Studies on the reduction of technetate(VII) by 1,2 bis(diphenylphosphino)ethane

International Nuclear Information System (INIS)

Muenze, R.; Seifert, S.; Kloetzer, D.; Maeding, P.; Goerner, W.

1984-01-01

The reduction of technetate(VII) by using 1,2 bis(diphenylphosphino)ethane (DPPE) has been investigated as a model for the preparation of new myotropic technetium compounds. Phosphino complexes were isolated and characterized which contain technetium in the oxidation state V([TcO 2 DPPE 2 ][TcO 4 ]), IV([TcCl 2 DPPE 2 ][TcCl 6 ]), III ([TcCl 3 DPPE 2 ] 0 ), ([TcCl 2 DPPE 2 ]Cl, and II ([TcCl 2 DPPE 2 ] 0 ) dependent on the reaction conditions, in particular Tc/DPPE and Tc/HCl ratios. (author)

Agile Objects: Component-Based Inherent Survivability

Science.gov (United States)

2003-12-01

pages 37-55, February 1990. [3] Clar, David D., Van Jacobson, John Romkey, and Howard Salwen. “An analysis of TCP processing overhead”. IEEE...www.microsoft.com/technet/treeview/default.asp?url=/technet/prodtech nol/acs/Default.asp 34. Chaum , D.L., Untraceable Electronic Mail, Return

*NEW* CRITICAL Windows Security patches

CERN Multimedia

2003-01-01

On 3 October and 10 September 2003, Microsoft issued new CRITICAL security patches MS03-040 and MS03-039. They must be URGENTLY applied on ALL WINDOWS systems, which are not centrally managed for security patches. This includes Experiment computers, Home computers and Windows Portable and Desktop systems not running NICE. Details of the security holes and patches are at: MS03-039: http://cern.ch/it-div/news/hotfix-MS03-039.asp http://www.microsoft.com/technet/security/bulletin/MS03-039.asp MS03-040: http://cern.ch/it-div/news/hotfix-MS03-040.asp http://www.microsoft.com/technet/security/bulletin/MS03-040.asp

Windows Security patch required

CERN Multimedia

3004-01-01

This concerns Windows PCs (XP, 2000, NT) which are NOT centrally managed at CERN for security patches, e.g. home PCs, experiment PCs, portables,... A security hole which can give full privileges on Windows systems needs to be URGENTLY patched. Details of the security hole and hotfix are at: http://cern.ch/it-div/news/hotfix-MS03-026.asp http://www.microsoft.com/technet/security/bulletin/MS03-026.asp

*New* CRITICAL Windows Security patch

CERN Multimedia

2003-01-01

On 10 September 2003, Microsoft issued a new CRITICAL security patch, MS03-039. It must be URGENTLY applied on ALL WINDOWS systems, which are not centrally managed for security patches. This includes Experiment computers, Home computers and Windows Portable and Desktop systems not running NICE. Details of the security hole and patch for MS03-039 (which also includes MS03-026) are at: http://cern.ch/it-div/news/hotfix-MS03-039.asp http://www.microsoft.com/technet/security/bulletin/MS03-039.asp

*New*: CRITICAL Windows Security patch

CERN Multimedia

2003-01-01

On 10 September 2003, Microsoft issued a new CRITICAL security patch, MS03-039. It must be URGENTLY applied on ALL WINDOWS systems, which are not centrally managed for security patches. This includes Experiment computers, Home computers and Windows Portable and Desktop systems not running NICE. Details of the security hole and patch for MS03-039 (which also includes MS03-026) are at: http://cern.ch/it-div/news/hotfix-MS03-039.asp http://www.microsoft.com/technet/security/bulletin/MS03-039.asp

Advancing MEMS Technology Usage through the MUMPS (Multi-User MEMS Processes) Program

Science.gov (United States)

Koester, D. A.; Markus, K. W.; Dhuler, V.; Mahadevan, R.; Cowen, A.

