Interim Report -- TREAT Test R12
The R-series TREAT test R12 was performed in support of the LMFBR safety program and, in particular, the licensing needs of the FFTF FSAR. The experiment addressed the key safety issue of final coolability as a result of an unprotected 50¢/sec transient overpower (TOP) accident. The objective of the R12 test was, therefore, to examine the extent of post-failure test section throughflow. The initial conditions specified for R12 duplicated those attained during TREAT test R9. A flowmeter feedback to the reactor control system was employed to initiate scram. Test R12 employed seven, full length, fresh fuel-elements with prototypic thermal/hydraulic properties. Previous TOP TREAT tests with unirradiated and irradiated fuel demonstrated sweepout, but each resulted in a blocked test section. It was believed that the test section blockages were formed as a result of overpowering beyond the initial failure, especially for the longer period transients. For this reason, it was desirable to have an early scram providing an accident shutdown scenario as close to the predicted FTR (based on negative reactivity of molten fuel being carried away from the core region) as can he achieved in TREAT for this type of experiment. The R12 test had a flow sensor feedback to the reactor control system which provided a scram upon a 40% reduction of the inlet flow rate. A background sununary discussion of the R12 test results is repeated here. It is concentrated in a time span bracketing the significant events, 2.0 to 4.0 sec after the TOP initiation. Approximately 2.27 seconds into the overpower segment of the transient, the initial fuel pin failure occurred. It is believed that the failure was not preceded by coolant boiling. The initial pin failure occurred prematurely to the prediction based upon R9 test data. Flow and pressure perturbations occurred which were probably caused by noncondensible gas release and fuel/coolant interactions. Concurrent with the initial pin failure was a sharp coolant temperature rise at the test section outlet. Approximately 40 msec after the initial fuel pin failure the hexagonal coolant flow tube breached probably due to overpressurization.
- Research Organization:
- Idaho National Lab. (INL), Idaho Falls, ID (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- DE-AC07-05ID14517
- OSTI ID:
- 1130759
- Report Number(s):
- ANL/RAS 78-19
- Country of Publication:
- United States
- Language:
- English
Similar Records
Final Report for TREAT Transient Overpower Tests R9 and R12 -- Part 2
Effect of power skew on the FTR TOP