First on the South Pole, 14 December, 1911

Transcription

1 First on the South Pole, 14 December, 1911

2 The potential use of small transportable neutron generators for studies of industrial mass flow Tor Bjørnstad Institute for Energy Technology (IFE) and Uniersity of Oslo

3 On demands. Short-lied radioactiely labeled tracers for liquid and solid phases at remote locations How to generate short-lied radionuclides? Nuclear reactors - cannot be moed! Particle accelerators cannot be moed! Isotopic/isotropic neutron sources can be moed but not turned off! Are there other solutions? Tor Bjørnstad 4

4 Radiotracer generator principle Elution of daughter nuclide Mother radionuclide Daughter radionuclide Radiotracer (RT) generator Radionuclide (RN) generator Radiotracer for aqueous, organic or solid phases Solution chemistry Tor Bjørnstad 9

5 Principle of a neutron generator Sealed-tube neutron generator: The principle of a neutron generator is illustrated below: HV D D + + e - D + D + n Ion source Deuterium T or D (in Ti) gas target Deuterium accelerated against tritium or deuterium gies the reactions: D + T 4 He + n (14.1 MeV) D + D 3 He + n (2.5 MeV) Tor Bjørnstad 11

6 Sealed tube neutron generator Berkeley design Tor Bjørnstad 12

7 Compact Spherical Neutron Generator, Adantages: High brightness Works like a point source High Flux High neutron field Safe D-D reactions IB-1675, Berkeley design RF antenna Target electrode Magnet Perforated extraction electrode Chamber cooling High-oltage feed-through Vacuum chamber Tor Bjørnstad 13

8 World s smallest neutron generator- The Sandia Laboratories Neutristor Deuterium target Negatie oltage Ion lens Ion source Positie oltage Drift region Tor Bjørnstad 14

9 Neutron generators (D-D and D-T) Neutron Energy : 14 MeV (DT) or 2.5MeV (DD) Neutron yield : up to n/s/4πsr (DT) or 10 8 n/s/4πsr (DD) Typical tube lifetime at n/s/4πsr (DT) : 4000 hour SODERN sealed tube Neutron Energy: 14 MeV (2.5 MeV for D-D) Neutron yield: up to n/s ( n/s for D-D) Typical tube lifetime: 4000 working hours (for 10 8 n/s) SODERN Sealed tube Tor Bjørnstad 15

10 Proton number Z Various reactions with «fast» particles (n,2n) Target Nuclide (n, ) (2n, ) (n,n ) (n,nnp) (n,np) (n,p) (n, n) (n, ) Neutron number N Tor Bjørnstad 16

11 Off-line fast neutron actiation on-line mount. Neutron generator Piston cylinder Aqueous/ acidic sol. Solid actiable compound Complexing chemistry Radiotracer injection D-D and D-T Flowline Tor Bjørnstad 17

12 Off-line thermal NA on-line mount. Neutron generator Moderator Displacing fluid Solution of actiable compound Complexing chemistry Radiotracer injection D-D and D-T Flowline Tor Bjørnstad 18

13 Neutron flux multiplication by moderator optimization? Neutron generator Metal with high (n,2n) reaction cross section Compound generating high-energy -rays Deuterium or 9 Be compounds Only D-T Moderator Neutron reflector Tor Bjørnstad 19 Solution of target material

14 Off-line fast or thermal NA off-line mount. Solution of actiable compound Thermal neutrons Complexation chemistry D-D and D-T Neutron generator Moderator Fast or thermal neutrons Flowline Complexation chemistry Solids dissolution Tor Bjørnstad 20 Solid actiable compound

15 In-flow fast «pulse» NA on-line mount. Neutron generator, pulse irradiation Lead collimator Gamma detector Flowline In-situ generation of radiotracer from matrix elements Radiotracer pulse detection Mainly D-T Example - irradiation of water: 16 O + n 14MeV 16 N (7.13 s) Tor Bjørnstad 21

16 In-line tracer generation by actiation of injected non-radioactie compound Piston cylinder Neutron generator, continuous irradiation Actiable tracer Lead collimator Gamma detector Flowline Flowline Pulse injection of non-radioactie but actiable compound In-situ generation of radiotracer in the injected pulse Radiotracer pulse detection D-D and D-T Tor Bjørnstad 22

17 On-line PGNA of injected non-radioactie «tracer» compound Piston cylinder «Actiable» tracer compound Neutron generator, continuous irradiation Lead collimator Pulse injection of nonradioactie compound with high interaction cross section Prompt gamma generation Gamma detector D-D and D-T Tor Bjørnstad 23

18 On line detection of injected non-radioactie «tracer» compound by neutron transmission Piston cylinder Tracer compound with high Neutron generator, continuous irradiation Flowline Injection of nonradioactie tracer compound high thermal cross section Neutron detector Mainly D-D Tor Bjørnstad 25

19 On-line detection of injected non-radioactie «tracer» compound by actiation foil method Piston cylinder Tracer compound with high absorption cross section Neutron generator, continuous irradiation Lead collimator Pulse injection of nonradioactie compound with high absorption cross section Tor Bjørnstad 26 Actiation foil Actiation and delayed or prompt gamma generation from the foil Gamma detector D-D and D-T

20 Pulse injection of nonradioactie but actiable tracer compound with high actiation cross section Off-line actiation of actiable «tracer» compound with offline sampling Continuous injection of nonradioactie but actiable tracer compound with high actiation cross section Sampling Tor Bjørnstad 27 D-D and D-T

21 Off-line actiation of collected actiable «tracer» compound Irradiated sample Gamma spectroscopy Gamma ray Lead collimator Off-line, on site neutron irradiation (NAA) Gamma detector Liquid scintillation counting ( ) Neutron generator, continuous irradiation PM1 Liquid scintillation cocktail with beta counting sample PM2 h Tor Bjørnstad 28

22 Summing up Aailability of small transportable neutron generators makes possible, in principle, RTD experiments to be carried out on «remote» locations A number of methods are possible, as outlined in the preious picture frames. None of these sketched methods hae, as of yet, been properly examined and deeloped. A major obstacle for further method deelopment and general dissemination is probably the up-front inestment cost. Major laboratories, supported by IAEA, should possibly lead the way and propose the most affordable and flexible combination of instrumentation and basic method(s). CRP? Tor Bjørnstad 29