Modified night-vision goggles show up radioactive spills

[Muckerheide <muckerheide@MEDIAONE.NET>]

An interesting concept, from New Scientist magazine:



Regards, Jim

===========



Glow for it



Modified military night-vision goggles show up radioactive spills as a glow

in the dark 



Exclusive from New Scientist magazine



One of the problems with radioactive contamination is that it is invisible.

Smoke blackens, oil stains, chemicals discolour, but you can't actually see

dangerous ionising radiation with the naked eye.



But now a British company is working on a system that shows up radioactivity

as a glow in the dark. With a pair of modified military night-vision

goggles, scientists monitoring radioactive contamination at the scene of a

possible spill would be able to spot smears of alpha-emitting radionuclides

such as plutonium.



The radiation goggles designed by British Instrument Consultants (BIC) in

Warrington, Cheshire, are based on an old technique. Early last century,

nuclear pioneer Ernest Rutherford saw the flashes of light given off by zinc

sulphide when it is struck by alpha particles. The effect, known as

scintillation, is commonly used in radiation monitors which convert the

flashes of light into electronic signals.



BIC wanted to find a way of boosting the weak flashes given off by low

levels of radioactivity until they're visible to the human eye. To do this,

the company took a pair of night-vision goggles and tuned them to highlight

light wavelengths emitted by scintillating zinc sulphide.





Nooks and crannies







The result, according to BIC spokesman Mike Scott, is that you can see alpha

contamination as low as 30 becquerels per square centimetre as an intense

glow on the goggles' green monochrome screen. "The main advantage is being

able to measure contamination of unusually shaped objects," he says. "With

standard probes it's very difficult to get into nooks and crannies."



 



The goggles, which have been tested at the University of Liverpool, would

also enable staff monitoring an area to keep well away from contamination.

One disadvantage, though, is that you have to spray zinc sulphide onto the

area under investigation.



Furthermore, you can only use the goggles out of doors at night because

daylight swamps the sensitive electronics, though filters might make it

possible to see the glow in ambient light, Scott says.





Hot spots







Nevertheless, Scott says some of the major players in the nuclear industry,

including the UK Atomic Energy Authority (UKAEA) and British Nuclear Fuels

(BNFL) have already expressed an interest.



The goggles could be useful in identifying hot spots of plutonium

contamination at the nuclear plants being decommissioned at Dounreay in

Caithness and Sellafield in Cumbria, he argues.



Scott, a physicist who has specialised in radiation measurement, accepts

some people would prefer a device that could detect lower levels of

contamination and other forms of radioactivity.



But he is confident that he can improve his design to highlight

contamination down to 10 becquerels per square centimetre. He is also

planning to investigate other materials such as plastics that are

susceptible to scintillation from beta, neutron and gamma radiation.



Peter Burgess from Britain's National Radiological Protection Board says

that while BIC's idea is a clever notion, he is worried that spraying

potentially contaminated areas with zinc sulphide might send radioactive

particles into the air and worsen the clean-up problem.



But the UKAEA believes the technology "sounds very interesting" and could be

useful. "But we need to reserve judgement until we have seen it

demonstrated," a spokesman says. BNFL takes a similar tack, arguing that the

goggles are the "spark of an idea" that needs more work and testing before

they would be willing to use them.



Correspondence about this story should be directed to

letters@newscientist.com



1900 GMT, 14 March 2001



Rob Edwards, Edinburgh





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