Faisal Salman and Nick Dagres of Hydro, Inc report how performing new design modifications on two critical safety-related charging pumps have extended their lifespan and reduced maintenance.
Written by: World Pumps
Publisher: World Pumps / February 2017
A Western European nuclear power plant was having difficulty meeting the necessary hydraulic performance at runout for two centrifugal charging pumps. The system needed 30 ft of Net Positive Suction Head required (NPSHr).
The pumps are safety-related pumps, which pump bore-rated water (water mixed with boric acid) into the reactor to kill nuclear fission. What water is to fire, bore-rated water is to nuclear fission. Bore-rated water kills nuclear reaction.
The two pumps are each about 15 ins in diameter and about 100 ins in length. They were shipped from the Western European site to Hydro, Inc.’s Chicago, IL facility to conduct analysis, redesign, manufacturing, and testing.
Scope of work
The customer had asked the original equipment manufacturer to help repair the two pumps because they were not meeting the hydraulic performance required at runout. However, the OEM was unable to resolve the issue of the NPSHr. It was needed on a critically tight emergency schedule.
The scope of work included the redesign and manufacturing of a new impeller, including the balancing, assembly, and performance testing with all necessary modifications during the process.
The first step was conducting an ‘as found’ performance test to determine how the pump was performing in its current condition. The data was collected and it confirmed the pump was not meeting the customer’s requirements.