Radioactive microspheres have demonstrated excellent therapeutic effects and good tolerance in the treatment of unresectable primary and secondary liver malignancies.This is attributed to precise embolization and pote...Radioactive microspheres have demonstrated excellent therapeutic effects and good tolerance in the treatment of unresectable primary and secondary liver malignancies.This is attributed to precise embolization and potent anti-tumor effect.However,certain limitations such as unstable loading,perfusion stasis,heterogeneous distribution,ectopic distribution,and insufficient dosage,restrict their clinical application.Herein,a novel personalized Y-90 carbon microsphere with high uniformity,high specific activity and high availability(^(90)Y-HUACM)is presented.It is synthesized through planar molecular complex adsorption and chemical deposition solidification.^(90)Y-HUACM exhibited controllable size,excellent biocompatibility,outstanding in vitro and in vivo stability.The radiolabeling efficiency of Y-90 exceeded 99%and the leaching rate of Y-90 is far below 0.1%.Furthermore,the excellent anti-tumor effect,nuclide loading stability,anti-reflux characteristics,precise embolization,and biosafety of^(90)Y-HUACM were validated in a rabbit VX2liver tumor model.In summary,this new,high-performance,and customizable radioactive microsphere provides a superior choice for selective internal radiation treatment of advanced liver cancer is expected to be rapidly applied in clinical practice.展开更多
Malignant tumours always threaten human health.For tumour diagnosis,positron emission tomography(PET)is the most sensitive and advanced imaging technique by radiotracers,such as radioactive^(18)F,^(11)C,^(64)Cu,^(68)G...Malignant tumours always threaten human health.For tumour diagnosis,positron emission tomography(PET)is the most sensitive and advanced imaging technique by radiotracers,such as radioactive^(18)F,^(11)C,^(64)Cu,^(68)Ga,and^(89)Zr.Among the radiotracers,the radioactive^(18)F-labelled chemical agent as PET probes plays a predominant role in monitoring,detecting,treating,and predicting tumours due to its perfect half-life.In this paper,the^(18)F-labelled chemical materials as PET probes are systematically summarized.First,we introduce various radionuclides of PET and elaborate on the mechanism of PET imaging.It highlights the^(18)F-labelled chemical agents used as PET probes,including[^(18)F]-2-deoxy-2-[^(18)F]fluoro-D-glucose([^(18)F]-FDG),^(18)F-labelled amino acids,^(18)F-labelled nucleic acids,^(18)F-labelled receptors,^(18)F-labelled reporter genes,and^(18)F-labelled hypoxia agents.In addition,some PET probes with metal as a supplementary element are introduced briefly.Meanwhile,the^(18)F-labelled nanoparticles for the PET probe and the multi-modality imaging probe are summarized in detail.The approach and strategies for the fabrication of^(18)F-labelled PET probes are also described briefly.The future development of the PET probe is also prospected.The development and application of^(18)F-labelled PET probes will expand our knowledge and shed light on the diagnosis and theranostics of tumours.展开更多
Background:To evaluate sex‐related differences in the risk factors associated with nonhealing or recurrence of hyper-thyroidism(NHRH)in patients with Graves'disease(GD)treated with radioactive iodine.Methods:In t...Background:To evaluate sex‐related differences in the risk factors associated with nonhealing or recurrence of hyper-thyroidism(NHRH)in patients with Graves'disease(GD)treated with radioactive iodine.Methods:In total,285 patients were enrolled.Data on radioactive iodine(RAI)dosage,ultrasound indexes of the thyroid,and other clinical factors were collected.Patients were divided into NHRH and non‐NHRH(hypothyroidism or euthyroidism)groups based on treatment outcomes.Univariate and multivariate weighted logistic regression analyses were used to identify factors associated with NHRH.Sex‐specific analyses of these risk factors were also conducted.Results:There were no significant differences between the two groups in terms of sex,thyroid shear wave elastography velocity values,or pretreatment serum free thyroxine(FT4)levels.Thyroid volume and age were independently associated with NHRH,with the odds of NHRH gradually decreasing as age increased.In subgroup analyses,both age and thyroid volume were independent risk factors for NHRH in female patients(p<0.05),while in male patients,only FT4 was independently associated with NHRH(p<0.05).Conclusions:In patients of different sexes,the influence of thyroid volume,age,and FT4 on treatment outcomes exhibits distinct patterns.展开更多
Alkaline igneous rocks represent one of the most economically important resources of radioactive minerals and rare metals.New field observations and petrographic studies are integrated with whole-rock geochemical anal...Alkaline igneous rocks represent one of the most economically important resources of radioactive minerals and rare metals.New field observations and petrographic studies are integrated with whole-rock geochemical analyses and Gamma ray spectroscopy data of alkaline rocks associated with the Amreit complex.The fieldwork was achieved by the collection of more than forty samples from alkaline granites and alkaline syenites.The youngest rocks cropping out in the study area are the cogenetic alkaline rocks,ranging from alkaline granite to alkaline syenite.These alkaline rocks are composed essentially of K-feldspar,alkali amphiboles(arfvedsonite),and sodic pyroxene,with accessories such as zircon,apatite,and ilmenite.Mineral characterization of the highly radioactive zones in both alkaline granite and alkaline syenite displays enrichment in monazite,thorite,zircon,ferro-columbite,xenotime,and allanite minerals.Geochemical analyses indicate that the Amreit rocks are alkaline with peralkaline affinity and have high concentrations of total alkalis(K_(2)O+Na_(2)O),large ion lithophile elements(LILEs;Ba and Rb),high field strength elements(HFSEs;Y,Zr and Nb),rare earth elements(REEs)and significantly depleted in K,Sr,P,Ti,and Eu,typically of post-collision A-type granites.Typically,the Amreit alkaline igneous rocks are classified as within plate granites and display A2 subtype characteristics.The fractionation of K-feldspars played a distinctive role during the magmatic evolution of these alkaline rocks.The geochemical characteristics indicate that the studied alkaline igneous rocks which were originated by fractional crystallization of alkaline magmas were responsible for the enrichment of the REE and rare metals in the residual melt.The high radioactivity is essentially related to accessory minerals,such as zircon,allanite,and monazite.The alkaline granite is the most U-and Thrich rock,where radioactivity level reaches up to 14.7 ppm(181.55 Bq/kg)e U,40.6 ppm(164.84 Bq/kg)e Th,whereas in alkaline syenite radioactivity level is 8.5 ppm(104.96 Bq/kg)e U,30.2 ppm(122.61 Bq/kg)e Th.These observations suppose that these alkaline rocks may be important targets for REEs and radioactive mineral exploration.展开更多
