EPA Air DOCKET NO: A-98-49; II-B1-30; July 2014

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Analysis of EPA and DOE WIPP Air Sampling Data

July 16, 2014

Table of Contents

1.0 Summary................................................................................................... 2

2.0 Monitoring Data.......................................................................................... 2

3.0 Methodology.............................................................................................. 3

3.1 Descriptive Statistics............................................................................... 3

3.2 Main Analysis........................................................................................ 3

4.0 Results...................................................................................................... 4

4.1 Descriptive Statistics................................................................................ 4

Table 1: Summary of Derived Activity Concentration Measurements........................ 5

Table 2: Summary of Z-Values for Activity Measurements from EPA and DOE........... 5

4.2 Main Analysis....................................................................................... 6

Table 3: Summary of ANOVA Results for Am-241............................................. 7

activity concentration measurements 

Table 4: Summary of ANOVA Results for Pu-238 .............................................. 7

 activity concentration measurements

Table 5: Summary of ANOVA Results for Pu-239/240.......................................... 8

 activity concentrations measurements

Table 6: Comparison of MSE values from ANOVA to estimates of CSU................... 8 

5.0 Limitations of the Analysis.............................................................................. 8

Table 7: Table of Units.............................................................................. 8

Attachment I: Data Listings................................................................................. 9

Table I.1: DOE Supplied Data for Selected Variables.......................................... 9

Table I.2: EPA Data for Selected Variables....................................................... 11
EPA Air DOCKET NO: A-98-49; II-B1-30; July 2014

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1.0 Summary

During the U.S. Environmental Protection Agency’s (EPA) April 2014 visit to the Waste Isolation 

Pilot Plant (WIPP), EPA co-located four ambient air samplers with existing Department of Energy 

(DOE) ambient air samplers to independently corroborate DOE’s reported air sampling results. The air 

samplers were located at the WIPP Far Field, WIPP East and WIPP South locations. Three sets of 

samples were run for week-long time in April 2014. The air filters were analyzed for americium-241 

(Am-241), plutonium-238 (Pu-238) and plutonium-239/240 (Pu-239/240) with the primary purpose of 

determining whether DOE and EPA data were comparable. 

Data for each radionuclide were fit separately using an analysis of variance model that accounted for 

potential effects on measured activity concentration of monitor location, time period and data source 

(DOE or EPA). Results provided no evidence of a systematic difference between the DOE and EPA 

activity concentration measurements, although it should be noted that the statistical power for detecting 

such a difference is limited. For both DOE and EPA data, the variation observed among the activity 

concentration measurements was consistent with the combined standard uncertainty estimates (CSU) 

that had been included with the data. The data provided no evidence of positive concentrations for any 

of the monitored radionuclides. 

2.0 Monitoring Data

Both DOE and EPA provided spreadsheets with common data fields; these included sampling location, 

time period sampled, activity in disintegrations per minute (dpm), air volume of the sample collected 

(m3), the derived measured activity concentration (Bq m-3), an estimate of the activity concentration 

CSU, and a “Z-value” for determining whether a sample measurement is a non-detect. The reported Zvalue is equal to the measured activity concentration divided by the CSU. The CSU is a measure of 

uncertainty, essentially an estimate of the standard deviation, which accounts for “error” in 

measurements associated with identified sources of uncertainty (e.g., random variation in the number 

of disintegrations within the monitoring period, uncertainty about the counting efficiency of the 

instrument, and uncertainty associated with corrections necessary to subtract out effects from sources 

of radiation other than the analyte). For many types of data (e.g., for which random variation follows a 

normal distribution), about 5% of measurements can be expected to differ from the value being 

measured by at least 2 times the CSU. It follows that a Z-value greater than 2 should not be an 

especially rare occurrence – even if the concentrations being measured all equal 0. A measurement 

with a Z-value less than 2 is typically regarded as being too small—relative to its CSU—to establish 

the presence of the radionuclide. A listing of selected data fields is given in the Attachment I. 

