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Sample records for ahwr-the indian thorium

  1. Thorium for energy independence

    International Nuclear Information System (INIS)

    Thorium utilization is the long-term core objective of the Indian nuclear programme for providing energy independence on a sustainable basis. The advanced stage of the programme is based on thorium-uranium-233 cycle. India is actively engaged in developing 300 MWe Advanced Heavy Water Reactor (AHWR). The design of this reactor incorporates several advanced features to meet the objectives being set out for future advanced nuclear reactor systems

  2. Energy from thorium-an Indian perspective

    International Nuclear Information System (INIS)

    Nuclear energy as a sustainable resource in India has been very clearly formulated in the three stage nuclear programme. The role of thorium as a potential fuel in the third stage of this programme has also been elucidated. With this aim there have been pioneering research efforts in all aspects of the thorium fuel cycle. Thorium being fertile and not accompanied by the fissile species requires the use of a fissile topping. There have been several studies in India on the use of thorium in different reactor systems from thermal to intermediate and fast spectrum, molten salt reactors, high temperature reactors, compact nuclear power packs and even Subcritical systems. In this paper, we present some of the research studies on use of thorium in thermal reactor systems. We give an overview of the neutronic properties of thorium and the bred fissile material and then proceed to show the performance potential in different reactor systems. We also present the innovative Indian reactor designs which utilize thorium, namely the Advanced Heavy Water Reactor (AHWR) and the Indian High Temperature Reactors. (author)

  3. Indian advanced heavy water reactor for thorium utilisation and nuclear data requirements and status

    International Nuclear Information System (INIS)

    BARC is embarking on thorium utilisation program in a concerted and consistent manner to achieve all round capabilities in the entire Thorium cycle under the Advanced Heavy Water Reactor (AHWR) development program. Upgrading our nuclear data capability for thorium cycle is one of the main tasks of this program. This paper gives a brief overview of the physics design features of the AHWR. The basic starting point of the analysis has been the lattice simulation of the fuel cluster employing the WIMS-D4 code package with 1986 version of 69 group library. For the analysis of thorium cycle, the present multi group version contains the three major isotopes viz., 232Th, 233U and 233Pa. To correctly evaluate the fuel cycle we require many more isotopes of the Th burnup chain. With the help of NDS, IAEA, many other isotopes of interest in AHWR, actinides in the thorium burnup chain, burnable absorbers, etc., were generated. Some of them were added to the WIMS-D4 library and the results are discussed. The WIMS-D4 library is also being updated as part of the IAEA coordinated research project on Final Stage of WLUP with international cooperation. India is also taking part in CRP. The evaluation of AHWR lattice with this new library is presented. Some comments regarding the fission product data being used in WIMS libraries are given, which are tuned to U-Pu cycles. The measurements for 233U are rather old. Measurements in high energies are also very sparse. More attention by nuclear data community is required in this regard as well. India has also begun a modest program to assess the ADS concepts, with the aim of employing thermal reactor systems, such as AHWR. A one way coupled booster reactor concept is being analysed with available code systems and nuclear data. A brief summary of this concept is also being discussed in this paper. A general survey on the quality of the evaluated nuclear data of the major and minor isotopes of thorium cycle is also given. A major

  4. Thorium

    Science.gov (United States)

    Wickleder, Mathias S.; Fourest, Blandine; Dorhout, Peter K.

    In 1815 Berzelius analyzed a rare mineral from the Falun district. He assumed that the mineral contained a new element, which he named thorium after the ancient Scandinavian god of thunder and weather, Thor (Weeks and Leicester, 1968).

  5. Thorium

    International Nuclear Information System (INIS)

    General mineralogical-geochemical and analytical characteristics of thorium are presented. It is stressed that the main trend in the development of analytical methods for determining Th in mineral raw material is the use of physical methods of the analysis. To separate Th from RE, Zr, U being its permanent companions, precipitation, extraction and ion exchange are used. Principal methods of geologic samples dissolution are considered. Some techniques of radiometric, emanation, (by thoron), neutron activation, fluorescence X-ray spectral, spectrographic, gravimetric, photometric (with arsenazo 3) thorium determinations are described

  6. Processing of Indian monazite for the recovery of thorium and uranium values

    International Nuclear Information System (INIS)

    The mineral monazite, a phosphate of rare earths and thorium with significant quantity of uranium is one of the six heavy minerals present in the beach sands of specific coastal areas of India. Indian Rare Earths Ltd is mining and processing monazite at its Rare Earths Division for the last many decades with an aim of building up enough stock of thorium concentrate for its future use in the three stage nuclear power programme of the country. The present paper briefly describes the monazite resource position of he country, the past and present modified processing schemes and the future programme commensurate with the requirement of the country for quality thorium and uranium bearing nuclear materials

  7. Thermal hydraulic analysis of the AHWR—The Indian thorium fuelled innovative nuclear reactor

    International Nuclear Information System (INIS)

    Highlights: • Advanced heavy water reactor. • Thermal hydraulics. • Safety analysis. • RELAP5. -- Abstract: Analysis has been carried out for simulating loss-of-coolant accident (LOCA) at inlet header in a natural circulation type reactor developed as the advanced heavy water reactor (AHWR).The paper will cover a case of LOCA due to 200% break at inlet header which is double ended rupture. The maximum clad surface temperature has been predicted in different cases by using the thermal hydraulic safety code RELAP5/Mod4.0. The proposed reactor is a 920 MWth vertical pressure tube type, boiling light water cooled and heavy water moderated reactor. One of the important passive design features of this reactor is heat removal through natural circulation of primary coolant (at all allowed power levels) with no primary coolant pumps. This reactor is equipped with emergency core cooling system (ECCS) and isolation condensers (ICs) to remove decay heat during LOCA. This ECCS provides cooling to fuel in passive mode during first fifteen minutes of LOCA and it is achieved by high pressure injection from advanced accumulator. Cooling is continued for Later for three days by the gravity driven water pool (GDWP). This paper investigates the impact of high pressure injection in this cooling process

  8. Utilisation of thorium in reactors

    Science.gov (United States)

    Anantharaman, K.; Shivakumar, V.; Saha, D.

    2008-12-01

    India's nuclear programme envisages a large-scale utilisation of thorium, as it has limited deposits of uranium but vast deposits of thorium. The large-scale utilisation of thorium requires the adoption of closed fuel cycle. The stable nature of thoria and the radiological issues associated with thoria poses challenges in the adoption of a closed fuel cycle. A thorium fuel based Advanced Heavy Water Reactor (AHWR) is being planned to provide impetus to development of technologies for the closed thorium fuel cycle. Thoria fuel has been loaded in Indian reactors and test irradiations have been carried out with (Th-Pu) MOX fuel. Irradiated thorium assemblies have been reprocessed and the separated 233U fuel has been used for test reactor KAMINI. The paper highlights the Indian experience with the use of thorium and brings out various issues associated with the thorium cycle.

  9. Scientometric dimensions of thorium research in India

    OpenAIRE

    Kademani, B. S.; Vijai, Kumar; Anil, Sagar; Anil, Kumar; Lalit, Mohan; Surwase, Ganesh

    2006-01-01

    This paper attempts to provide detailed quantitative analysis of Indian contributions on thorium in terms of publications output as per International Nuclear information System database during 1970-2004. A total of 2399 papers were published by the Indian scientists in the field of thorium. There were only nine publications in 1970. Thereafter, a steady growth was observed except for the period 1983-1985. The highest papers (188) were! published in the year 2000. USA with 8049 (28.05 per c...

  10. Some aspects on the variations in depositional flux of excess thorium-230 in the central Indian basin during late quaternary

    International Nuclear Information System (INIS)

    Examined in this paper is the tentative history of the depositional flux of 230Thxs (the unsupported fraction of 230Th scavenged from the overlying water column), for the late quaternary period from a sediment core of the central Indian basin (CIB). The measured depositional flux of 230Thxs is found to be substantially higher than that of the possible theoretical flux from the overlying water column. The average ratio of the measured depositional flux to that of the predicted flux from the overlying water column, indicates that the core site acts as a sink for 230Thxs and based on the existence of bottom current activity; the 230Thxs could be the result of focusing of younger sediments. (author). 29 refs., 2 figs., 2 tabs

  11. Proceedings of the international thorium energy conference: gateway to thorium energy

    International Nuclear Information System (INIS)

    Fuels cycles based on thorium, due to a number of favourable neutronics and material characteristics, could help address the issues of long-term sustainability of fuel resources and also the proliferation concerns associated with uranium based fuel cycles. In the case of India, due to our modest reserves of uranium and large reserves of thorium, efficient utilisation of thorium is an essential requisite and indeed the cornerstone of the Indian nuclear programme. This conference address the issues concerning thorium and its utilization in nuclear programme. Papers relevant to INIS are indexed separately

  12. Integral benchmarks with reference to thorium fuel cycle

    International Nuclear Information System (INIS)

    This is a power point presentation about the Indian participation in the CRP 'Evaluated Data for the Thorium-Uranium fuel cycle'. The plans and scope of the Indian participation are to provide selected integral experimental benchmarks for nuclear data validation, including Indian Thorium burn up benchmarks, post-irradiation examination studies, comparison of basic evaluated data files and analysis of selected benchmarks for Th-U fuel cycle

  13. Fabrication of Thorium and Thorium Dioxide

    OpenAIRE

    Balakrishna Palanki

    2015-01-01

    Thorium based nuclear fuel is of immense interest to India by virtue of the abundance of Thorium and relative shortage of Uranium. Thorium metal tubes were being cold drawn using copper as cladding to prevent die seizure. After cold drawing, the copper was removed by dissolution in nitric acid. Thorium does not dissolve being passivated by nitric acid. Initially the copper cladding was carried out by inserting copper tubes inside and outside the thorium metal tube. In an innovative developmen...

  14. Thorium-232

    International Nuclear Information System (INIS)

    This sheet belongs to a collection which relates to the use of radionuclides essentially in unsealed sources. Its goal is to gather on a single document the most relevant information as well as the best prevention practices to be implemented. These sheets are made for the persons in charge of radiation protection: users, radioprotection-skill persons, labor physicians. Each sheet treats of: 1 - the radio-physical and biological properties; 2 - the main uses; 3 - the dosimetric parameters; 4 - the measurement; 5 - the protection means; 6 - the areas delimitation and monitoring; 7 - the personnel classification, training and monitoring; 8 - the effluents and wastes; 9 - the authorization and declaration administrative procedures; 10 - the transport; and 11 - the right conduct to adopt in case of incident or accident. This sheet deals specifically with Thorium-232

  15. SRP thorium processing experience

    International Nuclear Information System (INIS)

    In the five separate thorium processing campaigns conducted at SRP, thorium was processed in equipment and facilities which had been converted in 1959 to recover highly enriched uranium. Two different flowsheets were used and a total of approximately 240 tons of thorium and 580 kg of uranium was processed. In the first two campaigns (initial campaigns), uranium was recovered with a dilute 3.5% TBP flowsheet and the thorium was sent to waste. In these two initial campaigns, the irradiation conditions for the thorium metal resulted in concentrations of 40 to 50 ppM and 200 ppM 232U in different batches of the product uranium. In the first of the last three campaigns (Thorex campaigns), thorium metal and thorium oxide were processed. Thorium oxide was processed in the remaining two Thorex campaigns. The three Thorex campaigns used 30% TBP to recover both uranium and thorium. Irradiation conditions were set to produce a concentration of 4 to 7 ppM 232U. Dissolving rates for thorium metal exceeded 4 tons/day and with thorium sent to waste, solvent extraction rates increased and posed no limits. Dissolving and Thorex solvent extraction rates were approximately 1 ton/day when thorium oxide feed was used. Studies to increase the dissolving rates indicated that a small amount of MgO (1%) in the thorium oxide would be beneficial. Seven tons of thorium oxide with 1% MgO did give some promise of increased dissolving rates. Satisfactory flowsheets were developed, losses were satisfactory, and decontamination from fission products and protactinium were adequate. About the only unexpected event during the campaigns was the appearance of thorium dibutyl phosphate precipitates that appeared in the second thorium cycle during the first thorex campaigns and interfered with operation. The system slowly returned to normal when the temperature was reduced

  16. Uranium and thorium

    International Nuclear Information System (INIS)

    Present article is devoted to uranium and thorium content in fluorite. In order to obtain the comprehensive view on uranium and thorium distribution in fluorite 100 fluorite samples of various geologic deposits and ores of Kazakhstan, Uzbekistan, Tajikistan and some geologic deposits of Russia were studied. The uranium and thorium content in fluorite of geologic deposits of various mineralogical and genetic type was defined.

  17. Thorium Energy Futures

    OpenAIRE

    Peggs, S.; Horak, W.; Roser, T.; Ashley, V.B.; Ashworth, R.F.; Barlow, Roger; Cywinski, R.; Seviour, Rebecca; Biarrotte, J.-L.; Henderson, S.; Hutton, A; Kelly, J; Lindroos, M.; McIntyre, P. M.; Norlin, A.

    2012-01-01

    The potential for thorium as an alternative or supplement to uranium in fission power generation has long been recognised, and several reactors, of various types, have already operated using thorium-based fuels. Accelerator Driven Subcritical (ADS) systems have benefits and drawbacks when compared to conventional critical thorium reactors, for both solid and molten salt fuels. None of the four options – liquid or solid, with or without an accelerator – can yet be rated as better or worse than...

  18. Estimation of thorium in gas mantles to ascertain regulatory compliance

    International Nuclear Information System (INIS)

    In India, stipulated limits for the use of thorium in gas mantles are 600 mg for luminosities less than 400 candle power (C.P.) rating and 800 mg for greater than 400 C.P. rating. Radioactivity measurements though done easily uncertainties are involved in assessing the mass of thorium because of disequilibrium and for want of information on age of thorium in it. This paper describes the detailed gamma spectrometric measurements performed on mantle samples from 18 different manufacturers. In this method ratio of 228Ac/228Th was used to evaluate the age(t) and using the age, 232Th content was determined and verified by neutron activation analysis and presents estimates of thorium in them. All of the mantles contained thorium in amounts well within the prescribed limits. The results show that approximately 11 ± 2% by weight of the mantle piece accounts for the weight of thorium. This factor may be used for a rapid preliminary estimation of thorium in gas mantles in the Indian context. (author). 5 refs., 2 tabs., 2 figs

  19. Thorium in lamp technology

    International Nuclear Information System (INIS)

    Since 1892 the natural radionuclide thorium has been applied in form of thoriated incandescent mantles for gas lighting. But also for a series of modern electrical discharge lamps the application of electrode-systems containing thorium is still today an international standard of technique. Inspite of intensive research - in consideration of radiation protection - it has neither been possible to find a suitable substitution for thorium nor to abandon it totally while maintaining present product quality. Thus, handling this material, we further will have to pay attention to a high standard in protecting our employees and the environment. (orig.)

  20. Thorium Energy Futures

    Energy Technology Data Exchange (ETDEWEB)

    Peggs, Stephen; Roser, Thomas; Parks, G; Lindroos, Mats; Seviour, Rebecca; Henderson, Stuart; Barlow, R; Cywinski, R; Biarrote, J -L; Norlin, A; Ashley, V; Ashworth, R; Hutton, Andrew; Owen, H; McIntyre, Peter

    2012-07-01

    The potential for thorium as an alternative or supplement to uranium in fission power generation has long been recognised, and several reactors, of various types, have already operated using thorium-based fuels. Accelerator Driven Subcritical (ADS) systems have benefits and drawbacks when compared to conventional critical thorium reactors, for both solid and molten salt fuels. None of the four options - liquid or solid, with or without an accelerator - can yet be rated as better or worse than the other three, given today's knowledge. We outline the research that will be necessary to lead to an informed choice.

  1. Thorium in human tissues

    International Nuclear Information System (INIS)

    The human tissue contents of natural alpha-emitting isotopes of thorium (228Th, 230Th, and 232Th) were determined in six sets of samples from Colorado and two lung samples from New York. Lung, lymph nodes from lung, liver, kidney, spleen, and bone were obtained at autopsy, and radiochemical analyses were made. Thorium-230 and 232Th are distributed similarly in the body, with major amounts present in bone (60%), followed by lung (20%) and lymph nodes (6%). Concentration decreased in the order lymph nodes > lung > bone > liver, kidney, and spleen. Thorium-228 is found primarily in bone (95%), and concentration decreases in the order lymph nodes > bone > lung > liver, kidney, and spleen. For all isotopes the median ratio of concentration in lymph nodes to lung was about 15. Thorium-230 was significantly increased in lung and skeleton samples from an underground hard-rock miner

  2. Thorium ore deposits

    International Nuclear Information System (INIS)

    The main occurences of the thorium minerals of the Argentine Republic which have not been exploited, due to their reduced volume, are described. The thoriferous deposits have three genetic types: pegmatitic, hydrothermal and detritic, being the most common minerals: monazite, thorite and thorogummite. The most important thorium accumulations are located in Salta, being of less importance those of Cordoba, Jujuy and San Juan. (M.E.L.)

  3. Thorium utilization in power reactors

    International Nuclear Information System (INIS)

    In this work the recent (prior to Aug, 1976) literature on thorium utilization is reviewed briefly and the available information is updated. After reviewing the nuclear properties relevant to the thorium fuel cycle we describe briefly the reactor systems that have been proposed using thorium as a fertile material. (author)

  4. Determination of uranium and thorium in monazite bearing sand by gamma ray spectrometry

    International Nuclear Information System (INIS)

    Monazite is one of the most important natural geological mineral due to the presence of heavy metals, rare earth and natural radioactive elements. Monazite is also an important ore for thorium, lanthanum, and cerium. It is very important to assess the concentration of uranium and thorium in various monazite samples observed in Indian coasts and their relative abundance. In addition to thorium, availability of uranium in monazite is also of interest because of an alternate source for the uranium fuel cycle operation going on in our country. The relative abundance of uranium in monazite bearing sands can be represented by the activity ratio of uranium to thorium in the samples. In the present study an attempt has been made to estimate the activity ratios of uranium to thorium in some of the monazite bearing beach sands collected from our coastal regions by using high resolution gamma ray spectrometry techniques

  5. Physics considerations for utilization of thorium in power reactors

    International Nuclear Information System (INIS)

    Molten Salt Reactor design concepts suit the needs of India's Three-Stage nuclear power program for efficient thorium utilization. An effort is being made in BARC to design a MSR configuration for Indian requirements. As a preliminary study, reactor physics analysis of 850 MWe, molten salt reactor operating in fast spectrum is being carried out in hot and static condition. The LiF-ThF4-UF4 is being considered as the primary coolants and fuel. The blanket material is LiF-ThF4. The talk will give an overview of the neutronic properties of thorium and the bred fissile material and then proceed to present the major design features in AHWR and the Indian Molten Salt Breeder Reactor under consideration at present

  6. Energy from thorium—An Indian perspective

    Indian Academy of Sciences (India)

    Umasankari Kannan; P D Krishnani

    2013-10-01

    Nuclear energy as a sustainable resource in India has been very clearly formulated in the three stage nuclear programme. The role of thorium as a potential fuel in the third stage of this programme has also been elucidated. With this aim there have been pioneering research efforts in all aspects of the thorium fuel cycle. Thorium being fertile and not accompanied by the fissile species requires the use of a fissile topping. There have been several studies in India on the use of thorium in different reactor systems from thermal to intermediate and fast spectrum, molten salt reactors, high temperature reactors, compact nuclear power packs and even Subcritical systems. In this paper, we present some of the research studies on use of thorium in thermal reactor systems. We give an overview of the neutronic properties of thorium and the bred fissile material and then proceed to show the performance potential in different reactor systems. We also present the innovative Indian reactor designs which utilize thorium, namely the Advanced Heavy Water Reactor (AHWR) and the Indian High Temperature Reactors.

  7. Advanced nuclear reactor systems - an Indian perspective

    International Nuclear Information System (INIS)

    The Indian nuclear power programme envisages use of closed nuclear fuel cycle and thorium utilisation as its mainstay for its sustainable growth. The current levels of deployment of nuclear energy in India need to be multiplied nearly hundred fold to reach levels of electricity generation that would facilitate the country to achieve energy independence as well as a developed status. The Indian thorium based nuclear energy systems are being developed to achieve sustainability in respect of fuel resource along with enhanced safety and reduced waste generation. Advanced Heavy Water Reactor and its variants have been designed to meet these objectives. The Indian High Temperature Reactor programme also envisages use of thorium-based fuel with advanced levels of passive safety features. (author)

  8. Thorium is an ultimate source of energy

    OpenAIRE

    Kim, HungGeun; Lee, Sangcheol

    2013-01-01

    This article is written for readers to help the understanding of thorium as an alternative source of nuclear energy. Thorium (Thorium) can be applied for reactor fuels and thorium energy development such as ADSR; Accelerator Driven Subcritical Reactor. This particle explains the thorium as a possible choice to replace of uranium to supply enormous energy could be the energy source. A Korean article published in "Science Times" in South Korea. The article is based on an interview ...

  9. Sustainability: role of thorium

    International Nuclear Information System (INIS)

    The task to renew the world's energy infrastructure, where fossil fuels account for 80% of supply, is enormous. The two carbon neutral energy sources - renewable and nuclear - should be the base of the world's future energy mix. Nuclear, however, suffers from a bad public opinion and lack of government support in many parts of the world. We can conclude that the world needs an 'on demand' energy source that is affordable, clean, safe and scalable. Thorium energy could be that energy source. It is the most energy dense solution we know, fitting well to the modular and size-constrained requirements of an urbanizing world. No part of society can create a sustainable world on their own and markets are too slow to drive transformational changes. We need new partnerships between governments, business, civil society and academia where each part is delivering on their specific responsibilities and roles

  10. Thorium nuclear fuel cycle technology

    Energy Technology Data Exchange (ETDEWEB)

    Eom, Tae Yoon; Do, Jae Bum; Choi, Yoon Dong; Park, Kyoung Kyum; Choi, In Kyu; Lee, Jae Won; Song, Woong Sup; Kim, Heong Woo

    1998-03-01

    Since thorium produces relatively small amount of TRU elements after irradiation in the reactor, it is considered one of possible media to mix with the elements to be transmuted. Both solid and molten-salt thorium fuel cycles were investigated. Transmutation concepts being studied involved fast breeder reactor, accelerator-driven subcritical reactor, and energy amplifier with thorium. Long-lived radionuclides, especially TRU elements, could be separated from spent fuel by a pyrochemical process which is evaluated to be proliferation resistance. Pyrochemical processes of IFR, MSRE and ATW were reviewed and evaluated in detail, regarding technological feasibility, compatibility of thorium with TRU, proliferation resistance, their economy and safety. (author). 26 refs., 22 figs

  11. Speeding-up Thorium decay

    CERN Document Server

    Cardone, F; Petrucci, A

    2007-01-01

    We show that cavitation of a solution of thorium-228 in water induces its transformation at a rate 10000 times faster than the natural radioactive decay would do. This result agrees with the alteration of the secular equilibrium of thorium-234 obtained by a Russian team via explosion of titanium foils in water and solutions. These evidences further support some preliminary clues for the possibility of piezonuclear reactions (namely nuclear reactions induced by pressure waves) obtained in the last ten years.

  12. Studies on the production of thorium in nitrate from Eskisehir-Beylikahir thorium ore

    International Nuclear Information System (INIS)

    A large thorium deposit (380.000 tonne ThO2) has been found in Eskisehir-Beylikahir area in Turkey. Representative sample of 1000 Kg. thorium ore was taken from this deposit for the pre-concentration studies. Thorium pre-concentrate which has 1.41% Th02 grade and minus 0.105 mm. particle size was obtained after the physical treatment tests. Sulphuric acid leach was conducted on the thorium pre-concentrate and the thorium extraction recovery was over 90%. After these leach tests with sulphuric acid, thorium was precipitated as a sulphate from the leach slurry with 96% recovery. Thorium sulphate cake was dissolved in HCl and precipitated with ammonia to give a thorium hydroxide. During this process, aluminium iron and calcium were separated from the thorium. The thorium hydroxide was dissolved in nitric acid and the solution was evaporated to solid thorium nitrate. (author)

  13. Determination of thorium in plutonium-thorium oxides and carbides

    International Nuclear Information System (INIS)

    Thorium is determined in (PuTh)C and (PuTh)O2 by complexometric titration with ethylenediaminetetraacetic acid (EDTA) following separation on anion-exchange resin. Carbides are first oxidized by ignition in air at about 8000C. Oxide or oxidized carbide samples are dissolved in acids by the sealed-reflux technique or by heating in beakers. The plutonium is selectively sorbed from the 12M hydrochloric acid solution of the fuel on a Bio-Rad AG1-X2 anion-exchange resin column, and the eluted thorium is titrated with EDTA using xylenol orange as the indicator. The average recovery of thorium in 20 samples is 99.98% with a relative standard deviation of 0.07%

  14. Thorium Energy for the World

    CERN Document Server

    Revol, Jean-Pierre; Bourquin, Maurice; Kadi, Yacine; Lillestol, Egil; De Mestral, Jean-Christophe; Samec, Karel

    2016-01-01

    The Thorium Energy Conference (ThEC13) gathered some of the world’s leading experts on thorium technologies to review the possibility of destroying nuclear waste in the short term, and replacing the uranium fuel cycle in nuclear systems with the thorium fuel cycle in the long term. The latter would provide abundant, reliable and safe energy with no CO2 production, no air pollution, and minimal waste production. The participants, representatives of 30 countries, included Carlo Rubbia, Nobel Prize Laureate in physics and inventor of the Energy Amplifier; Jack Steinberger, Nobel Prize Laureate in physics; Hans Blix, former Director General of the International Atomic Energy Agency (IAEA); Rolf Heuer, Director General of CERN; Pascal Couchepin, former President of the Swiss Confederation; and Claude Haegi, President of the FEDRE, to name just a few. The ThEC13 proceedings are a source of reference on the use of thorium for energy generation. They offer detailed technical reviews of the status of thorium energy ...

  15. Role of thorium in ensuring long term energy security to India

    International Nuclear Information System (INIS)

    Role of nuclear power in ensuring energy security to the world is inevitable due to a) dwindling fossil fuel resources and b) need for minimising green house gas emission that poses the risk of global climate change. India, keeping in mind its limited uranium and vast thorium resources, is pursuing a three stage nuclear power programme. The first stage is based on reactors that use uranium as fuel. It comprises of the indigenous Pressurised Heavy Water Reactors using natural uranium as fuel and light water reactors that employ enriched uranium as fuel and are to be set up in technical collaboration with other countries. The second stage is based on fast breeder reactors that employ plutonium derived from reprocessing of spent fuel from the first stage reactors. The third stage envisages reactors which will employ thorium based fuel after its irradiation in the second stage reactors. This programme is sequential in nature and has an ultimate objective of securing long term energy security to India through judicial use of its thorium resources. Thorium based reactors offer advantages in terms of better neutronic characteristics of thorium, it being better fertile host for plutonium disposition and better thermo-mechanical properties and slower fuel deterioration of thorium oxide. It is planned to introduce thorium in the Indian Nuclear Power Programme after sufficient (about 200 GWe) capacity build-up in the second stage. DAE is a global leader in the development of the entire thorium fuel cycle. It has a mature technology for extraction of thorium and preparation of thoria pellets. It has long back carried out irradiation of thoria pellets in its research reactors and also in PHWRs, post irradiation examination and reprocessing of irradiated thoria, fabrication of 233U based fuel. It has KAMINI - the world's only operating reactor employing 233U as fuel. An Advanced Heavy Water Reactor (AHWR) has been designed as a technology demonstrator for large scale utilisation

  16. The economics of thorium fuel cycles

    International Nuclear Information System (INIS)

    The individual cost components and the total fuel cycle costs for natural uranium and thorium fuel cycles are discussed. The thorium cycles are initiated by using either enriched uranium or plutonium. Subsequent thorium cycles utilize recycled uranium-233 and, where necessary, either uranium-235 or plutonium as topping. A calculation is performed to establish the economic conditions under which thorium cycles are economically attractive. (auth)

  17. Determination of natural thorium in urines

    International Nuclear Information System (INIS)

    A procedure for the quantitative analysis of thorium in urine is described. After precipitation with ammonium hydroxide, dissolution of the precipitate, extraction at pH 4-4.2 with cupferron in chloroformic solution and mineralization, a colorimetric determination of thorium with thorin is performed. It is thus possible to detect about 2 γ of thorium in the sample. (author)

  18. The occurring forms of thorium and characteristics of thorium mineral of skarn-type thorium deposit in Tranomaro, southern Madagascar

    International Nuclear Information System (INIS)

    In Tranomaro, thorium mineralization mainly occurs in Tranomaro pyroxenite which formed under skarnization and it mainly consists of diopside, scaponite and carbonate. Thorium exists in the form of independent thorium minerals in pyroxene, scapolite, olivine and carbonate, etc. The magnitude of thorium minerals ranges from 0.2 mm to 0.5 mm, which has no other paragenetic and associated metallic mineral. With the assay of electric probe, the main components of thorium minerals are ThO2, UO2 and PbO. According to characteristics of its components and observation under microscope, it's concluded that thorium mineralization mainly contains thorianite and uranothorianite. There is no obvious pyrometasomatic phenomenon in ore. It's inferred that thorium mineralization is formed in the early stage of skarnization. (authors)

  19. Research and development of thorium fuel cycle

    International Nuclear Information System (INIS)

    Nuclear properties of thorium are summarized and present status of research and development of the use of thorium as nuclear fuel is reviewed. Thorium may be used for nuclear fuel in forms of metal, oxide, carbide and nitride independently, alloy with uranium or plutonium or mixture of the compound. Their use in reactors is described. The reprocessing of the spent oxide fuel in thorium fuel cycle is called the thorex process and similar to the purex process. A concept of a molten salt fuel reactor and chemical processing of the molten salt fuel are explained. The required future research on thorium fuel cycle is commented briefly. (T.H.)

  20. Thorium in occupationally exposed men.

    Energy Technology Data Exchange (ETDEWEB)

    Stehney, A. F.

    1999-02-24

    Higher than environmental levels of {sup 232}Th have been found in autopsy samples of lungs and other organs from four former employees of a thorium refinery. Working periods of the subjects ranged from 3 to 24 years, and times from end of work to death ranged from 6 to 31 years. Examination of the distribution of thorium among the organs revealed poor agreement with the distribution calculated from the dosimetric models in Publication 30 of the International Commission on Radioprotection (ICRP). Concentrations in the lungs relative to pulmonary lymph nodes, bone or liver were much higher than calculated from the model for class Y thorium and the exposure histories of the workers. Much better agreement was found with more recently proposed models in Publications 68 and 69 of the ICRP. Radiation doses estimated from the amounts of thorium in the autopsy samples were compatible with health studies that found no significant difference in mortality from that of the general population of men in the US.

  1. Toxicty of thorium cycle nuclides

    International Nuclear Information System (INIS)

    The purpose of this project is to investigate the biological hazards associated with uranium-thorium breeder fuels and fuel recycle process solutions. Initial studies emphasize the metabolism and long-term biological effects of inhaled 233U-232U nitrate and oxide fuel materials andof 231Pa, a major, long-lived, radioactive waste product

  2. Assessment of Thorium Analysis Methods

    International Nuclear Information System (INIS)

    The Assessment of thorium analytical methods for mixture power fuel consisting of titrimetry, X-ray flouresence spectrometry, UV-VIS spectrometry, alpha spectrometry, emission spectrography, polarography, chromatography (HPLC) and neutron activation were carried out. It can be concluded that analytical methods which have high accuracy (deviation standard < 3%) were; titrimetry neutron activation analysis and UV-VIS spectrometry; whereas with low accuracy method (deviation standard 3-10%) were; alpha spectrometry and emission spectrography. Ore samples can be analyzed by X-ray flourescnce spectrometry, neutron activation analysis, UV-VIS spectrometry, emission spectrography, chromatography and alpha spectometry. Concentrated samples can be analyzed by X-ray flourescence spectrometry; simulation samples can be analyzed by titrimetry, polarography and UV-VIS spectrometry, and samples of thorium as minor constituent can be analyzed by neutron activation analysis and alpha spectrometry. Thorium purity (impurities element in thorium samples) can be analyzed by emission spectography. Considering interference aspects, in general analytical methods without molecule reaction are better than those involving molecule reactions (author). 19 refs., 1 tabs

  3. Thorium in occupationally exposed men

    International Nuclear Information System (INIS)

    Higher than environmental levels of 232Th have been found in autopsy samples of lungs and other organs from four former employees of a thorium refinery. Working periods of the subjects ranged from 3 to 24 years, and times from end of work to death ranged from 6 to 31 years. Examination of the distribution of thorium among the organs revealed poor agreement with the distribution calculated from the dosimetric models in Publication 30 of the International Commission on Radioprotection (ICRP). Concentrations in the lungs relative to pulmonary lymph nodes, bone or liver were much higher than calculated from the model for class Y thorium and the exposure histories of the workers. Much better agreement was found with more recently proposed models in Publications 68 and 69 of the ICRP. Radiation doses estimated from the amounts of thorium in the autopsy samples were compatible with health studies that found no significant difference in mortality from that of the general population of men in the US

  4. Radiological significance of thorium processing in manufacturing

    International Nuclear Information System (INIS)

    The study of thorium processing in manufacturing comprised monitoring programs at a plant where thorium dioxide was in use and another where the use of thorium nitrate had been discontinued. The measurements of the solubility in simulated lung fluid proved that both materials belonged in the Y Class with dissolution half-times greater than 500 days. Bioassay measurements of 20 subjects from both facilities proved that in vitro monitoring methods, urine, feces, hair and nails analysis were not sufficient indicators of thorium uptake. In vivo monitoring by phoswich and large sodium iodide detectors were proven to be good methods of determining thorium lung burdens. The thoron in breath technique was shown to have a lower limit of sensitivity than lung counting, however, due to lack of information regarding the thoron escape rate from the thorium particles in the lungs the method is not as accurate as lung counting. Two subjects at the thorium dioxide facility had lung burdens of 21+- 16 Bq and 29+- 24 Bq Th232 and one at the thorium nitrate facility had a lung burden of 37+- 13 Bq. Improvements in the procedures and use of a glove box were among the recommendations to reduce the inhalation of thorium by workers at the thorium dioxide facility. Decontamination of several rooms at the thorium nitrate facility and sealing of the walls and floors were recommended in order to reduce the escape of thoron gas into the room air. The risk to non Atomic Radiation Workers was primarily due to thoron daughters in air while gamma radiation and thorium in air were less important. Conversely, at the thorium dioxide facility the inhalation of thorium in air was the most significant exposure pathway

  5. Implementation strategy of thorium fuel cycle - 005

    International Nuclear Information System (INIS)

    Nuclear power is called again as a countermeasure of climate change recently. Nuclear power does not emit carbon dioxide (CO2) when it generates electricity. However there are still existing concerns such as the nuclear proliferation, long-term radioactive waste. Nuclear power was not included as a technical method of CDM (clean development mechanism) of Kyoto protocol. The use of the thorium is expected to overcome these concerns. Even though thorium utilization was known in the very early stage of nuclear application in 1940's, thorium was not used as primary source due to its lack of fissile material. Plenty amount of plutonium stock in the spent nuclear fuel from more than 50 years operation of the uranium fuel cycle can be used as starter of thorium fuel cycle. Declaration of the 'world without nuclear weapon' by the president Obama will also help to use weapon grade plutonium for starting thorium fuel cycle. In this paper, I will discuss how much amount of thorium cycle can be implemented triggered by the plutonium stock in spent nuclear fuel and by the weapon grade plutonium. Several implementation scenarios of thorium fuel cycle will be considered. Several types of molten-salt reactor were candidates of thorium nuclear power plant. The capacity of the thorium fuel cycle is estimated to be 450 GWe around at 2050. Some additional discussions on reducing carbon dioxide emission will be carried on rare-earth mining and electric vehicle in view of thorium utilization. (author)

  6. Thorium research and development in Turkey

    International Nuclear Information System (INIS)

    Turkey has a great potential regarding thorium resources. Thorium exploration activities have been done in the past mainly by state organizations for determining the thorium resources in Turkey. Thorium occurs as complex mineral together with barite, fluorite and rare earth elements (REE). The increase in global demand for REE creates the opportunity for REE production which will also produce thorium as a by-product. The development of nuclear energy program in Turkey provides the stimulus for research and development activities in nuclear technologies. The final declaration of the workshop emphasizes the importance of thorium reserves in Turkey and the necessity for thorium exploration and development activities in order to determine the feasibility of thorium mining and fuel cycle in Turkey. These activities should be conducted together with the development of technologies for separation of these complex minerals and purification of thorium, REE and other minerals to be utilized as commercial products. There are advanced academic research studies on thorium fuel cycle which should be supported by the industry in order to commercialize the results of these studies. Turkey should be integrated to international R and D activities on ADS which is expected to commercialize on medium term. The legislative framework should be developed in order to provide the industrial baseline for nuclear technologies independent from nuclear regulatory activities

  7. Thorium: Issues and prospects in Malaysia

    Energy Technology Data Exchange (ETDEWEB)

    AL-Areqi, Wadeeah M.; Majid, Amran Ab.; Sarmani, Sukiman; Bahri, Che Nor Aniza Che Zainul [Nuclear Science Programme, School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Malaysia. walareqi@yahoo.com (Malaysia)

    2015-04-29

    In Malaysia, thorium exists in minerals and rare earth elements production residue. The average range of thorium content in Malaysian monazite and xenotime minerals was found about 70,000 and 15,000 ppm respectively. About 2,636 tonnes of Malaysian monazite was produced for a period of 5 years (2006-2010) and based on the above data, it can be estimated that Malaysian monazite contains about 184.5 tonnes of thorium. Although thorium can become a major radiological problem to our environment, but with the significant deposit of thorium in Malaysian monazite, it has a prospect as a future alternative fuel in nuclear technology. This paper will discuss the thorium issues in Malaysia especially its long term radiological risks to public health and environment at storage and disposal stages, the prospect of exploring and producing high purity thorium from our rare earth elements minerals for future thorium based reactor. This paper also highlights the holistic approach in thorium recovery from Malaysian rare earth element production residue to reduce its radioactivity and extraction of thorium and rare earth elements from the minerals with minimum radiological impact to health and environment.

  8. Thorium: Issues and prospects in Malaysia

    Science.gov (United States)

    AL-Areqi, Wadeeah M.; Majid, Amran Ab.; Sarmani, Sukiman; Bahri, Che Nor Aniza Che Zainul

    2015-04-01

    In Malaysia, thorium exists in minerals and rare earth elements production residue. The average range of thorium content in Malaysian monazite and xenotime minerals was found about 70,000 and 15,000 ppm respectively. About 2,636 tonnes of Malaysian monazite was produced for a period of 5 years (2006-2010) and based on the above data, it can be estimated that Malaysian monazite contains about 184.5 tonnes of thorium. Although thorium can become a major radiological problem to our environment, but with the significant deposit of thorium in Malaysian monazite, it has a prospect as a future alternative fuel in nuclear technology. This paper will discuss the thorium issues in Malaysia especially its long term radiological risks to public health and environment at storage and disposal stages, the prospect of exploring and producing high purity thorium from our rare earth elements minerals for future thorium based reactor. This paper also highlights the holistic approach in thorium recovery from Malaysian rare earth element production residue to reduce its radioactivity and extraction of thorium and rare earth elements from the minerals with minimum radiological impact to health and environment.

  9. Safety aspects in thorium mining and milling

    International Nuclear Information System (INIS)

    On account of limited uranium and vast thorium resources, India has adopted a three stage nuclear energy programme wherein initially the existing uranium reserves shall be explored and at later stages the thorium reserves shall be utilized for nuclear power production. Thorium occurs in nature as mineral monazite, which along with other heavy minerals, is found abundantly in the beach sands along the coastal stretches of peninsular India. Recovery of thorium therefore involves mining of beach sands, mineral separation to obtain monazite and its chemical processing to obtain thorium values. The process for recovery of thorium involve both radiological as well as conventional hazards. This paper highlight's the issues related to Radiological Hazards, Conventional Hazards, Waste Management and Regulatory Control. The radiological safety provisions in the thorium mining and milling as well as the industrial and fire safety aspects in thorium milling are enforced by the Atomic Energy Regulatory Board (AERB), which is the national regulatory body of India for nuclear and radiation safety. AERB's regulatory oversight span through all consenting stages namely, siting, construction, commissioning, operation and decommissioning. AERB is supported in its work by elaborate committee structure and follows a multi-tier review system of safety committees to carry out review and assessment. The individual doses in thorium mining and milling facilities as well to those of public residing in vicinity of these facilities is well within the specified limits. Industrial and fire safety statistics in thorium mills are also better when compared to similar conventional industries

  10. Abundant thorium as an alternative nuclear fuel

    International Nuclear Information System (INIS)

    It has long been known that thorium-232 is a fertile radioactive material that can produce energy in nuclear reactors for conversion to electricity. Thorium-232 is well suited to a variety of reactor types including molten fluoride salt designs, heavy water CANDU configurations, and helium-cooled TRISO-fueled systems. Among contentious commercial nuclear power issues are the questions of what to do with long-lived radioactive waste and how to minimize weapon proliferation dangers. The substitution of thorium for uranium as fuel in nuclear reactors has significant potential for minimizing both problems. Thorium is three times more abundant in nature than uranium. Whereas uranium has to be imported, there is enough thorium in the United States alone to provide adequate grid power for many centuries. A well-designed thorium reactor could produce electricity less expensively than a next-generation coal-fired plant or a current-generation uranium-fueled nuclear reactor. Importantly, thorium reactors produce substantially less long-lived radioactive waste than uranium reactors. Thorium-fueled reactors with molten salt configurations and very high temperature thorium-based TRISO-fueled reactors are both recommended for priority Generation IV funding in the 2030 time frame. - Highlights: • Thorium is an abundant nuclear fuel that is well suited to three advanced reactor configurations. • Important thorium reactor configurations include molten salt, CANDU, and TRISO systems. • Thorium has important nuclear waste disposal advantages relative to pressurized water reactors. • Thorium as a nuclear fuel has important advantages relative to weapon non-proliferation

  11. Thorium as a nuclear fuel. Chapter 10

    International Nuclear Information System (INIS)

    Thorium-based nuclear power, despite several decades of research and development, has yet to be fully commercialized. In recent years, renewed interest in the potential advantages of thorium-based nuclear power has spurred research and development on several concepts for advanced reactors using thorium fuels, including high-temperature gas-cooled reactors, molten salt reactors, Canada Deuterium Uranium-type reactors, advanced heavy water reactors, fast breeder reactors, and pressurized heavy water reactors. If demand for thorium increases due to favorable reactor designs, then thorium can be supplied through byproduct recovery from deposits mined for other valuable mineral resources. As prominent examples, thorium-bearing monazite ((rare earth elements, Th) PO4) is an accessory mineral in many deposits of rare earth elements and heavy-mineral sands. (author)

  12. Thorium fuel cycle - Potential benefits and challenges

    International Nuclear Information System (INIS)

    There has been significant interest among Member States in developing advanced and innovative technologies for safe, proliferation resistant and economically efficient nuclear fuel cycles, while minimizing waste and environmental impacts. This publication provides an insight into the reasons for renewed interest in the thorium fuel cycle, different implementation scenarios and options for the thorium cycle and an update of the information base on thorium fuels and fuel cycles. The present TECDOC focuses on the upcoming thorium based reactors, current information base, front and back end issues, including manufacturing and reprocessing of thorium fuels and waste management, proliferation-resistance and economic issues. The concluding chapter summarizes future prospects and recommendations pertaining to thorium fuels and fuel cycles

  13. Alternative Thorium fuel cycle for LWRS

    International Nuclear Information System (INIS)

    In the paper, different thorium nuclear fuel cycles are examined and compared under light water reactor conditions, especially VVER-440. Two investigated thorium based fuels include one solely plutonium-thorium based fuel and the second one plutonium-thorium based fuel with initial uranium U-233 content. Both of them are used to carry and burn or transmute plutonium created in the classical UOX cycle. Different thorium fuel distribution in fuel assemblies is modeled - homogeneous and heterogenous. The article shows main features of VVER-440 reactor, analysed fuel assemblies and fuel cycles. Fuel cycles and fissile content in the fuel are tuned to fulfil operating conditions of VVER-440 reactor. The conclusion is concentrated on the rate of Pu transmutation and Pu with minor actinides cumulation in the spent thorium fuel and its comparison to UOX open fuel cycle. (authors)

  14. Antineutrino Monitoring of Thorium Reactors

    CERN Document Server

    Akindele, Oluwatomi A; Norman, Eric B

    2015-01-01

    Various groups have demonstrated that antineutrino monitoring can be successful in assessing the plutonium content in water-cooled nuclear reactors for nonproliferation applications. New reactor designs and concepts incorporate nontraditional fuels types and chemistry. Understanding how these properties affect the antineutrino emission from a reactor can extend the applicability of antineutrino monitoring.Thorium molten salt reactors (MSR) breed U-233, that if diverted constitute an IAEA direct use material. The antineutrino spectrum from the fission of U-233 has been determined, the feasibility of detecting the diversion of a significant quantity, 8 kg of U-233, within the IAEA timeliness goal of 30 days has been evaluated. The antineutrino emission from a thorium reactor operating under normal conditions is compared to a diversion scenario at a 25 meter standoff by evaluating the daily antineutrino count rate and the energy spectrum of the detected antineutrinos. It was found that the diversion of a signifi...

  15. Impact of Thorium Capture Cross Section Uncertainty on the Thorium Utilized ADS Reactivity Calculation

    OpenAIRE

    Thanh Mai Vu; Takanori Kitada

    2014-01-01

    Recently, the researches on fast neutron spectrum system utilized thorium fuel are widely conducted. However, the recent thorium cross section libraries are limited compared to uranium cross section libraries. The impact of thorium cross section uncertainty on thorium fuel utilized accelerator driven system (ADS) reactivity calculation is estimated in this study. The uncertainty of the keff caused by 232Th capture cross section of JENDL-4.0 is about 1.3%. The uncertainty of JENDL-4.0 is neede...

  16. Thorium and the Third Fuel

    Energy Technology Data Exchange (ETDEWEB)

    Dukert, Joseph M.

    1970-01-01

    This booklet discusses energy sources for nuclear power plants. Uranium-235 by itself will not be able to handle the energy needs. The two man-made supplements that can be used for nuclear power plants energy sources are plutonium and uranium-233. Uranium-233 is an isotope that appears as a result of radioactive decay after neutrons have been absorbed in thorium-232. This uranium-233 is called the third fuel.

  17. Performance of Thorium ORGEL Reactor

    International Nuclear Information System (INIS)

    The aim of this paper is to show the general characteristics of a thorium ORGEL reactor. Reference is deliberately made to existing technology or techniques that are easily developable, avoiding any advanced solutions; in particular, the general design of the reactor is entirely similar to one operating on uranium, and includes an organic coolant, a gas-insulation and SAP pressure tube channel, and a continuous fuel cycle with one zone and one type of fuel. The criteria governing the choice of fuel element are reviewed, and an element consisting of a cluster of 37 SAP-clad thorium oxide rods is chosen. The technical and economic performance of the fuel cycle - investment in fissionable material, specific consumption, cost of the cycle - is analysed as a function of various parameters such as lattice pitch, power density and burn-up. For every case considered the uranium is entirely recycled; the supplementary fissionable material is uranium-235. Finally, the performance is compared with that obtained in a uranium reactor, and an analysis is made of the economic conditions under which the thorium cycle would become more advantageous than the uranium. (author)

  18. Thorium fuel cycles in CANDU

    International Nuclear Information System (INIS)

    In recent years, Atomic Energy of Canada Limited has been examining in detail the implications of using thorium-based fuels tn the CANDU reactor. Various cycles initiated and enriched either with fissile plutonium or with enriched uranium, and with effective conversion ratios ranging up to 1.0, have been evaluated. We have concluded that: 1. Substantial quantities of uranium can be saved by adoption of the thorium fuel cycle, and the long-term security of fissile supply both for the domestic and overseas market can be considerably enhanced. The amount saved will depend on the details of the fuel cycle and the anticipated growth of nuclear power in Canada. 2. The fuel cycle can be introduced into the basic CANDU design without major modifications and without compromising current safety standards. 3. The economic conditions that make thorium competitive with the once-through natural uranium cycle depend a the price of uranium and on the costs both to fabricate α and γ-emitting fuels and to either enrich uranium or to extract fissile material from spent fuel. While timing is difficult to predict, we believe that competitive economic conditions will prevail toward the end of this century. 4. A twenty-year technological development program will be required to establish commercial confidence in the fuel cycle. (author)

  19. Thorium-U Recycle Facility (7930)

    Data.gov (United States)

    Federal Laboratory Consortium — The Thorium-U Recycle Facility (7930), along with the Transuranic Processing Facility (7920). comprise the Radiochemical Engineering Development Complex. 7930 is a...

  20. Health effects of industrial exposure to thorium

    International Nuclear Information System (INIS)

    The objective of this project is to determine the health effects of industrial exposure to thorium and the long-term pattern of deposition of inhaled thorium and its daughter products in human tissues. We obtained the study populations from employment records of the Lindsay Chemical Company and its corporate successors. The company was primarily engaged in the extraction of thorium and rare earth chemicals from monazite ores and in the production of thorium-impregnated mantles for gas lamps. From all available records, which date back to 1925, we have identified 3542 male and 1040 female employees. 1 ref

  1. Studies on the preparation of thorium metal sponge from thorium oxalate

    International Nuclear Information System (INIS)

    The results of investigations carried out on the production of high purity thorium metal sponge, starting with thorium oxalate are presented. The flow sheet includes chlorination of thorium oxalate, purification of raw thorium tetrachloride, magnesium reduction of anhydrous thorium tetrachloride, slag metal separation, vacuum distillation for removal of residual MgCl2 and excess magnesium, and consolidation of the metal sponge. Studies have been carried out to investigate the optimum chlorination efficiency and chlorine utilization attainable using different chlorinating agents, and to compare the quality of the sponge obtained with single and double distilled chloride. The overall process efficiency under optimum conditions was 81%. The thorium metal button, prepared from the sponge by arc-melting, analysed : O2 - 847, N2 - 20, C - 179, Mg - 100, Fe - 49, Ni<50, Al - 11, Cr - 7 (expressed in parts per million parts of thorium). The button could be further purified by electron beam melting to improve its ductility. (author)

  2. Possible types of breeders with thorium cycle

    International Nuclear Information System (INIS)

    Neutronics calculations of simplified homogeneous reactor models show the possibility that metal-fueled LMFBRs and coated particle fueled gas cooled reactors achieve reactor doubling times of around 10 years with the thorium cycle. Three concepts of gas-cooled thorium cycle breeders are discused. (Author)

  3. Possible types of breeders with thorium cycle

    International Nuclear Information System (INIS)

    Neutronics calculations of simplified homogeneous reactor models show the possibility that metal-fueled LMFBRs and coated particle fueled gas cooled reactors achieve doubling times of around 10 years with the thorium cycle. Three concepts of gas-cooled thorium cycle breeders are discussed. (Author)

  4. Utilization of thorium in power reactors

    International Nuclear Information System (INIS)

    The IAEA convened a Panel on the utilization of thorium in power reactors from 14 to 18 June 1965. 45 scientists from 14 countries and two international organizations took part in it. The proceedings of the Panel include 23 survey papers and brief reviews which stress the importance of utilizing thorium. A separate abstract was prepared for each of these papers. Refs, tabs, figs

  5. Thorium and health: state of the art

    International Nuclear Information System (INIS)

    This report reviews data available in the literature on the subject: 'thorium and health'. Thorium is a natural radioactive element of the actinide series. It is widely distributed in the earth's crust and 99% is found as isotope thorium-232. Its various uses are explained by its chemical, physical, and nuclear properties. As a potential nuclear fuel, thorium is still in demonstration in pilot scale reactors. But thorium has already multiple and sometimes unknown industrial uses. Some mass market products are concerned like light bulb. This raises the issue of wastes, and of exposures of workers and public. Environmental exposure via food and drink of the general population is low, where as workers can be exposed to significant doses, especially during ore extraction. Data on bio-monitoring of workers and biokinetic of thorium, in particular those provided by ICRP, are gathered here. Studies on health effects and toxicity of thorium are scarce and mostly old, except outcomes of its previous medical use. Studies on other forms of thorium should be undertaken to provide substantial data on its toxicity. Concerning treatment, Ca-DTPA is the recommended drug even if its efficacy is moderate. LiHOPO molecule shows interesting results in animals, and further research on chelating agents is needed. (authors)

  6. Thorium resources and energy utilization (14)

    International Nuclear Information System (INIS)

    After the accident at the Fukushima Daiichi Nuclear Power Station of Tokyo Electric Power Company, thorium reactor has been attracting attention from the viewpoint of safety. Regarding thorium as the resources for nuclear energy, this paper explains its estimated reserves in the whole world and each country, its features such as the situation of utilization, and the reason why it attracts attention now. The following three items are taken up here as the typical issues among the latest topics on thorium: (1) utilization of thorium as a tension easing measure against environmental effects involved in nuclear energy utilization, (2) thorium-based reactor as the next generation type reactor with improved safety, and (3) thorium utilization as the improvement policy of nuclear proliferation resistance. The outline, validity, and problems of these items are explained. Thorium reactor has been adopted as a research theme since the 1950s up to now mainly in the U.S. However, it is not enough in the aspect of technological development and also insufficient in the verification of reliability based on technological demonstration, compared with uranium-fueled light-water reactor. This paper explains these situations, and discusses the points for thorium utilization and future prospects. (A.O.)

