Noble Gas Contamination of Personnel - Request for Information

["Leamon, John A." <jaleamon@tva.gov>]

As a result of working in a more competitive environment, our utility is
performing more on-line maintenance than ever before to shorten the
refueling outage duration.  Since Sequoyah is a Westinghouse
Ice-Condenser type plant, we are able to perform numerous activities
inside the containment (reactor) building while the unit is at power.  

Our problem is that the ambient noble gas airborne concentration is
somewhat elevated (10 to 20 DACf - Xe, Ar, Kr) and workers are exiting
the building with residual contamination.  Particulate, iodine, and
tritium airborne radioactivity levels are less than 1 DACf.  

Many workers using the whole body friskers, located at the
Radiologically Controlled Area (RCA) exit, will cause the monitors to
alarm with indications of diffuse whole body contamination.  Those
workers receive a thorough whole body survey by a RADCON technician with
a portable, hand held frisker type instrument.  Workers exceeding the
station contamination limits are instructed to sit in front of ordinary
household cooling fans to wait for dissipation/decay of the
radioactivity.  

Considerable documentation is completed and periodic surveys of the
individuals are performed until contamination levels are acceptable.
Workers with facial or nasal contamination are sent for a follow-up
whole body count.  Additional complications result when those
individuals exiting the site cause the exit portal contamination
monitors to alarm.

My questions to the RADSAFE community are:

1) Are there any provisions we can implement to minimize gas deposition
on and/or in personnel?

2) Are there any personnel decontamination tools/techniques effective
for noble gases?

3) What type of detection instrumentation is most appropriate for this
situation?

4) What contamination levels/limits are most appropriate for release of
individuals from the Radiologically Controlled or Restricted Area (RCA)?

5) Is any confirmatory bioassay or qualitative isotopic analysis
required?  If so, what?

6) If bioassay is required, what are acceptance criteria for release of
personnel from the RCA?

7) What documentation is generated for these events?

8) Is any follow-up action necessary?

9) How are portal monitor alarms handled for personnel with known or
suspected contamination?


Respond directly to me unless you feel the information is of interest to
the RADSAFE audience.  State in your response if you are interested in
receiving a summary of the responses to this post.

John A. Leamon
Health Physicist
Tennessee Valley Authority
Sequoyah Nuclear Plant
P. O. Box 2000
Mail Stop SB-2A
Soddy Daisy, TN 37379-2000
phone   423-843-7711
fax        423-843-7133
email    JALeamon@tva.gov

      John A. Leamon