The ambient air monitoring data covers three, week-long time periods in April. Both DOE and EPA 

collected four samples each week; each organization collected two samples at the Far Field location 

and one each at WIPP East and WIPP South. A measurement from a blank sample was used to account 

for the effects of background radiation, that is to say, measurements of activity from field samples 

were “blank corrected” by subtracting out results obtained from the blanks. The EPA spreadsheet 

included the original results from the blank samples whereas the DOE spreadsheet only included the 

blank-corrected results. EPA used a common blank sample for each of the four samples collected each 

week, and a reasonable assumption—based on conversations with DOE—is that the same practice was 

used at DOE, that is to say, each week a common blank sample was used for each of the four samples. 

Thus, for both datasets, blank-corrected results from samples collected within the same time period are 

correlated.
EPA Air DOCKET NO: A-98-49; II-B1-30; July 2014

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3.0 Methodology

3.1 Descriptive Statistics 

Descriptive statistics were first calculated for the main variables of interest: activity concentration, and 

the corresponding CSU estimate and Z- values. Pairwise comparisons were also made between the 

blank-adjusted activity measurements from DOE and EPA. For each time period and location, the 

normalized difference between the average EPA activity measurement and average DOE measurement 

was calculated according to the equation:

Zd =

mean(YDOE)−mean(YEPA)

√k(mean(CSUDOE

2

)+mean(CSUEPA

2

))

, 

k = 1 for WIPP East or WIPP South and k = 0.75 for Far Field. 

For a pairwise comparison, an absolute value of Zd greater than 2 would indicate a difference between 

the DOE and EPA measurements that cannot be attributed to random error inherent in the sampling 

and laboratory measurement process. Note that if there is no such difference, then about 2.5% of the Zd

values would be expected to be greater than 2 and about 2.5% less than -2. That is, 5% would be false 

positives. This assumed false positive rate of 5% is only approximate, in part, because calculated 

values for Zdoften depend on imprecise estimates of the CSU. 

3.2 Main Analysis

For the main analysis, an Analysis of Variance (ANOVA) model – with modification to account for 

correlations among results for samples collected within the same time period – was used to test the 

(null) hypotheses that: 1) there is no systematic difference between the DOE and EPA activity 

concentration measurements, and 2) activity concentration at all monitoring stations for all time 

periods are equal to 0. For each radionuclide, blank corrected activity concentration measurements 

were assumed to depend on data source (i = 1, 2: DOE or EPA), time period sampled (j = 1, 2, or 3), 

sampling location (k = 1, 2, or 3 for Far Field, WIPP East or WIPP South), and replicate number (m = 

1 or 2 for Far Field; 1 for other locations) according to the equation:

Yijk(m) = μ +αi +βj + γij + λk + δij + εijk(m),

δij , εijk(m) ~ N(0, σ2) 

Here, μ = mean activity concentration (averaged over all locations and time periods). The parameters 

αi(data source), βj (time period sampled) and λk (location) are main effect terms and the γij are 

interaction terms for data source and time period. Note that the variance of a blank-corrected 

measurement is 2σ2. 

The software package, Stata, was used to calculate the ANOVA statistics and simple adjustments were 

applied to F-value statistics (for testing hypotheses at the 0.05 significance level), to account for the 

correlations in the blank-corrected measurements. An advantage of using this approach is that—under 

the null hypotheses—the mean squared error (MSE) value generated from the standard ANOVA is an 
EPA Air DOCKET NO: A-98-49; II-B1-30; July 2014

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unbiased estimate of σ

2

. The MSE (divided by 2) was then compared to the squared CSU estimates 

(included in the dataset). 

