RECENT ADVANCES IN TECHNETIUM RECENT ADVANCES IN TECHNETIUM ENVIRONMENTALLY FOCUSED ENVIRONMENTALLY FOCUSED

STUDIESSTUDIES

RUSSIAN ACADEMY OF SCIENCES

A.N. FRUMKIN INSTITUTE OF PHYSICALCHEMISTRY AND ELECTROCHEMISTRY

31/4 Leninsky prospect, Moscow , 119991, RUSSIA, Fax: 7-495- 335-17-78

IST-2008 , Port-Elizabeth 7-10 Oct. 2008, South Africa

KONSTANTIN E. GERMAN

2008 – The Year of Tc2008 – The Year of Tc

Plan of presentationPlan of presentation

Tc in the environments – sources, Tc in the environments – sources, history and modern trends.history and modern trends.

Tc in acidic and basic HLW.Tc in acidic and basic HLW. Different methods of Tc HLW Different methods of Tc HLW

treatment (insoluble residues, liquid treatment (insoluble residues, liquid wastes discharcges, in-tank wastes discharcges, in-tank storage, vitrification, plants storage, vitrification, plants decomissioning, transmutation decomissioning, transmutation projects )projects )

Chemical species of Tc in waste Chemical species of Tc in waste and environmentand environment

Physico-chemical aspects of Tc Physico-chemical aspects of Tc (colloids and nanoparticles)(colloids and nanoparticles)

Saying “Tc” here we mean Saying “Tc” here we mean Tc-99gTc-99g

-emitter-emitter (T(T½½ == 2*102*1055 y y)) accumulating with ~6% yeild accumulating with ~6% yeild by U, Np or Pu fission = 1kgby U, Np or Pu fission = 1kg//tt--U U

Tc concentration in reprocessing solutionsTc concentration in reprocessing solutions ~~ 5-80 5-80 mg/Lmg/L

Oxydation statesOxydation states: : 00, +1, + 2, +2.5, , +1, + 2, +2.5, +3+3, , +4 +4 , , +5,+5, +6, +6, +7+7

Insoluble Insoluble -phases = Tc metal-phases = Tc metal VolatileVolatile as: as: TcTc22OO77, HTcO, HTcO44 at T>100 at T>100ooCC

TcO2 and Tc-metalTcO2 and Tc-metal (T>350(T>350ooC+OC+O22); );

MTcOMTcO4 4 for M = Na, K, Cs atT>600for M = Na, K, Cs atT>600ooC = C = vitrificationvitrification??

In In WATERWATER : Extrimly high migration rate : : Extrimly high migration rate : TcOTcO44--

Technetium in the Technetium in the environment in 1986, environment in 1986, NEA_TDB –RARD in 1999NEA_TDB –RARD in 1999

An exceptional issue of “Technetium in the environment” in 1986 although made of An exceptional issue of “Technetium in the environment” in 1986 although made of independent parts was a complete presentation of all the pre-Chernobyl ideas and independent parts was a complete presentation of all the pre-Chernobyl ideas and results [1]. 13 years later an excellent review of NEA-TDB summed up the chemical results [1]. 13 years later an excellent review of NEA-TDB summed up the chemical thermodynamics of Tc [2]. Time passed being characterized with the controversy of thermodynamics of Tc [2]. Time passed being characterized with the controversy of nuclear industry present and future status, drastic for Tc-99 originating mostly as the nuclear industry present and future status, drastic for Tc-99 originating mostly as the uranium fission product. The definite stop in nuclear development would fix the uranium fission product. The definite stop in nuclear development would fix the further accumulation but now is clearly not the case and we appreciate the authors further accumulation but now is clearly not the case and we appreciate the authors were continuing efforts in Tc environmentally focused sciences. Several main were continuing efforts in Tc environmentally focused sciences. Several main directions could be drawn out: firstly those dealing with already accumulated Tc [3-directions could be drawn out: firstly those dealing with already accumulated Tc [3-5], then, focused on the construction of the migration barriers at the depositories [6-5], then, focused on the construction of the migration barriers at the depositories [6-9] and finally examining the Tc in vitrification. The understanding of Tc interaction 9] and finally examining the Tc in vitrification. The understanding of Tc interaction with microbial extremofils was importantly advanced [10-11]. The review is devoted with microbial extremofils was importantly advanced [10-11]. The review is devoted to these and numerous other results of environmental importance.to these and numerous other results of environmental importance.

““Technetium in the Environment” (Proc. CEC-RPP – SERE CEA Seminar - Cadarache, Technetium in the Environment” (Proc. CEC-RPP – SERE CEA Seminar - Cadarache, 1984), Eds.: G. Desmet and C. Myttenaere, Elsevier Publishers, L&N-Y. (1986).1984), Eds.: G. Desmet and C. Myttenaere, Elsevier Publishers, L&N-Y. (1986).

Rard J.A., Rand M.H., Anderegg G., Wanner H., Chemical thermodynamic of technetium. Rard J.A., Rand M.H., Anderegg G., Wanner H., Chemical thermodynamic of technetium. Eds. Sandino Amalia M., Osthols E. NEA (1999) Elsiever Publ. Amsterdam.Eds. Sandino Amalia M., Osthols E. NEA (1999) Elsiever Publ. Amsterdam.