Radioactive iodine(RAI)therapy remains a cornerstone in the management of differentiated thyroid cancer(DTC).The therapeutic efficacy of RAI depends on thyroid-stimulating hormone(TSH)-driven uptake via the sodium-iod...Radioactive iodine(RAI)therapy remains a cornerstone in the management of differentiated thyroid cancer(DTC).The therapeutic efficacy of RAI depends on thyroid-stimulating hormone(TSH)-driven uptake via the sodium-iodide symporter(NIS).Although elevated TSH levels are routinely achieved before RAI administration,the circadian rhythm of TSH,which peaks overnight,is largely overlooked in treatment protocols.Aligning RAI administration with this physiological peak,particularly through evening dosing,may enhance iodine uptake,improve therapeutic efficacy,and reduce systemic exposure.Preclinical data and the known circadian regulation of TSH and NIS support this approach,although clinical validation is lacking.Evening dosing may also improve patient convenience and clinic workflow.However,logistical challenges and the absence of human trials present barriers to implementation.In this narrative review,we synthesize current evidence and tentatively propose the chronotherapeutic alignment of RAI timing as a novel,potentially impactful optimization strategy in DTC management.Prospective studies are needed to evaluate its clinical benefits and feasibility.展开更多
This work is devoted to numerical analysis of thermo-hydromechanical problem and cracking process in saturated porous media in the context of deep geological disposal of radioactive waste.The fundamental background of...This work is devoted to numerical analysis of thermo-hydromechanical problem and cracking process in saturated porous media in the context of deep geological disposal of radioactive waste.The fundamental background of thermo-poro-elastoplasticity theory is first summarized.The emphasis is put on the effect of pore fluid pressure on plastic deformation.A micromechanics-based elastoplastic model is then presented for a class of clayey rocks considered as host rock.Based on linear and nonlinear homogenization techniques,the proposed model is able to systematically account for the influences of porosity and mineral composition on macroscopic elastic properties and plastic yield strength.The initial anisotropy and time-dependent deformation are also taken into account.The induced cracking process is described by using a non-local damage model.A specific hybrid formulation is proposed,able to conveniently capture tensile,shear and mixed cracks.In particular,the influences of pore pressure and confining stress on the shear cracking mechanism are taken into account.The proposed model is applied to investigating thermo-hydromechanical responses and induced damage evolution in laboratory tests at the sample scale.In the last part,an in situ heating experiment is analyzed by using the proposed model.Numerical results are compared with experimental data and field measurements in terms of temperature variation,pore fluid pressure change and induced damaged zone.展开更多
To monitor nuclear and radiation emergencies,it is crucial to obtain accurate in situ measurements of the environmentalγ radiation dose rate from key radionuclides,particularly for large radioactive surface sources.T...To monitor nuclear and radiation emergencies,it is crucial to obtain accurate in situ measurements of the environmentalγ radiation dose rate from key radionuclides,particularly for large radioactive surface sources.The methods currently used for measuring dose rates are inadequate for obtaining the dose rates of key radionuclides and have large angular response errors when monitoring surface sources.To address this practical problem,this study proposes three methods for measuring the dose rate:the weighted peak total ratio,mean value regression,and numerical integration methods.These methods are based on energy-spectrum measurement data,and they were theoretically derived and numerically evaluated.Finally,a 1-m-long hexagonal radioactive surface source was integrated into a larger surface source.In situ measurement experiments were conducted on a large radioactive surface source using a dose-rate meter and a portable HPGespectrometer to analyze the errors of the three aforementioned methods and verify their validity.展开更多
BACKGROUND Radiation enteritis is a common complication of radiation therapy in which the surrounding normal intestinal tissue is damaged by ionising radiation,and there is no standard pharmacological prophylaxis or t...BACKGROUND Radiation enteritis is a common complication of radiation therapy in which the surrounding normal intestinal tissue is damaged by ionising radiation,and there is no standard pharmacological prophylaxis or treatment regimen available.Mesenchymal stem cell transplantation can be used for radiation protection and the treatment of acute radiation injury,but its therapeutic mechanism of action remains unclear.AIM To investigate the protective effects of autologous bone marrow-derived mesenchymal stem cell(ABMSC)transplantation on radiation-induced intestinal injury.METHODS A model of acute radioactive enteritis was established in dogs by applying abdominal intensity-modulated radiation at a single X-ray dose of 12 Gy.ABMSCs were transplanted into the mesenteric artery with the technology of femoral artery puncture and DSA imaging two days after radiation.Visual and histopathological changes of the experimental dogs were observed.Different kinds of cytokines from intestinal samples were tested using Quantibody Canine Cytokine Array method.Enzyme-linked immunosorbent assay(ELISA)was also used to evaluate the cytokines changes in serum.RESULTS The ABMSCs group showed significant improvements in survival status compared with the blank and saline treatment groups.Histological observations revealed that the former had lower histological scores than the later after treatment(P<0.05).Compared to the control groups,interleukin(IL)-10 and monocyte chemotactic protein(MCP)-1 from intestinal samples showed a remarkable increase and ELISA of serum samples proved higher secretion of the two target cytokines in the ABMSCs group(P<0.05).CONCLUSION Our data suggest that transplantation of ABMSCs promotes intestinal recovery after acute radioactive injury in Beagle dogs.The cytokines of IL-10 and MCP-1 might play an important role in this process.展开更多
Objective:To test the curative effect of human umbilical cord-derived mesenchymal stem cells on rat acute radioactive enteritis and thus in provide clinical therapeutic basis for radiation sickness.Methods:Human umbil...Objective:To test the curative effect of human umbilical cord-derived mesenchymal stem cells on rat acute radioactive enteritis and thus in provide clinical therapeutic basis for radiation sickness.Methods:Human umbilical cord-derived mesenchymal stem cells were cultivated in vitro and the model of acute radioactive enteritis of rats was established.Then,the umbilical cord mesenchymal stem cells were injected into the rats via tail vein.Visual and histopathiological changes of the experimental rats were observed.Results:After the injection,the rats in the prevention group and treatment group had remarkably better survival status than those in the control group.The histological observations revealed that the former also had better intestinal mucosa structure,more regenerative cells and stronger proliferation activity than the latter.Conclusions:Human umbilical cord-derived mesenchymal stem cells have a definite therapeutic effect on acute radioactive enteritis in rats.展开更多
