Plutonium inventory

The spent firel issue is central to long-term fuel cycle policy, not simply because large volumes are threatening to clog the arteries of the nuclear power industry but because spent fuel is the repository of most of the worid s plutonium, some 1000 tons at present, and is already dispersed among the 30-odd countries in which nuclear power plants are located. The indefinite accumulation of these dispersed inventories has proliferation implications that are at least comparable in their gravity to the surplus weapons plutonium inventories in Russia... 

Attainment of the goal of balanced plutonium production and consumption and minimum inventory will require a number of decades. Paradoxically, achievement of the goal will be most important in the event that nuclear power is phased out, leaving large and increasingly accessible plutonium inventories in many countries if no provision for their destruction has been made. While the global abandonment of nuclear power is extremely... 

OVERSBY, V. M., MCPHEETERS, C. C., DEGUELDRE, C. Paratte, J. M. 1997. Control of civilian plutonium inventories using burning in a non-fertile fuel. Journal of Nuclear Materials, 245, 17-26. 

IAEA projections of plutonium inventories show that the rate of separation of civil plutonium and its rate of use will fall into balance in a few years. This is due to an enhanced capacity of MOX fuel production which will amount to 360 tonnes of heavy metal per year in 2000. Beyond this period, the inventory is expected to decrease modestly and level off at around 130 tonnes. Despite the efforts to reduce the current inventories of separated civil plutonium, the worldwide inventories still remain at a substantial level, as shown in Fig. 7.3. 

The speciation and chemical form of Pu in this sediment system has not been determined, but a fraction of the sediment-plutonium inventory may be in a chemical form (i.e., chelated, associated with organic matter, complexed with inorganic substances, or soluble) that is more mobile in the system than the balance of the inventory. While ingestion of sediment appears responsible for the highest levels of Pu (body burden) in fish, this mechanism apparently has not enhanced availability of Pu to biota because concentration factors for biota in WOL were relatively low compared to those observed at other study sites. Concentration factors for biota of WOL were low even though 12% of the plutonium in the water column was a soluble form (Table VI). 

The shorter time allowed for LMFBR fuel to cool is desirable for economic reasons to reduce the amount of plutonium inventory outside of the reactor. The rate at which plutonium is discharged from the LMFBR is eight times as high as from the uranium-fueled LWR (Fig. 3.31) and twice as high as from the LWR with plutonium recycle (Fig. 3.32). 

The plutonium inventory monitoring system (PIMS) is a network of 142 He neutron detectors in moderating enclosures, which are installed in a plutonium-powder process area at fixed positions outside of process glove boxes and the ventilation system (Simpson et al. 1998 Parvin 2007 Whitehouse et al. 2004). The collected neutron counts are processed in a matrix approach to image the neutron field of the process area. Any change to the in-process inventory will be detected and can be accounted for on a near real-time basis. The PIMS will also be used to verify the clean out and to measure any residual material. The PIMS is operator-owned equipment used jointly with the inspectorate. Appropriate authentication measures are therefore in place to validate the measurement results. 

Plutonium consumption and initial plutonium inventory should be as low as possible. 

Only little information is available concerning the behavior of the actinides in the primary circuit purification system. If one assumes a plutonium purification factor identical to that of the cobalt isotopes, one could calculate the approximate level of the plutonium inventory of the ion exchanger beds. Such a calculation for... 

For the larger oxide-fuelled PFR, collocation of the reactor and its associated fuel plants was not practicable. The larger quantities of fuel involved favoured the industrial scale involvement of British Nuclear Fuels, whose Magnox reactor fuel reprocessing plant at Sellafield would provide the initial plutonium inventory. It was, therefore, decided that the PFR oxide fuel fabrication plant would be built and operated by BNFL at Sellafield and that fuel would then be transported to Dounreay as completed assemblies ready, after inspection and adjustment of the coolant flow control gags, for irradiation. The small experimental fast reactor fuel fabrication plant was moved from Dounreay to the AEA s Windscale Laboratory, adjacent to BNFL Sellafield, to provide R D support to the main fuel fiibrication plant and to supply small batches of experimental variants for incorporation by BNFL into DMSA clusters and driver fuel assemblies. 

In terms of amount, by far the most significant of the synthetic actinide elements is plutonium. Nuclear power production by fission in uranium produces as a byproduct approximately 50 tons per year world-wide of a mixture of plutonium isotopes. About 250 tons of plutonium is estimated to be in the world plutonium inventory, some still in unprocessed spent fuel assemblies from nuclear reactors. World inventory of plutonium by the year 2000 has been estimated at 2400 tons [57], Plutonium produced for nuclear weapons is mainly Pu, but plutonium produced as a by-product of energy production contains substantial amounts of °Pu, Pu, and Pu and small amounts of Pu [64]. The plutonium in the environment is due, in decreasing order of importance, to the testing of nuclear weapons in the atmosphere, the re-entry into the atmosphere and disintegration of satellites equipped with Pu power sources, and the processing of irradiated uranium fuel from nuclear reactors. 

Such an AC path is already being explored (eg, notably by India, Norway, China, Canada, and others), with the transition to a near self-sustaining predominantly thorium-fueled cycle being initiated by burning plutonium as the start-up fuel. The cycle thus reduces plutonium inventories/stocks during transition to a primarily thorium near breeder cycle using separated... 

Paradoxically and ironically, recycling has already occurred by disposing of excess weapons material, eg, Pu of and Th originally produced by military production reactors for use in now retired nuclear bombs. The US has down-blended and used material from Russia as fuel for commercial reactors, and the UK is looking at some similar approaches to reduce its plutonium inventory. ... 

Pu, and 242pu components are shown in the upper figure. The lower figure illustrates the fractional contribution of each isotope to the total plutonium inventory. The same graphic format is used for all five reactor types. 

The isotopic content reaches 20% " Pu at an exposure of about 300 GWD/MT. The zero reactivity point is reached at an exposure of about 750 GWD/MT. At the zero reactivity point, the total plutonium inventory has been reduced to about 228 kg with 77.2% of the initial loading destroyed. The parasitic plutonium (2 Pu plus components) is about 53% at the zero reactivity point. The residual plutonium is subcritical after the zero reactivity point and would have to be externally driven to achieve greater exposure. At an exposure of 925 GWD/MT, the residual plutonium is less than 10 kg of the initial 1,000 kg. 

The reactor analysis indicated that the small plutonium inventory could be reduced if design modifications... 

Fast reactors and cores with significant plutonium inventory are not considered. 

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