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Here, we report a case of oral malodor that was diagnosed by bacterial examination. The patient (a 32-year-old female) visited our breath clinic because a family member advised her to do so. Strong oral malodor was detected by several tests including an organoleptic test, a portable sulfide monitor, and gas chromatography. She noticed her oral malodor, but her motivation toward treatment was low. Even after explaining the cause of halitosis and the importance of oral hygiene, her motivation did not improve. So we applied a bacterial examination, and explained the results in detail. She understood how oral bacteria had caused the oral malodor, and she tried to do tooth brushing better. After a basic periodontal treatment, her oral condition improved and the number of periodontopathic bacteria reduced. She continued with careful tooth brushing even after the periodontal treatment, and her breath odor remarkably decreased. This case report indicates the usefulness of bacterial examination for motivating patients to improve their oral hygiene.

Many people worry about their breath odor, and the importance of halitosis treatment is increasing. Consequently, it is necessary for dental hygienists to obtain a basic knowledge of halitosis. To achieve this, we must improve the motivation of dental hygienist students to acquire such knowledge. To this end, we conducted a questionnaire survey to assess the awareness and knowledge of the problem among dental hygienist students and compared the results of the survey for students in the first and third grades. The percentage of students who perceived the oral malodor of patients was higher in the third grade group. The third graders also placed a greater importance on the participation of dental hygienists in halitosis treatment. Most students in both grades believed that demand for halitosis treatment would increase, although there were students in the first grade that did not hold this view. A similar percentage of students in the two grades were willing to study halitosis, although some first grade students were not at all interested. Many more students in the third grade wanted to take part in halitosis treatment. Student knowledge of halitosis was approximately the same in both grades, but, surprisingly, the third graders gave some incorrect answers in this area. From the results of this study, the third grade students appeared to have higher motivation to study halitosis treatment than the first graders. However, the upper grade students seemed to lack some knowledge, which may be due to the extended time since they had studied the topic at school. It is necessary for us to improve student motivation for studying halitosis and for maintaining their knowledge in order to better perform the treatment of halitosis after the students become dental hygienists.

It is often necessary to use subjective information such that all effective information is used in decision making problems. The methods and key issues for the technical use of subjective information are analyzed. We present a technique for using subjective information about the time of liner leak for the planning of optimal groundwater remediation in an uncertain transmissivity field. The technique uses Monte Carlo simulation and Bayesian estimation theory. We also present applications of the technique to a fictitious problem. The results show that the prior distribution significantly affected optimal design planning. Therefore, the complete exclusion of subjective information may result in an unrealistic overestimate of uncertainty and hinder optimal planning.

Two major sources of acid deposition are SO2 and NOx. These are oxidized in the airto Sulfuric Acid and Nitric Acid. From Akimoto et al's5) data on the generation of SO2 and NOx in Eastern Asia, amount of acid deposition and concentration of SO2 and NOx, in the air at Fulcui were estimated and compared with observedvalues. Observed SO2 and NOx, are higher than that of estimated, especially NOx, concentration is about one order high. This may due to many assumptions used for estimaticm Further study will be focused on this discrepancy between observed and estimated values.

Our field survey showed that thequality of shallow groundwater around the KatsuraRiver in the Kyoto Basin was strongly affected by theinfiltration of river water. Furthermore, that thedeterioration of the groundwater in the southern areato the west of the Katsura River may be related to theincrease in groundwater extraction. To clarify themechanism of groundwater deterioration, we havedeveloped a stochastic method to simulate groundwaterflow. The results showed that there was a largereduction in the groundwater level where groundwaterextraction was intense and recharge flowed from theKatsura River to the high extraction areas in thesouthern region. Another simulation showed that if thegroundwater extraction was 10% of the present removalrate, there would be little recharge from the KatsuraRiver into the groundwater and the quality of thegroundwater would be improved. Thus, we conclude thatthe cause of groundwater deterioration is probably dueto the induced recharge of deteriorated river waterfrom the Katsura River.

Two major sources of acid deposition are SO2 and NOx. Amount of NOx from East Asian Countries has been calculated and compared with that of SO2. As the air passes through on the same route, contribution of each asian countries to the acid deposition at fukui showed similar pattern.