  7. Philosophy of future ready thorium reactor designs

    International Nuclear Information System (INIS)

    Due to modest uranium reserves and abundant thorium resources, thorium fuel cycle and thorium based reactors are very important to India. Over a period of time India has developed expertise in all aspects of thorium utilisation starting from mining, metal extraction, fuel fabrication, irradiation in reactors, reprocessing, and recycling the recovered 233U. In-line with the maturing of these technologies, development of innovative and advanced reactors is being pursued. India is developing technologies for thorium based reactors in many configurations, from light water cooled designs to high temperature liquid metal and molten salt cooled options. A research reactor, KAMINI, based on 233U was commissioned at Indira Gandhi Centre for Atomic Research (IGCAR) in Kalpakkam in 1996. This is the only reactor in the world currently operating with 233U based fuel. Advanced Heavy Water Reactor (AHWR) aims at technology development for industrial scale thorium utilisation. Thorium is also planned to be used in the High Temperature Reactors, which hold promise of producing hydrogen as an alternate energy carrier for transport applications, thus ensuring long term energy security. For long-term sustainability, it is envisaged to take full advantage of the unique characteristics of 233U - thorium fuel cycle, through development and deployment of advanced nuclear energy systems, such as molten salt breeder reactors and accelerator-driven sub-critical systems

  8. Recovery of uranium from thorium hydroxide concentrate using circular mixer settler

    International Nuclear Information System (INIS)

    Indian Rare Earths Ltd., a Govt. of India undertaking under administrative control of the Dept. of Atomic Energy (DAE) is engaged in the chemical processing of Monazite to recover rare earths and phosphate values for the last fifty years. The thorium hydroxide along with uranium, the remnant of the above process was stock piled in the silos. There is a huge demand for natural uranium in India to sustain its present as well as future nuclear energy needs and all efforts are being made to recover uranium from various sources to bridge the gap between supply and demand. Rare Earths Division of Indian Rare Earths Ltd. has taken this as a challenge and is making a significant progress in this direction by producing Nuclear Grade Ammonium Diuranate (NGADU) from various secondary sources. The important secondary sources are Thorium hydroxide concentrate (U3O8 - 0.6 to 0.7 %), Magnesium fluoride slag (U3O8 - 4-5 % ), Uranium tetra fluoride concentrate (U3O8 - 25 to 28 %), Niobium and Tantalum ore residue (U3O8 - 4 to 5 %). The present paper describes the commercial process developed by in house R and D wing of Rare Earths Division (RED), Aluva for producing NGADU from thorium hydroxide concentrate. In this process, the thorium concentrate is digested with hydrochloric acid to dissolve all hydroxides of thorium, uranium and rare earths. The mixed Th-U-RE chloride solution is subjected to solvent extraction with tri iso octyl amine (Hostrarex-327) to produce uranyl chloride solution using Circular Mixer Settler. Solvent extraction using Circular Mixer Settler for extraction of uranium is a mile stone in this field. The major advantages of circular mixer settler over the box type mixer settler are higher throughput of aqueous feed (10 m3 per hr) helps in reduction in the operating time and will reduce radioactive exposure to the operating personnel. (author)

  9. Solubility of crystalline thorium dioxide

    International Nuclear Information System (INIS)

    The solubility of thorium oxides of different crystallinity is investigated at 25 C by different experimental approaches. The dissolution of bulk crystalline ThO2(cr) is a very slow process and the Th(IV) concentrations measured after one year at pH 1-3 in 0.1 and 0.5 M HCl-NaCl solutions do not represent equilibrium data. Coulometric titration of thorium nitrate solutions in the low pH range of 1.5-2.5 leads to the formation of microcrystalline ThO2.xH2O(mcr) particles which subsequently agglomerate to a precipitate. The solubility of this solid, in equilibrium with Th4+(aq), is measured from the oversaturation direction. The solubility product is determined to be log K'sp = -49.9±0.4 in 0.5 M NaCl corresponding to log Kspo = -53.2±0.4 (converted to I = 0 with the SIT). It is close to the thermochemical value for ThO2(cr) and about 6 orders of magnitude lower than that of X-ray amorphous Th(IV) hydroxide or hydrous oxide. The differences in the solubility products are discussed with regard to the particle size and compared with analogous data for U(IV), Np(IV) and Pu(IV). Above the threshold of hydrolysis of Th4+ at pH > 2.5, the dissolution of microcrystalline ThO2.xH2O(mcr) is found to be irreversible. In near-neutral to alkaline solutions, the measured thorium concentrations approach those of amorphous Th(OH)4(am). Similar results are obtained with crystalline ThO2(cr) in 0.5 M NaCl-NaOH solutions. The solubility is not controlled by the bulk crystalline solid but by amorphous fractions on the surface. (orig.)

  10. Thorium: physicochemistry, pathophysiology, risks and prevention

    International Nuclear Information System (INIS)

    A contrast medium containing radioactive thorium (Thorotrast) was widely used in many countries from 1928 to 1950. This compound is associated with the occurrence after several decades of malignant tumors, in particular of the liver. Such tumors are still reported occasionally. The colloidal granules of metallic thorium accumulated in target organs (liver, kidney), subjecting them to high levels of alpha radiation. The reticular deposits of thorium granules can be seen clearly on roentgenograms and should be looked for routinely in patients with a history of injection of a contrast medium before 1950. Removal of the deposits in asymptomatic patients can be beneficial. Thorotrast-associated cancers have received little media coverage, in contrast with a recent case in a scrap metal merchant who took apart the wreck of a Mirage F1 plane with thorium-magnesium alloy parts. The risks related to exposure to thorium and preventive strategies are discussed. (author). 20 refs., 4 tabs

  11. Low energy neutron data relating to thorium

    International Nuclear Information System (INIS)

    As thorium fuel cycle had some elements useful for effective application of nuclear fuel resource and nonproliferation, it had been much focussed by Carter political power borne in 1976. Because of this factor, a number of experiments and research actions had been promoted to nuclear data on thorium isotopes among 10 years after then. By aging this a moment, the thorium research in Japan showed a remarkable advancement. Difficulties of the thorium experiment at a viewpoint of nuclear experiment, are high radiation dose in its handling and experiment, high background on its experiment and regulation at its use for a nuclear fuel substance. In this paper, after the special research on energy, three examples with much interests were introduced among nuclear experimental data on thorium series against the low energy neutron by using electron accelerator at the Research Reactor Institute, Kyoto University. (G.K.)

  12. Thorium isotopes in human tissues

    Energy Technology Data Exchange (ETDEWEB)

    Stehney, A.F.; Lucas, H.F.

    1991-12-31

    Concentrations of {sup 232}Th and activity ratios of {sup 228}Th to {sup 232}Th and {sup 230}Th to {sup 232}Th were determined in autopsy samples from five former employees of a thorium refinery. The ranges of {sup 232}Th activity concentrations (mBq g{sup {minus}1}) were 0.17--94 in lungs, 3.9--1210 in pulmonary lymph nodes, 0.14--1.19 in bones, 0.015--0.68 in liver, 0.97--5.8 in spleen, and 0.009--0.068 in kidneys. These concentrations are 10 to 1000 times greater than have been reported for persons not occupationally exposed to Th. In most of the samples, the ratios of {sup 230}Th to {sup 232}Th and {sup 228}Th to {sup 232}Th activity at death of the subject were 0.1--0.2 and 0.2--0.4, respectively. Thorium-228 to {sup 228}Ra activity ratios ({plus_minus} standard errors) of 0.86 {plus_minus} 0.11 in lungs and 1.18 {plus_minus} 0.13 in lymph nodes of one subject were obtained by calculation from ratios of {sup 228}Th to {sup 232}Th.

  13. Thorium inorganic gels and phosphoric complexes

    International Nuclear Information System (INIS)

    To get a better understanding of inorganic transparent gels formation in phosphonitric aqueous solutions obtained by mixing a thorium nitrate solution (10-2 to 5 x 10-1 M) with a phosphoric acid solution (1.33 more concentrated) at pH 0.5 to 1, we investigated the complexing of thorium in this medium. As nitrate ions are very weak complexing agents, only phosphate ions have been studied in the thorium phosphate complexes formation. The phosphoric medium have been defined by two independant parameters CTh and pH. The actual H3PO4 concentration at the equilibrium: [H3PO4] determines, with the pH conditions, the thorium complexes formation. Nevertheless, this free phosphoric acid concentration is less than 0.5 M, which corresponds to the upper value that could be reach by [H3PO4] if thorium ions were not complexed at pH 1.5. Thorium complexes have been identified and their equilibrium constant formation have been calculated from extrapolated data obtained at tracers scale with a radioactive thorium isotope: Th-227. These data have been obtained in phosphoric medium defined by [H3PO4]=2 M and 0.7Th and pH values

  14. Harnessing thorium for nuclear power: challenges ahead

    International Nuclear Information System (INIS)

    There are several barriers to rapid growth of nuclear power. These arise as a result of concerns related to possible disasters arising out of severe accidents like Chernobyl and Fukushima, nuclear weapons proliferation, long term radioactive waste disposal etc. It is well known that use of thorium can actually address several of these concerns in a significant way. With developments in nuclear fuel technology, it is now possible to realise these gains through the use of thorium-LEU mixed fuel even in existing reactor systems without losing out too much on energy output from mined uranium in comparison to contemporary uranium fuelled reactor systems. Thorium thus offers an opportunity to facilitate a more rapid growth even with existing proven nuclear reactor designs while evolution of more optimum specific thorium reactor designs takes place. India with its experience base with thorium, while moving ahead with her domestic programme to evolve thorium reactor technology, could do well to facilitate growth of nuclear power through the use of thorium in currently established nuclear reactor designs. The presentation would discuss some of these possibilities

  15. On the assessment of the thorium cycle

    International Nuclear Information System (INIS)

    The high costs in the development of nuclear power have made it unpracticable to develop the uranium cycle and the thorium cycle simultaneously. Increasing awareness of the limited resources seems to cause a change of attitude towards the use of thorium. In the long run the thorium cycle can provide better fuel utilization than the uranium cycle. Commerzialization of the thorium cycle would give added flexibility to the world's nuclear industry in dealing with the delay in FBR introduction. Furthemore the thorium fuel cycle can reduce power costs under certain circumstances, particularly at higher U308-prices. The combination of converter and breeder to a symbiotic system appears to provide an attractive model to meet global energy needs in future. Since the thorium cycle involves recycling of bred 233U, remote refabrication will be required. Vibro-compaction of bulk-fuel, especially the sphere-pac-process for fabrication of fuel elements has attracted special attention because it comprises fewer mechanically intensive process steps than pellet technology. Owing to the high thermal stability of thorium, the advantages of metallic fuel may be used, but commonly oxide fuel will be preferred since the technology is well known. (author)

  16. Migration of uranium and thorium: exploration significance

    International Nuclear Information System (INIS)

    This presentation deals with the problems and progress of radioelement geology and exploration. The ways in which uranium in the earth's crust might concentrate into economic deposits are discussed, and what industry can expect from any given exploration effort for uranium and thorium is considered. The idea is advanced that, in most past exploration, too much geologic thought has been channeled to one or two known types of uranium deposits. There are 16 chapters in this publication, entitled: Introduction; Fundamental Sources of Uranium and Thorium; Goechemistry of Uranium and Thorium; Mechanisms of Uranium and Thorium Transfer to the Crust; Diatreme Feeding of Uranium; Migration of Mantle-Derived Uranium and Thorium within the Crust; Shallow uranium Mobilization Processes; Fixation of Uranium; Cycles of Uranium and Thorium; Oceanic Migration History of Uranium and Thorium, Orogenic Continental-Margin History; Taphrogenic Continental-Margin History; Craton History; Geochemical Distinction of Uranium Mineralization Processes; Underemphasized Processes of uranium Mineralization; and Conclusions. An extensive bibliography is appended, followed by a computerized KWIC-type index

  17. Pressurized water reactor thorium fuel cycle studies

    International Nuclear Information System (INIS)

    The use of a thorium fuel cycle in a PWR is studied. The thorium has no fissile isotope and a fissile nuclide must be added to the thorium fuel. This nuclide can be uranium 235, plutonium 239 or uranium 233. In this work we have kept the fuel assembly geometry and the control rod system of an usual PWR. Cell calculations showed that the moderation ratio of an usual PWR can be used with uranium 235 and plutonium 239 fuels. But this moderation ratio must be decreased and accordingly the pumping power must be increased in the case of a uranium 233 fuel. The three fuels can be controlled with soluble boron. The power distribution inside an assembly agrees with the safety rules and the worth of the control rods is sufficient. To be interesting the thorium fuels must be recycled. Because the activity and the residual power are higher for a thorium fuel than for a uranium fuel the shielding of the shipping casks and storage pools must be increased. The Uranium 235-Thorium fuel is the best even if it needs expensive enrichment work. With this type of fuel more natural uranium is saved. The thorium fuel would become very interesting if we observe again in the future an increase of the uranium cost

  18. Impact of Thorium Capture Cross Section Uncertainty on the Thorium Utilized ADS Reactivity Calculation

    Directory of Open Access Journals (Sweden)

    Thanh Mai Vu

    2014-01-01

    Full Text Available Recently, the researches on fast neutron spectrum system utilized thorium fuel are widely conducted. However, the recent thorium cross section libraries are limited compared to uranium cross section libraries. The impact of thorium cross section uncertainty on thorium fuel utilized accelerator driven system (ADS reactivity calculation is estimated in this study. The uncertainty of the keff caused by 232Th capture cross section of JENDL-4.0 is about 1.3%. The uncertainty of JENDL-4.0 is needed to be enhanced to provide more reliable results on reactivity calculation for the fast system. The impact of uncertainty of  232Th capture cross section of ENDF/B-VII is small (0.1%. Therefore, it will cause no significant impact of the thorium cross section library on the thorium utilized ADS design calculation.

  19. Nuclear power from thorium - different approaches

    International Nuclear Information System (INIS)

    The importance of thorium for sustainability of nuclear power has been recognized way back in 1950's. High abundance in nature, a higher neutron yield per fission over a wide range of neutron energy (in the thermal and epithermal range), single valency of thorium which leads to higher stabilities of it's compounds and much reduced production of long lived radioactive waste in the Th-233U fuel cycle have made thorium a very attractive source material for generation of nuclear energy. The thorium based fuel cycle is associated with the generation of 232U. Some of the daughter products of 232U have short half-lives and emit strong gamma rays. Therefore, 233U related activities such as fuel fabrication and subsequent fuel handling would need shielding and remote access. The first part of the paper will summarize the basic advantages and associated problems with the operation of thorium fuel cycle. Thorium being a fertile material, it's utilization in the power generation program requires judicious adoption of appropriate fuel cycles. Different approaches for thorium utilization in solid fuelled, molten salt and accelerator driven subcritical reactor and their merits and demerits will be discussed. The scientific issues connected with thorium in heavy water and light water reactors have been examined in terms of in-situ burning of 233U, saving in uranium, Pu generation, enhancement of burn up, and reprocessing challenges. Based on the analyses it has been argued that for a country such as India where the fissile inventory is not large and the policy of closed fuel cycle is adopted, an early introduction of thorium can only reduce uranium consumption to a limited extent. However, for gaining experience in thorium fuel cycle and for evaluating performance of thorium based fuel experimental irradiation of such fuels of different compositions are in progress. Molten salt reactors are quite promising for Th-233U fuel cycles both from safety and fissile

  20. Thorium utilization in Candu reactors

    International Nuclear Information System (INIS)

    In this study, means of thorium utilization in a CANDU reactor are considered. A once through thorium-DUPIC cycle is analyzed in detail. CANDU has the best neutron economy among the commercially available power reactors, which makes it suitable for many different fuel cycle options. A review of the available fuel cycles is also done in the scope of this study to select an economically viable cycle which does not impose profound changes in the neutronic properties of the core that require remodeling of core and related systems. To create a good model ot the CANDU core for the necessary calculations, the steady state properties of CANDU reactor are analyzed. It is assumed that approximation ot refueling as moving the bundles at a constant velocity is valid. This approximation leads to a corollary; The average cross sections of two adjacent bidirectionally refueled channels are independent of axial location. This is also veritied. A result of this corollary the CANDU core can be modeled only in radial direction in cylindirical geometry. The steady state CANDU core model is prepared using the actual power values and these values are sought in the results. The control systems which effect the neutron flux shape are introduced into the model later in the form of additional absorption cross section and lower diffusion coefficient. The results are in good agreement with the actual values. Several different thorium-DUPIC fuel bundle configurations are considered and the one with 12 Th02 elements in the third ring is found to have similar burnup dependent cross-sections and location infinite multiplication factors. Using the model created, the bundle is tested also in the tull core model and it is tound that this bundle configuration complies with the current refueling scheme. That is, no changes are necessary in the refuelind rate or the control systems. A higher conversion ratio of 0.82 is attained, while the excess reactivity of the core is found to decrease by 0.01 Ak

  1. Thorium based fuel for AHWR

    International Nuclear Information System (INIS)

    Advanced Heavy Water Reactor (AHWR) is a 300 MWe, thoria fuel based, vertical pressure tube type reactor designed at BARC. It is heavy water moderated and boiling light water cooled reactor that has been designed for hundred years of plant life. The reactor design has evolved from the presently operating PHWRs and BWRs in India. AHWR has extensive deployment of passive safety features for its operation and accident mitigation at par with the present international standards and provides a robust design against external as well as internal threats. The physics design ensures inherent safety characteristics of the reactor. Heat removal from the core under both normal full power operating condition as well as shutdown condition is by natural circulation of water coolant. The physical characteristics of Thoria based fuel offer potential for high performance in reactor and slower fuel deterioration. With inherent feature of fuel cycle flexibility, a variety of fuel-types could be used in AHWR for generating power efficiently. AHWR-Pu version makes use of (Th-Pu) MOX and (Th-233U) MOX fuel in the closed fuel cycle mode. The adoption of the closed thorium fuel cycle on an industrial scale is for the first time and is important in view of very little global experience. The experience generated on the various fuel cycle activities will be useful in utilisation of the large thoria reserves as envisaged in India's three-stage nuclear power programme. This paper provides an overview of the various design aspects of the thorium based fuel for AHWR and its associated developmental activities. (author)

  2. Nuclear physics: Elusive transition spotted in thorium

    Science.gov (United States)

    Safronova, Marianna

    2016-05-01

    The highly precise atomic clocks used in science and technology are based on electronic transitions in atoms. The discovery of a nuclear transition in thorium-229 raises hopes of making nuclear clocks a reality. See Article p.47

  3. Measurement of lymphoblastogenic activity from thorium workers

    International Nuclear Information System (INIS)

    Mitogenic stimulation of peripheral blood lymphocyte cultures obtained from 36 thorium workers was studied to determine whether the response of these cells was affected by the individuals' occupational exposure to alpha irradiation. The standard assay involved incubating 2 x 105 lymphocytes per test well 72 hours in the presence of phytohemagglutinin (PHA), concanavalin A (Con A) or pokeweed mitogen (PWM). The results showed that there was a significant decrease in lymphocyte responsiveness of former thorium workers grouped by decade of life when compared with controls of the same decade of life for each mitogen tested with the exceptions of PHA in the 41-50 age group and PWM in the 51-60 age group. We are unable to correlate the decreased response observed with the measured body burdens, external gamma exposure, or thoron exhalation rates in these thorium cases. However, other occupational exposures (i.e., various chemicals used in processing thorium) cannot be eliminated as a possible cause. (author)

  4. Thorium exposure in a niobium mine

    International Nuclear Information System (INIS)

    The workers involved in the mineral process to obtain Nb-Fe alloy are exposure to thorium. Internal contamination with radioactive materials is a common problem. This is caused by presence of U and Th and their natural decay series associated with the mine ore. The examples are the workers at the niobium mine located in the state of Goias. Twenty mine workers were evaluated using in vitro bioassay techniques. Samples of urine and feces from occupationally exposed mine workers were analyzed for thorium isotopes. The fecal samples corresponding to one complete excretion and urine sample corresponding to a 24 hours collection were analyzed using alpha spectrometry. The results of thorium excretion (feces) have shown that in all the samples the 228 Th excretions in high than 232 Th. Thorium concentration in all the urine samples were below limit of detection that is approximately 1 mBq/l. (author). 3 refs., 1 fig., 1 tab

  5. Parametric study of a thorium model

    International Nuclear Information System (INIS)

    Models for radionuclides distribution in the human body and dosimetry involve assumptions on the biokinetic behavior of the material among compartments representing organs and tissues in the body. One of the most important problem in biokinetic modeling is the assignment of transfer coefficients and biological half-lives to body compartments. In Brazil there are many areas of high natural radioactivity, where the population is chronically exposed to radionuclides of the thorium series. The uncertainties of the thorium biokinetic model are a major cause of uncertainty in the estimates of the committed dose equivalent of the population living in high background areas. The purpose of this study is to discuss the variability in the thorium activities accumulated in the body compartments in relation to the variations in the transfer coefficients and compartments biological half-lives of a thorium-recycling model for continuous exposure. Multiple regression analysis methods were applied to analyze the results. (author)

  6. The environmental behaviour of uranium and thorium

    International Nuclear Information System (INIS)

    Uranium and thorium have had many uses in the past, and their present and potential use as nuclear fuels in energy production is very significant. Both elements, and their daughter products, are of environmental interest because they may have effects from the time of mining to the time of ultimate disposal of used nuclear fuel. To assess the impact on the environment of man's use and disposal of uranium and thorium, we must know the physical, chemical and biological behaviour of these elements. This report summarizes the literature, updating and extending earlier reviews pertaining to uranium and thorium. The radiological properties, chemistry, forms of occurrence in nature, soil interactions, as well as distribution coefficients and mode of transport are discussed for both elements. In addition, uranium and thorium concentrations in plants, plant transfer coefficients, concentrations in soil organisms and methods of detection are summarized. (auth)

  7. Self-Sustaining Thorium Boiling Water Reactors

    OpenAIRE

    Ehud Greenspan; Jasmina Vujic; Francesco Ganda; Arias, Francisco J.

    2012-01-01

    A thorium-fueled water-cooled reactor core design approach that features a radially uniform composition of fuel rods in stationary fuel assembly and is fuel-self-sustaining is described. This core design concept is similar to the Reduced moderation Boiling Water Reactor (RBWR) proposed by Hitachi to fit within an ABWR pressure vessel, with the following exceptions: use of thorium instead of depleted uranium for the fertile fuel; elimination of the internal blanket; and elimination of absorber...

  8. Technology assessment of near-term open-cycle thorium-fuelled nuclear energy systems

    International Nuclear Information System (INIS)

    As part of the RCUK-India civil nuclear research collaboration, British and Indian researchers have sought to determine the advantages, disadvantages, and viability of open-cycle thorium-uranium fuelled (Th-U-fuelled) nuclear energy systems. The research centred on fuel cycle modelling and life-cycle assessment of three Th-U-fuelled nuclear energy systems and compared these to a reference uranium-fuelled nuclear energy system, all operating with open nuclear fuel cycles. The results indicate that thorium-based fuels offers little benefit over conventional uranium fuelled approaches for open-cycle nuclear energy production. This paper provides an overview on the project and stresses over-arching conclusions. (author)

  9. Thorium utilization in a pebble bed reactor

    International Nuclear Information System (INIS)

    Thorium reserves in the earth's crust are much more than those of uranium, which today measure about 1.5 million tonnes of reasonably assured resources, plus 3 million tonnes of estimated additional resources. These large amount of thorium reserves, also available in Turkey encourages to focus on the utilization of thorium. The most remarkable applications of the use of thorium have been in high temperature reactors. The high temperature pebble bed reactor, which has been chosen as the basis for this study, is a close approximation of the thorium utilizing German reactor THTR. Pebble bed reactors have some unique features which are suitable to burn thorium. (i) The fuel is loaded in the form of coated particles, which are embedded in the graphite matrix of the fuel pebbles, allowing exceptionally high heavy metal burnups; and (ii) the continuous (on-line) fuel loading allows a high utilization factor. The criticality search of the pebble bed reactor is computed by the use of the SCALE4.4 code, CSASIX and KENOVa modules. And the in-core fuel management is computed via SCALE4.4 code, ORIGEN-S module

  10. Thorium residuals in West Chicago, Illinois

    International Nuclear Information System (INIS)

    Lindsay and Company began operation of its west Chicago, Illinois, plant in 1931, processing thorium ores for thorium and rare earths. From that time until normal operations ceased in 1973, thorium residuals from the operation found their way offsite to Reed-Keppler City Park, the West Chicago Sewage Treatment Plant, and numerous other locations about the city and its environs. The present study located and identified such thorium residuals in the West Chicago area, a total of 75 epicenters having been found in addition to deposits at Reed-Keppler Park, the sewage-treatment plant, and down Kress Creek and the DuPage River. Deposits proved to be almost exclusively the dense, gray, insoluble particles of thorium-ore tailings from the process, which have been historically stored in two large piles in the site waste area. Epicenter locations and associated radiological parameters are given for the 75 locations, along with quantitative descriptions of the larger collections of material at the park, at the sewage-treatment plant, and on the banks of Kress Creek and the DuPage River. Not one of the areas of thorium residuals located outside security fences was found to violate the requirements of 10 CFR 20

  11. Quinoline-8-ol modified cellulose as solid phase extractant (SPE) for preconcentrative separation and determination of thorium(IV)

    International Nuclear Information System (INIS)

    Cellulose has been functionalized by coupling with 5-chloro-quinoline-8-ol in the presence of alkali. The resulting polymer material has been characterized by IR spectra and has been used for preconcentrating thorium prior to its determination by spectrophotometry. The optimum pH value for quantitative extraction is 5.0-7.0 and can be eluted with 5 cm3 of 1 mol dm-3 of HCl. The retention capacity of the quinoline-8-ol modified cellulose is 20.0 mg g-1. The effect of various cations, anions and neutral electrolytes on the preconcentration of thorium in conjunction with the determination procedure has been studied and we have found that none of interferents including uranium (up to 10 fold amounts) interfere. The enrichment factor for preconcentration of thorium was found to be 200. Ten replicate determinations of 10 μg of thorium (IV) present in 1 dm3 of sample gave a mean absorbance of 0.084 with a relative standard deviation 1.52%. The detection limit (corresponding to three times the standard deviation of the blank) was found to be 2 μg dm-3. The thorium content of mixed rare earth chloride solution obtained from Indian Rare Earths Limited (IRE), India was estimated by using quinoline-8-ol immobilized cellulose for preconcentration and subsequent determination by spectrophotometry. (orig.)

  12. Recovery of uranium and thorium from uranium-thorium mixture by extraction-stripping

    International Nuclear Information System (INIS)

    An experiment has been conducted for the recovery of uranium and thorium from uranium-thorium mixture by extraction-stripping method. Thorium is one of the fission products of irradiated uranium fuel. This experiment aims to recover both uranium and thorium to be fed back as fuel. The samples for the extraction-stripping of uranium-thorium was made by varying mixtures of uranium-thorium for simulation, i.e. 5% U, 10% U, 15% U, 20% U, and 25% U, with a variation of extractant TBP of 25%, 30%, 35%, 40%, 48%, 60%, and 70%, while the amount/percentage of kerosene used as a diluent was in adjustment with the TBP percentage used. The stripping of the extracted product was done by using hot water at a temperature of 70°C with variation of nitric acid. The experimental results shows that uranium content of 93.6924% was obtained by TBP/kerosene composition of 30%/70% and 92.0754% thorium was obtained for TBP/kerosene composition of 48%/52%. The stripping results show that 98.6392% of thorium was obtained for stripping using hot water at 60-70°C with 0.6 N acidity, while 88.9873% of uranium was recovered for acidity of 0.5 N. (author)

  13. Recovery of rare earths from thorium hydroxide concentrate by preferential oxalate precipitation of thorium

    International Nuclear Information System (INIS)

    The paper describes the details of the simple process developed by in house R and D wing of Rare Earths Division (RED). The process is based on the preferential precipitation of thorium as oxalate in presence of rare earths at an acidity of 1.8-2 N hydrochloric acid. Thorium is preferentially precipitated from the uranium lean RE-Th chloride solution as thorium oxalate by adding stoichiometric quantity of solid oxalic acid. The thorium oxalate having about 95-97 % purity is stored in silos for future use in nuclear reactors. The acidity (2.5 N) of the RE chloride solution is neutralized with caustic lye to pH-3 in order to eliminate traces of dissolved thorium. The weak RE chloride solution having 20-25 g/l R2O3 is converted to RE carbonate using sodium carbonate. The leached RE carbonate slurry is filtered in agitated nutsh filter to produce RE carbonate

  14. Transformation of thorium sulfate in thorium nitrate by ion exchange resin

    International Nuclear Information System (INIS)

    A procedure for transforming thorium sulfate into thorium nitrate by means of a strong cationic ion exchanger is presented. The thorium sulfate solution (approximately 15 g/L Th (SO4) 2) is percolate through the resin and the column is washed first with water, with a 0,2 M N H4 OH solution and then with a 0.2 M N H4 NO3 solution in order to eliminate sulfate ion. Thorium is eluted with a 2 M solution of (N H4) 2 CO3. This eluate is treated with a solution of nitric acid in order to obtain the complete transformation into Th (NO3) 4. The proposed procedure leads to good quality thorium nitrate with high uranium decontamination. (author)

  15. Thorium research activities in Japan

    International Nuclear Information System (INIS)

    The nuclear energy policy in Japan is based on the Uranium-Plutonium fuel cycle with Light Water Reactors (LWR) and Fast Breeder Reactors (FBR). After the accident at Fukushima-Daiichi Nuclear Power Plant, the Japanese government recognizes the importance to ensure the flexibility for future nuclear power generation and then, it was specified in the latest Japanese strategic energy plan. Two research groups related to thorium fuelled nuclear systems and fuel cycle was set up in the Atomic Energy Society of Japan in 2013. One is a 'Research Committee on Nuclear Applications of Molten Salt'. The committee was established to discuss the current molten-salt technology including molten-salt cooled reactor, molten-salt fuelled reactor, accelerator driven system, fusion reactor blankets and dry reprocessing processes. Throughout two years discussion, the committee summarizes a current state of the art and issues of molten-salt application systems. Committee also discussed the handling technologies for molten-salt reactors especially in China and United Kingdom, issues of molten-salt application to fusion reactor, dry reprocessing of spent nuclear fuel, and non-nuclear application of molten-salt. Term of the committee will be extended for further research activities

  16. Uranium and thorium raw materials

    International Nuclear Information System (INIS)

    The main source of low-cost uranium reserves is found in sandstones, notably in the Colorado-Wyoming uranium province of the USA, though vein-type deposits have been developed in Australia. Other main categories of deposit also reviewed include quartz-pebble conglomerates, quartz alkali-feldspar pegmatites and nepheline syenites. The technology for the discovery of uranium still mainly rests on detecting the gamma radiation associated with the 238U decay series. Geiger-Mueller counters have, however, been effectively superseded by scintillation counters and gamma spectrometers. Additionally, increasingly sensitive geochemical methods have been developed, which show considerable future potential. Other promising future techniques include the use of thermal sensors, to measure radiogenic heat, and of enhanced Landsat imagery. Identified uranium resources are quite substantial compared with present production rates, but there may be significant constraints on the rate at which production can be expanded to meet future demands unless there continue to be substantial new discoveries of low-cost resources, and much may depend on the development of new prospecting methods. Finally, a brief look is taken at thorium production, noting that, while identified reserves are limited, there is no doubt that they could be greatly increased in response to an increased demand. (author)

  17. Competitive biosorption of thorium and uranium by actinomycetes

    International Nuclear Information System (INIS)

    The competitive biosorption of thorium and uranium by actinomycetes was examined. Of the actinomycetes tested, Streptomyces levoris showed the highest ability to sorb both thorium and uranium from aqueous systems. Thorium sorption was not affected by co-existed uranium, while uranium sorption was strongly hindered by co-existed thorium. The amounts of both thorium and uranium sorbed by Streptomyces levoris cells increased with an increase of the solution pH. Although the equilibrium isotherm of uranium biosorption is in similar manner as that of thorium biosorption, uranium was sorbed much faster than thorium. Biosorption isotherm of each metal ion could be well fitted by Langmuir isotherm taking the ionic charge of metal ions into account. The Langmuir isotherm for binary system did not explain completely the competitive biosorption of thorium and uranium by Streptomyces levoris. However, the results suggested that the ion species of both metals in the cells should be Th(OH)22+ and UO22+, respectively. (author)

  18. Vil løyse global energikrise med thorium

    CERN Multimedia

    Aure, Gyri

    2007-01-01

    A professor from Bergen claims thorium can contribute to save the world from a global energy crisis. He wants Norway to construct the first accelerator driven reactor in the world powered by thorium. (5 pages)

  19. Moving towards sustainable thorium fuel cycles

    International Nuclear Information System (INIS)

    The CANDU reactor has an unsurpassed degree of fuel-cycle flexibility as a consequence of its fuel-channel design, excellent neutron economy, on-power refueling, and simple fuel bundle design. These features facilitate the introduction and full exploitation of thorium fuel cycles in CANDU reactors in an evolutionary fashion. Thoria (ThO2) based fuel offers both fuel performance and safety advantages over urania (UO2) based fuel, due its higher thermal conductivity which results in lower fuel-operating temperatures at similar linear element powers. Thoria fuel has demonstrated lower fission gas release than UO2 under similar operating powers during test irradiations. In addition, thoria has a higher melting point than urania and is far less reactive in hypothetical accident scenarios owing to the fact that it has only one oxidation state. This paper examines one possible strategy for the introduction of thorium fuel cycles into CANDU reactors. In the short term, the initial fissile material would be provided in a heterogeneous bundle of low-enriched uranium and thorium. The medium term scenario uses homogeneous Pu/Th bundles in the CANDU reactor, further increasing the energy derived from the thorium. In the long term, the full energy potential from thorium would be realized through the recycle of the U-233 in the used fuel. With U-233 recycle in CANDU reactors, plutonium would then only be required to top up the fissile content to achieve the desired burnup. (author)

  20. Determination of boron spectrophotometry in thorium sulfate

    International Nuclear Information System (INIS)

    A procedure for the determination of microquantities of boron in nuclear grade thorium sulfate is described. The method is based on the extraction of BF-4 ion associated to monomethylthionine (MMT) in 1,2 - dichloroethane. The extraction of the colored BF-4-MMT complex does not allow the presence of sulfuric and phosphoric acids; other anions interfere seriously. This fact makes the dissolution of the thorium sulfate impracticable, since it is insoluble in both acids. On the other hand, the quantitative separation of thorium is mandatory, to avoid the precipitation of ThF4. To overcome this difficulty, the thorium sulfate is dissolved using a strong cationic ion exchanger, Th4+ being totally retained into the resin. Boron is then analysed in the effluent. The procedure allows the determination of 0.2 to 10.0 microgramas of B, with a maximum error of 10%. Thorium sulfate samples with contents of 0.2 to 2.0μg B/gTh have being analysed

  1. PWR and WWER thorium cycle calculation

    International Nuclear Information System (INIS)

    The first step of the investigation of the thorium fuel cycle with HELIOS 1.8 is validation of the results obtained from the code for this particular type of fuel. To complete this first task we performed calculation of the benchmark announced by IAEA in 1995. The benchmark was based on a simplified PWR model of the assembly with reduced fuel composition. This calculation was focused on a comparison of the methods and basic nuclear data. After successful validation of the code we focused our work on calculating the PWR and WWER thorium fuel cycles. The thorium cycle begins after the first use of UO2 fuel in the reactor as separation of plutonium from the burnt fuel. Separated plutonium is mixed with thorium and used as a new nuclear fuel in the reactor. For our calculation we prepared two variants of the assembly - the first variant is a homogeneous distribution and the second one is a non-homogenised distribution of thorium fuel in the assembly. The model of non-homogenised distribution of Pu-Th fuel was designed by replacing selected rods of the classical UO2 assembly by Pu-Th rods. These selected rods are distributed symmetrically in the assembly. Other rods in the assembly remain the same as in the classical UO2 assembly. The calculated and compared values are criticality and fuel composition as a function of burnup (Authors)

  2. Thorium: Does Crustal Abundance Lead to Economic Availability?

    OpenAIRE

    Brett W. Jordan; Rod Eggert; Brent Dixon; Brett Carlsen

    2014-01-01

    Recently, interest in thorium's potential use in a nuclear fuel cycle has been renewed. Thorium is more abundant, at least on average, than uranium in the earth's crust and, therefore, could theoretically extend the use of nuclear energy technology beyond the economic limits of uranium resources. This paper provides an economic assessment of thorium availability by creating cumulative-availability and potential mining-industry cost curves, based on known thorium resources. These tools provide...

  3. Composition of hydroponic medium affects thorium uptake by tobacco plants

    OpenAIRE

    Soudek, P. (Petr); Kufner, D. (Daniel); Petrová, Š. (Šárka); Mihaljevič, M.; Vaněk, T. (Tomáš)

    2013-01-01

    The ability of thorium uptake as well as responses to heavy metal stress were tested in tobacco cultivar La Burley 21. Thorium was accumulated preferentially in the root system. The presence of citric, tartaric and oxalic acids in hydroponic medium increased thorium accumulation in all plant organs. On the other hand, the addition of diamines and polyamines, the important antioxidants in plants, resulted in decrease of thorium accumulation, especially in the root system. Negative correlation ...

  4. Potential synergy: the thorium fuel cycle and rare earths processing

    International Nuclear Information System (INIS)

    The use of thorium in nuclear power programs has been evaluated on a recurring basis. A concern often raised is the lack of 'thorium infrastructure'; however, for at least a part of a potential thorium fuel cycle, this may less of a problem than previously thought. Thorium is frequently encountered in association with rare earth elements and, since the U.S. last systematically evaluated the large-scale use of thorium (the 1970's,) the use of rare earth elements has increased ten-fold to approximately 200,000 metric tons per year. Integration of thorium extraction with rare earth processing has been previously described and top-level estimates have been done on thorium resource availability; however, since ores and mining operations differ markedly, what is needed is process flowsheet analysis to determine whether a specific mining operation can feasibly produce thorium as a by-product. Also, the collocation of thorium with rare earths means that, even if a thorium product stream is not developed, its presence in mining waste streams needs to be addressed and there are previous instances where this has caused issues. This study analyzes several operational mines, estimates the mines' ability to produce a thorium by-product stream, and discusses some waste management implications of recovering thorium. (authors)

  5. Thorium removal by different adsorbents

    Energy Technology Data Exchange (ETDEWEB)

    Metaxas, Michail; Kasselouri-Rigopoulou, Vasilia; Galiatsatou, Polymnia; Konstantopoulou, Cathrine; Oikonomou, Dimitrios

    2003-02-28

    The removal of radiotoxic Th{sup 4+} from aqueous solutions has been explored using two different groups of adsorptive materials (e.g. two activated carbons and four zeolites--two natural and two synthetic). The activated carbons were prepared from solvent extracted olive pulp (SEOP) and olive stone (OS) by a two-step physical activation method with steam. They were characterized by N{sub 2} at 77 K adsorption, Hg porosimetry and by determination of their iodine number. All carbons prepared are of the H-type (e.g. contain mainly basic surface oxides) confirmed by the results of the Boehm's method. The natural zeolites, clinoptilolite (NaCLI) and mordenite (NaMOR), were pretreated with Na{sup +} before the adsorption experiments, while the synthetic ones, NaX and NaA, were provided in their commercial sodium form. The natural zeolites, NaCLI and NaMOR, utilized 11.5 and 38.6% of the theoretical ion-exchange capacity, based on Al content, respectively, while NaX and NaA utilized 41.5 and 45.9%, respectively. The activated carbons showed better removal capability than NaCLI. NaMOR, showed comparable results to the carbon originated from OS, but lower removal capability than the carbon originated from SEOP. The synthetic zeolites showed the highest removal ability for thorium ions due to their increased ion-exchange capacity because of their cleaner and larger framework channels and their higher number of ion-exchange sites. The carbons adsorption capacity mainly depends on the content and nature of functional surface groups. The adsorption data were fitted to Langmuir and Freundlich models. The former achieved best fits and was further applied to obtain the respective Langmuir constant and maximum adsorption capacity for each system.

  6. Reprocessing in the thorium fuel cycle

    International Nuclear Information System (INIS)

    An overview of the authors personal view is presented on open questions in regard to still required research and development work for the thorium fuel cycle before its application in a technical-industrial scale may be tackled. For a better understanding, all stations of the back-end of the thorium fuel cycle are briefly illustrated and their special features discussed. They include storage and transportation measures, all steps of reprocessing, as well as the entire radioactive waste treatment. Knowledge gaps are, as far as they are obvious, identified and proposals put forward for additional worthwile investigations. (orig.)

  7. Competitive biosorption of thorium and uranium by Micrococcus luteus

    International Nuclear Information System (INIS)

    Eighteen species of bacteria were screened for abilities to adsorb thorium and uranium. High adsorption capacity was observed for thorium by Arthrobacter nicotianae and Micrococcus luteus, and for uranium by Arthrobacter nicotianae. The adsorption of both thorium and uranium by Micrococcus luteus cells was rapid, was affected by the solution pH, and obeyed the Langmuir adsorption isotherm for binary systems in a competitive manner taking the ionic charge of the metal ion into account. The thorium selectivity in the competitive adsorption is assumed to be caused by the faster adsorption and the slower desorption rates of thorium than those of uranium. (author)

  8. Isotopic compositions of terrestrial thorium: a search in terrestrial thorium for the unidentified excess 4.6 MeV alpha-activity of lunar thorium

    International Nuclear Information System (INIS)

    Since thorium in lunar crystalline rocks was reported to be excessive in 4.6 MeV alpha-activity up to 80%, which was attributed to a long-lived isomer of 232Th with an origin different from normal thorium, alpha-spectra of various terrestrial thorium were measured in order to see if terrestrial thorium also contains some excess 4.6 MeV alpha-activity. The results showed that the content of the excess 4.6 MeV alpha-activity in terrestrial thorium, if any, is much less than 3%. An approach to set an upper limit for the excess alpha-activity in terrestrial thorium is proposed. The origin of the excess alpha-activity is discussed. (author) 21 refs.; 3 tabs

  9. Developmental activities related to thorium purification and metal production

    International Nuclear Information System (INIS)

    A new process for selective recovery of thorium and uranium from thorium cake of monazite origin has been developed, where the thorium cake was dissolved in nitric acid and separation of U(VI) was carried out using tris-2 ethyl hexyl phosphate (TEHP) diluted with n-paraffin. The recovery of Th(IV) from raffinate solution containing large amount of rare earths was carried out using 1M TiAP/n-paraffin as solvent. Finally, thorium from organic phase was stripped using 0.05 M HNO3 and precipitated as thorium oxalate. Based on experimental results, a process flow-sheet has been proposed for selective recovery of uranium and thorium from monazite. For pure Th-metal, lab scale process has already been developed at UED and recently using this metal NFG has produced 99% pure thorium foils for Physical Research Laboratory, Ahmedabad as per their request

  10. Future perspective of thorium based nuclear fuels and thorium potential of Turkey

    International Nuclear Information System (INIS)

    Today's nuclear technology has principally been based on the use of fissile U-235 and Pu-239. The existence of thorium in the nature and its potential use in the nuclear technology were not unfortunately into account with a sufficient importance. The global distributions of thorium and uranium reserves indicate that in general some developed countries such as the USA, Canada, Australia, France have considerable uranium reserves, and contrarily only some developing countries such as Turkey, Brazil, India, Egypt have considerable thorium reserves. The studies carried out on the thorium during the last 50 years have clearly showed that the thorium based nuclear fuels have the potential easily use in most of reactor types actually operated with the classical uranium based nuclear fuels without any considerable modification. In the case of the use of thorium based nuclear fuels in future nuclear energy production systems, the serious problems such as the excess of Pu-239, the proliferation potential of nuclear weapons, and also the anxious of nuclear terrorism will probably be resolved, and sustainable nuclear energy production will be realized in the next new century. (authors)

  11. Practical introduction of thorium fuel cycles

    International Nuclear Information System (INIS)

    The pracitcal introduction of throrium fuel cycles implies that thorium fuel cycles compete economically with uranium fuel cycles in economic nuclear power plants. In this study the reactor types under consideration are light water reactors (LWRs), heavy water reactors (HWRs), high-temperature gas-cooled reactors (HTGRs), and fast breeder reactors (FBRs). On the basis that once-through fuel cycles will be used almost exclusively for the next 20 or 25 years, introduction of economic thorium fuel cycles appears best accomplished by commercial introduction of HTGRs. As the price of natural uranium increases, along with commercialization of fuel recycle, there will be increasing incentive to utilize thorium fuel cycles in heavy water reactors and light water reactors as well as in HTGRs. After FBRs and fuel recycle are commercialized, use of thorium fuel cycles in the blanket of FBRs appears advantageous when fast breeder reactors and thermal reactors operate in a symbiosis mode (i.e., where 233U bred in the blanket of a fast breeder reactor is utilized as fissile fuel in thermal converter reactors)

  12. Experience of thorium fuel development in India

    International Nuclear Information System (INIS)

    India has one of the largest resources of thorium in the beach sands of Southern India. Generation of nuclear power through utilization of thorium is the ultimate goal of India's three stage nuclear power strategy. Bhabha Atomic Research Centre (BARC) is actively pursuing research, development, fabrication, characterization and irradiating testing of ThO2, ThO2-PuO2, ThO2-UO2 fuels in test and power reactors. Work related to developing the fuel fabrication technology including automation and remotization needed for 233U based fuels is in progress. Use of ThO2 fuel bundles for initial flux flattening in our PHWRs; recent criticality of KAMINI - a small neutron source reactor, with 233U-Al alloy fuel; introduction of ThO2 as axial and radial blankets in our Fast Breeder Test Reactor (FBTR) at Kalpakkam; proposed ThO2-PuO2 and ThO2-233UO2 fuel for Advanced Heavy Water Reactor (AHWR) are some of the steps taken by us towards utilization of Thorium in India. The paper summarizes the present status of thorium fuel development in India. (author)

  13. The chemistry of thorium in the hydrosphere and the geosphere. Chemie des Thoriums in der Hydro- und in der Geosphaere

    Energy Technology Data Exchange (ETDEWEB)

    Hill, R.

    1990-01-29

    Taking as a basis the knowledge of the migration of radionuclides in the geosphere, the author investigates the chemistry of thorium (a radioactive element found in larger quantities in the natural environment) in natural aqueous solutions. The thorium is analysed in the low concentration range in pure water, in ground water, and in the ground water/sediment system. The impact of the hydrolysis, complex formation and colloid formation on the sorption of thorium is explained, and thorium tracer techniques are discussed (methods, performance, activity measurements). The author presents results of experiments with molar thorium solutions, of paper chromatography analyses, and of scintillation counting analyses. (HWJ).

  14. Candu reactors with thorium fuel cycles

    International Nuclear Information System (INIS)

    Over the last decade and a half AECL has established a strong record of delivering CANDU 6 nuclear power plants on time and at budget. Inherently flexible features of the CANDU type reactors, such as on-power fuelling, high neutron economy, fuel channel based heat transport system, simple fuel bundle configuration, two independent shut down systems, a cool moderator and a defence-in-depth based safety philosophy provides an evolutionary path to further improvements in design. The immediate milestone on this path is the Advanced CANDU ReactorTM** (ACRTM**), in the form of the ACR-1000TM**. This effort is being followed by the Super Critical Water Reactor (SCWR) design that will allow water-cooled reactors to attain high efficiencies by increasing the coolant temperature above 5500C. Adaptability of the CANDU design to different fuel cycles is another technology advantage that offers an additional avenue for design evolution. Thorium is one of the potential fuels for future reactors due to relative abundance, neutronics advantage as a fertile material in thermal reactors and proliferation resistance. The Thorium fuel cycle is also of interest to China, India, and Turkey due to local abundance that can ensure sustainable energy independence over the long term. AECL has performed an assessment of both CANDU 6 and ACR-1000 designs to identify systems, components, safety features and operational processes that may need to be modified to replace the NU or SEU fuel cycles with one based on Thorium. The paper reviews some of these requirements and the associated practical design solutions. These modifications can either be incorporated into the design prior to construction or, for currently operational reactors, during a refurbishment outage. In parallel with reactor modifications, various Thorium fuel cycles, either based on mixed bundles (homogeneous) or mixed channels (heterogeneous) have been assessed for technical and economic viability. Potential applications of a

  15. Thorium and its future importance for nuclear energy generation

    Energy Technology Data Exchange (ETDEWEB)

    Lainetti, Paulo E.O., E-mail: lainetti@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2015-07-01

    Thorium was discovered in 1828 by the Swedish chemist Jons J. Berzelius. Despite some advantages over uranium for use in nuclear reactors, its main use, in the almost two centuries since its discovery, the use of thorium was restricted to use for gas mantles, especially in the early twentieth century. In the beginning of the Nuclear Era, many countries had interested on thorium, particularly during the 1950-1970 period. There are about 435 nuclear reactors in the world nowadays. They need more than 65.000 tons of uranium yearly. The future world energy needs will increase and, even if we assumed a conservative contribution of nuclear generation, it will be occur a significant increasing in the uranium prices, taking into account that uranium, as used in the present thermal reactors, is a finite resource. Thorium is nearly three times more abundant than uranium in the Earth's crust. Despite thorium is not a fissile material, {sup 232}Th can be converted to {sup 233}U (fissile) more efficiently than {sup 238}U to {sup 239}Pu. Besides this, since it is possible to convert thorium waste into nonradioactive elements, thorium is an environment-friendly alternative energy source. Thorium fuel cycle is also inherently resistant to proliferation. Some papers evaluate the thorium resources in Brazil over 1.200.000 metric t. Then, the thorium alternative must be seriously considered in Brazil for strategic reasons. In this paper a brief history of thorium is presented, besides a review of the world thorium utilization and a discussion about advantages and restrictions of thorium use. (author)

  16. Indian Summer

    Energy Technology Data Exchange (ETDEWEB)

    Galindo, E. [Sho-Ban High School, Fort Hall, ID (United States)

    1997-08-01

    This paper focuses on preserving and strengthening two resources culturally and socially important to the Shoshone-Bannock Indian Tribe on the Fort Hall Reservation in Idaho; their young people and the Pacific-Northwest Salmon. After learning that salmon were not returning in significant numbers to ancestral fishing waters at headwater spawning sites, tribal youth wanted to know why. As a result, the Indian Summer project was conceived to give Shoshone-Bannock High School students the opportunity to develop hands-on, workable solutions to improve future Indian fishing and help make the river healthy again. The project goals were to increase the number of fry introduced into the streams, teach the Shoshone-Bannock students how to use scientific methodologies, and get students, parents, community members, and Indian and non-Indian mentors excited about learning. The students chose an egg incubation experiment to help increase self-sustaining, natural production of steelhead trout, and formulated and carried out a three step plan to increase the hatch-rate of steelhead trout in Idaho waters. With the help of local companies, governmental agencies, scientists, and mentors students have been able to meet their project goals, and at the same time, have learned how to use scientific methods to solve real life problems, how to return what they have used to the water and land, and how to have fun and enjoy life while learning.

  17. Recovery of thorium and rare earths by their peroxides precipitation from a residue produced in the thorium purification facility

    International Nuclear Information System (INIS)

    As consequence of the operation of a Thorium purification facility, for pure Thorium Nitrate production, the IPEN (Instituto de Pesquisas Energeticas e Nucleares) has stored away a solid residue called RETOTER (REsiduo de TOrio e TErras Raras). The RETOTER is rich in Rare-Earth Elements and significant amount of Thorium-232 and minor amount of Uranium. Furthermore it contains several radionuclides from the natural decay series. Significant radioactivity contribution is generated by the Thorium descendent, mainly the Radium-228(T1/2=5.7y), known as meso thorium and Thorium-228(T1/2 1.90y). An important thorium daughter is the Lead-208, a stable isotope present with an expressive quantity. After the enclosure of the operation of the Thorium purification facility, many researches have been developed for the establishment of methodologies for recovery of Thorium, Rare-Earth Elements and Lead-208 from the RETOTER. This work presents a method for RETOTER decontamination, separating and bordering upon some radioactive isotopes. The residue was digested with nitric acid and the Radium-228 was separated by the Barium Sulphate co-precipitation procedure. Finally, the Thorium was separated by the peroxide precipitation and the Rare-Earth Elements were also recovered by the Rare-Earth peroxide precipitation in the filtrate solution.(author)

  18. Feasibility to produce uranium-233 from thorium in PHWR

    International Nuclear Information System (INIS)

    Uranium-233 is a fissile isotope of uranium that is bred from thorium-232 as part of the thorium fuel cycle. It is used as fuel in nuclear reactor. 233U is produced by irradiating thorium in fast reactor or thermal reactor. In this paper feasibility to produce 233U by irradiation of fuel bundles of thorium mixed with plutonium or irradiation of thorium bundles along with slightly enriched Uranium bundles in 220 MWe and 540 MWe PHWRs has been studied. Study shows that production of 233U is possible by irradiating few fuel bundles of PuTh or Thorium bundles along with SEU bundles without affecting the power operation and the safety related parameters. (author)

  19. Thorium oxide dissolution kinetics for hydroxide and carbonate complexation

    International Nuclear Information System (INIS)

    The purpose of this project was to determine the kinetics and thermodynamics of thorium oxide dissolution in the environment. Solubility is important because it establishes an upper concentration limit on the concentration of a dissolved radionuclide in solution L1. While understanding the behavior of thorium fuels in the proposed repository at Yucca Mountain is most applicable, a more rigorous study of thorium solubility over a wide pH range was performed so that the data could also be used to model the behavior of thorium fuels in any environmental system. To achieve this, the kinetics and thermodynamics of thorium oxide dissolution under both pure argon and argon with PCO2 of 0. 1 were studied under the full pH range available in each atmosphere. In addition, thorium oxide powder remnants were studied after each experiment to examine structural changes that may affect kinetics

  20. Thorium: An energy source for the world of tomorrow ?

    CERN Document Server

    CERN. Geneva

    2014-01-01

    To meet the tremendous world energy needs, systematic R&D has to be pursued to replace fossil fuels. The ThEC13 conference organized by iThEC at CERN last October has shown that thorium is seriously considered by developing countries as a key element of their energy strategy. Developed countries are also starting to move in the same direction. How thorium could make nuclear energy (based on thorium) acceptable to society will be discussed. Thorium can be used both to produce energy and to destroy nuclear waste. As thorium is not fissile, one elegant option is to use an accelerator, in so-called “Accelerator Driven Systems (ADS)”, as suggested by Carlo Rubbia. CERN’s important contributions to R&D on thorium related issues will be mentioned as well as the main areas where CERN could contribute to this field in the future.

  1. Thorium: An energy source for the world of tomorrow

    Science.gov (United States)

    Revol, J.-P.

    2015-08-01

    To meet the tremendous world energy needs, systematic R&D has to be pursued to replace fossil fuels. Nuclear energy, which produces no green house gases and no air pollution, should be a leading candidate. How nuclear energy, based on thorium rather than uranium, could be an acceptable solution is discussed. Thorium can be used both to produce energy and to destroy nuclear waste. The thorium conference, organized by iThEC at CERN in October 2013, has shown that thorium is seriously considered by some major developing countries as a key element of their energy strategy. However, developed countries do not seem to move fast enough in that direction, while global cooperation is highly desirable in this domain. Thorium is not fissile. Various possible ways of using thorium will be reviewed. However, an elegant option is to drive an "Accelerator Driven System (ADS)" with a proton accelerator, as suggested by Nobel Prize laureate Carlo Rubbia .

