Our University’s former Safety-Office-in-Chief, who retired about ten years ago, had a line in horror stories while presenting training lectures.  One of his “things” was always radiation checking a new piece of equipment before releasing it for use.

One of our departments had purchased a new X-ray generator system, and all the paperwork was in order.  But John was having none of that, and powered it up and went around it with his radiation monitor.  Loads of radiation coming out!  And at a level that would cause gentlemen great concern (and ladies too, but men’s brains seem to be located at that level.)

What had happened was that the company had been taken over during the manufacturing process.  During the transfer of responsibility, a very important bit of shielding had not been installed, and the equipment had gone out without this important element.  Of course, both the before and after companies took the line that “it was them, guv”, and nothing could be made to stick.

Was this a one-off?  No way, José.  We (a group including me) were generous given an old but very functional (and still functioning) scanning electron microscope that was looking for a home as the result of the closure of our country’s Central Electric laboratories, I think when the board was broken up in to several companies and privatized.

Around came John with his radiation monitor.  Lo and behold, radiation coming out the back!  Here, with a grossly over-simplified diagram by myself which will probably only confuse things, is what had happened.

This represents a plan view of the column containing the electron gun.  The main column, represented by A, does let some radiation out the back (facing left in the diagram.)  The extra shielding (represented by blue arc C) fits into a locating ring with three holes B-B-B.  However, the instrument had been partly disassembled during transport, and on reassembly, the equilateral nature of ring B had allowed the shielding to be placed in one of the positions D.

The situation was not as dire as in the previous episode, but anyone working round the back, say servicing the microscope or even just topping up the liquid nitrogen for the elemental analysis detector, could have got more radiation than was good for them.

So, watch out for Company Transfer Radiation!