BS ISO 20890-1:2020

What is ISO 20890‑1 about? 

ISO 20890‑1 is the first part of the multi-series European standard that specifies guidelines for pre-service-inspections (PSI) and in-service inspections (ISI) with mechanized ultrasonic test (UT) devices on components of the reactor coolant circuit of light water reactors. ISO 20890‑1 is also applicable to other components of nuclear installations. 

ISO 20890‑1 is applicable for the detection of indications by UT using normal-beam probes and angle-beam probes both in contact technique. It is to be used for UT examination on ferritic and austenitic welds and base material as search techniques and comparison with acceptance criteria by the national referencing nuclear safety standards. 

Note: Unless otherwise specified in national nuclear safety standards the minimum requirements of this document are applicable. 

Note: ISO 20890‑1 does not define: 

• Extent of examination and scanning plans 
• Acceptance criteria 
• UT techniques for dissimilar metal welds and for sizing (have to be qualified separately); 
• Immersion techniques 
• Time-of-flight diffraction technique (TOFD) 

And Immersion techniques and techniques for sizing are not in the scope of ISO 20890‑1 and are independent qualified. 

Who is ISO 20890‑1 for? 

ISO 20890‑1 on light water reactors is relevant to: 

• Nuclear power plants 
• Nuclear research organisations 
• Mechanical Engineers 
• Physicists 
• Nuclear research scientists and researchers 
• Nuclear regulatory authorities 

Why should you use ISO 20890‑1? 

ISO 20890‑1 provides guidelines on mechanized ultrasonic inspections of reactor coolant circuits of light water reactors, which are carried out to enable an evaluation in case of 

• Fault indications (e.g. on austenitic weld seams or complex geometry) 
• Indications due to geometry (e.g. in case of root concavity) 
• Complex geometries (e.g. fitting weld seams) 
• If a reduction in the radiation exposure of the test personnel can be attained in this way 

ISO 20890‑1 provides mechanised ultrasonic test methods used to define the validation of discontinuities (volume or surface open), requirements for the ultrasonic test equipment, for the preparation of test and device systems, for the implementation of the test and the recording. 

Overall, ISO 20890-1 establishes guidelines for preservice and in-service inspection of reactor coolant circuits using automated ultrasonic testing devices which will benefit the users as they can inspect the components earlier than they will break down and therefore save from any accident conditions.