The paper presents four problem-solving cases for sizing the outer surface cracks for the following components of CANDU nuclear generation station: steam generator lug welds, outlet weld of steam chest valve, bleed condenser inlet nozzle weld and primary circuits piping welds mock-ups for inspection qualification. The design, manufacture and performance assessment of miniature and sub-miniature 1-D linear phased array probes of high frequency (5-12 MHz) are commented and illustrated. A novel calibration technique on EDM notches and validated on fatigue cracks with known height is commented and illustrated. PAUT data were used for return-to-service decision for ECA engineering. It was found the PAUT is undersizing by 0.2-0.5 mm the real fatigue cracks and oversizing by 1 to 3 mm the implanted cracks.

The paper presents analysis of ultrasonic data acquired with conventional and PAUT (namely) on welded mock-ups with implanted flaws used for Inspection Qualification of CANDU ferritic piping welds. Some of the data were double-checked by TOFD. All data were compared to RT film interpretation. The following techniques were used: - 6 dB from the flaw sides and min-max (noise at 10-20% FSH and flaw amplitude saturated and measured at 100% FSH). The influence of beam spread, UT path and refracted angle was also presented. Flaws with smaller length < 8 mm will be oversized by 2 to 6 mm. It was found the -6 dB from sides (non-saturated) undersize the flaw length by 2-5 mm due to irregular amplitude variation along the flaw length (B-scan display) and low amplitude response of flaw edge; the min-max technique oversize by 3-6 mm the flaw length. TOFD and PAUT are within +/- 3 mm accuracy. Some weld flaws located in the weld preparation or in misalignment were missed (undetected) by RT. For conventional UT of 2.25 MHz (45⁰ and 60⁰ shear waves) the length accuracy has a maximum band spread of ? 10 mm. PAUT has an accuracy of ? 5 mm, similar with TOFD. There is no need to re-scan weld locations with flaw which saturate the amplitude. Min-max technique oversize the length within ? 10 mm error band. The experimental project regarding the length sizing for Inspection Qualification fulfills the ASME XI IWB-3514-1 requirements and ECA (safety factor of 2).

The paper presents experimental results for conventional ultrasonic probes of 2.25 MHz and 12.7 mm diameter / 45?a and 60?a refracted angles in ferritic steel on EDM notches, weld implanted flaws and turbine components cracks for length sizing. It was found the -12 dB technique is oversizing by 3-7 mm the length of EDM notches compared to -6 dB drop technique. The oversizing trend increases with ultrasonic path. Another experiment was performed to assess the influence of frequency (2.25 MHz, 3.5 MHz and 5 MHz) on length sizing of 5-, 10- and 15-mm EDM notches. It was found the higher frequencies reduce the oversizing length sizing error only on small target of 5 mm by 2-3 mm. Examples of field sizing on turbine components concluded the -12 dB technique is closer to reality and almost identical with min-max technique (saturated amplitude). A comparison between PAUT probes of different frequency and similar active area is presented for -6, 12 and mix-max techniques. Amalgamated results (conventional-both angles and PAUT on weld flaws) are compared to length measured on RT films. As a general recommendation: small flaws with length 10 mm should be sized by -6 dB technique. Flaws with length > 10 mm should be sized by -12 dB or -6 dB from the edge. If the flaw amplitude response is uneven and the edge of the flaw (namely SCC in turbine components) is difficult to be displayed in B-scan, use -12 dB or min-max techniques. All three techniques (-6, -12 dB and min-max) size the flaw length within the acceptable tolerances for performance demonstration / inspection qualification procedure.

After build-in to the structure, most building materials contain some amount of moisture which may significantly affect physical and mechanical properties and durability of the material too. The paper is focused at studying thermal moisture properties related to various types of cellular concrete materials with density ranging from 300 to 400 kg.m-3, the materials which are currently appearing in the construction market of the Czech Republic. This is essentially about studies of sorption characteristics for every individual type of materials and about studies of their thermal insulation properties` dependences on moisture content.