Nuclear Fuels

1. Nuclear Fuels 27th September 2011 AnnikaWössner and Richard Maceiczyk

2. Content • General • Analytic strategy • Analytical techniques • Analytical solutions • Sectoral Plan for deposits Source:

3. Types of reactors in CH • 4 nuclear power plants • Beznau 1 and 2: Pressurizedwaterreactor • Gösgen: Pressurizedwaterreactor • Leibstadt: BWR/6,Boilingwaterreactor • Mühleberg: Boiling water reactor • 3 research plants and one disposal plant Source: www.ensi.ch

4. Waste and final deposit 75 t per year of used fuel rod from nuclear plants in CH Two temporary stores in CH Source: nagra.ch

5. Final deposit • Low-level and high-level waste • Low: 97,3 volume-% of waste and 1,6% of activity (Nagra 2010)  For Ch two deposits for different levels • Process of implementation of final deposits • Selection process for final deposits • Final deposit: protection dose < 0,1 mS/year Source: ensi.ch

6. Half-lives Source:

7. Radioactivity 1. Becquerel • Activity: 1 Bq = 1 s-1 • one decay per sec = 1 Bq • 600 Bq/kg in food (Germany) • 54 000 Bq/kg (I-131) in spinach (Fukushima) 2. Gray • 1 Gy = 1 J/kg • absorbed radiation dose of ionizing radiation Source: www.kernenergie.de

8. 3. Sievert [Sv] Radiation dose that considers physical and biological aspects 1 Gy = 1 Sv = 1 J/kg • 7000mSv: lethal dose for single whole-body radiation • 400mSv/h 15. March 2011 – near block 3 (Fukushima) • 20mSv/year: threshold to occupationally exposed persons • 1mS/year threshold for population in CH • 0,3mSv /year dose emitted by cosmic radiation • 0,1mSv return flight Frankfurt – New York Source: kernernergie.de

9. Source:

10. Geiger Counter • measurement of α-, β- and γ-radiation • cheap and robust • can only measure presence and intensity of radiation

11. Geiger Counter Source: Department of Physics and Astronomy Youngstown State University

12. γ-Spectroscopy • spectroscopic examination of γ-rays emitted by sample • two types of detectors: scintillation (eg. NaI) and semiconductor (eg. Ge) • only radioactive isotopes can be measured • radioactivity of some isotopes to low (eg. 242Pu) • quantitative measurement possible

13. γ-Spectroscopy natural Uranium Source: Wikipedia

14. Thermal Ionisation MS • sample is placed on filament and heated up to 2500°C • probability of ionization is function of ionization energy, quantitative measurement difficult • not all elements are ionized

15. Secondary Ion MS Source: serc.carlton.edu

16. Secondary Ion MS • both atomic and molecular ions are produced • very little sample preparation needed

17. LA-ICP-MS • atomization of the sample by laser ablation • ionization by inductively coupled plasma • ionization rate very high • ions have to be transferred from ambient pressure into vacuum • mass bias (different response for ions of different mass)

18. Inductively Coupled Plasma Source: elchem.kaist.ac.kr Source: wikipedia

19. X-Ray Spectroscopy • XRF: x-ray fluorescence • XRD: x-ray diffraction • XAS: x-ray absorption

20. X-Ray Spectroscopy Source: F. Jalilehvand, U Calgary

21. XRF

22. XAS • XANES: valence and density of states, qualitative structural info • EXAFS: info about local atomic structure Source: B. Ravel, U Washington

23. Possible Solution to the Analytic Problem

24. The Problem Determine the composition of irradiated nuclear fuel qualitatively and quantitatively. Select one technique suitable to determine the isotopic composition.

25. Unsuitable Techniques • γ-Spectroscopy: only radioactive elements can be measured • TIMS: different probabilities of ionization makes quantitative measurement difficult • SIMS: isobaric interference by molecular ions • x-ray: synchrotron radiation needed, optics have to be shielded from radiation

26. LA-ICP-MS • gives spatial resolution • complex electronics safe from radiation • very little sample preparation needed • gaseous inclusions in rod can be measured • isobaric interferences • quantitative measurement only with know internal standard

27. LA-ICP-MS • detection limits: depend on laser power and elements, typically ppb to low ppm range • accuracy and precision: 1-10% for most elements Source: ICP-MS facility, U Cape Town

28. HPLC-ICP-MS • quantitative measurement through know standard • high precision due to prior sample preparation • no isobaric interferences • use of multi-collector detection provides very precise isotope ratios

29. HPLC-ICP-MSExp. Procedure • dissolve the fuel rod sample in HNO3/HCl • prepare stock solutions using 1 m/L HNO3 • add reference material (eg. 242Pu) with known concentration • inject into HPLC-ICP-MS Günther-Leopold, I. et al., 2005

30. ICP-MS • detection limits: at or below ppt range • accuracy: if isotope dilution is used about 0.25% • drawback: for exact isotope ratios isotope dilution using standard has to be done for each element of interest

31. Final deposit • stage 1: selection of suitable geological sites • stage 2: at least two sites • stage 3: choice of location (2030-2040) • Outlook for 50 years • 100 000 m3 waste (plant, industry, research etc.) = volume of the hall main station in ZH Source:

32. Stage 1 • Evaluation of different sites ZH Source:ensi.ch

33. Stage 2 • March 2011: report • rock type, tectonic, hydrogeology, geochemical properties, biosphere, feasibility of the project and calculation of nuclear diffusion Source: ensi.ch

34. Literature and further reading Degueldre, C., Kuri, G., et al., 2010a. Nuclear material investigations by advanced analytical techniques. Nuclear Inst. and Methods in Physics Research, B, 268(20), pp.3364–3370. Degueldre, C., Martin, M., et al., 2010b. Plutonium uranium mixed oxide characterization by coupling micro-X-ray diffraction and absorption investigations. Journal of Nuclear Materials Guillong, M. et al., 2007. A laser ablation system for the analysis of radioactive samples using inductively coupled plasma mass spectrometry. J Anal At Spectrom, 22(4), p.399. Günther-Leopold, Ines et al., 2007. Characterization of nuclear fuels by ICP mass-spectrometric techniques. Analytical and Bioanalytical Chemistry, 390(2), pp.503–510. Günther-Leopold, I et al., 2005. Measurement of plutonium isotope ratios in nuclear fuel samples by HPLC-MC-ICP-MS. International Journal of Mass Spectrometry, 242(2-3), pp.197–202. Moreno, J. & Betti, M., 1999. Determination of caesium and its isotopic composition in nuclear samples using isotope dilution-ion chromatography-inductively coupled plasma mass spectrometry. J Anal At Spectrom. Orlov, A.V. et al., 2010. Investigation on a corrosion product deposit layer on a boiling water reactor fuel cladding. Nuclear Inst. and Methods in Physics Research, B, 268(3-4), pp.297–305. PerkinElmer, 2011. The 30-Minute Guide to ICP-MS.