ML20125B942
| ML20125B942 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 07/03/1978 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Wachter L NORTHERN STATES POWER CO. |
| References | |
| NUDOCS 9212100222 | |
| Download: ML20125B942 (1) | |
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DA JUL 0 31978 J
Docket No. 5 26 Nort States Power Company A
eteo Wachter Vice President Power Production and System operation 414 Nicollet Hall Minneapolis, MN 55401 Gentlemen:
The enclosed IE Circular No. 78-12, is forwarded to you for information. No written response is required.
Should you have any questions related to your understanding of this matter, please contact this office.
Sincerely, James G. Keppler Director
Enclosures:
1.
IE Circular No. 78-12 2.
List of IE Circulars Issued in 1978 cc w/encls:
Mr. L. R. Eliason, Plant Manager
/ Central Files Director, NRR/DPH Director, NRR/ DOR
/
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DR 9212100222 780903 NSIC PDR ADOCK 05000263 TIC O
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Anthony Roisman, Esq.,
Attorney
.Tnkn V. Ps.rwnn ; Ph.D_;
RIII g{_,RIII Ruelear Engineer orriCE >
[_[iprelli/bk er SURNAME >
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NRC Form 318A (R3II) (5-76) N RCM 02040
'U. 5. GOVCRNMENT PRINTING OFFICE: 1978-25 3 814 l L
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U.S. NUCLEAR REGULATORY COMMIS3 ION OFFICE OF INSPECTION AND ENFORCEhTNT REGION III July 3, 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 valve 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 manuf actured by the Terry Steam Turbine Company.
Investigation revealed that the control valve lif t 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, decemined that the bending may have resulted from binding due to scale or rust buildup on the rods. The control valve lif t rods have a series of circumferential reliefs for steam leakage control. Material vedging 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 event a review was made to determine the extent of a possible generic problem in the area. -It was determined that the problem affects only the HPCI turbine with its multiple control valvea; other applic.ations using Terry Turbines, as in the Reactor Core Isolation Cooling System (RCIC) in BWRs and the Auxiliary Feedvater Pump in PWRs, are not af fected since they -incorporate a dif ferent 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, l
GE issued Service Information Letter (SIL) No. 223, dated July 8,1977 i
and associated instruction / drawing sheets to GE nuclear power facilities having HPCI turbines. That SIL together with the instruction / drawing sheets identified the control valve lift rod problem and the recoc= ended correc-l tive action. The recommended action by GE for BWR facilities with a HPCI turbine as set forth in the SIL is quoted ao follows:
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. i IE Circular No. 78 July 3, 1978-Examine the control valve linkage assembly for any evidence Examinalthe life rod 1*
of binding, rust or scale accumulation.
for evidence of bending. Damaged lift rods should be replaced. Do not attampt to rework or straighten.
Verify proper control valve linkage lengths as defined' on-
"2.
the lever diagram contained in Section 9 of your HPCI Terrv-turbine instruction manual. These measurements should be taken-with the turbine in the cold condition.
Exercise the' control valve linkage on a weekly basis, either manually or by starting the auxiliary oil pump, and verify 3.
total valve travel'and freedom of movement.
b l conditions noted-in the above "Immediately report any a norma checks to your local General Electric service representative.
"In addition, General Electric recommends that BWR operators install a -linkage modification which vill reduce the bending moment on the The hardware and an TDI lift rods during opening and closing cycles.
detailing instellation 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 EPCI Terry Turbine should be aware of the possibility of a scale or corrosion product buildup' in the steem chest The information and recom-bushing area and possible lif t rod seizure.
mandation provided by General Electric should be= referred to for appropriate corrective action.
No written response to this Circular is required. If you require e
additional information regarding this matter, contact the Director of the appropriate NRC Regional Office.
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IE Circular No. 78-12 July 3, 1978 LISTING OF IE CIRCULARS ISSUED IN 1978 Circular Subject Date issued To No.
of Issue 78-01 Loss of Well Logging 4/5/78 All Holders of Source Well Logging Source Licenses 78-02 Proper Lubricating 011 4/20/78 All Holders of for Terry Turbines Reactor OLs or cps 78-03 Packaging creater Than 5/12/78 All Holders of Type A Quantities of Reactor OLs, cps, Low Specific Activity Puel Cycle.
Radioactive Material Priority 1 Material for Transport and Wase,e Disposal Licenses 78-04 Installation Error That 5/15/78 All Holders of Could Prevent Closing of Reactor OLs or Fire Doors cps s
78-05 Inadvertent safety injection 5/23/78 All Holders of During Cooldown Reactor OLs or cps 78-06 Potential Common Mode 5/23/78 All Holders of Plooding of ECCS Equipment Reactor Ots or Rooms at BWR Pacilities 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 CPa Company Site 2 Contactors Enclosure Page 1 of 2
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IE Circular No. 78-12 July 3, 1978 LISTING OF IE CIRCULARS ISSUED IN 1978 Date of Issued to Circular Subject Issue No.
78-10 Control of Sealed 6/14/78 All Medical Licensees in Sources Used in Categories G Radiation Therapy and G1 78-11 Recirculation H-G 6/15/78 All Holders of BWR OLs or cps Set Overspeed Stop Enclosure Page 2 of 2
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