ML061250341

Request for Additional Information Related to LAR for Updated SAR Clarification of Operator Action During Loss of Main Feedwater Event

ML061250341
Person / Time
Site:	Fort Calhoun
Issue date:	05/05/2006
From:	Wang A NRC/NRR/ADRO/DORL/LPLG
To:	Ridenoure R Omaha Public Power District
Wang A
References
TAC MC7524
Download: ML061250341 (5)

Text

May 5, 2006 Mr. R. T. Ridenoure Vice President - Chief Nuclear Officer Omaha Public Power District Fort Calhoun Station FC-2-4 Adm.

Post Office Box 550 Fort Calhoun, NE 68023-0550

SUBJECT:

FORT CALHOUN STATION, UNIT 1 - REQUEST FOR ADDITIONAL INFORMATION RELATED TO LICENSE AMENDMENT REQUEST FOR UPDATED SAFETY ANALYSIS REPORT CLARIFICATION OF OPERATOR ACTION DURING LOSS OF MAIN FEEDWATER EVENT (TAC NO. MC7524)

Dear Mr. Ridenoure:

By letter dated July 1, 2005, Omaha Public Power District (OPPD) submitted a license amendment request for the Fort Calhoun Station, Unit 1. The license amendment proposed to revise the Updated Safety Analysis Report (USAR), Section 14.10, to credit operator action during the Loss of Main Feedwater Event. The proposed change will add a description of an existing Emergency Operating Procedure operator action to isolate steam generator blowdown within 15 minutes of reactor trip during a loss of main feedwater event to the USAR.

The Nuclear Regulatory Commission (NRC) staff has reviewed OPPDs submittal and had a teleconference on April 24, 2006, with OPPD to discuss this submittal. The NRC staff has determined that additional information is needed to complete our review. A request for additional information (RAI) is enclosed. This request was discussed with Thomas Matthews of your staff on May 1, 2006, and it was agreed that a response would be provided within 6 weeks of receipt of this letter.

If you have any questions, please contact me at (301) 415-1445.

Sincerely,

/RA/

Alan B. Wang, Project Manager Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-285

Enclosure:

RAI cc w/encl: See next page

May 5, 2006 Mr. R. T. Ridenoure Vice President - Chief Nuclear Officer Omaha Public Power District Fort Calhoun Station FC-2-4 Adm.

Post Office Box 550 Fort Calhoun, NE 68023-0550

SUBJECT:

FORT CALHOUN STATION, UNIT 1 - REQUEST FOR ADDITIONAL INFORMATION RELATED TO LICENSE AMENDMENT REQUEST FOR UPDATED SAFETY ANALYSIS REPORT CLARIFICATION OF OPERATOR ACTION DURING LOSS OF MAIN FEEDWATER EVENT (TAC NO. MC7524)

Dear Mr. Ridenoure:

By letter dated July 1, 2005, Omaha Public Power District (OPPD) submitted a license amendment request for the Fort Calhoun Station, Unit 1. The license amendment proposed to revise the Updated Safety Analysis Report (USAR), Section 14.10, to credit operator action during the Loss of Main Feedwater Event. The proposed change will add a description of an existing Emergency Operating Procedure operator action to isolate steam generator blowdown within 15 minutes of reactor trip during a loss of main feedwater event to the USAR.

The Nuclear Regulatory Commission (NRC) staff has reviewed OPPDs submittal and had a teleconference on April 24, 2006, with OPPD to discuss this submittal. The NRC staff has determined that additional information is needed to complete our review. A request for additional information (RAI) is enclosed. This request was discussed with Thomas Matthews of your staff on May 1, 2006, and it was agreed that a response would be provided within 6 weeks of receipt of this letter.

If you have any questions, please contact me at (301) 415-1445.

