ML21106A024

Enclosure B - Exemption Request No. 1

ML21106A024
Person / Time
Site:	Perry
Issue date:	04/07/2021
From:	Energy Harbor Nuclear Corp
To:	Office of Nuclear Reactor Regulation
References
L-21-002
Download: ML21106A024 (15)

Text

Enclosure B L-21-002 Request for Exemption No. 1 (14 pages follow)

Request for Exemption No. 1 Page 1 of 14

Subject:

Request for Exemption from Certain Requirements of 10 CFR 50, Appendix B, Quality Assurance Criteria for Nuclear Power Plants and Fuel Reprocessing Plants, to Credit Existing Non-Safety Related Protection Features as Flood Barriers 1.0 PURPOSE Pursuant to 10 CFR 50.12, Specific exemptions, Energy Harbor Nuclear Corp.

requests an exemption for Perry Nuclear Power Plant, Unit No. 1 (PNPP) from certain requirements of 10 CFR 50, Appendix B, Quality Assurance Criteria for Nuclear Power Plants and Fuel Reprocessing Plants. The requested exemption would credit existing (newly installed) non-safety related protection features, including permanent (passive) and temporary (deployable), as flood barriers that perform a mitigative function to act as an environmental interface for safety-related structures, systems, and components (SSCs) during external flood hazard events.

The requested exemption supports a license amendment request that includes a change in methodology used for analysis of flooding hazards at the site and a new flood hazard protection scheme. The request also supports a reconstitution effort for the design basis of the original probable maximum flood (PMF) event (small stream flood) and local intense precipitation (LIP) domain analyses (as well as other, less significant external flood hazards).

2.0 BACKGROUND

On March 12, 2012, the Nuclear Regulatory Commission (NRC) issued a letter titled, 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 (hereafter referred to as the 10 CFR 50.54(f) letter). During development of the response to the 10 CFR 50.54(f) letter, Energy Harbor Nuclear Corp. was unable to locate some of the analyses supporting the PNPP Updated Safety Analysis Report (USAR) discussions regarding external flooding hazards. As a result, Energy Harbor Nuclear Corp. initiated an effort reconstitute the design basis of the original PMF event (small stream flood) and LIP domain analyses.

In addition, throughout the life of the facility, various changes to the immediate (local) plant area have occurred that have influenced the LIP watershed. Changes such as installation of various security features (vehicle barrier system and jersey barriers, as well as the multi-layered perimeter fence) have affected the runoff characteristics of overland flow within and out of the LIP domain. Site improvement initiatives, such as the paving of grass and gravel areas, have resulted in changes to drainage patterns and runoff coefficients. These changes are being incorporated into the reconstituted analyses.

Request for Exemption No. 1 Page 2 of 14 Based on the reconstituted analyses, water surface elevations (WSE) resulting from external flood hazard events are above the nominal flood elevation of doors leading into plant structures at various locations.

As described in NUREG-0887, Safety Evaluation Report related to the operation of Perry Nuclear Power Plant, Units 1 and 2, Section 3.4.1, Flood Protection, the PNPP site was a dry site as defined in Regulatory Guide 1.102, Flood Protection for Nuclear Power Plants, Position C.1. For the purposes of Regulatory Guide 1.102, the Design Basis Flooding Level (DBFL) is defined as the maximum water elevation attained by the controlling flood, including coincident wind-generated wave effects. In the case of a dry site, the plant is built above the DBFL, and therefore safety-related SSCs are not affected by flooding.

10 CFR 50, Appendix A, General Design Criterion (GDC) 1, Quality standards and records, states:

Structures, systems, and components important to safety shall be designed, fabricated, erected, and tested to quality standards commensurate with the importance of the safety functions to be performed. Where generally recognized codes and standards are used, they shall be identified and evaluated to determine their applicability, adequacy, and sufficiency and shall be supplemented or modified as necessary to assure a quality product in keeping with the required safety function. A quality assurance program shall be established and implemented in order to provide adequate assurance that these structures, systems, and components will satisfactorily perform their safety functions. Appropriate records of the design, fabrication, erection, and testing of structures, systems, and components important to safety shall be maintained by or under the control of the nuclear power unit licensee throughout the life of the unit.

