Plutonium fuel fabrication

Plutonium compounds, 19 687-691 protection against, 19 702 Plutonium dioxide, 19 688—689 Plutonium fuel fabrication facilities, 17 547 Plutonium-gallium alloys, 19 683-684 Plutonium halides, 19 689-690 Plutonium hexafluoride, 19 689 Plutonium hydrides, 19 690 Plutonium ions... 

In addition to the MOX fuel fabrication at the Plutonium Fuel Fabrication Facility for Joyo, Fugen (ATR), and BWRs in Japan, a new Plutonium Fuel Production Facility (PFPF) was constructed at Tokai Works of PNC. PFPF started production of initial core fuel of Monju in October 1989 and completed in January 1994. 

The Plutonium Fuel Fabrication Facility (PFFF), which started operation in 1972, has two fuel fabrication lines for Advanced Thermal Reactor (ATR) (10 ton MOX/year) and FBR (1 ton MOX/year). It has supplied the fuel necessary for the operation of ATR Fugen and FBR Joyo. 

Current designs for large BHWRs use concrete pressure vessels and a project for building a model vessel In Sweden by Scandinavian funds has started. Discussion of economic and technical parameters Indicated that expected trends for the cost of uranium, plutonium, fuel fabrication and reprocessing and the size of units all favour the economics of natural uranium HWRs In general and the highly neutron economic BHWRs in particular. 

The operational costs of a plutonium-fuel fabrication facility are expected to be two to three times those currently encountered for the uranium-based fuel fabrication facilities, because of such considerations as personnel safety, physical security, and environmental restraints. Plutonium-fuel fabrication times are also expected to be increased by factors of 2 or 3 when compared to uranium-fuel fabrication times for similar reasons. 

The uranium and thorium ore concentrates received by fuel fabrication plants still contain a variety of impurities, some of which may be quite effective neutron absorbers. Such impurities must be almost completely removed if they are not seriously to impair reactor performance. The thermal neutron capture cross sections of the more important contaminants, along with some typical maximum concentrations acceptable for fuel fabrication, are given in Table 9. The removal of these unwanted elements may be effected either by precipitation and fractional crystallization methods, or by solvent extraction. The former methods have been historically important but have now been superseded by solvent extraction with TBP. The thorium or uranium salts so produced are then of sufficient purity to be accepted for fuel preparation or uranium enrichment. Solvent extraction by TBP also forms the basis of the Purex process for separating uranium and plutonium, and the Thorex process for separating uranium and thorium, in irradiated fuels. These processes and the principles of solvent extraction are described in more detail in Section 65.2.4, but the chemistry of U022+ and Th4+ extraction by TBP is considered here. 

After feed acidity adjustment, plutonium and neptunium are recovered in the NPEX process, with high yields and sufficiently low impurity levels to make them suitable for MOX fuel fabrication. 

A mixture of uranium, neptunium, and plutonium to fabricate new mixed actinide-fuels (either metallic or oxides)... 

The fast breeder reactor cycle in this cycle, the spent fuel is similarly reprocessed and the uranium and plutonium fabricated into new fuel elements. However, they are recycled to fast breeder reactors, in which there is a central core of uranium/plutonium fuel surrounded by a blanket of depleted uranium (uranium from which most of the uranium-235 atoms have been removed during the process of enrichment) or to burner reactors. This depleted uranium consists mostly of uranium-238 atoms, some of which are converted to plutonium during irradiation. By suitable operation, fast breeder reactors thus can produce slightly more fuel than they consume, hence the name breeder (see Fig. 7.1). 

Alpha-bearing wastes (also called transuranic, plutonium-contaminated material, or alpha wastes) include wastes that are contaminated with enough long-lived, alpha-emitting nuclides to make near-surface disposal unacceptable. They arise principally from spent fuel reprocessing and mixed-oxide fuel fabrication. The wastes may he disposed of in a similar manner to HLW. 

Components in the process of design and fabrication of ceramic plutonium fuels at Hanford Engineering Development Laboratory (HEDL) are displayed in Figure 5. The plan for the fuel fabrication demonstration facility at HEDL is shown in Figure 6. 

At the tail end of a solvent extraction process, the solvents are separated from the solutes for recycle. In this application of solvent extraction, vacuum distillation is used to separate volatile zinc and magnesium from coprocessed uranium and plutonium and from the uranium product. Feed to vacuum distillation is solid alloy. Overhead and bottom products are likwise cast into a solid alloy. These vacuum distillation operations are conducted in separate cells. The actinide products are converted to oxide for fuel fabrication. 

Fuel Recycle Requirements. We asstime that the final product returned for fuel fabrication and recycle is a mixed uranium-plutonium dioxide material, partially decontaminated from fission products. The questions of fissile material enrichment, radiation levels, and required handling facilities are not addressed. 

One of the major components of the operational dose uptake assessment process has been the development of a detailed plant operational model broken down to an individual task level. Preparation of the model commenced early in the project design and drew on the extensive experience gained by BNFL over many years of designing, operating, and decommissioning plutonium plants and more recent experience of operating MOX fuel fabrication plants. This experience provided valuable data on both the manpower requirements and task durations for both process and maintenance operations and on the main potential short- and long-term sources of operational exposure and how these exposures could be adequately controlled. 

Program direction will include the study of cross-cutting efforts in both countries dealing with reactor safety, safety issues involving transportation, plutonium vitrification, treatment options, and mixed uranium-plutonium oxide fuel fabrication. The program will also focus attention on safety in the storage, handling, treatment, and disposition of fissile weapons materials. 

These presentations are reprinted in this volume as a formal ARW Proceedings in the NATO Science Series. The representative technical papers contained here cover nuclear material safety topics on the storage and disposition of excess plutonium and high enriched uranium (HEU) fissile materials, including vitrification, mixed oxide (MOX) fuel fabrication, plutonium ceramics, reprocessing, geologic disposal, transportation, and Russian regulatory processes. 

AR475 3.7 Monitoring of combustible gases and vapors in plutonium processing and fuel fabrication... 

AR482 3.14 Seismic design classification for plutonium processing and fuel fabrication plants,... 

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