Probabilistic methods in a study of trip setpoints

Conference · Sun Jul 01 04:00:00 EDT 2012

OSTI ID:22105897

Kaulitz, D. E. ^[1]

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1. Tennessee Valley Authority, LP 4G-C, 1101 Market Street, Chattanooga, TN 37402-2801 (United States)

Most early vintage Boiling Water Reactors have a high head and high capacity High Pressure Coolant Injection (HPCI) pump to keep the core covered following a loss of coolant accident (LOCA). However, the protection afforded by the HPCI pump for mitigating a LOCA introduces the potential that a spurious start of the HPCI pump could oversupply the reactor vessel and lead to an automatic trip of the main turbine due to high water level. A turbine trip and associated increase in moderator density could challenge the bases of fuel integrity operating limits. To prevent turbine trip during spurious operation of the HPCI pump, the reactor protection system includes instrumentation and logic to sense high water level and automatically trip the HPCI pump prior to reaching the turbine trip setpoint. This paper describes an analysis that was performed to determine if existing reactor vessel water level trip instrumentation, logic and setpoints result in a high probability that the HPCI pump will trip prior to actuation of the turbine trip. Using nominal values for the initial water level and for the HPCI pump and turbine trip setpoints, and using the probability distribution functions for measurement uncertainty in these setpoints, a Monte Carlo simulation was employed to determine probabilities of successfully tripping the HPCI pump prior to tripping of the turbine. The results of the analysis established that the existing setpoints, instrumentation and logic would be expected to reliably prevent a trip of the main turbine. (authors)

• Research Organization: American Nuclear Society, Inc., 555 N. Kensington Avenue, La Grange Park, Illinois 60526 (United States)
• OSTI ID: 22105897
• Country of Publication: United States
• Language: English

Related Subjects

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
BWR TYPE REACTORS
COMPUTERIZED SIMULATION
DISTRIBUTION FUNCTIONS
FUEL INTEGRITY
HIGH PRESSURE COOLANT INJECTION
LOSS OF COOLANT
MODERATORS
MONTE CARLO METHOD
PRESSURE RANGE MEGA PA 10-100
PROBABILISTIC ESTIMATION
PROBABILITY
PUMPS
REACTOR SAFETY
REACTOR VESSELS
TURBINES
WATER