Applications of a surveillance and diagnostics methodology using neutron noise from a pressurized-water reactor

Journal Article · · Nuclear Safety; (United States)

OSTI ID:6870075

Wood, R T ^[1]; Miller, L F; Perez, R B ^[2]

---

1. Oak Ridge National Lab., TN (United States)
2. Univ. of Tennessee, Knoxville (United States)

Two applications of a noise diagnostic methodology were performed with ex-core neutron detector data from a pressurized-water reactor (PWR). A feedback dynamics model of the neutron power spectral denisty was derived from a low-order whole-plant physical model made stochastic with the Langevin technique. From a functional fit to plant data, the response of the dynamic system to changes in important physical parameters was evaluated by a direct sensitivity analysis. In addition, changes in monitored spectra were related to changes in physical parameters, and detection thresholds using common surveillance discriminants were determined. A resonance model was developed from perturbation theory to give the ex-core neutron detector response for small in-core mechanical motions in terms of a pole-strength factor, a resonance asymmetry (or skewness) factor, a vibration damping factor, and a frequency of vibration. The mechanical motion paramters for several resonances were determined by a functional fit of the model to plant data taken at various times during a fuel cycle and were tracked to determined trends that indicated vibrational changes of reactor internals. In addition, the resonance model gave the ability to separate the resonant components of the power spectral density after the parameters had been identified. As a result, the behavior of several vibration peaks was monitored over a fuel cycle. The noise diagnostic methodology illustrated by these applications can be used in monitoring the condition of the reactor system. Early detection of degraded mechanical components or undesirable operating conditions by using such surveillance and diagnostic techniques would enhance plant safety. 15 refs., 6 figs., 1 tab.

• DOE Contract Number: AC05-84OR21400
• OSTI ID: 6870075
• Journal Information: Nuclear Safety; (United States), Journal Name: Nuclear Safety; (United States) Vol. 33:1; ISSN 0029-5604; ISSN NUSAAZ
• Country of Publication: United States
• Language: English

Related Subjects

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
210200* -- Power Reactors
Nonbreeding
Light-Water Moderated
Nonboiling Water Cooled
DAMPING
DIAGNOSTIC TECHNIQUES
EMISSION
ENRICHED URANIUM REACTORS
FUEL CYCLE
FUNCTIONS
MONITORING
NEUTRON EMISSION
PERTURBATION THEORY
POWER REACTORS
PWR TYPE REACTORS
RADIATION MONITORING
REACTOR COMPONENTS
REACTOR INTERNALS
REACTOR NOISE
REACTOR SAFETY
REACTORS
RESONANCE
SAFETY
SENSITIVITY ANALYSIS
SPECTRAL DENSITY
SPECTRAL FUNCTIONS
THERMAL REACTORS
WATER COOLED REACTORS
WATER MODERATED REACTORS