For geological disposal of high-level radioactive waste （HLW）, the Chinese policy is that the spent nuclear fuel （SNF） should be reprocessed first, followed by vitrification and final disposal. The preliminary rep...For geological disposal of high-level radioactive waste （HLW）, the Chinese policy is that the spent nuclear fuel （SNF） should be reprocessed first, followed by vitrification and final disposal. The preliminary repository concept is a shaft-tunnel model, located in saturated zones in granite, while the final waste form for disposal is vitrified high-level radioactive waste. In 2006, the government published a long-term research and development （R＆D） plan for geological disposal of high-level radioactive waste. The program consists of three steps： （1） laboratory studies and site selection for a HLW repository （2006-2020）; （2） underground in-situ tests （2021-2040）; and （3） repository construction （2041-2050） followed by operation. With the support of China Atomic Energy Authority, comprehensive studies are underway and some progresses are made. The site characterization, including deep borehole drilling, has been performed at the most potential Beishan site in Gansu Province, Northwestern China. The data from geological and hydrogeological investigations, in-situ stress and permeability measurements of rock mass are presented in this paper. Engineered barrier studies are concentrated on the Gaomiaozi bentonite. A mock-up facility, which is used to study the thermo-hydro-mechano-chemical （THMC） properties of the bentonite, is under construction. Several projects on mechanical properties of Beishan granite are also underway. The key scientific challenges faced with HLW disposal are also discussed.展开更多
With the rapid development of nuclear power in China, the disposal of high-level radioactive waste（HLW） has become an important issue for nuclear safety and environmental protection. Deep geological disposal is inte...With the rapid development of nuclear power in China, the disposal of high-level radioactive waste（HLW） has become an important issue for nuclear safety and environmental protection. Deep geological disposal is internationally accepted as a feasible and safe way to dispose of HLW, and underground research laboratories（URLs） play an important and multi-faceted role in the development of HLW repositories. This paper introduces the overall planning and the latest progress for China＇s URL. On the basis of the proposed strategy to build an area-specific URL in combination with a comprehensive evaluation of the site selection results obtained during the last 33 years, the Xinchang site in the Beishan area,located in Gansu Province of northwestern China, has been selected as the final site for China＇s first URL built in granite. In the process of characterizing the Xinchang URL site, a series of investigations,including borehole drilling,geological mapping, geophysical surveying,hydraulic testing and in situ stress measurements, has been conducted. The investigation results indicate that the geological,hydrogeological, engineering geological and geochemical conditions of the Xinchang site are very suitable for URL construction. Meanwhile, to validate and develop construction technologies for the Beishan URL, the Beishan exploration tunnel（BET）, which is a 50-m-deep facility in the Jiujing sub-area, has been constructed and several in situ tests, such as drill-and-blast tests, characterization of the excavation damaged zone（EDZ）, and long-term deformation monitoring of surrounding rocks, have been performed in the BET. The methodologies and technologies established in the BET will serve for URL construction.According to the achievements of the characterization of the URL site, a preliminary design of the URL with a maximum depth of 560 m is proposed and necessary in situ tests in the URL are planned.展开更多
Clays and argillites are considered in some countries as possible host rocks for nuclear waste disposal at great depth.The use of compacted swelling clays as engineered barriers is also considered within the framework...Clays and argillites are considered in some countries as possible host rocks for nuclear waste disposal at great depth.The use of compacted swelling clays as engineered barriers is also considered within the framework of the multi-barrier concept.In relation to these concepts,various research programs have been conducted to assess the thermo-hydro-mechanical properties of radioactive waste disposal at great depth.After introducing the concepts of waste isolation developed in Belgium,France and Switzerland,the paper describes the retention and transfer properties of engineered barriers made up of compacted swelling clays in relation to microstructure features.Some features of the thermo-mechanical behaviors of three possible geological barriers,namely Boom clay（Belgium）,Callovo-Oxfordian clay（France） and Opalinus clay（Switzerland）,are then described,including the retention and transfer properties,volume change behavior,shear strength and thermal aspects.展开更多
A new and innovative detector system based on a silicon strip detector dedicated to the study of the reaction induced by lighter radioactive beams is described herein.The detector system consists of five sets of three...A new and innovative detector system based on a silicon strip detector dedicated to the study of the reaction induced by lighter radioactive beams is described herein.The detector system consists of five sets of three types of telescopes,which are successfully used to measure the angular distributions of both elastic scattering and breakup simultaneously, on the Radioactive Ion Beam Line in Lanzhou at Heavy Ion Research Facility in Lanzhou. This silicon detector array is used to measure the elastic scattering angular distributions of ^(11) Be on a ^(208) Pb target at E_(lab) = 140 and 209 MeV. A comparison of the Monte Carlo simulations with the experimental results shows a reasonable consistency.展开更多
In the context of radioactive waste disposal,an underground research laboratory(URL)is a facility in which experiments are conducted to demonstrate the feasibility of constructing and operating a radioactive waste dis...In the context of radioactive waste disposal,an underground research laboratory(URL)is a facility in which experiments are conducted to demonstrate the feasibility of constructing and operating a radioactive waste disposal facility within a geological formation.The Meuse/Haute-Marne URL is a sitespecific facility planned to study the feasibility of a radioactive waste disposal in the Callovo-Oxfordian(COx)claystone.The thermo-hydro-mechanical(THM)behaviour of the host rock is significant for the design of the underground nuclear waste disposal facility and for its long-term safety.The French National Radioactive Waste Management Agency(Andra)has begun a research programme aiming to demonstrate the relevancy of the French high-level waste(HLW)concept.This paper presents the programme implemented from small-scale(small diameter)boreholes to full-scale demonstration experiments to study the THM effects of the thermal transient on the COx claystone and the strategy implemented in this new programme to demonstrate and optimise current disposal facility components for HLW.It shows that the French high-level waste concept is feasible and working in the COx claystone.It also exhibits that,as for other plastic clay or claystone,heating-induced pore pressure increases and that the THM behaviour is anisotropic.展开更多
