[ RadSafe ] Re: Fw: Someone just responded to your comment

[Mercado, Don]

John Jacobus wrote: 

>Don,
>I do not base my judgement on the LNT or what I think
>about it.  I consider what is actions are need to get
>the work done and keep down radiation exposures.

Then you DO think about LNT. You balance getting the necessity of
getting the work done with the time/expense of keeping exposures down.
If it extends the work time by 16 hours by changing the work procedure
to reduce exposures by 100 mrem, would you do it or not? How about 3
hours? One hour? Ten minutes? If you are a fan of LNT, yes, you do. If
you are not, no you don't.

>I thought that is what ALARA is all about.

ALARA is a concept that allows HP professionals to use their judgment.
It's the "R" in ALARA that we are talking about. What is "Reasonable"
has a cost associated with it. What does $XXX buy you?

>If spending $100 for shielding, that is a good
>investment as the material could be used again.

What are the associated costs of that "$100 for shielding"? Design time,
ordering time, waiting for delivery time, installation costs and time,
etc. That shielding costs more than $100. That $100 really doesn't buy
you much protection at all if that's all you are going to *really*
spend. How much additional health/harm prevention does that $100 get
you? Non-LNT fan: none. LNT fan: Nothing quantifiable. So what's the
point in spending the money?

>If having a worker receive some radiation exposure in
>completing a job, that is what their job is.  The
>issue I think is whether or not anything can be done
>to reduce exposure.  

The issue is whether it is "reasonable" to do something to reduce the
exposure.

>By the way, on the first nuclear powered submarines,
>e.g, USS Nautilus SSN-571, etc., there was a 20 second stay-time for
crew members as they went aft over >the reactor. There was no shielded
tunnel over the reactor compartment. 

Spacecraft designers want to know how much radiation their parts are
being exposed to when we x-ray them. Because of the circumstances, we
can't use a shielded room. We have to x-ray them as installed on the
spacecraft. To get the numbers the designers want, I start way back from
the machine, stand in the primary beam and walk toward it with a survey
instrument until I find the 100 mR/hr distance and then do inverse
square calcs. Takes me all of about 2 minutes in the beam. Big deal.
Doesn't even show up on my dosimeter. To test to see if interior room
warning lights, emergency shut down switches, etc. work in a shielded
room installation I go into the room, close the door, have the operator
turn on the x-ray, confirm that it is running with my survey meter, and
hit the switch, and confirm that it is shut down. 15 seconds. Again, it
doesn't even show up on my dosimeter. It is "reasonable" to have the
operator set the machine to low kVp and mA to reduce exposure to me. It
is not reasonable to install a remote operating system to test the shut
down switches or a video camera to see if the light is working.  

>To tell you the truth, the only time I think about the
>LNT is when I get messages from this list server.  Do
>you think about the LNT a lot?

Yes I do. There's a situation at least once a week where I have to think
of what is "reasonable". Being reasonable costs money. LNT is a big
factor in costs of operations.