Analyses of Severe Accidents in GFR Demonstrator ALLEGRO With MELCOR 2.1

2016 ◽  
Author(s):  
Petr Vácha ◽  
Ladislav Bělovský
Keyword(s):  
Fast Reactor ◽  
Heat Removal ◽  
Computer Code ◽  
Full Scale ◽  
Severe Accident ◽  
The Road ◽  
Passive Safety Systems ◽  
Station Blackout ◽  
On The Road ◽  
Further Development

The helium-cooled Gas Fast Reactor (GFR) is one of the six reactor concepts selected for further development in the frame of the Generation IV International Forum (GIF). Since no gas cooled fast reactor has ever been built, a small demonstration reactor is necessary on the road towards the full-scale GFR reactor. A concept of this demonstrator is called ALLEGRO. The French Commissariat à l’énergie atomique et aux énergies alternatives (CEA) developed between 2001–2009 a pre-conceptual design of both the full-scale GFR called GFR2400 and the small demonstration unit called ALLEGRO (75 MWt). Since 2013 ALLEGRO has been under development by several partners from Czech Republic, France, Hungary, Poland and Slovakia. No severe accident study of ALLEGRO using a dedicated computer code has been published so far. This paper is the first attempt to perform computer simulations of the ALLEGRO CEA 2009 concept, using MELCOR version 2.1. A model of the ALLEGRO CEA 2009 concept has been developed with the aim to perform safety analyses; to confirm that MELCOR can be used for such a study, to investigate what scenarios lead to a severe accident and to study in detail the progression of the severe accident during the in-vessel phase. Several pressurized and depressurized protected scenarios were investigated; four of them are presented in this paper. It was observed that even long-lasting station blackout (SBO) without further failures of the passive safety systems does not lead to a severe accident as long as there is enough water in the decay heat removal (DHR) system. Loss of coolant (LOCA) transients with DHR system in the forced-convection mode can lead to peak cladding temperatures causing limited core damage in the early phase of the accidents, but without further development into core meltdown. On the other hand, LOCA combined with SBO leads to excessive core melting in orders of minutes, which represents a weak point of ALLEGRO 2009 concept. Recommendations were formulated for the further development of the ALLEGRO concept.

Analysis of ESFR Decay Heat Removal Systems in Protected Station Blackout

2021 ◽  
Author(s):  
Janos Bodi ◽  
Alexander Ponomarev ◽  
Evaldas Bubelis ◽  
Konstantin Mikityuk
Keyword(s):  
Power Plant ◽  
Fast Reactor ◽  
Heat Removal ◽  
Current Paper ◽  
Decay Heat ◽  
Sodium Fast Reactor ◽  
Station Blackout ◽  
Safety Assessments ◽  
The Individual

Abstract As part of the ESFR-SMART project, safety assessments are being conducted on the updated European Sodium Fast Reactor (ESFR) design. An important part of the study is the evaluation of the reactor's behavior within hypothetical accidental conditions to assess and ensure that the accident would not lead to unexpected and disastrous events. In the current paper, the analyzed accidental scenario is the so called Protected Station Blackout (PSBO), where the offsite power is lost for the power plant, simulated by using the TRACE and SIM-SFR system codes. The assessment started from the simulation of the reactor behavior without the decay heat removal systems (DHRS). Following this, calculations of multiple DHRS arrangements have been performed to evaluate the individual and combined efficiency of the systems. Where it was possible, the results from the two system codes have been compared to show the consistency of the separate calculations. Through this study, the design of the DHRSs proposed at the beginning of the project have been investigated, and certain recommendations have been made for further improvement of the DHRS systems performance.

Severe Accident Analysis for BWR With Containment Outer Pool

2012 ◽  
Author(s):  
Koki Yoshimura ◽  
Kohei Hisamochi
Keyword(s):  
Cooling System ◽  
Water Injection ◽  
Heat Removal ◽  
Severe Accident ◽  
Gas Temperature ◽  
Passive System ◽  
Active Components ◽  
Active System ◽  
Station Blackout ◽  
Materials Used

