scholarly journals Evaluation of Passive Safety Injection System Performance Under Large Break LOCA for Qinshan PWR

2021 ◽  
Vol 9 ◽  
Author(s):  
Xuesong Wang ◽  
Lin Sun ◽  
Meiru Liu ◽  
Genglei Xia
Keyword(s):  
System Performance ◽  
Nuclear Power ◽  
Cold Water ◽  
Injection System ◽  
Passive Safety ◽  
Primary System ◽  
System Pressure ◽  
Pressure Medium ◽  
Safety Parameters ◽  
Core Cooling

In this work, a brand new passive safety injection system has been designed for the ocean-based Qinshan Phase I nuclear power plant to update and replace the traditional active ones. The passive safety injection system is made up of high pressure, medium pressure, lower pressure safety injection system, and a two-stage automatic depressurization system. To evaluate the safety injection system performance, double-ended cold leg large break LOCA has been analyzed by best-estimated safety analysis RELAP5 code. The main operation and safety parameters such as primary system pressure, safe injection mass flow rates, core water level, and peak cladding temperature have been presented. The results conclude that the safety injection system can act as similar to that of the AP1000, which can assure sufficient core cooling and keep the reactor covered by the cold water under the most severe LBLOCA condition.

scholarly journals RELAP5 Foresight Thermal-Hydraulic Analysis of Hypothesis Passive Safety Injection System under LOCA for an Existing NPP in China

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Lin Sun ◽  
Xuesong Wang ◽  
Jun Wang ◽  
Meiru Liu ◽  
Genglei Xia
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Injection System ◽  
Passive Safety ◽  
Main Stream ◽  
Hydraulic Analysis ◽  
Pressurized Water ◽  
System Pressure ◽  
Thermal Hydraulic Analysis

Qinshan nuclear power plant is the first large Chinese-designed nuclear power station based on pressurized water reactor, and the second generation main stream active safety injection system is adopted for Qinshan nuclear power plant. In this paper, a novel passive safety injection system (PSIS) has been proposed for ocean-based Qinshan Phase One nuclear power plant to replace the original active one. The PSIS contains high-pressure, medium-pressure, and lower-pressure safety injection systems, and a two-stage automatic depressurization system. To evaluate the system performance, small-break LOCA has been investigated using RELAP5. Various break sizes and locations including 2-inch, 10-inch cold leg break, and double-ended direct vessel injection line break were analyzed. Key safety parameters such as safe injection mass flow rates, coolant level of the core, system pressure, and fuel cladding temperature were monitored during the accident process. The results illustrate that the performance of the safety injection system can guarantee the effective core cooling and submerged under different LOCA even with only half of the safety injection system, which can fulfill the single failure criteria. The thermal-hydraulic analysis for the Qinshan passive safety injection system is significant to master the related technologies for Chinese engineer and develop the Chinese-designed third-generation nuclear power plants, and the PSIS can guarantee the reactor submerged under LOCA even plus the station block out accident.

Investigation of Hydrodynamic Loads Associated With Pyrotechnic Valve Actuation

2012 ◽  
Author(s):  
Christopher E. Henry ◽  
Jaehyok Lim ◽  
Basar Ozar
Keyword(s):  
Nuclear Power ◽  
Cooling System ◽  
High Reliability ◽  
Injection System ◽  
Vertical Force ◽  
Hydrodynamic Loads ◽  
System Pressure ◽  
Parallel Configuration ◽  
Core Cooling ◽  
Valve Actuation

Pyrotechnic-actuated valves are utilized for various applications requiring remote actuation with high reliability. One such application is passive safety injection (SI) within the emergency core cooling system (ECCS) within the Generation III+ advanced commercial nuclear power plant designs. The pyrotechnic (explosive) actuation within the valve internals, which opens the valve for water flow, creates a vertical force that must be supported by the surrounding piping restraints. This is a well-known phenomenon that is accommodated in the design. However, there exists also a subsequent, lesser-known axial (horizontal) force that must be accommodated also. A RELAP5/MOD3.3 (patch03) code [1] model for the pyrotechnic valve and the broader injection system was configured to analyze the extent of this water hammer. Typically, the pyrotechnic actuation occurs at relatively low reactor coolant system pressure since the injection itself will eventually be a passive gravity-driven feed. However, even at this low actuation pressure, the RELAP5 analysis demonstrates that the hydrodynamic loads can be substantial. Furthermore, the analysis shows that staggered actuation of a two-valve parallel configuration can exacerbate and magnify the load, compared to a single valve actuation.

