IE Circular No. 78-12 - HPCI Turbine Control Valve Lift Rod Bending
CR78012
UNITED STATES
NUCLEAR REGULATORY COMMISSION
WASHINGTON, D. C. 20555
June 29, 1978
MEMORANDUM FOR: B. H. Grier, Director, Region I
J. P. O'Reilly, Director, Region II
J. G. Keppler, Director, Region III
K. V. Seyfrit, Director, Region IV
R. H. Engelken, Director, Region V
FROM: Norman C. Moseley, Director, Division of Reactor
Operations Inspection, Office of Inspection and
Enforcement
SUBJECT: IE CIRCULAR 78-12 - HPCI TURBINE CONTROL VALVE LIFT
ROD BENDING
The subject circular is transmitted for issuance no later than the
close of business on June 30, 1978. The circular should be issued to all
holders of BWR Operating Licenses or Construction Permits excepting those
listed in Enclosure 2. Also enclosed is a draft copy of the transmittal
letter.
Norman C. Moseley, Director
Division of Reactor Operations
Inspection
Office of Inspection and Enforcement
Enclosures:
1. Draft Transmittal Letter
2. List of Non-Applicable
BWR Plants
3. IE Circular 78-12
CONTACT: C. J. DeBevec, IE
49-28180
.
(Transmittal letter for IE Circular 78-12, to each holder of a BWR Operating
License or Construction Permit excepting to those listed as non-applicable
BWR plants)
Addressee:
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,
Signature
(Regional Director)
Enclosures:
1. IE Circular No. 78-12
2. List of IE-Circulars
Issued for 1978
.
List of Non-Applicable BWR Plants
The BWR plants listed below do not have a HPCI system or if they have a HPCI
system they use a different steam turbine. For these reasons the enclosed
Circular should not be issued to the licensees of these plants.
Plants in Region I
Millstone Unit No. 1
Nine Mile Point Unit No. 1
Oyster Creek
Plants in Region III
Big Rock Point
Dresden Unit Nos. 1, 2 and 3
La Crosse
Quad Cities Unit Nos. 1 and 2
Plant in Region V
Humboldt Bay
.
UNITED STATES
NUCLEAR 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 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 manufactured by the Terry Steam Turbine Company.
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 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 valves; other
applications using Terry Turbines, as in the Reactor Core Isolation Cooling
System (RCIC) in BWRs 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 having
HPCI turbines. That SIL together with the instruction/drawing sheets
identified the control valve lift rod problem and the recommended corrective
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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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 HPCI Terry turbine
instruction manual. These measures 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.
"Immediately report any abnormal conditions noted in the above 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 movement 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 information and
recommendation 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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