High Pressure Safety Injection (HPSI) System

The HPSI is used in all pressurized water reactor designs. The HPSI system is part of the Emergency Core Cooling System (ECCS) that performs emergency coolant injection and recirculation functions to maintain reactor core coolant inventory and adequate decay heat removal following a loss-of-coolant accident (LOCA). The coolant injection function is performed during a relatively short-term period after LOCA initiation, followed by realignment to a recirculation mode of operation to maintain long-term, post-LOCA core cooling.

The HPSI system actuates automatically on low pressurizer pressure, high containment pressure, or when steam line pressure or flow anomalies are detected. Therefore, in addition to a LOCA, other events will lead to HPI actuation. Some examples of such events are Steam Generator Tube Ruptures, RCS overcooling events resulting from steam line breaks (e.g.: stuck open main steam safety valves), or RCS depressurization events (e.g.: stuck open pressurizer spray valves).

The initial system study is documented in "Reliability Study: High-Pressure Safety Injection System, 1987–1997 (DRAFT)" (NUREG/CR-5500, Volume 9 ). The links below provide the current information for the study and latest results.

Current Results (SPAR-based):

Historical Results (SPAR-based):

Historical Results (LER-based):

Supporting Information:

Page Last Reviewed/Updated Monday, October 24, 2022