ORCHID - a computer simulation of the reliability of an NDE inspection system
CANDU pressurized heavy water reactors contain several hundred horizontally-mounted zirconium alloy pressure tubes. Following a pressure tube failure, a pressure tube inspection system called CIGARette was rapidly designed, manufactured and put in operation. Defects called hydride blisters were found to be the cause of the failure, and were detected using a combination of eddy current and ultrasonic scans. A number of improvements were made to CIGARette during the inspection period. The ORCHID computer program models the operation of the delivery system, eddy current and ultrasonic systems by imitating the on-reactor decision-making procedure. ORCHID predicts that during the early stage of development, less than one blistered tube in three would be detected, while less than one in two would be detected in the middle development stage. However, ORCHID predicts that during the late development stage, probability of detection will be over 90%, primarily due to the inclusion of axial ultrasonic scans (a procedural modification). Rotational and axial slip could severely reduce probability of detection. Comparison of CIGARette's inspection data with ORCHID's predictions indicate that the latter are compatible with the actual inspection results, through the numbers are small and data uncertain. It should be emphasized that the CIGARette system has been essentially replaced with the much more reliable CIGAR system.
- Research Organization:
- Ontario Hydro Research Division, Toronto
- OSTI ID:
- 5857209
- Journal Information:
- J. Nondestr. Eval.; (United States), Vol. 6:1
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
36 MATERIALS SCIENCE
BLISTERS
DETECTION
CANDU TYPE REACTORS
INSPECTION
PRESSURE TUBES
EDDY CURRENT TESTING
FAILURES
ULTRASONIC TESTING
TEST FACILITIES
O CODES
RELIABILITY
SYSTEMS ANALYSIS
ZIRCONIUM ALLOYS
COMPUTERIZED SIMULATION
HYDRIDATION
HYDROGEN EMBRITTLEMENT
PROBABILITY
ACOUSTIC TESTING
ALLOYS
CHEMICAL REACTIONS
COMPUTER CODES
ELECTROMAGNETIC TESTING
EMBRITTLEMENT
HEAVY WATER MODERATED REACTORS
MATERIALS TESTING
NONDESTRUCTIVE TESTING
PRESSURE TUBE REACTORS
REACTORS
SIMULATION
TESTING
THERMAL REACTORS
TUBES
210400* - Power Reactors
Nonbreeding
Otherwise Moderated or Unmoderated
360105 - Metals & Alloys- Corrosion & Erosion
360103 - Metals & Alloys- Mechanical Properties