  2. Thorium: An energy source for the world of tomorrow

    Directory of Open Access Journals (Sweden)

    Revol J.-P.

    2015-01-01

    Full Text Available To meet the tremendous world energy needs, systematic R&D has to be pursued to replace fossil fuels. Nuclear energy, which produces no green house gases and no air pollution, should be a leading candidate. How nuclear energy, based on thorium rather than uranium, could be an acceptable solution is discussed. Thorium can be used both to produce energy and to destroy nuclear waste. The thorium conference, organized by iThEC at CERN in October 2013, has shown that thorium is seriously considered by some major developing countries as a key element of their energy strategy. However, developed countries do not seem to move fast enough in that direction, while global cooperation is highly desirable in this domain. Thorium is not fissile. Various possible ways of using thorium will be reviewed. However, an elegant option is to drive an “Accelerator Driven System (ADS” with a proton accelerator, as suggested by Nobel Prize laureate Carlo Rubbia .

  3. Uranium and thorium deposits of Northern Ontario

    International Nuclear Information System (INIS)

    This, the second edition of the uranium-thorium deposit inventory, describes briefly the deposits of uranium and/or thorium in northern Ontario, which for the purposes of this circular is defined as that part of Ontario lying north and west of the Grenville Front. The most significant of the deposits described are fossil placers lying at or near the base of the Middle Precambrian Huronian Supergroup. These include the producing and past-producing mines of the Elliot Lake - Agnew Lake area. Also included are the pitchblende veins spatially associated with Late Precambrian (Keweenawan) diabase dikes of the Theano Point - Montreal River area. Miscellaneous Early Precambrian pegmatite, pitchblende-coffinite-sulphide occurrences near the Middle-Early Precambrian unconformity fringing the Lake Superior basin, and disseminations in diabase, granitic rocks, alkalic complexes and breccias scattered throughout northern Ontario make up the rest of the occurrences

  4. Accelerator breeder with uranium, thorium target

    International Nuclear Information System (INIS)

    An accelerator breeder, that uses a low-enriched fuel as the target material, can produce substantial amounts of fissile material and electric power. A study of H2O- and D2O-cooled, UO2, U, (depleted U), or thorium indicates that U-metal fuel produces a good fissile production rate and electrical power of about 60% higher than UO2 fuel. Thorium fuel has the same order of magnitude as UO2 fuel for fissile-fuel production, but the generating electric power is substantially lower than in a UO2 reactor. Enriched UO2 fuel increases the generating electric power but not the fissile-material production rate. The Na-cooled breeder target has many advantages over the H2O-cooled breeder target

  5. Thorium fuel cycle study for PWR applications

    International Nuclear Information System (INIS)

    A nuclear design feasibility of thorium fueled high converting PWR was investigated. Two kinds of fuel design option were tested for the comparison with conventional UO2 fuel. The first one was an application of MHTGR pyro-carbon coated particle fuels. The other design was an application of MOX fuels as a ThO2-PuO2 ceramic pellet. In the case of carbon-coated particle fuels, there was no benefit in nuclear design aspect because enrichment of U-235 was required over 5 w/o in order to match with the K-infinite of Ulchin-3/4 fuels. However, the use of thorium based plutonium fuels in PWR gave favorable aspects in nuclear design such as flatter K-infinite curve, lower M. T. C. and lower F. T. C. than that of UO2 fuel. (author). 6 refs., 3 tabs., 6 figs

  6. Computer simulations for thorium doped tungsten crystals

    International Nuclear Information System (INIS)

    Tungsten has the highest melting point among all metals in the periodic table of elements. Furthermore, its equilibrium vapor pressure is by far the lowest at the temperature given. Thoria, ThO2, as a particle dopant, results in a high temperature creep resistant material. Moreover, thorium covered tungsten surfaces show a drastically reduced electronic work function. This results in a tremendous reduction of tip temperatures of cathodes in discharge lamps, and, therefore, in dramatically reduced tungsten vapor pressures. Thorium sublimates at temperatures below those of a typical operating cathode. For proper operation, a diffusional flow of thorium atoms towards the surface has to be maintained. This atomic flux responds very sensitively on the local microstructure, as grain boundaries as well as dislocation cores offer ''short circuit paths'' for thorium atoms. In this work, we address some open issues of thoriated tungsten. A molecular dynamics scheme (MD) is used to derive static as well as dynamic material properties which have their common origin in the atomistic behavior of tungsten and thorium atoms. The interatomic interactions between thorium and tungsten atoms are described within the embedded atom model (EAM). So far, in literature no W-Th interaction potentials on this basis are described. As there is no alloying system known between thorium and tungsten, we have determined material data for the fitting of these potentials using ab-initio methods. This is accomplished using the full potential augmented plane wave method (FLAPW), to get hypothetical, i.e. not occurring in nature, ''alloy'' data of W-Th. In order to circumvent the limitations of classical (NVE) MD schemes, we eventually couple our model systems to external heat baths or volume reservoirs (NVT, NPT). For the NPT ensemble, we implemented a generalization of the variable cell method in combination with the Langevin piston, which results in a set of Langevin equations, i.e. stochastic

  7. Computer simulations for thorium doped tungsten crystals

    Energy Technology Data Exchange (ETDEWEB)

    Eberhard, Bernd

    2009-07-17

    Tungsten has the highest melting point among all metals in the periodic table of elements. Furthermore, its equilibrium vapor pressure is by far the lowest at the temperature given. Thoria, ThO{sub 2}, as a particle dopant, results in a high temperature creep resistant material. Moreover, thorium covered tungsten surfaces show a drastically reduced electronic work function. This results in a tremendous reduction of tip temperatures of cathodes in discharge lamps, and, therefore, in dramatically reduced tungsten vapor pressures. Thorium sublimates at temperatures below those of a typical operating cathode. For proper operation, a diffusional flow of thorium atoms towards the surface has to be maintained. This atomic flux responds very sensitively on the local microstructure, as grain boundaries as well as dislocation cores offer ''short circuit paths'' for thorium atoms. In this work, we address some open issues of thoriated tungsten. A molecular dynamics scheme (MD) is used to derive static as well as dynamic material properties which have their common origin in the atomistic behavior of tungsten and thorium atoms. The interatomic interactions between thorium and tungsten atoms are described within the embedded atom model (EAM). So far, in literature no W-Th interaction potentials on this basis are described. As there is no alloying system known between thorium and tungsten, we have determined material data for the fitting of these potentials using ab-initio methods. This is accomplished using the full potential augmented plane wave method (FLAPW), to get hypothetical, i.e. not occurring in nature, ''alloy'' data of W-Th. In order to circumvent the limitations of classical (NVE) MD schemes, we eventually couple our model systems to external heat baths or volume reservoirs (NVT, NPT). For the NPT ensemble, we implemented a generalization of the variable cell method in combination with the Langevin piston, which results in a

  8. The Fission of Thorium with Alpha Particles

    Energy Technology Data Exchange (ETDEWEB)

    Newton, Amos S.

    1948-04-15

    The fission distribution of fission of thorium with alpha particle of average energy 37.5 Mev has been measured by the chemical method. The distribution found shows that the characteristic dip in the fission yield mass spectrum has been raised to within a factor of two of the peaks compared to a factor of 600 in slow neutron fission of U{sup 235}. The raise in the deip has caused a corresponding lowering in fission yield of these elements at the peaks. The cross section for fission of thorium with 37.5 Mev alphas was found to be about 0.6 barn, and the threshold for fission was found to be 23 to 24 Mev.

  9. Thorium fuel cycle study for PWR applications

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Jae Yong; Kim, Myung Hyun [Kyung Hee Univ., Seoul (Korea, Republic of)

    1997-12-31

    A nuclear design feasibility of thorium fueled high converting PWR was investigated. Two kinds of fuel design option were tested for the comparison with conventional UO{sub 2} fuel. The first one was an application of MHTGR pyro-carbon coated particle fuels. The other design was an application of MOX fuels as a ThO{sub 2}-PuO{sub 2} ceramic pellet. In the case of carbon-coated particle fuels, there was no benefit in nuclear design aspect because enrichment of U-235 was required over 5 w/o in order to match with the K-infinite of Ulchin-3/4 fuels. However, the use of thorium based plutonium fuels in PWR gave favorable aspects in nuclear design such as flatter K-infinite curve, lower M. T. C. and lower F. T. C. than that of UO{sub 2} fuel. (author). 6 refs., 3 tabs., 6 figs.

  10. Remarks on the cavitation of Thorium-228

    CERN Document Server

    Cardone, F; Petrucci, A

    2010-01-01

    In this short note we would like to provide some useful remarks on our previous work about the piezonuclear decay of Thorium and in general about the methods and protocols that we used in the experiments on piezonuclear reactions. The purpose of these remarks is to highlight the critical points of the experiments and equipment in order to design future experiments that may obtain positive evidences or that can be as more comparable to previous ones as possible.

  11. Thorium dioxide: properties and nuclear applications

    International Nuclear Information System (INIS)

    This is the sixth book on reactor materials published under sponsorship of the Naval Reactors Office of the United States Department of Energy, formerly the United States Atomic Energy Commission. This book presents a comprehensive compilation of the most significant properties of thorium dioxide, much like the book Uranium Dioxide: Properties and Nuclear Applications presented information on the fuel material used in the Shippingport Pressurized Water Reactor core

  12. Thorium dioxide: properties and nuclear applications

    Energy Technology Data Exchange (ETDEWEB)

    Belle, J.; Berman, R.M. (eds.)

    1984-01-01

    This is the sixth book on reactor materials published under sponsorship of the Naval Reactors Office of the United States Department of Energy, formerly the United States Atomic Energy Commission. This book presents a comprehensive compilation of the most significant properties of thorium dioxide, much like the book Uranium Dioxide: Properties and Nuclear Applications presented information on the fuel material used in the Shippingport Pressurized Water Reactor core.

  13. Long term radiological impact of thorium extraction

    International Nuclear Information System (INIS)

    Thorium extraction produces a certain amount of radioactive wastes. Potential long term radiological impact of these residues has been calculated using the recent ICRP-68 ingestion dose factors in connection with the computing code DECAY, developed at Orsay and described in this work. This code solves the well known Bateman's equations which govern the time dependence of a set of coupled radioactive nuclei. Monazites will be very likely the minerals to be exploited first, in case of an extensive use of thorium as nuclear fuel. Because monazites contain uranium as well, mining residues will contain not only the descendants of 232Th and a certain proportion of non-extracted thorium (taken here to be 5%), but also this uranium, if left in the wastes for economical reasons. If no uranium would be present at all in the mineral, the potential radiotoxicity would strongly decrease in approximately 60 years, at the pace of the 5.8 years period of 228Ra, which becomes the longest-lived radionuclide of the 4n radioactive family in the residues. Moreover, there is no risk due to radon exhalation, because of the very short period of 220Rn. These significant differences between uranium and thorium mining have to be considered in view of some estimated long term real radiological impacts due to uranium residues, which could reach a value of the order of 1 mSv/year, the dose limit recommended for the public by the recent ICRP-60. (authors). 15 refs., 4 figs., 3 tabs., 43 appendices

  14. Thorium: in search of a global solution

    CERN Multimedia

    Antonella Del Rosso

    2013-01-01

    Last week, an international conference held at CERN brought together the world’s main experts in the field of alternative nuclear technology for the first time to discuss the use of thorium for the production of energy and the destruction of nuclear waste. Among the different technologies presented and discussed at the conference was ADS (Accelerator-Driven Systems) which relies primarily on particle accelerators.   The conference Chair (far left), the organisers and some of the distinguished participants of the ThEC13 conference held at CERN from 27 to 31 October 2013. “CERN has always been interested in finding ways in which fundamental research can help to resolve the problems of society,” says Jean-Pierre Revol, a physicist at the ALICE experiment who recently retired from CERN and is President of iThEC, the international not-for-profit organisation which promotes research and development in the field of thorium and which organised the Thorium Energy 2013 (Th...

  15. Self-Sustaining Thorium Boiling Water Reactors

    Directory of Open Access Journals (Sweden)

    Ehud Greenspan

    2012-10-01

    Full Text Available A thorium-fueled water-cooled reactor core design approach that features a radially uniform composition of fuel rods in stationary fuel assembly and is fuel-self-sustaining is described. This core design concept is similar to the Reduced moderation Boiling Water Reactor (RBWR proposed by Hitachi to fit within an ABWR pressure vessel, with the following exceptions: use of thorium instead of depleted uranium for the fertile fuel; elimination of the internal blanket; and elimination of absorbers from the axial reflectors, while increasing the length of the fissile zone. The preliminary analysis indicates that it is feasible to design such cores to be fuel-self-sustaining and to have a comfortably low peak linear heat generation rate when operating at the nominal ABWR power level of nearly 4000 MWth. However, the void reactivity feedback tends to be too negative, making it difficult to have sufficient shutdown reactivity margin at cold zero power condition. An addition of a small amount of plutonium from LWR used nuclear fuel was found effective in reducing the magnitude of the negative void reactivity effect and enables attaining adequate shutdown reactivity margin; it also flattens the axial power distribution. The resulting design concept offers an efficient incineration of the LWR generated plutonium in addition to effective utilization of thorium. Additional R&D is required in order to arrive at a reliable practical and safe design.

  16. Thorium in the workplace measurement intercomparison

    International Nuclear Information System (INIS)

    The monitoring of radionuclides in the nuclear industry has been recognized as the most straightforward way of assessing health and safety issues associated with the exposure of the workforce to potentially harmful radiation doses. Much of this is achieved by measurements in the workplace itself and by the bioassay and monitoring of workers in the industry. However, there also exists a significant 'non-nuclear' industry where workers are exposed to radioactive materials, for example where this involves thorium, which is made wide use of in the aerospace and other high technology industries. As such work involves the processing of thorium bearing materials, the workforce is potentially exposed to 232Th and its daughter nuclides. Thus, to monitor the workforce effectively, it is important to be able to measure both 232Th and the decay products of 232Th where they are in an unknown state of radioactive equilibrium and this is where monitoring laboratories may experience some difficulty. Accordingly, the Health and Safety Laboratory in the UK has organized a EC wide project on the monitoring of thorium in the 'non-nuclear' workplace; this project is currently ongoing. We report the results of the first intercomparison of this project involving two solutions of 232Th, one in radioactive equilibrium and one not in equilibrium with its daughters. The results are presented with some comments on how this intercomparison has progressed and how these first results will inform the rest of the project

  17. Self-Sustaining Thorium Boiling Water Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Greenspan, Ehud [Univ. of California, Berkeley, CA (United States); Gorman, Phillip M. [Univ. of California, Berkeley, CA (United States); Bogetic, Sandra [Univ. of California, Berkeley, CA (United States); Seifried, Jeffrey E. [Univ. of California, Berkeley, CA (United States); Zhang, Guanheng [Univ. of California, Berkeley, CA (United States); Varela, Christopher R. [Univ. of California, Berkeley, CA (United States); Fratoni, Massimiliano [Univ. of California, Berkeley, CA (United States); Vijic, Jasmina J. [Univ. of California, Berkeley, CA (United States); Downar, Thomas [Univ. of Michigan, Ann Arbor, MI (United States); Hall, Andrew [Univ. of Michigan, Ann Arbor, MI (United States); Ward, Andrew [Univ. of Michigan, Ann Arbor, MI (United States); Jarrett, Michael [Univ. of Michigan, Ann Arbor, MI (United States); Wysocki, Aaron [Univ. of Michigan, Ann Arbor, MI (United States); Xu, Yunlin [Univ. of Michigan, Ann Arbor, MI (United States); Kazimi, Mujid [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Shirvan, Koroush [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Mieloszyk, Alexander [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Todosow, Michael [Brookhaven National Lab. (BNL), Upton, NY (United States); Brown, Nicolas [Brookhaven National Lab. (BNL), Upton, NY (United States); Cheng, Lap [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2015-03-15

    The primary objectives of this project are to: Perform a pre-conceptual design of a core for an alternative to the Hitachi proposed fuel-self- sustaining RBWR-AC, to be referred to as a RBWR-Th. The use of thorium fuel is expected to assure negative void coefficient of reactivity (versus positive of the RBWR-AC) and improve reactor safety; Perform a pre-conceptual design of an alternative core to the Hitachi proposed LWR TRU transmuting RBWR-TB2, to be referred to as the RBWR-TR. In addition to improved safety, use of thorium for the fertile fuel is expected to improve the TRU transmutation effectiveness; Compare the RBWR-Th and RBWR-TR performance against that of the Hitachi RBWR core designs and sodium cooled fast reactor counterparts - the ARR and ABR; and, Perform a viability assessment of the thorium-based RBWR design concepts to be identified along with their associated fuel cycle, a technology gap analysis, and a technology development roadmap. A description of the work performed and of the results obtained is provided in this Overview Report and, in more detail, in the Attachments. The major findings of the study are summarized.

  18. Self-Sustaining Thorium Boiling Water Reactors

    International Nuclear Information System (INIS)

    The primary objectives of this project are to: Perform a pre-conceptual design of a core for an alternative to the Hitachi proposed fuel-self- sustaining RBWR-AC, to be referred to as a RBWR-Th. The use of thorium fuel is expected to assure negative void coefficient of reactivity (versus positive of the RBWR-AC) and improve reactor safety; Perform a pre-conceptual design of an alternative core to the Hitachi proposed LWR TRU transmuting RBWR-TB2, to be referred to as the RBWR-TR. In addition to improved safety, use of thorium for the fertile fuel is expected to improve the TRU transmutation effectiveness; Compare the RBWR-Th and RBWR-TR performance against that of the Hitachi RBWR core designs and sodium cooled fast reactor counterparts - the ARR and ABR; and, Perform a viability assessment of the thorium-based RBWR design concepts to be identified along with their associated fuel cycle, a technology gap analysis, and a technology development roadmap. A description of the work performed and of the results obtained is provided in this Overview Report and, in more detail, in the Attachments. The major findings of the study are summarized.

  19. Use of Thorium in Light Water Reactors

    International Nuclear Information System (INIS)

    Thorium-based fuels can be used to reduce concerns related to the proliferation potential and waste disposal of the conventional light water reactor (LWR) uranium fuel cycle. The main sources of proliferation potential and radiotoxicity are the plutonium and higher actinides generated during the burnup of standard LWR fuel. A significant reduction in the quantity and quality of the generated Pu can be achieved by replacing the 238U fertile component of conventional low-enriched uranium fuel by 232Th. Thorium can also be used as a way to manage the growth of plutonium stockpiles by burning plutonium, or achieving a net-zero transuranic production, sustainable recycle scenario. This paper summarizes some of the results of recent studies of the performance of thorium-based fuels.It is concluded that the use of heterogeneous U-Th fuel provides higher neutronic potential than a homogeneous fuel. However, in the former case, the uranium portion of the fuel operates at a higher power density, and care is needed to meet the thermal margins and address the higher-burnup implications. In macroheterogeneous designs, the U-Th fuel can yield reduced spent-fuel volume, toxicity, and decay heat. The main advantage of Pu-Th oxide over mixed oxide is better void reactivity behavior even for undermoderated designs, and increased burnup of Pu

  20. Thorium: An energy source for the world of tomorrow

    OpenAIRE

    Revol J.-P.

    2015-01-01

    To meet the tremendous world energy needs, systematic R&D has to be pursued to replace fossil fuels. Nuclear energy, which produces no green house gases and no air pollution, should be a leading candidate. How nuclear energy, based on thorium rather than uranium, could be an acceptable solution is discussed. Thorium can be used both to produce energy and to destroy nuclear waste. The thorium conference, organized by iThEC at CERN in October 2013, has shown that thorium is seriously considered...

  1. Health status and body radioactivity of former thorium workers

    International Nuclear Information System (INIS)

    The objectives of the study are: (1) to assess possible health effects of employment in the thorium milling industry by comparison of mortality and morbidity characteristics of former thorium workers with those of suitable general populations; (2) to examine disease outcomes by estimated exposure levels of thorium and thoron daughter products for possible radiation-related effects; and (3) to determine the body distribution of inhaled thorium (and daughters) and rare earths in humans by radioactivity measurements in vivo and by analysis of autopsy samples. The principal end points for investigation are respiratory disease and cancers of lung, liver, bone, and bone marrow

  2. Uranium and thorium in British arable crops and grass

    International Nuclear Information System (INIS)

    The uranium-238 and thorium-232 concentrations of 59 crop samples from ten locations in England have been determined using inductively coupled plasma-mass spectrometry. The samples were collected at harvesting time during the summer and autumn of 1988. The levels of uranium and thorium in the crops ranged from -1 for uranium and from -1 for thorium. A general increase in the uranium and the thorium concentration of the crops was observed as follows: root crop flesh 40K and about 20% due to 210Pb and 210Po. (author)

  3. Review of Brazilian activities related to the thorium fuel cycle and production of thorium compounds at IPEN-CNEN/SP

    International Nuclear Information System (INIS)

    The Brazilian's interest in the nuclear utilization of thorium has started in the 50's as a consequence of the abundant occurrence of monazite sands. Since the sixties, IPEN-CNEN/SP has performed some developments related to the thorium fuel cycle. The production and purification of thorium compounds was carried out at IPEN for about 18 years and the main product was the thorium nitrate with high purity, having been produced over 170 metric tons of this material in the period, obtained through solvent extraction. The thorium nitrate was supplied to the domestic industry and used for gas portable lamps (Welsbach mantle). Although the thorium compounds produced have not been employed in the nuclear area, several studies were conducted. Therefore, those activities and the accumulated experience are of strategic importance, on one hand due to huge Brazilian thorium reserves, on the other hand by the resurgence of the interest of thorium for the Generation IV Advanced Reactors. This paper presents a review of the Brazilian research and development activities related to thorium technology. (author)

  4. The hydrolysis of thorium dicarbide and of mixed uranium-thorium dicarbides

    International Nuclear Information System (INIS)

    The hydrolysis of thorium dicarbide leads to the formation of a complex mixture of gaseous and condensed carbon hydrides. The temperature, between 25 and 100 deg. C, has no influence on the nature and composition of the gas phase. The reaction kinetics, however, are strongly temperature dependent. In a hydrochloric medium, an enrichment in hydrogen of the gas mixture is observed. On the other hand a decrease in hydrogen and an increase in acetylene content take place in an oxidizing medium. The general results can be satisfactorily interpreted through a reaction mechanism involving C-C radical groups. In the same way, the hydrolysis of uranium-thorium-carbon ternary alloys leads to the formation of gaseous and condensed carbon hydrides. The variation of the composition of the gas phase versus uranium content in the alloy suggests an hypothesis about the carbon-carbon distance in the alloy crystal lattice. The variation of methane content, on the other hand, has lead us to discuss the nature of the various phases present in uranium-carbon alloys and carbon-rich uranium-thorium-carbon alloys. We have reached the conclusion that these alloys include a proportion of monocarbide which is dependent upon the ratio. Th/(Th + U). We put forward a diagram of the system uranium-carbon with features proper to explain some phenomena which have been observed in the uranium-thorium-carbon ternary diagram. (author)

  5. Content of Transuranium Nuclide in Process of Irradiating Thorium

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Currently, sufficient nuclear fuel supply is most important problem with the nuclear power grow rapidly, so the use of thorium fuel is being put on the agenda. The applicability of thorium as a power reactor is based on a (n, γ) reaction on 232Th. The consequent nucleus, 233Th,

  6. Regularities of flotation separation of thorium-containing anions

    International Nuclear Information System (INIS)

    A possibility of flotation separation of thorium from diluted sulfuric acid solution using the aliphatic amines is considered. Sulfuric acid solutions containing 50 mg/l thorium are the objects of the investigation. Flotational treatment of solutions is realized in a glass flotation column. Air has been pumped from below. The curves, characterizing the effect of hydrogen ion concentration on the degree of thorium flotational extraction, are similar for all the studied collectors and have two maxima: the first one (lower) at pH=1, the second one (higher) at pH=4-6. The maximum of thorium flotational separation in low-acid medium (pH=4-6) is observed at relatively low (25%) excess of decylamine and stoichiometric quantities of dodecyl-, tetradecyl-, hexadecyl-, octadecylamones. During thorium separation from higher acid solutions (pH=1) the highest degree of thorium separation takes place at 1.5-fold excess of hexa- and octadecylamines and 3-fold excess of do- and tetradecylamines. The period of time for thorium flotation separation varies depending on the experiment conditions from 2 to 15 min. Up to 98% thorium can be separated during one operation using the method of flotation from the given model solutions

  7. Economics and utilization of thorium in nuclear reactors

    International Nuclear Information System (INIS)

    Information on thorium utilization in power reactors is presented concerning the potential demand for nuclear power, the potential supply for nuclear power, economic performance of thorium under different recycle policies, ease of commercialization of the economically preferred cases, policy options to overcome institutional barriers, and policy options to overcome technological and regulatory barriers

  8. Determination of uranium and thorium in soils from Podunajske Biskupice

    International Nuclear Information System (INIS)

    Activity of uranium and thorium in soil samples was determined. The samples of soils were taken from region Podunajske Biskupice near Bratislava in Slovakia. Thorium and uranium activity was measured by alpha spectrometer with surface-barrier semiconductor detector. Specific activities and ratios Th-232/Th-230 and U-238/U-234 were calculated from obtained results. (authors)

  9. Strategy for the practical utilization of thorium fuel cycles

    International Nuclear Information System (INIS)

    There has been increasing interest in the utilization of thorium fuel cycles in nuclear power reactors for the past few years. This is due to a number of factors, the chief being the recent emphasis given to increasing the proliferation resistance of reactor fuel cycles and the thorium cycle characteristic that bred 233U can be denatured with 238U (further, a high radioactivity is associated with recycle 233U, which increases fuel diversion resistance). Another important factor influencing interest in thorium fuel cycles is the increasing cost of U3O8 ores leading to more emphasis being placed on obtaining higher fuel conversion ratios in thermal reactor systems, and the fact that thorium fuel cycles have higher fuel conversion ratios in thermal reactors than do uranium fuel cycles. Finally, there is increasing information which indicates that fast breeder reactors have significantly higher capital costs than do thermal reactors, such that there is an economic advantage in the long term to have combinations of fast breeder reactors and high-conversion thermal reactors operating together. Overall, it appears that the practical, early utilization of thorium fuel cycles in power reactors requires commercialization of HTGRs operating first on stowaway fuel cycles, followed by thorium fuel recycle. In the longer term, thorium utilization involves use of thorium blankets in fast breeder reactors, in combination with recycling the bred 233U to HTGRs (preferably), or to other thermal reactors

  10. Automated methods for thorium determination in liquids, solids and aerosols

    International Nuclear Information System (INIS)

    Methodology for determining trace thorium levels in a variety of sample types for compliance purposes was developed. Thorium in filtered water samples is concentrated by ferric hydroxide co-precipitation. Aerosols on glass-fibre, cellulose ester or teflon filters are acid digested and thorium is concentrated by lanthanum fluoride co-precipitation. Chemical separation and measurement are then done on a Technicon AAII-C auto-analyzer via TTA-solvent extraction and colorimetry using the thorium-arsenazo III colour complex. Solid samples are acid digested and thorium is concentrated and separated using lanthanum fluoride co-precipitation followed by anion-exchange chromatography. Measurement is then carried out on the autoanalyzer by direct development of the thorium-arsenazo III colour complex. Chemical yields are determined through the addition of thorium-234 tracer with assay by gamma-ray spectrometry. The sensitivities of the methods for liquids, aerosols and solids are approximately 1μg/L,0.5μg and 0.5 μg/g respectively. At thorium levels about ten times the detection limits, accuracy and reproducibility are typically +-10 percent for liquids and aerosols and +- 15 percent for solid samples

  11. Evaluation of thorium based nuclear fuel. Chemical aspects

    International Nuclear Information System (INIS)

    This report describes the chemical aspects of a thorium-based fuel cycle. It is part of a series devoted to the study of thorium-based fuel as a means to achieve a considerable reduction of the radiotoxicity of the waste from nuclear power production. Therefore special emphasis is placed on fuel (re-)fabrication and fuel reprocessing in the present work. (orig.)

  12. Separation of 228Ra (Ms Th 1) from thorium nitrate

    International Nuclear Information System (INIS)

    Treatment of 135 kg of thorium nitrate (purified and recrystallized in 1958) has been made for extraction of 228Ra in equilibrium. Elimination of the preponderant part of thorium by solvent extraction (TBP) and last purification by chromatography (Dowex 50 W X 8 and 1 X 8). Total yield was about (38 ± 4) per cent. (authors)

  13. Economics and utilization of thorium in nuclear reactors

    Energy Technology Data Exchange (ETDEWEB)

    1978-05-01

    Information on thorium utilization in power reactors is presented concerning the potential demand for nuclear power, the potential supply for nuclear power, economic performance of thorium under different recycle policies, ease of commercialization of the economically preferred cases, policy options to overcome institutional barriers, and policy options to overcome technological and regulatory barriers.

  14. Sorption of tetravalent thorium on muscovite

    Science.gov (United States)

    Schmidt, M.; Lee, S. S.; Wilson, R. E.; Soderholm, L.; Fenter, P.

    2012-07-01

    Adsorption of tetravalent thorium to the (0 0 1) basal surface of the phyllosilicate muscovite from an aqueous solution (1 × 10-4 mol/L Th(IV) in 1 × 10-1 mol/L NaCl, pH = 3.2) was studied by crystal truncation rod (CTR) and resonant anomalous X-ray reflectivity (RAXR) measurements. Th uptake to the muscovite surface from solutions with total Th concentrations [Th]tot = 1 × 10-6-4.88 × 10-3 mol/L and 1 × 10-1 mol/L NaCl, pH = 3.2 was quantified by alpha-spectrometry. The uptake measurements showed that Th adsorption to the muscovite surface follows a Langmuir isotherm with an apparent adsorption constant Kapp = 2 × 104 L/mol up to [Th]tot = 1.02 × 10-3 mol/L. The CTR and RAXR results identified one dominant Th species with a very broad distribution centered ∼10 Å above the surface, in agreement with strongly hydrated extended outer sphere sorption. The findings indicate that the large energy of hydration (ΔGhyd = -5815 kJ/mol (Marcus, 1991)) for the small and highly-charged Th4+ cation is a controlling parameter in its surface speciation. The surface occupancy (0.4 Th per unit cell area, AUC) measured by RAXR exceeds the expected level for surface charge compensation by tetravalent Th (0.25 Th/AUC). However, the radiometric uptake measurements show smaller occupancies (0.21 Th/AUC) after rinsing by deionized water, indicating a partial removability of sorbed thorium. Thorium oligomerization was observed at total Th concentrations [Th]tot ⩾ 2.0 × 10-3 mol/L in presence of the surface, although solubility studies suggest that Th is soluble under these solution conditions.

  15. Sorption and desorption of thorium from aqueous solutions by montmorillonite

    International Nuclear Information System (INIS)

    The sorption and desorption of thorium on a West Anatolian montmorillonite has been studied by application of a batch technique. Experimental procedures are outlined and results for thorium contacted with montmorillonite are reported and discussed. The thorium concentration range was between 200-4000 ppm (8.5 x 10-4 - 1.7 x 10-2M). The sorption and desorption coefficients varied between 1.586-0.216 ml g-1 and 0.829-0.168 ml g-1, respectively, and sorption was not fully reversible. The data could be fitted to Freundlich and Langmuir isotherms. The quantity of the sorbed thorium was much lower than its theoretical CEC. This was attributed to a blocking of montmorillonite's CEC by thorium islands in the interlayer. (author). 29 refs., 1 fig., 5 tabs

  16. Solubility of thorium under oxygen-free conditions

    International Nuclear Information System (INIS)

    Thorium solubility in 0.1 mol/l NaCl in oxygen- and carbonate-free conditions was studied. Equilibrium was established both in terms of unsaturated and oversaturated solutions. Crystallization of amorphous and microcrystal thorium-containing solid phases was controlled roentgenographically. Thorium concentration in solutions in the range of 10-11-10-8 mol/l was determined by means of mass spectrometry. Study by the methods of electron microscopy of the precipitate and solution after ultrafiltration suggests that in the system studied thorium does not form colloids. Experimentally obtained value of thorium solubility in carbonate-free medium agrees well with the calculated value (EQ3/6 code); i.e. approximately 2x10-3 mol/l

  17. Thorium fuel studies for CANDU reactors

    International Nuclear Information System (INIS)

    Applying the once-through Thorium (OTT) cycle in existing and advanced CANDU reactors might be seen as an evolved concept for the sustainable development both from the economic and waste management points of view. Using the Canadian proposed scheme - loading mixed ThO2-SEU CANFLEX bundles in CANDU 6 reactors - simulated at lattice cell level led to promising conclusions on higher burnup, lesser actinide inventory and proliferation resistance. The calculations were performed using the lattice codes WIMS and DRAGON (together with the corresponding nuclear data library based on ENDF/B-VII). (authors)

  18. The Use of Thorium within the Nuclear Power Industry - 13472

    International Nuclear Information System (INIS)

    Thorium is 3 to 4 times more abundant than uranium and is widely distributed in nature as an easily exploitable resource in many countries. Unlike natural uranium, which contains ∼0.7% fissile 235U isotope, natural thorium does not contain any fissile material and is made up of the fertile 232Th isotope only. Therefore thorium and thorium-based fuel as metal, oxide or carbide, has been utilized in combination with fissile 235U or 239Pu in nuclear research and power reactors for conversion to fissile 233U, thereby enlarging fissile material resources. During the pioneering years of nuclear energy, from the mid 1950's to mid 1970's, there was considerable interest worldwide to develop thorium fuels and fuel cycles in order to supplement uranium reserves. Thorium fuels and fuel cycles are particularly relevant to countries having large thorium deposits but very limited uranium reserves for their long term nuclear power programme. The feasibility of thorium utilization in high temperature gas cooled reactors (HTGR), light water reactors (LWR), pressurized heavy water reactors (PHWRs), liquid metal cooled fast breeder reactors (LMFBR) and molten salt breeder reactors (MSBR) were demonstrated. The initial enthusiasm for thorium fuels and fuel cycles was not sustained among the developing countries later, due to new discovery of uranium deposits and their improved availability. However, in recent times, the need for proliferation-resistance, longer fuel cycles, higher burnup, and improved waste form characteristics, reduction of plutonium inventories and in situ use of bred-in fissile material has led to renewed interest in thorium-based fuels and fuel cycles. (authors)

  19. Long-term monitoring of thorium inhaled by workers and assessment of thorium lung burden in China

    International Nuclear Information System (INIS)

    The long-term monitoring of thorium inhaled by workers and assessment of their thorium lung burden has been carried out in China since 1960. Various monitoring methods have been adopted, such as chemical analysis of thorium concentration in urine samples; assessing thorium lung burden by measurement of 212Pb etc. using a whole-body counter; measurement of exhaled thoron using a ZnS detector; or exhaled thoron decay products using an electrostatic collection system. Our experience over more than 20 years has shown that the last named measurement system is the best method for monitoring and assessing the lung burden of thorium (ThO2) inhaled by miners and workers. (author)

  20. Determination of rare earth elements, yttrium, uranium and thorium in Ilmenite samples by ICP-MS

    International Nuclear Information System (INIS)

    Ilmenite (FeOTiO2) is an important titanium bearing mineral that occurs in placer (both inland and beach sand) deposits, and is mainly used in the manufacture of titanium dioxide pigment. Ilmenite from Indian sand deposits are found to contain TiO2 ranging from 50% to 64% with varying amounts of FeO and Fe2O3 (nearly 30% Fe) and minor amounts of chromium, vanadium, calcium, magnesium and manganese. Ilmenite of various sand deposits show varied heavy mineral assemblages and contain different trace elements. Analysis of rare earth elements and other trace constituents in such iron-rich samples poses a challenge to the analysts. In the present work, ICP-MS has been applied to the rapid determination of REEs, as well as uranium and thorium in ilmenite samples

  1. Determination of Thorium and Ruthenium in Diuranate by ICP-AES

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Qian-ci; TAO; Miao-miao; LUO; Zhong-yan; ZHAO; Li-fei; HAO; Xiao-juan

    2012-01-01

    <正>Thorium and ruthenium are important impurities that should be monitored in diuranate product. A method for determination of thorium and ruthenium in diuranate was established. Due to the complicated atomic lines of uranium, which have strict interference with that of thorium and ruthenium during determination by ICP-AES, thorium and ruthenium should be separated firstly from uranium matrix before measurement.

  2. Use of nuclear recoil for separating 228Ra, 224Ra, and 233Pa from colloidal thorium

    International Nuclear Information System (INIS)

    By using α-recoil it is possible to separate by dialysis the α disintegration products (224 Ra; 228 Ra) of thorium from colloidal thorium hydroxide.The use of n, γ recoil allows the separation of 233Pa produced by the neutron irradiation of thorium, on condition that the colloidal thorium hydroxide is irradiated in the presence of a dispersing. (author)

  3. Benefits of transitioning to a thorium cycle

    International Nuclear Information System (INIS)

    Projections of the total world nuclear electricity demand for the next century show that existing natural uranium (NU) resources will be severely challenged by 2070. One way to meet this challenge is to recycle spent plutonium from Light Water Reactors (LWRs) as starting fissile material in thorium-fuelled Heavy Water Reactors (HWRs). This arrangement obtains more total energy per unit of NU mined since no NU is required by the HWR fleet, which instead gets its fissile material from LWR spent fuel and from U-233 bred into the thorium. Modeling shows that world NU requirements up to the year 2130 can be reduced by 10% for a once-through Th-Pu fuel cycle and by almost 20% in a Th-Pu-U-233 fuel cycle where the U-233 in spent HWR fuel is recovered and used to top-up the initial fissile material. As an added benefit, the total decay heat of spent fuel in repositories, a limiting factor, is reduced by more than one third by the transmutation of LWR plutonium. (author)

  4. Phthalocyaninato complexes of thorium, protactinium and uranium

    International Nuclear Information System (INIS)

    For the preparation of Bis(phthalocyaninato)-actinoid(IV) complexes, AnPc2, a new optimizing synthesis procedure was developed, with which it was possible to prepare spectrally pure, that is, H2Pc-free, ThPc2, UPc2 and the isostructurally similar 231PaPc2.PaPc2. This was verified with the help of electron spectra, which were compared to preparations which were synthesized in another manner. The corresponding perfluorinated compounds were also produced for thorium and uranium by use of tetrafluorophthalic acid nitrile instead of phthalic acid nitrile as initial product. Electron and infrared spectra show the typical bands of the non-substituted complexes. By the attempt to produce a mono(phthalocyaninato)-thorium complex with the use of ThI4 as initial material a pyridine-extracted pure ThPcI2(py)2 was obtained with a typical mono(phthalocyaninato) complex electron spectrum, an extremely moisture sensitive compound which in water or acids decomposes and produces H2Pc. (orig./RB)

  5. Thorium molten-salt nuclear energy synergetics

    International Nuclear Information System (INIS)

    One of the most practical and rational approaches for establishing the idealistic Thorium resource utilization program has been presented, which might be effective to solve the principal energy problems, concerning safety, proliferation and terrorism, resource, power size and fuel cycle economy, for the next century. The first step will be the development of Small Molten-Salt Reactors as a flexible power station, which is suitable for early commercialization of Th reactors not necessarily competing with proven Large Solid-Fuel Reactors. Therefore, the more detailed design works and practical R and D planning should be performed under the international cooperations soon, soundly depending on the basic technology established by ORNL already. R and D cost would be surprisingly low. This reactor(MSR) seems to be idealistic not only in power-size, siting, safety, safeguard and economy, but also as an effective partner of Molten-Salt Fissile Breeders(MSB) in order to establish the simplest and economical Thorium molten-salt breeding fuel cycle named THORIMS-NES in all over the world including the developing countries and isolated areas. This would be one of the most practical replies to the Lilienthal's appeal of 'A NEW START' in Nuclear Energy. (author)

  6. Advanced epithermal thorium reactor (AETR) physics

    International Nuclear Information System (INIS)

    The AETR concept is reviewed in reference to existing theory, nuclear parameters, and potential neutron economy. The effect of thorium resonance capture in graphite-moderate d systems with median absorption energies in the range from 0.10 to 100 keV have been studied. Narrow-resonance (NR) and wide-resonance (NRIA) formulations are used to obtain the temperature-dependent effective resonance integral of thorium rods which are expressed as equivalent multi-group cross-sections. The need for nuclear data in the intermediate energy range led to design and con- struction of a critical assembly. Nuclear design of this assembly emphasizes the importance of cross-section data and the theoretical interpretation of these experimental results, both pertinent to the design of an AETR. The accuracy of the analytical techniques has been demonstrated in the analysis of ZPR-III experimental results. Three heat-transfer configurations are compared using doubling time as an optimizing parameter. The effect of Pa233 and uranium-isotope s production on relative neutron economy, potential breeding ratios, and burn-up characteristics are evaluated in regard to the uncertainties in the nuclear cross-sections. (author)

  7. The resonance integral of thorium metal rods

    International Nuclear Information System (INIS)

    The resonance integral for thorium metal rods of different diameters has been determined by the activation method. The irradiations took place in the central channel of the reactor R1, where the energy dependence of the neutron flux had earlier been investigated with a fast chopper up to about 1 keV. The absolute calibration was made with gold as a standard. The true resonance integral for gold was taken from the literature as 1,500 ± 35 b. The experimental values for thorium were fitted to two alternative expressions with the following results: RI = (1.70 + 15.9√(S/M)) ± 5.5%; RI 17.3√(S/M + 0.06) ± 5.5 %. The measurements were made for S/M values in the range 0.14 - 0.87 cm2/g. The main contribution to the margin of errors arises from the uncertainties in the cross sections used and in the correction for the departure of the neutron energy distribution from the 1/E form

  8. An evaluation of once-through homogeneous thorium fuel cycle for light water reactors

    International Nuclear Information System (INIS)

    The other ways enhancing the economic potential of thorium fuel has been assessed ; the utilization of lower enriched uranium in thorium-uranium fuel, duplex thorium fuel concept, thorium utilization in the mixed core with uranium fuel assembly and thorium blanket utilization in the uranium core. The fuel economics of the proposed ways of thorium fuel increased compared to the previous homogeneous thorium fuel cycle. Compared to uranium fuel cycle, however, they do not show any economic incentives. From the view of proliferation resistance potential, thorium fuel option has the advantage to reduce the inventory of plutonium production. Any of proposed thorium options are less economical than uranium fuel option, the thorium fuel option has the potential to be utilized in the future for the sake of the effective consumption of excessive plutonium and the preparation against the using up of uranium resource

  9. Thorium-based nuclear fuel: current status and perspectives

    International Nuclear Information System (INIS)

    Until the present time considerable efforts have already been made in the area of fabrication, utilization and reprocessing of Th-based fuels for different types of reactors, namely: by FRG and USA - for HTRs; FRG and Brazil, Italy - for LWRs; India - for HWRs and FBRs. Basic research of thorium fuels and thorium fuel cycles are also being undertaken by Australia, Canada, China, France, FRG, Romania, USSR and other countries. Main emphasis has been given to the utilization of thorium fuels in once-through nuclear fuel cycles, but in some projects closed thorium-uranium or thorium-plutonium fuel cycles are also considered. The purpose of the Technical Committee on the Utilization of Thorium-Based Nuclear Fuel: Current Status and Perspective was to review the world thorium resources, incentives for further exploration, obtained experience in the utilization of Th-based fuels in different types of reactors, basic research, fabrication and reprocessing of Th-based fuels. As a result of the panel discussion the recommendations on future Agency activities and list of major worldwide activities in the area of Th-based fuel were developed. A separate abstract was prepared for each of the 9 papers in this proceedings series

  10. Environmental control technology for mining, milling, and refining thorium

    Energy Technology Data Exchange (ETDEWEB)

    Weakley, S.A.; Blahnik, D.E.; Young, J.K.; Bloomster, C.H.

    1980-02-01

    The purpose of this report is to evaluate, in terms of cost and effectiveness, the various environmental control technologies that would be used to control the radioactive wastes generated in the mining, milling, and refining of thorium from domestic resources. The technologies, in order to be considered for study, had to reduce the radioactivity in the waste streams to meet Atomic Energy Commission (10 CFR 20) standards for natural thorium's maximum permissible concentration (MPC) in air and water. Further regulatory standards or licensing requirements, either federal, state, or local, were not examined. The availability and cost of producing thorium from domestic resources is addressed in a companion volume. The objectives of this study were: (1) to identify the major waste streams generated during the mining, milling, and refining of reactor-grade thorium oxide from domestic resources; and (2) to determine the cost and levels of control of existing and advanced environmental control technologies for these waste streams. Six potential domestic deposits of thorium oxide, in addition to stockpiled thorium sludges, are discussed in this report. A summary of the location and characteristics of the potential domestic thorium resources and the mining, milling, and refining processes that will be needed to produce reactor-grade thorium oxide is presented in Section 2. The wastes from existing and potential domestic thorium oxide mines, mills, and refineries are identified in Section 3. Section 3 also presents the state-of-the-art technology and the costs associated with controlling the wastes from the mines, mills, and refineries. In Section 4, the available environmental control technologies for mines, mills, and refineries are assessed. Section 5 presents the cost and effectiveness estimates for the various environmental control technologies applicable to the mine, mill, and refinery for each domestic resource.

  11. Environmental control technology for mining, milling, and refining thorium

    International Nuclear Information System (INIS)

    The purpose of this report is to evaluate, in terms of cost and effectiveness, the various environmental control technologies that would be used to control the radioactive wastes generated in the mining, milling, and refining of thorium from domestic resources. The technologies, in order to be considered for study, had to reduce the radioactivity in the waste streams to meet Atomic Energy Commission (10 CFR 20) standards for natural thorium's maximum permissible concentration (MPC) in air and water. Further regulatory standards or licensing requirements, either federal, state, or local, were not examined. The availability and cost of producing thorium from domestic resources is addressed in a companion volume. The objectives of this study were: (1) to identify the major waste streams generated during the mining, milling, and refining of reactor-grade thorium oxide from domestic resources; and (2) to determine the cost and levels of control of existing and advanced environmental control technologies for these waste streams. Six potential domestic deposits of thorium oxide, in addition to stockpiled thorium sludges, are discussed in this report. A summary of the location and characteristics of the potential domestic thorium resources and the mining, milling, and refining processes that will be needed to produce reactor-grade thorium oxide is presented in Section 2. The wastes from existing and potential domestic thorium oxide mines, mills, and refineries are identified in Section 3. Section 3 also presents the state-of-the-art technology and the costs associated with controlling the wastes from the mines, mills, and refineries. In Section 4, the available environmental control technologies for mines, mills, and refineries are assessed. Section 5 presents the cost and effectiveness estimates for the various environmental control technologies applicable to the mine, mill, and refinery for each domestic resource

  12. OPTIMIZATION OF HETEROGENEOUS UTILIZATION OF THORIUM IN PWRS TO ENHANCE PROLIFERATION RESISTANCE AND REDUCE WASTE.

    Energy Technology Data Exchange (ETDEWEB)

    TODOSOW,M.; KAZIMI,M.

    2004-08-01

    Issues affecting the implementation, public perception and acceptance of nuclear power include: proliferation, radioactive waste, safety, and economics. The thorium cycle directly addresses the proliferation and waste issues, but optimization studies of core design and fuel management are needed to ensure that it fits within acceptable safety and economic margins. Typical pressurized water reactors, although loaded with uranium fuel, produce 225 to 275 kg of plutonium per gigawatt-year of operation. Although the spent fuel is highly radioactive, it nevertheless offers a potential proliferation pathway because the plutonium is relatively easy to separate, amounts to many critical masses, and does not present any significant intrinsic barrier to weapon assembly. Uranium 233, on the other hand, produced by the irradiation of thorium, although it too can be used in weapons, may be ''denatured'' by the addition of natural, depleted or low enriched uranium. Furthermore, it appears that the chemical behavior of thoria or thoria-urania fuel makes it a more stable medium for the geological disposal of the spent fuel. It is therefore particularly well suited for a once-through fuel cycle. The use of thorium as a fertile material in nuclear fuel has been of interest since the dawn of nuclear power technology due to its abundance and to potential neutronic advantages. Early projects include homogeneous mixtures of thorium and uranium oxides in the BORAX-IV, Indian Point I, and Elk River reactors, as well as heterogeneous mixtures in the Shippingport seed-blanket reactor. However these projects were developed under considerably different circumstances than those which prevail at present. The earlier applications preceded the current proscription, for non-proliferation purposes, of the use of uranium enriched to more than 20 w/o in {sup 235}U, and has in practice generally prohibited the use of uranium highly enriched in {sup 235}U. They were designed when

  13. Radiological impact assessment for near surface disposal of thorium waste

    International Nuclear Information System (INIS)

    Thorium (232Th) itself is not fissile and so is not directly usable in a thermal neutron reactor. However, it is fertile and upon absorbing a neutron will transmute to uranium-233 (233U), which is a fissile fuel material. The thorium fuel fabrication may lead to low level waste comprising of 232Th. This waste may be disposed of in the Near Surface Disposal Facility (NSDF). The very low probability event of leaching of the waste may lead to contamination of the groundwater system. This paper deals with the estimation of the radiological impact of thorium waste disposal in NSDF through groundwater drinking pathway using the Multiple Area Source Model (MASOM). (author)

  14. Some research and development of thorium fuel cycle in Russia

    International Nuclear Information System (INIS)

    There has recently been increasing interest in implementation of thorium into nuclear power. Among the new areas of that interest research in the field of nuclear fuel resources, safety improvement of nuclear reactors and their ecological acceptability should be mentioned. Many specialists consider the proliferation resistance to be the main advantage of thorium fuel cycle. In particular, this advantage leads to some proposals to use thorium-plutonium-based reactor fuel for plutonium utilization. This paper presents an overview of investigation, which are under way at the State Scientific Center - Institute of Physics and Power Engineering in Obninsk, Russia. (author)

  15. Thorium fuel-cycle studies for CANDU reactors

    International Nuclear Information System (INIS)

    The high neutron economy of the CANDU reactor, its ability to be refuelled while operating at full power, its fuel channel design, and its simple fuel bundle provide an evolutionary path for allowing full exploitation of the energy potential of thorium fuel cycles in existing reactors. AECL has done considerable work on many aspects of thorium fuel cycles, including fuel-cycle analysis, reactor physics measurements and analysis, fuel fabrication, irradiation and PIE studies, and waste management studies. Use of the thorium fuel cycle in CANDU reactors ensures long-term supplies of nuclear fuel, using a proven, reliable reactor technology. (author)

  16. Bioaccumulation of uranium and thorium from the solution containing both elements using various microorganisms

    International Nuclear Information System (INIS)

    The effects of proton, thorium and uranium on the bioaccumulation of thorium and uranium from the solution (pH 3.5) containing uranium and thorium using Streptomyces levoris cells were examined. The amount of thorium accumulated using the cells decreased by the pre-contact between the cells and the solution (pH 3.5) containing no metals, whereas that of uranium was almost unaffected by the treatment. The amount of thorium was almost unaffected by the existence of uranium. On the other hand, the amount of uranium accumulated was strongly affected by the thorium, especially thorium addition after uranium accumulation. The decrease of uranium accumulated by the addition of thorium after the accumulation of uranium was higher than that from the solution containing both elements. Therefore, the contribution of uranium-thorium exchange reaction was higher than that of competition reaction. Accordingly, proton-uranium-thorium exchange reaction was occurred in the accumulation of thorium from the solution containing thorium and uranium. The gram-positive bacteria, such as Micrococcus luteus, Arthrobacter nicotianae, Bacillus subtilis and B. megaterium, has a much higher separation factor as thorium/uranium than that of actinomycetes. These gram-positive bacterial strains can be used for the accumulation of thorium from the solution containing uranium and thorium

  17. Bioaccumulation of uranium and thorium from the solution containing both elements using various microorganisms

    Energy Technology Data Exchange (ETDEWEB)

    Tsuruta, T. [Department of Applied Chemistry, Tohwa University, 1-1-1 Chikushigaoka, Fukuoka 815-8510 (Japan)]. E-mail: ttsuruta@tohwa-u.ac.jp

    2006-02-09

    The effects of proton, thorium and uranium on the bioaccumulation of thorium and uranium from the solution (pH 3.5) containing uranium and thorium using Streptomyces levoris cells were examined. The amount of thorium accumulated using the cells decreased by the pre-contact between the cells and the solution (pH 3.5) containing no metals, whereas that of uranium was almost unaffected by the treatment. The amount of thorium was almost unaffected by the existence of uranium. On the other hand, the amount of uranium accumulated was strongly affected by the thorium, especially thorium addition after uranium accumulation. The decrease of uranium accumulated by the addition of thorium after the accumulation of uranium was higher than that from the solution containing both elements. Therefore, the contribution of uranium-thorium exchange reaction was higher than that of competition reaction. Accordingly, proton-uranium-thorium exchange reaction was occurred in the accumulation of thorium from the solution containing thorium and uranium. The gram-positive bacteria, such as Micrococcus luteus, Arthrobacter nicotianae, Bacillus subtilis and B. megaterium, has a much higher separation factor as thorium/uranium than that of actinomycetes. These gram-positive bacterial strains can be used for the accumulation of thorium from the solution containing uranium and thorium.

