ML051960406

Dresden and Quad Cities - RAI Alternative Source Term Amendment Request

ML051960406
Person / Time
Site:	Dresden, Quad Cities
Issue date:	07/22/2005
From:	Banerjee M NRC/NRR/DLPM/LPD3
To:	Crane C Exelon Generation Co
Banerjee, M. NRR/DLPM/LPD3-2, 415-2277
References
TAC MB6530, TAC MB6531, TAC MB6532, TAC MB6533
Download: ML051960406 (8)

Text

July 22, 2005 Mr. Christopher M. Crane, President and Chief Nuclear Officer Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555

SUBJECT:

DRESDEN NUCLEAR POWER STATION, UNITS 2 AND 3, AND QUAD CITIES NUCLEAR POWER STATION, UNITS 1 AND 2 - REQUEST FOR ADDITIONAL INFORMATION REGARDING ALTERNATIVE SOURCE TERM AMENDMENT REQUEST (TAC NOS. MB6530, MB6531, MB6532, AND MB6533)

Dear Mr. Crane:

By letter dated October 10, 2002, Exelon Generation Company (Exelon) submitted an amendment request to support application of an alternative source term (AST) at Dresden Nuclear Power Station, Units 2 and 3, and Quad Cities Nuclear Power Station, Units 1 and 2.

Our continuing review of the AST amendment request and past request for additional information (RAI) responses in the dose assessment and meteorological areas has resulted in additional questions and need for additional information. These questions are enclosed. These questions were mailed electronically to your staff on June 29, 2005, and could not be discussed with your staff until July 18 and 19, 2005, due to schedule constraints. Please respond to this RAI within 30 days from the date of this letter. A late or incomplete submittal may result in denial of the amendment request under the provisions of 10 CFR 2.108.

Please contact me at 301-415-2277 if your staff has any questions about this RAI.

Sincerely,

/RA/

Maitri Banerjee, Senior Project Manager, Section 2 Project Directorate III Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket Nos. 50-237, 50-249, 50-254, and 50-265

Enclosure:

Request for Additional Information cc w/encl: See next page

July 22, 2005 Mr. Christopher M. Crane, President and Chief Nuclear Officer Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555

SUBJECT:

DRESDEN NUCLEAR POWER STATION, UNITS 2 AND 3, AND QUAD CITIES NUCLEAR POWER STATION, UNITS 1 AND 2 - REQUEST FOR ADDITIONAL INFORMATION REGARDING ALTERNATIVE SOURCE TERM AMENDMENT REQUEST (TAC NOS. MB6530, MB6531, MB6532, AND MB6533)

Dear Mr. Crane:

By letter dated October 10, 2002, Exelon Generation Company (Exelon) submitted an amendment request to support application of an alternative source term (AST) at Dresden Nuclear Power Station, Units 2 and 3, and Quad Cities Nuclear Power Station, Units 1 and 2.

Our continuing review of the AST amendment request and past request for additional information (RAI) responses in the dose assessment and meteorological areas has resulted in additional questions and need for additional information. These questions are enclosed. These questions were mailed electronically to your staff on June 29, 2005, and could not be discussed with your staff until July 18 and 19, 2005, due to schedule constraints. Please respond to this RAI within 30 days from the date of this letter. A late or incomplete submittal may result in denial of the amendment request under the provisions of 10 CFR 2.108.

Please contact me at 301-415-2277 if your staff has any questions about this RAI.

Sincerely,

/RA/

Maitri Banerjee, Senior Project Manager, Section 2 Project Directorate III Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket Nos. 50-237, 50-249, 50-254, and 50-265

Enclosure:

Request for Additional Information cc w/encl: See next page DISTRIBUTION:

PUBLIC RidsNrrDLpmLpdiii2 (GSuh) RidsRgn3MailCenter RDennig PDIII/2 R/F RidsNrrPMGDick RidsNrrDlpmDpr RidsNrrLAPCoates RidsOgcRp LBrown RidsNrrPMMBanerjee RidsAcrsAcnwMail JHayes ADAMS Accession Number: ML051960406 NRR-088 OFFICE PDIII-2/PM PDIII-2/PM PDIII-2/LA DSSA:SPSB DSSA:SPSB SC:SPSB PDIII-2/SC NAME MBanerejee GDick THarris for LBrown JHayes RDennig GSuh PCoates DATE 07/21/05 07/21/05 07/21/05 07/21/05 07/22/05 07/21/05 07/22/05 OFFICIAL RECORD COPY

