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Quality Assurance

The ESER Quality Assurance Program consists of five ongoing tasks which measure:

  1. method uncertainty;
  2. data completeness;
  3. data accuracy, using spike and laboratory control samples;
  4. data precision, using split samples, duplicate samples, and recounts; and
  5. the presence of contamination in samples, using blanks.

The following discussion briefly summarizes the results of the quality assurance program for the period from May 1 to June 30, 2004.

METHOD UNCERTAINTY

The Quality Assurance Project Plan (QAPP) establishes data quality and method quality objectives for the ESER surveillance program (Stoller 2002). Since the primary concern is with detection, the lower bound for the method uncertainty is set at zero. The upper bound is established as the average maximum concentration from the past seven years of applicable data. Each individual result is checked for acceptance on the basis of the result, whether it is below the lower limit (i.e., a negative value), greater than the upper limit, or between the lower and upper limit (the most common occurrence). The calculated method uncertainty is then compared to the 1s measured uncertainty. A sample is deemed acceptable when the measured 1s uncertainty is less than the calculated uncertainty. Those results that did not meet this requirement are shown in Table 2.

 Table 2.                    Analytical results determined to be unacceptable. 

Media

Radionuclide

Number Unacceptablea

Air

Gross alpha

7 / 386b

filters and cartridges

Gross beta

3 / 386

 

Cesium-137

81 / 371

 

Iodine-131

153 / 371

 

Americium-141

6 / 11

 

Plutonium-238

0 / 11

 

Plutonium-239/40

0 / 11

 

Strontium-90

3 / 9

moisture in air

Tritium

0 / 9

Precipitation

Tritium

0 / 17

Milk

Cesium-137

0 / 89

 

Iodine-131

42 / 89

a.   Format shown is number unacceptable / total number of analyses.

b.   Total number of analyses varies due to different numbers of recounts for each radionuclide.

DATA COMPLETENESS

The Quality Assurance Project Plan (QAPP) specifies a 98 percent completeness goal for all regularly scheduled sample types (Stoller 2002). Data completeness for sample collection and delivery was 100 percent during the second quarter for all sample types with one exception: a number of precipitation samples were not collected due to lack of precipitation.

SUMMARY

In summary the quality assurance and data quality objectives for analyses were met in the fourth quarter of 2004 with the following exceptions:

The ESER will work with the laboratories to identify where improvements can be made.

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