Technogenic sources of Tc to the Technogenic sources of Tc to the environmentsenvironments Accumulation of Accumulation of 9999Тс Тс in nuclear industry in nuclear industry = 8 = 8

tonton//yearyear

Discharge sources ofTcDischarge sources ofTc: : Explsions in atmosphere Explsions in atmosphere 180180 TBq (Tera=10 TBq (Tera=101212) ) = =

490 490 kgkg Тс Тс Chernobyl accident Chernobyl accident = 82 = 82 kgkg

NPPNPP 1М 1МBqBq / /yearyear 1000 МВт (электр.), т.е. : 1000 МВт (электр.), т.е. : В 2000 году все АЭС мира выделили В 2000 году все АЭС мира выделили 350 МБк Тс = 160 г 350 МБк Тс = 160 г Заводы по переработке обл. топлива Заводы по переработке обл. топлива 10% от выбросов ЯТЦ 10% от выбросов ЯТЦ Завод Селафилд в Ирландское мореЗавод Селафилд в Ирландское море 1952-1986 гг : 770 ТБк Тс 1952-1986 гг : 770 ТБк Тс

= 1200 кг Тс = 1200 кг Тс Завод мыс Аг (Франция) 1966 – 86 гг : 70 ТБк Тс = 100 кг Завод мыс Аг (Франция) 1966 – 86 гг : 70 ТБк Тс = 100 кг

ТсТс Заводы изотопного обогащения Заводы изотопного обогащения U:U: 90% от выбросов ЯТЦ 90% от выбросов ЯТЦ

4.104.101010 Бк Тс/год Бк Тс/год = 4,5 кг/год Тс = 4,5 кг/год Тс

(Газодиффузионный завод в ОАК РИДЖ: 1975-82 гг. 5-30 Ки Тс = (Газодиффузионный завод в ОАК РИДЖ: 1975-82 гг. 5-30 Ки Тс = 0.3 - 2 кг Тс/год, 1982-1989 гг. 0.02 – 0.03 кг Тс/год, 1990 – 0.2 кг, 0.3 - 2 кг Тс/год, 1982-1989 гг. 0.02 – 0.03 кг Тс/год, 1990 – 0.2 кг, 1992 – 1 кг в связи с началом демонтажа оборудования) 1992 – 1 кг в связи с началом демонтажа оборудования)

Different approaches to Different approaches to handling the Tc-radwasteshandling the Tc-radwastes

Dilution in natural watersDilution in natural waters ( (only two isotopes only two isotopes 33H H andand 9999TcTc) ) (UK(UK, , Russia -hystoricRussia -hystoric))

Underground injection HLW, MLWUnderground injection HLW, MLW ( (Tomsk, Tomsk, KrasnoyarskKrasnoyarsk,, Dimitrovgrad Dimitrovgrad))

Tank farms storageTank farms storage ( (military wastes, historic wastesmilitary wastes, historic wastes)) Vitrification of histric wastes, witrification of raffinatesVitrification of histric wastes, witrification of raffinates Metal formsMetal forms New venture formsNew venture forms Separation and storageSeparation and storage Separation ant transmutationSeparation ant transmutation

The 1995-2005 years were The 1995-2005 years were ТсТс marked by marked by severe confrontation of Norwegian “greens” severe confrontation of Norwegian “greens” with Sellafield authorities for B205-MAGNOXwith Sellafield authorities for B205-MAGNOX discharges into the Irish sea - discharges into the Irish sea - 180 180 kgkg-Тс/-Тс/yearyear

Тс-Тс-to-sea standard for Sellafieldto-sea standard for Sellafield

( B205 + EARP-B211 + THORP )( B205 + EARP-B211 + THORP ) – 19919955-200-20000 - 200 Т - 200 ТBqBq-Тс-Тс– 2002000-2000-2003 - 90 Т3 - 90 ТBkBk-Тс -Тс – TPPBrTPPBr - April - April 23-24 23-24 - - 20032003

B211 = 10 HLW tanksB211 = 10 HLW tanks 1050 1050 cub. m eachcub. m each : :5 tanks for5 tanks for “MAC”“MAC”

2 tanks– sludges2 tanks– sludges2 tanks - THORP2 tanks - THORP1 – empty in 20031 – empty in 2003

EARPEARP

Pollution of the North seaPollution of the North sea, , caused by Sellafield, UKcaused by Sellafield, UK))

Тс content Тс content

In the samples collected in 1999 - 2001In the samples collected in 1999 - 2001 water = 0.01- 0.07 Bq/Lwater = 0.01- 0.07 Bq/L

algae = 510 Bq/kg algae = 510 Bq/kg ( ! )( ! ) lobsters = 33 - 42 Бк/кг lobsters = 33 - 42 Бк/кг ( ! )( ! )

(acc. to (acc. to Bellona,Bellona, Norvege) Norvege)Risks of refused distribution of Norvege Risks of refused distribution of Norvege

sea-foodssea-foods

Tc discharges in 2002-2005

The sum of total-beta activity (excluding tritium) from all nuclear installations has fallen significantly over the past 15 years. Total emissions are dominated by discharges from the nuclear fuel plant at Springfields and to a lesser extent the reprocessing plant at Sellafield. The two installations together contribute approximately 98 % of the overall discharges. The high, but decreasing total-beta discharges from Sellafield are mainly attributable to the radionuclide Technetium-99. The reduction of Sellafield’s total-beta discharges from 2002 to 2005 is a result of the significant reduction in Technetium-99 discharges, due to the vitrification process, since 1994 for oxide fuels and 2003, for magnox fuels. Discharge of Tc-99 to sea (primarily from treatment of stored Magnox wastes) has been reduced between 1994 and 2005.

