Characterisation of the Thule Pu-U particles. Per Roos DTU Nutech

Transcription

1 Characterisation of the Thule Pu-U particles Per Roos DTU Nutech

2 Center for Nuclear Technologies Technical University of Denmark (Risø Campus) [Formerly known as Risø National Laboratory] Radiation physics Radiation dosimetry Radiopharmaceuticals Radioecology/environmental radioactivity Tracer studies Radiochemistry Nuclear instruments Industrial applications of nuclear methods Staff of 80 in 3 research programmes and a mechanical workshop o Radiation Physics o Biomedical Tracers - Hevesy Laboratory o Radioecology and Tracer Studies

3 Investigations of man-made radioactivity in the Danish environment from DTU Nutech, Technical University of Denmark

4 CONCENTRATION (µbq/m 3 ) Radioactivity in Air at Risø 1.E+04 1.E+03 Atmospheric nuclear weapons tests Chernobyl, 1986 Fukushima, E+02 1.E+01 1.E+00 Sr-90 Cs E-01 1.E YEAR 4 DTU Nutech, Technical University of Denmark

5 Radionuclides from Fukushima in air in Denmark

6 Precipitation Precipitation is collected at Risø and 10 other locations in Denmark and analysed for content of Sr-90 and Cs DTU Nutech, Technical University of Denmark

7 Sea water and plants 10 E 11 E 12 E 13 E Kattegat-413 Kattegat SW Hesselø Kullen Øresund, N, B 56 N Øresund, N, A Asnæs rev Halskov rev Øresund, S Møen 55 N Langeland bælt Femern bælt Gedser odde DTU Nutech, Technical University of Denmark

8 Koncentration (Bq/kg frisk vægt) Caesium-137 in fish/cod Færøerne Grønland Nordsøen Kattegat Østersøen År DTU Nutech, Technical University of Denmark

9 Radioactive contamination in Denmark Poster in building 204 shows concentrations of strontium-90 and caesium-137 in air, precipitation, milk and grass at Risø and in Denmark since the 1950 s. 9 DTU Nutech, Technical University of Denmark

10 Ore heaps at Risø with crushing house in background DTU Nutech, Technical University of Denmark

11 Decommissioning work

12 Analytical capacity in-house: C:a gamma (Ge) detectors (including one anti-compton well detector). One low-energy HPGe for characteristic x-ray analysis. 30 Gas-flow anticoincidence shielded GM-counters. Quantulus PerkinElmer TriCarb LSC. 32 solid state (PIPS) alpha detectors. Q-ICP-MS & ICP-OES Neighbours toys: SEM/EDX (10+ systems) TEM. FIB. TOF-SIMS (IonTOF 4). Micro-RAMAN Etc

13 Analytical Methods Radionuclides Chemical Analyses LSC Total Beta Counting Gamma Spec Alpha Spec ICPMS AMS 3 H X X 90 Sr X X X 99 Tc X X X 129 I X X 137 Cs X X 210 Pb X 210 Po X X 226 Ra X X X 230 Th X X 232 Th X X X 234 U X X X 238 U X X X 237 Np X X X 239 Pu X X 240 Pu X X Pu X X X 241 Am X X X Other gamma emitters X

14 Analytical Methods in decommissioning work Radionuclides Chemical Analyses LSC 55 Fe X X 63 Ni X X 14 C X X 41 Ca X X 36 Cl X X Total Beta Counting Gamma Spec Alpha Spec ICPMS AMS

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16 Operation Crested Ice Plane wreckage and weapons components sent to US. Contaminated ice/snow stored temporarily in Gallon tanks at Tank Farm before sending to US. Radioecological follow-up

17 Previous investigations Marine expeditions: 1968, 1970, 1974, 1979, 1984, 1991, 1997, 2003 Sediment, water, animals and sea plants. Terrestrial sampling (Including lakes): 1968 (Crested Ice). Pu on snow at Narssarssuk, Saunders Island and Wolstenholme identified (WC Hanson). Investigations around Kap Atholl. Weapons Pu identified (Eriksson & Holm). Soil & lake sediments north & east of TAB. No sign of weapons Pu (Thule-2003 exp). Soil sampling at Narssarssuk (main focus on marine programme) 2006 Sampling at Nassarssuk and south of Green Valley Sampling at Nassarssuk, Thule Air Base, Moriusaq village, Saunders Island.

18 Mapping and screening Moriusaq Saunders Island Thule Air Base Wolstenholme Island Narssarssuk Grønnedal

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24 Soil sampling

25 Summary of soil deposition at investigated sites

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27 Particles characterization methodology Isolation technique. Radioisotope content via gamma and x-ray spectrometry (large particles) Radioisotope content via ICP-MS (small particles) Visual appearance via optical microscopy. Morphology & element composition via SEM/EDX. Mechanical and chemical stability in the environment and in the body. Additional techniques (TOF-SIMS, XPS etc)

28 Region with strong lines from Pu-239, 240, 241 & U kev Pu kev U kev U kev U kev Pu kev Pu-241 (U-237) kev : % [Pu-239] kev : % [Pu-240] 208 kev : % [Pu-241 (U-237)]

29 375 & 414 kev Pu-239 lines. 375 kev 414 kev 375 kev % 414 kev %

30 Gamma lines used for elemental/isotopic composition of particles 241Am 238Pu 239Pu 240Pu 235U [kev] [kev] [kev] [kev] [kev] % % % % % % % % % % % % % % % % % % % % % % %

31 1% HPGe & 5kBq Pu-239 Thule particle (230 ksec) Canberra GL0055P. 50mm 2 active area, 5mm thick. FWHM 122keV: 0.47 kev FWHM 5.9 kev: 0.13 kev

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33 1% HPGe & 5kBq Pu-239 Thule particle (230 ksec) 51.6 kev Pu kev Pu kev Pu kev Pu-240 Ge Kα escape 59.4 kev Am-241

34 1% HPGe & 5kBq Pu-239 Thule particle (230 ksec) Lα Lβ Lγ Lζ

35 Complexity of the Lx-peak groups (here Lβ in a Thule particle)

36 Thule particle on Si(Li)-detector

37 Risø ICP-MS instruments Thermo X-series II Quadrupole ICP-MS Plasma Trace 2 Sector field ICP-MS

38 UH/U Elemental & isotopic Pu-U composition of Thule particles Important point: UH/U may depend on cone & plasma conditions. The UH/U value closest in time to the sample of interest may be most accurate. UH/U decrease with time in the set above. This means UH/U=6.14E UH/U ratio vs time 12/ Atom% Atom% Atom% REFERENCE VALUES U-238 U-235 U-234 n(235)/n(238) n(234)/n(235) NBL U112-A 99,2746 0, , , , Measurement No

39 Normalized intensity (%) Normalized intensity (%) TOF-SIMS Sample 1A 0-50 s sputtering (10 points summed) Mass (amu) Sample 1C s sputtering (10 points summed) Mass (amu)

40 Int.( 235 U) / Int.( 238 U) Homogeneous 235U/238U ratios in particles or not? Sample K Sample 1 235/ Position 1 Position 2 Position 3 235/ / /238 A B C Ave StDev Ave 4.70 StDev Position 1 Position 2 Position 3 3

41 SEM/EDX

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43 Thank you for your attention!