interchange of fission-product bromine with carrier bromine

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Interchange of FissionProduct Bromine with Carrier Bromine Andrew F. Stehney and Nathan Sugarman Citation: The Journal of Chemical Physics 20, 629 (1952); doi: 10.1063/1.1700504 View online: http://dx.doi.org/10.1063/1.1700504 View Table of Contents: http://scitation.aip.org/content/aip/journal/jcp/20/4?ver=pdfcov Published by the AIP Publishing Articles you may be interested in Comparisons of Neutron Cross Sections and Isotopic Composition Calculations for FissionProduct Evaluations AIP Conf. Proc. 769, 511 (2005); 10.1063/1.1945059 Fission Products Evaluation for the Selected Nuclei AIP Conf. Proc. 769, 378 (2005); 10.1063/1.1945027 Identification of μs isomers in fission products AIP Conf. Proc. 455, 694 (1998); 10.1063/1.57273 Fission product yields at intermediate energy AIP Conf. Proc. 447, 453 (1998); 10.1063/1.56722 Electrodialysis Unit for Fission Product Separation Rev. Sci. Instrum. 32, 857 (1961); 10.1063/1.1717534 This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitation.aip.org/termsconditions. Downloaded to IP: 161.6.156.35 On: Thu, 04 Dec 2014 02:36:53

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Page 1: Interchange of Fission-Product Bromine with Carrier Bromine

Interchange of FissionProduct Bromine with Carrier BromineAndrew F. Stehney and Nathan Sugarman Citation: The Journal of Chemical Physics 20, 629 (1952); doi: 10.1063/1.1700504 View online: http://dx.doi.org/10.1063/1.1700504 View Table of Contents: http://scitation.aip.org/content/aip/journal/jcp/20/4?ver=pdfcov Published by the AIP Publishing Articles you may be interested in Comparisons of Neutron Cross Sections and Isotopic Composition Calculations for FissionProductEvaluations AIP Conf. Proc. 769, 511 (2005); 10.1063/1.1945059 Fission Products Evaluation for the Selected Nuclei AIP Conf. Proc. 769, 378 (2005); 10.1063/1.1945027 Identification of μs isomers in fission products AIP Conf. Proc. 455, 694 (1998); 10.1063/1.57273 Fission product yields at intermediate energy AIP Conf. Proc. 447, 453 (1998); 10.1063/1.56722 Electrodialysis Unit for Fission Product Separation Rev. Sci. Instrum. 32, 857 (1961); 10.1063/1.1717534

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Page 2: Interchange of Fission-Product Bromine with Carrier Bromine

THE JOURNAL OF CHEMICAL PHYSICS VOLUME 20, NUMBER 4 APRIL, 1952

Interchange of Fission-Product Bromine with Carrier Bromine* ANDREW F. STEHNEVN

Argonne National Laboratory, Department of Chemistry and Institute for Nuclear Studies University of Chicago, Chicago, Illinois

AND

NATHAN SUGARMAN Institute for Nuclear Studies, University of Chicago, Chicago, Illinois

(Received October 4, 1951)

Experiments on the interchange of the fission products 2.4-hr Br83 and 55.6-sec BrS7 with carrier bromine have been performed. Essentially the same degree of interchange is effected by the following chemical procedures: carrier added as BrOa- and reduced by H2S, carrier added as BrOa- and reduced by excess carrier Br-, and carrier added as Be to HCl and irradiated uranium metal dissolved.

INTRODUCTION

I N the study of the radiations and fission yield1 of 5S.6-sec Br87, some experiments were performed on

the extent of interchange of carrier bromine with Br87

using different carrier species and chemical procedures. Since it had been noted that the interchange of fission­product iodine with carrier iodine was not complete except under very special chemical conditions,2 it was thought that perhaps similar difficulties might be en­countered in the interchange of bromine.

