9-Day
Emergency
Repair
By Dr. T. Ravisundar, Hydro, Inc.
Dr. T. Ravisundar
Dr. T. Ravisundar is chief engineer
for Chicago-based Hydro, Inc. Prior
to joining Hydro
in mid-2009, he
spent more than
seven years at KSB
in Germany with
responsibility for
pump hydraulic
design and
development.
He earned a
doctorate from the
Indian Institute
of Technology
(Madras) in 1997
for his work on the
hydraulic design of
pumps and turbines.
Safety Injection Pump Requires
Challenging Turnkey Job
When a low head safety injection
pump rotor seized in its casing due to
an incident in a nuclear power plant, the
plant operation was flagged to critical and
consequently the pump repair became an
emergency. This challenging turnkey job
required decontamination, equivalency
engineering, new-parts manufacture, and
testing. The customer needed the repaired
pump to be returned to fully functional as
quickly as possible, meeting all its origi-
nal specification requirements. The en-
gineering pump repair service center at
HydroAire, a Hydro,
Inc., company in
Chicago, success-
fully implemented
a timely repair and
the challenging re-
installation of the
pump into service,
in a short turnaround
time of 9 days.
The safety in-
jection pump, a dou-
ble suction volute
casing pump, had
operated dry (with
the suction valve
closed and the dis-
charge valve open)
for
approximately
30 minutes, causing overheating and a
seized rotor. The damaged pump needed
to be decontaminated and was brought
to a third-party decontamination facil-
ity. During the pump disassembly by the
personnel at the decon facility, it was ob-
served that the impeller had seized into
the casing. Due to the limited resources at
the decon facility, a field machining com-
pany was called in to take the rotor off the
casing. This caused irreparable damages
to the impeller and rotor resulting in a
need for those parts to be replaced. Once
the pump had been decontaminated and
cleared for repair work, it was shipped
immediately to Hydro’s Chicago shop.
Emergent Preparations
Time was of the essence in
completing this repair. Per the customer’s
request, Hydro called in the shop’s
operations personnel and all required staff
in various departments for 24/7 service
in shifts. The customer also made their
station personnel available around-the-
clock at the plant and in Hydro’s service
center to monitor the in-process repair
and to assist in quicker decision making.
Communications
tactics
included
conference calls with the customer,
giving updates every four hours, every
day, during the full duration of the repair
and reinstallation process.
Equivalency Checks for
Spare Parts
To accelerate the repair process, all
relevant spare parts stocked in the plant’s
inventory were brought to Hydro’s
service center before the decontaminated
pump arrived. To avoid any surprises,
service center staff proactively reviewed
the original documentations and
inspected the spare parts which were
kept in inventory. Equivalencies such as
dimensional and functional conformity
were studied.
Engineering Analysis
The spare OEM impeller supplied
by the customer initially appeared to
be a viable replacement, ostensibly
Damaged rotor, due to pump running dry.
40
NuclearPlantJournal.com Nuclear Plant Journal, May-June 2016
