MELTING RISK ASSESSMENT IN PEC REACTOR FUEL DURING NORMAL AND OFF-NORMAL OPERATION
A reliable evaluation of fuel temperature is a key safety requirement in the design of the fuel subassembly of a nuclear reactor, especially in the case of LMFBR whose efficient operation demands high thermal performance fuels. The physico-chemical properties such as density, oxygen to metal ratio, thermal conductivity and diffusivity, specific heat, associated to fuel - cladding gap conductance, which are all known to be temperature and/or burn-up dependent, strongly affect the temperature profile within the fuel pellet. In order to achieve a safe operation of the reactor, the design criteria state that fuel melting be avoided whether in Normal Operation category (Level I) or Upset category (Level II) even though there is at the moment a tendency to admit a limited amount of molten fuel in the pin in case of an Upset event. Thus, even after a Level II accidental transient, the restart of the reactor has to be insured without making any correcting intervention on the core. Referring to the design categories mentioned above, a statistical analysis of the BOL and EOL temperature values in the fuel of the Experimental Fast Reactor PEC is carried out by means of the Response Surface Methodology coupled to a Monte Carlo Technique. The wide set of uncertainties on independent variables takes into account four different sources of uncertainty: physical, geometrical, modelling and operational. The scope of the present work is to show how the melting risk in the fuel of PEC reactor is really limited, provided that are excluded here those severe accidental events which go out of the boundaries referred above.
Bibliographic Reference: INTERNATIONAL CONFERENCE ON RELIABLE FUELS FOR LIQUID METAL REACTOR, TUCSON, ARIZONA (USA), SEPT. 7-11, 1986 WRITE TO CEC LUXEMBOURG, DG XIII/A2, POB 1907 MENTIONING PAPER E 32709 ORA
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Record Number: 1989125058000 / Last updated on: 1987-11-01
Available languages: en