Experiment Description and Hazards Evaluation for the Pacific Northwest Laboratory Mixed Oxide (UO₂-PuO₂) Capsules for Insertion in Subassembly X011

Technical Report · Thu Aug 01 00:00:00 EDT 1968

DOI:https://doi.org/10.2172/4491265· OSTI ID:4491265

Pember, L. A. ^[1]

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1. Battelle Pacific Northwest Labs., Richland, WA (United States)

Pacific Northwest Laboratories (PNL) has reached agreement with the AEC Office of Research and Development Technology on the experiment plan (PNL X-1 through 7) to take advantage of spaces made available by the recent removal of the five pins from the EBR-II Subassembly X011. Approval-in-principle has been requested from the Argonne National Laboratory Director's Office to irradiate five encapsulated mixed oxide pins in Subassembly X011 when it is reinserted into the EBR-II. These tests will provide the desired data during the additional exposure of approximately 2200 MWD planned for Subassembly X011. The proposed tests comprise five encapsulated pins which will operate at relatively low linear power generation rates to provide information on the following: (1) Kinetics of fuel-cladding gap closure; (2) Effect of initial gap size on the fuel radial temperature profile; (3) Fission gas release as a function of temperature; (4) Extent of fuel restructuring which will take place at these power levels. These pins will provide support information for the three planned 37 unencapsulated pin subassembly irradiations, for which PNL has received approval-in-principle from the LDO, and preliminary information on the performance of prototypical, mechanically blended mixed oxide FTR fuel. The data from the five test pins will strengthen the technical basis for the fuel-cladding gap specification for FFTF driver fuel pins. The group of five pins will nominally comprise three pins containing naturally enriched UO₂-25 wt% PuO₂ and two pins containing 45% enriched UO₂-25 % PuO₂. Fabricated fuel is available for the natural UO₂-PuO₂ pins and the pellets containing enriched uranium have been fabricated. For these tests, the smeared density of the fuel will be held constant while the fuel-cladding gap and pellet density are varied. A Row 3 position is planned for the reinsertion of XOll in EBR-II. A reactor power of 4S MW will produce a maximum linear heat generation rate of approximately 6 kW/ft in the NUO₂-PuO₂ pins, which is comparable with the minimum linear power generation rate of the FTR driver fuel pins. The 45 % enriched UO₂-PuO₂ pins will generate approximately 10.6 kW/ft (maximum) which is near the average linear pin power generation rate anticipated in the FTR. Most of the mixed oxide pin experiments conducted in EBR-II tests have operated with higher heat ratings. Therefore, these proposed tests will add to the few existing data on the performance of mixed oxide fuel at the minimum and average power ratings expected in the FTR. Threshold flux monitors will be incorporated into each capsule. The different monitor materials to be used will include iron, nickel, copper, scandium and titanium. Lengths of monitor wire will be sealed in the stainless-steel hypodermic tubing used for wire wrapping the fuel pins to provide spacing between the fuel pins and the inner wall of each capsule. Results from these monitors may help in resolving differences in flux values which are obtained from the fission monitors used by ANL and from the activation monitors used by many other experimentors .

• Research Organization: Battelle Pacific Northwest Labs., Richland, WA (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA), Nuclear Criticality Safety Program (NCSP); US Atomic Energy Commission (AEC)
• DOE Contract Number: AT(45-1)-1830
• NSA Number: NSA-22-050804
• OSTI ID: 4491265
• Report Number(s): BNWL-841
• Resource Relation: Other Information: UNCL. Orig. Receipt Date: 31-DEC-68
• Country of Publication: United States
• Language: English

Related Subjects

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
10 SYNTHETIC FUELS
ANALYSIS
DESIGN
FABRICATION
FUEL ELEMENTS
IRRADIATION
ISOTOPES
MIXING
NUMERICALS
PERFORMANCE
PLUTONIUM OXIDES
REACTORS
TESTING
URANIUM OXIDES
Nuclear Criticality Safety Program (NCSP)
Criticality
Irradiation
Plutonium Oxides
FTR
Threshold Flux
Monitors
EBR-II
FFTF
PNL
N38510* -Research & Test Reactors & Critical Assemblies- Kinetics & Dynamics