It seems that the recent developments in BWR fuels (increased enrichment, added uranium mass at the bottom, part-length fuel rods especially in the corners) have changed the control rod reactivity values in such a way that the potential reactivity insertion caused by the postulated rod drop accident is potentially quite high at certain points during nuclear heating. More specifically, at the stage when CR:s adjacent tho those already withdrawn are being taken out of the core. This may result into quite large reactivity insertions and it is not trivial that the RIA limits of fuel are fulfilled at every point (up until the spectral effect finally cuts the CR reactivity values), if the situation has not been considered thoroughly at some stage during the gradual fuel development. I was wondering if someone else has come up with this issue, and if there are some findings that might be of interest? Especially the behaviour of Doppler and other feedback mechanisms during the heating phase would be interesting. I am planning to do some generic calculations on my own, but it would be nice to know if someone has already done something in this direction.