Júlio Takehiro Marumo. Nuclear and Energy Research Institute, IPEN CNEN/SP, Brazil

Transcription

1 Júlio Takehiro Marumo Nuclear and Energy Research Institute, IPEN CNEN/SP, Brazil

2 Introduction Brazil State of São Paulo City of São Paulo Reactor IEA-R1 Source: Source: Production of Radioisotopes for Medical Applications Research and development activities

3 Waste Management Department - IPEN Disused sealed sources dismantling cell Compaction unit General view Lightning rod dismantling cell Chemical laboratory Interim storage Radiometric Laboratory Source:

4 Poços de Caldas Laboratory - LAPOC State of Minas Gerais Poços de Caldas City LAPOC Source:

5 Poços de Caldas Laboratory - LAPOC Liquid scintillation analyzers Low energy gamma-ray spectrometry Gamma-ray spectrometry ICP-MS Chemical laboratory Perkin Elmer sample oxidizer

6 Characterization team IPEN 3 chemists 3 physists 2 laboratory technicians Postgraduated students and trainees LAPOC 3 chemists 2 physists 4 laboratory technicians

7 Currently, the team is beginning to develop a project to characterize the historical, already immobilized wastes generated by the two units of the Angra Nuclear Power Plant since The two recently replaced steam generators and the pressure vessel lid of Angra Unit I are also included in the contract being signed between IPEN-LAPOC and the Utility for the waste characterization work Source:

8 Recent publications A comparative study using liquid scintillation counting and X-ray spectrometry to determine 55 Fe in radioactive wastes (in J. Radioanalytical and Nuclear Chemistry, 2013) Determination of 63 Ni and 59 Ni in spent ion-exchange resin and activated charcoal from the IEA-R1 nuclear reserach reactor (in Applied Radiation and Isotopes, 2013) Determination of long-lived rdionuclides in radioactive wastes from the IEA-R1 nuclear reactor (in J. Radioanalytical and Nuclear Chemistry, 2013)

9 IEA-R1 (IPEN s reactor) First reactor to operate in South Hemisphere Location: Nuclear and Energy Research Institute (IPEN CNEN/SP) Type: Open pool research reactor First operation: September, 1957 Maximum power: 5 MW (2 MW until 80 s) Graphite reflector Coolant and moderator: light water U-235 enrichment: 19.75% (~93% until 80 s) Supplier: Babcock & Wilcox Co., Source:

10 The waste: Resins and charcoal liter drums (resins); liter drums (charcoal) Contact dose rate: 2-10 msv/h (resins); msv/h (charcoal) Moisture content of the packages variable; 200-liter drum (steel) Polyethylene bag Overpack (PVC)

11 Sampling Planned carefully to avoid high personnel exposures and contamination; 42 samples of charcoal from L-drums 36 samples of resins L-drums Sampler Scoop One bag/drum Five bags/drum

12 Sampling of ion exchange resins Sampler

13 Sampling of ion exchange resins and charcoal Sampler being inserted in the plastic bag that contains the waste; Sample in the lower window being transferred to a sample container.

14 Sample preparation drying 5 g aliquots Stove 60 C 24 hours Counting 2 g dry mass Germanium Detector Canberra Co-axial Hyper-pure P-type GX4519 (resolution of 1.9keV and relative eff of 45%) Calibration with certified Amersham Eu-152 (122 to 1,408 kev) and Pb (46.5 kev) point sources; Sample dissolution/stock solution Resin 1.5g + HNO 3 conc (3 x) + H 2 O 2 30% + HClO 4 conc HNO 3 8M Charcoal 1.5g calcined (450 C; for 24h) HNO 3 conc (3 x) + HF conc + H 2 O 2 30% + HClO 4 conc HNO 3 8M

15 232 U, 242 Pu, 243 Am, 236 Pu

16 Table 1: Activity concentration (Bq g -1 ) of KN, 90 Sr and actinides in samples of activated charcoal and ionexchange resins Radioisotope 60 Co 90 Sr 137 Cs 234 U 235 U 238 U 238 Pu 239/240 Pu 241 Pu 241 Am 244 Cm Activated charcoal Minimum 1.2E E E E E E E E E E E-05 1st Quartile 2.5E E E E E E E E E E E-04 Median 3.4E E E E E E E E E E E-03 3rd Quartile 4.4E E E E E E E E E E E-03 Maximum 5.5E E E E E E E E E E E-02 Number of samples Ionexchange resin Minimum 4.3E E E E E E E E E E E-05 1st Quartile 4.1E E E E E E E E E E E-04 Median 1.6E E E E E E E E E E E-04 3rd Quartile 9.1E E E E E E E E E E E-03 Maximum 6.5E E E E E E E E E E E-02 Number of samples Np concentration below Bq g -1 detection limit Pu expressed together because alpha emissions energies are close Chemical recovery 62-85% for Sr, 75-99% for U, 60-95% for Np/Pu and 45-85% for Am/Cm

