Research Reactor Aluminum Spent Fuel Treatment Options for Disposal (1998) / Chapter Skim
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2. Treatment Options for Aluminum Spent Nuclear Fuel
2. Treatment Options for Aluminum Spent Nuclear Fuel
Pages 30-55
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From page 30... ...
The second part of the chapter provides an analysis of this work in response to He first charge of the statement of task. l ~ As noted in Chapter 1, the term "aluminum spent fuel" refers to aluminum-clad or aluminum-matrix spent nuclear fuel from foreign and domestic research reactors, the subject of this report.
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From page 31... ...
As noted above, Be focus of the Task Team's work was on technologies for treating aluminum spent filet that could be used in the place of conventional reprocessing Savannah River currently has two reprocessing facilities in operation (the F and H Canyons; see Figure 2.1) 2 Conventional reprocessing involves the dissolution of aluminum spent fuel in acid followed by the chemical recovery of uranium.
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From page 32... ...
In principle, the Canyons also could be used to process the inventory of aluminum spent fired from research reactors, which is small in comparison to the inventory of aluminum spent fuel from production reactors. In fact, some aluminum
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From page 33... ...
The need to develop alternative treatment technologies for aluminum spent fuel was necessitated by DOE's policy to phase out reprocessing. The policy to phase-out reprocessing at DOE sites was announced by the Secretary of Energy in February 1992 (DOE, 1992a)
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From page 34... ...
According to Savannah River staff, this study also may address reprocessing of domestic research reactor filet. Because the receipt of aluminum spent fuel currently is scheduled to continue for several decades beyond the scheduled operation of the Canyons at Savannah River, non-reprocessing treatment options for this spent filet will have to be planned unless the present schedules are revised.
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From page 35... ...
Jack DeVine, the chair of Task Team, commented that a solicitation for treatment ideas also was distributed to DOE laboratones. ~ At present, all of the aluminum spent research reactor fuel at Savannah River is being stored underwater.
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From page 36... ...
it In this option, spent fuel would be loaded into cans, which in turn would be placed in stainless steel canisters and encapsulated in high-level waste glass. The Task Team eliminated this option because of the technical difficulties associated with the low melting point of aluminum spent fuel.
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From page 37... ...
. , " In this treatment option, the spent fuel is shredded mechanically and combined with depleted uranium.
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From page 38... ...
Press and Dilute Treatment. The dried and sized aluminum spent fuel assemblies are physically pressed into sandwiches along with sheets of depleted uranium to produce dimensionally uniform packages with composite 235U enrichments of 20 percent or less by mass.
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From page 39... ...
is combined with depleted uranium and melted in a plasma arc furnace at high temperature to produce a vitreous ceramic with a uranium enrichment of 20 percent or less by mass. The Task Team estimated that at a 20 percent composite 23su enrichment, about 400 canisters would be required to dispose of all of the aluminum spent fuel to be sent to the repository.
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From page 40... ...
The solution is transferred to a vitrification plant where it is combined with flit to produce glass logs. The Task Team estimated that about 800 DWPF-size glass lowest would be produced to dispose of all of the aluminum spent fuel to be sent to the repository.
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From page 41... ...
The foreign research reactor spent fuel ElS (DOE, 1996c) establishes a target date of 2000 for implementation of an alternative technology for aluminum spent fiiel.
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From page 42... ...
No score was calculated by the Task Team for processing and co-disposal treatment, because, as noted previously, the team was directed to consider alternatives to conventional reprocessing. The Task Team performed a simple sensitivity analysis to determine whether the relative rankings would change if any of the ranking criteria were eliminated from Me analysis.
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44 On S:: .e sit U
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From page 45... ...
The Task Team recommended direct co-disposal treatment as the primary treatment option, with melt and dilute treatment as a "parallel" option. The task team noted that direct co-disposal treatment "is the simplest of the technology options evaluated, and seems technically achievable in all respects, at moderate cost and on a timetable consistent with DOE's needs" (Task Team, 1996, p.
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From page 46... ...
RESPONSE TO FIRST CHARGE IN STATEMENT OF TASK The first charge of the statement of task involves an examination of the set of technologies chosen by DOE for treatment of aluminum spent filet and to the identification of other alternatives that DOE might
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From page 47... ...
, and a solicitation to DOE laboratories to identify alternative treatment options. There was no effort made to perform a systematic search for treatment technologies in use in other countries or industries that might be applied to aluminum spent fuel.
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From page 48... ...
, then there is no obvious treatment and disposition pathway for this fuel. The answer to the second question was Me methodology used to screen and rank the treatment alternatives technically sound and did it lead to Me selection of appropriate primary and backup treatment options?
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The Task Team was consistent in its application of the ranking methodology to the various treatment options, although the various treatment alternatives were at different stages of maturity (e.g., the direct co-disposal treatment technology is more mature than the plasma arc treatment technology)
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The third question posed abov~are the primary and backup treatment options likely to work as described and produce acceptable waste forms? has two parts: (~)
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From page 51... ...
Similarly, offgas systems are in use in several other applications and have even been utilized successfully to capture fission products from the pyrometallurg~cal processing of the highly radioactive spent files Tom the Experimental Breeder Reactor (ANL, 1963; see Figure 2.4~. Although such systems cannot be used directly for aluminum spent fuel treatment, they should be readily adaptable for treating aluminum spent fuel, much of which has been in storage for more than a decade and has lost to decay much of its gaseous radionuclide inventory.
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From page 52... ...
In particular, not enough is known at present about electrometallurgical treatment, which was selected as the backup option by the Task Team, to determine whether it will work as described, and additional development work will have to be done to determine the feasibility of applying this treatment technology to aluminum spent fuel.22 The uranium removal process has been demonstrated successfully on uranium metal-based spent nuclear fuel, but the electrorefining step for removal of aluminum requires further development and testing. In addition, more work must be done to demonstrate that all of the waste streams from this process either can be recycled or will be acceptable for disposal in a repository.
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From page 53... ...
that is lowered over the furnace during melting to capture Me gaseous fission products. SOURCE: Argonne National Laboratory.
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elements for return to the reactor. These fumaces were operated for five years in the m~-1960s as part of the pyrometallurg~cal fuel cycle used to recycle HEU filet from the Experimental Breeder Reactor IT.
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From page 55... ...
24 See also the comments of consultant Harry Harmon in Appendix D 25 As noted previously, DOE is expected to release a study on the proliferation implications of conventional reprocessing of aluminum spent fuel from foreign research reactors in He second quarter of FY 98.
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