AEP-NRC-2016-24, Response to Fifth Request for Additional Information Regarding the License Amendment Request to Adopt TSTF-490 and Implement Alternative Source Term

Response to Fifth Request for Additional Information Regarding the License Amendment Request to Adopt TSTF-490 and Implement Alternative Source Term

ML16069A151
Person / Time
Site:	Cook
Issue date:	02/19/2016
From:	Lies Q Indiana Michigan Power Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
AEP-NRC-2016-24, TAC MF5184, TAC MF5185
Download: ML16069A151 (15)

Text

£NINA Indiana Michigan Power MICHIGAN Co ula ln POWER rdmnM 90 A un/it of Amierican Electric PowerAPco February 19, 2016 AEP-NRC-201 6-24 10 CFR 50.90 Docket Nos. 50-315 50-316 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Donald C. Cook Nuclear Plant Unit 1 and Unit 2 Response to Fifth Request for Additional Information Regarding the License Amendment Request to Adopt TSTF-490 and Implement Alternative Source Term

References:

1. Letter from J. P. Gebbie, Indiana Michigan Power Company (I&M), to U. S. Nuclear Regulatory Commission (NRC), "Donald C. Cook Nuclear Plant, Units 1 and 2 License Amendment Request to Adopt TSTF-490, Revision 0, 'Deletion of E Bar Definition and Revision to Reactor Coolant System Specific Activity Technical Specification' and Implement Full-Scope Alternative Source Term," dated November 14, 2014, Agencywide Documents Access and Management System (ADAMS) Accession No. ML14324A209.

2. Letter from J. P. Gebbie, I&M, to NRC, "Donald C. Cook Nuclear Plant Unit 1 and Unit 2 Supplemental Information for the License Amendment Request to Adopt TSTF-490, Revision 0, "Deletion of E Bar Definition and Revision to Reactor Coolant System Specific Activity Technical Specification" and Implement Full-Scope Alternative Source Term," dated February 12, 2015, ADAMS Accession No. ML15050A247.

3. E-mail capture from A. W. Dietrich, NRC, to H. L. Kish, l&M, "D.C. Cook Units 1 and 2 - MET RAI Concerning L.AR to Adopt TSTF-490 and Implement Full-Scope AST (TAC NOS.

MF5184 and MF5185)," dated December 17, 2015, ADAMS Accession No. ML15352A003.

4. Letter from NRC to J. P. Gebbie, I&M, "Donald C. Cook Nuclear Plant, Units 1 and 2 -

Regulatory Audit Report Regarding License Amendment Request to Adopt Technical Specifications Task Force-490, Rev.0, and Implement Alternative Source Term (CAC NOS.

MF5184 AND MF5185)," dated January 20, 2016, ADAMS Accession No. ML16007A180.

This letter provides Indiana Michigan Power Company's (l&M), licensee for Donald C. Cook Nuclear Plant (CNP) Units 1 and 2, response to the fifth Request for Additional Information (RAI) by the U. S. Nuclear Regulatory Commission (NRC) regarding a license amendment request (LAR) to adopt Technical Specification Task Force (TSTF)-490 and implement Alternative Source Term (AST).

U. S. Nuclear Regulatory Commission AEP-NRC-201 6-24 Page 2 By Reference 1, as supplemented by Reference 2, I&M submitted a request to amend the Technical Specifications to CNP Units 1 and 2 Renewed Facility Operating Licenses DPR-58 and DPR-74.

l&M proposes to adopt TSTF-490, Revision 0, and implement full scope AST radiological analysis methodology. By Reference 3, the NRC transmitted an RAI from the Meteorology and Oceanography Team of the Hydrology and Meteorology Branch regarding the [AR submitted by I&M in Reference 1. This RAI contains five separate items for which additional information is requested. To clarify the items addressed in this RAI, telephone conferences were held with the NRC Project Manager and NRC technical reviewers. Enclosure 1 to this letter provides an affirmation statement. Enclosure 2 to this letter provides I&M's response to the RAI contained in Reference 3.