10 CFR 50, Appendix A, GDC 2, Design bases for protection against natural phenomena, states:

Structures, systems, and components important to safety shall be designed to withstand the effects of natural phenomena such as earthquakes, tornadoes, hurricanes, floods, tsunami, and seiches without loss of capability to perform their safety functions. The design bases for these structures, systems, and components shall reflect: (1) Appropriate consideration of the most severe of the natural phenomena that have been historically reported for the site and surrounding area, with sufficient margin for the limited accuracy, quantity, and period of time in which the historical data have been accumulated, (2) appropriate combinations of the effects of normal and accident conditions with the effects of the natural phenomena and (3) the importance of the safety functions to be performed.

Request for Exemption No. 1 Page 3 of 14 10 CFR 50, Appendix B, Quality Assurance Criteria for Nuclear Power Plants and Fuel Reprocessing Plants, states, in part:

Nuclear power plants and fuel reprocessing plants include structures, systems, and components that prevent or mitigate the consequences of postulated accidents that could cause undue risk to the health and safety of the public. This appendix establishes quality assurance requirements for the design, manufacture, construction, and operation of those structures, systems, and components. The pertinent requirements of this appendix apply to all activities affecting the safety-related functions of those structures, systems, and components; these activities include designing, purchasing, fabricating, handling, shipping, storing, cleaning, erecting, installing, inspecting, testing, operating, maintaining, repairing, refueling, and modifying.

As used in this appendix, quality assurance comprises all those planned and systematic actions necessary to provide adequate confidence that a structure, system, or component will perform satisfactorily in service.

These criteria were satisfied in the construction of the PNPP site. The controlling flood and associated water levels impacting the PNPP site are a result of the surface drainage capabilities during the LIP event. The safety-related structures of the plant are located within the LIP domain, which is shown in Figure 2-1 below. As described in the current PNPP USAR, the floors at plant grade are nominally set at elevation (EL) 620 feet (ft) 6 inches U.S. Geological Survey (USGS).

The PNPP USAR presents elevations using a USGS datum that is equivalent to the National Geodetic Vertical Datum of 1929 (NGVD 29). A plant-specific datum for PNPP, referred to as Perry Local Datum (PLD), was established to provide NGVD 29 data corrected to local monument markers. For reference, conversion for the North American Vertical Datum of 1988 (NAVD 88), for the International Great Lakes Datum of 1985 (IGLD 85), and for PLD are provided in Table 2-1 below.

Table 2-1: General Datum Conversions Datum Conversions (feet)

NGVD 29 NAVD 88 IGLD 85 PLD 0.00 -0.72 -0.94 +0.21 Station structures are passively protected against water levels up to EL 620 ft 6 inches, the nominal elevation of the building floors. The below-grade portions of the structures are provided with sealed penetrations and a watertight membrane.

Request for Exemption No.

Page 4 of 14 Figure 2-1: LIP Domain i'

a O

i I

f t 't t '+

a t 'a

'+

t. 't

'i

+

+

t Based on the higher water levels from the reconstituted analyses, new methods are necessary to protect the site against flooding from external flood hazard events.

lncorporated barriers, as defined in Regulatory Guide 11A2, "Flood Protection for Nuclear Power Plants," are being used. Because buildings have already been constructed, non-safety protection features, including the concrete portion of non-safety related building walls, newly installed flood walls or curbs (either concrete or aluminum),

flood panels, and non-safety related building roofs (including roof drains and scuppers),

are used for mitigation of the reconstituted design basis external flood hazard events.

These protection features were not designed, fabricated, erected, or initially tested consistent with SSCs that provide a safety-related function. Having been purchased and installed as non-safety related, these features do not fall under the scope of quality assurance program (OAP) controls. Although aspects of the QAP can be retroactively enforced, the full pedigree of these SSCs cannot be established. Therefore, an exemption to the requirements of 10 CFR 50, Appendix B, is required.

This exemption request is specific to non-safety related protection features that are required to prevent floodwaters from entering safety-related buildings. Where postulated water levels exceed the first-floor grade of a building, flood protection is necessary to meet the requirements of incorporated barriers. Energy Harbor Nuclear Corp. is requesting an exemption to credit existing (newly installed) non-safety related protection features, including permanent (passive) and temporary (deployable), as flood

Request for Exemption No. 1 Page 5 of 14 barriers that perform a mitigative function to act as an environmental interface for safety-related SSCs during external flood hazard events.