The total beta discharges from Sellafield (2002: 112 TBq, 2003: 83 TBq, 2004: 73 TBq, 2005: 43 TBq) were previously mainly attributable to the radionuclide Technetium-99 (2002: 85 TBq, 2003: 37 TBq, 2004 14 TBq, 2005: 6,7 TBq ), for which abatement technology was installed in 2004. The reduction of Sellafield’s total beta discharges in 2005 is due to the reduction of Technetium-99 (2004 14 TBq, 2005: 6,7 TBq),

Tc releases in Europe

For other European facilities the annual Tc release is negligible

Mayak

Karachay lake

VVER

3*10-2

Tc behavior during the Tc behavior during the underground HLW storageunderground HLW storage

Pretreatment : рН + Pretreatment : рН + complexones + . . . complexones + . . .

Ingection into the sandy Ingection into the sandy levels – collectorslevels – collectors

Migration controlMigration control …………………………………………………………………………

……………………………………. . .. . . Tc sorption at the minerals Tc sorption at the minerals

and rocks was studied and rocks was studied beforebefore

Main conclusionsMain conclusions Тс(Тс(VII) has high migration VII) has high migration

mobility mobility Тс(Тс(IV) may form both IV) may form both

immobile TcO2 and immobile TcO2 and mobile complexes mobile complexes

Guerman K.E., Kosareva I.M., Peretroukhin V.F., Guerman K.E., Kosareva I.M., Peretroukhin V.F., Savushkina M.K., Egorov N.N., Kudryavtsev E., Savushkina M.K., Egorov N.N., Kudryavtsev E., Revenko Yu.A. ICEM'95. V.1. Cross-cutting Issues Revenko Yu.A. ICEM'95. V.1. Cross-cutting Issues and management of high-level waste and spent fuel.and management of high-level waste and spent fuel. (Eds.: S.Slate, Feizollahi, C.Creer), NY, 1995, p. 713 – 722 .(Eds.: S.Slate, Feizollahi, C.Creer), NY, 1995, p. 713 – 722 .

Tc speciation in simulated radioactive wastes Tc speciation in simulated radioactive wastes conditionned for the underground injections conditionned for the underground injections (1980-88, 1994, 2000)(1980-88, 1994, 2000)

TcOTcO44- - - is highly migrative- is highly migrative

Radiolyses in presence of Radiolyses in presence of organic components lead to organic components lead to the reduction of Тс(VII) to the reduction of Тс(VII) to TcTc((V, IV, III)V, IV, III)

Acetate complexes Acetate complexes Тс(Тс(V, IV, V, IV, III) exist but the data are III) exist but the data are scattered and the structure scattered and the structure not systematically studiednot systematically studied

Acetate complexes of Acetate complexes of Тс(Тс(III) III) could co-exist withTc(VII) .could co-exist withTc(VII) .

EXAFS ROBL_ESRFEXAFS ROBL_ESRF

4

3

2

1

0

Four

ier T

rans

form

Mag

nitu

de

543210

R + (Å)

experiment fit

-10

-5

0

5

10

k3 (

k)

141210864

k (Å-1

)

Russians experience of Tc separation and Russians experience of Tc separation and conversion (decl. avail.for CEA France conversion (decl. avail.for CEA France 1994-1997)1994-1997)

Spitsyn V.I., Kuzina A.F., Prokopchuk Yu. Z., Chepurkov G.Ya. , German K.E., Oblova Spitsyn V.I., Kuzina A.F., Prokopchuk Yu. Z., Chepurkov G.Ya. , German K.E., Oblova A.A.,A.A.,Kryuchcov S.V. Kryuchcov S.V. Preparation of technetium metal by thermal decomposition ofPreparation of technetium metal by thermal decomposition of tetrabutylammonium pertechnetate in inert gas atmospheretetrabutylammonium pertechnetate in inert gas atmosphere. . Report IReport IPCASPCAS, N-P-2907, , N-P-2907, 1983.1983.

Spitsyn V.I., Kuzina A.F., Prokopchuk Yu.Z., Chepurkov G.Ya., German K.E., Oblova A.A., Spitsyn V.I., Kuzina A.F., Prokopchuk Yu.Z., Chepurkov G.Ya., German K.E., Oblova A.A., Kryuchcov S.V., Dzekun E.G., Sokhina L.P. Kryuchcov S.V., Dzekun E.G., Sokhina L.P. Precipitation technology for technetium Precipitation technology for technetium separationseparation from radioactive wastesfrom radioactive wastes. Report Mayak/IPCAS- 1984.. Report Mayak/IPCAS- 1984.

Spitsyn V.I., Kuzina A.F., Prokopchuk Yu.Z., Chepurkov G.Ya., German K.E., Oblova A.A.,Spitsyn V.I., Kuzina A.F., Prokopchuk Yu.Z., Chepurkov G.Ya., German K.E., Oblova A.A., Kryuchcov S.V., Tzarenko A.F., Akopov G.A., Krinitsyn A., Kapitonov V.I., Galkin Kryuchcov S.V., Tzarenko A.F., Akopov G.A., Krinitsyn A., Kapitonov V.I., Galkin A.,Maksimenko A., Berezuk N., Mezentsev V.I. A.,Maksimenko A., Berezuk N., Mezentsev V.I. Technology of technetium recovery Technology of technetium recovery from radwastesfrom radwastes.Report Mayak /IPCAS/ Khlopin Radievy.Inst.,1985, N P-3171. 32 p..Report Mayak /IPCAS/ Khlopin Radievy.Inst.,1985, N P-3171. 32 p.

Spitsyn V.I., Kuzina A.F., Prokopchuk Yu.Z., Chepurkov G.Ya., Guerman K.E., Oblova Spitsyn V.I., Kuzina A.F., Prokopchuk Yu.Z., Chepurkov G.Ya., Guerman K.E., Oblova A.A.,Kryuchcov S.V., Kapitonov V.I., Mezentsev V.I. A.A.,Kryuchcov S.V., Kapitonov V.I., Mezentsev V.I. Improuvment of anion exchange Improuvment of anion exchange technetiumtechnetium recovery from radwastes using TBP as eluentrecovery from radwastes using TBP as eluent. Report Mayak -IPC AS. . Report Mayak -IPC AS. 1985, N P-3066 , 82 P.1985, N P-3066 , 82 P.