During preparation of the response to this RAI, errors were discovered in the meteorological data tables provided in Reference 1. As a result of correcting those errors, changes have been made to the atmospheric dispersion factor (X/Q) calculations that were described in Section 2.3 of Enclosure 9 to Reference 1. Updated data files related to the new calculations are being provided on a compact disc as an attachment to Enclosure 2. By Reference 4, the NRC identified supplemental information to be provided in support of the technical review. Because of the errors identified above, some of the documents requested by the NRC in Reference 4 require revision and will be provided by May 6, 2016.

Copies of this letter are being transmitted to the Michigan Public Service Commission and Michigan Department of Environmental Quality, in accordance with the requirements of 10 CFR 50.91.

There are no new regulatory commitments made in this letter. Should you have any questions, please contact Mr. Michael K. Scarpello, Regulatory Affairs Manager, at (269) 466-2649.

Sincerely, F"~

__Shane Lies Site Vice President TLC/mll

Enclosures:

1. Affirmation

2. Response to Fifth Request for Additional Information Regarding the License Amendment Request to Adopt TSTF-490 and Implement Alternative Source Term c: R. J. Ancona, MPSC, w/o attachment to Enclosure 2 A. W. Dietrich, NRC, Washington, D.C.

MDEQ - RMD/RPS, w/o attachment to Enclosure 2 NRC Resident Inspector, w/o attachment to Enclosure 2 C. D. Pederson, NRC, Region III, w/o attachment to Enclosure 2 A. J. Williamson, AEP Ft. Wayne, wfo enclosures

Enclosure 1 to AEP-NRC-2016-24 AFFIRMATION I, Q. Shane Lies, being duly sworn, state that I am the Site Vice President of Indiana Michigan Power Company (I&M), that I am authorized to sign and fife this request with the U. S. Nuclear Regulatory Commission on behalf of I&M, and that the statements made and the matters set forth herein pertaining to I&M are true and correct to the best of my knowledge, information, and belief.

Indiana Michigan Power Company Q. Shne Lies Site Vice President SWORN TO AND SUBSCRIBED BEFORE ME THIS _1B DAY OF *'~*, ,*-\ 2016 NotaryDANIELLE BURGOYNE Public, State of Michigan County of Berrien My Cornmiss ion Expires 04-04-2Oi Acting in the Couni f: **^0.

My Commission Expires Q-"A -t'%'.-\ *.. *K

Enclosure 2 to AEP-NRC-2016-24 Response to Fifth Request for Additional Information Regarding the License Amendment Request to Adopt TSTF-490 and Implement Alternative Source Term By letter dated November 14, 2014, (Agencywide Documents Access and Management System (ADAMS) Accession No. ML14324A209), as supplemented by letter dated February 12, 2015, (ADAMS Accession No. ML15050A247), Indiana Michigan Power Company (I&M), the licensee for the Donald C. Cook Nuclear Plant (CNP), Units 1 and 2, submitted a license amendment request.

The proposed amendment consists of adoption of Technical Specifications Task Force-490, Revision 0, and implementation of a full scope alternative source term (AST) radiological analysis methodology.

The U. S. Nuclear Regulatory Commission (NRC) staff in the Meteorology and Oceanography Team of the Hydrology and Meteorology Branch (MET) of the Office of Nuclear Reactor Regulation is currently reviewing the submittal, as supplemented, and has determined that additional information is needed in order to complete the review. The requests for additional information (RAI)s and I&M's responses are provided below.

During preparation of the responses to this RAI, errors were discovered in the meteorological data tables. As a result of correcting those errors, changes have been made to the atmospheric dispersion factor (X/Q) calculations that were described in Section 2.3 of Enclosure 9 to Reference 1. Updated files related to the new calculations are being provided on a compact disc (CD) as an attachment to this enclosure.

