ML19209A005
| ML19209A005 | |
| Person / Time | |
|---|---|
| Issue date: | 06/30/1978 |
| From: | NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| To: | |
| References | |
| IEC-78-12, NUDOCS 7910010761 | |
| Download: ML19209A005 (4) | |
Text
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UNITED STATES N11 CLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON D. C.
20555 June 30, 1978 IE Circular No. 78-12 HPCI TURBINE CONTROL VALVE LIFT ROD BENDING In March 1977, during routine surveillance testing of the High Pressure Coolant Injection (HPCI) system at Cooper Nuclear Station, it was found that the minimum turbine speed attainable via control valse regulation by the speed governor was 4000 rpm. This indicated that the control valves were remaining partially open even though the control system was sending a shut signal. The HPCI turbine is manufactured by the Terry g
Steam Turbine Company.
l Investigation revealed that the control valve lift rods were bent.
The initial cause was thought to be improper linkage length adjustments causing positive overtravel in the closed position.
Subsequent review, while not discounting the previous conclusions, determined that the bending may have resulted from binding due to scale or rust buildup on the rods. The control valve lift rods have a series of circumferential reliefs for steam leakage control. Material wedging between the rod relief area and the rod bushing in the steam chest could cause momentary seizure and bending of the lift rods during the rapid closure action associated with a quick start.
Subsequent to this evet.t a review was made te determine the extent of a possible generic probleo in the area.
It was determined that the problem affects only the HPCI turbine with its multiple control valves; other applications using Terry Turbines, as in the Reactor Core Isolation Cooling System (RCIC) in BkRs and the Auxiliary Feedwater Pump in PWRs, are not affected since they incorporate a different control system.
During the review, GE representatives were consulted and it was learned that bent lift rods had been reported at four operating BWRs.
In response, GE issued Service Information Letter (SIL) No. 223, dated July 8, 1977 and associated instruction / drawing sheets to GE nuclear power facilities baving HPCI turbines. That SIL together with the instruction / drawing sheets identified the control valve lift rod problem and the recornended correc-tive action. The recommended action by GE for BWR facilities with a HPCI turbine as set forth in the SIL is quoted as follows:
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s IE Circular No. 78-12 June 30, 1978 "1.
Examine the control valve linkage assembly for any evidence of binding, rust or scale accumulation.
Examine the lift rod for evidence of bending.
Damaged lift rods should be replaced.
Do not attempt to rework or straighten.
"2.
Verify proper control valve linkage lengths as defined on the lever diagram contained in Section 9 of your llPCI Terry turbine instruction manual.
These measurements should be taken with the turbine in the cold condition.
"3.
Exercise the control valve linkage on a weekly basis, either manually or by starting the auxiliary oil pump, and verify total valve travel and freedom of movement.
"Isnediately report any abnormal conditions noted in the above I
checks to your local General Electric service representative.
"In addition, General Electric recommends that BWR operators install a linkage modification which will reduce the bending moment on the lift rods during opening and closing cycles. The hardware and an FDI detailing installation instructions will be made available at no charge in approximately 3 months.
Following installation and check out of this modification, the weekly check (item 3 above) may be discontinued."
All holders of boiling water reactor operating licenses or construction permits for facilities with a HPCI Terry Turbine should be aware of the possibility of a scale or corrosion product buildup in the steam chest bushing area and possible lift rod seizure. The infonnation and recom-mendation provided by General Electric should be referred to for appropriate corrective action.
No written response to this Circular is required.
If you require additional information regarding this matter, contact the Director of the appropriate NRC Regional Office.
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9 IE Circular No. 78-12 June 30, 1978 LISTING OF 1E CIRCULARS ISSUED IN 1978 Circular Subject Date Issued To No.
or Issue 78-01 Loss of Well Logging 4/5/78 All Holders of Source Well Logging Source Licenses 78-02 Proper Lubricating Oil 4/20/78 All Holders of for Terry Turbines Reactor OLs or cps 78-03 Packaging Greater Than 5/12/78 All Holders of Type A Quantities of l
Low Specific Activity Reactor Ols, cps, j
Radioactive Material Fuel Cycle, for Transport Priority I Material 1
and Vaste Disposal Licenses 78-04 Installation Error That 5/15/78 All Holders of Could Prevent Closing of Fire Doors Reactor OLs or cps 78-05 Inadvertent safety Injection 5/23/78 All Holders of During Cooldown Reactor OLs or cps 78-06 Potential Cormon Mode 5/23/78 All Holders of Flooding of ECCS Equipment Reactor OLs or Rooms at BWR Facilities cps 78-07 Damaged Components of a 5/31/78 All Holders of Bergen-Paterson Series Reactor OLs or 25000 Hydraulic Test cps Stand 78-08 Environmental Qualification 5/31/78 All Holders of of Safety Related Equipment Reactor OLs or at Nuclear Power Plants cps 78-09 Arcing of General Electric 6/5/78 All Holders of Company Size 2 Contactors cps Enclosure Page 1 of 2 1
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IE Circular No. 78-12 June 30, 1978 LISTING OF IE CIRCULARS ISSUED IN 1978 Date of Issued to Circular Subject Issue No.
78-10 Control of Scaled 6/14/78 All Medical Licensees in Sources Used in Categories G Radiation Therapy and G1 78-11 Recirculation M-G 6/15/78 All 11olders of BWR OLs or cps Set Overspeed Stop l
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