Methods for the determination of the in-phase and out-of-phase stability characteristics of a boiling water reactor

Journal Article · Mon Aug 01 04:00:00 EDT 1994 · Nuclear Technology; (United States)

OSTI ID:6991496

Van Der Hagen, T H.J.J.; Pazsit, I; Thomson, O ^[1]; Melkerson, B ^[2]

---

1. Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Reactor Physics
2. Vattenfall AB, Vaeroebacka (Sweden)

Measurements, taken in the Ringhals-1 boiling water reactor after revision in 1990, showed that instability occurred at high power and low core flow. Measurements in several points of the power-flow map showed that the decay ratio (DR), obtained by conventional methods, jumps from a moderate value directly to unity. This was valid for DR values calculated from both average power range monitor (APRM) and local power range monitor (LPRM) signals. Thus, the conventional DR cannot be used as a measure of the margin to instability. It was found that both global (in-phase) and regional (out-of-phase) oscillations occur, the global with low DR but large signal amplitude, and the regional with high DR but low signal amplitude. The former dominates the DR calculated from both APRMs and LPRMs, except when the instability is fully developed and impedes detection of the actual margin to instability. Methods for obtaining the stability characteristics of both modes separately from neutron noise signals were developed. The DR of the out-of-phase mode appears to be a good indicator of the margin to instability.

• OSTI ID: 6991496
• Journal Information: Nuclear Technology; (United States), Journal Name: Nuclear Technology; (United States) Vol. 107:2; ISSN 0029-5450; ISSN NUTYBB
• Country of Publication: United States
• Language: English

Related Subjects

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
210100 -- Power Reactors
Nonbreeding
Light-Water Moderated
Boiling Water Cooled
22 GENERAL STUDIES OF NUCLEAR REACTORS
220900* -- Nuclear Reactor Technology-- Reactor Safety
BWR TYPE REACTORS
COOLING SYSTEMS
ENERGY SYSTEMS
ENRICHED URANIUM REACTORS
FLOW RATE
POWER REACTORS
PRIMARY COOLANT CIRCUITS
REACTOR COMPONENTS
REACTOR COOLING SYSTEMS
REACTOR MONITORING SYSTEMS
REACTOR NOISE
REACTOR SAFETY
REACTOR STABILITY
REACTORS
RINGHALS-1 REACTOR
SAFETY
STABILITY
THERMAL REACTORS
WATER COOLED REACTORS
WATER MODERATED REACTORS