ML20037B378
| ML20037B378 | |
| Person / Time | |
|---|---|
| Site: | Dresden, Peach Bottom, Point Beach, Quad Cities, Zion, LaSalle  |
| Issue date: | 01/03/1974 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Brian Lee COMMONWEALTH EDISON CO. |
| Shared Package | |
| ML20037B379 | List: |
| References | |
| NUDOCS 8009240808 | |
| Download: ML20037B378 (1) | |
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UNITED STATE 3 I I ATOMIC ENERGY COMMISSION i
I DIRECTOR ATE OF REGULATORY OPERATIONS k,
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GLEN ELLYN, ILLINOIS 60137 (312) 858-2840 Janeary 3, 1974 i
Commonwealth Edison Company Dockets No. 50-10 ATTE:
Mr. Byron Lee, Jr.
50-237 Tice President 50-249 P. O. Box 767 50-254 Chicage, Illinois 60690 50-265 50-295 50-304 50-373 50-374 Gentlemen:
The enclosed Directorate of Regulatory operations Bulletin No. 74-1, involving two valve problems, is sent to you to provide you with information we recently received from the PM1mAelphia Electric Company and the Wisconsin Electric Power Company. The problems involved deficiencies identified at the Peach Bottom, Units 2 and 3 and the Point Beach reactors. This informa-tion may' relate to the performance of certain equipment at your facilities.
The Bellatin aise requests certcin action on your part in this matter.
Sincerely yours, James G. Keppler Regional Director Attaclament s Bulletin No. 74-1 i
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e' January 3, 1974 Directorate of Regulatory Operations Bulletin No. 74-1 VALVE DEFICIENCIES Information was recently received from the Philadelphia Electric
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Company and the Wisconsin Electric Power Company concerning two types of deficiencies relating to valves.
The deficiency identified by the Philadelphia Electric Company at' the Peach Bottom Units.2 and 3 facilities related to weld failures between the valve yoke and the motor operator mounting plate in valves supplied by the Walworth Company. A description of the deficiency is provided in Attachment A.
The second deficiency, identified by the Wisconsin Electric Power Company at the Point Beach plant, involved a backseating disc mislocation problem on two inch Darling valves. Details are provided in Attachment B.
In light of the above information, you are requested to determine whether similar valves are installed or scheduled to be installed in your facilities and inform this office in writing within 30 days of the date of this letter regarding dhe results of your determination.
Also please send a copy of your report to B. H. Grier, Assistant Director for Construction and Operation, Directorate of Regulatory Operations. USAEC, Washington, D. C. 20545.
In the event such valves are identified, you are requested to determine whether those identified valves have the deficiencies described and if so, to inform us in your letter of the corrective action planned and the date of scheduled completion of that corrective action.
Attachments:
A.
Philadelphia Electric Co. Ltr dated 10-1-73 to Dr. Knuth B.
Wisconsin Electric Power Co. L r dated 10-29-73 to J. F. O' Leary Cgat
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PHILADELPHIA ELECTRIC COMPANY 2301 MARKET STREET PHILADEt. PHI A. PA.19101 1215) 841-450o V.S.BOYER vics.passicant October 1, 1973 Dr. D. F. Knuth, Director Directorate of Regulatory Cperations United States Ate:J.c Energy Cc 4ssion Washington, D.C.
20545
Subject:
Significant Eeficiency Report -
High Pressure Service Water Valve Veld Failure Peach Botten Atenic Power Station - Units 2 & 3 l
AEC Construction Permit Nos. CPPR-37 and CPPR-38 File: OUltL 2-10-2 SDR No. 5 l
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Dear Dr. Knuth:
In compliance with 1CCFR50 55, paragraph (e) attached is the Significant Deficiency Report concerning the veld failure en the High Pressure Service Water valve in Unit No. 2.
This item was reported to AEC DRO I by telecon on June 1, 1973 We trust that this satisfactorily rescIves this iten.
If further information is required, please do not hesitate to contact us.
l We appreciate your extending the time for our respense to October 1,1973 as agreed by telecon en September 14, 1973 between l
our Mr. G. R. Hutt and Mr. R. Heisebmnm, USAEC DRO I.
