ML020870348
| ML020870348 | |
| Person / Time | |
|---|---|
| Site: | McGuire, Mcguire  |
| Issue date: | 03/15/2002 |
| From: | Barron H Duke Power Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| Download: ML020870348 (3) | |
Text
Duke Power Company A Duke Energy Company McGuire Nuclear Station MG01VP 12700 Hagers Ferry Rd.
Huntersville, NC 28078-9340 H. B. Barton Vice President, McGuire Nuclear Generation Department March 15, 2002 U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 ATTENTION:
Document Control Desk
SUBJECT:
REFERENCE:
Relief Request 01-005 Request for Additional Information McGuire Nuclear Station Units 1 and 2 Docket Nos.
50-369, 50-370 Duke Relief Request,01-005, dated June 26, 2001 Duke Response to RAI, dated January 11, 2002 Duke Energy Corporation (Duke) submitted Relief Request 01-005 and the RAI, dated June 26, 2001 and January 11, 2002, respectively.
In a followup teleconference on February 14,
- 2002, the NRC staff requested additional information with respect to Duke's response to Question No.
16(a) of the RAI.
The following information is provided to supplement the January 11, 2002 submittal:
"Seismic sequences follow a similar path to core damage as the tornado initiated sequences which are included in the conditional core damage probability (CCDP) estimates submitted. These typically evolve as station blackout sequences with subsequent reactor coolant pump seal LOCAs or turbine driven auxiliary feedwater pump failures. Station blackout sequences were not important contributors to the CCDP calculations for the RI-ISI submittal. This is due to the fact that pipe failures result in an initiating event or loss of a mitigating function. The sequences that dominated the CCDP are those for which a needed mitigating function has been impaired or an important initiator has developed.
In station blackout sequences, many mitigating functions have been impaired and the pipe failure makes an insignificant contribution to the overall failure probability of needed functions. Therefore, the station blackout sequences are insignificant contributors to the CCDP calculations and the LERF/CLERP calculations that depend on them.
o Power.
A D.-k E, rgV Co.panY (704) 875-4800 OFFICE (704) 875-4809 FAX
U.S. Nuclear Regulatory Commission March 15, 2002 Page 2 In the base case PRA, the seismic contribution to CDF is less than a factor of 2 greater than the contribution from the tornadoes. An increase in the station blackout contribution to the CDF/CCDP/LERF/CLERP estimates that might occur by explicitly including the seismic sequences along with the tornado sequences would still leave the blackout contribution as insignificant.
Therefore, our judgment is that the segment rankings as evaluated in the RI-ISI submittal would not be impacted by an explicit treatment of the seismic initiating event."
Please direct questions related to this matter to Norman T.
Simms at (704) 875-4685.
Very truly yours, H.B. Barron cc:
L.A. Reyes Regional Administrator, Region II U.S. Nuclear Regulatory Commission Atlanta Federal Center 61 Forsyth Street, SW, Suite 23T85 Atlanta, GA.
30323 -
3415 R.E. Martin, Project Manager (addressee only)
Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission One White Flint North, M ail Stop O-8G9 11555 Rockville Pike Rockville, MD 20852-2738 S.M. Shaeffer NRC Senior Resident Inspector McGuire Nuclear Station
U.S. Nuclear Regulatory Commission March 15, 2002 Page 3 bxc:
N.T.
Simms M.A.
Pyne (EC090)
G.J. Underwood (EC07J)
R.K. Rhyne (EC07J)
R.D. Klein (MG01MM)
R.
Branch (MG01MM)
ELL (EC050)
Kay Crane McGuire Master File 1.3.2.13