1995-01-01

In order to help provide access to advanced micro-electro-mechanical systems (MEMS) technologies and lower the barriers for both industry and academia, the Microelectronic Center of North Carolina (MCNC) and ARPA have developed a program which provides users with access to both MEMS processes and advanced electronic integration techniques. The four distinct aspects of this program, the multi-user MEMS processes (MUMP's), the consolidated micro-mechanical element library, smart MEMS, and the MEMS technology network are described in this paper. MUMP's is an ARPA-supported program created to provide inexpensive access to MEMS technology in a multi-user environment. It is both a proof-of-concept and educational tool that aids in the development of MEMS in the domestic community. MUMP's technologies currently include a 3-layer poly-silicon surface micromachining process and LIGA (lithography, electroforming, and injection molding) processes that provide reasonable design flexibility within set guidelines. The consolidated micromechanical element library (CaMEL) is a library of active and passive MEMS structures that can be downloaded by the MEMS community via the internet. Smart MEMS is the development of advanced electronics integration techniques for MEMS through the application of flip chip technology. The MEMS technology network (TechNet) is a menu of standard substrates and MEMS fabrication processes that can be purchased and combined to create unique process flows. TechNet provides the MEMS community greater flexibility and enhanced technology accessibility.

Study on the stability of MAG 3

International Nuclear Information System (INIS)

Aungurarat, Angkanan; Ngamprayad, Tippanan; Thuntawewadthananon, Twesak

2000-01-01

Tc 9 9m -MAG 3 ([(N-(N-(N-(mercaptoacetyl) glycyl)glycyl) glycinato (2-) N, N', N , S) oxo technetate (2-)]) was prepared for a good renal imaging agent. The two chromatographic methods for analysis of radiochemical purity investigated that the kit could be used with sodium pertechnetate (Technetium-9 9m ) up to 25 mCi, volume 2-5 ml and the Tc9 9m -MAG 3 complex reached maximum at 15 mins. The shelf life of the complex and the expiry date of the kit were 4 hrs and 6 months respectivily

Study on the stability of MAG 3

CERN Document Server

Aungurarat, A; Thuntawewadthananon, T

2000-01-01

Tc 9 sup 9 sup m -MAG 3 ([(N-(N-(N-(mercaptoacetyl) glycyl)glycyl) glycinato (2-) N, N', N sup , S) oxo technetate (2-)]) was prepared for a good renal imaging agent. The two chromatographic methods for analysis of radiochemical purity investigated that the kit could be used with sodium pertechnetate (Technetium-9 sup 9 sup m) up to 25 mCi, volume 2-5 ml and the Tc9 sup 9 sup m -MAG 3 complex reached maximum at 15 mins. The shelf life of the complex and the expiry date of the kit were 4 hrs and 6 months respectivily.

Technetium-99m in nuclear medicine and radiation protection experience

International Nuclear Information System (INIS)

Ninkovic, M. M.; Raicevic, J. J.; Pavlovic, S.; Glisic, R.

2002-01-01

The one of the major contributors to personnel exposure whithin nuclear medicine laboratories is primarily now ubiquitous 99 Mo- 99m Tc generators. These generators, first available about more than forthy years ago, are now providing large quantities of 99m Tc radioactive source daily in the most laboratories, both for direct injection, as a per-technetate ion, and through the utilization of the kits for the preparation of dipherent radiopharmaceuticals. The safe and efficient utilization of technetium-99m in nuclear medicine, as other radionuclides, begin with the design, construction and operation of the 'Hot'Laboratory area, where radionuclide are stored and patient doses are prepared. Regardless of the specific physical configuration, suitable facilities need to be provided and good working practices established in order to get these principal objectives: (a) keep radiation exposure to personnel at ALARA levels; (b) prevent contamination of personnel; (c) prevent contamination of measuring instruments (including imaging devices such as gamma cameras and rectilinear scanners), and (d) prevent spread of contamination to places or persons outside the laboratory

Critical review of the chemistry and thermodynamics of technetium and some of its inorganic compounds and aqueous species

International Nuclear Information System (INIS)

Rard, J.A.

1983-01-01

Chemical and thermodynamic data for Technetium (Tc) and some of its inorganic compounds and aqueous species are reviewed here. Major emphasis is given to systems with potential geochemical applications, especially the geochemistry of radioactive waste disposal. Compounds considered include oxides, hydroxides, hydrates oxides, halides, oxyhalides, double halides, and sulfides. The aqueous species considered include those in both noncomplexing media (pertechnetates, technetates, aquo-ions, and hydrolyzed cations) and complexing media (halides, sulfates, and phosphates). Thermodynamic values are recommended for specific compounds and aqueous ions when reliable experimental data are available. Where thermodynamic data are inadequate or unavailable, the chemistry is still discussed to provide information about what needs to be measured, and which chemistry needs to be clarified. A major application of these thermodynamic data will be for chemical equilibrium modeling and for construction of potential-pH diagrams for aqueous solutions. Unfortunately, the present lack of data precludes such calculations for complexing aqueous media. The situation is much better for noncomplexing aqueous media, but the chemistry and thermodynamics of cationic Tc(V) species and hydrolyzed Tc(III) species are poorly understood. 240 references, 6 tables