Sincerely,

/RA/

Alan B. Wang, Project Manager Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-285

Enclosure:

RAI cc w/encl: See next page DISTRIBUTION:

PUBLIC LPLIV R/F RidsNrrPMAWang DGuha, NRR/ADRO SSun, NRR/ADES RidsNrrDorlLpl4 (DTerao)

RidsRgn4MailCenter (DGraves) RidsOgcRp RidsAcrsAcnwMailCenter RidsNrrDorlDpr RidsNrrDssSpwb (JNakowski)

RidsNrrLALFeizollahi RidsNrrPMBSingal ADAMS ACCESSION NO.: ML061250341 OFFICE LPL4/PM LPL4/LA LPL4/BC NAME AWang; mxr4 LFeizollahi DTerao DATE 5/5/06 5/5/06 5/5/06 OFFICIAL RECORD COPY

REQUEST FOR ADDITIONAL INFORMATION REGARDING UPDATED SAFETY ANALYSIS REPORT (USAR) CLARIFICATION OMAHA PUBLIC POWER DISTRICT FORT CALHOUN STATION DOCKET NO. 50-285 By letter dated July 1, 2005, Omaha Public Power District (OPPD), the licensee for the Fort Calhoun Station, Unit 1 (FCS), requested a license amendment to permit FCS to revise the USAR, Section 14.10, to credit operator action during the Loss of Main Feedwater (LMFW)

Event. The proposed change will add a description of an existing Emergency Operating Procedure operator action to isolate steam generator blowdown within 15 minutes of reactor trip during an LMFW event to the USAR. The operator action is intended to assist the auxiliary feedwater system in performing its design function of maintaining adequate steam generator (SG) water level for decay heat removal once the auxiliary feedwater actuation signal is actuated. OPPD requests approval of the proposed change to support plant operations following the 2006 outage during which the SGs, pressurizer, and reactor vessel head will be replaced.

The Nuclear Regulatory Commission (NRC) staff has performed a preliminary review of the human performance associated changes in the license amendment request. The licensees responses to the following request for additional information with regard to containment analysis aspects of the license amendment are needed for the NRC staff to complete its review.

1. Page 22 of Attachment 4 to the licensee's letter of July 1, 2005, stated that for the feedwater line break (FLB) analysis that "SG blowdown flow is automatically and conservatively isolated at 49.03 sec...." The NRC staff has noted that in FCS Technical Specification Table 2-1, a containment pressure high signal (CPHS) or a pressurizer pressure low signal (PPLS) would actuate a containment isolation actuation signal that isolates SG blowdown flow. As such:

a. Please indicate which signal (a CPHS or a PPLS) was credited to automatically isolate the SG in the analysis. Demonstrate that the FLB case with SG blowdown isolation occurring at 49.03 seconds is the limiting break case (considering full-break sizes of the FLB) with respect to the acceptance criterion of the peak post-trip hot-leg temperature of 600 degrees F.

b. If OPPD credited a CPHS to isolate the SG blowdown flow, please discuss how the CPHS time was determined for FLB cases with break sizes ranging from the maximum break size to the smallest credible size.

c. Please provide a description of the containment model to show its adequacy for the CPHS time determination (with respect to prediction of a lower containment pressure resulting in a high CPHS time).

d. For the small-size FLBs that would not result in a CPHS, please discuss the available Emergency Operating Procedures for the operator to manually isolate SG blowdown flow, and show that the proposed operation action (15 minutes after a reactor trip) for the LMFW event is sufficient for the FLB event.

Ft. Calhoun Station, Unit 1 cc:

Winston & Strawn Mr. Daniel K. McGhee ATTN: James R. Curtiss, Esq. Bureau of Radiological Health 1700 K Street, N.W. Iowa Department of Public Health Washington, DC 20006-3817 Lucas State Office Building, 5th Floor 321 East 12th Street Chairman Des Moines, IA 50319 Washington County Board of Supervisors P.O. Box 466 Blair, NE 68008 Mr. John Hanna, Resident Inspector U.S. Nuclear Regulatory Commission P.O. Box 310 Fort Calhoun, NE 68023 Regional Administrator, Region IV U.S. Nuclear Regulatory Commission 611 Ryan Plaza Drive, Suite 400 Arlington, TX 76011-4005 Ms. Julia Schmitt, Manager Radiation Control Program Nebraska Health & Human Services R & L Public Health Assurance 301 Centennial Mall, South P.O. Box 95007 Lincoln, NE 68509-5007 Mr. David J. Bannister, Manager Fort Calhoun Station Omaha Public Power District Fort Calhoun Station FC-1-1 Plant P.O. Box 550 Fort Calhoun, NE 68023-0550 Mr. Joe L. McManis Manager - Nuclear Licensing Omaha Public Power District Fort Calhoun Station FC-2-4 Adm.

P.O. Box 550 Fort Calhoun, NE 68023-0550 April 2006