Some indication of interchange difficulties of bromine was present in the work of Langsdorf and SegreS who observed that the recovery of tracer Br83 from the decay of Se83 in a solution containing macro quantities of SeOa= was incomplete when carrier bromine was added as Br and AgBr was precipitated. They found it necessary first to oxidize SeOa= to Seor with Brz before the chemical separation was complete. A pro­cedure was developed by Edwards, Gest, and Davies4

for the separation of Br83 from solutions containing macro-SeOa= in which complete interchange was effected by adding carrier BrOa-, and reducing the BrOa- to Br with H 2S. This H 2S procedure has been used subse­quently for the radiochemical analysis of bromine in fission,5 and in the study6 of the isomeric states of Se83•

In the experiments reported here, comparisons were made of the extent of interchange of carrier bromine with Br87 obtained by three different chemical pro-

* This document is based on work performed at the Argonne National Laboratory, Chicago, Illinois.

t Presented in partial fulfillment for the Ph.D. degree in the Department of Chemistry, University of Chicago.

t Now at the Argonne National Laboratory, Chicago, Illinois. 1 A. F. Stehney and N. Sugarman (to be published elsewhere). 2 Glendenin, Metcalf, Novey, and Coryell, Paper 279, National

Nuclear Energy Series (McGraw-Hill Book Company, Inc., New York, 1951), Vol. 9, Div. IV; Katcoff, Dillard, Finston, Finkle, Seiler, and Sugarman, Paper 141, ibid.

3 A. Langsdorf and E. Segre, Phys. Rev. 57, 105 (1940). • Edwards, Gest, and Davies, Paper 22, National Nuclear Energy

Series (McGraw-Hill Book Company, Inc., New York, 1951), Vol. 9, Div. IV.

cedures. The recovery of Br87 was found to be essentially the same when the radiobromine was separated by the H2S procedure, by solution of uranium metal in Hel in the presence of Br carrier, and by the use of BrOs­and excess Br carriers. Similar concordant results were achieved in the study of 2.4-hr Br83 where the time spent by the radioactive atoms in solution was much greater. It would appear from these experiments that complete interchange between carrier and fission­product bromine is effected, using carrier bromine as BrO" and Br, whereas the analogous carriers (plus periodate) do not achieve complete interchange for radioiodine.

INTERCHANGE STUDmS OF 55.6-SEC Br87

The reduction of Br03- with H2S, shown4 to give complete recovery of Brss, was used first in the inter­change study of 5S.6-sec BrS7. A SOO-mg sample of uranyl nitrate was irradiated in the "rabbit" of the Argonne Heavy-water Pile for 45 seconds, then trans­ferred and dissolved in 7 ml water containing an aliquot of standardized KBrOa solution and some KIOa. The solution was gassed with H 2S for 1 min, the minimum time necessary for complete reduction of the BrOs­to Bc. The Bc was oxidized to Br2 by addition of a heated solution containing 15 ml O.5M KMn04 and 5 ml 6M HNOa; simultaneously the 1- was oxidized1

to 10a-; and the excess H 2S was destroyed. The solu­tion was then poured into a distillation apparatus and the Br2 was distilled by heating the solution and passing air through it. This procedure is similar to that used by Strassmann and Hahn8 in their study of short-lived bromine activities in fission. The air stream containing Br2 was passed through an acid solution of Ag+ and Fe++ for the precipitation of AgBr. Trial runs with BrOs- absent in the original solution showed that neither h nor H 2S was being carried in the air stream, since no precipitate formed in the Ag+-Fe++ solution.

6 Glendenin, Edwards, and Gest, Paper 232, National Nuclear 7 R. K. McAlpine and B. A. Soule, Prescott and Johnson's Energy Series {McGraw-Hill Book Company, Inc., New York, Qualitative Chemical Analysis (D. Van Nostrand and Company, 1951), Vol. 9, Div. IV. Inc., New York, 1933), p. 550. •

8 J. R. Arnold and N. Sugarman, J. Chem. Phys. 15, 703 (1947). 8 F. Strassmann and O. Hahn, Naturwiss. 28 817 (1940).

629

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Page 3: Interchange of Fission-Product Bromine with Carrier Bromine

630 A. F. STEHNEY AND N. SUGARMAN

TABLE I. Interchange experiments on 55.6-sec BrB?

Fission product Experiment isolated

Activity. elm XlO-'

Activity ratio Br87/Ba l3O

H 2S reduction procedure-500 mg uranyl nitrate, BrO,- carrier, H 2S reduction

1 B~ 7.n 3.~ Ba139 2.11

2 BrB7 7.60 3.35 Ba139 2.27

3 BrB7 7.99 3.43 Ba" 9 2.33

Average activity ratio=3.49±0.13a

Uranium metal procedure-200 mg uranium metal dissolved in HCI containing Br- carrier

4 BrB7 8.57 3.58 Ba139 2.39

.5 BrB7 9.00 3.91 Ba139 2.30

Averageactivity ratio=3.75±0.17a

BrO,--Br- procedure--500 mg uranyl nitrate, BrO,- and excess Bc carriers

6 BrB7 9.34 3.79 Ba139 2.46

7 BrB7 9.75 3.66 Ba139 2.66

8 Br87 5.90 3.71 Ba139 1.59

9 BrB7 7.56 4.25 Ba'" 1.78

10 BrB7 8.27 3.32 Ba139 2.49

11 BrB7 10.2 3.70 Ba139 2.76

Average activity ratio=3.74±0.19a

Ilo Mean deviation from average value.

