NUCLEAR REACTOR CORE PROBLEMS
DOE-HDBK-1017/2-93
Plant Materials
NUCLEAR REACTOR CORE PROBLEMS
Material problems in a nuclear reactor plant can be grouped into at least two
categories, one concerning the nuclear reactor core and one that will apply to all
plant materials. This chapter discusses specific material problems associated with
the reactor that include pellet-cladding interaction, fuel densification, fuel-
cladding embrittlement, and effects on fuel due to inclusion and core burnup.
EO 1.12
STATE nuclear reactor core problems and causes associated with
the following:
a.
Pellet-cladding interaction
b.
Fuel densification
c.
Fuel cladding embrittlement
d.
Fuel burnup and fission product swelling
EO 1.13
STATE measures taken to counteract or minimize the effects of the
following:
a.
Pellet-cladding interaction
b.
Fuel densification
c.
Fuel cladding embrittlement
d.
Fission product swelling of fuel elements
Fuel Pellet-Cladding Interaction
Fuel pellet-cladding interaction (PCI) may lead to cladding failure and subsequent release of
fission products into the reactor coolant. PCI appears to be a complex phenomenon that tends
to occur under power ramping conditions. Expansion of the fuel pellets due to high internal
temperatures, cracking due to thermal stresses, and irradiation-induced swelling may lead to
contact of the fuel with the cladding. Thermal, chemical, and mechanical interactions may then
occur that, if not appropriately accounted for in the design, may lead to cladding failure. Design
features to counteract PCI include the following.
a.
an increase in the cladding thickness
b. an increase in the cladding-pellet gap, with pressurization to prevent cladding collapse
c.
the introduction of a layer of graphite or other lubricant between the fuel and the cladding
MS-05
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