Milk Sampling

Milk samples were collected weekly in Idaho Falls and monthly at nine additional locations around the INEEL.  All samples were analyzed for gamma emitting radionuclides.  A total of 27 monthly and 13 weekly milk samples were collected during the second quarter of 2001. 

No samples had a ¹³⁷Cs concentration greater than the 2s uncertainty.  One sample from Rupert (April 3) had an ¹³¹I result greater than the 2s and MDC, however, an immediate recount of the sample showed that it did not exceed either the 2s or MDC, thus indicating a false positive. 

Of the four samples submitted for tritium analysis, one (Roberts) had a concentration greater than 2s.  However, the sample blank also had tritium results greater than 2s.  Therefore, there is a high probability that this result is a false positive.  All tritium, ¹³⁷Cs, and ¹³¹I results can be found in Appendix C in Table C-8.

Six samples were submitted for ⁹⁰Sr analysis.  All of them had concentrations of ⁹⁰Sr greater than the 2s level, and three (Carey, Rupert, Blackfoot) were above the MDC. 

While there are no specific regulatory limits for ⁹⁰Sr in milk, as a comparison, the DCG for ⁹⁰Sr of 1.0 x 10^-6 µCi/ml in water can be used.  None of the samples exceeded the DCG for ⁹⁰Sr in water.  In fact, the samples that exceeded both the 2s and MDC were from 1,209 to 1,330 times smaller than the DCG value (Table B-1).  Results for ⁹⁰Sr analyses are located in Table C-9, Appendix C. 

As discussed in the Helpful Information section, ⁹⁰Sr exists as a remnant of atmospheric testing of nuclear weapons and nuclear accidents.  Because of this fact, detections of ⁹⁰Sr cannot automatically be attributed to the INEEL.  From 1978 to 2001 the EPA, as part of its ERAMS program, measured ⁹⁰Sr from 4.9 x 10⁰ to –2.8 x 10^-1 pCi/L in milk samples across the United States (EPA, 2002).   The measured values for this quarter are well within range of these observed values.

Back