Sincerely, l
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Copy to:
J. P. O' Rem y, USAEC
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3 SIG!!IFICANT DF5ICIE::CY REPCRT - SER NO. 5 HIGH PRESSURE SER'IICE MATr.R VAINE 1 ELD FAILURE PEACH BOTTOM ATOMIC PO'.ER STATIO!! - Ui!ITS 2 & 3 AEC CONSTRUCTIO:I PE9 FIT UGS. CPPR-37 AIID CPPR-38 I
Descrintion of Deficiency I
During a routine walk-thru of Unit No. 2 plant by the licensees operating personnel, a 12 inch - 300 pound motor operated globe valve in the High Pressure Service Water line on the discharge side of one Residual Heat Rencval heat exchanger was discovered to have experienced a weld failure. The failure occurred between the valve yoke and the motor operator mounting plate.
The reascn for the failum has been identified as insufficient fillet veld threat a4mnsion caused by the installation of unauthorised shins between the yoke legs and the mounting plate, which reduced the effective sisc of the weld.
i Corrective Action l
The failed valve is one of a series of eight valves (four in Unit 2 and four in Unit 3).
These eight valves were visually inspected I
and a second valve was found to have cracks in the yoko to motor operator mounting plate veld.'
All eight valves were returned to the vendor for rework.
The rework involved elimination of the shims in the failed valve and the reuelding of the counting plates to the yoke legs with full pene-tration welds on all eight valves.
i An investigation of s N 1ar valves (supplied by the same vendor) elsewhere in the plant, was undertaken.
A total of 108 valves vera iden-tified by the vendor to have yoke to motor operator =cunting plate con-
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struction similar to that of the failed valve.
Fi"ty-eight (includine the above mentioned eight) of these valves are nuclear valves classified as Group II as defined by Figure A.2.1 of Accendix A of the Peach Bo'+ m i
Atomic Power Station FSAR. The remaining valves are Group III non-nuclear balance of plant valves.
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The Vendor's weld stress analysis calculations were reviewed and a table of acceptable weld sises prepared.
1 This valve was originally reported in the interim report to have shims.
The valve was only vismily inspected at that time and the cracks were interpreted to indicate the presence of shima.
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October 29, 1973 f
Mr. John F. O' Leary, Director Directorate of Licensing U. S. Atomic Energy Ccmmission Washington, D. C.
20545
Dear Mr. O' Leary:
DOCKET NOS. 50-266 AND 50-301 FACILITY OPEPATING LICENSE NOS. DPR-24 AND DPR-27 POINT BEACH NUCLEAR PLANT BACKSEATING DISC MISLCCATION PROBLEM ON 2" DARLING VALVES In accordance with Section 15.6.6.A.3.b of the technical Specifications for Point Beach Nuclear Plant (Facility Operating License Nos. DPR-24 and DPR-27), this report describes a possible generic problem with a category of 2" gate valves in-stalled at Point Beach Nuclear Plant.
The valves in question are 2", No. S-350 WDD welding end, outside screw and yoke, double disc gate valves with lip seals, and are manufactured by the Darling Valve and Manufacturing Ccmpany.
The valves used at Point Beach Nuclear Plant are safety class I, ASA series 1500 lb. valves.
An investigation of excess letdown line leakage on September 15, 1973, lead to an inspection and subsequent repair of valve DIOV-1299 on Unit 1 (excess letdown system root valve) on Septerber 26, 1973.
Inspection of the valve disclosed that its dcwnstream seat protruded from the valve bcdy such that if the valve disc was fully withdrawn frem the guides, as allowed by its backseating ring, the disc could catch the " lip" of the seat ring when reinserting.
Four marks on the lip of the down-stream seat ring indicated that the disc had caught there during previous valve closings.
Internal damage to the valve consisted of a fine vertical crack at the 12 o'cicek position in the upper portion of the downstream seat ring.
Two locating pins between the upstream and downstream discs of the split disc valve were found to be slightly bent also and scme facial scratches to the down stream disc were evident.
