ML12334A007

CALC-ANO2-CS-12-00002, Rev. 0, Arkansas Nuclear One Unit 2 Flooding Walkdown Submittal Report for Resolution of Fukushima Near-Term Task Force Recommendation 2.3: Flooding.

ML12334A007
Person / Time
Site:	Arkansas Nuclear
Issue date:	11/19/2012
From:	Dietz J Enercon Services
To:	Office of Nuclear Reactor Regulation
References
2CAN111202 CALC-ANO2-CS-12-00002, Rev 0
Download: ML12334A007 (19)

Text

Attachment 1 to 2CAN111202 ANO-2 Flooding Walkdown Report

Engineering Report Number CALC-ANO2-CS- 12-00002 Rev. 0 Page I of 17

.- Entergy ENTERGY NUCLEAR Engineering Report Cover Sheet Engineering Report

Title:

Arkansas Nuclear One Unit 2 Flooding Walkdown Submittal Report for Resolution of Fukushima Near-Term Task Force Recommendation 2.3: Flooding Engineering Report Type:

New [ Revision El Cancelled El Superseded 11 Applicable Site(s)

IPn El IP2 El IP3 El JAF El PNPS El vy El Wpo El ANOI E] ANO2 Z EC-Hl GGNS El RBS El WF3 El PLP El EC Number 40635 Report Origin: El Entergy Z Vendor Vendor Document Number: CALC-ANO2-CS- 12-00002 Quality-Related: [] Yes Z No Prepared by: ENERCON / Date.

Date: L/4,LLL?/2-l*

A Responsible Engineer (Print Name/Sign)

Design Verified/ N/A Design Verifier (if required) (Print Name/Sign)

Reviewed by: Chris Johnson / -- 7 , Date: I- Zl--IZ Reviewer (Print Name/Sign)

Reviewed by*: N/A Date:

ANII (if required) (Print Name/Sign)

Approved by: 'L c/ - Date:

upervi int Name/Sign) /

(§7~ CALC.ANO2-CS-12-0002 r.3ENERCON REV.0 E2nteWg3 Page 2of 17 ENGINEERING REPORT ARKANSAS NUCLEAR ONE UNIT 2 FLOODING WALKDOWN SUBMITTAL REPORT FOR RESOLUTION OF FUKUSHIMA NEAR TERM TASK FORCE RECOMMENDATION 2.3:

FLOODING Prepared By-. Date: +/-kzoo-,.L Jeff1leEnron Srce7,p Reviewed By: Date: 0A 04 J1eflfnsworth (Enercon Services)

Peer Reviewed ByQ.._- I Date:9 ( L'z Tom O'Reilly (Enercon Services)

Approved by: Atwood Browning (Enarconi~lwlce$) Date: 11-1_.

• l, CALC-ANO2-CS-1 2-00002 FI ENERCON _ REv.O Page 3 of 17 ANO Unit 2 Flooding Walkdown Submittal Report for Resolution of Fukushima Near-Term Task Force Recommendation 2.3: Flooding TABLE OF CONTENTS Section Title Page 1.0 SCOPE AND OBJECTIVE .................................................. 4 2.0 DESIGN BASIS FLOOD HAZARD LEVEL ........................... 5 2.1 Flood Hazards Identified ....................................................... 5 2.2 Assum ptions ......................................................................... 6 2.3 Methodology ....................................................................... ..6 2.4 Non Conform ance ............................................................... 6 3.0 EXTERNAL FLOOD PROTECTION AND MITIGATION FEATURES ......................................................................... 6 3.1 Flooding Licensing Basis ...................................................... 6 3.2 Flood Duration ..................................................................... . .7 3.3 Flood Protection Features ..................................................... 7 3.4 P rocedures ......................................................................... ..8 3.5 Adverse W eather .................................................................. 9 4.0 INTERNAL WARNING SYSTEMS ........................................ 9 4.1 Room Water Level Warning Systems ................................... 9 5.0 EFFECTIVENESS OF FLOOD PROTECTION SYSTEMS ........ 9 5.1 Acceptance Criteria ............................................................. 9 5.2 Discussion ....................................................................... . . 11 6.0 IMPLEMENTATION OF WALKDOWNS ............................. 13 6.1 NEI-12-07 Guidance ........................................................... 13 6.2 Team O rganization ............................................................. 13 6.3 Training Approach ............................................................. 14 7.0 WALKDOWN RESULTS .................................................... 14 7.1 Deficiencies ....................................................................... . . 14 7.2 O bservations ...................................................................... 15 7.3 Corrective Actions .............................................................. 15 7.4 Flood Protection Features not Inspected ............................. 15 8.0 AVAILABLE PHYSICAL MARGIN ..................................... 17 9.0 NEW FLOOD PROTECTION SYSTEMS ............................ 17

