BS ISO 20890-4:2020 pdf download.Guidelines for in-service inspections for primary coolant circuit components of light water reactors
3.19 reference block
piece of material, with specified metallurgical, geometrical and dimensional characteristics, used for calibration and assessment of equipment for visual testing
Note 1 to entry: Specified metallurgical, geometrical and dimensional characteristics means for example material, weld seam implementation, form, wall thickness, any cladding present) with reference characteristics (e.g. grooves, bores) that are adapted to the test assignment.
Note 2 to entry: Depending on the test assignment, the properties relevant to the inspection technique can be determined by hue (3A) colour intensity (3,3), reflectivity or texture of the surface.
4 Inspection technique
Visual testing is used to recognise deviations from the expected state. This state is specified in the test procedures. Depending on the test assignment, the visual testing is conducted either as a general visual testing or a selective visual testing. Depending on the accessibility and required detail recognition, direct or remote visual testing is used, whereby the latter can be carried out as a mechanized visual testing. The local radiation dose rate shall be considered when selecting the inspection techniques and auxiliaries.
The suitability of the inspection technique and the combined device system shall be validated according to the requirements of the applicable nuclear safety standards.
NOTE 1 The procedure for the qualification of the inspection techniques or the combined device system is described in ENIQ report nr. 31131.
NOTE 2 The visual testing test method discussed in this document involves a standardized test method whose application is realised based on standard test procedures relating to nuclear power plants. A qualification as above can be necessary in individual cases if there are significant deviations from the specifications from the test procedures.
A general test procedure shall be prepared. Annex B contains the items of the general test procedure.
5 Requirements
5.1 Test personnel
5.1.1 Task of NDT personnel
NDT personnel[4] have a great responsibility, not only with respect to their employers or contractors but also under the rules of good workmanship. The NDT personnel shall be independent and free from economic influences with regard to his test results, otherwise the results may be compromised. The NDT personnel shall be aware of the importance of his signature and the consequences of incorrect test results for safety, health and environment. Under legal aspects, the falsification of certificates is an offence and judged according to the national legal regulations. A tester may find himself in a conflicting situation about his findings with his employer, the responsible authorities or legal requirements.
Finally, the NDT personnel is responsible for all interpretations of test results carrying his signature. NDT personnel should never sign test reports beyond their certification (see Table 1).
NOTE For reasons of readability, the male form is used with personal names, however the female form is also always intended.BS ISO 20890-4 pdf download.