ML11286A420
| ML11286A420 | |
| Person / Time | |
|---|---|
| Site: | Watts Bar  |
| Issue date: | 09/16/2011 |
| From: | - No Known Affiliation |
| To: | Division of Operating Reactor Licensing |
| References | |
| Download: ML11286A420 (12) | |
Text
WBN2Public Resource From: Boyd, Desiree L [dlboyd@tva.gov]
Sent: Friday, September 16, 2011 8:57 AM To: Epperson, Dan; Poole, Justin; Raghavan, Rags; Milano, Patrick; Campbell, Stephen Cc: Hamill, Carol L; Boyd, Desiree L; Crouch, William D
Subject:
TVA letter to NRC_09-15-2011_FSAR Ch 15.5 Non-FHA Response Attachments: 09-15-2011_FSAR Ch 15.5 Non-FHA Response_Final.pdf Please see attached TVA letter that was sent to the NRC today.
Thank You,
~*~*~*~*~*~*~*~*~*~*~*~
Désireé L. Boyd WBN 2 Licensing Support Sun Technical Services dlboyd@tva.gov 423-365-8764 1
Hearing Identifier: Watts_Bar_2_Operating_LA_Public Email Number: 542 Mail Envelope Properties (7AB41F650F76BD44B5BCAB7C0CCABFAF231188B0)
Subject:
TVA letter to NRC_09-15-2011_FSAR Ch 15.5 Non-FHA Response Sent Date: 9/16/2011 8:57:22 AM Received Date: 9/16/2011 8:57:29 AM From: Boyd, Desiree L Created By: dlboyd@tva.gov Recipients:
"Hamill, Carol L" <clhamill@tva.gov>
Tracking Status: None "Boyd, Desiree L" <dlboyd@tva.gov>
Tracking Status: None "Crouch, William D" <wdcrouch@tva.gov>
Tracking Status: None "Epperson, Dan" <Dan.Epperson@nrc.gov>
Tracking Status: None "Poole, Justin" <Justin.Poole@nrc.gov>
Tracking Status: None "Raghavan, Rags" <Rags.Raghavan@nrc.gov>
Tracking Status: None "Milano, Patrick" <Patrick.Milano@nrc.gov>
Tracking Status: None "Campbell, Stephen" <Stephen.Campbell@nrc.gov>
Tracking Status: None Post Office: TVANUCXVS2.main.tva.gov Files Size Date & Time MESSAGE 291 9/16/2011 8:57:29 AM 09-15-2011_FSAR Ch 15.5 Non-FHA Response_Final.pdf 146015 Options Priority: Standard Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date:
Recipients Received:
Tennessee Valley Authority, Post Office Box 2000, Spring City, Tennessee 37381-2000 September 15, 2011 10 CFR 50.34(b) 10 CFR 100 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555-0001 Watts Bar Nuclear Plant, Unit 2 NRC Docket No. 50-391
Subject:
Watts Bar Nuclear Plant (WBN) Unit 2 - Final Safety Analysis Report (FSAR) - Chapter 15.5 Design Basis Dose Analysis
References:
- 1. TVA Letter to NRC dated June 27, 2011, Watts Bar Nuclear Plant (WBN) Unit 2 - Final Safety Analysis Report (FSAR) - Response to Request for Additional Information (RAI) Regarding Accident Dose Analysis Basis
- 2. TVA Letter to NRC dated August 5, 2011, Watts Bar Nuclear Plant (WBN) Unit 2 - Final Safety Analysis Report (FSAR) - Chapter 15.5 Design Basis Dose Analysis This letter provides revised FSAR Design Basis Accident dose analysis results for the Main Steam Line Break (MSLB), Steam Generator Tube Rupture (SGTR), and Loss of AC Power accidents. provides updated FSAR Tables for the MSLB, SGTR, and Loss of AC Power events. These results changed as a result of correcting the release elevation of the Unit 2 South Main Steam Valve Vault. The effect on the results was minimal, with the resulting dose being slightly lower than previously calculated. A discussion of the limiting release/receptor points for the Unit 2 Control Room Dose assessments for all accidents analyzed for dose is also provided. lists the new commitments to include the revised analysis in a future FSAR amendment and to submit a revised Fuel Handling Accident and a complete FSAR Section 15.5 draft incorporating recent changes by September 30, 2011.
