ML20215M327
| ML20215M327 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 10/22/1986 |
| From: | Papanic G YANKEE ATOMIC ELECTRIC CO. |
| To: | Mckenna E Office of Nuclear Reactor Regulation |
| References | |
| DCC-86-159, FYR-86-100, NUDOCS 8610300167 | |
| Download: ML20215M327 (5) | |
Text
-
YANKEE ATOMI6ELECTR10 COMPANY Tepho"e (6 ") & ' -"'oo TWX 710-380-7619 s.,
~
1671 Worcester Road, Framingham, Massachusetts 01701DCC 86-159 2.C2.1
/,e K I: e,, /
/ha October 22, 1986 FYR 86-100 United States Nuclear Regulatory Commission Washington, D. C. 20555 Attention:
Eileen M. McKenna, Project Manager Project Directorate #1 Division of PWR Licensing - A
References:
(a) License No. DPR-3 (Docket No. 50-29)
(b) USNRC letter to YAEC dated November 30, 1985 (c) YAEC letter to USNRC, dated June 30, 1986
Subject:
First Level Undervoltage Protection
Dear Ms. McKenna:
The enclosed attachment is in response to your recent request for additional information on our First Level Undervoltage Protection.
We trust you will find this information satisfactory however, should you desire additional information, please contact us.
Very truly yours, YANKEE ATOMIC ELECTRIC COMPANY 1
Q.
A George apanic, J.
Senior Project Engineer - Licensing GP/kaw Attachment 8610300167 861022 0
10 pek -
DR ADOCK 0500 9
g4'
ATTACHMENT 1 BACKGROUND In Reference (b), the USNRC approved the YAEC request for a change to the Yankee Nuclear Power Station Technical Specifications to modify the surveillance interval for testing of the second-level undervoltage (degraded grid voltage) protection from 18 months to monthly. To facilitate the testing, a circuitry change had been implemented via EDCR 84-325 during the 1985 refueling outage.
In the same Reference (b), USNRC stated that:
(1) additional modifications to the Technical Specifications are still necessary to address the loss of first-level undervoltage protection, and (11) the proposed change to address this modification should include documentation of the existing relay's reliability.
In response to Reference (b), YAEC issued Reference (c) which presented:
(a) evidence demonstrating the high reliability of the Westinghouse Type CV-7 undervoltage relays, based on the available maintenance history since 1975 (b) a description of the plant's unique Electrical System design, which features three safety divisions with only two divisions required for safe shutdown of the plant under the design basis accident, and (c) YAEC's position on simplicity of system design, which emphasized that the modifications to permit on-line testing of the first-level undervoltage protection is complex, and could reduce reliability.
This attachment is in response to a recent NRC question regarding the complexity of the modification required for the installation and wiring of testing equipment necessary to meet NRC requirements for monthly testing of the first undervoltage protection.
The following will describe the actual arrangement of the first undervoltage protection relays, the equipment needed for relay testing, and the difficulties associated with the implementation of the NRC requirements for monthly testing of these relays.
DISCUSSION 1.
Present Relay Arrangement The first-level undervoltage protection consists of one Westinghouse Type CV-7 electromagnetic induction disc relay on each of the three 480 volt emergency busses. These relays are installed on the rear of the Safety Injection Panel (SIP) as shown in Enclosure (A).
. _D
i ATTACHMENT 1 (Continued)
The relays are installed at the top of the rear panel, between the second-level degraded grid undervoltage relays and their associated testinr, equipment and the group of relaya associated with the emergency diesel generator's protection and con >rol.
4 As shown on the rear view,-the SIP.ccommodates in addition to the subject relays, numerous instrumentation and control equipment, plastic wire ducts, terminal blocks, wiring, and hardware. The inside rear of j
the SIP is completely utilized, except for two narrow free-equipment areas divided by a vertical plastic wire duct. These areas, 9" by 17" and 7" by 24", approximately, are crossed by wire bundles used for all relays and instrumentation connections.
2.
Testina Equipment l
Similar to the existing testing circuitry installed for the second level undervoltage protection, the following fixed testing equipment would be needed for the first-level undervoltage protection testing:
3 - variacs 0-120 volt 3 - 12 deck test switches 3 - fuse holders for variac protection 3 - auxiliary relays l
12 - plugs, for connection of a portable counter and meters to the fixed testing equipment 2 - metal barrier for train separation 100 - terminal points The use of portable testing equipment for CV-7 relay testing has been rejected, since it would interfere with the relay's internal parts, and will inherently lead to relay damage and loss of operational reliability.
In addition, the use of portable equipment temporarily wired to CV-7 l
relays, may cause human errors, such as relay internal test switches lef t open or not properly closed.
l 3.
Problems Related to the Installation of Testing Equipment Based on the CV-7 relay arrangement on the rear of the SIP and the
{
testing equipment needed in order to meet NRC requirements, the following j
problems became evident:
There is no available space to accommodate the testing equipment for the first-level undervoltage protection relays. The two j
equipment-free areas mentioned above are unsuitable in terms of space required for testing equipment, wiring, terminal points, and separation barriers, i
l
ATTACHMENT 1 (Continued)
Furthermore, the existing wires which service 16 relays and other equipment, and cross the free areas, would have to be removed and replaced with new wires rerouted around the separation barriers.
Except the right side of the SIP (facing the front), which is free of equipment, all areas inside and outside, SIP are fully utilized.
The right side of the SIP may accommodate all testing equipment but presents the following problems:
(a) a person performing the testing will not be able to see the relay being tested, and (b) the wiring to be installed between CV-7 relays and the testing equipment would have to cross the second undervoltage protection panel, interfering with its wiring and separation.
For these reasons, we believe that the right side of SIP is inadequate for testing equipment mounting.
+
CONCLUSIONS Based on the above discussion, we have concluded that the installation of testing equipment cannot be properly accomplished, and could reduce the reliability due to the physical interference with other equipment and circuitries.
OVERSIZE DOCUMENT PAGE PULLED SEE APERTURE CARDS NUMBER OF PAGES:
ACCESSION NUMBER (S):
h / O S O O/(o7-o/
APERTURE CARD /HARD COPY AVAILABLE FROM RECORD SERVICES BRANCH,TIDC FTS 492 = 8989 w
>