ML19347E510
| ML19347E510 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 05/07/1981 |
| From: | Kay J YANKEE ATOMIC ELECTRIC CO. |
| To: | Crutchfield D Office of Nuclear Reactor Regulation |
| References | |
| FYR-81-74, IEB-80-06, IEB-80-6, NUDOCS 8105110218 | |
| Download: ML19347E510 (3) | |
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" $_ ANKEE ATOMIC ELECTRIC COMPANY e
f 1671 Worcester Road, framingham, Massothusetts 01701 2.C.2.1 Y
e ANKEE FYR 81-74 May 7, 1981 f
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U.S. Nucicar Regulatory Commiesion C
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.g Washington, D. C.
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Attention:
Mr. Dennis M. Crutchfield, Chief Operating Reactors Brauch #5 4
N Division of Licensing V,;.%&
Ref ere nces: (a) License No. DPR-3 (Docket No. 50-29)
(b) USNRC Letter to YAEC dated March 28, 1981 (c) USNRC Letter to YAEC dated March 13, 1980 Su bject: Additional Information on Engineered Safety Feature Reset Controls (1E Bulletin 80-06)
Dear Sir:
e In response to your request in Reference (b), the following discussions are p rovDied. This information will document our previous phone discussions and provides additional information in response to Reference (c).
Item 1 (a, b, c)
The proper operation of the Containment Isolation valves ensures that the containment atmosphere will be isolated from the outside environment in the event of an overpressurization of the containment.
The Containment Isolation System is a redundant system in which no single failure will prevent an isolation valve f rom operating. Each isolation valve is controlled by two independent actuation devices; operation of either device will cause isolation.
Electrical and physical separation is maintained throughout by the routing of electrical systemt:, and power sources.
Two power supplies. have been incorporated into the design of each train; Station Battery #3 is ased for one train, while Station Battery #1 is used for the second train.
Incorporated into the design of the Containment Isolation System is the provision for testing each isolation trip valve individually. Each of the re dund ant trains has a specific test switch for each isolation valve. When the switch is in the " TEST" position, the selected isolat. ion valve will be operated (closed). One of the prime purposes of this function is to accommodate the operational testing of these isolation valves; specifically, to test the operating time as required in Technical Specifications.
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U S. Nuclear Regulatory Commission Ely 7.'1981 Attention:
Mr. Dennis M. Crutchfield, Chief Page 2 The " BYPASS" function is another feature of this system. When in the " BYPASS" mode, the isolation valve, if already -in a tripped position, would be returned to its normal (open) position.
This is an operational requirement for specific isolation valves. By design, it has a protective feature which would require that the specific'" BYPASS" switch f rom both trains be in the " BYPASS" position before the isolation valve would open. This is a' safety consideration to prevent accidental opening of a tripped isolation valve by only a single operation. Administratively controlled and keylocked cabinets which contain switches w'11 prevent inadvertent opening of these valves.
When any isolation valve is put. into the " TEST" or " BYPASS" mode by use of the switches, the operator is automatically alerted to an off-normal condition by the annunciator system.
The annunciator indication remains for as long as any switch is in the " TEST" or " BYPASS" mode.
Also, initiation of the Containment 1sclation System by either or both trains will cause annunciation and indication on the Main Control Board.
An additional feature of the system design r' elates to the advantage of paving -
status indicator lights for each actuation train.
These are located on the front of the Main Control Board adjacent to the manual CIS trip switches.
These indicators give the operator immediate awareness of the integrity of the Containment Isolation Systems by monitoring the initiating coil continuity.
There are 3 modes by which CIS initiation can occur, (1) Manual, (2) Containment Pressure, (3) Safety Injection Actuation (Iow main coolant system pressure or high containment pressure - only non-essential valves)..
(1) Manual A manual trip function of the Containment Isolation System is one rethod of initiating containment isolation. Two pushbutton switches, ecch one located in a separate area of the Main Control Board, provide this capability. One is located on Section 1 of the Main Control Board, and the other on Section 5 of the Main Control Board.
Either pushbutton switch can initiate Containment Isolation.
(2) High Containment Pressure High containment pressure would be sensed by pressure switches, one for each of the redundant systems. High containment pressure would close contacts in the actuating and seal-in circuits of the system. Actuation by high containment pressure will trip all CIS isolation valves.
(3)
Diverse Parameter (Saf ety Injection Actuation System)
Initiation.of SIAS system would close all non essential valves of the Containment Isolation System. SIAS is initiated by either low main coolant system preesure or high containment pressure.
Attached Figure 3 indicates the primary circuitry for the Containment Isolation System.
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3 c4 U S.; Nuclear Regulatory Commission May.7, 1981
- Attention:
Mr. Dennis M. Crutchfield, Chief Page 3
, Item 2 Under the present configuration, operation of the charging pump control circuits under accident conditions is as follows:
The SIS Initiation Signal trips a lockout relay, the lockout relay trips an auxiliary relay which seals itself in and als) trips its related charging pump..To reset the circuit, it is vecessary for the following to occur:
1)
Th'e SIS Signal must be removed.
2)
The lockout relay must be manually reset.
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3)
All three charging pump control switches to be placed in the trip l
position.
Af ter the above three actions have been completed, it is possible for the operator-to turn on any of the three charging pumps as desired.
.See Figure 1.
Item 3 The Lfollowing is. a description of the Safety Injection Accumulator bitrogen l
Valve Solenoid Operating Valve Control Circuit under accident conditions:
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Upon receipt of an SlS Actuation Signal, a lockout relay is tripped.
This relay energizes a pair of -time-delay on pickup relays. After the appropriate time, both the time-delay relays energize the Solenoid Operated Valve i
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(electrically operated) to open it.
To reset this circuit'it is necessary for l
. the following to occur:
1)
The SIS Signal must be removed.
2)
The lockout relay must be manually reset.
3)
There is a spring-return pushbutton switch for each Sole noid Operated Valve. Pushing this button switch will cause the Solenoid Operated Valve to go closed.
See Figure 2.
f We trust the above information is satisfactory; however, if you have any additional questions, please contact us.
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Very truly yours, l
YANKEE ATOMIC ELECTRIC COMPANY
. 0 J. A. Kay I
Senior Engineer - Licensing At tac hme nt
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