ML030570023
| ML030570023 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 04/29/2003 |
| From: | Macon W NRC/NRR/DLPM/LPD3 |
| To: | Skolds J Exelon Generation Co |
| Macon W, NRR/DLPM/LPDIII-02, 415-3965 | |
| References | |
| TIA-01-014 | |
| Download: ML030570023 (5) | |
Text
April 29, 2003 Mr. John L. Skolds, President Exelon Nuclear Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555
SUBJECT:
RESPONSE TO TASK INTERFACE AGREEMENT 2001-14, "EVALUATION OF LASALLE WATER HAMMER ANALYSIS"
Dear Mr. Skolds:
The U.S. Nuclear Regulatory Commission (NRC) has reviewed your letter dated January 13, 2003, which provided Exelon Generation Company, LLC, (EGC) perspectives regarding Task Interface Agreement (TIA) 2001-14, "Evaluation of LaSalle Water Hammer Analysis," involving the impact of operating LaSalle County Station (LSCS) Residual Heat Removal (RHR) system in Suppression Pool Cooling (SPC) mode.
Your letter stated that EGC agrees with the NRC staffs TIA conclusion that continuous long term operation of a single train of the RHR system in the SPC mode is within the LSCS design basis, but that the LSCS licensing basis is silent with respect to any limitations on the use of SPC. EGC has determined that the LSCS licensing basis needs to be clarified to prevent similar misunderstandings in the future. In this respect, please note that the original General Electric (GE) RHR design basis assumed initiation only from the Standby mode and expected RHR to be aligned in SPC mode during normal power operation for only a low fraction of operating time. Therefore, extended use (increased frequency and long duration) of the RHR system in the SPC mode during normal operation may be outside the original design basis accident analysis assumptions. The staffs position regarding this mode of operation is described in Information Notice (IN) 87-10, "Potential for Water Hammer During Restart of Residual Heat Removal Pumps, Supplement 1, dated May 15, 1997.
Your letter also stated that EGC agrees with the TIA conclusion that the water hammer analysis LSCS used in their assessment did not provide adequate design basis justification for changing the original design intent regarding the extent of SPC usage to allow continuous operation of the RHR system in the SPC mode. LSCS initiated an interim action requiring that whenever a single train of RHR is operating in the SPC mode, the LPCI mode of operation for that RHR train is declared inoperable. The staff finds this interim action is appropriate but not sufficient.
The staff concludes that all modes of operation for a RHR train should be declared inoperable while operating that train in SPC mode because initiation of RHR in any mode could subject that train to water hammer loads.
EGC believes that the TIA position (i.e., that a water hammer analysis is required) is inconsistent with the original design basis accepted by the NRC and requests that a backfit analysis be performed in accordance with Section 50.109 of Title 10 of the Code of Federal Regulations, "Backfitting." Further, EGC believes that this issue is generic in nature and
J. Skolds requests that this TIA position not be imposed at LSCS until the staffs position is resolved generically and uniformly addressed within the industry. After careful review, the staff agrees that a water hammer analysis requirement for "short operational periods" may be inconsistent with the original licensing basis and previous staff reviews. The staff has taken the position that a design basis loss-of-coolant accident (LOCA) coincident with a loss of offsite power (LOOP) is not postulated to occur during the low fraction of time that RHR is expected to be operated in the SPC mode. Therefore, a water hammer analysis is not required for "short operational periods."
The staff further concludes that continuous long term operation of a single train of the RHR system in the SPC mode is not within the LSCS design basis. The staff expects that use of SPC during normal operation would be of short duration and that this design basis limitation is adequately described in the licensing basis. The staff recommends that the Updated Final Safety Analysis Report be updated at the next opportunity. Any increase in frequency beyond that assumed in the licensing basis, once updated, would then constitute a nonconforming condition subject to resolution per Part 9900, "Technical Guidance," of the NRC Inspection Manual. A revision to TIA 2001-14 clarifying the staffs position on water hammer analysis requirements for the RHR system when it is aligned in the SPC mode was issued on April 28, 2003. TIA 2001-14, Revision 1, is being made publicly available in ADAMS under Accession No. ML030640015 and will be accessible from the Electronic Reading Room on the NRC Web site.
In summary, the staff concludes that requiring a water hammer analysis for infrequent use of the RHR system in the SPC mode would be considered a backfit under the provisions of 10 CFR 50.109. Due to the low safety significance of this issue, the staff does not consider it necessary to pursue this as a generic safety issue at this time or revise its position previously provided in IN 87-10 and its supplement. However, the staff recognizes the generic nature of this problem and plans to issue another supplement to IN 87-10 in the near future to clarify the potential impact on operability of the RHR system when it is aligned in SPC mode.
