The SCK-CEN Activities in Neutron Dosimetry

Transcription

1 The SCK-CEN Activities in Neutron Dosimetry Filip Vanhavere Belgian Nuclear Research Centre SCK-CEN NPL, September 25th 2001 p 1

2 The Belgian Nuclear Research Centre SCK-CEN Beach BR2 Rad. Prot. BR1 Underground laboratory p 2

3 SCK-CEN: Belgian Nuclear Research Centre 600 researchers mainly working in: reactor safety reactor material research MYRRHA project: a multipurpose accelerator driven system radioactive waste research decommissioning of nuclear installations disposal of vitrified waste in geological clay formations BR2 R&D isotopes production and NDT (neutron doping by transmutation) p 3

4 Radiation Protection Low-level measurements Decision strategy research Radiation Protection Research radiobiology Radon radioecology Safeguards and measurements safeguards spectrometry and NAA (neutron activation analysis) Instrumentation, calibration and dosimetry p 4

5 Neutron calibration facilities at the SCK-CEN Radionuclide sources: 2x 252 Cf, Am-Be, Ra-Be, Am-Li Accreditation for 252 Cf calibrations of neutron area monitors p 5

6 Thermal neutron beam at the BR1 reactor p 6

7 Dosimetry service Gamma and beta TL-dosemeters (TNO system, Harshaw detectors, 5000/month) Extremity and environmental dosimetry Neutron dosimetry: BTI bubble detectors combination BD-PND and BDT poole of 15 detectors (x2) only used for specific applications p 7

8 Criticality dosemeter Used at SCK-CEN, BN and FBFC in the Molarea Based on activation of 197 Au(n,gamma) 198 Au 115 In(n,n ) 115 In m 32 S(n,p) 32 P Basic reconstruction of spectrum by algorythm Yearly test at BR1 p 8

9 phd-work focussed on Research on characteristics of the bubble detectors energy dependence: combination of BD-PND and BDT angular dependence temperature dependence Application in MOX-producing plant nuclear power plant medical field p 9

10 Some results Relative respons BDT BD-PND H*(10) ICRP 51 Sensitivity relative to 21 C C 28 C 35 C Energy [MeV] Days after BTI calibration p 10

11 Present research: temperature dependence of BDT detector Pilot test of new type of temperature compensation: preliminary results Relative sensitivity temperature [ C] temperature [C] Relative sensitivity p 11

12 Future research Medical application: neutron contamination at radiation therapy LINAC s influence of IMRT High energy response of BTI detectors New type of BDT p 12

13 Neutron sensitivity of new TL-materials Present personal dosimetry systems use LiF-based materials Other materials (new alkali fluoride compounds)? LiKYF 5 :Pr 3+ % at. doping concentration 0, 0.1, 1, 3, 5, 10 KYF 4 :Tm 3+ % at. doping concentration 0.1, 1 The main objective was to see if these materials are suitable for gamma and/or neutron dosimetry p 13

14 Sensitivity to thermal neutrons vs. gamma s Comparison to TLD material Intensity (a.u.) TLD100 TLD600 TLD700 LiKYF5-1 at.% Pr3+ KYF4-1 at.% Tm Temperature ( C) n (+gamma) 1 msv gamma n/gamma TLD TLD TLD LiKYF5-1% KYF4-1% p 14

15 EValuation of Individual DOSimetry in mixed neutron and photon radiation fields: EVIDOS (FP5) PTB, IPSN, DIMNP, NRPB, SCK-CEN, SSI, PSI Characterisation of workplace fields + measurements with different detectors SCK-CEN: bubble detector measurements workplaces:venus reactor and BN p 15

16 The VENUS reactor facility Zero-power research reactor at the Belgian Nuclear Research Centre Studies on light water reactor fuels p 16

17 Comparison of different neutron spectrometric methods Fluence per lethargy [1/cm².h] 1E+7 1E+6 Tripoli Multisphere + proton recoil detector ROSPEC BINS 1E+5 1E-1 1E+0 1E+1 Energy [MeV] p 17

18 Tissue Equivalent Proportional Counter SW5 proportional counter (Far West Technologies): recent purchase Filled with propane-based tissue equivalent gas First test starting Measurements in neutron, gamma and mixed fields p 18

19 Summary Neutron dosimetry: limited manpower, some interesting tools Goals: to be experts in Belgium to maintain expertise to do usefull applied research to collaborate with international groups p 19