LIC-13-0152, Supplemental Response to Request for Additional Information (RAI) for Exigent License Amendment Request (LAR) to Revise Current Licensing Basis of Pipe Break Criteria for High Energy Piping Outside of Containment

Supplemental Response to Request for Additional Information (RAI) for Exigent License Amendment Request (LAR) to Revise Current Licensing Basis of Pipe Break Criteria for High Energy Piping Outside of Containment

ML13296A066
Person / Time
Site:	Fort Calhoun
Issue date:	10/22/2013
From:	Cortopassi L Omaha Public Power District
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
LIC-13-0152
Download: ML13296A066 (4)

Text

444 South 16th Street Mall Omaha, NE 68102-2247 October 22, 2013 LIC-13-0152 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Mail Station P1-137 Washington, D.C. 20555

References:

1. Docket No. 50-285

2. Letter from OPPD (L. P. Cortopassi) to NRC (Document Control Desk), Fort Calhoun Station - Exigent License Amendment Request 13-08 Revise Current Licensing Basis of Pipe Break Criteria for High Energy Piping Outside of Containment, dated October 6, 2013 (ML13280A089) (LIC-13-0146)

3. Email from NRC (J. Sebrosky) to OPPD (B. R. Hansher), Request for Additional Information (RAI) for Fort Calhouns Station (FCS) Exigent License Amendment Request (LAR) To Revise Current Licensing Basis of Pipe Break Criteria for High Energy Piping Outside of Containment, dated October 9, 2013 (ML13290A002)

4. Letter from OPPD (L. P. Cortopassi) to NRC (Document Control Desk), Response to Request for Additional Information (RAI) for Fort Calhoun Station (FCS) Exigent License Amendment Request (LAR) to Revise Current Licensing Basis of Pipe Break Criteria for High Energy Piping Outside of Containment, dated October 15. 2013 (ML13291A127) (LIC-13-0148)

SUBJECT:

Supplemental Response to Request for Additional Information (RAI) for Fort Calhoun Station (FCS) Exigent License Amendment Request (LAR) to Revise Current Licensing Basis of Pipe Break Criteria for High Energy Piping Outside of Containment On October 6, 2013, pursuant to 10 CFR 50.90 and 10 CFR 50.91(a)(6), the Omaha Public Power District (OPPD) submitted an exigent license amendment request (LAR) (Reference 2) proposing to amend Fort Calhoun Station (FCS), Unit No. 1, Renewed Facility Operating License No. DPR-40 by revising the current licensing basis (CLB) pertaining to pipe break criteria for high-energy piping outside of containment. On October 9, 2013, teleconferences between representatives of OPPD and NRC Staff were held to discuss the LAR. Following the phone call, the NRC emailed (Reference 3) a request for additional information (RAI) to which OPPD responded in Reference 4.

On October 21, 2013, an additional teleconference between representatives of OPPD and NRC Staff was held to discuss the Reference 4 response. OPPD agreed to supplement its Reference 4 response to Mechanical and Civil Engineering Branch (EMCB) RAI-7 to explain how the proposed revision to Criterion B.3.c.(4) ensures that all components with a potential to be wetted by the flow from a leakage crack are identified.

The supplemental response to EMCB-RAI-7 is attached.

No commitments to the NRC are contained in this submittal.

Employment with Equal Opportunity

U. S. Nuclear Regulatory Commission LlC-13-0152 Page 2 If you should have any additional questions or require additional information, please contact Mr. Bill Hansher at (402) 533-6894.

I declare under penalty of perjury that the foregoing is true and correct; executed on October 22,2013.

Louis P. Cortopassi Site Vice President and CNO LPC/SPQ/brh

Attachment:

Supplemental Response to Request for Additional Information (RAI) for Fort Calhoun Station (FCS) Exigent License Amendment Request (LAR) to Revise Current Licensing Basis of Pipe Break Criteria for High Energy Piping Outside of Containment c: M. L. Dapas, NRC Regional Administrator, Region IV J. M. Sebrosky, NRC Senior Project Manager L. E. Wilkins, NRC Project Manager J. C. Kirkland, NRC Senior Resident Inspector Director of Consumer Health Services, Department of Regulation and Licensure, Nebraska Health and Human Services, State of Nebraska