3.0 PROPOSED EXEMPTION Based on the reconstituted analyses, WSEs resulting from external flood hazard events are above the nominal flood elevation of doors leading into plant structures at various locations. Plant buildings are now directly subject to static and dynamic forces resulting from accumulated flood waters. The resulting static and dynamic loadings are evaluated at safety-related buildings (structures), and non-safety related buildings (structures) that function as an environmental interface to determine the flood protection requirements. A non-safety building (structure) is considered an environmental interface to a safety-related building if external floodwaters would enter the safety-related building when the existence of all or part of the non-safety related building was removed. Non-safety related buildings are now a required protection feature to prevent floodwaters from entering safety-related buildings. Other non-safety related protection features, permanent (passive) and temporary (deployable), are required to mitigate the reconstituted design basis external flood hazard events and include flood walls, flood panels, stop logs, ramps, and non-safety related building roofs (including roof drains and scuppers).

The new flood hazard protection scheme for PNPP credits the non-safety related building exteriors themselves or credits a wall or curb around the perimeter of the applicable buildings. The protective wall or curb is constructed to an appropriate height and with sufficient margin to prevent flood water intrusion. Gaps are present only where temporary flood panels protect personnel or equipment openings (doors). The protective features were analyzed and determined to be capable of withstanding the static and dynamic loads resulting from the analyzed flood conditions.

With respect to WSEs above the nominal flood elevation of doors leading into plant structures, Energy Harbor Harbor Corp. is installing flood barriers at the applicable doorways to provide a seal to prevent water from entering building structures. The barriers consist of installation of the steel end channels of the barrier system, which are attached to the building structure and allow for the installation of aluminum stop logs with seals to provide the flood protection. The stop logs are stored in accordance with site procedures.

A total of 89 door locations are identified as points of interest (POI) with each assigned an identification number (ID No.). The calculation results for these POIs are presented in Table 3-1. The maximum water depth is observed at the Unit 2 Heater Bay (Door 2HB 306, POI ID No. 61) followed by the Service Building (Door 0SB 107, POI ID No.

39) as shown in Table 3-1. A margin depth of negative value means maximum WSE is greater than door floor elevation. A margin depth value of zero and greater means the resulting water surface elevation is less than the door floor elevation, which means the door of interest is not flooded. The flooding durations at the doors are presented in Table 3-2.

Request for Exemption No. 1 Page 6 of 14 The stop logs used as flood barriers provide protection from flood waters up to approximately 2 ft in height. This is adequate to prevent water intrusion into the doors with the maximum water depth (Door 2HB 306 and Door 0SB 107). The aluminum flood barriers are capable of withstanding the postulated flood waters, including dynamic loading from impact velocity and impact from postulated flood-borne debris.

With respect to flood waters being present against the exterior of plant structures, Energy Harbor Nuclear Corp. is installing a flood barrier wall (either concrete or aluminum) as overall protection against water entry into plant buildings. The concrete walls are nominally 8 inches thick and 2 ft high at the building environment interface.

The aluminum walls are comprised of modular segments, prefabricated using 1/4 inch aluminum plate, that are nominally 1.5 ft high and secured to the structure using concrete anchors. The segments are provided with 1/2 inch gaskets that form the seal at the panel to panel interface, as well as at the panel to concrete interface. Table 3-3 provides a listing of the buildings using either concrete or aluminum flood walls.

The actual forces experienced by plant structures during a LIP event, the controlling flood event for the site, are far less than other design basis GDC 2 forces (specifically tornado wind loads). This is applicable to safety-related buildings, which are designed for such loads. This is also reiterated in Regulatory Guide 1.102 in the context of forces resulting from temporary ponding. For non-safety related structures, the relatively low flood water heights and low velocities are analytically demonstrated to be within the capacity of the non-safety related building exteriors (where credited) or the protection features provided at the environmental interface.

Monitoring plans are to be developed or revised to perform periodic inspections of building exteriors and protection features to ensure overall integrity. In this way, gross floodwater ingress is prevented. Although not expected, any incidental inleakage would be easily accommodated by building floor drain systems or by the internal storage capacity of the structures. Should inleakage exceed these physical margins, the resulting inleakage into safety-related areas can be addressed via building sumps.

Collectively, although no inleakage is expected, the defense-in-depth approach outlined above ensures overall plant safety.

No other forces act concurrently on the non-safety related structures during the LIP event. Forces such as those induced by seismic loads or tornado winds need not be postulated simultaneously.

These non-safety related plant components are designed to withstand the static and dynamic loads expected during the LIP event. Preventive maintenance is to be established to ensure that these protection methods maintain their integrity. Therefore, taking credit for non-safety protection features, including the concrete portion of non-safety building walls, flood walls or curbs (concrete or aluminum), flood panels (permanent or deployable), and non-safety related building roofs (including roof drains and scuppers) as an environmental interface for safety-related structures to mitigate the effects of the design basis external flood hazard events is reasonable.