Essentially, the ANOVA compares the amount of observed variation in the activity concentration 

measurements associated with factors such as data source, monitor location and sampling period to an 

estimate of the amount of variation that would be expected if these factors would have no effect on the 

measurements. The F-statistic (with adjustment), is the ratio of the observed variation associated with 

the factors being tested to an estimate of variation that would be expected if the (tested) factors have no 

effect on the measurements. A ratio that is sufficiently large indicates that the amount of variation may 

be too large to be attributed to chance alone, i.e., the results are statistically significant. Statistically 

significant results are typically interpreted as evidence that the factors being tested have a noticeable 

effect on measurement results.

4.0 Results

4.1 Descriptive Statistics

Table 1 summarizes the 72 activity concentration measurements for Am-241, Pu-238, and Pu-239/240 

(24 measurements each). Measurements (Bq m-3) ranged from (-4.14E-7 to 6.22E-07) for Am-241, (-

4.32E-7 to 2.47E-07) for Pu-238 and (-3.35 E-07 to 2.41 E-07) for Pu-239/240. Average 

measurements were positive for Am-241 and negative for Pu-238. For Pu-239/240 the average was 

negative for data from EPA. The mean DOE measurement was greater than the corresponding mean 

from EPA for Am-241 and Pu-239/240, but smaller for Pu-238. For all radionuclides tested, the 

absolute value of the mean was smaller than the standard deviation. 
EPA Air DOCKET NO: A-98-49; II-B1-30; July 2014

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Table 1: Summary of derived activity concentration measurements (Bq m-3) 

Radionuclide Data Source Mean Standard 

deviation

Minimum1 Maximum1

Am-241 DOE (n=12) 1.29E-07 1.99E-07 -1.08E-07

(1.91E-07)

6.22E-07

(4.58E-07)

EPA (n=12) 2.20E-08 2.47E-07 -4.14E-07

(2.47E-07)

3.68E-07

(3.44E-07)

Combined 7.53E-08 2.26E-07 -4.14E-07 6.22E-07

Pu-238 DOE (n=12)

-3.88E-08 1.10E-07 -1.80E-07

(9.01E-08)

2.47E-07

(2.54E-07)

EPA (n=12)

-2.69E-08 2.24E-07 -4.32E-07

(2.20E-07)

2.26E-07

(3.42E-07)

Combined -3.29E-08 1.73E-07 -4.32E-07 2.47E-07

Pu-239/240 DOE (n=12) 9.75E-09 1.13E-07 -1.51E-07

(6.88E-08)

2.00E-07

(2.31E-07)

EPA (n=12)

-1.01E-07 1.99E-07 -3.35E-07

(2.08E-07)

2.41E-07

(2.80E-07)

Combined -4.54E-08 1.68E-07 -3.35E-07 2.41E-07

1 Minimum and maximum reported Combined Standard Uncertainties given in parentheses. 

As seen in Table 2, Z-values for the activity measurements are all smaller than 2. Thus, all samples 

were designated “non-detects.” It can be easily shown that if the CSU can be accurately determined, 

the standard deviation of Z-values should be about 1, i.e., a measurement might typically deviate from 

its measurand by an amount approximately equal to 1 standard deviation. However, for all 

radionuclides the standard deviations of the Z-values were less than 1. This could be an indication of a 

bias in the CSU estimates (the CSU estimates having a tendency to be too large), although there are 

alternate explanations. Z-values associated with paired-comparisons (not shown) were also all less than 

2.

Table 2: Summary of Z-values for activity measurements from EPA and DOE

Radionuclide Data Source Mean Standard 

deviation

Minimum Maximum

Am-241 DOE* 0.38 0.63 -0.53 1.89

EPA 0.09 0.81 -1.31 1.26

Combined 0.24 0.72 -1.31 1.89

Pu-238 DOE* -0.35 0.58 -1.03 0.97

EPA -0.09 0.84 -1.73 0.84

Combined -0.22 0.72 -1.73 0.97

Pu-239/240 DOE* -0.13 0.83 -1.43 0.87

EPA -0.47 0.86 -1.47 0.97

Combined -0.30 0.84 -1.47 0.97

*Z- values were incorrectly reported by DOE. Spreadsheet values were multiplied by a factor of 2. 
EPA Air DOCKET NO: A-98-49; II-B1-30; July 2014