German K.E., Kuzina A.F., Spitsyn V.I. Patent: German K.E., Kuzina A.F., Spitsyn V.I. Patent: Method of technetium carbide preparationMethod of technetium carbide preparation. . USSR. Patent No 1258016, 1986.2 USSR. Patent No 1258016, 1986.2

Russian approach to Tc separation in PUREX included Russian approach to Tc separation in PUREX included (1980-1986): (1980-1986): extraction at the first extraction stage, back extraction at extraction at the first extraction stage, back extraction at the U-Pu separation stage, anion-exchange separation at the U-Pu separation stage, anion-exchange separation at QuatPhosBase AER, purification at VP-1AP-AER, QuatPhosBase AER, purification at VP-1AP-AER, denitrification with formic acid or Hdenitrification with formic acid or H22O-SH, O-SH, precipitation of KTcO4 or Rprecipitation of KTcO4 or R44NTcONTcO44 and its conversion to and its conversion to metal Tcmetal Tc

Conversion to metal: Conversion to metal: Search for the conditions Search for the conditions

(Ar-6%H2, gaz product (Ar-6%H2, gaz product evaquation, evaquation,

Products - volatile and Products - volatile and solid, solid,

Russ.Inorg. Chem-2002 -Russ.Inorg. Chem-2002 -47-No547-No5

MTcO4M =

Solubility in water at 25°C

Density g/ml

Association constant in water, L/M

Me4N+ 0.135 0.0050.096 [8]

1,67 -

Et4N+(2.5 0.7) x 10-2

1.24 x 10-2 at 20C 1,34 -

Pr4N+(8.7 0.2) x 10-3

7.8 x 10-3 [8] 1,26 2,6 0,4

Bu4N+(4.3 0.20) x 10-3

4.2 x 10-3 at 20C 1,17 15 3

Pent4N+ (7.9 0.2) x 10-4 1,12 27 5

Hex4N+ (7.1 0.5) x 10-5 1,07 40 5

Hept4N+ (8.8 0.8) x 10-6 1,03 52 5

p[(C4H9)4N]OH (aqueouse) [(C4H9)4NOH]p (aqueouse) (8) [(C4H9)4N]+

(aqueouse) + TcO4- (aqueouse) [(C4H9)4N]TcO4 (solide) (9)

[(C4H9)4NOH]p (aqueouse) + TcO4-(aqueouse)

[(C4H9)4NOH]p-1TcO4 (aqueouse) + OH- (10)HTcO4

H+ +TcO4- (TcKa)

TcKa/( TcKa + [H+]) = [TcO4

-] /([TcO4-]+ [HTcO4]) = [TcO4

-] /[Tc]tot

The TcKa was found equl to 4.02 M which is in very good agreement with [[i]]

[i] Ashley K.R., Ball J. R. Solvent extraction and ion exchange, 1994, 12(2), p.239-259.

Co-precipitation of Tc(VII) with BuCo-precipitation of Tc(VII) with Bu44NReONReO44 from 100 ml 1.0 M NaOH, [ TcOfrom 100 ml 1.0 M NaOH, [ TcO44

--] = 5*10] = 5*10-4-4 M, [ Bu M, [ Bu44NN++] ]

= 0.005 - 0.02 M, reagent = 0.1M NH= 0.005 - 0.02 M, reagent = 0.1M NH44ReOReO44

0

0.2

0.4

0.6

0.8

1

100 102 104 106 108 110

Total volume, %

Tc fractionremainedin the solution 0,02M Bu4N

0,01M Bu4N

0.005M Bu4N

V= +3%V= +3%

Tc oxides Tc oxides

TcTc22OO55- decomposition of - decomposition of

TcTc22OO55*nH*nH22O at 100O at 100ooCC

TcTc22OO55*nH*nH22O – gamma O – gamma

in NaOHin NaOH

TcTc44OO55*14H*14H22O hydrolisis O hydrolisis

of K3Tc2Cl8 of K3Tc2Cl8

TcTc44OO5 - 5 - thermolisis thermolisis

Tc Oxide

Parameters for innerelectrons (Tc3d3/2,5/2)

E(Tc) Half-width

1 Tc2O5256,6 1,8

2 Tc2O5*nH2O 256,0 1,7

3 TcO2255,2 1,8

4 TcO2*1.6H2O 255,4 2

5 Tc4O5*14H2O 255,9 1,8

6 Tc4O5

255,0 (0,4)253,6 (0,4)

(I1:I2=1:1.3)3.5

7 Tc2O7- volatile

Tc under HAW vitrification Tc under HAW vitrification conditions conditions

No stable Tc silicates were found before – but now we No stable Tc silicates were found before – but now we know about Tc sodalite although losing in structure know about Tc sodalite although losing in structure stability to cancrinite in presence of common nitratestability to cancrinite in presence of common nitrate

Pertechnetates are volatile at temp.Pertechnetates are volatile at temp. > 600> 600ooCC

Reduced Tc valence forms Reduced Tc valence forms –– Tc(IV) no interaction with silicatesTc(IV) no interaction with silicates Tc(0) no interaction with silicatesTc(0) no interaction with silicates

Tc separation before HAW vitrification is preferableTc separation before HAW vitrification is preferable

Methods for Tc separation from Methods for Tc separation from alkaline and neutral solutionsalkaline and neutral solutions

- Not easy when Tc species is different from Tc(VII)- Not easy when Tc species is different from Tc(VII) (Schroeder(Schroeder, 1996 - , 1996 - HanfordHanford: : treatment with Streatment with S22OO88 etc. etc.