The mission of nuclear safety authorities in national radioactive waste disposal programmes is to ensure that people and the environment are protected against the hazards of ionising radiations emitted by the waste.It...The mission of nuclear safety authorities in national radioactive waste disposal programmes is to ensure that people and the environment are protected against the hazards of ionising radiations emitted by the waste.It implies the establishment of safety requirements and the oversight of the activities of the waste management organisation in charge of implementing the programme.In Belgium,the safety requirements for geological disposal rest on the following principles:defence-in-depth,demonstrability and the radiation protection principles elaborated by the International Commission on Radiological Protection(ICRP).Applying these principles requires notably an appropriate identification and characterisation of the processes upon which the safety functions fulfilled by the disposal system rely and of the processes that may affect the system performance.Therefore,research and development(R&D)on safety-relevant thermo-hydro-mechanical-chemical(THMC)issues is important to build confidence in the safety assessment.This paper points out the key THMC processes that might influence radionuclide transport in a disposal system and its surrounding environment,considering the dynamic nature of these processes.Their nature and significance are expected to change according to prevailing internal and external conditions,which evolve from the repository construction phase to the whole heatingecooling cycle of decaying waste after closure.As these processes have a potential impact on safety,it is essential to identify and to understand them properly when developing a disposal concept to ensure compliance with relevant safety requirements.In particular,the investigation of THMC processes is needed to manage uncertainties.This includes the identification and characterisation of uncertainties as well as for the understanding of their safety-relevance.R&D may also be necessary to reduce uncertainties of which the magnitude does not allow demonstrating the safety of the disposal system.展开更多
Radioactive noble-gas isotopes, SSKr （half-life tl/2=10.8 y）, 39Ar （tl/2=269 y）, and SlKr （t1/2-229,000 y）, are ideal tracers and can be detected by atom trap trace analysis （ATTA）, a laser-based technique, fr...Radioactive noble-gas isotopes, SSKr （half-life tl/2=10.8 y）, 39Ar （tl/2=269 y）, and SlKr （t1/2-229,000 y）, are ideal tracers and can be detected by atom trap trace analysis （ATTA）, a laser-based technique, from environmental samples like air and groundwater. Prior to ATTA measurements, it is necessary to efficiently extract krypton and argon gases from samples. Using a combination of cryogenic distillation, titanium chemical reaction and gas chromatography, we demonstrate that we can recover both krypton and argon gases from 1-10 L ＂air-like＂ samples with yields in excess of 90% and 98%, respectively, which meet well the requirements for ATTA measurements. A group of testing samples are analyzed to verify the performance of the system, including two groundwater samples obtained from north China plain.展开更多
In Belgium,the Boom clay was selected as a potential host formation for the disposal of high-level radioactive waste（HLW）.To demonstrate the suitability of Boom clay for bearing thermal load induced by the HLW,a lar...In Belgium,the Boom clay was selected as a potential host formation for the disposal of high-level radioactive waste（HLW）.To demonstrate the suitability of Boom clay for bearing thermal load induced by the HLW,a large-scale in-situ heater test,called PRACLAY heater test,will be conducted in the underground research laboratory（URL） in Mol.Owing to the limitations of the test（a short period of time compared with that considered in a real repository,different boundary conditions,etc.）,the test is designed to simulate,in a conservative way,the most critical state and phenomena that could occur in the host rock.The PRACLAY gallery was excavated at the end of 2007;the heating phase will begin in 2010 and will last for at least 10 years.The PRACLAY gallery itself leaves an opportunity to study the possibilities of sealing a disposal drift in Boom clay and testing the feasibility of hydraulic cut-off of any preferential pathway to the main access gallery through the excavation damage zone（EDZ） and the lining with a seal in a horizontal drift（horizontal seal）.Indeed,this is a generic problem for all deep geological disposal facilities for HLW.An annular seal made of compacted swelling bentonite will be installed in the front of the heated part of the PRACLAY gallery for these purposes.This paper provides detailed considerations on the thermo-hydro-mechanical（THM） boundary conditions for the design of the PRACLAY heater test and the seal test with the support of numerical calculations.It is believed that these important items considered in the PRACLAY heater test design also constitute key issues for the repository design.The outcome of the PRACLAY heater test will be an important milestone for the Belgian repository design.展开更多
Underground research laboratories （URLs）, including ＂generic URLs＂ and ＂site-specific URLs＂, are un- derground facilities in which characterisation, testing, technology development, and/or demonstration activiti...Underground research laboratories （URLs）, including ＂generic URLs＂ and ＂site-specific URLs＂, are un- derground facilities in which characterisation, testing, technology development, and/or demonstration activities are carried out in support of the development of geological repositories for high-level radioactive waste （HLW） disposal. In addition to the generic URL and site-specific URL, a concept of ＂areaspecific URL＂, or the third type of URL, is proposed in this paper. It is referred to as the facility that is built at a site within an area that is considered as a potential area for HLW repository or built at a place near the future repository site, and may be regarded as a precursor to the development of a repository at the site. It acts as a ＂generic URL＂, but also acts as a ＂site-specific URL＂ to some extent. Considering the current situation in China, the most suitable option is to build an ＂area-specific URL＂ in Beishan area, the first priority region for China＇s high-level waste repository. With this strategy, the goal to build China＇s URL by 2020 mav be achieved, but the time left is limited.展开更多
In view of the need for geomechanical safety analysis of repositories in salt rock, failure criteria,creep rupture criteria,material models,pillar design methods and criteria for the assessment of barrier efficiency a...In view of the need for geomechanical safety analysis of repositories in salt rock, failure criteria,creep rupture criteria,material models,pillar design methods and criteria for the assessment of barrier efficiency as well as investigations of the interaction between hydraulics and mechanics for the case of uncontrolled flooded repositories are necessary. The introduction of damage mechanics and of the Hou/Lux material model including damages into geomechanical safety analysis of repositories in salt rock can reduce some previous deficits in knowledge and modelling. This article will be as a part of geotechnical assessment to introduce the Hou/Lux material model,a new concept of hydro-mechanical coupling and a pillar design method as well as criteria for the assessment of efficiency of geological barriers.展开更多
