ML19284A788
| ML19284A788 | |
| Person / Time | |
|---|---|
| Site: | Point Beach, Peach Bottom  |
| Issue date: | 01/03/1974 |
| From: | US ATOMIC ENERGY COMMISSION (AEC) |
| To: | |
| References | |
| IEB-74-01, IEB-74-1, NUDOCS 8001290636 | |
| Download: ML19284A788 (6) | |
Text
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January 3, 1974 Directorate of Regulatory Operations Bulletin No. 74-1 VALVE DEFICIENCIES Information was recently received from the Philadelphia Electric Company and the Wisconsin Electric Power Company concerning two types of deficiencies relating to valves.
The deficiency identified by the Philadelphia Electric Conpany at the Peach Bottom Units 2 and 3 facilities related to weld failures between the valve yoke and the meter 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 p:'vided in Attachment B.
In light of the above informatien, 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 the 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. Ltr dated 10-29-73 to J. F. O' Leary 80012$0 g{
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ATTACIMENT A f
PHILAD ELPHIA ELECTRIC COM PAN'Y 2301 M ARKET STREET PHILADELPHI A. PA.19101 (215)841-45o0 vict.m sios ht October 1, 1973 Dr. D. F. Knuth, Director Directorate of Regulatory Operations United States Atomic Energy Commiccien Washington, D.C.
20545
Subject:
Significant Deficiency Report -
High Pressure Service Water Valve Weld Failure Peach Bottem Atenic Power Station - Unitc 2 & 3 AEC Construction Permit Nos. CPPR-37 and CPPR-38 File: CUAL 2-10-2 SDR Ho. 5
Dear Dr. Knuth:
In compliance with 1CCFR50.55, paragraph (c) attached is the Significant Deficiency Report concerning the ucld failure on the High Pressure Service Fater valve in Unit Ho. 2.
This item was reported to AEC DRO I by telecon on June 1, 1973 We truct that thic satisfactorily recolves this item.
If further information is required, please do not hesitate to contact us.
We appreciate your extending the time for our response to October 1, 1973 as agreed by telecon on September 14, 1973 between our Mr. G. R. Hutt and Mr. R. Heischnann, USAEC DRO I.
Sincerely, 7
lY,
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Copy to:
J. P. O'Reilly, USAEC O..C C Q v.)
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SIGNIFICANT DE"ICIF.::CY REPORT - SDR I:0. 5 HIGH PREFS!DE FFZlTCE MATER VAI'TE UFJ D FAILUFE PEACH BOTTOM ATCMIC PO'.IrR STATION - UUITS 2 E: 3 AEC CO?!STRUCTION PER"IT HOS. CFPR-37 AHD CPPR-33 1
Description of Deficiency 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 !later line on the discharge side of one Residual Heat Removal heat exchanger was discovered to have experienced a weld failure.
The failure occurred between the valve yoke and the motor operator mounting plate. The reacon for the failure has been identified ac insufficient fillet weld throat dinancion caused by the install.ation of unauthoriced shins between the yoke legs and the mounting plate, which reduced the effective cice of the weld.
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_ Corrective Action j
The failed valve is cne of a ceriec of eight valves (four in Unit 2 and four in Unit 3). Thece eight valves were visually inspected and a second valve was found to have cracks in the yoke to motor operator mounting plate weld.1 All eight valves were returned to the vendor for rework.
The rework invo]ved elicinaticn of the chitc in the failed valve and the rowelding of the nounting plates to the yoke legc with full pene-tration welds on all eight valves.
An investigation of cimilar valves (cupplied by the cane vendor) elseuhere in the plant, was undertaken. A total of 108 valves were iden-tifled by the vendor to have yoke to motor operator nounting plate con-struction similar to that of the failed valve.
Fifty-eight (including the above mentioned eight) of these valves are nuclear valves claccified as Group II as defined by Figure A.2.1 of Appendix A of the Peach Botten Atomic Power Station FSAR.
The ranaining valves are Group III non-nuclear balance of plant valvec.
The Vendor's weld stress analysis calculations were revicued and a table of acceptable weld sicos prepared.
1 This valve was originally reported in the interim report to have chins.
The valve was only visually incpceted at that time and the cracks were interpreted to indicate the presence of shima.
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October 29, 1973 Mr. John F. O' Leary, Director Directorate of Licensing U. S. Atomic Energy Commission Washington, D. C.
20545
Dear Mr. O' Leary:
DOCKET NOS. 50-266 AND 50-301 FACILITY OPERATING LICENSE NOS. DPR-24 AND DPR-27 POINT BEACH NUCLEAR PLAUT BACKSEATING DISC MISLOCATION 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 IMOV-1299 on Unit 1 (excess letdown system root valve) on September 26, 1973.
Inspection of the valve disclosed that its downstream seat protruded from the valve body such that if the. valve disc was fully withdraun from 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 previor.; valve closings.
Internal damage to the valve consisted of a fine vertical crack at t.3 12 o' clock position in the upper portion of the downstream seat ring.
Two locating pins between the upstream and dotinstream discs of the split disc valve were found to be slightly bent also and some facial scratches to the down-stream disc were evident.
There was no metal loss involved in the damage.
vsas
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 eeat could not be fully lapped out during the repair.
Accordingly, a manual valve was added to the system downstream of 1MOV-1299 to back up the root valve.
Valve 1MOV-1299 thereby remains effective and operable as a remotely contr)lled root. shutoff valve, but is considered not totally capable of effecting completely tight shutoff without some through-leakage.
At the time, measurements indicated that the location of the backseating ring on the valve 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 seat.
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 & B (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 valva 427 is to close in the event of low pressuriser level and, in closing, cause the closure of the containment isolation valves 200 A, B 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 approxima tely 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 A0V-200 letdown isolation valves.
Measurements indicated that the discs of 1MOV-427 when e
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hk. John F. O' Leary October 29, 1973 backscated 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 down 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 October 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 locations on the stem.
With these confirmations, it was conclud-d that all twelve valves of this type would recuire investigation on a sche-dule commensurate with the plant operating schedules.
Valves 1MOV-1299, 2MOV-1299 and 2MOV-427 will be electrically limited similarly to 1MOV-427.
Valve IMOV-1299 will be completely 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 alve will not permit the discs to lose the guide effect 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,
/
6&C? '
Sol Burstein Senior Vice President cc:
Mr. James G.
Keppler Regional Director Directorate of Regulatory Operations, Region III 4
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