RA-12-117, Company, Llc'S 180-Day Response to NRC Request for Information Pursuant to 10 CFR 50.54(f) Regarding the Flooding Aspects of Recommendation 2.3 of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident

Company, Llc'S 180-Day Response to NRC Request for Information Pursuant to 10 CFR 50.54(f) Regarding the Flooding Aspects of Recommendation 2.3 of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident

ML12331A203
Person / Time
Site:	Oyster Creek
Issue date:	11/19/2012
From:	Jesse M Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
RA-12-117, RS-12-178
Download: ML12331A203 (57)

Text

1 Exelon Generation 10 CFR 50.54(f)

RS-12-178 RA-12-117 November 19, 2012 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk 11555 Rockville Pike Rockville, MD 20852 Oyster Creek Nuclear Generating Station Renewed Facility Operating License No. DPR-16 NRC Docket No. 50-219

Subject:

Exelon Generation Company, LLC's 180-day Response to NRC Request for Information Pursuant to 10 CFR 50.54(f) Regarding the Flooding Aspects of Recommendation 2.3 of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident

References:

1. NRC Letter, 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 Dai-ichi Accident, dated March 12, 2012

2. Exelon Generation Company, LLC's gO-day Response to NRC Request for Information Pursuant to 10 CFR 50.54(f) Regarding Recommendations 2.1 and 2.3, of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident (Flooding), dated June 11 , 2012

3. NRC Letter, Endorsement of Nuclear Energy Institute (NEI) 12-07, "Guidelines For Performing Verification Walkdowns of Plant Flood Protection Features," dated May 31 , 2012 On March 12, 2012, the Nuclear Regulatory Commission (NRC) issued Reference 1 to all power reactor licensees. Enclosure 4 of Reference 1 contains specific Requested Actions, Requested Information, and Required Responses associated with Recommendation 2.3 for Flooding. On June 11, 2012, Exelon Generation Company, LLC (EGC) submitted the 90-day response (Reference 2) requested in Enclosure 4 of Reference 1, confirming that EGC would use the NRC-endorsed flooding walkdown procedure.

u.s. Nuclear Regulatory Commission 180-Day Response to 50.54(f) Letter NTTF Recommendation 2.3: Flooding November 19, 2012 Page 2 For flooding Recommendation 2.3 (walkdowns), Enclosure 4 of Reference 1 states that within 180 days of the NRC's endorsement of the walkdown process (Reference 3), each addressee will submit a final response, including a list of any areas that are unable to be inspected due to inaccessibility and a schedule for when the walkdown will be completed. This letter provides the Oyster Creek Nuclear Generating Station (OCNGS) 180-day response to Reference 1 for Flooding Recommendation 2.3.

Conditions identified during the walkdowns were documented and entered into the corrective action program. to this letter provides the requested information for OCNGS and references the current UFSAR. On October 29,2012 Oyster Creek and the surrounding area was impacted by the effects of Hurricane Sandy. This large storm resulted in the area reaching and exceeding historical records for local flooding levels. The current UFSAR description will be revised in the next periodic update to incorporate the flooding information obtained during the storm into the station's UFSAR.

This letter contains new regulatory commitments, which are identified in Enclosure 2.

Should you have any questions concerning the content of this letter, please contact Ron Gaston at (630) 657-3359.

I declare under penalty of perjury that the foregoing is true and correct. Executed on the 19th day of November 2012.

Respectfully, Michael D. Jesse Director - Licensin egulatory Affairs Exelon Generation ompany, LLC

Enclosures:

1. Flooding Walkdown Report In Response To The 50.54(f) Information Request Regarding Near-Term Task Force Recommendation 2.3: Flooding for the Oyster Creek Nuclear Generating Station

2. Summary of Regulatory Commitments

u.s. Nuclear Regulatory Commission 180-Day Response to 50.54(f) Letter NTTF Recommendation 2.3: Flooding November 19, 2012 Page 3 cc: Director, Office of Nuclear Reactor Regulation Regional Administrator - NRC Region I NRC Senior Resident Inspector - OCNGS NRC Project Manager, NRR - OCNGS Director, Bureau of Nuclear Engineering - New Jersey Department of Environmental Protection Mayor of Lacey Township, Forked River, NJ

u.s. Nuclear Regulatory Commission 180-0ay Response to SO.S4(f) Letter NTTF Recommendation 2.3: Flooding November 19, 2012 Page 5 Enclosure 1 Flooding Walkdown Report In Response To The 50.54(f) Information Request Regarding Near-Term Task Force Recommendation 2.3: Flooding for the Oyster Creek Nuclear Generating Station (52 pages)

NTTF Recommendation 23 (Walkdowns): Roodlng Exelon Corporation October 31, 2012 Revision 0 FLOODING WALKDOWN REPORT IN RESPONSE TO THE SO.S4(f) INFORMATION REQUEST REGARDING NEAR-TERM TASK FORCE RECOMMENDATION 2.3: FLOODING for the OYSTER CREEK NUCLEAR GENERATING STATION Route 9 South PO Box 388 Forked River, New Jersey, 08731 FadlltJOperating License No. DPR-16 NRC Docket No. SO-219 1

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Exelon Generation Company, LLC 300 Exelon Way Kennett Square, PA 19348 Prepared by:

ENERCON 400 Valley Rd Suite 301 Mount Arlington, New Jersey 07856 October 31,2012 Prlntld Namel11tl~ Afflllill2D .tlm Preparer: Julien Abramovlcl ENERCON 10/31/2012

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Reviewer: Christopher Prather ENERCON 10/31/2012 Approver: RaySacramo ENERCON 10/31/2012 Lead Responsible Engineer: Ruben Martinez EXELON ID/!/I'lIJ/2-Branch Manager Ralph Larzo EXELON

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Senior Manager Design EXELON Engineering:

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/tJ!?!egl Corporate Acceptance: Joseph V. Bellini EXELON

• 11/01/2012 Pasel

NTIF Recommendation 2.3 (Walkdowns): Flooding Exelon Corporation October 31, 2012 Revision 0 Contents

1. EXECUTIVE

SUMMARY

............................................................................................................................... 3

2. PURPOSE .................................................................................................................................................... 4

a. Background ............................................................................................................................................... 4

b. Site Description ........................................................................................................................................ 5

c. Requested Actions ................................................................................................................................... 6

d. Requested Information ............................................................................................................................ 6

3. METHODOLOGy ......................................................................................................................................... 7

a. Overview of NEI12-07 (Walkdown Guidance) ................................................................................... 7

b. Application of NEI12-07 .......................................................................................................................... 8

c. Reasonable Simulations ........................................................................................................................ 10

d. Walkdown Inspection Guidance ............................................................................................................ 11

4. RESUlTS .................................................................................................................................................... 11

a. Requested Information Item 2(a) - Design Basis Flood Hazards ..................................................... 11

b. Requested Information Item 2(b) - ClB Protection and Mitigation Features ....................................... 16

c. Requested Information Item 2(c) - Flood Warning Systems ................................................................ 18

d. Requested Information Item 2(d) - Flood Protection System/Barrier Effectiveness ........................... 18

e. Requested Information Item 2(e) -Implementation of Walkdown Process ....................................... 20

f. Requested Information Item 2(f) - Findings and Corrective Actions Taken/Planned ......................... 20

g. Requested Information Item 2(g) - Cliff-Edge Effects and Available Physical Margin .......................... 24

h. Requested Information Item 2(h) - Planned/NewlY-Installed Flood Protection ................................. 24

5. CONClUSiONS .......................................................................................................................................... 24

6. REFERENCES ............................................................................................................................................. 51 Page 2

NTTF Recommendation 2.3 (Walkdowns): Flooding Exelon Corporation October 31, 2012 Revision 0

1. EXECUTIVE

SUMMARY

This Flooding Walkdown Report provides the Oyster Creek Nuclear Generating Station (OCNGS) response to the March 12, 2012 10 CFR50.54(f) letter concerning the Near Term Task Force (NTTF) review of the accident at the Fukushima-Dai-ichi nuclear facility, Recommendation 2.3 Flooding. To address Recommendation 2.3, walkdowns were performed 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 OCNGS credited flood protection system does not require the implementation of procedures involving manual actions so no reasonable simulations were required.

The effort was accomplished by following the guidance in NEI 12-07, Rev. O-A, "Guidelines for Performing Verification Walkdowns of Plant Flood Protection Features". The ClB flood levels were identified and then plant features credited in the ClB to protect against the flood level and/or mitigate the flood were identified. The features include passive items such as walls, doors, and penetration seals. Walkdown packages were assembled for each feature to identify its location, critical characteristics, and acceptance criteria in order to be properly prepared for the visual inspection performed on the walkdown.

The scope of the OCNGS walkdowns included a visual inspection of all features currently credited for protection from external floods. The features provide the external flood barrier for the Reactor Building, Turbine Building, and the Emergency Diesel Generator (EDG) Building.

The visual inspections revealed that the majority of the features met the acceptance criteria. Features not immediately judged to be acceptable were entered into the Corrective Action Program (CAP) and/or correlated to an existing action request addressing flooding concerns. For those features classified as inaccessible, reasonable assurance based on available visual observations that these Items could perform their flood protection function was provided on the individual walkdown record forms. 421 features were included in the walkdown scope.

• 225 of these features met the acceptance criteria. See Table 3, Section 5.

• 120 features were classified as restricted access and were deferred to the upcoming October 2012 lR24 Refueling Outage. See Table 5, Section 5.

• 47 features were determined to be inaccessible. See Table 6, Section 5.

• 36 features could not be immediately judged acceptable and were entered in the CAP system. 12 Incident Reports (IRs) were written to document and evaluate these observations. See Table 4, Section 5.

Of the 36 features with observations, 22 were identified as deficient by site CAP. 2 roof drains and 1 scupper at 46' on the Turbine building were observed to be partially obstructed by debris. 2 penetrations were observed to have cut, uncapped conduit pipe. Those five deficiencies are scheduled to be resolved by 11/27/2012.

17 conduit penetrations associated with the EDG cables show evidence of water leakage. These observations were entered into CAP, and it was determined that the penetrations are deficient by the standards of the ClB. Water ingress rate is negligible, and sealing the conduits would extend the exposure of safety related cables to ground water. Therefore, the penetrations were deemed acceptable. See section 4(f) for details.

Page 3

NTTF Recommendation 2.3 (Walkdowns): Flooding Exelon Corporation October 31, 2012 Revision 0 It was determined that inspecting electrical conduits in manholes and tunnels in the yard was unnecessary for OCNGS. Internal conduit and external penetration seals create a flood barrier at the walls of the Turbine and Reactor Buildings, therefore conduits and penetrations need not be inspected in manholes or tunnels. See section 4(d) for more information.

2. PURPOSE

a. Background In response to the nuclear fuel damage at the Fukushima-Dai-ichi power plant due to the March 11, 2011 earthquake and subsequent tsunami, the United States Nuclear Regulatory Commission (NRC) established the Near Term Task Force (NTTF) to conduct a systematic review of NRC processes and regulations, and to make recommendations to the Commission for its policy direction. The NTTF reported a set of recommendations that were intended to clarify and strengthen the regulatory framework for protection against natural phenomena.

On March 12, 2012, the NRC issued an information request pursuant to Title 10 of the Code of Federal Regulations, Section 50.54 (f) (10 CFR 50.54(t) or 50.54(f)) (Reference 3) which included six (6) enclosures:

(1) [NTTF1 Recommendation 2.1: Seismic (2) [NTTF1 Recommendation 2.1: Flooding (3) [NTTF1 Recommendation 2.3: Seismic (4) [NTIF1 Recommendation 2.3: Flooding (5) [NTIF1 Recommendation 9.3: EP (6) licensees and Holders of Construction Permits In Enclosure 4 of Reference 3, the NRC requested that licensees 'perform flood protection walkdowns to identify and address plant-specific degraded, nonconforming, or unanalyzed conditions and cliff-edge effects (through the corrective action program) and verify the adequacy of monitoring and maintenance procedures'. (See note below regarding 'cliff-edge effects'.)

Structures, Systems, and Components (SSCs) important to safety are designed either in accordance with, or meet the intent of, Appendix A to 10 CFR Part 50, General Design Criteria (GDC) 2. GDC 2 states that SSCS important to safety at nuclear power plants must be designed to withstand the effects of natural phenomena, including floods, without loss of capability to perform their intended safety functions. For flooding walkdowns, identifying/addressing plant-specific degraded, nonconforming, or unanalyzed conditions (through the corrective action program) and verifying the adequacy of monitoring and maintenance procedures is associated with flood protection and mitigation features credited in the current design/licensing basis. New flood hazard information will be considered in response to Enclosure 2 of Reference 3.

On behalf of Exelon Generation Company, LLC (Exelon), this report provides the information requested in the March 12, 2012, 50.54(t) letter; specifically, the information listed under the 'Requested Information' section of Enclosure 4, paragraph 2 ('a' through 'h'). The 'Requested Information' section of Enclosure 4, paragraph 1 ('a' through 'j'), regarding flooding walkdown procedures, was addressed via Exelon's June 11, 2012, acceptance (Reference 1) of the industry walkdown guidance (Reference 2).

Page 4

Nm Recommendation 2.3 (Walkdowns): Flooding Exelon Corporation October 31, 2012 Revision 0 Note Regarding Cliff-Edge Effects Cliff-edge effects were defined by the NTIF Report (Reference 5), which noted that 'the safety consequences of a flooding event may increase sharply with a small increase in the flooding level'. While the NRC used the same term as the NTIF Report in the March 12, 2012 50.54(f) information request (Reference 3), the information the NRC expects utilities to obtain during the Recommendation 2.3: Flooding Walkdowns is different. To clarify, the NRC is now differentiating between cliff-edge effects (which are dealt with under Enclosure 2 of Reference 3) and a new term, Available Physical Margin (APM). APM information will be collected during the walkdowns, but will not be reported in the response to Enclosure 4 of Reference 3. The collected APM information will be available for use in developing the response to of Reference 3.

b. Site Description Oyster Creek Nuclear Generating Station is located in Lacey Township, New Jersey, roughly 9 miles south of Toms River and 50 miles east of Philadelphia, Pennsylvania. The site is adjacent to Oyster Creek, about two miles inland from the shore of Barnegat Bay. Because of the shallowness of Barnegat Bay, normal tidal fluctuations of water level in Oyster Creek are only 0.5 feet, on a 12.7 hour8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br /> tidal cycle. The site is located directly west of US route 9 (at 19' MSL).

