An innovative research reactor design

A new and innovative core design for a research reactor is presented. It is shown that while using the standard, low enriched uranium as fuel, the maximum thermal flux per MW of power for the core design suggested and analyzed here is greater than those found in existing state of the art facilities without detrimentally affecting the other design specs. A design optimization is also carried out to achieve the following characteristics of a pool type research reactor of 10 MW power: high thermal neutron fluxes; sufficient space to locate facilities in the reflector; and an acceptable life cycle. In addition, the design is limited to standard fuel material of low enriched uranium. More specifically, the goal is to maximize the maximum thermal flux to power ratio in a moderate power reactor design maintaining, or even enhancing, other design aspects that are desired in a modern state of the art multi-purpose facility. The multi-purpose reactor design should allow most of the applications generally carried out in existing multi-purpose research reactors. Starting from the design of the German research reactor, FRM-II, which delivers high thermal neutron fluxes, an azimuthally asymmetric cylindrical core design with an inner and outer reflector, is developed. More specifically, one half of the annular core (0 < θ < π) is thicker than the other half. Two variations of the design are analyzed using MCNP, ORIGEN2 and MONTEBURNS codes. Both lead to a high thermal flux zone, a moderate thermal flux zone, and a low thermal flux zone in the outer reflector. Moreover, it is shown that the inner reflector is suitable for fast flux irradiation positions. The first design leads to a life cycle of 41 days and high, moderate and low (non-perturbed) thermal neutron fluxes of 4.2 × 10¹⁴ n cm⁻² s⁻¹, 3.0 × 10¹⁴ n cm⁻² s⁻¹, and 2.0 × 10¹⁴ n cm⁻² s⁻¹, respectively. Heat deposition in the cladding, coolant and fuel material is also calculated to determine coolant flow rate, coolant outlet temperature and maximum fuel temperature under steady-state operating conditions. Finally, a more compact version of the asymmetric core is developed where a maximum (non-perturbed) thermal flux of 5.0 × 10¹⁴ n cm⁻² s⁻¹ is achieved. The core life of this more compact version is estimated to be about 23 days.     

研究堆堆芯换料优化研究

利用特征统计算法(CSA)与先进格林函数节块法相结合,对研究堆平衡循环换料进行优化研究,以重水区热中子注量率最大为主要目标,得到了优于手工优化方案的平衡循环倒换料方案.     

Design of the VVR-S research reactor

A water-cooled, water-moderated reactor for facilitating scientific research endeavors on applications of nuclear energy in peaceful pursuits has been built in the Soviet Union.Such reactors are currently completed and in operation in the Soviet Union and in other Socialist countries. Six such reactors were put into operation during 1957–1959; five reactors (four of which are built to handle power surges) are in the stage of preparation, assembly, and start-up tests.This article describes the design of the VVR-S reactor and its experimental facilities. The physical characteristics of the reactor have been described in an earlier paper [1].     

Gas cooled fast reactor research in Europe

Research on the gas-cooled fast reactor system is directed towards fulfilling the ambitious long term goals of Generation IV (Gen IV), i.e., to develop a safe, sustainable, reliable, proliferation-resistant and economic nuclear energy system. In common with other fast reactors, gas-cooled fast reactors (GFRs) have exceptional potential as sustainable energy sources, for both the utilisation of fissile material and minimisation of nuclear waste through transmutation of minor actinides. The primary goal of GFR research is to develop the system primarily to be a reliable and economic electricity generator, with good safety and sustainability characteristics. However, for the longer term, GFR retains the potential for hydrogen production and other process heat applications facilitated through a high core outlet temperature which, in this case, is not limited by the characteristics of the coolant. In this respect, GFR can inherit the non-electricity applications of the thermal HTRs in a sustainable manner in a future in which natural uranium becomes scarce.GFR research within Europe is performed directly by those states who have signed the “System Arrangement” document within the Generation IV International Forum (the GIF), specifically France and Switzerland and Euratom. Importantly, Euratom provides a route by which researchers in other European states, and other non-European affiliates, can contribute to the work of the GIF, even when these states are not signatories to the GFR System Arrangement in their own right. This paper is written from the perspective of Euratom's involvement in research on the GFR system, starting with the 5th Framework Programme (FP5) GCFR project in 2000, through the FP6 project between 2005 and 2009 and looking ahead to the proposed activities within the current 7th Framework Programme (FP7). The evolution of the GFR concept from the 1960s onwards is discussed briefly, followed by the current perceived role, objectives and progress with the Generation IV GFR system.     

Second trip system for NRU research reactor

For the past four decades, the NRU research reactor has played an important role at the Chalk River Laboratories, Atomic Energy of Canada Limited, serving as one of its major research and isotope production facilities. To ensure that it continues as an effective facility, compliant with the current safety standards, a comprehensive upgrade program is underway. Adding a second trip system (STS) is part of this upgrade program, aiming at improving the effectiveness and reliability of the overall shutdown function. This document describes the main features and basic principles of the STS.The STS is an independent, seismically qualified trip system, that guarantees reactor shutdown even if the existing trip system fails. It is designed based on 2 out of 3 general coincidence logic, with minimal interferences and changes to the existing system. In addition to the manual trip in the main control room, a remote manual trip is provided in the new Qualified Emergency Response Centre, which is also seismically qualified and always accessible. Thus, for any reason, if the main control room becomes uninhabitable, the reactor still can be manually shut down from this centre.     

FRM-II: The new German research reactor

A new German high-flux research reactor is presently being built in Garching by the Technical University of Munich. The new reactor, called FRM-II, shall replace the existing ‘Forschungsreaktor München' FRM which has been operating very successfully for about 40 years now. The new reactor has been optimized primarily with respect to beam tube applications of slow neutrons, but will also allow to irradiate samples with thermal neutrons. Therefore, the FRM-II has been designed to provide a high flux of thermal neutrons in a large volume outside of the reactor core, where the neutron spectrum can be locally modified by using special spectrum shifters. The goal was to further obtain this high flux at a reactor power being as low as possible since this represents the best choice because of the lowest background radiation for the experiments, the lowest nuclear risk potential, the lowest costs and superior inherent safety features. In April, 1996, the project obtained the first partial nuclear licence which covered the general acceptance of the safety concept, the site opening and the construction of the reactor building. The final partial nuclear licence which allows nuclear start-up is expected for the year 2001.     

Choosing suitable type of research reactor for Mongolia

Mongolian government said that one of the sources for energy supply will be a nuclear power. To utilize nuclear energy, it is required that Mongolia has to have sufficient number of national nuclear professionals. It is totally impossible to send all nuclear professionals to study in abroad for education degrees and do provide them with on the job training abroad. One of the key approaches to educate and train nuclear professionals locally is the need for Mongolia to have our own research reactor. The chosen research reactor will be used in various studies and for educational and training purposes. It is significantly important to get public acceptance to implement the nuclear power program. We are considering that it is suitable to choose TRIGA reactor of 300-500 kW power and of 10¹²⁻¹³ n/cm² s neutron flux.