17 Decomposed sample solution 8 Mol L -1 HNO 3 Add stable Ni e Fe Adjust ph 8-9 with NH 4 OH Precipitate Fe(OH) 3, NI(OH) 2, M(OH) x Dissolution 9 Mol L -1 HCl ph adjustment NH 4 OH Eluate 55 Fe Dowex 1x4 anionic 1) Wash 9 Mol L -1 HCl 2) Wash 4 Mol L -1 HCl 3) Eluting 55Fe with 0.5 Mol L -1 HCl Precipitate Fe(OH) 3 LEGe 55 Fe Effluent 59 Ni, 63 Ni Stable Fe ICP-OES LSC 55 Fe 1) Evaporation 2) Dissolution with 1 Mol L -1 HCl, adic. NH 4 citr., NH 4 OH ph 9 Precipitate Ni- DMG Eluate 59 Ni, 63 Ni Column Ni (DMG) 1) Wash with 0.2 Mol L -1 amonium citrate (interference removal) 2) Elution with 3 Mol L -1 HNO 3 Filtration LEGe 59 Ni Dissolution 3 Mol L -1 HNO 3 Stable Ni ICP-OES LSC 63 Ni

18 Table 2. Results of 55 Fe activity concentration obtained by liquid scintillation counting and X-ray spectrometry, along with the Fe chemical yield determined by ICP-OES Sample Liquid Scintillation Counting [Bq.g 1 ] X-ray Spectrometry [Bq.g 1 ] Chemical Yield [%] CA ± ± CA ± ± RTI ± ± RTI ± ± RTI ± ± RTI ± < RTI ± ± RTI ± ±

19 Table 3. Activity concentrations of 63 Ni and 59 Ni in spent ion-exchange resin and activated charcoal samples, and chemical yield of the stable Ni carrier added in the determination process. Spent ion-exchange resin Spent activated charcoal Sample 63 Ni [Bq.g 1 ] 59 Ni [Bq.g 1 ] 63 Ni/ 59 Ni Yield [%] 63 Ni [Bq.g 1 ] 59 Ni [Bq.g 1 ] 63 Ni/ 59 Ni Yield [%] ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± Average 132 Average 131 SD 58 SD 66

20 PhD thesis conclusion(maria Helena Tirollo Taddei) Determination of scaling factors to estimate the radionuclide inventory in waste with low and intermediate level activity from the IEA-R1 reactor 3 H and 14 C (ß emitters) concentrations were determined by Oxidizer/LSC. PerkinElmer Model A307 Sample Oxidizer is an instrument that combusts the sample material to achieve physical separation of 3H and 14C radionuclides into two separate counting vials. 108m Ag (γ emitter) concentration was determined by coprecipitation with silver chloride (AgCl) using silver nitrate solution and concentrated hydrochloric acid. The PhD thesis applied the scaling factor methodology in order to estimate the radionuclide inventory of spent ion-exchange resins and activated charcoal beds from a nuclear research reactor. This work determined the activity concentrations of 18 DTM ( 3 H, 14 C, 55 Fe, 59 Ni, 63 Ni, 90 Sr, 108m Ag, 234 U, 235 U, 236 U, 238 U, 238 Pu, Pu, 241 Pu, 241 Pu, 241 Am and Cm) and two key nuclides (KN), 60 Co and 137 Cs. Scaling factors or correlation functions were establishedbetweenalldtmand KN withthe onlyexceptionof 3 H

21 Activity concentration of each radionuclide meaured in ion exchange resin and activated charcoal.

22 NEXT CHALLENGE As we are working on the project of characterization of waste generated from Angra NPP, our team has to develop analytical methods for 93 Zr, 94 Nb, 99 Tc, 129 I, 135 Cs

23 Thank you! Júlio Takehiro Marumo Waste Management Department Nuclear and Energy Research Institute IPEN CNEN/SP São Paulo - Brazil jtmarumo@ipen.br