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4.2 Main Analysis

The fitting of the data to the ANOVA model allowed for a more thorough examination as to whether: 

1) there is a systematic difference between DOE and EPA measurements, and 2) there are positive 

activity concentrations for any of the locations or time periods sampled. Results for the three (sets of) 

radionuclides are summarized in Tables 3 to 5. The tables include F-statistics with corresponding pvalues (statistically significant results are those for which the p-value < 0.05). F-statistics are the ratios 

of the observed variation associated with tested factors to the estimated expected variation if the 

factors had no effect on the activity concentration measurements. More specifically, F-statistics are 

given which were used to determine:

1) The statistical significance of variation associated with data source, i.e., whether the data is 

from DOE or EPA. (A sufficiently large value for this F-statistic would indicate that the 

difference between DOE and EPA average measurements could not be just a consequence of 

random variation inherent in the measurement process).

2) The statistical significance of variation associated with any of the factors included in the model, 

(i.e., variation associated with data source, sampling location or time period).

3) Whether average measured activity concentrations were significantly > 0. 

There were no significant results. For each radionuclide

1) There was no evidence of a systematic difference between DOE and EPA measurements (Fstatistic associated with Data Source is not significant).

2) There was insufficient evidence to conclude that activity concentrations depended on data 

source, time period or sampling location (F-statistic associated with the model is not 

significant).

3) There was insufficient evidence (Am-241) or no evidence (Pu-238, Pu-239/240) that activity 

concentrations for any of the locations or time periods sampled was > 0.

Finally, Table 6 compares the MSE values (Tables 3 to 5) to the CSU estimates calculated by DOE and 

EPA. If underlying assumptions for the ANOVA model and CSU calculations are correct, the MSE 

would be (on average) about half as large as the average of the squared CSU value. Given the small 

sample sizes (and the variation in data used to calculate the MSE and the CSU), results shown in 

Table 6 are consistent (ratios in the last column are sufficiently close to 1). 
EPA Air DOCKET NO: A-98-49; II-B1-30; July 2014

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Table 3: Summary of ANOVA results for Am-241 activity concentration measurements (Bq m-3)

Source Hypothesis test question Df1 Mean Square F -Statistic2

All in Model Do activity concentrations 

depend on data source, time 

period sampled or location?

7 9.92E-14 1.32

(p = 0.3)

Error 16 3.03E-14

Data Source

(DOE vs. EPA)

Is there a systematic 

difference between 

measurements from DOE vs. 

EPA?

1 6.82E-14 0.903

(p = 0.36)

Constant term Are activity concentrations 

for any of the locations or 

time periods sampled > 0?4

1 1.36E-13 1.793

(p = 0.1)

1 Degrees of freedom

2 Adjusted to account for correlations induced from the use of common blank samples.

3 F-statistic from Stata calculations divided by 2.5.

4 Assumes no overall bias in measurements from DOE and EPA.

Table 4: Summary of ANOVA results for Pu-238 activity concentration measurements (Bq m-3)

Source Hypothesis test question Df Mean Square F-Statistic1

All in Model Do activity concentrations 

depend on data source, time 

period sampled or location?

7 2.96E-14 0.43

p>0.5

Error 16 3.00E-14

Data Source

(DOE vs. EPA)

Is there a systematic 

difference between 

measurements from DOE vs. 

EPA?

1 9.0 E-16 0.012

p>0.5

Constant term Are activity concentrations 

for any of the locations or 

time periods sampled > 0?3

1 2.58E-14

0.342

(mean < 0)

p>0.5

1 Adjusted to account for correlations induced from the use of common blank samples.

2 F-statistic from Stata calculations divided by 2.5

3 Assumes no overall bias in measurements from DOE and EPA.
EPA Air DOCKET NO: A-98-49; II-B1-30; July 2014

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Table 5: Summary of ANOVA results, Pu-239/240 activity concentration measurements (Bq m-3)

Source Hypothesis test question Df Mean Square F-Statistic1

All in Model Do activity concentrations 

depend on data source, 

time period sampled or 

location?

