ML19351F731
| ML19351F731 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 01/13/1981 |
| From: | Crutchfield D Office of Nuclear Reactor Regulation |
| To: | Counsil W NORTHEAST NUCLEAR ENERGY CO. |
| References | |
| TASK-03-10.A, TASK-05-11.A, TASK-06-07.C1, TASK-08-03.B, TASK-3-10.A, TASK-RR LSO5-81-01-011, LSO5-81-1-11, NUDOCS 8102200003 | |
| Download: ML19351F731 (22) | |
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-s Mr. W. G. Counsil, Vice President RNgk tf" f Nuclear Engineering and Operations Northeast Nuclear Energy Company Post Office Box 270 Hartford, Connecticut 06101
Dear Mr. Counsil:
RE: MILLSTONE SEP TOPICS III-10.A, V-ll. A, VI-7.C.1, AND VIII-3.B Enclosed are a copy of our evaluation of Systematic Evaluation Program Topics III-10.A, Thermal Overload Protection for Motors of Motor-Operated Valve. ; V-11. A, Electrical Instrumentation and Control Features for Isolation of High and Low Pressure Systems; VI-7.C.1, Independence of Redundant Onsite Power Systems; and VIII-3.B. DC Power System Bus Voltage Monitoring and Annunciation.
These assessments compare your facility, as described in Docket No.
50-245, with the criteria currently used by the regulatory staff for l
licensing new facilities.
Please inform us if your as-built facility l
differs from the licensing bases assumed in our assessments within 90
(
days of receipt of this letter.
t These evaluations will be a basic input to the integrated safety assess-ment for your facility unless you identify changes needed to reflect the as-built conditions at your facility, These topic assessments may be revised in the future if your facility design is changed or if NRC criteria relating to this topic is modified before the integrated assessment is complete.
Sincerely, b67/l.$du4 Dennis M. Crutchfield, [ief Operating Reactors Branch #5 Division of Licensing i
Enclosure:
Draft SEP Topics III-10.A, V-ll.A, VI-7.C,1 and VIII-3,B cc w/ enclosure:
See next page 810 220 0 oo 3 f
l Mr. W. G. Counsil MILESTONE NUCLEAR POWER STATION, UNIT NO. 1 DOCKET NO. 50-245 cc William H. Cud @, Esquire Connecticut Energy Agency Day, Berry & Howard ATTN: Assistant Director Counselors at Law Research and Policy One Constitution Plaza Development Hartford, Connecticut 06103 Department of Planning and Energy Policy Natural Resources Defense Council 20 Grand Street j
hington
- 5. 2 bOS Director, Technical Assessment Division l
Northeast Nuclear Energy Conpany Office of Radiation Programs ATTN: Superintendent (AW-459) s l
. Millstone Plant U. S. Environmental Protection P. O. Box 128 Agency Waterford, Connecticut 06385 Crystal Mall #2 Arlington, Virginia 20460 Mr. James R. Himmelwright Northeast Utilities Service Conpany U. S. Environmental Protection l
P. D. Box 270 Agency Hartford, Connecticut 06101 Region I Office ATTN:
EIS COORDINATOR Resident Inspector.
JFF Federal Building c/o V. S. NRC Boston, Massachusetts 02203 l
P. O. Box Drawer KK Niantic, Connecticut 06357 l
Waterford Public Library Rope Ferry Road, Route 156 j
Waterford, Connecticut 06385 First Selectman of the Town of Waterford Hall of Records 200 Boston Post Road Waterford, Connecticut 06385 John F. Opeka Systams Superintendent Norcheast Utilities Service ~Conpany P. O. Box 270 Hartford, Connecticut 06101 1
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SEP TECHNICAL EVALUATION l
TOPIC III-10.A THERMAL-OVERLOAD PROTECTION FOR MOTORS OF MOTOR-0PERATED VALVES MILLSTONE 1 I
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Docket No. 50-245 April 1980 J
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o SEP TECHNICAL EVALUATION TOPIC III-10.A THERMAL-OVERLOAD PROTECTION FOR MOT 0hG OF MOTOR-OPERATED VALVES MILLSTONE 1 l
TOPIC III-10.A Thermal-Overload Protection for Motors of Motor-Operated l
Valves l
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The objective of this review is to provide assurance that the appli-l cation of thermal-overload protection devices to motors associated with safety-related motor-operated valves do not result in needless hindrance of the valves to perform their safety functions.