Newly designed plants, e.g., next-generation light water reactor or ESBWR, employ a passive containment cooling system and have an enhanced safety with RHRs (Residual Heat Removal system) including active components. Passive containment cooling systems have the advantage of a simple mechanism, while materials used for the systems are too large to employ these systems to existing plants. Combination of passive system and active system is considered to decrease amount of material for existing plants. In this study, alternatives of applying containment outer pool as a passive system have been developed for existing BWRs, and effects of outer pool on BDBA (Beyond Design Basis Accident) have been evaluated. For the evaluation of containment outer pool, it is assumed that there would be no on-site power at the loss of off-site power event, so called “SBO (Station BlackOut)”. Then, the core of this plant would be uncovered, heated up, and damaged. Finally, the reactor pressure vessel would be breached. Containment gas temperature reached the containment failure temperature criteria without water injection. With water injection, containment pressure reached the failure pressure criteria. With this situation, using outer pool is one of the candidates to mitigate the accident. Several case studies for the outer pool have been carried out considering several parts of containment surface area, which are PCV (Pressure Containment vessel) head, W/W (Wet Well), and PCV shell. As a result of these studies, the characteristics of each containment outer pool strategies have become clear. Cooling PCV head can protect it from over-temperature, although its effect is limited and W/W venting can not be delayed. Cooling suppression pool has an effect of pressure suppressing effect when RPV is intact. Cooling PCV shell has both effect of decreasing gas temperature and suppressing pressure.

scholarly journals Application of ASTEC, MELCOR, and MAAP Computer Codes for Thermal Hydraulic Analysis of a PWR Containment Equipped with the PCFV and PAR Systems

2017 ◽  
Vol 2017 ◽  
pp. 1-16 ◽  
Author(s):  
Siniša Šadek ◽  
Davor Grgić ◽  
Zdenko Šimić
Keyword(s):  
Severe Accident ◽  
Pressurized Water Reactor ◽  
Hydraulic Analysis ◽  
Pressurized Water ◽  
Passive Safety Systems ◽  
European Code ◽  
Station Blackout ◽  
Computer Codes ◽  
Safety Systems ◽  
Thermal Hydraulic Analysis

The integrity of the containment will be challenged during a severe accident due to pressurization caused by the accumulation of steam and other gases and possible ignition of hydrogen and carbon monoxide. Installation of a passive filtered venting system and passive autocatalytic recombiners allows control of the pressure, radioactive releases, and concentration of flammable gases. Thermal hydraulic analysis of the containment equipped with dedicated passive safety systems after a hypothetical station blackout event is performed for a two-loop pressurized water reactor NPP with three integral severe accident codes: ASTEC, MELCOR, and MAAP. MELCOR and MAAP are two major US codes for severe accident analyses, and the ASTEC code is the European code, joint property of Institut de Radioprotection et de Sûreté Nucléaire (IRSN, France) and Gesellschaft für Anlagen und Reaktorsicherheit (GRS, Germany). Codes’ overall characteristics, physics models, and the analysis results are compared herein. Despite considerable differences between the codes’ modelling features, the general trends of the NPP behaviour are found to be similar, although discrepancies related to simulation of the processes in the containment cavity are also observed and discussed in the paper.

scholarly journals Analysis of Settlement of the Road with Full Scale Geotextile Reinforcement on the Very Soft Soil (Case Study in Tapin Regency, South Kalimantan)

2019 ◽  
Vol 280 ◽  
pp. 03012
Author(s):  
Muhammad Arsyad ◽  
Indrasurya B. Mochtar ◽  
Noor Endah Mochtar
Keyword(s):  
Soft Soil ◽  
Road Construction ◽  
Full Scale ◽  
Construction Site ◽  
The Road ◽  
Local Material ◽  
Long Time ◽  
Soil Settlement ◽  
On The Road ◽  
Additive Materials

Abstract, in case of the construction of road in soft soil, it is necessary toconsider the use of materials around the road construction site, and not touse selected material which is imported from outside the road constructionsite. Thus, aim to overcome the difficulties of using selected materials, namely the difficulty to obtain the materials, the price of expensivematerials , the freight of material that could takes a long time period, highcost, and the use of materials that tend to be environmentally unfriendly. Itis very necessary to learn about the use of nonstandard additive materials, taken to the road construction site, but with the use of geotextilereinforcement. The research method used is a full scale method in the formof trial embankment, so that the performance of the road can be observedfor a long period of time due to the traffic and soil settlement. The resultsobtained is settlement that occur on the road from the combination ofordinary embankment material and local material, most frequently occuredin a larger percentage of ordinary embankment than the local material. While the visual value is relevant to the settlement in which a largerpercentage of ordinary embankment results in a better visual value, due tothe quality of the ordinary embankment material is better than the localmaterial.

