Nuclear reactor with internal thimble-type delayed neutron detection system
- Lemont, IL
- Downers Grove, IL
- Wheaton, IL
This invention teaches improved apparatus for the method of detecting a breach in cladded fuel used in a nuclear reactor. The detector apparatus is located in the primary heat exchanger which conveys part of the reactor coolant past at least three separate delayed-neutron detectors mounted in this heat exchanger. The detectors are spaced apart such that the coolant flow time from the core to each detector is different, and these differences are known. The delayed-neutron activity at the detectors is a function of the delay time after the reaction in the fuel until the coolant carrying the delayed-neutron emitter passes the respective detector. This time delay is broken down into separate components including an isotopic holdup time required for the emitter to move through the fuel from the reaction to the coolant at the breach, and two transit times required for the emitter now in the coolant to flow from the breach to the detector loop and then via the loop to the detector. At least two of these time components are determined during calibrated operation of the reactor. Thereafter during normal reactor operation, repeated comparisons are made by the method of regression approximation of the third time component for the best-fit line correlating measured delayed-neutron activity against activity that is approximated according to specific equations. The equations use these time-delay components and known parameter values of the fuel and of the part and emitting daughter isotopes.
- Research Organization:
- Argonne National Laboratory (ANL), Argonne, IL (United States)
- DOE Contract Number:
- W-31109-ENG-38
- Assignee:
- United States of America as represented by United States (Washington, DC)
- Patent Number(s):
- US 4938917
- OSTI ID:
- 867442
- Country of Publication:
- United States
- Language:
- English
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Apparatus for and method of monitoring for breached fuel elements
Apparatus for and method of monitoring for breached fuel elements
Related Subjects
reactor
internal
thimble-type
delayed
neutron
detection
teaches
improved
apparatus
method
detecting
breach
cladded
fuel
detector
located
primary
heat
exchanger
conveys
coolant
past
separate
delayed-neutron
detectors
mounted
spaced
apart
flow
time
core
differences
activity
function
delay
reaction
carrying
emitter
passes
respective
broken
components
including
isotopic
holdup
required
move
transit
times
loop
via
determined
calibrated
operation
thereafter
normal
repeated
comparisons
regression
approximation
third
component
best-fit
line
correlating
measured
approximated
according
specific
equations
time-delay
parameter
values
emitting
daughter
isotopes
separate components
daughter isotope
neutron detection
detector apparatus
time required
transit time
time delay
reactor coolant
heat exchange
nuclear reactor
heat exchanger
spaced apart
coolant flow
neutron detector
improved apparatus
primary heat
delay time
reactor operation
transit times
normal reactor
components including
third time
parameter values
delayed neutron
cladded fuel
neutron detectors
flow time
detectors mounted
teaches improved
neutron activity
separate component
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