The AgBr precipitate was filtered through a filter paper disk in a Hirsch funnel, washed with water, alcohol, and ether, and mounted on a cardboard card for ac­tivity determination. After the counting was com­pleted, the filter paper disk was removed from t}le mounting card, dried in an oven at 110°C for 10 mm, and weighed to determine the chemical yield of the bromine carrier.

Several determinations of Br87 activity were also made by irradiating uranium metal, a strongly reducing medium in which the fission-product bromine might be expected to be in a reduced state, and thus would interchange readily with carrier Br when the metal is dissolved in HCI containing Br. This procedure is analogous to that used on iodine by Katcoff et al.2 in their determination of the fission yield of 6.7-hr 1135,

and by Stanley and Katcoff9 in their work on the fission yield of 86-sec P36. A 200-mg sample of uranium was irradiated for 45 sec and then dissolved in dilute HCI containing standardized Br carrier and some 1- carrier. The small amount of oxide remaining in the solution was dissolved by the addition of 1 ml 6M HNOa. Attempts to dissolve the uranium metal quickly in H 2S04 or H aP04 were unsuccessful, and HNOa was not desirable because of t~e possible oxidation of radiobromine dur-

9 C. W. Stanley and S. Katcofi, J. Chern. Phys. 17, 653 (1949).

ing the solution process. The permanganate oxidation­distillation procedure was used for the separation of bromine, and special pains were taken to prevent the distillation of Ch along with Br2; namely, the use of a minimum quantity of HCI to dissolve the uranium (1 ml 6N Hel in 4 ml solution) and a preliminary CCl4

extraction of the Br2 after adding only a slight excess of KMn04. The bromine was extracted into NaHSOa solution and then reoxidized with HNOa- KMn04 solution, after which the distillation was carried out as in the H 2S-reduction procedure. The method was tested for chlorine interference and no precipitate was found in the Ag+- Fe++ solution when no Br carrier was added.

The third chemical procedure used was the reduction of BrOa- carrier with excess Br and the subsequent oxidation of the remaining Br with KMn04. In this 'procedure, 500 mg of irradiated uranyl nitrate was dis­solved in a solution containing 5 ml 6M H 2S04 and 4 ml O.05M KBr, then 1 rnl O.OIM KBr03 was added. After stirring for 15 sec, 1- carrier was added, followed by 15 ml O.5M KMn04. The distillation procedure was then performed. The 1- carrier addition was delayed to ensure the reduction of Br03- by Br.

Activity measurements were started on the isolated bromine samples 3 to 4 minutes after the end of the irradiation. Since much of the 55.6-sec Br87 had dis­integrated during this time interval, thick absorbers were used to distinguish the hard {3- and /'-radiations1

of Br87 from the relatively weaker radiationslO of 3.00-min Br85. Under these conditions only the 55.6-sec activity and a much less intense component of about 32-min half-life (Br84) were observed in the decay curves.

Since only one determination of Br87 was made for each irradiation because of the short half-life of Br87, , . the activity of Br87 was compared with that of 85-mm Bal39 from the same irradiation. The ratio of the activity of Br87 to Bal39 is then a measure of the radio­chemical yield of Br87. Extra samples of uranyl nitrate were included in each irradiation for the isolation of duplicate samples of barium activity, which was done by the HCl-ether procedure given by GlendeninY The activities of Br87 and Bal39 were each measured under standard conditions. The results of these measurements are given in Table I. Column 3 gives the activity of the fission product denoted in column 2 measured with a standard absorber, calculated to the end of the irradia­tion and corrected for chemical yield. The activity of , . the Br87 was measured through 1029 mgjcm2 of alumI-num absorber. The activity of Ba1a9 was measured through zero or 47.6 mgj cm2 of aluminum absorber and calculated to zero total absorber. The ratio of the activity of Br87 to that of Bal39 in each experiment is

10 N. Sugarman, J. Chern. Phys. 17, 11 (1949). . 11 L. E. Glendenin, Paper 288, National Nuclear Energy Ser!es

(McGraw-Hill Book Company, Inc., New York, 1951), Vol. 9, Dlv. IV.

