18,640 research outputs found
A methodology for determining optimal durations for the use of contaminated crops as fodder following a nuclear accident using a dynamic food-chain model
No full textA methodology for determining optimal durations for the use of contaminated crops as fodder was designed based on cost-benefit analysis. Illustrative results of the application of this methodology to pigs are presented for the hypothetical deposition of radionuclides on August 15 when a number of crops are fully developed in Korean agricultural conditions. For investigating the appropriateness of the use of contaminated crops as fodder, the net benefit from this action was compared with the imposition of a ban on human consumption of contaminated crops without alternative use. The time-dependent radionuclide concentrations in crops and pork after the deposition event were predicted from a dynamic food-chain model DYNACON. The net benefit from the actions was quantitatively evaluated in terms of cost equivalent of the doses incurred or averted and the monetary costs needed to implement the action. The optimal duration for the use of contaminated crops as fodder depended on a number of factors such as radionuclide, variety of crops fed as fodder and duration of the action. Such action was more cost effective for Cs-137 deposition than for Sr-90 or I-131 deposition. The use of contaminated crops as fodder can be an effective response to a public reluctance to consume contaminated crops. (C) 2000 Elsevier Science Ltd. All rights reserved
A methodology for optimisation of countermeasures for animal products after a nuclear accident and its application
No full textA methodology for the optimisation of the countermeasures associated with the contamination of animal products was designed based on cost-benefit analysis. Results are discussed for the hypothetical deposition of radionuclides on 15 August, when pastures are fully developed in Korean agricultural conditions. A dynamic food chain model, DYNACON, was used to evaluate the effectiveness of the countermeasures for reducing the ingestion dose. The countermeasures considered were: (1) a ban on food consumption; and (2) the substitution of clean fodder. These are effective in reducing the ingestion dose as well as simple and easy to carry out in the first year after deposition. The net benefit of the countermeasures was quantitatively estimated in terms of avertable doses and monetary costs. The benefit depends on a variety of factors, such as radionuclide concentrations on the ground, starting time and duration of the countermeasures. It is obvious that a fast reaction after deposition is important in maximising the cost effectiveness of the countermeasures. In most cases, the substitution of clean fodder is more cost effective than a ban on food consumption. The methodology used in this study may serve as a basis for rapid decision-making on the introduction of countermeasures relating to the contamination of animal products after a nuclear accident. (C) 1999 Elsevier Science Ltd. All rights reserved
Development of a dynamic food chain model DYNACON and its application to Korean agricultural conditions
No full textA dynamic food chain model DYNACON was developed to simulate the radionuclide transfer on agricultural ecosystems. DYNACON estimates the radioactivity in each compartment of food chains for three radionuclides, nine plant species and five animal products as a function of the deposition date. A number of the parameter values used in this study are representative of Korean agricultural conditions. The model was expressed by coupled differential equations and the radioactivity in each compartment was solved as a function of time following an acute deposition. Although DYNACON is structurally based on existing models, it was designed in order to simulate more realistic radionuclide behavior in Korean agricultural conditions and to save computation time. It was found that the radioactivity in foodstuffs depends strongly on the date of deposition. A comparative study between DYNACON and an equilibrium model showed good agreement for depositions that occur during the growing season of plants. DYNACON is going to be implemented in a Korean rear-time dose assessment system FADAS
Seasonal influence of countermeasures for milk after a nuclear accident
No full textThe seasonal influence of countermeasures for milk after a nuclear accident was investigated using a quantitative decision-aiding technique, cost-benefit analysis. The 15th day of April and July was selected as a typical deposition date of radionuclide for growing season and non-growing season of pastures, respectively. A dynamic food chain model, DYNACON, was used to evaluate the effectiveness of countermeasures for reducing the ingestion dose. The countermeasures considered are (1) a ban on milk consumption and (2) the substitution of clean fodder. The net benefit from the countermeasures was quantitatively evaluated in terms of cost equivalent of avertable doses and monetary costs of implementing the action. It showed a distinct difference for the different deposition seasons of radionuclides. Obviously, the rapid introduction of a countermeasure after a deposition was important in maximizing the cost effectiveness. In most cases, the substitution of clean fodder was more cost effective than a ban on milk consumption
SPHERICAL APPROXIMATION IN GAMMA DOSE CALCULATIONS AND ITS APPLICATION TO AN EMERGENCY RESPONSE ACTION AT KORI REACTOR SITE IN KOREA
No full textAn approximate method for estimating gamma external dose given from an arbitrary distribution of radioactive material has been developed. For the assessment of external gamma dose, the space over which radioactive material is distributed is assumed to be composed of rectangular cells. The evaluation of three-dimensional integration over the space is an extremely time-consuming task. In this study, a regular hexahedron is modeled as a volume-equivalent sphere to simplify the integration. A comparative study with a point source approximation and the Monte Carlo integration method shows that the present method gives reasonable results in a physical sense. An accident consequence assessment model has been integrated using the Gaussian puff model and an external gamma dose has been assessed for Korean meteorological data. A procedure useful for selecting the most effective protective action to a given environmental condition is also provided here
Secondary neutron dose assessment from proton therapy using passive scattering at the National Cancer Centre (NCC)
No full textUse of swine wastewater as alternative substrate for mycelial bioconversion of white rot fungi
No full textSeven white rot fungal species were tested for growth as mycelia using swine wastewater (SW), an agro-waste with tremendous environmental footprint, as the sole nutrient source. The SW contained high concentrations of carbon and nitrogen components, which could support nutritional requirements for mycelial growth. Out of the seven species, Pleurotus ostreatus and Hericium erinaceus were successfully cultivated on the SW medium using solid-state fermentation. Response surface methodology was employed to determine the combination of pH, temperature (T), and substrate concentration (C) that maximizes mycelial growth rate (Kr) for the two species. The optimum condition was estimated as pH = 5.8, T = 28.8 A degrees C, and C = 11.2 g chemical oxygen demand (COD)/L for P. ostreatus to yield Kr of 11.0 mm/day, whereas the greatest Kr (3.1 mm/day) was anticipated at pH = 4.6, T = 25.5 A degrees C, and C = 11.9 g COD/L for H. erinaceus. These Kr values were comparable to growth rates obtained using other substrates in the literature. These results demonstrate that SW can be used as an effective substrate for mycelial cultivation of the two white rot fungal species, suggesting an alternative method to manage SW with the production of potentially valuable biomass.110Nsciescopu
Analysis of 1/f noise in CMOS preamplifier with CDS circuit
No full textNoise of CMOS charge-sensitive preamplifier (CSA) and correlated double sample-and-hold (CDS) circuit matching a capacitive source is calculated to analyze the relative portions of thermal and 1/f noise. In most radiation detector systems, a PMOS transistor is used as the input device because its 1/f noise is lower than that of the NMOS. However, to study the 1/f noise reduction action of a CDS circuit in the 1/f noise dominant condition, an NMOS transistor is deliberately chosen as the input transistor of the CSA. The theoretical minimum number of equivalent noise charge (ENC) that can be achieved in this system is about 1700 electrons, rms for a 5-pF detector capacitance. To demonstrate the theoretical analysis, a chip of CSA and CDS was designed in a 0.5-mum CMOS technology. The main amplifier is a differential input single-ended folded cascode, and its measured gain bandwidth is more than 5 MHz. The measured ENCs of the CSA shaper and the CSA-CDS systems are 2105 and 3046 electrons rms, respectively.This work
was supported in part by the Korea Ministry of Science and Technology
A Study on the Application of Countermeasure for the Reduction of the Ingestion Dose After Nuclear Accident
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