In accordance with this objective, the application of either one of the two recommendations contained in Regulatory Guide 1.106, " Thermal-Overload Protection for Electric Motors on Motor-Operated \\*alves," is ade-quate. These recommendations are as follows:
(1)
Provided that the completion of the safety funct ion is not jeopardized or that other safety systems are n:t degraded, (a) the thermal-overload protection devices should be continuously bypassed and temporarily placed in force only when the valve motors are undergoing periodic or maintenance testing, or (b) those thermal-overload protection devices that are normally in force during plant operation should be bypassed under acci-dent conditions.
(2)
The trip setpoint of the thermal-overload protection devices shodid be established with all uncertainties resolved in favor of completing the safety-related action. With respect to those uncertainties, consider-ation should be given to (a) variations in ths ambient temperature at the installed location of the overload 1
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protection devices and the valve motors, (b) inaccura-cies in motor heating data and the overload protection device trip characteristics and the catching of these two items, and (c) setpoint drift.
In order to ensure continued functional reliability and the accuracy of the trip point, the thermal-overload protection device
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should be periodically tested.
In addition, the current licensing criteria require that:
(3) 'In MOV designs that use a torque switch to limit the opening or closing of the valve, the automatic opening or closing signal should be used in conjunction with a corresponding lb=it switch.
DISCUSSION On February 7, 1980, the licensee submitted a list of all safety-related motor-operated valves and the electrical schematics for those valves.' All 65 of the valves listed have thermal-overload protection devices which are not bypassed; there is no docketed information to indi-cate that TOL trip setpoints have been set to comply with Criterion 2, l
above. Additionally, 54 v,alve open functions and 58 valve close functions l
are terminated by torque switches rather than limit switches.
l IVALUATION Thermal-overload protection for motors of motor-operated valves at Millstone 1 does not comply with current licensing criteria. Thermal-overload devices are not bypassed, no information is available to support.
adequacy of trip setpoints, and for most of the valves, torque switches.
rather than limit switches are used to terminate valve travel.
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1388F SEP TECHNICAL EVALUATION REPORT ELECTRICAL, INSTRUMENIATION, AND CONTROL FEATURES FOR ISOLATION OF HIGH AND LOW PRESSURE SYSTEMS yiI n MILLSTONE NUCLEAR STATION, UNIT 1 Northeast Utilities Docket No. 50-245 January 1980 l
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CONTENTS 1
1.0 INIRODUCTION 1
2.0 CRITERLA 1
2.1 Residual Heat Rccoval (RHR) System.
2 2.2 Emergency Core Cooling System..............
2 2.3 Other Systems 3
3.0 DISCUSSION AND EVALUAIION.
3 3.1 Reactor "Jater Clean-Up System..............
3 3.2 Low Pressure Coolant Injection System 4
3.3 Core Spray System 4
4.0 SUMHARY...............
4
5.0 REFERENCES
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SEP TECHNICAL EVALUATION REPORT ELECTRICAL, INSTRUMENTATION, AND ColfrROL FEATURES FOR ISOLATION OF HIGH AND LOW PRESSURE SYSTEMS MILLSTONE NUCLEAR STATION, UNIT 1 1.0 LNIRODUCTION The purpose of this review is to determine if the electrical, instrumentation, and control (EI&C) features used to isolate systems with a lower pressure racing than the reactor coolant prinary system are in compliance with current licensing requirements as outlined in SEP Topic V-11A.
Current guidance for isolation of high and low pres-sure systems is contained in Branch Technical Position (BTP) EICSB-3, BTP 153-5-1, and the Standard Review Plant (SRP), Section 6.3.
