ML20203G287
| ML20203G287 | |
| Person / Time | |
|---|---|
| Issue date: | 07/28/1986 |
| From: | Rosenthal J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| To: | Stramback G GENERAL ELECTRIC CO. |
| References | |
| NUDOCS 8608010060 | |
| Download: ML20203G287 (3) | |
Text
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JUL 28 M Mr. George B. Stramback M/C 682 General Electric Company 175 Curtner Avenue San Jose, CA 95123
Dear Mr. Stramback:
SUBJECT:
IE DRAFT INFORMATION NOTICE:
SCRAM S0LEN0ID VALVE REBUILD KIT PROBLEMS The draft IE information notice is enclosed.for your review per the recent telephone conversation between you and Eric Weiss of my staff.
If you have any comments, please send them to me as soon as possible but not later than 7 days from the date of this letter because we expect to issue the notice soon.
If you have any questions regarding this matter, please feel free to contact me or Mr. Weiss.
I can be reached at (301) 492-4193 and Mr. Weiss at (301) 492-9005.
Sincerely, Grismai aews y Jack E. Rosenthal, Chief Events Analysis Branch Division of Emergency Preparedness and Engineering Response Office of Inspection and Enforcement
Enclosure:
IE draft information notice Distribution:
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IN 86-0NITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 July 1986 IE INFORMATION NOTICE NO. 86- :
SCRAM S0LEN010 VALVE REBUILD KIT PROBLEMS Addressees:
All boiling water reactor (BWR) facilities holding an operating license (0L) or a constrt: tion permit (CP).
Purpose:
This notice is to alert recipients of a potential problem with kits used to refurbish the scram solenoid valves.
Recipients are expected to review the information for applicability to their facilities and consider actions, if appropriate, to preclude similar problems occurring at their facilities.
However, suggestions contained in this information notice do not constitute NRC requirements; therefore, no specific action or written response is required.
Description of Circumstances:
On June 14, 1986, Vermont Yankee nuclear power plant reported that one control rod failed to scram and five others hesitated a few seconds before scramming during a single-rod scram time test.
During the outage that preceded the scram time test, all of the scram solenoid valves had been rebuilt with replacement kits supplied by General Electric Company (GE).
The reactor had been taken critical before the problem was discovered because the in-sequence critical test was performed before the testing that identified the problem with the scram solenoid valves.
Three types of problems were identified in the scarm solenoid valves (SVs) which operated six control rods.
In one SV, the core spring of the SV was separated from the core assembly.
On another SV, the diaphragm was installed backwards on the exhaust side of the solenoid valve.
On four SVs, an incorrect core assembly provided with the kits was installed in the valve. Subsequent investigation determined that in one SV, the spring was separated from the core.
Also some solenoid base subassemblies that were out of round, which could prevent free travel of the core.
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IN 86-
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Discussion:
These problems would likely delay but 'not prevent a scram during normal operation because backup scram valves would depressurize the air header and cause the control rods to scram.
The defective rebuild kits are used at BWR-2s, 3s, 4s, and some Ss.
Vermont Yankee used replacement kits (ASCO type 204-139) to refurbish the scram solenoids in the Hydraulic Contro Units (HCU).
GE purchased 3000 of these replacement kits from Automatic Switch Company (ASCO), the manufacturer of the solenoid valves.
GE purchased these kits as commercial grade items.
Each kit contains 11 individual components, of which two are assemblies.
The two assemblies are the core assembly (ASCO part 65-716-2A) and the solenoid base sub-assembly (ASCO part 44-869-2) and require critical inspections.
On June 26, 1986, subsequent to the event at Vermont Yankee, GE returned to ASCO 200 replacement kits (ASCO type 204-139) from their stock and requested ASCO to perform critical inspections.
ASCO inspected the two assemblies in each kit and rejected 127 core assemblies and two solenoid base assemblies for out of tolerance conditions.
The rejected parts were replaced with acceptablie assemblies.
Although the extent of the distribution of the parts kits used to rebuild the scram solenoid valves is not known at this time, preliminary information suggests that these kits may be in wide distribution.
ASCO suggests that the kits be returned to GE.
No specific action or written response is required by this information notice.
If you have questions about this matter, please contact the Regional Adminis-trator of the appropriate NRC regional office or this office.
p'o7' S((p1/60 Edward L. Jordan, Director Division of Emergency Preparedness and Engineering Response Office of Inspection and Enforcement Technical
Contact:
Eric Weiss, IE (301) 492-9005 K. R. Naidu, IE (301) 492-4179
Attachment:
List of Recently Issued IE Information Notices
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