ML18139B062
| ML18139B062 | |
| Person / Time | |
|---|---|
| Site: | Surry, North Anna  |
| Issue date: | 01/23/1981 |
| From: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | Ferguson J VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| References | |
| NUDOCS 8102190557 | |
| Download: ML18139B062 (6) | |
Text
e e
UNITED STATES NUCLEAR REGULATORY COMMISSION REGION II In Reply Refer RII:JPO To:
50-338,. 50-339 50-404: 50-405
<;;2'0-280_ 50-28] _:::::::>
101 MARIETTA ST., N.W., SUITE 3100 ATLANTA, GEORGIA 30303 JAN 2 3 1981 Virginia Electric and Power Company ATTN: J. H. Ferguson Executive Vice President-Power P. 0. Box 26666 Richmond, VA 23261 Gentlemen:
U,S, NUCLEAR REQlAATOf;Y
, [
COMMISSION
.. \\*.:;*~'
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The enclosed IE Circular No. 81-01 contains recommendations that may be applicable to your facility with regard to design problems associated with the subject indicating pushbotton switches. Should you have any questions regarding this circular or the recommendations contained therein, please _contact this
.office.
Sincerely, Director
Enclosures:
- 1.
IE Circular No. 81-01
- 2.
List of Recently issued IE Circulars cc w/encl:
W.R. Cartwright, Station Manager P. G. Perry, Senior Resident Engineer J. L.* Wilson, Manager s102190 S51
e UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D. C. 20555 January 23, 1981 SSINS No.:
6830 Accession No.:
8008220280 IE CIRCULAR NO. 8 t.-01:
DESIGN PROBLEMS INVOLVING INDICATING PUSHBUTTON SWITCHES MANUFACTURED BY HONEYWELL INCORPORATED
Background:
By letter dated September 18, 1980 (J.M. Curran to R.H. Engelken), Southern California Edison Company (SCE) notified NRC of design problems involving certain indicating pushbutton switches.
The subject switches are of the type designated as Series 2 indicating pushbutton switches that are manufactured by the Micro Switch Division of Honeywell Incorporated.
The switches identified by SCE as having design deficiencies are used on the containment isolation panels at San Onofre Unit 1 (Docket No. 50-206).
SCE identified two problems with the subject switches, both. of which manifest themselves during relamping:
(1) a short circuit maybe induced; and (2) the*
circuit. controlled.. by the* switch. may* inadvertently be* actuated.
Although the*
specificity of this circular is *restricted to the previously mentioned Series 2 switches. the* deficiencies, cited. may be 0
- common to other indicating pushbutton switches,.
Accordingly,. holders, of operating licenses. and. construction permits should. scrutinize the design. of other*indicating pushbutton switches in their facilities for susceptiblity to the* above problems..
By letter dated October 10, 1980 (J'. G. Haynes to R.H. Engelken), SCE submitted a detailed followup report addressing the defective switches.
Sections of the
$CE.report containing relevant information have been excerpted and included in the paragraphs that follow.
Sections so excerpted are identified by quotation marks.
Discussion:
The SCE report provided the following details of the problems previously mentioned:
"1.
The* design:: of indicating pushbutton switches is such that during insertion of the lamp assembly into the switch housing, shorting could occur between the metallic: p.lunger and the energized indicator
- lamp. connection inside* the switch as*sembly.
- Since the metal plunger is connected to the.cabinet ground through the switch housing, the control circuit could be short circuited, causing failure of the control circuit if it is energized*.
e
!EC No. 81.-01 January 23, 1981 Page 2 of 4
- 2.
The design 0£ the lamp assembly is such that to lock the switch into place after relamping will cause actuation of the.switch resulting in operation of the control circuit if it is energized.
Since the current containment isolation system operational design requires that the power supply to the containment isolation panels remain energized during relamping, the potential exists for operating containment isolation valves during the lamp replacement."
To circumvent the preceding problems, SCE,. in cooperation with Honeywell Incorporated, is implementing the following corrective actions.
"1.
The metallic plunger is being redesigned to solve the short circuit problem discussed in Item 1 above.
The design modification involves providing a plastic tip on the plunger.
The plastic tip will provide isolation between the metallic plunger and energized indicator lamp connection inside the switch assembly and this will avoid short circuit problems.
A prototype modified switch assembly was received on September 20, 1980 and successfully tested.
Accordingly, the manufacturer is developing the necessary tooling for production purposes. It is expected that the modified switch assemblies can be delivered and installed prior to return to power operation from the current outage.
- 2.
The indicating pushbutton lamp assembly system is being redesigned to solve*the*switch actuation problem discussed in Item 2. above.
The, design-modification will permit relamping with the power supply energized, without causing switch actuat:i,on.
It is expected that the systemwill be redesigned.and the current switches replaced during the next scheduled cold shutdown of sufficient duration following return to power operation from the current outage."
- In addition, SCE.. has-. instructed* its* station: personnel on procedural steps to be followed when* changing lamps.
The procedural steps currently in effect at San Onofre Unit 1 for relampingthe. indicating push button switches address* the potential for shorting or for inadvertently actuating the control circuit as*
follows:
"1.