EXTRACTIONKetones : Aceton,Methyl-ethyl-ketone,)ТPPBr/ТPAsBr/CCl4Polyglicoles

ChromatographyQuatPhosBase(KHL-Rad-Inst) +VP-1АP(IPCERAS) (= RAILEX) for technologyHPLC - DIONEX-AS11 (for anallyt separation from MoO4/I/Br/ClO4/TcO4)

Not a problem compared to acidic, quite efficient are several methods used in Russia in 1980-85

solidexsolidex TPPBrTPPBr ( (developed for HLWdeveloped for HLW B205-MAGNOX)B205-MAGNOX)

Properties of different reagents for Tc Properties of different reagents for Tc separation by (co-) crystallization or solidex separation by (co-) crystallization or solidex

technologytechnology

Тетрафениларсоний бромид Тетрафениларсоний бромид (Трибалат, Кузина)(Трибалат, Кузина)

Нитрон Нитрон (Кузина)(Кузина) Тетрафенилфосфоний Тетрафенилфосфоний

бромидбромид (BNFL) (совместимы с (BNFL) (совместимы с фосфатными стеклами)фосфатными стеклами)

Тетраалкиламмоний бромид / Тетраалкиламмоний бромид / перренат перренат (осадки (осадки совместимы с совместимы с боратными стекламиборатными стеклами, метод , метод опробован в 1982-85 совм. с ПО опробован в 1982-85 совм. с ПО Маяк, в 1995-97 определены Маяк, в 1995-97 определены оптимальные осадители, оптимальные осадители, которые рекомендованы КАЭ которые рекомендованы КАЭ Франции и ДЭ США)Франции и ДЭ США)

Table 4.1 Aqueous solubilities of technetium saltsPertechnetate cations Solubility at 25ºC, M

Cesium 1.60x10-2

Thallium 3.1x10-3

Tetrapropylammonium (8.70.2)x10-3

Tetrabutylammonium (4.3 0.2)x10-3

4.2x10-3 at 20CTetrapentylammonium (7.9 0.2)x10-4

Tetrahexylammonium (7.1 0.5)x10-5

Tetraheptylammonium (8.8 0.8)x10-6

Triphenylguanidinium (3.9 0.3)x10-3

Tetraphenylarsonium (4.0 0.2)x10-4

Some of these regents were also used forSome of these regents were also used for•Tc-Ion-selective electrode construction Tc-Ion-selective electrode construction

•Fiber sorbents productionFiber sorbents production

The SRS waste volumes (Table 2.4 of "Integrated Database Report - 1993: S.Spent Fuel and Radioactive Waste Inventories, Projections, and Characteristics,”] Tc-99 quantities (Table 2.11),

and Tc-99 concentrations calculated from these data

Volume, Tc-99, Ci [Tc-99], [Tc], Volume, Tc-99, Ci [Tc-99], [Tc], 10106 6 KdKd

liters Ci/liter liters Ci/liter g/liter total g/liter total

Liquid 61.4 1.68E+04 2.74E-03 Liquid 61.4 1.68E+04 2.74E-03 0.162 -0.162 -

Sludge 13.9 1.14E+04 8.20E-03 Sludge 13.9 1.14E+04 8.20E-03 0.483 30.483 3

Salt Cake 53.8 2.78E+03 5.17E-04 0.0305 Salt Cake 53.8 2.78E+03 5.17E-04 0.0305 0.2 0.2

Overall waste 129.1 3.098E+04 2.40E-03 0.141 Overall waste 129.1 3.098E+04 2.40E-03 0.141 - -

Question to be answered : Which components absorb Tc with Kd higher than 3 and are Question to be answered : Which components absorb Tc with Kd higher than 3 and are resistant to leaching?resistant to leaching?

Reducing Grout

Tank Equipment (e.g. slurry pump)

CLSM

2000# grout

Isolation Valve

Capped

Grout fill

Underground line (valve closed)

Underground line (line capped)

Service Line (e.g. steam, air)

Formwork (typ)

Diversion Box

Risers (typ)

SRS TYPE IV HIGH LEVEL WASTE TANK

Reducing Grout

Tank Equipment (e.g. slurry pump)

CLSM

2000# grout

Isolation Valve

Capped

Grout fill

Underground line (valve closed)

Underground line (line capped)

Service Line (e.g. steam, air)

Formwork (typ)

Diversion Box

Risers (typ)

SRS TYPE IV HIGH LEVEL WASTE TANK

9999Tc concentrations found in Tc concentrations found in various tank sludgesvarious tank sludges at at SRSSRS

Tank Tank NumberNumber

[Tc-99], [Tc-99], mCi/g mCi/g dried dried solidssolids

ReferenceReference

1717 0.4620.462 d'Entremont et d'Entremont et al. 1997al. 1997

20, white 20, white solidssolids

0.340.34 d'Entremont d'Entremont and Hester and Hester 19961996

20, brown 20, brown solidssolids

0.940.94 d'Entremont d'Entremont and Hester and Hester 19961996

4242 0.220.22 Hay 1999Hay 1999

5151 0.210.21 Hay 1999Hay 1999

88 0.220.22 Hay 1999Hay 1999

1111 0.340.34 Hay 1999Hay 1999

The discovery of The discovery of relatively high relatively high 9999Tc Tc concentrations in concentrations in inorganic mineral inorganic mineral

sludge heels taken from sludge heels taken from some tanks at the US-some tanks at the US-DOE Savannah River DOE Savannah River

