Theory of cladding breach location and size determination using delayed neutron signals

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1988

OSTI ID:7142359

Reece, Jr, W D

For nuclear reactors that use clad fuel, the detection of breach of clad and the determination of location and of size of breach is a troublesome and time consuming process, especially for reactors with liquid metal coolant. When breach of cladding occurs, fission fragments created in the fuel below the breach can be transported into the coolant. Some of these fission fragments are delayed neutron precursors, that is, after undergoing a beta decay, these fragments eject a neutron from the nucleus as a mode of decay toward stability. Several reactors monitor for these delayed neutrons to detect failed fuel and to try to locate the breach, notably, the second Experimental Breeder Reactor (EBR-II), the Fast Flux Text Facility (FFTF), and the French fast reactors, Rapsodie, Phenix, and Superphenix. The detection and location systems of these reactors are reviewed and the limitations of each are discussed. The analyses of all of these reactor system signals are based largely on empirical data, without a complete understanding of the mechanisms involved. In this thesis, each step of the process that leads to a delayed neutron signal is analyzed and a complete theoretical model is developed for each step. Transport by the coolant, although ignored or grossly simplified by all other analysis methods, is shown to be dominant factor in the delayed neutron signal. This algorithm is tested on data collected on two different breaches in the FFTF. The location of one of the breaches is correctly predicted by the algorithm, and on the other, the signal between two of the monitors appears to be switched. Experiments are proposed using the FFTF to confirm the algorithms developed in this thesis.

• Research Organization: Georgia Inst. of Tech., Atlanta, GA (USA)
• OSTI ID: 7142359
• Country of Publication: United States
• Language: English

Related Subjects

050000 -- Nuclear Fuels
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
210000 -- Nuclear Power Plants
22 GENERAL STUDIES OF NUCLEAR REACTORS
220300 -- Nuclear Reactor Technology-- Fuel Elements
651000* -- Nuclear Physics
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ACCIDENTS
BREEDER REACTORS
COMPUTER CODES
DATA ANALYSIS
DETECTION
EBR-2 REACTOR
ENRICHED URANIUM REACTORS
EPITHERMAL REACTORS
EXPERIMENTAL REACTORS
FAST REACTORS
FBR TYPE REACTORS
FFTF REACTOR
FISSION PRODUCT RELEASE
FUEL ELEMENT FAILURE
FUEL-COOLANT INTERACTIONS
LIQUID METAL COOLED REACTORS
LMFBR TYPE REACTORS
NEUTRON DETECTION
PHENIX REACTOR
PLUTONIUM REACTORS
POWER REACTORS
RADIATION DETECTION
RAPSODIE REACTOR
REACTOR ACCIDENTS
REACTORS
RESEARCH AND TEST REACTORS
RESEARCH REACTORS
SODIUM COOLED REACTORS
SUPER PHENIX REACTOR
TEST REACTORS