Diffusion of anionic species in borecore samples of Boda claystone formation

Energy Technology Data Exchange (ETDEWEB)

Lazar, K.; Megyeri, J. [Inst. of Isotopes, Budapest, P.O.B. 77, H-1525 (Hung ary)]. e-mail: lazar@iki.kfki.hu; Mathe, Z. [Mecsekerc Co., Esztergar L. 19, Pec s, H-7633 (Hungary)

2007-06-15

Diffusion of {sup 99}Tc and {sup 14}C radioisotopes in anionic forms of TcO{sub 4} - and H{sup 14}CO{sub 3} - were studied in samples originated from Boda Claystone Formation by using break-through measurements. The {sup 99}Tc solution was spiked (5 x 10{sup -4} mol/l), whereas the HCO{sub 3} - concentration was the same as in the respective ground water of the formation (1.2 x 10{sup -2} mol/l). The apparent diffusivity constants were estimated from the slope of the increase of the activity concentrations observed within 230 day period. Similar values were obtained: 1.1 x 10{sup -12}/m{sup 2}/s for technetate and 1.3 x 10{sup -12}/m{sup 2}/s for hydrocarbonate. These results can be compared with previous studies carried out under similar conditions with {sup 125}I, where practically the same value was obtained for the apparent diffusivity. Thus, it can be concluded that anionic species migrate with a similar rate in the studied Boda Claystone samples, and do not interact noticeably with the rock. In correlation with the diffusion of TcO{sub 4} - the actual redox state of the rock sample was characterized by determining the Fe{sup 3+}/Fe{sup 2+} ratio with Moessbauer spectroscopy. In spite of the significant amount of ferrous iron present, the redox processes probably do not considerably influence the migration rate of the studied anions.

Using Mobile Phones to Improve Vaccination Uptake in 21 Low- and Middle-Income Countries: Systematic Review.

Science.gov (United States)

Oliver-Williams, Clare; Brown, Elizabeth; Devereux, Sara; Fairhead, Cassandra; Holeman, Isaac

2017-10-04

The benefits of vaccination have been comprehensively proven; however, disparities in coverage persist because of poor health system management, limited resources, and parental knowledge and attitudes. Evidence suggests that health interventions that engage local parties in communication strategies improve vaccination uptake. As mobile technology is widely used to improve health communication, mobile health (mHealth) interventions might be used to increase coverage. The aim of this study was to conduct a systematic review of the available literature on the use of mHealth to improve vaccination in low- and middle-income countries with large numbers of unvaccinated children. In February 2017, MEDLINE (Medical Literature Analysis and Retrieval System Online), Scopus, and Web of Science, as well as three health organization websites-Communication Initiative Network, TechNet-21, and PATH-were searched to identify mHealth intervention studies on vaccination uptake in 21 countries. Ten peer-reviewed studies and 11 studies from white or gray literature were included. Nine took place in India, three in Pakistan, two each in Malawi and Nigeria, and one each in Bangladesh, Zambia, Zimbabwe, and Kenya. Ten peer-reviewed studies and 7 white or gray studies demonstrated improved vaccination uptake after interventions, including appointment reminders, mobile phone apps, and prerecorded messages. Although the potential for mHealth interventions to improve vaccination coverage seems clear, the evidence for such interventions is not. The dearth of studies in countries facing the greatest barriers to immunization impedes the prospects for evidence-based policy and practice in these settings. ©Clare Oliver-Williams, Elizabeth Brown, Sara Devereux, Cassandra Fairhead, Isaac Holeman. Originally published in JMIR Mhealth and Uhealth (http://mhealth.jmir.org), 04.10.2017.

