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Reactor coolant pump surveillance using sequential probability ratio tests

Conference · · Transactions of the American Nuclear Society; (USA)
OSTI ID:6434099
 [1];  [2];  [3]
  1. Argonne National Lab., IL (USA)
  2. Univ. of Maryland, College Park (USA)
  3. Indiana Univ., Bloomington (USA)

In March 1987, a pump-degradation event was experienced in one of the two primary coolant pumps at the Experimental Breeder Reactor II (EBR-II). The event was caused by mechanical binding of the rotating shaft, which reduced the flow rate of coolant through the core and caused an automatic scram of the reactor. Mechanical torquing of the pump shaft was sufficient to clear the sodium-oxide debris that caused the binding, and the reactor was returned to operation. Although no major equipment damage was experienced, an investigation was launched to develop new techniques for monitoring pump performance. Research has culminated in the development and computer implementation of an extremely sensitive pump operability surveillance technique that is based on the sequential probability ratio test (SPRT). The SPRT technique processes the stochastic components of digitized signals from identical sensors monitoring the same physical process on each of two pumps (e.g., speed signals, vibration levels, power, motor current, discharge pressure) and identifies subtle changes in the statistical quality of the noise associated with either signal. If any disturbance causes the noise characteristics for either signal to change, (e.g., a larger variance, skewness, or signal bias) then SPRT provides a sensitive and rapid annunciation of that disturbance while minimizing the probabilities of both false alarms and missed alarms.

OSTI ID:
6434099
Report Number(s):
CONF-891103--
Journal Information:
Transactions of the American Nuclear Society; (USA), Journal Name: Transactions of the American Nuclear Society; (USA) Vol. 60; ISSN TANSA; ISSN 0003-018X
Country of Publication:
United States
Language:
English