There was no metal loss involved in the damage.
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.Mr. John F. O' Leary October 29, 1973
-Repair of the valve involved rounding the lip of the seat ring to prevent future hangups of the disc.
The thin ver-tical crack in the downstream seat could not be fully lapped out during the repair.
Accordingly, a manual valve was added to the system dcwnstream of 1MOV-1299 to back up the root valve.
Valve IMOV-1299 thereby remains effective and operable as a remotely controlled root shutoff valve, but is considered not totally
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capable of effecting ccmpletely tight shutoff without some through-leakage.
At the time, measurements indicated that the location of the backseating ring on the valv.e stem was too low but this could not be assuredly determined.
If such was the case, this would allow the split discs to fully clear the seat rings when the valve was fully open and backseated.
The tendency'for inter-ference to occur between the downstream disc and seat during valve closing could be expected to increase if there was flow through the valve, creating a differential pressure which could swing the loose hanging disc onto the lip of the scat.
There are six similar 2" Darling valves in each unit at Point Beach Nuclear Plant.
In addition to the above mentioned 1299 valve, valves 270A & a (normally open) are installed on the reactor coolant pump seal return lines.
These valves are, rarely operated in the life of the plant.
Also, valves 598 and 599 on the reactor coolant system drain line are of this type.
These valves are never operated during normal pressurized and power operation.
The sixth,similar valve on each unit is MOV-427 on the normal letdown line.
The function of valve 427 is to close in the event of low pressurizer level and, in closing, cause che closure of the containnent isolation valves 200 A, 3 and C, via an interlock.
None of the Darling valves described in this re-port are containment isolation valves.
Valve IMOV-427 was investigated during a Unit 1 shut-down on October 13, 1973, after it was reported that it would not fully close remotely.
Manual manipulation of the valve on Septem-ber 28, 1973, had shown that at approximately one-half shut and again just prior to closing, the valve operation became sticky.
Tests were conducted at that time to verify that IMOV-427 was capable of performing its primary function of initiating an iso-lation signal for the letdown line.
The slightest movement of the valve off its backseat was found to be sufficient to activate the interlocks and close the AOV-200 letdown isolation valves.
Measurements indicated that the discs of 1MOV-427 when e
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Mr. John F. O' Leary 3-October 29, 1973 backseated cleared the seat rings and left the valve open to simi-lar problems as experienced in 1MOV-1299.
Inspection showed no damage to valve IMOV-427 other than a slight marking of the upper edge of the seat ring, similar to that found in 1MOV-1299.
Before closing up the valve, the seat ring edges were rounded to aid in guiding the discs dcwn between the seats.
The " valve open" limit-switch was then set for 2-1/4", 5/16" less than the maximum back-
-seating position of 2-9/16".
Valve cycling tests were then con-ducted satisfactorily.
During the same shutdown, valve IMOV-270B was cycled manually with no evidence of stickiness or disc hangup.
At the completion of repair of 1MOV-427, on Oc:cher 13, 1973, it was concluded frca measurements taken, operating experience and tele-phone discussions with the valve manufacturer, that, indeed a
dimension error could exist with respect to backseat locatienc on the stem.
With these confirmations, it was concluded that all twelve valves of this type would recuire investigation on a sche-dule commensurate with the plant operating schedules.
Valves IMOV-1299, 2MOV-1299 and 2MOV-427 will be electrically limited similarly to IMOV-4-27.
Valve IMOV-1299 will be ccmpletely changed out during a convenient shutdown fol-lowing the receipt of a new valve.
New valve stems with back-seats located so that full opening of the valve will not permit the discs to lose the guide eff ect of the seats have been ordered and will be fitted in the remaining valves at convenient shut-downs.
The service of the 598, 599 and 270A & B valves is such that it is not considered necessary to change the stems of these valves until the next refueling shutdown of each unit.
The nuclear steam supply system supplier has been in-formed about the problems encountered with these valves.
Very truly yours,
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1 Sol Burstein Senior Vice President 4
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Mr. James G. Keppler Regional Director Directorate of Regulatory Operations, Region III i
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