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State of Wisconsin - 2010
La Crosse Boiling Water Reactor
Environmental Radioactivity Survey

Wisconsin Department of Health Services
Division of Public Health
Bureau of Environmental and Occupational Health
Radiation Protection Section
P.O. Box 2659
Madison, Wisconsin 53701

Table of Contents

Introduction
WI DHS LACBWR Environmental Monitoring Program
Program Modifications
Laboratory Services and Quality Assurance
Detection Limits
Reporting of Sample Analysis Results
Results and Discussion
List of Tables
References

Introduction

Wisconsin Public Health Statues 254.41 mandates the Department of Health Services (DHS) to conduct environmental radiation monitoring around the nuclear power facilities that impact Wisconsin. This environmental monitoring report is for the La Crosse boiling water reactor (LACBWR) for the calendar year January - December 2010 and provides a description and results of this environmental monitoring program.

WI DHS LACBWR Environmental Monitoring Sampling Program

The WI DHS environmental monitoring program consists of the collection of various types of samples from the air, water and terrestrial exposure pathways.  The sampling program included samples of air, ambient gamma radiation (TLD), surface water, fish, bottom sediments, soil and vegetation that are collected from selected locations at planned sampling intervals. 

Table 1 is a listing of sampling sites and includes a description, direction and distance from the monitored power plant. Table 2 provides a listing of the types of samples collected, sites where samples are collected, the number of samples collected, number of samples that were missed or had noted problems and a listing of the required analyses.  Table 3 provides an explanation of missing samples or non-routine sample analyses. Figure 1 is a map showing the location of each environmental sampling site.

Program Modifications

On April 30, 1987, Dairyland Power Cooperative permanently shutdown the LACBWR facility.  Their NRC licensee was amended to a possess-but-not-operate status on August 4, 1987 and they are now in the process of decommissioning the LACBWR facility.  Since any severe accident involving the stored spent fuel will have little offsite consequences, the WI DHS environmental radioactivity monitoring program was modified in June 1988.  These modifications included the elimination of precipitation, shoreline sediment and well water samples as well as a reduction in vegetation, soil and some surface water sampling. 

In response to this and considering other funding restrictions the LACBWR environmental monitoring program was reviewed and further modified in 1998, 1999 and 2000.  Table 1 is a listing of presently used sampling sites that have been renumbered after eliminating sample sites that have been discontinued.  Sampling sites that have been discontinued were last listed as sampling sites in WI DHS’s environmental monitoring report for the La Crosse boiling water reactor (LACBWR) for the calendar year of January - December, 1999.

Due to funding restrictions and the future relocation of the spent fuel to the LACBWR Independent Spent Fuel Storage Installation (ISFSI), the following program modifications were implemented beginning in the 3^rd quarter of 2010.

Air particulate sites:  The WI DHS control site (LAC-1) was discontinued.

Fish:  The sampling frequency was reduced from quarterly to twice per year with samples to be collected in the 2^nd and 3^rd quarters of the year.

Bottom sediment:  The sampling frequency was reduced from twice per year to an annual sample to be collected in the spring or early summer.

Laboratory Services and Quality Assurance

The analysis of the samples is performed under contract with the Wisconsin State Laboratory of Hygiene (WSLH).  WSLH maintains a quality assurance program.  Analytical procedures provide for routine replicate analyses to verify methods and instrument operation.  Traceable sources are used to regularly calibrate the counters and daily performance checks are made between calibrations.  In addition, quality control charts are maintained on the counters.

WSLH participates in the Environmental Resource Associates’ Proficiency Testing program and has performed satisfactorily over the report period.  Proficiency testing results are available from the Wisconsin State Laboratory of Hygiene.

Detection Limits

Detection limits, required by WI DHS, will be expressed as a lower limit of detection (LLD).   The required WI DHS LLD as indicated in Table 4 under the heading “LLD” is an "a priori" estimate of the capability for detecting an activity concentration by a given measurement system, procedure, and type of sample.  Counting statistics of the appropriate instrument background are used to compute the LLD for each specific analysis.  Using 4.66 times the standard deviation (s_b) of the instrument background, the LLD for each specific analysis is defined at the 95% Confidence Level.

The LLD for each radioisotope listed in Table 4 has been calculated from the following equation:

Where:

Typical values for E, V, Y and dt have been used to calculate the LLD.

Results for specific analyses will be reported as either a “less than” (<) value or an actual activity value. The reporting of results in Table 4 under the heading “Range” and in Tables 5-11 are “a posteriori” calculations based on the actual analysis performed using the actual sample values for E, V, Y and dt. Typically the reported “less than” (<) results are lower than the required WI DHS LLD indicating that the required WI DHS LLD has been met.

An actual activity value will be accompanied by an uncertainty term for that analysis.  The uncertainty term is a plus or minus counting uncertainty term at the 2 sigma (95%) confidence interval and is printed as (+- or ±).  Examples and explanations of data reporting are:

Example

Nuclide 

Activity reported

1

¹³⁷Cs

< 10 pCi/liter

2

¹³⁷Cs

      15 ± 3 pCi/liter

Air Particulate

A summary of reported activities by WI DHS for air particulate samples is included in Table 4.  Results from the individual sample analyses are listed in Tables 5 and 6.

