where expertise comes together - since 1996 -

The Largest Open Access Portal of Nondestructive Testing (NDT)

Conference Proceedings, Articles, News, Exhibition, Forum, Network and more

where expertise comes together
- since 1996 -

TecScan Systems
We offer a complete line of NDT scanners, Immersion Tanks & Gantry systems which incorporate Ultrasonic, Phased Array & Eddy Current technologies.
2662 views
Technical Discussions
rajan
rajan
08:32 Aug-15-2008
expose chart for selinium75

pleas anybody can give me a expose formula or chart for seliniun isotope using gamma radiography


 
 Reply 
 
collin maloney
NDT Inspector, - Plant Inspector
Applus RTD, Australia, Joined Nov 2000, 147

collin maloney

NDT Inspector, - Plant Inspector
Applus RTD,
Australia,
Joined Nov 2000
147
01:30 Aug-21-2008
Re: expose chart for selinium75
----------- Start Original Message -----------
: pleas anybody can give me a expose formula or chart for seliniun isotope using gamma radiography
------------ End Original Message ------------

If you multiply your Ir192 exposures by 4 you will achieve acceptable images.


 
 Reply 
 
Scott Cargill
Scott Cargill
02:53 Aug-26-2008
Re: expose chart for selinium75
----------- Start Original Message -----------
: : pleas anybody can give me a expose formula or chart for seliniun isotope using gamma radiography
: If you multiply your Ir192 exposures by 4 you will achieve acceptable images.
------------ End Original Message ------------

Selinium75 has a constant of 2.2 R per curie compared to Iridium 192's 5.2 R.

Multiply your exposures by a factor of 2.4 x




 
 Reply 
 
Slawomir Mackiewicz
Slawomir Mackiewicz
01:48 Sep-12-2008
Re: expose chart for selinium75
Hi
Rules of thumb given by Scot and Collin (i.e. multiply the exposure time calculated for Ir-192 by a factor 4 or by a factor 2.4) are both equally wrong or… good !

The ratio of exposure constants (dosage rates) for Ir-192 and Se-75 is only a part of the story. These two radionuclides have different energy spectra. For Se-75 main emission lines are between 136 and 280 keV whereas for Ir-192 they are between 296 and 468 keV. As a result Selenium radiation is much ‘softer’ and its linear attenuation coefficient is higher than for Iridium. Their HVL values in steel are respectively 6.2 and 9.2 mm.

It means that exposure chart for Se-75 and Ir-192 have different slopes. As a result there is no single factor connecting exposure times for Ir-192 and Se-75. For example factor 2.4, mentioned by Scott, is good for steel thickness, say 10-15mm, whereas factor 4 mentioned by Collin may be good for thicker plates, say 25-30 mm.

The Rajan request for Se-75 exposure chart can not be simply answered as the exposures required for particular testing conditions are determined by many changing factors, as type/brand of film, thickness of Pb screens, type of processing, mode of processing, type/brand of used chemicals etc. So there are no one universal chart, sliding ruler or computer program good for all RT laboratories.

The solution is purchasing a professional software for exposure calculations (necessary with tuning up/auto-correction function) or preparation the exposure chart reflecting all working conditions of own laboratory.

----------- Start Original Message -----------
: pleas anybody can give me a expose formula or chart for seliniun isotope using gamma radiography
------------ End Original Message ------------




 
 Reply 
 

Product Spotlight

NDTkit RT

NDTkit RT, TESTIA's Digital Radiography software The NDTkit product line software for X-ray analysi
...
s. NDTkit RT is a software benefiting from the Ultis kernel which is dedicated to radiographic image analysis. It offers a set of tools and filtering processes to assist RT operators in finding relevant flaws.
>

Ultrasonic Probe Recharacterization Service

NDT Systems offers a comprehensive Aftercare and Recharacterization Service for all our ultrasonic
...
probes. The Recharacterization Service is fully compliant with International ASTM E1065 Standard Guide (and other applicable standards) and offers complete documentation, traceable to the ASTM E1065 Standard. For more details or to schedule Recharacterization Services contact ndtsales@ndtsystems.com
>

CIVA 2020 UT Module

CIVA NDE Simulation Software is the world leader of NDT Simulation. The UT simulation Module incl
...
udes: - "Beam computation": Beam propagation simulation - "Inspection Simulation": Beam interaction with flaws or specimens The user can simulate a whole inspection process (pulse echo, tandem or TOFD) with a wide range of probes (conventional, Phased- arrays or EMAT), components, and flaws.
>

Compact NDT inspection-heads for measurements with active thermography

The compact inspection head is suitable for thermographic ndt tasks. The uncooled infrared camera
...
is specially developed for NDI-tasks and offers a thermal sensitivity until now known only from thermal imagers with cooled detector. All required components and functions are integrated into the inspection-head. You will only need an ethernet cable to connect the sensor with the evaluation system.
>

Share...
We use technical and analytics cookies to ensure that we will give you the best experience of our website - More Info
Accept
top
this is debug window