Containment Isolation Valves on Non-essential Systems All automatic containment isolation valves are included in this category.
When replacement of a. burned out lamp is necessary, the power supply of the' circuit of the valve will be-opened and the associated valve will close* i£ open or will be de-energized in the closed.position if already closed.
The burned: out lamp will be replaced: and. the power supply to the circuit. will be closed permitting the' valve, to.be* reopened* or re-energized. in. the closed position.
- 2.
Remote Manual Containment Isolation Valves on Essential Systems The_systems in this category include the Chemical Volume and Control Letdown System, Reactor Coolant Pump Seal Water Return System, Turbine Plant Cooling Water Supply and Return System, and Pressurizer Relief
.J
-e e !EC No. 81-01 January 23, 1981 Page 3 of 4 Tank Nitrogen Supply System.
The containment isolation valves on these systems are normally open during operation and may be required to be open during accident conditions.
If it is necessary to replace burned out lamps after the metallic plunger has been -redesigned as described in corrective action 1 above, the following steps will be taken:
- 1.
The touch plate with the burned out lamp will be removed and lamps replaced.
- 2.
The glass cover on the HFA relay (panels behind north vertical board) associated with the valve in question will be removed and the relay held in place *by depressing the insulated portion of the spring loaded relay plunger.
- 3.
The touch plate with the replaced lamps will be inserted into the switch chassis.
- 4.
The "open" switch of the valve in question will be depressed to assure that the circuit has been reset and the glass cover replaced on the HFA relay."
"If it is_necessary to replace-burned out lamps before the metallic plun-ger. is redesigned, the replacement will be performed during an outage of sufficient duration when the affected system and valve can be removed from service. At that time, the procedural stepsc to be: followed are identical.
to. those established for the automatic containment isolation valves on non~
essential systems discussed above.
Until such*time as the lamp can be re-p,laced, the* position of the affected* valve can be determined by examining the" system flow, pressure-and. temperature process. instrumentation."
Recommended Actions for Holders of Construction Permits or Operating Licenses:
I.
Determine whether your facility uses the subject Series 2 indicating push-.
button* switches in any safety-related function.
If there are no indicating pushbutton switches of this type in your fac~lity, you need not pursue this matter further.
- 2.
If the subject switches are used to perform safety-related functions at your facility, either replace them with qualified units or modify them to eliminate the* deficiencies.
Holders of operating licenses should take the appropriate action as, soon* as practical; construction permit holders should.take the* appropriate* action prior to startup.
(If the switches are to be modified, contact Honeywell. Incorporated for assistance.)
- 3.
Until the appropriate* corrective action is, completed*, the following. interim measures should be taken:
e IEC No. 81-01 January 23, 1981 Page 4 of 4
- a.
If the design of the affected equipment permits its switch assembly to be deenergized for relamping, verify that the procedures specify that power is to be removed from the switch assembly during relamping.
If the procedures do not so specify, revise them to include such a provision.
- b.
If the-design of the affected equipment does not permit its switch assembly to be.deenergized for relamping, verify that the operator can dete_rmine the status of the affected equipment by alternate means.
Towards this end, implement procedures to enable the operator to determine the status. of the.affected equipment by alternate means (e-. g., acceptable method for inferring the position of a valve could-include system flow, pressure, or temperature measurements).. If alternate status indication methods are not available, relamping should be deferred until the next outage during which time the affected equipment can be removed from service.
However, during the* resulting blind time, rigid administrative controls should be.
implemented to provide the operator with reliable status information.
No written response to this circular is required.
If you require additional information with regard to this subject, please contact the appropriate NRC Regional Office.
Circular No.
81-01 80-25 80-24 80-23 80-22 80-21 80-20 80-19 80-18 80-17 80-16 RECENTLY ISSUED IE CIRCULARS Subject Design Problems Involving Indicating Pushbutton Switches Manufactured by Honeywell Incorporated Case Histories of Radiography Events AECL Teletherapy Unit Malfunction Potential Defects in Beloit Power Systems Emergency Generators Confirmation of Employee Qualifications Regulation of Refueling Crews Changes in Safe-Slab Tank Dimensions.
Noncompliance* with License Requirements for Medical Licensees 10 CFR 50.59 Safety Evaluations for Changes to Radioactive Waste Treatment Systems.
Fuel Pin Damage Due to Water Jet from Baffle Plate Corner Operational Deficiencies In Rosemount Model 510DU Trip Units And Model 1152 Pressure Transmitters Cooling and Natural Circula-tion Cooldown Date of Issue 01/23/81 12/5/80 12/2/80 10/31/80 10/2/80 9/10/80 8/21/80 8/26/80 8/22/80 7/23/80 6/27/80 OL - Operating Licenses CP = Construction Permit e IEC 81-01 January 23, 1981 Issued to All nuclear power facilities holding an OL or CP All radiography licensees All teletherapy licensees All power reactor facilities with OL or a CP All holders of a power reactor OL or CP architect-engineering companies and nuclear steam system suppliers All holders of a power reactor OL or CP All Part SO and Part 70 fuel facility licensees All medical licensees All power reactor facilities with an OL or CP All holders of PWR OLs and PWR CPs All power reactor facilities with an OL or a CP facilities with an OL or CP