7 6.06E-14 1.80

(p=0.16)

Error 16 1.38E-14

Data Source

(DOE vs. 

EPA)

Is there a systematic 

difference between 

measurements from DOE 

vs. EPA?

1 7.28E-14 2.112

(p=0.17)

Constant term Are activity concentrations 

for any of the locations or 

time periods sampled > 0?3 1 4.95E-14

1.432

(mean < 0)

(p> 0.5)

1 Adjusted to account for correlations induced from the use of common blank samples.

2 F-statistic from Stata calculations divided by 2.5.

3 Assumes no overall bias in measurements from DOE and EPA.

Table 6: Comparison of MSE values from ANOVA to estimates of CSU

Radionuclide MSE (Mean Square CSU)/2 Ratio

Am-241 3.03E-14 4.38E-14 0.69

Pu-238 3.00E-14 2.71E-14 1.11

Pu-239/240 1.38E-14 2.00E-14 0.69

5.0 Limitations of the Analysis

The data provided no evidence of a systematic difference between the DOE and EPA measurements. 

Although this is an indication that systematic differences between DOE and EPA measurements may 

be negligible, it should be noted that the statistical power for detecting such differences is limited. The 

dataset is small (for each radionuclide, measurements from DOE and EPA were each based on only 12 

field samples and 3 blank samples), and average differences in measurement less than the CSUs for 

individual blank-corrected activity concentration measurements were not detectable. A potentially 

more important issue relates to the possibility that the magnitude of systematic differences, if they 

exist, might be expected to increase with the level of concentrations being measured. However, this 

issue could not be investigated, since the data were consistent with zero concentrations for each of the 

radionuclides.

Table 7: Table of Units

Unit Abbreviation Quantity/Description

Becquerel Bq International System of Units (SI unit) of 

radioactivity = 1 disintegration per second

Disintegrations per minute dpm Radioactivity 

Becquerel per meter cubed Bq m-3 or 

Bq/m3

Activity concentration

Meter cubed m3 Air volume of the sample collected
EPA Air DOCKET NO: A-98-49; II-B1-30; July 2014

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Attachment I: Data Listings

Table I.1: DOE Supplied Data for Selected Variables1

Am-241

Sample Location

Sampling 

Period

Blankcorrected 

Activity 

(dpm)

Volume 

m3

Activity 

Concentration 

(Bq m-3)