RAI-MET-1 The Donald C. Cook Nuclear Plant (CNP) Alternate Source Term (AST) Radiological Analyses Technical Report was provided as Enclosure 9 to the license amendment request (LAR) dated November 14, 2014, (Agencywide Documents Access and Management System (ADAMS)

Accession No. ML1I4324A 209). Section 2.3.3, "MeteorologicalData," of Enclosure 9, states that meteorological data were collected from a primary, backup, and shoreline tower. The LAR states that data from the shoreline tower most accurately represents the meteorological conditions on site based on its vicinity to CNP. However, the shoreline tower only records data at a height of 10 meters (in). As a result, a hybrid meteorological data set is created using the 10 m data from the shoreline tower for the lower level measurements, and the 60 m data from the primary tower for the upper level measurements. The stability classes are calculated based on the temperature difference between the 10 m and 60 m levels on the primary tower. The years of data provided are based on the 5 most recent years that have valid data for both the primary and shoreline towers. Five years' worth of meteorological data is used, which meets the guidance set forth in Regulatory Position 3.1 of Regulatory Guide 1.194 (ADAMS Accession No. ML031530505).

The LAR does not state the distance between the towers. Moreover, in the absence of the 60 m level data from the shoreline tower, it is not clear what data were used, if any, to replace the bad or missing data from the primary tower for the upper level measurements, or whether there were sufficient good data from the shoreline tower to meet the >90% recovery criterion.

to AEP-NRC-2016-24 Pg Page 2 a) Indicate the locations of weather towers and their distances from CNP.

b) Indicate the sources of data, if any, which were used to replace the bad or missing data for the 60 m level.

I&M Response to RAI-MET-I:

a) The locations of the weather towers are depicted in Figure 2.2-23 of the D.C. Cook Nuclear Plant Updated Final Safety Analysis Report (UFSAR) (Reference 2). Figure 2.2-23 is reproduced in this response as Figure 1.

The shoreline tower is located approximately 500 feet NNE of CNP along the shore of Lake Michigan. The primary tower is located approximately 1.3 miles ENE of both CNP and the shoreline tower (see Figure 1).

Figure 1: Reproduction of Figure 2.2-23, "Monitoring Site Locations", of the D.C. Cook UFSAR to AEP-NRC-2016-24 Pg Page 3 b) Section 2.3.3 of Enclosure 9 to Reference 1 states that the selected years (2002, 2004, 2005, 2007, and 2010) were chosen because they were the most recent years with "high quality data."

The phrase "full periods of high quality data available" was not intended to imply that 100% of the hours from a given year were used in the meteorological data set. Rather, it was meant to indicate that the data set from each of the specified years had more than 90% of the hours used as input to the analyses. Therefore, no data was used to replace any bad or missing data because there was sufficient 10 m shoreline, 10 m primary, and 60 m primary tower data to meet the >90% recovery rate outlined in Section C5 of Reference 3. The recovery rate percentages are presented in Table 1.

Table 1 is being provided as a replacement to Table 2.3-1 of Enclosure 9 to Reference 1. The table reflects updated and additional data recovery rates resulting from resolution of issues regarding use of meteorological tower data. Tables 2.3-2 through 2.3-4 and Table 2.3-7, previously provided in Section 2.3 of Enclosure 9 of Reference 1, remain unchanged as a result of the updated calculations. However, Tables 2.3-5 and 2.3-6 from Enclosure 9 of Reference 1, which provide maximum, or bounding, offsite atmospheric dispersion factors and release receptor pair applications, respectively, are dependent upon the outcome of the dose consequence analyses. For that reason, changes to those tables may be required after completion of revisions to the dose consequence analyses. Therefore, updated versions of Tables 2.3-5 and 2.3-6 from Enclosure 9 of Reference 1 will be provided, if necessary, when supplemental information regarding the updated dose consequence analyses is provided at a later date.

Table 1: Meteorological Data Recovery Rate Parameter 2002 2004 2005 2007 2010 WidSed1%Piay 9. 99. 99. 99. 99.

Wind Speed 60 m Primary 99.9 99.4 99.8 94.3 89.5 Wind Speed 10 m Shore 100 96 99.8 99.9 99.2 Wind Direction 10 m Primary 99.9 99.4 99.8 99.6 99.5 Wind Direction 60 m Primary 99.9 99.4 99.8 99.6 91.8 Wind Direction 10 m Shore 100 96 99.8 100 98.6 Delta Temperature 60-10 m 9. 93 9. 94 9.

