Radioactive Cup Source: Strontium - 90kBq. The active material is enclosed in metal foil fixed in a cylindrical mount provided with a stem of 4mm diameter. The foil is further protected from accidental damage by a wire gauze cap over the open 'window' of the mount. The nature and strength of each source is clearly engraved on its mount and it is also colour coded for identification. Each is supplied in a small lead 'castle' in a suitably labelled MDF storage box (100mm x 75mm x 65mm). A data sheet is enclosed with each. 5µCi (185 kBq) of Strontium90 in equilibrium with its daughter nuclide Yttrium90, incorporated in a silver disc allowing the major proportion of the Beta radiation to escape. Emissions: ß. Half-life: 28 years (strontium), 64 hours (yttrium). Colour code: Yellow. Requirements for purchase:. Welsh state schools need a permit from the Welsh Assembly. Scottish schools require approval from the Scottish Government Education Directorate. Schools in Northern Ireland require a DENI permit. State schools in England do not require a Letter of Authorisation. Independent schools in England, Wales & Northern Ireland do not require a Letter of Authorisation. Unavailable for export outside of the UK.