The risk-based life-cycle management of engineering systems in a nuclear power plant is intended to ensure safe and economically efficient operation of energy generation infrastructure over its entire service life. An important element of life-cycle management is to understand, model and forecast the effect of various degradation mechanisms affecting the performance of engineering systems, structures and components. The modeling of degradation in nuclear plant components is confounded by large sampling and temporal uncertainties. The reason is that nuclear systems are not readily accessible for inspections due to high level of radiation and large costs associated with remote data collection methods. The models of degradation used by industry are largely derived from ordinary linear regression methods. The main objective of this thesis is to develop more advanced techniques based on stochastic process theory to model deterioration in engineering components with the purpose of providing more scientific basis to life-cycle management of aging nuclear power plants. This thesis proposes a stochastic gamma process (GP) model for deterioration and develops a suite of statistical techniques for calibrating the model parameters. The gamma process is a versatile and mathematically tractable stochastic model for a wide variety of degradation phenomena, and another desirable property is its nonnegative, monotonically increasing sample paths. In the thesis, the GP model is extended by including additional covariates and also modeling for random effects. The optimization of age-based replacement and condition-based maintenance strategies is also presented. The thesis also investigates improved regression techniques for modeling deterioration. A linear mixed-effects (LME) regression model is presented to resolve an inconsistency of the traditional regression models. The proposed LME model assumes that the randomness in deterioration is decomposed into two parts: the unobserved heterogeneity of individual units and additive measurement errors. Another common way to model deterioration in civil engineering is to treat the rate of deterioration as a random variable. In the context of condition-based maintenance, the thesis shows that the random variable rate (RV) model is inadequate to incorporate temporal variability, because the deterioration along a specific sample path becomes deterministic. This distinction between the RV and GP models has profound implications to the optimization of maintenance strategies. The thesis presents detailed practical applications of the proposed models to feeder pipe systems and fuel channels in CANDU nuclear reactors. In summary, a careful consideration of the nature of uncertainties associated with deterioration is important for credible life-cycle management of engineering systems. If the deterioration process is affected by temporal uncertainty, it is important to model it as a stochastic process.

This thesis involves exploring enhancement of estimating the probability of a critical station blackout in nuclear power plant operations by the use of direct numerical evaluation of multidimensional nonrecovery integrals. This requires development of computational methods with data provided from South Texas Project Nuclear Operating Company (STPNOC). Several methods that are currently used in the industry to estimate such probabilities often overestimate the value substantially. The computational integral method developed in the thesis will reduce excess conservatism while maintaining plant safety standards. This computational integral is calculated using a MATLAB research code referred to generally as "STP-TAMIL" which is for South Texas Project --Texas A&M Improved LOOP. The code itself (along with the user manual) was developed in conjunction with this Thesis. STP-TAMIL is successful in reducing the estimated probability of critical station blackout by a significant amount (about 88.47 percent ) with the incorporation of recovery of offsite and onsite power for South Texas Project̕ s nuclear plants, and results were verified. This thesis also describes an asymptotic justification for to the non-recovery integral used. Applications to the industry, or STPNOC, which will use the "TAMIL" code are addressed. Some assumptions used throughout the problem suggest that if more dynamic rates or distributions are used then more recovery can be obtained, which will decrease the probability of critical station blackout. Methodology developed in this thesis will be used in future work to develop this STP-TAMIL research code into a model used industry wide in commercial nuclear power plants.

Thesis (M. Soc. Sc.)--University of Hong Kong, 1988.

published_or_final_version / Mechanical Engineering / Master / Master of Philosophy