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2.0 CRITERIA 2.1 Residual Heat Removal (RHR) Systems. Isolation requirements for RER systems contained in BTP RSB-5-1 are:
(1) The suction side must be provided with the following isolation features:
(a) Two power-operated valves in series with posi-tion indicated in the control room.
(b) The valves must have independent and diverse interlocks to prevent opening if the reactor coolant system (RCS) pressure is above the design pressure of the RER system.
(c) The valves must have independent and diverse interlocks to ensure at least one valve closes upon an increase in RCS pressure above the i
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design pressure of the RER system.
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(2) The discharge side must be provided with one of the l
following features:
(a) The valves, position indicators, and interlocks described in (1)(a) through (1)(c) above.
(b) One or more check valves in series with a
. normally-closed power-operated valve which has 1
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its position indicated in the control room.
If this valve is used for an Emergency Core Cooling System (ICCS) function, the valve =ust open upon receipt of a safety injection signal (SIS) when RCS pressure has decreased below 3ER system design pressure.
(c) Three check valves in series.
(d) Two check valves is series, provided that both may be periodically checked for leak tightness and are checked at least annually.
2.2 Emergency Core Cooling System. Isolation requirements for ECCS are contained in SRP 6.3.
Isolation of ECCS to prevent overpres-surization must meet one of the following features:
(1) One or more check valves in raries with a normally-closed motor-operated valve (MOV) which is to be opened upon receipt of a SIS when RCS pressure is less than the ECCS design pressure (2) Three check valves in series (3) Two check valves in series, provided that both may be periodically checked for leak tightness and are checked at least annually.
i 2.3 Other Systems. All other low pressure systems interfacing with the RCS sust meet the following isolation requirements from BTP EICSB-3:
(1) At leas t two valves in series must be provided to isolate the system when RCS pressure is above the system design pressure and valve position should be provided in the control room (2) For systens 'with two MOVs, each MOV should have independent and diverse interlocks to prevent opening until RCS pressure is below the system design pressure and should automatically close when RCS pressure increases above system design pressure (3) For sys te=s with one check valve and a MOV, the MOV should be interlocked to prevent opening if RCS pressure is above system design pressure and should auto =atically close whenever RCS pressure exceeds system design pressure' 2
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-y 3.0 DISCUSSION AND EVALUATION There are three syste=s at Millstone 1, with direct interface to the RCS pressure boundary, which have a design pressure rating for all or part of the system which is lover than the RCS design pressure.
These systems are the Reactor Water Clean-Up (RWCU) system, Low Pres-sure Coolant Injection (LPCI) system, and Core Spray (CS) system.
3.1 Reactor Water Clean-Up System. The RWCU system takes suction on the RCS, cools the water by circulation throu;h regenerative and non-regenerative heat exchangers, and lovers the water pressure by the use of a pressure control valve. After passing through the low pres-l sure filter and clean-up portions of the system, the water is pumped at l
high pressure through the regenerative heat exchanger and back to the i
reactor via the f eed line. The section side of the system has three motor-operated isolation valves, an inboard valve, a pump suction valve, and a peop bypass valve. Isolation on the discharge side is provided by a MOV and a check valve. The MOVs cannot open if the pressure in the ' low pressure portions of the system is higher than its designed pressure. "They will automatically close on high RWCU system tempera-ture, lov flow, high 'RWCU' sys tem pressure, low reactor level, high f
dryve ll. pres s ure, or less of control power. However, the interlocks for these valves all use the same sensors and relays. Each MOV has position indication in the control room.
l Isolation provisions of the RWCU system do not meet the current licensing criteria since the interlocks for the isolation valves are f
not independent as required by BTP EICSB-3.
3.2 Low Pressure Coolant Injection System. The L?CI system takes l
s action on the suppiession pool (or condensate storage tank) and dis-charges into the reactor vessel. The discharge of each loop has two normally-closed MOVs which cannot be opened unless a LPCI system initi-ation signal is present and the RCS pressure is below the design pres-sure of the system. The valves vill automatically close if either the LPCI systen signal or RCS pressure increases above the LPCI system 3
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design pressure. Each valve has position indication in the control The LPCI system is in conformance with isolation provisions of room.
current licensing requirements.