LIC-13-0152 Attachment Page 1 Supplemental Response to Request for Additional Information (RAI) for Fort Calhoun Station (FCS) Exigent License Amendment Request (LAR) to Revise Current Licensing Basis of Pipe Break Criteria for High Energy Piping Outside of Containment By letter dated October 6, 2013 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML13280A089) Omaha Public Power District (the licensee) submitted for Nuclear Regulatory Commission (NRC) approval a license amendment request that would revise the Fort Calhoun Station Updated Safety Analysis Report for pipe break criteria for high energy piping outside of containment. The proposed amendment would allow the use of U.S. Nuclear Regulatory Commission guidance provided in Branch Technical Position Mechanical Engineering Branch 3-1 Revision 2, which allows for the exemption of specific piping sections from postulated failures if certain criteria are met.

Based on a review of the submittal, the NRC staff has determined that the following additional information (RAIs) are required in order to complete its review. The request for additional information was discussed with you on October 9, 2013. It was agreed that a response to these RAIs would be provided by October 15, 2013. Should the NRC determine that these RAIs are no longer necessary prior to the scheduled date, the request will be withdrawn. If circumstances result in the need to revise the requested response date, please contact me at (301) 415-1132 or via e-mail at joseph.sebrosky@nrc.gov. The NRC staff has determined that no security-related or proprietary information is contained herein.

EMCB-RAI-7 The proposed LAR requests to add to the CLB MEB 3-1, Rev 2 Section B.3.c(1) to eliminate HELCs in piping equal to or less than 1 inch. The licensee is requested to include all parts of Section B.3.c or to provide justifications and bases for omitting the remainder parts of Section B.3.c.

OPPD SUPPLEMENTAL RESPONSE Wetting Effects from Critical Cracks Wetting effects from a critical crack are to be determined on a case by case analysis depending on the fluid conditions in the line prior to the crack. Three different cases are included for review:

1. High pressure, high temperature lines with less than 70°F sub-cooling Wetting effects are to be determined based on engineering judgement using guidance provided in Sandia National Laboratory study documented in NUREG/CR-2913. This study provided a relationship between break stagnation conditions and the impingement zone of influence (lengths and radii from the break), where the liquid jets ranged from 60 to 170 bars and 70 degrees Celsius sub-cooling to saturated conditions, and the steam jets between 0 to 0.75 quality. The results are applicable for steam qualities greater than 0.75 since the

LIC-13-0152 Attachment Page 2 target pressure distribution is a weak function of qualities for stagnation qualities greater than 0.75.

Based on the results of this study, the load associated from a jet at a given target is negligible beyond 10 pipe diameters under worst case conditions. Consequently, there would essentially be no interaction between the jet and targets beyond 10 diameters. As a result, the wetting effects at this point would not be significant other than the environmental effects of wetting due to the increase in humidity. Thus, for high pressure saturated steam conditions or high pressure liquid conditions with limited sub-cooling, the wetting effects will be evaluated based on a criterion of 10 pipe diameters from the crack location. This criterion would apply to the following systems:

Steam generator blowdown to the blowdown tank (FW-7)

Steam generator blowdown tank (FW-7) vent line to atmosphere Steam supply line to AFW pump turbine (FW-10-M)

Letdown upstream from the letdown heat exchanger (CH-7)

2. Low temperature lines These liquid, non flashing jets (below 212°F) will be considered not to expand as they move in a straight line from the crack until gravity forces the water jet to the floor. They will be considered capable of moving beyond 10 diameters. This criterion would apply to the following lines:

This criterion would apply to the following lines:

Chemical and volume control system (CVCS) charging line CVCS letdown line downstream from the letdown heat exchanger (CH-7)

3. Low pressure, high temperature liquid filled lines These lines operate near saturated conditions, approximately 212°F. As the temperature is low enough that flashing may not occur, the wetting effects will be evaluated based on worst case conditions, either using the Sandia methodology of Case 1 above or the straight line methodology for non-flashing jets provided in Case 2 above. This criterion would apply to the following lines:

Steam generator blowdown drain lines from the blowdown tank to the transfer pumps Steam generator blowdown drain lines from the transfer pump to the raw water tie-in