Request for Exemption No. 1 Page 7 of 14 In the case of these flood protection features, full application of 10 CFR 50, Appendix B, requirements to categorize them as safety-related would not provide an appreciable change in assurance they would perform as intended and would be cost prohibitive. As described above, the features have been demonstrated to withstand applicable static and dynamic loads. The features are at a height to prevent floodwaters from entering safety-related buildings, ensuring safety-related SSCs perform their safety functions.

Because these non-safety related features do not fall under specific QAP controls, an exemption in accordance with 10 CFR 50.12 is applicable. The proposed exemption is from 10 CFR 50, Appendix B, requirements to allow PNPP to credit existing (newly installed) non-safety related protection features, including permanent (passive) and temporary (deployable), as providing adequate assurance or confidence that safety-related SSCs will satisfactorily perform their safety functions during external flood hazard events.

4.0 JUSTIFICATION OF EXEMPTION 10 CFR 50.12, Specific exemptions, states that the NRC may grant exemptions from the requirements of the regulations of this part provided three conditions are met. They are:

(1) The exemptions are authorized by law, (2) The exemptions will not present an undue risk to the public health and safety, and (3) The exemptions are consistent with the common defense and security.

Energy Harbor Nuclear Corp. has evaluated the requested exemption for PNPP against the criteria of 10 CFR 50.12 and determined the criteria are satisfied as described below.

1. This exemption is authorized by law.

The requested exemption is authorized by law in that no law precludes the activities covered by this exemption request. Granting of the request does not result in a violation of the Atomic Energy Act of 1954, as amended.

2. This exemption will not present an undue risk to the health and safety of the public.

The underlying purpose of 10 CFR 50, Appendix A, requiring structures, systems, and components (SSCs) important to safety to be designed, fabricated, erected, and tested to quality standards commensurate with the importance of the safety functions to be performed, is to ensure the SSCs will satisfactorily perform their safety functions, and thereby protect the health and safety of the public. The underlying purpose of 10 CFR 50, Appendix B, is to ensure quality assurance requirements are applied to these SSCs to provide adequate confidence that the SSCs will perform satisfactorily in service. In

Request for Exemption No. 1 Page 8 of 14 the case of the reconstituted design basis external flood hazard events, use of non-safety related protection features to help prevent intrusion of water into these SSCs is necessary. The flood protection features have been demonstrated to withstand applicable static and dynamic loads and are at a height to prevent floodwaters from entering safety-related buildings, ensuring safety-related SSCs perform their safety functions. The underlying purpose of 10 CFR 50, Appendix B, is still achieved.

The requested exemption does not create any new accident precursors. The probability and consequences of postulated accidents are not increased, and an acceptable level of external flood hazard protection is maintained.

Therefore, there is no undue risk to public health and safety.

3. The exemption is consistent with the common defense and security.

The requested exemption credits existing (newly installed) non-safety related protection features, including permanent (passive) and temporary (deployable), as flood barriers that perform a mitigative function to act as an environmental interface for SSCs during external flood hazard events. This exemption has no relation to security issues. The common defense and security are not impacted by this exemption.

In addition to the three conditions discussed above, 10 CFR 50.12(a)(2) states that the NRC will not consider granting an exemption unless special circumstances are present.

Under 10 CFR 50.12(a)(2)(ii), special circumstances are present whenever the application of the regulation in the particular circumstances would not serve the underlying purpose of the rule or is not necessary to achieve the underlying purpose of the rule. The non-safety related flood protection features have been demonstrated to withstand applicable static and dynamic loads and are at a height to prevent floodwaters from entering safety-related buildings, ensuring safety-related SSCs perform their safety functions. To categorize these features as safety-related would not provide an appreciable change in assurance of SSC performance. Therefore, the underlying purpose of the rule is achieved with the non-safety related flood protection features.

5.0 ENVIRONMENTAL CONSIDERATION

Energy Harbor Nuclear Corp. is requesting an exemption from certain requirements of 10 CFR 50, Appendix B, for the Perry Nuclear Power Plant, Unit No. 1 (PNPP).

Specifically, Energy Harbor Nuclear Corp. is requesting to credit existing (newly installed) non-safety related protection features, including permanent (passive) and temporary (deployable), as flood barriers that perform a mitigative function to act as an environmental interface for safety-related structures, systems, and components (SSCs) during external flood hazard events. The following information is provided in support of an environmental assessment and a finding of no significant impact for the proposed exemption.

