From: lachlan@dmp.csiro.au (Lachlan Cranswick)
Subject: Re: Brehmstrehhlung X-rays - Safety
Organization: CSIRO Division of Mineral Products, Melbourne, AUSTRALIA
Date: Thu, 28 Jan 1993 10:06:01 GMT

jgd@dixie.com (John De Armond) writes:

>lachlan@dmp.csiro.au (Lachlan Cranswick) writes:


>>1cm from the source.  This gives two complete levels of safety on our
>>diffractometers which some people would argue is total overkill.

>This is unfortunate because it makes a mockery of radiation safety.  It
>opates those who abstractly fear radiation but for those with some knowledge
>of radiological procedures, it is the radiation equivalent of crying
>wolf.  Pretty soon the mockery destroys confidence in the system.  People
>begin to assume that ALL radiological hygene procedures are "wolf crying"
>and ignore them.

If I may beg to differ - good safety design and technology can make
methods and procedures more convenient - there is no reason
why safety has to be a synonym with inconvenience.

Using Powder X-ray Diffraction may not be "directly"
analogous with the original post as when you turn the
power off on an X-ray generator - the radiation "threat"
ceases.  However, in the "bad old days", of Powder
X-ray Diffraction, safety was reliant mainly on users'
common sense and best practise.  Safety switches were not that common such
that a user would always have to remember to manually turn
off the "X-rays" shutter, manually take out the sample, insert
a new sample (manually), and turn on the shutter again.
If you have 40 samples, you have to do this 40 times.
Now as it is not uncommon for people to occassionally make
mistakes, you can see the potential for a finger burn.

What happens now? (If I can use a Philips system with a
1775 automatic sample changer as an example).
The user loads a cassette with up to 40 samples 
and slots the cassette into the sample changer.  The user goes
away to a PC and instructs the Diffractometer via the PC to run
all the samples (the PC is a safety device in itself as
the instructions are given at a distance from the radiation
source). The user is now free for the duration of the 
running time to go away and do something else.
Unlike the old days, the user is semi-independent of
safe practises.  I can only personally vouch 
for modern Philips equipment, but
you would have to be very motivated to try and get a X-ray
burn.  Because of good design, nothing above background
radiation levels from the machine is expected (this
doesn't mean you stop regular radiation monitoring).

A sister site in Western Australia that does a lot of little
mods to their goniometer - designed and installed a full-enclosure
that is connected to counter-weighted pullies.  When they
want to do a mod, the whole full-enclosure goes into
the air to give them full access.

While adding a full-enclosure to a machine that already
has a full goniomter shield (as we are doing) may seem overkill,
it is definitely a positive corperate statement on safety.
Also, while full-eonclosures are not required in Victoria, this is
not the case in other Australian states.  And as safety standards
are always getting tougher, you may as well go
"over the top" now rather than be forced by law later.
(PS:- Didn't the Russians think a containment vessel on nuclear
reactors a Western Capitalist trick to "artificially"
increase capital cost?)


If I can try to relate this to the original post.
I interpreted the essence of this that the author
was annoyed at some rather cumbersome and ad-hoc
safety procedures.  This implied to me that if
safety equipment had have been well designed,
there would have not been a problem.  Given the
technology is out there, I think that background
levels should be "achievable" in all situations with
either the same level of convenience or better.
Its a matter of good design and motivation.

On the comment about overly excessive safety practises destroying
confidence in procedures:- if done well, users wouldn't want
to get around the safety devices and wouldn't
be given the choice because of good design.

Now, If I had have said you should try to go for
less than background levels - then I may be open
for charges of irrational paranoia.
(I remember hearing that the Japanese - after WWII -
used to have lead lined walls on all their low-level
radiation labs (including X-ray Diffraction labs).
Is this true and is it still practised?)

Please feel free to ignore the above opinions,  Lachlan.
-- 
  Lachlan Cranswick  -  CSIRO             _--_|\  lachlan@dmp.CSIRO.AU
  Division of Mineral Products           /      \ tel +61 3 647 0367
  PO Box 124, Port Melbourne 3207        \_.--._/ fax +61 3 646 3223
  AUSTRALIA                                    v 
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