A PSA Case Study: Promoting the Reliability of the CRSS on the CMRR Through the ATWS Mitigation System

2018 ◽  
Author(s):  
Heng Yu ◽  
Guan-bo Wang ◽  
Da-zhi Qian ◽  
Yu-chuan Guo ◽  
Bo Hu
Keyword(s):  
Research Reactor ◽  
Control Rod ◽  
Research Reactors ◽  
The Core ◽  
Core Damage ◽  
The World ◽  
Safety Features ◽  
Control Rods ◽  
Pool Type

An increasing number of PSA programs concerning research reactors have been launched across the world. As with many other reactors, the CMRR (China Mianyang Research Reactor), a typical pool-type research reactor, regards the control rod shutdown system (CRSS) as its primary shutdown system which enables the reactor subcritical by dropping control rods into the core after a specific initiating event is detected. As a result, the CRSS is an essential ingredient of engineered safety features. It is necessary to enhance the reliability of the CRSS, ensuring the reactor can be successfully shut down when the ATWS — the anticipated transients without scram occurs. Therefore, additional facilities should be designed to cope with the extremely severe circumstance. Accordingly, the purpose of this paper is to evaluate the promotion of the CMRR’s safety degree and the reliability of its CRSS from the PSA’s perspective with an ATWS mitigation system installed. Results indicate that, by introducing the ATWS mitigation system, the failure probability of the CRSS can decrease from 1.52e−05 per demand to 3.35e−06 per demand, while the aggregate CDF (core damage frequency) induced by all IE (initiating event) groups, is able to decrease to a relatively low value 1.17e−05/y from its previous value 3.11e−06/y. It is apparent that the reliability of the CRSS as well as the safety degree of the overall reactor can be enhanced effectively by adding the ATWS mitigation system to the elementary design of the normal CRSS.

Development of REFT Code System for the Analysis of Highly Heterogeneous Research Reactors

2014 ◽  
Author(s):  
Tengfei Zhang ◽  
Hongchun Wu ◽  
Youqi Zheng ◽  
Liangzhi Cao ◽  
Yunzhao Li
Keyword(s):  
Least Square Method ◽  
Least Square ◽  
Core Analysis ◽  
Code System ◽  
Lattice Calculation ◽  
Control Rod ◽  
Research Reactors ◽  
The Core ◽  
User Friendly ◽  
Control Rods

As an effort to enhance the accuracy in simulating the operations of research reactors, a fuel management code system REFT was developed. Because of the possible complex assembly geometry and the core configuration of research reactors, the code system employed HELIOS in the lattice calculation to describe arbitrary 2D geometry, and used the 3D triangular nodal SN method transport solver, DNTR, to model unstructured geometry in the core analysis. Flux reconstruction with the least square method and micro depletion model for specific isotopes were incorporated in the code. At the same time, to make it more user friendly, a graphical user interface was also developed for REFT. In the analysis of the research reactors, the calculations involving the control rod movement are encountered frequently. The modeling of the control rods differential worth behavior is important in that the movement of the control rod may introduce variations on the reactivity. To handle the problem two effective ways of alleviating the control rod cusping effect are recently proposed, based on the established code system. The methodologies along with their application and validation will be discussed.

scholarly journals Comparative Analysis of the Dalat Nuclear Research Reactor with HEU Fuel Using SRAC and MCNP5

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Giang Phan ◽  
Hoai-Nam Tran ◽  
Kien-Cuong Nguyen ◽  
Viet-Phu Tran ◽  
Van-Khanh Hoang ◽  
...  
Keyword(s):  
Research Reactor ◽  
Nuclear Research ◽  
Maximum Deviation ◽  
Control Rod ◽  
The Core ◽  
Nuclear Research Reactor ◽  
The Difference ◽  
Enriched Uranium ◽  
Analysis Models ◽  
Control Rods

Neutronics analysis has been performed for the 500 kW Dalat Nuclear Research Reactor loaded with highly enriched uranium fuel using the SRAC code system. The effective multiplication factors, keff, were analyzed for the core at criticality conditions and in two cases corresponding to the complete withdrawal and the full insertion of control rods. MCNP5 calculations were also conducted and compared to that obtained with the SRAC code. The results show that the difference of the keff values between the codes is within 55 pcm. Compared to the criticality conditions established in the experiments, the maximum differences of the keff values obtained from the SRAC and MCNP5 calculations are 119 pcm and 64 pcm, respectively. The radial and axial power peaking factors are 1.334 and 1.710, respectively, in the case of no control rod insertion. At the criticality condition these values become 1.445 and 1.832 when the control rods are partially inserted. Compared to MCNP5 calculations, the deviation of the relative power densities is less than 4% at the fuel bundles in the middle of the core, while the maximum deviation is about 7% appearing at some peripheral bundles. This agreement indicates the verification of the analysis models.

scholarly journals Meditation Tourism, Buddhist Philosophy in Practice: A Case Study of Lumbini, Nepal

