Removal of Actinides from Nuclear FuelReprocessing

38 Pages·2012·1.78 MB·English

1 -
ARH-SA-217
Qt - 96-09/3 - - /3
Removal of Actinides from
Nuclear Fuel
Reprocessing
Waste Solutions with
Bidentate
Organophosphorus
Extractants
Wallace W. Schulz
Lyle D. McIsaac
August 1975
Prepared for the U.S. Energy Research
and Development Administration
Under Contract E(45-1)-2130
Atlantic Richfield Hanford Company
Richland.Washington 99352
ARA
/,
*ASTER
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Atlantic Richfield Hanford Company
Richland, Washington 99352
A.
.'
NOTICE
THIS REPORT WAS PREPARED AS AN ACCOUNT OF WORK SPONSORED BY THE
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ED-9300-090.2 (1-75)
ARH-SA-217
REMOVAL OF ACTINIDES FROM NUCLEAR FUEL
REPROCESSING WASTE SOLUTIONS WITH BIDENTATE
ORGANOPHOSPHORUS EXTRACTANTS
Wallace W. Schulz
NOTICC
This report was prepared as an account of work
• Chemical Technology Laboratory sthpoensoUrend it e dby S tthaeteUsn intoetdtShteatesUnGiotevedrnmSentat.te s ENenietihgeyr
Research Department Research and Development Administration, nor any of
their employee, nor any of their contractors.
Research and Engineering Division swuabrrcaonntytr, aecxtpor/e, sosr or tihmepiruede,mp0lo,yeaesssu,memsaakneys laengayl
Atlantic Richfield Hanford Company liability or responsibility for the accuracy, completeness .
or usefulness of any inforrnation, apparatus, product or
Richland, Washington pinrforciengses pdriisvcaltoesleydo,w onre rdeprrieghstes.nts that its use would not
and
Lyle D. McIsaac
Radiochemistry Section
Chemical Research and Engineering Branch
Allied Chemical Corporation
Idaho Falls, Idaho
August 1975
To be presented at the
4th International Transplutonium Element Symposium
Baden Baden, West Germany
September 13-17, 1975
0
DISTRIBUTION OF. THIS DOCUMENT IS UNLIMITED
ARH-SA-217
ii
TABLE OF CONTENTS
Page
iii
ABSTRACT .
.
LIST OF FIGURES . . . . . . . . . . . . . . . . . . . iv
LIST OF TABL,ES . . . . . . . . . . . . . . . . . . . . iv
INTRODUCTION . . . . . . . . . . . . . . . . . . . . . 1
CHARACTERISTICS OF BIDENTATE ORGANOPHOSPHORUS
1 EXTRACTANTS . . . . . . . . . . . . . . . . . . : . 3 1
S Y N T H E S I S. . . . . . . . . . . . . . . . . . . . 3
AVAILABILITY AND C O S T. . . . . . . . . . . . . . 3
PURIFICATION . . . . . . . . . . . . . . . . . , 4
7
PROPERTIES . . . . . . . . . . . . . . . . . . .
Extraction Mechanisms . . . . . . . . . . . 7
Equilibrium Distribution Data . . . . . . . 8
Solubility in Aqueous Solutions . . . . . . 12
Radiolytic Behavior . . . . . . . . . . . . 14
PROPOSED PLANT-SCALE APPLICATIONS OF BIDENTATE
EXTRACTANTS . . . . . . . . . . . . . . . . . . . . 16
HANFORD PLUTONIUM RECLAMATION FACILITY . . . . . 16
. . . . . . . . . 21
IDAHO CHEMICAL PROCESSING PLANT
OTHERS . . . . . . . . . . . . . . . . . . . : . 24
SUMMARY AND EVALUATION . . . . . . . . . . . . . . . . 25
25
ACKNOWLEDGMENTS . . . . . . . . . . . . . . . . : . .
26
R E F E R E N C E S. . . . . . . . . . . . . . . . . . . . . .
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iii ARH-SA-217
ABSTRACT
The neutraZ bidentate organophosphorus reagents DBDECMP
(dibutyZ-N,N-diethyZearbamyZmethyZenephosphonate) and its
dihezyZ. anaZogue DHDECMP are cand€date eztractants for
removaz of actinides from certain acidic waste streams .
produced at the U. S..ERDA Sanford and Idaho FaZZs sites.