The plant site is about 10 acres in size, and is mostly covered in buildings, roads, and other structures. Plant grade around safety related buildings is 23' MSL. The exact topography is such that water on site flows from the center of the island towards the intake canal to the north and west, the discharge canal to the south and west, and Route 9 to the east. The entrances to all site buildings with the exception of the Emergency Diesel Generator Building (EDG Building) are at 23.5'. The entrances to the EOG Building are at 23', with dikes around the building entrances up to elevation 23.5'. The Reactor Building and Turbine Building are located in the center of the site, with the EOG Building to the southwest, near the discharge canal.

The current licensing basis includes two bounding floods, the Probable Maximum Hurricane (PMH) and the Probable Maximum Precipitation (PMP). The chances of a tsunami affecting the plant site were considered to be insignificant in the CLB. Dam failure was evaluated and no flooding which would affect safety related structures was postulated for the site. The effects of probable ice blockage on plant safety related SSCs were deemed insignificant. As stated in the UFSAR, section 2.4, the greatest flood level ever recorded at plant site was 4.5' feet MSL in 1962, prior to plant construction.

The PMH postulated for OCNGS is evaluated in UFSAR section 2.4, Appendix A. The hurricane considered is a Category 4 storm with wind speeds of 133 mph, a forward speed between 12 knots and 23 knots, occurring along with an astronomical high open-ocean tide of 2.7' MSl. This storm results in a storm surge still water level of 22' MSL, with waves at plant site of up to l' high. The main plant grade is at 23' MSl.

The PMP event postulated for OCNGS was evaluated most recently in the site Individual Plant Examination of External Events (IPEEE) Request for Additional Information (RAI) response (Reference 37). The site was divided up into nine watersheds, two of which were postulated to have significant ponding. The Reactor Building sits in these areas, but neither the Turbine Building nor the EDG Building do. Onsite water levels were calculated to be 23.6' immediately adjacent to the Reactor Building and 23.5' over the remainder of the site. The PMP is not assumed to occur coincidental to the PMH.

Page 5

NTIF Recommendation 2.3 (Walkdowns): Flooding Exelon Corporation October 31, 2012 Revision 0 Site topography has changed since the IPEEE RAI PMP calculation, with security features added, new buildings constructed, and a wall installed around the EDG Building. Not all of these new changes have been evaluated for impact on site runoff, so a new site drainage calculation is being prepared (see IR 01404344).

Power and control cables run from the EDG Building to the Southwest Corner of the Turbine Building.

These cables are in concrete duct banks buried below grade. Cables are designed to be water resistant, and the conduits and penetrations were designed to include seals.

c. Requested Actions Per Enclosure 4 of Reference 3, the NRC requests that each licensee confirm use of the industry-developed, NRC-endorsed, flood walkdown procedures or provide a description of plant-specific walkdown procedures.

In a letter dated June 11, 2012 (Reference 1), Exelon confirmed that the flooding walkdown procedure (Reference 2), endorsed by the NRC on May 31, 2012, will be used as the basis for the flooding walkdowns.

Other NRC's requested actions include:

(1) Perform flood protection walkdowns using an NRC-endorsed walkdown methodology; (2) Identify and address plant-specific degraded, nonconforming, or unanalyzed conditions, as well as, cliff-edge effects through the corrective action program, and consider these findings in the Recommendation 2.1 hazard evaluations, as appropriate; (3) Identify any other actions taken or planned to further enhance the site flood protection; (4) Verify the adequacy of programs, monitoring and maintenance for protection features; and (5) Report to the NRC the results ofthe walkdowns and corrective actions taken or planned.

Per Enclosure 4 of Reference 3 also states, 'If any condition identified during the walkdown activities represents a degraded, nonconforming, or unanalyzed condition (i.e. noncompliance with the current licensing basis) for an SSC, describe actions that were taken or are planned to address the condition using the guidance in Reference 6, including entering the condition in the corrective action program. Reporting requirements pursuant to 10 CFR 50.72 should also be considered.'

d. Requested Information Per Enclosure 4 of Reference 3,

1. The NRC requests that each licensee confirm that it will use the industry-developed, NRC endorsed, flooding walkdown procedures or provide a description of plant-specific walkdown procedures. As indicated previously, Exelon's letter dated June 11, 2012 (Reference 1), confirmed that the flooding walkdown procedure (Reference 2), endorsed by the NRC on May 31, 2012, will be used as the basis for the flooding walkdowns.

2. The NRC requests that each licensee conduct the walkdown and submit a final report which includes the following:

a. Describe the design basis flood hazard level(s) for all flood-causing mechanisms, including groundwater ingress.

Page 6

NTIF Recommendation 2.3 (Walkdowns): Flooding Exelon Corporation October31,2012 Revision 0

b. Describe protection and mitigation features that are considered in the licensing basis evaluation to protect against external ingress of water into SSCs important to safety.

c. Describe any warning systems to detect the presence of water in rooms important to safety.

d. Discuss the effectiveness of flood protection systems and exterior, incorporated, and temporary flood barriers. Discuss how these systems and barriers were evaluated using the acceptance criteria developed as part of Requested Information item l.h.

e. Present information related to the implementation of the walkdown process (e.g., details of selection of the walkdown team and procedures,) using the documentation template discussed in Requested Information item l.j, including actions taken in response to the peer review.

f. Results of the walkdown including key findings and identified degraded, nonconforming, or unanalyzed conditions. Include a detailed description of the actions taken or planned to address these conditions using the guidance in Regulatory Issues Summary 2005-20, Revision 1, Revision to NRC Inspection Manual Part 9900 Technical Guidance, "Operability Conditions Adverse to Quality or Safety," including entering the condition in the corrective action program.

g. Document any cliff-edge effects identified and the associated basis. Indicate those that were entered into the corrective action program. Also include a detailed description of the actions taken or planned to address these effects. See note in Section 10 regarding the NRC's change in position on cliff-edge effects.

h. Describe any other planned or newly installed flood protection systems or flood mitigation measures including flood barriers that further enhance the flood protection. Identify results and any subsequent actions taken in response to the peer review.

3. METHODOLOGY

a. OverviewofNEI 12-07 (Walkdown Guidance)

In a collaborative effort with NRC staff, NEI developed and issued report 12-07 [Rev O-Al, Guidelines for Per/orming Verification Walkdowns of Plant Protection Features, dated May 2012 (Reference 2). The NRC endorsed NEI 12-07 on May 31, 2012 with amendments. NEI 12-07 was updated to incorporate the amendments and re-issued on June 18, 2012. On June 11, 2012, Exelon issued a letter to the NRC (Reference 1) stating that the endorsed flooding walkdown procedure (Reference 2) will be used as the basis for the flooding walkdowns. NEI12-07 provides guidance on the following items:

• Definitions o Incorporated Barrier/Feature o Temporary Barrier/Feature o Exterior Barrier/Feature o Current Licensing Basis (CLB) o Design Bases o Inaccessible o Restricted Access o Deficiency o Flood Protection Features Page 7

NTIF Recommendation 2.3 (Walkdowns): Flooding Exelon Corporation October 31,2012 Revision 0 o Reasonable Simulation o Visual Inspection o Cliff-Edge Effects o Available Physical Margin o Variety Of Site Conditions o Flood Duration

• Scope o Basis for Establishing Walkdown Scope o Identify Flood Protection Features (Walkdown list)

• Methodology o Develop Walkdown Scope o Prepare Walkdown Packages o Walkdown Team Selection and Training o Perform Pre-Job Briefs o Inspection of Flood Protection And Mitigation Features

• General

• Incorporated or Exterior Passive Flood Protection Features

• Incorporated or Exterior Active Flood Protection Features

• Temporary Passive Flood Protection Features

• Temporary Active Flood Protection Features

• Procedure Walk-through and Reasonable Simulation o Review of The Maintenance and Monitoring of Flood Protection Features o Review of Operating Procedures o Documentation of Available Physical Margins o Documenting Possible Deficiencies o Restricted Access, or Inaccessible

• Acceptance Criteria

• Evaluation and Reporting Results of The Walkdown

• Related Information Sources

• Examples

• Walkdown Record Form

• Sample Training Content

• Walkdown Report

b. Application of NE112-07 Exelon's approach to the flooding walkdowns included three phases:

Phase 1- Preparation, Training, Data Gathering, and Scoping The walkdown list was developed using the guidance provided in Section 4.2 of NEI 12-07. The existing design and licensing documents such as the UFSAR, plant drawings, and severe weather response procedures were reviewed to identify the plant features credited for protection and mitigation against external flooding events. Plant specific documents used to develop the walkdown list are identified in the PageS

NTTF Recommendation 2.3 (Walkdowns): Flooding Exelon Corporation October 31,2012 Revision 0 Reference Section. The critical attributes of each feature are reported in Part A of the NEI12-Q7 Walkdown Record Form. Topics and items reviewed to develop the walkdown list included the following:

• The barriers important to resisting the effects of external flooding (e.g., structures, walls, floors, doors, etc.).

• Penetrations through barriers, such as trenches and cable openings, that could provide a path for flood water to enter buildings and the means to seal these penetrations. Temporary penetrations and equipment hatches that could provide a path for floodwater to enter buildings were also identified. The means and process to isolate these penetrations, if they are open, within the required time will be identified.

• Instrumentation relied upon to detect water in rooms and the associated warning system.

• Features or pathways credited for flood water relief (e.g., surface drainage swales, subsurface drainage system, culverts, floor/yard drains, etc.).

• Plant response procedures for external floods to identify any incorporated or exterior equipment that is credited for flood protection or mitigation.

• Situations for which temporary plant equipment (e.g., portable pumps, sandbags, temporary barriers, etc.) is credited to protect or mitigate the effects of the external flooding event.

• Flood response procedures to evaluate the practicality of the associated actions performed by site personnel, i.e., Reasonable Simulation.

• Training provided to support implementation of plant flood procedures to determine if it is adequate (content, frequency, and participants) and reflects any time sensitive actions.

A walkdown package was developed for each feature. The purpose of the packages was to provide the teams with relevant information for efficient and thorough walkdowns.

In preparation for the walkdowns preliminary walkthroughs of the different areas were conducted. This activity helped familiarize the team with the conditions as well as offering an opportunity to identify additional credited features that may not have been identified by review of plant documentation.

Each team member was trained to NEI 12-07 and took and passed the NANTEL Generic Verification Walkdowns of Plant Flood Protection Features test. Confined space and fall protection training was obtained to prepare for the need to enter confined spaces such as manholes, and access features via ladders and scaffolding.

Phase 2 -Inspections and Reasonable Simulations Visual inspection of each accessible feature was performed and the observations documented on the walkdown record forms. The condition of each feature was compared to the acceptance criteria defined in the Supplemental Walkdown/lnspection Guidance (Reference 2). The OCNGS credited flood protection system does not require the implementation of procedures involving manual actions so no reasonable simulations were required.

Phase 3 - Final Reporting Page 9

NTIF Recommendation 2.3 (Walkdowns): Flooding Exelon Corporation October 31, 2012 Revision 0 The walkdown record forms for each feature were assembled into a package that includes a summary and a cover page to document management review of the entire package. Completion of the walkdown record forms was performed in accordance with the guidance provided in Section 7 of NEI 12-07. A Flooding Walkdown Report was prepared to address the items outlined in the "Requested Information" section of the "Recommendation 2.3: Flooding" enclosure from the 10 CFR SO.S4(f} letter.

c. Reasonable Simulations A procedure walk-through, or 'Reasonable Simulation', is required for temporary and/or active features that require manual/operator actions to perform their intended flood protection function. The purpose of the reasonable simulations is to verify the procedure or activity can be executed as specified/written. Per NEI12-07 (Reference 2), reasonable simulation included the following:

• Verify that any credited time dependent activities can be completed in the time required. Time-dependent activities include detection (some signal that the event will occur, has occurred, or is occurring), recognition (by someone who will notify the plant), communication (to the control room), and action (by plant staff}.

• Verify that specified equipment/tools are properly staged and in good working condition.

• Verify that connection/installation points are accessible.

• Verify that the execution of the activity will not be impeded by the event it is intended to mitigate or prevent. For example, movement of eqUipment across unpaved areas on the site could be impeded by soft soil conditions created by excessive water.

• Review the reliance on the station staff to execute required flood protection features. If during the review several activities are identified to rely on station staff, then perform and document an evaluation of the aggregate effect on the station staff to demonstrate all actions can be completed as required.

• Verify that all resources needed to complete the actions will be available. (Note that staffing assumptions must be consistent with site access assumptions in emergency planning procedures.)

• Show that the execution of the activity will not be impeded by other adverse conditions that could reasonably be expected to simultaneously occur (for example, winds, lightning, and extreme air temperatures).

• Personnel/departments that have responsibility for supporting or implementing the procedure should participate in the simulation effort.

• The simulation should demonstrate that the personnel assigned to the procedure do not have other duties that could keep them from completing their flood protection activities during an actual event. Actions that would be performed in parallel during an event should be simulated in parallel; not checked individually and the results combined.

• Reasonable simulation need not require the actual performance of the necessary activities if they have been previously performed and documented or it is periodically demonstrated and documented that the activities can be completed in the credited time.