Investigation of effects of nonavailability of passive safety systems on the reactor behaviour during LOCA Scenario in AP600

Kerntechnik ◽  
2021 ◽  
Vol 86 (3) ◽  
pp. 244-255
Author(s):  
S. H. Abdel-Latif ◽  
A. M. Refaey
Keyword(s):  
Passive Safety ◽  
Primary System ◽  
Water Storage Tank ◽  
The Core ◽  
Passive Safety Systems ◽  
Loss Of Coolant Accident ◽  
Passive Safety System ◽  
Stage 4 ◽  
Core Cooling ◽  
Safety Systems

Abstract The AP600 is a Westinghouse Advanced Passive PWR with a two–loop 1 940 MWt. This reactor is equipped with advanced passive safety systems which are designed to operate automatically at desired set-points. On the other hand, the failure or nonavailability to operate of any of the passive safety systems may affect reactor safety. In this study, modeling and nodalization of primary and secondary loops, and all passive reactor cooling systems are conducted and a 10-inch cold leg break LOCA is analyzed using ATHLET 3.1A Code. During loss of coolant accident in which the passive safety system failure or nonavailability are considered, four different scenarios are assumed. Scenario 1 with the availability of all passive systems, scenario 2 is failure of one of the accumulators to activate, scenario 3 is without actuation of the automatic depressurization system (ADS) stages 1–3, and scenario 4 is without actuation of ADS stage 4. Results indicated that the actuation of passive safety systems provide sufficient core cooling and thus could mitigate the accidental consequence of LOCAs. Failure of one accumulator during LOCA causes early actuation of ADS and In-Containment Refueling Water Storage Tank (IRWST). In scenario 3 where the LOCA without ADS stages 1–3 actuations, the depressurization of the primary system is relatively slow and the level of the core coolant drops much earlier than IRWST actuation. In scenario 4 where the accident without ADS stage-4 activation, results in slow depressurization and the level of the core coolant drops earlier than IRWST injection. During the accident process, the core uncovery and fuel heat up did not happen and as a result the safety of AP600 during a 10-in. cold leg MBLOCA was established. The relation between the cladding surface temperature and the primary pressure with the actuation signals of the passive safety systems are compared with that of RELAP5/Mode 3.4 code and a tolerable agreement was obtained.

Passive Safety Systems of Advanced Nuclear Power Plant: AP1000

2010 ◽  
Author(s):  
Guohua Yan ◽  
Chen Ye
Keyword(s):  
Nuclear Power ◽  
Human Error ◽  
Cooling System ◽  
Heat Removal ◽  
Injection System ◽  
Passive Safety ◽  
Human Errors ◽  
Power Sources ◽  
Passive Safety Systems ◽  
Safety Systems

In the entire history of commercial nuclear power so far, only two major accidents leading to damage of reactor core have taken place. One is Three Mile Island (TMT) accident (1979), which is caused by a series of human error, and the other is Chernobyl accident (1986), which is due to the combined reason of design defects and human errors. After TMI and Chernobyl accidents, in order to reduce manpower in operation and maintenance and influence of human errors on reactor safety, consideration is given to utilization of passive safety systems. According to the IAEA definition, passive safety systems are based on natural forces, such as convection and gravity, and stored energy, making safety functions less dependent on active systems and operators’ action. Recently, the technology of passive safety has been adopted in many reactor designs, such as AP1000, developed by Westinghouse and EP1000 developed by European vendor, and so on. AP1000 as the first so-called Generation III+ has received the final design approval from US NRC in September 2004, and now being under construction in Sanmen, China. In this paper, the major passive safety systems of AP1000, including passive safety injection system, automatic depressurization system passive residual heat removal system and passive containment cooling system, are described and their responses to a break loss-of-coolant accident (LOCA) are given. Just due to these passive systems’ adoption, the nuclear plant can be able to require no operator action and offsite or onsite AC power sources for at least 72h when one accident occurs, and the core melt and large release frequencies are significantly below the requirement of operating plants and the NRC safety goals.

Safety Analysis on Mitigation Overpressure ATWS in VVER-1000 NPP

2013 ◽  
Author(s):  
Ting Qi ◽  
Changjiang Yang
Keyword(s):  
Nuclear Power ◽  
Late Phase ◽  
Safety Analysis ◽  
Severe Accident ◽  
Injection System ◽  
Feed Water ◽  
System Pressure ◽  
Design Characteristics ◽  
Coolant System ◽  
Relap5 Code

Safety analysis on operating nuclear power plant (NPP) plays an important role on nuclear energy application, especially after the severe accident of Fukushima plants. This paper focuses on one of the operating NPPs in China, the TianWan NPP Unit1&2. TianWan Unit1&2 belong to VVER-1000 NPP type, which have special design characteristics and different safety migrating methods comparing with other domestic PWR NPPs in China. Calculations and analyses were made to give thermal hydraulics support to Level-1 PSA of this VVER type PWR on the anticipated transient without scram (ATWS) accidents. The calculation of loss of main feed water ATWS was carried out using the RELAP5 code to evaluate the intrinsic safety mainly impacted by fuel and moderator. The model also considers reactivity introduction caused by the change of boron concentration to find out the influence of the emergency boron injection system (JDH) on mitigating the coolant system over pressure. The paper gives out the success criteria of the safety valves of pressurizer (PRZ) with the critical moderator temperature coefficient (MTC) value according to the condition of coolant system pressure being under the pressure limit. It is indicated that the JDH system can play an important role on mitigating the over pressure of coolant system in the late phase of the transient.