scholarly journals Safety Design and Evaluation in a Large-Scale Japan Sodium-Cooled Fast Reactor

2012 ◽  
Vol 2012 ◽  
pp. 1-14 ◽  
Author(s):  
H. Yamano ◽  
S. Kubo ◽  
Y. Shimakawa ◽  
K. Fujita ◽  
T. Suzuki ◽  
...  
Keyword(s):  
Fast Reactor ◽  
Large Scale ◽  
Natural Circulation ◽  
Heat Removal ◽  
Severe Accident ◽  
Safety Requirements ◽  
Generation Plant ◽  
Safety Design ◽  
Phenomenological Consideration ◽  
Heat Removal System

As a next-generation plant, a large-scale Japan sodium-cooled fast reactor (JSFR) adopts a number of innovative technologies in order to achieve economic competitiveness, enhanced reliability, and safety. This paper describes safety requirements for JSFR conformed to the defense-in-depth principle in IAEA. Specific design features of JSFR are a passive reactor shutdown system and a recriticality-free concept against anticipated transients without scram (ATWS) in design extension conditions (DECs). A fully passive decay heat removal system with natural circulation is also introduced for design-basis events (DBEs) and DECs. In this paper, the safety design accommodation in JSFR was validated by safety analyses for representative DBEs: primary pump seizure and long-term loss-of-offsite power accidents. The safety analysis also showed the effectiveness of the passive shutdown system against a typical ATWS. Severe accident analysis supported by safety experiments and phenomenological consideration led to the feasibility of in-vessel retention without energetic recriticality. Moreover, a probabilistic safety assessment indicated to satisfy the risk target.

scholarly journals Safety Analyses of VVER-1200/V491 reactor for longterm station blackout along with small LOCAs

2016 ◽  
Vol 6 (4) ◽  
pp. 8-17
Author(s):  
Thi Hoa Bui ◽  
Tan Hung Hoang ◽  
Minh Giang Hoang
Keyword(s):  
Steam Generator ◽  
Heat Removal ◽  
Safety Analysis ◽  
Severe Accident ◽  
Management Guideline ◽  
Accident Management ◽  
Station Blackout

Performance of  Passive Heat Removal through Steam Generator (PHRS-SG) of VVER-1200/V491 reactor presented in Safety Analysis Report for Ninh Thuan 1 shows that in case of long term station black out (SBO),  VVER-1200/V491 reactor can be cooldown and remained in safety mode at least 24 hours based on PHRS-SG performance. Anyway, long term station blackout along with small break in main coolant pipe of VVER-1200/V491 is assumed to be happening as an extension design condition that needs to be investigated. This study focuses on investigation of SBO along with different size of small break of LOCAs with expectation of finding the range of break size that the reactor is still kept in safety mode during 24 hours. During the investigation, some indicators for fuel damage such as the timing of HA1 actuation or mass of coolant inventory discharged are introduced as necessary information contributed to Severe Accident Management Guideline (SAMG).

scholarly journals On the Road to Circular Public Procurement: Case, Variations, and Potential Actions in Germany

2021 ◽  
Vol 13 (24) ◽  
pp. 13784
Author(s):  
Simone Wurster ◽  
Rita Schulze ◽  
Ramona G. Simon
Keyword(s):  
Circular Economy ◽  
Public Procurement ◽  
Pilot Project ◽  
Supply Side ◽  
Waste Generation ◽  
The Road ◽  
On The Road ◽  
Framework Conditions ◽  
Further Development

According to the United Nations, the consumption of materials is expected to double between 2020 and 2050. At the same time, annual waste generation is forecast to increase by 70% by 2050. The circular economy (CE) addresses this problem. However, many barriers to the further development of the CE exist. This article analyses the situation of public procurement in supporting a sustainable CE for tyres in Germany based on 18 interviews with public procurement professionals directly responsible for the purchase of tyres and four additional expert interviews. Based on the dimensions ‘current circular public procurement (CPP) intensity’ and ‘current CPP opportunities’, a classification of tyre procurement situations and barriers to sustainable circular tyre procurement is presented. Strategies to overcome these supply-side and demand-side barriers are specified, resulting in nine recommendations for German policymakers. As a way forward, a detailed concept for a pilot project on tyre CPP is provided. The article also shows how the circular public procurement classification can be used to support sustainability measures in a broader context. Finally, the article’s outlook focuses on implications to promote sustainable circular tyre procurement in other countries. It explains different framework conditions and elaborates to what extent additional research is necessary to develop appropriate recommendations for those conditions.

