Bulletin 79-15: Deep Draft Pump Deficiencies
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF INSPECTION AND ENFORCEMENT
WASHINGTON, D.C. 20555
July 11, 1979
IE Bulletin No. 79-15
DEEP DRAFT PUMP DEFICIENCIES
Description of Circumstances:
On October 20, 1978, Commonwealth Edison Company reported that manufacturing
deficiencies had been identified in new high pressure core spray, low
pressure core spray, and residual heat removal pumps manufactured by
Ingersoll-Rand (I-R) Company, Cameron Pump Division.
Each of these pumps is a vertical turbine pump with impellers located in
bowls in a sump or a self contained barrel. The motor (prime mover) is
located at the highest pump elevation to take into account maximum flooding
at the site or space considerations. The suction is at the lower end of the
pump while the discharge head is just below the driver. Bearings supporting
the vertical shaft segments (usually 5 to 10 segments) are either self
lubricated, force fed (lubricated by fluid being pumped), or oil lubricated
and maintained within their own isolated system. These pumps are designated
as "Deep Draft". Figures 1&2 show typical outlines of such pumps.
The internal deficiencies, identified through dimensional and visual
inspections were as follows:
Low Pressure Core Spray Pumps (I-R Model No. 29APKD-5) (Date of Manufacture
- February 1973)
. Loose impeller bolts and bolts improperly staked
. Loose key - keyway fit
. Excessive runout on pump shaft
. Bearing showed wear
. Bearing clearance exceeded recommended tolerance
. Coupling thread galled
. Wear ring clearance out-of-specification
. Impeller-to-shaft clearance out of specification
. Cracks found in second-and-third-stage impellers
. Stuffing box bushings were severely galled
High Pressure Core Spray Pumps (I-R Model No. 12X20KD) (Date of Manufacture
- September 1972)
. Bearing clearance exceeded recommended tolerance
. Wear ring clearance out-of-specification
. Bearings showed wear
.
IE Bulletin No. 79-15 July 11, 1979
Page 2 of 3
. Bearing loose in casing
. Excessive runout on pump shaft
. Wear ring lock screws missing on eighth stage
. Shrink fit bearing came out of casing during pump shaft removal -
casing sleeve socket found to be egg shaped
Residual Heat Removal Pumps (I-R Model No. 29APKD-3) (Date of Manufacture
December 1972)
. Loose impeller bolts and bolts not properly staked
. Excessive runout on pump shaft
. Bearing found cracked
. Bearing clearance out-of-specification
. Couplings cut because galling prevented disassembly
. Wear ring clearance out-of-specification
The above deficiencies were identified at a facility under construction. In
1978, similar deficiencies in deep draft pumps were identified at three
other facilities (North Anna 1 & 2, Surry 1 & 2, Beaver Valley 1). Problems
with these pumps involved design and workmanship deficiencies which required
extensive inspection, replacement of parts and major redesign. The
manufacturers involved in these cases were Ingersoll-Rand,
Bingham-Willamette and Byron Jackson. Some of the measures taken to assure
pump operability at these locations included:
1. Pump shaft bearing redesign
2. Column redesign (stiffening) to improve vibration response
3. Upgraded pump alignment procedures
4. Pump fluid inlet condition reevaluation and redesign
5. Extensive testing
The observed deficiencies spanning the past 1 1/2 years indicate that pumps
of this class may not be sufficiently reliable particularly when utilized in
ECCS and RHR applications where long tem cooling capability is required
following a LOCA or similar event.
Action to be Taken by Licensees and Permit Holders:
All holders of reactor operating licenses and construction permits shall
provide the following information within 60 days of this letter.
1. The number of deep draft pumps similar to those shown in Figures 1 and
2 utilized in safety related applications in each facility.
2. Manufacturer, model, capacity and plant application.
.
IE Bulletin No. 79-15 July 11 ,1979
Page 3 of 3
3. Overall dimensions of pumps.
4. Summary of startup, testing and routine maintenance history.
5. Operational problems and major repair efforts.
6. The longest interval that each pump has been available for operation
without corrective maintenance. Identify the number of cycles of opera-
tion during this interval, the duration of each cycle and the operating
mode(s) (recirculation, rated flow, etc.). Identify the longest con-
tinuous operation at or near rated flow conditions for each pump and
the status of the pump operability at the end of the run.
In addition licensees shall accumulate and make available for inspection at
the licensees plant site the following information on the above identified
pumps.
1. Drawings, sectional assemblies and parts list.
2. Detailed history of pump maintenance (alignment, parts replacement,
etc) including bearing wear data, replacement frequency and a
comparison with the manufacturers rated life for wearing surfaces.
3. Quality assurance and reliability testing requirements.
4. Design specifications
5. Results of tests performed during operation or prior to licensing.
6. Details of the procedures used to align the pump column.
For those cases where the maintenance or operating history of a particular
pump indicates that the design specifications are not being met, initiate
appropriate actions that will demonstrate conformance to design
requirements. Provide a description of planned actions within 60 days
including a schedule for implementation of any actions that will not be
completed within 120 days. In addition describe any planned or completed
tests involving long tem operation of prototypes or pumps of similar design,
which demonstrate the long term operability of such deep draft pumps at your
facility.
Approved by GAO, B180225 (R0072), clearance expires 7/31/80. Approval was
given under a blanket clearance specifically for identified generic
problems.
Enclosure:
Figures 1 and 2
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