Site (SRS) has Site (SRS) has prompted investigations prompted investigations

of Tc uptake from of Tc uptake from alkaline highly active alkaline highly active waste (HAW) by solid waste (HAW) by solid

adsorbentsadsorbents

Sludge components as Sludge components as carriers for Tc(VII) and carriers for Tc(VII) and

Tc(IV)Tc(IV)

. SO D IU M O XALAT E .N a 2C 2O 4

. C R YO LIT E .N a 3AlF6

ALU MIN O SILIC AT ESC AN C R IN IT E

SO D ALIT E

W H IT E SO LID S

. PLAT IN U M G R O U P .MET ALS

R h, R u, Pd

MET AL H YD R O XID ES(Fe, C r, Mn)(O )(O H )

B R O W N SO LID S

SOLID SLUDGE COM PONENTS

TiO2 was also tested

Study of Tc uptake with Study of Tc uptake with AluminosilicatesAluminosilicates under oxidizing under oxidizing

conditions at 70-130conditions at 70-130ooCC

TcOTcO44-- is too large is too large

and therefore it is and therefore it is excludedexcluded from the from the

aluminosilicate aluminosilicate structure in both structure in both

cancrinite and cancrinite and sodalitesodalite

Solution Formed solid Kd

10-3-10-5M Tc0.2-5M NaOH

0.5-5 M NaNO3Cancrinite less 1

10-3-10-5M Tc0.2-5M NaOHNaNO3 free

Sodalite less 1

Literature data have demonstrated the possibility of Literature data have demonstrated the possibility of ClOClO44

-- and MnO and MnO44-- co-crystallisaton with aluminosilicates : co-crystallisaton with aluminosilicates :

purple Na8[AlSiO4]6(MnO4)2 (Weller,1999 etc.)

OUR EXPERIMENTS on TcOOUR EXPERIMENTS on TcO44- - (reaction: NaAlO2+Na2SiO3+NaOH)

Case of Aluminosilicates Case of Aluminosilicates formed in concentrated formed in concentrated

Tc(VII) solutionTc(VII) solution [Tc] = 0.2 M[Tc] = 0.2 M in NaNO3 solutions - cancrinite in NaNO3 solutions - cancrinite in NaNO3-free solutions - sodalitein NaNO3-free solutions - sodalite Although NMR spectrum Although NMR spectrum

presented shift typical for presented shift typical for coordinated Tc(VII) its coordinated Tc(VII) its concentration is very lowconcentration is very low

Dissolution in NaHFDissolution in NaHF22 and LSC has and LSC has shown : [Tc] in solid cancrinite shown : [Tc] in solid cancrinite was 57 mg/kg ~ 100 times less was 57 mg/kg ~ 100 times less than in initial solution than in initial solution

Tc is excluded from the Tc is excluded from the aluminosilicate structurealuminosilicate structure

Fig. 1. NMR-99Tc spectrum of the aluminosilicate containing

57 mg-Tc/kg. Tc spectrum presents evidence for -30 ppm shift

characteristic of coordinated pertechnetate

Study of Tc uptake with Study of Tc uptake with AluminosilicatesAluminosilicates under under reducing reducing conditionsconditions

( (0.2M N0.2M N22HH55Cl, 1M NaNOCl, 1M NaNO33, , T T = 80= 8000С, t = 3 С, t = 3

d)d)

Precipitation ofcancrinite

Leaching conditions:

NaOHM

Tc yield, %

Leaching agent:

T, oC

Leaching yield , Tc, %

3 hour

1 day 10 days

2.0 18.9 1M NaOH 20 0.8 1 3.7

4.0 32 2M NaOH 20 0.8 1.2 2.0

2.0 25.2 0.1M NaOH + 0.25 M H2O2

60 25 26.9 27

2.0 18.9 0.1M NaOH + 0.5 H2O2

18 4 6.9 7

4.0 32 0.1M NaOH + 0.5 H2O2

18 6.5 6.9 11

Under reducing conditions Tc uptake is important Under reducing conditions Tc uptake is important

Tc(IV) in aluminosilicates is resistant to leachingTc(IV) in aluminosilicates is resistant to leaching

Study of Tc(VII) sorption Study of Tc(VII) sorption by crystalline TiOby crystalline TiO22

under oxidizing conditionsunder oxidizing conditions

Tc(VII) was sorbed by Tc(VII) was sorbed by TiOTiO22 from neutral from neutral solution with Ksolution with Kdd = 30 = 30 ml/g. ml/g.

However, the KHowever, the Kdd at at pH=10 was only 3.3 pH=10 was only 3.3 ml/gml/g

No affinity to Tc(VII) No affinity to Tc(VII) was noted for was noted for TiOTiO2 2 at at pH=12 and higherpH=12 and higher ..

Among the minerals tested

for Tc(VII) uptake, high-

density TiO2 was the most efficient

MST and Silicotitanates yet not tested ..?