10.0 REFERENCES

.................................................................. 17 11.0 ATTACHMENTS ............................................................... 17

Engineering Report No. CALC-ANO2-CS-12-00002 Page 4 of 17 Revision 0 1.0 SCOPE AND OBJECTIVE This report was developed to provide information requested by the United States Nuclear Regulatory Commission (NRC) pursuant to Title 10 of the Code of Federal Regulations, Section 50.54(f) on March 12, 2012 for Arkansas Nuclear One (ANO)

Unit 2. In response to the NRC request, Entergy performed walkdowns to verify that plant features credited in the current licensing basis (CLB) for protection and mitigation from external flood events are available, functional, and properly maintained. The walkdowns were performed to verify that structures, systems, and components (SSCs), portable flood mitigation equipment, and the procedures needed to install and or operate them during a flood are acceptable and capable of performing their design function as credited in the CLB.

This report presents the findings of the flooding walkdown inspections completed at ANO Unit 2. The walkdowns were completed in accordance with the NRC endorsed guidance of NEI 12-07, Rev. OA, Guidelines for Performing Verification Walkdowns of Plant Flood Protection Featuresand Entergy Nuclear procedure EN-DC-170 that was developed to provide instructions for implementation of the NRC endorsed guidelines. The walkdowns completed at ANO Unit 2 were performed to verify that the structures, systems, and components (SSCs) credited for flood protection are capable of performing their design function as described in the current licensing, basis. The walkdowns were also used to verify that plant modifications implemented since original construction, such as changes to topography, do not adversely affect flooding protection.

This report identifies the flooding hazards that comprise the current licensing basis and the protection and mitigation features that are credited with preventing the ingress of external water into SSCs important to safety at ANO Unit 2. The effectiveness of the flood protection features is evaluated against a set of acceptance criteria. Results of the walkdowns, including key findings, available physical margin, and any identified degraded, or nonconforming conditions are addressed and a description of the actions taken or planned to address these conditions is provided.

Engineering Report No. CALC-ANO2-CS-12-00002 Page 5 of 17 Revision 0 2.0 DESIGN BASIS FLOOD HAZARD LEVEL The ANO Unit 2 Final Safety Analysis Report (FSAR) Sections 2.4 and 3.4 describe the external flood events postulated for the site and the design considerations/features used for protecting safety related equipment.

2.1 Flood Hazards Identified ANO Units 1 & 2 are adjacent nuclear plants located on a peninsula that extends into the Dardanelle Reservoir. The plant is centrally located on the peninsula with a grade elevation (near the center of the site) of 353 feet above mean sea level (MSL). The peninsula is about two miles wide and two miles long. The plant is surrounded on three sides by the Dardanelle reservoir. The shortest stretch of land is approximately one mile in a southeast direction. The ground surface surrounding the plant is predominantly meadow.

The Dardanelle Reservoir is part of the Arkansas River navigation project. The Dardanelle Dam impounds the Arkansas River, creating the Dardanelle Reservoir (also known as Lake Dardanelle). The dam is managed and controlled by the United States Army Corps of Engineers (USACE). The reservoir fluctuates between 336 feet (normal pool) and 338 feet (maximum controlled pool) above MSL. The upper end of the Dardanelle Reservoir lies beneath the Ozark Dam, which is approximately 51 miles upstream.

The safety-related structures, systems, and components at ANO Unit 2 are capable of withstanding the worst flooding caused by any of a number of hypothetical events. The Probable Maximum Flood (PMF) level is 358' MSL considering maximum probable flooding flows and a maximum flood level on the downstream side of the Ozark Dam. An instantaneous failure of the Ozark Dam coupled with the PMF results in a maximum potential flood level of 361' MSL. The effects of wind and wave action on a PMF event would add approximately 2.5' MSL to the PMF of 358' MSL, or approximately an effective 360.5' MSL flood level.

Therefore, the combined effects of wave action and PMF are bounded by the combination of a hypothetical Ozark Dam failure event and PMF event and thus the design flood elevation for ANO Unit 2 was determined to be 361' MSL.

According to the ANO Unit 2 FSAR, critical equipment and components are protected from splash effects up to 10 feet above PMF level of 358' MSL (i.e. 368' MSL) as follows: "...critical components and equipment are either protected or are located above Elevation 369 feet".

