7010 INTRODUCTION* 7010 A. General Discussion 1. Occurrence and Monitoring Specific radionuclide measurements must be made if dose estimates are needed [e.g., when gross analyses1 results exceed established action limits (regulatory or other) or long-term trends are being monitored]. They usually are more expensive and time-consuming than a gross analysis. Specific measurements identify radionuclides by the type and energy of emitted radiation, chemical techniques, half-life, or some combination of these. Gamma-emitting radionuclides can be measured rapidly and with minimal sample preparation via gamma spectrometry. Chemical separations make it possible to improve measurement results by increasing the quantity of sample that can be measured and decreasing interference from non-target radionuclides in samples. Knowing the chemical and radiochemical characteristics of the measured radionuclide is critical for satisfactory results. Gross alpha and gross beta results cannot provide accurate information about radionuclides whose energies are significantly different from those of the calibration standard. When concentrating water samples via evaporation, certain radionuclides (e.g., radioiodine, polonium, tritium, and carbon-14) may be lost to volatilization. If the sample is ignited, the chance of volatilization loss is even greater. When analyzing samples containing uranium and thorium, keep in mind that members of these series are rarely present in secular equilibrium. Identifying short-lived radionuclides, which may not be in secular equilibrium during sampling, may require that samples be analyzed shortly after collection and that analysts consider the dynamic nature of radionuclide concentrations as a result of decay and ingrowth phenomena. Radioactivity in water and wastewater originates from both natural sources and human activities (e.g., nuclear fuel-related operations, from mining to reprocessing; medical uses of radioisotopes; industrial uses of radioisotopes; worldwide fallout from atmospheric testing of nuclear devices; and enhanced concentration of naturally occurring radionuclides). Water and wastewater monitoring programs should be designed to realistically assess the degree of radioactive contamination. In some cases (e.g., compliance monitoring for drinking water), the conditions are clearly defined.1 In others, it may be necessary to examine the individual situation2 to determine the critical radionuclide(s), the critical pathway by which such radionuclide(s) move(s) through the environment, and a critical population group that is exposed as a result. This approach will help narrow the list of possible radionuclides to monitor. A relevant list of the most hazardous radionuclides can be created by examining the radioactivity concentration standards issued by the International Committee on Radiation Protection (ICRP),3 the Federal Radiation Council (FRC),4 the National Committee on Radiation Protection and Measurement (NCRP),2 the U.S. Environmental Protection Agency,1 and agencies in other countries. Applicable regulatory standards and action levels may vary from state to state in the USA, as well as from country to country. Monitoring programs should provide both assurances when environmental conditions are safe and adequate warning when they are not so proper precautions can be taken. Therefore, it is necessary to establish baselines for naturally occurring radionuclides (kinds and quantities) so changes can be measured. This will help decision-makers make sound judgments on the hazardous or nonhazardous nature of increased concentrations. 3. References 1. U.S. ENVIRONMENTAL PROTECTION AGENCY. 2000. National primary drinking water regulations; radionuclides; final rule. 40 CFR Parts 9, 141 & 142. Fed. Reg. 65(236):76708. 2. U.S. ENVIRONMENTAL PROTECTION AGENCY. 2004. National primary drinking water regulations: analytical method for uranium. Fed. Reg. 69(164):52176. 3. U.S. ENVIRONMENTAL PROTECTION AGENCY. 2002. Implementation Guidance for Radionuclides, EPA 816-F-00-002. U.S. Environmental Protection Agency, Off. Ground Water and Drinking Water, Washington, D.C. Available at http://water.epa.gov/lawsregs/rulesregs/sdwa/radionuclides/compliancehelp.cfm. Accessed August 2011. 