CSU

(Bq m-3) Z-value

1 WFF 4/8-4/15 1.20E-02 571.20 3.50E-07 4.11E-07 0.85

2 WFF 4/8-4/15 1.84E-04 574.06 5.34E-09 3.32E-07 0.02

3 WEE 4/8-4/15 5.53E-03 568.60 1.62E-07 3.11E-07 0.52

4 WSS 4/8-4/15 3.71E-03 570.74 1.08E-07 4.58E-07 0.24

5 WFF 4/15-4/22 1.89E-04 551.76 5.71E-09 2.10E-07 0.03

6 WFF 4/15-4/22 1.57E-03 555.76 4.71E-08 2.44E-07 0.19

7 WEE 4/15-4/22 -3.60E-03 557.36 -1.08E-07 2.05E-07 -0.53

8 WSS 4/15-4/22 4.40E-03 543.32 1.35E-07 2.64E-07 0.51

9 WFF 4/22-4/29 2.10E-02 562.80 6.22E-07 3.29E-07 1.89

10 WFF 4/22-4/29 5.12E-04 577.01 1.48E-08 1.91E-07 0.08

11 WEE 4/22-4/29 -1.13E-03 568.83 -3.31E-08 2.17E-07 -0.15

12 WSS 4/22-4/29 8.14E-03 579.86 2.34E-07 2.51E-07 0.93

Pu-238

1 WFF 4/8-4/15 8.47E-03 571.20 2.47E-07 2.54E-07 0.97

2 WFF 4/8-4/15 -3.57E-04 574.06 -1.04E-08 1.70E-07 -0.06

3 WEE 4/8-4/15 -1.88E-03 568.60 -5.51E-08 9.01E-08 -0.61

4 WSS 4/8-4/15 -2.21E-03 570.74 -6.45E-08 9.93E-08 -0.65

5 WFF 4/15-4/22 -4.27E-03 551.76 -1.29E-07 1.47E-07 -0.88

6 WFF 4/15-4/22 -6.01E-03 555.76 -1.80E-07 1.75E-07 -1.03

7 WEE 4/15-4/22 -7.68E-04 557.36 -2.30E-08 2.30E-07 -0.10

8 WSS 4/15-4/22 -4.53E-03 543.32 -1.39E-07 1.55E-07 -0.90

9 WFF 4/22-4/29 -8.83E-04 562.80 -2.61E-08 1.70E-07 -0.15

10 WFF 4/22-4/29 1.84E-03 577.01 5.31E-08 2.05E-07 0.26

11 WEE 4/22-4/29 -2.93E-03 568.83 -8.58E-08 1.15E-07 -0.75

12 WSS 4/22-4/29 -1.83E-03 579.86 -5.26E-08 1.75E-07 -0.30
EPA Air DOCKET NO: A-98-49; II-B1-30; July 2014

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Pu-239/240

Sample Location

Sampling 

Period

Blankcorrected 

Activity 

(dpm)

Volume 

m3

Activity 

Concentration 

(Bq m-3)

CSU

(Bq m-3) Z-value

1 WFF 4/8-4/15 2.76E-03 571.20 8.05E-08 1.95E-07 0.41

2 WFF 4/8-4/15 -5.20E-03 574.06 -1.51E-07 1.57E-07 -0.96

3 WEE 4/8-4/15 -1.03E-04 568.60 -3.02E-09 1.64E-07 -0.02

4 WSS 4/8-4/15 6.86E-03 570.74 2.00E-07 2.31E-07 0.87

5 WFF 4/15-4/22 -3.71E-04 551.76 -1.12E-08 1.38E-07 -0.08

6 WFF 4/15-4/22 4.21E-03 555.76 1.26E-07 1.78E-07 0.71

7 WEE 4/15-4/22 -3.30E-03 557.36 -9.87E-08 6.88E-08 -1.43

8 WSS 4/15-4/22 -4.51E-03 543.32 -1.38E-07 1.08E-07 -1.28

9 WFF 4/22-4/29 -2.78E-03 562.80 -8.23E-08 8.74E-08 -0.94

10 WFF 4/22-4/29 3.50E-03 577.01 1.01E-07 1.69E-07 0.60

11 WEE 4/22-4/29 -9.04E-05 568.83 -2.65E-09 1.44E-07 -0.02

12 WSS 4/22-4/29 3.34E-03 579.86 9.60E-08 1.54E-07 0.62

1 Does not include data on quality control blanks
EPA Air DOCKET NO: A-98-49; II-B1-30; July 2014

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Table I.2: EPA Data for Selected Variables1

Am-241

Sample Location

Sampling 

period

Blankcorrected

Activity 

(dpm)

Volume 

(m3)

Activity 

Concentration 

(Bq m-3)