Page 10

NTTF Recommendation 2.3 (Walkdowns): Flooding Exelon Corporation October 31, 2012 Revision 0 OCNGS is a zero flood plant. As such, water is not expected to enter the Reactor, Turbine Building and Emergency Diesel Building. The OCNGS credited flood protection system does not require the implementation of procedures involving manual actions so no reasonable simulations were required.

d. Walkdown Inspection Guidance A 'Walkdown Inspection Guidance' was developed by Exelon to supplement NE112-07 (Reference 2), based largely on Appendix A of NEI 12-07 (Examples). The guidance was intended to supplement, not supersede, NE112-Q7 and provide inspection guidance for specific features, listed below.

• Incorporated or Exterior Passive Features:

o Site Elevations and Topography o Earthen Features (i.e., Flood Protection Berm, Dike, Levee) o Concrete and Steel Structures o Wall, Ceiling, and Floor Seals (e.g. Penetration Seals, Cork Seals) o Passive Flood Barriers or Water Diversion Structures o Drains and Catch Basins o Plugs and Manhole Covers o Drainage Pathways (Swales, Subsurface Drainage System, etc.)

o Piping and Cable Vaults and Tunnels, Electrical Cable Conduit o Floor Hatches o Flap Gate/Backwater Valve/Duckbill Valve o Flood Wall

• Incorporated or Exterior Active Features:

o Credited Water Tight Doors o Credited Non-Watertight Doors o Pumps o Water Level Indication o Gate Valves

• Temporary Passive Features:

o Portable Flood Barriers and Inflatable Rubber Seals o Flood Gate

• Temporary Active Feature o Pumps

4. RESULTS The information requested in Reference 3, Enclosure 4, under paragraph 2 of the 'Requested Information' section, is provided below. The contents of each item were developed in accordance with Reference 2, Appendix D.

a. Requested Information Item 2 (a) - Design Basis Flood Hazards Describe the design basis flood hazard level(s) for all flood-causing mechanisms, including groundwater ingress.

Page 11

NITF Recommendation 2.3 (Walkdowns): Flooding Exelon Corporation October 31,2012 Revision 0 The design basis flood hazard is a PMP event with a maximum still-water level of 23.6' MSl adjacent to the Reactor Building and 23.5' MSl over the remainder of the site. This level accounts for the highest possible ponding of water on plant site resulting from the PMP event. A PMH event with a maximum still-water storm surge level of 22' MSl and duration as shown in the figure below, with up to l' of wave run-up, is also considered in the current licensing basis. See Figure 1.

Page 12

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PMH STILLWATER LEVEL AT OYSTER CREEK NUCLEAR UNIT I Figure 1: PMH Stillwater Level vs. Time. (Ref 13, Appendix 2.4A, Plate 3)

Page 13

NTIF Recommendation 2.3 (Walkdowns): Flooding Exelon Corporation October 31,2012 Revision 0 As part of the IPEEE RAI in 2000, the effects of a PMP event on the OCNGS site were calculated by Professor Robert Moynihan acting as a consultant to EQE (Reference 37). The PMP event was derived from NOAAjNWS Hydrometeorological Reports (HMR) Nos. 51, 52, and 53 according to the site IPEEE RAI reply.

Storm duration, precipitation, and intensity are listed in Figure 2. The CLB does not specify which of these events is bounding on the site.

Duration PMP (ntensity (min) (in) (inlhr) 5 6.1 73.2 15 9.5 38.0 30 13.6 27.2 60 18.0 18.0 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> 35.0 Varies Figure 2: PMP Durations and Intensities Considered by CLB (Ref 37, Page 24)

For the analysis, the OCNGS site was divided into nine distinct watershed areas, shown in Figure 3. The tributary areas for the watersheds include the roof areas of the buildings abutting them . This is conservative, as the roof drains for the Reactor Building, Turbine Building, and Old Radwaste Building flow directly to the 30" overboard drain instead of the site storm drains. The wording in the IPEEE RAI is ambiguous as to whether site storm drains are considered in the runoff calculation. See Figure 3 for subcatchments and flow directions.

Page 14

NTIF Recommendation 2.3 (Walkdowns): Flooding Exelon Corporation October 31,2012 Revision 0 e

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IX Figure 3: Site Plan View showing Subcatchments (Ref 37, Page 31, Figure 8)

Page 15

NTTF Recommendation 2.3 (Walkdowns): Flooding Exelon Corporation October 31,2012 Revision 0 The IPEEE RAI analysis established that ponding would only occur in areas 3 and 6 of the plant site, which do not contact the Turbine or EDG Buildings. For the flooding response walkdowns, the PMP flood level of 23.6' MSL was applied to the Reactor Building and 23.5' MSL to the remainder of the site. The effects of a PMP event on the roofs of the Reactor and Turbine Buildings were evaluated as part of the IPEEE RAI response (Reference 37).

The PMH event for OCNGS was calculated by Burns and Roe in 1972 per UFSAR section 2.4 (Reference 13).

The storm considered is a Category 4 on the 5affir-Simpson Hurricane scale, with a maximum sustained wind speed of 133 mph and a central barometric pressure of 27.1 inches Hg. This storm is considered to move at 12 and 23 knots, and occurs concurrent with the astronomical high tide of 2.7' MSL at the mouth of the bay. Slower speed storms were also evaluated, but the 12 and 23 knot storms were found to produce the bounding flood. Assumptions on the storm surge overflow of Barnegat Bay were evaluated based on experience with landfall of hurricanes along the United States east coast. 10' to 20' of horizontal beach loss was assumed. Wave runup at the plant area was calculated based on USGS topographical information. The probability of the calculated PMH occurring at plant site was characterized by Burns and Roe as "so remote as to be almost inconceivable". As stated in the UFSAR section 2.4, the highest flood level ever recorded at the plant site is 4.5' MSL, based on evidence left behind after a 1962 storm (pre-dating construction of the plant).

The PMH still-water storm surge level was calculated to be 22' MSL, with up to l' of wave runup at plant site. As plant grade is at 23' MSL, the CLB PMH is not postulated to impact any safety critical buildings on plant site. All safety critical plant buildings have been evaluated for hydrostatic forces associated with the PMH storm surge water levels, as well as the potential for buoyancy. The service water intake structure will be underwater during a PMH event.

The effects of dam breaches and flooding due to PMP on OCNGS and the Forked River were evaluated, but did not result in water levels at the OCNGS site greater than those created by the PMH. Therefore, the PMH bounds those PMF conditions. Per UFSAR Section 2.4 (Ref. B), the chance of a tsunami affecting the plant site on the east coast ofthe United States is so small as to be insignificant. Thus, tsunami events were not evaluated for OCNGS. The effects of probable ice blockage in the intake canal on plant safety related SCCs were evaluated, and deemed to be insignificant.

The groundwater table at OCNGS is 12' MSL under normal conditions, reaching 19' to 22' MSL during a PMH storm surge (Reference 13, section 2.4.11 and Table 2.4-7). There is no information on design basis groundwater levels during a PMP event. The OCNGS Systematic Evaluation Program (SEP) Final Report (Reference 33), Topic 111-3.A discusses the effects of groundwater on the plant. Per subsection (3), "all penetrations below grade are designed to be leak tight", to prevent groundwater ingress. SEP Supplement 1 states that "on the basis of the factors of safety obtained against flotation, the adequacy of the subgrade walls, and the adequacy of bearing capacity, the OCNGS facility can adequately withstand a groundwater level of 23 feet MSL."

b. Requested Information Item 2(b) - CLB Protection and Mitigation Features Describe protection and mitigation features that are considered in the licenSing basis evaluation to protect against external ingress of water into SSCS important to safetv.

The bounding licensing basis floods for OCNGS are the PMP and PMH, as discussed in section 4a.

Incorporated and external passive features are credited in the CLB to prevent water from entering the Turbine and EDG Buildings at grade, to minimize water ingress at grade into the Reactor Building, to Page 16

NTIF Recommendation 2.3 (Walkdowns): Flooding Exelon Corporation October 31, 2012 Revision 0 prevent failure of the Reactor and Turbine building roofs, and to prevent any groundwater ingress into safety critical buildings.

As discussed previously, the maximum flood level due to PMH is 22' MSL. The plant grade, 23' MSL, is one foot above the PMH flood level. Therefore, the PMH flood will not directly affect or enter the plant safety critical buildings above grade. However, the circulating water intake structure will be under water. This deck supports the circulating water pumps and the emergency service water pumps. During a PMH flood, the circulating water and service water pumps will become inoperable and thus emergency plant procedures (ABN-32) have been instituted which require the plant to shut down when water levels at the intake reach 4.5' MSL and the reactor to scram at 6' MSL to ensure a safe plant shutdown. As the time to SCRAM the reactor is insignificant, compared to the time for still-water to reach PMH levels at site, the plant is considered in hot shutdown for the purposes of the PMH flood. Procedure ABN-31 (high winds) requires contact with the NWS every 30 minutes during a hurricane watch or warning for updates on the specifics of the storm, and water level at the intake to be logged at the same interval. Wind speeds of up to 133 miles per hour are assumed to be concurrent with the PMH event. For the purposes of our walkdowns, a loss of offsite power was assumed. PMH flood water level over time is given in Figure 1 (see section 4(a)).

Storm surge still water level will be greater than the normal ground water level for approximately 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.

As discussed previously, the maximum flood level due to PMP is 23.5', except immediately adjacent to the Reactor Building. The entrances to all safety critical plant buildings (except for the EOG Building) are at 23.5' MSl. The two entrances to the EDG BUilding are at elevation 23' MSL, which is 6 inches below the PMP flooding level. Dikes riSing 6 inches above plant grade are provided at the entrances to protect against flooding of the EDG Building. Therefore, water will not enter through the Turbine Building doors or overtop EDG Building dikes in a PMP flood.

The maximum flood level due to PMP is 23.6' adjacent to the Reactor Building. The entrances to the Reactor Building are 3 sets of airlock doors which remain closed during normal operation. The airlock doors' credited flood protection function is to "remain in place and minimize water intrusion into the building." The IPEEE RAI response does not discuss the volume of water allowed into the Reactor Building, but it does state that it "does not contribute to severe accident risk at OCNGS."

Without proper drainage, the PMP event could potentially cause the roofs of the Turbine and Reactor Buildings to exceed design live load and fail. To prevent roof failure, area drains were installed on the roofs of the Turbine and Reactor Buildings at the time of plant construction, and scuppers were added per commitments made in SEP section 4.5.3 (Roof Drains) (Reference 33). Calculations performed in the IPEEE RAI responses demonstrate that the revised PMP will not cause failure of the Turbine or Reactor Building roofs. As a PMP event can arise suddenly and without warning, no assumption can be made about plant configuration. No warning is assumed for the PMP flood. For the purposes of our walkdowns, a loss of offsite power was assumed. No controlling duration is given for the PMP flood in the IPEEE RAI; the longest duration evaluated is 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

Flood protection below grade for the PMP, PMH, and groundwater intrusion is provided by the CLB requirement that all below-grade penetrations be sealed against water intrusion. The external walls and floors below flood level of the Turbine Building, Reactor Building, and EDG Building are flood protection features, as are the seals for all penetrations through these barriers. All internal seals of conduits that penetrate these barriers must be considered as 'inaccessible' flood protection features. Additionally, the airlock expansion joints connecting the two buildings are flood protection features, as both the Turbine and Page 17

NTIF Recommendation 2.3 (Walkdowns): Flooding Exelon Corporation October 31,2012 Revision 0 Reactor Buildings contain safety related equipment. If all of these flood protection features perform their intended functions, water will not enter the plant buildings below grade.

Procedures ABN-31, ABN-32, and OP-OC-l08-109-1001 were evaluated to determine if any simulations were required. ABN-31 requires manning the combustion turbines in the event of a hurricane event, but the Combustion Turbines were deemed to be outside the scope of our walkdowns, as they are not part of the plant and not required to maintain safe shutdown. A loss of offsite power was assumed instead. ABN-32 requires monitoring water level at the intake. No reasonable simulation is required for that action.

OP-OC-l08-109-1001 requires that if building flooding conditions exist, then temporary flood protection features should be installed lias necessary". Further, work support is required to stage sandbags near the Turbine Building truck bay to protect the 4160V room. The procedure lacks any guidance as to where this equipment is to be stored, how much of it is to be stored, when and where it is to be deployed in a flooding event, and how to compensate for the lack of warning for a PMP. The procedure needed to be upgraded and IR 01398217 was issued. No action was committed to in the CLB since implementing OP-OC-l08-109-1001 would only add margin above CLB flood level. Therefore, no reasonable simulations of the procedure were required.

As there are no ClB features requiring manual actions for implementation, no reasonable simulations are required for deployment and operability.

There is no discussion in the OCNGS CLB about plant configurations during a flooding event. For the purposes of these walkdowns, the plant was assumed to be in hot shutdown per ABN-31 and ABN-32 for a PMH, and in any configuration for a PMP event. The flood protection features evaluated protect plant safety related features in any configuration. As all features below grade were in the walkdown scope, protection against groundwater intrusion during normal and PMH conditions is captured in the walkdowns performed.

c. Requested Information Item 2(c) - Flood Warning Systems Describe any warning systems to detect the presence of water in rooms important to safety.

There are no room water level warning systems that are credited for external flood protection in OCNGS's CLB.

d. Requested Information Item 2(d) - Flood Protection System/Barrier Effectiveness Discuss the effectiveness of flood protection systems and exterior. incorporated. and temporary flood barriers. Discuss how these systems and barriers were evaluated using the acceptance criteria developed as part of Requested Information Item 1.h [in Enclosure 4 of the March 12. 2012. SO.S4(f) letter]

Section 6 of NE112-07 defines 'acceptance' as:

"Flood protection features are considered acceptable if no conditions adverse to quality were identified during walkdowns, verification activities, or program reviews as determined by the licensee's Corrective Action Program. Conditions adverse to quality are those that prevent the flood protection feature from per/orming its credited function during a design basis external flooding event and are "defiCiencies". Deficiencies must be reported to the NRC in the response to the 50.54(f) letter."

