RE: some details on St. Lucie

[Jack_Earley@rl.gov]

Mitchell Davis wrote:



<<This sort of thing happens frequently. Not that it is supposed to, but it

just does.  I have been at many plants that during refueling we "lose

containment" to airborne.  It happens for various reasons.  Some

controllable, others not.>>



The AP wrote:



<The company said it has made changes to how it judges radiation levels

inside the plant and now requires all workers who go inside the steam

generator to wear respirators.>>



Ted Rockwell wrote:



<<The only risk associated with low-dose radiation is the possibility of

dropping a lead brick on your toe.  I've seen warning signs about the risk

of skiing at Winter Park, CO, but not a word about the increased cosmic rays

at 11,000 ft.>>





What I seem to be detecting here is a lack of understanding, apparently

starting with my own. TMI-2 lost airborne radioactivity control in the early

80s in the Fuel Handling Building because they didn't think it would migrate

to the upper floors. Yet when we teach contamination control we tell workers

to think of it as working in a flour mill--it's going to get everywhere if

it's not contained. I'm also not seeing adequate engineering controls here.

To me, that would/should be the NRC's main interest. For comparison, 10 CFR

835 (I haven't looked at 10 CFR 20 in a while but it's probably similar if

not identical) requires application of engineering controls; if they're

"demonstrated" (and documented) to be impractical, then administrative

controls are used. If engineering controls and administrative controls

together are inadequate, then (and only then) respiratory protection may be

used (not "shall be").



So I don't understand why the company would automatically revert to

respiratory protection, especially on higher-exposure jobs in the

containment. Wearing respiratory protection slows workers on average by 25

percent, increasing external exposure proportionately. The break-even point

for Co-60 can be less than 30 mR/h--any higher exposure rate and your

increased external exposure exceeds your internal exposure savings (I can

dig up the formula for the break-even point if anyone needs it). So the

points I see are that (1) they had inadequate portable HEPA-filtered

ventilation, which could have prevented migration of the airborne

contamination, (2) they had inadequate training to understand the nature of

airborne contamination and the application of engineering controls, and (3)

even if the ventilation were shown to be inadequate for other workers in the

containment, they can plan for any resulting internal exposure rather than

increasing the total exposure by putting the workers in respirators. The

issue isn't the exposure--it's inadequate understanding and an apparent lack

of engineering controls.



Re. risk--if you look at the back of your lift ticket it will tell you

(similar to horseback riding, attending a hockey or baseball game, etc.)

that it's an inherently risky venture and you need to be responsible for

your own safety (and they're not liable if you're not).



Jack Earley

Radiological Engineer