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Advanced Fission Technologies and Systems
Published in William J. Nuttall, Nuclear Renaissance, 2022
While separated plutonium from PUREX reprocessing is pure and well-characterised if compared to the partitioned waste streams usually considered for transmutation, there is however a specific problem relating to the older UK plutonium inventory. In 1998, it was already being reported that the isotope plutonium-241 comprised 9.9% of the plutonium in UK AGR spent fuel, and 14.7% in LWR spent fuel [172]. This plutonium-241 component decays with a half-life of 14 years to form americium-241 (half-life 433 years) [173]. As discussed in Chapter 5, this americium isotope is particularly problematic if placed in a thermal neutron flux (e.g. in an LWR MOX fuel cycle) as curium isotopes can result. Curium is an extremely nasty and highly radioactive element that is best avoided, if at all possible. For this reason, americium removal would be wise, but it represents an expensive and rather troublesome part of the management of old plutonium, if it is to be used as a MOX fuel in conventional thermal reactors, such as LWRs. The americium build-up in the UK separated plutonium would not be such a problem were the United Kingdom to still have in mind a fast reactor power programme, but those days are either far in the past (pre-1994), or still lie in the future (Generation IV) depending on how one looks at that story. The problem of placing americium isotopes in a thermal neutron flux is illustrated by Figures III.8.4 and III.8.5 from H Gruppelaar et al. [153]. These ideas are also discussed in a paper by R J Konings et al. [174].
Applied Chemistry and Physics
Published in Robert A. Burke, Applied Chemistry and Physics, 2020
Symbols and names of elements are derived from a number of sources. They may have been named after the person who discovered the element. For example, W which is the symbol for tungsten is named after Wolfram, the discoverer. Other elements are named after famous scientists, universities, cities and states. Es is the symbol for einsteinium, named after Albert Einstein. Cm is the symbol for curium, named after Madam Curie. Bk is the symbol for berkelium, named after the city of Berkeley, California. Cf is the symbol for the element californium, named after the state of California. Other element names come from Latin, German, Greek and English languages. In the case of sodium, Na comes from the Latin word for natrium. Au, the symbol for gold, comes from aurum, meaning “shining down” in Latin. Cu (copper) comes from the Latin cuprum or cyprium because the Roman source for copper was the island of Cyprus. Fe (iron) comes from the Latin ferrum. Bromine means “stinch” in Greek. Rubidium means red in color. Mercury is sometimes referred to as quick silver. Sulfur is referred to as brimstone in the Bible.
Qualification of Metallic Fuel Data for Advanced SFR Applications
Published in Nuclear Technology, 2023
Abdellatif M. Yacout, Kun Mo, Aaron Oaks, Michael Billone, Yinbin Miao, Jeffrey Alicz
The fuel pins experienced various irradiation conditions in the EBR-II. As mentioned in Sec. II, the fuel pin operating conditions were calculated using a collection of ANL analysis codes, including axial distributions for power, temperatures, fluences, burnups, and isotopic densities. Part of the data, mainly the neutronics calculations, was inherited from the EBR-II Physics Analysis Database.18,34,35 In the FIPD, the operating conditions of a fuel pin can be divided into thermal-hydraulic, neutronic, and isotopic density data. The thermal-hydraulic data include temperature distributions for the coolant, cladding (outer surface, mid wall, and inner surface), and fuel (outer surface and centerline). The neutronics data include burnup, power density (W/cm3) (and corresponding linear power in kW/ft), total and fast fluence (n/cm2), and cladding displacements per atom (DPA). Finally, the calculated isotopic densities are available for 21 different isotopes across uranium, plutonium, neptunium, americium, and curium.
Plutonium-238 Production Program Results, Implications, and Projections from Irradiation and Examination of Initial NpO2 Test Targets for Improved Production
Published in Nuclear Technology, 2022
Emory D. Collins, Robert N. Morris, Joel L. McDuffee, Padhraic L. Mulligan, Jeffrey S. Delashmitt, Steven R. Sherman, Raymond J. Vedder, Robert M. Wham
Aluminum-clad, aluminum matrix–heavy metal oxide cermet targets are typically used for irradiation in research reactors such as the HFIR and the ATR. This type of target design was chosen for 238Pu production because it has been used successfully for many years for the irradiation of plutonium, americium, and curium in the transuranium element production program at ORNL. However, only 5 to 50 targets per year have been required to be fabricated, irradiated, and processed for the transuranium element production needed; whereas, for production of kilogram amounts of 238Pu per year, with the 237Np limited to <15% per irradiation (step 5 in Fig. 2), multikilogram quantities of 237Np must be irradiated each year. This much larger amount requires tens of thousands of pellets and several hundred targets to be fabricated, transported to and from the reactors, irradiated, and processed each year. In addition, the production rate is limited by the research reactor’s operating time, the volume of available irradiation space in the reactor, and the 237NpO2 loading per target, which is limited by heat transfer and the 660°C melting point of aluminum. Thus, achieving the needed production rate of 238Pu is challenging, and irradiations in both the HFIR at ORNL and the ATR at the Idaho National Laboratory will be required.
Activity and weight ratios of cesium, uranium, plutonium, and curium isotopes based on elaborate inventory calculations of Fukushima Dai-ichi NPP units 1 to 3
Published in Journal of Nuclear Science and Technology, 2022
Table 1 lists the main heavy and fission product nuclides, their half-lives [11], the biases ((C/E-1) %) of the nuclide inventories calculated with CASMO5 (JENDL-4.0 base nuclear library) [10], here C and E mean the calculated and measured inventories, respectively. It also lists the standard errors in the biases, the bias-corrected nuclide inventories just before the accident, and the standard errors in the inventories. The standard errors in the biases were calculated by dividing the standard deviations listed in the reference [10] by the square root of the number of the samples. The nuclide in Table 1 includes the nuclides which will not be referred to as the activity and weight ratios. They are supplementary information for the related studies. The activity and weight ratios of cesium, uranium, plutonium, and curium were calculated using the bias-corrected nuclide inventories. The standard errors in the ratios were also obtained using the standard errors in the biases. They are listed in the tables in Section 3.