Page 18

NTTF Recommendation 2.3 (Walkdowns): Flooding Exelon Corporation October 31, 2012 Revision 0 As indicated in Section 3.d, inspection guidance was developed, supplementing NEI12-07, to provide more specific criteria for judging acceptance. All observations that cannot be immediately judged as acceptable were entered into the site's CAP where an evaluation of the observation can be made.

Visual inspections of the external flood protection features were performed with the objective of comparing the observed condition of the feature to the acceptance criteria as defined in Section 6 of NEI 12-07 and the Supplemental Walkdown Inspection Guidance. Observations not immediately judged as acceptable were entered into the CAP, per section 4(f) and Table 4 of section 5 of this report.

Table 3 in Section 5 of this report lists the features that were immediately judged as acceptable via the visual inspections. Details of these acceptable features are as follows.

With the exception of the inaccessible Turbine Building base slab, the concrete walls and floors identified as external flood barriers were inspected and found to have no signs of material degradation. There were no signs of water intrusion through the walls and floors; the only observed water intrusion was directly attributable to specific penetrations. Observations indicate that all walls and floors meet the acceptance criteria in Reference 2. The expansion joints between the Turbine and Reactor Buildings were inspected and found to have no signs of material degradation. No signs of past water intrusion into the airlocks between the buildings was observed. These observations also met the acceptance criteria in Reference 2.

The protective dikes around the EDG Building entrances were evaluated and determined to be the correct height and in good condition (see IR 01410069).

The Reactor Building Airlock Doors DR-814-038, DR-814-040, and DR-814-042 were found to be in place and in good structural condition. The gaps between the doors and the Reactor Building floor were measured and found to be acceptable. The doors were closed, as required by procedure. All observations met the acceptance criteria in Reference 2 for a credited non-watertight door.

The majority of penetrations and penetration seals had no signs of material degradation. A number of the penetrations had superficial oxidation, and one appeared to have recently been re-sealed after past water intrusion. Nevertheless, the aforementioned cases were judged to meet the acceptance criteria in Reference 2. However, there were penetrations where either active water intrusion was observed, or there was evidence of past water intrusion with no clearly sufficient repairs. These penetrations were entered into the CAP, and IRs written to document these conditions. The CAP disposition resulted in 19 penetrations found to be deficient.

A majority of all roof drains and scuppers were found to be in place, without debris buildup or any other blockage. Three drains on the Heater Bay and Fan Roofs of the Turbine Building were found to be partially obstructed, and the drain cover of one of them was installed upside down. These drains were entered into the CAP and found to be deficient. All roof drains and scuppers taken credit for as part of the IPEEE RAI roof drainage calculation were in acceptable condition.

The manholes in the yard were not inspected to determine if the manhole could be a source of water for conveyance into a building via a conduit that penetrates the building. These inspections were deemed unnecessary, as walkdowns were able to establish that the incorporated passive flood protection features of the Turbine and Reactor buildings provide a flood barrier. Water from manholes would be prevented from entering safety critical buildings by penetration and conduit internal seals. See above for discussion of penetration seals, and section 4(f) for discussion of conduit internal seals.

Page 19

NTTF Recommendation 2.3 (Walkdowns): Flooding Exelon Corporation October 31,2012 Revision 0

e. Requested Information Item 2 (e) - Implementation of Walkdown Process Present information related to the implementation of the walkdown process (e.g., details of selection of the walkdown team and procedures) using the documentation template discussed in Requested Information Item 1.j [in Enclosure 4 of the March 12, 2012, SO.S4(f) letter), including actions taken in response to the peer review.

The selection of the walkdown team considered site familiarity and diversity of disciplines. The walkdown team consisted of members from the mechanical, electrical and civil/structural disciplines. Two members of the team have experience with plant modifications.

All ENERCON team members, as well as the OCNGS site lead Responsible Engineer (lRE), participated in eight hours of training conducted by Exelon that reviewed the content of the Reference 2, NEI 12-07 guidelines. Team members were required to pass the NANTEl Generic Flood Protection Awareness training course, and the NANTEl Generic Verification Walkdowns of Plant Flood Protection Features test.

Familiarization with the basis for walkdown scope and items to be inspected was established by having each member of the walkdown team involved in some aspect of evaluation of the ClB and defining the walkdown flood protection features to be inspected. A walkdown record form template was developed.

The template cross referenced sections of the guidelines to the questions being asked on the form so that a better understanding of form completion requirements could be understood by each member of the team.

Prior to performing any walkdown inspections the walkdown team members completed Parts A, Bl, B2 and B3 of the walkdown record forms and developed the necessary walkdown packages. In order to complete these four pages of the walkdown record form, acceptance criteria, preventive maintenance records, and operating procedures were reviewed.

Pre walkthroughs of many areas to be inspected were conducted. There activities resulted in walkdown team members becoming more familiar with the scope prior to any inspections being performed. The walkdowns, with the exception for those of the Torus room and Reactor Building Equipment Drain Tank (RBEDT) room, were conducted by teams of two to three ENERCON engineers, accompanied by the OCNGS flooding response lRE and up to two other OCNGS personnel. In order to keep dose As low As Reasonably Achievable (ALARA), the walkdown team for the RBEDT room consisted of one ENERCON engineer and the OCNGS lRE, and the walkdown team for the Torus room consisted of one ENERCON engineer, the OCNGS lRE, and the OCNGS Task Manager. At least two NANTEl Flood Protection trained engineers were on every walkdown, and video and photographs of features evaluated on ALARA-constrained walkdowns were reviewed by the remainder of the ENERCON team.

During the visual inspection each flood protection feature was identified by each member of the team to ensure that data being collected was associated with the same plant feature.

f. Requested Information Item 2(f) - Findings and Corrective Actions Taken/Planned Results of the walkdown including key findings and identified degraded, non-conforming, or unanalyzed conditions. Include a detailed description of the actions taken or planned to address these conditions using the guidance in Regulatorv Issues Summary 2005-20, Rev 1. Revision to NRC Inspection Manual Part 9900 Technical Guidance, "Operabilitv Conditions Adverse to Quality or Safety," including entering the condition in the corrective action program.

Page 20

NTIF Recommendation 2.3 (Walkdowns): Flooding Exelon Corporation October 31,2012 Revision 0 Observations not immediately judged as acceptable Observations made during the visual inspections not immediately judged as acceptable were entered into the CAP. The features contained in this category are listed in Table 4 in Section 5 of this report. The table identifies the actions taken to evaluate potential deficiencies and resolve the conditions.

12 penetrations (including 1 conduit with an internal seal) in the Reactor Building corner rooms and Torus room showed signs of past water intrusion in the form of rust stains on the wall. 3 of those penetrations also showed stalactite growth. These penetrations were entered into CAP (See Table 4 of Section 5 for the list of IRs), and it was determined there is no active leakage from these penetrations. ARs have been generated to paint these walls.

A walkdown of the plant site was performed to evaluate plant topography, and several deviations from the topography assumed in the design basis PMP runoff calculation were noted. Deviations include post-9/11 security improvements, an ISFSI expansion, and the construction of the contractor building. The ISFSI expansion was evaluated for runoff impact, but flooding considerations were screened out or not considered for other changes. These observations were documented, and dispositioned as IR 01404344. It was determined that these alterations did not constitute a "significant" change since 2000, and "no safety related equipment is affected." A new PMP/LIP flooding study is being performed as part of OCNGS's Fukushima response.

Observations Designated through CAP as Deficient In the Southwest corner of the Turbine Building basement, 2 cut and uncapped conduit pipes penetrate the west wall. As the penetrations are not '4" Conduit Penetration' features, credit cannot be taken for visually inspected internal seals. IRs 01406952 and 01406089 were written to evaluate these conditions, and ARs A2313037 and A2313043 were issued to correct the deficiencies. Repairs are scheduled to be completed by 11/27/2012.

During walkdowns on the Heater Bay and Fan Roofs of the Turbine Building, 2 area drains and 1 scupper were observed to be partially obstructed by debris. Further, one of the drain's cover appears to be installed upside down which puts it at greater risk of blockage. IR 01419031 was written to evaluate this condition, and AR A2313982 was issued to correct the deficiencies. Repairs are scheduled to be completed by 11/27/2012.

Active water intrusion into the southwest corner of the Turbine Building basement at a rate of about 40 drops per minute was observed during a rainfall event. Eight penetrations were allowing the water in. As 6 of the penetrations are permanently covered in fireproofing, they could not all be observed directly. These penetrations are associated with the cables for the number 2 EDG, and leakage from them has been noted and documented in the past. The observation was entered into the CAP as IR 01405765.

Per IR 01405765, Assignment 3 (Reference 36), during a rain event the soil outside the Turbine Building became saturated to grade level. The hydrostatic head on the Turbine Building penetrations created by this storm is only slightly less than that which would be created by a PMP event. Flooding in the Turbine Basement does not impact plant safety unless it causes the airlocks between the Turbine and Reactor Buildings to fail. The airlocks can withstand water up to elevation 7' MSl. Computations by site staff in response to this IR demonstrate that the water inflow that could be expected from a PMP in 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> is several orders of magnitude less than that required to flood the basement to 7' MSl. A PMH will only Page 21

NTTF Recommendation 2.3 (Walkdowns): Flooding Exelon Corporation October 31, 2012 Revision 0 maintain a storm surge greater than 18' MSL (the lowest elevation of effected penetrations) for 2.2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> per the UFSAR.

It was concluded that the impact of leakage through the EDG 2 conduits on the Turbine Building basement is minimal. Per IR 01405765, Assignment 2, it is desirable to keep the cables inside the conduits dry, in order to prevent degradation of the cables. Therefore, it was concluded in Assignment 4 that it was more desirable to allow the conduits to drain into the Turbine Building basement than it would be to re-seal the conduits and allow standing water in them. The penetrations are deficient by the standards of the CLB, but deemed acceptable.

Evidence of past water leakage from nine conduit penetrations associated with cables for the number 1 EDG was similarly observed in the Turbine Building basement. It was entered into the CAP and dispositioned in IR 01406841. Site engineers came to the conclusion that liThe leak noted in (Turbine Building] basement is from conduit that goes to EDG. This is expected leakage. The design is to prevent any water from accumulating in conduit, instead any water that enters conduit is directed to the 1-5 sump".

These penetrations are similarly deficient by the standards of the CLB, but deemed acceptable.

Observations Awaiting Final Disposition in CAP None Restricted Access Areas 108 features could not be inspected during the original walkdowns due to high radiation fields in the Turbine BUilding (Condenser Bay, Steam Jet Air Ejector Room, and High Low Room). 10 conduit penetrations in cable trenches in the EDG Building could not be observed due to close proximity to high voltage cables that could become energized, posing a severe risk to personnel safety. 2 wall penetration seals (1 in the Reactor Building, 1 in the Turbine Building) are not accessible from normal personnel access areas due to height. All of these 120 features were designated as 'restricted access' and will be evaluated during the lR24 refueling outage in October 2012.

Inaccessible Areas A total of 47 inaccessible features were identified. 26 of them are internal seals of 4" conduits penetrating into the Reactor and Turbine Buildings. These conduits are not designed to provide easy access for inspection, and so major disassembly would be required to look inside. 411 conduit penetrations 007, 011, 014, 015, 018, 020, 022, and 031 were all open on the interior of the plant, allowing the internal seal against water intrusion to be visually inspected. Further, there is a SEP requirement that all below-grade penetrations be designed to be leak tight. Also, the interface between conduit and conduit penetration generally used by the plant does not appear to be water-tight, so any water intrusion would become apparent by inspecting walls and the conduit exteriors for signs of water intrusion. These factors provide reasonable assurance that seals are in place and functional for 25 of these 26 features. The remaining feature was dispositioned in IR 01407010, and determined to be satisfactory.

15 of the remaining inaccessible features are conduit penetrations, either covered in fireproofing material, covered in a plaster-like material, or where a seal was not able to be observed and inspection with a ladder or scaffold would be impossible or very unsafe due to interference with existing equipment. Major equipment disassembly would be required to inspect these penetrations. Reasonable assurance is provided as above for 9 of the 15 features. 6 of the features had observed leakage and were dispositioned Page 22

NTTF Recommendation 2.3 (Walkdowns): Flooding Exelon Corporation October 31, 2012 Revision 0 in IR 01405765 (see above, under "observations designated through the CAP as deficient", for evaluation of the aggregate effect of this observation).

Two 4" floor drains in the EDG Building are located directly beneath the EDG units, and inspection would require disassembling the EDGs. No signs of ponding on the EDG floor were noted, even after rain events, and the 4 area drains inspected at floor level in each EDG room were unblocked. The 30" overboard drain system is largely buried, but water was observed flowing from it with no restrictions.

The bottoms of Sump 1-5 and Sump 1-1 are both inaccessible due to standing water in each sump, leaving no practical means of access. Sump 1-1 is not adjacent to any exterior Turbine Building wall. The bottom of Sump 1-1 is at EI. H 4' MSL, and is separated from the ground under the Turbine Building by 6' of reinforced concrete, making water intrusion unlikely. No unusual run times for the 1-1 sump have been reported, which is inconsistent with the characteristics of a groundwater ingress path. All of the above offer reasonable assurance that there is not groundwater intrusion into the 1-1 sump.

Sump 1-5 is adjacent to the South and West walls of the Turbine Building. The bottom of the sump is at EI.

(-) 6' MSL. The South and West walls are each 3' thick reinforced concrete, and the Turbine Building base slab is 6' deep under the 1-5 Sump. A high density polyurethane liner was installed in the sump in 1985.

Analysis of Sump 1-5 run times from 2010 to 2012 revealed several 2 to 3 week periods where the sump was not required to pump any water. Given that the bottom of the sump is 18' below the water table and 6' below sea level, this is inconsistent with the sump being a groundwater infiltration path. The 1-5 sump collects water from the Turbine Building floor and equipment drains, as well as the deficient Turbine Building west wall penetrations mentioned above. Water in the sump can be attributed to these sources.

