[en] A number of in-pile and out-of-pile experiments as well as analytical studies have addressed LMFBR fuel disruption: several disruption models have been discussed in the literature. Hypotheses have included, among others, that the fuel could: (1) breakup rapidly in a ''dust-cloud''; (2) swell in the solid or liquid state to a ''froth'' with fission gas forming the discontinuous phase; or (3) melt and slump with release of fission gas. Sandia Fuel Disruption Experiments are described which have been designed to study this phenomenology and to clarify this issue

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[en] An inexpensive, long focal-length optical system was developed to view microscopic targets from large distances. Measured and theoretical limits of resolution agree within 2 percent at 560 nm. Spheres of diameter greater than or equal to 50 μm at 50 cm distance are clearly resolved. (U.S.)

[en] This study (1) evaluates, on a comparative basis, the national and international regulatory and insurance standards that serve as guidance for fire protection within the nuclear power industry; (2) analyzes the recommendations contained in the major reports on the Browns Ferry Fire; (3) proposes quantitative safety goals and evaluation methods for Nuclear Power Plant Fire Protection Systems (NPPFPS); (4) identifies potential improvements that may be incorporated into NPPFPS; and (5) recommends a plan of action for continuation of the fire protections systems study

[en] Under prompt burst conditions the work potential of expanding fuel vapor is a sensitive function of the ability of fission product gases to cause fuel dispersal milliseconds before dispersal would occur from fuel vapor pressure alone. This relation is of potentially significant importance and merits investigation. A fuel disruption experiment at Sandia Laboratories exhibited rapid disruption probably below but near the fuel melt temperature. The fuel was being heated at 130K/msec when vigorous dispersal occurred in the hottest regions near the fuel melting point. Fuel vapor could not have been responsible. Dispersal is attributed to rapid release of fission product gases under the prompt burst conditions. Further tests are planned to explore this important phenomenon

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[en] In a loss-of-flow (LOF) accident in an LMFBR, the mode and timescale of disruption of fuel can establish the probability of a subsequent energetic excursion. To investigate these phenomena, in-pile disruption of internal-fission-heated fuel pellets, both fresh UO₂ and preirradiated mixed oxide, was recorded by high speed cinematography. Neither fuel frothing nor dust-cloud breakup occurred under the simulated LOF conditions. Instead massive and very rapid fuel swelling, not predicted by current transient fuel-swelling and gas-release models, occurred. This may be the initial and dominant mode of fuel disruption in a LOF. A new transient fuel-swelling model, FISGAS, has been developed at Sandia

[en] A fuel disruption experiment at Sandia Laboratories exhibited rapid disruption probably below but near the fuel melt temperature. The fuel was being heated at 130K/msec when vigorous dispersal occurred in the hottest regions near the fuel melting point. Fuel vapor could not have been responsible. Dispersal is attributed to rapid release of fission product gases under the prompt burst conditions. Further tests are planned to explore this important phenomenon. 13 refs

No abstract available