood CDF is 2.83E-07 /yr.
- Change in risk with and without barriers is very low
- Calculated external flood CDF is 7E-09 /yr.
Updated rigorous analyses show CDF result to be of very low safety significance 23
Operations Response Steve Bowe Operations Shift Manager 24
Station Response
- Operations Actions vs. Lake Level
- Weather Conditions are monitored daily by the Shift Technical Advisor and entered into Safety Monitor
- Weekend look ahead by Work Week Manager for weather impact on Safety Monitor
- Procedurally directed Monthly Recording of Lake Level per PC 80 Part 7 Lake Level Determination 25
Station Response
- Postulated Lake Level rises to (580.7)
- Per PC 80 Part 7 Jersey Barriers are installed
- Administrative Procedures and Programs entered
- If Lake Level Rises to the License Basis Lake Level (581.9)
- Both units will be shutdown
- Operations Response to Degraded Barriers
- Alarm Response procedures would direct operator actions for internal/external flooding
- Operators are procedurally directed to respond to degraded barriers and internal/external flooding that has the potential to cause degraded equipment 26
Changes in Station Response
- Abnormal Operating Procedure AOP-13C, for Severe Weather
- Modified Jersey Barrier installation 27
Conclusion Rich Wright Plant General Manager 28
Conclusion
- NextEra accepts the performance deficiency and understands the importance of protecting the plant from the effects of flooding:
- The procedure was lacking and NextEra owns that performance
- The learning from this process has been extremely valuable to NextEra
- NextEra has conducted updated analyses including:
- Water levels inside and outside the turbine building
- Site features, equipment impacted, and updated PRA evaluations
- Based on the results of our analysis of this issue, NextEra concludes that the safety significance is very low.
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Closing Remarks Larry Meyer Site Vice President 30