ML20137F782
| ML20137F782 | |
| Person / Time | |
|---|---|
| Site: | Wolf Creek  |
| Issue date: | 08/12/1985 |
| From: | Koester G KANSAS GAS & ELECTRIC CO. |
| To: | Denise R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| References | |
| KMLNRC-85-197, NUDOCS 8508270081 | |
| Download: ML20137F782 (3) | |
Text
'
KANSAS GAS AND ELECTRIC COMPANY CLENN L NOESTER vect Passiotar-muct ama August 12, 1985 g gji
< 1 7 --
,1 AUG 161985 Mr. R.P. Denise, Director j
Division of Reactor Safety and Projects O.S. Nticlear Regulatory Comission Region IV 611 Ryan Plaza Drive, Suite 1000 Arlington, Texas 76011 KMLNRC 85-197 Re:
Docket No. 50-482 Subj: Supplemental Information Regarding Non-Environmentally Qualified Terminal Blocks
Dear Mr. Denise:
The purpose of this letter is to provide information regarding terminal blocks which are not environmentally qualified for the installed a5 plication.
The subject terminal blocks were installed in Main Steam Isolation Valve (MSIV) and Main Feedwater Isolation Valve (MFIV) electrical connection boxes.
The use of the installed tern.inal blocks, when conbined with conpensatory action in the event of a steam line break in the area, provides assurance that the affected valves will perform their intended safety function and the health and safety of the public is not affected.
The terminal blocks in question are NU2 blocks manufactured by Connectron Incorporated and supplied to Wolf Creek by Anchor / Darling Valve Conpany.
Model EU2 terminal blocks are environmentally qualified for both a high tenperature application and a low tenperature application.
The terminal blocks for high tenperature applications are nade of a polysulphono material and are opaque and light tan in color. For low tenperature applications terminal blocks are made of polyamide (nylon) and are transluscent white in color.
Each type has a distinct Anchor / Darling part nunber.
The tan polysulphono terminal block part nunber is W32676.
The white nylon terminal block part nunber is W30164.
8508270081 850812 l
PDR ADOCK 05000482
&s93a h '/' 3 201 N. Market - WicNta Kansas -Mail Address: PO. Box 208 I %7ctuta. Kansas 67201 - Telephone: Area code (316) 261-6451
4 Mr. R.P. Denise August 12, 1985 KM mRC 85-197 The subject terminal blocks were ordered in a lot of 16 by Bechtel Power Corporation from Anchor / Darling Valve Conpany on 05/31/84.
The correct part number for the polysulphono blocks (W32676) was specified on the purchase order.
The 16 blocks were received on 08/09/84.
Included in the receiving records is a KG&E Receiving Inspection Report which documents that the identification and narkings for the terminal block package received was consistant with what was ordered.
In this case, the part nunber is not identified on each individual terminal block but identification which is included in the bag containing the terminal blocks. Also included in the receiving records are the packing list from Anchor / Darling,a Certificate of Conformance from Anchor / Darling, and Anchor / Darling verification of conformance with the purchase specification.
Each of these documents specifies part nunber W32676 for the terminal blocks.
Terminal blocks from this lot were withdrawn on three occasions.
Six blocks were removed from stores on 12/07/84 and installed in MPIV AE-FV-42.
Four blocks were removed from stores on 12/08/84 and installed in MFIV AE-FV-39.
Four blocks were removed from stores on 07/31/85 and installed in MSIV AB-HV-14.
Events which lead to the current situation on a MSIV and a FWIV began during a refurbishing effort on these valves in Decenber 1984 in which a total of 10 damaged terminal blocks were removed and replaced on two MPIV's.
During the same time, Bechtel was asked to clarify the difference between the two types of NU2 terminal blocks which were installed in various applications in the field.
Bechtel responded by explaining that the tan polysulphono terminal blocks were environmentally qualified for the high tenperature environment of the MSIV's and MFIV's and the white nylon terminal blocks were qualified for other normal applications.
The replacement terminal blocks used in the MFIV's were the unqualified white nylon terminal blocks.
The difference was not discovered at the time and the valves were put back into service.
In July 1985, the engineering group was asked to investigate a damagad terminal block found in a MSIV terminal box.
During this investigation, the unqualified terminal blocks were discovered.
94aagmmt surveys revealed a total of 14 installed unqualified nylon terminal blocks in the MSIV and MFIV terminal boxes.
Four nylon terminal blocks were installed in MSIV AB-HV-14, stan&y train; four were installed in MFIV AE-FV-39; four were installed in the stanty train and two were installed in the active train of FWIV AE-FV-42. Since both trains were affected on MFIV AE-FV-42, these were replaced with available polysulphono spare blocks on 08/08/85.
Replacement blocks for the other valves are on order and they will be installed at the first outage, but no later than the shutdown from the plant trip from 100% power startup test.
Mr. R.P. Denise August 12, 1985 KMLNRC 85-197 An evaluation was conducted to investigate the consequences of a steam line break accident in the MSIV/MFIV area with the unqualified terminal block installed in MSIV AB-HV-14 and MFIV AE-FV-42.
It is assumed that all the MSIV's and MPIV's close as designed in the initial part of the accident.
The circuitry on MSIV AB-HV-14 is such that if the terminal blocks in question were to fail, the valve would fail as-is in all cases.
MFIV AE-FV-42 could open again, however, only with a specific failed hot-short configuration. This could be prevented if power is removed from the terminal box by pulling the control power fuses.
In the interim period until the terminal blocks are replaced, an Operational Aid (Informational Posting) is in place to pull the control power fuses in the event of a steam line break in that area.
This evaluation concluded that for the short term the unqualified terminal blocks could remain installed and operation could continue without undue risk to the health and safety of the public. The major factors which lead to that conclusion are as follows:
The nylon terminal blocks are installed in the standby train of both the MFIV and the MSIV.
The valves will still perform their safety function.
The steam line and feedwater line piping in the MSIV/MFIV area is of the " super pipe design",i.e.
designed to the no-break zone criteria as defined in Section 3.6 of the FSAR.
The probability of a steam line break accident prior to the next outage is extremely low.
Tenporary procedures are in place to remove power from the affected cabinets in the event of a steamline break accident.
If you have any questions concerning this matter, please contact me or Mr. Otto L. Maynard of my staff.
Yours very truly, A Glenn L. Koester Vice Presidert, Nuclear i
cc: PO'Connor (2)
JCumins I
--_.-y 7
,