Primary ______ ______

to AEP-NRC-2016-24 Pg Page 4 RAI-MET-2 Section 2.3.3, "MeteorologicalData," of Enclosure 9 of the LAR, states that meteorologicaldata from a 5-year data set (2002, 2004, 2005, 2007, and 2010) were selected, since they were the 5 most recent years with full periods of high quality data available. The meteorological data was converted from the raw format into the proper formatting required to create the meteorological data files for use with ARCON96 and PA VAN.

The 2004 data in the Excel spreadsheet provided shows that for the time period from 1/1/2004 at 00:00 until 1/3/2004 at 01:00 (i.e., longer than 2 days), all data were bad, both at the primary and shoreline towers, and possibly at the backup tower. Although 55 bad data points out of 8,786 hourly data points is only 0. 63 percent of the data collected in 2004, the probability of such bad data occurring simultaneously at two stations at the same time is extremely low unless there is a common cause failure.

The data for the year 2004 was manipulated within a spreadsheet for use with ARCON96 and PA VAN, but nothing is mentioned about the source of any data that replaced bad or missing data.

There are no hours in the . MET data files that were provided for ARCON96 input that indicate calm wind speeds. There are many hours in the .MET data files (284 in lower, 142 in. upper) that have wind speeds that exceed the maximum wind speed classification used in the PA VAN input file.

a) Explain the reason for the missing or bad data for the first 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> in the 2004 Excel file.

b) Since the LAR states that 2004 is one of the years in which data were available for the full period (i.e., the whole year), please explain which data, if any, were used to substitute for these 2 days, and the method, if any, that was used to extrapolate these data.

c) Explain how this period was represented in the joint frequency distribution (JFD) for PA VAN.

d) Explain the missing calm wind speed data and the excessive high wind speed data in the supplied . MET files I&M Response to RAI-MET-2:

a) The missing data for the first 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> of 2004 was due to technical issues related to the new installation of the Meteorological Information and Dose Assessment System (MIDAS) at CNP. The MIDAS application processes were locked and not responding to input. The technical issues were entered into, and addressed through, the CNP corrective action program. The 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> of missing data is acceptable for the atmospheric dispersion analysis because a 90% recovery rate is still achieved after the bad and missing data is discarded (see Table 1 in the response to RAI-MET-1).

b) Section 2.3.3 of Enclosure 9 to Reference 1 states that the selected years (2002, 2004, 2005, 2007, and 2010) were chosen because they were the most recent years with "high quality data." No data was substituted for the two days of missing or bad data in 2004 (or to AEP-NRC-2016-24 Pg Page 5 any other missing or bad data in the other specified years) because a 90% recovery rate is still achieved after the bad and missing data is discarded, as shown in Table 1 in the response to RAI-MET-1.

c) This period, as well as all bad and missing data, is not represented in the joint frequency distribution since a 90% recovery rate, as outlined in Reference 3, is still achieved after the bad and missing data is discarded.

d) Input errors were identified in PAVAN while developing the response to this RAI, and as a result, the atmospheric dispersion factor calculations were revised. Specifically, values that should have been flagged as "bad" data were incorrectly input as "calm" wind speeds.

Information is provided below regarding how wind speeds are defined in the new calculations.

Calm Wind Speeds The calm wind speed threshold of the CNP meteorological instrumentation is 0.22 meters per second (m/s) (0.5 miles per hour (mph)). As part of the updated calculations discussed previously, wind speeds of 0.5 mph and lower are designated as "calm" wind speeds in PAVAN.

This threshold differs slightly from the previous input threshold in the original submittal, which considered only wind speeds less than 0.5 mph as "calm." As such, there are 462 total hours within the five years of data used (2002, 2004, 2005, 2007, and 2010) that experience "calm" wind speeds in the updated information for the primary tower 10 m data set. There are zero hours of calm wind speed in the five year shoreline tower 10 m data set. This is not unexpected, considering the tower is located immediately adjacent to the Lake Michigan shoreline.

