Category Archives: DESIGN FEATURES TO ACHIEVE. DEFENCE IN DEPTH IN SMALL AND. MEDIUM SIZED REACTORS

Probabilistic safety criteria

Probabilistic safety criteria specify the basic safety indices of an NPP in probabilistic terms as the following: (a) To avoid the need for population evacuation beyond plant boundaries established by the regulatory requirements regarding the location of NPPs, it is necessary to target a probable maximum release of no more than 10-7 per reactor per year; the value of this […]

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Passive core heat removal by natural convection during normal operation and in shutdown conditions

In the AHWR, natural convection is the mode of coolant circulation to remove heat from the reactor core under both normal and shutdown conditions. Figure VI-3 shows the main heat transport (MHT) system and the passive decay heat removal system of the AHWR. A two phase steam water mixture generated in the core flows through the tail pipes to the […]

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SAFETY DESIGN FEATURES OF THE CHTR

Bhabha Atomic Research Centre (BARC),India X — 1. DESCRIPTION OF THE CHTR CONCEPT The Compact High Temperature Reactor (CHTR) is a lead-bismuth cooled beryllium oxide moderated reactor, designed to operate mainly with 233U-Th fuel. The concept of this reactor, which is initially being developed to generate about 100 kW(th), has a core lifetime of 15 years and incorporates several advanced […]

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MEASURES PLANNED IN RESPONSE TO SEVERE ACCIDENTS

Physical properties of the reactor core and engineering features of the GT-MHR reactor plant ensure that the temperature of the coated particle fuel is kept below 1600°C in any accidents with heat removal failure, including a complete failure of all active means of reactor emergency protection and shutdown. The effectiveness of fuel element claddings (coatings), which provide the main protective […]

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Emergency core cooling system

This system provides for the injection of water directly into the reactor core in three stages. In the first stage, injection from the accumulator takes place, see Fig. VI-4. In the second stage, water flows from the GDWP under gravity, providing core cooling for three days. In the third stage, water accumulated in the reactor cavity is pumped back to […]

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Passive power regulation system

CHTR incorporates a passive power regulation system (PPRS). This system operates on the principle of an increase in gas pressure with temperature, thereby pressurizing and forcing a column of molten metal with floating absorbing material into the core. This introduces negative reactivity in the core. Depending on the sensed temperature rise, the system would stabilize at a particular value of […]

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SUMMARY OF PASSIVE SAFETY DESIGN FEATURES FOR THE GT-MHR

Tables VII-5 to VII-9 below provide the designer’s response to questionnaires developed at an IAEA technical meeting Review of Passive Safety Design Options for SMRs, held in Vienna on 13-17 June 2005. These questionnaires were developed to summarize passive safety design options for different SMRs according to a common format, based on provisions of IAEA Safety Standards [VII-3] and other […]

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Passive containment cooling system

Passive containment coolers (PCCs) are used to provide post-accident primary containment cooling in a passive mode, as well as to limit post-accident primary containment pressure. The PCCs are located below the GDWP and are connected to the GDWP inventory, see Fig. VI-5. During a LOCA, condensation of steam and cooling of hot air are achieved via cooling provided by natural […]

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