High-temperature reactor fuel fission product release and distribution at 1600 to 1800 degrees C
- Forschungszentrum Juelich, Postfach 1913, W-5170 Juelich (DE)
The essential feature of small, modular high-temperature reactors (HTRs) is the inherent limitation in maximum accident temperature to below 1600{degrees} C combined with the ability of coated particle fuel to retain all safety-relevant fission products under these conditions. To demonstrate this ability, spherical fuel elements with modern TRISO particles are irradiated and subjected to heating tests. Even after extended heating times at 1600{degrees} C, fission product release does not exceed the already low values projected for normal operating conditions. In this paper details of fission product distribution within spherical fuel elements heated at constant temperatures of 1600, 1700, and 1800{degrees} C are presented. The measurements confirm the silicon carbide (SiC) coating layer as the most important fission product barrier up to 1800{degrees} C. If the SiC fails (or is defective), the following transport properties at 1600 to 1800{degrees} C can be observed; cesium shows the fastest release from the UO{sub 2} kernel but is highly sorbed in the buffer layer of the particle and in the matrix graphite of the sphere; strontium is retained strongly both in the UO{sub 2} kernels and in matrix graphite, but can penetrate SiC in some cases where cesium is still completely retained; only if all coating layers are breached can iodine and noble gases be released. For the first 100 h at 1600{degrees} C (enveloping all possible accident scenarios of small HTRs), these fission products are almost completely retained in the coated particles.
- OSTI ID:
- 5477628
- Journal Information:
- Nuclear Technology; (United States), Journal Name: Nuclear Technology; (United States) Vol. 96:3; ISSN NUTYB; ISSN 0029-5450
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
220200 -- Nuclear Reactor Technology-- Components & Accessories
220900* -- Nuclear Reactor Technology-- Reactor Safety
ACCIDENTS
ACTINIDE COMPOUNDS
ALKALI METALS
CARBIDES
CARBON COMPOUNDS
CESIUM
CHALCOGENIDES
COATINGS
DISTRIBUTION
ELEMENTS
FISSION PRODUCT RELEASE
GAS COOLED REACTORS
GRAPHITE MODERATED REACTORS
HTGR TYPE REACTORS
METALS
OXIDES
OXYGEN COMPOUNDS
REACTOR ACCIDENTS
REACTORS
SILICON CARBIDES
SILICON COMPOUNDS
TEMPERATURE RANGE
TEMPERATURE RANGE 1000-4000 K
URANIUM COMPOUNDS
URANIUM OXIDES