Submission Title
Inherent Safety in Advanced Nuclear Reactors- A Physical Approach
Presentation Type
Keynote
Start Date
16-12-2018 2:00 PM
Abstract
Inherent or passive safety is an important design feature of advanced reactors, which require a multi-physics approach. Reactor designers are focussed on achieving a greater level of safety by ingenious design. Improved safety would require a stricter control on the achievable operational characteristics. This talk will highlight some of the physics safety features of advanced reactor systems being designed in BARC.
The Advanced Heavy water Reactor (AHWR), designed by BARC is a pressure-tube type boiling water cooled heavy water moderated reactor has several passive safety features. These have been achieved by physics solutions such as larger thermal margins by bottom peaked power distribution, achieving negative void coefficient through suitable epithermal spectrum, flat power distribution and low power density. AHWR is also designed to have effective fuel utilisation by optimising the fissile depletion and production. The axial gradation of enrichment in the AHWR fuel assembly has helped to tune the power distribution in a Pressure-Tube type reactor with boiling coolant and hence achieve better thermal margins. The equilibrium core design has a very low excess reactivity thereby minimizing the reactivity swings and enhancing the safety. A critical facility has been built in BARC to study some of the physics parameters of AHWR.
Another domain is the safety of long life cores which require burnabIe poisons to be in-built in the fuel and thereby its influence on core characteristics. In Compact High Temperature Reactor (CHTR) the use of Gadolinium and its effective optimisation has been done to achieve a 15 year operating cycle. In the Indian pressurised Water Reactor (IPWR), Gd bearing pins have been optimised to get a good power distribution.
Pressurised Heavy Water Reactors (PHWR) by design are flexible to the use of different fuels. An innovative physics solution was demonstrated in the use of thoria bundles instead of depleted uranium to achieve a flat radial power distribution in the initial core of 220 MW(e) PHWRs.
The challenges in safety analysis are multi-fold. The time scales to be modelled range from pico seconds to years and the phenomenon to be modelled are also very heterogeneous. Neutronics coupled with thermal hydraulics requires to be modelled with higher degree of accuracy. The modelling of these systems would require detailed experimentation and advanced computational tools. Safety analysis requires the quantification of uncertainties. The talk will also cover some of these developmental activities.
Recommended Citation
Kannan, Umasankari (2018). "Inherent Safety in Advanced Nuclear Reactors- A Physical Approach," Symposium on Advanced Sensors and Modeling Techniques for Nuclear Reactor Safety.
Inherent Safety in Advanced Nuclear Reactors- A Physical Approach
Inherent or passive safety is an important design feature of advanced reactors, which require a multi-physics approach. Reactor designers are focussed on achieving a greater level of safety by ingenious design. Improved safety would require a stricter control on the achievable operational characteristics. This talk will highlight some of the physics safety features of advanced reactor systems being designed in BARC.
The Advanced Heavy water Reactor (AHWR), designed by BARC is a pressure-tube type boiling water cooled heavy water moderated reactor has several passive safety features. These have been achieved by physics solutions such as larger thermal margins by bottom peaked power distribution, achieving negative void coefficient through suitable epithermal spectrum, flat power distribution and low power density. AHWR is also designed to have effective fuel utilisation by optimising the fissile depletion and production. The axial gradation of enrichment in the AHWR fuel assembly has helped to tune the power distribution in a Pressure-Tube type reactor with boiling coolant and hence achieve better thermal margins. The equilibrium core design has a very low excess reactivity thereby minimizing the reactivity swings and enhancing the safety. A critical facility has been built in BARC to study some of the physics parameters of AHWR.
Another domain is the safety of long life cores which require burnabIe poisons to be in-built in the fuel and thereby its influence on core characteristics. In Compact High Temperature Reactor (CHTR) the use of Gadolinium and its effective optimisation has been done to achieve a 15 year operating cycle. In the Indian pressurised Water Reactor (IPWR), Gd bearing pins have been optimised to get a good power distribution.
Pressurised Heavy Water Reactors (PHWR) by design are flexible to the use of different fuels. An innovative physics solution was demonstrated in the use of thoria bundles instead of depleted uranium to achieve a flat radial power distribution in the initial core of 220 MW(e) PHWRs.
The challenges in safety analysis are multi-fold. The time scales to be modelled range from pico seconds to years and the phenomenon to be modelled are also very heterogeneous. Neutronics coupled with thermal hydraulics requires to be modelled with higher degree of accuracy. The modelling of these systems would require detailed experimentation and advanced computational tools. Safety analysis requires the quantification of uncertainties. The talk will also cover some of these developmental activities.