Correction of Zero-Drift of Differential Pressure Flow Meters of ACME Facility

2014 ◽  
Author(s):  
Mingtao Cui ◽  
Tao Zhang
Keyword(s):  
Nuclear Power ◽  
Large Scale ◽  
Cooling System ◽  
Differential Pressure ◽  
Zero Drift ◽  
Test Facility ◽  
Passive Safety ◽  
Pressure Flow ◽  
Flow Meters ◽  
Core Cooling

ACME facility (Advanced Core-cooling Mechanism Experiment) is a large-scale test facility used to validate the performance of passive core-cooling system under SBLOCA (Small Break Lost of Coolant Accident) for the CAP1400, an upgraded passive safety nuclear power plant of AP1000. To simulate the features of passive safety system properly, DELTABAR, a kind of differential pressure flow meter, is designed to measure different mass flow of ACME. Because of the low pressure loss of DELTABAR, Zero-Drift problem of differential pressure flow meters in ACME is amplified, and some of the measured values are distorted seriously. To minimize the influence of Zero-Drift, analysis on zero-drift phenomenon is made, and a compensation method is proposed. The method is applying to PBL flow meters, and the result shows that the method is applicable.

scholarly journals Research and Evaluation for Passive Safety System in Low Pressure Reactor

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Peng Chuanxin ◽  
Zhuo Wenbin ◽  
Chen Bingde ◽  
Nie Changhua ◽  
Huang Yanping
Keyword(s):  
Steady State ◽  
Satisfactory Agreement ◽  
Nuclear Power ◽  
Low Pressure ◽  
Safety System ◽  
Test Facility ◽  
Passive Safety ◽  
Passive Safety System ◽  
Calculation Results ◽  
Core Cooling

Low pressure reactor is a small size advanced reactor with power of 180 MWt, which is under development at Nuclear Power Institute of China. In order to assess the ability and feasibility of passive safety system, several tests have been implemented on the passive safety system (PSS) test facility. During the LOCA and SBO accident, the adequate core cooling is provided by the performance of passive safety system. In addition the best-estimate thermal hydraulic code, CATHARE V2.1, has been assessed against cold leg LOCA test. The calculation results show that CATHARE is in a satisfactory agreement with the test for the steady state and transient test.

Test Analysis of CAP1400 5cm Break Accident Based on the ACME Test Facility

2016 ◽  
Author(s):  
Sheng Zhu
Keyword(s):  
System Design ◽  
Nuclear Power ◽  
Reactor Core ◽  
Safety System ◽  
Test Facility ◽  
Passive Safety ◽  
Pressurized Water ◽  
Power Simulation ◽  
Passive Safety System ◽  
Core Cooling

CAP1400 is a large pressurized water reactor based on the passive safety conception. An ACME (Advanced Core-cooling Mechanism Experiment) facility has been designed and constructed in order to validate that the CAP1400 system design is acceptable to mitigate the loss of coolant accident (LOCA). The ACME test facility is an isotonic pressure, 1/3-scale height and 1/54.32-scale power simulation of the prototype CAP1400 nuclear power plant. It contains the main-loop system, passive safety system, secondary steam system and auxiliary system etc. The all of ACME test matrix including 5 kinds 21 cases .In this paper, the test results and the Realp5 prediction of the cold leg 5cm break accident of CAP1400 are compared and analyzed to briefly evaluate the ACME capability. Furthermore, 3 different types of 5cm cold leg break test cases are presented, and the transient process, system responses and key parameters tendency are analyzed based on the test. The results indicate that the passive safety system design can successfully combine to provide a continuous removal of core decay heat and the reactor core remains to be covered with considerable margin for the 3 different 5cm cold leg break accidents.

Preliminary Safety Analysis of a Compact Small Reactor: Feedwater Line Break and Small-Break LOCA Accident Analysis

2017 ◽  
Author(s):  
Linsen Li ◽  
Feng Shen ◽  
Mian Xing ◽  
Zhan Liu ◽  
Zhanfei Qi
Keyword(s):  
Conceptual Design ◽  
Cooling System ◽  
Passive Safety ◽  
Accident Analysis ◽  
Primary System ◽  
Primary Coolant ◽  
Pressurized Water ◽  
Passive Safety Systems ◽  
Core Cooling ◽  
Safety Systems

A small Pressurized Water Reactor (PWR) with compact primary system and passive safety feature, which is called Compact Small Reactor (CSR), is under pre-conceptual design and development. For the purpose of preliminary assessment of the primary coolant system and capability evaluation of the passive safety system, a detailed thermal-hydraulic (T-H) system model of the CSR was developed. Several design-basis accidents, including feedwater line break, double ended direct vessel injection line break (one of the small-break Loss Of Coolant Accidents, LOCA) and etc, are selected and simulated so as to evaluate and further optimize the design of passive safety systems, especially the passive core cooling system. The results of preliminary accident analysis show that the passive safety systems are basically capable of mitigating the accidents and protecting the reactor core from severe damage. Further research will be focused on the optimization of pre-conceptual design of the thermal-hydraulic system and the passive core cooling system.

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