U.S. Nuclear Regulatory Commission Page 3 September 15, 2011 bcc (Enclosures):
Stephen Campbell U.S. Nuclear Regulatory Commission MS 08H4A One White Flint North 11555 Rockville Pike Rockville, Maryland 20852-2738 Charles Casto, Deputy Regional Administrator for Construction U. S. Nuclear Regulatory Commission Region II Marquis One Tower 245 Peachtree Center Ave., NE Suite 1200 Atlanta, Georgia 30303-1257
Enclosure 1 WBN Unit 2 Revised FSAR Section 15.5 Dose Analysis A telephone call was held with the NRC on August 30, 2011, for a general discussion of the release points from WBN building ventilation exhausts and receptor points at the Main Control Room (MCR) air intakes used in the FSAR Chapter 15 dose analyses for Unit 2. A summary of the discussions follows.
Release points from either the Unit 1 or Unit 2 shield building stack are used for the Loss of Coolant Accident (LOCA) and Fuel Handling Accident (FHA). The South Main Steam Valve Vault is the release point for the MSLB, SGTR, and Loss of AC events. The release point for the Waste Gas Decay Tank Rupture is the normal Auxiliary Building Exhaust. The receptor points for any of these events can be either the east or west MCR intake.
The control room X/Qs were determined using ARCON96. For the LOCA and FHA, the most limiting release/receptor combination is the Unit 1 Shield Building Vent to the west Control Building Intake. The Unit 1 Shield Building Vent is a release point for Unit 2 because for a LOCA or FHA on Unit 2 due to the design of the Emergency Gas Treatment System and Auxiliary Building Gas Treatment System, the release can occur from either the Unit 1 or the Unit 2 Shield Building Stack. Of the various possible combinations, the path described above will result in the highest dose to the operators. The X/Q for the LOCA is 1.09 E-3 for the 0-2 hour time period and 9.44 E-4 for the 2-8 hour time period. Since all releases for the FHA are assumed to occur within 0-2 hours, only the 1.09E-3 X/Q is used for this accident.
For the MSLB, SGTR, and Loss of AC event, the most limiting release/receptor combination is the Unit 2 South Main Steam Valve Vault with the east Control Building Intake. The X/Q for this combination is 2.59 E-3 for the time period of 0-2 hours and 2.12 E-3 for 2-8 hours. The release elevation is 23 meters.
The limiting Waste Gas Decay Tank rupture control room X/Q is 2.56 E-3 for the 0-2 hour time period. This is based on a release from the Auxiliary Building Vent to the east Control Room intake. Since all releases for the Waste Gas Decay Tank rupture are assumed to occur within the 0-2 hour time period, X/Qs for other time periods are not applicable.
The operators are procedurally directed to use the MCR intake that is experiencing the lower dose rate. The analyses take credit for this action for events with a release that exceeds 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />. The analyses assume that the intake that maximizes the dose to the operator is used for the first 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> and then the intake with the lower dose rate is used thereafter. In the case of the limiting LOCA for Unit 2, the west MCR intake is used for the first 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> (X/Qs are 1.09E-03 from 0-2 hours, and 9.44E-04 from 2-8 hours) after which time the east intake would be used. The X/Qs for the path from the Unit 1 shield building vent to the east MCR intake are 1.26 E-4, 9.53 E-5, and 8.07 E-5 for the time periods of 8 to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, 1 to 4 days, and 4 to 30 days respectively. The dose analyses actually used 1.56 E-4, 1.16 E-4, and 9.59 E-5.
These values are conservative relative to the values that could have been used and will result in a higher calculated Control Room dose.
E1-1
Enclosure 1 WBN Unit 2 Revised FSAR Section 15.5 Dose Analysis The elevation of the release point for the South Main Steam Valve Vault was corrected from 20 to 23 meters. This resulted in slightly lower X/Q values and thus slightly lower Control Room doses. The following draft FSAR tables provide updated results from analyses using the corrected elevation.