Air at Fukui in 1993 was traced by Inverse-Trajectory method. Air at Fukui comes from China mainland from October to next May when Siberian anticyclone is superior. In July and August air comes fmm Pacific Ocean, while June and September comes from almost all directions. SO2 load in East Asia was estimated by Akimoto et al. Using Eliassen's dispersion and chemical reaction formulae, origin of acid deposition to Fukui was estimated. Fukui is situated close to Japan Sea so that contribution of China mainland reaches up to 90%, but during the summer season no pollution comes from China. Not only artificial sources, but volcanoes discharge SO2 in the air. In Kyushu Islands amount of SO2 discharged is much more than artificial ones. Sakurajima, Aso and Suwanosejima are three main volcanoes whose SO2 release affects the acid deposition at Fukui. In 1993, maximum portion of volcanic vent to the total acid deposition at Fukui was about 40%.

137Cs released from atmospheric nuclear detonation tests has been transported worldwide in the environment and finally taken up by humans through various pathways. In particular, ingestion pathways are important for evaluating the human health risks caused by the chronic global low-level radioactive contamination. In this research, the mathematical model for the evaluation of the dietary intake of 137 Cs and the related risks to Japanese are proposed by coupling the previously published global 137 Cs distribution model with the regional models such as various food ingestion models and the model of the domestic and international supply. Predictions from the proposed model were compared with the monitoring data of 137 Cs in Japanese total diet as an attempt at validation. The major findings obtained in this research include that the proposed model is promising for evaluating tbe risk to Japanese health caused by the dietary intake of global radioactive fallout 137 Cs, the 137 Cs is taken up by Japanese mostly through farm products, the ingestion of 137 Cs through imported foods is increasing, the risk to the Japanese health of inducing cancer by 137 Cs internal exposure reached a maximum in 1963, gradually decreasing to the lowest present level, and the risk to infants is the highest.

Fukui Prefecture faces Japan Sea and receives air pollution from China mainland. China shows more than 10% per year of high economic growth and uses coals with high sulfur content as main resources of energy. It is afraid that Fukui would receive severe damage by acid deposition in the future. Air which arrives at Fukui is simulated by inverse trajectory analysis. Air at Fukui arrives from China mainland from October to April, and from Pacific Ocean in July and August. Other months are transient of winter and summer season, air comes from almost all direction.

地下水汚染機構の研究などのため, よく土壌カラムを用いた実験が行われる. このとき土壌カラム中の水分と物質の移動を実時間で追跡する方法として, インピーダンスを測定する方法の有効性を検討した. このため測定システム全体をコンピューター制御した土壌カラムのインピーダンス測定システムを構成し, 一定温度下において不飽和土壌カラム中の水分物質移動の測定実験を行った. その結果, サセプタンス/角周波数を測定することにより, 土壌粒径や濃度に関係なく含水率の測定が可能であることが, 加えてコンダクタンスを測定することにより, イオン濃度に比例する土壌溶液の導電率の測定が可能であることがわかった. また検量線の簡便な作製方法も提案した. 本研究で開発した方法は不飽和浸透現象の実時間追跡などにおいて極めて有効である.

長崎大水害を対象にして, 廃棄物処理システムが直接的・間接的に被害を被る場合に, 災害ごみを含めて廃棄物流動がどのように変化するかを評価するための数学モデルを構築した。水害後に実際に採用された廃棄物対策がそれぞれ講じられない場合を想定し, 廃棄物流動をシミュレーションにより推定し, 講じられた対策の効果を評価した。本研究により得られた主要な結論を要約すると以下のようになる。(1) 構築した数学モデルは, 廃棄物処理システムを構成するプロセスが一時的に機能を喪失する条件下での, 廃棄物流動を説明するモデルとして利用することができる。(2) 水害後に採用された廃棄物対策の内では, 発生源での廃棄物滞留を早期に解消する面からは, 輸送能力の増強や一時保管場の設置等の効果が著しく, 仮焼却 (野焼き) の効果は大きくなかったといえる。(3) 廃棄物処理システムを構成する各プロセスの処理能力や輸送能力等の増強は, システム内での廃棄物流動が過不足なくバランスするように調整された場合に, その効果が最大になる。

