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Title: Application of Modified Direct Denitration to Support the ORNL Coupled-End-to-End Demonstration in Production of Mixed Oxides Suitable for Pellet Fabrication

Abstract

The current and future development of the Modified Direct Denitration (MDD)process is in support of Oak Ridge National Laboratory's (ORNL) Coupled End-to-End (CETE) research, development, and demonstration (R&D) of proposed advanced fuel reprocessing and fuel fabrication processes. This work will involve the co-conversion of the U/Pu/Np product streams from the UREX+3 separation flow sheet utilizing the existing MDD glove-box setup and the in-cell co-conversion of the U/Pu/Np/Am/Cm product streams from the UREX+1a flow sheet. Characterization equipment is being procured and installed. Oxide powder studies are being done on calcination/reduction variables, as well as pressing and sintering of pellets to permit metallographic examinations.

Authors:
 [1];  [1];  [1];  [1]
  1. ORNL
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Nuclear Energy (NE)
OSTI Identifier:
958805
DOE Contract Number:
DE-AC05-00OR22725
Resource Type:
Conference
Resource Relation:
Conference: ANS Global 2007, Boise, ID, USA, 20070909, 20070913
Country of Publication:
United States
Language:
English
Subject:
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS; DENITRATION; FABRICATION; FLOWSHEETS; ORNL; OXIDES; PELLETS; PRESSING; PRODUCTION; REPROCESSING; SINTERING

Citation Formats

Walker, Elisabeth A, Vedder, Raymond James, Felker, Leslie Kevin, and Marschman, Steve. Application of Modified Direct Denitration to Support the ORNL Coupled-End-to-End Demonstration in Production of Mixed Oxides Suitable for Pellet Fabrication. United States: N. p., 2007. Web.
Walker, Elisabeth A, Vedder, Raymond James, Felker, Leslie Kevin, & Marschman, Steve. Application of Modified Direct Denitration to Support the ORNL Coupled-End-to-End Demonstration in Production of Mixed Oxides Suitable for Pellet Fabrication. United States.
Walker, Elisabeth A, Vedder, Raymond James, Felker, Leslie Kevin, and Marschman, Steve. Mon . "Application of Modified Direct Denitration to Support the ORNL Coupled-End-to-End Demonstration in Production of Mixed Oxides Suitable for Pellet Fabrication". United States. doi:.
@article{osti_958805,
title = {Application of Modified Direct Denitration to Support the ORNL Coupled-End-to-End Demonstration in Production of Mixed Oxides Suitable for Pellet Fabrication},
author = {Walker, Elisabeth A and Vedder, Raymond James and Felker, Leslie Kevin and Marschman, Steve},
abstractNote = {The current and future development of the Modified Direct Denitration (MDD)process is in support of Oak Ridge National Laboratory's (ORNL) Coupled End-to-End (CETE) research, development, and demonstration (R&D) of proposed advanced fuel reprocessing and fuel fabrication processes. This work will involve the co-conversion of the U/Pu/Np product streams from the UREX+3 separation flow sheet utilizing the existing MDD glove-box setup and the in-cell co-conversion of the U/Pu/Np/Am/Cm product streams from the UREX+1a flow sheet. Characterization equipment is being procured and installed. Oxide powder studies are being done on calcination/reduction variables, as well as pressing and sintering of pellets to permit metallographic examinations.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}

Conference:
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  • The current and future development of the Modified Direct Denitration (MDD) process is in support of Oak Ridge National Laboratory's (ORNL) Coupled End-to-End (CETE) research, development, and demonstration (R and D) of proposed advanced fuel reprocessing and fuel fabrication processes. This work will involve the co-conversion of the U/Pu/Np product streams from the UREX+3 separation flow sheet utilizing the existing MDD glove-box setup and the in-cell co-conversion of the U/Pu/Np/Am/Cm product streams from the UREX+1a flow sheet. Characterization equipment is being procured and installed. Oxide powder studies are being done on calcination/reduction variables, as well as pressing and sintering ofmore » pellets to permit metallographic examinations. (authors)« less
  • The fuel pellet fabrication experience described in this paper involved three different feed powders: coprecipitated PuO/sub 2/-UO/sub 2/ which was flash calcined in a fluidized bed; co-direct denitrated PuO/sub 2/-UO/sub 2/; and direct denitrated LWR recycle PuO/sub 2/ which was mechanically blended with natural UO/sub 2/. The objectives of this paper are twofold; first, to demonstrate that acceptable quality fuel pellets were fabricated using feed powders manufactured by processes other than the conventional oxalate process; and second, to highlight some pellet fabrication difficulties experienced with the direct denitration LWR recycle PuO/sub 2/ feed material, which did not produce acceptable pellets.more » The direct denitration LWR recycle PuO/sub 2/ was available as a by-product and was not specifically produced for use in fuel pellet fabrication. Nevertheless, its characteristics and pellet fabrication behavior serve to re-emphasize the importance of continued process development involving both powder suppliers and fuel fabricators to close the fuel cycle in the future.« less
  • Direct thermal denitration of nitrate solutions containing uranium, plutonium, and about 2 mol of ammonium nitrate per mol of heavy metals produced a mixed oxide powder which was well suited to the production of pellets. The nitric acid concentration of the solutions was maintained at greater than 1 M to prevent hydrolysis of the plutonium. The resulting UO{sub 3}-PuO{sub 2} powder had a bulk density of about 1.2 g/cm{sup 3} and required preslugging before pellet pressing. Pellets prepared at the Oak Ridge National Laboratory (ORNL) by pressing at 241 MPa (35,000 psi) or 310 MPa (45,000 psi) and sintering atmore » 1450{sup 0}C for 4 h had densities of 95% of theoretical, good external appearances, and good microstructures. The pellets were completely soluble in refluxing 7 M HNO{sub 3}. Pellets were also pressed from this powder at Battelle Pacific Northwest Laboratory (PNL) with similar results. A sinterable PuO{sub 2} product was obtained in comparable denitration tests with plutonium solutions, although the powder had poor flowability and produced pellets with scattered, relatively large porosities. The results, however, encourage further development of better plutonia powder by this process.« less
  • The fabrication technology for low density pellets was studied using three recycled MOX powders with different particle sizes (fine, medium-coarse and coarse). The coarse recycled powder has a larger effect on reducing the pellet density than the fine one.Many pores can be observed in the cross section image of the sintered pellet made with the coarse powder although pore-former was not added. It seems that the large number of relatively large interstices which exist between the coarse recycled powder particles and the rest of the raw powder particles are retained as stable pores in the sintered pellets. However, a highmore » addition rate for the coarse recycled powder in feed powder leads to large densification by re-sintering. The degree of densification by re-sintering is also a function of the addition rate of pore-former when the coarse recycled powder was mixed in the raw powder. As a result, it is concluded that the pellets with 25 wt% of the coarse recycled powder and 1.3-1.5 wt% of pore-former acquire reasonable density and densification by re-sintering. By using the coarse recycled powder, the addition rate of pore-former can be reduced to satisfy the density specification of low density pellets (83-87%TD) and higher yield of good density products can be achieved due to the reduction of density deviation. (authors)« less
  • No abstract prepared.