[ RadSafe ] Definition of Reliability of Provision of Dosimetry Results

[CHASE John -NUCLEAR]

I provide technical support for OPG's thermoluminescent  dosimetry (TLD) systems, and Ontario Power Generation analyzes many urine samples for tritium as well. In Canada, to provide dosimetry services you must have a Dosimetry Service License (DSL) issued by our regulator, the Canadian Nuclear Safety Commission (CNSC). One of the provisions of our DSL is that we must make an unplanned event report for any event that affects, or has the potential to affect, the precision, accuracy and reliability of the dosimetry results obtained while carrying out the activities authorized by the license.

There is no specification on "reliability" of the provision of dosimetry services, nor on how much change/deterioration in the reliability of the provision of the results would be considered enought to affect the reliability.

We do the typical gamut of start-up (before a TLD run or bioassay analysis on an LSC) and in-line (during the readout) QC checks, as well as QA performance (in house) tests and independent (samples prepared or dosimeters irradiated by an external agency) tests. We also have processes in place to identify necessary corrective actions and monitor their completion. And for personnel whole body TLDs, we of course use the results from Electronic Personal Dosimeters as backup for the TLD results when these are not available.

My questions are:

1.      How would you define reliability for providing dosimetry results?
2.      How would you specify or determine when the reliability has deteriorated, and especially how would you tell if it has deteriorated significantly to report?
3.      Do you know of any standards (e.g., ISO, IEC, ANSI, etc.) that address this issue?

John Chase




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