ML052080512

Clinton - RAI Application of Alternative Source Term Methodology

ML052080512
Person / Time
Site:	Clinton
Issue date:	07/26/2005
From:	Jabbour K NRC/NRR/DLPM/LPD3
To:	Crane C AmerGen Energy Co
Jabbour K, NRR/DLPM, 415-1496
References
TAC MB8365
Download: ML052080512 (6)

Text

July 26, 2005 Mr. Christopher M. Crane, President and Chief Executive Officer AmerGen Energy Company, LLC 4300 Winfield Road Warrenville, Illinois 60555

SUBJECT:

CLINTON POWER STATION, UNIT 1 - REQUEST FOR ADDITIONAL INFORMATION RE: APPLICATION OF ALTERNATIVE SOURCE TERM METHODOLOGY (TAC NO. MB8365)

Dear Mr. Crane:

By letter dated April 3, 2003, as supplemented by letters dated December 23, 2003, December 9 and 17, 2004, and March 30, 2005, AmerGen Energy Company, LLC, submitted a request for changes to the Technical Specifications that support application of an alternative source term methodology at the Clinton Power Station, Unit 1.

Based on our review of your submittal, the U.S. Nuclear Regulatory Commission (NRC) staff finds that a response to the enclosed request for additional information is needed before we can complete the review. This request for additional information was previously forwarded to your staff; and on July 25, 2005, it was discussed with them. Your staff agreed that a response would be provided on or before August 26, 2005. If the response is not provided by the agreed upon date, AmerGen should notify the NRC staff in writing. Upon written notification, a new date may be established with agreement from the NRC staff. Alternatively, the NRC staff may act on your request consistent with 10 CFR 2.108, Denial of application for failure to supply information.

If you have any comments or questions, please contact me at (301) 415-1496.

Sincerely,

/RA/

Kahtan N. Jabbour, Senior Project Manager, Section 2 Project Directorate III Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. 50-461

Enclosure:

As stated cc: See next page

ML052080512 OFFICE PM:PD3-2 LA:PD3-2 SC:SPSB (A) SC:PD3-2 NAME KJabbour PCoates ADrozd GSuh DATE 7/26/05 7/26/05 7/26/05 7/26/05 Clinton Power Station, Unit 1 cc:

Senior Vice President - Nuclear Services Clinton Power Station Plant Manager AmerGen Energy Company, LLC AmerGen Energy Company, LLC 4300 Winfield Road Clinton Power Station Warrenville, IL 60555 RR 3, Box 228 Clinton, IL 61727-9351 Vice President of Operations - Mid-West Boiling Water Reactors Resident Inspector AmerGen Energy Company, LLC U.S. Nuclear Regulatory Commission 4300 Winfield Road RR #3, Box 229A Warrenville, IL 60555 Clinton, IL 61727 Vice President - Licensing and Chief Operating Officer Regulatory Affairs AmerGen Energy Company, LLC AmerGen Energy Company, LLC 4300 Winfield Road 4300 Winfield Road Warrenville, IL 60555 Warrenville, IL 60555 Regional Administrator, Region III Manager Licensing - Dresden, Quad Cities, U.S. Nuclear Regulatory Commission and Clinton 801 Warrenville Road AmerGen Energy Company, LLC Lisle, IL 60532-4351 4300 Winfield Road Warrenville, IL 60555 Associate General Counsel AmerGen Energy Company, LLC Regulatory Assurance Manager - Clinton 4300 Winfield Road AmerGen Energy Company, LLC Warrenville, IL 60555 Clinton Power Station RR3, Box 228 R. T. Hill Clinton, IL 61727-9351 Licensing Services Manager General Electric Company Director - Licensing and Regulatory Affairs 175 Curtner Avenue, M/C 481 AmerGen Energy Company, LLC San Jose, CA 95125 4300 Winfield Road Warrenville, IL 60555 Chairman of DeWitt County c/o County Clerks Office Document Control Desk-Licensing DeWitt County Courthouse AmerGen Energy Company, LLC Clinton, IL 61727 4300 Winfield Road Warrenville, IL 60555 Site Vice President - Clinton Power Station AmerGen Energy Company, LLC Clinton Power Station RR 3, Box 228 Clinton, IL 61727-9351

Clinton Power Station, Unit 1 cc:

