ML082260401

Transmittal of Supplemental Response to Request for Additional Information License Amendment Request - Application of Alternative Source Term

ML082260401
Person / Time
Site:	Peach Bottom
Issue date:	08/07/2008
From:	Cowan P Exelon Generation Co, Exelon Nuclear
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML082260401 (13)

Text

Exelon Nuclear www.exeloncorp.com Exelno 200 Exelon Way Nuclear Kennett Square, PA 19348 10 CFR 50.90 August 7, 2008 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Peach Bottom Atomic Power Station, Units 2 and 3 Renewed Facility Operating License Nos. DPR-44 and DPR-56 Docket Nos. 50-277 and 50-278

Subject:

Supplemental Response to Request for Additional Information Concerning License Amendment Request - Application of Alternative Source Term

References:

1. Letter from Pamela B. Cowan, Exelon Generation Company, LLC, to U. S. Nuclear Regulatory Commission, "License Amendment Request - Application of Alternative Source Term," dated July 13, 2007

2. U. S. Nuclear Regulatory Commission e-mail dated July 18, 2008, draft Request for Additional Information (RAI), Peach Bottom Atomic Power Station, Units 2 and 3, License Amendment Request (LAR), Alternative Source Term Application (five questions)

3. U. S. Nuclear Regulatory Commission updated e-mail dated July 25, 2008, draft Request for Additional Information (RAI), Peach Bottom Atomic P,.wer Station, Units 2 and 3, License Amendment Request (LAR), Alternative Source Term Application (one question)

4. Letter from Pamela B. Cowan, Exelon Generation Company, LLC, to U. S. Nuclear Regulatory Commission, "Response to Request for Additional Information Concerning License Amendment Request - Application of Alternative Source Term," dated July 29, 2008 In Reference 1, Exelon Generation Company, LLC (Exelon) submitted an application requesting a change to the Technical Specifications (TS), Appendix A, of Renewed Facility Operating License Nos. DPR-44 and DPR-56 for Peach Bottom Atomic Power Station (PBAPS), Units 2 and 3, respectively. The proposed change was requested to support the application of Alternative Source Term (AST) methodology at PBAPS, Units 2 and 3.

In References 2 and 3, the U. S. Nuclear Regulatory Commission (NRC) issued draft requests for additional information (RAIs) concerning the PBAPS License Amendment Request (LAR).

The NRC identified six questions in the draft RAIs in which additional information was requested concerning meteorological and dose consequence aspects related to AST. The draft questions were identified as AADB RAI 20 through AADB RAI 25.

.ADC/

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U.S. Nuclear Regulatory Commission License Amendment Request Alternative Source Term Docket Nos. DPR-44 and DPR-56 August 7, 2008 Page 2 In Reference 4, Exelon responded to four of the six draft questions identified by the NRC.

Specifically, information was provided to RAI questions AADB 20, AADB 21, AADB 22, and AADB 24. The response indicated that Exelon would submit a supplemental response to address RAI questions AADB 23 and AADB 25, since these questions focused on further evaluation of X/Q values and the need to submit revised calculations. The attachments to this letter contain the complete responses to AADB 23 and AADB 25. The revised calculations also provide documentation and clarification for those responses discussed in the Reference 4 letter.

Exelon has concluded that the information provided in this response does not impact the conclusions of the: 1) Technical Analysis, 2) No Significant Hazards Consideration under the standards set forth in 10 CFR 50.92(c), or 3) Environmental Consideration as provided in the original submittal (Reference 1).

There are no regulatory commitments contained in this letter. If you have any further questions or require additional information, please contact Richard Gropp at 610-765-5557.

I declare under penalty of perjury that the foregoing is true and correct. Executed on the 7th day of August 2008.

