How To Make Molybdenum 99

Transcription

1 IAEA-TECDOC-1065 XA Production technologies for molybdenum-99

2 The originating Section of this publication in the IAEA was: Industrial Applications and Chemistry Section International Atomic Energy Agency Wagramer Strasse

3 The IAEA does not normally maintain stocks of reports in this series. However, copies

4 Nuclear medicine FOREWORD

5 EDITORIAL NOTE In preparing this publication for press, staff of the IAEA have made up the pages from the original manuscripts

6 CONTENTS Surrimaiy...^ Characteristics of nuclear reactors used for the production of molybdenum R.M. Ball Targets

7 SUMMARY Technetium-99m (6.02 h) is the most widely used radioisotope in nuclear medicine, accounting

8 The presently installed processing capacity is substantially larger than the above mentioned demand,

9 photon radiopharmaceuticals (i.e.

10 CHARACTERISTICS XA

11 In practice, one cannot productively capture all the neutrons available and a comparison among reactor types, shown later,

12 with

13 TABLE I. CHARACTERISTICS OF REACTORS USED TO IRRADIATE TARGETS FOR "MO PRODUCTION Reactor Name Location Power kwth Flux nvth Target Vol. cm 3 (1 tar.) NRU Canada 135, E HFR Netherlands 45, E ACRR USA 2, E HFIR USA 85, E15 TRIGA USA 2, E13 MURR USA 10, E14 -- SAFARI- 1 South Africa 20, E14 HIFAR Australia 10, E NRU Reactor This reactor

14 quantities of "Mo have been made in The reactor is owned and operated under contract for the U.S. Department of Energy. It is stated to be a "backup" for other commercial sources of "Mo HFIR Reactor

15 1.4. Heat removal requirements for targets used to make "Mo Irradiation of 98 Mo Targets The deposition of energy in

16 (3) By using daily extraction of "Mo, eliminates the unrecoverable losses from target decay within the reactor (see Figure 1). (4) Reduces the amount of fission product waste produced by a factor of 100 and stores long lived wastes within the reactor solution. (5) Requires only the

17 FIG

18

19 NONE Required Target Preparation NOT Required Encapsulate Ship FIG. 5. Process cycle using solution (MIPR) system. 8»

20 Downscaling the MIPR for Lower Production Requirements Some developing countries may desire a lower production rate, perhaps 8000 GBq week" 1. With three days of production, the reactor could be operated at less than 10 kw. The amount of uranium and the hardware requirements for reactor operation are much the same but the consumption of consumables and the production of radioactive waste are greatly reduced Uranium Consumption

21 S200/Curie

22 If a MIPR system were constructed with investment capital, the costs for the product must include repayment and interest. The other costs are variable costs associated the level of production.

23 TARGETS FOR THE PRODUCTION OF NEUTRON ACTIVATED MOLYBDENUM-99 XA E.L.R. HETHERINGTON, R.E. BOYD Australian Nuclear Science

24 2. TARGET CHARACTERISTICS Natural molybdenum consists of seven stable isotopes; neutron activation gives rise to only three molybdenum radioisotopes

25 TABLE II. PRODUCTION OF "Mo BY NEUTRON IRRADIATION OF MOLYBDENUM TRIOXIDE IN THE ANSTO RESEARCH REACTOR HIFAR Reactor Type 10

26 [4] NARASHIMAN, D.V.S., VANAJA, P, IYER, S.P., MANI, R.S., Development of a new

27 PURIFICATION ANNEX

28 XA CONVERTING TARGETS AND PROCESSES FOR FISSION-PRODUCT MOLYBDENUM-99 FROM HIGH- TO LOW-ENRICHED URANIUM G.F. VANDEGRIFT, J.L. SNELGROVE, S. AASE, M.M. BRETSCHER, B.A. BUCHHOLZ,