4. NATIONAL COMMITTEE on RADIATION PROTECTION and MEASUREMENTS. 1959. Maximum Permissible Body Burdens and Maximum Permissible Concentrations of Radionuclides in Air and Water for Occupational Exposure, NBS Handbook No. 69, pp. 1, 17, 37, 38 & 93. National Committee on Radiation Protection and Measurements, Bethesda, Md. 2. Types of Measurement Meaningful measurements require careful application of good scientific techniques. The types of measurements to be made depend on the testing objectives. Gross alpha and gross beta screening measurements are relatively inexpensive, can be completed quickly, and are useful for determining whether further analysis for specific radionuclides may be merited. However, they do not provide information about the sample’s isotopic composition, cannot be used to estimate radiation dose, and are subject to significant bias if the sample contains other radionuclides or has a high concentration of dissolved solids. While calibration standards that closely match the samples’ characteristics and carefully applied self-absorption and cross-talk corrections may help minimize bias and optimize precision, gross activity measurements are generally not capable of providing reliable, unbiased results of known precision that reflect the samples’ isotopic makeup. * Approved by Standard Methods Committee, 2011. Joint Task Group: Robert T. Shannon (chair), Shiyamalie R. Ruberu, Bahman Parsa. 10-1 INTRODUCTION (7010)/Sample Collection and Preservation 4. Bibliography INTERNATIONAL COMMISSION on RADIATION PROTECTION. 1979. Limits for Intakes of Radionuclides by Workers, ICRP Publ. 30. Pergamon Press, New York, N.Y. FRIEDLANDER, G., J.W. KENNEDY, E.S. MACIAS & J.M. MILLER. 1981. Nuclear and Radiochemistry, 3rd ed. John Wiley & Sons, New York, N.Y. FIRESTONE, R.B., V.S. SHIRLEY, C.M. BAGLIN, S.Y.F. CHU & J.J. ZIPKIN. 1996. Table of Isotopes, 8th ed. John Wiley & Sons, New York, N.Y.INTRODUCTION (7010)/Sample Collection and PreservationFirestone, R.B., S.Y.F. Chu & C.M. Baglin. 1999. Table of Isotopes, Update to 8th ed. John Wiley & Sons, New York, N.Y. FEDERAL RADIATION COUNCIL. 1961. Background Material for the Development of Radiation Protection Standards, Rep. No. 2 (Sept.). U.S. Government Printing Off., Washington, D.C. INTERNATIONAL ATOMIC ENERGY AGENCY. 1971. Disposal of Radioactive Wastes into Rivers, Lakes, and Estuaries, IAEA Safety Ser. No. 36, St. 1/PUB 283. International Atomic Energy Agency, Vienna, Austria. NATIONAL COUNCIL on RADIATION PROTECTION and MEASUREMENTS. 1976. Environmental Radiation Measurements, NCRP Rep. No. 50. National Council on Radiation Protection and Measurements, Washington, D.C. 7010 B. Sample Collection and Preservation 1. Collection 2. Preservation The principles of representative water and wastewater sampling apply to sampling for radioactivity testing (see Section 1060). Because radioactive elements often are present in subnanogram quantities, a significant fraction may be lost via adsorption to the sampling container’s surface. Similarly, radionuclides may be largely or wholly adsorbed on the surface of suspended particles.Sample container sizes vary from 0.02 to 18 L, depending on required analyses. Use plastic (polyethylene or equivalent) or glass containers (required for tritium). Consider the possibility of radioactivity deposition on container and equipment surfaces, which may cause a loss of radioactivity. To eliminate possible cross-contamination of subsequent samples, do not reuse sample containers. For general information on sample preservation, see Section 1060. For guidance on sample handling, preservation, and holding times for compliance measurements of radionuclides in drinking water in the United States, see Table 7010:I. Optimally, add preservative at time of collection unless sample will be separated into suspended and dissolved fractions, but do not delay acid addition beyond 5 d. Use conc nitric (HNO3) or hydrochloric (HCl) acid to obtain a pH h, then recheck