Geological and hydrological characteristics, joint geometric features, rock physical and mechanical properties and rock mass quality are studied in the Beishan area, preselected for China5 s high-level radioactive was...Geological and hydrological characteristics, joint geometric features, rock physical and mechanical properties and rock mass quality are studied in the Beishan area, preselected for China5 s high-level radioactive waste(HLW) disposal engineering. A comprehensive survey method is developed to study joint geometric features in the outcrop and samples from borehole BS06 into the Xinchang rock mass were tested. The optimal joint sets are determined by rose diagrams and equal-area lower hemisphere plots of joint poles. Results show that: 1) the distribution of joint occurrence obeys a normal distribution, while the distribution of joint spacing obeys a negative exponential distribution; 2) concentric circular and tangent circular sampling windows are applied to study the trace length and the trace midpoint density. Results indicate that tangent circular sampling window is more stable and reasonable; 3) Beishan granite shows high density, low porosity and high strength based on many laboratory tests and the physical properties and mechanical properties are closely related; and4) a synthesis index, Joint Structure Rating(JSR), is applied to evaluate the quality of rock mass. Through the research results of rock mass characteristics, the Xinchang rock mass in the Beishan preselected area has the favorable conditions for China's HLW disposal repository site.展开更多
基金supported by the National Major Scientific and Technological Special Project for“Significant New Drugs Development”(No.2018ZX09201018–028)the nuclear energy development projects of China during the 13thFive Year Plan periodthe key research and development project of the Sichuan Provincial Department of Science and Technology(No.18ZDYF1466)。
文摘Radioactive microspheres have demonstrated excellent therapeutic effects and good tolerance in the treatment of unresectable primary and secondary liver malignancies.This is attributed to precise embolization and potent anti-tumor effect.However,certain limitations such as unstable loading,perfusion stasis,heterogeneous distribution,ectopic distribution,and insufficient dosage,restrict their clinical application.Herein,a novel personalized Y-90 carbon microsphere with high uniformity,high specific activity and high availability(^(90)Y-HUACM)is presented.It is synthesized through planar molecular complex adsorption and chemical deposition solidification.^(90)Y-HUACM exhibited controllable size,excellent biocompatibility,outstanding in vitro and in vivo stability.The radiolabeling efficiency of Y-90 exceeded 99%and the leaching rate of Y-90 is far below 0.1%.Furthermore,the excellent anti-tumor effect,nuclide loading stability,anti-reflux characteristics,precise embolization,and biosafety of^(90)Y-HUACM were validated in a rabbit VX2liver tumor model.In summary,this new,high-performance,and customizable radioactive microsphere provides a superior choice for selective internal radiation treatment of advanced liver cancer is expected to be rapidly applied in clinical practice.
文摘Malignant tumours always threaten human health.For tumour diagnosis,positron emission tomography(PET)is the most sensitive and advanced imaging technique by radiotracers,such as radioactive^(18)F,^(11)C,^(64)Cu,^(68)Ga,and^(89)Zr.Among the radiotracers,the radioactive^(18)F-labelled chemical agent as PET probes plays a predominant role in monitoring,detecting,treating,and predicting tumours due to its perfect half-life.In this paper,the^(18)F-labelled chemical materials as PET probes are systematically summarized.First,we introduce various radionuclides of PET and elaborate on the mechanism of PET imaging.It highlights the^(18)F-labelled chemical agents used as PET probes,including[^(18)F]-2-deoxy-2-[^(18)F]fluoro-D-glucose([^(18)F]-FDG),^(18)F-labelled amino acids,^(18)F-labelled nucleic acids,^(18)F-labelled receptors,^(18)F-labelled reporter genes,and^(18)F-labelled hypoxia agents.In addition,some PET probes with metal as a supplementary element are introduced briefly.Meanwhile,the^(18)F-labelled nanoparticles for the PET probe and the multi-modality imaging probe are summarized in detail.The approach and strategies for the fabrication of^(18)F-labelled PET probes are also described briefly.The future development of the PET probe is also prospected.The development and application of^(18)F-labelled PET probes will expand our knowledge and shed light on the diagnosis and theranostics of tumours.
基金suported by the National High Level Hospital Clinical Research Funding(2022-NHLHCRF-LX-02-03,2023-NHLHCRF-YXHZ-ZRZD-06)Ministry ofScience and Technology of the People's Republic ofChina,and National Natural Science Foundation ofChina(82071943,82273523).
文摘Background:To evaluate sex‐related differences in the risk factors associated with nonhealing or recurrence of hyper-thyroidism(NHRH)in patients with Graves'disease(GD)treated with radioactive iodine.Methods:In total,285 patients were enrolled.Data on radioactive iodine(RAI)dosage,ultrasound indexes of the thyroid,and other clinical factors were collected.Patients were divided into NHRH and non‐NHRH(hypothyroidism or euthyroidism)groups based on treatment outcomes.Univariate and multivariate weighted logistic regression analyses were used to identify factors associated with NHRH.Sex‐specific analyses of these risk factors were also conducted.Results:There were no significant differences between the two groups in terms of sex,thyroid shear wave elastography velocity values,or pretreatment serum free thyroxine(FT4)levels.Thyroid volume and age were independently associated with NHRH,with the odds of NHRH gradually decreasing as age increased.In subgroup analyses,both age and thyroid volume were independent risk factors for NHRH in female patients(p<0.05),while in male patients,only FT4 was independently associated with NHRH(p<0.05).Conclusions:In patients of different sexes,the influence of thyroid volume,age,and FT4 on treatment outcomes exhibits distinct patterns.
文摘Alkaline igneous rocks represent one of the most economically important resources of radioactive minerals and rare metals.New field observations and petrographic studies are integrated with whole-rock geochemical analyses and Gamma ray spectroscopy data of alkaline rocks associated with the Amreit complex.The fieldwork was achieved by the collection of more than forty samples from alkaline granites and alkaline syenites.The youngest rocks cropping out in the study area are the cogenetic alkaline rocks,ranging from alkaline granite to alkaline syenite.These alkaline rocks are composed essentially of K-feldspar,alkali amphiboles(arfvedsonite),and sodic pyroxene,with accessories such as zircon,apatite,and ilmenite.Mineral characterization of the highly radioactive zones in both alkaline granite and alkaline syenite displays enrichment in monazite,thorite,zircon,ferro-columbite,xenotime,and allanite minerals.Geochemical analyses indicate that the Amreit rocks are alkaline with peralkaline affinity and have high concentrations of total alkalis(K_(2)O+Na_(2)O),large ion lithophile elements(LILEs;Ba and Rb),high field strength elements(HFSEs;Y,Zr and Nb),rare earth elements(REEs)and significantly depleted in K,Sr,P,Ti,and Eu,typically of post-collision A-type granites.Typically,the Amreit alkaline igneous rocks are classified as within plate granites and display A2 subtype characteristics.The fractionation of K-feldspars played a distinctive role during the magmatic evolution of these alkaline rocks.The geochemical characteristics indicate that the studied alkaline igneous rocks which were originated by fractional crystallization of alkaline magmas were responsible for the enrichment of the REE and rare metals in the residual melt.The high radioactivity is essentially related to accessory minerals,such as zircon,allanite,and monazite.The alkaline granite is the most U-and Thrich rock,where radioactivity level reaches up to 14.7 ppm(181.55 Bq/kg)e U,40.6 ppm(164.84 Bq/kg)e Th,whereas in alkaline syenite radioactivity level is 8.5 ppm(104.96 Bq/kg)e U,30.2 ppm(122.61 Bq/kg)e Th.These observations suppose that these alkaline rocks may be important targets for REEs and radioactive mineral exploration.
