NB/T 20003.3-2021Non-destructive testing for mechanical components in nuclear island of nuclear power plants - Part 3: Radiographic testing (English PDF)

3.1 penetrated thickness

T nominal thickness of material in the direction of radiography. In multilayer radiography, it is the sum of nominal thickness of penetrated layers of materials

3.2 object-to-film distance

b distance between the surface of the workpiece under test on the side of the radiographic source and the film measured along the centerline of the ray beam

3.3 source-to-object distance

f distance between the ray source and the surface of the workpiece under test on the side of the radiographic source measured along the centerline of the ray beam

3.4 source-to-film distance

F distance from the radiation source to the film measured along the centerline of the beam

3.5 source size

d converted size of the radioisotope source or the effective focal size of the X-ray tube

3.6 standard density tablet

calibrated radiographic negatives with different density steps

3.7 rounded defect

welding defects such as porosity, slag inclusion and tungsten inclusion with length-width ratio not greater than 3

3.8 elongated defect

welding defects such as porosity, slag inclusion and tungsten inclusion with length-width ratio greater than 3

4.1 Testing personnel

The general requirements of radiographic testing personnel shall meet the relevant requirements of NB/T 20003.1.

Radiographic testing personnel shall receive training and assessment on radiation safety knowledge before taking up their posts, and shall obtain corresponding certificates in accordance with relevant regulations. The uncorrected or corrected near vision of radiographic testing personnel shall not be less than 4.8, and the test method shall meet the requirements of GB 11533. Film-assessing personnel shall have a visual acuity test once a year.

4.2 Testing documents

Radiographic testing documentations, including testing procedures, testing process card or other testing documents, shall meet the requirements of NB/T 20003.1. Radiographic testing shall be implemented according to effective testing procedures.

Radiographic testing procedures shall at least include the following content:

- - Scope of application: type, size, testing range and material of the workpiece under test;

- - Quoted laws, regulations, standards, design documents, etc.;

- - Qualification of testing personnel;

- - Testing equipment and materials: radiographic source, film, intensifying screen, filter, masking board, image quality indicator, mark, film processing equipment in darkroom, film-assessing equipment, etc.;

- - Testing conditions: surface state, testing time, etc.;

- - Testing technology: radiography mode; exposure parameter; cassette composition (film type and quantity as well as intensifying screen); model, quantity and arrangement of image quality indicator; and type and arrangement of mark;

- - Darkroom processing of films;

- - Radiograph quality: radiograph marking, radiograph density, image quality indicator sensitivity of radiograph, etc.;

- - Defect evaluation, quality grading and acceptance criteria;

- - Content and format of test report.

4.3 Verification of procedures

Verification of testing procedures shall be performed when:

- - the testing procedures are used for the first time;

- - the specified value or numerical range of important variables in the testing procedure in Table 1 changes;

- - specified in relevant product design documents or procurement specifications.

The reference radiographs shall be used as the main basis for procedure verification. The reference radiograph may be taken separately or selected from the qualified radiograph of the workpiece under test. In both cases, the reference radiograph shall be marked.