Study of Tc uptake withStudy of Tc uptake with Na oxalateNa oxalate under under

oxidizing and reducing conditionsoxidizing and reducing conditions

Tc(VII) is excluded from the Na oxalate structure Tc(VII) is excluded from the Na oxalate structure under oxidizing conditions (Kd = 1-2)under oxidizing conditions (Kd = 1-2)

Under reducing conditions Tc(IV) forms a separate Under reducing conditions Tc(IV) forms a separate TcOTcO22*1.6H*1.6H22O phase - no interaction between Tc O phase - no interaction between Tc hydroxide and Na oxalate were detectedhydroxide and Na oxalate were detected

Tc precipitate is not resistant to leaching with 0.1 N Tc precipitate is not resistant to leaching with 0.1 N NaNONaNO22

NaOH + H2C2O4 = Na2C2O4

X-ray diffraction tests : the precipitate is sodium oxalate Na2C2O4

(PDF#20-1149)

Study of Tc uptake withStudy of Tc uptake with Cryolite NaCryolite Na33AlFAlF66 under under

oxidizing and reducing conditionsoxidizing and reducing conditions

Reduced Tc Reduced Tc ::

17-35% of Tc(IV) as 17-35% of Tc(IV) as TcClTcCl662-2- is co- is co-precipitated with precipitated with cryolite cryolite

NN22HH55NONO33 inhibits co- inhibits co-precipitationprecipitation

Oxidizing conditionsOxidizing conditions: :

Kd is less 1Kd is less 1

Tc(VII) is excluded Tc(VII) is excluded from cryolite from cryolite structurestructure

6F6F--+NaAlO+NaAlO22+Na+Na22COCO33

X-ray diffraction tests : the precipitate is cryolite Na3AlF6

Study of Tc(IV) uptake Study of Tc(IV) uptake with with Cryolite NaCryolite Na33AlFAlF66

under under rreducing conditionseducing conditions

No [NH4F]

initial,M

[Na2CO3] in

final solution, M

[N2H5NO3], in

final solution, M

Tc(IV) uptake,

%

1234589

10

2,02.53.04,06,02,02,02,0

0,60.60,60.60,60,40,80,6

-------

0,1

202326283525170

• Tc(IV) is added as NaTc(IV) is added as Na22TcClTcCl66 to ( to (NHNH44F+NaAlOF+NaAlO22) solution) solution

• No additional reducing agent in exp. No 1-9No additional reducing agent in exp. No 1-9• Leaching test were impossible to quantify relative to Leaching test were impossible to quantify relative to real cryolite in tanks as complete peptization occurred.real cryolite in tanks as complete peptization occurred.

Study of Tc(IV) uptake with Study of Tc(IV) uptake with FeOOH FeOOH under under rreducing conditionseducing conditions

Precipitation test: Leaching test (t=18 oC, d = days):

Leaching yield ,Tc, %NaOH

M

Tc in solidphase, %

Leachingagent: 1 d 10 d 29 d 105d

0.6 97 0.1M NaOH 1.0 9.8 14.9 24

2.0 88.0 1M NaOH 2.9 16.5 40.2 58

4.0 90 2M NaOH 0.8 2 3 8.2

Reducing agent: 0.02M FeSO4, T = 60Reducing agent: 0.02M FeSO4, T = 6000СС, time = 3 h , time = 3 h Precipitate : FeOOH/FePrecipitate : FeOOH/Fe22OO33

ThoughThough TcTc adsorbed adsorbed betterbetter on iron hydroxides from 0.5–2.0 M NaOH on iron hydroxides from 0.5–2.0 M NaOH than from 3.0-4.0 M NaOH,than from 3.0-4.0 M NaOH, the precipitates formed the precipitates formed at lower NaOH at lower NaOH

concentration were more easily leached by the NaOH leachantconcentration were more easily leached by the NaOH leachantTc leaching with H2O2 was 20 % and with Na2S2O8 was70-100% in 100

days

Study of Tc(IV) uptake with Study of Tc(IV) uptake with MnOOH MnOOH under under rreducing conditionseducing conditions

Reaction NaOH + NaReaction NaOH + Na22MnOMnO44+ N+ N22HH55OH= MnOOHOH= MnOOHX-ray diffraction tests : the freshly precipitated solid X-ray diffraction tests : the freshly precipitated solid

was Mnwas Mn22OO3 3 , the aged precipitate was manganite , the aged precipitate was manganite MnOOH MnOOH (PDF#18-805)(PDF#18-805)

Manganese(III) oxides were effective Tc carriers and underwent chemical transformations on ageing that increased leaching

resistance to most agents.

0

2

4

6

8

10

12

0 2 4 6 8 10 12Time. d

Lea

ched

Tc,

%

1) Mn/Al=1/10

2) Mn/Al=1/40

3)Mn/Al=1/10

4) Mn/Al=1/40

MnOOH precipitation MnOOH leaching to 0.1 NaOH (1,3,4) and Na2S2O8(2)

0

15

30

45

60

75

90

0 5 10 15 20 25 30

Time,d

Tc u

ptak

e by

pre

cipi

tate

, %

Mn/Al=1/10

Mn/Al=1/40

(a)(a) Al(OH)3 - Aluminum hydroxide - gibbsite ; Al(OH)3 - Aluminum hydroxide - gibbsite ;

(b)(b) Boehmite [AlO(OH)] -aluminum oxyhydroxide Boehmite [AlO(OH)] -aluminum oxyhydroxide

(c)(c) Al2O3 aluminum oxide - corundAl2O3 aluminum oxide - corund

Boehmite and Al-oxyhydroxide gels sorb ReO4Boehmite and Al-oxyhydroxide gels sorb ReO4 a non-radioactive analogue a non-radioactive analogue of TcO4of TcO4 from NaNO3 solutions.Sorption appears to be substantially from NaNO3 solutions.Sorption appears to be substantially electrostatic (though thereelectrostatic (though there appears to be a specific preference for ReO4appears to be a specific preference for ReO4 over NO3over NO3 andand is most effective at pH , 8. Measured Kd’s lie between 5 andis most effective at pH , 8. Measured Kd’s lie between 5 and 105 ml g105 ml g--1, depending on the solid, pH, and ionic strength.1, depending on the solid, pH, and ionic strength. ReO4ReO4 and TcO4 and TcO4 are both partially removed from high pHare both partially removed from high pH Hanford-type acid waste simulants Hanford-type acid waste simulants upon neutralization and formationupon neutralization and formation of Al-rich sludges. It was proposed that of Al-rich sludges. It was proposed that sequestrationsequestration of Tc by boehmite limits dissolved Tc levels in the nearof Tc by boehmite limits dissolved Tc levels in the near and and sub-surface environment and for that purpose boehmitesub-surface environment and for that purpose boehmite might be relied on might be relied on as a backfill, or reactive barrier, to limitas a backfill, or reactive barrier, to limit environmental transport environmental transport of Tc.of Tc.

