International Journal of Nuclear Safety and Security (3 papers in press)
Passive containment cooling system with hydrogen recombiner for prolonged station blackout
by Shripad T. Revankar
Abstract: An accident scenario beyond the design basis, where station blackout could lead to a severe accident with hydrogen release, has become important after the accident at Fukushima Daiichi nuclear plant. In this paper, a passive containment cooling system (PCCS) combined with a hydrogen mitigation system is suggested that will passively remove containment heat load as well as mitigate hydrogen from the containment atmosphere during a prolonged station blackout. It is proposed to make use of atmospheric air as the ultimate heat sink to reject the PCCS heat, which in turn will transfer heat from the containment. In the proposed design, a finned vertical tube type PCCS system submersed in pool water is considered, with the supply of pool water lasting three days following which airflow cools the PCCS tubes over the long term. The PCCS inlet flow path will have a catalytic recombiner that is effective during the first few days should there be any hydrogen generation and accumulation in the containment.
Keywords: passive containment cooling; passive condenser; severe accident; station blackout; hydrogen mitigation;.
Physical protection systems of nuclear facilities: a proposed nuclear power plant general layout and regulatory requirements
by Olivea Elhefnawy, Mahmoud Barakat
Abstract: At present, great efforts in Egypt are directed towards elaborate physical protection regulations to protect nuclear and radiological facilities from any adversary actions, especially after signing the agreement between Egypt and Russia for the establishment of the first Egyptian nuclear power plant in Dabaa. The upcoming regulations will include a physical protection regulation of nuclear facilities and nuclear materials. Thus, the present work is concerned with a proposal of physical protection regulation of nuclear facilities. This proposal discussed the role of the licensee in defining threat assessment and design basis threat, followed by classifying different areas in the general layout of the nuclear facility or nuclear power plant. Also, the requirements of an efficient physical protection system were discussed based on the four basic elements, e.g. entry control, intrusion detection, delay of intruder, and response force. This suggested regulation takes into consideration the International Atomic Energy Agency recommendations and many other countries' regulations.
Keywords: physical protection systems; nuclear facilities; nuclear power plant; general layout; threat assessment; design basis threat; regulatory requirements; entry control; intrusion detection; delay of intruder; response force.
Thermal hydraulic simulations of a PWR nuclear power plant
by Said Mohamed Ali Ibrahim, Sami Ibrahim Atia
Abstract: The safety of nuclear reactors is one of the most challenging and important issues. It is extremely important to protect the public from nuclear radiation exposure in the case of a nuclear power plant (NPP) accident. The proper performance of the safety systems of nuclear plants is one of the most highly important concerns which enhance the use of nuclear energy options. This research study presents an analysis simulation of the steady state, station blackout, and loss of coolant accident thermal hydraulic conditions. The nuclear power plant is a pressurised water reactor type with output electrical power of about 1000 MW. In this study, the thermal hydraulics is performed by using RELAP and PcTran codes to develop a model of this PWR, which could simulate its primary system, with good accuracy in the case of steady state, station blackout, and loss of coolant accident condition. The simulation describes the reactor behaviour during steady state, station blackout, and loss of coolant accident conditions. The main findings of this study are that the core temperature distribution, pressure, coolant mass flow inlet and outlet temperatures of the reactor, and other parameters that have been modelled with the reference data are proven to be in good agreement with each other. These simulations aim to verify the efficiency of the management procedures by analytical means in ensuring that the auxiliary cooling systems are efficient and provide a strong cooling capability of the reactor core in the case of accident conditions, and that it makes an active contribution to the mitigation of the significant undesirable consequences, and the importance of the auxiliary system during the accident conditions. This paper demonstrated that the developed RELAP and PcTran models are capable of reproducing the thermal hydraulic behaviour of the studied PWR, and it can contribute to the process of the plant safety analysis.
Keywords: steady state; RELAP and PcTran codes; Nuclear safety; Station Blackout; LOCA; Thermal hydraulic.