Groundwater intrusion into safety related structures is considered a credible source during flooding events. The design of the Seismic Class 1 structures considers the source as credible and provides protection against groundwater intrusion into these structures as low as the base grade level at elevation 317' MSL. Minor groundwater leaks are anticipated and discussed in the ANO Unit 2 FSAR.

The effects of local intense precipitation on the site are bounded by the hypothetical Ozark Dam failure event. The Auxiliary Building Roof is structurally designed to withstand roof ponding loads; the Auxiliary Building Roof drainage is sufficient to protect safety-related equipment; and the site drainage is not credited for flooding protection.

Engineering Report No. CALC-ANO2-CS-12-00002 Page 6 of 17 Revision 0 2.2 Assumptions No assumptions apply to establish a CLB threshold with respect to wind and waves. As discussed above, the effect of wind and waves were considered but were bounded by the combination of a PMF and Ozark Dam failure events and thus do not apply.

With the exception of watertight doors and hatches, the FSAR is silent with respect to non-piping penetrations being a credible flooding pathway. Therefore, it is assumed that when the FSAR refers to piping penetrations being sealed, it implicitly also includes conduit, HVAC, and other similar penetrations that pose a credible flooding pathway, and that they should be similarly sealed.

2.3 Methodology The PMF for the Arkansas River is estimated based upon the project flood defined by the USACE. USACE has computed the maximum probable flood flow at the Dardanelle Dam as 1,500,000 cubic feet per second. At this flow, the water level at the Dardanelle Dam would be 353 feet. The upper end of the Dardanelle Reservoir is at the Ozark Dam, about 51 miles upstream. During PMF conditions, the level of the Dardanelle Reservoir at the downstream side of Ozark Dam would be 389.5 feet. No profile for this condition is available, but it is reasonable to assume a straight-line variation. On this basis, the PMF level at the plant site is 358 feet.

Wind and wave activity are considered but are bounded by the possibility of a coincidental Ozark Dam failure with the PMF. For the purpose of the estimate of wind and wave activity, the results indicate an approximately 2.5' additional effective flood level and utilized a calculation input for wind speeds of 45 mph from the south west direction and a fetch of 18,000'.

Evaluation of the instantaneous and coincidental Ozark Dam failure with the PMF determines a theoretical water level rise of 6.8 feet, but then describes this outcome as "so unlikely as to be practically impossible." The estimate uses a uniform river channel assumption which is considered very conservative.

Furthermore, an additional 50 square miles of flood plain would be a consequence not accounted for in the original computations and it would result in a "great amount of extra storage". Thus the calculation estimates a 3 foot rise in flood elevation over the PMF level of 358' MSL. Thus the overall design basis for the ANO Unit 2 site was calculated to be 361' MSL.

2.4 Non Conformance No differences or contradictions in flood hazard levels were found in design or licensing basis documentation.

3.0 EXTERNAL FLOOD PROTECTION AND MITIGATION FEATURES 3.1 Flooding Licensing Basis The safety-related structures, systems, and components at ANO are designed to withstand the worst flooding caused by a combination of hypothetical events.

Engineering Report No. CALC-ANO2-CS-12-00002 Page 7 of 17 Revision 0 These events are the probable maximum flood of the Arkansas River coincident with the Ozark Dam failure.

Based on the current licensing basis at ANO, the current maximum design basis flood level is 361' MSL. Furthermore, critical components and equipment are protected by flood rated Seismic Class 1 structures or placed at elevations above 369' to protect against splash effects.

The following Seismic Category I structures are designed to withstand external flooding: Reactor Building, Auxiliary Building, Emergency Diesel Fuel Storage Vaults, and the Post Accident Sampling System (PASS) Building.

The Technical Specifications state that "Flood protection shall be provided for all safety-related systems, components and structures when the water level of the Dardanelle Reservoir exceeds 350 feet Mean Sea Level USGS datum, at the intake structure." It imposes the following action in order to meet the requirement:

With the water level at the intake structure above elevation 350 feet Mean Sea Level USGS datum, closure of the identified openings and penetrations is required to be initiated and complete within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.

The Technical Specifications state that the water level at the intake structure shall be monitored according to the level thresholds below:

a. Measurement at least once per 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> when the water level is below elevation 350 feet Mean Sea Level USGS datum, and

b. Measurement at least once per 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> when the water level is equal to or above elevation 350 feet Mean Sea Level USGS datum.

3.2 Flood Duration A total duration for the probable maximum flood of the Arkansas River coincident with the Ozark dam failure is given as lasting no more than a few days in the ANO Unit 2 plant's CLB.

3.3 Flood Protection Features Safety-related systems and components are flood protected either because of their location above the postulated maximum flood level, or because they are enclosed in reinforced concrete, Seismic Class 1 structures. The Seismic Class 1 structures that may be affected by a design basis flood at the site are designed to withstand the postulated floods for the site using the hardened flood protection approach.