It can be said with reasonable assurance that the 1-5 sump is a functional groundwater barrier.

The base slab of the Turbine Building, outside of the Condenser Bay, is almost entirely covered by the Turbine Building floor at elevation 3.5' MSL, and a bed of sand between the two concrete slabs. As the Turbine Building floor cannot be dug up to inspect the base slab, there is no reasonable means of access and the feature is inaccessible. There is a history of water buildup in the area between the Turbine Building floor slab and base slab. A comprehensive study on Turbine Building basement water intrusion performed in 2002 (Reference 38) attributed water intrusion primarily to deficient wall penetrations in the southwest of the Turbine Building, and internal water seeping from corroded drain lines. Remedial actions taken by OCNGS since the problem was discovered include replacing cables and conduit seals, constructing water resistant vaults where water used to pool between the Turbine and Reactor Buildings, and repairing the drain system. These activities have dramatically reduced the amount of water entering between the floor and the base slab. If the base slab were a groundwater infiltration path, it would be expected that remediating penetrations and drains would have minimal impact on water levels between the floor and the base slab. All inspected OCNGS walls and floors, as well as the portion of the base slab visible in the hallway along the North Wall of the Turbine Building, are acceptable. The Turbine Building base slab is 6' of reinforced concrete, so failure is exceedingly unlikely. All of the above provide reasonable assurance that the Turbine Building base slab is in good condition. The base slab is visible in the Condenser Bay, and will be inspected during the 1R24 outage (see 'Restricted Access Areas', above).

Original walkdown record forms are available on-site for review, as required.

Page 23

NTIF Recommendation 2.3 (Walkdowns): Flooding Exelon Corporation October 31, 2012 Revision 0

g. Requested Information Item 2(g) - Cliff -Edge Effects and Available Physical Margin Document any cliff-edge effects identified and the associated basis. Indicate those that were entered into the corrective action program. Also include a detailed description of the actions taken or planned to address these effects.

Cliff-edge effects were defined in the NTIF Report (Reference S) as "the safety consequences of a flooding event may increase sharply with a small increase in the flooding level". As indicated in Sections 3.12 of NEI 12-07 (Reference 2), the NRC is no longer expecting the Recommendation 2.3: Flooding Walkdowns to include an evaluation of cliff-edge effects. The NRC is now differentiating between cliff-edge effects, which are addressed in Enclosure 2 of Reference 3, and Available Physical Margin (APM).

As indicated in Sections 3.13 of NEI 12-07 (Reference 2), APM describes the flood margin available for applicable flood protection features at a site (not all flood protection features have APMs). The APM for each applicable flood protection feature is the difference between licensing basis flood height and the flood height at which water could affect an SSC important to safety.

APM information was collected during the walkdowns in accordance with the guidance provided in NEI 12-07 and the final resolution to FAQ-OOG. APM was collected primarily support the response to Enclosure 2 of Reference 3 and, as such, is not included in this report. APM determinations did not involve calculating cliff-edge effects (i.e. the safety consequences). During the Integrated Assessment (see Enclosure 2 of Reference 3), the cliff-edge effects and the associated safety risks will be evaluated using the APMs and other information, such as the specific SSCs that are subjected to flooding and the potential availability of other systems to mitigate the risk. IR 01422582 was written to document cases of small margin, significant consequences, and to disposition them in the site CAP.

h. Requested Information Item 2 (h) - Planned/Newly-Installed Flood Protection Enhancements Describe any other planned or newly installed flood protection systems or flood mitigation measures including flood barriers .that further enhance the flood protection. Identify results and any subsequent actions taken in response to the peer review.

There are no newly installed or planned flood protection features at OCNGS at the time of the writing of this report.

5. CONCLUSIONS This section of the report includes 6 tables that provide the results of the walkdowns. Table 1 provides a summary of the number and type of features included in the walkdown scope. A total of 421 features were included in the scope of this effort.

Table 2 summarizes the reasonable simulations performed. As no reasonable simulations were performed, this table is empty.

Page 24

NTTF Recommendation 2.3 {Walkdowns}: Flooding Exelon Corporation October 31, 2012 Revision 0 The results of the visual inspections during the flooding walkdowns showed that 225 features meet the NEI 12-07 acceptance criteria. Table 3 provides this list of features that were immediately judged to be acceptable.

Table 4 provides the list of 36 features that were not immediately judged as acceptable during the walkdowns. The table provides the tracking mechanism for CAP resolution of the identified conditions.

Table 5 lists the features classified as being in restricted access areas. The reason for being classified as restricted access is provided along with the planned future time for inspection. 120 features are classified as in restricted access areas.

Table 6 lists 47 features that are classified as in inaccessible areas. The reason for this classification is provided along with a summary of the reasonable assurance that the feature can perform its intended function (as applicable). Detailed discussions of reasonable assurance are provided in Section 4(f) of this report. 7 of these features were entered into the CAP because of observations associated with them.

The only findings that were found to be -deficient per the CLB were 17 conduit penetrations showing signs of water intrusion, 2 cut and uncapped conduit in the Reactor Building and Turbine Building, and 3 partially blocked drains on the Turbine Building Heater Bay and Fan roofs. The leakage rate through the 17 penetrations were evaluated, and found to be orders of magnitude lower than that which would threaten plant SSCs. The other deficiencies will be resolved no later than 11/27/2012. No other findings challenge the CLB. Water intrusion into the Reactor Building is expected in the CLB during a PMP event, and it was verified that the airlock doors are in place to "minimize water intrusion into the building." Per the IPEEE RAI response, this CLB water intrusion "does not contribute to severe accident risk at OCNGS."

The flooding walkdown record forms document the details of all observations for all flood protection features inspected, and are available for on-site review. Except as noted above, OCNGS flood protection features met the NE112-07 Supplemental Guidance acceptance criteria and were found to be in accordance with the site CLB.

Page 25

NTIF Recommendation 2.3 (Walkdowns): Flooding Exelon Corporation October 31,2012 Revision 0 Table # 1: Summary - Features Included in the Walkdown Scope Feature Type Total Number Passive -Incorporated 421 Passive - Temporary 0 Active - Incorporated 0 Active - Temporary 0 Table # 2: Reasonable Simulations

1. Description Purpose N/A No Reasonable Simulations were N/A performed.

Page 26

NTTF Recommendation 2.3 (Walkdowns): Flooding Exelon Corporation October 31,2012 Revision 0 Table #3

• Ust of Features Immediately Judged as Acceptable Passive/Active

1. FeaturelD # Description Incorporated/Temporary 1 16" Pipe Sleeve 219 Pipe Penetration Seal Passive -Incorporated 2 20" Pipe Sleeve 220 Pipe Penetration Seal Passive -Incorporated 3 8" Pipe Sleeve 221 Pipe Penetration Seal Passive -Incorporated 4 20" Pipe Sleeve 222 Pipe Penetration Seal Passive -Incorporated 5 8" Pipe Sleeve 223 Pipe Penetration Seal Passive -Incorporated 6 4" Conduit Penetration 224 Conduit Penetration Seal Passive -Incorporated 7 4" Conduit Penetration 225 Conduit Penetration Seal Passive -Incorporated 8 4" Conduit Penetration 226 Conduit Penetration Seal Passive -Incorporated 9 4" Conduit Penetration 227 Conduit Penetration Seal Passive -Incorporated 10 4" Conduit Penetration 228 Conduit Penetration Seal Passive -Incorporated 11 NW corner room floor Floor Passive -Incorporated 12 NE corner room floor Floor Passive -Incorporated Reactor Build to Turbine Building Building Expansion Passive -Incorporated 13 Expansion Joints (T-114) Joints 14 6" Pipe Sleeve 275 Pipe Penetration Seal Passive -Incorporated 15 6" Pipe Sleeve 276 Pipe Penetration Seal Passive -Incorporated 16 12" Pipe Sleeve 277 Pipe Penetration Seal Passive -Incorporated 17 SE corner room floor Floor Passive -Incorporated 18 4" Conduit Penetration 247 Conduit Penetration Seal Passive -Incorporated 19 4" Conduit Penetration 248 Conduit Penetration Seal Passive -Incorporated 20 4" Conduit Penetration 287 Conduit Penetration Seal Passive -Incorporated 21 4" Conduit Penetration 357 Conduit Penetration Seal Passive -Incorporated 22 4" Conduit Penetration 359 Conduit Penetration Seal Passive -Incorporated 23 Rectangular Penetration 4'x2' 267 Penetration Seal Passive -Incorporated 24 10" Pipe Sleeve 268 Pipe Penetration Seal Passive -Incorporated 25 SW corner room floor Floor Passive -Incorporated Reactor Build to Turbine Building Building Expansion Passive -Incorporated 26 Expansion Joints (T-113) Joints Page 27

NTIF Recommendation 2.3 (Walkdowns): Flooding Exelon Corporation October 31, 2012 Revision 0 Table #3 - Ust of Features Immediately Judged as Acceptable PasslvelActive

1. Feature 10# Description Incorporated/Ternporary 27 12" Pipe Sleeve 272 Pipe Penetration Seal Passive -Incorporated 28 10" Pipe Sleeve 274 Pipe Penetration Seal Passive -Incorporated 29 6" Penetration S Pipe Penetration Seal Passive -Incorporated 30 Rectangular Penetration 8'x8' 279 Penetration Seal Passive -Incorporated 31 Rectangular Penetration 3'x2' 280 Penetration Seal Passive -Incorporated 32 12" Pipe Sleeve 284 Pipe Penetration Seal Passive - Incorporated 33 6" Penetration N Pipe Penetration Seal Passive - Incorporated 34 Torus Room floor Floor Passive -Incorporated 35 Personnel Air Lock 285 (DR-814-042) Door Passive - Incorporated 36 Personnel Air Lock 286 (DR-814-038) Door Passive - Incorporated 37 Personnel Air Lock 380 (DR-814-D40) Door Passive - Incorporated 38 Area Drain 288 Area Drain Passive - Incorporated 39 Area Drain 289 Area Drain Passive - Incorporated 40 Area Drain 290 Area Drain Passive - Incorporated 41 Area Drain 291 Area Drain Passive - Incorporated 42 6" Scupper Type Roof Drain 378 Scupper Passive - Incorporated 43 6" Scupper Type Roof Drain 379 Scupper Passive - Incorporated 44 East Wall Reactor Building Wall Passive - Incorporated 45 North Wall Reactor Building Wall Passive - Incorporated 46 South Wall Reactor Building Wall Passive - Incorporated 47 West Wall Reactor Building Wall Passive - Incorporated 48 East Wall Turbine Building Wall Passive -Incorporated 49 North Wall Turbine Building Wall Passive -Incorporated 50 South Wall Turbine Building Wall Passive - Incorporated 51 11/2" Conduit Penetration Penetration Seal Passive -Incorporated 52 Area Drain 352 Area Drain Passive -Incorporated 53 Area Drain 354 Area Drain Passive -Incorporated 54 Area Drain 355 Area Drain Passive - Incorporated Page 28

NTIF Recommendation 2.3 (Walkdowns): Flooding Exelon Corporation October 31, 2012 Revision 0 Table #3 - Ust of Features Immediately Judged as Acceptable

, Feature ID# Description Passive/Active Incorporated/Temporary 55 Area Drain 356 Area Drain Passive -Incorporated 56 Area Drain 360 Area Drain Passive - Incorporated 57 4" Scupper Type Roof Drain 368 Scupper Passive -Incorporated 58 4" Scupper Type Roof Drain 369 Scupper Passive -Incorporated 59 4" Scupper Type Roof Drain 370 Scupper Passive - Incorporated 60 4" Scupper Type Roof Drain 371 Scupper Passive -Incorporated 61 4" Scupper Type Roof Drain 372 Scupper Passive -Incorporated 62 4" Scupper Type Roof Drain 373 Scupper Passive -Incorporated 63 6" Scupper Type Roof Drain 374 Scupper Passive -Incorporated 64 6" Scupper Type Roof Drain 375 Scupper Passive -Incorporated 65 6" Scupper Type Roof Drain 376 Scupper Passive -Incorporated 66 6" Scupper Type Roof Drain 377 Scupper Passive -Incorporated 67 Area Drain 293 Area Drain Passive -Incorporated 68 Area Drain 294 Area Drain Passive -Incorporated 69 Area Drain 296 Area Drain Passive -Incorporated 70 Area Drain 297 Area Drain Passive -Incorporated 71 Area Drain 300 Area Drain Passive -Incorporated 72 Area Drain 301 Area Drain Passive -Incorporated 73 4" Scupper Type Roof Drain 292 Scupper Passive -Incorporated 74 4" Scupper Type Roof Drain 298 Scupper Passive -Incorporated 75 4" Scupper Type Roof Drain 302 Scupper Passive -Incorporated 76 24" Pipe Sleeve 004 Pipe Penetration Seal Passive - Incorporated 77 Rectangular Penetration 3 x 1'-6" 005 Penetration Seal Passive -Incorporated 78 4" Conduit Penetration 007 Conduit Penetration Seal Passive - Incorporated 79 4" Conduit Penetration 008 Conduit Penetration Seal Passive -Incorporated 80 4" Conduit Penetration 009 Conduit Penetration Seal Passive -Incorporated 81 4" Conduit Penetration 010 Conduit Penetration Seal Passive -Incorporated 82 4" Conduit Penetration all Conduit Penetration Seal Passive -Incorporated Page 29

NTIF Recommendation 2.3 (Walkdowns): Flooding Exelon Corporation October 31,2012 Revision 0 Table #3 - Ust of Features Immediately Judged as Acceptable Passive/Active

