ML20010B267
| ML20010B267 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 08/07/1981 |
| From: | Kay J YANKEE ATOMIC ELECTRIC CO. |
| To: | Crutchfield D Office of Nuclear Reactor Regulation |
| References | |
| TASK-07-01.A, TASK-07-02, TASK-7-1.A, TASK-7-2, TASK-RR FYR-81-119, NUDOCS 8108140292 | |
| Download: ML20010B267 (5) | |
Text
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YANKEE ATO 10 ELECTRIC COMPANY
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1671 Worcester Road, framingham, Massachusetts 01701 1 119
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August 7, 1981
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United States Nuclear Regulatory Commission b
Washington, D.C. 20555 97 AUG 1. 519815 2 Attention:
Mr. Dennis M. Crutchfield, Chief
- d7 Operating Reactors Branch #5 b
d Division of Licensing Ob 9
References:
(a) License No. DPR-3 (Docket No. 50-29)
(b) UShTC Letter to YAEC dated April 23, 1981 (c) YAEC Letter to USNRC dated June 5, 1981 (FYR 81-84)
Subject:
RAI for SEP Topics VII-1. A and VII-2
Dear Sir:
This letter provides the information requested by Reference (b). This information describes the degree of isolation between the Reactor Trip System, the ESF System and non-safety control systems. The requested drawings were supplied in Reference (c).
We trust this information is satisfactory; however, if you have any questions or desire additional information, please contact us.
Very truly yours, YANKEE ATOMIC ELECTRIC COMPANY
. A. Kay Senior Engineer - Licensing JAK/sec 8
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8108140292 810807 PDR ADOCK 05000029 p
ENCLOSURE Response to Request For Additional Information on Yankee Rowe For SEP Topics VII-1A & VII-2.
In response to your request for additional information concerning the degree of isolation between the Reactor Trip System, the ESF System and non-safety control systems, we are providing the following additional Information.
1.
Analog protection signals from RPS channels to process recorders and remote indicating meters are provided in most cases via current sensing resistors or/and isolation resistors. These resistors help to minimize the effects on the protection channels of open or short circufts at the recorders or meters.
In other cases indicators and recorders are an integral part of the current loop.
In all cases the indicators and recorders are located on control panels within the main control room and are under the observation of the control room operators.
The charging pump control system is a pneumatic control system which operates from a narrow range pressurizer level channel signal via electro pneumatic trane'ucer. The narrow range pressurizer level channel is not a protection channel and therefore isolation is not required.
2.
Isolation buffer devices are being installed and will be used for analog protection signal inputs to the Safety Parameter Display System (SPDS).
These isolation devices are manufactured by the Technology For Energy Corporation (TEC) of Knoxville, Tennessee.
The qualified isolation voltage is 1000 vde or 480 vac.
The isolation system has been type tested according to guidelines set forth in IEEE-323-1974, IEEE-344-1975 and IEEE-381-1977. A schematic diagram, TEC drawing 156D1003 is provided separately for your information.
Digital signals which are used for alarms, indication and control functions are isolated from the RPS analog and ESF digital signals through relay contacts. Schematics of these arrangements have been provided as indicated below.
3.
Our letter FYR 81-84 dated June 5, 1981 transmitted the requested electrical schematics and elementary drawings for each of the systems you listed.
As a supplement to the information discussed above, brief summaries are provided below to describe the Nuclear Instrumentation Channels, Primary-Plant Instrumentation channels, the various other parameters which generate a reactor trip, and the ESF protection channels.
3.1 The Nuclear Instrumentation (NI) Channels provide trip signals to the Reactor Protection System. The following is a description of the ten NI channels:
3.1.1 Two source range and two intermediate range channels provide start-up rate trip signals to the alarm and scram panel via trip bistables (the source range trip signal is permanently bypassed through the administrative control of a cutout switch). These channels also provide log level and rate
e signals to local and remote meters and remote recorder (level only) through isolation resistors. Rate signals from these channels operate relays in the Start-up and Power Range Auxiliary Panel (SURAP). Contacts from these relays are used for a start-up rate alarm (associated with all four channels) and rod stop control and indication, and a scram alarm (associated with the intermediate range channels). Log level signals from the intermediate channels also operate relays in the SURAP. Contacts from these relays provide high voltage cutout control and indication to the source range channels.
3.1.2 Three intermediate power range and three power range channels 4 provide power level trip signals to the alarm and scram panel via trip bistables and single-coincidence circuits. These channels also provide power level signals to local and remote meters and remote recorder (power range channels only) through isolation resistors. Signals from these channels operate relays in the SURAP (for power range) and Intermediate Range Auxiliary Panel (IRAP). Contacts from these relays are used for a power level alarm.
3.1.3 Signals from the NI channels will be provided for the SPDS via TEC analog signal isolators.
3.2 Several Primary Plant Instrumentation channels provide trip signals to the Reactor Protection System.' The following is a description of these channels.
3.2.1 Three main coolant pressure channels provide high and low pressure trip signals to the reactor trip switchgear via channel bistables, which operate channel relays and two trains of trip relays.
In the same fashion, these channels also provide permissive signals which are used in the Non-Return Valve (NRV) automatic trip-block logic.
Contacts from the channel relays and trip relays also provide channel trip and reactor trip alarms. Each channel incorporates an indicator which is part of the signal loop.