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Page 4: Interchange of Fission-Product Bromine with Carrier Bromine

FISSION-PRODUCT BROMINE 631

given in column 4; the constancy of this ratio is a measure of the reproducibility of the interchange of Br87 with carrier bromine.

An examination of the activity ratios of Table I shows that the interchange effected by all three chem­ical procedures is the same within the determined pre­cision of about 5 percent. Since the procedure using metallic uranium would in principle be expected to provide complete interchange of Br87 with carrier, it appears that the other two procedures also give com­plete interchange.

INTERCHANGE STUDIES OF 2.4-HR Br83

Studies of the interchange of 2.4-hr Br83 with carrier bromine were made by the H 2S reduction and the BrOa-Be procedures to see if the formation of Br83

from the decay of the 25-min Se83 and 67-sec Se83m

parents leads to chemical states that are not inter­changeable with carrier bromine in these procedures. Although it had now been established that 55.6-sec Br87

interchanges to the same extent in each of these pro­cedures, it was possible that some difficulty might be encountered in the case of Br83 because of the ap­preciable half-life of the parent species, and the length of time the radiobromine existed in solution before the radiochemical analysis.

In these experiments, the results of the two methods were compared directly, since the half-life of Br83 is long enough to allow for several analyses from the same solution of irradiated uranyl nitrate. Thus, it was not necessary to analyze for Ba 139 and to compare the bromine activities with those of Bal39 from the same irradiation, as was done in the case of Br87. Two ex­periments were performed in which uranyl nitrate was irradiated in the Argonne Graphite Pile and dissolved two to three hours later and a stock solution prepared. Aliquots were taken for bromine analvsis after a wait of 3 hr or more from the end of the irr;diation, to allow for the decay of the 25-min Se83 parent. In each case the sample was mounted as AgBr and the decay was followed for 3 half-lives. Corrections for chemical yield and decay were made to compare the activity recovered by each procedu·re. The results are given in Table II.

In the entries designated "H2S, Extract," the an­alyses were performed according to the procedure given for fission-product bromine by Glendenin et al. 6 Carrier

TABLE II. Interchange experiments on 2.4-hr. Br83.

Experi­ment

2

Procedure

H2S, Extract Be, Extract

H.S, Extract Be, Extract H2S, Sweep, NaHSOa Be, Sweep, NaHSOa

Activity. Re<:overy,a. elm %

13600 100 13000 96

6900 100 6520 95 6820 99 6660 96

a Percent recovery based on IIH2S. Extract" set equal to 100.

BrOa- was reduced for 5 min by H 2S to Be, and the bromine was subjected to several cycles of oxidation and reduction, using KMn04 for oxidation and NH20H . HCI or NaHSOa for reduction. The "Be, Extract" experiments were made in the same way except that the BrOa- carrier was reduced by excess Be before the oxidation-reduction cycles. The "H2S, Sweep, NaHSOa" and "Br-, Sweep, NaHS03" experiments were done by the distillation procedure used for Br87 except that the Br2 was absorbed in 15 ml of O.OIM NaHSOa instead of the Ag+- Fe++ solution. The bisulfite solution was acidified with 1 ml of 6M HNOa and boiled for 1 min to expel S02 before the precipitation of AgBr.

A comparison of the data of Table II shows that the activity of Br83 recovered from the reduction of BrOa­by H 2S is consistently about 4 percent higher than that recovered from the reduction of BrOa- by excess Be. If this difference is truly significant of more complete interchange in the H 2S-reduction procedure, then the reason it was not noted in the Br87 interchange experi­ments may be due to the larger scatter of the values in those experiments.

SUMMARY

The experiments on the interchange of fission-pro­duct Br87 and Br83 with carrier bromine show that there is no apparent difficulty in achieving interchange. There is, apparently, some significant difference between the chemistry of bromine and iodine such that using the analogous chemistry for iodine complete interchange is not effected.

It is a pleasure to acknowledge the assistance given to one of us (A. F. S.) by the Atomic Energy Commis­sion in the form of a predoctoral fellowship.

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