Dose recording on Pocket dosimeter -- Is it accurate for a person's whole body?

[Salman Khan]

Pocket dosimeter consists of a small ionization chamber, if a person having pocket dosimeter moving in a radiation environment, how the dose received by the man is equivalent to the dose showing on pocket dosimeter although the exposed area of a man is quite larger than the dosimeter ?

 

[.Scott]

The dosimeter measurements are intended to be a "representative exposure". A presumption is made that the radiative field is uniform and that the dosimeter exposure will be proportional to the exposure of the person wearing it. In situations where the field is often not uniform, more than one dosimeter can be distributed on you - for example, in you shirt pocket, right and left wrist, whatever.

Generally, these dosimeters (or the results from them) are forwarded to a lab for interpretation. Commonly, the lab will know your age, height, BMI, and the type of radiation present in your work environment. So, if appropriate, they have the option of adjusting their report on the severity of the exposure to your size.

 

[Salman Khan]

Ok the thing which I got from your answere is, if the field is suppose to be a uniform then the dose recorded on let say a pocket dosimeter wearing by the worker will be not equal to the total actual dose received by the worker, due to the the small area of dosimeter as compare to the whole body of the worker, which wll be later on calculated according to his hight bmi etc. Please correct if I got wrong. Thanks

 

[.Scott]

Ok the thing which I got from your answere is, if the field is suppose to be a uniform then the dose recorded on let say a pocket dosimeter wearing by the worker will be not equal to the total actual dose received by the worker, due to the the small area of dosimeter as compare to the whole body of the worker, which wll be later on calculated according to his hight bmi etc. Please correct if I got wrong. Thanks

Yes. But I would add that a "pocket dosimeter" is intended for your shirt pocket - in proximity to you vital organs. Not all human organs are created equally susceptible to radiation.

 

[gmax137]

To be reliable, dosimetry and associated calculations have to be appropriate to the work and working environment. Walking thru the plant is not the same as jumping steam generators.

 

[berkeman]

not the same as jumping steam generators.

I hesitate to ask, but what is involved in that activity...?

 

[gmax137]

In the old days, PWR steam generator tube inspection required someone to manually place the Eddy current probe in each tube, which meant you had to "jump" into the primary side plenum. The shine from the tube sheet was such that you got quarterly dose in something like 60 seconds. So we engineers trained to do this, leaving the outage tasks requiring more skill to the guys who did that stuff full time. Nowadays they have robots to move the probe from tube to tube, so it is an obsolete task.

They put dosimeters on our heads, being closer to the tubesheet.

 

[berkeman]

The shine from the tube sheet was such that you got quarterly dose in something like 60 seconds.

Holy crap. Glad you are still with us.