Manny Mathuthu, Ntokozo Khumalo, Malayita M Baloyi and Refilwe N Maretela North-West University (Mafikeng) Center for Applied Radiation Science and Technology (CARST) Mmabatho, 2735, South Africa Manny.Mathuthu@nwu.ac.za Application of ICP-MS and Isotopic Techniques in Resolving Nuclear Forensics Signatures in South African Mining and Processing

Overview Aim of the Research Objectives Background Methodology Present Results & Discussions Conclusions

Aim of ICP-MS & Isotopic Ratio Technique Apply the ICP-MS & Isotopic Ratio Technique to resolve nuclear forensic signatures in South African Uranium Thorium Mining and Processing. Objectives are to: Resolve the U-238, Th-232 nuclear forensics signatures for the mine using: Isotopic Ratio Technique ICP-MS Technique Gamma spectrometry Technique Develop a nuclear forensics Library for U & Th from the mine Use Library to trace origin of interdicted nuclear material Provide evidence for law enforcement and nuclear security

Background: Nuclear security Prevention, detection and response to theft associated with illegal possession or transfer of radioactive or nuclear material and their facilities (Kristo and Tumey, 2013). Fig 1: Prevention (LHS), Characterization (Middle) and Fingerprinting (RHS). (Davydov, Hutcheon et al. 2014)

Background Cont… Nuclear forensics Examination of nuclear and or radioactive material for supporting nuclear security. Nuclear forensic helps to characterizes nuclear material at each stage of the fuel cycle: the uranium ore body underground, the milling and processing of the ore, enrichment of uranium in 235U, nuclear reactor operation the spent fuel (nuclear waste) stage re-processing of spent fuel. In this work we focus on the first two stages.

MATERIALS AND METHODS Signatures Includes- physical characterization, elemental, isotopic and chemical composition of the nuclear material Techniques Here we characterize mining and processing of U & Th using ICP-MS REE (Lanthanides), minor and trace elements. Run samples in the ICP-MS under the Isotopic Ratio Method We compare to the gamma spectrometry technique

Mine Tailing Fig 2: The Fuel Cycle (Adapted from NRC)

Study Area Mine Tailings Mine Tailing Fig 3: Study Area

Active Tailing Fig 4: Sampling the Tailing slurry

Disused Tailing Fig 5: Sampling at 50 year intervals ng at 50 year intervals

Fig 6: Instrument: NexION 300Q ICP-MS (Perkin Elmer) ICP-MS Equipment Used (A) ICP-MS for major and trace elements Fig 6: Instrument: NexION 300Q ICP-MS (Perkin Elmer)

HPGe Detector Equipment Used Fig 7: High Purity Germanium for Gamma spectrometry

ICP-MS Results for mining and Processing

Table 4:

Table:5 Fingerprinting the mines Tailing Dam1 Tailing Dam 2 Comment B, Th, U, Y, V, Ni and Ti Strong suggestion that Phosphate was used during Processing Phosphorite deposit, Apatite & fluorapatite minerals. Uranium is recovered from phosphoric acid Ba,, Sr, Cr, Mo, Pb, Cu, Zn, Cd, Li, Fe and As Ca, K, Mg, Mn and Fe Absence of Se, Re, Lu suggests that Uranium is NOT in a Coal-Hosted Ore Studying these 22 elements more closely, the elements which distinguished the U ore Source Dams from each particular mine were determined. See Fig 5. Dam 2 has higher concentrations of Ca, K, Mg, Mn and Fe, which indicates leach processing of the U ore. Lime pptn of impurities, Magnesia pptn of U

REE Patterns for Tailing Shaft water REE Conc/ Chondrites Means Fig. 8. Chondrite normalised REE patterns for Mine samples. REEs in order of A. (Chondrite data : Anders and Grevesse, 1989).

REE Patterns for Tailing 3. REE Conc/ Chondrites Means Fig. 9. Chondrite normalised REE patterns for Mine samples. REEs in order of A. (Chondrite data : Anders and Grevesse, 1989).

Table 6: Heavy metals concentration per Tailing:

Discussions on ICP-MS Results The concentration of uranium is below 10 ppm for both tailing dam 1 and 2- absence of blackshale deposit but higher for Tailing dam 3-5. Rb, Th, Cs, Pb, Ti and S represent a Quartz-pebble conglomerate deposit. High concentration values of As and Ni and Mo are associated with uncorformity-type ore deposit. V, Ti and Fe represent a type of leach solution when in situ process Al, Mg, Ca, Fe, K, Mn are predominant in this mine. As a result, they are a distinctive characteristic of this mine.

During the processing of the ore, fingerprint is lost During the processing of the ore, fingerprint is lost. However, Rare earth elements (REE) or Lanthanides, are used to determine the original deposit Fig 8 & 9 show that La, Ce, (Pr) & Nd have high signatures for U (and low for Th) A Chondrite normalized plot of the REE concentration versus the REE, arranged in order of atomic mass numbers, gives the characteristic Lanthanides patterns for the particular mine. The (LREE), light rare earth elements (Sc, La, Ce, Pr, Nd, Pm, Sm, Eu, and Gd; - cerium group), are dominant in this gold/uranium ore body. Ca, Fe, W and Pb were impurities found in urinates and this is normally the characteristic of vein type hydrothermal deposit. The increase of uranium in the T5W samples suggests: Time scale for technology development over years Poor processing methods Poor value of uranium at that time

ICP-MS Isotopic Ratios Fig10(a): Lead isotope ratio for water samples from the gold mine in SA.

(B) Low Th concentration Fig 10(b): Lead isotope ratio for water samples from the gold mine in SA 207Pb/206Pb 208Pb/206Pb

Fig. 5 207Pb/206Pb versus 208Pb/206Pb for tailing samples.

Fig. 12 A plot 207Pb/204Pb versus 206Pb/204Pb for mine (fissure) water samples.

Conclusions Rare earth elements (REE) are good signatures of the original deposit {La, Ce, (Pr) & Nd } and dominant group In Fig 12 show Lead (Pb) isotope ratios for SA gold mine range from 12 %wt to 18.5%wt. This is distinctively different from UK, Germany, Poland, Italy, and Spain [Balcaen et al., 2010]. See also Fig 11. First endmember point shows lack of Th232 in sample. Ca, Fe, W and Pb were impurities found in urinates and this is normally the characteristic of vein type hydrothermal deposit. Fingerprints suggests Phosphorite deposit in Apatite & fluorapatite minerals. Uranium is recovered from phosphoric acid Lime used for pptn of impurities & Magnesia used for pptn of U

Acknowledgements Authors would like to acknowledge the International Atomic Energy Authority for sponsoring this Project under CRP J2003. We also acknowledge the assistance given by Dr Lebo Motsei and Chief Technician Ms Mpho Tsheole on the operation of the ICP-MS for Isotopic Ratio data analysis.

Thank you!!!