Respectfully, Pamela B. 6owan Director - Licensing and Regulatory Affairs Exelon Generation Company, LLC : Supplemental Response to Request for Additional Information RAI Questions AADB 23 and AADB 25 : Revised Calculation PM-1055, "Calculationof Alternative Source Term (AST)

Onsite and Offsite X/Q Values," Revision 1 : Revised Calculation PM-1077, "Post-LOCA EAB, LPZ and CR Doses Using Alternative Source Term (AST)," Revision 1 : Revised Calculation PM-1059, "Re-analysis of Fuel HandlingAccident (FHA)

Using Alternative Source Terms," Revision 3 : Revised Calculation PM-1057, "Re-analysisof Control Rod Drop Accident (CRDA) Using Alternative Source Terms," Revision 2 : Additional PAVAN Input and Output Data Files cc: Regional Administrator - NRC Region I Attachment 1 only NRC Senior Resident Inspector - PBAPS NRC Project Manager, NRR - PBAPS Director, Bureau of Radiation Protection - Pennsylvania Department of Environmental Protection S. T. Gray, State of Maryland

ATTACHMENT 1 Peach Bottom Atomic Power Station Units 2 and 3 Docket Nos. 50-277 and 50-278 License Amendment Request Supplc smental Response to Request for Additional Information Alternative Source Term (AST)

Response to RAI Questions AADB 23 and AADB 25 Alternative Source Term Supplemental RAI Response Page 1 of 10

Background

By letter dated July 13, 2007, Exelon Generation Company, LLC (Exelon) submitted an application requesting a change to the Technical Specifications (TS), Appendix A, of Renewed Facility Operating License Nos. DPR-44 and DPR-56 for Peach Bottom Atomic Power Station (PBAPS), Units 2 and 3, respectively. The proposed change was requested to support the application of Alternative Source Term (AST) methodology at PBAPS, Units 2 and 3.

By electronic mail (e-mail) on July 18, 2008 and an updated e-mail on July 25, 2008, the U. S.

Nuclear Regulatory Commission (NRC) transmitted six draft Request for Additional Information (RAI) questions pertaining to the meteorological and dose consequence issues related to AST.

The questions were identified as AADB RAI 20 through AADB RAI 25. By letter dated July 29, 2008, Exelon provided information in response to four of the six RAI questions (AADB 20, AADB 21, AADB 22, and AADB 24). The response to the remaining two questions would be provided in a supplemental response, since these questions focused on further evaluation of X/Q values and the need to submit revised calculations. The calculations requiring revision as a result of the changes in X/Q values are included in Attachments 2 through 5 of this submittal as listed below.

• Attachment 2 - Revised Calculation PM-1 055, "Calculationof Alternative Source Term (AST) Onsite and Offsite X/Q Values," Revision 1 a Attachment 3 - Revised Calculation PM-1 077, "Post-LOCA EAB, LPZand CR Doses Using Alternative Source Term (AST)," Revision 1

• Attachment 4 - Revised Calculation PM-1059, "Re-analysisof Fuel HandlingAccident (FHA) Using Alternative Source Terms," Revision 3

• Attachment 5 - Revised Calculation PM-1 057, "Re-analysisof Control Rod Drop Accident (CRDA) Using Alternative Source Terms," Revision 2 In addition, Attachment 6 provides additional PAVAN input and output data files that were used in support of revising Calculation PM-1 055 (Attachment 2). These files use the 11 wind speed categories per Regulatory Guide 1.23, Revision 1.

Tables 1 through 4 below provide a summary of the changes made to the attached calculations.

Table 5 provides a summary comparing the dose values between the revisions in the calculations. Table 6 provides a summary of the revised X/Q (sec/m 3) values used.

Exelon agreed to provide a supplemental response to the remaining two RAI questions (AADB 23 and AADB 25) and submit the revised calculations by August 7, 2008. AADB 23 and AADB 25 have been restated below followed by Exelon's response. RAI Questions AADB 20, AADB 21, AADB 22, and AADB 24 are not discussed since the responses to these questions were the subject of the July 29, 2008 letter. The revised calculations also provide documentation and clarification for those responses discussed in the July 29, 2008 letter.