scholarly journals “Between Heaven and Earth”: A.N. Tolstoy’s Fiction of 1918–1919

2021 ◽  
Vol 6 (2) ◽  
pp. 128-143
Author(s):  
Galina N. Vorontsova
Keyword(s):  
Full Scale ◽  
Russian Revolution ◽  
The Novel ◽  
The Road ◽  
The Creation ◽  
To Come ◽  
Heaven And Earth ◽  
Further Development

The article is based on the thesis that in the writer’s works it is always possible to trace the existence of periods marked by the emergence of new themes and motives. As a rule, this is due both to external circumstances and the artist’s reaction to them, his internal feeling of the need to change the paradigm of his further development. In the work of A.N. Tolstoy one of such periods was the era of the Russian Revolution of 1917 and, in particular, the first revolutionary years, which are characterized by artistic experiments of the writer, allowing to talk about a definitely new vector of his searches. The article analyzes Tolstoy’s stories Mercy!, Peter’s Day, Count Cagliostro and Delirious in the context of the writer’s artistic searches of the 1918–1919. The writer’s work within the boundaries of small prosaic genres at that time allowed him, already in the second half of 1919, to come close to the creation of a full-scale canvas about the Russian Revolution, the novel The Road to Calvary.

Experimental Methods for Road Tankers: A Critical Review

2020 ◽  
Author(s):  
Frank Otremba ◽  
José A. Romero Navarrete ◽  
Alejandro A. Lozano Guzmán
Keyword(s):  
Critical Review ◽  
Road Safety ◽  
Experimental Methods ◽  
Potential Effect ◽  
Full Scale ◽  
Field Conditions ◽  
The Road ◽  
Experimental Approaches ◽  
On The Road ◽  
High Center

Abstract The transportation of liquids involves several situations derived from the curved shape of the cargo containers, including a comparatively high center of gravity, which negatively shifts when the container is partially loaded, and the vehicle is subjected to steering or braking accelerations. Aiming at reducing these effects several experimental approaches have been applied, involving different tank shapes and the use of baffles, tested under laboratory or field conditions, at full scale or at a down-scale. However, the scope of such approaches has been limited, mainly because the potential effect of other components of the vehicle on the road tanker behavior, has been neglected. In this paper, a critical review is presented of the experimental approaches considered so far, identifying specific experimental needs to improve the performance of the vehicles, from both the road safety and the environmental perspective.

Emergency Decay Heat Removal in a GEN-IV Gas-Cooled Fast Reactor

2006 ◽  
Author(s):  
Lap Y. Cheng ◽  
Hans Ludewig ◽  
Jae Jo
Keyword(s):  
Fast Reactor ◽  
Cooling System ◽  
Natural Circulation ◽  
Heat Removal ◽  
Forced Flow ◽  
Decay Heat ◽  
Conversion Unit ◽  
Station Blackout ◽  
Combination Approach ◽  
Gen Iv

A series of transient analyses using the system code RELAP5-3d has been performed to confirm the efficacy of a proposed hybrid active/passive combination approach to the decay heat removal for an advanced 2400MWt GEN-IV gas-cooled fast reactor. The accident sequence of interest is a station blackout simultaneous with a small break (10 sq.inch/0.645m2) in the reactor vessel. The analyses cover the three phases of decay heat removal in a depressurization accident: (1) forced flow cooling by the power conversion unit (PCU) coast down, (2) active forced flow cooling by a battery powered blower, and (3) passive cooling by natural circulation. The blower is part of an emergency cooling system (ECS) that by design is to sustain passive decay heat removal via natural circulation cooling 24 hours after shutdown. The RELAP5 model includes the helium-cooled reactor, the ECS (primary and secondary side), the PCU with all the rotating machinery (turbine and compressors) and the heat transfer components (recuperator, pre-cooler and inter-cooler), and the guard containment that surrounds the reactor and the PCU. The transient analysis has demonstrated the effectiveness of passive decay heat removal by natural circulation cooling when the guard containment pressure is maintained at or above 800kPa.

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