2020 ◽  
Vol 11 (1) ◽  
pp. 37-59
Author(s):  
Netra Prasad Sharma
Keyword(s):  
Research Study ◽  
National Development ◽  
Meditation Practice ◽  
Tourist Destination ◽  
The Core ◽  
Spiritual Tourism ◽  
Religious Tourism ◽  
The World ◽  
The Government

The dimensions of travelling and tourism have become manifold in recent decades. People love to travel with various purposes. Religious tourism, yoga tourism, peace tourism and spiritual tourism are some dimensions. Lumbini can be a best destination for meditation tourism, which could be much rewarding for individual, social and national development. The travelers and stakeholders have yet to be aware of this aspect. In Buddhism, Lumbini is a best destination for meditation tour. Exploring the importance of travelling Lumbini for meditation is the main objective of this article. Tourists and pilgrims would benefit immensely if they understand the significance of meditation tourism to Lumbini, its philosophy and practice. This article aims to explore the spiritual significance of Lumbini and it will provide visions of a purposeful development and publicity that would shape Lumbini as a best destination for meditation tourism. The government and private sectors are interested to develop Lumbini as best tourist destination. People all over the world are attracted to visit Lumbini for different reasons. Most tourists are unaware of the core aspect of visiting Lumbini. People who visit Lumbini are unaware about meditation practice or involving in charity works. Meditation and compassion are the core aspects of Buddha’s teachings, which are neither realized nor practiced. There seems a vast gap between the actual philosophy of Buddhism and the attitude of most of the visitors. This research study attempts to reveal the significance of meditation tourism in Lumbini.

scholarly journals Patriarchy in the Digital Conjuncture: An Analysis of Google’s James Damore

2020 ◽  
Author(s):  
Ben Little ◽  
Alison Winch
Keyword(s):  
Scientific Method ◽  
Software Engineer ◽  
High Stress ◽  
Silicon Valley ◽  
High Status ◽  
The Core ◽  
Core Belief ◽  
The World ◽  
New Form

Our case study looks at the events surrounding the sacking ofGoogle engineer James Damore who was fired for authoring a memo which stated that women are biologically less suited to high-stress, high-status technical employment than men. Damore, asserting that his document ‘was absolutely consistent with what he’d seen online’, instantly became an ambivalent hero of the alt-right. Like the men who own and run the companies of Silicon Valley, the software engineer subscribes to the idea that the world can be understood and altered through the rigorous application of the scientific method. And as he draws on bodies of knowledge from evolutionary psychology and mathematical biology, we see how the core belief structures of Silicon Valley, when transferred from the technical to the cultural and social domain, can reproduce the sort of misogynistic ‘rationalism’ that fuels the alt-right. We argue that Damore’s memo is in line with Google’s ideology of ‘dataism’: that is the belief that the world can be reduced to decontextualised information and subject to quantifiable logics.Through its use of dataism, the memo reveals much about the similarities and continuities between Damore, the ideas laid out n his memo, and Google itself. Rather than being in opposition, these two entities are jostling for a place in the patriarchal structures of a new form of capitalism.

Estimation of control rod worth, xenon effect on reactivity and power defect of BAEC TRIGA Mark-II research reactor

2018 ◽  
Vol 33 (39) ◽  
pp. 1850233
Author(s):  
Md. Mehedi Hassan ◽  
K. M. Jalal Uddin Rumi ◽  
Md. Nazrul Islam Khan ◽  
Rajib Goswami
Keyword(s):  
Theoretical Analysis ◽  
Low Power ◽  
Temperature Effects ◽  
Research Reactor ◽  
Power Level ◽  
Fuel Temperature ◽  
Control Rod ◽  
Full Power ◽  
Triga Mark Ii ◽  
Control Rods

In this work, control rod worth, xenon (Xe) effect on reactivity and power defect have been measured by doing experiments in the BAEC TRIGA Mark-II research reactor (BTRR) and through established theoretical analysis. Firstly, to study the xenon-135 effect on reactivity, reactor is critical at 2.4 MW for several hours. Next, experiments have been performed at very low power (50 W) to avoid temperature effects. Moreover, for the power defect experiment, different increasing power level has been tested by withdrawing the control rods. Finally, it is concluded that the total control rods worth of the BAEC TRIGA Mark-II research reactor, as determined through this study, is enough to run the reactor at full power (3 MW) considering the xenon-135 and fuel temperature effects.

