Rapid actinide measurements in environmental samples Dr Phil Warwick Geosciences Advisory Unit Southampton Oceanography Centre

Analytical requirement Sequential Pu and U separation from soils Survey of the former Greenham Common airbase Survey of the environment around a UK nuclear weapons establishment samples per year

Final measurement techniques Plutonium - Alpha spectrometric measurement of Pu and 238 Pu Uranium - 238/235 atomic ratio and U concentration by TIMS

Conventional approach and associated problems Sample dissolution Aqua regia leach or fluoride / pyrosulphate fusion Problems with incomplete dissolution or application of a potentially hazardous procedure Pu and U separation Preconcentration / Anion exchange chromatography Long ion exchange columns and incomplete U / Fe separation

Sample fusion Complete sample dissolution can be achieved rapidly and effectively using a lithium borate fusion technique The technique is routinely used in geological analysis for rock dissolution prior to ICP-AES measurement as well as in XRF analysis

Isolation of Pu and U Pu is readily isolated and purified using conventional anion exchange chromatography. U isolated using UTEVA resin Good separation of U from Fe. U K d on UTEVA is > 200

Uptake of U on UTEVA

Analytical technique - fusion Thoroughly mix 5g of sample (ground) with 7g of lithium borate flux. Spike with 242 Pu and 236 U. Fuse at 1200°C Cast melt into 50ml of water. Add 50ml HNO 3 and 1ml 0.2M PEG-2000 Dissolve glass at 60°C overnight and filter to produce a clear solution

Pu (Th) / U separation Load 8M HNO 3 Wash 13M HNO 3 Wash 2 (AX only)c. HCl Elution 1 (AX only)HCl / H 2 O 2 Elution 2 (UTEVA only)0.02M HCl

Lithium borate fusion versus aqua regia digest for Pu Data for NIST 4353

Lithium borate fusion versus aqua regia digest for U Data for NIST 4353

Advantages Rapid and efficient fusion procedure Fast analysis - typically 2 days for 8 samples Clean alpha spectrum - Good Pu recoveries (routinely 80-90%) U recoveries around % (not directly monitored) U sources suitable for TIMS or alpha spectrometric measurement Reduction in consumable costs as smaller columns are used (also UTEVA can be recycled)

Further developments Isolation of U and Th from sediments using UTEVA resin Sequential separation of Pu and Am from sediments and biota using TRU resin Both techniques employ a lithium borate fusion followed by extraction chromatographic isolation of the analytes

Acknowledgements Co-workers I Croudace, R Taylor, J-S Oh, J Milton, S Dee Funding bodies West Berkshire Council AWE Aldermaston