  18. Development of a methodology for the determination of americium and thorium by ICP-AES and their inter-element effect

    International Nuclear Information System (INIS)

    Due to the scarcity of good quality uranium resources, the growth of nuclear technology in India is dependent on the utilization of the vast thorium resources. Therefore, Advance Heavy Water Reactor is going to acquire significant role in the scenario of Indian nuclear technology, where (Th, Pu)O2 will be utilized as fuel in the outermost ring of the reactor core. This will lead to a complex matrix containing thorium as well as americium, which is formed due to β-decay of plutonium. The amount of americium is dependent on the burn up and the storage time of the Pu based fuels. In the present case, attempt was made to develop a method for the determination of americium as well as thorium by ICP-AES. Two emission lines of americium were identified and calibration curves were established for determination of americium. Though the detection limit of 283.236 nm line (5 ng mL-1) of americium was found to be better than that of 408.930 nm (11 ng mL-1), the former line is significantly interfered by large amount of thorium. Three analytical lines (i.e. 283.242, 283.730 and 401.913 nm) of thorium were identified and calibration curves were established along with their detection limits. It was observed that 283.242 and 401.913 nm line are having similar detection limits (18 and 13 ng mL-1, respectively) which are better than that of 283.730 nm (60 ng mL-1). This can be attributed to the high background of 283.273 nm channel of thorium. The spectral interference study revealed that even small amount of americium has significant contribution on 283.242 nm channel of thorium while the other two channels remain practically unaffected. Considering both these facts, spectral interference and analytical performance (detection limits and sensitivity), it was concluded that 401.913 nm line is the best analytical line out of the three lines for determination of thorium in presence of americium. (author)

  19. Biosorption of uranium, thorium and radium

    International Nuclear Information System (INIS)

    The present study provides a historical background of uranium ore processing, radium extraction, and thorium production; a summary of the development of environmental regulations relative to uranium mill tailing (UMT) management; and an overview of the major factors influencing the biosorption of radionuclides. In addition, kinetic and mass transfer parameters of uranium uptake from synthetic solutions and UMT effluents by calcium alginate beads were determined. Kinetic values vm and K for uranium biosorption were calculated to be 10.3 mg/L/min and 63 g bead/L, respectively. A mathematical expression was derived to determine the associated biosorption diffusion coefficient which was calculated to be 9.20 x 10-8 cm2/s. The importance of these findings as they relate to the literature are discussed

  20. Neutron scattering from elemental uranium and thorium

    International Nuclear Information System (INIS)

    Differential neutron-scattering cross sections of elemental uranium and thorium are measured from ∼ 4.5 to 10.0 MeV in steps of ∼ 0.5 MeV. Forty or more differential values are obtained at each incident energy, distributed between ∼ 17 degree and 160 degree. Scattered-neutron resolutions are carefully defined to encompass contributions from the first four members of the ground-state rotational band (02 g.s., 2+, 4+ and 6+ states). The experimental results are interpreted in the context of coupled-channels rotational models, and comparisons made with the respective ENDF/B-VI evaluated files. These comparisons suggest some modifications of the ENDF/B-VI 238U and 232Th evaluations

  1. KNOW YOUR NEVADA INDIANS.

    Science.gov (United States)

    POEHLMAN, CHARLES H.; AND OTHERS

    THIS PUBLICATION PRESENTS THE RESULTS OF A STUDY OF THE SOCIOCULTURAL BACKGROUNDS OF THE PAIUTE, WASHOE, AND SHOSHONE INDIANS OF NEVADA. INCLUDED ARE AN OUTLINE OF GENERAL PROBLEMS PERTAINING TO INDIAN EDUCATION, SOME DISTINCT CULTURAL DIFFERENCES BETWEEN THE DOMINANT NON-INDIAN SOCIETY AND THE INDIAN SOCIETY, AND THE PREHISTORIC ASPECTS OF THE…

  2. Thor, a thorium-reflected plutonium-metal critical assembly

    International Nuclear Information System (INIS)

    Critical specifications of Thor, an old assembly of thorium-reflected plutonium, have been refined. These specifications are brought together with void coefficients, Rossi-alpha values, fission traverses, and spectral indices

  3. Program of Environmental monitoring in uranium and thorium mines

    International Nuclear Information System (INIS)

    This work suggests a plan for the elaboration of a program of environmental monitoring of radioactive pollutants around mining of uranium and thorium with the purpose of protecting the man and the environment

  4. Assessment of thorium in the environment (a review)

    International Nuclear Information System (INIS)

    Thorium, the radioactive metal, present in natural sediments produced in the form of detritus minerals such as monazite, rutile, granitic complexes, syenitic complexes, thorite, thorianite and progenitor of U, Th and Ac series. It is used in variety of industrial purposes, medical applications and proposed as fissile material for nuclear energy via production of U from Th. Anthropogenic process including modern trends in agriculture causes environmental pollution and also affect the biochemical cycle. However, changes in pH or different redox conditions of rocks enable a fraction of thorium to be released in the environment eventually. This review focuses on the radiochemical techniques, such as alpha, gamma spectroscopy as well as inductively coupled plasma mass spectrometry (ICP-MS) that are used for the measurement of thorium. A survey of current research activities intend to control the incorporation of thorium in order to minimize internal doses has been performed. (author)

  5. Tables for determining lead, uranium, and thorium isotope ages

    Science.gov (United States)

    Schonfeld, E.

    1974-01-01

    Tables for determining lead, uranium, and thorium isotope ages are presented in the form of computer printouts. Decay constants, analytical expressions for the functions evaluated, and the precision of the calculations are briefly discussed.

  6. Treatment of uranium and thorium bearing nitrate effluent

    International Nuclear Information System (INIS)

    Indigenously designed Advanced Heavy Water Reactor utilises (Th-LEU)O2 MOX as the fuel. During fabrication of MOX fuel, pellets not meeting the quality requirements will be recycled by wet processing for the recovery of uranium and thorium. The present study investigates the feasibility of various processes on the treatment of thorium bearing effluent arising from wet processing of reject MOX pellets. Process involving the reductive precipitation of uranium by sodium dithionite followed by adsorption of thorium onto inorganic sorbent, MST was developed and optimized. Reproducibility of the process under scale up conditions was also established. Under the optimized parameters, percentage removal obtained for uranium, thorium and radium was 99%, 97% and 98% respectively. (author)

  7. Conceptual design of loop-in-tank type Indian molten salt breeder reactor concept

    International Nuclear Information System (INIS)

    The third stage of Indian nuclear power programme envisages use of thorium as fertile material with 233U, which is proposed to be obtained from reprocessing of spent fuel of Pu/Th based fast reactors in the later part of the second stage of the programme. In India, thorium based reactors have been designed in many configurations, from light water cooled designs to high temperature liquid metal and molten salt cooled options. Another option, which holds promise, is the molten salt-fuelled reactor, which can be configured to give significant breeding ratios. A crucial part for achieving reasonable breeding in such reactors is the need to reprocess the salt continuously, either online or in batch mode. India has recently started carrying out fundamental studies so as to arrive at a conceptual design of Indian Molten Salt Breeder Reactor (IMSBR). (author)

  8. Irradiation of thorium based fuels at research reactors of Trombay

    International Nuclear Information System (INIS)

    Utilization of large thorium reserve of our country for power production had been a prime goal from the inception of our three stage nuclear power programme. This long term policy is well reflected in irradiation programme of Thoria and Thorium rods at research reactors Cirus and Dhruva, located at Trombay. The first batch of Thorium/Thoria rods were loaded in Cirus reactor on August 28, 1960, immediately after attaining first criticality on July 10, 1960 which reflects the priority the Thorium utilization programme received from our planners. The programme was aimed for gaining sufficient experience with Thorium fuel cycle by the time our first stage of nuclear power programme attained maturity. In Cirus, these rods are irradiated in the annular gap, called J-rod annulus, between the two graphite reflectors around the pile. About 200 Thorium/Thoria rods had been irradiated in Cirus before the reactor was shut down permanently on 31st December 2010. A few Thoria assemblies have also been irradiated in fuel positions of Dhruva reactor. Apart from these, a few fuel assemblies made of ThO2, PuO2 and UO2 were irradiated in Pressurized Water Loop of Cirus to study fuel and clad behavior under high temperature and pressure, before their induction in power programme. Presently, fuel cluster with AHWR type Th-Pu and Th-LEU MOX fuel pins are being irradiated in a regular fuel position of Dhruva for obtaining vital information and experience related to Thorium based MOX fuel cycle. This paper highlights the experience gained in irradiation of Thoria/Thorium rods, expected yield of 233U, contamination level of 232U and handling of these assemblies at research reactors Cirus and Dhruva. (author)

  9. The use of thorium as an alternative nuclear fuel

    International Nuclear Information System (INIS)

    The use of thorium as an alternative or supplementary nuclear fuel is examined and compared with uranium. A description of various reactor types and their suitability to thorium fuel, and a description of various aspects of the fuel cycle from mining to waste disposal, are included. Comments are made on the safety and economics of each aspect of the fuel cycle and the extension of the lifetime of nuclear fuel

  10. The indispensable role of thorium for creating a sustainable society

    International Nuclear Information System (INIS)

    Several approaches are required in parallel for constructing a sustainable society. One of them is to fight against global warming. The other one is to make this world nuclear weapon free. Nuclear power has been used for peaceful purpose because nuclear power produces electricity without emitting CO2. Nearly 15% of world electricity is produced by nuclear power. Through nuclear power plant has a possibility of severe accident such as Fukushima Daiichi, its advantage is still valuable for the world. President Obama's speech in Prague in 2009 brought a impact to the world to move toward the world without nuclear weapon. The remaining subject is how to treat dismantled fissionable materials. Existing nuclear power plants utilize uranium because only uranium contains natural occurring fissionable material, uranium-235. The spent uranium fuel contains fissionable plutonium-239. Thus, uranium fuel cycle always accompanies possibility of nuclear proliferation. Thorium plays an important role for both solving global warming and nuclear weapon. Fertile thorium can be used as nuclear fuel by support of fissionable plutonium-239 from spent uranium fuel or weapon head. Preliminary calculation indicates that the USA's and Russia's dismantle nuclear weapon enable to start more than 10 GWe of thorium nuclear power plants. In addition, plutonium-239 obtained from uranium fuel is available of 392 GWe of thorium nuclear power. Uranium-233 coming from thorium is also a fissionable but it is hard to be used for weapon because of its accompanied gamma-ray. Thorium itself is now obtained as by-product of rare-earth mining, which is used for high-tech products including photovoltaic cell, wind-mill, and hybrid-vehicle. However, thorium is not taken care adequately and becomes environmental hazard. Both to take care of environment, to support implementation of high-tech product and to make the world without nuclear weapon, a comprehensive role of thorium will be presented

  11. Method of synthesis of anhydrous thorium(IV) complexes

    Science.gov (United States)

    Kiplinger, Jaqueline L; Cantat, Thibault

    2013-04-30

    Method of producing anhydrous thorium(IV) tetrahalide complexes, utilizing Th(NO.sub.3).sub.4(H.sub.2O).sub.x, where x is at least 4, as a reagent; method of producing thorium-containing complexes utilizing ThCl.sub.4(DME).sub.2 as a precursor; method of producing purified ThCl.sub.4(ligand).sub.x compounds, where x is from 2 to 9; and novel compounds having the structures: ##STR00001##

  12. The use of thorium for plutonium utilization in reactors

    International Nuclear Information System (INIS)

    cycle with a full-scale use of thorium is only a far perspective for Russia. Resources of uranium for NPPs with thermal neutron reactors will be sufficient for decades in Russia and involvement of fast neutron reactors into power system makes the problem of raw resources less actual. However, in Russia research works on uranium-plutonium cycle were closely followed by those on thorium-based one. Of course scales of those research works were incomparable. But recently the peculiarities, problems, and perspectives of thorium-based cycle have been discussed more actively in Russia and abroad. Besides, experts have realized that application of thorium-based cycle, at least in the nearest future, will be most probably evolutional, which does not demand any radical changes in the existing fuel cycle. At the same time, some useful features of thorium can be used in a short term. The possibility of using thorium in the process of plutonium utilization is one of such useful properties; in this case, unlike MOX fuel, the plutonium breeding is excluded. The feasibility to include plutonium and thorium into a fuel cycle of Russian light-water reactors WWER-1000 is also touched upon in this report. Once-through fuel recycle has been considered, the final decision on its further utilization being postponed. Basic fuel parameters and properties, important from safety standpoint, are presented. The minimum changes in the structure necessary to ensure safety of plutonium-thorium fuel at the level of conventional WWER-1000 are needed. A wide range of problems investigated and to be investigated is outlined in the paper. (author)

  13. Techno-economic assessment of thorium power in Canada

    International Nuclear Information System (INIS)

    Highlights: • Costs of replacing uranium in Canada’s nuclear reactors with thorium evaluated. • Results show a thorium plant to be more financially lucrative than a uranium plant. • Results were most sensitive to electricity price, then capital and decommissioning cost. • Abatement cost analysis showed nuclear power offers cost savings over fossil fuels. - Abstract: Thorium fission is a large yet relatively unexplored renewable energy source and could help feed increasing energy demands. An analysis was performed on the feasibility of replacing the uranium in Canada’s nuclear reactors with thorium. Thorium only exists as a fertile isotope, and so an external fissile source such as 235U, 233U, or 239Pu is required to stimulate the fission process. A uranium plant and a similar thorium-fuelled plant were compared over a 40 year operational life based on a comprehensive economic analysis. The results from the economic analysis were used to estimate the greenhouse gas (GHG) abatement cost compared to the coal and natural gas-based power. The economic analysis determined that a thorium plant is more financially lucrative in Canada than a uranium plant. An abatement cost assessment in relation to gas-fired and coal-fired power plants demonstrated that nuclear power offers a cost savings per tonne of CO2 equivalent greenhouse gas (GHG) when compared to both fossil fuel alternatives. From the values determined for a plant potentially fuelled on thorium, the abatement cost when compared to the coal-fired and gas-fired plants is −$10.4/tonne-CO2eq and −$15.7/tonne-CO2eq, respectively

  14. Thorium survey using thermoluminescence radiation dosimetry (Cerro Impacto, Venezuela)

    International Nuclear Information System (INIS)

    Calibrated thermoluminescent dosimeters of LiF were utilized to map the radiation flux 0.5m beneath the surface of a thorium-rare-earth elements deposit in southern Venezuela. The isorad map obtained from measurements of the thermoluminescence induced in the buried dosimeters during their eight-month exposure period at the site, agrees well with the mapped thorium concentration at the surface of the deposit. The results indicate that thermoluminescence radiation dosimetry can be used for radiometric prospecting

  15. Material requirements for a thorium based nuclear fuel

    OpenAIRE

    Galiana Gonzalez, Bernat

    2010-01-01

    The increase in the energy consumption and the expected growth in the nuclear capacity make it necessary to look for alternative fuels to replace uranium. The fuel chosen, which was also considered in the early stages of nuclear energy, is thorium. Thorium has some characteristics that make it valuable as a fuel, like its abundance, the low radiotoxicity of the waste generated, the higher economy regarding its larger absorption cross-section and higher burnups and the prolifera...

  16. Estimating terrestrial uranium and thorium by antineutrino flux measurements

    OpenAIRE

    Dye, Stephen T.; Guillian, Eugene H.

    2008-01-01

    Uranium and thorium within the Earth produce a major portion of terrestrial heat along with a measurable flux of electron antineutrinos. These elements are key components in geophysical and geochemical models. Their quantity and distribution drive the dynamics, define the thermal history, and are a consequence of the differentiation of the Earth. Knowledge of uranium and thorium concentrations in geological reservoirs relies largely on geochemical model calculations. This research report desc...

  17. Separation of Protactinium from Neutron Irradiated Thorium Oxide

    International Nuclear Information System (INIS)

    The chemical separation of thorium and protactinium can be carried out by leaching most of the last one, about 95%, with aqueous HF from neutron irradiated thorium oxide. This leaching reaction la highly favored by the transformation reaction of the ThO2 material into ThF4. For both reactions, leaching and transformation, the reagents concentration, agitation speed and temperature influences were studied and the activation energies were found. (Author) 18 refs

  18. Uranium and thorium behavior at aluminium floating-zone refining

    International Nuclear Information System (INIS)

    Uranium and thorium behaviour during aluminium refining by crystallization from the melt is ascertained. Measurements of of uranium and thorium radioactive impurities content in high-purity aluminiumn samples using the surface α-activity method are carried out. The content of the given impurities happened to be less than 1 x 10-7 mass.%. Such purity satisfies the requirements to materials applied in the low background 71Ge detection system of gallium-germanium solar neutrino detector

  19. An assessment of once-through homogeneous thorium fuel economics for light water reactors

    International Nuclear Information System (INIS)

    The fuel economics of an once-through homogeneous thorium fuel concept for PWR was assessed by doing a detailed core analysis. In addition to this, the fuel economics assessment was also performed for two other ways enhancing the economic potential of thorium fuel; thorium utilization in the mixed core with uranium fuel assembly and Duplex thorium fuel concepts. As a results of fuel economics assessment, the thorium fuel cycle does not show any economic incentives in preference to uranium fuel cycle under the 18-months fuel cycle for PWR. However, the utilization of thorium is the mixed core with uranium fuel assembly and Duplex thorium fuel cycle and show superior fuel economics to uranium fuel under the longer fuel cycle scheme. The economic potential of once-through thorium fuel cycle is expected to be increased further by utilizing the Duplex thorium fuel in the mixed core with uranium fuel assembly

  20. U.S. leans toward denatured thorium cycle

    International Nuclear Information System (INIS)

    Denatured thorium appears to be the most promising among the nonproliferating alternatives to the plutonium cycle, which the Carter Administration is trying to cancel. Criteria for a better system include uranium utilization comparable to current light water reactors and minimal separation of fissile material into the waste stream. Comparisons with other systems conclude that thorium is preferable because it can lead to an acceptable fast breeder. The thorium cycle can be placed in energy centers for sensitive facilities and can also be introduced into ongoing light water systems. Reprocessing can be handled in the centers, where thorium can be mixed with plutonium for use in reactors within the center, while light water reactors operate on the outside. Any fuel leaving the center would be unsuitable for weapons. Later adaptation to in-center fast breeders will extend energy supplies, although a thorium breeder will be less efficient than a plutonium fast breeder. Denatured thorium is a technical answer to a complex political problem, but those in the nuclear industry see the U.S. goal of a nonproliferating fuel as futile in the light of world politics and breeder efforts in other countries

  1. A study of functions of 'the bank (thorium energy bank)'

    International Nuclear Information System (INIS)

    Several approaches are required in parallel for constructing a sustainable society. One of them is to fight against global warming. Nuclear power has been used for peaceful purpose because nuclear power produces electricity without emitting CO2. Though nuclear power plant has a possibility of severe accident such as the Fukushima Dai-ichi accident, its advantage is still valuable for the world. Thorium plays an important role for solving global warming. Fertile thorium can be used as nuclear fuel by support of fissionable plutonium-239 from spent uranium fuel. Plutonium-239 obtained from uranium fuel enables implementing 392 GWe of thorium nuclear power. Thorium itself is now obtained as a by-product of rare-earth mining, which is used for high-tech products including photovoltaic cell, wind-mill, and electric vehicle. However, thorium is not taken care of environmental hazard adequately so far. Both to take care of environment and to support implementation of high-tech product, and international framework of storage of thorium will be presented. (author)

  2. Dynamic Analysis of the Thorium Fuel Cycle in CANDU Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Chang Joon; Park, Chang Je

    2006-02-15

    The thorium fuel recycle scenarios through the Canada deuterium uranium (CANDU) reactor have been analyzed for two types of thorium fuel: homogeneous ThO{sub 2}UO{sub 2} and ThO{sub 2}UO{sub 2}-DUPIC fuels. The recycling is performed through the dry process fuel technology which has a proliferation resistance. For the once-through fuel cycle model, the existing nuclear power plant construction plan was considered up to 2016, while the nuclear demand growth rate from the year 2016 was assumed to be 0%. After setting up the once-through fuel cycle model, the thorium fuel CANDU reactor was modeled to investigate the fuel cycle parameters. In this analysis, the spent fuel inventory as well as the amount of plutonium, minor actinides and fission products of the multiple recycling fuel cycle were estimated and compared to those of the once-through fuel cycle. From the analysis results, it was found that the closed or partially closed thorium fuel cycle can be constructed through the dry process technology. Also, it is known that both the homogeneous and heterogeneous thorium fuel cycles can reduce the SF accumulation and save the natural uranium resource compared with the once-through cycle. From the material balance view point, the heterogeneous thorium fuel cycle seems to be more feasible. It is recommended, however, the economic analysis should be performed in future.

  3. Evaluation of thorium based nuclear fuel. Extended summary

    International Nuclear Information System (INIS)

    Application of thorium based nuclear fuels has been evaluated with emphasis on possible reduction of the actinide waste. As a result three ECN-reports are published, discussing in detail: - The reactor physics aspects, by comparing the operation characteristics of the cores of Pressurized Water Reactors and Heavy Water Reactors with different fuel types, including equilibrium thorium/uranium free, once-through uranium fuel and equilibrium uranium/plutonium fuel, - the chemical aspects of thorium based fuel cycles with emphasis on fuel (re)fabrication and fuel reprocessing, - the possible reduction in actinide waste as analysed for Heavy Water Reactors with various types of thorium based fuels in once-through operation and with reprocessing. These results are summarized in this report together with a short discussion on non-proliferation and uranium resource utilization. It has been concluded that a substantial reduction of actinide radiotoxicity of the disposed waste may be achieved by using thorium based fuels, if very efficient partitioning and multiple recycling of uranium and thorium can be realized. This will, however, require large efforts to develop the technology to the necessary industrial scale of operation. (orig.)

  4. Determination of the total nitrate content of thorium nitrate solution with a selective electrode

    International Nuclear Information System (INIS)

    The nitrate content of thorium nitrate solutions is determined with a liquid membrane nitrate selective electrode utilizing the known addition method in 0.1 M potassium fluoride medium as ionic strength adjustor. It is studied the influence of pH and the presence of chloride, sulphate, phosphate, meta-silicate, thorium, rare earths, iron, titanium, uranium and zirconium at the same concentrations as for the aqueous feed solutions in the thorium purification process. The method is tested in synthetic samples and in samples proceeding from nitric dissolutions of thorium hidroxide and thorium oxicarbonate utilized as thorium concentrates to be purified

  5. Economics of large-scale thorium oxide production: assessment of domestic resources

    Energy Technology Data Exchange (ETDEWEB)

    Young, J.K.; Bloomster, C.H.; Enderlin, W.I.; Morgenstern, M.H.; Ballinger, M.Y.; Drost, M.K.; Weakley, S.A.

    1980-02-01

    The supply curve illustrates that sufficient amounts of thorium exist supply a domestic thorium-reactor economy. Most likely costs of production range from $3 to $60/lb ThO/sub 2/. Near-term thorium oxide resources include the stockpiles in Ohio, Maryland, and Tennessee and the thorite deposits at Hall Mountain, Idaho. Costs are under $10/lb thorium oxide. Longer term economic deposits include Wet Mountain, Colorado; Lemhi Pass, Idaho; and Palmer, Michigan. Most likely costs are under $20/lb thorium oxide. Long-term deposits include Bald Mountain, Wyoming; Bear Lodge, Wyoming; and Conway, New Hampshire. Costs approximately equal or exceed $50/lb thorium oxide.

  6. Thorium as an energy source. Opportunities for Norway

    Energy Technology Data Exchange (ETDEWEB)

    2008-01-15

    Final Recommendations of the Thorium Report Committee: 1) No technology should be idolized or demonized. All carbon-dioxide (Co2) emission-free energy production technologies should be considered. The potential contribution of nuclear energy to a sustainable energy future should be recognized. 2) An investigation into the resources in the Fen Complex and other sites in Norway should be performed. It is essential to assess whether thorium in Norwegian rocks can be defined as an economical asset for the benefit of future generations. Furthermore, the application of new technologies for the extraction of thorium from the available mineral sources should be studied. 3) Testing of thorium fuel in the Halden Reactor should be encouraged, taking benefit of the well recognized nuclear fuel competence in Halden. 4) Norway should strengthen its participation in international collaborations by joining the EURATOM fission program and the GIF program on Generation IV reactors suitable for the use of thorium. 5) The development of an Accelerator Driven System (ADS) using thorium is not within the capability of Norway working alone. Joining the European effort in this field should be considered. Norwegian research groups should be encouraged to participate in relevant international projects, although these are currently focused on waste management. 6) Norway should bring its competence in waste management up to an international standard and collaboration with Sweden and Finland could be beneficial. 7) Norway should bring its competence with respect to dose assessment related to the thorium cycle up to an international standard. 8) Since the proliferation resistance of uranium-233 depends on the reactor and reprocessing technologies, this aspect will be of key concern should any thorium reactor be built in Norway. 9) Any new nuclear activities in Norway, e.g. thorium fuel cycles, would need strong international pooling of human resources, and in the case of thorium, a strong long

  7. Thorium as an energy source. Opportunities for Norway

    International Nuclear Information System (INIS)

    Final Recommendations of the Thorium Report Committee: 1) No technology should be idolized or demonized. All carbon-dioxide (Co2) emission-free energy production technologies should be considered. The potential contribution of nuclear energy to a sustainable energy future should be recognized. 2) An investigation into the resources in the Fen Complex and other sites in Norway should be performed. It is essential to assess whether thorium in Norwegian rocks can be defined as an economical asset for the benefit of future generations. Furthermore, the application of new technologies for the extraction of thorium from the available mineral sources should be studied. 3) Testing of thorium fuel in the Halden Reactor should be encouraged, taking benefit of the well recognized nuclear fuel competence in Halden. 4) Norway should strengthen its participation in international collaborations by joining the EURATOM fission program and the GIF program on Generation IV reactors suitable for the use of thorium. 5) The development of an Accelerator Driven System (ADS) using thorium is not within the capability of Norway working alone. Joining the European effort in this field should be considered. Norwegian research groups should be encouraged to participate in relevant international projects, although these are currently focused on waste management. 6) Norway should bring its competence in waste management up to an international standard and collaboration with Sweden and Finland could be beneficial. 7) Norway should bring its competence with respect to dose assessment related to the thorium cycle up to an international standard. 8) Since the proliferation resistance of uranium-233 depends on the reactor and reprocessing technologies, this aspect will be of key concern should any thorium reactor be built in Norway. 9) Any new nuclear activities in Norway, e.g. thorium fuel cycles, would need strong international pooling of human resources, and in the case of thorium, a strong long

  8. The influence of different hydroponic conditions on thorium uptake by Brassica juncea var. foliosa.

    Science.gov (United States)

    Wang, Dingna; Zhou, Sai; Liu, Li; Du, Liang; Wang, Jianmei; Huang, Zhenling; Ma, Lijian; Ding, Songdong; Zhang, Dong; Wang, Ruibing; Jin, Yongdong; Xia, Chuanqin

    2015-05-01

    The effects of different hydroponic conditions (such as concentration of thorium (Th), pH, carbonate, phosphate, organic acids, and cations) on thorium uptake by Brassica juncea var. foliosa were evaluated. The results showed that acidic cultivation solutions enhanced thorium accumulation in the plants. Phosphate and carbonate inhibited thorium accumulation in plants, possibly due to the formation of Th(HPO4)(2+), Th(HPO4)2, or Th(OH)3CO3 (-) with Th(4+), which was disadvantageous for thorium uptake in the plants. Organic aids (citric acid, oxalic acid, lactic acid) inhibited thorium accumulation in roots and increased thorium content in the shoots, which suggested that the thorium-organic complexes did not remain in the roots and were beneficial for thorium transfer from the roots to the shoots. Among three cations (such as calcium ion (Ca(2+)), ferrous ion (Fe(2+)), and zinc ion (Zn(2+))) in hydroponic media, Zn(2+) had no significant influence on thorium accumulation in the roots, Fe(2+) inhibited thorium accumulation in the roots, and Ca(2+) was found to facilitate thorium accumulation in the roots to a certain extent. This research will help to further understand the mechanism of thorium uptake in plants. PMID:25475618

  9. Laser spectroscopy of trapped thorium ions

    Energy Technology Data Exchange (ETDEWEB)

    Herrera-Sancho, Oscar-Andrey; Okhapkin, Maxim; Zimmermann, Kai; Tamm, Christian; Peik, Ekkehard [Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig (Germany); Taichenachev, Alexey; Yudin, Valeriy [Institute of Laser Physics, Siberian Branch of RAS, Novosibirsk 630090 (Russian Federation)

    2011-07-01

    In our experiment more than 10{sup 5} {sup 232}Th{sup +} ions are stored in a linear Paul trap after creation by laser ablation from thorium metal. Single-frequency laser excitation in the complex spectrum of Th{sup +} poses the problem that spontaneous decay populates a number of metastable levels that are decoupled from the laser. Helium and Argon buffer gas are used for collisional cooling and quenching of those levels. We observe laser excitation of the strong resonance line at 401.9 nm with an extended-cavity diode laser and laser excitation of several other transitions around 400 nm and 270 nm with harmonics of a pico-second Ti:Sa laser. In a theoretical analysis we approximate the dense electronic level structure of Th{sup +} ions by just four levels: the ground state and an excited state are coupled by the primary laser, one metastable state is depopulated by a repumper laser and one level by collisions only. The model agrees with experimental results for the fluorescence rate as a function of the laser intensities and can be used to deduce populations and quenching rates. First investigations on two-photon excitation of the Th{sup +} electron shell to the energy range 7.8 eV of the nuclear transition of {sup 229}Th are in progress.

  10. Uranium and thorium migration under dislocative metamorphism

    International Nuclear Information System (INIS)

    Investigated were peculiarities of uranium and thorium behaviour in the process of dislocation metamorphism on the basis of regional fracture zones of early-proterozoic embedding of Ukrainian, Aldan and Baltic shields. The studied zones correspond to tectonite of green-shale and almandin-amphibolite facies of regional metamorphism according to mineral associations. The most peculiar feature of the tectonites of green-shale facies is uranium presence in migrationally able forms, which can be involved afterwards into the ore process by hydrothermal solutions. Adsorved forms of uranium on the crystal surface or separate grains and in the cracks, as well as microinclusions of uranium minerals, selectively timed to mineral structure defects prevail among easily mobile uranium compounds. Dissolved uranium is present, evidently in gas-liquid inclusions in minerals and pore waters. There forms of uranium presence are peculiar for epidote-chlorite mylonites, as well as cataclasites and diaphthorites related to them by blastomylonites of almandin-amphibolite facies. Wide range of manifestation of this process, caused by multikilometer extension of deep fracture zones permit to consider the formations of green-shale facies of dislocation metamorphism as one of the main uranium sources in deposit formation in different uranium-ore associations different age

  11. IRIS reactor core with thorium fuel

    International Nuclear Information System (INIS)

    This work is aimed at running the first IRIS reactor core with mixed thorium dioxide fuel (ThO2-UO2 and ThO2-PuO2). Calculations are performed by using Dragon 4.0.4 and Citation codes. The results show the multiplication factor(Keff) for central and peripheral assemblies as a function of burnup. To ensure the proliferation resistance,the value of 235U enrichment is ≤ 20%. The Keff is calculated using Dragon 4.0.4 for a single fuel rod and the model developed to fuel assembly, while the whole core was calculated using Citation code. For a fuel burnup, the use of increased enrichment fuel in the IRIS core leads to high reserve of reactivity, which is compensated with an integral fuel burnable absorber. The self-shielding of boron is in an IRIS reactor fuel. The effect of increased enrichment to the burn-up rates, and burnable poison distribution on the reactor performance, are evaluated. The equipment used in traditional light water reactors is evaluated for designing a small unit IRIS reactor. (authors)

  12. Thorium Nitrate Stockpile Drum Characterization Report

    International Nuclear Information System (INIS)

    Thorium nitrate (ThN) has been stored at depots for several decades and the Defense National Stockpile Center (DNSC) has evaluated options for its disposition. In support of this project, Oak Ridge National Laboratory (ORNL) has directed a characterization campaign for the ThN. The analytical results lead to the following conclusions: the ThN could be classified as LSA-1; the ThN does not contain hazardous contaminants at concentrations that would cause it to be categorized as a mixed waste if were declared to be a waste; the ThN is not required to be classfied as a Division 5.1 oxidizer per the US Dept. of Transportation definition; and, the disposal of the ThN would not be regulated by the Resource Conservation and Recovery Act and thus it could be accepted for disposal at the Nevada Test Site. This report disucsses the regulatory requirements involved with the packaging, transportation, and disposal of the ThN stockpile at the NTS. It also provides background information about the ThN stockpile, the current packaging configurations, and the current storage arrangements. The reader is also provided a description of the ThN and headspace gas sampling activities that wer conducted in 2002 and 2003 respectively. The basis for using ISO containers to transport and dispose of the ThN is discussed

  13. Electrochemical and Microscopic Study of Thorium in a Molten Fluoride System

    Czech Academy of Sciences Publication Activity Database

    Straka, M.; Szatmary, L.; Šubrt, Jan

    2015-01-01

    Roč. 162, č. 9 (2015), "D449"-"D456". ISSN 0013-4651 Institutional support: RVO:61388980 Keywords : cyclic voltametry * electrolysis * thorium fluoride * thorium separation Subject RIV: CA - Inorganic Chemistry Impact factor: 3.266, year: 2014

  14. Study and suggestions on development of the thorium fuel cycle in China

    International Nuclear Information System (INIS)

    The features of thorium fuel cycle are analyzed and an overview of development of the thorium fuel cycle is carried out. On the basis of detailed analyses on potentials of utilizing thorium resources in all kinds of reactors, suggestions on development of the thorium fuel cycle in our country are put forward following the outlook of sustainable development of nuclear energy: (1) current reactors can't make full use of thorium resources from industrial viewpoints other than HTRs; (2) an advanced synergic fuel cycle of fast reactors and thermal reactors is suggested to utilize thorium resources; (3) more R and D efforts should be devoted on advanced and immature reactor technologies instead of the thorium utilization of these reactors; (4) currently much fundamental research work on the thorium utilization should be done. (authors)

  15. Thorium based fuel options for the generation of electricity: Developments in the 1990s

    International Nuclear Information System (INIS)

    The IAEA has maintained an interest in the thorium fuel cycle and its worldwide utilization within its framework of activities. Periodic reviews have assessed the current status of this fuel cycle, worldwide applications, economic benefits, and perceived advantages with respect to other nuclear fuel cycles. Since 1994, the IAEA convened a number of technical meetings on the thorium fuel cycle and related issues. Between 1995 and 1997 individual contributions on the thorium fuel cycle were elicited from experts from France, Germany, India, Japan, the Russian Federation and the USA. These contributions included evaluations of the status of the thorium fuel cycle worldwide; the new incentives to use thorium due to large stockpiles of plutonium produced in nuclear reactors; new reactor concepts utilizing thorium; strategies for thorium use; and an evaluation of toxicity of the thorium fuel cycle waste compared to that from other fuel cycles. The results of this updated evaluation are summarized in this publication

  16. Ultra-long cycle SMART core design using thorium fuel

    International Nuclear Information System (INIS)

    A ultra-long cycle(5 years) SMART core design is examined using the thorium fuel. Most of design configurations of SMART core such as fuel loading pattern, control rod management strategy, and burnable absorber material remain unchanged but uranium fuel which is replaced with a homogeneous mixture of 20% enriched uranium and thorium. The number of burnable absorber pins of the thorium loaded SMART core was adjusted to control the excess reactivity during the cycle burnup. It was shown that mixing ratio of 40:60 of uranium fuel and thorium fuel is necessary to achieve a 5 year cycle length of SMART core. The results also show that the ultra-longer cycle SMART core satisfying all design constraints such as Fq less than 2.5, axial offset less than 0.3, keff less than 0.95 when refueling shutdown margin of 1% with most reactive control rod stuck, and ejected rod worth less than 250 pcm, are possible by using thorium fuel and absorber materials effectively

  17. Chelation therapy of thorium deposited in rat lung

    International Nuclear Information System (INIS)

    The effect of calcium diethylenetriaminepentaacetate (CaDTPA) and a siderophore analogue 3,4,3-LI(1,2-HOPO) on decorporation of small and large thorium masses (234Th 46 ng, 234Th 46 ng + 232Th 5 μg per rat) instilled into the lungs was studied. Along with repeated injections, chelating agents were administered continuously by mini-osmotic pumps over 14 d. Treatment with CaDTPA alone was partly successful in the decorporation of both thorium masses. Greater decorporation was achieved with 3,4,3-LI(1,2-HOPO) in pumps and CaDTPA in injections. In the whole body, lungs and skeleton, 23%, 24% and 24% of control radioactivity was found, respectively, for the small mass of thorium. When the large mass of thorium was instilled, only continuous infusion of 3,4,3-LI(1,2-HOPO) at low concentration efficiently prevented transfer of thorium to the skeleton (reduced to 9% of control). Both the whole body and lungs retained 50% of control radioactivity. (author)

  18. A proposal for rational thorium utilization: thorims-nes

    International Nuclear Information System (INIS)

    In this study, a globally applicable system depending on a new philosophy has been introduced for solving the problems connected with nuclear safety, ratio-waste, anti-nuclear proliferation and terrorism and public/institutional acceptance and economy. This rational thorium breeding fuel-cycle system named as THORIMS-NES (Thorium Molten- Salt Nuclear Energy Synergetics ) appears to be particularly promising and can be the way of nuclear power development. THORIMS-NES depends on three principles: I. Thorium utilization, II. Application of molten-fluoride fuel technology and III. Separation of fissile producing breeders and power producing reactors. Thorium fuel cycle has benefit on the reduction of trans-U elements and for recycling fuels produced by all kinds of military, research and industrial reactors. A system for the realization of THORIMS-NES has been introduced by the explanation of connections/relations between facilities. In this study, the status of countries/groups working on Th and Th fuel cycle has been summarized. Additionally, the resultant announcement of the International Conference on Thorium Molten Salt Reactor Development (8-11 April, 1997, Santa Monica) has been mentioned to present the cooperation of scientists and engineers for the realization of THORIMS-NES

  19. Uranium and thorium recovery in thorianite ore-preliminary results

    Energy Technology Data Exchange (ETDEWEB)

    Gaiotte, Joao V.M. [Universidade Federal de Alfenas, Pocos de Caldas, MG (Brazil); Villegas, Raul A.S.; Fukuma, Henrique T., E-mail: rvillegas@cnen.gov.br, E-mail: htfukuma@cnen.gov.br [Comissao Nacional de Energia Nuclear (CNEN), Pocos de Caldas, MG (Brazil). Lab. de Pocos de Caldas

    2011-07-01

    This work presents the preliminary results of the studies aiming to develop a hydrometallurgical process to produce uranium and thorium concentrates from thorianite ore from Amapa State, Brazil. This process comprises two major parts: acid leaching and Th/U recovery using solvent extraction strategies. Thorianite ore has a typical composition of 60 - 70% of thorium, 8 - 10% lead and 7 - 10% uranium. Sulfuric acid leaching operational conditions were defined as follows: acid/ore ratio 7.5 t/t, ore size below 65 mesh (Tyler), 2 hours leaching time and temperature of 100 deg C. Leaching tests results showed that uranium and thorium recovery exceeded 95%, whereas 97% of lead ore content remained in the solid form. Uranium and thorium simultaneous solvent extraction is necessary due to high sulfate concentration in the liquor obtained from leaching, so the Primene JM-T primary anime was used for this extraction step. Aqueous raffinate from extraction containing sulfuric acid was recycled to the leaching step, reducing acid uptake around 60%, to achieve a net sulfuric acid consumption of 3 t/t of ore. Uranium and thorium simultaneous stripping was performed using sodium carbonate solution. In the aqueous stripped it was added sulfuric acid at pH 1.5, followed by a second solvent extraction step using the tertiary amine Alamine 336. The following stripping step was done with a solution of sodium chloride, resulting in a final solution of 23 g L-1 uranium. (author)

  20. Thorium reserves - potential for power generation, exploration and mining

    International Nuclear Information System (INIS)

    The estimated resources as on 31-03-2015 of natural uranium in India is about 1,86,000 tons compared to more than 9,60,000 tons of thorium oxide deposit. India has the world's largest deposits of thorium. The three stage Atomic Energy Program adopted by India for harnessing the nuclear energy is based on utilization of the scarcely available uranium in the country along with abundant availability of thorium, so that plutonium generated from utilization of natural uranium in power reactors using heavy water as moderator can be successfully used to breed fissile materials from thorium in most efficient manner in breeder reactors which are also capable to producing energy. Utilization of vast resources of available thorium by the breeder route will be a potential source of nuclear power for sustaining the growing energy requirement of India in long term. Thanks to the problems of greenhouse gas emissions and the depleting limited hydro-carbon resources of the country, nuclear power is likely to play a significant role in the energy production sector. The subject matter of the talk focuses on prospects and challenges in developing the process technologies of various value added products from monazite and myriad of applications in the above mentioned industry sectors which are ever evolving with time

  1. Uranium, thorium and rare earth extraction and separation process by processing their chloride aqueous solutions

    International Nuclear Information System (INIS)

    The different steps of the process are the following: uranium and iron extraction by a neutral organic phosphorus compound and thorium and rare earth recovery in an aqueous solution, iron recovery in acid aqueous phase, concentration of the thorium and rare earth aqueous solution followed by thorium extraction with a organic phosphorus compound and rare earth recovery in the aqueous phase, thorium recovery in acid aqueous phase

  2. Up-gradation of technology for production of nuclear grade thorium oxide

    International Nuclear Information System (INIS)

    India with its large deposit of thorium and relatively modest deposit of uranium has drawn up its long term nuclear power generation programme based on utilisation of thorium. While the solvent extraction route presently being followed for processing of thorium is able to meet the ongoing demand for thorium for its utilisation in research programme reasonably well, the process needs to be further upgraded in view of more and more regulations on health and safety, operation and environmental impact

  3. Conceptual design of Indian molten salt breeder reactor

    Indian Academy of Sciences (India)

    P K Vijayan; A Basak; I V Dulera; K K Vaze; S Basu; R K Sinha

    2015-09-01

    The third stage of Indian nuclear power programme envisages the use of thorium as the fertile material with 233U, which would be obtained from the operation of Pu/Th-based fast reactors in the later part of the second stage. Thorium-based reactors have been designed in many configurations, from light water-cooled designs to high-temperature liquid metal-cooled options. Another option, which holds promise, is the molten salt-fuelled reactor, which can be configured to give significant breeding ratios. A crucial part for achieving reasonable breeding in such reactors is the need to reprocess the salt continuously, either online or in batch mode. India has recently started carrying out fundamental studies so as to arrive at a conceptual design of Indian molten salt breeder reactor (IMSBR). Presently, various design options and possibilities are being studied from the point of view of reactor physics and thermal hydraulic design. In parallel, fundamental studies on natural circulation and corrosion behaviour of various molten salts have also been initiated.

  4. Technology of thorium concentrates purification and their transformation in pure nuclear products

    International Nuclear Information System (INIS)

    An experimental study for the purification of thorium concentrates by solvent extraction is presented. The product of purification is appropriate for utilization in the fabrication of nuclear reactor fuel elements. The experiments are carried out in a laboratory scale and the following operations are studied: dissolution, extraction-scrubbing, stripping-scrubbing, thorium oxalate precipitation, and thorium nitrate coagulation

  5. Recommendations for bioassay monitoring methods for thorium

    International Nuclear Information System (INIS)

    Full text: Thorium is a naturally occurring radioactive element, which has a number of applications in industry. Handling of Th and its compounds could lead to radiation exposure of workers. Occupational incorporations of Th can be accurately monitored by analysis of Th excreted daily in urine. But interpretation of measured excretion values requires the knowledge of baseline levels for non-exposed subjects. Urinary Th excretion measurements have been performed on 14 non-exposed subjects of both genders. Age of the persons ranged from 25 to 79 years. Two highly sensitive analytical methods employing radiochemical neutron activation analysis (RNAA) and applying high resolution sector field ICP-MS (HR-SF-ICPMS) were developed, standardized and applied to measure pg levels of Th in urine samples from which the daily urinary excretion of Th was quantified. Using ICP-MS, median (mean) daily urinary Th excretion was obtained as 1.34 (1.84) ng. Similar median and mean excretion data in urine of 1.35 and 1.94 ng Th per day were found by RNAA. However, chemical procedures before sample irradiation should be performed with utmost care to avoid high chemical blank values. ICP-MS measurements compared to RNAA are easy, fast and cost-saving, and just predilution is needed for sample preparation. New improved ICP-MS techniques with detection limits of Th of 0.1 ng/ L in urine samples should become the routine technique for incorporation monitoring of workers and of the members of the general public. Recommendations concerning urine sampling, sample preparation and measurement technique are given. (author)

  6. Effect of the crystallinity on the leaching of thorium dioxide

    International Nuclear Information System (INIS)

    The effect of the precursor and temperature of calcination on the crystallinity and the dissolution of thorium dioxide has been studied. For a calcination temperature of 900 deg. C, the largest crystallite is obtained from the precipitation of thorium oxalate. The dissolution of crystallized ThO2 has been studied as a function of pH. High temperature crystallized ThO2 is less soluble by two order of magnitude than hydrous ThO2. We have pointed out a correlation between the crystallinity of the solid and its apparent leachability in acidic perchlorate solutions, resulting mainly in the thorium site concentration differences between solids. However, the normalized dissolution rate of crystallized ThO2 is independent on the way of synthesis of the solid. (authors)

  7. Performance of a 229Thorium solid-state nuclear clock

    International Nuclear Information System (INIS)

    The 7.8 eV nuclear isomer transition in 229thorium has been suggested as a clock transition in a new type of optical frequency standard. Here we discuss the construction of a ‘solid-state nuclear clock’ from thorium nuclei implanted into single crystals transparent in the vacuum ultraviolet range. We investigate crystal-induced line shifts and broadening effects for the specific system of calcium fluoride. At liquid nitrogen temperatures, the clock performance will be limited by decoherence due to magnetic coupling of the thorium nuclei to neighboring nuclear moments, ruling out the commonly used Rabi or Ramsey interrogation schemes. We propose clock stabilization based on a fluorescence spectroscopy method and present optimized operation parameters. Taking advantage of the large number of quantum oscillators under continuous interrogation, a fractional instability level of 10−19 might be reached within the solid-state approach. (paper)

  8. Feasibility and deployment strategy of water cooled thorium breeder reactor

    International Nuclear Information System (INIS)

    The author have studied water cooled thorium breeder reactor based on matured pressurized water reactor (PWR) plant technology for several years. Through these studies it is concluded that reduced moderated core by arranging fuel pins in a triangular tight lattice array with heavy water coolant in the primary loop by replacing original light water is appropriate for achieving sufficient breeding performance as sustainable fission system and high enough burn-up as an economical power plant. The heavy water cooled thorium reactor is feasible to be introduced by using Pu recovered from spent fuel of LWR, keeping continuity with current LWR infrastructure. This thorium reactor can be operated as sustainable energy supplier and also MA transmuter to realize future society with less long-lived nuclear waste

  9. Estimating terrestrial uranium and thorium by antineutrino flux measurements

    Science.gov (United States)

    Dye, Stephen T.; Guillian, Eugene H.

    2008-01-01

    Uranium and thorium within the Earth produce a major portion of terrestrial heat along with a measurable flux of electron antineutrinos. These elements are key components in geophysical and geochemical models. Their quantity and distribution drive the dynamics, define the thermal history, and are a consequence of the differentiation of the Earth. Knowledge of uranium and thorium concentrations in geological reservoirs relies largely on geochemical model calculations. This article describes the methods and criteria to experimentally determine average concentrations of uranium and thorium in the continental crust and in the mantle by using site-specific measurements of the terrestrial antineutrino flux. Optimal, model-independent determinations involve significant exposures of antineutrino detectors remote from nuclear reactors at both a midcontinental and a midoceanic site. This would require major, new antineutrino detection projects. The results of such projects could yield a greatly improved understanding of the deep interior of the Earth. PMID:18172211

  10. Gold, uranium and thorium in zones of greenschist displacement metamorphism

    International Nuclear Information System (INIS)

    Distribution of gold, uranium (bar and mobile) and thorium in 15 zones of greenschist dislocated metamorphism in different structures of the Karelo-Kola region carried out by geologic formations of the Early-Archean-Late-Proterozoic age has been studied. More than 200 samples of well core from 0-200 m depths have been analyzed. The results obtained testify to the increase of gold, uranium and less thorium content in zones of green-schist dislocated metamorphism in comparison with the enclosing rocks 1.4-3.1 times. The variation coefficient of gold, uranium and thorium content in green-schist dislocated tectonites increases 1.5-2.9 times. The correlation coefficient of Au/Umob. pair is +0.69, and Au/Ubar pair -+0.87. Essential correlation between concentrations of all three elements in enclosing rocks is absent

  11. Estimating terrestrial uranium and thorium by antineutrino flux measurements

    CERN Document Server

    Dye, Stephen T

    2008-01-01

    Uranium and thorium within the Earth produce a major portion of terrestrial heat along with a measurable flux of electron antineutrinos. These elements are key components in geophysical and geochemical models. Their quantity and distribution drive the dynamics, define the thermal history, and are a consequence of the differentiation of the Earth. Knowledge of uranium and thorium concentrations in geological reservoirs relies largely on geochemical model calculations. This research report describes the methods and criteria to experimentally determine average concentrations of uranium and thorium in the continental crust and in the mantle using site-specific measurements of the terrestrial antineutrino flux. Optimal, model-independent determinations involve significant exposures of antineutrino detectors remote from nuclear reactors at both a mid-continental and a mid-oceanic site. This would require major, new antineutrino detection projects. The results of such projects could yield a greatly improved understa...

  12. Host minerals for uranium and thorium in the Cape granite

    International Nuclear Information System (INIS)

    The uranium and thorium in Cape granite reside chiefly in trace minerals. The principle host minerals differ much from pluton to pluton. The large composite Khubus pluton in the Richterveld is composed of a central body of syenite surrounded by various types of granite. The granites are usually very low in dark minerals. According to autoradiographic results, the bulk of the uranium and thorium in the Khubus pluton is situated in the zircon, rather than in the sphene, apatite and fluorite. In many intrusives of the Cape granite suite most of the uranium is situated in a single host mineral such a zircon, xenotime, sphene or even uraninte. The most important thorium host mineral is monazite. The radio-element host mineral spectrum is unique for each different intrusive

  13. Thorium utilization in ACR (Advanced CANDU) and CANDU-6 reactors

    International Nuclear Information System (INIS)

    It is the main objective of this study to investigate fuel composition options for CANDU type of reactors that are capable of using a mixture of U-Th as fuel. A homogenous mixture of (U-Th)O2 was used in all elements of fuel bundles. The core of CANDU-6 and ACR (Advanced CANDU) were modeled using MCNP5. In equilibrium core, using MONTEBURNS2 code (coupled with MCNP5 and ORIGENS) for once-through uranium and once-through uranium-thorium fuel cycle of CANDU-6 and ACR, discharge burnups and spent fuel compositions were computed. For various enrichments of uranium and different fractions of thorium in a uranium-thorium fuel mixture, performing burnup calculations, relevant relations were derived; in addition, conversion ratio, fuel requirement, uranium resource utilization, and natural uranium savings were determined, and their changes with burnup were observed. Appropriate fuel compositions were discussed.

  14. Preparation of thorium oxide microspheres by internal gelation process

    International Nuclear Information System (INIS)

    Thorium oxide microspheres are used for the High Temperature Reactors (HTR) fuel element fabrication. One of the preparation methods is the internal gelation technique. This technique involves precipitation of hydrous thorium oxide via an hydrolytic process (internal gelation) by the dispersion of a stream of droplets of Th(NO3)4 . 4H2O solution containing an hydrolysable material. Urea is used for Th+4 complexation and hexamethylenetetramine (HMTA) for NH3 generation. The colloidal thorium is injected into a hot (95 + - 30C) oil column. The droplets are solidified as spheres by the action of in situ generated ammonia. The procedures for washing, drying, calcination and sintering of the microspheres are described as well as the physical and chemical characterization of the final product. (Author)

  15. Thermal decomposition of thorium and uranium(4) chloroacetates

    International Nuclear Information System (INIS)

    Using the complex of physico-chemical methods (derivatographic-combined TG-DTG-DTA investigation, IR-spectroscopy, X-ray phase analysis) in poly- and isothermal conditions, the process of thermal decomposition of uranium and thorium mono-, di- and trichloroacetates is studied. Stages and compositions of final and intermediate (solid and volatile) decomposition products are found. A total analogy in the behaviour of uranium and thorium chloroacetates under heating is found. Using the literary data, diagrams for thermolysis of the above compounds are suggested

  16. Canada's early research on nuclear energy from thorium

    International Nuclear Information System (INIS)

    Recently we have heard numerous presentations on the promise of molten-salt and other designs of nuclear reactors that can use thorium as a fuel. This chemical element can generate fission energy after it has been transformed by in-reactor irradiation into a synthetic isotope of uranium. It is well known that experiments. were done in the 1950s and 1960s in the USA and Canada, but interest in thorium as an energy source goes back considerably farther than that. In fact Canada was extracting that synthetic isotope, U-233, as early as 1944, before we even had an operating nuclear reactor! (author)

  17. Thorium fueled high temperature gas cooled reactors. An assessment

    International Nuclear Information System (INIS)

    The use of thorium as a fertile fuel for the High Temperature Gas Cooled Reactor (HTR) instead of uranium has been reviewed. It has been concluded that the use of thorium might be beneficial to reduce the actinide waste production. To achieve a real advancement, the uranium of the spent fuel has to be recycled and the requested make-up fissile material for the fresh fuel has to be used in the form of highly-enriched uranium. A self-sustaining fuel cycle may be possible in the HTR of large core size, but this could reduce the inherent safety features of the design. (orig.)

  18. Thorium determination in water and biological materials by fission track

    International Nuclear Information System (INIS)

    As a segment of a research programme on the study of bioaccumulation of radionuclides, in animals and vegetables from Morro do Ferro, Pocos de Caldas, MG, a fission track method for the determination of low levels of thorium in environmental samples was developed as an alternative for alpha spectroscopy. The study was carried out in early alpha spectroscopy samples, containing high levels of 228 Th activity, which makes difficult the 232 Th determination. A dry way method for thorium evaluation was developed. Pieces of membrane filters, containing La F3 (Th), coupled to Makrofol detectors, were irradiated in the core of a research reactor, IEA-R1 (IPEN). (author)

  19. PROCESS FOR DECONTAMINATING THORIUM AND URANIUM WITH RESPECT TO RUTHENIUM

    Science.gov (United States)

    Meservey, A.A.; Rainey, R.H.

    1959-10-20

    The control of ruthenium extraction in solvent-extraction processing of neutron-irradiated thorium is presented. Ruthenium is rendered organic-insoluble by the provision of sulfite or bisulfite ions in the aqueous feed solution. As a result the ruthenium remains in the aqueous phase along with other fission product and protactinium values, thorium and uranium values being extracted into the organic phase. This process is particularly applicable to the use of a nitrate-ion-deficient aqueous feed solution and to the use of tributyl phosphate as the organic extractant.