Request for Exemption No. 1 Page 9 of 14 Energy Harbor Nuclear Corp. has determined that the exemption involves no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite; that there is no significant increase in individual or cumulative public or occupational radiation exposure; that there is no construction impact; and there is no significant increase in the potential for or consequences from a radiological accident. Accordingly, the proposed exemption meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(25). Pursuant to 10 CFR 51.22(b),

no environmental impact statement or environmental assessment need be prepared in connection with the issuance of this proposed exemption request.

Request for Exemption No. 1 Page 10 of 14 Table 3 LIP Results at Door Locations for Front-Loaded LIP Temporal Distribution Max Flow 2Margin Depth Above =

1Door Ground Door Elev -

POI Elev. Elevation Max WSE Max WSE ID Door Grid ft-PNPP ft-PNPP No. Building No. No. Datum ft. ft-NAVD88 Datum (ft.)

Unit 1 (U1) Auxiliary 1 Building 1AX 406 74326 620.504 0.899 620.06 620.99 -0.49 2 U1 Auxiliary Building 1AX 404 74642 620.465 0.703 620.06 620.99 -0.53 3 U1 Auxiliary Building 1AX 403 75274 620.456 1.370 620.08 621.01 -0.55 4 U1 Auxiliary Building 1AX 407 68496 620.614 1.253 620.32 621.25 -0.64 5 U1 Auxiliary Building 1AX 405 68499 620.506 0.884 620.32 621.25 -0.75 6 U1 Turbine Building 1TB 307 59754 620.500 0.890 620.32 621.25 -0.75 7 U1 Turbine Building 1TB 308 58385 620.500 0.054 619.23 620.16 0.34 8 U1 Turbine Building 1TB 306 61482 624.500 0.399 619.00 619.93 4.57 9 U1 Turbine Building 1TB 316 71777 620.392 0.713 620.03 620.96 -0.57 10 U1 Heater Bay 1HB 306 64199 620.410 0.030 619.16 620.09 0.32 11 U1 Heater Bay 1HB 310 68856 620.385 0.625 619.88 620.81 -0.43 12 U1 Heater Bay 1HB 314 67868 620.870 0.057 619.75 620.68 0.19 13 U1 Heater Bay 1HB 311 67870 620.416 0.408 619.72 620.65 -0.23 14 U1 Heater Bay 1HB 309 70808 620.610 0.593 620.02 620.95 -0.34 15 U1 Heater Bay 1HB 308 71778 620.261 0.900 620.03 620.96 -0.70 16 U1 Turbine Power Complex 1TP 306 73051 620.420 0.909 620.05 620.98 -0.56 17 U1 Turbine Power Complex 1TP 303 67841 620.516 0.824 620.32 621.25 -0.74 18 U1 Off Gas Building 1OG 303 63836 620.467 1.000 620.32 621.25 -0.78 19 U1 Off Gas Building 1OG 302 63499 620.431 0.970 620.32 621.25 -0.82 20 U1 Off Gas Building 1OG 304 61123 620.467 0.830 620.32 621.25 -0.78 21 U1 Water Treatment Building 0WT 101 55241 620.401 0.824 619.87 620.80 -0.40 22 Water Treatment Building 0WT 103 55936 620.399 1.102 620.23 621.16 -0.76 23 Water Treatment Building 0WT 102 58372 620.429 1.371 620.32 621.25 -0.82 24 Diesel Generator Building 0DG 106 64479 620.512 0.908 620.36 621.29 -0.78 25 Diesel Generator Building 0DG 105 64146 620.547 0.771 620.34 621.27 -0.72 26 Diesel Generator Building 0DG 104 63813 620.680 0.585 620.34 621.27 -0.59 27 Diesel Generator Building 0DG 103 63478 620.650 0.611 620.33 621.26 -0.61 28 Diesel Generator Building 0DG 102 63143 620.503 0.769 620.33 621.26 -0.76 29 Diesel Generator Building 0DG 101 62808 620.487 0.836 620.33 621.26 -0.77 30 Radwaste Building 0RW 422 62470 620.459 0.916 620.33 621.26 -0.80 31 Radwaste Building 0RW 407 62132 620.393 0.964 620.32 621.25 -0.86 32 Radwaste Building 0RW 411 61457 620.435 0.981 620.32 621.25 -0.82 33 Radwaste Building 0RW 401 62819 620.473 1.290 620.32 621.25 -0.78 34 Intermediate Building 0IB 315 76859 620.594 1.363 620.08 621.01 -0.42

Request for Exemption No. 1 Page 11 of 14 Table 3 LIP Results at Door Locations for Front-Loaded LIP Temporal Distribution Max Flow 2Margin Depth Above =

1Door Ground Door Elev -

POI Elev. Elevation Max WSE Max WSE ID Door Grid ft-PNPP ft-PNPP No. Building No. No. Datum ft. ft-NAVD88 Datum (ft.)

