[en] The report describes the behaviour of modern LMFBR'S during accidents with loss of electrical power without scram. This situation has earlier been considered to result in coolant boiling and core-melting. Recent experiments in prototype-reactors (PFR and Phenix) supported by theory show that inherent reactivity coefficients may prevent coolant boiling even in the very improbable case of power failure without scram. It is possible to further improve the behaviour by a simple modification of the control rods. If this can be proved to be true it will result in an improvement of the safety features of the LMFBR. (Author)