In adCition, each loop will l
provide a signal for the SPDS via TEC analog signal isolators.
One main coolant pressure channel also incorporates the following functions. A low pressure signal is provided via l
bistable and relay to initiate actuation of one safety injection train.
This channel is also provided with a signal repeator/ isolator which drives high and low pressure alarms via bistable contacts, a remote indicator, and a recorder input.
l 3.2.2 The wide range pressurizer level channel provides' a high level trip signal to the alarm and scrsm panel via trip bistable.
This channel also provides a signal directly to a recorder via current sensing resistor and to a remote meter through current sensing and isolation resistors.
In addition to the trip l
bistable, another bistable and associated relay are operated from this channel. A contact from this relay is used for a low l
level alarm.
l.
e Provisions are made for this channel to drive the narrow range pressurizer level control channel through an amplifier and selector switch. This feature allows the narrow range channel to operate from the wide range channel if the narrow range transmitter becomes inoperable. These channels are isolated from each other through contacts of the selector-switch.
3.2.3 '
Four main coolant flow channels (steam generator A P) provide a low flow trip signal to the alarm and scram panel via trip bistable. This trip bistable operates whenever two of the-four channel alarm bistables have operated. Each of the four alarm bistables operate an associated relay. Contacts from these relays provide low flow alarms. Each of these channels also provide a signal directly to a recorder via current sensing resistor and to a remote meter through current sensing and isolation resistors.
3.3 The Reactor Protection System receives trip signals which are generated from various other parameters.
The following is a description of these-channels:
3.3.1 Four main coolant flow channels (reactor coolant pump motor current) provide a low flow trip signal to the reactor trip switchgear via two sets of four channel relays and two sets of train relay logic. Channel relays are operated by undercurrent and overcurrent relays which monitor pump motor current.
Contacts from the channel relays are used for alarm and indicating light purposes as well as for train relay logic.
Contacts from logic relays are used to trip the reactor trip switchgear.
1 3.3.2 Four narrow range steam generator level channels provide a. low level trip signal to the alarm and scram panel via trip bistables. The trip bistable contacts are combined to produce-a 2 out of 4 trip logic. A remote indicator and local indicating meter relay are also incorporated in each channel signal loop. Contacts from the meter relsys provide high and low level alarms.
3.3.3 Several main generator protection channels also provide trip signals to the reactor trip switchgear via auxiliary relays.
These auxiliary relsys are operated by protective relays which monitor stuck breaker on either high line, generator differential, generator ground, unit differential, generator overcurrent, generat r loss of field, No. I station service transformer differe.cial,, No. I station service transformer overcurrent, and No. 4~ station service transformer overcurrent. Contacts from these auxiliary relays also provide the following' generator protection functions: trips and locks out the main generator exciter breaker, trips and locks out the No. 4 station service transformer breaker, trips the main transformer breakers and trips the No. I station service transformer breaker.
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F 3.3.4
.A turbine trip cign:1 10 providId to trip tha rascter trip.
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switchgear via ' auxiliary relay.
This relay is operated by
, limit switches which monitor the position of the turbine control ~and throttle valves.
Contacts from this auxiliary relay are also used to trip the high line breakers.
3.4 The following descriptions are for prote'etion channels and trains associated with the ESF systems: - The act u ation channels for these 7
systems are initiated by pressure switches (with the exception of one Safety. Injection train which is initiated via a bistable - as discussed in section 3.2.1).
3.4.1 The Safety Injection System consists of two redundant trains.
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Each train is actuated by contacts of lockout relays which operate upon receipt of a high containment pressure signal or low main coolant oressure signal.- In addition to initiating the protection ianctions associated with the safety injection system, contacts from the lockout relays niso operate diverse function relays in the containment isolation system (CIS).
Contacts from the diverse function relays then operate a diverse function lockout relay in each train of CIS.-
Contacts l-from these lockout relays then initiate closure of non-essential CIS valves.
Contacts from the lockout relays are f
used for alarm purposes.
I 3.4.2 The containment isolation system also consists of two redundant j
trains.which' operate on high containment pressure similar to those described for the safety injection system. Contacts from
'the CIS lockout relays initiate closure of the CIS valves.
Contacts from the lockout relays are also used for alarm purposes.
In addition a contact from one of the lockout relays is used (in conjunction with the NRV logic) as a permissive to trip the condensate pumps. The CIS lockot relays are operated l
via auxiliery relay contacts. - 2 contact from each auxiliar/
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relay is also used in the NRV trip logic to close the NRV's and i.
trip the reactor.
i 3.4.3 The main steam isolation system incorporates a design to automatically close the NRVs and trip the reactor and turbine.
Three pressure switch channels monitor the steam line pressure i
in each of the four main steam lines. Each pressure switch operates a pair of channel relays which provide contacts for two trains of logic and for alarms and indication.
An intermediate relay in each train is actuated en a 2 out of 3 Iow steam'line pressure signal in any one steam line. Contacts from these relays then operate the trip relays in the respective trains. An additional contact from one of the intermediate relays is used with a CIS signal (as diccussed above) to trip the condenaate pumps. - The trip relays in each train of trip logic 'also operate from a CIS high containment pressure signal and provide contacts for closing the NRV's, tripping the reactor and turbine and for alarms and indication.
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