J. W. Blattner Project Manager Sargent & Lundy Engineers 55 East Monroe Street Chicago, IL 60603 Illinois Emergency Management Agency Division of Disaster Assistance &

Preparedness 110 East Adams Street Springfield, IL 62701-1109

REQUEST FOR ADDITIONAL INFORMATION APPLICATION OF ALTERNATIVE SOURCE TERM METHODOLOGY AMERGEN ENERGY COMPANY, LLC CLINTON POWER STATION, UNIT 1 DOCKET NO. 50-461

1. Clintons use of the main steam line aerosol deposition methodology from AEB-98-03, Assessment of Radiological Consequences for the Perry Pilot Plant Application Using the Revised (NUREG-1465) Source Term, appears to be non-conservative. Please address the following concerns:

a. AEB-98-03 modeling assumed 2 removal nodes in each of the unbroken steam lines, with each segment well-mixed. The broken steam line was modeled as one segment (removal node). Clinton extrapolates use of the AEB-98-03 methodology by modeling main steam line deposition in 3 nodes, using the same 50th percentile deposition rate value (deposition velocity) in each node. The staff thinks that this use overestimates the deposition in the later nodes. The model currently used by Clinton assumes the same rate of deposition in each node which is ultimately based on a particle size distribution that has not undergone any change through deposition in upstream nodes. In other words, the removal of the larger, more quickly and easily deposited aerosols would change the size distribution of aerosols in the piping in later piping segments. These later piping segments would be expected to have a higher concentration of smaller aerosols that would be less likely to be deposited, and the deposition velocity in these segments (modeled as removal nodes) should be reduced to reflect this change.

Please discuss whether your aerosol deposition model accounts for or otherwise addresses this change in the aerosol size distribution due to deposition in upstream piping.

b. The calculated aerosol removal rate increases over time (as indicated in the licensees spreadsheet calculation of equivalent aerosol filter efficiency in Appendix A of the March 30, 2005 submittal), where the staff would expect the removal rate to decrease over time because most of the easily deposited aerosols have already been deposited in previous time periods. Please discuss whether your aerosol deposition model accounts for or otherwise addresses this change in the aerosol size distribution over time due to deposition.

c. Half of the pipe circumference was multiplied by the pipe segment length to estimate the aerosol settling area. This formulation appears to include essentially vertical sections of pipe in the settling area, and thus may be non-conservative. Please discuss the effect of including vertical sections, if any, in the estimated aerosol settling area and the resultant effect on aerosol removal.

2. Please address these further considerations with respect to the modeling of main steam line deposition:

a. What is the effect of the decay heat from deposited material in the main steam piping with respect to iodine re-evolution?

b. The report on which the elemental iodine deposition rate was based (MSIV Leakage Iodine Transport Analysis, J.E. Cline, August 20, 1990) also includes resuspension and conversion. Have you considered the effect of resuspension and conversion on the elemental iodine deposition rate?

c. Does the pipe wall temperature used in elemental iodine deposition modeling account for the decay heat of the deposited material in the pipe? How would this additional source of heat affect the deposition assumed?

3. By licensee letter (RS-03-239), dated December 23, 2003, in response to NRC staffs Question 9, it was stated that the LOCA analysis would no longer credit a 50 percent reduction in the feedwater isolation valve (FWIV) leak rate after 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. The correction would be noted in Table 4, Key LOCA Analysis Inputs and Assumptions when a revised analysis would be subsequently submitted. The revised analysis was submitted by licensee letter (RS-05-033), dated March 30, 2005. In revised Table 4, the 50 percent reduction in FWIV leak rate after 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> does not appear to have changed.

Is this assumption used in the revised LOCA analysis?

4. The staff understands how the new filter penetrations requested in the submittal were developed. However, the staff requests that the licensee provide technical data and information to show that the filter, if they were tested and used in the degraded state, would provide satisfactory performance for the entire surveillance period and be sufficiently capable of mitigating an event if it were needed. The staff has reasonable assurance that filters tested in accordance with the criteria set forth in Regulatory Guide (RG) 1.52 Revision 2 or Revision 3, which incorporated a safety factor of 2 or greater, would provide adequate performance to protect public health and safety. A number of studies and data have been developed which confirm adequate performance at the conditions specified in the RG. For penetrations that exceed the values listed in the RG, the staff has no data upon which to base degraded filter performance and thus requires this information to assess the impact on safety.