RRFM 2009 Transactions - European Nuclear Society

A
3.1. Place a boron insert in a high density U 3 Si 2 fuel plate
AREVA-CERCA already had experience as regards insertion of a boron insert but only with
an aluminide fuel core. The specificities of JHR’s developments were:
- The fabrication of a boron insert with a high quantity of boron,
- The fabrication of the fuel plate with mastering the occurrence of blistering and low
cladding thickness.
So as to succeed, several types of boron inserts were manufactured and placed in the plates
in order to test different mechanical behaviours. The parameters tested in the boron inserts
were the following:
- The boron core,
- The cladding,
- The fabrication process.
B
C
Aluminium
cladding
Boron core
D
E i
E e
Fig 4: Sketch of a boron insert
After a development period of more than one year, organised in several progressive testing
phases, a design of boron insert as well as a design of fuel plate were agreed. They enabled
to reach a high level of quality, as show following inspections results:
- No blister was observed by visual inspection, nor by UT,
- The cladding thickness reached was similar to other standard fabrications – see figures 5
and 6 for illustrations in the uranium and in the boron area,
- Homogeneous uranium distribution surface was obtained, even in the dog-bone area –
see figure 7.
Fig 5: Metallographic inspection: dog bone area
Fig 6: Metallographic inspection: boron insert area
Fig 7: Surfacic uranium distribution
These excellent results enabled to obtain the acceptance of the CEA on the designs retained
and to validate the specification covering the fabrication of the plates.
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