The hardened protection approach means structural provisions are incorporated in the plant's design that will protect safety-related structures, systems, and components from the static and dynamic effects of a flood. As part of the hardened approach, watertight doors and equipment hatches as well as watertight piping and electrical penetrations are installed below the maximum flood level.

Each of the Seismic Class 1 structures discussed in Section 3.1 is protected by:

Wall thicknesses below flood level are a minimum of two feet.

Engineering Report No. CALC-ANO2-CS-12-00002 Page 8 of 17 Revision 0 Waterstops are provided in all construction joints below flood level.

The number of openings in walls and slabs below flood level are kept to a minimum.

Waterproof doors and equipment hatches are installed.

With respect to the Reactor Building, the Reactor Equipment Hatch and Escape Lock are double sealed openings. The Tendon Gallery Escape Hatch is protected using a water tight scuttle.

With respect to the Auxiliary Building, door openings are protected utilizing watertight doors; floor openings are protected utilizing watertight hatch covers; roof openings over underground vaults are protected utilizing concrete plugs with neoprene seals; conduit penetrations are externally and/or internally sealed, and pipe penetrations are protected utilizing rubber seals or closure plates.

With respect to the Emergency Diesel Fuel Storage Vault, door openings are protected utilizing watertight doors; roof openings are protected utilizing concrete plugs with neoprene seals; conduit penetrations are externally and/or internally sealed, and pipe penetrations are protected utilizing rubber seals or closure plates.

With respect to the PASS building, door openings are protected utilizing watertight doors; hatch openings are protected utilizing watertight hatch covers; conduit penetrations are externally and/or internally sealed; and pipe penetrations are protected utilizing rubber seals or closure plates.

Through wall leakage will be controlled by sumps and sump pumps. However, through wall leakage will be very small and the seepage into the Seismic Category 1 buildings would be of such minute quantity that the failure of the sump pumps would have no adverse effect on the flood protection of the buildings.

3.4 Procedures ANO's Unit 2 site adverse weather procedure describes the actions to be taken in the event of plant flooding caused by natural phenomena at the site. This procedure provides actions to be taken based on different levels of the Dardanelle Reservoir as measured at the Unit 2 Intake Structure. In order to maintain offsite power to the plant when flood levels exceed 356.5' MSL, temporary jumper cables are installed from the 161 kV Pleasant Hill transmission line to Startup Transformer

1. 2. The site adverse weather procedure not only addresses plant actions to address flooding, but also provides directions to mobilize outside parties to perform the jumper hookups. The Unit 2 site adverse weather procedure gives specific details for the verification and closure of the various openings and penetrations in the flood protected buildings.

ANO's site preventative maintenance procedures address the required maintenance for components, such as doors and hatches, that require procedural actions in order 'to maintain flood protection. The inspection interval of the doors and seals is not associated with a specific water level or flood situation, but is established as part of the maintenance work order planning system.

Engineering Report No. CALC-ANO2-CS-12-00002 Page 9 of 17 Revision 0 Entergy corporate procedures associated with condition monitoring of maintenance rule structures per 10 CFR 50.65 provide the programmatic instructions for preventative maintenance and surveillance for the Seismic Class 1 structures that are protected from flooding.

3.5 Adverse Weather In accordance with the current licensing basis, with the exception of the aforementioned temporary action to install jumpers from the 161 kV Pleasant Hill transmission line to the Startup Transformer #2, temporary active or passive flood protection measures are not required to be installed for protection of safety-related SSCs during flooding conditions at ANO Unit 2. Based on the current licensing basis, several Unit 2 doors are assumed to remain closed or be verified as closed during a flooding event. ANO's site adverse weather procedure provides instructions to verify and/or close the doors as part of the response in accordance with anticipated and measured flood levels. All doors, with the exception of the Emergency Diesel Fuel Vault doors, can be accessed without requiring personnel to travel outdoors. Therefore, only the Emergency Diesel Fuel Vault doors would require personnel to travel outside into potentially adverse weather conditions.

However, these doors are maintained in a normally closed position, thus, adverse weather impacts are not considered a credible hindrance to the flooding response.

4.0 INTERNAL WARNING SYSTEMS 4.1 Room Water Level Warning Systems No interior water level warning systems or alarms are credited for external flood protection in the plant's current licensing basis.