  20. Determination of thorium in human urine by neutron activation

    International Nuclear Information System (INIS)

    A routine procedure for the determination of thorium in urine of workers has been developed by the neutron activation method. The technique suggested by Dang, et. al. has been modified in order to reduce the cost involved and the sample processing time. The samples were irradiated in the MIT (Massachusetts Institute of Technology-Boston) reactor, in a thermal neutron flux of 8 x 10 12n.cm-2.s-1 for 3,5 hours. Thorium-232 was determined by counting 233Pa. (author) 6 refs.; 2 tabs

  1. Optimization of thorium oxalate precipitation conditions relative to thorium oxide sinterability

    International Nuclear Information System (INIS)

    The effect of thorium oxalate precipitation conditions on derived oxide sinterability was investigated with the objective of producing ThO2 powder that could be sintered to high density without premilling. Precipitation conditions examined were temperature, digestion time and agitation method which were employed in a two-level factorial experimental design to delineate their effects. The two levels for each of the factors, respectively, were 100C and 700C, 15 min and 360 min, and mechanical stirrer and a homogenizer that imparted both mechanical and ultrasonic agitation. The ThO2 derived from each of the precipitation trials was characterized with respect to morphology, surface area, and crystallite size as well as sinterability. Only precipitation temperature had a significant effect upon all the properties of the derived oxide powders

  2. Introduction of Thorium in the Nuclear Fuel Cycle. Short- to long-term considerations

    International Nuclear Information System (INIS)

    Since the beginning of the nuclear era, significant scientific attention has been given to thorium's potential as a nuclear fuel. Although the thorium fuel cycle has never been fully developed, the opportunities and challenges that might arise from the use of thorium in the nuclear fuel cycle are still being studied in many countries and in the context of diverse international programmes around the world. This report provides a scientific assessment of thorium's potential role in nuclear energy both in the short to longer term, addressing diverse options, potential drivers and current impediments to be considered if thorium fuel cycles are to be pursued. (authors)

  3. Analytical Characterization of the Thorium Nitrate Stockpile

    Energy Technology Data Exchange (ETDEWEB)

    Mattus, CH

    2003-12-30

    For several years, Oak Ridge National Laboratory (ORNL) has been supporting the Defense Logistics Agency-Defense National Stockpile Center with stewardship of a thorium nitrate (ThN) stockpile. The effort for fiscal year 2002 was to prepare a sampling and analysis plan and to use the activities developed in the plan to characterize the ThN stockpile. The sampling was performed in June and July 2002 by RWE NUKEM with oversight by ORNL personnel. The analysis was performed by Southwest Research Institute of San Antonio, Texas, and data validation was performed by NFT, Inc., of Oak Ridge, Tennessee. Of the {approx} 21,000 drums in the stockpile, 99 were sampled and 53 were analyzed for total metals composition, radiological constituents (using alpha and gamma spectrometry), and oxidizing characteristics. Each lot at the Curtis Bay Depot was sampled. Several of the samples were also analyzed for density. The average density of the domestic ThN was found to be 1.89 {+-} 0.08 g/cm{sup 3}. The oxidizer test was performed following procedures issued by the United Nations in 1999. Test results indicated that none of the samples tested was a Division 5.1 oxidizer per Department of Transportation definition. The samples were analyzed for total metals following the U.S. Environmental Protection Agency methods SW-846-6010B and 6020 (EPA 2003) using a combination of inductively coupled plasma--atomic emission spectroscopy and inductively coupled plasma--mass spectroscopy techniques. The results were used to compare the composition of the eight Resource Conservation and Recovery Act metals present in the sample (arsenic, barium, cadmium, chromium, lead, mercury, selenium, and silver) to regulatory limits. None of the samples was found to be hazardous for toxicity characteristics. The radiological analyses confirmed, when possible, the results obtained by the inductively coupled plasma analyses. These results--combined with the historical process knowledge acquired on the material

  4. Recovery of lead-208 radiogenic of residues of thorium with rare earth

    International Nuclear Information System (INIS)

    In the middle of the years 1970 in IPEN, considerable work for the purification and conversion of uranium and thorium project, the production of thorium nitrate, a pilot scale from different compounds of Thorium was accomplished; This installation of thorium nitrate produced for national marketing, given the industry of incandescent lighting gas mangles.. The method used by this installation was the purification by solvent extraction with pulsed columns. The thorium was in the organic phase, which was reversed as of thorium nitrate with a high degree of purity. The aqueous phase of this chemical process, containing impurities, some not extracted thorium and virtually all rare earths was precipitated in the form of a hydroxide. This was called RETOTER hydroxide (residue of Thorium and Rare Earth). This residue containing thorium, rare earth and some impurities such as lead-208 product of the decay of thorium-232 were stored in the shed of safeguarding IPEN for further recovery of thorium and rare earth. In this work was studied the recovery of lead-208, nuclear material of interest, separating it by the technique of cementation , where it adds zinc metallic to an acid solution of RETOTER, holding up the lead on the surface of the metallic zinc. (author)

  5. A review on the status of development in thorium-based nuclear fuels

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Young Woo; Na, S. H.; Lee, Y. W.; Kim, H. S.; Kim, S. H.; Joung, C.Y

    2000-02-01

    Thorium as an alternative nuclear energy source had been widely investigated in the 1950s-1960s because it is more abundant than uranium, but the studies of thorium nuclear fuel cycle were discontinued by political and economic reasons in the 1970s. Recently, however, renewed interest was vested in thorium-based nuclear fuel cycle because it may generate less long-lived minor actinides and has a lower radiotoxicity of high level wastes after reprocessing compared with the thorium fuel cycle. In this state-of the art report, thorium-based nuclear cycle. In this state-of the art report, thorium-based nuclear fuel cycle and fuel fabrication processes developed so far with different reactor types are reviewed and analyzed to establish basic technologies of thorium fuel fabrication which could meet our situation. (author)

  6. Design analysis of a thorium fueled reactor with seed-blanket assembly configuration

    International Nuclear Information System (INIS)

    Recently, thorium is receiving increasing attention as an important fertile material for the expanding nuclear power programs around the world. The superior nuclear and physical properties of thorium-based fuels could lead to very low fuel cycle cost and make thorium reactors economically attractive. In addition, the use of thorium in reactors would permit more efficient utilization of low cost uranium reserves and reduction of nuclear wastes. In this work, the nuclear characteristics of a new type of thorium fueled reactor (Radkowsky Thorium Reactor) consisting of seed-blanket assemblies are addressed and compared with those of typical assemblies of a PWR (CE type). Also, an assessment on several advantages of thorium fueled reactors is provided. All these results are based on the HELIOS code calculation

  7. A review on the status of development in thorium-based nuclear fuels

    International Nuclear Information System (INIS)

    Thorium as an alternative nuclear energy source had been widely investigated in the 1950s-1960s because it is more abundant than uranium, but the studies of thorium nuclear fuel cycle were discontinued by political and economic reasons in the 1970s. Recently, however, renewed interest was vested in thorium-based nuclear fuel cycle because it may generate less long-lived minor actinides and has a lower radiotoxicity of high level wastes after reprocessing compared with the thorium fuel cycle. In this state-of the art report, thorium-based nuclear cycle. In this state-of the art report, thorium-based nuclear fuel cycle and fuel fabrication processes developed so far with different reactor types are reviewed and analyzed to establish basic technologies of thorium fuel fabrication which could meet our situation. (author)

  8. Design and evaluation of a thorium (IV) selective optode

    Energy Technology Data Exchange (ETDEWEB)

    Safavi, Afsaneh [Department of Chemistry, Faculty of Sciences, Shiraz University, Shiraz 71454 (Iran, Islamic Republic of)]. E-mail: Afsaneh_safavi@yahoo.com; Sadeghi, Marzieh [Department of Chemistry, Faculty of Sciences, Shiraz University, Shiraz 71454 (Iran, Islamic Republic of)

    2006-05-17

    A novel optical sensor has been proposed for sensitive determination of thorium (IV) ion in aqueous solutions. The thorium sensing membrane was prepared by incorporating 4-(p-nitrophenyl azo)-pyrocatechol (NAP) as ionophore in the plasticized PVC membrane containing tributyl phosphate (TBP) as plasticizer. The membrane responds to thorium ion by changing color reversibly from yellow to red-brown in glycine buffer solution at pH 3.5. The proposed sensor displays a linear range of 8.66 x 10{sup -6}-2.00 x 10{sup -4} M with a limit of detection of 6 x 10{sup -6} M. The response time of the optode was about 8.8-12.5 min, depending on the concentration of Th (IV) ions. The selectivity of optode to Th (IV) ions in glycine buffer is good. The sensor can readily be regenerated by exposure to a solution mixture of sodium fluoride and 5-sulfosalicylic acid (dihydrate) (0.01 M each). The optode is fully reversible. The proposed optode was applied to the determination of thorium (IV) in environmental water samples.

  9. Decontamination of liquid radioactive waste by thorium phosphate

    International Nuclear Information System (INIS)

    In the field of the complete reexamination of the chemistry of thorium phosphate and of the improvement of the homogeneity of Thorium Phosphate Diphosphate (TPD, Th4(PO4)4P2O7) prepared at high temperature, several crystallized compounds were prepared as initial powdered precursors. Due to the very low solubility products associated to these phases, their use in the field of the efficient decontamination of high-level radioactive liquid waste containing actinides (An) was carefully considered. Two main processes (called 'oxalate' and 'hydrothermal' chemical routes) were developed through a new concept combining the decontamination of liquid waste and the immobilization of the actinides in a ceramic matrix (TPD). In phosphoric media ('hydrothermal route'), the key-precursor was the Thorium Phosphate Hydrogen Phosphate hydrate (Th2(PO4)2(HPO4). H2O, TPHP, solubility product log(KS,00) ∼ - 67). The replacement of thorium by other tetravalent actinides (U, Np, Pu) in the structure, leading to the preparation of Th2-x/2Anx/2(PO4)2(HPO4). H2O solid solutions, was examined. A second method was also considered in parallel to illustrate this concept using the more well-known precipitation of oxalate as the initial decontamination step. For this method, the final transformation to single phase TPD containing actinides was purchased by heating a mixture of phosphate ions with the oxalate precipitate at high temperature. (authors)

  10. Inconsistencies in the new ICRP model for thorium

    International Nuclear Information System (INIS)

    The biokinetic model for thorium, currently recommended by the ICRP, shows severe inconsistencies. Since this model forms the basis for calculations of dose coefficients and consequently for secondary derived limits, it is highly desirable to validate the model parameters, particularly the f1 value. Recent advances in the analytical techniques allow to do this with acceptable effort. (A.K.)

  11. Refining of thorium from monazite by solvent extraction

    International Nuclear Information System (INIS)

    The distribution of Th (IV) between aqueous H2SO4 solutions and organic phases of LA-2 has been described. The dependence of extraction on the aqueous acidity and the metal and extractant concentrations was investigated. The possible extraction mechanism is discussed on the basis of the results obtained. A flowsheet for production of high-grade thorium from monazite is suggested. (authors)

  12. Transmutation of minor actinide using thorium fueled BWR core

    International Nuclear Information System (INIS)

    One of the methods to conduct transmutation of minor actinide is the use of BWR with thorium fuel. Thorium fuel has a specific behaviour of producing a little secondary minor actinides. Transmutation of minor actinide is done by loading it in the BWR with thorium fuel through two methods, namely close recycle and accumulation recycle. The calculation of minor actinide composition produced, weigh of minor actinide transmuted, and percentage of reminder transmutation was carried SRAC. The calculations were done to equivalent cell modeling from one fuel rod of BWR. The results show that minor actinide transmutation is more effective using thorium fuel than uranium fuel, through both close recycle and accumulation recycle. Minor actinide transmutation weight show that the same value for those recycle for 5th recycle. And most of all minor actinide produced from 5 unit BWR uranium fuel can transmuted in the 6th of close recycle. And, the minimal value of excess reactivity of the core is 12,15 % Δk/k, that is possible value for core operation

  13. Pollution of agricultural crops with lanthanides, thorium and uranium studied

    Czech Academy of Sciences Publication Activity Database

    Kučera, Jan; Mizera, Jiří; Řanda, Zdeněk; Vávrová, M.

    2007-01-01

    Roč. 271, č. 3 (2007), s. 581-587. ISSN 0236-5731 Institutional research plan: CEZ:AV0Z10480505 Keywords : thorium, uranium * agricultural crops * neutron activation analysis Subject RIV: BE - Theoretical Physics Impact factor: 0.499, year: 2007

  14. Design study of long-life PWR using thorium cycle

    Science.gov (United States)

    Subkhi, Moh. Nurul; Su'ud, Zaki; Waris, Abdul

    2012-06-01

    Design study of long-life Pressurized Water Reactor (PWR) using thorium cycle has been performed. Thorium cycle in general has higher conversion ratio in the thermal spectrum domain than uranium cycle. Cell calculation, Burn-up and multigroup diffusion calculation was performed by PIJ-CITATION-SRAC code using libraries based on JENDL 3.2. The neutronic analysis result of infinite cell calculation shows that 231Pa better than 237Np as burnable poisons in thorium fuel system. Thorium oxide system with 8% 233U enrichment and 7.6˜ 8% 231Pa is the most suitable fuel for small-long life PWR core because it gives reactivity swing less than 1% Δk/k and longer burn up period (more than 20 year). By using this result, small long-life PWR core can be designed for long time operation with reduced excess reactivity as low as 0.53% Δk/k and reduced power peaking during its operation.

  15. Kinetics of thermal dehydration of zirconium and thorium hydroxide hydrogels

    International Nuclear Information System (INIS)

    Kinetics of thermal dehydration of synthetic zirconium and thorium hydroxide hydrogels have been studied by thermogravimetric method. Dehydration followed first order kinetics upto a certain stage. The rate constants for the initial and final stages of dehydration were related to the water content of the gels. Textural change on heat treatment also contributes to it. (author)

  16. Waste management aspects during the reprocessing of irradiated thorium rods

    International Nuclear Information System (INIS)

    Irradiated thorium rods were processed at RDL in two campaigns to recover the fissile material. The major steps involved in the process are rod charging, dissolution, solvent extraction and reconversion. The radioactive wastes that are generated from various stages of process, their management and disposal are discussed. (author)

  17. Alpha spectrometry and the secondary ion mass spectrometry of thorium

    International Nuclear Information System (INIS)

    The main objective of this master thesis was preparation of samples with thorium content on the steel discs by electrodeposition for determination of natural thorium isotope by alpha spectrometry and the secondary ion mass spectrometry and finding out their possible linear correlation between these methods. The samples with electrolytically excluded isotope of 232Th were prepared by electrodeposition from solution Th(NO3)4·12H2O on steel discs in electrodeposition cell with use of solutions Na2SO4, NaHSO4, KOH and (NH4)2(C2O4) by electric current 0.75 A. Discs were measured by alpha spectrometer. Activity was calculated from the registered impulses for 232Th and surface's weight. After alpha spectrometry measurements discs were analyzed by TOF-SIMS IV which is installed in the International Laser Centre in Bratislava. Intensities of isotope of 232Th and ions of ThO+, ThOH+, ThO2H+, Th2O4H+, ThO2-, ThO3H-, ThH3O3- and ThN2O5H- were identified. The linear correlation is between surface's weights of Th and intensities of ions of Th+ from SIMS, however the correlation coefficient has relatively low value. We found out with SIMS method that oxidized and hydride forms of thorium are significantly represented in samples with electroplated thorium. (authors)

  18. Decommissioning of the thorium high temperature reactor (THTR 300)

    International Nuclear Information System (INIS)

    The prototype Thorium-High-Temperature-Reactor (THTR 300) was decommissioned using the option of safe enclosure. Decision was made in 1989 and safe enclosure was reached in February 1997, followed by up to thirty years of operation of the safe enclosed plant. (author)

  19. Concentrations of uranium and thorium in bottled mineral waters

    International Nuclear Information System (INIS)

    Concentrations of uranium and thorium in commercial bottled mineral waters (81 domestic and 11 foreign products) have been analyzed using ICP-MS. Domestic bottled mineral waters exhibit very wide range of the uranium concentrations (0.1–3300 ng/L). However uranium concentrations of most samples were below 100 ng/L. There is no obvious correlation between the values of hardness and the uranium concentrations of the domestic bottled mineral waters. The uranium concentrations of foreign bottled mineral waters tended to be much higher than those of domestic ones (up to 4000 ng/L), and the values of hardness correlate roughly with the uranium concentration. It may be due to interactions between limestone and groundwater. Thorium concentrations of both domestic and foreign bottled mineral waters are typically less than 3.0 ng/L. Concentrations of uranium and thorium in bottled mineral waters were greatly lower than provisional guideline values defined by WHO. Therefore, it can be considered that there is no health risk chemically/radioactively induced by natural uranium and thorium in commercial mineral waters currently available in Japan, especially in Kyoto City. (author)

  20. Controlled synthesis of thorium and uranium oxide nano-crystals

    International Nuclear Information System (INIS)

    Very little is known about the size and shape effects on the properties of actinide compounds. As a consequence, the controlled synthesis of well-defined actinide-based nano-crystals constitutes a fundamental step before studying their corresponding properties. In this paper, we report on the non-aqueous surfactant-assisted synthesis of thorium and uranium oxide nano-crystals. The final characteristics of thorium and uranium oxide nano-crystals can be easily tuned by controlling a few experimental parameters such as the nature of the actinide precursor and the composition of the organic system (e.g., the chemical nature of the surfactants and their relative concentrations). Additionally, the influence of these parameters on the outcome of the synthesis is highly dependent on the nature of the actinide element (thorium versus uranium). By using optimised experimental conditions, monodisperse isotropic uranium oxide nano-crystals with different sizes (4.5 and 10.7 nm) as well as branched nano-crystals (overall size ca. 5 nm), nano-dots (ca. 4 nm) and nano-rods (with ultra-small diameters of 1 nm) of thorium oxide were synthesised. (authors)

  1. Helium on Venus - Implications for uranium and thorium

    Science.gov (United States)

    Prather, M. J.; Mcelroy, M. B.

    1983-01-01

    Helium is removed at an average rate of 10 to the 6th atoms per square centimeter per second from Venus's atmosphere by the solar wind following ionization above the plasmapause. The surface source of helium-4 on Venus is similar to that on earth, suggesting comparable abundances of crustal uranium and thorium.

  2. Helium on Venus: Implications for uranium and thorium

    OpenAIRE

    Prather, MJ; McElroy, MB

    1983-01-01

    Helium is removed at an average rate of 106 atoms per square centimeter per second from Venus's atmosphere by the solar wind following ionization above the plasmapause. The surface source of helium-4 on Venus is similar to that on Earth, suggesting comparable abundances of crustal uranium and thorium.

  3. Discovery of the actinium, thorium, protactinium, and uranium isotopes

    OpenAIRE

    Fry, C; Thoennessen, M

    2012-01-01

    Currently, 31 actinium, 31 thorium, 28 protactinium, and 23 uranium isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  4. Role of thorium in the industry advantage of atomic energy

    International Nuclear Information System (INIS)

    Based in the utilization of others fossil substances, such as plutonium and uranium 233, produzed through the thorium and natural uranium (238), it is discussed the relative merits of alternative processes: to produce U233 on Pu 239 to substitute the initial load of U235. (M.C.K.)

  5. 76 FR 42722 - Indian Gaming

    Science.gov (United States)

    2011-07-19

    ... Bureau of Indian Affairs Indian Gaming AGENCY: Bureau of Indian Affairs, Interior. ACTION: Notice of... FURTHER INFORMATION CONTACT: Paula L. Hart, Director, Office of Indian Gaming, Office of the Assistant... of the Indian Gaming Regulatory Act of 1988 (IGRA), Public Law 100-497, 25 U.S.C. 2710, the...

  6. 75 FR 61511 - Indian Gaming

    Science.gov (United States)

    2010-10-05

    ... Bureau of Indian Affairs Indian Gaming AGENCY: Bureau of Indian Affairs, Interior. ACTION: Notice of... CONTACT: Paula L. Hart, Director, Office of Indian Gaming, Office of the Deputy Assistant Secretary... section 11 of the Indian Gaming Regulatory Act of 1988 (IGRA), Public Law 100-497, 25 U.S.C. 2710,...

  7. 75 FR 38834 - Indian Gaming

    Science.gov (United States)

    2010-07-06

    ... Bureau of Indian Affairs Indian Gaming AGENCY: Bureau of Indian Affairs, Interior. ACTION: Notice of... INFORMATION CONTACT: Paula L. Hart, Director, Office of Indian Gaming, Office of the Deputy Assistant...: Under Section 11 of the Indian Gaming Regulatory Act of 1988 (IGRA), Public Law 100-497, 25 U.S.C....

  8. 76 FR 165 - Indian Gaming

    Science.gov (United States)

    2011-01-03

    ... Bureau of Indian Affairs Indian Gaming AGENCY: Bureau of Indian Affairs, Interior. ACTION: Notice of... the Menominee Indian Tribe of Wisconsin (``Tribe'') and the State of Wisconsin Gaming Compact of 1992... CONTACT: Paula L. Hart, Director, Office of Indian Gaming, Office of the Deputy Assistant...

  9. Introducing advanced thorium-based fuel cycles in SA : an evolutionary approach / Maria Hendrina (Marina) du Toit

    OpenAIRE

    Du Toit, Maria Hendrina

    2013-01-01

    Past experience in several thorium fuelled research- and power reactors provides the basis and history of thorium. The material properties, fertile- and fissile isotope properties as well as the decay chain of thorium are discussed for purposes of evaluating thorium as a source of fuel. The different thorium-based fuel designs for PWR cores are discussed and resulting difficulties and solutions are outlined. The different options for each strategy are compared in terms of ad...

  10. Uranium- and thorium-bearing pegmatites of the United States

    Energy Technology Data Exchange (ETDEWEB)

    Adams, J.W.; Arengi, J.T.; Parrish, I.S.

    1980-04-01

    This report is part of the National Uranium Resource Evaluation (NURE) Program designed to identify criteria favorable for the occurrence of the world's significant uranium deposits. This project deals specifically with uranium- and thorium-bearing pegmatites in the United States and, in particular, their distribution and origin. From an extensive literature survey and field examination of 44 pegmatite localities in the United States and Canada, the authors have compiled an index to about 300 uranium- and thorium-bearing pegmatites in the United States, maps giving location of these deposits, and an annotated bibliography to some of the most pertinent literature on the geology of pegmatites. Pegmatites form from late-state magma differentiates rich in volatile constituents with an attendant aqueous vapor phase. It is the presence of an aqueous phase which results in the development of the variable grain size which characterizes pegmatites. All pegmatites occur in areas of tectonic mobility involving crustal material usually along plate margins. Those pegmatites containing radioactive mineral species show, essentially, a similar distribution to those without radioactive minerals. Criteria such as tectonic setting, magma composition, host rock, and elemental indicators among others, all serve to help delineate areas more favorable for uranium- and thorium-bearing pegmatites. The most useful guide remains the radioactivity exhibited by uranium- and thorium-bearing pegmatites. Although pegmatites are frequently noted as favorable hosts for radioactive minerals, the general paucity and sporadic distribution of these minerals and inherent mining and milling difficulties negate the resource potential of pegmatites for uranium and thorium.

  11. Uranium- and thorium-bearing pegmatites of the United States

    International Nuclear Information System (INIS)

    This report is part of the National Uranium Resource Evaluation (NURE) Program designed to identify criteria favorable for the occurrence of the world's significant uranium deposits. This project deals specifically with uranium- and thorium-bearing pegmatites in the United States and, in particular, their distribution and origin. From an extensive literature survey and field examination of 44 pegmatite localities in the United States and Canada, the authors have compiled an index to about 300 uranium- and thorium-bearing pegmatites in the United States, maps giving location of these deposits, and an annotated bibliography to some of the most pertinent literature on the geology of pegmatites. Pegmatites form from late-state magma differentiates rich in volatile constituents with an attendant aqueous vapor phase. It is the presence of an aqueous phase which results in the development of the variable grain size which characterizes pegmatites. All pegmatites occur in areas of tectonic mobility involving crustal material usually along plate margins. Those pegmatites containing radioactive mineral species show, essentially, a similar distribution to those without radioactive minerals. Criteria such as tectonic setting, magma composition, host rock, and elemental indicators among others, all serve to help delineate areas more favorable for uranium- and thorium-bearing pegmatites. The most useful guide remains the radioactivity exhibited by uranium- and thorium-bearing pegmatites. Although pegmatites are frequently noted as favorable hosts for radioactive minerals, the general paucity and sporadic distribution of these minerals and inherent mining and milling difficulties negate the resource potential of pegmatites for uranium and thorium

  12. Indian concepts on sexuality

    OpenAIRE

    Chakraborty, Kaustav; Thakurata, Rajarshi Guha

    2013-01-01

    India is a vast country depicting wide social, cultural and sexual variations. Indian concept of sexuality has evolved over time and has been immensely influenced by various rulers and religions. Indian sexuality is manifested in our attire, behavior, recreation, literature, sculptures, scriptures, religion and sports. It has influenced the way we perceive our health, disease and device remedies for the same. In modern era, with rapid globalization the unique Indian sexuality is getting diffu...

  13. Report on intercomparisons S-14, S-15, and S-16 of the determination of uranium and thorium in thorium ores

    International Nuclear Information System (INIS)

    Twenty-nine laboratories from 18 countries took part in this intercomparison, organized by the IAEA's Analytical Quality Control Service, to help laboratories engaged in this task to check the reliability of their results. An additional aim was to establish the concentrations of thorium and uranium in three large batches of thorium ores and certifying them as reference materials. The evaluation was based on 438 individual results (108 laboratory means) for thorium, and on 412 individual results (106 laboratory means) for uranium. The number of laboratory means per element and per sample varied from 34 to 38. The methods most frequently used in the determination of both elements were neutron activation analysis and radiometry. They were followed by spectrophotometry and X-ray fluorescence analysis for thorium and by fluorimetry, X-ray fluorescence analysis and spectrophotometry for uranium determination, respectively. The relative uncertainty of all computed overall medians which were used as the best estimations of true values, does not exceed +-10% and +-5% for the concentration values below and above 0.1%, respectively

  14. Accuracy of thorium cross section of JENDL-4.0 library in thorium based fuel core evaluation

    International Nuclear Information System (INIS)

    Highlights: ► Critical experiments on Th core were conducted to verify the accuracy of Th232 cross section of JENDL-4.0 library. ► Calculations are found to overestimate effective multiplication factor about (0.90 ± 0.01–0.99 ± 0.01)%. ► Comparison between measured and calculated Th sample worth reassures Th232 capture underestimation of JENDL-4.0 library. ► Th capture cross section is needed to be adjusted at thermal energy range to provide more reliable evaluation. - Abstract: Considering the importance of thorium data and concerning about the accuracy of Th232 cross section library, a series of experiments on thorium critical core with different neutron spectra has been implemented at Kyoto University Critical Assembly (KUCA). Reactivity worth of control rod and thorium sample was measured after the cores experimentally achieved critical state. In order to verify the accuracy of thorium cross section library, calculations of effective multiplication factor, control rod worth, reactivity worth of Th plates for the same core configurations were done by MVP code (Nagaya et al., 2005) using JENDL-4.0 library (Shibata et al., 2011). From the comparison between the measured and calculated results, the calculations are found to overestimate effective multiplication factor about (0.90 ± 0.01–0.99 ± 0.01)%. By comparing the measured Th sample worth with the calculated one, Th capture underestimation is reassured. Sensitive study on reactivity worth evaluation was conducted and it suggests that Th capture cross section is needed to be adjusted at thermal energy range to provide more reliable evaluation for thorium based fuel core design and safety calculation

  15. Mechanism of thorium biosorption by the cells of the soil fungal isolate Geotrichum sp. dwc-1

    International Nuclear Information System (INIS)

    In order to understand the impact of microorganisms on the fate of thorium in soils, we investigated the thorium biosorption behavior and the corresponding mechanisms by the cells of Geotrichum sp. dwc-1, one of the dominant species of fungal group isolated from 3.5 m depth soil layer in Southwest China. It was observed that fast thorium adsorption onto cells of G. sp. dwc-1 could take place, with a high distribution coefficient Kd (0.93 mL/mg) obtained, when Geotrichum sp. dwc-1and thorium concentrations were 5 g/L and 10 mg/L, respectively. The thorium biosorption behavior was dependent on the pH value, and the lower pH could disrupt cell membrane of G. sp. dwc-1. At pH 1, thorium was accumulated in the cytoplasmic region of the cells. When pH was higher than 1, thorium was adsorbed on the cell surface of G. sp. dwc-1, like in periplasmic region or in the outer membrane. FTIR study combined with biosorption experiments further indicated that the thorium distribution and binding behavior on cell surface were associated with amino, hydroxyl groups and phosphate or sulphur functional groups, and might also be governed by electrostatic interaction. Moreover, PIXE and EPBS showed that ion-exchange mechanism contributed to the thorium biosorption process, in which the tetravalent thorium ions replaced smaller counter-ions (K+, Ca2+ and Fe3+) occuring on the cell surface. (orig.)

  16. Influence of plant activity and phosphates on thorium bioavailability in soils from Baotou area, Inner Mongolia

    Energy Technology Data Exchange (ETDEWEB)

    Guo Pengran [State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Science, 5625 Renmin Street, Changchun, Jilin 130022 (China); School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Jia Xiaoyu; Duan Taicheng; Xu Jingwei [State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Science, 5625 Renmin Street, Changchun, Jilin 130022 (China); Chen Hangting, E-mail: guopengran@gmail.co [State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Science, 5625 Renmin Street, Changchun, Jilin 130022 (China)

    2010-09-15

    Harm of thorium to living organisms is governed by its bioavailability. Thorium bioavailability in the soil-plant system of Baotou rare earth industrial area was studied using pot experiments of wheat and single extraction methods. The effects of wheat growth stage and phosphate on thorium bioavailability were also investigated. Based on extractabilities of various extraction methods (CaCl{sub 2}, NH{sub 4}NO{sub 3}, EDTA, HOAc) and correlation analysis of thorium uptake by wheat plant and extractable thorium, a mixture of 0.02 M EDTA + 0.5 M NH{sub 4}OAc (pH 4.6) was found suitable for evaluation of thorium bioavailability in Baotou soil, which could be predicted quantitatively by multiple regression models. Because of differences of wheat root activities, thorium bioavailability in rhizosphere soil was higher than in bulk soil at tillering stage, but the reverse occurred at jointing stage. Phosphate addition induced the mineralization of soluble thorium by forming stable thorium phosphate compounds, and reduced thorium bioavailability in soil.

  17. Influence of plant activity and phosphates on thorium bioavailability in soils from Baotou area, Inner Mongolia

    International Nuclear Information System (INIS)

    Harm of thorium to living organisms is governed by its bioavailability. Thorium bioavailability in the soil-plant system of Baotou rare earth industrial area was studied using pot experiments of wheat and single extraction methods. The effects of wheat growth stage and phosphate on thorium bioavailability were also investigated. Based on extractabilities of various extraction methods (CaCl2, NH4NO3, EDTA, HOAc) and correlation analysis of thorium uptake by wheat plant and extractable thorium, a mixture of 0.02 M EDTA + 0.5 M NH4OAc (pH 4.6) was found suitable for evaluation of thorium bioavailability in Baotou soil, which could be predicted quantitatively by multiple regression models. Because of differences of wheat root activities, thorium bioavailability in rhizosphere soil was higher than in bulk soil at tillering stage, but the reverse occurred at jointing stage. Phosphate addition induced the mineralization of soluble thorium by forming stable thorium phosphate compounds, and reduced thorium bioavailability in soil.

  18. Current research activity in the measurement of thorium and the identification of future research needs

    International Nuclear Information System (INIS)

    A pre-requisite in the setting and enforcement of regulatory limits for exposure to thorium in the workplace is that thorium and its progeny can be accurately measured. Literature surveys have shown that the majority of thorium measurements were performed using either a radiochemical technique, such as alpha or gamma spectroscopy, or ICP-MS. For many methods, there was a separation step to isolate and pre-concentrate thorium from the sample matrix. Thorium was most commonly measured in geological matrices and industrial materials. A survey of current research activity was performed through distribution of a questionnaire to laboratories and national centres. From the responses, four areas of current activity were identified: (i) development of methods for low level thorium determination, (ii) biological monitoring and metabolism of thorium, (iii) environmental monitoring for thorium, and (iv) health risks from X ray contract media. Two key areas for priority research were identified by the thorium Thematic Network: namely sample preparation methods and for traceable standards and reference materials for thorium analysis. (author)

  19. The Tarascan Indian House.

    Science.gov (United States)

    Quinn, Joyce

    1989-01-01

    This lesson plan introduces K-grade three students to Mexican Indian architecture. Students will become familiar with the cultural context of the Indian treasure house; discuss the use of wood as the sole building material; compare the treasure house with present day structures; and create miniature treasure houses using wood materials. (GEA)

  20. Pima Indian Legends.

    Science.gov (United States)

    Shaw, Anna Moore

    The stated purpose of this book is to preserve in writing some of the Pima Indian legends that had been verbally passed from generation to generation in the past. This collection of 23 legends, which were originally used to instruct the young people of the tribe, presents in story form various aspects of American Indian life--including…

  1. Indian Ocean Rim Cooperation

    DEFF Research Database (Denmark)

    Wippel, Steffen

    Since the mid-1990s, the Indian Ocean has been experiencing increasing economic cooperation among its rim states. Middle Eastern countries, too, participate in the work of the Indian Ocean Rim Association, which received new impetus in the course of the current decade. Notably Oman is a very active...

  2. Indian Inuit Pottery '73

    Science.gov (United States)

    Tawow, 1974

    1974-01-01

    A unique exhibit of Canadian Native Ceramics which began touring various art galleries in September 1973 is described both verbally and photographically. The Indian Inuit Pottery '73 display, part of the 1973 International Ceramics Exhibition, includes 110 samples of craftsmanship from Indian and Inuit artists across Canada. (KM)

  3. America's Indian Statues.

    Science.gov (United States)

    Gridley, Marion E., Comp.

    A comprehensive compilation of facts and photographs of statues honoring or memorializing the American Indians is presented in this paperback. The vignettes accompanying the photographs are the result of extensive research. Examples of the American Indian statues include "The Signal of Peace,""The Protest,"" The Medicine Man,""Appeal to the Great…

  4. A Commercial Thorium-based Fuel for LWRs

    International Nuclear Information System (INIS)

    Thorium-based fuels offer great potential to address large-scale energy needs with improved sustainability. Thorium oxide exhibits numerous advantageous features as a fuel form: in itself it produces practically no long-lived actinides, it lends high proliferation-resistance and it has excellent material properties that contribute to high safety and waste management credentials. A new thorium-based fuel is being developed by the Norwegian company Thor Energy, and this will target the commercial Light-Water Reactor (LWR) market. The ceramic oxide fuel will incorporate recovered LWR plutonium - homogeneously distributed in a fertile thorium oxide matrix. The fuel material is denoted TOP for Thorium Og Plutonium, og being the Norwegian word for 'and'. Thor Energy is working within a staged approach for deploying thorium fuels - a first phase will build on today's MOX fuel infrastructure, a second phase will see industrialization of technologies for extracting bred-in U-233 and reusing this in current-generation reactors, a third phase will see thorium fuels designed for breeding in advanced LWRs, and subsequent recycle of bred-in U-233. This phased introduction of thorium fuel fits in well before the entry-into-service of significant numbers of Gen IV (fast spectrum) reactors. Thorium fuel options can in fact serve to 'hedge ones' bets' for providing more sustainable nuclear energy before this point. Thor Energy has started detailed planning for an experimental campaign comprising pellet fabrication trials and a test irradiation in the Halden research reactor, in which the performance of (Th,Pu)O2 fuel pellets will be investigated in conditions valid for licensing in LWRs. In parallel with this, fuel assembly designs are being generated for existing and new BWRs. Pin size and other lattice geometry parameters are being optimised against neutronic parameters and the efficient utilisation of plutonium. Thermal-hydraulic compatibility with existing BWR fuel assemblies

  5. Thorium content of a mineral ore from Morro do Ferro by fission track technique

    International Nuclear Information System (INIS)

    The feasibility to determine thorium concentrations by fission track technique in samples of mineral ore has been demonstrated. The literature registers only the application of the fission track technique to mineral ore in the case where the fissionable element is uranium. The technique was applied to determine the thorium concentration of an ore sample from Morro do Ferro, taking advantage of the high thorium to uranium ratio in that mineral. The sample analysed presented a thorium concentration of 2467 +- 400 mg Th/Kg ore. The so called wet method was adopted by using the Bayer made Makrofol KG 10μm thick, as the detector foil, immersed in the thorium solution. The technique is also useful to determine thorium concentrations in environmental samples because of the following aspects: high sensitivity; fast chemical separation of interfering elements; low cost; and operational simplicity. (Author)

  6. Analysis of integral experiment for thorium fuel cycle at Kyoto University Critical Assembly

    International Nuclear Information System (INIS)

    To measure integral neutronics characteristics of thorium loaded core, critical experiments had been carried out at Kyoto University Critical Assembly (KUCA). The critical experiments were performed with various neutron spectra and thorium inventories. The thorium loaded core has two regions which are a test zone and a driver fuel zone. The test zone consists of thorium plates and graphite plates. In order to change the neutron spectrum of the experimental neutron field systematically, the graphite/Th-232 ratio at the test zone had been systematically varied by changing the combination of the thorium plates and the graphite plates in a unit cell. In this study, the criticalities of thorium loaded core were analyzed by MVP2.0 with JENDL-4.0, JENDL-3.3. In addition, sensitivity analyses were performed by SAGEP code and uncertainties of the numerical results were evaluated by using cross section covariance matrix. (author)

  7. Thorium removal from aqueous solutions of Mexican erionite and X zeolite

    International Nuclear Information System (INIS)

    Thorium(IV) removal from aqueous solutions by erionite and X zeolite was investigated. The Th(IV) uptake at different thorium nitrate concentrations (from 0.25 to 25 mM) was evaluated. The thorium content in the aqueous solution was determined by neutron activation analysis. Th(IV) retained by zeolites was 1.7 and 3.7 meq/g for erionite and X zeolite. In order to explain the thorium sorption process in both zeolites, ion exchange mechanism was considered. It was found that thorium sorption behavior is strongly dependent of the type of zeolite, the separation factor for Mexican erionite was αTh(IV)Na(I) Th(IV)Na(I) ∼1, this value suggested an approximately ideal ion exchange behavior. The effect of pH on thorium sorption was also considered. (author)

  8. Biosorption of uranium and thorium by agro based biomass

    International Nuclear Information System (INIS)

    The use of low cost sorbent was investigated by evaluating the potential of three different agro based biomass designated biomass 1,11,111 respectively for the biosorption of uranium and thorium. Equilibrium and rate relationship were determined. The initial pH of the metal ion solution effected metal uptake capacity of the biomass and indicated a higher uptake of uranium in relation to thorium. Equilibrium, adsorption capacities was thus determined only for uranium and biomass III showed the highest uptake capacity. Biosorption of uranium was also studied in a packed bed continuous flow column. Metal bound could be eluted with O.2M NaHCO3. Reusability of the column was demonstrated over three cycles indicating the biosorption process for uranium removal is reversible without significant loss of binding efficiency. (author)

  9. Production and fabrication of thorium fuels at BARC

    International Nuclear Information System (INIS)

    Thorium oxide can be consolidated by conventional powder metallurgy technique of compaction and sintering. Thorium oxide is a difficult material to sinter and even at a sintering temperature of 2000degC, the density achievable is not > 80% T.D. Hence, activated sintering with the use of additives is resorted to for achieving densities > 90% T.D. Sinterability of thoria powders obtained from different compounds such as hydroxide, hydrocarbonate, tannate, oxalate etc. has been thoroughly investigated. The effect of different additives such as CaO, CaF2, MgO, Nb2O5 on the sinterability of thoria has been extensively studied. With the addition of 0.25% Nb2O5, sintering temperature can be brought down to as low as 1150deg-1200degC. High density thoria pellets have been fabricated for use in CIRUS, DHRUVA, FBTR, PHWRs and Experimental Fission/Fusion Hybrid Systems. (author). 6 refs., 8 figs

  10. First-principles study of point defects in thorium carbide

    Energy Technology Data Exchange (ETDEWEB)

    Pérez Daroca, D., E-mail: pdaroca@tandar.cnea.gov.ar [Gerencia de Investigación y Aplicaciones, Comisión Nacional de Energía Atómica, Av. General Paz 1499, (1650) San Martin, Buenos Aires (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas, (1033) Buenos Aires (Argentina); Jaroszewicz, S. [Gerencia de Investigación y Aplicaciones, Comisión Nacional de Energía Atómica, Av. General Paz 1499, (1650) San Martin, Buenos Aires (Argentina); Instituto de Tecnología Jorge A. Sabato, UNSAM-CNEA, Av. General Paz 1499, (1650) San Martin, Buenos Aires (Argentina); Llois, A.M. [Gerencia de Investigación y Aplicaciones, Comisión Nacional de Energía Atómica, Av. General Paz 1499, (1650) San Martin, Buenos Aires (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas, (1033) Buenos Aires (Argentina); Mosca, H.O. [Gerencia de Investigación y Aplicaciones, Comisión Nacional de Energía Atómica, Av. General Paz 1499, (1650) San Martin, Buenos Aires (Argentina); Instituto de Tecnología Jorge A. Sabato, UNSAM-CNEA, Av. General Paz 1499, (1650) San Martin, Buenos Aires (Argentina)

    2014-11-15

    Thorium-based materials are currently being investigated in relation with their potential utilization in Generation-IV reactors as nuclear fuels. One of the most important issues to be studied is their behavior under irradiation. A first approach to this goal is the study of point defects. By means of first-principles calculations within the framework of density functional theory, we study the stability and formation energies of vacancies, interstitials and Frenkel pairs in thorium carbide. We find that C isolated vacancies are the most likely defects, while C interstitials are energetically favored as compared to Th ones. These kind of results for ThC, to the best authors’ knowledge, have not been obtained previously, neither experimentally, nor theoretically. For this reason, we compare with results on other compounds with the same NaCl-type structure.

  11. attenuation of reactor neutrons by uranium and thorium dioxides

    International Nuclear Information System (INIS)

    A formula is given which allows to calculate the total thermal cross-section of a crystalline uranium and thorium dioxide as function of crystal constants temperature and neutron wavelength. A computer codes PUO and SUO were developed to calculate the total attenuation of reactor neutrons through poly and mono-crystalline respectively. The calculated values of the neutrons cross-section of ploy crystalline uranium and thorium dioxide were compared with the available experimental ones in the energy range from 4 MeV to eV. The obtained agreement shows that the deduced formula fits the experimental data within accuracy less than 10%. A feasibility study on using depleted polycrystalline uranium dioxide as a cold neutron filter and the single crystal as a thermal one is given. The optimum crystal parameters and thickness for efficiently transmitting the thermal reactor neutrons while strongly attenuating both fast neutrons and γ-rays accompanying the thermal ones is also given

  12. First-principles study of point defects in thorium carbide

    Science.gov (United States)

    Pérez Daroca, D.; Jaroszewicz, S.; Llois, A. M.; Mosca, H. O.

    2014-11-01

    Thorium-based materials are currently being investigated in relation with their potential utilization in Generation-IV reactors as nuclear fuels. One of the most important issues to be studied is their behavior under irradiation. A first approach to this goal is the study of point defects. By means of first-principles calculations within the framework of density functional theory, we study the stability and formation energies of vacancies, interstitials and Frenkel pairs in thorium carbide. We find that C isolated vacancies are the most likely defects, while C interstitials are energetically favored as compared to Th ones. These kind of results for ThC, to the best authors' knowledge, have not been obtained previously, neither experimentally, nor theoretically. For this reason, we compare with results on other compounds with the same NaCl-type structure.

  13. Thorium and plutonium utilisation in pebble-bed modular reactor

    International Nuclear Information System (INIS)

    Thorium and plutonium utilisation in a high temperature gas-cooled pebble-bed reactor is investigated with the aim to predict the economic value of vast thorium reserves in Turkey. A pebble-bed reactor of the type designed by PBMR Pty. of South Africa is taken as the investigated system. The equilibrium core of a PBMR is considered and neutronics analyses of such a core are performed through the use of the SCALE-4.4 computer code system KENOV.a module. Various cross-section libraries are used to calculate the criticality of the core. Burn-up calculations of the core are performed by coupling the KENOV.a module with the ORIGEN-S module. Calculations are carried out for various U-Th, U-Pu-Th and U-Pu combinations. The results are preliminary in nature and the work is currently proceeding as planned. (author)

  14. Physical speciation of thorium in aquatic subsurface environment

    International Nuclear Information System (INIS)

    During this work laboratory simulated experiments were conducted to study the physical speciation of thorium by using ultrafiltration technique. Thorium has only one stable oxidation state i.e. IV, under all redox conditions in natural waters and therefore, its speciation is dominated by its interaction with various fraction of aquatic humic substances(AHS). Samples of water were collected from oligotropic environment having DOC in the range of 60 - 70 ppm. Th(IV) ions are extremely particle reactive having Kd value of the order of 106, hence to avoid adsorption on suspended particulate matter, spiking of the solution with Th(NO3)4 was carried out in ground water samples after filtering through 0.22 μm pore size using suction filtration. Experimental results show that 70% of the spiked Th is in association with low molecular weight colloids i.e 500 NMWL followed by < 500 NMWL. (author)

  15. First-principles study of point defects in thorium carbide

    International Nuclear Information System (INIS)

    Thorium-based materials are currently being investigated in relation with their potential utilization in Generation-IV reactors as nuclear fuels. One of the most important issues to be studied is their behavior under irradiation. A first approach to this goal is the study of point defects. By means of first-principles calculations within the framework of density functional theory, we study the stability and formation energies of vacancies, interstitials and Frenkel pairs in thorium carbide. We find that C isolated vacancies are the most likely defects, while C interstitials are energetically favored as compared to Th ones. These kind of results for ThC, to the best authors’ knowledge, have not been obtained previously, neither experimentally, nor theoretically. For this reason, we compare with results on other compounds with the same NaCl-type structure

  16. Determination of dose equivalent and risk in thorium cycle

    International Nuclear Information System (INIS)

    In these report are presented the calculations of dose equivalent and risk, utilizing the dosimetric model described in publication 30 of the International Comission on Radiological Protection. This information was obtained by the workers of the thorium cycle, employed at the Praia and Santo Amaro Facilities, by assessing the quantity and concentration of thorium in the air. The samples and the number of measurements were established through design of experiments techniques, and the results were evaluated with the aid of variance analysis. The estimater of dose equivalent for internal and external radiation exposure and risk associated were compared with the maximum recommended limits. The results indicate the existence of operation areas whose values were above those limits, requiring so an improvement in the procedures and services in order to meet the requirements of the radiological protetion. (author)

  17. Investigation of CANDU reactors as a thorium burner

    International Nuclear Information System (INIS)

    Large quantities of plutonium have been accumulated in the nuclear waste of civilian LWRs and CANDU reactors. Reactor grade plutonium can be used as a booster fissile fuel material in the form of mixed ThO2/PuO2 fuel in a CANDU fuel bundle in order to assure reactor criticality. The paper investigates the prospects of exploiting the rich world thorium reserves in CANDU reactors. Two different fuel compositions have been selected for investigations: (1) 96% thoria (ThO2) + 4% PuO2 and (2) 91% ThO2 + 5% UO2 + 4% PuO2. The latter is used for the purpose of denaturing the new 233U fuel with 238U. The behavior of the reactor criticality k ∞ and the burn-up values of the reactor have been pursued by full power operation for >∼8 years. The reactor starts with k ∞ = ∼1.39 and decreases asymptotically to values of k ∞ > 1.06, which is still tolerable and useable in a CANDU reactor. The reactor criticality k ∞ remains nearly constant between the 4th year and the 7th year of plant operation, and then, a slight increase is observed thereafter, along with a continuous depletion of the thorium fuel. After the 2nd year, the CANDU reactor begins to operate practically as a thorium burner. Very high burn-up can be achieved with the same fuel (>160,000 MW D/MT). The reactor criticality would be sufficient until a great fraction of the thorium fuel is burned up, provided that the fuel rods could be fabricated to withstand such high burn-up levels. Fuel fabrication costs and nuclear waste mass for final disposal per unit energy could be reduced drastically

  18. Preparation of Ceramic-Grade Thorium-Uranium Oxide

    International Nuclear Information System (INIS)

    A method for the preparation of sintered bodies of thorium-uranium mixed oxide starting from a solution of thorium nitrate and uranyl nitrate was investigated. This method can be useful both in the fabrication of fuel elements and in the reprocessing of such type of materials. In the first step of the method, uranyl nitrate is reduced to uranium (IV) nitrate. As reducing agent, both gaseous hydrogen and formic acid are employed; urea is added to prevent the formation of nitrous acid, which catalyses the reoxidation of uranium (IV). As catalyst, both platinum and palladium can be employed. Data are given for a continuous process, in which formic acid and urea are added to the solution, which is then pre-heated and passed in a column packed with 1/8 in x 1/8 in alumina pellets, carrying 0.5 wt.% of platinum. The influence of flow rate, temperature, formic acid and urea concentration, as well as catalyst life and poisoning are studied. The second step in the method is the precipitation of an oxalate of thorium and uranium (IV). The influence of oxalic acid to thorium-uranium ratio, temperature, aging time on settling and filtering characteristics of the precipitate and on the ceramic properties of the obtained powders is reported. Firing was carried out both in reducing and oxidizing atmosphere. After preliminary tests, two standard procedures were set up for the fabrication of ceramic bodies, namely by cold pressing and sintering and by extrusion and sintering. The ability of the different powders to sinter was tested by both of the two standard methods. With some of the powders, densities higher than 95% of theoretical density were obtained; reproducibility tests were successfully carried out. (author)

  19. Recent advances in thorium fuel cycles for CANDU reactors

    International Nuclear Information System (INIS)

    The once-through thorium fuel cycle in CANDU reactors provides an evolutionary approach to exploiting the energy potential of thorium. In the 'mixed bundle' strategy, the central 8 elements in a CANFLEX fuel bundle contain thoria, while the outermost 35 elements contain slightly enriched uranium (SEU). Detailed full-core fuel-management simulations have shown that this approach can be successfully implemented in existing CANDU reactors. Uranium requirements are lower than for the natural uranium fuel cycle. Further energy can be derived from the thorium by recycling the irradiated thoria fuel elements, containing 233U, as-is without any processing, into the center of a new mixed bundle. There are several examples of such 'demountable' bundles. Recycle of the central 8 thoria elements results in an additional burnup of 20 MW·d/kgHE from the thoria elements, for each recycle. The reactivity of these thoria elements remains remarkably constant over irradiation for each recycle. The natural uranium requirements for the mixed bundle (which includes the natural uranium feed required for the outer SEU fuel elements), without recycle, is about 10% lower than for the natural uranium fuel cycle. After the first recycle, the uranium requirements are -35% lower than for the natural uranium cycle, and remain fairly constant with further recycling (the total uranium requirement averaged over a number of cycles is 30% lower than a natural uranium fuelled CANDU reactor). This thorium cycle strategy is a cost-effective means of reducing uranium requirements, while producing a stockpile of valuable 233U, safeguarded in the spent fuel, that can be recovered in the future when predicated by economic or resource considerations. (author)

  20. Preliminary economic evaluation of thorium based fuels in PWRs

    OpenAIRE

    Du Toit, M.H.; Cilliers, A.C.

    2014-01-01

    Many studies have proven that thorium-based fuel cycles are more expensive than current uranium fuel cycles, which is confirmed in this paper as well. This research, however, goes beyond the conventional nuclear plant refueling cycle, aiming to optimize the refueling cycle in line with specific advantages realized from the thoriumbased refueling cycle. These benefits are the good thermal neutronic characteristics of fertile 232Th and fissile 233U, resulting in longer r...

  1. Treatment of uranium-thorium fuel at its production stage

    International Nuclear Information System (INIS)

    The possibility of removing 232U at the stage of obtaining 233U for the convenience of processing and reducing radiation dose has been analyzed in the paper. This problem is solved by the technology of obtaining 233U in extracted neutron beams in cold channels of a reactor. This technology will allow the acceleration of the implementation of the uranium-thorium fuel cycle in the current reactor technologies

  2. Composition of hydroponic medium affects thorium uptake by tobacco plants

    Czech Academy of Sciences Publication Activity Database

    Soudek, Petr; Kufner, Daniel; Petrová, Šárka; Mihaljevič, M.; Vaněk, Tomáš

    2013-01-01

    Roč. 92, č. 9 (2013), s. 1090-1098. ISSN 0045-6535 R&D Projects: GA MŠk LH12162; GA MŠk(CZ) LD13029; GA MPO FR-TI3/778 Institutional research plan: CEZ:AV0Z50380511 Keywords : Thorium * Plant uptake * Polyamines Subject RIV: DN - Health Impact of the Environment Quality Impact factor: 3.499, year: 2013

  3. Spectrophotometric determination of thorium using arsenazo III in water

    International Nuclear Information System (INIS)

    A spectrophotometric determination of thorium with arsenazo III (1,8 dihidroxynaphtaline - 3,6 sulfanic acid - 2,7 bis (azo-2) - phenil argonic acid) was carried out aiming to analyse this element in water. In order to eliminate possible interferences, a coprecipitation with lantanium fluoride was used followed by an extration with 0,2 M TTA (tenoil-trifluor - aceton) / Benzen. The results showed a good agreement with the ones obtained by alfa-spectrometry. (Author)

  4. Phonon spectrum, mechanical and thermophysical properties of thorium carbide

    International Nuclear Information System (INIS)

    In this work, we study, by means of density functional perturbation theory and the pseudopotential method, mechanical and thermophysical properties of thorium carbide. These properties are derived from the lattice dynamics in the quasi-harmonic approximation. The phonon spectrum of ThC presented in this article, to the best authors’ knowledge, have not been studied, neither experimentally, nor theoretically. We compare mechanical properties, volume thermal expansion and molar specific capacities with previous results and find a very good agreement

  5. The Spondylarthritis Ankylopoietica and its treatment with thorium X

    International Nuclear Information System (INIS)

    After a detailed and comprehensive survey over the history of the spondylarthritis ankylopoietica or 'Bechterew's disease' and over the thorium X therapy, own experiences with patients are described. The patients received a Th-X therapy, supplemented by prednison phenylbutazone administration, with a total dose of up to 1000 to 2400 e.s. E. Th X. In addition, an intensive physicobalneologic and physiotherapeutic treatment was carried out. More than two thirds of the patients expressed their satisfaction with the results achieved. (DG)

  6. Utilization of Arsenazo-III for spectrophotometric determination of thorium in soil samples

    International Nuclear Information System (INIS)

    The paper discusses the application of Arsenazo-III for thorium estimation in soil samples. The basic parameter as stability of complex, linear working range, method detection limit and conditioning for complex formation are discussed. Quality assurance parameter for thorium estimation in soil samples using this reagent is also discussed. The result demonstrates the utilization of Arsenazo-III for the accurate and reliable estimation of thorium in soil samples. (author)

  7. Understanding response of thorium under high temperatures and high pressures using ab-initio calculations

    International Nuclear Information System (INIS)

    The knowledge of high-temperature and high-pressure properties of thorium are important for designing advanced nuclear power systems for utilization of thorium. Employing the first principles method, we have determined the thermal expansivity, thermal vibrations and room pressure melting of thorium, and also determined its response to the high strain rate shock compression and various elastic moduli in the compressed states. (author)

  8. Studies on supercritical fluid extraction behaviour of uranium and thorium nitrates using amides

    International Nuclear Information System (INIS)

    Supercritical fluid extraction studies of uranyl nitrate and thorium nitrate in mixture were carried out using various amides such as N,N-di(2-ethylhexyl) isobutyramide (D2EHIBA),N,N-dihexyl octanamide (DHOA) and Diisooctyl Butanamide (DiOBA). These studies established a preferential extraction of uranium over thorium. Among the various amides studied, D2EHIBA offered the best rate of preferential extraction of uranium over thorium. (author)

  9. ISOLATION OF URANIUM(VI) AND THORIUM(IV) FROM AQUEOUS SOLUTIONS BY INORGANIC SORBENTS

    OpenAIRE

    Menchuk, V. V.; Perlova, N. A.