Alternative Source Term Supplemental RAI Response Page 2 of 10 NRC Question 4 (AADB RAI 23)

The response to NRC Question 12 (AADB RAI 12) of the licensee's May 23, 2008, letter stated that the reactorbuilding stack tops are at 305 feet (ft) mean sea level (msl) and the meteorological Tower 2 grade elevation is 367 ft msL NRC staff agrees that the elevation of the reactorbuilding stack tops is nearer the height of the meteorological Tower 2 grade elevation than the grade elevation of the River Tower or Tower 1A which are approximately 116 feet msL However, the reactorbuilding stack tops are about 60 feet below the Tower 2 grade elevation and therefore appearto be below the top of at leastpart of the bluff upon which Tower 2 is located. In addition, otherpostulated release locations such as the personnel access door, railway bay door,and groundhatches are at or near the plant structures on the river valley shoreline and appearto be at a height more nearly that of River Tower and Tower 1A.

Therefore, please provide justification that these postulated releases could not be impacted by localized air flow patterns in the valley. Further,please provide justification that use of the Tower 2 meteorological data in the PA VAN computer calculationsprovides the limiting atmospheric dispersion factors (x/Q values) for the low populationzone dose assessment.

Response

Topography near the Peach Bottom Site is complex. The facility is located on the shore of the Susquehanna River adjacent to a bluff. Effluent releases are postulated from multiple locations, including from short stacks and openings on top of facility structures, locations at or near ground-level at the facility, and from the 152 meter off-gas stack on the bluff.

Meteorological data from all three towers were utilized to generate atmospheric dispersion factors (X/Q values), namely Tower 2 on the bluff, Tower 1 A near the shore in the vicinity of the Peach Bottom facility structures, and from the River Tower based in the Susquehanna River. In most cases, two (and in some cases three) sets of data were used to generate X/Q values for a single release/receptor pair. In every such case, the limiting (highest) X/Q values were selected for use in the dose assessment.

Meteorological Tower 2 is located on a bluff approximately 2600 feet (approximately 800 meters) from the Reactor Building stacks. Tower 2 has a grade elevation of 367 feet above mean sea level (msl), or 251 feet (76.5 meters) above station grade. Tower 1A is located at 119 feet msl approximately 1300 feet southeast of the Reactor Building stacks, and is also topographically situated very similarly to the Station (i.e., at the Susquehanna River's edge and immediately adjacent to the steeply higher terrain in the westerly, southwesterly, and southerly directions). The River Tower is approximately 1200 meters north-northeast of the Station. The River Tower measures winds at 45 feet above the river level, but stability class based on the, delta temperature parameter, in accordance with NRC Regulatory Guide 1.23, is not monitored on the River Tower. However, Tower 1A, prior to its decommissioning in 1993, monitored the temperature difference between elevation 89 feet and elevation 34 feet. Tower lA is ideally situated adjacent to and based at essentially the same grade elevation as the Station so as to best represent the local dispersion conditions to which the Reactor Building stack releases are subject for over-river trajectories out to the EAB.

Alternative Source Term Supplemental RAI Response Page 3 of 10 While meteorological tower data measured on Towers 1A and the River Tower would not generally be representative of conditions at the LPZ, for purposes of conservatism additional LPZ X/Q values for the Units 2 and 3 Reactor Building stacks were calculated based on the meteorological data from Tower 1A located in the Valley immediately adjacent to the Peach Bottom Facility. Furthermore, these LPZ X/Q values are utilized to conservatively represent the Reactor Building Personnel Access Doors, Railway Bay Doors, Roof Scuttle, and Ground-Level Hatch for the Fuel Handling Accident analysis, and for a conservatively-assumed ground level release for the Control Rod Drop Accident analysis. Conservatively, corresponding EAB X/Q values for these accidents based on the meteorological data from Tower 1A are utilized as well.

For each time-averaging period, the use by PAVAN of the 11-bin joint frequency distributions based on Regulatory Guide 1.23, Revision 1, results in somewhat higher X/Q values for the EAB and LPZ, and for the other modeled distance values in support of the Off-Gas Stack to Control Room X/Q. These 11-bin joint frequency distributions were used in the development of the X/Qs for this response as well as for use in the dose calculations (Attachments 3 through 5).