This study attempts to determine the factors which account for the fact that women are both more opposed and uncertain than men concerning the further development of nuclear energy. To that end, data from four national opinion surveys covering the period 1975-1979 are employed. Log-linear techniques are used in the analyses. Two plausible explanations for women's greater aversion to nuclear power are presented. The marginality explanation attributes the differential support of men and women for nuclear power to the differential positions which they occupy in the economic, political, and technical spheres within society. Because men hold more central positions in these areas, it is postulated that they will perceive a greater need for additional energy and continued economic growth, believe that the advantages of nuclear power toward these goals are greater, and be more confident in applications of nuclear technology. The fact that men express more favorable attitudes toward nuclear power is thus to be explained by these factors. The safety explanation attributes the sex difference to a greater concern on the part of women about the safety of using nuclear fission to generate electricity. The general thrust of this argument is that women's greater concern for safety revolves around their reproductive and nurturant roles, and the protection of future generations. Uncertainty is viewed as a special problem. An explanation for women's greater uncertainty, which attributes the difference to a sex-typed expectation concerning the formulation and expression of opinions on complex technical issues, is presented. Since children are socialized to view science and technology as primarily male fields, it is argued that the expectation to appear informed and provide opinions on technical topics like nuclear energy is less strong for women. The pattern of sex differences observed across a large number of survey items supports this view. With regard to the competing explanations for the sex difference in opposition to nuclear energy, the analyses support the safety rather than the marginality argment. Women are found to believe that nuclear power plants are less safe than men do, and to rate the problems of nuclear power as more serious. Controlling for these factors accounts for the sex difference in support for nuclear power, both in general and in respondents' local communities. Contrary to the implications of the marginality argument, women view our energy problems as more serious than men do, and there are virtually no sex differences with regard to the ratings given to various economic and other advantages of nuclear power. In line with the predictions of that argument, men are somewhat more likely to opt for producing energy over protecting the environment, and also more confident that the technical capability to rely more heavily on nuclear power currently exists. However, controlling for these factors fails to account for the sex difference. Additional topics addressed include the role of key opinion leadership groups in shaping the public opinion process concerning nuclear energy, and sex differences in reaction to the Three Mile Island accident. Women express greater confidence than men in environmentalists and Ralph Nader's organization, but no sex differences are found in confidence in scientists or the Nuclear Regulatory Commission. Hypothetical pro or con statements from each of these groups effect striking changes in the distribution of opinions of nuclear power. The magnitude of these changes in support vs. opposition is the same for both sexes. However, attaching the "expert opinion" results in a convergence of male and female uncertainty. Finally, the comparison of pre and post-TMI attitudes indicates a perception that the accident was more serious, and a greater increase in opposition to nuclear power among women.

No description available.

No description available.

No description available.

Nuclear safety is the main concern for the licensing of nuclear power plants, not only in the Republic of South Africa but also worldwide. The design of the nuclear power plant plays an important role in the licensing process, which includes probabilistic and deterministic analysis of a set of design or Licensing basis events. This study was about the deterministic analysis for the sensitivity of licensing basis events radiological consequences to different radiological pathways. The study was done for the Pebble Bed Modular Reactor (PBMR), which is a nuclear power plant, still in its early phase of design approaching its detailed design phase. An abnormal event or an accident could lead to a release of radioactive particles and gases from a Pebble Bed Modular Reactor and could give rise to radiation exposure to workers and the surrounding population. Therefore nuclear events due to PBMR, which are Licensing Basis Events or Design Basis Accidents, must be analysed in order to demonstrate that accidental and routine releases of radioactivity are kept As Low As Reasonably Achievable (ALARA) and that the design basis meets offsite dose requirements with adequate safety margins. In this work, it is also shown that collectively the risk criteria are satisfied in the fundamental safety requirements of National Nuclear Regulator (NNR) of the Republic of South Africa (RSA) and similar risk criteria of the other countries in which it has to be employed. Furthermore the various pathways through which radioactivity can reach the public are analysed. The focus of the study was to determine which pathways deliver the greatest radiation exposure if there is an accident due to an event happening in PBMR and also to provide a LBE analysis process as a step in confirming that the design meets the licensing requirements. / Thesis (M.Sc. ARST) North-West University, 2004

In the afterglow of Japan’s dramatic economic growth during the post-war period, the growth mentality is still apparent in contemporary Japan. The powerful business communities that helped the industrialization of the country are still structurally interconnected with the political elites. As a result, the growth interests of the corporations are reflected in industrial and environmental policies. Public opinion is deliberately shaped to allow the growth ideology while the environment is used as a symbol to be protected. This thesis will analyse how public opinion and responses are manipulated so that the growth goals are achieved under the guise of national benefit. This thesis will examine two cases of growth politics: nuclear policy and the Eco Town project in Japan to analyse the influence of the growth mentality and the linkages. The conclusion is that if Japan continues to overreach for economic growth at the cost of the environment and if public scrutiny is kept to a minimum, Japan will fail to secure either economic or environmental sustainability. / Graduate / 0615 / nao57526@hotmail.com