Nuclear fuel, long-lived actinide elements

What complicates the environmental situation is that plutonium is not the only transuranium element produced in nuclear reactors. Curium and americium are also formed by multiple neutron capture (see Fig. 14.1). The amounts of long-lived actinides in spent fuel as a function of time after removal from a reactor are shown in Table 14.12. The elements americium and curium formed in the reactor undergo radioactive decay to produce radioactive daughter species [57] ... 

Nuclear fuel reprocessing and partitioning allow recycling of useful fissionable materials such as uranium and plutonium, and remove harmful long-lived minor actinides (americium and curium). It is necessary also for safety storage of high-level liquid wastes(l). In order to improve efficiency of mutual separation between lanthanide and actinide elements, design of useful extractants are requisite. 

This chapter first introduces the fundamentals of radioactivity and its environmental significance. The following sections focus on the geochemistry of uranium and uranium ore deposits as the basis of the nuclear fuel cycle. Later sections consider nuclear power and the geochemistry of important radionuclides in nuclear wastes, with emphasis on the actinide elements and some of their fission products which make nuclear wastes a potential problem for future generations because of their very long half-lives. 

All actinide elements of the 5/series are radioactive. Th and U are long lived and occur in minerals that also contain their radioactive decay products. Elements beyond uranium are made artificially, by bombardment with neutrons or with nuclei. Uranium and plutonium are used as nuclear fuels. 

An option to recycle all self-produced transuranic (TRU) elements including minor actinides or to utilize spent nuclear fuel from other reactors, e.g. LWRs, is being examined (e.g., KALIMER, PEACER) both of the abovementioned approaches result in the reduction of long-lived high level waste. 

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