Various chemicaZ and physicat properties ineZuding ava€Za-
cost, purification, aZpha radiotybis, and aqueous
b€Zity,
phase solubility of DBDECMP and DHDECMP are reviewed. A
conceptual flowsheet employing a 15% DBDECMP (or DHDECMP)-
CCZ 4 extractant for removat (and recovery) of Am and Pu from
Hanford's PZutonium RecZamation Facitity acid waste stream
(CAW Botution) was suecessfuZZy demonstrated in Zaboratory-
scaZe mixer-settZer tests; this extraction scheme can be
.used to produce an actinide-free waste. A 30% DBDECMP-xylene
fZoesheet is being tested at the Idaho FaZZs site for removeZ
of U, Np, Pu, .and Am from Idaho Chemical Processing Plant
first-cyete high-ZeveZ raffinate to produce an actinide-free
(<10 nCi atpha activity/gram) waste.
iV ARH-SA-217
LIST OF FIGURES
FIGURE EXTRACTION OF AMERICIUM BY PURIFIED AND
1 TECHNICAL-GRADE DBDECMP
FIGURE 2 EQUILIBRIUM DBDECMP EXTRACTION OF Am(111) AND
Pu(IV) FROM HN03 SOLUTIONS
DBDECMP PROCESS FLOWSHEET FOR RECOVERY OF
FIG.URE 3
AMERICIUM AND PLUTONIUM FROM HANFORD CAW
SOLUTION
FIGURE 4 CONCEPTUAL PROCESS FLOWSHEET FOR REMOVAL OF
ACTINIDES FROM ICPP WASTE SOLUTION
LIST OF TABLES
TABLE TYPICAL COMPOSITION.OF HANFORD AND ICPP
I ACTINIDE WASTES
TABLE 11 EXTRACTION OF SELECTED METAL IONS BY DBDECMP.
AND DHDECMP SOLVENTS.
TABLE 111 SOLUBILITY OF DBDECMP· IN VARIOUS AQUEOUS
SOLUTIONS
TABLE IV ALPHA RADIOLYSIS OF DHDECMP SOLUTIONS
r
- ARH-SA-217
REMOVAL OF ACTINIDES FROM NUCLEAR FUEL
' REPROCESSING WASTE SOLUTIONS WITH BIDENTATE
ORGANOPHOSPHORUS EXTRACTANTS
INTRODUCTION
The biological hazards and long half-lives of the
actinide elements make them of special importance in proper
management of. nuclear waste solutions. Potential advantages
and simplifications which might accrue from partitioning
these wastes into an actinide and a nonactinide fraction
have been cited by several· authors.[1-31 Transuranium-
contaminated·solid wastes have been defined[1,4] as those
contaminated with greater than 10 nei/gram of certain alpha-
emitting radionuclides of lon4 half-life and high specific
radiotoxicity. Claiborne[2] has noted the desir'ability of '
reducing the long-term (>1000 y) hazard potential of high-
level wastes to about 5% of that for pitchblende mineral on
the basis of hazard indices. '
Aqueous waste solutionsgenerated in present-day
schemes for reprocessing both irradiated and nonirradiated
(e.g., Pu scrap· recovery) nuclear fuels contain relatively
high doncentrations of nitric acid. From such solutions
common monodentate neutral organophosphorus extractants such
as TBP (tri-n-butylphosphate) and DBBP (dibutylbutylphospho-
nate)-extract Pu(IV), Np(IV), and U(VI) very well but do not
exttact trivalent americium and curium. These monodentate
reagents will, however, extract Am3+ and Cm 3+ reasonably
well from low-acid, highly salted solutions. [Such feed-
stock is employed, as described more fully later, in the
Hanford DBBP Am-extraction process.] Solvent extraction
processes which use HDEHP [bis(2-ethylhexylphosphoric acid)]
2 ARH-SA-217
as the extractant have been devised both in,the United
States [5] and in Germany[6] for recovery of americium and
curium from nuclear waste solutions previously adjusted to
PH's 21.
The great advantages of reagents which could be used
for solvent extraction of +3 as well as +4 and +6 actinides
from strong HN03 solutions were recognized early on.
Siddall in the 1960's synthesized various methylene diph6s-
0 0
" 11
phonites [(RO-) 2P-CH 2-P (-OR) 2], carbamylphosphonates
00
[(RO-)2$-C11 -N(-R)2] and carbamylmethylenephosphonates
00
[ (RO-) 2P" - C H 2 1-1C-N(-R) 2] and investigated their ability to
extract. Am 3+, Ce 3+, pm 3+, and HNO) from 0.1 to 12M HNO 3
solutions. His:favorable results[7,81 led Siddall to sug-
gest such bidentate extractants could be used to remove
trivalent ·actinides and lanthanides from high-level Purex
process waste; this idea was eventually patented.[91
Work is currently in progress at both the U. S. Energy
- Research and Development Administration (ERDA) Hanford and
Idaho Falls sites to extend Siddall's pioneering research
with bidentate organophosphorus extractants. Our objective
is to :develop and demonstrate practical bidentate extraction
precesses for plant-scale removal and recovery of americium,
plutonium, and other actinides from certain acidic nuclear
wastes generated at these sites. This paper summarizes the
current status of our research including accomplishments and
unsolved problems.
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