June 30th, 2011 – Update on a Review of REMP Direct Radiation Programs and ANSI N13.37

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[quote]“If you can’t explain it mathematically, you don’t understand it”,
Richard Conatser, 2011[/quote]

The results from the new dosimeters are lower across all locations when compared to the results previously obtained using the Panasonic UD-814 dosimeters. This difference is most likely due to the manner in how background badge data was applied for the in-house processing of Panasonic dosimeters as compared to the method used by the vendor.

The quarterly average for the indicator locations was 25.5 millirem/quarter and a range from 20.0 to 40.0 millirem/quarter. The control stations 44 and 111, which are located 10.3 miles, 270 degrees and 10.8 miles, 254 degrees, respectively, had an average of 25.5 millirem/quarter and a range from 21.0 to 29.0 millirem/quarter. The highest station was Station 67 with an average of 28.8 millirem/quarter and a range from 21.0 to 40.0 millirem/quarter.

For the year 2007, the statistical average dose rate of all the quarterly TLD’s was 0.472 mr/day. The quarterly measured dose rates ranged from a minimum of 0.0061 mr/day to a maximum of 0.1042 mr/day.

The statistical average dose rate of all the annual TLDs was 0.428 mr/day. The annual measured dose rates ranged from a minimum of 0.019 mr/day to a maximum of 0.242 mr/day.

There was good agreement between the sum of the measured doses of the individual quarterly TLDs and the measured dose of the annual TLDs. The summation of the individual quarterly measured doses averaged 20.28 mr for all the forty three monitoring stations while the annual measured dose averaged 18.4 mr for all the monitoring stations.

Issues that now are being added to the ANSI:
 Spur the use of multiple dosimeters
 Identify anomalies
 Proper significant figures (24 vs 24.4 vs 24.3582), attention to detail
 Get units under control (mrem/Standard Quarter, and Ambient Dose Equivalent)
 Transit controls not handled correctly or minimized (the crucial, but easiest fixes)
 Proper Reporting Processes
 LLDs: above natural background baselines (not 1 mrem per year)
 “Was the public exposed to direct radiation?”
 How to handle new monitoring stations
 Relevance of Fukushima disaster

Actions taken in the past year
San Onofre Revisions/Improvements
 Limerick Station improvements to their results
 Assisted other stations (discovered two offsite exposures)
 Reviewed other station reports with site personnel, showing people that this is easier than it sounds
 Continued ANSI efforts

Summary
 Goal will be to develop the ANSI N5.45 replacement.
 Providing guidance for the REMP Direct Radiation Section.
 Units in mRem per standard quarter and mrem per year
 Recommendations for system improvements (better statistics, multiple dosimeters at each location, consider longer field cycles, coordinate shorter transit times (contracts), anomalous data reviews, compare to NRC Direct Radiation Network, one decimal place as a norm)
 Transit controls (handed correctly and be less than 25% of the field dose)
 Long term averages: LLDs as compared to a natural background baselines (already detected small exposures, including dose at a natural gas pumping station 5 miles from a plant)
 Reporting processes (individual station results vs baseline, annual doses, not just inner and outer ring averages)
 Determination of any positive dose results and conversion to “hypothetical maximumexposed individual” (occupancy factor guidance needed)

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