I have a couple of ionising smoke detectors (i.e. containing a small amount of radioactive material) that have reached their 10 year end of life. I have checked online for information about disposing of/recycling these but I can't find anything useful/authoritative. Anybody got any ideas? I'm buying replacement dual mode smoke and carbon monoxide detectors online so returning them under WEEE isn't an easy option as I don't really want to have to post them back to the online vendor...