3.3 Core Spray System. The CS system consists of two loops
'taking suction on the suppression pool and discharging into the reactor vessel through two MOVs (one normally open, the other normally closed) and a testable (air-operated) check valve per loop. All three valve positions are indicated in the control room. The normally-closed MOV vill only open upon a CS system initiation signal when RCS pressure has decreased below CS system design pressure. The MOV will automatically close upon clearing the initiation signal or increasing RCS pressure above CS system design pressure. Therefore,,the CS system meets the isolation criteria of current licensing requirements.
4.0 SUMHARY Millstone 1 has three systems with lower design pressure ratings than the RCS which are directly connected to the RCS. The LPCI and CS systems meet current licensing criteria contained in SRP 6.3 for isola-tion of high and low pressure sys tems. The RWCU system is not in com-pliance with BTP EICSB-3 since the isolation valve interlocks are not independent.
5.0 REFERENCES
l 1.
NUREG-075/087, Branch Technical Positions EICSB-3, RSB-5-1; Stan-i dard Review Plan 6.3.
2.
Millstone 1 Piping and Instrumentation Drawings 25202-26008,
-29119, -29128, and 29133.
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Millstone 1 Electrical Drawings 25202-31001-684, -684A, -685,
-686, -687, -745, -746, -773, -798, -858, -859, -863, -864, -868, and -869.
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SEP TECHNICAL EVALUATION t
INDEPENDENCE OF REDUNDANT ONSITE POWER SYSTEMS MILLSTONE NUCLEAR STATION, UNIT 1 Northeast Utilities December 1979 e
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CONTENTS
1.0 INTRODUCTION
1 2.0 CRITERIA 1
2.1 AC Supplies 1
2.2 DC Supplies 2
3.0 DISCUSSION AND E7ALUATION.
2 2
3.1 AC System 3
3.2 DC System 4.0
SUMMARY
4
5.0 REFERENCES
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TECENICAL EVALUATION INDEPEICENCE OF REDUNDANI ON3ITE POWER SYSTEMS EILLSTONE NUCLEAR STATION, UNIT 1
1.0 INTRODUCTION
The objective of this review is to determine if the onsite elec-crical power systems (AC and DC) are in compliance with current licen-sing criteria for e1~ectrical*i,ndependence between redundant standby (onsite) power sources and their distribution systems.
General Design Criterion 17 requires that the ensite electrical power supplies and their onsite distribution systees shall have suf-ficient independence to perform their safety function assuming a single failure.
Regulatory Guid? 1.6, " Independence Betwen Redundant Standby (Onsite) Power Sources and Between Their Distribution System," and IEIE Standard 308-1974, "IEEE St.ndard Criteria for Nuclear Power Gen-erating Stations" provide a basis acceptable to the NRC staff for meeting GDC 17 in regards to electrical independence of onsite power systems.
2.0 CRITERIA t
2.1 AC Supplies. When operating from standby sources, redundant load groups and redundant standby sex ces should be independent of each I
other at least to the following extent.
(1) The standby source of one load group should not be automatically paralleled with the standby source of another load group under accident conditions (2) No provisions should exist for automatically trans-s ferring one load group to another load group or i
loads between redundant power sources i
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2.2 DC Supplies. Each DC load group should be energized by a battery and battery charger. The battery-charger conbination should have no automatic co'anection'to any other redundant DC 1 cad group.
3.0 DISCUSSION AND EVALUATION 3.1 AC System. Millstone 1 energency AC power is provided by a gas turbine generator (GTG) and a diesel generator ( G's.
The GTG nor-mally supplies buses 7 and 1 upon loss of auxiliary ;over.
The DG normally supplies buses 5 and 6 which also supply buses 3 and 4, respec-tively.
Should the DG fail to supply power to buses 3 and 4, the GTG will automatica11y supply those buses via tie breakers f== bus 7.
The 7-3 and 7-4 tie breakers are electrical 1 ' interlocked'so that they 7
cannot be shut manually or automatically if the DG is supplying buses 3 or 4.