5.0 EFFECTIVENESS OF FLOOD PROTECTION SYSTEMS 5.1 Acceptance Criteria The flood protection features credited in the current licensing basis for Arkansas Nuclear One Unit 2 are incorporated active and passive features and include 14 doors and door seals, exterior structural walls, penetration seals through exterior walls, neoprene sealed hatches, and Reactor Building, Auxiliary Building and Tendon Gallery equipment and escape hatches. The site topography, and existing drainage ditches and culverts are not licensing basis credited features for flood protection although natural drainage patterns and drainage designs are consistent with ensuring that flood waters drain away from protected areas and that critical equipment and systems are in elevated areas where applicable. These flood protection features were visually inspected in accordance with the acceptance criteria described in Section 6 of the NEI 12-07 document and as discussed below.

ANO Unit 2 maintenance procedure for watertight doors was used as a reference to determine the acceptance criteria for the doors. Based on the instruction, the seals are to be installed between the door and the frame, with the seal being slightly compressed and maintaining solid contact at all locations. Therefore, with the door closed, the seal was visually inspected to ensure no gaps are seen between the seal and the door. The door was then opened to inspect the seal and ensure that no visible cracks or deterioration was present. The sealing

Engineering Report No. CALC-ANO2-CS-12-00002 Page 10 of 17 Revision 0 mechanisms and latches were inspected for functionality. The seal was determined to be acceptable if there appeared to be contact between the seal and door at all points, no degradation or deterioration on the seal was observed, and the seals on the doors were installed to an elevation that ensured the door was protected to the maximum-elevation of 361' MSL.

Seismic Class I structures at ANO Unit 2 are protected from the effects of a design basis flood based on the hardened flood protection approach and include the following structures: the Reactor Building, the Auxiliary Building, the Emergency Diesel Fuel Vault, and the PASS Building. The hardened approach requires structural provisions, such as watertight doors and penetrations to be incorporated into the plant design to protect safety-related structures, systems, and components from the effects of a flood. Based on the hardened approach the following Seismic Class I walls, including the associated penetrations, were required to be walked down as they were located on the exterior of the structure and were not shielded from potential flooding by other structures: the exposed Western portion of the Reactor Building at elevations 335' and 354'; the North, South, East and West exterior walls of the Auxiliary Building at elevations 317' 335' and 354'; the exterior North, South, East, West Walls and associated ground level covers of the Emergency Diesel Fuel Vault; and the exterior PASS building West wall at elevation 354' and East wall adjoining the Auxiliary Building at elevation 354'. The walls and penetrations act as an external flood barrier and prevent water intrusion into the structures.

Groundwater may be present near the ground surface; therefore, flooding sources from below the ground surface are considered. Seismic Class 1 structures are designed for flood protection above and below grade elevation 353' MSL. Exterior walls below grade were inaccessible from the outside; therefore, the walls were inspected from the interior.

Drainage characteristics associated with site topography are not a credited licensing basis feature. However topography was visually inspected against the ANO Site drainage drawings. The walkdowns visually verified that the topography of the site allowed water to drain as depicted in the drawings. Engineering changes including those completed for security reasons were reviewed to ensure that any obstructions or changes made to the site did not adversely impact site flooding protection.

Portions of the Unit 2 Service Water Intake Structure are Seismic Class 1 structures, but are not specifically discussed in the CLB as providing flooding protection. Walkdowns were completed in these areas to determine if critical components and equipment (those designated as Safety related) in these areas were adequately protected against flooding. The current structural design of the structures is considered sufficient to address the effects of run-up due to waves breaking at the plant. However, the water would be splashed to a height of about 10 feet above the static water level of 358 feet. For this condition, critical components and equipment are either protected or are located above Elevation 369 feet. Equipment housed within the Unit 2 Intake Structure building was walked down to determine if the equipment was above the CLB 361' MSL flood level, or whether the equipment was above the 369' elevation, or protected from splash effects.

Engineering Report No. CALC-ANO2-CS-12-00002 Page 11 of 17 Revision 0 Portions of the ANO Emergency Cooling Pond Intake and Discharge Structures are Seismic Class 1 structures, but are not specifically discussed in the CLB as providing flooding protection. These areas were walked down to ensure that protection was evident in the event flooding was to occur that might transport debris and render these systems inoperable due to blockage. The acceptance criteria for these features were to verify the presence of trash racks and debris blocking features.

Unit 2 Auxiliary Building sumps and sump pumps are a credited licensing basis flood protection feature. Therefore, sump pumps and level instrumentation were visually inspected in accordance with the acceptance criteria described in Section 6 of the NEI 12-07 document.

