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EDF has listed the approved PT products--and, for this purpose, many other products for NDT and non-NDT applications--as per the PMUC process/lists. PMUC comes as the acronym, in French, of: Products and Equipments suitable for use in Nuclear power plants.

 

- Water-washable colour contrast penetrants supplied in bulk or in spray cans.

 

- Level 2 water-washable fluorescent (under UV-A radiation) penetrants supplied in bulk or in spray cans.

 

- Degreasers supplied in spray cans, bulk or as wipes.

 

- Non-aqueous wet developers supplied in bulk or in spray cans.

 

- Thixotropic colour contrast penetrants supplied in bulk.

 

- Level 2 fluorescent (under UV-A radiation) thixotropic penetrants supplied in bulk.

 

- High temperature colour contrast penetrants supplied in bulk or in spray cans.

 

- High temperature cleaners supplied in bulk or in spray cans.

 

- High temperature developers supplied in bulk or in spray cans.

 

All of these products are listed: they may be used in nuclear power plants.

 

But many of them are rarely or never seen in power plants.

 

Colour contrast PT products are used almost exclusively.

 

Wondering why this situation one of us conducted an inquiry in EDF -- many years ago.

 

The answer is quite consistent: during power plants assembly, during planned maintenance, in many areas it would be almost impossible to lower the ambient visible light to a level low enough to comply with the standards if using fluorescent products. For a better consistency manufacturing of reactors, vapour-generators, pumps, etc. is checked also using colour contrast PT materials.

 

Nevertheless EDF has anticipated some specific needs: inspection above +50 °C (122 °F), areas where liquid penetrants would be detrimental to the equipment, hence need to use thixotropic materials, etc.

 

Colour contrast PT has allowed for detecting microcracks on the reactors covers, some twenty years ago. This method is still the most widely accepted method to detect open to the surface discontinuities in remote areas using automatic equipments or robots able to perform the inspection; still cameras or video cameras are used and as a matter of course human beings decide whether parts are acceptable or not! Automatic equipments or robots are useful to have inspectors staying out of radiations...but as per our motto, nothing is more valuable to decide than the "old system": sensor (eyes) + signal processor (brain) which has a good track record since dozens of millennia!

 

One small "point-against" though: colour contrast PT has its own limits and we talk about that in a published "oldies-but-goodies" published this month: "Colour contrast penetrant testing: old times young generations will never know!"

 

THE FRENCH ELECTRICITY BOARD (EDF)

AND COLOUR CONTRAST PENETRANT TESTING