ML19309D608
| ML19309D608 | |
| Person / Time | |
|---|---|
| Site: | Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png |
| Issue date: | 03/03/1980 |
| From: | Counsil W, Fee W CONNECTICUT YANKEE ATOMIC POWER CO. |
| To: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| IEB-79-27, NUDOCS 8004110012 | |
| Download: ML19309D608 (2) | |
Text
.
fn CONNECTICUT YANKEE ATOMIC POWER COMPANY BERLIN. C O N N E CTIC U T P O BOR 270 H ARTFORD. CONNECTICUT Ottol ts6 s eseo=a 203 666-6911 March 3, 1980 Docket No. 50-213 Mr. Boyce H. Grier, Director Region I Office of Inspection and Enforcement U. S. Nuclear Regulatory Co= mission 631 Park Avenue King of Prussia, PA 19406
Reference:
(1) I&E Bulletin No. 79-27, dated November 30, 1979 Gentlemen:
Haddam Neck Plant Loss of Non-Class lE Instrumentation and Control Power Supuly Bus During Operation As requested by Reference u.), Connecticut Yankee Atomic Power Company (CYAPCO) has reviewed the Class lE and Non-Class lE buses supplying power to safety and non-safety-related instrumentation and control systems which could affect the ability to achieve a cold shutdown condition.
In response to Item la, Alarms or Indication to Alert the Operators of Loss of Power to Each Bus, the Haddam Neck Plant has two (2) semi-vital buses with either of two (2) feeds via an automatic transfer and backed up by either of two (2) emergency diesel generators. There are four (4) vital buses fed by four (4) inverters which are supplied by two (2) station batteries.
Loss of the semi-vital buses' supply is annunciated on the main control board.
Actual semi-vital bus voltage is indicated on the back of the main control board.
In addition, various instrument channels vould alarm simultaneously, directly indicating loss of the supporting semi-vital bus.
Loss of any single vital bus is directly annunciated on the main control board. Actual vital bus voltage indication is available en the back of the main control board.
With power lost to one vital bus, channel trips occur in associated Reactor Protection and Engineered Safeguard Acutation Systems.
8004110 eq
l t
< i i
All of the instrument and control systems loads on the various buses have been identified and evaluated as to the effect of loss of the entire bus on the ability to achieve cold shutdown (Item lb).
Existing emergency procedures, i
including those to achieve cold shutdown, indicate there would be no problem l
vith regard to instrumentation on the loss of one of the four vital buses because of redundant instrumentation 'and controls.
l Loss of all semi-vital bus power would deprive the operator of all instrumenta-tion normally used to achieve a cold shutdown using normal operating procedures.
No design nodifications (Item Ic) are necessary as a result of this investiga-i tion.
Instead, CYAPC0 vill prepare new abnormal operating procedures (Item 2) to allow the operators to achieve cold shutdown utilizing local indications.
The new procedures are expected to be completed by June 1, 1980.
The reference bulletin also requests (Item 3) that CYAPCO review IE Circular No. 79-02, Failure of 120 Volt Vital AC Power Supplies, to include both Class lE and Non-Class lE power supply inverters and describe any proposed design modifications or administrative controls to be implemented as a result of this review.
The existing vital AC Inverter Systems at the Haddam Neck Plant are not of the same design philosophy as that described in IE Circular No. 79-02.
The inverters at the Haddam Neck Plant have DC input only.
The alternate source for a vital bus is another inverter, and transfer to the alternate source is a manual operation.
j Thus, the four concerns identified in IE Circular No. 79-02 are not applicable to the Haddam Neck Plant.
We trust this information is responsive to the Staff's requests.
l Very truly yours, CONNECTICUT YANKEE ATOMIC POWER COMPANY h.
d 'W W. GVCounsil Vice President 2
By:
W. F. Fee Vice President
)
J d
eg r*
---