The 5-3 and 6-4 tie breakers cannot automatica1~.y close to pro-vide power from the DG if the GTG is supplying buses 3 and 4.
The DC output breakers to buses 5 and 6 cannot auto =aticall close if buses 5 and 6 are being supplied by the GTG frem buses 3 and 4.
Iewever, the 5-3 and 6-4 tie breakers are not interlocked to prevent =anua. closing of the breakers if the GTG is providing power to buses 3 :: 4 while the DG is supplying buses 5 or 6, respectively. Also, the DG output breakers are not interlocked to prevent manual closing of the breaker if the GTG is supplying buses 5 or 6.
Millstone 1 has four main 480 V AC buses, 1, LA. ~, and 1A, ' which are supplied by 416.0 buses 3, 4, 5, and 6, respective'.y. 3uses 1 and s
1A and 2 and 1A have tie breakers. There are electrital interlocks that prevent closing the tie breaker unless one of the =ain feeders for the two buses is open.
In order to close the = min feeder for either bus, the tie must be tripped.
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The 120 V AC vital bus is supplied by cn cuto=ati: transfs; d2vice receiving power fron either bus 2-5 or the vital co:r: genera:er set (vital MG). The MC is powered either from bus DC-1"1-3 :: bus 2-5.
Therefore, the autenatic transfer does not occur be:veen rede: dant sources of power. The 120 V AC instrument bus is supplied by an auto-i matic transfer device receiving power from bus 2-5 c bus 1A-3.
Buses 2A-5 and 2-5 nor= ally receive power from the D3.
Invever, they can be supplied by either th"e.DG, the GTG, or both. Is sace ases, they may be supplied from redundant sources and would, tigrafere, not be in compliance with the requirements for no automati: transfer of loads between redundant sources.
The reactor protec: ion buses 1 and 1A can be connected by shutting two manual breakers whi:h have ns inter-locks. The two buses are normally supplied from buses 2-5 and 2A-5, respectively. As with the instrument bus, these buses can be (but are not normally) supplied by redundant sources.
3.2 DC Sys tens. The Millstone 1 DC system co:sists of rvo 125 V batteries and their respective chargers, a standby :iarger capable of supplying either battery, and the DC distribution system.
The main DC buses, DC-1. and DC-1A, are powered from batteries 1 and 1A, respectively. The remaining buses are powered froc either bus DC-1 or DC-1A via an automatic transfer switch. Under norsal con-ditions, the buses DC-1 and DC-LA are supplied by chargers powered from buses 2-5 and 2A-5, respec:ively. As previously ca tioned, these buses are usually, but not always, powered by the same emergen:7 AC power supply.
In any case, loss of AC power results in the DC system being 1
supplied by redundant battery supplies. Therefore, :hs provisions for automatic transfer of power for buses DC-11A-1, DC-lil-2, and DC-IIA-3 is not in compliance with the requirements for no actesatic transfer of loads between redundant sources.
The ouput breakers of the s:andby charger are mechanically interlocked to 7tevent pare!~. sling of the two DC batteries and their buses.
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4.0
SUMMARY
The onsite energency AC system at Millstone 1 is not in compliance with current licensing criteria for independence of redundant onsite There are no interlocks preventing =anual paralleling power systens.
of the redundant AC source at the 5-3 and 6-4 tie breakers and r.t the DG. output breakers. The 120 V AC instrument bus is supplied 'oy an automatic transfer switch which can transfer loads between redundant sonrces in some cases. The reactor protection systen buses have no interlocks to prevent parallel operation when being supplied by redun-The DC system has three automatically transferred loads dant sources.
between redundant sources 'which are not in compliance with current licensing criteria.
5.0 REFERENCES
General Design Criterion 17, ',' Electrical Power System," of Appen-1.
dix A, " General Design Criteria of Nuclear Power Plants,',' to 10 CFR Part 50, Damastic Licensing of Production a-d Utilization Facilities."
" Independence Between Redundant Standby (Onsite) Power Sources and 2.
B'etween Their Distribution Systems," Regulatory Guide 1.6.
1 3.
