Nuclear reactor accidents, behavior

Suppose a chamber is filled with an aerosol that is kept well-mixed. The particles are coagulating and at the same time settling and diffusing to the walls. This type of model has been used to analyze the behavior of radioactive particles generated in a nuclear reactor accident and then collected in a vessel specially designed for the purpose. The contents of the containment structure are mixed as a result of natural convection induced by temperature gradients present under postaccident conditions. The effectiveness of the... 

The present study reports measurement methodology and features of the migration behavior of atmospherically derived radionuclides ( s, Pb, and Be) and includes data from previous studies (Matsunaga et al., 1991, 1995, 1999) of two Japanese watersheds. In addition to the good traceability of Cs, the choice of this radionuclide was rational for us because it is a major radionuclide and important in a nuclear accident because of its abundance in nuclear reactors and its volatility. Though, the present report is for radionuclide elements, the present findings could provide suggestions for the fate of other trace elements. 

Recent probabilistic risk assessments [In-5-9] establish that there is room for accident management to influence the consequences of reactor accidents. These risk assessments show there to be orders of magnitude uncertainty in the radionuclide releases as a result of accidents at nuclear power plants. A very significant portion of this uncertainty comes from uncertainty in the details of radionuclide behavior that can be influenced by accident management measures. The accident management measures taken to affect the radionuclide source term are not necessarily distinct from those taken to arrest or... 

The complexity of the heat transfer processes in nuclear reactor core requires computer codes to handle both local and system-wide behavior under normal, transient, and accident conditions. The code models are assessed with experimental data to ensure that they were working properly. Some of the largest and most widely used codes in United States are as follows ... 

Vinjamuri, K., Osetek, D. J., Hobbins, R. R. (a) Tellurium behavior during and after the TMI-2 accident. Proc. 5. Internat. Meeting on Thermal Nuclear Reactor Safety, Karlsruhe 1984, Report KfK 3880/3, p. 1583-1592... 

Pressure Behavior in a Nuclear Reactor Containment following a Loss of Coolant Accident", by M.S. Khattab, N.A. Ibrahim and S.D. Bedrose, AEA Cairo... 

The proceedings of these conferences provide insight on computer codes used to predict the behavior of aerosols in reactor containments under accident conditions. More technical details can be found in M.M.R. Williams and S.K. Loyalka, Aerosol Science Theory and Practice -With Special Applications to the Nuclear Industry, Pergamon Press, 1991. 

During reactor operation, small amounts of C are also formed in nuclear fuels. With regard to the radioactivity balance of the fuel during plant operation, this radionuclide is of no relevance however, considering its comparatively long halflife of 5736 years and its postulated release behavior from the fuel matrix under storage or accident conditions, it is of definite interest with respect to reprocessing or final disposal of the spent fuel. For these reasons, it is of importance to know the inventories as well as the chemical state of this radionuclide in the fuel. 

Taig, A. R. Release and retention phenomena in LWR degraded cores. Proc. Am. Nucl. Soc. Meeting on Fission Product Behavior and Source Term Research. Snowbird, Utah, USA, 1984 Report EPRI NP-4113-SR (1985), p. 5/1-14 US Nuclear Regulatory Commission (NRC) Reactor Safety Study An Assessment of Accident Risks in US Commercial Nuclear Power Plants, Appendix VII. Report WASH-1400, 1975... 

Beahm, E. C., Weber, C. F., Kress, T. S., Shockley, W. E., Daish, S. R. Chemistry and mass transport of iodine in containment. Proc. 2. CSNI Workshop on Iodine Chemistry in Reactor Safety, Toronto, Can., 1988 Report AECL-9923 (1989), p. 251—266 Beard, A. M., Bowsher, B. R., Nichols, A. L. Interaction of molecular iodine vapour with silver—indium—cadmium aerosol. Proc. International Symposium Severe Accidents in Nuclear Power Plants, Sorrento, Italy, 1988 IAEA-SM-298/108, Vol. 2, p. 201—213 Bell, J. T. Chemistry of iodine and cesium, in M. Silberberg (Report Coordinator) Technical Bases for Estimating Fission Product Behavior during LWR Accidents. Report NUREG-0772 (1981), Chapter 5... 

In the early years of nuclear power development, the cores of several research reactors in the US were deliberatedly damaged by experimental power excursions in order to study the behavior of the fission products under such conditions. To be sure, the characteristic data of these reactors, such as the nature of the nuclear fuel, the design of the safety installations, the construction of the buildings etc., showed great differences from that of modem power reactors so that the results are of only limited value for the assessment of severe accidents. However, certain qualitative impressions can be derived from these results, as can be seen from the summary paper of Smith (1981). 

M. F. Osborne, R. A. Lorenz, and J. L. Collins, "Atmospheric Effects on Fission Product Behavior at Severe Accident Conditions," Proceedings of the Ammican Nuclear Society International Topical Meeting on the Safety of Thermal Reactors, Portland, OR, July 25, 1991. 

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