1. Feature 10# Description Incorporated/Temporary 83 4" Conduit Penetration 012 Conduit Penetration Seal Passive - Incorporated 84 4" Conduit Penetration 013 Conduit Penetration Seal Passive - Incorporated 85 4" Conduit Penetration 014 Conduit Penetration Seal Passive -Incorporated 86 4" Conduit Penetration 015 Conduit Penetration Seal Passive -Incorporated 87 4" Conduit Penetration 016 Conduit Penetration Seal Passive - Incorporated 88 4" Conduit Penetration 017 Conduit Penetration Seal Passive - Incorporated 89 4" Conduit Penetration 018 Conduit Penetration Seal Passive - Incorporated 90 4" Conduit Penetration 019 Conduit Penetration Seal Passive - Incorporated 91 4" Conduit Penetration 020 Conduit Penetration Seal Passive - Incorporated 92 4" Conduit Penetration 021 Conduit Penetration Seal Passive -Incorporated 93 4" Conduit Penetration 022 Conduit Penetration Seal Passive -Incorporated 94 4" Conduit Penetration 023 Conduit Penetration Seal Passive -Incorporated 95 4" Conduit Penetration 024 Conduit Penetration Seal Passive -Incorporated 96 4" Conduit Penetration 025 Conduit Penetration Seal Passive -Incorporated 97 4" Conduit Penetration 026 Conduit Penetration Seal Passive -Incorporated 98 Rectangular Penetration 5'9" x 1'-6" 027 Penetration Seal Passive -Incorporated 99 24" Pipe 242 Penetration Seal Passive - Incorporated 100 MW-13 Monitor Well Passive - Incorporated 101 4" Conduit Penetration 028 Conduit Penetration Seal Passive -Incorporated 102 4" Conduit Penetration 029 Conduit Penetration Seal Passive -Incorporated 103 4" Conduit Penetration 030 Conduit Penetration Seal Passive -Incorporated 104 4" Conduit Penetration 031 Conduit Penetration Seal Passive -Incorporated 105 4" Conduit Penetration 033 Conduit Penetration Seal Passive -Incorporated 106 4" Conduit Penetration 034 Conduit Penetration Seal Passive -Incorporated 107 4" Conduit Penetration 035 Conduit Penetration Seal Passive -Incorporated 108 4" Conduit Penetration 037 Conduit Penetration Seal Passive -Incorporated 109 4" Conduit Penetration 038 Conduit Penetration Seal Passive -Incorporated 110 4" Conduit Penetration 039 Conduit Penetration Seal Passive -Incorporated Page 30

NTIF Recommendation 2.3 (Walkdowns): Flooding Exelon Corporation October 31,2012 Revision 0 Table #3 - Ust of Features Immediately Judged as Acceptable PasslvelActive Feature ID#

" Description Incorporated/Temporary 111 2" Conduit Penetration 041 Conduit Penetration Seal Passive -Incorporated 112 2" Conduit Penetration 042 Conduit Penetration Seal Passive - Incorporated 113 2" Conduit Penetration 043 Conduit Penetration Seal Passive -Incorporated 114 2" Conduit Penetration 044 Conduit Penetration Seal Passive -Incorporated 115 4" Conduit Penetration 047 Conduit Penetration Seal Passive -Incorporated 116 4" Conduit Penetration 048 Conduit Penetration Seal Passive -Incorporated 117 4" Conduit Penetration 052 Conduit Penetration Seal Passive -Incorporated 118 4" Conduit Penetration 056 Conduit Penetration Seal Passive - Incorporated 119 4" Conduit Penetration 057 Conduit Penetration Seal Passive - Incorporated 120 4" Conduit Penetration 058 Conduit Penetration Seal Passive - Incorporated 121 4" Conduit Penetration 059 Conduit Penetration Seal Passive -Incorporated 122 4" Conduit Penetration 060 Conduit Penetration Seal Passive -Incorporated 123 4" Conduit Penetration 061 Conduit Penetration Seal Passive -Incorporated 124 4" Conduit Penetration 062 Conduit Penetration Seal Passive -Incorporated 125 4" Conduit Penetration 063 Conduit Penetration Seal Passive -Incorporated 126 4" Conduit Penetration 064 Conduit Penetration Seal Passive -Incorporated 127 4" Conduit Penetration 065 Conduit Penetration Seal Passive -Incorporated 128 4" Conduit Penetration 066 Conduit Penetration Seal Passive -Incorporated 129 4" Conduit Penetration 067 Conduit Penetration Seal Passive -Incorporated 130 4" Conduit Penetration 068 Conduit Penetration Seal Passive -Incorporated 131 4" Conduit Penetration 069 Conduit Penetration Seal Passive -Incorporated 132 4" Conduit Penetration 070 Conduit Penetration Seal Passive -Incorporated 133 4" Conduit Penetration 071 Conduit Penetration Seal Passive -Incorporated 134 4" Conduit Penetration 072 Conduit Penetration Seal Passive -Incorporated 135 2" Conduit Penetration 073 Conduit Penetration Seal Passive -Incorporated 136 2" Conduit Penetration 074 Conduit Penetration Seal Passive -Incorporated 137 2" Conduit Penetration 075 Conduit Penetration Seal Passive -Incorporated 138 4" Conduit Penetration 076 Conduit Penetration Seal Passive -Incorporated Page 31

NTTF Recommendation 2.3 (Walkdowns): Flooding Exelon Corporation October 31, 2012 Revision 0 Table #3 - List of Features Immediately Judged as Acceptable

, Feature ID" Description Passive/Active Incorporated/Temporary 139 2" Conduit Penetration 077 Conduit Penetration Seal Passive -Incorporated 140 2" Conduit Penetration 078 Conduit Penetration Seal Passive - Incorporated 141 2" Conduit Penetration 079 Conduit Penetration Seal Passive - Incorporated 142 4" Conduit Penetration 080 Conduit Penetration Seal Passive -Incorporated 143 4" Conduit Penetration 081 Conduit Penetration Seal Passive - Incorporated 144 4" Conduit Penetration 082 Conduit Penetration Seal Passive -Incorporated 145 4" Conduit Penetration 083 Conduit Penetration Seal Passive - Incorporated 146 4" Conduit Penetration 084 Conduit Penetration Seal Passive -Incorporated 147 4" Conduit Penetration 086 Conduit Penetration Seal Passive - incorporated 148 4" Conduit Penetration 087 Conduit Penetration Seal Passive - Incorporated 149 4" Conduit Penetration 088 Conduit Penetration Seal Passive -Incorporated 150 4" Conduit Penetration 090 Conduit Penetration Seal Passive - Incorporated 151 4" Conduit Penetration 091 Conduit Penetration Seal Passive - Incorporated 152 4" Conduit Penetration 092 Conduit Penetration Seal Passive -Incorporated 153 4" Conduit Penetration 094 Conduit Penetration Seal Passive -Incorporated 154 4" Conduit Penetration 095 Conduit Penetration Seal Passive - Incorporated 155 4" Conduit Penetration 096 Conduit Penetration Seal Passive -Incorporated 156 4" Conduit Penetration 098 Conduit Penetration Seal Passive -Incorporated 157 4" Conduit Penetration 099 Conduit Penetration Seal Passive -Incorporated 158 4" Conduit Penetration 100 Conduit Penetration Seal Passive - Incorporated 159 4" Conduit Penetration 101 Conduit Penetration Seal Passive -Incorporated 160 4" Conduit Penetration 102 Conduit Penetration Seal Passive -Incorporated 161 4" Conduit Penetration 103 Conduit Penetration Seal Passive -Incorporated 162 4" Conduit Penetration 104 Conduit Penetration Seal Passive -Incorporated 163 4" Conduit Penetration 105 Conduit Penetration Seal Passive -Incorporated Rectangular Penetration 3'-3" x 2'-0" Penetration Seal Passive -Incorporated 164 106 165 4" Conduit Penetration 107 Conduit Penetration Seal Passive -Incorporated Page 32

NTTF Recommendation 2.3 (Walkdowns): Flooding Exelon Corporation October 31, 2012 Revision 0 Table #3 - Ust of Features Immediately Judged as Acceptable Passive/Active

1. Feature 10# Description Incorporated/Temporary 166 4" Conduit Penetration 108 Conduit Penetration Seal Passive -Incorporated 167 4" Conduit Penetration 109 Conduit Penetration Seal Passive -Incorporated 168 4" Conduit Penetration 110 Conduit Penetration Seal Passive - Incorporated 169 4" Conduit Penetration 111 Conduit Penetration Seal Passive - Incorporated 170 4" Conduit Penetration 112 Conduit Penetration Seal Passive - Incorporated 171 4" Conduit Penetration 113 Conduit Penetration Seal Passive -Incorporated 172 4" Conduit Penetration 114 Conduit Penetration Seal Passive - Incorporated 173 4" Conduit Penetration 115 Conduit Penetration Seal Passive -Incorporated 174 4" Conduit Penetration 116 Conduit Penetration Seal Passive - Incorporated 175 4" Conduit Penetration 118 Conduit Penetration Seal Passive -Incorporated 176 4" Conduit Penetration 127 Conduit Penetration Seal Passive - Incorporated 177 4" Conduit Penetration 128 Conduit Penetration Seal Passive -Incorporated 178 4" Conduit Penetration 129 Conduit Penetration Seal Passive -Incorporated 179 4" Conduit Penetration 131 Conduit Penetration Seal Passive - Incorporated 180 24" Pipe Sleeve 133 Pipe Penetration Seal Passive - Incorporated West Wall Turbine Building (excluding Wall Passive - Incorporated 181 condenser bay) 182 6" Dike 362 Dike Passive - Incorporated 183 6" Dike 363 Dike Passive - Incorporated 184 4" Area Drain 366 Area Drain Passive -Incorporated 185 6" Dike 364 Dike Passive -Incorporated 186 6" Dike 365 Dike Passive - Incorporated 187 4" Area Drain 367 Area Drain Passive - Incorporated 188 4" Floor Drain 306 Area Drain Passive - Incorporated 189 4" Floor Drain 320 Area Drain Passive - Incorporated 190 4" Floor Drain 321 Area Drain Passive - Incorporated 191 4" Floor Drain 323 Area Drain Passive - Incorporated 192 4" Floor Drain 324 Area Drain Passive - Incorporated Page 33

NTIF Recommendation 2.3 (Walkdowns): Flooding Exelon Corporation October 31,2012 Revision 0 Table #3 - Ust of Features Immediately Judged as Acceptable PassivelActive

1. Feature 10# Description Incorporated/Temporary 193 1'6" x 2' Duct Bank 307 Duct Bank Passive -Incorporated 194 l' x 2' Duct Bank 316 Duct Bank Passive -Incorporated 195 4" Conduit 308 Conduit Penetration Seal Passive - Incorporated 196 4" Conduit 309 Conduit Penetration Seal Passive -Incorporated 197 4" Conduit 312 Conduit Penetration Seal Passive - Incorporated 198 3" Conduit 314 Conduit Penetration Seal Passive -Incorporated 199 3" Conduit 315 Conduit Penetration Seal Passive -Incorporated 200 4" Conduit 317 Conduit Penetration Seal Passive -Incorporated 201 4" Conduit 318 Conduit Penetration Seal Passive -Incorporated 202 4" Conduit 319 Conduit Penetration Seal Passive -Incorporated 203 EDG1 floors Wall Passive - Incorporated 204 1'6" x 2' Duct Bank 326 Duct Bank Passive - Incorporated 205 l' x 2' Duct Bank 335 Duct Bank Passive -Incorporated 206 4" Floor Drain 325 Area Drain Passive - Incorporated 207 4" Floor Drain 340 Area Drain Passive -Incorporated 208 4" Floor Drain 341 Area Drain Passive -Incorporated 209 4" Floor Drain 342 Area Drain Passive -Incorporated 210 4" Floor Drain 344 Area Drain Passive -Incorporated 211 3" Conduit 333 Conduit Penetration Seal Passive -Incorporated 212 4" Conduit 336 Conduit Penetration Seal Passive - Incorporated 213 4" Conduit 337 Conduit Penetration Seal Passive -Incorporated 214 4" Conduit 338 Conduit Penetration Seal Passive - Incorporated 215 EDG2 floors Floor Passive -Incorporated East Wall Emergency Diesel Generator Wall Passive -Incorporated 216 Building North Wall Emergency Diesel Generator Wall Passive -Incorporated 217 Building South Wall Emergency Diesel Generator Wall Passive -Incorporated 218 Building Page 34

NTIF Recommendation 23 (Walkdowns): Flooding Exelon Corporation October 31, 2012 Revision 0 Table #3 - Ust of Features Immediately Judged as Acceptable Passive/Active

1. FeaturelD# Description I ncorporated/Temporary West Wall Emergency Diesel Generator Wall Passive -Incorporated 219 Building 220 D. O. Tank Sump Sump Passive -Incorporated 221 8" Sleeve 303 Penetration Seal Passive -Incorporated North Wall Emergency Diesel Generator Wall Passive -Incorporated 222 Building DO Vault South Wall Emergency Diesel Generator Wall Passive -Incorporated 223 Building DO Vault West Wall Emergency Diesel Generator Wall Passive -Incorporated 224 Building DO Vault 225 D.O. floors Floor Passive -Incorporated Page 35

NTIF Recommendation 2.3 (Walkdowns): Flooding Exelon Corporation October 31, 2012 Revision 0 Table # 4: Ust of Features Not Immediately Judged as Acceptable Component

1. FeaturelD# Description Observation Resolution Operability Pipe 16" Pipe Sleeve 1 Penetration 281 ARA2312529 Seal has been issued Corrosion on Pipe Yes- to paint the area 6" Pipe Sleeve penetration and signs 2 Penetration Documented in under the 282 of water seepage on Seal IR 01402009 penetration.

wall.

Approved, not Pipe 16" Pipe Sleeve scheduled yet.

3 Penetration 283 Seal

, ARA2312528 has been issued Corrosion on Rectangular Yes- to paint the area Penetration penetration pipe flange 4 Penetration 4'x2' Documented in under the Seal and signs of water 278 IR 01402045 penetration.

seepage on wall.

