Afshin Hedayat
Abstract
Both of small and medium sized reactors and small modular reactors are called SMRs. They are reviewed and discussed in this paper, particularly integral Pressurized Water Reactors (iPWRs). Studies show that PWRs are the most interested, designed and constructed ...
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Both of small and medium sized reactors and small modular reactors are called SMRs. They are reviewed and discussed in this paper, particularly integral Pressurized Water Reactors (iPWRs). Studies show that PWRs are the most interested, designed and constructed nuclear reactor type worldwide. Some innovative small modular PWRs like the MASLWR, NuScale, CAREM-25, SMART and ACP-100 have several outstanding characteristics to be promisingly recognized as near term options of the next generation of small modular PWRs. They have several inherently safety features and improved passive safety system. They require smaller infrastructure and capital costs. They can be also developed rapidly in different and independent modular unites even for remote area or outlands without required infrastructure or electrical grids. It should be noted that new modern economy strategies like the Return of Investment (ROI) issues may advice medium or large reactors rather than small units for developed and industrial countries while small modular plans can be much more interesting and accessible for new comers or even developing countries. Finally, multi-applicability is an appropriate solution to develop expensive nuclear power plants economically as well as multi-purpose research reactors (especially by means of small modular iPWRs).
Ehsan Boustani; Samad Khakshournia
Abstract
A second shutdown system (SSS) is designed for the Tehran Research Reactor (TRR) completely independent and diverse from the existing First Shutdown System (FSS). Given limitations, specifications, and requirements of the reactor, the design of SSS is based ...
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A second shutdown system (SSS) is designed for the Tehran Research Reactor (TRR) completely independent and diverse from the existing First Shutdown System (FSS). Given limitations, specifications, and requirements of the reactor, the design of SSS is based on the injection of liquid neutron absorber. The plan has the ability to satisfy the major criterion of required negative reactivity worth, to transfer the reactor to subcritical state in needed time, with necessary shutdown margin and for the required duration. Design calculations are performed using the stochastic code MCNPX2.6.0, deterministic code PARET and Pipe Flow Expert software. The ORIGEN2 code and HotSpot health physics code are also used for simulation of environmental pollution release. The SSS chambers cause a decrease of about 5% and 15% in total and thermal neutron flux, respectively. To demonstrate the SSS role in enhancing reactor safety, the probable accident of core meltdown is investigated. As a consequence of this accident, the radioactive pollution in and out of reactor containment is released. Without existing the SSS and in case of failure of FSS, the residents within 58000 m2 of the reactor perimeter would receive about 1 mSv which is more than the annual limit of absorbed dose for the community.