Regarding the .MET files used as ARCON96 input, "calm" wind speeds are not defined or treated differently than the rest of the hourly data because the wind speed values (upper and lower) are simply input as part of the hourly data.

For the joint frequency distribution data used in PAVAN, the total number of calm hours for each stability class was applied to the PAVAN input using the "Distribute Calm array into first wind-speed category" option. The 462 hours0.00535 days <br />0.128 hours <br />7.638889e-4 weeks <br />1.75791e-4 months <br /> of calm hours for the primary tower cases are distributed across the Pasquill stability classes from A through G, respectively, as follows: 13, 3, 0, 13, 54, 86, 293.

High Wind Speeds The maximum wind speed classification in the PAVAN files is 14 m/s. The maximum wind speed (for the 10 m shoreline and 10 m primary tower readings) from all five years of data is less than 20 m/s. There are 2,037 hours4.282407e-4 days <br />0.0103 hours <br />6.117725e-5 weeks <br />1.40785e-5 months <br /> from the 10 m shoreline tower data that have a wind speed between 10 m/s and 20 m/s. All of these hours are included in the highest wind speed bin in PAVAN, with 284 of the hours (less than 0.7% of the total hours in the entire data set) between 14 and 20 m/s. There are only 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> from the 10 m primary tower data that have a wind speed between 10 m/s and 20 m/s. These hours are included in the highest wind speed bin in PAVAN, and neither of the hours exceeds 14 m/s. The response to RAI-MET-3 contains additional information regarding selection of the 14 m/s wind speed category limit.

to AEP-NRC-2016-24 Pg Page 6 RAI -MET-3 The JFD table was synthesized from hourly readings of wind speed, wind direction and atmospheric stability collected at the shoreline and primary towers. Wind speed was segmented into 14 ranges from 0 to 14 meters per second (mis). Although it was clear that wind speeds of less than 0.22 mis were treated as calm, and went into the first wind-speed bin, it was not clear from the LAR how wind speeds greaterthan 14 mis were treated.

Although high wind speeds are not usually associated with high relative air concentration (X/Q),

all assumptions about how the JFD table was created should be clearly stated.

a) State whether data for wind speeds greaterthan 14 mis were discarded, or became part of the JFD table.

l&M Response to RAI-MET-3:

a) Wind speeds greater than 14 m/s are included as part of the JFD table in the highest wind speed bin (10 m/s - 14 m/s). The basis for determining the highest wind speed bin limit is described below.

The highest wind speed category from the joint frequency distribution encompasses wind speeds ranging from 10 m/s to 20 m/s. For any wind speed category, PAVAN sets the speed to the average of the upper and lower bound for ground level releases as described in Section 4.3 of Reference 4. The average wind speed above 10 m/s for all hours of meteorological data was calculated to be approximately 12 m/s for the 10 m shoreline tower data. Since the highest wind speed category entered in the PAVAN cases is 10 m/s to 14 m/s, a wind speed of 12 m/s will be applied in the PAVAN computations when the wind speed exceeds 10 m/s.

RAI-MET-4 Although all of the . MET data that the licensee used was supplied to the NRC staff, not all of the ARGON96 results were replicated. In the LAR, Enclosure 9, Table 2.3-3, there are results for 16 different ARCON96 input datasets. Of the 16, the staff was able to replicate the results for 14 of them. The only parts of the input data that were changed were the exclusion area boundary (EAB) and low population zone (LPZ) boundary data, per Table 2. 3-4.

The two release points that were not replicated have the word "diffuse" in the descriptions.

Some other portion of the input data was changed that is not reflected in the five columns of input data numbers that are provided for the 16 input datasets in Table 2.3-2. Also, there are blanks in scenario 0 of Table 2. 3-3. The ARGON96 output for this case did provide results for the blank columns appearingin this row.

a) Explain the reasoning behind leaving the blanks in scenario 0 of Table 2.3-3.

b) Provide the . RSF input data file for the case represented by scenarios M and N, and at least one other case (e.g. scenario D).

to AEP-NRC-2016-24 Pg Page 7 c) Explain the assumptions made to approximate the diffuse sources in scenarios M and N of Table 2. 3-3.