Approved, not scheduled yet.

Conduit 4" Conduit 5 Penetration Penetration 245 ARA2313047 Seal There is extensive corrosion on these Issued to clean Conduit the area under 4" Conduit penetration sleeves, 6 Penetration the Penetration 246 and stalactite growth Yes-Seal penetrations.

underneath the Documented in Conduit penetration and cap. Not scheduled 4" Conduit IR 01407010 7 Penetration yet. Closed to Penetration 358 existing Seal preventative There is stalactite maintenance.

4" Conduit Seal Conduit 8 growth underneath this 358A Internal Seal conduit.

AR A2313693 Corrosion on has been issued Rectangular Yes-Penetration penetration and signs to paint area 9 Penetration 3' x Documented in Seal of water seepage on under the 2'229 IR 01412372 wall. penetration.

Not yet scheduled Page 36

NTTF Recommendation 2.3 (Walkdowns): Flooding Exelon Corporation October 31, 2012 Revision 0 Table # 4: Ust of Features Not Immediately Judged as Acceptable Component

1. Feature 10 " Description Observation Resolution Operability Rectangular Penetration Penetration 4'x2' 10 Seal ARA2313692 269 has been issued Corrosion on Rectangular Yes- to paint the area Penetration penetration and signs 11 Penetration 3'x2' Documented in under the Seal of water seepage on 270 IR01412397 penetration. Has wall.

not been Rectangular Penetration sched uled yet.

12 Penetration 3'x2' Seal 271 Area underthe Corrosion on Rectangular Yes- penetration to Penetration penetration and signs 13 Penetration 4'x2' Documented in be painted. Has Seal of water seepage on 273 IR 01415778 not been wall.

scheduled yet.

ARA2313043 No-issued to cap Documented in Rectangular conduit, Penetration Penetrating conduit is IR 01406089.

14 Penetration 4'- scheduled to be Seal cut and uncapped. See discussion in 6" x 1'6" 040 completed no Resolution later than column 11/27/2012 Conduit According to 4"Conduit 15 Penetration plant engineers, Penetration 045 Seal liThe docu mentation Conduit 4" Conduit provided in 16 Penetration Penetration 046 assignment Seal 01405765*04 Conduit Water intrusion states the Impact 4" Conduit No-17 Penetration through these on flooding is Penetration 049 Documented in Seal penetrations was negligible ... cable IR 01405765.

observed at roughly 40 drainage Is Conduit See discussion In 4" Conduit drops per minute preferred 18 Penetration Resolution Penetration 050 during a light because it Seal column.

rainstorm. minimizes the Conduit amount of time 4" Conduit 19 Penetration the electrical Penetration 051 Seal cables are wetted ... from a Conduit 4" Conduit flooding 20 Penetration Penetration 053 electrical Seal standpoint, the Page 37

NTTF Recommendation 2.3 (Walkdowns): Flooding Exelon Corporation October 31,2012 Revision 0 Table # 4: Ust of Features Not Immediately Judged as Acceptable Component

1. Feature 10. Description Observation Resolution Operability Conduit seals do not 4" Conduit 21 Penetration need to be Penetration 054 Seal repaired. No further actions Conduit 4" Conduit required" 22 Penetration Penetration 055 Seal Conduit 4" Conduit 23 Penetration Penetration 117 Seal Conduit 4" Conduit 24 Penetration Penetration 119 Seal According to plant engineers, Conduit 4" Conduit "The leak noted 25 Penetration Penetration 120 in [Turbine Seal Building]

Conduit basement is 4" Conduit 26 Penetration from conduit Penetration 121 Penetration seals Seal No- that goes to appear to be severely Documented in EDG. This is Conduit degraded, and signs of 4" Conduit IR 01406841. expected 27 Penetration past water intrusion Penetration 122 See discussion in leakage. The Seal are apparent on walls Resolution design is to underneath Conduit column. prevent any 4" Conduit penetrations.

28 Penetration waterfrom Penetration 123 Seal accumulating in condUit, instead Conduit 4" Conduit any water that 29 Penetration Penetration 124 enters conduit is Seal directed to the Conduit 1-5 sump" 4" Conduit 30 Penetration Penetration 125 Seal Conduit 4" Conduit 31 Penetration Penetration 126 Seal Page 38

NTIF Recommendation 2.3 (Walkdowns): Flooding Exelon Corporation October 31, 2012 Revision 0 Table # 4: Ust of Features Not Immediately Judged as Acceptable Component

1. Feature ID# Description Observation Resolution Operability ARA2313037 No-Penetrating conduit is issued to cap Documented in Pipe cut and uncapped. A conduit, 6" Pipe Sleeve IR 01406952.

32 Penetration seal inside the scheduled to be 134 See discussion in Seal penetrating conduit is completed no Resolution not visible. later than column 11/27/2012 Cu rrent site topography is being Since the most recent documented, PMP flooding and a revised calculation in 2000, site Yes- PMP flooding topography has Documented in study is being OCNGSSite changed, including the IR 01404344. performed as 33 Topography installation of security See discussion in part of the barriers and new Resolution Fukushima buildings, and re- column Response Effort.

grading around the Current EDG building. configuration determined not to negatively impact SSCs.

34 Area Drain 351 Area Drain Area drains and ARA2313982 No-scupper are partially issued to repair 35 Area Drain 353 Area Drain Documented in clogged with debris. drains, IR 01419031. Se Area Drain 353's drain scheduled to be discussion in 4" Scupper Type cap appears to have completed no 36 Scupper Resolution Roof Drain 295 been installed upside later than column down. 11/27/2012 Page 39

NTTF Recommendation 2.3 (Walkdowns): Flooding Exelon Corporation October 31,2012 Revision 0 Table # 5: Ust of Features in Restricted Access Areas

1. Feature ID# Description Reason Resolution 1 2" Conduit Penetration Conduit Penetration 136 Seal 2 2" Conduit Penetration Conduit Penetration 137 Seal 3 2" Conduit Penetration Conduit Penetration 138 Seal 4 4" Conduit Penetration Conduit Penetration 139 Seal 5 2" Conduit Penetration Conduit Penetration 140 Seal 6 2" Conduit Penetration Conduit Penetration 141 Seal 7 2" Conduit Penetration Conduit Penetration 142 Seal 8 4" Conduit Penetration Conduit Penetration These features are 143 Seal in the Condenser To be evaluated 9 4" Conduit Penetration Conduit Penetration Bay, SJAE room, during the 1R24 144 Seal and High Low Refueling Outage Room, all of which October 2012 10 4" Conduit Penetration Conduit Penetration are significantly 145 Seal lower dose during 11 4" Conduit Penetration Conduit Penetration outage.

146 Seal 12 24" Pipe Sleeve 147 Pipe Penetration Seal 13 Rectangular Penetration Penetration Seal 3 x 1'-6" 148 14 2" Conduit Penetration Conduit Penetration 149 Seal 15 2" Conduit Penetration Conduit Penetration 150 Seal 16 2" Conduit Penetration Conduit Penetration 151 Seal 17 2" Conduit Penetration Conduit Penetration 152 Seal 18 4" Conduit Penetration Conduit Penetration 153 Seal Page 40

NTIF Recommendation 2.3 (Walkdowns): Flooding Exelon Corporation October 31,2012 Revision 0 Table # 5: Ust of Features in Restricted Access Areas

1. Feature 10# Description Reason Resolution 19 4" Conduit Penetration Conduit Penetration 154 Seal 20 4" Conduit Penetration Conduit Penetration 155 Seal 21 4" Conduit Penetration Conduit Penetration 156 Seal 22 4" Conduit Penetration Conduit Penetration 157 Seal 23 4" Conduit Penetration Conduit Penetration 158 Seal 24 4" Conduit Penetration Conduit Penetration 159 Seal 25 4" Conduit Penetration Conduit Penetration 160 Seal 26 4" Conduit Penetration Conduit Penetration 161 Seal These features are in the Condenser To be evaluated 27 4" Conduit Penetration Conduit Penetration Bay, SJAE room, during the 1R24 162 Seal and High Low Refueling Outage 28 4" Conduit Penetration Conduit Penetration Room, all of which October 2012 163 Seal are significantly lower dose during 29 4" Conduit Penetration Conduit Penetration outage.

164 Seal 30 4" Conduit Penetration Conduit Penetration 165 Seal 31 4" Conduit Penetration Conduit Penetration 166 Seal 32 4" Conduit Penetration Conduit Penetration 167 Seal 33 4" Conduit Penetration Conduit Penetration 168 Seal 34 4" Conduit Penetration Conduit Penetration 169 Seal 35 4" Conduit Penetration Conduit Penetration 170 Seal 36 4" Conduit Penetration Conduit Penetration 171 Seal Page 41

NTIF Recommendation 2.3 (Walkdowns): Flooding Exelon Corporation October 31, 2012 Revision 0 Table # 5: Ust of Features in Restricted Access Areas

1. Feature 10# Description Reason Resolution 37 4" Conduit Penetration Conduit Penetration 172 Seal 38 4" Conduit Penetration Conduit Penetration 173 Seal 39 4" Conduit Penetration Conduit Penetration 174 Seal 40 4" Conduit Penetration Conduit Penetration 175 Seal 41 4" Conduit Penetration Conduit Penetration 176 Seal 42 4" Conduit Penetration Conduit Penetration 1n Seal 43 4" Conduit Penetration Conduit Penetration 178 Seal 44 4" Conduit Penetration Conduit Penetration 179 Seal These features are in the Condenser To be evaluated 45 4" Conduit Penetration Conduit Penetration Bay, SJAE room, during the 1R24 180 Seal and High Low Refueling Outage 46 4" Conduit Penetration Conduit Penetration Room, all of which October 2012 181 Seal are significantly lower dose during 47 4" Conduit Penetration Conduit Penetration outage.

182 Seal 48 4" Conduit Penetration Conduit Penetration 183 Seal 49 4" Conduit Penetration Conduit Penetration 184 Seal 50 4" Conduit Penetration Conduit Penetration 185 Seal 51 4" Conduit Penetration Conduit Penetration 186 Seal 52 4" Conduit Penetration Conduit Penetration 187 Seal 53 4" Conduit Penetration Conduit Penetration 188 Seal 54 4" Conduit Penetration Conduit Penetration 189 Seal Page 42

NTTF Recommendation 2.3 (Walkdowns): Flooding Exelon Corporation October 31,2012 Revision 0 Table # 5: Ust of Features in Restricted Access Areas

1. Feature 10# Description Reason Resolution 55 4" Conduit Penetration Conduit Penetration 190 Seal 56 4" Conduit Penetration Conduit Penetration 191 Seal 57 4" Conduit Penetration Conduit Penetration 192 Seal 58 2" Conduit Penetration Conduit Penetration 193 Seal 59 2" Conduit Penetration Conduit Penetration 194 Seal 60 2" Conduit Penetration Conduit Penetration 195 Seal 61 2" Conduit Penetration Conduit Penetration 196 Seal 62 18" Pipe Sleeve 197 Pipe Penetration Seal lhese features are 63 4" Conduit Penetration Conduit Penetration in the Condenser To be evaluated 198 Seal Bay, SJAE room, during the 1R24 64 4" Conduit Penetration Conduit Penetration and High Low Refueling Outage 199 Seal Room, all of which October 2012 are significantly 65 4" Conduit Penetration Conduit Penetration lower dose during 200 Seal outage.

66 4" Conduit Penetration Conduit Penetration 201 Seal 67 4" Conduit Penetration Conduit Penetration 202 Seal 68 4" Conduit Penetration Conduit Penetration 203 Seal 69 4" Conduit Penetration Conduit Penetration 204 Seal 70 4" Conduit Penetration Conduit Penetration 205 Seal 71 4" Conduit Penetration Conduit Penetration 206 Seal 72 4" Conduit Penetration Conduit Penetration 207 Seal 73 10" Pipe Sleeve 208 Pipe Penetration Seal Page 43

NTIF Recommendation 2.3 (Walkdowns): Flooding Exelon Corporation October 31, 2012 Revision 0 Table # 5: Ust of Features in Restricted Access Areas

1. Feature 10 " Description Reason Resolution 74 16" Pipe Sleeve 209 Pipe Penetration Seal 75 3" Pipe Sleeve 210 Pipe Penetration Seal 76 16" Pipe Sleeve 211 Pipe Penetration Seal 77 16" Pipe Sleeve 212 Pipe Penetration Seal 78 4" Conduit Penetration Conduit Penetration 213 Seal 79 4" Conduit Penetration Conduit Penetration 214 Seal 80 4" Conduit Penetration Conduit Penetration 215 Seal 81 4" Conduit Penetration Conduit Penetration 216 Seal 82 4" Conduit Penetration Conduit Penetration 346 Seal 83 4" Conduit Penetration Conduit Penetration These features are 347 Seal in the Condenser To be evaluated 84 4" Conduit Penetration Conduit Penetration Bay, SJAE room, during the lR24 348 Seal and High Low Refueling Outage Room, all of which October 2012 85 4" Conduit Penetration Conduit Penetration are significantly 349 Seal lower dose during 86 20" Pipe Sleeve 217 Pipe Penetration Seal outage.

87 Manhole Cover and Manhole Cover 243 Seal 88 Manhole Cover and Manhole Cover 244 Seal 89 Condenser Bay floor Condenser Bay floor 90 West Wall Turbine Wall Building Condenser Bay 91 Rectangular Penetration Penetration Seal 3'6" x 3'6" 218 92 4" Conduit Penetration Conduit Penetration 230 Seal 93 4" Conduit Penetration Conduit Penetration 231 Seal 94 4" ConduIt Penetration Conduit Penetration 232 Seal Page 44

NTTF Recommendation 2.3 (Walkdowns): Flooding Exelon Corporation October 31, 2012 Revision 0 Table # 5: Ust of Features In Restricted Access Areas

1. Feature ID# Description Reason Resolution 95 4" Conduit Penetration Conduit Penetration 233 Seal 96 4" Conduit Penetration Conduit Penetration 234 Seal 97 4" Conduit Penetration Conduit Penetration 235 Seal 98 4" Conduit Penetration Conduit Penetration 236 Seal 99 4" Conduit Penetration Conduit Penetration 237 Seal 100 4" Conduit Penetration Conduit Penetration These features are 238 Seal in the Condenser Bay, SJAE room, 101 4" Conduit Penetration Conduit Penetration and High Low 239 Seal Room, all of which 102 4" Conduit Penetration Conduit Penetration are significantly 240 Seal lower dose during outage.