NRC Question 6 (AADB RAI 25)

Updated Table 4.3-1 (LOCA Parameters)of the Enclosure to the May23, 2008, Peach Bottom response to a request for additionalinformation provides a set of control room atmospheric dispersion factors (X/Q values) for containmentand ESF leakage releases via an off-gas stack release. Sheet 5 of Attachment A to the Enclosureprovides a second set of X/Q values for releases from the off-gas stack to the control room intake that were calculated in accordance with Section 3.2.2 of Regulatory Guide 1.194. The two sets of values appearto be for a single release scenario using two different methodologies. If this is the case, please identify which set you propose to establish as the new licensing basis control room X/Q values for postulated releases from the off-gas stack.

Response

The X/Q values used for the new licensing basis are shown in Table 6 below.

Alternative Source Term Supplemental RAI Response Page 4 of 10 Table 1 Calculation Chang~es Made to PM-1055 "Calculation of Alternative Source Term (AST) Onsite and Ofsite X1Q Values"

SUMMARY

Calculation PM-1055 is revised to determine more conservative ground level )(I values for the EAB and LPZ, developed using the meteorological wind and stability data from Tower 1lA. The EAB and LPZ XIQs were also recalculated using PAVAN with the finer wind speed categories described in Regulatory Guide 1.23, Revision 1. There are no changes made to the Control Room X/Q values except to those for Off-Gas Stack releases as a result of the PAVAN finer wind speed categories results.

Item Specific Changes Made to: le Asu Revse Reason for Change 1 Cover Sheet Revision 0 Revision 1 Administrative change replaces the Revision 0 cover sheet.

2 Owners Acceptance Checklist Revision 0 Revision 1 Administrative change replaces the Revision 0 checklist.

3 Table of Contents Revision 0 Revision 1 Editorial change reflects updated page numbers and attachments.

4 Section 1.0, "Purpose/Objective" Revision 0 Revision 1 Updated to reflect changes made in Revision 1.

Provides additional X/Q values that support responses to Questions Section 4.0, "Additional PAVAN AADB RAI 12, 13, and 23. It also provides justifications for the use 5 Analysis Of Control Room, EAB, Revision 0 Revision 1 of the meteorological data used in the development of various X/Q and LPZ" values. Section 4 Tables are also updated to reflect new calculated X/Q values.

6 Section 5.0, "Summary and Revision 0 Revision 1 Updates the summary of the worst-case X/Q results.

Conclusions" (Table 5-1)

Editorial change that adds RG 1.194 (as the superceded DG- 1111) 7 S o and RG 1.23 Rev. 1 (regarding additional wind speed categories used for the EAB, LPZ, and the Off-Gas stack to Control Room intake analyses).

This attachment incorporates the corrected sheet 4 previously provided in response to NRC RAI AADB 16.

9 Attachment "J" Revision 0 Revision 1 Duplicated pages identified in Question AADB RAI 17 from the July 23, 2008, letter to NRC were removed.

These attachments include the finer wind speed category Joint 10 Attachments "K"and "L" Revision 0 Revision 1 Frequency Distribution results and the PAVAN input and output summaries for the new cases for the EAB, LPZ, and the Off-Gas stack to Control Room intake X/Qs in response to NRC RAIs.

Alternative Source Term Supplemental RAI Response Page 5 of 10 Table 2 Calculation Chang~es Made to PM-1077 Post-LOCA EAB, LPZ, and CR Doses Usinq Alternative Source Term (AST),

SUMMARY

Calculation PM-1077 is revised to reflect doses due to more conservative X/Q values for the EAB and LPZ that were developed in calculation PM-i 055, Revision 1, "Calculation of Alternative Source Term (AST) Onsite and Offsite X/Q Values." A description of the Maximum Hypothetical Accident (MHA) is also included as a response to Question AADB RAI 20.