わが国における紙資源のライフサイクルを評価するために構築した数学モデルを用いて, 紙資源のリサイクルの推進によって, 物質としての紙資源の流動がどのように変化するかを解析した。紙資源ライフサイクルの要素プロセスにおけるエネルギー原単位, 費用原単位を推定し, ライフサイクル全体の資源消費, エネルギー収支関係や費用収支関係が, 古紙リサイクルの推進によって現状からどのように変化するかを定量的に検討した。古紙の資源としての回収とエネルギーとしての回収との間にはトレードオフが成立する可能性があるが, 熱エネルギーの回収レベルが低い現状では現実的な意味を持たないこと, 製紙部門による古紙の買い入れ価格と古紙回収費用の組み合わせによって, 製紙部門および廃棄物処理部門の費用負担パターンが異なること, 費用負担が減少する部門から増加する部門へ, 費用負担の減少分の一部を移す施策を導入することにより, 古紙回収が経済的に促進される可能性があること等を明らかにした。

The activated charcoal passive collector method can be applied to measure the concentration of 222 Rn in river water. The 222 Rn collector is composed of dry activated charcoal sealed in a polyethylene bag. However, we found it very difficult to keep activated charcoal in a collector dry during the period the collector was left in a river. The degree of dampness and the time lapsed when activated charcoal became wet were thought to affect the quantity of 222 Rn collected. First, we studied the effect of some parameters in the activated charcoal passive collector method qualitatively in three experiments. We found that the quantity of 222 Rn collected in a collector was not so sensitive to the quantity of activated charcoal in the collector or the thickness of polyethylene film under the condition of wet activated charcoal, and that wet activated charcoal accumulated less 222 Rn than dry activated charcoal. We present some equations which could explain how much 222 Rn was collected in a collector when activated charcoal was submerged directly in water and when activated charcoal was packed in a polyethylene bag but completely wet. These equations were proved effective by being compared with the results of the other experiments. Finally, we recommended some conditions which proved useful when measuring at an actual river.

The distribution coefficient (Kd) of material between soil and soil solution is one of the most important factors in evaluating the transport of pollutant from soil to plant root. However, Kd value varies largely depending on the environmental conditions. Therefore, careful examination for conditions is necessary when reported Kd value is to be used for assessment of material transport in the ground.In this study, effect of three environmental factors (temperature, soil-pH, and co-existing ions) on Kd of zinc was investigated by batch and column experiments. The results obtained are as follows:1) Linear relationship was derived in the batch experiment between logarithm of Kd of zinc and that of cation equivalent in the equilibrium solution.2) Effect of soil-pH on Kd of zinc became larger at lower ion concentration.3) Effect of temperature on Kd of zinc was relatively small compared with the effect by the other two factors.4) Physicochemically, equilibrium soil must be used for Kd determination by the column method. Ten pore volumes of influent solution were required to get the stationary ion composition in the column effluent.5) Kd value determined by the column method was almost equal to that determined by the batch method.

廃棄物処分場跡地と対照地区から土壌とクローバーを採取し, 放射化分析法により希少元素濃度を測定した。土壌中濃度は, 26元素中14元素で廃棄物処分場跡地の方が有意に高かったが, 人為的な汚染があるとは断定できなかった。希土類元素のクローバー中濃度は非常に低く, 植物に吸収されにくい形態で環境中に存在することが示唆された。比較的高いクローバー中濃度を示した希少元素は, 第4周期以降の必須元素と同族の元素であった。

Transfer factor (TF) is defined as the amount of material in the plant tissue divided by that in the soil. It is widely used to predict the amount of radionuclides transferred from the soil to edible parts of plant. But TF value varies greatly due to environmental factors and other growth conditions. In order to predict the precise amount taken up through plant roots using TF, the effect of those factors on TF should be considered.In this study, a model to estimate TF through plant root was proposed. This model is described as follows:TF=S·Tc/θr+Kd, where S is the selectivity [-]; Tc, the transpiration coefficient [ml/g]; θr, the soil water content by soil weight [ml/g]; and Kd, the distribution coefficient [ml/g].In experiments, the fluctuation range of S was investigated. The S was not affected by the zinc concentration level in nutrient solution when there were less than 0.15mmol zinc/l. The decrease of co-existing ion concentration in nutrient solution increased S, but the effect was considered to be small if no problem with the plant growth was observed. The TF calculated from the proposed model had considerably good agreement with the actual TF.