29 performance, economics,

30 TABLE

31 TABLE

32 TABLE

33 TABLE II. (Cont.) Major Technical Challenges to LEU Substitution (Continued) Specific Acid Dissolution Process Base Dissolution

34 TABLE II. (Cont.) Means Convert to Acid Dissolution Process Base Dissolution

35 TABLE II. (Cont.) Means Acid Dissolution Process Base Dissolution

36 TABLE II. (Cont.) Status Acid Dissolution Process Base Dissolution

37 TABLE H. (Cont.) Status Acid Dissolution Process Base Dissolution

38 In

39

40 Postirradiation examinations performed during April and May of 1996 showed that the uranium foil was bonded to the inner tube of each of these targets. The tentative explanation

41 The latter two targets demonstrated the viability of the fission-fragment-barrier concept. Another series

42 surface preparation has been extremely challenging. We must balance surface roughness against dissolution of the foil. We have used an alkaline zincate bath for plating zinc, an alkaline copper phosphate bath

43 FIG. FIG. 3. SEM photograph showing nodular nature of Zn plate.

44 FIG. 5. Early Zn-plated uranium foil showing considerable loss of uranium during etching. FIG.

45 FIG.7. Two examples of acceptable zinc-plated uranium foils. Scanning electron micrographs of an early attempt at plating uranium with zinc barriers are shown

46 Surface preparation is a compromise between optimal conditions for making a uniform

47 Target dissolution The Cintichem HEU target is a closed cylinder with an electrodeposited layer of UO

48 positive. This gave a a of , a 33 of , a n! of , a n2 of , a sl of , a s2 of ,

49 10 o c 1 Nitric acid is 3M in all cases S 1 03 EC _o *3 _=> O V) V) 1M Sulfuric Acid 2M Sulfuric Acid FIG looon; I/K -t-

50 TO In a ct^ 3 (A in 0) ^ a. w ffi > o in in tuu A l\ < >* 1 I 1 ' f. I * *, f il '/,', I ' /' ''" 'I* '(. I ' -D g.BAT AN

51 compound. Although we have been developing the Zn-barrier foils for basic dissolution, using it for acid-side processing is certainly possible if the dissolution rate can be easily handled by increasing dissolver temperature. Further details

52 volume

53 FIG.

54 TABLE

55 In summary, our experimental results predict that replacing the current dissolution cocktail, which contains both nitric and sulfuric acids, with nitric acid alone will not compromise the effectiveness of the Cintichem process. In our tracer experiments with this substitution, molybdenum recovery and purity were not degraded. Removal of sulfuric acid from

56 An important side reaction that occurs during the silicide dissolution process is the autodestruction of hydrogen peroxide: 6 2H 2 O 2

57 is considered. The different activation energies for the two particle types show that more than surface area differences are relevant in the dissolution kinetics of atomized and comminuted U 3 Si 2 particles. 100 a. -29 D C, CO --*--50 C,CO - r 50 C,AT -» C, CO o Initial NaOH Concentration (mol

58 or 160=[H0 2-3[H 2 0] = [HQJ] [H ][OH~] [H ][OH-] Figure 14 plots the equilibrium concentrations of O 2 H~, OH", and H 2 O 2 for a fixed initial peroxide concentration of 5.2M H 2 O 2 and variable initial OH" concentrations. In basic solution the equilibrium H 2 O 2 concentration

59 Eventually, through a series of fast reactions, complex B becomes the soluble form of uranium that

60 Dissolving unirradiated U

61 Cladding precipitates must

62 Design of a dissolver system for a two-step process that also provides physical desegregation is a difficult technical problem. This among other problems led us to suspend activity in this area and look toward other targets Uranium-foil targets We first dissolved uranium foil

63 this basis,

64 10" o» * J o Cfl C/3 S -r IO' 5 Z <OS 3 b O a < 65 lo' 7

65 10'= on u. O UJ O 2 UJ 0. Q. E o "o E 10" Various Base 0.2M NaOH LOMNaOH 5.0M NaOH li. O UJ 10' 10' 10"' 10 [H 2 O 2 ] AT EQUILIBRIUM (M) FIG.