35 Intermediate Building 0IB 316 78439 620.570 1.053 620.18 621.11 -0.54 36 Intermediate Building 0IB 317 78120 620.416 1.002 620.20 621.13 -0.72 37 Service Building 0SB 113 71398 620.430 1.365 620.40 621.33 -0.90 38 Service Building 0SB 114 71721 620.434 1.235 620.40 621.33 -0.90 39 Service Building 0SB 107 70749 620.466 1.395 620.40 621.33 -0.87 40 Service Building 0SB 104 70098 620.436 1.355 620.40 621.33 -0.90 41 Service Building 0SB 105 68131 620.493 1.334 620.40 621.33 -0.84 42 Service Building 0SB 108 66808 620.477 1.266 620.41 621.34 -0.86 43 Service Building 0SB 103 66476 620.482 1.236 620.41 621.34 -0.85 44 Service Building 0SB 102 64810 620.461 1.242 620.39 621.32 -0.86 45 Service Building 0SB 101 64477 620.467 1.034 620.36 621.29 -0.83 Unit 2 (U2) Auxiliary 46 Building 2AX 403 78748 620.419 0.928 620.30 621.23 -0.81 47 U2 Auxiliary Building 2AX 404 78745 620.415 0.950 620.37 621.30 -0.89 48 U2 Auxiliary Building 2AX 406 79062 620.439 0.973 620.41 621.34 -0.90 49 U2 Auxiliary Building 2AX 405 73000 620.546 1.154 620.40 621.33 -0.79 50 U2 Auxiliary Building 2AX 407 72041 620.469 1.304 620.40 621.33 -0.87 51 U2 Turbine Building 2TB-E 77146 620.499 1.017 620.47 621.40 -0.90 52 U2 Turbine Building 2TB-D 77780 620.426 1.127 620.47 621.40 -0.97 53 U2 Turbine Building 2TB 316 80003 620.440 1.324 620.60 621.53 -1.09 54 U2 Turbine Building 2TB-C 80320 620.311 1.253 620.61 621.54 -1.23 55 U2 Turbine Building 2TB 306 70722 624.500 1.204 620.48 621.41 3.09 56 U2 Turbine Building 2TB-B 66782 620.373 1.393 620.46 621.39 -1.02 57 U2 Turbine Building 2TB 308 67445 620.318 1.301 620.47 621.40 -1.08 58 U2 Turbine Building 2TB-A 65462 620.325 1.184 620.40 621.33 -1.01 59 U2 Turbine Building 2TB 307 66130 620.311 1.143 620.40 621.33 -1.02 60 U2 Heater Bay 2HB 303 78716 620.476 1.361 620.61 621.54 -1.06 61 U2 Heater Bay 2HB 306 74889 620.430 1.625 620.49 621.42 -0.99 62 U2 Turbine Power Complex 2TP 303 72999 620.377 1.135 620.40 621.33 -0.96 63 U2 Off Gas Building 2OG 304 66467 620.461 1.253 620.40 621.33 -0.87 64 U2 Off Gas Building 2OG 302 68454 620.422 1.285 620.40 621.33 -0.91 65 U2 Off Gas Building 2OG 303 68782 620.477 1.285 620.40 621.33 -0.86 66 Service Water Pump SW 102 58081 620.000 0.155 618.56 619.49 0.51 67 Service Water Pump SW 105 61183 620.000 0.275 618.73 619.66 0.34 68 Service Water Pump SW 103 57039 620.000 0.277 618.37 619.30 0.70 69 Service Water Pump SW 104 56698 620.000 0.367 618.51 619.44 0.56 70 Service Water Pump SW 101 61190 620.000 0.512 618.77 619.70 0.30

Request for Exemption No. 1 Page 12 of 14 Table 3 LIP Results at Door Locations for Front-Loaded LIP Temporal Distribution Max Flow 2Margin Depth Above =

1Door Ground Door Elev -

POI Elev. Elevation Max WSE Max WSE ID Door Grid ft-PNPP ft-PNPP No. Building No. No. Datum ft. ft-NAVD88 Datum (ft.)

