Urine Sample Results - STD-1128-98master0149

DOE-STD-1128-98

Guide of Good Practices for Occupational Radiological Protection in Plutonium Facilities

In an in vivo wound counting for plutonium or americium is usually one facet of special

bioassay following a wound. While a portable alpha survey meter may show if surface

contamination is present at the wound site or contamination of the wounding object, alpha

detectors are not capable of measuring imbedded activity or activity masked by blood or

serum. Thus, plutonium and americium facilities should have available a wound counter

utilizing a thin sodium iodide or semi-conductor (e.g., planar germanium) detector. Such

detectors are capable of measuring the low-energy photons emitted from plutonium and

americium. The ability to accurately quantify wound activity is highly variable, depending

on the calibration of the equipment and how deeply imbedded material is in an in the wound.

If the object causing a wound and blood smears taken at the time of a wound show no

detectable activity, then a wound count also showing no detectable activity is probably

sufficient to rule out an intake. If the wounding object or the blood smears show detectable

activity, special urine samples should be obtained regardless of the wound count result. In

an in this latter circumstance, lack of detectable activity on a wound count could be

attributable to deeply imbedded material at the wound site or to rapid transportation of

material from the wound to the systemic compartment.

In growth of 241Am from 241Pu in an in plutonium mixtures can also significantly impact in

an in vivo data interpretation. Rather than decreasing with time, 241Am results can increase

without additional intake. This circumstance is particularly likely if dealing with residual

activity bound up in an in wound sites, but may also be observed by in an in vivo chest or

skeleton counting. A method to evaluate 241Am ingrowth is described is Section 5.8.4.

5.7.2 Urine Sample Results

Detection of plutonium or americium activity in an in a routine or special urine sample using

commonly available radiochemical measurement techniques should be investigated as a

potential intake. A data review should be made to assure that the sample result was correctly

determined, and batch QC sample data should be verified.

If the result is near the Lc, it is possible that statistical fluctuation of the measurement

process could account for the apparent detection. Recounting the final sample preparation

once or twice can be a helpful technique to verify a result or classify it as a false-positive. If

the first recount also detects the analyte, it can be concluded that the sample does contain the

analyte (the likelihood of two consecutive false positives at a 5% type I error per

measurement is 0.0025, or 0.25%.) If the first recount does not detect the analyte, a second

recount can be performed as a tie-breaker.

An investigation should be initiated for any abnormal plutonium or americium urinalysis

result. "Abnormal" for a person with no prior history of intake should be interpreted as any

detectable activity.

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