BS ISO 20890-4:2020 pdf download – Guidelines for in-service inspections for primary coolant circuit components of light water reactors Part 4: Visual testing
4 Inspection technique
Visual testing is used to recognise deviations from the expected state.This state is specified in the testprocedures. Depending on the test assignment, the visual testing is conducted either as a general visualtesting 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 visualtesting.The local radiation dose rate shall be considered when selecting the inspection techniques andauxiliaries.
The suitability of the inspection technique and the combined device system shall be validated accordingto the requirements of the applicable nuclear safety standards.
NOTE1 The procedure for the qualification of the inspection techniques or the combined device system isdescribed in ENIQ report nr.31.
NOTE2The visual testing test method discussed in this documentinvolves a standardized test method whoseapplication is realised based on standard test procedures relating to nuclear power plants. A qualification asabove can be necessary in individual cases if there are significant deviations from the specifications from thetest procedures.
Ageneral test procedure shall be prepared.Annex B contains the items of the general test procedure.5 Requirements
5.1.1 Task of NDT personnel
NDT personnell4 have a great responsibility, not only with respect to their employers or contractorsbut also under the rules of good workmanship.The NDT personnel shall be independent and free fromeconomic influences with regard to his test results, otherwise the results may be compromised.TheNDT personnel shall be aware of the importance of his signature and the consequences of incorrecttest results for safety, health and environment. Under legal aspects, the falsification of certificates is anoffence and judged according to the national legal regulations.A tester may find himself in a conflictingsituation 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 isalso always intended.
The test personnel comprise the test inspector, the test supervisor and possibly the operating personnelfor the test robot.
Those personnel, using qualified non-destructive testing (NDT) procedures and equipment, should be qualified through one or any combination of the following:
— certification through a national NDT personnel certification scheme;
— theoretical and/or open trials; — blind trials. Any personnel certification requirements invoking relevant national NDT personnel certification schemes (e.g. ISO 9712) should be validated according to Table 1. Any additional personnel training requirements should also be specified in the qualification dossier. If no relevant scheme exists or if extra personnel qualification is needed, the qualification body should determine the additional practical and theoretical examinations needed beyond those in the national certification scheme, include these in the qualification procedure and ensure that the NDT procedure also includes the necessary requirements.
The qualification procedure should describe the proposed system. The test supervisor is responsible for the application of the NDT qualified system and shall have the knowledge required for his tasks as well as sufficient knowledge of the application options and limitations of the test methods and have knowledge about the characteristic appearances of operationally induced faults. Conspicuous indications requiring more extensive measures shall be evaluated by the test supervisor, who has the requisite experience in respect to the test object, test assignment, test method and combined device system.
The test inspectors shall have the skills to perform the work they are to carry out. In particular, they shall have sufficient experience in conducting visual testing and knowledge in respect to this concerning the test object and appearance of conspicuous indications that can result during operation.
The operating personnel for test robots and the test inspectors during mechanized testing shall be trained for the requirements of the work to be carried out. Test personnel performing NDT and the evaluation of the results shall be qualified in accordance with ISO 9712 or equivalent at an appropriate level in the relevant industrial sector.