Testing candidate interlayers for an enhanced water-cooled divertor target

International Nuclear Information System (INIS)

Hancock, David; Barrett, Tom; Foster, James; Fursdon, Mike; Keech, Gregory; McIntosh, Simon; Timmis, William; Rieth, Michael; Reiser, Jens

2015-01-01

Highlights: • We introduce an optimised divertor target concept: the “Thermal Break”. • We suggest a candidate interlayer material for this concept: FeltMetal. • We describe a bespoke rig for testing the thermal conductivity of this material. • We present preliminary results for a number of samples. - Abstract: The design of a divertor target for DEMO remains one of the most challenging engineering tasks to be overcome on the path to fusion power. Under the European DEMO programme, a promising concept known as Thermal Break has been developed at CCFE. This concept is a variation of the ITER tungsten divertor in which the pure Copper interlayer between Copper Chrome Zirconium coolant pipe and Tungsten monoblock armour is replaced with a low thermal conductivity compliant interlayer, with the aim of reducing the thermal mismatch stress between the armour and structure. One candidate material for this interlayer is FeltMetal™ (Technetics Group, USA). This material consists of an amorphous matrix of fine copper wires which are sintered onto a thin copper foil, creating a sheet of approximately 1 mm thickness. FeltMetal has been successfully used for many years to provide compliant sliding electrical contacts for the MAST TF coils and on ALCATOR C-Mod and extensive material testing has therefore been undertaken to quantify thermal and mechanical properties. These tests, however, have not been performed under vacuum or DEMO-relevant conditions. A bespoke experimental test rig has therefore been designed and constructed with which to measure the interlayer thermal conductance as a function of temperature and pressure under vacuum conditions. The design of this apparatus and the results of experiments on FeltMetal as well as other candidate interlayers are presented here. In parallel, joint mockups using the candidate interlayers have been prepared and Thermal Break divertor target mockups have been manufactured, requiring the development of a dedicated

Solubility of Tc(IV) oxides

International Nuclear Information System (INIS)

Liu, D.J.; Fan, X.H.

2005-01-01

Full text of publication follows: The deep geological disposal of the high level radioactive wastes is expected to be a safer disposal method in most countries. The long-lived fission product 99 Tc is present in large quantities in nuclear wastes and its chemical behavior in aqueous solution is of considerable interest. Under the reducing conditions, expected to exist in a deep geological repository, it is generally predicted that technetium will be present as TcO 2 .nH 2 O. The solubility of Tc(IV) is used as a source term in performance assessment of radioactive waste repository. Technetium oxide was prepared by reduction of a technetate solution with Sn 2+ . The solubility of Tc(IV) oxide has been determined in simulated groundwater and re-distilled water under aerobic and anaerobic conditions. The effects of pH and CO 3 2- concentration of solution on solubility of Tc(IV) oxide were studied. The concentration of total technetium and Tc(IV) species in the solutions were periodically determined by separating the oxidized and reduced technetium species using a solvent extraction procedure and counting the beta activity of the 99 Tc with a liquid scintillation counter. The experimental results show that the rate of oxidation of Tc(IV) in simulated groundwater and re-distilled water is about (1.49∼1.86) x 10 -9 mol/(L.d) under aerobic conditions, but Tc(IV) in simulated groundwater and re-distilled water is not oxidized under anaerobic conditions. Under aerobic or anaerobic conditions the solubility of Tc(IV) oxide in simulated groundwater and re-distilled water is equal on the whole after centrifugation or ultrafiltration. The solubility of Tc(IV) oxide decreases with the increase of pH at pH 10 and is pH independent in the range 2 -8 to 10 -9 mol/L at 2 3 2- concentration. These data could be used to estimate the Tc(IV) solubility for cases where solubility limits transport of technetium in reducing environments of high-level waste repositories. (authors)

Testing candidate interlayers for an enhanced water-cooled divertor target

Energy Technology Data Exchange (ETDEWEB)

Hancock, David, E-mail: david.hancock@ccfe.ac.uk [CCFE, Culham Science Centre, Oxfordshire OX14 3DB (United Kingdom); Barrett, Tom; Foster, James; Fursdon, Mike; Keech, Gregory; McIntosh, Simon; Timmis, William [CCFE, Culham Science Centre, Oxfordshire OX14 3DB (United Kingdom); Rieth, Michael; Reiser, Jens [Karlsruhe Institute of Technology, IAM-AWP, P.O. Box 3640, 76021 Karlsruhe (Germany)

