Analyzing Nuclear Fuel Cycles from Isotopic Ratios of Waste Products Applicable to Measurement by Accelerator Mass Spectrometry

Abstract

An extensive study was conducted to determine isotopic ratios of nuclides in spent fuel that may be utilized to reveal historical characteristics of a nuclear reactor cycle. This forensic information is important to determine the origin of unknown nuclear waste. The distribution of isotopes in waste products provides information about a nuclear fuel cycle, even when the isotopes of uranium and plutonium are removed through chemical processing. Several different reactor cycles of the PWR, BWR, CANDU, and LMFBR were simulated for this work with the ORIGEN-ARP and ORIGEN 2.2 codes. The spent fuel nuclide concentrations of these reactors were analyzed to find the most informative isotopic ratios indicative of irradiation cycle length and reactor design. Special focus was given to long-lived and stable fission products that would be present many years after their creation. For such nuclides, mass spectrometry analysis methods often have better detection limits than classic gamma-ray spectroscopy. The isotopic ratios were found to be good indicators of fuel cycle length and are well suited for analysis by accelerator mass spectroscopy. Sm

Principle and Uncertainty Quantification of an Experiment Designed to Infer Actinide Neutron Capture Cross-Sections

“…To date this effort has been motivated by the need to provide ultra-sensitive metrology for environmental assay and emerging basic science applications. However, this technique could also potentially be used in other important nuclear energy applications including studies of nuclear fuel cycles and radioactive waste disposal [3].…”

“…As a result, long halflives and low gamma yields are not problems for AMS detection limits. Hence, AMS is a sensitive technique for measuring minute quantities of long-lived isotopes accurately in the presence of more abundant ones (abundances as low as 10 -12 -10 -15 can be detected) using very small amounts of material [2,3]. The precision of AMS measurements is typically between 0.5% and 2% for standard applications like carbon dating [4].…”

Simultaneous Determination of Transuranium Radionuclides for Nuclear Forensics by Compact Accelerator Mass Spectrometry

“…Most of the transuranium isotopes (TRUs), including those of neptunium (Np), plutonium (Pu), americium (Am), and curium (Cm), are anthropogenic radionuclides and could be used as a signature of human nuclear activities. − The isotopic ratios of transuranium (so-called characteristic fingerprint) in the samples are critical for the accurate identification of radioactive sources and age dating of nuclear material. For instance, the 240 Pu/ 239 Pu and 237 Np/ 239 Pu atomic ratios as excellent indicators are an important signature reflecting the type of nuclear reactor design, and the parent/daughter ratios (e.g., 241 Pu/ 241 Am, 244 Cm/ 240 Pu) are unique clock indicators for estimation of the production date of the nuclear material. Besides environmental and nuclear samples, noninvasive biological samples (e.g., hair, urine) for TRU radionuclides could provide the source information of the exposure sites and the circumstance .…”

“…Besides environmental and nuclear samples, noninvasive biological samples (e.g., hair, urine) for TRU radionuclides could provide the source information of the exposure sites and the circumstance . The major challenge for such work is that the sample size is often very small, and a highly sensitive method to measure the attogram–femtogram level radionuclides is therefore needed. ,− In order to achieve detection at such levels, this usually requires a complete separation of TRUs from the matrix and potential interferences in combination with the measurement techniques with high sensitivity.…”