Item Specific Changes Made to: As As ResnfrCag Submitted Revised Reasn for Change 1 Cover Sheet Revision 0 Revision 1 Administrative change replaces the Revision 0 cover sheet.

2 Owners Acceptance Checklist Revision 0 Revision 1 Administrative change replaces the Revision 0 checklist.

3 Table of Contents Revision 0 Revision 1 Editorial change reflects updated page numbers and attachments.

Section 2.3.3, "Recirculation Line Revised to better describe the MHA. Added a tracking number to 4 Rupture Vs. Main Steam Line Revision 0 Revision 1 ensure it is not deleted in future revisions in response to Question Rupture" AADB RAI 22.

Reflect changes to RADTRAD run numbers based on new X/Q Editorial changes (throughout) Revision 0 Revision 1 values.

Sections 5.6.7, 5.7.1, 5.7.2, 5,7.4, and 5.7.5 revised to indicate the 6 Section 5.0, " Design Inputs" Revision 0 Revision 1 new X/Q values used in theanalysis, consistent with the releases modeled in Figure 2 of the calculation.

7 Section 8.1, "Results Summary" Revision 0 Revision 1 Updated to reflect doses based on new X/Q values.

8 Section 9.0, "References" Revision 0 Revision 1 References Rvso 1 and Revision updated n addition Asrevised X/Q Calculation PM-1055, diinoto reflect of RAls.

9 Appendix "A" Revision 0 Revision 1 Includes the sensitivity study regarding question AADB RAI 22.

Contains RADTRAD outputs for all runs made for the DBA case as well as for the AEB 98-03 sensitivity study. Additional supporting RADTRAD runs were included for completeness of the CR shine dose model.

kýA Alternative Source Term Supplemental RAI Response Page 6 of 10

.Table 5 Calculation Chani~s -Made to PM-1059 "Re-analysis of Fuel Handling Accident (EHA) Using Alternative Source Terms'

SUMMARY

Calculation PM-I 059 is revised to reflect new more conservative X/Q values for the EAB and LPZ that were developed in calculation PM-1055. Revision 1, "Calculation of Alternative Source Term (AST) Onsit e and Offsite X/Q Values."

Item Specific Changes Made to: As As Resnio Change Submitted Revised Ranifor change 1 Cover Sheet Revision 2 Revision 3 Administrative change replaces the Revision 0 cover sheet.

2 Owners Acceptance Checklist Revision 2 Revision 3 Administrative change replaces the Revision 0 checklist.

3 Table of Contents Revision 2 Revision 3 Editorial change reflects updated page numbers and attachments.

4 Section 1.0, "Purpose/Objective" Revision 2 Revision 3 Updated to describe Revision 3 calculation changes.

5 Table 2 Revision 2 Revision 3 Updated to reflect new EAB and LPZ X/Qs 6 Section 5.0, "References" Revision 2 Revision 3 Updated references list for X/Q Calculation PM-1055, Rev. 1 7 Section 6.0, "Calculations" Revision 2 Revision 3 Changes to reflect updated EAB and LPZ X/Qs Updated to reflect new EAB and LPZ doses based on revised X/Q values, and the resulting unacceptability of only the EAB dose 8 Section 7.0, Summary and Revision 2 Revision 3 resulting for Case 2 (the zero decay time case, illustrating the acceptability with respect to Control Room doses of even this

- improbable scenario).

Section 8.0, "Owners Acceptance Revision 2 Revision 3 Administrative change replaces the Revision 0 checklist.

Checklist" Contains new RADTRAD runs using revised EAB and LPZ X/Qs 10 Attachment "B" Revision 2 Revision 3 (and a minor correction in the Control Room X/Q values used for Cases 3 and 4 from 1.93E-03 to the proper value of 1.90E-03).

11 Attachment "G", Figure 3-1 Revision 2 Revision 3 Corrected the note describing the elevation of the roof scuttle to the proper value of 294 feet msl.