Dresden and Quad Cities Nuclear Power Stations cc:

Site Vice President - Dresden Nuclear Power Station Exelon Generation Company, LLC Exelon Generation Company, LLC 4300 Winfield Road 6500 N. Dresden Road Warrenville, IL 60555 Morris, IL 60450-9765 Vice President of Operations - Mid-West Dresden Nuclear Power Station Plant Manager Boiling Water Reactors Exelon Generation Company, LLC Exelon Generation Company, LLC 6500 N. Dresden Road 4300 Winfield Road Morris, IL 60450-9765 Warrenville, IL 60555 Regulatory Assurance Manager - Dresden Vice President - Licensing and Regulatory Exelon Generation Company, LLC Affairs 6500 N. Dresden Road Exelon Generation Company, LLC Morris, IL 60450-9765 4300 Winfield Road Warrenville, IL 60555 U.S. Nuclear Regulatory Commission Dresden Resident Inspectors Office Director - Licensing and Regulatory 6500 N. Dresden Road Affairs Morris, IL 60450-9766 Exelon Generation Company, LLC 4300 Winfield Road Chairman Warrenville, IL 60555 Grundy County Board Administration Building Associate General Counsel 1320 Union Street Exelon Generation Company, LLC Morris, IL 60450 4300 Winfield Road Warrenville, IL 60555 Regional Administrator U.S. NRC, Region III Manager Licensing - Dresden, 801 Warrenville Road Quad Cities and Clinton Lisle, IL 60532-4351 Exelon Generation Company, LLC 4300 Winfield Road Illinois Emergency Management Warrenville, IL 60555 Agency Division of Disaster Assistance & Site Vice President - Quad Cities Nuclear Preparedness Power Station 110 East Adams Street Exelon Generation Company, LLC Springfield, IL 62701-1109 22710 206th Avenue N.

Cordova, IL 61242-9740 Document Control Desk - Licensing Exelon Generation Company, LLC Quad Cities Nuclear Power Station 4300 Winfield Road Plant Manager Warrenville, IL 60555 Exelon Generation Company, LLC 22710 206th Avenue N.

Cordova, IL 61242-9740 Senior Vice President - Nuclear Services

Dresden and Quad Cities Nuclear Power Stations cc:

Regulatory Assurance Manager - Quad Cities Exelon Generation Company, LLC 22710 206th Avenue N.

Cordova, IL 61242-9740 Quad Cities Resident Inspectors Office U.S. Nuclear Regulatory Commission 22712 206th Avenue N.

Cordova, IL 61242 David C. Tubbs MidAmerican Energy Company One River Center Place 106 E. Second, P.O. Box 4350 Davenport, IA 52808-4350 Vice President - Law and Regulatory Affairs MidAmerican Energy Company One River Center Place 106 E. Second Street P.O. Box 4350 Davenport, IA 52808 Chairman Rock Island County Board of Supervisors 1504 3rd Avenue Rock Island County Office Bldg.

Rock Island, IL 61201

DRESDEN NUCLEAR POWER STATION, UNITS 2 AND 3 AND QUAD CITIES NUCLEAR POWER STATION, UNITS 1 AND 2 REQUEST FOR ADDITIONAL INFORMATION ALTERNATIVE SOURCE TERM AMENDMENT REQUEST The following request for additional information (RAI) is generated from the Nuclear Regulatory Commission staffs continued review of the subject amendment request:

1. For the control rod drop accident analysis, the results of the staffs confirmatory analysis do not match Exelon's conclusions. Please provide your calculations. In addition, please discuss the assumptions used for radionuclide deposition and plateout during the period of mechanical vacuum pump operation.

2. For the fuel handling accident analysis, the staff's confirmatory analysis does not match Exelon's conclusions. This disparity may be caused by the assumed release rate.

Please confirm that Exelons analysis assumes that the entire activity released from the fuel pool is released to the environment at the end of two hours. Please provide the calculation for the pool decontamination factor.

