Home > Kinetic Simulation, Sensitivity Analysis of Fission Product Activity and Source Term Evaluation for Typical Accident Scenarios in Nuclear Reactors
Kinetic Simulation, Sensitivity Analysis of Fission Product Activity and Source Term Evaluation for Typical Accident Scenarios in Nuclear Reactors
Saeed Ehsan Awan, PhD, Department of Physics & Applied Mathematics, PIEAS, June 2012. "Kinetic Simulation, Sensitivity Analysis of Fission Product Activity and Source Term Evaluation for Typical Accident Scenarios in Nuclear Reactors”; Supervisor: Dr. Nasir. M. Mirza; Co-Supervisor: Dr. Sikander M. Mirza; Department of Physics & Applied Mathematics, PIEAS, Nilore 45650, Islamabad. With growing demands of safe and reliable energy resources worldwide, nuclear power plants present viable option. A two third majority of these plants are PWRs. In comparison with their competitors, PWRs suffer from significantly higher dose rate due to radioactivity in the primary circuit which is dominantly contributed by corrosion and followed by fission products leakage from fuel. There has been extensive investigation in developing corrosion resistance alloys. But the problem of corrosion product activity in primary circuit has aggravated in view of trend towards high burn-ups, high temperatures, and longer-life time reactors. Under this scenario, the significance of fission products releases becomes even higher. The fission product activity (FPA) is considered to be the second leading contributor towards prevalent radiation levels in Pressurized Water Reactors (PWRs). The elevated radiation level results in delay and prolongation of routine repair/maintenance tasks of reactor’s cooling system, which not only reduces its effectiveness but also results in several million dollars revenue loss per power plant annually. However the reliable estimates of fission product activity (FPA) are also significant for the evaluation of fuel performance, assessment of radiological consequences in case of any accident releasing radioactivity and scheduling repair/maintenance tasks. The detailed knowledge about radioactivity build up and sensitivity analysis of fission product activity (FPA) is essential for reducing the plant maintenance time, which also helps to reduce the dose for plant operators and general public. In this work, first a model is developed for dynamic and static sensitivity analysis of fission product activity in primary coolant of typical pressurized water reactor (PWR). It has been implemented in the FPCART based computer program FPCART-SA that carries out sensitivity analysis of fission product activity (FPA) using both static as well as dynamic approaches. For long steady power operation of reactor, the computed values of normalized static sensitivity have been compared with the corresponding values obtained by using the dynamic sensitivity analysis. The normalized sensitivity values for the reactor power (P), failed fuel fraction (D), Coolant leakage rate (L), total mass of coolant (m) and the let down flow rate (Q) have been calculated and the values: 1.0, 0.857, -2.0177 × 10-6, 2.349 × 10-4, -2.329 × 10-4 have been found correspondingly for Kr-88 with the dominant values of fission product activity (FPA) as 0.273 μCi/g. In the second part of this study, evaluation of time dependence of source term has been carried out for a typical reactor system. The modeling and simulation of release of radioactivity has been carried out by developing a computer program FPARA which uses the ORIGEN2 code as subroutine, for core inventory calculations. Time dependent release of fission product activity to the containment and air has been simulated for loss of coolant accident scenarios. For noble gases, iodine and for aerosols, the release rate studies have been carried out for different leakage rates from containment. Effects of fraction of source in the coolant that is directly available after the accident on volumetric fission product activity were studied. Results show that volumetric activity in the containment air for different fission products remains strong function of decay constants, leakage rates, retention factors, deposition rates and fractional release rates.
The Government of Pakistan has a primary obligation to establish and maintain quality public schools for its citizens. The education policies and documents of the government of Pakistan (see 1973 constitution of Pakistan) not only recognizes education as a public good, but also expresses commitment to establish an equitable education system. Nonetheless, the element of conceptualized ‘equality’ looks a far cry in real sense. This paper, hence, realizing on-ground situation, examines empirically the contradictions that exist between government rhetoric of egalitarianism in education and the extent to which the gap exists between policy intention and policy implementation. Drawing on qualitative interviews with 28 educationists, this article asserts that the government’s dual policy towards education (ignoring public education and encouraging private education) has tacitly legitimized the sale and purchase of education as commodity. This shift, in the perception of education from a public good to a private commodity, seriously brings disadvantages to working class pupils in the competition for earning valuable educational credentials and trading upon them. Treating education as private good contributes to perpetuation of class hierarchies in Pakistan.
Politicians, policy makers and economic managers want to spur economic growth, bring economic stability and to create jobs. Economic growth is not only affected by macroeconomic policies but it is also prone to various types of shocks. Appropriate and timely policy response can at least minimize, if not completely escaped, the distortions and loses associated with shocks. Optimization of economic growth and its sustainability demands the execution of good macroeconomic policies in general and fiscal and monetary policy in particular. Some time fiscal policy seems to be more effective while the environment is more favorable for monetary policy in other times. We also know that both fiscal and monetary policy have different objective with different policy instruments. The macroeconomic situation of Pakistan’s is very depressing and the situation demands stark assessment of its macroeconomic policies particularly fiscal and monetary policy. The objective of this thesis is to investigate the interaction between fiscal and monetary policy using small scale open economy dynamic stochastic general equilibrium model. This thesis explores the responsiveness of monetary policy to fiscal policy vis-à-vis explore the fiscal implications of monetary policy. As we assume a small scale open economy, we also explore the responses of fiscal and monetary policy interaction to technology and foreign output shocks. We also countercheck few results using the techniques of autoregressive distributive lag model. Our findings reveal the existence of interaction between fiscal and monetary policy in Pakistan. The response of interest rate to fiscal policy, particularly to tax shock is positive. Fiscal and monetary policy behaves as a strategic complements. This is not a good sign for a crippling economy like Pakistan’s as two important macroeconomic policies are contractionary simultaneously. Similarly when it comes to spending component, interest rate negatively responds when government increases spending. Both fiscal and monetary authority adopts expansionary policies simultaneously. We also find that higher interest rate discourage government borrowing. Inflation responds negatively to interest rate in DSGE set up while the phenomenon of price puzzle exists in ARDL schemes of things. The response of inflation is positive to both higher taxes and government spending. Government spending reduces in response to a monetary policy shock. Tax revenue also reduces when interest rate shock occurs in the economy. Inflation also raises the revenue from taxes but is very short lived.