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Radionuclides in Drinking Water

Module 5: EPA Approved Radiochemical Drinking Water Methods

Description

"EPA Approved Radiochemical Drinking Water Methods" reviews the methods and requirements of the six most commonly used EPA radiochemical drinking water methods:

  • EPA Method 906.0 for the analysis of tritium in drinking water;
  • EPA Method 900.0 for the measurement of gross alpha and gross beta;
  • EPA Method 903.1 for analysis of radium-226;
  • EPA Method 904.0 for the analysis of radium-228;
  • EPA Method 908.0 for total isotopic uranium; and
  • EPA Method 901.1 for gamma-emitting radionuclides.

The tutorials discuss limitations and, where applicable, recent authorized improvements. Each section of this module should take approximately 45 minutes to complete.

Instructional Resources

This module is divided into 6 tutorials. Each tutorial is presented as a self-paced Adobe Flash video with audio narration. The learning aids that are provided for you to use in this module, which you may access via the links in the "Instructional Resources" panel on the right, include the "Prescribed Procedures for Measurement of Radioactivity in Drinking Water" (EPA Methods Manual) chapters for each of the methods described in the tutorials. You may wish to print out the PDF transcript of the audio narration, also available from a link in the "Instructional Resources" panel. The "Links to Additional Information" provide more in-depth discussions of these topic areas.

 

Tutorial 5.1 - Tritium Analysis by Liquid Scintillation Counting (EPA Method 906.0)

At the end of this tutorial you will be able to:

  • Describe the atomic structure of the tritium atom and the common anthropogenic sources of tritium in the environment.
  • List the basic steps involved in EPA Method 906.0 for the analysis of tritium in drinking water.
  • Calculate the Figure of Merit, the recovery correction factor (rcf), and the amount of tritium in a water sample.
  • List 5 sources of error or interference frequently encountered during the analysis of tritium.

Tutorial 5.2 - Measurement of Gross Alpha and Gross Beta (EPA Method 900.0)

At the end of this tutorial you will be able to:

  • Define the term "self-absorption" and how it relates to GPC counting efficiency.
  • Calculate the cross-talk factor, the Detection Level (DL), the activity, and the uncertainty for gross alpha and gross beta determinations.
  • Describe the analyses required if the gross alpha or gross beta activity exceeds the Maximum Contaminant Level (MCL).
  • List 3 limitations to EPA Method 900.0.

Tutorial 5.3 - Radium-226 Analysis by EPA Method 903.1

At the end of this tutorial you will be able to:

  • Define the terms "supported" and "unsupported" as they apply to radionuclide decay chains and describe how these phenomena impact the amount of Ra-226 in the environment and in the laboratory.
  • Explain how the volatility and short half-life of Rn-222 are exploited in Method 903.1 to specifically quantitate Ra-226.
  • Describe the components of a typical Ra-226 analysis apparatus and the steps required to set up and calibrate the instrument.
  • Calculate the amount of Ra-226 in a water sample at the time of collection based on the measurement of Rn-222 ingrown in the laboratory.

Tutorial 5.4 - Radium-228 Analysis by GPC (EPA Method 904.0)

At the end of this tutorial you will be able to:

  • Describe how "supported" and "unsupported" decay phenomena impact the concentration of Ra-228 in the environment, and how they are utilized in the laboratory for analysis of Ra-228.
  • Describe the steps involved in EPA Method 904.0 for the analysis of Ra-228 in drinking water.
  • Explain why count times longer than about 280 minutes result in higher detection limits for Ra-228.
  • Calculate the amount of Ra-228 in a water sample at the time of collection based on the measurement of Ac-228 ingrown in the laboratory.

Tutorial 5.5 - Uranium by Gross Alpha (EPA Method 908.0) and by Alpha Spectrometry (ASTM Method D3972)

At the end of this tutorial you will be able to:

  • Explain the relationship between activity and the mass of uranium as described in the drinking water regulations.
  • Describe how the measurement of the isotopic activity for uranium in a sample helps to determine the type of uranium that may be present.
  • Describe the principal differences between EPA Method 908.0 and ASTM Method D3972 when determining uranium activity.
  • Calculate the activity and the mass of uranium in a water sample.

Tutorial 5.6 - Gamma Spectrometry 2: Calibrations, Presets, and EPA Method 901.1

At the end of this tutorial you will be able to:

  • List the steps involved in gamma detector energy and efficiency calibrations and state their importance for the accurate measurement of radionuclides.
  • Properly select and set the gamma spectrometer's preset parameters.
  • Verify the reported data.
  • State the general requirements of EPA Method 901.1 "Gamma Emitting Radionuclides in Drinking Water" and list 4 improvements to the original method that are now allowed.

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