Monte Carlo Simulation of Inclined Reactivity Control Rod and Boron Poisoning for the Canadian-SCWR Supercell

2016 ◽  
Vol 2 (2) ◽  
Author(s):  
Haykel Raouafi ◽  
Guy Marleau
Keyword(s):  
Monte Carlo ◽  
Three Dimensional ◽  
Coolant Temperature ◽  
Monte Carlo Code ◽  
Control Rod ◽  
Vertical Control ◽  
The Core ◽  
Core Height ◽  
Supercell Model ◽  
Control Rods

The Canadian-SCWR is a heavy-water moderated supercritical light-water-cooled pressure tube reactor. It is fueled with CANada deuterium uranium (CANDU)-type bundles (62 elements) containing a mixture of thorium and plutonium oxides. Because the pressure tubes are vertical, the upper region of the core is occupied by the inlet and outlet headers render it nearly impossible to insert vertical control rods in the core from the top. Insertion of solid control devices from the bottom of the core is possible, but this option was initially rejected because it was judged impractical. The option that is proposed here is to use inclined control rods that are inserted from the side of the reactor and benefit from the gravitational pull exerted on them. The objective of this paper is to evaluate the neutronic performance of the proposed inclined control rods. To achieve this goal, we first develop a three-dimensional (3D) supercell model to simulate an inclined rod located between four vertical fuel cells. Simulations are performed with the SERPENT Monte Carlo code at five axial positions in the reactor to evaluate the effect of coolant temperature and density, which varies substantially with core height, on the reactivity worth of the control rods. The effect of modifying the inclination and spatial position of the control rod inside the supercell is then analyzed. Finally, we evaluate how boron poisoning of the moderator affects their effectiveness.

scholarly journals DESIGN OF NEUTRONIC PARAMETERS OF MTR REACTOR USING WIMSD-5B/BATAN-FUEL CODES

2020 ◽  
Vol 5 (3) ◽  
pp. 239-248
Author(s):  
Tukiran Surbakti ◽  
Surian Pinem ◽  
Lily Suparlina
Keyword(s):  
Neutron Flux ◽  
Thermal Neutron ◽  
Cycle Length ◽  
Thermal Neutron Flux ◽  
Diffusion Method ◽  
Irradiation Position ◽  
Research Reactors ◽  
The Core ◽  
Neutronic Parameters ◽  
Control Rods

BATAN has three aging research reactors, so it is necessary to design a new, more modern MTR type reactor using high-density, low enrichment uranium molybdenum fuel. The thermal neutron flux at the irradiation position is an important concern in the design of research reactors. This analysis is performed using standard computer codes WIMSD-5B and Batan-FUEL. The purpose of this study is to analyze the effect of the core configuration with safety control rods and neutronic parameters using the diffusion method calculation. The reactor core consists of 16 fuel elements and four control rods placed in the 5 x 5 position of the grid plate and is loaded the reflector elements outside the core. The cycle length is also a concern, not less than 20 days, and the reactor can be operated safely with a power of 50 MW. The calculation results show that for the highest fuel loading, which is 450 grams of U7Mo/Al fuel with D2O as a reflector, it will provide the lowest thermal neutron flux at the center of the core irradiation position, namely 1.0 x1015 n/cm2s. The core fuel cycle length will be up to 39 days, meeting the expected acceptance and safety criteria.

From High to Low Enriched Uranium Fuel in Research Reactors

2010 ◽  
Vol 73 ◽  
pp. 78-90 ◽  
Author(s):  
Sven van den Berghe ◽  
Ann Leenaers ◽  
Edgar Koonen ◽  
Leo Sannen
Keyword(s):  
Research Reactor ◽  
Current Status ◽  
Research Reactors ◽  
Dispersion Fuel ◽  
The Past ◽  
Uranium Fuel ◽  
The World ◽  
Enriched Uranium ◽  
The Moment ◽  
Global Threat

Since the 1970's, global efforts have been going on to replace the high-enriched (>90% 235U), low-density UAlx research reactor fuel with high-density, low enriched (<20% 235U) replacements. This search is driven by the attempt to reduce the civil use of high-enriched material because of proliferation risks and terrorist threats. American initiatives, such as the Global Threat Reduction Initiative (GTRI) and the Reduced Enrichment for Research and Test Reactors (RERTR) program have triggered the development of reliable low-enriched fuel types for these reactors, which can replace the high enriched ones without loss of performance. Most success has presently been obtained with U3Si2 dispersion fuel, which is currently used in many research reactors in the world. However, efforts to search for a replacement with even higher density, which will also allow the conversion of some high flux research reactors that currently cannot change to U3Si2 (eg. BR2 in Belgium), have continued and are for the moment mainly directed towards the U(Mo) alloy fuel (7-10 w% Mo). This paper provides an overview of the past efforts and presents the current status of the U(Mo) development.

Career Choice and Adjustment Issues from a Gender Role Perspective

1998 ◽  
Vol 7 (1) ◽  
pp. 9-12
Author(s):  
Coline Colton ◽  
Wendy Patton ◽  
Coline Colton ◽  
Wendy Patton
Keyword(s):  
Gender Role ◽  
Career Choice ◽  
Career Choices ◽  
Career Education ◽  
The Core ◽  
The World ◽  
Career Adjustment ◽  
Adjustment Issues

Career education in schools has helped to enhance the career choices of women by providing information about options and challenging gender stereotypical beliefs about the world of work. However, issues concerned with career adjustment have been neglected. It is increasingly being recognised, however, that the entry of women into new fields of work is not enough. The question is how to keep women, with their knowledge, skills and experience, in the workforce once they have entered it. This issue is the core focus of this case study.

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