ML19340C251
| ML19340C251 | |
| Person / Time | |
|---|---|
| Site: | Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png |
| Issue date: | 11/07/1980 |
| From: | Counsil W CONNECTICUT YANKEE ATOMIC POWER CO. |
| To: | Crutchfield D Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML19340C252 | List: |
| References | |
| TASK-06-07.B, TASK-06-07.C, TASK-06-10.A, TASK-07-03, TASK-08-02, TASK-08-03, TASK-6-7.B, TASK-RR NUDOCS 8011140349 | |
| Download: ML19340C251 (3) | |
Text
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3 TES November 7, 1980 Docket No. 50-213 A01217 Director of Nuclear Reactor Regulation Attn:
Mr. Dennis M. Crutchfield, Chief Operating Reactors Branch #5 U. S. Nuclear Regulatory Commission Washington, D.C.
20555
Reference:
(1)
D. M. Crutchfield letter to W. G. Counsil dated September 16, 1980.
Gentlemen:
Haddam Neck Plant SEP Topics VI-7.B, VI-7.C, VI-10, VII-3, VIII-2, and VIII-3 In Reference (1), the NRC requested additional information on the subject SEP topics, concerning the operation of the inverters supplying vital AC at Connecticut Yankee Atomic Power Company's (CYAPCO) Haddam Neck Plant.
The following information is submitted in response to that request.
Question 1 Quantify the number of instrument invertere in your plant and for each inverter:
a)
Identify the inverter and its pcwer supplies; and b) Describe the switching features that are provided to switch inverter power supplies and inverter loads (including synchronization circuits).
Response
a)
Inverters A and B are supplied by 125 VDC Bus 1.
Inverters C and D are supplied by 125 VDC Bus 2.
Refer to Drawing No. 16103-30055, Sheet 1, for a one-line diagram of the inverter system.
b) All switching of inverter supplies and loads is accomplished manually with no paralleling of inverters.
0011140 }
Question 2 Provide requirements for:
a) Testing the transfer paths described in your Response to Question 1 above, and b) Limiting the number of redundant load groups that may be placed on any mainten- :e power source during each operating condition
Response
No testing is done since no transfer paths (other than manual switching) a)
exist.
Each load group has the capability of being switched from its normal source b) to one alternate source via the permanent connections illustrated in the one-line diagram (Drawing No. 16103-30055, Sheet 1).
For example, Load Group A is normally supplied by Inverter A, but may use Inverter C as an alternate supply. No provisions exist by which more than two load groups can be connected to a single inverter. Also, because of the mechanical interlock, one load group cannot be connected to more than one inverter.
Question 3 Describe the consequence of one or more load groups on a single DC source losing power (e.g., automatic initiation of ECCS, automatic initiation of transfer from ECCS injection mode to recirculation mode, loss of indication loss of annunciators, loss of plant communications, loss in the control room, of emergency telephones).
Response
The loss of one inverter would cause the loss of one of four channels of indication on the main control board, and arming of one channel of degraded voltage protection, nuclear instrumentation, reactor control, reactor protection, and pressure The result of arming one channel of most of these functions monitoring systems.
would be an alarm. Arming of one channel of the power range monitoring will block withdrawal of control rods. For power operation above 84%, a signal indicating loss of coolant flow (loss ot una channel out of four) will initicte a reactor trip.
The loss of both inverters on the same battery will cause the loss of two out of the four channels of indication on the main control board and the arming of two of the three or four channels (depending on the system) of degraded This will cause a reactor voltage protection and pressure monitoring systems.
trip, initiation of safety injection, diesel start and operation of the safety injo ; ion loads on the diesels rather than the offsite power supplies.
Anytime Inverter D is lost, the Containment Evacuation Siren and the plant Emergency Telephones will be lost.
The Haddam *!eck Plant has no automatic transfer from ECCS injection mode to recircul? tion mode.
CYAPCO trusts that this information is responsive to th Staff's request.
Very truly yours, CONNECTICUT YANKEE ATOMIC POWER COMPANY J'
ML/rik W. G. Counsil Senior Vice President Attachment
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