How Mo-Tc generators could do work being made of Al oxide - How Mo-Tc generators could do work being made of Al oxide - oxyhydroxide ???oxyhydroxide ???

Boehmite sorbs perrhenate and pertechnetateBoehmite sorbs perrhenate and pertechnetateBy Peng-Chu Zhang*, James L. Krumhansl and Patrick V. BradyBy Peng-Chu Zhang*, James L. Krumhansl and Patrick V. BradySandia National Laboratories, Albuquerque, USASandia National Laboratories, Albuquerque, USARadiochim. Acta 88, 3692373 (2000)Radiochim. Acta 88, 3692373 (2000)

Tc(VII) + STc(VII) + S2-2-

0 2 4 6 8 10 12 14 16 18 20 22 240.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

Kinetics of the reaction of pertechnetate with sulfide

in 0.3M Na2S solution at 22oC

[Tc], *104M

Tc2.66 Tc1.9 Tc1.52 Tc1.14 Tc0.57

Co

nve

rtio

n d

eg

ree

Time, min

SSeeparation paration ofof Tc Tc22SS77 colloid colloideses fromfrom Na Na22SS solution solution byby

Microfilterfuge (RAININ Instr. Co) Microfilterfuge (RAININ Instr. Co) with with ultrafiltrationultrafiltration membranes membranes -- 30000 NMWL 30000 NMWL

Formation Formation ofof colloid colloideses TcTc22SS7 7 is c is complomplèteète inin 50 50 hhoursours under these under these conditionsconditions

[Tc] [Tc] in the in the solutionsolutionss at at times from times from 50 50 toto 150 h 150 hoours urs corresponds to true corresponds to true solubilitsolubility ofy of Tc Tc22SS77

Tc2S7 ultrafiltration

0

0.0001

0.0002

0.0003

0.0004

0.0005

0.0006

0.0007

0 25 50 75 100 125 150 175 200

TIME, H

C(T

c), M

/L

0.46M

0.33M

0.2M

0.13M

0.066M

0.033M

0.02M

[Na2S]

Solubility Tc2S7 in Na2S solutions

C(Tc) = -9E-05Ln[Na2S] - 2E-05

R2 = 0.9917

0

0.00005

0.0001

0.00015

0.0002

0.00025

0.0003

0.00035

0 0.1 0.2 0.3 0.4 0.5

[Na2S], M/L

C(T

c), M

/L

The reduction of Tc(VII) to The reduction of Tc(VII) to Tc(V,IV,III ) by abiotic and biotic Tc(V,IV,III ) by abiotic and biotic

processesprocesses

The reduction of Tc(VII) to Tc(IV) by abiotic and biotic The reduction of Tc(VII) to Tc(IV) by abiotic and biotic processes has recently been the subject of extensive studies processes has recently been the subject of extensive studies because it has a significant effect on the mobility of because it has a significant effect on the mobility of technetium in waste streams, vadose zones, sediments, and technetium in waste streams, vadose zones, sediments, and groundwater. These reaction processes are the basis for groundwater. These reaction processes are the basis for certain remediationtechnologies such as permeable barriers certain remediationtechnologies such as permeable barriers composed of zero-valent iron particles (i.e., as metallic iron) or composed of zero-valent iron particles (i.e., as metallic iron) or sodium-dithionite reduced soils, which are being tested for sodium-dithionite reduced soils, which are being tested for immobilization of groundwater contaminants.immobilization of groundwater contaminants.

Microbial reduction of Microbial reduction of Tc(VII)Tc(VII)

Microbial reduction of Tc(VII) has been suggested as a Microbial reduction of Tc(VII) has been suggested as a potential mechanism for removing technetium from potential mechanism for removing technetium from contaminated groundwaters and waste streams (e.g., Lovley contaminated groundwaters and waste streams (e.g., Lovley 1993, 1995, Lyalikova,German et all. 1994).1993, 1995, Lyalikova,German et all. 1994).

Certain dissimilatory metal reducing bacteria and sulfate Certain dissimilatory metal reducing bacteria and sulfate reducing bacteria have been determined to be capable of reducing bacteria have been determined to be capable of coupling the oxidation of organic carbon or hydrogen to the coupling the oxidation of organic carbon or hydrogen to the reduction of Tc(VII) to Tc(IV) (Lyakikova,German,Khizhnyak reduction of Tc(VII) to Tc(IV) (Lyakikova,German,Khizhnyak Peretrukhin 1994 , 1998, Gavrilov –German 2007 and Lloyd Peretrukhin 1994 , 1998, Gavrilov –German 2007 and Lloyd and Macaskie 1996; and Macaskie 1996; Lloyd et al. 1997, 1998, 1999, 2000a,b; Lloyd et al. 1997, 1998, 1999, 2000a,b; Wildung et al. 2000; Fredrickson et al. 2000).Wildung et al. 2000; Fredrickson et al. 2000).

TransmutationTransmutation

Tc-Ru acidic and pyrochemical solubilization problemTc-Ru acidic and pyrochemical solubilization problem

N. Schroeder approach : homogeneous transmutation