An optimum monitoring well network (number of wells and their locations) is proposed which enables rapid, redundant and economical detection of contaminants in groundwater around a solid-waste landfill site. The procedure also guarantees detection of the contaminants given data on the probability of detection at different points in the saturated zone. The well selection is accomplished using a two-step procedure: 1. (1) A Monte Carlo simulation of contaminant transport in the unconsolidated shallow saturated zone is conducted. In this zone hydrogeological parameters are variable but their stochastic distributions are known. Three governing equations are solved numerically using the finite-difference method to obtain the travel time distribution of each contaminant: the two-dimensional steady-state groundwater flow equation; the two-dimensional transient convective-dispersion equation for sorptive contaminants; and the sorptive-desorptive isotherm equation. 2. (2) The procedure utilizes “fuzzy” theory, comprising of a set of newly developed mathematical techniques to deal with uncertainty in a wide range of man-machine interface issues, to assist in the design of a monitoring well network. The procedure requires a mathematical description of a four-attribute design problem using fuzzy utility functions and fuzzy weights. An optimum monitoring well network is then defined as the network having maximum total utility, which is evaluated as a fuzzy expectation of weighted arithmetic sums of the four utilities. One result of the simulation is the definition of relationships between the contaminant of interest and precursor materials. The precursor material can then serve as an “indicator” for faster detection of contaminant leaked from solid-waste landfill site. The procedures are applied to a hypothetical solid-waste landfill site under appropriate conditions to obtain the optimum monitoring well network for detection of precursor indicators. Sensitivity analysis of the optimum network was conducted by considering changes in components of the mathematical description of the design problem. Components which were changed include total utility evaluation, quality of uncertainty in weight factor and utility evaluation, weigth level determination, delay time requirement, well number limitation and perfect detection constraint.

A new method to measure 222 Rn concentration in water is described. This method is an application of the activated charcoal passive collector method, which is sometimes used for measurement of 222 Rn concentration in air. The model and the equation which express the quantity of 222 Rn adsorbed in activated charcoal in the collector were constructed, inspected experimentally, and proved to work well enough for the measurement of relative concentration of 222 Rn in water. We used this method to measure the 222 Rn concentration in water at ∼ 20 points in an actual river. Based on the fact that the concentration of 222 Rn in ground water is generally much higher than that of surface water, we found several possible groundwater seepage points along the river. For the absolute measurement of 222 Rn concentration in water by this method, it would also be necessary to investigate the effect of temperature on the quantity of 222 Rn collected in a collector.

Fallout {sup 137}Cs from atmospheric nuclear detonation test have been monitored worldwide since the late 1950`s. The deviation and the correlation among these monitoring data were analyzed, and their surface deposition characteristics were estimated by the compartment model developed in this research. In the analysis, the scale of space (i.e., size of each compartment) and the degree of detail (i.e., number of compartments) were statistically determined using the global distribution data of {sup 137}Cs. The mathematical model was evaluated by comparing the numerically simulated results with the fallout monitoring data including the {sup 137}Cs concentration in sea water. The major findings obtained in this research include that the deposition pattern of {sup 137}Cs is dependent on the latitude zone but not on the longitude, the mathematical model is promising for evaluating the dynamic performance of {sup 137}Cs in global atmospheric environment and its surface deposition, {sup 137}Cs is accumulated more in both the surface and deep ocean water of the North Pacific Ocean and the North Atlantic ocean than that of other oceans, the {sup 137}Cs inventory is decreasing after the peak time in 1965, and the {sup 137}Cs inventory in the deep ocean water is decreasing more slowly thanmore » that in the surface ocean water. 26 refs., 10 figs., 3 tabs.« less

Distribution coefficients between sample soil and water were determined for 17 soil samples and 9 radionuclides by batch and/or column method. Those experimental data were analyzed on some environmental factors, such as macro ionic component in liquid phase, percolation rate of water through soil column, saturation degree of the soil pore with water, cation exchange capacity of soil and so on, which might have large influence on a variation of kd. Some instructive results were obtained such as: (1) Relative magnitude of kd for 90Sr, 137Cs and 60Co does not depend on the sample soil. kdos is the largest among 3 nuclides and is followed by kdco. kdSr is the smallest. (2) kd for calcium rich soil might be estimated mainly based on Ca+Mg concentration in water phase, and kd for calcium poor soil based on pH in water phase. (3) Positive correlation is observed between kd of 90Sr and cation exchange capacity of soil. (4) kd for unsaturated soil with water are observed to be larger than kd determined for saturated soil with water. (5) 90Y, 110mAg and 59Fe among 9 nuclides used in this work might be stable in non-ionic form in water.