pH before analysis to verify successful acidification. For further details, see references.1–3 Reagents used to preserve samples should be tested for concentrations of radioactivity that could compromise test results (e.g., by using a reagent or method blank). TABLE 7010:I. SAMPLE HANDLING, PRESERVATION, AND HOLDING TIMES Constituent Preservative* Container† Maximum Holding Time‡§ Gross alpha Gross beta Radium-226 Radium-228 Radon-222 Uranium, natural Radioactive strontium Radioactive iodine Tritium Photon-emitters Conc HNO3 or HCl to pH ⬍2储 Conc HNO3 or HCl to pH ⬍2储 Conc HNO3 or HCl to pH ⬍2 Conc HNO3 or HCl to pH ⬍2 Cool Conc HNO3 or HCl to pH ⬍2 Conc HNO3 or HCl to pH ⬍2 None None Conc HNO3 or HCl to pH P or G P or G P or G P or G G with TFE-lined septum P or G P or G P or G P or G P or G 6 months 6 months 6 months 6 months 8 d# 6 months 6 months 14 d 6 months 6 months * (All except radon-222 samples). Add preservative at time of sample collection unless suspended solids activity is to be measured. If sample must be shipped to a laboratory or storage area, acidification (in original sample container) may be delayed for no more than 5 d. At least 16 h must elapse between acidification and analysis. †P ⫽ plastic, hard or soft; G ⫽ glass, hard or soft. ‡Holding time is time elapsed between sampling and analysis. In all cases, analyze samples as soon after collection as possible. §A 1-year holding time allows for compositing four quarterly samples. 㛳If HCl is used to acidify samples that will be analyzed for gross alpha or gross beta activities, the chloride salts must be converted to nitrate salts by evaporation with nitric acid before transferring samples to planchets. # When analyzing short-lived radionuclides, adjust maximum holding time based on the radionuclide’s half-life (e.g., 72 h for Ra-224). ** Cooling at 4°C is recommended. Large temperature changes will cause dissolved radon to outgas from sample. 10-2 INTRODUCTION (7010)/Sample Collection and Preservation 3. Wastewater Samples ical composition of wastes, the behavior of radioelements, and the quantity of radioisotopes in use appears in the literature.4,5 Wastewater often contains more nonradioactive suspended and dissolved solids than most drinking, surface, or ground water does. Often, the sample’s radioactivity is distributed between the solid and liquid phases. Using carriers in the analysis is generally ineffective unless the solid phase is dissolved; even then, high solids content in the sample may interfere with radioanalytical procedures. Radioelements may exhibit unusual chemical characteristics due to complexing agents or the waste-production method. For example, tritium may be part of an organic compound when used in the manufacture of luminous articles. Radioiodine from hospitals may occur as complex organic compounds, while the fission products from processing spent nuclear fuels typically contain elemental and iodide forms. Uranium and thorium progeny often exist as inorganic complexes (rather than oxides) after processing in uranium mills. Strontium-90 titanate waste from radioisotope heat sources is quite insoluble when compared to most other strontium wastes. Valuable information on the chem- 4. References 1. U.S. GEOLOGICAL SURVEY. 1977. Methods for Determination of Radioactive Substances in Water and Fluvial Sediments. U.S. Government Printing Off., Washington, D.C. 2. U.S. DEPARTMENT of ENERGY. 1997. EML Procedures Manual, HASL300, 28th ed. (rev.), Vol. 1. Environmental Measurements Lab., U.S. Dep. Energy, New York, N.Y. Available online at http://www.orau.org/ptp/PTP%20Library/library/DOE/eml/hasl300/ HASL300TOC.htm. Accessed May 2011. 3. U.S. ENVIRONMENTAL PROTECTION AGENCY. 2005. Manual for the Certification of Laboratories Involved in Analyzing Public Drinking Water Supplies, 5th ed., EPA-815-R-05-004. U.S. Environmental Protection Agency, Washington, D.C. 4. INTERNATIONAL ATOMIC ENERGY AGENCY. 1960. Disposal of Radioactive Wastes. International Atomic Energy Agency, Vienna, Austria. 5. NEMEROW, N.L. 1963. Industrial Waste Treatment. Addison-Wesley, Reading, Mass. 10-3