EXTENDE

The RT simulation module can compute direct and scattered radiation produced by an X-ray or Gamma-Ray source.

The user can easily and rapidly define its control configuration: Test piece selection, source definition, detector, possibility to insert several flaws, positioning of source and detector, and finally computation options.

Digital Radiography can also be simulated.

Simulation Examples

Result of a simulation of a stiffener radiographic testing: 3D view, photons path, image of the optical density, curves extraction

Result of two different pipes welding

Specimen

Parametric geometries and CAD files

The graphical interface allows the user to define the following geometries for the specimen:

• Canonical ones: Planar, cylindrical, conical
• Predefined component: Nozzle, Weld templates (13 different bevel profiles available), Turbine blade root and groove, Through Wall Penetration, Elbow
• 2D CAD files containing a profile and generation of the 3D geometry either by translation or rotation of the profile: The profile can be homogeneous or heterogeneous. It can be defined either by CAD import (DXF or IGES format) or directly drawn by the user inside the 2D sketcher of CIVA
• 3D CAD files (STL, IGES or STEP format): Homogeneous or heterogeneous solids, assembled structures with different solids. It is also possible to import several objects and simulate some backscattering phenomena

CIVA can also export specimen geometries in IGES format.

Examples of component geometries

Materials

The material is defined from an available database including more than 110 elements and alloys, with the associated cross-section data. The specimen can be homogeneous (1 single material) or heterogeneous.

Source

Radiation:

• X-ray Source: One defines the intensity of the source in Ampere and the spectral contents of the photons radiated by the source. This spectrum can be defined:
  • By selection in a catalogue proposing predefined ones (Birsh-Marshall)
  • By manual settings
  • By using a spectrum calculator embedded in CIVA based on the physical parameters of the source entered by the user: anode ( angle & material) & voltage
• Gamma Source: One defines the activity of the source in Gbq and the radiated rays. The more classical ones are already predefined: Cobalt 60, Iridium 192 & Selenium 75

Emission zone: One limits the effective zone of radiation in space with a conical or cylindrical volume. The effective size of the source (anode target with X-rays, radioactive capsule in Gamma) can be assumed as an ideal spot or not, allowing to account for geometrical unsharpness.

Detector

The detectors can be planar or curved. Several ways to define them are possible:

• Simple selection among a list of 16 industrial films of different classes bases on EN584-1 standard.
• Image plates of high sensitivity or high resolution including reinforced screen.
• Definition of all the parameters by the user (gain, material of the sensitive layer, sensitometric curve, etc.)

It is possible to take into account the granularity of the film. For any type of film, a filter can be added. A region of interest (ROI) can be used to increase the resolution of the computation at one part of the detector.

A MTF curve can be added for any type of detectors and an automatic MTF can be computed by CIVA for image plate detectors.

Flaws

Several flaws can be inserted in the test piece. They can have different shapes: Planar, spherical, ellipsoidal, trapezoidal, or an arbitrary 3D CAD geometry as well as calibration holes: Flat bottomed Hole, Side Drilled Hole or Hemispherical Bottomed Hole. Flaws can be made of void, gas or solid. It can be an alloy.

Examples of different types of flaws in a weld

IQI

A large library of the main standards IQI (EN, ASTM, AFNOR, DIN62, and CERL) and penetrameters is included in CIVA: Wire (simple, or duplex), Plate with holes, step wedge, etc.

Some of the IQI available in CIVA

Results

Two combined methods (analytical Beer-Lambert & Monte-Carlo) compute both the direct radiation and the scattered radiation. The build-up (ratio direct/scattered) is also available in order to estimate the importance of scattering in a given inspection. Scenario of parametric variations can be defined.

For Monte Carlo computations, the algorithms benefit from multi-core architectures in order to reduce calculation times. Moreover, if this calculation has been done once, and that user wishes to study the variation of a parameter that does not impact the scattering (variation of the exposure time for instance), the Monte-Carlo can be re-used in the new configuration and associated with a new and fast direct computation.

Users can visualize both the detector response (optical density or gray levels) as well as the incident dose in Gray or the deposited energy on the detector in keV. Results are presented as images in the classical CIVA environment as well as curves following selected cross sections, allowing the user to easily quantify local variations of contrast. The cursors are dynamically linked to the 3D graphic view and the photons paths are plotted. The thicknesses of materials passed through are indentified in a table. The images obtained can be exported in the Tiff or raw format.

POD calculations (Probability Of Detection) are also now available in RT, based on the accounting of uncertain input parameters.

Since CIVA 11, post-processing capabilities have been offered to the user who can quickly re-calculate the activity of the gamma source, the intensity of the X-ray source, or the relevant exposure time necessary to reach a targeted optical density. In the same way, the optical density can be quickly recalculated if these 3 parameters change.

Some detectability criteria based on the smallest surface interpretable by the eye has also been implemented. This criterion will help the user to define the flaw detectability.