    2016-01-01

    Efficiency of use of a new sorbent on the basis of a silica gel at uranium and thorium isolation from their diluted aqueous solutions was investigated. It is shown that the investigated sorbent sorbs uranium and thorium better than a known sorbent (the silica gel). Influence of phases contact time, pH, the metal nature and solution ionic composition on the efficiency of uranium and thorium sorption process was studied. Experimentally received isotherms sorption are described by means of Langm...

  10. Sustainability Indicators for Open-Cycle Thorium-Fuelled Nuclear Energy

    OpenAIRE

    Ashley, S. F.; Fenner, R. A.; Nuttall, W. J.; Parks, Geoffrey T.

    2012-01-01

    The potential for countries which currently have a nominal nuclear energy infrastructure to adopt thorium-uranium-fuelled nuclear energy systems, using a once-through ?open? nuclear fuel cycle, has been presented by the International Atomic Energy Agency. This paper highlights Generation III and III+ nuclear energy technologies that could potentially adopt an open thorium-uranium fuel cycle and qualitatively highlights the main differences between the open thorium-uranium and open uranium fue...

  11. 3.4. Research and Development of Thorium in Nuclear Fuel -European Commission

    OpenAIRE

    Tsige-Tamirat, Haileyesus

    2012-01-01

    Thorium fuel cycles (ThFCs) have been investigated with varying intensity for many different reactor types in the past.This was motivated by the vast abundance of thorium and its ability to be used as a fertile material in most reactor types. Thorium oxide fuel possesses favorable neutronic, thermal and chemical properties that could enable higher fuel utilization, lower minor actinide production, and improved proliferation resistance. Past studies in the European Union indicated that Th...

  12. Determination of uranium in thorium matrix- a novel approach to quality control in nuclear fuel cycle

    International Nuclear Information System (INIS)

    In view of potential role of thorium in the future nuclear programme, research and development work in various aspects of thorium fuel cycle has been undertaken. Besides, the recent interest in thorium utilisation in Pressurised Heavy Water Reactors (PHWRs) necessitates monitoring of its purity with respect to a number of metallics which are of significance to its performance. Prominent among these metals and equally difficult to determine at trace level is uranium

  13. Final purification of 233U from thorium by Dowex 50x4 in Thorex process

    International Nuclear Information System (INIS)

    The 233U product obtained after a single cycle 5% tributyl phosphate/shell sol T extraction, scrubbing and stripping often contains significant amount of thorium as impurity. Further purification is normally carried out using ion exchange. The present paper summarises the results of the studies carried out to find out the various factors responsible for the extraordinary binding of thorium ion at the exchanger site while exploring the possibility of eluting total thorium using HNO3 alone

  14. Thorium biosorption by Aspergillus fumigatus, a filamentous fungal biomass

    International Nuclear Information System (INIS)

    Thorium biosorption by Aspergillus fumigatus was carried out in a batch reactor to study the effect of initial pH and metal ion concentration, contact time, biomass dose and kinetics and equilibrium Th uptake. Thorium(IV) uptake by A. fumigatus was pH dependent (pH range, 2.0-6.0) and maximum sorption was observed at pH 4.0. The uptake was rapid and the biosorption process reached equilibrium within 2 h of contact times at pH 2-4 and initial Th concentration of 50 and 100 mg/L. The kinetics data fitted well to Lagergren's pseudo-second-order rate equation (r2 > 0.99). A maximum initial sorption rate of 71.94 (mg/g min) and second-order rate constant of 7.82 x 10-2 (g/mg min) were observed at pH 4.0, 50 mg Th/L. The observed maximum uptake of thorium was 370 mg Th/g at equilibrium. Biosorption process could be well described by Langmuir isotherm in comparison to Freundlich and Temkin isotherms. Sodium bicarbonate was the most efficient desorbing reagent with desorption efficiency of more than 99%. Environmental scanning electron micrograph (ESEM) showed that the surface of the biomass after desorption was intact.

  15. Investigation of the thorium content in human tissues

    International Nuclear Information System (INIS)

    The content of natural alpha-emitting isotopes of thorium (Th-238, 230, and 232) have been determined in 22 sets of human tissue samples obtained at autopsy from Grand Junction, Colorado and 10 sets from Washington, DC. Lung, pulmonary lymph nodes, liver, kidney and bone were obtained for each case. Personal data for each individual's age, sex, smoking history, and occupation were obtained whenever possible. Radiochemical analysis was performed after tissue digestion, by solvent extraction, and electrodeposition, followed by solid state alpha spectrometric measurements using Si(Li) surface barrier detectors. Thorium-230 and 232 are distributed similarly in the body with the major fraction of the body burden present in bone (70%) followed by lung (20%) and lymph nodes (7%). Thorium-228 is found primarily in the skeleton (95%). For all isotopes, no significant difference was found between the concentration in tissue of smokers and non-smokers. The ratio of Th-230/232 in Colorado tissues was comparable to that of controls (Washington, DC) and probably reflects the relative geochemical abundance of the isotopes in local soils

  16. Radiochemical characterization of uranium and thorium isotopes in phosphogypsum

    International Nuclear Information System (INIS)

    Phosphogypsum is the by-product of the phosphoric acid industry and it is obtained by reacting phosphate rock with sulfuric acid. Approximately 69 million tons of this by-product have already been produced by the phosphate fertilizer industry in Brazil, whose production is 5.4 million tons per year. The accumulation of phosphogypsum, which is stockpiled and has no close destination, has become more and more problematical. The main objective of this study is to determine activity concentrations of 226Ra, 40K and uranium and thorium isotopes in phosphogypsum, which might help to find out an eventual future application for this material. A methodology has been developed and checked in order to determine 238U, 234U, 230Th, 232Th and 228Th in phosphate rock and phosphogypsum samples. This methodology is based on solvent extraction and ion exchange resins. The measurements were performed by alpha spectrometry. 226Ra, 232Th and 40K were also analysed by gamma spectrometry. The results showed that 226Ra migrates preferentially in the phosphogypsum, form 4 to 20%, and thorium concentrated about 80% in the phosphogypsum. The radioactive concentration of uranium isotopes ranged between 11 and 1700 Bq/kg. The radioactive concentration of thorium isotopes ranged between 7 and 850 Bq/kg. The concentration of 226Ra ranged between 22 and 1410 Bq/kg, and for 40K, it ranged between the detection limit and 41 Bq/kg. (author)

  17. Contributions to the thorium occupational exposure in Brazil

    International Nuclear Information System (INIS)

    There are around 15.000 workers in Brazil involved in the mining and milling processes of thorium bearing minerals. It is necessary to estimate the exposure of workers to airborne particulate containing thorium to estimate the risk associated with the inhalation of aerosols. The aims of this study were: - to develop a national cascade impactor and - to characterize the exposure of workers to airborne particulate containing Th in two plants and one industry that were chosen. Plant A and Pant B process niobium ore and industry C uses thorium nitrate to manufacture gas mantle. The national cascade impactor - ICN was developed to collect particulate in the range of 0,64 up to 19,4 μm. Its advantage over commercially available cascade impactors is the selections of particulate in the respirable and inhalable fractions of aerosol. The experimental calibration of the ICN agreed with the theoretical calibration. The results obtained with the ICN were compared to the ones obtained with other selective air samplers, in 3 plants. The particle size distribution and the Th mass concentration were determined in those plants. The size distribution of particulate containing Nb. U Zr, Pb. Fe, Y and Sr, and the elemental mass concentration was determined. A group of workers in installations B and C were also monitored through bioassay analysis of Th excreted in urine and feces. Air and bioassay results have shown that the systemic incorporation of Th is not significant. (author)

  18. Thorium biosorption by Aspergillus fumigatus, a filamentous fungal biomass.

    Science.gov (United States)

    Bhainsa, Kuber C; D'Souza, Stanislaus F

    2009-06-15

    Thorium biosorption by Aspergillus fumigatus was carried out in a batch reactor to study the effect of initial pH and metal ion concentration, contact time, biomass dose and kinetics and equilibrium Th uptake. Thorium(IV) uptake by A. fumigatus was pH dependent (pH range, 2.0-6.0) and maximum sorption was observed at pH 4.0. The uptake was rapid and the biosorption process reached equilibrium within 2h of contact times at pH 2-4 and initial Th concentration of 50 and 100mg/L. The kinetics data fitted well to Lagergren's pseudo-second-order rate equation (r(2)>0.99). A maximum initial sorption rate of 71.94 (mg/g min) and second-order rate constant of 7.82 x 10(-2) (g/mg min) were observed at pH 4.0, 50 mg Th/L. The observed maximum uptake of thorium was 370 mg Th/g at equilibrium. Biosorption process could be well described by Langmuir isotherm in comparison to Freundlich and Temkin isotherms. Sodium bicarbonate was the most efficient desorbing reagent with desorption efficiency of more than 99%. Environmental scanning electron micrograph (ESEM) showed that the surface of the biomass after desorption was intact. PMID:19036508

  19. Thorium fuel cycle concept for KAERI's accelerator driven system project

    International Nuclear Information System (INIS)

    Korea Atomic Energy Research Institute (KAERI) has been carrying out accelerator driven system related research and development called HYPER for transmutation and energy production. HYPER program is aiming to develop the elemental technologies for the subcritical system by 2001 and build a small bench scale test facility (∼5MW(th)) by the year 2006. Some major features of HYPER have been developed and employed, which are on-power fueling concepts, a hollow cylinder-type metal fuel, and Pb-Bi as a coolant and spallation target material. Another fuel cycle concept for HYPER has been also studied to utilize thorium as a molten salt form to produce electricity as well as to transmute TRU elements. At the early stage of the fuel cycle, fissile plutonium isotopes in TRU will be incinerated to produce energy and to breed 233U from thorium. Preliminary calculation showed that periodic removal of fission products and small amount of TRU addition could maintain the criticality without separation of 233Pa. At the end of the fuel cycle, the composition of fissile plutonium isotopes in TRU was significantly reduced from about 60% to 18%, which is not attractive any more for the diversion of plutonium. Thorium molten salt fuel cycle may be one of the alternative fuel cycles for the transmutation of TRU. The TRU remained at the end of fuel cycle can be incinerated in HYPER having fast neutron spectrums. (author)

  20. Uranium thorium dioxide fuel-cycle and economic analysis

    International Nuclear Information System (INIS)

    The fuel division of Framatome ANP (Advanced Nuclear Power) is performing a fuel-cycle analysis for uranium-thorium dioxide (U/Th) reactor fuel as part of a U.S. Department of Energy Nuclear Energy Research Initiative project titled, ''Advanced Proliferation Resistant, Lower Cost, Uranium-Thorium Dioxide Fuels for Light Water Reactor'', (DE-FC03-99SF21916). The objective is to evaluate the economic viability of the U/Th fuel cycle in commercial nuclear reactors operating in the U.S. This analysis includes formulating the evaluation methodology, validating the methodology via benchmark calculations, and performing a fuel-cycle analysis and corresponding economic evaluation. The APOLLO2-F computer program of Framatome ANP SCIENCE package was modified to incorporate the thorium decay chains and provide cross sections for the SCIENCE fuel-cycle analysis. A comparison and economic evaluation was made between UO2 and UO2/ThO2 fuel cycles in a typical 193-fuel assembly pressurized water reactor using reload batch sizes corresponding to batch average discharge burnups of 50, 70, and 90 GWd/mtHM. Results show an increase in front-end costs for the UO2/ThO2 cycles due primarily to the higher cost in separative work units for enriching the uranium to 19.5 wt% 235U. (author)

  1. Age dependence of natural uranium and thorium concentrations in bone.

    Science.gov (United States)

    Larivière, Dominic; Packer, Ana Paula; Marro, Leonora; Li, Chunsheng; Chen, Jing; Cornett, R Jack

    2007-02-01

    The age dependence of the natural concentration of uranium and thorium in the skeleton was investigated using human vertebrae bone collected from two Canadian locations (Winnipeg, Manitoba, and Regina, Saskatchewan). The concentration of both radioelements in digested ashed bone samples was determined using sector-field inductively coupled plasma mass spectrometry. The geometric means for uranium level in bones showed a significant statistical difference between the two locations studied. Similarly for thorium, a statistical difference was observed, although this difference was considered marginal. The thorium concentration differed only marginally with respect to age group, indicating that its behavior in the body could be age-independent. Conversely, the uranium level in bones was found to change for the age groups tested, an indication of age-specific deposition. The age profile for uranium was comparable to the calcium turn-over rate, indicating that uranium deposition is probably, in part, dictated by this metabolic process, showing the role of present uptake into the uranium concentration in bones for populations exposed to significant uranium intake. PMID:17220713

  2. Alkaline autoclave leaching of refractory uranium-thorium minerals

    International Nuclear Information System (INIS)

    This paper deals with the study of an innovative method for processing the Oman placer ores by alkaline leaching in ball mill autoclaves, where grinding and leaching of the refractory minerals take place simultaneously. This was followed by the selective separation of thorium and uranium from lanthanides by autoclave leaching of the hydroxide cake with ammonium carbonate-bicarbonate solutions. The introduced method is based on the fact that thorium and uranium form soluble carbonate complexes with ammonium carbonate, while lanthanides form sparingly soluble double carbonates. It was found that a complete alkaline leaching of Oman placer ores (98.0Percent) was attained at 150 and 175degreeC within 2.5 and 2h, respectively. Oman placer ores leaching was intensified and accelerated in a ball mill autoclaves as a result of the grinding action of steel balls, removal of the hydroxide layer covering ores grains and the continuous contact of fresh ore grains with alkaline solution. The study of selective carbonate processing of hydroxide cake with ammonium carbonate-bicarbonate solutions on autoclave under pressure revealed that the complete thorium recovery (97.5Percent) with uranium recovery (90.8Percent) and their separation from the lanthanides were attained at 70-80degreeC during l-2h. The extraction of lanthanides in carbonate solution was low and did not exceed 4.6Percent.

  3. Different periods of uranium and thorium occurrence in Madagascar (1960)

    International Nuclear Information System (INIS)

    In Madagascar, the first typical occurrences of thorium and uranium are about 500 million years old. Previously thorium and uranium were rather concentrated in the granitic and charnockitic zones, chiefly in minerals such as monazite, apatite and zircon. At the end of the Precambrian period, metasomatic granites occur especially in the anticlinal series (Andriba orthite granite). The granitization is followed by the formation of the main pegmatitic areas in the Island with Th-U niobotantalates, uraninite and beryl. The pegmatites are well developed in the synclinal series with a poor migmatization or no migmatization at all. In the same time a large uranium and thorium province with uranothorianite deposits appears within the calcomagnesian series of the Southern part of Madagascar. Later, large amounts of monazite were carried down to the detritic Karroo sediments during tile erosion of the metamorphic precambrian rocks. Monazite has been concentrated again by frequent marine incursions, till the present time. In the medium Karroo, near Folakara, uranium minerals occur in direct relation with carbonaceous material. Finally we must note the uranium occurrence in the pleistocene carbonaceous shales of Antsirabe basin, in contact with crystalline rocks. (author)

  4. Long term potential risk due to thorium mining

    International Nuclear Information System (INIS)

    As in the case of uranium, thorium extraction produces a certain amount of radioactive wastes, the so called mining residues, in which natural long-lived natural decay products are mobilized. Monazites, the most likely ores to be exploited first, in case of an extensive use of thorium as nuclear fuel, contain a certain fraction of uranium as well. One has studied potential long terms radiological impact of the residues originated from two typical monazites found in India and Italy, respectively poor an rich in uranium. In the case of the Italian monazite, uranium is supposed to be extracted at a level of 95%. For such monazites, the long term impact is completely governed by the residual uranium (presence of long-lived 238U descendants, 230Th (80,000 years) and/or 226Ra (1600 years)). However, for the two extreme cases studied here, the potential risks remain much smaller (by a factor lying between 20 to 50) than in the usual case of uranium mining. The risk due to radon is also correspondly reduced by the same factors. These significant differences between uranium and thorium mining have to be considered in view of some estimated long term real radiological impacts due to uranium residues, which could reach a value of the order of 1 mSv/year, the dose limit recommended for the public by the recent ICRP-60. (author). 7 refs, 3 figs, 3 tabs

  5. The Effective Resonance Integral of Thorium Oxide Rods

    International Nuclear Information System (INIS)

    The effective resonance integral of thorium oxide rods has been determined as a function of their surface to mass ratio. The range of S/M values covered is 0.15 - 0.65 cm/g. An experimental technique based on the comparison of activities obtained in thermal and slowing-down neutron fluxes was employed. The shape of the resonance neutron spectrum was determined from measurements with a fast chopper and from calculations, permitting deduction of a correction factor which relates the experimental values to the ideal 1/E case. The results are summarized by the following expression: RIThO2 (5.0 + 15.6√(S/MThO2)) ± 5% The main contribution to the margin of error arises from the uncertainties in the 1.5 % spectral correction applied in the 1.5 b '1/v' part deducted and in the 1520 b infinite dilution integral of gold, used as a standard. In order to compare the consistency of Dresner's first equivalence theorem and Nordheim's numerical calculations relative to our results, the resonance integral values for thorium metal rods obtained previously by Hellstrand and Weitman have been recalculated, using recent cross section and spectrum data. The new formula is RlTh = (3.3 + 16.1√(S/MTh)) ± 5%. It differs from the old one mainly because of the proved non-1/v behaviour of the thorium cross section below the first resonance

  6. Application of EDRXF technique for the determination of uranium and thorium in beach sand minerals

    International Nuclear Information System (INIS)

    Zircon is a naturally occurring mineral and is available in many locations all over the world, This mineral usually contains U and Th at about 100-500 μg/g. Naturally occurring TiO2, containing minerals, rutile and ilmenite have small quantities of associated uranium. Natural rutile may contain upto 10% iron and upto 500 μg/g of uranium. Since the availability of rutile in nature is limited, ilmenite is used as raw material for producing synthetic rutile. In India, from monazite, thorium is separated by Indian Rare Earths Ltd., wherein uranium is a bye product. Since rutile is of importance to the gemstone markets, this is also produced from ilmenite ore. Roasting, reduction and leaching processes are important steps for removal of iron economically and efficiently from ilmenite ore during the production of synthetic rutile. We have developed a method to determine U and Th in zircon, using synthetic powder standards of ZrO2, containing U and Th in the range of 50 to 1000 μg/g. The limits of detection for U and Th were determined to be 200 and 100 μg/g respectively. Three zircon ore samples from different locations in India were analyzed for uranium and thorium using the method. The standardized method can be used for fast determination U and Th in zircon samples non-destructively with a precision of 10-20 %. Further another method was developed for the determination of uranium in rutile. Since iron and chromium are among the other impurities co-existing with U in rutile, these analytes have been included in the method. Synthetic standards containing U at 200-10,000 μg/g and Fe, Cr at 100- 2000 μg/g level were prepared and the spectrometer was calibrated using these standards. Two synthetic samples were analyzed using this method to evaluate the method for its reliability and reproducibility. In the present talk, details of these studies will be discussed. Moreover the work carried out on the determination of U/Th in sand minerals by other international

  7. Thorium cycle implementation through plutonium incineration by thorium molten-salt nuclear energy synergetics

    International Nuclear Information System (INIS)

    Considering the increasing world energy demand and the urgent necessity of replacement of fossil-fuel by nuclear energy for survival of the global environmental crisis, we urgently need to prepare a more rational and a huge nuclear industry. As an improved alternative of present technology, the utilization of U is strongly recommended. ORNL proposed an idealistic MSBR since 1970. We modified it to the world-wide applicable system: THORIMS-NES [Thorium Molten-Salt Nuclear Energy Synergetic System], which is composed of simple thermal fission power stations (FUJI) and fissile-producing Accelerator Molten-Salt Breeder (AMSB). FUJI is a size-flexible NEAR BREEDER even not using continuous chemical processing and core-graphite exchange, and AMSB is based on a single-fluid molten-salt target/blanket concept, the technological development of which is easy and simple except for the high-current proton accelerator. THORIMS-NES has many advantages, and here the issues of safety, nuclear-proliferation and social/philosophical acceptance is mostly explained. In practice, the shift to THORIMS-NES from the present U-Pu cycle era will be smoothly implemented by converting Pu and TRU in weapons and spent-fuels into molten fluoride salt by a drying process (such as the Russian FREGATE project) which was established by the French, Russians and Czechs. Pilot plant 'mini FUJI', 7MW(e) might be commissioned after 7 years depending on the result of successful 4 years operation of MSRE in ORNL, and Small Demonstration Reactor 'FUJI-Pu', 150MW(e) can probably be in operation 12 years from now utilizing the world ability of Na-Reactor Technology. Depending on such MSR-technology development, AMSB-Pu might be able to industrialize 20 years from now. (author)

  8. Spent fuel treatment options and application - An Indian perspective

    International Nuclear Information System (INIS)

    India has opted for a three stage nuclear power programme based on a closed fuel cycle approach for the development of the nuclear energy. Currently India has a total of 16 operating power reactors comprising 14 PHWRs and 2 BWRs with a total power capacity of 3.9 GW. The energy demand is growing by leaps and bounds and the per capita energy requirement is expected to cross 5000 KWh by the middle of the century. For the next 20 years, India will have to rely mainly on thermal and hydroelectric power. However in the long run, nuclear energy can play a vital role in the future energy mix since our coal reserve is finite and hydroelectric power addition can only be moderate. Reprocessing and recycling of the fissile and fertile components back into appropriate reactor systems is an integral part of the Indian nuclear energy programme. The limited natural uranium resources will be used up in the first phase and the vast resources of thorium is expected to be employed for sustained electricity generation in the third phase. The plutonium recovered from the first phase will serve as a link between the two phases where it will be deployed in fast reactors for enhancing the fissile inventory to launch the thorium fuel cycle. The choice of the reprocessing and plutonium recycle option has endowed the nuclear power program with a variety of midcourse options in both uranium and thorium fuel cycle. This spent fuel reprocessing programme was launched way back in 1964 with the commissioning of the plant at Tromby for the reprocessing of research reactor spent fuel. This was followed by setting up of another plant in 1975 at Tarapur for the reprocessing of spent fuel from PHWRs. The next plant for the reprocessing of power reactor spent fuel was commissioned in 1998 at Kalpakkam to meet the growing requirements of the nuclear energy programme. India is about to step up its nuclear energy production and is ready to launch the second stage activities by setting up Fast Breeder

  9. Thorium determination by X-ray Fluorescence Spectrometry in simulated thorex process solutions

    International Nuclear Information System (INIS)

    The X-ray fluorescence method for thorium determination in aqueous and organic (TBP-n-dodecane) solutions is described. The thin film-technique for sample preparation and a suitable internal standard have been used. Some parameters as analytical line, internal standard, filter paper, paper geometry, sample volume and measurement conditions were studied. Uranium, fission products, corrosion products and thorex reagent components were studied as interfering elements in the thorium analysis, as well as the matrix effect by using the thorex process simulated solutions the method to thorium determination in irradiated thorium solutions was applied. (M.J.C.)

  10. Remeasurement of thorium-230 in the pore water of Lacnor tailings

    International Nuclear Information System (INIS)

    A resampling of the Lacnor tailings management area was undertaken under a comprehensive quality assurance programme to establish levels of thorium 230 in pore water. A quality assurance programme was established for field sampling, sample handling and transport, and laboratory procedures and reporting. The external audit was used to evaluate analytical bias (on synthetic and field samples) and precision (by comparison of duplicate-duplicate results). Accuracy was assessed using synthetic samples. The external audit indicates that thorium 230 measurements by the main laboratory are not significantly different from the interlaboratory average within standard statistical limits. The results of the audit are based on measurement of environmental samples and known synthetic samples. This shows that present and previous measurements of thorium 230 varying from 0,1 to 150 Bq/L are valid data. A qualitative interpretation of the controls on thorium 230 geochemistry is provided in terms of control by thorium 232 and thorium dioxide(c) solid phase. Generic dose estimates for consumption of water containing thorium 230 are made but require refinement ot account for the actual pH of the drinking water and the degree of dilution of the pore water. The results of this project indicate that the performance of the laboratory that will conduct future thorium 230 measurements can be assessed satisfactorily with a smaller scale external laboratory assurance programme. The programme should include replicate samples sent to each laboratory and interlaboratory comparison on samples having high and low values of thorium 230

  11. The biokinetics of thorium nitrate after deposition in the rat lung: implications for occupational exposure

    International Nuclear Information System (INIS)

    Biokinetic studies in rats have indicated that: 1) thorium nitrate behaves more like a Class Y compound than a Class W compound as defined by ICRP; 2) any increased excretion of thorium in the presence of excessive amounts of Class D uranium compounds does little to arrest the substantial reduction in the ALI from that based on uranium alone; 3) the behaviour of thorium is sufficiently different from that of its gamma-ray emitting daughter radionuclides as to cast doubt on the reliability of external monitoring techniques for assessing intake; and 4) the chelating agent DTPA will be of little value for treating workers overexposed to thorium. (Author)

  12. Modified anion-exchange method for determination of thorium in uranium based materials

    International Nuclear Information System (INIS)

    This paper details a modified anion-exchange method for estimation of thorium in uranium based samples like uranium dioxide powders, pellets and uranyl nitrate solutions. The method involves separation of thorium from uranium from 3M commercial grade HCl containing 15% NaCl through an anion-exchange resin. The uranium free effluent containing the analyte(thorium) is determined spectrophotometrically by exploiting absorption of the thorium-arsenazo III complex at 660 nm. The method has a precision of about ±2% at 50 ppm level. (author). 3 refs., 1 tab

  13. New Indian Tribalism. Working Paper.

    Science.gov (United States)

    Beckmann, Kathleen

    The purposes of this paper are to identify the problems Washington State Indians face and to provide considerations that might assist in promoting the welfare and well-being of American Indians. It is stated that the major barrier to the Indian's success in American society is the attitude of the Anglo towards the Indian. Thus, the programs and…

  14. 76 FR 33341 - Indian Gaming

    Science.gov (United States)

    2011-06-08

    ... Bureau of Indian Affairs Indian Gaming AGENCY: Bureau of Indian Affairs, Interior. ACTION: Notice of Approved Tribal--State Class III Gaming Compact. SUMMARY: This notice publishes an extension of Gaming... FURTHER INFORMATION CONTACT: Paula L. Hart, Director, Office of Indian Gaming, Office of the...

  15. 78 FR 10203 - Indian Gaming

    Science.gov (United States)

    2013-02-13

    ... Bureau of Indian Affairs Indian Gaming AGENCY: Bureau of Indian Affairs, Interior. ACTION: Notice of Approved Tribal State Class III Gaming Compact. SUMMARY: This notice publishes the Approval of the Class III Tribal- State Gaming Compact between the Chippewa-Cree Tribe of the Rocky Boy's Indian...

  16. 77 FR 59641 - Indian Gaming

    Science.gov (United States)

    2012-09-28

    ... Bureau of Indian Affairs Indian Gaming AGENCY: Bureau of Indian Affairs, Interior. ACTION: Notice of Approved Tribal-State Class III Gaming Compact. SUMMARY: This notice publishes an extension of Gaming.... FOR FURTHER INFORMATION CONTACT: Paula L. Hart, Director, Office of Indian Gaming, Office of...

  17. 76 FR 65208 - Indian Gaming

    Science.gov (United States)

    2011-10-20

    ... Bureau of Indian Affairs Indian Gaming AGENCY: Bureau of Indian Affairs, Interior. ACTION: Notice of Approved Tribal--State Class III Gaming Compact. SUMMARY: This notice publishes an Approval of the Gaming..., Office of Indian Gaming, Office of the Deputy Assistant Secretary--Policy and Economic...

  18. 77 FR 45371 - Indian Gaming

    Science.gov (United States)

    2012-07-31

    ... Bureau of Indian Affairs Indian Gaming AGENCY: Bureau of Indian Affairs, Interior. ACTION: Notice of Approved Tribal--State Class III Gaming Compact. SUMMARY: This notice publishes an extension of Gaming... FURTHER INFORMATION CONTACT: Paula L. Hart, Director, Office of Indian Gaming, Office of the...

  19. 75 FR 8108 - Indian Gaming

    Science.gov (United States)

    2010-02-23

    ... Bureau of Indian Affairs Indian Gaming AGENCY: Bureau of Indian Affairs, Interior. ACTION: Notice of Approved Tribal-State Class III Gaming Compact. SUMMARY: This notice publishes approval of the Tribal-State Compact between the Pyramid Lake Paiute Indian Tribe and the State of Nevada Governing Class III...

  20. 75 FR 68618 - Indian Gaming

    Science.gov (United States)

    2010-11-08

    ... Bureau of Indian Affairs Indian Gaming AGENCY: Bureau of Indian Affairs, Interior. ACTION: Notice of... the Red Cliff Band of Lake Superior Chippewas (``Tribe'') and the State of Wisconsin Gaming Compact of... CONTACT: Paula L. Hart, Director, Office of Indian Gaming, Office of the Deputy Assistant...

  1. 78 FR 44146 - Indian Gaming

    Science.gov (United States)

    2013-07-23

    ... Bureau of Indian Affairs Indian Gaming AGENCY: Bureau of Indian Affairs, Interior. ACTION: Notice of Tribal-State Class III Gaming Compact taking effect. SUMMARY: This notice publishes the Class III Amended and Restated Tribal-State Gaming Compact between the Shingle Springs Band of Miwok Indians and...

  2. 76 FR 56466 - Indian Gaming

    Science.gov (United States)

    2011-09-13

    ... Bureau of Indian Affairs Indian Gaming AGENCY: Bureau of Indian Affairs, Interior. ACTION: Notice of Approved Tribal--State Class III Gaming Compact. SUMMARY: This notice publishes an approval of the gaming...: September 13, 2011. FOR FURTHER INFORMATION CONTACT: Paula L. Hart, Director, Office of Indian...

  3. 76 FR 52968 - Indian Gaming

    Science.gov (United States)

    2011-08-24

    ... Bureau of Indian Affairs Indian Gaming AGENCY: Bureau of Indian Affairs, Interior. ACTION: Notice of Approved Tribal--State Class III Gaming Compact. SUMMARY: This notice publishes an extension of Gaming... FURTHER INFORMATION CONTACT: Paula L. Hart, Director, Office of Indian Gaming, Office of the...

  4. 77 FR 43110 - Indian Gaming

    Science.gov (United States)

    2012-07-23

    ... Bureau of Indian Affairs Indian Gaming AGENCY: Bureau of Indian Affairs, Interior. ACTION: Notice of Approved Tribal--State Class III Gaming Compact. SUMMARY: This notice publishes an extension of Gaming... FURTHER INFORMATION CONTACT: Paula L. Hart, Director, Office of Indian Gaming, Office of the...

  5. 78 FR 15738 - Indian Gaming

    Science.gov (United States)

    2013-03-12

    ... Bureau of Indian Affairs Indian Gaming AGENCY: Bureau of Indian Affairs, Interior. ACTION: Notice of Approved Tribal--State Class III Gaming Compact. SUMMARY: This notice publishes an extension of the gaming..., 2013. FOR FURTHER INFORMATION CONTACT: Paula L. Hart, Director, Office of Indian Gaming, Office of...

  6. 75 FR 55823 - Indian Gaming

    Science.gov (United States)

    2010-09-14

    ... Bureau of Indian Affairs Indian Gaming AGENCY: Bureau of Indian Affairs, Interior. ACTION: Notice of approved Tribal-State Class III Gaming Compact. SUMMARY: This notice publishes an extension of Gaming.... FOR FURTHER INFORMATION CONTACT: Paula L. Hart, Director, Office of Indian Gaming, Office of...

  7. 78 FR 26801 - Indian Gaming

    Science.gov (United States)

    2013-05-08

    ... Bureau of Indian Affairs Indian Gaming AGENCY: Bureau of Indian Affairs, Interior. ACTION: Notice of Approved Tribal-State Class III Gaming Compact. SUMMARY: This notice publishes the approval of an amendment to the Class III Tribal-State Gaming Compact between the Menominee Indian Tribe of Wisconsin and...

  8. 78 FR 11221 - Indian Gaming

    Science.gov (United States)

    2013-02-15

    ... Bureau of Indian Affairs Indian Gaming AGENCY: Bureau of Indian Affairs, Interior. ACTION: Notice of Approved Tribal-State Class III Gaming Compact. SUMMARY: This notice publishes an extension of the gaming..., 2013. FOR FURTHER INFORMATION CONTACT: Paula L. Hart, Director, Office of Indian Gaming, Office of...

  9. 75 FR 38833 - Indian Gaming

    Science.gov (United States)

    2010-07-06

    ... Bureau of Indian Affairs Indian Gaming AGENCY: Bureau of Indian Affairs, Interior. ACTION: Notice of Approved Tribal-State Class III Gaming Compact. SUMMARY: This notice publishes the Approved Compact between... FURTHER INFORMATION CONTACT: Paula Hart, Director, Office of Indian Gaming, Office of the Deputy...

  10. 77 FR 76514 - Indian Gaming

    Science.gov (United States)

    2012-12-28

    ... Bureau of Indian Affairs Indian Gaming AGENCY: Bureau of Indian Affairs, Interior. ACTION: Notice of Approved Tribal-State Class III Gaming Compact taking effect. SUMMARY: This notice publishes the Approval... L. Hart, Director, Office of Indian Gaming, Office of the Deputy Assistant Secretary--Policy...

  11. 77 FR 76513 - Indian Gaming

    Science.gov (United States)

    2012-12-28

    ... Bureau of Indian Affairs Indian Gaming AGENCY: Bureau of Indian Affairs, Interior. ACTION: Notice of Approved Amended Tribal-State Class III Gaming Compact taking effect. SUMMARY: This notice publishes the... CONTACT: Paula L. Hart, Director, Office of Indian Gaming, Office of the Deputy Assistant...

  12. 76 FR 8375 - Indian Gaming

    Science.gov (United States)

    2011-02-14

    ... Bureau of Indian Affairs Indian Gaming AGENCY: Bureau of Indian Affairs, Interior. ACTION: Notice of Approved Tribal-State Class III Gaming Compact. SUMMARY: This notice publishes an extension of the Gaming..., 2011. FOR FURTHER INFORMATION CONTACT: Paula L. Hart, Director, Office of Indian Gaming, Office of...

  13. 75 FR 68823 - Indian Gaming

    Science.gov (United States)

    2010-11-09

    ... Bureau of Indian Affairs Indian Gaming AGENCY: Bureau of Indian Affairs, Interior. ACTION: Notice of Approved Tribal-State Class III Gaming Amendment. SUMMARY: This notice publishes approval of the Amendments to the Class III Gaming Compact (Amendment) between the State of Oregon and the Siletz Indians...

  14. Rasam Indian Restaurant: Menu

    OpenAIRE

    Rasam Indian Restaurant

    2013-01-01

    Rasam Indian Restaurant is located in the Glasthule, a suburb of Dublin and opened in 2003. The objective is to serve high quality, authentic Indian cuisine. "We blend, roast and grind our own spices daily to provide a flavour that is unique to Rasam. Cooking Indian food is founded upon long held family traditions. The secret is in the varying elements of heat and spices, the tandoor clay oven is a hugely important fixture in our kitchen. Marinated meats are lowered into the oven on long m...

  15. Indian concepts on sexuality

    Science.gov (United States)

    Chakraborty, Kaustav; Thakurata, Rajarshi Guha

    2013-01-01

    India is a vast country depicting wide social, cultural and sexual variations. Indian concept of sexuality has evolved over time and has been immensely influenced by various rulers and religions. Indian sexuality is manifested in our attire, behavior, recreation, literature, sculptures, scriptures, religion and sports. It has influenced the way we perceive our health, disease and device remedies for the same. In modern era, with rapid globalization the unique Indian sexuality is getting diffused. The time has come to rediscover ourselves in terms of sexuality to attain individual freedom and to reinvest our energy to social issues related to sexuality. PMID:23858263

  16. Safety implications of reactivity variations in fast thorium ADSRs

    International Nuclear Information System (INIS)

    Highlights: ► A lumped fast reactor model is used to simulate reactivity and power variations in a fast thorium ADSR. ► Neutron flux changes produce reactivity changes due to shifts in the 233Pa and 233U populations. ► On reactor start-up, the reactivity will fall in the early part of the burn-up. ► On reactor shutdown the reactivity will increase. ► A thorium fuelled ADSR operating at keff ⩾ 0.990 is at risk from an accelerator-trip-induced post-shutdown criticality excursion. - Abstract: Nuclear power generation offers a reliable, low-impact and large-scale alternative to fossil fuels. However, concerns exist over the safety and sustainability of this method of power production, and it remains unpopular with some governments and pressure groups throughout the world. Fast thorium fuelled accelerator-driven sub-critical reactors (ADSRs) offer a possible route to providing further re-assurance regarding these concerns on account of their properties of enhanced safety through sub-critical operation combined with reduced actinide waste production from the thorium fuel source. The appropriate sub-critical margin at which these reactors should operate is the subject of continued debate. Commercial interests favour a small sub-critical margin in order to minimise the size of the accelerator needed for a given power output, whilst enhanced safety would be better satisfied through larger sub-critical margins to further minimise the possibility of a criticality excursion. Against this background, this paper examines some of the issues affecting reactor safety inherent within thorium fuel sources resulting from the essential 23290Th→23390Th→23391Pa→23392U breeding chain. Differences in the decay half-lives and fission and capture cross-sections of 233Pa and 233U can result in significant changes in the reactivity of the fuel following changes in the reactor power. Reactor operation is represented using a homogeneous lumped fast reactor model that can

  17. Methodology of simultaneous analysis of Uranium and Thorium by nuclear and atomic techniques. Application to the Uranium and Thorium dosing in mineralogic samples

    International Nuclear Information System (INIS)

    This work concerns essentially the potential applications of 100 kW nuclear reactor of Strasbourg Nuclear Research Centre to neutron activation analysis of Uranium and Thorium. The Uranium dosing has been made using: 239-U, 239-Np, fission products or delayed neutrons. Thorium has been showed up by means of 233-Th or 233-Pa. The 239-U and 233-Th detection leads to a rapid and non-destructive analysis of Uranium and Thorium. The maximum sensitivity is of 78 ng for Uranium and of 160 ng for Thorium. The Uranium and Thorium dosing based on 239-Np and 233-Pa detection needs chemical selective separations for each of these radionuclides. The liquid-liquid extraction has permitted to elaborate rapid and quantitative separation methods. The sensitivities of the analysis after extraction reach 30 ng for Uranium and 50 ng for Thorium. The fission products separation study has allowed to elaborate the La, Ce and Nd extractions and its application to the Uranium dosing gives satisfying results. A rapid dosing method with a sensitivity of 0.35 microgramme has been elaborated with the help of delayed neutrons measurement. These different methods have been applied to the Uranium and Thorium dosing in samples coming from Oklo mine in Gabon. The analyses of these samples by atomic absorption spectroscopy and by the proton induced X-ray emission (PIXE) method confirm that the neutron activation analysis methods are reliable. 37 figs., 14 tabs., 50 refs

  18. Band structure and decay channels of thorium-229 low-lying isomeric state for ensemble of thorium atoms adsorbed on calcium fluoride

    International Nuclear Information System (INIS)

    The results are presented on the study of the electronic structure of thorium atoms adsorbed by the liquid atomic layer deposition from aqueous solution of thorium nitrate on the surface of CaF2. The chemical state of the atoms and the change of the band structure in the surface layers of Th/CaF2 system on CaF2 substrate were investigated by XPS and REELS techniques. It was found that REELS spectra for Th/CaF2 system include peaks in the region of low energy losses (3-7 eV) which are missing in the similar spectra for pure CaF2. It is concluded that the presence of the observed features in the REELS spectra is associated with the chemical state of thorium atoms and is caused by the presence of uncompensated chemical bonds at the Th/CaF2 interface, and, therefore, by the presence of unbound 6d- and 7s-electrons of thorium atoms. Assuming the equivalence of the electronic configuration of thorium-229 and thorium-232 atoms, an estimate was made on the time decay of the excited state of thorium-229 nuclei through the channel of the electron conversion. It was found that the relaxation time is about 40 μs for 6d-electrons, and about 1 μs for 7s-electrons. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. Recovery of radiogenic lead-208 from a residue of thorium and rare earths obtained during the operation of a thorium purification pilot plant

    International Nuclear Information System (INIS)

    Brazil has a long tradition in thorium technology, from mineral dressing (monazite) to the nuclear grade thorium compounds. The estimate reserves are 1200,000. ton of ThO2. As a consequence from the work of thorium purification pilot plant at Instituto de Pesquisas Energeticas e Nucleares-CNEN/IPEN-SP, about 25 ton of a sludge containing thorium and rare earths was accumulated. It comes as a raffinate and washing solutions from thorium solvent extraction. This sludge, a crude hydroxide named RETOTER contains thorium, rare earths and minor impurities including the radiogenic lead-208, with abundance 88.34 %. This work discusses the results of the studies and main parameters for its recovery by anionic ion exchange technique in the hydrochloric system. The isotope abundance of this lead was analyzed by high resolution mass spectrometer (ICPMS) and thermoionic mass spectrometer (TIMS) and the data was used to calculate the thermal neutron capture cross section. The value of σγ0 = 14.6±0.7 mb was found, quite different from the σγ0 = 174.2 ± 7.0 mb measure cross section for the natural lead. Preliminary study for the thorium and rare earths separation and recovery was discussed as well. (author)

  20. Recovery of radiogenic lead-208 from a residue of thorium and rare earths obtained during the operation of a thorium nitrate purification pilot plant

    International Nuclear Information System (INIS)

    Brazil has a long tradition in thorium technology, from mineral dressing (monazite) to the nuclear grade thorium compounds. The estimate reserves are 1200,000. ton of ThO2. As a consequence from the work of thorium purification pilot plant at Instituto de Pesquisas Energeticas e Nucleares-CNEN/SP, about 25 ton of a sludge containing thorium and rare earths was accumulated. It comes as a raffinate and washing solutions from thorium solvent extraction. This sludge, a crude hydroxide named RETOTER contains thorium, rare earths and minor impurities including the radiogenic lead-208, with abundance 88.34 %. This work discusses the results of the studies and main parameters for its recovery by anionic ion exchange technique in the hydrochloric system. The isotope abundance of this lead was analyzed by high resolution mass spectrometer (ICPMS) and thermoionic mass spectrometer (TIMS) and the data was used to calculate the thermal neutron capture cross section. The value of s?o = 14.6 +/- 0.7 mb was found, quite different from the s?o = 174.2 +/- 7.0 mb measure cross section for the natural lead. Preliminary study for the thorium and rare earths separation and recovery was discussed as well. (author)

  1. Variation of the thorium to uranium ratio in rain: thorium-230 chronology of the eruptions of Mt. St. Helens and El Chichon volcanoes

    International Nuclear Information System (INIS)

    Principles of the thorium-230 dating method were applied to the study of thorium and uranium isotopes in a seris of rain samples collected at Fayetteville (36 degN, 94 degW), Arkansas, since 1980. The results indicate that the rainwater contains volcanic ash materials with a wide variety of ages, which were blown up onto the upper stratosphere from the 18 May 1980 eruption of Mount St. Helens and the 28 March 1982 eruption of El Chichon. These volcanic materials seem to have stayed airborne for a number of years and profoundly affected the global atmospheric inventories of thorium and uranium isotopes. (author) 11 refs.; 7 figs

  2. Indian Cosmological Ideas

    CERN Document Server

    Narayan, R

    2007-01-01

    This paper, third in the series on Indian tradition of physics, describes conceptions of the cosmos with ideas that are clearly spelt out in texts such as Yoga Vasishtha.In particular, the conception of multiple universes that occurs often in this text will be examined in the framework of the Indian physics. The other surprising concepts that are discussed include flow of time and its variability with respect to different observers, and the possibility of passage across universes.

  3. A review of the current status of nuclear data for major and minor isotopes of thorium fuel cycle

    International Nuclear Information System (INIS)

    In this paper, we present a critical overview of the status of the available nuclear data of isotopes of thorium fuel cycle, viz., 230Th, 232Th, 231Pa, 233Pa, 232U, 233U and 234U. Induced in the main body of the paper is a critical analysis of information contained in the two basic evaluated nuclear data files JENDL-3.2 and ENDF/B-VI (Rev.5) recently released by the IAEA/NDS as a result of truly international efforts. In some of the cases, the information and data given in EXFOR is examined to get an idea of the status of measured nuclear data of these isotopes. Some comments regarding gaps in experimental data as of 1999 are included in the discussion. Most of these experimental data were those generated two decades ago. In addition, generally, these experimental data are very limited in comparison to the voluminous nuclear data generated for the uranium-plutonium cycle. Experimental data is absent in most of the cases and, in such cases, evaluated cross sections in the two basic evaluated nuclear data files JENDL-3.2 and ENDF/B-VI(Rev.5) are based upon theoretical models and nuclear systematics. Some of these differences between JEF-2.2 and its source ENDF/B-V that were carried over to ENDF/B-VI(Rev.5) are explained. The role and the importance of 231Pa and 233Pa in the thorium fuel cycle in advanced concepts such as the Energy Amplifier are mentioned. New calculations of criticality property of 231Pa and 233Pa are presented using the neutron reaction data of JENDL-3.2 and ENDF/B-VI(Rev.5). The possible influence of 230Th is examined with respect to its cross sections and production of 231Pa in a typical Indian PHWR environment. The quality assurance in design and safety studies in nuclear energy in the next few decades and centuries require new and improved data with high accuracy and energy resolution. As a starter, the nuclear data of the set of isotopes of thorium fuel cycle discussed in this paper is a challenging sample for consideration as a trial project

  4. Analytical procedure for the determination of thorium, zinc and potassium in diet samples

    International Nuclear Information System (INIS)

    Instrumental neutron activation analysis (INAA), and atomic absorption spectrometry (AAS) have been used for the determination of trace amounts of thorium, zinc, and potassium in diet samples. Interlaboratory comparison has been made. The z-scores show that INAA can be used to determine thorium and zinc whereas AAS can be employed to determine potassium in diet samples. (author)

  5. Study of IV B elements carbonate complexes 1. Stability constant of thorium (IV) pentacarbonate complex

    International Nuclear Information System (INIS)

    A method for the solvent extraction of thorium (IV) by chelation and neutronic activation analysis, allows the determination of stability constant of thorium (IV) pentacarbonate complexe at an ionic strength of 1.0 and 2.5: log β = 26.2 ± 0.2 and 26.3 ± 0.2. 10 refs

  6. 49 CFR 173.434 - Activity-mass relationships for uranium and natural thorium.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Activity-mass relationships for uranium and natural thorium. 173.434 Section 173.434 Transportation Other Regulations Relating to Transportation....434 Activity-mass relationships for uranium and natural thorium. The table of...

  7. Norwegian thorium might solve the world climate problems and energy crisis

    International Nuclear Information System (INIS)

    The article discusses the possibilities of developing Norway into a energy giant also after the decline of oil and gas production through use of new technologies and exploiting the large natural thorium reserves. Some advantages of thorium to uranium as energy source in the nuclear power industry are also discussed. Some environmental aspects are mentioned. (tk)

  8. Atomic Energy Control Board and its role in the regulation of uranium and thorium mines

    International Nuclear Information System (INIS)

    Laws governing the Atomic Energy Control Board (AECB), its structure and functions is described in the context of the Board's role in uranium and thorium mining. The licensing and compliance procedures are described as they pertain to the objectives of the AECB in protecting workers, the public and the environment during construction, operating and closure of uranium and thorium mining and milling facilities. (OT)

  9. Inhalation radiotoxicity of irradiated thorium as a heavy water reactor fuel

    International Nuclear Information System (INIS)

    The online refueling capability of Heavy Water Reactors (HWRs), and their good neutron economy, allows a relatively high amount of neutron absorption in breeding materials to occur during normal fuel irradiation. This characteristic makes HWRs uniquely suited to the extraction of energy from thorium. In Canada, the toxicity and radiological protection methods dealing with personnel exposure to natural uranium (NU) spent fuel (SF) are well-established, but the corresponding methods for irradiated thorium fuel are not well known. This study uses software to compare the activity and toxicity of irradiated thorium fuel ('thorium SF') against those of NU. Thorium elements, contained in the inner eight elements of a heterogeneous high-burnup bundle having LEU (Low-enriched uranium) in the outer 35 elements, achieve a similar burnup to NU SF during its residence in a reactor, and the radiotoxicity due to fission products was found to be similar. However, due to the creation of such inhalation hazards as U-232 and Th-228, the radiotoxicity of thorium SF was almost double that of NU SF after sufficient time has passed for the decay of shorter-lived fission products. Current radio-protection methods for NU SF exposure are likely inadequate to estimate the internal dose to personnel to thorium SF, and an analysis of thorium in fecal samples is recommended to assess the internal dose from exposure to this fuel. (authors)

  10. Separation of thorium ions from wolframite and scandium concentrates using graphene oxide.

    Science.gov (United States)

    Jankovský, Ondřej; Sedmidubský, David; Šimek, Petr; Klímová, Kateřina; Bouša, Daniel; Boothroyd, Chris; Macková, Anna; Sofer, Zdeněk

    2015-10-14

    The separation of rare metals from the ores and commercially available compounds is an important issue due to the need of their high purity in advanced materials and devices. Important examples of two highly important elements that co-exist in the ores are scandium and thorium. Scandium containing ores and consequently also commercially available scandium compounds often contain traces of thorium which is very difficult to separate. We used graphene oxide for the selective sorption of thorium ions from scandium and thorium mixtures originating from the mined ores as well as from commercially available scandium salts. Our results showed that graphene oxide has an extreme affinity towards thorium ions. After the sorption process the graphene oxide contained over 20 wt% of thorium while the amount of scandium sorbed on GO was very low. This phenomenon of high sorption selectivity of graphene oxide can be applied in industry for the purification of various chemicals containing scandium and for separation of thorium containing mixtures. Alternatively, this methodology can be used for preconcentration of thorium from low-grade ores and its further use in the new generation of nuclear reactors. PMID:26352806

  11. Spent fuel characteristics analysis for thorium-uranium breeding recycle in PWRs

    International Nuclear Information System (INIS)

    Spent fuel characteristics analyses of thorium-based fuel were investigated using ORIGEN-S code compared with uranium-based fuel. Such parameters as radio- activity, radiotoxicity, decay heat, and gamma ray were considered. Relative results in this work could provide some reference information for storage, reprocessing and disposal of thorium-based spent fuel. Four type fuels, thorium-based fuel U3ThOX (mixed reactor grade 233U-thorium oxide), PuThOX (mixed reactor grade plutonium-thorium oxide), uranium-based fuel UOX (uranium oxide) and MOX (mixed reactor grade plutonium-uranium oxide), on the basis of core designs for thorium-uranium breeding recycle in PWRs were investigated. The calculated results show that: 1) Due to extremely low content of transuranic nuclides, the radiotoxicity of U3ThOX is dramatically lower than that of three other types of spent fuel in 1000 years after discharge; 2) In thorium-based spent fuel the intensity of gamma ray near 2.6 MeV mainly generated by 208Tl in 232U decay chain is much stronger than that in uranium-based fuel. The intensity of γ ray near 2.6 MeV reaches a local peak in about 10 years after discharge when the reprocessing should not be performed for thorium-based spent fuel. (authors)

  12. 76 FR 24871 - Reimbursement for Costs of Remedial Action at Active Uranium and Thorium Processing Sites

    Science.gov (United States)

    2011-05-03

    ... Reimbursement for Costs of Remedial Action at Active Uranium and Thorium Processing Sites AGENCY: Department of... from eligible active uranium and thorium processing site licensees for reimbursement under Title X of the Energy Policy Act of 1992. DATES: In our Federal Register Notice of November 24, 2010, (75...

  13. 75 FR 71677 - Reimbursement for Costs of Remedial Action at Active Uranium and Thorium Processing Sites

    Science.gov (United States)

    2010-11-24

    ... Reimbursement for Costs of Remedial Action at Active Uranium and Thorium Processing Sites AGENCY: Department of... uranium and thorium processing site licensees for reimbursement under Title X of the Energy Policy Act of... published a final rule under 10 CFR Part 765 in the Federal Register on May 23, 1994, (59 FR 26714) to...

  14. Critical review of analytical techniques for safeguarding the thorium-uranium fuel cycle

    Energy Technology Data Exchange (ETDEWEB)

    Hakkila, E.A.

    1978-10-01

    Conventional analytical methods applicable to the determination of thorium, uranium, and plutonium in feed, product, and waste streams from reprocessing thorium-based nuclear reactor fuels are reviewed. Separations methods of interest for these analyses are discussed. Recommendations concerning the applicability of various techniques to reprocessing samples are included. 15 tables, 218 references.