66 Based

67 An optimized procedure

68 foil. Zinc is an active electropositive element and forms a strong anion with oxygen. It also dissolves readily in sodium-hydroxide/nitrate solution. Work on barrier materials for targets to be processed

69 Solutions suitable for dissolving the intermetallic U/Zn compound were pursued. Attempts to dissolve the zinc from this foil showed that this intermetallic would not dissolve as the zinc plate had from the unheated foils (at 70 C with 50 ml of 2.5M NaOH and 1M NaNO 3 ).

70 aluminum dissolution. Finally,

71 irradiated

72 Alummum/UO Dispersion Aluminum Cladding Dispersion FIG. 22. Illustration of a UO 2 /AI-dispersion plate and micrograph of a UO 2 /Al-dispersion compact. Molybdenum recovery was high, and purification was as expected when the two-step dissolution was followed by acidification and molybdenum sorption on an alumina column. Because

73 Once conditions for LEU target dissolution are firm, we will need to reinvestigate the effects of these compositional and volume differences on the primary molybdenum-recovery step. 6. PLANNED R&D ACTIVITIES We will continue our development activities on both acid- and base-side processes. The LEU-modified Cintichem process needs

74 [6] SAMEH, A.A., ACHE, H.J., "Production Techniques of Fission 99 Mo", Fission Molybdenum for Medical Use, Proc. of Technical Committee Mtg. Organized by the International Atomic Energy Agency, Karlsruhe, October 13-16, 1987, IAEA-TECDOC-515 (1989) [7] SALACZ, J., "Processing of Irradiated

75 [19] LUNDQUIST, J.R., BRAUN, R.L., STROMATT, R.W., "Nickel Plating Uranium: Review

76 LEU Targets for "Mo Production Demonstration of a Modified Cintichem Process", Proceedings

77 [48] HOFMAN, G.L., NEIMARK, L.A., OLQUIN, F.L, "The Effect

78 THE ACCELERATOR PRODUCTION XA

79 that A comparison of the experimental production yields reported in the literature indicates

80 3. RESULTS

81 100 Mo -f p Proton Energy / MeV FIG.

82 100 Mo + p 99i. (p.pn^mo 98ji (p,p2n) ah Mo c CO (p,p4n) 96 Mo (p,p3n) 97 Mo Proton Energy / MeV FIG.

83 potential accelerator production

84 IS 20 2S JO JJ SO W SO S3 70 o \ O 0 S O +S SO IS 60 6S 70

85 100i Mo

86

87 [2] Further steps to ensure moly-99 supply, J. Nucl. Med. 37 (1996) 34N.

88 [22] BLANN M., VONACH H.K., Global test of modified precompound decay models, Phys. Rev. C28 (1983) [23] MYERS W.D., SWIATECKI W., Anomalies in nuclear masses, J. Ark. Fys. 36 (1967) [24] SCHOLTEN

89 ACCELERATOR PRODUCTION OF 99m Tc WITH PROTON BEAMS XA

90 have suffered from minor

91 and should be able to withstand high current bombardments. The natural and enriched 98 Mo(VI) oxide (MoO 3. d= g/cm 3 ; m.p. 795 C; b.p C sub.) were used only in experiments conducted with low intensity beams (< 1 ya), as the Mo oxide is not an appropriate target material for high intensity bombardments. Other chemical forms of Mo were

92 similar enriched IOO Mo thick target

93 (BOB).

