The use of high-flux reactor SM-3 for activation process of molibdenum-99 production

Transcription

1 ROSATOM STATE ATOMIC ENERGY CORPORATION ROSATOM The use of high-flux reactor SM-3 for activation process of molibdenum-99 production V.D. Risovanyy (JSC «Science & Innovation», Moscow) A.L. Izhutov, V.A. Tarasov, Yr.G. Toporov (JSC «SSC RIAR», Dimitrovgrad) V.S. Skuridin (TPU, Tomsk) Symposium «Opportunities and Approaches for Supplying Molybdenum-99 and Associated Medical Isotopes to Global Markets», , Vienna

2 Production of activation Mo-99 in the RBMK-1000 reactor and fabrication of Tc-99 eluate at Radium Institute Centrifugal extractor Since 1992, the Radium Institute delivers Tc-99m eluate to St. Petersburg hospitals 2

3 Tc generator «99m Тс-GT-TOM» (TPU, Tomsk, 2003) Generators (19 GBq and more) are developed with the use of activation Мо-99 with a standard body. The amount of activation Mo makes up 175mg against 5mg when using fission Mo-99. At a specific activity of 50Ci/g to produce 1 generator, the Mo mass will make up 0.025g only (in metal). Such amount can be easily absorbed on a generator column of a standard size. 3

4 Main problems of activation method of Mo-99 production and ways to increase specific activity Key issue of activation 99 Мо: - low section of thermal neutrons absorption by a target from 98 М (0,212 barn); -short half-life of 99 Мо (66hs) that does not allow having a high specific activity during a relatively short irradiation period (6-10 days to achieve the plateau). As a rule, the traditionally applied targets allow the activation of only one atom per 1000 atoms of 98 Мо by reaction 98 Mo(n,γ) 99. The dissolution of a target results in 99 Мо containing a lot of carriers (other Mo isotopes). Ways to increase the 99 Мо specific activity: -to use target enriched more than 98% in 98 Мо (in natural Mo its content is 24%); -to use high neutron flux; -to increase the resonance component in the neutron spectrum -to decrease the number of carriers 4

5 Examined targets with Мо-98 in SM-3 Parameters Characteristics&values 1 Material Mo oxide 2 Enrichment in Мо-98 24,13% (natural) 81,04% (enriched) 3 Target shape Powder pressed in pellets after annealing 4 Pellet density, g/cm 3 2,5 5 Diameter and height of Mo pellets in an ampoule, mm 9х300 6 Amount of Mo per ampoule, g about 30 7 Diameter of ampoule with targets, mm 10х0,4 8 Ampoule material Quarts 5

6 Cross-section of a specific SM-3 fuel assembly with cells to irradiate targets; SM-3 core arrangement Д Д6 КО КО Д8 1 3 Д Д Д4 92 КО КО1 Д Д3 3 2 Д2 7 8 Д fuel rod; 2 - FA duct; 3 - irradiation cell duct; 4 - target central neutron trap; 2 - specific FAs with 4 irradiation positions (core irradiation positions) 3 - channels in the Be reflector; 4 - standard FAs; 5 - shim rods with FAs

7 Activation production of Mo-99 in reactor SM-3 Irradiation position Мо-99 specific activity, Ci/gMo Ampoule option, Мо mass (metal) per ampoule, g Quarts ampoules Pellets No. of ampoules in the irradiation position Total Мо-99 activity per an irradiation position, Ci 1 cell of the SM-3 neutron trap 80 3,0 unpractical 1 - Channel of the SM-3 reflector 2nd row ( 10) 8 4,5 30, SM-3 FA ,5 30, Channel of the SM-3 reflector 3rd row ( 20) or RBT reactor channel 1,5 4,5 30,

8 4.Activation process of the Mo-99 production using nano-powder of Мо 2 С nm нм Mo Растворение Dissolution С 99 Mo 0,2-0,4 nm нм n Szilard-Chalmers effect Elastic interaction of atoms with neutrons, displacement cascades, escape of atoms from the lattice on the structure defects Extraction of 99 Mo by dissolving surface layers of the initial target nano-powder 8

9 4.Calculation and theoretical research of recoil atoms yield in reaction 98 Mo(n,γ) 99 Mo (nano-particles MoS 2 10 nm in diameter) Particle radius R = 5 nm Initial energy 100 ev Yield of Mo atoms Initial energy 30 ev Coordinate of the initial location of a Mo atom, nm 9

10 4. Мо 2 С nano-powder structure (RIAR) 10

11 Мо 2 С crystalline structure 11

12 4. Irradiation rig CMP 12

13 Increase of specific activity Concentratio n of KOH, mol/l Content of Mo in a weighted amount, mg Spec. activity of a weighted amount, Ci/g Mo Content of Mo in the filtrate, mg Spec. activity of filtrate, Ci/g Mo Enrichment factor ,66 0,7 13,39(19%) 1,13 1,6 0,1 71,52 0,9 17,84(25%) 1,35 1,5 13

14 Cell of a heterogeneous target from nano-particles of Mo-98 and Al 2 O 3 14

15 Test of a flat target in a cyclotron (Kurchatov Institute) - Al 2 O 3 powder as a buffer accumulating 20,5% of 99 Mo - enrichment factors: on the 1 st (paper) filter F1=18,3, on the 2 nd (0.22µm) F2= 10,2 - total yield of 99 Mo made up 20,5% that correlates with the extraction into wipe of 78% of 99 Mo activity - Specific activity of Mo-99 extracted by wipe (20% from the produced) will be about 1000 Ci/g 15

16 Conclusion 1.More 25 years Radium institute are using activation method of Mo-99 production in Centrifugal Extractor for medical clinics of St-Petersburg 2. TPU has developed and is producing generators (19GBq and more) using activation Mo-99 with a standard body 3. Experiments have proven that Mo-99 can be produced by activation method in SM-3 reactor with specific activity 80 Ci/g in a trap and 50 Ci/g in fuel assembly in case of 80% enrichment of Mo-98 and full dissolution after irradiation. Four ampoules with 120g Mo-98 in fuel assembly produce 4800 Ci Mo-99 in 10 days. It is possible to load 6 fuel assemblies (26800 Ci) 4. Principle and technical possibility of production of 99Mo with high specific activity by using targets made of nano-particles has been shown. Activity may be increased up to 1000 Ci/g with particle sizes nm 16