ML20012E170

Forwards Addl Info Re Ari/Rpt Sys Power Supply,Per NRC 900110 Request

ML20012E170
Person / Time
Site:	Brunswick
Issue date:	03/13/1990
From:	Loflin L CAROLINA POWER & LIGHT CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NLS-90-061, NLS-90-61, TAC-73351, TAC-73352, NUDOCS 9003300169
Download: ML20012E170 (7)

Text

{{#Wiki_filter:.. _ r l I-Caronna Power & Light Company SERIAL: NLS-90-061 l [. g i MAR 131990 [ f e United States Nuclear Regulatory Commission ATTENTION: Document Control Desk-Washington, DC 20555 BRUNSWICK STEAM ELECTRIC PLANT, UNIT NOS. 1 AND 2 i DOCKET NOS. 50-325 & 50-324/ LICENSE NOS. DPR-71 & DPR-62 ARI/RPT SYSTEM POWER SUPPLY (TAC NOS. 73351/73352) i-Centlemen: g In a. letter. dated January 10th,1990, the NRC requested Carolina Power & Light Company (CP&L) to furnish additional information associated with the RTS and the ARI/RPT system to assure and demonstrate that a common mode failure would' not propagate through the, power supplies and disable both the RTS and ARI/RPT systems. Enclosure l' provides the additional information requested. We hope that this additional'information will aid in your review. Please refer any ' questions regarding this submittal to Mr. M. R. Oates at (919) 546-6063. Yours very truly, L. I. Lo lin Manag Nuclear Licens ng Section DBB/eoo (615ECC) Enclosure oo: Mr. S. D. Ebneter Mr. N. B. Le Mr. W.' H. Ruland 7 r .fh l \\ i i F 9003300169 900313 PDR ADOCK 05000324 NevHle Street e P. O. Box 1551

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Fg Nv 'X g .s# 3 b n.3' p 5 ENCLOSURE 1 ARI/RPT SYSTEM POWER SUPPLY u [ Staff Request Item 1: Demonstrate that the " qualified isolators" (two fuses) have been properly ' sized to prevent fault propagation. CP&L Response to Item-1: .The NRC SER (October 21, 1986) states that proper isolation consists of two L qualified Class 1E breakers in series or two fuses or a combination of one l. fuse and one breaker in series as an acceptable means of isolation. In response to the Staffs letter dated August 21, 1989, CP&L's letter dated October 23, 1989, Enclosure 1 Figure 4 (system isolation) indicated a number of qualified isolators in series. However, the only isolators required to . prevent propagation and/or single failure would be the branch circuit ~ breaker 2 for the ARI/RPT system or branch circuit breaker 19 for the ATTU ~ oabinot and the main circuit breaker of 125VDC distribution panel _12A. The attached circuit breaker coordination curves clearly indicate _that the branch oircuit breakers will trip before the main circuit ;breakar, thereby isolating .the equipment served by= that particular ' branch circuit breaker from the rest i of the system.. F p Staff Request' Item 2: l Demonstrate that a common mode failure affecting the 125/250 VDC distribution system (including degraded voltage:and/or frequency conditions, i.e., over-voltage and undervoltage; the effects of degraded voltage / frequency conditions can go undetected)Loannot compromise both the RTS and the ARI/RPT functions. If alarms are relied on-to-provide early detection of degraded voltage /- frequency conditions, the information should include the specific alarm (s) and their setpoint value(s),' and the limiting voltage / frequency' values for which the affected circuits / components have been analyzed / demonstrated to still-be - capable of performing their intended functions. CP&L's Responses to Itsm 2: 1 As. previously provided (CP&L letter dated October 23, 1989) the RTS logio and actuation.oevices are from an A.C. source supplied from M-0 sets and the ARI - logio and actuation devices are supplied from a non-interruptible Class 1E. 'D.C.csource. The configuration of qualified isolators in series prevents the possibility of common mode; failure other than that of a passive device,Li.e. seissio supported cable supplying 125VDC power to 125VDC distribution panel '"12A". However, if this 125VDC reeder cable to 125VDC distribution panel 12A were'to fail and the ARI/RPT system including service to the trip calibration -oabinet XU-65 are lost, the 120VAC supplied logic and actuation devices for L the RTS system would receive a half scram signal from trip channel "A". This 'would still allow the RTS to be capable of performing its intended function.

Q, %;bl f-i p-i l' The batteries are designed to provide an adequate power source for' supplying the engineered' safety feature loads of one unit, and the shutdown loads of the second unit, with concurrent loss of offsite power and any single failure in the D.C. system. The design and performance characteristics of the 125/250 volt' D.C. batteries are such.tnat the battery voltage lower range is 105 volts i for the.125 VDC service. This type of voltage drop or undervoltage will not effect or compromise operation'or either the RTS as previously explained (loss L of DC power provides half scram signal) or the ARI/RPS system which will be explained later. Additionally, Technical Specifications (TS) require that j each-of the 125V batteries and chargers shall be demonstrated to be operable at least once per. seven days by verifying that the parameters in TS Table J 4.8.2 3 2-1L meet category "A" limits and total battery terminal voltage is ' greater than or equal to 129 volts on float charge. The 125/250VDC annunciation / alarms and their setpoints are as follows: j! nit 1 Annunciator-Panel UA Window 1-7 250V battery A undervoltage.. 129VDC decreasing (for Bus 1 A-1 and 1 A-2) Annunciator Panel UA Window 1-8 250V battery B undervoltage... 129VDC decreasing (for Bus 1B-1 and 1B-2)- Unit 2 Annunciator Panel UA Window 1-7 250V battery A undervoltage.. 129VDC decreasing (for Bus 2A-1 and 2A-2) Annunciator Panel UA Window 1-8 250V battery.B undervoltage.. 129V decreasing L (for Bus 2B-1 and 2B-2) As previously indicated, the minimum voltage of the battery system-is 105 l Volts which is above the limiting voltage range-of the ARI/RPT components. ' Control loop voltage drop calculations performed on the ARI/RPT oircuits (see-attached)-indicate.a maximum voltage drop of. 4.92 volts, which, when deducted l Trom Lthe minimum 105VDC supply voltage, leaves a minimum voltage 'of 100.08VDC. -This is equal' to or greater than the voltage ranges of devices as -

indicated below,.thus ensuring actuation as designed.

The voltage ranges for these. components are'as follows:

1) ASCO solenoid valves (SV5500. SV5501, SV5502, SV5503, SV5498, SV5499, SV5643, and SV5644). NPL8316A77E have a coil operating voltage range of 90'to 140VDC.

2) Agastat relays (3-1 through 3-4) Cat. Nos. E7014PALLOO2 and E7022PD002 are operational at 80 to 110% of rated voltage or 100 to 137-1/2 VDC.

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