This paper describes the importance of a food chain to estimate the concentration of heavy metals from the viewpoint of nutrition ecology. The experiments were performed to investigate the effects of the following experimental conditions on the uptake of heavy metals by a predator, using 137Cs as a tracer; ration size per day, feeding interval and the change in weight of the predator fish. Top minnows (Oryzias latipes) were used as preys and Golden astro (Astronotus ocellatus) as predators. The preys were raised without feeding in an aquarium and the predators were fed top minnows. The set of results showed that (1) the concentration of a metal in predator fish increased with the ration size, (2) the feeding interval had no effect on the uptake of the metal by fish under the experimental conditions performed, and (3) the concentration in the growing fish was suppressed increasing in value with the increase of its weight. They suggest the importance of generalization of the experimental food conditions when the study on the concentration process of heavy metals through a food chain is performed. The paper also deals with the compartment model applied to the concentration process of the metal by a fish. The theoretical results depicted well the experimental ones.

The flow rate and sediment concentration of inflow into settling basins usually vary with respect to time; thus the sediment concentration of effluent also varies following these variations. This sediment concentration variation of settling basin effluents was analyzed theoretically by a lumped-parameter model. The resuspension of deposits from the bottom of the basin by scouring was taken into account in the computation of effluent concentration. Some numerical calculations are carried out and the results prove that the flow rate of settling basins should be carefully controlled because if the volume of water in the basin decreases greatly the sediment concentration in effluent increases sharply.

In order to estimate and evaluate the radioactivity concentration in an aquatic ecosystem, the transfer of radioactivity through a food web should be considered. In this paper, systems analysis on the above problem was performed and a quantity of radioactivity in organisms concentrated through their diet was presented. It was found from numerical evaluation that whether the transfer of radioactivity through a diet is significant or not depended on such ecological factors as ration rates, assimilation rates, uptake rates and turnover rates, etc. The degree of the importance of these parameters on the concentration process of radioactivity was quantitatively evaluated by the mathematical technique of sensitivity analysis.

This paper proposed the food condition factor ⌈, which unifies the population density and aggregation index of prey organisms from the viewpoint of the nutrition ecology in the case of modeling the concentration process of heavy metals by aquatic organisms. By using this factor ⌈, we can generalize the food conditions when the experimental researches on the biological concentration process of trace heavy metals through a food chain are performed. Simulation analysis by computer on the concentration process of metals by a fish is made on the basis of the mathematical model described in this paper for the case that the weight of a fish increases with time. The change in weight of a fish is assumed to obey the logistic curve. The simulation results show the biological dilution of the metal concentration in an organism due to increase in the weight of a fish. Under the simulation situation conditions, however, the effect of the growth rate of a fish on the biological dilution was found to be small.

A dynamic parameter estimation method for the settling basin model is brought out on the assumption that a continuous-valued time-varying parameter can be approximated with a sequence of discrete-valued time-invariant parameters by dividing a time interval into short subintervals in which the parameter is allowed to be time-invariant. Employing test data, the model parameter and the effluent concentration are calculated to confirm the applicability of the method. The method is also applied to the primary settling basins in a municipal wastewater treatment facility to determine its practicability. The calculated results with both the test and plant scale data show that this method is a useful tool for the dynamic prediction of the effluent sediment concentration of settling basins.

The use of ion-exchange materials for the removal of radioactive iodine from air streams was investigated. Experiments were carried out with ion-exchange resin, liquid ion-exchanger and other materials to evaluate the removal efficiency and factors affecting the removal. Results are as follows:(1) A packed column of Amberlite-IRA-400-OH showed a high exchange sorption capacity for gaseous iodine. The rate of iodine transport from air stream to resin phase and the rate of ion-exchange were estimated to be both sufficiently high.(2) A larger decontamination factor for radio-iodine (3.5×103) was obtained with Amberlite column than with either activated charcoal, copper ball or molecular sieve, under conditions of identical pressure loss.(3) The presence of 50% CO2 in air stream interfered little with the exchange ability of Amberlite, due to the large mass. action constant between I- and CO3-.(4) Tris (2-ethylhexyl) amine showed a somewhat smaller removal efficiency than solutions of eilther silver nitrate, sodium hydroxide or sodium thiosulfate, under conditions of identical volume and concentration.

