1. Addressing Uncertainty in Radiochemistry Measurements M. C. Nichols, CHP mcnichols@vzw.blackberry.net 404-819-5118 RETS-REMP meeting

2. June, 2009RETS-REMP meeting Guidelines for Using Quality Control and Performance Testing (PT) Data USNRC regulatory guide 4.15 revision 1, performance testing –Specification in 6.3.2 for performance testing –Acceptance criteria –Uncertainty estimates from PT data Revision 2, based on MARLAP –Total propagated uncertainty

3. June, 2009RETS-REMP meeting USNRC Regulatory Guide 4.15, Rev. 1 Performance testing - 6.3.2 –Measure accuracy (normalized deviation) –Measure precision (normalized range) Basis: “Environmental Radioactivity Laboratory Intercomparison Program”, EPA 600/4-07-001, January 1977

4. June, 2009RETS-REMP meeting Acceptance Criteria Confidence interval estimates Normalized deviation and normalized ranged in the EPA cross check program Ratio and resolution based on US NRC Inspection Procedure-84750

5. June, 2009RETS-REMP meeting Confidence Limit

6. June, 2009RETS-REMP meeting EPA Cross Check - Accuracy

7. June, 2009RETS-REMP meeting EPA Cross Check - Precision

8. June, 2009RETS-REMP meeting NRC IP-84750 Resolution - divide each NRC result by its associated uncertainty Uncertainty defined as the relative uncertainty, 1S, of NRC results calculated from counting statistics Ratio - licensee result / NRC result Criteria - gives a range of acceptable ratios as a function of resolution

9. June, 2009RETS-REMP meeting Single Laboratory Precision Counting uncertainty Providers specification Use performance testing history Construct an uncertainty budget –May be available for specific procedures (gamma spectroscopy) –Build on existing quality control data

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12. June, 2009RETS-REMP meeting Variance - Future Prediction

13. June, 2009RETS-REMP meeting Sr-90 Concentration (pCi/Liter) Prediction Interval (1S) Coefficient of Variation 51.837% 101.818% 151.812% 201.89% 251.87% 301.96% Prediction Intervals for Sr-90

14. June, 2009RETS-REMP meeting Suggestions for Performance Testing Data Two components to the evaluation of performance data –Uncertainty of the known value –Uncertainty of the measured value Regression - use replicate measurements for each performance testing round Uncertainties from performance testing results are limited to the range of testing

15. June, 2009RETS-REMP meeting Uncertainty Budget Define the process including components of the activity estimate Identify uncertainty estimates for each component Use software tools to create uncertainty budgets (e.g. Gumcalc)

16. Efficiency

17. June, 2009RETS-REMP meeting Example - Uncertainty for Balance Measurement

18. June, 2009RETS-REMP meeting

19. June, 2009RETS-REMP meeting Strontium-89 Uncertainty at 18.5 mg cm -2, Efficiency 0.453 ± 0.012 (95% CL).

20. June, 2009RETS-REMP meeting Summary All performance testing evaluation is based on an estimate of measurement uncertainty Performance testing data will provide an estimate of total measurement uncertainty Measurements outside the range of PT data and new program requirements will require assessment of measurement uncertainty Laboratories currently have sufficient data to construct these estimates

21. June, 2009RETS-REMP meeting References –Ellison, S.L.R., M. Rosslein, and A. Williams, 2000. EURACHEM/CITAC guide CG 4: quantifying uncertainty in analytical measurement, 2nd edition –MARLAP, 2004. Multi-agency radiological laboratory analytical protocols manual (final) volume i (epa 402-b-04-001a), volume ii (epa 402-b-04-001b), volume iii (epa 402-b-04-001c)volume ivolume iivolume iii –Mccroan, K. D., 2005. Gumcalc v 1.0. Freeware developed for the MARLAP project. Http://mccroan.Com/gumcalc.Htm –USEPA, 1977. Environmental radioactivity laboratory intercomparison program”, EPA 600/4-07-001 –USNRC, 2007 Quality assurance for radiological monitoring programs (inception through normal operations to license termination) -- effluent streams and the environment, revision 2, ML071790506, July, 2007 ML071790506 –USNRC, 1994. NRC inspection manual procedure 84750 for radioactive waste treatment, effluent, and environmental monitoring