94 TABLE

95 TABLE III. REACTION CHANNELS

96 97 Mo, 96 Mo, 95 Mo and 94 Mo as target nuclides in the enriched 100 Mo targets, was minimized by using

97 each thin

98 TABLE IV. (Cont.) Proton Energy (MeV)

99 TABLE

100 > ' c o /3 co s u Experimental Data ""Fit Proton Energy (MeV) FIG. 2. Excitation function for the nat Mo(p,xn) 96 Tc reaction. 1500

101

102 However, the precision of the yield estimates for 96 Tc, 95 Tc, and 94 Tc, produced by the unfolding method, needed further testing (see section 3.4, below). Further analysis of the yield data

103 TABLE V. (Cont.) Target Energy (MeV) 16.0 ± ± ± ± ±

104

105 Experimental Data ""Fit Proton Energy (MeV) FIG.

106 TABLE VI. COMPARISON OF MEASURED AND CALCULATED To WITH 20.5 AND ^Tc YIELDS PRODUCED

107 Further experimental testing with a MeV thick

108 medical use. Technetium-96 (4.35

109 Tc-99m (140.5 kev) Gamma-ray Energy (kev) 450 FIG. 9. Gamma-ray spectrum of accelerator-produced 99m Tc from anenriched!00 Mo (CIS; 97.46%) thick ( MeV) target Radioassay at 25 h after BOB Tc-99m (140.5 kev) I u ( FIG Gamma-ray Energy (kev)

110 iu - au ex 3 O U Tc-94 (702.6 kev) \ c i CD cm "; "-'- Tc-95 (766 kev) p p oo on\ o cxfn <nno Tc-96 (849.9 kev) H O OOO QDO OD

111 cumulative 99m Tc yields per target were extrapolated to higher beam intensities and target power using enriched 100 Mo (97.46%). Results

112 I c o S 40 C/3 00 o u

113 depending on foreign supply based on the operation of few commercial reactors, and many at present rely on aging reactor facilities facing decommissioning. Accelerator facilities capable

114 [9] LAGUNAS-SOLAR, M.C. et al, "An update on the direct production of Tc-99m with proton beams and enriched Mo-100 targets". Annual Meeting of the American Nuclear Society (June 16-20, 1996), Reno, Nevada, USA. [10] EGAN G., JAMIESON, C., LAGUNAS-SOLAR, M.C., An investigation into the technical feasibility

115 EXCITATION FUNCTIONS XA

116 In the second part we present the results of our calculations concerning production yields

117 TABLE I. NUCLEAR DATA OF THE REACTIONS Nuclide Half life Molybdenum 101 Mo 14.6

118 TABLE I. (Cont.) Nuclide Half life 97 Tc 2.6*

119 TABLE I. (Cont.) Nuclide Half life Decay mode Niobium "Nb 15.0s P"(100) 99n Nb

120 TABLE I. (Cont.) Nuclide Half life 94m Nb 6.26

121 Cross-section [mb]

122 3.2.

123 Cross-section [mb] Cross-section [mb] c A 01 p [V. 0 yoen C/J en -» o> o o' g1 3 (B O^ ^ S 1 (-3 s -s 5. o P" <n ^^ A TO H p W o ro

124 to Cross-section [mb] w ; S en P ON O 3en en en.* 8«h o" U >3 O t. J O *< i 1 o "x 4" M

125 The excitation curve (Fig.5) shows two contributing reactions: 94 Mo(d,2n) (Q 7.34 MeV) and 95 Mo(d,3n) (Q= MeV), where the (d,2n) reaction on the less abundant 94 Mo (9.25 %) reaches a maximal cross section value near 16 MeV, making this the optimal production path using deuteron induced reactions below 21 MeV. From our measured cross section values a physical yield of 3545 MBq/mAh (95 mci/uah) is calculated for the energy range 12-17

126 Cross-section [mb] Cross-section [mb] o < -i. _L O SO 01 O < o o o < n HH P CO 0 3cn cn cn 8 3?. G 1 o 5 3 <3 0 '2 "x u! "~"«2*. I *? > -is Ol " j o ^0 % > ^^ "5 * i» 00 H p o ro at