The transport of a cationic radionuclide through the earth was determined by hydrodynamic convection, hydraulic dispersion, and ion-exchange sorption. If the manner of water movement is first asdertained by tritiated water tracer measurements and the exchange properties are determined by laboratory tests, it is possible to predict the arrival of individual radioisotopes at some distant point of concern. For the prediction theory to be fully applicable, the formation should be reasonably homogeneous, the isotope distribution factor should remain constant, and exchange equilibria should prevail at all points. It is also desirable that the hydraulic flow net remain unchanged. The validity of the prediction theory was tested with laboratory columns and with a field investigation. The field test involved several arrays of injections and relief wells and twenty-three observation wells penetrating a confined aquifer 100 ft below the earth's surface. The results demonstrated the theoretical validity and practical utility of the theory. (auth) H03 H0237001 Boiling Water Reactors. Zero-power experiments were carried out on the central superheater core CSH-1 of BORAX V. The chemistry of the reactor cooling water was followed. The maintenance and development involved in BORAX V are described. Liquid-Metal-Cooled Reactors. Central reactivity coefficient and Doppler coefficient measurements aremore » reported for a 4000-liter core in Assembly 43 of ZPR- III. Development of fast reactor fuels is described. The operation of EBR-1, Mark IV and EBR-II is described. The fuel cycle facility and process development of EBR-II are also considered. The design studies and other development work on FARET are discussed. General Reactor Technology. Nuclear physics studies which were made included Doppler effect calculations, numerical integration of differential equations, and development of a solid-state fast neutron spectrometer. Corrosion studies on reactor materiais are described. The development of ceramic and particulate metal fuel elements is discussed, and the irradiation and extrusion studies are described. Among the chemical studies carried out were the formation of Tc/sub 2/ Zn/sub 11/in Tc-- Zn, dissolution of U in flowing liquid Cd, thermal decomposition of UO/sub 2/Cl/sub 2/ in molten LiCi--KCl, solubility of U in Cd--Mg--Zn alloys, fluidization and volatility separation processes, preparation of UC and US, analysis of PuF/sub 6/, solubility of Ar in Na, etc. In the Plutonium Recycle Program, the cross-section correction factors for the Pu region and the building of Sm/sup 149/ in the reactor zones are discussed. Advanced Systems Research and Development. The operation of a thermionic flim-boiling liquid-metal diode with cesium is described. The design of a nuclear magnetohydrodynamic system (fast reactor coupled with liquid-sodium MHD generator) was analyzed, and the system characteristics are tabulated. Nuclear Safety. Oxidation studies were carried out on Pu and Pu--2 at.% Al alloy. The Al--U/sub 3/O/sub 8/ thermite reaction and the vapor-phase burning of Al in water were studied. In-pile oxidation studies in air were made on one sample of U and one sample of a U-Fs alloy. (D.L.C.)« less

The decontamination factor of an ion exchange column for radioactive liquid wastes was ascertained with respect to the water quantity treated. Refering to the conventional theories applied to ordinary industrial waste water, this problem was theoretically solved, dividing the phenomena into two cases of equal and of different valency. Finally, a formula representing the average quality of the treated water was proposed. Furthermore, in order to check the above heory, a laboratory study was carried out, which gave a good result considerably matched with the theoretical one. The property of such materials as clays and zeolites was also tested and compared for their usage as the ion exchanges for this type of treatment.

The movement through soil of radioactive nuclides contained in chemical processing waste was investigated. Theories governing this movement, including the authors' were first reviewed. Experiments were carried out with 90Sr and 137Cs in IN-HNO3 to Simulate waste. This simulated waste was passed through a column packed with sand and the behavior of these radionuclides in the column was observed. The breakthrough curve of 90Sr was very Similar to the curve of the waste, while 137Cs showed a curve about 60 times slower than the waste. It can thus be concluded that 90Sr in actual wastes travels with the ground water, while 137Cs moves about 60 times slower. These results can be explaned by the authors' theory.

While so far emphasis has been placed on the treatment of radioactive wastes, consistent procedures from the treatment phase to final disposal, especially underground disposal, is in overseas countries, ideas for waste disposal, techniques available at present, and their economic aspects are reviewed. Prospects of underground disposal in Japan and subjects of research in this field are discussed. Radioactive waste disposal in oceans, underground, in cosmic space, and in-reactor is discussed. Underground disposal is carried out for solid and liquid wastes at different radioactivlty levels and of gaseous wastes. Location of ground-disposal sites is determined by the return of radioactive substances to human beings through varied routes. Finally, the problems encountered in the disposal of solid wastes from nuclear power stations are indicated. (JA)