(Figure 4). Furthermore, extending the reaction time lessens the catalyst requirement. Approximately the same conversions were obtained in a 16-hour run made with 1.3 grams of catalyst per mole as in a n 8-hour run made with 2.5 grams of catalyst per mole. As shown in Figure 5, a n increase in the amount of catalyst results in a n increase in total conversion to cyclics as well as in an increase in the proportion of trans isomer produced a t both 800 and 1200 p.s.i.g. Obviously, in reactions of this type there is considerable interaction of variables and no one variable can be considered individually. However, a t temperatures u p to 220' C. an increase in any one of the four variables studied, temperature, hydrogen pressure, time, or catalyst concentration, tended to increase the conversion to 2,5-dimethylpiperazine, and tended to increase the proportion of trans isomer in the piperazine product. The best yields of 2,5-dimethylpiperazine and the
highest trans to cis ratios were obtained a t 1200 p.s.i.g., 220' C., with 2.5 grams of Raney catalyst per mole and with a reaction time of 4 to 8 hours. Under these conditions isopropanolamine was almost completely consumed and the yield of mixed dimethylpiperazine isomers was about 75%. The trans isomer content of this product was about 80%. literature Cited
(1) Bain, J. P., Pollard, C. B.. J . Am. Chem. SOC.6 1 , 532 (1939). (2) Ishiguro, T., Kitamura, E., Matsumura, M., Yakugaku Zasshi 77, 1051-4 (1957).
( 3 ) Langdon, W. K. (to \.L-yandotte Chemicals Corp.), U. S.
Patent 2,813,869 (Nov. 19, 1957). (4) Sasaki, T., Ydki GGsez Kagaku KyBkaiShi 16, 614-20 (1958). RECEIVED for review March 3, 1961 ACCEPTED October 23, 1961 Division of Industrial and Engineering Chemistry, 138th Meeting, .4CS, New York. N. Y., September 1960.
NITRIC ACID DISSOLUTION OF URANIUM= MOLYBDENUM ALLOY REACTOR FUELS WALLACE W. SCHULZ,
R A Y M O N D E. B U R N S , A N D E D W A R D M . D U K E '
Hanford Atomic Products Operation, General Electric Co., Richland, Wash.
Nitric acid dissolution procedures for the preparation of redox process solvent extraction feedstocks from U-Mo alloy reactor fuels have been developed. Special dissolution procedures are required to prepare low-acid solutions of relatively high (0.75M or greater) uranium content because of the limited solubility of uranyl polymolybdate and Moo3. In one procedure U-Mo alloys are dissolved in 3 to 5M "03-0.5 to 1 .OM Fe(N03)3 soluiions; under proper conditions dissolution can be accomplished without precipitation This process of solids. An alternative technique involves dissolution in concentrated ( 2 12M) " 0 3 . requires separation of large amounts of Moos,neutralization or destruction of residual HN03, and extensive treatment of Moo3to remove occluded uranium and plutonium. The necessity for a difficult liquid-solid separation step i s avoided b y dissolution in HN03-Fe(NO& solutions.
being designed or constructed in the United States are scheduled to use low enrichment (3000 140 2 0.0 0.80 0.36 0.89 0,061 5 29 41 91 5 3 -0.3 0.77 0.30 0.85 0,059 0 45 115 1800 9 4 -0.5 0.78 0.35 0.89 0.060 0 190 260 >3000 35 5 -0.5 0.75 0 . 8 3 0.61 0.058 3000 20 All feeds also 0.2M 2 % T a ~ c rand z o ~0.0008MPuOz(N0a)z. b Standard redox process feed; data from four runs averaged.
Run No.
5
7 extraction, 5 scrub.
llrasfe Losses, yo L' Pu 0.080 0.17 0.019 0.013 0.18 0.14 0.40 0.38 0.018 0.063
VOL. 1 N O . 2 A P R I L 1 9 6 2
159
TO STACK
UP-
,
DRAFT
1 AlNO3(OHl2
T NITROGEN OXIDES DISSOLVER CHARGE ONE TON U-3 WT% MO ALLOY 6 8 4 G A L H20 424 GAL 13 M HNO? 196 GAL 5 M Fe(NC&
I
1
I
ADDITION 4 M AI - 7 M “03 277 GAL
I
075 M U%(N03)2
1
1
1 ~
Figure 4. Flowsheet for HN03-Fe(N03)* dissolution of U-Mo alloy fuels
-
Precipitation of solids is avoided when this procedure is used to prepare redox process feeds
SOLVENT EXTRACTION FEED 062 M U02(N03)2 0048 M Mo 062 M Fe(N03)3 -040 M HNO 0.70 M Al(N&J3 1581 GAL.