I&M Response to RAI-MET-4:

a) Table 2.3-3 of Enclosure 9 to Reference 1 shows blanks for some of the scenario 0 X/Qs because these values represent a release from the Steam Jet Air Ejector (SJAE). During a steam generator tube rupture (SGTR) event, a release from the SJAE is modeled to occur prior to the plant trip. Offsite power is assumed to be lost concurrent with the limiting SGTR event. Therefore, the RCS is cooled using the power operated relief valves (PORVs) post-trip. The worst-case radiological release scenario is through the PORVs as they are the largest release path. As a result, the SGTR scenario release location shifts from the SJAE to the PORV/mnain steam safety valve following a plant trip. Since there are no releases from the SJAE beyond the 0-2 hour period in the SGTR dose analysis, X/Q values are not provided for the remaining time periods.

b) The requested .RSF input data files are being provided on a CD as an attachment to this enclosure.

c) Scenarios M and N are considered diffuse area releases from the Unit 2 containment surface. These scenarios are included as an approach for considering a source reasonably well distributed within the containment. The building surface is modeled as a vertical planar area (or diffuse area) source. The diffuse source is modeled in ARCON96 via two initial diffusion coefficients. The coefficients are calculated based on the guidance found in Section 3.2.4.4 of Reference 5. The area source width is the containment diameter of approximately 122 feet (ft), resulting in an initial diffusion coefficient Oy of 6.2 m. The area source height, based conservatively on the elevation difference between the top of the containment building and the top of the tallest building connected to the containment surface, is approximately 89.5 ft, resulting in an initial diffusion coefficient 0 zo of 4.55 m.

RAI-M ET-5 The atmospheric dispersion calculations completed for this LAR are based on data collected from both the primary meteorological tower, located approximately one mile east of CNP, and the shoreline meteorological tower, located slightly northwest of CNP on the Lake Michigan shoreline. The licensee uses wind speed and direction from the 10 m location of the shoreline tower, but relies on temperature measurements at the 10 and 60 m levels of the primary tower for defining atmospheric stability. The licensee states that data from the shoreline tower are more representative of the plant for wind speed and direction. For on-shore winds, which are the main direction of concern for impact to the control room (CR), EAB and LPZ, it appears that there is a considerable difference in wind speed, direction, and temperature measurements from the 10 m level of the two towers. Therefore, the use of wind speed and direction from the shoreline tower, and atmospheric stability from the primary tower, may not be accurate or conservative. This could especially be true for a site where sharp contrasts in surface friction and air/water temperature can exist that could lead to the development of a coastal Thermal Internal Boundary Layer.

to AEP-NRC-2016-24 Pg Page 8 a) Justify the use of combined meteorological data from the two towers in the atmospheric dispersion calculations. This justification should particularly address the validity of combining data for off-site dose evaluations. If it is shown that X/Q at the CR, EAB and LPZ could be higher for some scenarios using only primary tower data for the atmospheric dispersion calculations, justify why the use of the shoreline tower is acceptable. Alternatively, develop anotherdata set for dispersion calculations.

I&M Response to RAI-MET-5:

a) Section 2.2.3.2 of Reference 2 provides information regarding the representative nature of the shoreline tower 10 m (elevation) wind speed data. In particular, this information provides assurance that the use of this data is most representative of the meteorological conditions of areas immediately around the facility. As the EAB and LPZ regions utilized in the dose consequence analyses may extend beyond this representative area, an assessment of the applicability of the use of data from both the primary tower and shoreline towers has been performed.

