SEDL / STP / STP681-EB / STP36692S

Zirconium Cladding Deformation in a Steam Environment with Transient Heating

Chapman, RH
Manager, project leader, and project engineer, Multirod Burst Test Program, Engineering Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee

Crowley, JL
Manager, project leader, and project engineer, Multirod Burst Test Program, Engineering Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee

Longest, AW
Manager, project leader, and project engineer, Multirod Burst Test Program, Engineering Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee

Hofmann, G
Guest scientist, Oak Ridge National LaboratoryKarlsruhe Nuclear Research Center, Karlsruhe,

Pages: 16    Published: Jan 1979

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Abstract

Zircaloy-4 cladding is being tested under loss-of-coolant accident (LOCA) conditions to determine its deformation behavior and to provide data for verification of analytical models. Data obtained thus far from 34 single-rod tests imply less ballooning, and consequently less flow restriction, than would be predicted from earlier data.

The instrumented simulators, consisting of unirradiated Zircaloy-4 cladding with an internal heater to simulate fuel pellet heating, are tested to failure in superheated steam over a wide range of internal pressures at a temperature increase rate of about 28°C/s. Cladding surface temperature and internal pressure data are recorded during the transient and deformation measurements are obtained posttest.

An analytical expression is given for the burst temperature as a function of burst pressure. The experimental results show excellent correlation between cladding deformation and surface temperature distribution. Deformation is extremely sensitive to small temperature variations.