Emergency Service Water 71 Pump House (ESWPH) EW 202 65576 619.500 0.462 618.92 619.85 -0.35 72 ESWPH EW 201 64916 619.500 0.458 619.01 619.94 -0.44 73 ESWPH EW East 66916 619.500 0.607 619.06 619.99 -0.49 74 Circulating Water Pump U2 CW 101 96539 621.500 0.502 620.70 621.63 -0.13 75 Circulating Water Pump U2 CW 102 96901 621.500 0.902 620.70 621.63 -0.13 76 Circulating Water Pump U2 CW 103 97636 626.500 0.084 620.93 621.86 4.64 77 Circulating Water Pump U2 CW 104 95463 626.500 0.035 624.39 625.32 1.18 78 Circulating Water Pump U2 CW South 97994 624.500 0.492 620.70 621.63 2.87 79 Circulating Water Pump U1 CW 101 83930 621.500 0.224 620.04 620.97 0.53 80 Circulating Water Pump U1 CW 102 83929 621.500 0.124 620.04 620.97 0.53 81 Circulating Water Pump U1 CW 103 85532 626.500 0.094 620.91 621.84 4.66 82 Circulating Water Pump U1 CW 104 84900 626.500 0.030 624.55 625.48 1.02 83 Circulating Water Pump U1 CW South 84887 624.500 0.138 620.09 621.02 3.48 Waste Abatement/Low-Level Radwaste Storage 84 (LLRWSPF) RWSP 101 71498 623.000 0.030 620.90 621.83 1.17 85 LLRWSPF RWSP 102 71499 623.000 0.038 620.84 621.77 1.23 86 LLRWSPF RWSP 103 71177 623.000 0.031 620.69 621.62 1.38 87 LLRWSPF RWSP 104 73116 623.000 0.600 622.21 623.14 -0.14 88 LLRWSPF RWSP 107 75019 623.000 1.322 619.97 620.90 2.10 89 LLRWSPF RWSP 108 74383 623.000 0.030 621.41 622.34 0.66 1

Door elevations are not the same as the FLO-2D PRO (new methodology used in reconstitution of LIP) grid cell elevations as door elevation values were determined via point surveys (different from the 2012 survey) and different from the adjacent grid cell elevations. The margin calculations are based on door elevation and depth, which is the depth per the FLO-2D PRO grid cell.

2 Some of the reported values above are rounded to two decimal places for presentation in this table. Values generated as output by FLO-2D PRO contain more precise values than presented in this table. Margin computations are performed using the more precise values (unrounded). As such, the results provided in the margin column of this table, while more accurate, may vary +/-0.01 ft. from that computed using the presented values.

Table 3 Flood Duration above Door Elevation for Front-Loaded LIP Temporal Distribution 1Flooding Maximum Water Surface Door Duration POI ID No. Building Elevation No.

Minutes ft-PNPP Datum 1 U1 Auxiliary Building 1AX 406 132 620.99 2 U1 Auxiliary Building 1AX 404 144 620.99 3 U1 Auxiliary Building 1AX 403 156 621.01 4 U1 Auxiliary Building 1AX 407 168 621.25 5 U1 Auxiliary Building 1AX 405 216 621.25 6 U1 Turbine Building 1TB 307 198 621.25 7 U1 Turbine Building 1TB 308 0 620.16 8 U1 Turbine Building 1TB 306 0 619.93 9 U1 Turbine Building 1TB 316 132 620.96

Request for Exemption No. 1 Page 13 of 14 Table 3 Flood Duration above Door Elevation for Front-Loaded LIP Temporal Distribution 1Flooding Maximum Water Surface Door Duration POI ID No. Building Elevation No.

