Alkali Metal Disposal - Ispra

The Joint Research Centre in Italy was established as a nuclear research facility in the late 1950's. Research on the site has now been discontinued and the redundant facilities have entered the decommissioning phase. In late 2007 NDSL was part of a team along with UKAEA Ltd who were successful in winning the contract to dispose of alkali metal which had been used as part of the JRC research programmes. The metal consisted of approximately 200kg of sodium and 400kg of sodium / potassium alloy, known as NaK.

The material lacked any substantial documentation and was contained in drums that appeared to be heavily corroded. As part of the JRC requirement, the material had to be characterised in order that NDSL could design a safe repackaging process and then plan the ultimate disposal. A decision was taken that the NaK must be frozen before being sampled and this was achieved by lowering the temperature inside the building to -20°C at a time when the outside temperature was +35°C. The characterisation process confirmed that the sodium and NaK was non radiological in nature and also provided information regarding the sodium/potassium mixture in the drums.

Sodium reacts violently with water and will cause caustic and thermal burns if it comes into contact with skin. NaK is even more volatile due to the potassium content.

Having been awarded the contract by the EU Commission, the NDSL Managing Director was appointed as the UKAEA Project Manager for the work, and NDSL staff undertook all of the practical work. This included design of the sampling process, preparation of a Safety Case, sampling and subsequent analysis of each of the 13 containers, repacking of the material to allow for its transport to the UK, transportation, further repackaging in small quantities suitable for incineration, and subsequent incineration.

The work was completed some nine months ahead of the original schedule in June 2009, on budget and was carried out to the total satisfaction of the client. The work required meticulous planning, deep technical understanding of the alkali metal, the preparation of a complicated safety case, clear management of its decommissioning operatives to undertake the hazardous hands-on work of sampling, repacking and further repackaging, and an understanding of potential waste treatment methodologies that could be used.