From the bi-weekly and quarterly gross beta activities listed in Table 5 it may be noted that there are no significant differences due to distance from the LACBWR facility.  With no significant differences due to distance from the LACBWR facility an increase in gross beta activity attributable to LACBWR is not evident.

The gamma isotopic analysis of the quarterly air particulate filter composites detected only small amounts of the radioisotopes listed in Table 4.  All other radioisotopes were below their respective lower limit of detection.  Naturally occurring beryllium-7 (⁷Be), detected in all composites, is constantly produced through nuclear reactions between cosmic rays and nuclei in the atmosphere and is detected in air composites from other areas of the state.

Influence by the LACBWR facility on air quality is not evident from air particulate analysis.

Direct Radiation - Thermoluminescent Dosimeters (TLD's)

A summary of reported activities by WI DHS for direct radiation is included in Table 4.  Results from the individual sample analyses are listed in Table 7.

Direct radiation (TLD) data for 2010 from the WI DHS network was comparable for all sites.  Significant differences in exposure were not noticed at different distances from the LACBWR facility.  The average quarterly exposure from the four sites located within Wisconsin was 14.2 ± 2.8 milliroentgens.  The average quarterly exposure for 2010 is at background levels and is comparable to other areas within Wisconsin.

Fish

A summary of reported activities by WI DHS for fish samples is included in Table 4.  Results from the individual sample analyses are listed in Table 8.

The fish samples showed no unusual activities.  Naturally occurring potassium-40 (⁴⁰K) was reported in all samples.  All other radioisotopes were below their respective lower limit of detection.

Surface Water

A summary of reported activities by WI DHS for surface water samples is included in Table 4. Results from the individual sample analyses are listed in Table 9.

The surface water samples showed no unusual activities.  All detected activities are at background levels and are comparable to data from previous years.  The surface water samples uniformly show activities below state or federal standards.

Bottom sediments

A summary of reported activities by WI DHS for bottom sediment samples is included in Table 4.  Results from the individual sample analyses are listed in Table 10.

The naturally occurring radioisotope potassium-40 (⁴⁰K) was detected in all samples.  The gamma isotopic analysis of the bottom sediment samples taken at site LAC-3 and LAC-4 detected small activities for cesium-137 (¹³⁷Cs). The reported activities for cesium-137 (¹³⁷Cs) can be attributable to past effluent discharges from the LACBWR facility and have also been detected in previous years. Naturally occurring radioisotopes such as radium-226 (²²⁶Ra), bismuth-214 (²¹⁴Bi), lead-214 (²¹⁴Pb), actinium-228 (²²⁸Ac), bismuth-212 (²¹²Bi) and lead-212 (²¹²Pb) from the naturally occurring uranium-238 (²³⁸U) and thorium-232 (²³²Th) decay series are commonly detected but have not been quantified or reported.

Vegetation

A summary of reported activities by WI DHS for vegetation samples is included in Table 4.  Results from the individual sample analyses are listed in Table 11.

Analysis of the vegetation samples showed no unusual activities.  The gamma isotopic analysis detected only small amounts of naturally occurring potassium-40 (⁴⁰K) and beryllium-7 (⁷Be) listed in Table 4.

Soil

A summary of reported activities by WI DHS for soil samples is included in Table 4.  Results from the individual sample analyses are listed in Table 11.

Analysis of the soil samples showed no unusual activities.  The naturally occurring radioisotopes potassium-40 (⁴⁰K) was detected in all samples.  The reported activities for cesium-137 (¹³⁷Cs) were also detected in previous years and are attributable to residual fallout from previous atmospheric nuclear weapons tests.  Naturally occurring radioisotopes such as radium-226 (²²⁶Ra), bismuth-214 (²¹⁴Bi), lead-214 (²¹⁴Pb), actinium-228 (²²⁸Ac), bismuth-212 (²¹²Bi) and lead-212 (²¹²Pb) from the naturally occurring uranium-238 (²³⁸U) and thorium-232 (²³²Th) decay series are commonly detected but have not been quantified or reported.

Dose to an Average Individual

Federal regulations 10 CFR 20, 10 CFR 50 Appendix I and 40 CFR 190 restrict the annual exposure of the population from all parts of the nuclear fuel cycle, including nuclear power plants. Doses resulting from gaseous and liquid effluent releases from the LACBWR facility are less than the limits as stated in these Federal regulations.

The WI DHS limits for permissible levels of radiation exposure from external sources in unrestricted areas are defined in the Wis. Adm. Code section DHS 157.23.  Doses resulting from gaseous and liquid effluent releases from the LACBWR facility are less than the limits as stated in Wis. Adm. Code section DHS 157.23.

References

State of Wisconsin, Wisconsin Administrative Code, DHS 157.23

U.S. Environmental Protection Agency, Environmental Radiation Requirements for Normal Operations of Activities in the Uranium Fuel Cycle, EPA 520/4-76-016, 40 CFR Part 190, November 1976.

U.S. Nuclear Regulatory Commission, Title 10, Part 20.

U.S. Nuclear Regulatory Commission, Title 10, Part 50, Appendix I.