ANO's Unit 2 site adverse weather procedure provides the procedures and instructions for site responses to flooding events. As described in Section 3.4 of this report, the procedure provides the instructions to contact a third party to make jumper connections from the Pleasant Hill 161 kV transmission line to the Startup Transformer #2. Additionally, the time to complete closure of openings and penetrations was evaluated to ensure it could be completed in the required 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.

The site adverse weather procedure was tested step by step through posing questions to address the guidance found in section 5.5.6 of NEI 12-07. Namely:

1. Can the procedural step be executed as written?

2. Can any time dependent activities be completed in the time frame required?

3. Are specified equipment or tools properly staged and in good working order?

4. Will completion of the activity not be impeded by the flood event?

5. Is it certain that there is no over reliance on the staff and that the staff can complete the necessary steps?

The acceptance criteria are positive answers to the above questions against each procedural step.

All observations which were not immediately able to be judged as acceptable on the walkdowns were entered into the Arkansas Nuclear One Corrective Action Program to allow for a more detailed evaluation to be completed.

5.2 Discussion 5.2.1 Overall Effectiveness ANO Unit 2 is determined to have sufficient protection available at the site to ensure the safe operation of the plant in the event of an external flood based on the walkdowns completed at ANO Unit 2 and the results of the operability determinations associated with the observations that were entered into the site Corrective Action Program.

Engineering Report No. CALC-ANO2-CS-12-00002 Page 12 of 17 Revision 0

.Except as noted in Sections 7.1 and 7.2; Walls and penetrations located below the CLB flood level of 361' were walked down to ensure no credible flood pathways exist. No cracks or leaks which would allow credible flooding pathways of the structures were observed below the CLB 361' MSL elevation.

Doors and door seals were observed to ensure the proper operation of water tight doors, and were found to be in working order with proper seals, and that their function would not allow flooding of structures.

Site topography, although not a credited flood protection feature, was verified against site drainage drawings and was determined to not direct flood waters towards protected features.

Critical equipment and components installed in the Unit 2 Service Water Intake Structure Building were observed to be above CLB 361' MSL. Furthermore, they were confirmed to be splash protected.

The Emergency Cooling Pond Intake and Discharge structures were confirmed to have debris blocking features.

The Unit 2 Auxiliary Building sump pumps and level instrumentation were observed to be in working order and were verified as being maintained.

The reasonable simulations applied to the site adverse weather procedures confirmed that 5 guidance questions, per Section 5.5.6 of NEI 12-07, could be answered in the affirmative for each of the procedural steps.

During the walkdowns, conditions that did not meet the acceptance criteria discussed in Section 5.1 above were entered into the Corrective Action Program at ANO.

5.2.2 Other SSCs and Procedures Entergy corporate procedures associated with the Maintenance Rule Program provide the guidance and requirements for conducting a structural condition monitoring program to meet the requirements of 10 CFR 50.65. At ANO Unit 2, Maintenance Rule walkdowns are conducted a minimum of every five (5) years and are completed in accordance with the procedures. This program provides a systematic approach for evaluation of plant systems/structure which will provide a reasonable assurance that the structures are capable of fulfilling their intended 10CFR 50.65 functions. The program consists of periodic reviews of the condition of the plant structures via periodic inspections, routine walkdowns, surveillance tests, and ongoing review of the effect of the condition of plant structures on significant plant equipment. The program consists of defining and performing periodic structural evaluation which will ensure the timely identification, assessment, and repair of degraded structural elements. Concrete structures and penetration seals are inspected for cracking, spalling, erosion, corrosion of reinforcing bars, settlement, deformation, leaching, discoloration, groundwater leakage, rust stains, exposed rebar, rust bleeding, and other surface irregularities.

Engineering Report No. CALC-ANO2-CS-12-00002 Page 13 of 17 Revision 0 All flood barriers and seals, with the exception of the watertight doors, hatches and internal conduit seals, for structures were determined to be within the scope of the Maintenance Rule and are therefore examined in accordance with these procedures. Maintaining the structures and materials monitored under these procedures provides a reasonable assurance that those structures that fall under the program will be able to perform their intended function.

The Auxiliary Building and Emergency Diesel Fuel Vault are equipped with floor drainage systems. Water entering these structures would flow across sloped floors and enter the floor drainage systems to be collected in sumps at the bottom floor elevations. However, the CLB takes no credit for the lowering of water levels by the operation of the floor drainage system. The floor drainage system would assist in the lowering of water levels caused by in-leakage at ANO and would help prevent water from pooling inside structures.