during dissolution. Plutonium can be oxidized to the hexavalent state by adjusting dissolver solution acidity to about OM “03, adding Na2C1-20, to a concentration of 0.1 to 0.2 mole per liter, and heating for 2 hours at 90’ to 100’ C. Precipitation of uranyl polymolybdate occurs during the oxidation step if the Fe(N03)3 concentration is not at least equal to the UOn(N03) 2 concentration. Data from mixer-settler runs made under redox process conditions with U-3 wt. 7 0 Mo alloy solution are shown in Table 111. Feedstock for these runs was prepared by complete dissolution of U-3 wt. % Mo alloy in 4.1M “ 0 3 1M Fe(SOs)3-0.0009M Pu(NO3)d to yield a dissolver solution of the composition 0.92M UO:!(NO3)2-OM “O,-IM Fe(N03)3-0.0009M Pu(NO3)a. One-liter portions of this solution were spiked with 0.1 ml. of Hanford redox plant dissolver solution prepared from irradiated uranium metal to provide a source of fission product activity. Plutonium was then oxidized to the hexavalent state by addition of 59.7 grams of NazCrzO,. 2H20 to a liter of alloy solution and heating 2 hours a t 95’ C. After cooling to 25’ C., 4M AlNO3(OH)2 and 2.4M Al(N03)3 were added to adjust solutions to the desired feed acidities and Al(N03)3 concentrations. Solvent extraction runs were of 3 hours’ duration; end stream analyses indicated steady state conditions were attained in about 1 hour. Waste losses and decontamination factors were calculated from analyses of effluent streams produced in the third hour of operation. The following conclusions were drawn from mixer-settler run data: At about the maximum acid deficiency consistent with feed stability (runs 4 and 5) gross gamma and beta decontamination factors for U-Mo alloy solutions were lower than those for standard feeds by factors of about six and five, respectively. Radioruthenium decontamination limited over-all decontamination at this acidity. At higher acidities increased extraction of radioactive zirconium and niobium, as well as radioactive ruthenium, resulted in further decreased decontamination. In most cases, plutonium and uranium recoveries from U-Mo alloy solutions were comparable to those obtained with standard feeds. Molybdenum was not extracted from U-Mo alloy solutions under redox process conditions. CHEMICAL FLOWSHEET. Although mixer-settler runs were performed with U-Mo alloy solution containing 1M Fe(N03) 3, the flowsheet shown in Figure 4 specifies 0.75M Fe(NOJ3 for 160
I
I
I
0.75 M Fe(NO&, 11.00 M “02 “ 11304 GAL.
I
I&EC PROCESS DESIGN A N D DEVELOPMENT
dissolution. The lower Fe(N03)3 concentration is specified primarily because of the high corrosion rates which have been found ( 9 ) for available materials of construction in “ 0 8 Fe(N03) 3 solutions. The flowsheet shown allows complete dissolution of U-3 wt. % Mo alloy without precipitation of uranyl polymolybdate. Appropriate adjustments in terminal uranium and/or terminal acidity are required for dissolution of alloys of higher molybdenum content without formation of solids. For example, dissolution of U-10 wt. % Mo alloy to 1M H x 0 3 at 0.75M Fe(N03)3 requires that the terminal Uo*(T\T03)2concentration be no more than about 0.4M. Acknowledgment
The assistance of D. G. Bouse and L. C. Neil in performing much of the experimental work is gratefully acknowledged. literature Cited
f l I Adams. W. H.. Fowler. E. B.. Christenson. C. W..IND. ENC. CHEM.52, 55 (1960). ‘ (2) Alter, H. W.,Codding, J. W., Jennings, H. S., Anal. Chem. 26, 1357 (1954). (3) Baker, L. C. W., Foster, G., Tan, W., Scholnuck, F., McCutcheon, T. P., J . Am. Chem. SOC. 77,2136 (1955). f4) Baker. L. C. LV.. Loev., B... McCutcheon, T. P., Zbid.,. 72,. 2374 ‘ ’(1950).‘ (5) Blanco, R. E., Watson, C. D., “Reactor Handbook,” R . B. Richards, S. M. Stoller, eds., Vol. 11, Chap. 3, Interscience, New York, 1961. (6) Ferris, L. M., U. S. At. Energy Commission Rept. ORNL3068, July 14, 1961. (7) Healy, T. V., J . Appl. Chem. (London) 8, 553 (1958). (8) Latimer, W. M., Hildebrand, J. H., “Reference Book of Inorganic Chemistry,” 3rd ed., p. 380, Macmillan, New York, 1951. (9) Maness, R. F., U. S. At. Energy Commission Rept. HW61662, September 1959. (10) Moore, R. L., Schulz, LV. W.,Walter, S. 5., Zbid., H W 28995, July 1953. (11) Nucleon& 18, 73 (1960). (12) Scott. F. E., Zabetakis, N. B., U. S. Bur. Mines Rept. ’ 3507,1956. (13) Stevenson, R. L., Smith, P. E., “Reactor Handbook,” R. B. Richards, S. M. Stoller, eds., Vol. 11, Chap. 4, Interscience, New York, 1961. \
I
RECEIVED for review September 16, 1960 ACCEPTEDOctober 24, 1961 ACS Northwest Regional Meeting, Richland, Wash., June 1960. Work performed under Contract No. At (45-1)-1350 between the U. S. .4tomic Energy Commission and General Electric Co.