The data from the shoreline tower is considered to most accurately represent the meteorological conditions on-site based on its vicinity to the plant. However, the shoreline tower only records data at a height of 10 m. As a result, for on-site analyses, a meteorological data set is created using the 10 m shoreline data for the lower level measurements and the 60 m primary tower data for the upper, level measurements. The stability classes are calculated based on the temperature difference between the 10 m and 60 m levels on the primary tower. The use of stability classes based on primary tower data is considered to be conservative because the primary tower likely experiences more stable conditions due to its location further inland.

Using topographical maps, meteorological expertise was applied to determine which dose sectors within the EAB and LPZ are most represented by either the shoreline tower or primary tower. Figures 2 and 3 below (EAB and LPZ, respectively), provided to I&M by a contracted meteorologist, show the dose sectors which would be best represented by data from each tower. The sectors shaded in yellow in both Figures 2 and 3 have been determined to be best represented by the shoreline tower meteorology when considering a release from the plant to a receptor at the boundary. The primary tower has been determined to be most representative of the remaining, non-shaded sectors.

Figures 2 and 3 use the standard 16 wind direction sectors (N-NNW) to break down the areas that are represented by the shoreline and primary towers. A sector is considered to be the 22.5 degree region centered on the direction from the plant to the EAB or LPZ boundary. The EAB and LPZ boundaries are represented by a dashed red line (Figure 2) and dashed blue line (Figure 3), respectively.

Along the Lake Michigan shoreline on the CNP site, a rugged dune structure is present which builds up moving inland. The dune structure forms a natural ridge line east of the plant that runs north-south along the shoreline. Noting the orientation of the dune structure in relation to the plant, meteorological evaluation has determined that the EAB sectors from the SSE sector to the NNE sector (clockwise) are best represented by the shoreline tower.

The EAB sectors from the NE sector to the SE sector (clockwise) have been determined to to AEP-NRC-2016-24 Page 9 be best represented by the primary tower. The shaded sectors, those sectors for which the shoreline tower is considered to be most representative, fall within the shoreline side of the ridgeline.

Likewise, the LPZ sectors from the SSW sector to the N sector (clockwise) have been determined to be best represented by the shoreline tower. The LPZ sectors from the NNE sector to the S sector (clockwise) have been determined to be best represented by the primary tower. The shaded sectors, those sectors for which the shoreline tower is considered to be most representative, fall within the shoreline side of the ridgeline.

Noting the above discussion and the information presented, in Figures 2 and 3, it has been determined that a mixed meteorological data set should be utilized in calculating atmospheric dispersion factors for use in the preparation of offsite dose consequence analyses. This approach has been incorporated into revised atmospheric dispersion factor calculations, with the associated files are being provided on a CD, included as an attachment to this enclosure.

to AEP-NRC-201 6-24Pae1 Page 10 Figure 2: Topographical Map of EAB with Dose Sector Overlay to AEP-NRC-201 6-24Pae1 Page 11 Figure 3: Topographical Map of LPZ with Dose Sector Overlay to AEP-NRC-2016-24Pae1 Page 12 REFERENCES

1. AEP-NRC-2014-65, "License Amendment Request to Adopt TSTF-490, Revision 0, "Deletion of E Bar Definition and Revision to Reactor Coolant System Specific Activity Technical Specification" and Implement Full-Scope Alternative Source Term," November 14, 2014, ADAMS Accession No. ML14324A209.

2. D.C. Cook Nuclear Plant Updated Final Safety Analysis Report, Revision 26.

3. USNRC Regulatory Guide 1.23, Rev. 1, "Meteorological Monitoring Programs for Nuclear Power Plants," March 2007.

4. NUREG/CR-2858, "PAVAN: An Atmospheric Dispersion Program for Evaluating Design Basis Accidental Releases of Radioactive Materials from Nuclear Power Stations," November 1982.

5. USNRC Regulatory Guide 1.194, "Atmospheric Relative Concentrations for Control Room Radiological Habitability Assessments at Nuclear Power Plants," June 2003.

ATTACHMENT

1. D. C. Cook AST Accident Analyses Meteorological Data. (The enclosed compact disc contains the revised meteorological data used to develop the on-site and off-site atmospheric dispersion (X/Q) factors)