6.0 IMPLEMENTATION OF WALKDOWNS 6.1 NEI-12-07 Guidance The verification walkdowns were performed in accordance with the NRC endorsed guidance of NEI 12-07, Rev. OA, "Guidelines for Performing Verification Walkdowns of Plant Flood Protection Features" dated May 31, 2012, and Entergy Nuclear procedure EN-DC-170 that was developed to provide instructions for implementation of the NRC endorsed guidelines. Additional guidance for implementation was also obtained from the Flooding Walkdown Frequently Asked Questions (FAQs) and NRC responses, which are based on discussions between NEI and the NRC.

The basis for establishing the walkdown scope and the flood protection features included the preparation of a walkdown list in accordance with the guidance provided in Section 4 of NEI 12-07. As part of this preparation, the current licensing basis was reviewed to determine the flood protection features and actions that are necessary to prevent an external flooding event at the site from adversely impacting safety-related SSCs. In addition to the identification of passive and active protection features, existing site and Entergy Corporate procedures were reviewed to determine if any procedures were necessary to ensure existing flood protection features would be functional in the event of a flood at the site.

Walkdown packages were prepared in accordance with the guidance provided in Section 5.2 and walkdown team personnel were selected based on the requirements provided in Section 5.3 of NEI 12-07.

Prior to each walkdown, a pre-job brief was conducted. All walkdown results were documented in accordance with the recommendations of Section 7 of NEI 12-07 and the Flooding Walkdown Record Form provided in Attachment 9.3 of EN-DC-170. The walkdown record form provided in Attachment 9.3 is consistent with the record form template provided in Appendix B of NEI 12-07.

6.2 Team Organization Consistent with Section 5.3 of NEI 12-07, the walkdown team consisted of two trained individuals with a complementary set of skills. The walkdown team

Engineering Report No. CALC-ANO2-CS-12-00002 Page 14 of 17 Revision 0 consisted of two degreed engineers (or equivalent) and had familiarity with the site.

The walkdown team was supplemented as required by plant maintenance and/or operations personnel.

6.3 Training Approach Consistent with Section 5.3 of NEI 12-07 and Section 4.1 of EN-DC-1 70, personnel selected to perform walkdown inspection activities were experienced and knowledgeable of the site current licensing basis. Personnel were also trained to perform the visual inspections and met the knowledge requirements specified in EN-DC-170 and Appendix C of NEI 12-07. Team members associated with the flooding walkdowns also satisfactorily completed the NANTEL Generic Verification Walkdowns of Plant Flood Protection Features lesson and were knowledgeable of the 50.54(f) letter dated March 12, 2012.

Plant maintenance and/or operations personnel who supplemented the walkdown teams did not need to be qualified to the aforementioned requirements.

7.0 WALKDOWN RESULTS A total of 80 work packages were associated with the walkdowns completed for ANO Unit 2, with each package containing a single feature. The features and attributes walked down as part of this package are broken down into flood protection type (incorporated passive, temporary passive, incorporated active, and temporary active) as shown in the table below.

Table #11: Summary - Features Included in the Walkdown Scope Flood Protection Type Total Number of Features Total Number of Attributes Passive - Incorporated 79 988 Passive - Temporary 0 0 Active - Incorporated 1 18 Active - Temporary 0 0 7.1 Deficiencies There were some observed conditions of features that did not meet the NEI 12-07 acceptance criteria. These conditions were entered into the Corrective Action Program; however, none of these observations were determined to be deficiencies as defined in NEI 12-07. The operability determinations for these conditions concluded that the feature could perform its intended flood protection function when subject to its design basis flooding hazard.

Engineering Report No. CALC-ANO2-CS-12-00002 Page 15 of 17 Revision 0 7.2 Observations All Condition Reports (CR's) that were written due to a potential deficiency on the site were input into the corrective action program and an operability determination associated with the potential deficiency was completed prior to this report being written. Based on the operability determinations associated with the CRs, none of the flooding conditions observed during the walkdowns were determined to pose a risk to the safe operation of the plant and no safety-related or safe-shutdown equipment is adversely impacted by these conditions.

7.3 Corrective Actions There were no observations identified that required actions to address a deficiency.

Since the CAP has determined that there are no deficiencies, there are no planned actions pending. However, the CAP did initiate a work order to repair a watertight door in order to restore available flood margin back to design conditions. The watertight door was observed to be in a degraded condition with an evident gap between the door and door seal at the top of the door. While the observation was not a deficiency, as the gap was above the CLB flood level of 361', the repair to the door will restore the door condition to non-degraded, so that full flooding margin is available.

7.4 Flood Protection Features not Inspected Room 2032 was determined to be inaccessible due to its high radiation fields. The southern wall of this room is considered a flooding barrier. No fire rated penetrations are noted in this southern wall. Because this room is considered to be inaccessible, it is evaluated for acceptance based on other conditions identified in the Unit 2 Auxiliary Building external flooding barriers.