103 4" Conduit Penetration Conduit Penetration To be evaluated 241 Seal during the 1R24 104 40" Pipe Sleeve 001 Pipe Penetration Seal Refueling Outage October 2012 105 40" Pipe Sleeve 002 Pipe Penetration Seal 106 Rectangular Penetration Penetration Seal 3 x 1'-6" 003 107 East Wall Turbine Building Wall (SJAE/High-Low Room) 108 South Wall Turbine Wall Building (SJAE Room) 109 3" Pipe Sleeve (plant These features Pipe Penetration Seal ground penetration) seals are inside long lengths of 110 pipe, and will 6" Pipe Sleeve 135 Pipe Penetration Seal require special equipment in order to observe 111 4" Conduit 310 Penetration Seal These features are in the DG1 and 112 4" Conduit 311 Penetration Seal DG2 cable 113 4" Conduit 313 Penetration Seal trenches, and can only be accessed 114 4" Conduit 327 Penetration Seal when the Diesel Page 45

NTIF Recommendation 2.3 (Walkdowns): Flooding Exelon Corporation October 31,2012 Revision 0 Table # 5: Ust of Features in Restricted Access Areas

1. Feature 10 , Description Reason Resolution 115 4" Conduit 328 Penetration Seal Generators are offline to ensure 116 4" Conduit 329 Penetration Seal To be evaluated they are during the 1R24 117 4" Conduit 330 Penetration Seal denergized.

Refueling Outage 118 4" Conduit 331 Penetration Seal October 2012 119 4" Conduit 332 Penetration Seal 120 4" Conduit 334 Penetration Seal Page 46

NTTF Recommendation 2.3 (Walkdowns): Flooding Exelon Corporation October 31, 2012 Revision 0 Table # 6: Ust of Features in Inaccessible Areas

1. Feature 10# Description Reason Resolution Conduit Internal 1 4" Conduit Seal 224A Seal Conduit Internal 2 4" Conduit Seal 225A Seal Conduit Internal 3 4" Conduit Seal 226A Seal Conduit Internal 4 4" Conduit Seal 248A Seal Conduit Internal 5 4" Conduit Seal 287A Seal Conduit Internal 6 4" Conduit Seal 357A Seal Conduit Internal 7 4" Conduit Seal 359A Seal Conduit Internal Conduits at OCNGS could not 8 4" Conduit Seal 008A be disassembled for Seal Reasonable inspection during the Assurance Conduit Internal walkdown, and no 9 4" Conduit Seal 009A Documented in Seal accommodation for Part E of the Conduit Internal inspection of the internal Walkdown Record 10 4" Conduit Seal 010A seals was made when the Seal Forms plant was built. Major Conduit Internal equipment disassembly 11 4" Conduit Seal 012A Seal would be required to access.

Conduit Internal 12 4" Conduit Seal 013A Seal Conduit Internal 13 4" Conduit Seal 016A Seal Conduit Internal 14 4" Conduit Seal 067A Seal Conduit Internal 15 4" Conduit Seal 068A Seal Conduit Internal 16 4" Conduit Seal 069A Seal Conduit Internal 17 4" Conduit Seal 070A Seal Conduit Internal 18 4" Conduit Seal onA Seal Page 47

NTTF Recommendation 2.3 (Walkdowns): Flooding Exelon Corporation October 31, 2012 Revision 0 Table # 6: Ust of Features in Inaccessible Areas

1. Feature 10# Description Reason Resolution Conduit Internal 19 4" Conduit Seal 081A Seal Conduit Internal 20 4" Conduit Seal115A Seal Conduits at OCNGS could not be disassembled for Conduit Internal 21 4" Conduit Seal116A inspection during the Seal walkdown, and no Conduit Internal accommodation for 22 4" Conduit Seal 127A Seal Inspection of the Internal seals was made when the Conduit Internal 23 4" Conduit Seal 128A plant was built. Major Seal equipment disassembly Conduit Internal would be required to access.

24 4" Conduit Seal 129A Seal Conduit Internal 25 4" Conduit Seal131A Seal This penetration includes a cut conduit, and the camera Reasonable on a pole used for OCNGS Assurance walkdowns was not able to Documented in Rectangular capture images of the inside. Part E of the 26 Penetration 3 x 1'*6" Penetration Seal To access this penetration by Walkdown Record 006 ladder or scaffold, a cable Forms tray would need to be removed. Major equipment disassembly would be required to access.

4" Conduit Conduit The camera on a pole was not 27 Penetration 032 penetration seal able to capture images of internal seals, and access 4" Conduit Conduit would require major 28 Penetration 036 penetration seal disassembly of equipment 4" Conduit Conduit 29 Penetration 085 penetration seal Conduits are permanently 4" Conduit Conduit covered with a plaster*llke 30 Penetration 089 penetration seal coating that prevents direct 4" Conduit Conduit inspection. Major equipment 31 disassembly would be Penetration 093 penetration seal required to access.

4" Conduit Conduit 32 Penetration 097 penetration seal Page 48

NTTF Recommendation 2.3 (Walkdowns): Flooding Exelon Corporation October 31, 2012 Revision 0 Table # 6: Ust of Features in Inaccessible Areas

1. Feature 10# Description Reason Resolution 4" Conduit Conduit 33 Penetration 130 penetration seal 4" Conduit Conduit 34 Penetration 132 penetration seal 35 4" Floor Drain 322 Area Drain These floor drains are located directly under Diesel Generators 1 and 2, and 36 4" Floor Drain 343 Area Drain cannot be observed. Major equipment disassembly would be required to access.

Reasonable Much of the system is buried, Assurance and could not be observed Documented in Roof & Overboard 37 3D" O.V. Drain during the walkdowns. There Part E of the Drainage System is no practical way to inspect Walkdown Record this whole system. Forms 38 Sump 1-1 Turbine Building There is no practical means to evaluate the bottom of the 1-1 and 1-5 sump, as both are 39 Sump 1-5 Turbine Building under water.

The Turbine Building base slab is at 0' MSL, and buried Turbine Building under the Turbine Building 40 Turbine Building Base Slab floor and a bed of sand.

There is no reasonable means of access.

4" Conduit Conduit 41 Penetration 045 penetration seal 4" Conduit Conduit 42 These penetrations are Penetration 046 penetration seal permanently covered in These features 4" Conduit Conduit fireproofing, which is were entered into 43 Penetration 049 penetration seal required to provide site CAP due to 4" Conduit Conduit separation between DGl and observations 44 DG2 cables. Major associated with Penetration 050 penetration seal equipment disassembly them . See Table 4.

4" Conduit Conduit would be required to access.

45 Penetration 053 penetration seal 4" Conduit Conduit 46 Penetration 054 penetration seal Page 49

NTIF Recommendation 2.3 (Walkdowns): Flooding Exelon Corporation October 31, 2012 Revision 0 Table # 6: Ust of Features in Inaccessible Areas

1. Feature 10# Description Reason Resolution Conduits at OCNGS could not Conduit Internal be disassembled for 47 4" Conduit Seal 358A Seal inspection during the walkdown Page SO

NTTF Recommendation 2.3 (Walkdowns): Flooding Exelon Corporation October 31,2012 Revision 0

6. REFERENCES

1. Exelon Letter to U.S. Nuclear Regulatory Commission. Exelon Generation Company, LLC's 90-Day Response to March 12, 2012 Request for Information Pursuant to Title 10 oj the Code of Federal Regulations 50.54(f) Regarding Recommendations 2.1 and 2.3, of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident (Flooding). June 11, 2012.

2. Nuclear Energy Institute (NEI), Report 12-07 [Rev O-A]. Guidelines for Performing Verification Walkdowns of Plant Protection Features. May 2012 [NRC endorsed May 31,2012; updated and re-issued June 18, 2012].

3. U.S. Nuclear Regulatory Commission. Letter to Licensees. Request for Information Pursuant to Title 10 of the Code of Federal Regulations 50.54(t) Regarding Recommendations 2.1, 2.3, and 9.3 of the Near Term Task Force Review of Insights from the Fukushima Dai-ichi Accident. March 12, 2012.

4. U.S. Nuclear Regulatory Commission. Demonstrating the Feasibility and Reliability of Operator Manual Actions in Response to Fire. NUREG-1852. October 2007.

5. U.S. Nuclear Regulatory Commission. Recommendations for Enhancing Reactor Safety in the 21st Century, The Near Term Task Force Review of Insights from the Fukushima Dai-ichi Accident. July 12, 2011.

6. U.S. Nuclear Regulatory Commission. Operability Determinations & Functionality Assessments for Resolution of Degraded or Nonconforming Conditions Adverse to Quality or Safety. NRC Inspection Manual. Part 9900: Technical Guidance. Regulatory Issues Summary 2005-20, Revisions 1.

September 26, 2005.

7. Institute of Nuclear Power Operations. Fukushima Dai-ichi Nuclear Station Fuel Damage Caused by Earthquake and Tsunami. INPO Event Report 11-1. March 15, 2011.

8. U.S. Nuclear Regulatory Commission. Follow-up to the Fukushima Dai-ichi Nuclear Station Fuel Damage Event. Inspection Manual. Temporary Instruction 2515/183. ML113220407. November 2011.

9. U.S. Nuclear Regulatory Commission. Inspection of Structures, Passive Components, and Civil Engineering Features at Nuclear Power Plants. Inspection Manual. Inspection Procedure 62002.

Section 03.01(h), Dams, Embankments and Canals.

10. U.S. Nuclear Regulatory Commission. Evaluate Readiness to Cope with External Flooding. Inspection Procedures. Attachment 71111.01. Adverse Weather Protection. Section 02.04.

11. U.S. Nuclear Regulatory Commission. NRC Inspector Field Observation Best Practices. NUREG/BR-0326, Rev. 1. August 2009.

12. U.S. Nuclear Regulatory Commission. Flood Protection for Nuclear Power Plants. Regulatory Guide 1.102.

13. OCNGS UFSAR Revision 16, sections 2.3, 2.4, 3.2, 3.4, 3.8

14. B&R 2299, Rev. 0 - Civil/Structural index Book of Calculations Page Sl

NTIF Recommendation 2.3 (Walkdowns): Flooding Exelon Corporation October 31,2012 Revision 0

15. DWG B&R 4049, Rev. 7 - Reactor Building Foundation Plan & Sections

16. DWG B&R 4051, Rev. 4 - Reactor Building Foundation Wall Elevations and Sections

17. DWG B&R 4052, Rev. 3 - Reactor Building Foundation Wall Sections and Details

18. DWG B&R 4075, Rev. 8 - Turbine Building Foundation Plan

19. DWG B&R 4076, Rev. 6 - Turbine Building Foundation Plan

20. DWG B&R 4087, Rev. 7 - Turbine Building Foundation Walls Elevation

21. DWG B&R 4088, Rev. 7 - Turbine Building Foundation Walls Elevation

22. DWG B&R 4113, Rev. 9 - Reactor Building Wall Penetrations

23. DWG 3E-151-02-003, Rev. 11- General Arrangement Turbine Building Plan Floor Elevation 23'-6"

24. DWG 3E-151-02-o01, Rev. 12 - General Arrangement Turbine Building Plan Floor Elevation 0'-0" and 3'-6"

25. DWG 3E-153-02-001, Rev. 8 - General Arrangement Reactor Building Plan Floor Elevation (-) 19'-6"

26. DWG 3E-153-02-002, Rev.14 - General Arrangement Reactor Building Plan Floor Elevation 23'-6"

27. Procedure OP-OC-l08-109-1001- Severe Weather Preparation T&RM for Oyster Creek, Rev. 13

28. Procedure ABN High Winds, Rev. 17

29. Procedure ABN Abnormal Intake Level, Rev. 18

30. Procedure ABN Loss of Offsite Power, Rev. 20

31. Procedure 203 - Plant Shutdown, Rev. 62

32. Procedure ER-OC-450 - Oyster Creek Structures Monitoring, Rev. 3

33. Oyster Creek SEP Final Report (NUREG-0822) and Final Report Supplement 1

34. NRC Temporary Instruction 2515/183 Inspection Report for OCNGS

35. RA-11-024 OCNGS response for INPO Event Report level 111-1: Fukushima Daiichi Nuclear Station Fuel Damage. Transferred 4/15/2011.

36. IR 01405765

37. OCNGS Reply to RAI on IPEEE, 8/17/2000

38. ENERCON Services, Turbine Basement Water Intrusion Comprehensive Study for AmerGen Oyster s

Creek Nuclear Station. May 31 t, 2002.

Page 52

U.S. Nuclear Regulatory Commission 180-Day Response to 50.54(f) Letter NTTF Recommendation 2.3: Flooding November 19, 2012 Page 6 Enclosure 2

SUMMARY

OF REGULATORY COMMITMENTS The following table identifies commitments made in this document. (Any other actions discussed in the submittal represent intended or planned actions. They are described to the NRC for the NRC's information and are not regulatory commitments.)

COMMITTED COMMITMENT TYPE COMMITMENT DATE OR ONE-TIME ACTION PROGRAMMATIC "OUTAGE" (Yes/No) (Yes/No)

Exelon Generation Company, LLC (EGC) will OC1R24 Yes No complete the inspection of the 120 features Fall 2012 classified as restricted access.