Thorium nitrate (CAS 13823-29-5): storage and disposal

Two properties decide where it goes: it is radioactive, and it is an oxidiser that may intensify a fire. So the bottle stays in place, labelled, with its record of holding, in a separate space clear of flammable, organic and reducing materials. Check that nothing like wooden shelving, cardboard or solvent bottles sits beside it, because those are what old cupboards tend to be full of, and clear those neighbours instead of shifting the bottle. It is also toxic to aquatic life with long lasting effects, so nothing should reach water. Leave it locked away from general access. Do not repackage it, however tired the container looks, and let your Radiation Protection Adviser decide the next step.

Old glass with a brown or peeling label, a rusted metal cap or a perished stopper is what you are likely to see. The crystals readily take up moisture, and a thorium nitrate bottle that has sat in a damp store may show clumped, wet looking or partly liquefied contents. Staining on the shelf beneath, or corrosion on nearby metal fittings, suggests the bottle has been leaking or the cap has failed. There is no change in colour that reliably marks age, so it gives few other visible signs. Its radioactive status does not fade over any working lifetime. Paper or card that has been in contact with spilled salt deserves caution too, because it has been in contact with an oxidiser. Report it, without opening anything.

This does not go through our standard collection route. It is arranged by manual enquiry, and never goes down the drain or into general waste.

Do not pour it away, dissolve it for disposal or put it out with general waste. Do not move it to a collection point either. It is radioactive material under the Environmental Permitting regime in England and Wales, with equivalent rules in Scotland and Northern Ireland, and that puts it outside a chemical collection. It is not quoted online. Schools and colleges should go to their Radiation Protection Adviser, while a university may use its Radioactive Waste Adviser too. A manual enquiry can help you describe what you have, and a store assessment is recommended. Give the amount, the label wording and the state of the bottle, then leave it labelled and in place until advice comes.

Usually held as: legacy stock.

Tell us the container size and how many you hold. An estimate is enough to start with, and some items cannot be priced until someone has looked at them.