文摘Radioactive iodine(RAI)therapy remains a cornerstone in the management of differentiated thyroid cancer(DTC).The therapeutic efficacy of RAI depends on thyroid-stimulating hormone(TSH)-driven uptake via the sodium-iodide symporter(NIS).Although elevated TSH levels are routinely achieved before RAI administration,the circadian rhythm of TSH,which peaks overnight,is largely overlooked in treatment protocols.Aligning RAI administration with this physiological peak,particularly through evening dosing,may enhance iodine uptake,improve therapeutic efficacy,and reduce systemic exposure.Preclinical data and the known circadian regulation of TSH and NIS support this approach,although clinical validation is lacking.Evening dosing may also improve patient convenience and clinic workflow.However,logistical challenges and the absence of human trials present barriers to implementation.In this narrative review,we synthesize current evidence and tentatively propose the chronotherapeutic alignment of RAI timing as a novel,potentially impactful optimization strategy in DTC management.Prospective studies are needed to evaluate its clinical benefits and feasibility.
基金supported by the French National Agency for radioactive waste management(ANDRA).
文摘This work is devoted to numerical analysis of thermo-hydromechanical problem and cracking process in saturated porous media in the context of deep geological disposal of radioactive waste.The fundamental background of thermo-poro-elastoplasticity theory is first summarized.The emphasis is put on the effect of pore fluid pressure on plastic deformation.A micromechanics-based elastoplastic model is then presented for a class of clayey rocks considered as host rock.Based on linear and nonlinear homogenization techniques,the proposed model is able to systematically account for the influences of porosity and mineral composition on macroscopic elastic properties and plastic yield strength.The initial anisotropy and time-dependent deformation are also taken into account.The induced cracking process is described by using a non-local damage model.A specific hybrid formulation is proposed,able to conveniently capture tensile,shear and mixed cracks.In particular,the influences of pore pressure and confining stress on the shear cracking mechanism are taken into account.The proposed model is applied to investigating thermo-hydromechanical responses and induced damage evolution in laboratory tests at the sample scale.In the last part,an in situ heating experiment is analyzed by using the proposed model.Numerical results are compared with experimental data and field measurements in terms of temperature variation,pore fluid pressure change and induced damaged zone.
文摘To monitor nuclear and radiation emergencies,it is crucial to obtain accurate in situ measurements of the environmentalγ radiation dose rate from key radionuclides,particularly for large radioactive surface sources.The methods currently used for measuring dose rates are inadequate for obtaining the dose rates of key radionuclides and have large angular response errors when monitoring surface sources.To address this practical problem,this study proposes three methods for measuring the dose rate:the weighted peak total ratio,mean value regression,and numerical integration methods.These methods are based on energy-spectrum measurement data,and they were theoretically derived and numerically evaluated.Finally,a 1-m-long hexagonal radioactive surface source was integrated into a larger surface source.In situ measurement experiments were conducted on a large radioactive surface source using a dose-rate meter and a portable HPGespectrometer to analyze the errors of the three aforementioned methods and verify their validity.
基金Supported by People's Livelihood Science and Technology Plan Joint Project of Liaoning Province,No.2021JH2/10300083。
文摘BACKGROUND Radiation enteritis is a common complication of radiation therapy in which the surrounding normal intestinal tissue is damaged by ionising radiation,and there is no standard pharmacological prophylaxis or treatment regimen available.Mesenchymal stem cell transplantation can be used for radiation protection and the treatment of acute radiation injury,but its therapeutic mechanism of action remains unclear.AIM To investigate the protective effects of autologous bone marrow-derived mesenchymal stem cell(ABMSC)transplantation on radiation-induced intestinal injury.METHODS A model of acute radioactive enteritis was established in dogs by applying abdominal intensity-modulated radiation at a single X-ray dose of 12 Gy.ABMSCs were transplanted into the mesenteric artery with the technology of femoral artery puncture and DSA imaging two days after radiation.Visual and histopathological changes of the experimental dogs were observed.Different kinds of cytokines from intestinal samples were tested using Quantibody Canine Cytokine Array method.Enzyme-linked immunosorbent assay(ELISA)was also used to evaluate the cytokines changes in serum.RESULTS The ABMSCs group showed significant improvements in survival status compared with the blank and saline treatment groups.Histological observations revealed that the former had lower histological scores than the later after treatment(P<0.05).Compared to the control groups,interleukin(IL)-10 and monocyte chemotactic protein(MCP)-1 from intestinal samples showed a remarkable increase and ELISA of serum samples proved higher secretion of the two target cytokines in the ABMSCs group(P<0.05).CONCLUSION Our data suggest that transplantation of ABMSCs promotes intestinal recovery after acute radioactive injury in Beagle dogs.The cytokines of IL-10 and MCP-1 might play an important role in this process.
基金supported by Wu Zuze Science and Technology Development Foundation of Beijing
文摘Objective:To test the curative effect of human umbilical cord-derived mesenchymal stem cells on rat acute radioactive enteritis and thus in provide clinical therapeutic basis for radiation sickness.Methods:Human umbilical cord-derived mesenchymal stem cells were cultivated in vitro and the model of acute radioactive enteritis of rats was established.Then,the umbilical cord mesenchymal stem cells were injected into the rats via tail vein.Visual and histopathiological changes of the experimental rats were observed.Results:After the injection,the rats in the prevention group and treatment group had remarkably better survival status than those in the control group.The histological observations revealed that the former also had better intestinal mucosa structure,more regenerative cells and stronger proliferation activity than the latter.Conclusions:Human umbilical cord-derived mesenchymal stem cells have a definite therapeutic effect on acute radioactive enteritis in rats.