  15. New Twists and Turns for Actinide Chemistry: Organometallic Infinite Coordination Polymers of Thorium Diazide.

    Science.gov (United States)

    Monreal, Marisa J; Seaman, Lani A; Goff, George S; Michalczyk, Ryszard; Morris, David E; Scott, Brian L; Kiplinger, Jaqueline L

    2016-03-01

    Two organometallic 1D infinite coordination polymers and two organometallic monometallic complexes of thorium diazide have been synthesized and characterized. Steric control of these self-assembled arrays, which are dense in thorium and nitrogen, has also been demonstrated: infinite chains can be circumvented by using steric bulk either at the metallocene or with a donor ligand in the wedge. PMID:26865502

  16. On the development of fast breeder reactors and the use of thorium in Brazil

    International Nuclear Information System (INIS)

    This work presents a discussion on the possibility of construction of fast breeder reactors in Brazil. It is specially concerned with the use of thorium which is abundant in our country. The main advantages of this projects are: develop fuel and reactor technology in Brazil, increase thorium research, demonstrate the safety of LMFBR and promote its public acceptance. (A.C.A.S.)

  17. 78 FR 21352 - Update on Reimbursement for Costs of Remedial Action at Active Uranium and Thorium Processing Sites

    Science.gov (United States)

    2013-04-10

    ... on Reimbursement for Costs of Remedial Action at Active Uranium and Thorium Processing Sites AGENCY... reimbursement for cleanup work performed by licensees at eligible uranium and thorium processing sites in... licensees of eligible uranium and thorium processing sites. If licensees submit claims in FY 2013,...

  18. Development of a method for recovery of 233U from thorium oxalate cake in reconversion step of reprocessing of irradiated thorium rods

    International Nuclear Information System (INIS)

    A method is developed for the selective leaching of 233U from a thorium oxalate cake. The leaching capacity of ammonium carbonate and nitric acid have been investigated, showing that (NH4)2CO3 leads to higher recovery. The maximum leaching efficiency is obtained using 0.5% ammonium carbonate, with a minimal thorium pick-up. A uranium recovery of 94% is obtained after three consecutive contact experiments in carbonate media, with minimal thorium uptake in the leachate. This process was applied to an actual plant stream, allowing the reduction of the 233U α-activity from 5.64 to 0.3 μCi/g of thorium oxalate cake. (author)

  19. Towards the thorium fuel cycle with molten salt fast reactors

    International Nuclear Information System (INIS)

    Highlights: • Neutronic calculations for fast spectrum molten salt reactor. • Evaluation of the fissile matter to be used in such reactor as initial fissile load. • Capabilities to transmute transuranic elements. • Deployment scenarios of the Thorium fuel cycle. • Waste management optimization with molten salt fast reactor. - Abstract: There is currently a renewed interest in molten salt reactors, due to recent conceptual developments on fast neutron spectrum molten salt reactors (MSFRs) using fluoride salts. It has been recognized as a long term alternative to solid-fueled fast neutron systems with a unique potential (large negative temperature and void coefficients, lower fissile inventory, no initial criticality reserve, simplified fuel cycle, wastes reduction etc.) and is thus one of the reference reactors of the Generation IV International Forum. In the MSFR, the liquid fuel processing is part of the reactor where a small side stream of the molten salt is processed for fission product removal and then returned to the reactor. Because of this characteristic, the MSFR can operate with widely varying fuel compositions, so that the MSFR concept may use as initial fissile load, 233U or enriched uranium or also the transuranic elements currently produced by light water reactors. This paper addresses the characteristics of these different launching modes of the MSFR and the Thorium fuel cycle, in terms of safety, proliferation, breeding, and deployment capacities of these reactor configurations. To illustrate the deployment capacities of the MSFR concept, a French nuclear deployment scenario is finally presented, demonstrating that launching the Thorium fuel cycle is easily feasible while closing the current fuel cycle and optimizing the long-term waste management via stockpile incineration in MSRs

  20. Determination of rare earth elements, yttrium, uranium and thorium in ilmenite samples by ICP-MS

    International Nuclear Information System (INIS)

    Ilmenite is a principal mineral of titanium and is used mainly in the production of titanium dioxide pigment. Determination of trace elements in ilmenite samples constitutes a challenge to the analyst as the highly Iron-Titanium rich matrix poses a lot of problems, both during the sample dissolution stage as well as during the instrumental determination stage. Solution inductively coupled plasma mass spectrometry (ICP-MS) has emerged as a powerful and sensitive technique that has been successfully used for the accurate direct determination of several trace elements in geological materials. But, even with ICP-MS, direct determination of trace constituents in complex mineral matrices is extremely difficult because of the constraints on total dissolved salt (TDS) levels of sample solutions and other mass spectroscopic and non-mass spectroscopic interferences. Therefore, in the present work, the extent of interference on all rare-earth elements (REEs), yttrium, uranium and thorium due to the iron matrix has been assessed at a single set of operating conditions for different amounts of iron taken, using solutions of magnetite ore 'SARM 12' (containing 95.3% Fe2O3) and the accuracy of the results obtained have been evaluated. Some selected Indian ilmenite samples have been analysed by ICP-MS after sample dissolution using a mixture of hydrofluoric, hydrochloric and sulphuric acids and the values obtained compared with those obtained by ICP-OES after separation of the iron matrix. Though a number of international ilmenite reference materials are available, certified or even proposed values are available only for a very few elements in them. Two ilmenite reference materials (IGS 31 and SARM 59) have also been analysed by ICP-MS and usable values have been proposed in this paper. The % RSD for all the estimated elements varied from 3.0% to 15.0% at different concentration levels. (author)

  1. Fluorination of thorium oxide by ammonium bifluoride and its reduction to metal

    International Nuclear Information System (INIS)

    The fluorination of thoria (ThO2) with ammonium bifluoride, NH4HF2 to obtain oxygen free thorium fluoride is reported. It is interesting to note that the fluorination starts right from room temperature to form ammonium thorium fluoride intermediate. On heating, the intermediate decomposes to form pure ThF4. It was also seen that any unreacted ThO2 reacts with the ThF4 to form ThOF2. The oxygen free ThF4 produced was then reduced by calcium to form metallic thorium. The advantage in the process is that it can make thorium in bulk form which greatly reduces the issue of handling powders. However, as the process involves the melting of thorium, selection of suitable crucible becomes a key to its success. Yttria crucible appears to be a good choice. (author)

  2. Separation studies of uranium and thorium using tetra(2-ethylhexyl) diglycolamide (TEHDGA) as an extractant

    International Nuclear Information System (INIS)

    The extraction behavior of uranium, thorium and nitric acid has been investigated for the TEHDGA/isodecyl alcohol/n-dodecane solvent system. Conditional acid uptake constant (KH) of TEHDGA/n-dodecane and the ratio of TEHDGA to nitric acid were obtained as 1.72 and 1 : 0.96, respectively. The extracted species of uranium and thorium in the organic phase were found to be UO2(NO3)2 x 2TEHDGA and Th(NO3)4 x 2TEHDGA. A workable separation factor (DTh/DU) of the order of 300 was observed between thorium and uranium in the nitric acid range of 0.5M to 1.5M. Similar separation factor was also achieved at higher acidity when thorium was present in large concentration compared to uranium. These results indicate that TEHDGA solvent system could be a potential candidate for separation of thorium from uranium. (author)

  3. Recovery of thorium along with uranium 233 from Thorex waste solution employing Chitosan

    International Nuclear Information System (INIS)

    The low level waste solution, generated from Thorex process during the processing of U233, contains thorium along with traces of Th228 and U233. Chitosan, a natural bio-polymer derived from Chitin, was earlier used to recover the uranium and americium. The studies were extended to find out its thorium sorption characteristics. Chitosan exhibited very good absorption of thorium (350 mg/g). Chitosan was equilibrated directly with the low level waste solution at different pH after adjusting its pH, for 60 minutes with a Chitosan to aqueous ratio of 1:100 and the raffinates were filtered and analysed. The results showed more than 99% of thorium and U233 could be recovered by Chitosan between pH 4 and 5. Loaded thorium and uranium could be eluted from the Chitosan by 1M HNO3 quantitatively. (author)

  4. Potential of Melastoma malabathricum as bio-accumulator for uranium and thorium from soil

    Science.gov (United States)

    Saat, Ahmad; Kamsani, Ain Shaqina; Kamri, Wan Nur Aina Nadzira; Talib, Nur Hasyimah Mat; Wood, Ab Khalik; Hamzah, Zaini

    2015-04-01

    Uranium and Thorium are naturally occuring radionuclides. However, due to anthropogenic activities in some locations their concentrations in the soils could be elevated. This study explores the potential of Melastoma malabathricum (locally known as `pokok senduduk') as bio-accumulator of uranium and thorium from soils of three different study areas, namely former tin mining, industrial and residential/commercial areas in Peninsular Malaysia. The study found elevated concentrations of uranium and thorium in former tin mining soils as compared to natural abundance. However in industral and residential/commercial areas the concentrations are within the range of natural abundance. In terms of transfer factor (TF), in ex-mining areas TF > 1 for uranium in the leaf, stem and roots, indicating accumulation of uranium from soil. However for thorium TF uranium and thorium were observed. The results indicated the potential of Melastoma malabathricum to be used as bio-accumulatior of uranium, especially in areas of elevated concentration.

  5. Effect of mineral and organic fertilizers on uptake of uranium and thorium by cotton and wheat

    International Nuclear Information System (INIS)

    The effects of large applications of fertilizers on the uptake of uranium and thorium by cotton and wheat from soils containing small amounts of natural radionuclides were studied. The uranium content of cotton plant parts decreased by a factor of 2.9 and that of thorium by a factor of 3.8; the uptake of uranium in wheat grain was less than the control by a factor of 1.4 and that of thorium by a factor of 2.6. Complete mineral fertilizer had a greater effect on radionuclide uptake than individual applications of mineral nutrients. The smallest uptake of uranium and thorium by cotton resulted from combined use of complete mineral fertilizer and manure. Fertilizer application altered the relative amounts of water-soluble, exchangeable, acid-soluble and fixed forms of the radionuclides in the soil. Phosphorus fertilizers decreased the exchangeable thorium fraction by 20%, and, in combination with manure, by 40%

  6. Measurement of uranium and thorium in marine sediments

    International Nuclear Information System (INIS)

    Lakes, oceans and seas accumulate sediments. These sediments constitute a file of the last environmental conditions going up in some cases to thousands of years. In our study, we consulted this file by analyzing radioisotopes of Uranium and Thorium that are included in a carrot of marine sediment taken from the south of Mediterranean Sea. When we applied the technique developed by the maritime environment's laboratory of Monaco, we found spectra with bad resolutions. For this reason, the optimization of this protocol appeared necessary. (Author).

  7. Concentrations of Uranium,Thorium and Potassium in Sweden

    Energy Technology Data Exchange (ETDEWEB)

    Thunholm, Bo; Linden, Anders H.; Gustafsson, Bosse [Geological Survey of Sweden, Uppsala (Sweden)

    2005-04-01

    This report is largely a result of the Swedish contribution to an IAEA co-ordinated research programme (CRP) on the use of selected safety indicators in the assessment of radioactive waste disposal. The CRP was focusing on the assessment of the longterm safety of radioactive waste disposal by means of additional safety indicators based on data from natural systems with emphasis on description of existing data on radioactive elements and radionuclides. A major part of the work was focused on collecting data on geophysics as well as geochemistry and groundwater chemistry; mainly uranium (U), thorium (Th) and potassium (K). Data were interpreted resulting in maps and statistical description.

  8. Natural intake and excretion of thorium and uranium

    International Nuclear Information System (INIS)

    The natural content of the isotopes 238Th, 230Th and 232Th in faeces as well as 234U, 235U and 238U in drinking-water has been investigated by means of α-spectroscopy. The averaged total activity of thorium in faeces has been found to be 56,6 mBq per daily excretion, the activity of uranium in drinking water is reported to be 11.3 mBq/l. The results are in comparison with the existing data from Germany, but different to international suppositions as in UNSCEAR or ICRP 23. (orig.)

  9. Uranium, thorium and radium in soil and crops

    International Nuclear Information System (INIS)

    The distribution of the naturally occuring radionuclides uranium, thorium and radium in soil, plant material and drainage water was evaluated. The plant/soil concentration factors showed that very small fractions of the nuclides were available for the plants. The water/soil concentration factors were calculated; the nuclide content in drainage water generally indicated very low leaching rates. The distribution of the radionuclides was utilized with the aim to obtain reliable concentration factors which in turn could be used to calculate the transfer of nuclides within the agricultural ecosystem. Dose calculations were performed using plant/soil concentration factors based on geometric mean values. (authors)

  10. Fast reactor experiments with thorium at the PROTEUS facility

    International Nuclear Information System (INIS)

    The largescale utilization of thorium is usually linked to its introduction in fast breeder reactors and/or advanced converters. The present experiments were carried out in the zero-energy reactor facility, PROTEUS, at EIR. Six different configurations for the central fast test zone were considered in the current programme, the principal fuel/blanket materials used being in the form of rods of 15% PuO2/UO2, depleted UO2, ThO2 and Th-metal. For each configuration, measurements of the principal reaction rate ratios at the centre, as well as of reaction rate distributions across the test zone, were made. (Auth.)

  11. Determination of fluoride with thorium nitrate by catalytic titration

    International Nuclear Information System (INIS)

    Amperometry, constant-current potentiometry and spectrophotometry were used to follow the course of catalytic titrations of fluoride and silicofluoride with thorium nitrate. The hydrogen peroxide-iodide system was used as the indicator reaction. Titrations were performed in 50% ethanolic acetate buffer, pH 3.6. Amounts of 3.70 to 6.85 mg of ammonium fluoride, 5.53 to 10.79 mg of potassium fluoride and 4.34 to 8.41 mg of sodium silicofluoride were determined with a maximum average deviation of 0.9%. The results obtained are in good agreement with those of comparable methods. (author)

  12. Determination of natural uranium and thorium content by alpha spectrometry

    International Nuclear Information System (INIS)

    Alpha-spectrometry has been used to determine simultaneously the uranium and thorium content in solid samples as well as the equilibrium with their decay products. Samples require preparation for measurement only by milling in a disc mill, without additional chemical treatment. Instrumentation used consisted of a commercial large area Frisch grid ionisation chamber. At concentration levels of 100 ppm of U or Th, deviations from decay equilibrium were measured within ± 10%, with increasing error margins for smaller concentrations. The detection limits appear to depend primarily on the background count rates of the chamber. (author)

  13. Concentrations of Uranium,Thorium and Potassium in Sweden

    International Nuclear Information System (INIS)

    This report is largely a result of the Swedish contribution to an IAEA co-ordinated research programme (CRP) on the use of selected safety indicators in the assessment of radioactive waste disposal. The CRP was focusing on the assessment of the longterm safety of radioactive waste disposal by means of additional safety indicators based on data from natural systems with emphasis on description of existing data on radioactive elements and radionuclides. A major part of the work was focused on collecting data on geophysics as well as geochemistry and groundwater chemistry; mainly uranium (U), thorium (Th) and potassium (K). Data were interpreted resulting in maps and statistical description

  14. Conversion ratio in epithermal PWR, in thorium and uranium cycle

    International Nuclear Information System (INIS)

    Results obtained for the conversion ratio in PWR reactors with close lattices, operating in thorium and uranium cycles, are presented. The study of those reactors is done in an unitary fuel cell of the lattices with several ratios V sub(M)/V sub(F), considering only the equilibrium cycles and adopting a non-spatial depletion calculation model, aiming to simulate mass flux of reactor heavy elements in the reactor. The neutronic analysis and the cross sections generation are done with Hammer computer code, with one critical apreciation about the application of this code in epithermal systems and with modifications introduced in the library of basic data. (E.G.)

  15. Neutronic calculations for CANDU thorium systems using Monte Carlo techniques

    Science.gov (United States)

    Saldideh, M.; Shayesteh, M.; Eshghi, M.

    2014-08-01

    In this paper, we have investigated the prospects of exploiting the rich world thorium reserves using Canada Deuterium Uranium (CANDU) reactors. The analysis is performed using the Monte Carlo MCNP code in order to understand how much time the reactor is in criticality conduction. Four different fuel compositions have been selected for analysis. We have obtained the infinite multiplication factor, k∞, under full power operation of the reactor over 8 years. The neutronic flux distribution in the full core reactor has already been investigated.

  16. The Thorium Molten Salt Reactor Moving on from the MSBR

    CERN Document Server

    Mathieu, L; Brissot, R; Le Brun, C; Liatard, E; Loiseaux, J M; Méplan, O; Merle-Lucotte, E; Nuttin, A; Wilson, J; Garzenne, C; Lecarpentier, D; Walle, E

    2006-01-01

    A re-evaluation of the Molten Salt Breeder Reactor concept has revealed problems related to its safety and to the complexity of the reprocessing considered. A reflection is carried out anew in view of finding innovative solutions leading to the Thorium Molten Salt Reactor concept. Several main constraints are established and serve as guides to parametric evaluations. These then give an understanding of the influence of important core parameters on the reactor's operation. The aim of this paper is to discuss this vast research domain and to single out the Molten Salt Reactor configurations that deserve further evaluation.

  17. On thorium and plutonium cocrystallization with calcium oxalate

    International Nuclear Information System (INIS)

    Study of possibility of 239Pu and 234Th concentration from bone ashe (calcium phosphate) hydrochloric acid solutions by coprecipitation with nonisotopic medium (CaC2O4) for their further radiometry or alpha-spectrometry is carried out. Thorium and plutonium distribution coefficients in calcium oxalate precipitate - solution system, as well as coefficients of Th and Pu cocrystallization with CaC2O4 and cocrystallization type are determined. Possibility of Pu and Th concentration from bone tissue solutions is demonstrated on small oxalate amount containing 25% of Ca total amount in bone tissue

  18. Electrotransport of vanadium, niobium and tantalum in thorium

    International Nuclear Information System (INIS)

    The electrotransport behavior of vanadium, niobium and tantalum was measured in β(b.c.c.) thorium over the temperature range 1370-16650C. The concentration profiles of the solutes were measured using spark source mass spectrometry as the method of analysis. All three solutes migrated in the same direction as the electron flow. Vanadium was found to have the highest electric mobility, followed by niobium and tantalum. Values for the diffusivity and effective valence were also determined at each of four temperatures. (Auth.)

  19. Origin of Thorium/Uranium Variations in Carbonaceous Chondrites

    OpenAIRE

    Goreva, J. S.; Burnett, D. S.

    2000-01-01

    Thorium-, U-, and Pb-isotopic analyses of a wide variety of planetary materials show that Th/U ratio (by weight) varies from 3.5 to 4.2. It is generally believed that chondritic meteorites contain refractory lithophile elements in a relative proportions close to solar, i.e., CI chondrites [1]. Surprisingly, a number of analyses of different types of carbonaceous chondrites show a large (at least a factor of 3) scatter in Th/U measurements [2]. The widest spread in Th/U is observed in the most...

  20. Chemical Speciation of Thorium in Marine Biogenic Particulate Matter

    OpenAIRE

    Katsumi Hirose

    2004-01-01

    Concentrations of particulate thorium in seawater were determined together with the strong organic ligand (SOL) and uranium in particulate matter (PM). The concentrations of particulate Th in surface waters of the western North Pacific and the Sea of Japan ranged from 0.05 to 1.5 pM (1 x 10−12 M), and showed relatively large temporal and spatial variations. In order to chemically characterize the particulate Th in seawater, the relationship between particulate Th and SOL concentrations in sur...

  1. Configurational analysis of uranium-doped thorium dioxide

    Science.gov (United States)

    Shields, A. E.; Ruiz-Hernandez, S. E.; de Leeuw, N. H.

    2015-04-01

    While thorium dioxide is already used industrially in high temperature applications, more insight is needed about the behaviour of the material as part of a mixed-oxide (MOX) nuclear fuel, incorporating uranium. We have developed a new interatomic potential model, commensurate with a prominent existing UO2 potential, to conduct configurational analyses of uranium-doped ThO2 supercells. Using the GULP and Site Occupancy Disorder (SOD) computational codes, we have analysed the distribution of low concentrations of uranium in the bulk material, but have not observed the formation of uranium clusters or a single dominant configuration.

  2. Thorium occurrences in the Czech Republic and their mineralogy

    International Nuclear Information System (INIS)

    A short description and characteristics of several types of thorium mineralization in the Bohemian Massif are given: orthogneisses with 200 ppm Th (Moldanubicum), Permian volcanics in the Intra-Sudetic basin (U-Th-V, up to 450 ppm Th), REE-Th pegmatites (Moldanubicum), metasomatic (the Sudety Mts.) and Ordovician Ti-Zr-Th-REE paleo-placers (Saxothuringicum), Recent Ti-Zr-Th-REE-Nb placers (Luznice River, S Bohemia), vein type - Moldanubicum (Th-U). Reserves of 87 tons Th have been calculated in the Estimated Additional II category at Budisov (vein-type deposit in melanosyenites). (author)

  3. Photon attenuation properties of some thorium, uranium and plutonium compounds

    Energy Technology Data Exchange (ETDEWEB)

    Singh, V. P.; Badiger, N. M. [Karnatak University, Department of Physics, Dharwad-580003, Karnataka (India); Vega C, H. R., E-mail: kudphyvps@rediffmail.com [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas, Zac. (Mexico)

    2015-10-15

    Mass attenuation coefficients, effective atomic numbers, effective electron densities for nuclear materials; thorium, uranium and plutonium compounds have been studied. The photon attenuation properties for the compounds have been investigated for partial photon interaction processes by photoelectric effect, Compton scattering and pair production. The values of these parameters have been found to change with photon energy and interaction process. The variations of mass attenuation coefficients, effective atomic number and electron density with energy are shown graphically. Moreover, results have shown that these compounds are better shielding and suggesting smaller dimensions. The study would be useful for applications of these materials for gamma ray shielding requirement. (Author)

  4. Photon attenuation properties of some thorium, uranium and plutonium compounds

    International Nuclear Information System (INIS)

    Mass attenuation coefficients, effective atomic numbers, effective electron densities for nuclear materials; thorium, uranium and plutonium compounds have been studied. The photon attenuation properties for the compounds have been investigated for partial photon interaction processes by photoelectric effect, Compton scattering and pair production. The values of these parameters have been found to change with photon energy and interaction process. The variations of mass attenuation coefficients, effective atomic number and electron density with energy are shown graphically. Moreover, results have shown that these compounds are better shielding and suggesting smaller dimensions. The study would be useful for applications of these materials for gamma ray shielding requirement. (Author)

  5. Profile: American Indian/Alaska Native

    Science.gov (United States)

    ... Minority Population Profiles > American Indian/Alaska Native Profile: American Indian/Alaska Native Spotlight ACA Infographic for American Indians/ ... Program Circle of Life multimedia youth education program American Indian/Alaska Native Profile Great Plains Area Alaska Area ...

  6. Mechanism of thorium biosorption by the cells of the soil fungal isolate Geotrichum sp. dwc-1

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Congcong; Feng, Su [Sichuan Univ., Chengdu (China). Key Laboratory of Biological Resource and Ecological Environment; Li, Xiaolong [Sichuan Univ., Chengdu (China). Key Laboratory of Radiation Physics and Technology; and others

    2014-04-01

    In order to understand the impact of microorganisms on the fate of thorium in soils, we investigated the thorium biosorption behavior and the corresponding mechanisms by the cells of Geotrichum sp. dwc-1, one of the dominant species of fungal group isolated from 3.5 m depth soil layer in Southwest China. It was observed that fast thorium adsorption onto cells of G. sp. dwc-1 could take place, with a high distribution coefficient K{sub d} (0.93 mL/mg) obtained, when Geotrichum sp. dwc-1and thorium concentrations were 5 g/L and 10 mg/L, respectively. The thorium biosorption behavior was dependent on the pH value, and the lower pH could disrupt cell membrane of G. sp. dwc-1. At pH 1, thorium was accumulated in the cytoplasmic region of the cells. When pH was higher than 1, thorium was adsorbed on the cell surface of G. sp. dwc-1, like in periplasmic region or in the outer membrane. FTIR study combined with biosorption experiments further indicated that the thorium distribution and binding behavior on cell surface were associated with amino, hydroxyl groups and phosphate or sulphur functional groups, and might also be governed by electrostatic interaction. Moreover, PIXE and EPBS showed that ion-exchange mechanism contributed to the thorium biosorption process, in which the tetravalent thorium ions replaced smaller counter-ions (K{sup +}, Ca{sup 2+} and Fe{sup 3+}) occuring on the cell surface. (orig.)

  7. Comparison of the radiological hazard of thorium and uranium spent fuels from VVER-1000 reactor

    International Nuclear Information System (INIS)

    Thorium fuel is considered as a viable alternative to the uranium fuel used in the current generation of nuclear power plants. Switch from uranium to thorium means a complete change of composition of the spent nuclear fuel produced as a result of the fuel depletion during operation of a reactor. If the Th–U fuel cycle is implemented, production of minor actinides in the spent fuel is negligible. This is favourable for the spent fuel disposal. On the other hand, thorium fuel utilisation is connected with production of 232U, which decays via several alpha decays into a strong gamma emitter 208Tl. Presence of this nuclide might complicate manipulations with the irradiated thorium fuel. Monte-Carlo computation code MCNPX can be used to simulate thorium fuel depletion in a VVER-1000 reactor. The calculated actinide composition will be analysed and dose rate from produced gamma radiation will be calculated. The results will be compared to the reference uranium fuel. Dependence of the dose rate on time of decay after the end of irradiation in the reactor will be analysed. This study will compare the radiological hazard of the spent thorium and uranium fuel handling. - Highlights: • Spent thorium and uranium fuel composition in VVER-1000 was calculated by MCNPX. • Important nuclide 208Tl is not included in the thorium spent fuel composition. • There are large differences in activity of actinides between spent Th and U fuels. • Dose rate from spent thorium fuel is increasing during 50 years of decay. • 208Tl in spent thorium fuel increased the dose rate by several percent

  8. Thorium utilization as a Pu-burner: proposal of Plutonium-Thorium Mixed Oxide (PT-MOX) Project

    International Nuclear Information System (INIS)

    In this paper, a Pu-Th mixed oxide (PT-MOX) project is proposed for a thorium utilization and a plutonium burning. None of plutonium can be newly produced from PT-MOX fuel, and the plutonium mass of about 1 ton can be consumed with one reactor (total heavy metal assumed: 100 tons) for 1 year. In order to consume plutonium produced from usual Light Water Reactor, it should be better to operate one PT-MOX reactor for three to five Light Water Reactors. (author)

  9. Indian Development vs Sino-Indian Relations

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    @@ A deep, lasting, great friendship can be traced back to over two millennia ago between two close neighbors, the initiators of the world-famous Five Principles of Peaceful Co-existence with its 50th anniversary just commemorated this year. Historically, China benefited much from learning the brilliant Indian culture. Today, the two major Asian countries are learning from each other in their rapid economic growth. The rise of China and India, closer ties between the two, will definitely exert a significant impact on the Asia-Pacific region and the broader world in the days ahead.

  10. Indian Ocean Traffic: Introduction

    Directory of Open Access Journals (Sweden)

    Lola Sharon Davidson

    2012-06-01

    Full Text Available Like the Mediterranean, the Indian Ocean has been a privileged site of cross-cultural contact since ancient times. In this special issue, our contributors track disparate movements of people and ideas around the Indian Ocean region and explore the cultural implications of these contacts and their role in processes that we would come to call transnationalization and globalisation. The nation is a relatively recent phenomenon anywhere on the globe, and in many countries around the Indian Ocean it was a product of colonisation and independence. So the processes of exchange, migration and cultural influence going on there for many centuries were mostly based on the economics of goods and trade routes, rather than on national identity and state policy.

  11. Hamlin Garland and the Indian

    Science.gov (United States)

    Underhill, Lonnie E.

    1974-01-01

    Written to stimulate interest in an evaluation of Hamlin Garland's total production of work on the American Indian, this article suggests a reevaluation of some of Garland's work in light of the current interest in American Indian studies. (JC)

  12. Dietary intake of naturally occurring radionuclides from thorium series, uranium series and potassium-40 in high background radiation areas of Manavalakurichi, Tamil Nadu

    International Nuclear Information System (INIS)

    Natural background radiation is a major source of human exposure to radiation. The source of background radiation is due to monazite containing naturally occurring radionuclides like thorium and uranium. These natural radionuclides are found in all environmental matrices like rocks, soil, water, and dietary sources. The intake of natural radionuclides to public would occur in ingestion pathway via dietary sources. The present study aims to evaluate the natural radionuclides in dietary sources from Manavalakurichi region, which is a High Background Radiation Area's (HBRA's) in Tamil Nadu. The natural radionuclides such as Uranium (238U and 234U), Radium (226Ra and 228Ra), Polonium (210Po) and Potassium (40K) in the dietary products were analyzed in various dietary sources and computed the ingestion dose for different age group of public residing in and around Manavalakurichi. The study can act as existing data for Indian population living in the high radiation background areas

  13. Extraction of trace thorium from hydrochloric acid media by 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone

    Institute of Scientific and Technical Information of China (English)

    YANG Wei-Fan; YUAN Shuang-Gui; XU Yan-Bing; XIAO Yong-Hou; XIONG Bing

    2003-01-01

    The paper describes the solvent extraction of trace thorium from hydrochloric acid media by1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (PMBP) using a radioactive tracer technique. The percent extraction ofthorium was studied as a function of acidity, PMBP concentration and equilibrium time. The back-extraction behaviorof thorium from the organic phase was also tested. Separation of thorium was performed from fission products pro-duced in 14 MeV neutron bombardment of natural uranium by employing the PMBP extraction procedure. Thegamma-ray spectra of the separated thorium fractions show that thorium can be separated from most of fission prod-ucts and a large amount of uranium.

  14. Thermal Hydraulic Analysis Of Thorium-Based Annular Fuel Assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Han, Kyu Hyun [Korea Institute of Nuclear Safety, 19, Guseong-dong, Yuseong-gu, Daejeon, 305-338 (Korea, Republic of)

    2008-07-01

    Thermal hydraulic characteristics of thorium-based fuel assemblies loaded with annular seed pins have been analyzed using AMAP combined with MATRA, and compared with those of the existing thorium-based assemblies. MATRA and AMAP showed good agreements for the pressure drops at the internal sub-channels. The pressure drop generally increased in the cases of the assemblies loaded with annular seed pins due to the larger wetted perimeter, but an exception existed. In the inner sub-channels of the seed pins, mass fluxes were high due to the grid form losses in the outer sub-channels. About 43% of the heat generated from the seed pin flowed into the inner sub-channel and the rest into the outer sub-channel, which implies the inner to outer wall heat flux ratio was approximately 1.2. The maximum temperatures of the annular seed pins were slightly above 500 deg. C. The MDNBRs of the assemblies loaded with annular seed pins were higher than those of the existing assemblies. Due to the fact that inter-channel mixing cannot occur in the inner sub-channels, temperatures and enthalpies were higher in the inner sub-channels. (author)

  15. Thermal Hydraulic Analysis Of Thorium-Based Annular Fuel Assemblies

    International Nuclear Information System (INIS)

    Thermal hydraulic characteristics of thorium-based fuel assemblies loaded with annular seed pins have been analyzed using AMAP combined with MATRA, and compared with those of the existing thorium-based assemblies. MATRA and AMAP showed good agreements for the pressure drops at the internal sub-channels. The pressure drop generally increased in the cases of the assemblies loaded with annular seed pins due to the larger wetted perimeter, but an exception existed. In the inner sub-channels of the seed pins, mass fluxes were high due to the grid form losses in the outer sub-channels. About 43% of the heat generated from the seed pin flowed into the inner sub-channel and the rest into the outer sub-channel, which implies the inner to outer wall heat flux ratio was approximately 1.2. The maximum temperatures of the annular seed pins were slightly above 500 deg. C. The MDNBRs of the assemblies loaded with annular seed pins were higher than those of the existing assemblies. Due to the fact that inter-channel mixing cannot occur in the inner sub-channels, temperatures and enthalpies were higher in the inner sub-channels. (author)

  16. Promises and Challenges of Thorium Implementation for Transuranic Transmutation - 13550

    Energy Technology Data Exchange (ETDEWEB)

    Franceschini, F.; Lahoda, E.; Wenner, M. [Westinghouse Electric Company LLC, Cranberry Township, PA (United States); Lindley, B. [University of Cambridge (United Kingdom); Fiorina, C. [Polytechnic of Milan (Italy); Phillips, C. [Energy Solutions, Richland, WA (United States)

    2013-07-01

    This paper focuses on the challenges of implementing a thorium fuel cycle for recycle and transmutation of long-lived actinide components from used nuclear fuel. A multi-stage reactor system is proposed; the first stage consists of current UO{sub 2} once-through LWRs supplying transuranic isotopes that are continuously recycled and burned in second stage reactors in either a uranium (U) or thorium (Th) carrier. The second stage reactors considered for the analysis are Reduced Moderation Pressurized Water Reactors (RMPWRs), reconfigured from current PWR core designs, and Fast Reactors (FRs) with a burner core design. While both RMPWRs and FRs can in principle be employed, each reactor and associated technology has pros and cons. FRs have unmatched flexibility and transmutation efficiency. RMPWRs have higher fuel manufacturing and reprocessing requirements, but may represent a cheaper solution and the opportunity for a shorter time to licensing and deployment. All options require substantial developments in manufacturing, due to the high radiation field, and reprocessing, due to the very high actinide recovery ratio to elicit the claimed radiotoxicity reduction. Th reduces the number of transmutation reactors, and is required to enable a viable RMPWR design, but presents additional challenges on manufacturing and reprocessing. The tradeoff between the various options does not make the choice obvious. Moreover, without an overarching supporting policy in place, the costly and challenging technologies required inherently discourage industrialization of any transmutation scheme, regardless of the adoption of U or Th. (authors)

  17. Thorium fuel cycle studies: fuel fabrication process and cost estimation

    International Nuclear Information System (INIS)

    Early in 1976 a study was made to assess the relative economics and fuel utilization of thorium and uranium fuel cycles in various types of reactors. It was to be completed in approximately two months, so all component parts had to be developed in a short time with a high degree of dependence on existing information. One of the components required for the study was a consistent set of relatively accurate fuel fabrication costs for the various reactor-fuel combinations. A report documents the rationale used in generating these cost estimates and presents in some detail the basis and methodology employed. Since three types of thermal flux reactors (LWR, HWR, and HTGR) and two types of fast flux reactors (liquid metal and gas cooled) together with three fuel forms (oxides, carbides, and metal) were included in the study with various combinations of the fissionable metals U, Th, and Pu, it was necessary to define a methodology that would permit a rapid relative estimate for each case. Existing cost studies were chosen for a Light-Water Reactor with low-enriched uranium fuel and for a High-Temperature Gas-Cooled Reactor with highly enriched uranium and thorium fuel as the reference cases which could be compared with other reactor-fuel combinations

  18. Decommissioning and rehabilitation of uranium and thorium production facilities

    International Nuclear Information System (INIS)

    The use of nuclear energy for military as well as for peaceful purposes was and remains closely connected with the mining and processing of uranium ore and, to a lesser extent, of thorium ore. Mining and processing of radioactive ores are characterised by the generation of huge amounts of radioactive residues, massive impacts upon ecosystems, landscape reshaping (or devastation in some places), and the monostructural socio-economic orientation of human settlement areas. However, a great number of the mines and mills commissioned during the cold war have been already closed, either for deposits being depleted of economically recoverable resources or on political grounds. The specifics of uranium/thorium mining and milling make high demands on the decommissioning and rehabilitation of the facilities which in addition to radiological aspects would have to address issues such as water pollution control and soil conservation, future site re-use, landscaping, and infrastructure development. The present paper gives an overview of the state of decommissioning and rehabilitation. Radiological specifics and their integration into the decommissioning and rehabilitation management are demonstrated for the rehabilitation of uranium mining legacies in Saxony and Thuringia. (orig.)

  19. Radiotoxicity Characterization of Multi-Recycled Thorium Fuel - 12394

    International Nuclear Information System (INIS)

    As described in companion papers, Westinghouse is proposing the implementation of a thorium based fuel cycle to burn the transuranic (TRU) contained in the used nuclear fuel. The potential of thorium as a TRU burner is described in another paper presented at this conference. This paper analyzes the long-term impact of thorium on the front-end and backend of the fuel cycle. This is accomplished by an assessment of the isotopic make-up of Th in a closed cycle and its impact on representative metrics, such as radiotoxicity, decay heat and gamma heat. The behavior in both thermal and fast neutron energy ranges has been investigated. Irradiation in a Th fuel PWR has been assumed as representative of the thermal range, while a Th fuel fast reactor (FR) has been employed to characterize the behavior in the high-energy range. A comparison with a U-fuel closed-cycle FR has been undertaken in an attempt of a more comprehensive evaluation of each cycle's long-term potential. As the Th fuel undergoes multiple cycles of irradiation, the isotopic composition of the recycled fuel changes. Minor Th isotopes are produced; U-232 and Pa-231 build up; the U vector gradually shifts towards increasing amounts of U-234, U-235 etc., eventually leading to the production of non negligible amounts of TRU isotopes, especially Pu-238. The impact of the recycled fuel isotopic makeup on the in-core behavior is mild, and for some aspects beneficial, i.e. the reactivity swing during irradiation is reduced as the fertile characteristics of the fuel increase. On the other hand, the front and the back-end of the fuel cycle are negatively affected due to the presence of Th-228 and U-232 and the build-up of higher actinides (Pu-238 etc.). The presence of U-232 can also be seen as advantageous as it represents an obstacle to potential proliferators. Notwithstanding the increase in the short-term radiotoxicity and decay heat in the multi-recycled fuel, the Th closed cycle has some potentially substantial

  20. Mortality among male workers at a thorium-processing plant

    International Nuclear Information System (INIS)

    Mortality is described in a cohort of 3039 men who were employed between 1940 and 1973 at a company involved in the production of thorium and rare earth chemicals from monazite sand. The standardized mortality ratio (SMR) for all causes was 1.05. SMR's were high for cancers of the lung (1,44), rectum (1.90), and pancreas (2.01), and for motor vehicle accidents (1.64). A subgroup of 592 men who worked for one year or longer in selected jobs (laborer, operator, maintenance) was followed up more intensively. SMR's were high for both lung cancer (1.62; 95% CL = 0.78 and 2.98) and pancreatic cancer (4.01; 95% CL = 1.30 and 9.34). The higher proportion of smokers in this subgroup relative to US males could have explained at least part of the excess mortality from lung cancer. Continued follow-up of the cohort in morbidity and mortality studies is needed to evaluate further these possible long-term effects of exposure to radioactivity and chemicals in the thorium extraction process

  1. Accelerator molten-salt breeding and thorium fuel cycle

    International Nuclear Information System (INIS)

    The recent efforts at the development of fission energy utilization have not been successful in establishing fully rational technology. A new philosophy should be established on the basis of the following three principles: (1) thorium utilization, (2) molten-salt fuel concept, and (3) separation of fissile-breeding and power-generating functions. Such philosophy is called 'Thorium Molten-Salt Nuclear Energy Synergetics [THORIMS-NES]'. The present report first addresses the establishment of 233U breeding fuel cycle, focusing on major features of the Breeding and Chemical Processing Centers and a small molten-salt power station (called FUJI-II). The development of fissile producing breeders is discussed in relation to accelerator molten-salt breeder (AMSB), impact fusion molten-salt breeder, and inertial-confined fusion hybrid molten-salt breeder. Features of the accelerator molten-salt breeder are described, focusing on technical problems with accelerator breeders (or spallators), design principle of the accelerator molten-salt breeder, selection of molten salt compositions, and nuclear- and reactor-chemical aspects of AMSB. Discussion is also made of further research and development efforts required in the future for AMSB. (N.K.)

  2. Neutron activation analysis of airborne thorium liberated during welding operations

    Energy Technology Data Exchange (ETDEWEB)

    Glasgow, D.C.; Robinson, L.; Janjovic, J.T.

    1996-02-01

    Typically, reactive metals such as aluminum are welded using a thoriated tungsten welding electrode which is attached to a source of argon gas such that the local atmosphere around the weld is inert. The metal is heated by the arc formed between the electrode and the grounded component to be welded. During this process, some of the electrode is vaporized in the arc and is potentially liberated to the surrounding air. This situation may result in a hazardous airborne thorium level. Because the electrode is consumed during welding, the electrode tip must be repeatedly dressed by grinding the tip to a fine point so that the optimal welding conditions are maintained. These grinding activities may also release thorium to the air. Data generated in the 1950s suggested that these electrodes posed no significant health hazard and seemed to justify their exemption from licensing requirements for source material. Since that time, other studies have been performed and present conflicting results as to the level of risk. Values both above and below the health protection limit in use in the United States, have been reported in the literature recently. This study is being undertaken to provide additional data which may be useful in evaluating both the chemical toxicity risk and radiological dose assessment criteria associated with thoriated tungsten welding operations.

  3. Supercritical fluid extraction of uranium and thorium employing dialkyl amides

    International Nuclear Information System (INIS)

    Extraction and purification of actinides from different matrices is of utmost importance to the nuclear industry. In recent decades, supercritical fluid extraction (SFE) has emerged as a promising alternative to solvent extraction owing to its inherent potential of minimization of liquid waste generation. N,N-dialkyl aliphatic amides have been proposed to be an alternative to TBP in the reprocessing of spent nuclear fuel due to several attractive features like innocuous nature of degradation products (mainly carboxylic acids/ amines), possibility of complete incineration of the used extractant leading to reduction in volume of secondary waste. Also, physico-chemical properties of this class of extractants can be tuned by the judicious choice of alkyl groups. In the present work, N,N-dialkyl aliphatic amides with varying alkyl groups viz. N,N-dibutyl-2-ethylhexanamide (DBEHA), N,N-dibutyl-3,3-dimethylbutanamide (DBDMBA), N,N-dihexyloctanamide (DHOA), N,N-disecbutylpentamide (DBPA), N,N-dibutyloctanamide (DBOA), have been evaluated for supercritical fluid extraction (SFE) of uranium and thorium from nitric acid medium as well as tissue paper matrix. Amides were obtained from Department of Chemistry, Delhi University and were used as such. This fact could be exploited for separation of thorium and uranium

  4. Determination of thorium and uranium particles in monazite airborne

    International Nuclear Information System (INIS)

    The work is the determination of the Mass Median Aerodynamic Diameter of Airborne particles of Th and U, produced during the milling of monazite in Monozite Sand Plants. The air samples was collected using a Cascade Impactor from Delron DCI-6 with a flux of 12,5 1/min and cut-off diametes of 0,5, 1,0, 4,0, 8,0 and 16,0 μm. Each stage of the cascate impactor was analysed by measuring the X rays induced in collision with 2 MeV protons acellereted by a 4 MV Van de Graaff acceletor located at University Catolic, PUC, RJ. The MMAD found for Th and U was of 1,15 μm with a geometric standard desviation of 2,0. Take in acount that there are more thorium than uranium in the brazilian monazite, and the 232Th 238U are thr principal isotopes at the Th and U natural radioative decay series, we considered the mass and the activity distribution as equal. The mean concentration of Th (17,0 Bq/m3) record in the air was 42% above 3/10 of international limit for concentration of oxides of thorium in the air, while the concentration of U remaind below 1/10 of the limit for concentration of U3O8 in the air. (author)

  5. Core design for thorium-uranium breeding recycle in PWRs

    International Nuclear Information System (INIS)

    Two kinds of mixed core designs were investigated in this study respectively with partially PuThOX (plutonium-thorium mixed oxide) and U3ThOX (reactor grade 233U-thorium mixed oxide) loading on the basis of reference full UOX (uranium-oxide) equilibrium-cycle core design. In UOX/U3ThOX mixed core/ U3ThOX fuel assemblies stay in-core for 6 cycles of which average cycle length is 5 EFPD longer than that of reference full UOX core. Compared with initial load, the fissile material inventory in U3ThOX fuel increased by 7% via 1 year cooling after discharge. Furthermore, the fuel management scheme of UOX/MOX (plutonium-uranium mixed oxide) mixed core was designed for comparison. The results show that: 1) Mixed core with PuThOX loading has similar impacts as MOX on several neutronic characteristics, such as reduced differential boron worth, reduced control rod worth, higher critical boron concentration, more negative moderator temperature coefficient, reduced shutdown margin and larger Doppler power defects; 2) mixed core with U3ThOX loading has no distinct impacts on neutronic characteristics compared with reference full UOX core. (authors)

  6. Thorium fuel cycle studies: fuel fabrication process and cost estimation

    Energy Technology Data Exchange (ETDEWEB)

    Olsen, A.R.

    1979-09-01

    Early in 1976 a study was made to assess the relative economics and fuel utilization of thorium and uranium fuel cycles in various types of reactors. It was to be completed in approximately two months, so all component parts had to be developed in a short time with a high degree of dependence on existing information. One of the components required for the study was a consistent set of relatively accurate fuel fabrication costs for the various reactor-fuel combinations. A report documents the rationale used in generating these cost estimates and presents in some detail the basis and methodology employed. Since three types of thermal flux reactors (LWR, HWR, and HTGR) and two types of fast flux reactors (liquid metal and gas cooled) together with three fuel forms (oxides, carbides, and metal) were included in the study with various combinations of the fissionable metals U, Th, and Pu, it was necessary to define a methodology that would permit a rapid relative estimate for each case. Existing cost studies were chosen for a Light-Water Reactor with low-enriched uranium fuel and for a High-Temperature Gas-Cooled Reactor with highly enriched uranium and thorium fuel as the reference cases which could be compared with other reactor-fuel combinations.

  7. A study of pulse columns for thorium fuel reprocessing

    International Nuclear Information System (INIS)

    Two 5 m pulse columns with the same cartridge geometries are installed to investigate the performance. The characteristic differences of the aqueous continous and the organic continuous columns were investigated experimentally. A ternary system of 30% TBP in dodecane-acetic acid-water was adopted for the mass-transfer study. It was concluded that the overall mass-transfer coefficient was independent of whether the mass-transfer is from the dispersed to the continuous phase or from the continuous to the dispersed phase. Thorium nitrate was extracted and reextracted using both modes of operation. Both HETS and HTU were obtained. The aqueous continuous column gave much shorter HTU than the organic continuous column. In reextraction the organic continuous column gave shorter HTU. The Thorex-processes for uranium and thorium co-extraction, co-stripping, and partitioning were studied. Both acid feed solution and acid deficiend feed solution were investigated. The concentration profiles along the column height were obtained. The data were analysed with McCABE-THIELE diagrams to evaluate HETS. (orig./HP)

  8. Promises and Challenges of Thorium Implementation for Transuranic Transmutation - 13550

    International Nuclear Information System (INIS)

    This paper focuses on the challenges of implementing a thorium fuel cycle for recycle and transmutation of long-lived actinide components from used nuclear fuel. A multi-stage reactor system is proposed; the first stage consists of current UO2 once-through LWRs supplying transuranic isotopes that are continuously recycled and burned in second stage reactors in either a uranium (U) or thorium (Th) carrier. The second stage reactors considered for the analysis are Reduced Moderation Pressurized Water Reactors (RMPWRs), reconfigured from current PWR core designs, and Fast Reactors (FRs) with a burner core design. While both RMPWRs and FRs can in principle be employed, each reactor and associated technology has pros and cons. FRs have unmatched flexibility and transmutation efficiency. RMPWRs have higher fuel manufacturing and reprocessing requirements, but may represent a cheaper solution and the opportunity for a shorter time to licensing and deployment. All options require substantial developments in manufacturing, due to the high radiation field, and reprocessing, due to the very high actinide recovery ratio to elicit the claimed radiotoxicity reduction. Th reduces the number of transmutation reactors, and is required to enable a viable RMPWR design, but presents additional challenges on manufacturing and reprocessing. The tradeoff between the various options does not make the choice obvious. Moreover, without an overarching supporting policy in place, the costly and challenging technologies required inherently discourage industrialization of any transmutation scheme, regardless of the adoption of U or Th. (authors)

  9. Determination of 131I and thorium in urine

    International Nuclear Information System (INIS)

    Methods for the determination of 131I and Thorium in urine have been developed taking into account the monitoring needs for people who handle with these radioisotopes. The method for determining 131I is based in the use of silver chloride to separate iodine by precipitation from the sample; the detection was carried out in a Nal (Tl) well type scintillator connected to a single channel analyser. This method has the following advantages; it is easy and relatively fast as well as selective, showing a separation yield higher than 80%. Thorium in urine was determined by colorimetry after the mineralization of the sample using nitric acid, and sulphuric acid, and then oxygen peroxide. The chromophore reagent used was Thoron (disodium salt of 2-(2-hydroxy-3,6-disulfo-l-naphthylazo) benzenearsonic acid).The absorbance was measured in a spectro colorimeter at a fixed wavelength (530 nm). The method proved to be simple allowing a separation yield of about 80%. The most representative sample for a monitoring program in a 131I production laboratory has been established. The 131I concentration in urine of individuals with chronic contamination have also been measured; an interpretation of these results is discussed. (author)

  10. Conceptual design of a commercial accelerator driven thorium reactor

    International Nuclear Information System (INIS)

    This paper describes the substantial work done in underpinning and developing the concept design for a commercial 600 MWe, accelerator driven, thorium fuelled, lead cooled, power producing, fast reactor. The Accelerator Driven Thorium Reactor (ADTR TM) has been derived from original work by Carlo Rubbia. Over the period 2007 to 2009 Aker Solutions commissioned this concept design work and, in close collaboration with Rubbia, developed the physics, engineering and business model. Much has been published about the Energy Amplifier concept and accelerator driven systems. This paper concentrates on the unique physics developed during the concept study of the ADTR TM power station and the progress made in engineering and design of the system. Particular attention is paid to where the concept design has moved significantly beyond published material. Description of challenges presented for the engineering and safety of a commercial system and how they will be addressed is included. This covers the defining system parameters, accelerator sizing, core and fuel design issues and, perhaps most importantly, reactivity control. The paper concludes that the work undertaken supports the technical viability of the ADTR TM power station. Several unique features of the reactor mean that it can be deployed in countries with aspirations to gain benefit from nuclear power and, at 600 MWe, it fits a size gap for less mature grid systems. It can provide a useful complement to Generation III, III+ and IV systems through its ability to consume actinides whilst at the same time providing useful power. (authors)

  11. Electrodeposition of uranium and thorium onto small platinum electrodes

    Science.gov (United States)

    Reichenberger, Michael A.; Ito, Takashi; Ugorowski, Philip B.; Montag, Benjamin W.; Stevenson, Sarah R.; Nichols, Daniel M.; McGregor, Douglas S.

    2016-03-01

    Preparation of thin U- and Th-coated 0.3 mm diameter Pt working electrodes by the cyclic potential sweep method is described. Uranyl- and thorium hydroxide layers were electrodeposited from ethanol solutions containing 0.02 M natural uranyl and 0.02 M natural thorium nitrate, each with 3.6 M ammonium nitrate. The cell for electrodeposition was specially developed in order to accommodate the small working electrodes for this research by including a working electrode probe, 3-D translation stage, and microscope. The source material deposition was analyzed using digital microscopy and scanning electron microscopy, and confirmed using x-ray fluorescence measurements. The appropriate potential range for electrodeposition was determined to be -0.62 V to -0.64 V for a 0.3 mm diameter Pt working electrode placed 1 cm from the counter electrode. Smooth, uniform deposition was observed near the central region of the working electrode, while surface cracking and crystalline formations were found near the edge of the working electrode. The final procedure for sample substrate preparation, electrolytic solution preparation and electrodeposition are described.

  12. Thorium (IV) toxicity of green microalgae from Scenedesmus and Monoraphidium genera

    International Nuclear Information System (INIS)

    The toxicity of thorium by two green microalgae species, Monoraphidium sp. and Scenedesmus sp was studied. During the toxicity tests, the microalgae cultures were inoculated in ASM-I culture medium in the presence and absence of thorium (cultures at pH 8.0 and 6.0 in the absence of thorium, - control - and at pH 6.0 for thorium concentrations ranging from 0.5 to 100.0 mg/L Th). Its effect was monitored by direct counting on Fuchs-Rosenthal chamber and with the help of software developed by the group during the experiments. The difference in pH value in the culture medium did not affect the growth of the microalgae, and pH 6.0 was chosen as a reference in order not to compromise solubility and speciation of thorium in solution. The toxicity of the metal over the species was observed just for thorium concentrations over 50.0 mg/L. A Monoraphidium sp. culture containing 6.25x105 microorganisms/mL reached a final concentration of 5.52x107 microorganisms/mL in the presence of thorium in the concentration of 10.0 mg/L. If we consider the 100.0 ppm thorium solution reached a final concentration of 8.57x106 microorganisms/mL. Control tests indicated a final concentration of 2.51x107 microorganisms/mL at the end of the growth. Scenedesmus sp. cells proved to be more resistant to the presence of thorium in solution. Low concentrations of the radionuclide favored the growth of these microalgae. A culture containing 7.65x105 microorganisms/mL reached a final concentration of 2.25x106 microorganisms/mL, in the absence of thorium in the medium. Toxicological tests indicated a final culture concentration of 5.87x106 microorganisms/mL in the presence of 0.5 mg/L thorium. The software used for comparison of direct count method proved to be very useful for the improvement of accuracy of the results obtained and a decrease in the uncertainty in counting. Beyond these advantages it also allowed recording of the data. From the present results one can conclude, that the presence of

  13. The Indian in American History.

    Science.gov (United States)

    Vogel, Virgil J.

    The treatment of American Indians is discussed historically with reference to the 4 principal methods used to create or perpetuate false impressions: obliteration, defamation, disembodiment, and disparagement. Indian contributions to American civilization are cited in contrast with historical references to Indians in textbooks. The author suggests…

  14. 78 FR 54670 - Indian Gaming

    Science.gov (United States)

    2013-09-05

    ... Bureau of Indian Affairs Indian Gaming AGENCY: Bureau of Indian Affairs, Interior. ACTION: Notice of extension of Tribal--State Class III Gaming Compact. SUMMARY: This publishes notice of the Extension of the Class III gaming compact between the Yankton Sioux Tribe and the State of South Dakota. DATES:...

  15. 76 FR 49505 - Indian Gaming

    Science.gov (United States)

    2011-08-10

    ... Bureau of Indian Affairs Indian Gaming AGENCY: Bureau of Indian Affairs, Interior. ACTION: Notice of Tribal-State Class III Gaming Compact taking effect. SUMMARY: This publishes notice of the Tribal-State... Gaming, Office of the Deputy Assistant Secretary--Policy and Economic Development, Washington, DC...

  16. 78 FR 17428 - Indian Gaming

    Science.gov (United States)

    2013-03-21

    ... Bureau of Indian Affairs Indian Gaming AGENCY: Bureau of Indian Affairs, Interior. ACTION: Notice of Approved Tribal-State Class III Gaming Compact. SUMMARY: This notice publishes the approval of the Class III Tribal- State Gaming Compact between the Pyramid Lake Paiute Tribe and the State of...

