What makes a suitable linear measurement device for a radioactive environment?

[mistry]

Hi, I am on a placement year with an engineering company who design tools for the nuclear industry. One of the tasks I have been given looks at what linear measurement devices can be used in a radioactive environment? I havn't been able to find much and was wondering if anyone could point me in the right direction. I am basically looking at what can be used to replace the current mechanical device and has the capabilites of being used in a reactor.
Thanks is advance
Am

 

[FredGarvin]

Let's start by listing some of the known selection criteria you need. What distinguishes an instrument that can be used in a radioactive environment?

 

[berkeman]

Let's start by listing some of the known selection criteria you need. What distinguishes an instrument that can be used in a radioactive environment?

...and whether you need to measure absolute distances or relative displacements. If relative displacements, then non-contact laser interferometry would be a good choice:

http://www.home.agilent.com/agilent...00386.0.00&id=1000000394:epsg:pgr&cmpid=93152

It's rad hard, as long as you can place the laser outside the main vessel, and use optical windows to get the laser into the vessel.

 

[FredGarvin]

The laser device was going to be my first thought, but it depends on quite a few things from what I have seen of them. The OP has no mention of accuracy, length of measurement, what is being measured, etc...

 

[mistry]

Firstly to clarify. the measurment that needs to be taken is of the diameter of the graphite bricks which make up a nuclear reactor core. The measurment instrument needs to be integrated into a 1m inspection unit which performs core montioring of graphite bricks and fuel channels. The idea is to integrate a new measurement device into this tool to allow measurment to be taken. Standard diameter values of anout 600mm. The aim of taking the measurment is to determine if bricks have shrunk or have be misaligned - therefore accuracy is important.

The point : 'what distinguishes an instrument that be used in radioactive environment'.
The criteria that i am currently looking at is - it must be able to work in a hostile environment with changing temperature and pressure. In addition it needs to be easily maintainable because, once it has been deployed in a reactor it becomes radioactive. Also radioation cannon affect the function of the measurement.

Thanks