基金Supported by the China Atomic Energy Authority’s Special Program for Radioactive Waste Management and the International Atomic Energy Agency’s Technical Cooperation Project (IAE-TC Project CPR/9/026, CPR/4/024, CPR/3/008)
文摘For geological disposal of high-level radioactive waste （HLW）, the Chinese policy is that the spent nuclear fuel （SNF） should be reprocessed first, followed by vitrification and final disposal. The preliminary repository concept is a shaft-tunnel model, located in saturated zones in granite, while the final waste form for disposal is vitrified high-level radioactive waste. In 2006, the government published a long-term research and development （R＆D） plan for geological disposal of high-level radioactive waste. The program consists of three steps： （1） laboratory studies and site selection for a HLW repository （2006-2020）; （2） underground in-situ tests （2021-2040）; and （3） repository construction （2041-2050） followed by operation. With the support of China Atomic Energy Authority, comprehensive studies are underway and some progresses are made. The site characterization, including deep borehole drilling, has been performed at the most potential Beishan site in Gansu Province, Northwestern China. The data from geological and hydrogeological investigations, in-situ stress and permeability measurements of rock mass are presented in this paper. Engineered barrier studies are concentrated on the Gaomiaozi bentonite. A mock-up facility, which is used to study the thermo-hydro-mechano-chemical （THMC） properties of the bentonite, is under construction. Several projects on mechanical properties of Beishan granite are also underway. The key scientific challenges faced with HLW disposal are also discussed.
基金support from the China Atomic Energy Authority (CAEA) for China's URL Development Program and the Geological Disposal ProgramThe International Atomic Energy Agency is specially thanked for its support for China's geological disposal program through its Technical Cooperation Projects
文摘With the rapid development of nuclear power in China, the disposal of high-level radioactive waste（HLW） has become an important issue for nuclear safety and environmental protection. Deep geological disposal is internationally accepted as a feasible and safe way to dispose of HLW, and underground research laboratories（URLs） play an important and multi-faceted role in the development of HLW repositories. This paper introduces the overall planning and the latest progress for China＇s URL. On the basis of the proposed strategy to build an area-specific URL in combination with a comprehensive evaluation of the site selection results obtained during the last 33 years, the Xinchang site in the Beishan area,located in Gansu Province of northwestern China, has been selected as the final site for China＇s first URL built in granite. In the process of characterizing the Xinchang URL site, a series of investigations,including borehole drilling,geological mapping, geophysical surveying,hydraulic testing and in situ stress measurements, has been conducted. The investigation results indicate that the geological,hydrogeological, engineering geological and geochemical conditions of the Xinchang site are very suitable for URL construction. Meanwhile, to validate and develop construction technologies for the Beishan URL, the Beishan exploration tunnel（BET）, which is a 50-m-deep facility in the Jiujing sub-area, has been constructed and several in situ tests, such as drill-and-blast tests, characterization of the excavation damaged zone（EDZ）, and long-term deformation monitoring of surrounding rocks, have been performed in the BET. The methodologies and technologies established in the BET will serve for URL construction.According to the achievements of the characterization of the URL site, a preliminary design of the URL with a maximum depth of 560 m is proposed and necessary in situ tests in the URL are planned.
文摘Clays and argillites are considered in some countries as possible host rocks for nuclear waste disposal at great depth.The use of compacted swelling clays as engineered barriers is also considered within the framework of the multi-barrier concept.In relation to these concepts,various research programs have been conducted to assess the thermo-hydro-mechanical properties of radioactive waste disposal at great depth.After introducing the concepts of waste isolation developed in Belgium,France and Switzerland,the paper describes the retention and transfer properties of engineered barriers made up of compacted swelling clays in relation to microstructure features.Some features of the thermo-mechanical behaviors of three possible geological barriers,namely Boom clay（Belgium）,Callovo-Oxfordian clay（France） and Opalinus clay（Switzerland）,are then described,including the retention and transfer properties,volume change behavior,shear strength and thermal aspects.
基金supported by the National Natural Science Foundation of China(Nos.U1432247,11575256,and U1632138)the CAS program of Light of West China Program under Grant(No.Y601030XB0)the National key R&D Program of China(No.2018YFA0404403)
文摘A new and innovative detector system based on a silicon strip detector dedicated to the study of the reaction induced by lighter radioactive beams is described herein.The detector system consists of five sets of three types of telescopes,which are successfully used to measure the angular distributions of both elastic scattering and breakup simultaneously, on the Radioactive Ion Beam Line in Lanzhou at Heavy Ion Research Facility in Lanzhou. This silicon detector array is used to measure the elastic scattering angular distributions of ^(11) Be on a ^(208) Pb target at E_(lab) = 140 and 209 MeV. A comparison of the Monte Carlo simulations with the experimental results shows a reasonable consistency.
文摘In the context of radioactive waste disposal,an underground research laboratory(URL)is a facility in which experiments are conducted to demonstrate the feasibility of constructing and operating a radioactive waste disposal facility within a geological formation.The Meuse/Haute-Marne URL is a sitespecific facility planned to study the feasibility of a radioactive waste disposal in the Callovo-Oxfordian(COx)claystone.The thermo-hydro-mechanical(THM)behaviour of the host rock is significant for the design of the underground nuclear waste disposal facility and for its long-term safety.The French National Radioactive Waste Management Agency(Andra)has begun a research programme aiming to demonstrate the relevancy of the French high-level waste(HLW)concept.This paper presents the programme implemented from small-scale(small diameter)boreholes to full-scale demonstration experiments to study the THM effects of the thermal transient on the COx claystone and the strategy implemented in this new programme to demonstrate and optimise current disposal facility components for HLW.It shows that the French high-level waste concept is feasible and working in the COx claystone.It also exhibits that,as for other plastic clay or claystone,heating-induced pore pressure increases and that the THM behaviour is anisotropic.