127 Cross-section [mb] g & 8 Cross-section [mb] ro

128

129 investigate

130 TABLE II. DEUTERON INDUCED REACTIONS ON ENRICHED

131 Production yield

132 reactions 100 Mo(p,2n) 99m Tc and 100 Mo(p,pn)"Mo on Fig. 11 for comparison. The yields for proton were calculated from

133

134 HIGH BEAM INTENSITIES FOR CYCLOTRON-BASED RADIOISOTOPE PRODUCTION XA

135 internal P.LG. source,

136 sources. The adopted solution of an external H" source with its own pumping system allows the neutral gas to be pumped in the external source system, and moderate size pumps are sufficient

137 As

138 an extraction system allowing

139

140 ADONIS: THE PROTON-DRIVEN NEUTRON SOURCE FOR RADIOISOTOPE PRODUCTION XA Y. JONGEN Ion Beam Applications s.a., Louvain-la-Neuve, Belgium Abstract 99 The world production of fission Mo is today made in a very small number of research reactors which are getting quite old and are due, in the next years, for a major refurbishment or for decommissioning.

141 99 continue to use the existing and very expensive fission Mo chemical separation facilities, and

142

143 ^0^0 a H B D^0^ao^o^ e 3 ^ =& f E R,VoVflYnVn avii o 0 & o o ov^^ 3 > tj<j=j Wta,,1 I,. 1 1 i i. D m m Sl I will i i,-,-^jijjf 1 1

144 Fig. 2. Positioning of the uranium targets 143

145 All the above components are located in a main irradiation pool, for moderation and shielding purposes. Adjacent to the main pool is an annex pool (see Fig.l) allowing the remote handling

146 Fig. 3. Neutron flux distribution The maximum total production corresponds, at the end, to more than 50% of the world's demand, while the obtained mean specific activities are comparable to those presently obtained

147 [2] JONGEN, Y., "A Proton-Driven, Intense, Sub-critical, Fission Neutron Source for Radioisotope Production", International Conference on Accelerator-Driven Transmutation Technologies and Applications, Las Vegas, NV, July [3] MC ADAMS, R., KING, R.F., PROUDFOOT, G., HOLMES, A.J.T., "Pure and Cesiated CW Volume Source Performance at the Culham Ion Source Test Stand", Proceedings of Sixth Intl. Symposium

148 THE XA

149 Although some general comments

150 150g Mo03 Irrad. 7x10* 3 n/cm2/sec 7 days Dissolve in m NaOH

151 then another range of much higher radioactivities typical of those used in centralised radiopharmacies (the "jumbo" generators). A comprehensive program of performance testing

152 4.3. Other radionuclidic impurities After the short-lived radioactivities had decayed (a few days), several of the eluateswere re-examined for the presence (identity and concentration) of other radionuclidic impurities.

153 4.5. Radiochemical Purity Radiochemical impurities often arise due to the effects of radiation on the solvent(radiolysis), changes in temperature or ph, or the presence of reducing/oxidising agents. The pertechnetate ion is a strong oxidising agent capable of reacting with traces of reducing substances to produce lower valency species. Using thin layer chromatographic techniques the radiochemical species present in the eluates were investigated (Table VI) Elution Profile The elution profile of column based generators is influenced strongly by physical size and shape [6].

154 FIG. 2. The effect of bed size on the elution profile Clinical experience

155 The gaseous releases from

156 REFERENCES [1] COATS, R.L., "The "Mo Production Program at Sandia National Laboratories", Proc. Conf. American Nuclear Society, (Philadelphia, June 1995). [2] LAGUNAS-SOLAR, M. et al, Cyclotron production of NCA 99m Tc and "Mo. An alternative non-reactor supply source of instant " m Tc and "Mo, Appl. Radial. Isot. 42 (1991) [3] JONGEN, Y., "A Proton-Driven, Intense, Sub-critical, Fission Neutron Source for Radioisotope Production", Accelerator-Driven Transmutation Technologies

157 LIST

158 Vandegrift, G.F. Argonne National Laboratory, Argonne, Illinois, United States of America Vera Ruiz,