ML20098C828
| ML20098C828 | |
| Person / Time | |
|---|---|
| Site: | Hatch  |
| Issue date: | 09/20/1984 |
| From: | Gucwa L GEORGIA POWER CO. |
| To: | Stolz J Office of Nuclear Reactor Regulation |
| References | |
| NED-84-505, TAC-55633, NUDOCS 8409270225 | |
| Download: ML20098C828 (2) | |
Text
F Georgia Power Ccmpany 333 Piedmont Avenue Atfanta, Georgia 30308 Telephone 404 5266526 Mailing Address:
- Post Off;ce Box 4545 Atlanta, Georgia 30302 Georgia Power L T. Gucwa the SOUThem elecinc System Manager Nuclear Engineering and Chief Nuclear Engrneer NED-84-505 September 20, 1984 Director of M1 clear Reactor Reg 21ation
- Attention. Mr. John F. Stolz, Chief Operating Beactors Branch No. 4 Division of Licensirg
-U. S. M1 clear Regulatory Canmission Washirgton, D. C.
20555 NRC DOCKER 50-366 OPERATING LIGNSE NPF-5 EIMIN I. HA701 NUCLEAR PIANT UNIT 2 (INTAD5DTP IENETRATION OVERQRRENT NOTECTION Gentlemen:
Our subnittal of A1 gust 27,1984 proposed changes to the Hatch Unit 2 Technical Specifications to upgrade Table 3.8.2.6-1, Primary Penetration Overcurrent Protective. Devices, to reflect revised electrical current reglirements for newly installed motors.
R1ralant to subseq2ent disalssions with members of your staff, we hereby provide additional information in this regard:
The four affected penetrations are General Electric 100 Series Electric Penetration Assemblies using #8 size wire.
Reviews of the specification sheets for this type penetration assembly indicate the following current verals time ratings:
-1.
Steady state alrrent rating - 50 anps l
2.
Startup current rating (30 seconds) - 350 amps 3.
Short circuit current rating (8 cycles or 0.133 seconds) -
3300 amps RMS asymmetrical or 2350 amps symetrical The affected circuit breakers listed in Technical Specifications Table 3.8.2.6-1 are Westinghause Mark 75 HEB type molded case magnetic only (providing short circuit protection only) breakers.
Reviews of marufacturer's specification sheets and characteristic trip curves for this breaker indicate an interrupt time of approximately 0.016 seconds (1 cycle),
which is bounded by the 8 cycle short cirolit alrrent duration potential of the penetrativ n as indicated above.
These breakers are certified to NEMA standard ABl (1969)-Paragraphs 2.16 and 2.22.
Backup protection asalmirg single failures of these breakers, as reglired by Reg 21atory G2ide 1.63 (October 1973), is provided by fuses located in the motor control centers.
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Georgia Power A U. S. M1 clear Regulatory Comission September 20, 1984 Page 2
%e trip setpoints as listed in 'mchnical Specification Table 3.8.2.6-1 are not based solely on protection of contairunent penetrations.
The trip setpoints of the affected breakers are based on Westinghouse recomendations designed -to protect cables, etc. inside containment asalming a ground fallt in. the motor.
Westinghouse recomends setting the breaker to a alrrent corresponding to 160 percent of the locked-rotor altrent of the affected motor.
Since the function of the notor is lost before the breaker opens,
. protection of the cables is an economic consideration rather than a safety consideration.
Therefore, charges to the trip setpoints have no effect on plant safety as long as they provide protection for the penetration by remainirg within the alrrent verals time limits of the penetration as discussed above.
The content of
- charges, safety evaluation, significant hazards evaluation, and all other information in our Alcpst 27, 1984 altmittal, remain correct.
@is letter provides additional information to be used in the staff's evaluation of our recpest.
Please contact this office if you desire further information.
4 Very truly yours, W r. % in L. T. G1 cwa REB /
xc:
H. C. Nix, Jr.
Senior Resident Inspector J. P. O'Reilly (NRC-Region II)