Alternative Source Term Supplemental RAI Response Page 7 of 10 Table 4 Calculation Chang~es Made to PM-1057 "Re-analysis of Cotntrol Rod Drop Accidenti (CRDA) Ushnig Alternative Source Terms"

SUMMARY

~Calculation PM- 1057 is revised to: reflect new more conservative X/Q values for the EAB and LPZ that were developed in calculation PM-1055, Revision 1, "Calculation of Alternative Source Te rm AST) Onsi e and Off site X/Q Values."

As.. As Item Specific ChangesRMade to: Submitted Revised eason for Change 1 Cover Sheet Revision 1 Revision 2 Administrative change replaces the Revision 1 cover sheet.

2 Owners Acceptance Checklist Revision 1 Revision 2 Administrative change replaces the Revision 1 checklist.

3 Table of Contents Revision 1 Revision 2 Editorial changes reflect updated page numbers and attachments.

4 Section 1.0, "Purpose/Objective" Revision 1 Revision 2 Updated to describe Revision 2 calculation changes.

5 Section 4.1, "X/Q Calculations Revision 1 Revision 2 Updated to reflect new EAB and LPZ X/Qs (Meteorology)"

6 Section 5.0, "References" Revision 1 Revision 2 Updated references list for X/Q Calculation PM-1055, Rev. 1 and FHA Calculation PM-1059, Rev. 3.

7 Section 6.2, "Dose Calculations" Revision 1 Revision 2 Changes to reflect updated EAB and LPZ X/Qs 8 Section 7.0, "Summary and Revision 1 Revision 2 Updated to reflect new EAB & LPZ doses based on revised X/Q Conclusions" values.

9 Attachment "B" Revision 1 Revision 2 New RADTRAD runs using revised EAB and LPZ X/Qs.

Alternative Source Term Supplemental RAI Response Page 8 of 10 Table 5 Dose Results Summary Dose Rem TIEDE Rem *TIEDE Accident Receptor Prior to X/Q After, X/Q Location Revision Revision:

CR 4.66 4.69 1 LOCA EAB 6.65 10.7 (PM-1077)

LPZ 7.13 8.99 3.85 3.792 FHA 3 CR (PM-1059) EAB 1.16 2.49 24-Hour Decay LPZ 0.132 0.377 FHA 3 CR 4.56 4.56 (PM-1059) EAB 0.714 1.53 84-Hour Decay LPZ 0.081 0.232 CR 0.302 0.302 CRDA EAB 0.065 0.086 (PM-1057)

LPZ 0.012 0.032 Notes:

1. CR dose for the LOCA increased due to the change in X/Q from the elevated Off-Gas (main) stack.

2. CR dose for the FHA decreased due to the minor correction in X/Q (1.90E-03 vs. 1.93E-03).

3. FHA 24-hour decay results support Technical Specifications (TS) changes that include the definition of Recently Irradiated Fuel, and relaxation of TS for secondary containment integrity during fuel handling operations with as little as 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after shutdown. FHA with a minimum of 84 hours9.722222e-4 days <br />0.0233 hours <br />1.388889e-4 weeks <br />3.1962e-5 months <br /> decay is included as the bounding case that would allow limiting ground-level hatches (H15 through H24) to the west of the Reactor/Radwaste Buildings to be opened, with a minimum decay time of 84 hours9.722222e-4 days <br />0.0233 hours <br />1.388889e-4 weeks <br />3.1962e-5 months <br /> after shutdown and MCREV operable via automatic initiation.