Minutes ft-PNPP Datum 10 U1 Heater Bay 1HB 306 0 620.09 11 U1 Heater Bay 1HB 310 114 620.81 12 U1 Heater Bay 1HB 314 0 620.68 13 U1 Heater Bay 1HB 311 78 620.65 14 U1 Heater Bay 1HB 309 90 620.95 15 U1 Heater Bay 1HB 308 150 620.96 16 U1 Turbine Power Complex 1TP 306 150 620.98 17 U1 Turbine Power Complex 1TP 303 198 621.25 18 U1 Off Gas Building 1OG 303 204 621.25 19 U1 Off Gas Building 1OG 302 210 621.25 20 U1 Off Gas Building 1OG 304 234 621.25 21 U1 Water Treatment Building 0WT 101 144 620.80 22 U1 Water Treatment Building 0WT 103 216 621.16 23 U1 Water Treatment Building 0WT 102 210 621.25 24 Diesel Generator Building 0DG 106 276 621.29 25 Diesel Generator Building 0DG 105 210 621.27 26 Diesel Generator Building 0DG 104 3600 621.27 27 Diesel Generator Building 0DG 103 3600 621.26 28 Diesel Generator Building 0DG 102 3600 621.26 29 Diesel Generator Building 0DG 101 204 621.26 30 Radwaste Building 0RW 422 210 621.26 31 Radwaste Building 0RW 407 222 621.25 32 Radwaste Building 0RW 411 210 621.25 33 Radwaste Building 0RW 401 204 621.25 34 Intermediate Building 0IB 315 114 621.01 35 Intermediate Building 0IB 316 138 621.11 36 Intermediate Building 0IB 317 210 621.13 37 Service Building 0SB 113 330 621.33 38 Service Building 0SB 114 330 621.33 39 Service Building 0SB 107 318 621.33 40 Service Building 0SB 104 330 621.33 41 Service Building 0SB 105 300 621.33 42 Service Building 0SB 108 312 621.34 43 Service Building 0SB 103 306 621.34 44 Service Building 0SB 102 318 621.32 45 Service Building 0SB 101 312 621.29 46 U2 Auxiliary Building 2AX 403 372 621.23 47 U2 Auxiliary Building 2AX 404 3600 621.30 48 U2 Auxiliary Building 2AX 406 2904 621.34 49 U2 Auxiliary Building 2AX 405 270 621.33 50 U2 Auxiliary Building 2AX 407 312 621.33 51 U2 Turbine Building 2TB-E 3600 621.40 52 U2 Turbine Building 2TB-D 3600 621.40 53 U2 Turbine Building 2TB 316 774 621.53 54 U2 Turbine Building 2TB-C 3600 621.54 55 U2 Turbine Building 2TB 306 0 621.41 56 U2 Turbine Building 2TB-B 3222 621.39 57 U2 Turbine Building 2TB 308 3600 621.40 58 U2 Turbine Building 2TB-A 378 621.33

Request for Exemption No. 1 Page 14 of 14 Table 3 Flood Duration above Door Elevation for Front-Loaded LIP Temporal Distribution 1Flooding Maximum Water Surface Door Duration POI ID No. Building Elevation No.

Minutes ft-PNPP Datum 59 U2 Turbine Building 2TB 307 366 621.33 60 U2 Heater Bay 2HB 303 456 621.54 61 U2 Heater Bay 2HB 306 1524 621.42 62 U2 Turbine Power Complex 2TP 303 342 621.33 63 U2 Off Gas Building 2OG 304 318 621.33 64 U2 Off Gas Building 2OG 302 336 621.33 65 U2 Off Gas Building 2OG 303 312 621.33 66 Service Water Pump SW 102 0 619.49 67 Service Water Pump SW 105 0 619.66 68 Service Water Pump SW 103 0 619.30 69 Service Water Pump SW 104 0 619.44 70 Service Water Pump SW 101 0 619.70 71 ESWPH EW 202 396 619.85 72 ESWPH EW 201 3600 619.94 73 ESWPH EW East 2910 619.99 74 Circulating Water Pump U2 CW 101 42 621.63 75 Circulating Water Pump U2 CW 102 42 621.63 76 Circulating Water Pump U2 CW 103 0 621.86 77 Circulating Water Pump U2 CW 104 0 625.32 78 Circulating Water Pump U2 CW South 0 621.63 79 Circulating Water Pump U1 CW 101 0 620.97 80 Circulating Water Pump U1 CW 102 0 620.97 81 Circulating Water Pump U1 CW 103 0 621.84 82 Circulating Water Pump U1 CW 104 0 625.48 83 Circulating Water Pump U1 CW South 0 621.02 84 LLRWSPF RWSP 101 0 621.83 85 LLRWSPF RWSP 102 0 621.77 86 LLRWSPF RWSP 103 0 621.62 87 LLRWSPF RWSP 104 228 623.14 88 LLRWSPF RWSP 107 0 620.90 89 LLRWSPF RWSP 108 0 622.34 1

Flooded duration of 3600 minutes corresponds to LIP simulation duration. POI IDs showing this duration represent local topographic low points without drainage features, which retain water depths at the end of the simulation.

Table 3 Buildings with Concrete or Aluminum Flood Walls Building U1 Heater Bay U1 Turbine Building U1 Turbine Power Complex Service Building Radwaste Building Water Treatment Auxiliary Boiler U2 Heater Bay U2 Turbine Building U2 Turbine Power Complex