Table 15.5-2 Doses From Loss of A/C Power Conservative Analysis (rem) 2 HR EAB 30 Day LPZ Control Room Gamma 7.45 E-04 4.18 E-04 2.10 E-04 Beta 4.48 E-04 2.52 E-04 2.52 E-03 Thyroid - ICRP-30 4.57 E-02 2.57 E-02 2.09 E-02 Realistic Analysis (rem) 2 HR EAB 30 Day LPZ Control Room Gamma 1.80 E-08 1.01 E-08 5.05 E-09 Beta 1.66 E-05 9.29 E-06 1.79 E-04 Thyroid - ICRP-30 1.10 E-06 6.18 E-07 5.03 E-07 E1-2
Enclosure 1 WBN Unit 2 Revised FSAR Section 15.5 Dose Analysis Table 15.5-14 Atmospheric Dilution Factors At The Control Building DILUTION FACTOR (sec/m3)
SGTR/MSLB/Loss of Time Period (hr) LOCA/FHA1 WGDT AC Power 0-2 1.09 E-03 2.59E-03 2.56 E-03 2-8 9.44 E-04 2.12 E-03 N/A 8-24 1.56 E-04* N/A N/A 24-96 1.16 E-04** N/A N/A 96-720 9.59 E-05*** N/A N/A GENERAL CONTROL ROOM PARAMETERS Volume 257,198 cu ft Makeup/pressurization flow 711 cfm Recirculation flow 2889 cfm Unfiltered intake 51 cfm Filter efficiency 95% first pass 70% second pass 0% for noble gases, Tritium Isolation time, T 40 seconds Occupancy factors:
0-24 hr 100%
1-4 days 60%
4-30 days 40%
- 1. All FHA releases are within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />. Thus, only the 0-2 hr X/Q is applicable for the FHA.
- Calculated value for U1 Shield Bldg 1.26 E-04 Vent to East MCR Intake
- Calculated value for U1 Shield Bldg 9.53 E-05 Vent to East MCR Intake
- Calculated value for U1 Shield Bldg 8.07 E-05 Vent to East MCR Intake E1-3
Enclosure 1 WBN Unit 2 Revised FSAR Section 15.5 Dose Analysis Table 15.5-17 Doses From Main Steam Line Break 1 gpm Primary- 2 HR EAB 30 Day LPZ SRP Control SRP to-Secondary Guidance for Room Guidance Leakage 10CFR100 for (ARCON-96 X/Q) Limits (rem) 10CFR100 Limits (rem)
Pre-Accident Initiated Spike Case (14 Ci/gm maximum peak)
Gamma 2.74 E-02 1.11 E-02 25 4.32 E-03 5 Beta 8.80 E-03 4.20 E-03 300 3.96 E-02 30 Thyroid - 2.41 E+00 1.21 E+00 300 7.38 E+00 30 ICRP-30 Accident Initiated Spike Case (0.265 Ci/gm steady state)
Gamma 1.04 E-01 1.25 E-01 2.5 8.00 E-03 5 Beta 2.54 E-02 3.02 E-02 30 6.44 E-02 30 Thyroid - 3.09 E+00 4.78 E+00 30 1.03 E+01 30 ICRP-30 E1-4
Enclosure 1 WBN Unit 2 Revised FSAR Section 15.5 Dose Analysis Table 15.5-18 Parameters Used In Steam Generator Tube Rupture Analysis Primary Side Activity Technical Specification Limit Secondary Side Activity ANSI/ANS-18.1-1984 (Expected levels, 150 gpd/SG)
Iodine Spiking Factor Case 1: Accident initiated spike of 500 times equilibrium iodine concentration Case 2: Pre-accident spike of 14 Ci/gm I-131 dose equivalent Iodine Partition Factor 100 Secondary Side Mass Release (Ruptured Steam Generator) 0 -2 hours 103,300 lbm 2 - 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> 32,800 lbm Secondary Side Mass Release (Intact Steam Generator) 0 - 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> 492,100 lbm 2 - 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> 900,200 lbm Primary Coolant Mass Release (Total) 191,400 lbm 0 - 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> Primary Coolant Mass Release (Flashed) 10,077.2 lbm 0 - 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> Meteorology See Table 15A-2 and 15.5-14 E1-5
Enclosure 1 WBN Unit 2 Revised FSAR Section 15.5 Dose Analysis Table 15.5-19 Doses From Steam Generator Tube Rupture Pre-Accident Initiated Spike Case (14 Ci/gm maximum peak)
(rem) 2 HR EAB 30 Day LPZ Control Room Gamma 3.78 E-01 1.11 E-01 6.22 E-02 Beta 2.26 E-01 6.92 E-02 7.01 E-01 Thyroid - ICRP-30 1.39 E+01 3.79 E+00 1.23 E+01 Accident Initiated Spike Case (0.265 Ci/gm steady state)
(rem) 2 HR EAB 30 Day LPZ Control Room Gamma 5.46 E-01 1.60 E-01 5.71 E-02 Beta 2.51 E-01 7.73 E-02 6.64 E-01 Thyroid - ICRP-30 7.19 E+00 2.12 E+00 2.01 E+00 E1-6
Enclosure 2 Regulatory Commitments
- 1. Provide a letter that includes a complete FSAR Section 15.5 draft incorporating the updated X/Qs; the revised results for the MSLB, SGTR , and Loss of AC Power; and the revised FHA results by September 30, 2011.
E2-1