2015-10-15

Highlights: • We introduce an optimised divertor target concept: the “Thermal Break”. • We suggest a candidate interlayer material for this concept: FeltMetal. • We describe a bespoke rig for testing the thermal conductivity of this material. • We present preliminary results for a number of samples. - Abstract: The design of a divertor target for DEMO remains one of the most challenging engineering tasks to be overcome on the path to fusion power. Under the European DEMO programme, a promising concept known as Thermal Break has been developed at CCFE. This concept is a variation of the ITER tungsten divertor in which the pure Copper interlayer between Copper Chrome Zirconium coolant pipe and Tungsten monoblock armour is replaced with a low thermal conductivity compliant interlayer, with the aim of reducing the thermal mismatch stress between the armour and structure. One candidate material for this interlayer is FeltMetal™ (Technetics Group, USA). This material consists of an amorphous matrix of fine copper wires which are sintered onto a thin copper foil, creating a sheet of approximately 1 mm thickness. FeltMetal has been successfully used for many years to provide compliant sliding electrical contacts for the MAST TF coils and on ALCATOR C-Mod and extensive material testing has therefore been undertaken to quantify thermal and mechanical properties. These tests, however, have not been performed under vacuum or DEMO-relevant conditions. A bespoke experimental test rig has therefore been designed and constructed with which to measure the interlayer thermal conductance as a function of temperature and pressure under vacuum conditions. The design of this apparatus and the results of experiments on FeltMetal as well as other candidate interlayers are presented here. In parallel, joint mockups using the candidate interlayers have been prepared and Thermal Break divertor target mockups have been manufactured, requiring the development of a dedicated

Volatility of ruthenium-106, technetium-99, and iodine-129, and the evolution of nitrogen oxide compounds during the calcination of high-level, radioactive nitric acid waste

International Nuclear Information System (INIS)

Rimshaw, S.J.; Case, F.N.; Tompkins, J.A.

1980-02-01

The nitrate anion is the predominant constituent in all high-level nuclear wastes. Formic acid reacts with the nitrate anion to yield noncondensable, inert gases (N 2 or N 2 O), which can be scrubbed free of 106 Ru, 129 I, and 99 Tc radioactivities prior to elimination from the plant by passing through HEPA filters. Treatment of a high-level authentic radioactive waste with two moles of formic acid per mole of nitrate anion leads to a low RuO 4 volatility of about 0.1%, which can be reduced to an even lower level of 0.007% on adding a 15% excess of formic acid. Without pretreatment of the nitrate waste with formic acid, a high RuO 4 volatility of approx. 35% is observed on calcining a 4.0 N HNO 3 solution in quartz equipment at 350 0 C. The RuO 4 volatility falls to approx. 1.0% on decreasing the initial HNO 3 concentration to 1.0 N or lower. It is postulated that thermal denitration of a highly nitrated ruthenium complex leads to the formation of volatile RuO 4 , while decarboxylation of a ruthenium-formate complex leads to the formation of nonvolatile RuO 2 . Wet scrubbing with water is used to remove RuO 4 from the off-gas stream. In all glass equipment, small amounts of particulate RuO 2 are formed in the gas phase by decomposition of RuO 4 . The 99 Tc volatility was found to vary from 0.2 to 1.4% on calcining HNO 3 and HCOOH (formic acid) solutions over the temperature range of 250 to 600 0 C. These unexpectedly low volatilities of 99 Tc are correlated to the high thermal stability limits of various metal pertechnetates and technetates. Iodine volatilities were high, varying from a low of 30% at 350 0 C to a high of 97% at 650 0 C. It is concluded that with a proper selection of pretreatment and operating conditions the 106 Ru and 99 Tc activities can be retained in the calcined solid with recycle of the wet scrubbing solution

Solubility study of Tc(IV) oxides

International Nuclear Information System (INIS)

Liu, D.J.; Fan, X.H.

2005-01-01

The deep geological disposal of the high level radioactive wastes is expected to be a safer disposal method in most countries. The long-lived fission product 99 Tc is present in large quantities in nuclear wastes and its chemical behavior in aqueous solution is of considerable interest. Under oxidizing conditions technetium exists as the anionic species TcO 4 - whereas under the reducing conditions, expected to exist in a deep geological repository, it is generally predicted that technetium will be present as TcO 2 ·nH 2 O. Hence, the mobility of Tc(IV) in reducing groundwater may be limited by the solubility of TcO 2 ·nH 2 O under these conditions. Due to this fact it is important to investigate the solubility of TcO 2 ·nH 2 O. The solubility determines the release of radionuclides from waste form and is used as a source term in radionuclide migration analysis in performance assessment of radioactive waste repository. Technetium oxide was prepared by reduction of a technetate solution with Sn 2 + . The solubility of Tc(IV) oxide has been determined in simulated groundwater and redistilled water under aerobic and anaerobic conditions. The effects of pH and CO 3 2- concentration of solution on solubility of Tc(IV) oxide were studied. The concentration of total technetium and Tc(IV) species in the solutions were periodically determined by separating the oxidized and reduced technetium species using a solvent extraction procedure and counting the beta activity of the 99 Tc with a liquid scintillation counter. The experimental results show that the rate of oxidation of Tc(IV) in simulated groundwater and redistilled water is about (1.49-1.86) x 10 -9 mol/(L·d) under aerobic conditions, but Tc(IV) in simulated groundwater and redistilled water is not oxidized under anaerobic conditions. Under aerobic or anaerobic conditions the solubility of Tc(IV) oxide in simulated groundwater and redistilled water is equal on the whole after centrifugation or ultrafiltration. The