3. For the main steamline break accident analysis, the contributions from noble gases and cesium do not appear to be included in Exelons analysis. Please provide the results of an analysis considering cesium and noble gas contributions. Please provide the assumptions utilized in determining the effect of cesium and noble gases upon dose.

4. Loss-of-Coolant Accident (LOCA )

a. Exelon's analysis assumes credit for radionuclide deposition in vertical main steamline components. It is inappropriate to consider deposition and plateout in such sections of piping. Please provide a revised analysis which does not take credit for vertical removal, or provide a justification for why credit for a vertical run of pipe is appropriate. Please provide Stone & Webster Calculation 086457.022-UR(B)-001, Rev. 0, "Modeling Gravitational Settling/Plateout in Main Steam Lines at Dresden 2 & 3 and Quad Cities 1 & 2," if it is still being used and relied upon in your analysis [sensitive information - redacted].

b. Please provide the bases for the reduction in the drywell and main steam isolation valve leakage by 50 percent after 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, including the applicable reactor pressure vessel and drywell pressures used in this analysis.

c. For the drawdown time for the standby gas treatment system (SGTS), it is the staffs understanding that the actual performance at Dresden has shown the reactor building at positive pressure for a period of time following the SGTS receiving a start signal. This appears to be contrary to information provided in responses to a previous RAI and to the alternate source term submittal. Please provide information on those occurrences where the reactor building was not at a negative pressure. Provide an analysis which accounts for the reactor building being positive, or provide justification for the staff to conclude that the reactor

building pressure is being maintained negative.

d. The licensee's analysis assumes a leakage rate of one gallon per minute (gpm) for emergency core cooling system leakage contributions, but it is unclear how this number is supported by plant procedures. Please provide the bases for the assumed leakage rate, including a discussion of applicable plant procedures and surveillance practices which assure that actions are taken to limit actual leakage to one gpm.

e. The staffs calculations do not result in a decontamination factor of 200 for elemental iodine in the drywell at 3.1 hours1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />. Please provide additional details on the analytical assumptions and initial conditions used in determining the value of 3.1 hours1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />.

5. With respect to control room dose calculations, Exelon indicated in a response to a previous request for information that operation of the normal control room ventilation system was assumed during all or parts of all accidents. Given that tracer gas inleakage testing was only done for emergency ventilation system operation, please provide information as to how Exelon has confirmed the inleakage characteristics of the control room envelope in the normal operating mode. Please discuss how the system will operate in the event of a loss of offsite power.

6. Please discuss whether the control room X/Q values listed in Attachments 2 and 3 to the November 5, 2004, response to an RAI are limiting. Please address whether there are penetrations or other possible release locations that are closer to the control room intake which would result in higher X/Q values and whether factors such as loss of offsite power or single-failure (e.g., loss of forced ventilation) would result in more limiting X/Q values. Page 7 of Attachment 4 states that only one release scenario was considered for each of the design-basis accidents. Please discuss the bounding nature of these scenarios for each design-basis accident.

7. Please discuss whether the elevated release X/Q values in Attachments 2 and 3 to the November 5, 2004, letter adequately reflect reduced effective plume heights due to terrain. The PAVAN input files provided as an enclosure to the November 5, 2004, letter, do not include arrays of terrain heights as a function of distance and direction.

Page 2 of the attachment to an October 31, 2003, response to an RAI states that there is a general lack of complexity to the terrain surrounding both sites, but estimates a maximum terrain height of about 25 feet at an unspecified location. Therefore, please provide a table of terrain heights as a function of distance and direction suitable for input into PAVAN. In addition, please discuss the results for downwind sectors with increases in terrain height and whether the resultant X/Q values in those sectors are still lower than the limiting X/Q values presented in Attachments 2 and 3 of the November 5, 2004, letter.

8. For purposes of considering the effects of possible downwash in the ARCON96 X/Q calculations, please provide the station chimney diameter(s) and estimated effluent vertical velocities and stack flows during the applicable design-basis accidents.

9. Please confirm that the direction from the Dresden control room intake looking toward

the station chimney is approximately 48 degrees from true north (i.e., in a northeasterly direction).

10. Please provide a reference citing when Regulatory Guide 1.5 was previously used and reviewed by the staff to estimate the exclusion area boundary and low population zone X/Q values for the main steamline break accident dose assessments.