Millstone 1 Drawings 25202-31001, Sheets 110, 1*1, 112, 130, 131, 271, 276, 291, 292, 300, 301, 311, 321, 322, 323, 324, and 605.
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1355F i
- l SEP TECHNICAL EVALUATION TOPIC VIII-3.3 DC POWER SYSTEM BUS VOLTAGE MONITORING AND ANNUNCIATION MILLSTONE UNIT 1 Docket No. 50-245 January 1980 1
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CONTENTS 1
1.0 INIRODUCTION..
1 D
2.0 CRITERIA.
2 3.0 DISCUSSION AND EVALUATION 3.1 Discussion 2
2 3.2 Evaluation 2
4.0
SUMMARY
3
5.0 REFERENCES
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SEP TECHNICAL EVALUAIION TOPIC VIII-3.3 DC PokT.R SYSTD( 3US VOLTAGE
.".ONITORING AND ANNUNCIATION MILLSTONI UNIT 1
1.0 INTRODUCTION
The objective of this review is to determine if the DC power sys-tem bus voltage menitoring and annunciation are in compliance with current licensing criteria for Class II DC power syscams.
The specific requirements for DC power system monitoring derive from the general requirements embodied in Sections 5.3.2(4), 5.3.3(5 ),
and 5.3.4(5) of IIII Standard 308-1974, and in Regulatory Guide 1.47.
In su=ary, these general requirements simply state that the DC system (batteries, distribution systems, and ch rgers) sha21 be nionitored to the extent that it is shown to be ready to perform ins intended function.
2.0 CRITERIA As a =inimum, the following indications and alarms of the Class II DC power syste=(s) status shall be provided in the control room:
l Battery current (a m atar-charge / discharge) e Battery charger output current (ameter) e DC bus voltage (voltmeter) e Battery charger output voltage (voltmeter) e l
Battery high discharge rate alarm l
e DC bus undervoltage and overvoltage alarm e
DC bus ground alarm (for ungrounded system)
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of abnormal conditions which are usually indicated locally).
3.0 DISCUSSION AND EVALUATION 3.1 Dis cussion. Two 125 V batteries, three 125 V battery chargers, two 125 V DC buses, four 24 V betteries, four 24 V battery chargers, and two 24 V DC buses ccmprise the Millstone Unit 1 Class IE DC power systems.
Control. room indication for the 125 V DC systems consists of bus voltage metering, bus undervoltage alarms, bus ground alarms, charger alarms, and bus parallel alarms; local indication con-sists of battery / bus voltmeters and anseters, charger output under/
overvoltage indicators and positive and negative ground voltmeters, and monitor lights. Control room indication for the 24 V DC system con-sists of " Battery / Charger Trouble" alarms; local indication consists of DC voltme' ers and ammeters.
3.2 Evaluation. The Millstone 1 control room has no indication of battery current, charger output current, bus voltage (24 V system),
l charger output voltage, bus undervoltage (24 V system) or overvoltage, l
bus ground (24 7 system), battery breaker / fuse status, or charger out-put breaker / fuse status. Therefore, the Millstone 1 DC power system monitoring is not in compliance with current licensing criteria.
4.0
SUMMARY
Of 11 paramer2rs currently required to be indicated or alarmed in the control room, only four are indicated or alarmed for the 125 V l
syste=s and one for the 24 V systems in the Millstone 1 control room.
Therefore, the Millstone Unit 1 DC power systems are not monitored in ec=pliance with current licensing criteria.
2
5.0 REFRENCES 1.
IEEE Standard 308-1974, " Standard Criteria for Class IE Powet Systens for Nuclear Power Generating Stations."
2.
Regulatory Guide 1.74, " Bypassed and Isoperable Status Indi-cation for Nuclear Power Plant Safety Systems."
3.
NRC Memorandum, PSB (Rosa) to SEPB (Crutchfield), "DC System Monitoring and Annunciation," dated October 16, 1979 4.
Letter, Connecticut Yankee Atomic Power Company (Counsil) to NRR (Ziemann), "SEP Topic VIII-3.5, DC Power System Bus Voltage Monitoring and Annunciation," dated August 29, 1979.
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