Sincerely,
/RA/
William A. Macon, Jr., Project Manager, Section 2 Project Directorate III Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket Nos. 50-373 and 50-374 cc: See next pages
J. Skolds requests that this TIA position not be imposed at LSCS until the staffs position is resolved generically and uniformly addressed within the industry. After careful review, the staff agrees that a water hammer analysis requirement for "short operational periods" may be inconsistent with the original licensing basis and previous staff reviews. The staff has taken the position that a design basis loss-of-coolant accident (LOCA) coincident with a loss of offsite power (LOOP) is not postulated to occur during the low fraction of time that RHR is expected to be operated in the SPC mode. Therefore, a water hammer analysis is not required for "short operational periods."
The staff further concludes that continuous long term operation of a single train of the RHR system in the SPC mode is not within the LSCS design basis. The staff expects that use of SPC during normal operation would be of short duration and that this design basis limitation is adequately described in the licensing basis. The staff recommends that the Updated Final Safety Analysis Report be updated at the next opportunity. Any increase in frequency beyond that assumed in the licensing basis, once updated, would then constitute a nonconforming condition subject to resolution per Part 9900, "Technical Guidance," of the NRC Inspection Manual. A revision to TIA 2001-14 clarifying the staffs position on water hammer analysis requirements for the RHR system when it is aligned in the SPC mode was issued on April 28, 2003. TIA 2001-14, Revision 1, is being made publicly available in ADAMS under Accession No. ML030640015 and will be accessible from the Electronic Reading Room on the NRC Web site.
In summary, the staff concludes that requiring a water hammer analysis for infrequent use of the RHR system in the SPC mode would be considered a backfit under the provisions of 10 CFR 50.109. Due to the low safety significance of this issue, the staff does not consider it necessary to pursue this as a generic safety issue at this time or revise its position previously provided in IN 87-10 and its supplement. However, the staff recognizes the generic nature of this problem and plans to issue another supplement to IN 87-10 in the near future to clarify the potential impact on operability of the RHR system when it is aligned in SPC mode.
Sincerely, William A. Macon, Jr., Project Manager, Section 2 Project Directorate III Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket Nos. 50-373 and 50-374 cc: See next pages DISTRIBUTION:
PUBLIC WRuland AMendiola TReis RLaufer PD3-2 r/f WMacon BBurgess PCoates RPulsifer JZwolinski/TMarsh RCaruso JMoore CMarco ADAMS Accession Number: ML030570023
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DATE 04/29/03 04/29/03 03/10/03 03/13/03 04/08/03 04/02/03 04/09/03 OFFICIAL RECORD COPY
LaSalle County Station Units 1 and 2 cc:
Site Vice President - LaSalle Regional Administrator Exelon Generation Company, LLC U.S. NRC, Region III 2601 North 21st Road 801 Warrenville Road Marseilles, IL 61341-9757 Lisle, IL 60532-4351 LaSalle County Station Plant Manager Illinois Department of Nuclear Safety Exelon Generation Company, LLC Office of Nuclear Facility Safety 2601 North 21st Road 1035 Outer Park Drive Marseilles, IL 61341-9757 Springfield, IL 62704 Regulatory Assurance Manager - LaSalle Document Control Desk-Licensing Exelon Generation Company, LLC Exelon Generation Company, LLC 2601 North 21st Road 4300 Winfield Road Marseilles, IL 61341-9757 Warrenville, IL 60555 U.S. Nuclear Regulatory Commission Senior Vice President - Nuclear Services LaSalle Resident Inspectors Office Exelon Generation Company, LLC 2605 North 21st Road 4300 Winfield Road Marseilles, IL 61341-9756 Warrenville, IL 60555 Phillip P. Steptoe, Esquire Vice President Sidley and Austin Mid-West Operations Support One First National Plaza Exelon Generation Company, LLC Chicago, IL 60603 4300 Winfield Road Warrenville, IL 60555 Assistant Attorney General 100 W. Randolph St. Suite 12 Senior Vice President Chicago, IL 60601 Mid-West Regional Operating Group Exelon Generation Company, LLC Chairman 4300 Winfield Road LaSalle County Board Warrenville, IL 60555 707 Etna Road Ottawa, IL 61350 Vice President - Licensing and Regulatory Affairs Attorney General Exelon Generation Company, LLC 500 S. Second Street 4300 Winfield Road Springfield, IL 62701 Warrenville, IL 60555 Chairman Illinois Commerce Commission 527 E. Capitol Avenue, Leland Building Springfield, IL 62706 Robert Cushing, Chief, Public Utilities Division Illinois Attorney Generals Office 100 W. Randolph Street Chicago, IL 60601
LaSalle County Station Units 1 and 2 Director - Licensing Mid-West Regional Operating Group Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555 Senior Counsel, Nuclear Mid-West Regional Operating Group Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555 Manager - Licensing -Clinton and LaSalle Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555