Diagnostics and performance evaluation of neutron monitoring system detectors

Conference · Sat Jul 01 04:00:00 EDT 2006

OSTI ID:22030077

Kniss, T; Doyle, J ^[1]

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1. GE Energy, 8499 Darrow Rd., Twinsburg, OH 44087 (United States)

Neutron monitoring detectors used in Boiling Water Reactor (BWR) power range monitoring control systems are typically miniature fission chambers that remain in the core for many years. Pressurized Water Reactors (PWR) also utilize movable miniature fission chambers for neutron flux mapping during power operations. The baseline performance of the detectors must be established at the time of installation and retested periodically during the life of the detector to evaluate its suitability for continued use. This paper reports on the characteristics that the power range detectors typically exhibit at the beginning of life and describes the normal changes in characteristics that are expected to occur as the detector ages in the in-core environment. Deviations from the normal aging effects that may be revealed through periodic testing are described. Possible root causes for some deviations from the expected performance are discussed. In addition to the power range monitoring detectors, the neutron monitoring system also utilizes other fission chambers for source range or intermediate range neutron monitoring during startup, and neutron or gamma detectors for periodic sensitivity re-calibration of the power range monitoring detectors. Each of the detectors has function specific requirements that call for additional diagnostic testing methods to evaluate performance. Diagnostic tests such as Time Domain Reflectometry and Current vs. Voltage (IV) characterization provide useful information about the condition of the detector and the signal path that links the detector to the reactor monitoring and control system. Typical test results of properly functioning detectors are described and the significance of deviations from a normal result is discussed. (authors)

• Research Organization: American Nuclear Society, 555 North Kensington Avenue, La Grange Park, IL 60526 (United States)
• OSTI ID: 22030077
• Country of Publication: United States
• Language: English

Related Subjects

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
AGING
BWR TYPE REACTORS
CALIBRATION
FISSION CHAMBERS
IN CORE INSTRUMENTS
MAPPING
MONITORING
NEUTRON DETECTION
NEUTRON FLUX
PWR TYPE REACTORS
REACTOR CONTROL SYSTEMS
REACTOR CORES
REACTOR MONITORING SYSTEMS
SENSITIVITY