文摘The mission of nuclear safety authorities in national radioactive waste disposal programmes is to ensure that people and the environment are protected against the hazards of ionising radiations emitted by the waste.It implies the establishment of safety requirements and the oversight of the activities of the waste management organisation in charge of implementing the programme.In Belgium,the safety requirements for geological disposal rest on the following principles:defence-in-depth,demonstrability and the radiation protection principles elaborated by the International Commission on Radiological Protection(ICRP).Applying these principles requires notably an appropriate identification and characterisation of the processes upon which the safety functions fulfilled by the disposal system rely and of the processes that may affect the system performance.Therefore,research and development(R&D)on safety-relevant thermo-hydro-mechanical-chemical(THMC)issues is important to build confidence in the safety assessment.This paper points out the key THMC processes that might influence radionuclide transport in a disposal system and its surrounding environment,considering the dynamic nature of these processes.Their nature and significance are expected to change according to prevailing internal and external conditions,which evolve from the repository construction phase to the whole heatingecooling cycle of decaying waste after closure.As these processes have a potential impact on safety,it is essential to identify and to understand them properly when developing a disposal concept to ensure compliance with relevant safety requirements.In particular,the investigation of THMC processes is needed to manage uncertainties.This includes the identification and characterisation of uncertainties as well as for the understanding of their safety-relevance.R&D may also be necessary to reduce uncertainties of which the magnitude does not allow demonstrating the safety of the disposal system.
基金This work was supported by the Special Fund for Land and Resources Research in the Public Interest （No.201511046） and the National Natural Science Foundation of China （No.21225314 and No.41102151）. We would like to give our gratitude to Zong-yu Chen from IHEG for organizing the field campaign.
文摘Radioactive noble-gas isotopes, SSKr （half-life tl/2=10.8 y）, 39Ar （tl/2=269 y）, and SlKr （t1/2-229,000 y）, are ideal tracers and can be detected by atom trap trace analysis （ATTA）, a laser-based technique, from environmental samples like air and groundwater. Prior to ATTA measurements, it is necessary to efficiently extract krypton and argon gases from samples. Using a combination of cryogenic distillation, titanium chemical reaction and gas chromatography, we demonstrate that we can recover both krypton and argon gases from 1-10 L ＂air-like＂ samples with yields in excess of 90% and 98%, respectively, which meet well the requirements for ATTA measurements. A group of testing samples are analyzed to verify the performance of the system, including two groundwater samples obtained from north China plain.
文摘In Belgium,the Boom clay was selected as a potential host formation for the disposal of high-level radioactive waste（HLW）.To demonstrate the suitability of Boom clay for bearing thermal load induced by the HLW,a large-scale in-situ heater test,called PRACLAY heater test,will be conducted in the underground research laboratory（URL） in Mol.Owing to the limitations of the test（a short period of time compared with that considered in a real repository,different boundary conditions,etc.）,the test is designed to simulate,in a conservative way,the most critical state and phenomena that could occur in the host rock.The PRACLAY gallery was excavated at the end of 2007;the heating phase will begin in 2010 and will last for at least 10 years.The PRACLAY gallery itself leaves an opportunity to study the possibilities of sealing a disposal drift in Boom clay and testing the feasibility of hydraulic cut-off of any preferential pathway to the main access gallery through the excavation damage zone（EDZ） and the lining with a seal in a horizontal drift（horizontal seal）.Indeed,this is a generic problem for all deep geological disposal facilities for HLW.An annular seal made of compacted swelling bentonite will be installed in the front of the heated part of the PRACLAY gallery for these purposes.This paper provides detailed considerations on the thermo-hydro-mechanical（THM） boundary conditions for the design of the PRACLAY heater test and the seal test with the support of numerical calculations.It is believed that these important items considered in the PRACLAY heater test design also constitute key issues for the repository design.The outcome of the PRACLAY heater test will be an important milestone for the Belgian repository design.
文摘Underground research laboratories （URLs）, including ＂generic URLs＂ and ＂site-specific URLs＂, are un- derground facilities in which characterisation, testing, technology development, and/or demonstration activities are carried out in support of the development of geological repositories for high-level radioactive waste （HLW） disposal. In addition to the generic URL and site-specific URL, a concept of ＂areaspecific URL＂, or the third type of URL, is proposed in this paper. It is referred to as the facility that is built at a site within an area that is considered as a potential area for HLW repository or built at a place near the future repository site, and may be regarded as a precursor to the development of a repository at the site. It acts as a ＂generic URL＂, but also acts as a ＂site-specific URL＂ to some extent. Considering the current situation in China, the most suitable option is to build an ＂area-specific URL＂ in Beishan area, the first priority region for China＇s high-level waste repository. With this strategy, the goal to build China＇s URL by 2020 mav be achieved, but the time left is limited.
文摘In view of the need for geomechanical safety analysis of repositories in salt rock, failure criteria,creep rupture criteria,material models,pillar design methods and criteria for the assessment of barrier efficiency as well as investigations of the interaction between hydraulics and mechanics for the case of uncontrolled flooded repositories are necessary. The introduction of damage mechanics and of the Hou/Lux material model including damages into geomechanical safety analysis of repositories in salt rock can reduce some previous deficits in knowledge and modelling. This article will be as a part of geotechnical assessment to introduce the Hou/Lux material model,a new concept of hydro-mechanical coupling and a pillar design method as well as criteria for the assessment of efficiency of geological barriers.
基金supported by the High-level Talent Research Launch Project, Chongqing Technology and Business University, under grant No. 950318066the Open Research Fund of the State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, under grant No. Z017010the National Natural Science Foundation of China, under grant No. 41688103
文摘Geological and hydrological characteristics, joint geometric features, rock physical and mechanical properties and rock mass quality are studied in the Beishan area, preselected for China5 s high-level radioactive waste(HLW) disposal engineering. A comprehensive survey method is developed to study joint geometric features in the outcrop and samples from borehole BS06 into the Xinchang rock mass were tested. The optimal joint sets are determined by rose diagrams and equal-area lower hemisphere plots of joint poles. Results show that: 1) the distribution of joint occurrence obeys a normal distribution, while the distribution of joint spacing obeys a negative exponential distribution; 2) concentric circular and tangent circular sampling windows are applied to study the trace length and the trace midpoint density. Results indicate that tangent circular sampling window is more stable and reasonable; 3) Beishan granite shows high density, low porosity and high strength based on many laboratory tests and the physical properties and mechanical properties are closely related; and4) a synthesis index, Joint Structure Rating(JSR), is applied to evaluate the quality of rock mass. Through the research results of rock mass characteristics, the Xinchang rock mass in the Beishan preselected area has the favorable conditions for China's HLW disposal repository site.