  17. 77 FR 30550 - Indian Gaming

    Science.gov (United States)

    2012-05-23

    ... of Approval in the Federal Register on February 23, 2010 (47 FR 44678). This agreement allows for the... Bureau of Indian Affairs Indian Gaming AGENCY: Bureau of Indian Affairs, Interior. ACTION: Notice of Approved Tribal--State Class III Gaming Compact. SUMMARY: This notice publishes approval by the...

  18. 77 FR 41200 - Indian Gaming

    Science.gov (United States)

    2012-07-12

    ... Bureau of Indian Affairs Indian Gaming AGENCY: Bureau of Indian Affairs, Interior. ACTION: Notice of Approved Tribal--State Class III Gaming Compact. SUMMARY: This notice publishes approval by the Department of an extension to the Class III Gaming Compact between the State of California and the...

  19. 78 FR 62649 - Indian Gaming

    Science.gov (United States)

    2013-10-22

    ... Bureau of Indian Affairs Indian Gaming AGENCY: Bureau of Indian Affairs, Interior. ACTION: Notice of Tribal-State Class III Gaming Compact taking effect. SUMMARY: This notice publishes the Class III Gaming... Gaming, Office of the Deputy Assistant Secretary--Policy and Economic Development, Washington, DC...

  20. 77 FR 5566 - Indian Gaming

    Science.gov (United States)

    2012-02-03

    ... Bureau of Indian Affairs Indian Gaming AGENCY: Bureau of Indian Affairs, Interior. ACTION: Notice of Tribal--State Class III Gaming Compact Taking Effect. SUMMARY: This publishes notice of the Tribal-State... Gaming, Office of the Deputy Assistant Secretary--Policy and Economic Development, Washington, DC...

  1. 78 FR 62650 - Indian Gaming

    Science.gov (United States)

    2013-10-22

    ... Bureau of Indian Affairs Indian Gaming AGENCY: Bureau of Indian Affairs, Interior. ACTION: Notice of extension of Tribal-State Class III Gaming Compact. SUMMARY: This publishes notice of the extension of the Class III gaming compact between the Rosebud Sioux Tribe and the State of South Dakota. DATES:...

  2. 78 FR 78377 - Indian Gaming

    Science.gov (United States)

    2013-12-26

    ... Bureau of Indian Affairs Indian Gaming AGENCY: Bureau of Indian Affairs, Interior. ] ACTION: Notice of extension of Tribal-State Class III Gaming Compact. SUMMARY: This publishes notice of the extension of the Class III gaming compact between the Yankton Sioux Tribe and the State of South Dakota. DATES:...

  3. 78 FR 17427 - Indian Gaming

    Science.gov (United States)

    2013-03-21

    ... Bureau of Indian Affairs Indian Gaming AGENCY: Bureau of Indian Affairs, Interior. ACTION: Notice of Approved Tribal-State Class III Gaming Compact. SUMMARY: This notice publishes approval of the agreement between the Northern Cheyenne Tribe and the State of Montana concerning Class III Gaming (Compact)....

  4. 78 FR 54908 - Indian Gaming

    Science.gov (United States)

    2013-09-06

    ... Bureau of Indian Affairs Indian Gaming AGENCY: Bureau of Indian Affairs, Interior. ACTION: Notice of approved Tribal-State Class III Gaming Compact. SUMMARY: This notice publishes the approval of the Class III Tribal- State Gaming Compact between the Wiyot Tribe and the State of California. DATES:...

  5. 78 FR 33435 - Indian Gaming

    Science.gov (United States)

    2013-06-04

    ... Bureau of Indian Affairs Indian Gaming AGENCY: Bureau of Indian Affairs, Interior. ACTION: Notice of Approved Tribal-State Class III Gaming Amendments. SUMMARY: This notice publishes approval of an Agreement to Amend the Class III Tribal-State Gaming Compact between the Salt River Pima- Maricopa...

  6. Title IV: Improving Indian Education.

    Science.gov (United States)

    Barker, Kipp A.

    The Indian Education Act of 1972, Title IV, has improved Native American education by emphasizing Native American control; it comes after 400 years of Euro-American involvement in Indian education during which assimilation was the primary goal. In 1568 Jesuit priests began "civilizing" and Christianizing the "savage" Indians; in 1794 the first…

  7. Carrier facilitated transport of thorium from HCl medium using Cyanex 923 in n-dodecane containing supported liquid membrane

    International Nuclear Information System (INIS)

    Present studies deal with supported liquid membrane (SLM) technique for the separation of thorium from hydrochloric acid (HCl) medium using Cyanex 923 as a carrier. Effects of feed acidity, strippant, and membrane pore size and membrane thickness on the transport of thorium have been studied in detail. The optimized parameters were applied for separation of thorium from a radioanalytical waste. Stability of the membrane and membrane support was investigated. Transport of thorium increased from 78.3 to about 93.7 % with increase in acidity from 0.5 to 2 M using 0.3 M Cyanex 923 in n-dodecane as carrier and 2 M ammonium carbonate as stripping phase. The transport of thorium decreased above 2 M HCl. An attempt was made to model the physicochemical transport of thorium in SLM and understand the mechanism of thorium transport. (author)

  8. Current extraction and separation of uranium, thorium and rare earths elements from monazite leach solution using organophosphorous extractants

    International Nuclear Information System (INIS)

    A new process based on solvent extraction has been developed for separation of uranium, thorium and rare earths from monazite leach solution using organophosphorous extractants. The Thorium cake coming from monazite source was dissolved in HNO3 medium in presence of trace amount of HF for feed preparation. The separation of U(VI) was carried out by liquid-liquid extraction using tris-2-ethyl hexyl phosphoric acid (TEHP) in dodecane leaving thorium and rare earths elements in the raffinate. The thorium from raffinate was selectively extracted using 1M tri iso amyl phosphate (TiAP) in dodecane in organic phase leaving all rare earths elements in aqueous solution. The uranium and thorium from organic medium was quantitatively stripped using 0.05 M HNO3 counter current mode. Results indicate the quantitative separation of uranium, thorium and rare earths from thorium cake (monazite source) using organophosphorous extractant in counter current mode

  9. Biosorption behavior and mechanism of thorium on Bacillus sp. dwc-2 isolated from soil

    Institute of Scientific and Technical Information of China (English)

    兰图; 刘宁; 张东; 杨吉军; 罗顺忠; 安竹; 邬琦琦; 杨远友; 冯更生; 唐军

    2015-01-01

    To develop a microbe-based bioremediation strategy for cleaning up thorium-contaminated sites, we have investigated the biosorption behavior and mechanism of thorium on Bacillus sp. dwc-2, one of the dominant species of bacterial groups isolated from soils in Southwest China. Thorium biosorption depended on the pH of environment, and its rapid biosorption reached a maximum of up to 10.75 mg Th per gram of the bacteria (wet wt.) at pH 3.0. The biosorption agreed bettter with Langmuir isotherm model than Freundlich model, indicating that thorium biosorption was a monolayer adsorption. The thermodynamic parameters, negative change in Gibbs free energy and positive value in enthalpy and entropy, suggested that the biosorption was spontaneous, more favorable at higher temperature and endothermic process with an increase of entropy. Scanning electron microscopy (SEM) indicated that thorium initially binded with the cell surface, while transmission electron microscopy (TEM) revealed that Th deposited in the cytoplasm and served as cores for growth of element precipitation (e.g., phosphate minerals) or by self-precipitation of hydroxides, which is probably controlled by ion-exchange, as evidenced by particle induced X-ray emission (PIXE) and enhanced proton backscattering spectrometry (EPBS). Fourier Transform Infrared (FTIR) further indicated that thorium biosorption involved carboxyl and phosphate groups and protein in complexation or electrostatic interaction. Overall results indicated that a combined electrostatic interaction-complexation-ion exchange mechanism could be involved in thorium biosorption by Bacillus sp. dwc-2.

  10. Improved chelation therapy of intramuscularly deposited thorium by CaDTPA in the rat

    International Nuclear Information System (INIS)

    Comparative studies on the translocation and retention of intramuscularly (i.m.) injected thorium nitrate (234Th 46 ng + 232Th 5 μg per rat) in solutions of citrate, CaDTPA or citrate + CaDTPA in rats have been conducted. Results show that only thorium in mixed-ligand solution was entirely translocated from the muscle, with the greatest part being excreted from the body. In this case, the whole-body retention of thorium decreased to 16% of the injected radioactivity within 2 d, 13% being retained in the skeleton. Studies on the decorporation of 234Th + 232Th nitrates from a rat wound simulated with i.m. injection have also been carried out. The greatest translocation of thorium and its excretion was achieved with a single local injection of the mixed-ligand (citrate + CaDTPA) solution when compared with those of citrate or CaDTPA alone. The efficiency of mixed-ligand treatment decreased with its delay. On day 2 post-therapy, the whole-body content of thorium decreased to 30, 37 and 55% of injected radioactivity when the local treatment started immediately, postponed to 1 h or 24 h, after i.m. injection of thorium, respectively. In control rats without treatment, there was only a slight decrease in the content of thorium in the whole body. (author)

  11. Investigation of the use of thorium in LWRs for improving reactor core performance

    International Nuclear Information System (INIS)

    Thorium is a fertile material and most of the past research has focused on breeding thorium into fissile material to achieve a more sustainable use of nuclear power. However, the focus in this report is on using thorium to improve reactor core performance. The improvement of reactor core performance is achieved by increasing the thermal margins by homogeneously distributing thorium in the fuel pellets. A proposed uranium-thorium-based fuel assembly is simulated for the Swedish Ringhals-3 PWR core in a realistic demonstration. In order to fully grasp the benefits and drawbacks of the newly proposed uranium-thorium-based fuel, a reload safety evaluation has been performed. For a real core, the Swedish Radiation Safety Authority would require an identical evaluation method to ensure that safety criteria are met during the whole cycle. In this report, only a few key safety parameters, such as isothermal- and Doppler-temperature coefficients of reactivity, pin peak power, boron worth, shutdown margins, and core average beta-effective are presented. The calculations were performed by the two-dimensional transport code CASMO-4E, and the two group three dimensional nodal code SIMULATE-3K from Studsvik Scandpower. The results showed that the uranium-thorium-based fuel assembly improves the thermal margins, both in the pin peak power and the local power (Fq). The improved thermal margins would allow more flexible core loading patterns with less neutron leakage, and could be used in power uprated cores to offer better safety margins

  12. Effect of Thorium on Growth and Uptake of Some Elements by Maize Plant

    International Nuclear Information System (INIS)

    A pot experiment (sand culture) was carried out to investigate the effect of thorium on maize dry matter yield, contents and uptake of N,P ,K, Na and Fe and thorium accumulation in maize plant.The pots were contaminated by thorium as Thorium Nitrate(Th (NO3)4,H2O)at concentrations 0,5,10,11,12,13,14,15 and 50 ppm. Pots irrigated by 1/10 Hogland solution for 15 days, increased tol/4 Hogland solution after that.The results show that the dry matter (shoot, root and whole plant)decreased with increasing thorium concentration in soil up to 12 ppm and slightly increased with increasing Th to 13 ppm . The Nitrogen content and its uptake decreased with increasing thorium concentration in media growth up to 11 ppm .They were slightly increased at Th concentration between 11-14 ppm in maize shoot and root. The shoots always contained N-content and uptake more than that found in roots . P- uptake decreased in both shoots and roots with increasing in thorium concentration in media growth.

  13. Thorium determination by x-ray fluorescence spectrometry in simulated thorex process solutions

    International Nuclear Information System (INIS)

    The X-ray fluorescence method for thorium determination in aqueous and organic (TBP/n-dodecane) solutions is described. The thin film technique for sample preparation and a suitable internal standard had been used. The best conditions for Thorium determination had been established studying some parameters as analytical line, internal standard, filter paper, paper geometry, sample volume and measurement conditions. With the established conditions, thorium was concentration range of to 200 g Th/L and in organic solutions (2-63g Th/L) with 1,5% of precision. The accuracy of the proposed method was 3% in aqueous and organic phases. The detection limit was 1,2μg thorium for aqueous solutions and 1,4μg for organic solutions. Uranium, fission products, corrosion products and Thorex reagent components were studied as interfering elements in the thorium analysis. The matrix effect was also studied using the Thorex process simulated solutions. Finally, the method was applied to thorium determination in irradiated thorium solutions with satisfactory results. (author)

  14. Thorium cycle and molten salt reactors: field parameters and field constraints investigations toward 'thorium molten salt reactor' definition

    International Nuclear Information System (INIS)

    Producing nuclear energy in order to reduce the anthropic CO2 emission requires major technological advances. Nuclear plants of 4. generation have to respond to several constraints, as safety improvements, fuel breeding and radioactive waste minimization. For this purpose, it seems promising to use Thorium Cycle in Molten Salt Reactors. Studies on this domain have already been carried out. However, the final concept suffered from serious issues and was discontinued. A new reflection on this topic is being led in order to find acceptable solutions, and to design the Thorium Molten Salt Reactor concept. A nuclear reactor is simulated by the coupling of a neutron transport code with a materials evolution code. This allows us to reproduce the reactor behavior and its evolution all along its operation. Thanks to this method, we have studied a large number of reactor configurations. We have evaluated their efficiency through a group of constraints they have to satisfy. This work leads us to a better understanding of many physical phenomena controlling the reactor behavior. As a consequence, several efficient configurations have been discovered, allowing the emergence of new points of view in the research of Molten Salt Reactors. (author)

  15. Band structure and decay channels of thorium-229 low-lying isomeric state for ensemble of thorium atoms adsorbed on calcium fluoride

    Energy Technology Data Exchange (ETDEWEB)

    Borisyuk, Petr V.; Vasilyev, Oleg S.; Krasavin, Andrey V.; Troyan, Victor I. [National Research Nuclear University ' ' MEPhI' ' (Moscow Engineering Physics Institute), Kashirskoye shosse 31, 115409 Moscow (Russian Federation); Lebedinskii, Yury Yu. [National Research Nuclear University ' ' MEPhI' ' (Moscow Engineering Physics Institute), Kashirskoye shosse 31, 115409 Moscow (Russian Federation); Moscow Institute of Physics and Technology (State University), Institutskiy per. 9, 141700 Dolgoprudny, Moscow region (Russian Federation); Tkalya, Eugene V. [Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, Leninskie gory, 119991 Moscow (Russian Federation); Nuclear Safety Institute of Russian Academy of Science, Bol' shaya Tulskaya 52, 115191 Moscow (Russian Federation)

    2015-12-15

    The results are presented on the study of the electronic structure of thorium atoms adsorbed by the liquid atomic layer deposition from aqueous solution of thorium nitrate on the surface of CaF{sub 2}. The chemical state of the atoms and the change of the band structure in the surface layers of Th/CaF{sub 2} system on CaF{sub 2} substrate were investigated by XPS and REELS techniques. It was found that REELS spectra for Th/CaF{sub 2} system include peaks in the region of low energy losses (3-7 eV) which are missing in the similar spectra for pure CaF{sub 2}. It is concluded that the presence of the observed features in the REELS spectra is associated with the chemical state of thorium atoms and is caused by the presence of uncompensated chemical bonds at the Th/CaF{sub 2} interface, and, therefore, by the presence of unbound 6d- and 7s-electrons of thorium atoms. Assuming the equivalence of the electronic configuration of thorium-229 and thorium-232 atoms, an estimate was made on the time decay of the excited state of thorium-229 nuclei through the channel of the electron conversion. It was found that the relaxation time is about 40 μs for 6d-electrons, and about 1 μs for 7s-electrons. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  16. Thorium compounds processing at IPEN-CNEN/SP - Brazil and recent research initiatives

    International Nuclear Information System (INIS)

    Brazil has a long tradition in the thorium technology, from mining of monazite until the obtainment of high purity thorium compounds and IPEN has accumulated since the 60's a wide experience in the purification of thorium, obtained primarily from the monazite processing. Brazil has one of the biggest world nuclear resources (uranium and thorium), being the sixth natural uranium resource in the world (309,000 t U3O8), one of the first world thorium natural resource. The reasonably assured reserves and the estimated additional resources can reach 1.3 million metric tons of ThO2. Unfortunately, Brazil has not a thorium program and there never was a national program, lasting for a period sufficient to produce practical results of effective use of thorium in the Brazilian reactors. Worse, the specific research activities on different topics of the thorium cycle have declined over time, due to the lack of interest and support. An autonomous nuclear program was carried out in the country in the 80's. However, major political changes occurred in the program in the early 90's. These changes contributed to the further reduction of interest in alternative nuclear fuel cycles. Unfortunately, contrarily to what is happening in some countries in recent years, nowadays Brazil is paying little attention to the thorium, even less than in the past, despite its huge reserves. There are only limited and localized initiatives from some researchers. Some proposals would be an excellent opportunity to keep the existent capabilities in the institution that will be strategically important for the country in the future

  17. Assessment of thorium fuel cycles in pressurized water reactors. Final report

    International Nuclear Information System (INIS)

    Alternate thorium fuel cycles were evaluated on a consistent basis in a Combustion Engineering Standard System 80 plant to provide a base-line for comparison of resource utilization with the conventional uranium cycle and with more advanced concepts. The economic motivation and the technical feasibility of employing thorium-based fuels in present PWRs were also determined. In order to achieve a significant increase in generating capacity for a given uranium ore resource, thorium utilization must be widespread. This necessitates the use of thorium cycles employing highly-enriched uranium; increases in the energy generated per mined ton of ore on the order of 18 to 34 percent can be realized in the long term with these fuel cycles. Increases in energy generation for the highly-enriched uranium/thorium fuel cycles are obtained, however, at the expense of higher separative work requirements (about 25 percent) and higher uranium ore requirements during the early cycles. As a consequence, greater 30-year levelized fuel cycle costs are obtained for these fuel cycles. Cycles employing plutonium enrichment have a more limited long term impact on uranium ore utilization because of the large fraction of the nuclear generating capacity which must be operated on the conventional uranium cycle to provide start-up and makeup plutonium inventories. However, about 20 percent more energy can be generated per kilogram of plutonium consumed in the thorium cycle than in the uranium cycle, and hence the thorium-based cycle represents a superior way of utilizing existing plutonium stockpiles. Comparison of the characteristics of uranium- and thorium-based cores indicates that thorium fueling is feasible, and modifications to PWRs designed to accommodate plutonium recycle do not appear to be required

  18. Performance of Energy Multiplier Module (EM2) with long-burn thorium fuel cycle

    International Nuclear Information System (INIS)

    Energy Multiplier Module (EM2) is a helium-cooled fast reactor being developed by General Atomics for the 21st century grid. It is designed as a modular plant with a net electric output of 265 MWe with an evaporative heat sink and 240 MWe with an air-cooled heat sink. EM2 core performance is examined for the baseline loading of low-enriched uranium (LEU) as fissile material with depleted uranium (DU) as fertile material and compared to the alternate LEU with thorium loading. The latter has two options: a heterogeneous loading of thorium fuel in the place of DU that produces a longer fuel cycle, and homogeneously mixed thorium-uranium fuel loading. Compared to the baseline LEU/DU core, the cycle length of both thorium options is reduced due to higher neutron absorptions by thorium. However, for both, heterogeneous and homogenous thorium loading options, the fuel cycle length is over 24 years without refueling or reshuffling of fuel assemblies. The physics properties of the EM2 thorium core are close to those of the baseline core which constitute low excess reactivity, negative fuel temperature coefficient, and very small void reactivity. However, unlike the case of baseline EM2, the homogeneous thorium fuel loading provides additional advantage in reducing the power peaking of the core, which in turn reduces the cladding material neutron damage rate by 23%. It is interpreted that the relatively slow 233U buildup as compared to 239Pu for baseline core retards reactivity increase without the need for a complicated fuel loading pattern of the heterogeneous fuel loading, while maintaining the peak power density low. Therefore both the heterogeneous and homogeneous thorium loading options will be feasible in the EM2

  19. Design and evaluation of a thorium fueled reactor with seed-blanket assembly configuration

    International Nuclear Information System (INIS)

    Recently, thorium fuel cycle is receiving increasing attention as one of possible ways to solve the problems of existing reactor design. In particular, a competitive thorium fuel cycle for pressurized water reactors of current technology, Radkowsky Thorium Reactor (RTR), was suggested by Radkowsky, et al. Main design concept of RTR is to replace the fuel assemblies of existing reactors with new thorium fueled assemblies with seed-blanket configuration. Except for the use of Seed-Blanket Units (SBUs), RTR has almost the same hardware components with existing PWR technology. With minor modification, RTR concepts may be adopted to PWR. In this thesis, we designed a thorium fueled reactor according to the design features of RTR and carried out the assessment of its overall performance. For numerical estimation, we used the cell code system HELIOS and the 2-group diffusion nodal code system AFEN. The link of these two code systems was done for depletion calculation. To compare its performance with existing PWRs, the ABB/CE type SYSTEM 80+ core was also modeled and calculated. From the preliminary results of performance analysis of an RTR-type thorium reactor, and comparison with the ABB/CE type reactor, we could ascertain some advantages and problems. Although some technical problems still remain, i.e., the need of extensive use of burnable absorbers and other thermo-mechanical problems, we conclude that RTR-type thorium reactor may is one of the effective ways to solve the two main problems of existing nuclear technology, i.e., possible diversion of the spent fuel for weapons and the storage and disposal of the spent fuel (discharged fuel is less in amount and poor in fissile plutonium quality). From RTR-type thorium fuel cycle, we can also achieve economical benefits because it requires much less uranium and thorium than existing PWR to produce the same amount of energy

  20. American Indian Authors.

    Science.gov (United States)

    Momaday, Natachee Scott

    Twenty-six selections by 15 contemporary American Indian authors are given in this book. The selections--legends, ceremonial chants and prayers, poems, and stories--are accompanied by topics for discussion. Some of the selections deal with the supernatural, and some tell an actual story about the author. Pictures and short biographies of each…

  1. Indian Astronomy: History of

    Science.gov (United States)

    Mercier, R.; Murdin, P.

    2002-01-01

    From the time of A macronryabhat under dota (ca AD 500) there appeared in India a series of Sanskrit treatises on astronomy. Written always in verse, and normally accompanied by prose commentaries, these served to create an Indian tradition of mathematical astronomy which continued into the 18th century. There are as well texts from earlier centuries, grouped under the name Jyotishaveda macronn d...

  2. Caregiving in Indian Country

    Centers for Disease Control (CDC) Podcasts

    2009-12-23

    This podcast discusses the role of caregivers in Indian County and the importance of protecting their health. It is primarily targeted to public health and aging services professionals.  Created: 12/23/2009 by National Center for Chronic Disease Prevention and Health Promotion (NCCDPHP).   Date Released: 12/23/2009.

  3. Native Indian Leadership.

    Science.gov (United States)

    Jules, Felicity

    1988-01-01

    Identifies valued qualities and behaviors of Indian leaders through a literature review and unstructured interviews with three British Columbian tribal elders. Develops a model of Native leadership emphasizing connection to the people, wisdom, humility, personal integrity, service orientation, and the facilitator role. Contains 22 references. (SV)

  4. Indians of North Carolina.

    Science.gov (United States)

    Bureau of Indian Affairs (Dept. of Interior), Washington, DC.

    Published by the U.S. Department of the Interior, this brief booklet on the historical development of the Cherokee Nation emphasizes the Tribe's relationship with the Bureau of Indian Affairs and its improved economy. Citing tourism as the major tribal industry, tribal enterprises are named and described (a 61 unit motor court in existence since…

  5. American Indian Recipes.

    Science.gov (United States)

    Gurnoe, Katherine J.; Skjervold, Christian, Ed.

    Presenting some 60 to 70 Native American recipes, this document includes a brief introduction and a suggested reading list (15 citations related to American Indian foods). The introduction identifies five regional Native American cuisines as follows: in the Southwest, peppers and beans were made into chili, soups, guacamole, and barbecue sauces by…

  6. Indian School Days.

    Science.gov (United States)

    Johnston, Basil H.

    This autobiography relates the experiences of a young Ojibway boy who was taken from his family in 1939 at age 10 and placed in a Jesuit boarding school in northern Ontario, Canada. St. Peter Claver (later Garnier) or "Spanish," as the Indian school was known, was home to approximately 135 boys. Most of the students, who ranged in age from 4 to…

  7. Radiocarbon and Indian archaeology

    International Nuclear Information System (INIS)

    The increasing use of radiocarbon (C14) dating techniques in Indian archaeology has been described in detail. Work done in Microlithic cultures, Neolithic period, Indus civilization and Iron age cultures have been reported. C14 dates of various archaeological sites are listed. (K.B.)

  8. Transmutation of minor actinides in a Candu thorium borner

    International Nuclear Information System (INIS)

    The paper investigates the prospects of exploitation of rich world thorium reserves in CANDU reactors. Large quantities of plutonium have been accumulated in the nuclear waste of civilian LWRs and CANDU reactors. Reactor grade plutonium can be used as a booster fissile fuel material in form of mixed ThO2/PuO2 fuel in a CANDU fuel bundle in order to assure reactor criticality. Two different fuel compositions have been selected for investigations: 1) 96% thoria (ThO2) + 4% PuO2 and 2) 91% ThO2 + 5% UO2 + 4 PuO2. The latter is used for the purpose of denaturing the new 233U fuel with 238U. The behavior of the criticality k∞ and the burn-up values of the reactor have been pursued by full power operation for > ∼ 8 years. The reactor starts with k∞ = ∼ 1.39 and the criticality drops down asymptotically to values k∞ > 1.06, still tolerable and usable in a CANDU reactor. Reactor criticality k∞ remains nearly constant between the 4th year and 7th year of plant operation and then a slight increase is observed thereafter, along with a continuous depletion of thorium fuel. After the 2nd year, the CANDU reactor begins to operate practically as a thorium burner. Very high burn up can be achieved with the same fuel (> 160 000 MW.D/MT). The reactor criticality would be sufficient until a great fraction of the thorium fuel is burnt up, provided that the fuel rods could be fabricated to withstand such high burn up levels. Fuel fabrication costs and nuclear waste mass for final disposal per unit energy could be reduced drastically. There is a great quantity of weapon grade plutonium accumulated in nuclear stockpiles. In the second phase of investigations, weapon grade plutonium is used as a booster fissile fuel material in form of mixed ThO2/PuO2 fuel in a CANDU fuel bundle in order to assure the initial criticality at startup. Two different fuel compositions have been used: 1) 97% thoria (ThO2) + 3% PuO2 and 2) 92% ThO2 + 5% UO2 + 3% PuO2. The latter is used for

  9. Role of Thorium to Supplement Fuel Cycles of Future Nuclear Energy Systems

    International Nuclear Information System (INIS)

    The investigation of the thorium fuel cycle (ThFC) is a collaborative INPRO (International Project on Innovative Nuclear Reactors and Fuel Cycles) activity within its main area on global vision on sustainable nuclear energy for the 21st century. The current publication reports on the sustainability of nuclear power by re-examining the potential of thorium-based fuel cycles to support future large scale deployment of nuclear energy systems by increasing the availability of nuclear material. Special attention is paid to the thorium fuel cycle from the point of view of economics and proliferation resistance.

  10. Thorium Deposits of the United States - Energy Resources for the Future?

    Science.gov (United States)

    Van Gosen, Bradley S.; Gillerman, Virginia S.; Armbrustmacher, Theodore J.

    2009-01-01

    Many nations are exploring new ways to meet their growing energy supply needs, with a particular focus upon methods that produce lower carbon dioxide emissions compared to traditional oil, natural gas, and coal power plants. As a result, thorium-based nuclear power has experienced renewed attention as a potential energy source. Thus, it benefits the United States and other countries to identify and evaluate their indigenous thorium resources. This report describes the geology and resources of the principal thorium districts of the United States.

  11. Thorium determination in intercomparison samples and in some Romanian building materials by gamma ray spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Pantelica, A.; Georgesecu, I.I.; Murariu-Magureanu, M.D.; Margaritescu, I.; Cincu, E

    2001-07-01

    Thorium content in zircon sand, thorium ore and thorium liquid sample (EU Laboratories Network Intercomparison), as well as in some Romanian building materials: sand, wood, tufa, asbestos-cement, cement mill dust, coal fly ash, bricks, and tile (28 samples) were determined by gamma ray spectrometry. For the building materials, {sup 226}Ra, {sup 40}K and {sup 137}Cs specific activities were also measured. The results were compared with the Romanian legal norms concerning the highest admissible levels for {sup 232}Th, {sup 226}Ra, and {sup 40}K radioactivity, and to Th, U, and K concentration values previously determined in our laboratory on similar types of samples. (author)

  12. Thorium determination in intercomparison samples and in some Romanian building materials by gamma ray spectrometry

    International Nuclear Information System (INIS)

    Thorium content in zircon sand, thorium ore and thorium liquid sample (EU Laboratories Network Intercomparison), as well as in some Romanian building materials: sand, wood, tufa, asbestos-cement, cement mill dust, coal fly ash, bricks, and tile (28 samples) were determined by gamma ray spectrometry. For the building materials, 226Ra, 40K and 137Cs specific activities were also measured. The results were compared with the Romanian legal norms concerning the highest admissible levels for 232Th, 226Ra, and 40K radioactivity, and to Th, U, and K concentration values previously determined in our laboratory on similar types of samples. (author)

  13. Determination of thorium in environmental and workplace materials by ICP-MS

    International Nuclear Information System (INIS)

    The paper outlines the advantages of the use of Inductively Coupled Plasma Mass Spectrometry (ICP-MS) over radiometric techniques to measure natural thorium, 232Th. Experimental parameters that must be taken into account in the sample digestion, preparation and ICP-MS analysis of environmental (soils, rocks, sediments) or workplace (thorium oxide, reference solutions) materials are described. The methods presented are applied to various reference materials, with the aim of providing suitable procedures to be useful for other important thorium containing materials (such as monazite sands or welding electrodes). The participation in a European Commission intercomparison exercise is detailed and a comparison with alpha spectrometry is made

  14. Measurement of the thorium-228 activity in solutions cavitated by ultrasonic sound

    Energy Technology Data Exchange (ETDEWEB)

    Ford, R.; Gerbier-Violleau, M. [SNOLAB, 1039 RR-24, Lively ON, P3Y 1N2 (Canada); Vazquez-Jauregui, E., E-mail: ericvj@snolab.c [SNOLAB, 1039 RR-24, Lively ON, P3Y 1N2 (Canada)

    2010-01-18

    We show that cavitation of a solution of thorium-228 in water does not induce its transformation at a faster rate than the natural radioactive decay. We measured the activity of a thorium-228 solution in water before, and after, it was subjected to a cavitation at 44 kHz and 250 W for 90 min in order to observe any change in the thorium half-life. The results were compared to the original activity of the sample and we observed no change. Our results and conclusions conflict with those in a recent paper by F. Cardone et al.

  15. Measurement of the thorium-228 activity in solutions cavitated by ultrasonic sound

    International Nuclear Information System (INIS)

    We show that cavitation of a solution of thorium-228 in water does not induce its transformation at a faster rate than the natural radioactive decay. We measured the activity of a thorium-228 solution in water before, and after, it was subjected to a cavitation at 44 kHz and 250 W for 90 min in order to observe any change in the thorium half-life. The results were compared to the original activity of the sample and we observed no change. Our results and conclusions conflict with those in a recent paper by F. Cardone et al.

  16. Measurement of the thorium-228 activity in solutions cavitated by ultrasonic sound

    CERN Document Server

    Ford, R; Vazquez-Jauregui, E

    2009-01-01

    We show that cavitation of a solution of thorium-228 in water does not induce its transformation at a faster rate than the natural radioactive decay. We measured the activity of a thorium-228 solution in water before, and after, it was subjected to a cavitation at 44 kHz and $250 $W for 90 minutes in order to observe any change in the thorium half-life. The results were compared to the original activity of the sample and we observed no change. Our results and conclusions conflict with those in a recent paper by F. Cardone et. al. [Phys. Lett. A 373 (2009) 1956-1958].

  17. Some aspects of the thorium fuel cycle in heavy-water-moderated pressure tube reactors

    International Nuclear Information System (INIS)

    The use of thorium fuel cycles in heavy-water-moderated pressure tube (CANDU) reactors will allow much more energy to be extracted from a given amount of fuel than is possible with the present natural uranium cycle. The extent to which various factors affect thorium fuel cycle economics and resource consumption with equilibrium 233U levels in the fuel is considered. Resource consumption in growing nuclear power systems is also considered, and it is shown that considerable savings can be achieved even under conditions of rapid growth. The main elements of the development program necessary to provide the technological base for thorium fuel cycles in CANDU reactors are discussed. (author)

  18. Some aspects of the thorium fuel cycle in heavy-water-moderated pressure tube reactors

    International Nuclear Information System (INIS)

    The use of thorium fuel cycles in heavy-water-moderated pressure tube (CANDU) reactors will allow much more energy to be extracted from a given amount of fuel than is possible with the present natural uranium cycle. The extent to which various factors affect thorium fuel cycle economics and resource consumption with equilibrium 233U levels in the fuel is considered. Resource consumption in growing nuclear power systems is also considered, and it is shown that considerable savings can be achieved even under conditions of rapid growth. The main elements of the development program necessary to provide the technological base for thorium fuel cycles in CANDU reactors are discussed

  19. Equilibrium distribution of lanthanum, neodymium, and thorium between lithium chloride melt and liquid bismuth

    Science.gov (United States)

    Zagnit'ko, A. V.; Ignat'ev, V. V.

    2013-04-01

    The distribution of lanthanum, neodymium, and thorium between a lithium chloride melt and liquid bismuth with additions of lithium as a reducing agent are investigated at 650°C. Equilibrium values of their distribution constants are measured. It is shown that in contrast to neodymium and lanthanum, thorium cannot be extracted from bismuth into lithium chloride. This allows us to propose an efficient scheme for separating lanthanides and thorium in a system for the extraction of fuel salts in molten-salt nuclear reactors.

  20. Extraction studies of uranium(VI) and thorium(IV) with tributylphosphine oxide

    International Nuclear Information System (INIS)

    Tributylphosphine oxide is proposed as an extractant for uranium(VI) and thorium(IV) from salicylate media. The optimum extraction conditions were evaluated by studying various parameters such as pH, sodium salicylate concentration, tributylphosphine oxide concentration, diluents and shaking time. The extracted species were ascertained by logD-logC plots. The method is simple, fast, precise and permits the separation of uranium(VI) and thorium(IV) in binary as well as multicomponent systems. The method is also applied for the determination of uranium(VI) and thorium(IV) in monazite sand samples. (author)

  1. Determination of thorium and uranium contents in soil samples using SSNTD's passive method

    Indian Academy of Sciences (India)

    T A Salama; U Seddik; T M Dsoky; A Ahmed Morsy; R El-Asser

    2006-08-01

    Thorium-to-uranium ratios have been determined in different soil samples using CR-39 and LR-115-II solid-state nuclear track detectors (SSNTDs). A calibration method based on determination of SSNTD registration sensitivity ratio for -particles of thorium and uranium series has been developed. Thorium and uranium contents of the standard soil samples have been determined and compared with its known values. There is a good agreement between the results of this method and the values of standard samples. The method is simple, inexpensive, non-destructive and has a wide range of applications in environment, building materials and petroleum fields.

  2. Regularities of distribution of scandium and thorium complexes with alizarin derivatives in aqua-organic systems

    International Nuclear Information System (INIS)

    Complexing of thorium and scandium with alizarin derivatives was studied in aqua-acetone media. It was shown that maximal yield of complexes achieved when ph value was 2.5-6.0. Complex composition, stability constants and molar light absorption coefficients were determined by spectrophotometric method. Scandium and thorium were extracted quantitatively from acetate-buffer solutions in the presence of perchlorate or trichloroacetate ions. Complexes were extracted in organic phase with mole ratio R:Me=2:1. Structure of extracted complexes was established on IR and PMR spectra. The 1,2-dihydroxyanthraquinone was the most effective extractant for thorium and scandium ions

  3. The foam separation of thorium(IV) from dilute aqueous solutions

    International Nuclear Information System (INIS)

    The foam separation of thorium(IV) from the dilute aqueous solutions was investigated at pH values ranging from 1.2 to 12 using the cationic surfactant cetyl trimethyl ammonium bromide and the anionic collector sodium lauryl sulphate. Cetyl trimethyl ammonium bromide could not remove soluble thorium but partially floated the hydrous oxide. The percentage removal was found to depend on the pH. With sodium lauryl sulphate, removals approaching 100% could be achieved at all the pH values tested. The various factors that can affect the separation process investigated and the results are discussed in terms of the hydrolysis of thorium. (orig.)

  4. Study of the thorium incorporation by inhalation in individuals occupationally exposed

    International Nuclear Information System (INIS)

    A mathematical model describing the metabolism of inhaled thorium in the human body was developed. Through this model theoretical limits of excretion were calculated for workers of a monazite plant (Usina Santo Amaro). This limits were based on International Commission on Radiological Protection publication 30, 1979. Excreta samples from twelve workers of Usina Santo Amaro were collected and analysed for thorium. All samples were bellow the theoretical limits of excretion indicating that Usina Santo Amaro workers are exposed to thorium levels bellow the Annual Limits of Intake recommended by ICRP, publication 30. (author)

  5. Uranium and thorium determination in water samples taken along River Kura

    International Nuclear Information System (INIS)

    Full text : In the present investigation, uranium and thorium concentration in rivers water of Azerbaijan has been measured using inductively coupled plasma mass spectrometry. The Agilent 7700x series ICP-MS applied for analysis of water samples. This method is based on direct introduction of samples, without any chemical pre-treatment, into an inductively coupled plasma plasma mass spectrometer. Uranium and thorium was determined at the mass mass numbers of 238 and 232 respectively using Bi-209 as internal standard. The main purpose of the study is to measure the level of uranium and thorium in water samples taken along river Kura

  6. A modified fluoride reduction route for the preparation of thorium metal

    International Nuclear Information System (INIS)

    Thorium oxide is one of the most stable oxides known in nature. Commercially, thorium metal is produced by calciothermic reduction of its oxide. The process leads to the production of thorium powders, which if not handled carefully, can often lead to oxygen contamination in the final metal. In this paper, we report an alternative possibility of producing bulk thorium metal by calciothermic reduction of its fluorides. Fluoride being less hygroscopic and having higher boiling and melting point is preferred over the chloride intermediate. The process involves mixing of as prepared ThF4 and 20% excess calcium in a crucible in an argon environment and heating the charge to beyond the melting point of thorium. The heat of reaction during calcium reduction of thorium fluoride is not sufficient to increase the temperature of the reacted mass to above the melting points of the products. This is unlike the common metallothermic reduction process, viz. thermit process, in which both the products, the metal and the slag, melt due to the intense heat of the reaction and separate from each other due to density difference. The slag-metal separation in this process has to be ensured by heating the charge to above the melting point of the higher melting substance, otherwise a mixture of CaF2 and thorium metal would result. The reaction sequence of the process was studied by a visual observation. Besides, liquid thorium being very reactive, a proper choice of crucible material becomes important. In this paper, we describe our experiences on the interaction of liquid thorium with the crucible materials. In this work, we used two kind of crucibles: standard molybdenum crucibles and custom made fully dense yttria crucibles. Yttria crucibles of 25 mm dia and 85 mm length were specially made by Glass and Advanced Materials Division, Materials Group. An alternative route for production of metallic thorium is reported. The advantage in the process is that it can make thorium in bulk form

  7. A sequential separation procedure for the determination of Uranium, Thorium and their isotopes in geological materials

    International Nuclear Information System (INIS)

    Inductively coupled plasma atomic emission spectrometry(ICP/AES) was used for the determination of uranium and thorium in geological materials. Samples were predecomposed by mixed acid digestion technique. The separation of the uranium and thorium was achieved by systematic solvent extraction with TTA(thenoyltrifluoroacetone) and TOA(tri-n-octylamine) and back extraction into HCl. The results for standard rock sample, NIST SRM 278, showed a good agreement with those certified from NIST as well as found values by other non-destructive techniques. Additional purification for extracted portions was carried out by anion exchange chromatography for measurement of several natural radioisotopes of uranium and thorium by alpha spectrometry. (author)

  8. The Crystal Structure of Thorium and Zirconium Dihydrides by X-ray and Neutron Diffraction

    Science.gov (United States)

    Rundle, R.E.; Shull, C.G.; Wollan, E.O.

    1951-04-20

    Thorium forms a tetragonal lower hydride of composition ThH{sub 2}. The hydrides ThH{sub 2}, ThD{sub 2}, and ZrD{sub 2} have been studied by neutron diffraction in order that hydrogen positions could be determined. The hydrides are isomorphous, and have a deformed fluorite structure. Metal-hydrogen distances in thorium hydride are unusually large, as in UH{sub 3}. Thorium and zirconium scattering amplitudes and a revised scattering amplitude for deuterium are reported.

  9. Thorium and uranium in soil fractions and certain macromycete species in boreal forest ecosystems

    OpenAIRE

    M. M. Vinichuk

    2012-01-01

    The content of thorium (Th) and uranium (U) in fractions of soil edaphosphere, rhizosphere, rhizoplane, fungal mycelium and fruit bodies were investigated. The concentrations of thorium in edaphosphere and rhizosphere fractions and mycelia of fungi are not different significantly and vary in the range of 0.74–1.45 mg kg–1 dry matter. The concentration of thorium in the rhizoplane fraction is 4 times lower than in the bulk soil – edaphosphere. The concentrations of uranium in edaphosphere, rhi...

  10. High-quality thorium TRISO fuel performance in HTGRs

    International Nuclear Information System (INIS)

    Thorium as a nuclear fuel has received renewed interest, because of its widespread availability and the good irradiation performance of Th and mixed (Th,U) oxide compounds as fuels in nuclear power systems. Early HTGR development employed thorium together with high-enriched uranium (HEU). After 1980, HTGR fuel systems switched to low-enriched uranium (LEU). After completing fuel development for the AVR and the THTR with BISO coated particles, the German program expanded its efforts utilizing thorium and HEU TRISO coated particles in advanced HTGR concepts for process heat applications (PNP) and direct-cycle electricity production (HHT). The combination of a low-temperature isotropic (LTI) inner and outer pyrocarbon layers surrounding a strong, stable SiC layer greatly improved manufacturing conditions and the subsequent contamination and defective particle fractions in production fuel elements. In addition, this combination provided improved mechanical strength and a higher degree of solid fission product retention, not known previously with high-temperature isotropic (HTI) BISO coatings. The improved performance of the HEU (Th, U)O2 TRISO fuel system was successfully demonstrated in three primary areas of development: manufacturing, irradiation testing under normal operating conditions, and accident simulation testing. In terms of demonstrating performance for advanced HTGR applications, the experimental failure statistic from manufacture and irradiation testing are significantly below the coated particle requirements specified for PNP and HHT designs at the time. Covering a range to 1300 C in normal operations and 1600 C in accidents, with burnups to 13% FIMA and fast fluences to 8 x 1025 n/m2 (E> 16 fJ), the performance results exceed the design limits on manufacturing and operational requirements for the German HTR-Modul concept, which are 6.5 x 10-5 for manufacturing, 2 x 10-4 for normal operating conditions, and 5 x 10-4 for accident conditions. These

  11. Physics design of advanced heavy water reactor utilising thorium

    International Nuclear Information System (INIS)

    An Advanced Heavy Water Reactor (AHWR) is being developed in India with the aim of utilising thorium for power generation. AHWR is a vertical pressure tube type reactor cooled by boiling light water and moderated by heavy water. It has been optimised for the thorium cycle. The main design objective is to be self-sustaining in 233U with most of the power from the thorium fuel using plutonium as the external fissile feed. It incorporates several advanced safety features namely, heat removal through natural circulation and a negative void coefficient of reactivity. The reactor has been designed to produce 750 MW(th) at a discharge burnup of 20,000 MWd/H(e). The physics design of AHWR has followed an evolutionary path ranging from a seed and blanket concept to a simplified composite cluster to achieve a good thermal hydraulic coupling. We have designed a composite cluster using both kinds of fuel namely, (Th-UO2 and (Th-Pu)O2. With plutonium seed, negative void coefficient can be achieved by making the spectrum harder. This was done by using a pyrocarbon scatterer in the moderator. The void coefficient strongly depends on plutonium. As plutonium burns very rapidly, it is not possible to achieve uniformly negative void coefficient with burnup in this cluster. Alternatively, burnable poison can be used within the cluster to achieve negative void coefficient taking advantage of the flux redistribution and change in spectrum upon voiding. Here, it is possible to achieve almost constant void reactivity with burnup resulting in a good thermal hydraulic coupling. The cluster design presently incorporates a central burnable absorber region. Boiling light water coolant requires that the core power distribution be optimised with thermal hydraulic parameters. The peaking factors inside the cluster should be low so as to have significant margin in operational conditions and to avoid burnout in accident conditions. The variation of reactivity from cold clean to hot operating has

  12. High-quality thorium TRISO fuel performance in HTGRs

    Energy Technology Data Exchange (ETDEWEB)

    Verfondern, Karl [Forschungszentrum Juelich GmbH (Germany); Allelein, Hans-Josef [Forschungszentrum Juelich GmbH (Germany); Technische Hochschule Aachen (Germany); Nabielek, Heinz; Kania, Michael J.

    2013-11-01

    Thorium as a nuclear fuel has received renewed interest, because of its widespread availability and the good irradiation performance of Th and mixed (Th,U) oxide compounds as fuels in nuclear power systems. Early HTGR development employed thorium together with high-enriched uranium (HEU). After 1980, HTGR fuel systems switched to low-enriched uranium (LEU). After completing fuel development for the AVR and the THTR with BISO coated particles, the German program expanded its efforts utilizing thorium and HEU TRISO coated particles in advanced HTGR concepts for process heat applications (PNP) and direct-cycle electricity production (HHT). The combination of a low-temperature isotropic (LTI) inner and outer pyrocarbon layers surrounding a strong, stable SiC layer greatly improved manufacturing conditions and the subsequent contamination and defective particle fractions in production fuel elements. In addition, this combination provided improved mechanical strength and a higher degree of solid fission product retention, not known previously with high-temperature isotropic (HTI) BISO coatings. The improved performance of the HEU (Th, U)O{sub 2} TRISO fuel system was successfully demonstrated in three primary areas of development: manufacturing, irradiation testing under normal operating conditions, and accident simulation testing. In terms of demonstrating performance for advanced HTGR applications, the experimental failure statistic from manufacture and irradiation testing are significantly below the coated particle requirements specified for PNP and HHT designs at the time. Covering a range to 1300 C in normal operations and 1600 C in accidents, with burnups to 13% FIMA and fast fluences to 8 x 10{sup 25} n/m{sup 2} (E> 16 fJ), the performance results exceed the design limits on manufacturing and operational requirements for the German HTR-Modul concept, which are 6.5 x 10{sup -5} for manufacturing, 2 x 10{sup -4} for normal operating conditions, and 5 x 10{sup -4

  13. Recovery of thorium and rare earths by their peroxides precipitation from a residue produced in the thorium purification facility; Recuperacao de torio e terras raras via peroxido do residuo originado na unidade de purificacao de torio

    Energy Technology Data Exchange (ETDEWEB)

    Freitas, Antonio Alves de

    2008-07-01

    As consequence of the operation of a Thorium purification facility, for pure Thorium Nitrate production, the IPEN (Instituto de Pesquisas Energeticas e Nucleares) has stored away a solid residue called RETOTER (REsiduo de TOrio e TErras Raras). The RETOTER is rich in Rare-Earth Elements and significant amount of Thorium-232 and minor amount of Uranium. Furthermore it contains several radionuclides from the natural decay series. Significant radioactivity contribution is generated by the Thorium descendent, mainly the Radium-228(T{sub 1/2}=5.7y), known as meso thorium and Thorium-228(T{sub 1/2} 1.90y). An important thorium daughter is the Lead-208, a stable isotope present with an expressive quantity. After the enclosure of the operation of the Thorium purification facility, many researches have been developed for the establishment of methodologies for recovery of Thorium, Rare-Earth Elements and Lead-208 from the RETOTER. This work presents a method for RETOTER decontamination, separating and bordering upon some radioactive isotopes. The residue was digested with nitric acid and the Radium-228 was separated by the Barium Sulphate co-precipitation procedure. Finally, the Thorium was separated by the peroxide precipitation and the Rare-Earth Elements were also recovered by the Rare-Earth peroxide precipitation in the filtrate solution.(author)

  14. Asymmetrically deformed states of thorium isotopes during fission process

    International Nuclear Information System (INIS)

    Some theoretical considerations are recalled on fission barriers calculated from macroscopic, microscopic or macroscopic-microscopic and ''thorium anomaly'' problem is set. Experimental techniques used to measure fission cross sections in (n,f) reactions near the threshold are described. Fission dectector is described; stray resonance problems and retrodiffused neutrons are discussed. Results obtained in experimental study of 230Th(n,f) and 232Th(n,f) reactions are presented. They are compared with results obtained in other laboratories. The analysis model which allows to describe a (n,f) reaction is exposed. The compound nucleus formation cross section and transmission coefficients in neutron and gamma output channel are presented according to neutron energy for each value of angular moment and parity. Cross-section analysis and angular distribution obtained respectively in 230Th(n,f) and 232Th(n,f) reactions is exposed. Result interpretation show new aspects of nuclei rotational spectra and new nuclear forms

  15. Burnup calculations using serpent code in accelerator driven thorium reactors

    International Nuclear Information System (INIS)

    In this study, burnup calculations have been performed for a sodium cooled Accelerator Driven Thorium Reactor (ADTR) using the Serpent 1.1.16 Monte Carlo code. The ADTR has been designed for burning minor actinides, mixed 232Th and mixed 233U fuels. A solid Pb-Bi spallation target in the center of the core is used and sodium as coolant. The system is designed for a heating power of 2 000 MW and for an operation time of 600 days. For burnup calculations the Advanced Matrix Exponential Method CRAM (Chebyshev Rational Approximation Method) and different nuclear data libraries (ENDF7, JEF2.2, JEFF3.1.1) were used. The effective multiplication factor change from 0.93 to 0.97 for different nuclear data libraries during the reactor operation period. (orig.)

  16. Burnup calculations using serpent code in accelerator driven thorium reactors

    Energy Technology Data Exchange (ETDEWEB)

    Korkmaz, M.E.; Agar, O. [Karamanoglu Mehmetbey Univ., Karaman (Turkey). Physics Dept.; Yigit, M. [Aksaray Univ. (Turkey). Physics Dept.

    2013-07-15

    In this study, burnup calculations have been performed for a sodium cooled Accelerator Driven Thorium Reactor (ADTR) using the Serpent 1.1.16 Monte Carlo code. The ADTR has been designed for burning minor actinides, mixed {sup 232}Th and mixed {sup 233}U fuels. A solid Pb-Bi spallation target in the center of the core is used and sodium as coolant. The system is designed for a heating power of 2 000 MW and for an operation time of 600 days. For burnup calculations the Advanced Matrix Exponential Method CRAM (Chebyshev Rational Approximation Method) and different nuclear data libraries (ENDF7, JEF2.2, JEFF3.1.1) were used. The effective multiplication factor change from 0.93 to 0.97 for different nuclear data libraries during the reactor operation period. (orig.)

  17. Mortality among female workers at a thorium-processing plant

    International Nuclear Information System (INIS)

    The mortality patterns among a cohort of 677 female workers at a thorium-processing plant are reported for the period from 1940 to 1982. Of the 677 women, 165 were reported dead; 459 were still alive; and 53 (7.8%) were lost to follow-up. The standardized mortality ratios from all causes (0.74), all cancers (0.53), and circulatory diseases (0.66) were significantly below those for the general US population. In this cohort, 5 deaths due to lung cancer and 1 death from leukemia were observed, with 4.53 and 1.69 deaths expected, respectively. No deaths from cancer of the liver, pancreas, or bone were observed. Poisson regression analysis was used for an internal comparison within the cohort. The results of the Poisson regression analysis showed no significant effect on mortality rates of all causes and cancers from the study factors, including job classification, duration of employment, and time since first employment

  18. Thorium fuel cycle technology for molten salt reactor systems

    International Nuclear Information System (INIS)

    Molten Salt Reactor (MSR) is classified as the non-classical nuclear type based on the specific featured coming out from the use of liquid fuel circulating in the MSR primary circuit. Other uniqueness of the reactor type is based on the fact that the primary or fuel circuit of the reactor in operation for a long run. MSR is the only reactor system, which can be operated with thorium fuel within the pure 232Th - 233U fuel cycle with the breeding factor significantly higher than one. It can bring several advantages, mainly in the radioactive waste management, thanks to minimized production higher actinides. With respects to all these facts and features, the fuel cycle aspects of MSR system are quite complicated, especially if the technology shall guarantee all possible advantages of MSR system concurrently with good economy, technological safety and reliability and inevitable proliferation resistance

  19. Nuclear thermionic converter. [tungsten-thorium oxide rods

    Science.gov (United States)

    Phillips, W. M.; Mondt, J. F. (Inventor)

    1977-01-01

    Efficient nuclear reactor thermionic converter units are described which can be constructed at low cost and assembled in a reactor which requires a minimum of fuel. Each converter unit utilizes an emitter rod with a fluted exterior, several fuel passages located in the bulges that are formed in the rod between the flutes, and a collector receiving passage formed through the center of the rod. An array of rods is closely packed in an interfitting arrangement, with the bulges of the rods received in the recesses formed between the bulges of other rods, thereby closely packing the nuclear fuel. The rods are constructed of a mixture of tungsten and thorium oxide to provide high power output, high efficiency, high strength, and good machinability.

  20. Microdetermination of thorium using 5, 7-diiodo-8-hydroxyquinoline

    International Nuclear Information System (INIS)

    An extractive spectrophotometric method for the trace determination of thorium is developed employing 5, 7-diiodo-8-hydroxyquinoline (in acetone) as complexing agent for the metal ion in aqueous medium. The yellow colored complex produced is quantitatively extracted into chloroform with absorption maximum at 409 nm. The method obeys Beer's law in the range 0.0-12.0 μg Th ml-1 having molar absorbitivity and Sandell's sensitivity values of 0.9 x 104 1 mol-1 cm-1 and 0.0256 μg Th cm-2 respectively. The ratio of metal to ligand in the extracted species is determined as 1:2. The method is free from the interference of a large number of diverse ions. Using the proposed procedure, the analysis of various samples has been carried out satisfactorily. (author)