Solubility study of Tc(IV) in a granitic water

International Nuclear Information System (INIS)

Liu, D.J.; Yao, J.; Wang, B.; Bruggeman, C.; Maes, N.

2007-01-01

The deep geological disposal of the high level radioactive wastes is expected to be a safe disposal method in most countries. The long-lived fission product 99 Tc is present in large quantities in nuclear wastes and its chemical behavior in aqueous solution is of considerable interest. Under oxidizing conditions technetium exists as the anionic species TcO 4 - whereas under the reducing conditions, expected to exist in a deep geological repository, it is generally predicted that technetium will be present as TcO 2 .nH 2 O. Hence, the mobility of Tc(IV) in reducing groundwater may be limited by the solubility of TcO 2 .nH 2 O under these conditions. Due to this fact it is important to investigate the solubility of TcO 2 .nH 2 O. The solubility determines the release of radionuclides from waste form and is used as a source term in radionuclide migration analysis in performance assessment of radioactive waste repository. Technetium(IV) was prepared by reduction of a technetate solution with Sn 2+ . The solubility of Tc(IV) has been determined in simulated groundwater and redistilled water under aerobic and anaerobic conditions. The effects of pH and CO 3 2- concentration of solution on solubility of Tc(IV) were studied. The concentration of total technetium and Tc(IV) species in the solutions were periodically determined by separating the oxidized and reduced technetium species using a solvent extraction procedure and counting the beta activity of the 99 Tc with a liquid scintillation counter. The experimental results show that the rate of oxidation of Tc(IV) in simulated groundwater and redistilled water is about (1.49 ∝ 1.86) x 10 -9 mol L -1 d -1 under aerobic conditions, while no Tc(IV) oxidation was detected in simulated groundwater and redistilled water under anaerobic conditions. Under aerobic or anaerobic conditions the solubility of Tc(IV) in simulated groundwater and redistilled water is equal on the whole after centrifugation or ultrafiltration. The

Solubility study of Tc(Ⅳ) in a granitic water

International Nuclear Information System (INIS)

Liu Dejun; Yao Jun; Wang Bo

2008-01-01

The deep geological disposal of the high level radioactive wastes is expected to be a safe disposal method in most countries. The long-lived fission product 99 Tc is present in large quantities in nuclear wastes and its chemical behavior in aqueous solution is of considerable interest. Under oxidizing conditions technetium exists as the anionic species TcO 4 - whereas under the reducing conditions, expected to exist in a deep geological repository, it is generally predicted that technetium will be present as TcO 2 -nH 2 O. Hence, the mobility of Tc(Ⅳ) in reducing groundwater may be limited by the solubility of TcO 2 ·nH 2 O under these conditions. Due to this fact it is important to investigate the solubility of TcO 2 ·nH 2 O. The solubility determines the release of radionuclides from waste form and is used as a source term in radionuclide migration analysis in performance assessment of radioactive waste repository. Technetium (Ⅳ) was prepared by reduction of a technetate solution with Sn 2+ . The solubility of Tc(Ⅳ) has been determined in simulated groundwater and redistilled water under aerobic and anaerobic conditions. The effects of pH and CO 3 2- concentration of solution on solubility of Tc(Ⅳ) were studied. The concentration of total technetium and Tc(Ⅳ) species in the solutions were periodically determined by separating the oxidized and reduced technetium species using a solvent extraction procedure and counting the beta activity of the 99 Tc with a liquid scintillation counter. The experimental results show that the rate of oxidation of Tc(Ⅳ) in simulated groundwater and redistilled water is about (1.49-1.86)x10 -9 mol·L -1 d -1 under aerobic conditions, while no Tc(Ⅳ) oxidation was detected in simulated groundwater and redistilled water under anaerobic conditions. Under aerobic or anaerobic conditions the solubility of Tc(Ⅳ) in simulated groundwater and redistilled water is equal on the whole after centrifugation or ultrafiltration. The