ML19339A723
| ML19339A723 | |
| Person / Time | |
|---|---|
| Site: | Zimmer |
| Issue date: | 10/31/1980 |
| From: | Flynn J CINCINNATI GAS & ELECTRIC CO. |
| To: | Tedesco R Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8011040579 | |
| Download: ML19339A723 (3) | |
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TIIE CINCINNATI GAS & ICLICCTitIC COA 11*ANY rrIZ__ DES CINCINN ATI. OHIO 4 52OI Docket No. 50-358 October 31, 1980 Mr. Robert L. Tedesco Assistant Director for Licensing Division of Licensing U.S.
Nuclear Regulatory Commission Washington, D.C.
20555 RE:
WM. H.
ZIMMER NUCLEAR POWER STATION - ~
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UNIT 1 - STAFF POSITIONS ON DEGRADED GRID is e,
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VOLTAGE AND PROTECTION OF REACTOR CON-ifj
'-b TAINMENT ELECTRICAL PENETRATIONS mm
Dear Mr. Tedesco:
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$2 CD By letter dated September 12, 198 0 to Mr. id. A.
El Borgmann, you requested that CG&E respond to Staff p8sitio$'s x
on degraded grid voltage and protection of reactor containment electrical penetrations.
The attachments to this letter con-tain our responses to the NRC's Staff Positions.
Very truly yours, THE CINCINNATI GAS & ELECTRIC COMPANY gifffAt.
o By J
S D.
FLYNN, Manager Licensing and Environmental Affairs JDF: dew Enclosures cc:
Charles Bechhoefer Glenn O. Bright Frank F. Hooper Troy B. Conner, Jr.
James P. Fenstermaker Steven G. Smith William J. Moran J.
Robert Newlin William G.
Porter, Jr.
Earl A.
Borgmann F. T.
Daniels W.
Peter Heile Leah S.
Kosik John D. Woliver Mary Reder 6011040 $["7'T
' David K. Martin f
Robert A. Jones Andrew B.
Dennison p/
RESPONSE TO NRC POSITION ON DEGRADED GRID VOLTAGE
RESPONSE
A.
A second level of undervoltage protection is provided at each of the emergency buses.
This undervoltage protection meets criteria a-e defined by Section A of the staff position on degraded grid voltage.
The Technical Specification shall include limiting conditions for operation, surveillance requirements, trip set points including tolerances, and allowable values for the second-level of undervoltage protection sensors and associated time delay devices.
B.
It is the applicant's position that the existing load shedding system is adequately designed to prevent in-advertent load shed operations.
After the onsite sources are supplying power to sequenced loads in response to an ECCS actuation signal, a load shed will only occur if:
- 1) The voltage at the emergency bus dips below approximately 50% of the rated value.
- 2) The voltage remains at this level for a pre-determined time.
These conditions ensure that a loss of onsite power has occurred.
The undervoltage sensors include co-incidence logic on a per bus basis to preclude spurious-load shed operations.
The set points and time delays of the undervoltage sensors will be verified during periodic testing performed in position A above.
C.
The Technical Specifications will include a requirement to demonstrate the full functional operabilicy and independence of the onsite power sources at least once per 18 months during shutdown.
The testing requirements will comply with the criteria defined by section C of the position on degraded grid voltage.
D.
This requirement has previously been addressed in tla response to position 423.40(14) submitted with Revision 65 (April, 1980) of the FSAR.
Reference:
Volume 12, Qua;' ions and Answers for Chapter 14, Page Q423.40-1.
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RESPONSE TO NRC POSITION ON PROTECTION OF REACTOR CONTAINMENT ELECTRICAL PENETRATIONS
RESPONSE
The penetration design will conform to position Cl of Regulatory Guide 1.63 (Oct., 1973) and with respect to back-up overcurrent protection either:
1)
" Incorporating adequate self-fusing characteristics with the penetration conductors themselves constitutes an acceptable design approach" or 2)
Where self-fusing characteristics are not incorporated, the current cverload protection system will conform to IEEE-279(71); ANSI-N42.7(72).
As an alternate method, overcurrent devices upstream from the overcurrent device protecting the penetration will provide fully coordinated back-up protection to maintain penetration integrity.over the expected range of fault currents.
NOTES:
1)
Position 2 above applies to power circuits only.
Control and instrument circuits are not subject to detrimental high level fault currents.
2)
Regulatory Guide 1.63, Revision 1 (May, 1977) was identified for implementation on construction permit applications docketed after December 30, 1977.
In addition, as listed in NUREG-04 27 Table III-13 and III-14; Regulatory Guide 1.63 is identified as a category I or category II item.
As such, the applicant shall be allowed to demonstrate tF-adequacy of Revision 0 of the Regulatory Guide.
3)
It is the applicant 's position that the FSAR was evaluated under Revision 0 of Regulatory Guide 1.63 and the Safety Evaluation Report'(NUREG-0528) issued on that basis.
Reference:
FSAR, Appendix C (Conformance to Regulatory Guides)
Page C-51, Revision 36 (November, 1977).
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