NPSHR (NPSH3) Improvement of a Low Pressure Safety Injection Pump

Abstract

This case study discusses the rerate of a set of vertically-mounted single-stage end-suction centrifugal pumps used for low pressure safety injection (LPSI) in a nuclear power plant. The original LPSI pumps were supplied early 1970s and for safety purposes it was decided to overhaul these pumps to improve NPSHR (i.e. NPSH3). The rerate consisted of replacing the existing impeller with a new design yielding close to identical head performance characteristic, yet lower NPSHR. Aim was to improve NPSHR by (minimally) 0.5 m (1.64 ft) at rated capacity of 682 m3/h (3003 USGPM) and 1470 r/min running speed, and demonstrate by test the actual improvement in NPSHR