skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Guidance on Radiochronometry

Abstract

Radiochronometry is the measurement of radioactive materials and their decay products to determine the “age” of the material. It differs from the practice of geochronology in that the materials (samples) are man-made, and in that the timespan of interest is confined to the nuclear era, i.e., since the discovery of fission in 1939. In radiochronometry, the “age” of the material ideally records the time when the sample was manufactured, or produced in the final form that is analyzed in the laboratory. It is an important predictive signature in a nuclear forensic investigation which can help in the attribution to a source. The calculation of this “age” can only be made if a model is invoked that allows simplification of the parent radionuclide to daughter isotope decay equation. The simplification required for this model is that the parent was purified completely from all traces of its daughter product at the time of sample preparation. Then, this “age” should be described as the “model age” from which a “model date” in the past can then be calculated. For this model date to represent the date of sample preparation, two other assumptions are required to be true. The first is that the materialmore » has remained a closed system since that time (i.e., that there has been no loss or gain of either parent or daughter), and the second is that the analyses are accurate.« less

Authors:
 [1];  [1];  [1]
  1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1321436
Report Number(s):
LLNL-TR-701379
TRN: US1700266
DOE Contract Number:
AC52-07NA27344
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY; 98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL PROTECTION; RADIOACTIVE MATERIALS; DAUGHTER PRODUCTS; NUCLEAR FORENSICS; SAMPLE PREPARATION; DECAY; AGE ESTIMATION; EQUATIONS; MATHEMATICAL MODELS; RECOMMENDATIONS

Citation Formats

Williams, Ross W., Gaffney, Amy M., and Kristo, Michael J. Guidance on Radiochronometry. United States: N. p., 2016. Web. doi:10.2172/1321436.
Williams, Ross W., Gaffney, Amy M., & Kristo, Michael J. Guidance on Radiochronometry. United States. doi:10.2172/1321436.
Williams, Ross W., Gaffney, Amy M., and Kristo, Michael J. Sun . "Guidance on Radiochronometry". United States. doi:10.2172/1321436. https://www.osti.gov/servlets/purl/1321436.
@article{osti_1321436,
title = {Guidance on Radiochronometry},
author = {Williams, Ross W. and Gaffney, Amy M. and Kristo, Michael J.},
abstractNote = {Radiochronometry is the measurement of radioactive materials and their decay products to determine the “age” of the material. It differs from the practice of geochronology in that the materials (samples) are man-made, and in that the timespan of interest is confined to the nuclear era, i.e., since the discovery of fission in 1939. In radiochronometry, the “age” of the material ideally records the time when the sample was manufactured, or produced in the final form that is analyzed in the laboratory. It is an important predictive signature in a nuclear forensic investigation which can help in the attribution to a source. The calculation of this “age” can only be made if a model is invoked that allows simplification of the parent radionuclide to daughter isotope decay equation. The simplification required for this model is that the parent was purified completely from all traces of its daughter product at the time of sample preparation. Then, this “age” should be described as the “model age” from which a “model date” in the past can then be calculated. For this model date to represent the date of sample preparation, two other assumptions are required to be true. The first is that the material has remained a closed system since that time (i.e., that there has been no loss or gain of either parent or daughter), and the second is that the analyses are accurate.},
doi = {10.2172/1321436},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sun Aug 21 00:00:00 EDT 2016},
month = {Sun Aug 21 00:00:00 EDT 2016}
}

Technical Report:

Save / Share:
  • In a recent international exercise, 10 international nuclear forensics laboratories successfully performed radiochronometry on 3 low-enriched uranium oxide samples, providing 12 analytical results using 3 different parent-daughter pairs serving as independent chronometers. The vast majority of the results were consistent with one another and consistent with the known processing history of the materials. In general, for these particular samples, mass spectrometry gave more accurate and more precise analytical results than decay counting measurements. In addition, the concordance of the 235U- 231Pa and 234U- 230Th chronometers confirmed the validity of the age dating assumption, increasing our confidence in the resulting conclusions.
  • This guidance manual was developed to address the practical aspects and issues pertaining to the Superfund risk-assessment process for both public health and environment concerns. Part 1, Guidance for Public Health Risk Assessments, supplements the Superfund Public Health Evaluation Manual and Superfund Exposure Assessment Manual and the Endangerment Assessment Handbook. Explicit guidance on technical matters which should be followed in developing public health risk assessments for EPA Region 1. The guidance addresses hazard identification, dose-response assessment, exposure assessment, risk characterization, and uncertainty/limitations. Part 2 of the manual, Guidance for Ecological Risk Assessments, addresses the collection of site-specific data needed tomore » support an ecological risk assessment, describes a framework for conducting the assessments, and provides several specific approaches for assessing risks to systems exposed to chemical contamination in different media.« less
  • The directive provides guidance on the compilation and release of waste-in lists and volumetric rankings to help Regions comply with the information release requirements of CERCLA section 122(e) and the information release and exchange policies outlined in OSWER directives 9835.12 and 9834.10.
  • In response to one of the requirements of Section 3004(o)(7) of RCRA, as amended by HSWA of 1984, the guidance presents guidance criteria for identifying areas of vulnerable hydrogeology. The guidance document specifies a method for determining ground-water vulnerability at hazardous waste facilities that requires the calculation of the time of travel (TOT) of ground water along a 100-foot flow line originating at the base of a hazardous-waste unit. Locations where the ground water moves fairly rapidly (those with short (TOTs) are considered more vulnerable than those with high TOTs). In general, EPA uses 100 years as the criterion formore » determining vulnerability; sites used for the disposal of hazardous waste are vulnerable if the ground water takes less than 100 years to travel 100 feet. The TOT concept integrates various aspects of hydrogeology into a single measure that reflects the potential for pollutant migration and exposure at a site. EPA developed the methodology for use with well-prepared, complete permit application data. The methodology depends heavily on the determination of effective porosity, hydraulic gradient, and hydraulic conductivity.« less
  • Because the per capita use of x rays in medicine and dentistry has expanded rapidly in the United States, the Environmental Protection Agency undertook a program in 1974 to develop, in cooperation with Federal Agencies, guidance for reducing unproductive exposures to medical radiation in Federal facilities while maintaining high standards of health care. The report examines the elements of good radiography, the fundamental objective of which is to obtain optimal diagnostic information with minimum patient exposure. Achievement of this objective requires elimination of clinically unproductive examinations, the use of appropriate and properly functioning equipment, and the use of optimal technicmore » by qualified operators. Recommendations are given in the report for the prescription and performance of medical and dental radiographic procedures. Twelve recommendations were developed from these and approved by the President on January 26, 1978 as Radiation Protection Guidance to Federal Agencies for Diagnostic X Rays (43FR 4377).« less