Attachment 1 Alternative Source Term Supplemental RAI Response Page 9 of 10 Table 6 3)

X/O (sec/m Results Summary (from PM-1055 Rev. 1 Table 5-1),

Meteorological Database Utilized with Justification, and Dose Calculation Application Bases Controlling Receptor Release Point o0-0.5 0-2 hour 2-8 hour 18-24 hourl 1-4 day 4-30 day Meteorological Justification for Used in Dose hour Tower Database Usage Calculation Utilized Tower 2 is the only representative database Off-Gas Stack 3.31E-06 1.OOE-15 1.OOE-15 1.64E-08 4.54E-09 Tower2 (See Calculation PM-1077, Rev. 1 PM-1055, Rev 1, Sections 2.2.3 and 2.2.4)

The higher of the X/Qs predicted by Tower 2 (0-2 hour) representative Towers PM- 1077, Rev. 1, Unit 2 Reactor Building Stack 1.18E-03 9.08E-04 4.14E-04 2.90E-04 2.26E-04 Tower lA (all other 2 and IAdatabases PM-1057, Rev. 2, periods) were selected (See PM-1059, Rev 3 Calculation PM-1055, Rev 1, Sections 2.2.3 and 2.2.4)

Control The higher of the Room Intake X/Qs predicted by representative Towers PM-1077, Rev. 1, Unit 3 Reactor Building Stack 1.18E-03 8.91E-04 4.00E-04 2.51E-04 1.98E-04 Tower2 2and IA databases PM-1057, Rev. 2, (Unit 2 is limiting) were selected (See PM-1059, Rev 3 Calculation PM-1055, Rev 1, Sections 2.2.3 and 2.2.4)

Tower 1A is the most representative and Fuel Handling Accident Reactor Building Personnel (Various) 0-2 hour values conservatively utilized conservative database Access Doors and Roof 4.3613-04 to Tower IlA (See Calculation PM- PM-1059, Rev 3 1059, Rev 3, Scuttles, Railway Bay Doors, 1.28E-02 Attachment G, and Ground-Level Hatches Section 3.1 and Table

________ ____________________________________________4-I)

Attachment 1 Alternative Source Term Supplemental RAI Response Page 10 of 10 Table 6 (continued)

S8-Controlling Receptor Release Point 0-0.5 0-2 hour 2-8 hour 1- Meteorological Justification for Used in Dose 1 hour

_Utilized hour 4 Tower Database Usage Tower 2 is the only Calculation representative database Off-Gas Stack 5.30E-05 9.17E-06 3.24E-06" 1.92E-06 I 6.22E-07 1.23E-07 Tower 2 PM-1077, Rev. 1 (See Calculation PM-1055, Rev 1, Sections 3.2.3. 3.2.4. and 4.1)

EAB The highest of the Units 2 and 3 Reactor Building X/Qs predicted by the (823 m)

Stacks, Turbine Building, and representative Towers 2, 1A, and River PM-1077, Rev. 1, Personnel Access Doors, 9.11E-04 4.67E-04" 3.35E-04 1.64E-04 6.26E-05 Tower 1A Tower/lA databases PM-1057, Rev. 2, Railway Bay Doors, Roof were selected (See PM-1059, Rev 3 Scuttle, and Ground-Level Calculation PM-Hatches 1055, Rev 1, Sections 3.2.4 and 4.1)

Tower 2 is the only Off-Gas Stack representative database 1.75E-05 9.05E-06 4.01E-06" 2.67E-06 1.1OE-06 3.1OE-07 Tower 2 PM-1077, Rev. I (See Calculation PM-1055, Rev 1, Sections 3.2.3. 3.2.4. and 4.1 )

LPZ The higher of the (7,300 m) Units 2 and 3 Reactor Building X/Qs predicted by the Stacks, Turbine Building, and representative Towers PM-1077, Rev. 1, Personnel Access Doors, 1.38E-04 5.81E-05* 3.77E-05 1.48E-05 4.15E-06 Tower IA 2 and IAdatabases PM-1057, Rev. 2, Railway Bay Doors, Roof were selected (See PM-1059, Rev 3 Scuttle, and Ground-Level Calculation PM-Hatches 1055, Rev 1, Sections 3.2.4 and 4.1) 1

• PAVAN result representing 0-8 hour time period.

NOTE: AST Calculation PM-1058 for the Main Steam Line Break accident utilized Regulatory Guide 1.5 methodology for off-site X/Qs, and steam cloud concentrations rather than X/Qs for Control Room dose modeling, as developed within Calculation PM-1058.