If the worst conditions found in the balance of the Auxiliary Building were assumed to be applied in this area, the condition of the flood barrier would still be acceptable. Therefore, this wall is considered to be an acceptable external flooding barrier given the similar inspections performed on the concrete reinforced walls for the Unit 2 Auxiliary Building external flooding barriers. This evaluation complies with the guidance given in NEI 12-07, that evaluations can use as a rationale:

"inspection of justifiably similar installations that are accessible and materials of construction."

A number of features were considered restricted access and were unavailable for inspection. Each of these features has been documented in the site CAP as requiring walkdown at a later date.

Engineering Report No. CALC-ANO2-CS-12-00002 Page 16 of 17 Revision 0 Table #2: - Restricted Access Features Unit 2 Restricted Access Listing Restricted Access Area & Features Reason Means to Address Unit 2 Aux Building Room 2009 No readily available means CAP to address (elevator Shaft) EL 317 - Required to of egress. Entry requires walkdown no later than verify Walls and Penetrations coordinated efforts with Sept. 30, 2013 safety, radiation protection and electrical craft.

Unit 2 Aux Building Room 2001 & Locked High Radiation CAP to address 2002 El 317 - Required to verify Areas walkdown no later than Walls and Penetrations Sept. 30, 2013 Penetrations - 2019-03-0007, 0008, Junction boxes are to be CAP to address 0009, 0010 (Located on Turbine opened and are above floor walkdown no later than Building wall - El 352' above the 335 level 16-18 feet. Craft was Sept. 30, 2013 deck) Room 2019 - Need to evaluate unable to open within the conduit internal seals time frame of the walkdowns. Scaffolding is required to complete inspections.

Unit 2 Aux Building Tank Vaults Restricted hatch access CAP to address Rooms 2020A, 2020B, 2020C, and High Radiation Area. walkdown no later than 2020D El 335 - Required to verify This requires coordination Sept. 30, 2013 Walls and Penetrations with safety, radiation protection and mechanical craft.

Unit 2 Aux Building Pens 2279-0021 Craft was unable to open CAP to address and 0022 EL 354 - Junction Boxes within the time frame of the walkdown no later than are to be opened to look at internal walkdowns Sept. 30, 2013 conduit seals Unit 2 Aux Building EL 335' Room Observation of these CAP to address 2055 - Penetration #'s 2055-07-, penetrations was impeded walkdown no later than 0303 and 0304. by ability to gain viewpoint Sept. 30, 2013 due to contaminated equipment interferences.

Penetrations require scaffolding to inspect.

Unit 2 Manhole 2MH03 (Yard) - Craft was unable to open CAP to address Required to verify conduit internal within the time frame of the walkdown no later than seals walkdowns. Inspections will Sept. 30, 2013 requires safety coordination due to 4160 V cable runs.

Engineering Report No. CALC-ANO2-CS-12-00002 Page 17 of 17 Revision 0 8.0 AVAILABLE PHYSICAL MARGIN As indicated in Section 3.12 of NEI 12-07, Rev. 0A, the NRC is no longer expecting the Recommendation 2.3: Flooding Walkdowns to include an evaluation of the cliff-edge effects at the site. The available physical margin (APM) has been determined and documented on the walkdown record forms. The APMs provided on the walkdown record forms will allow flood hazard reevaluations completed in response to Recommendation 2.1: Flooding to be completed.

With the exception of the watertight door mentioned in Section 7.3, no small APMs were documented in the walkdown record forms for ANO Unit 2. A repair work order has been initiated to restore the watertight door to a non-degraded condition. Upon completion of this work order there will be no small APM instances at ANO Unit 2.

9.0 NEW FLOOD PROTECTION SYSTEMS There are no planned or newly installed flood protection systems or flood mitigation measures at ANO Unit 2.

10.0 REFERENCES

10.1 NRC Letter to Licensees, dated March 12, 2012, "Request for Information Pursuant to Title 10 of the Code of Federal Regulations 50.54(f) Regarding Recommendations 2.1, 2.3, and 9.3 of the Near Term Task Force Review of Insights from the Fukushima Daiichi Accident" 10.2 Guidelines for Performing Verification Walkdowns of Plant Flood Protection Features, NEI 12-07, Rev. OA, dated May 2012.

10.3 EN-DC-1 70, "Fukushima Near Term Task Force Recommendation 2.3 Flooding Walkdown Procedure 10.4 ANO Unit 2, Final Safety Analysis Report, Amendment 24 10.5 ANO Unit 2, Technical Specifications 11.0 ATTACHMENTS None