ML19347B535
| ML19347B535 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 10/10/1980 |
| From: | Brown S VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | Harold Denton, Parr O Office of Nuclear Reactor Regulation |
| References | |
| 893, NUDOCS 8010150304 | |
| Download: ML19347B535 (3) | |
Text
,
e PCO VIRGINI A EL E CTRIC AND PO W ER COMP ANY, RICHMONO, VIRGINI A 23261 Octooer 10, 1980 Mr. Harold R. Denton, Director Serial No.
823 Office of Nuclear Reactor Regulation PSE&C/KSB:vnl: wang Attn: Mr. O. D. Parr, Chief Light Water Reactors Branch No. 3 Docket Nos. 50-339 Division of Project tianagement U. S. Nuclear Regulatory Ccmmission Washington, D.C.
20555
Dear Mr. Denton:
PRIMARY AND SECONDARY ELECTRICAL-PROTECTION OF CONTAIi M NT FENETRATIONS FCR NORTH ANNA POWER STATION, UNIT 2 In compliance with your letters of August 3,1979 and November 30, 1979 on electrical penetration protection for North Anna 2, we hereby submit the primary and secondary (independent back-up) electrical penetraticn protection for the power, control, and instrumentation electrical circuits.
Enclosed are twenty copies each of " Electrical Penetration Protection-Power Circuits (Primary and Secondary)," " Electrical Penetraticn Protection-Control Circuits (Primary and Seconcary)," and "Electricel Penetration Protection-Instrumentation Circuits."
Each of these Documents includes the following information for their respective circuit classification:
1.
Identification of each electrical circuit that penetrates the containment.
2.
Mantification of each penetration type and conductor size, 3.
Description of the primary and seccndary protective devices.
6 Time-current characteristic curves showing the fault current-vs-time regime for the primary and secondary protective devices, the fault current-vs-time regime for the penetrations, and the coordination between the two.
An analysis was made to ensure that the maximum temperature when comoining the penetration temocrature rise due to the maximum fault with the peak LOC 4 temperature did not exceed the maxi. mum temperature for which the penetraticn is cualified.
This analysis assun.ed no heat generatec by fault current passing through
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the cenetration wss lost from the penetration.
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- The following clarifications apply to the instruments.
t circuits:
1.
Time-current characteristic curves are not shown for the majority.of penetrations because the maximum fault current is less than the penetration centinuous rating in those cases.
Secondary protecticn is not required for these cases.
2.
'For.the penetraticns of the following circuits, a maximum fault current has not yet been obtained from the equipment manufacturers.
To ensure protection of the penetration, primary and secondary protection are applied to these circuits.
Time-current characteristic curves have not been included because of the small size of the primary and secondary protective fuses with respect to the penetrations' continuous ratings.
The curves will be provided upon request.
A.
Drive assemblies A, B, C, D, E B.
Drive assemblies A-2, B-2, C-2, D-2, E-2 C.
Five path transfer devices for drive assemblies A, B, C, D, E
D.
Evacuation horn The following clarifications apply to the control circuits:
1.
For curves IB-1, IB-2A, 18-23, IB-3, 18 4, IB-5, IB-6, IB 7,
IB-8, IS-9, and 18-10 a continuous rating of 25 amps has teen used instead of 12 amps. The 12 amp rating applies with 12 amps in each of the 140 conductors. Since this is not a feasible case for control circuits of this nature, we have applied a more realistic case: a shared load of 20 amps in 138 conductors.
This current equals a minimum of twice the full load expected and is applied' simultaneously to the conductors while the actual loads occur intermittantly. Under this condition, any 2 of the 140 conductors are capable of carrying 25. amps continuously.
This rating has been derived by test.
2.
The protection scheme is designed around the highest possible fault current available.
The current shown on the curves is the current calculated using only line impedance from the circult's source. No credit has been taken for power supply or Controller Impedances.
In addition, internal protection devices located in power supplies'or controllers are not incorporated into the analysis, even though these factors decrease available fault current and offer acoltional steps of protection.
3.
For tnase AC and DC circuits which are ungrounded and have a fuse in each leg of the circuit, these fuses serve as primary and secondary protection for the penetration.
4 The_ fault current for curve IB-9 will be no greater than 500 anps.
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.-3 5.
'For those circuits which do not have a full load current specified, the full load current will.not materially affect the
' penetration analysis.
The penetration in curve 18-2B is a #14 feed thru with single 6.
and double seal integrity characteristics shown.
The.following clarification applies to the power circuits:
1.
' Eight circuits associated with non-class lE loads that do, not need to be energized when containment. integrity must be maintained do not have secondary protection. When containment integrity is required, the circuit breakers providing the power feeds to these circuits will be open.
This submittal completes.the~ requirements set forth in paragraph 2-C-10 on The Page 6 of the Facility Operating License NPF-7 issued cn August 21,.1980.
secondary protection will be installed and cperational prior to resuming power cperation following 'the first refueling cutage for Unit 2.
If further information _is required, please contact this office.
Ver' truly,yo 's,
' 'RU [? Ulm
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SeniorVicePresident[i am C. B wn,-Jr.
Power Station Engineerin and Construction cc: Mr. Victor Stello, Director Office of Inspecticn & Enforcement Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation m.