CSU

(Bq m-3) Z-value

1 WEE 4/7-4/15 -7.91E-03 589.20 -2.24E-07 3.06E-07 -0.73

2 WFF 4/7-4/15 -8.41E-03 575.00 -2.44E-07 3.21E-07 -0.76

3 WFF 4/7-4/15 -1.47E-02 592.50 -4.14E-07 3.15E-07 -1.31

4 WSS 4/7-4/15 -8.52E-03 602.00 -2.36E-07 2.94E-07 -0.80

5 WFF 4/15-4/22 2.04E-03 557.00 6.11E-08 3.06E-07 0.20

6 WFF 4/15-4/22 6.18E-03 616.30 1.67E-07 2.67E-07 0.63

7 WSS 4/15-4/22 4.27E-03 540.70 1.32E-07 2.89E-07 0.46

8 WEE 4/15-4/22 1.11E-02 541.60 3.40E-07 3.44E-07 0.99

9 WEE 4/22-4/29 5.91E-03 527.90 1.87E-07 2.85E-07 0.65

10 WSS 4/22-4/29 2.06E-03 525.59 6.53E-08 2.47E-07 0.26

11 WFF 4/22-4/29 1.15E-02 521.60 3.68E-07 2.92E-07 1.26

12 WFF 4/22-4/29 2.06E-03 563.40 6.09E-08 2.66E-07 0.23

Pu-238

1 WEE 4/7-4/15 7.97E-03 589.20 2.26E-07 2.72E-07 0.83

2 WFF 4/7-4/15 4.17E-03 575.00 1.21E-07 2.71E-07 0.45

3 WFF 4/7-4/15 2.12E-03 592.50 5.96E-08 3.42E-07 0.17

4 WSS 4/7-4/15 4.24E-03 602.00 1.17E-07 2.20E-07 0.53

5 WFF 4/15-4/22 -8.33E-03 557.00 -2.49E-07 2.92E-07 -0.85

6 WFF 4/15-4/22 7.78E-03 616.30 2.11E-07 2.50E-07 0.84

7 WSS 4/15-4/22 -1.00E-02 540.70 -3.09E-07 2.74E-07 -1.13

8 WEE 4/15-4/22 -4.26E-03 541.60 -1.31E-07 3.32E-07 -0.39

9 WEE 4/22-4/29 -5.87E-03 527.90 -1.85E-07 2.84E-07 -0.65

10 WSS 4/22-4/29 1.86E-03 525.59 5.90E-08 2.40E-07 0.25

11 WFF 4/22-4/29 5.95E-03 521.60 1.90E-07 3.17E-07 0.60

12 WFF 4/22-4/29 -1.46E-02 563.40 -4.32E-07 2.49E-07 -1.73
EPA Air DOCKET NO: A-98-49; II-B1-30; July 2014

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Pu-239/240

Sample Location

Sampling 

period

Blankcorrected

Activity 

(dpm)

Volume 

(m3)

Activity 

Concentration 

(Bq m-3)

CSU

(Bq m-3) Z-value

1 WEE 4/7-4/15 -9.58E-03 589.20 -2.71E-07 2.13E-07 -1.27

2 WFF 4/7-4/15 -1.16E-02 575.00 -3.35E-07 2.43E-07 -1.38

3 WFF 4/7-4/15 -1.16E-02 592.50 -3.25E-07 2.21E-07 -1.47

4 WSS 4/7-4/15 -9.50E-03 602.00 -2.63E-07 2.26E-07 -1.16

5 WFF 4/15-4/22 -6.57E-03 557.00 -1.96E-07 2.08E-07 -0.94

6 WFF 4/15-4/22 -8.63E-03 616.30 -2.33E-07 2.10E-07 -1.11

7 WSS 4/15-4/22 9.20E-04 540.70 2.84E-08 2.42E-07 0.12

8 WEE 4/15-4/22 -1.61E-03 541.60 -4.96E-08 2.80E-07 -0.18

9 WEE 4/22-4/29 7.64E-03 527.90 2.41E-07 2.48E-07 0.97

10 WSS 4/22-4/29 -2.16E-03 525.59 -6.85E-08 2.39E-07 -0.29

11 WFF 4/22-4/29 3.97E-03 521.60 1.27E-07 2.37E-07 0.53

12 WFF 4/22-4/29 4.69E-03 563.40 1.39E-07 2.59E-07 0.54

1 Does not include data on blanks