Emergency Strategy Research of Loss of Coolant Accident for Small Modular Reactor

2017 ◽  
Author(s):  
Wang Yuqi ◽  
Yu Aimin ◽  
Yang Qingming
Keyword(s):  
Simulation System ◽  
Passive Safety ◽  
Strategy Research ◽  
Passive Safety Systems ◽  
Loss Of Coolant Accident ◽  
Small Modular Reactor ◽  
Loss Of Coolant ◽  
Full Power ◽  
Safety Systems ◽  
Emergency Operating

This paper researched the behavior of 20mm break Loss of Coolant Accident (LOCA) which is located in the Direct Vessel Injection (DVI) line of the integrated small modular reactor (SMR) in case of full power with RELAP5-3KEYMASTER simulation system. The response of passive safety systems is analyzed and compared with the Primary Safety Analysis Report (PSAR) post-accident. Tendency for the variation of main parameters after the accident agree well with the PSAR, which validates the accuracy and rationality of the model, and solves the new problems in the process of modeling and provides an important tool for the research and development of SMR. Cooling and depressurization are calculated post-accident. The variation of main parameters post-accident and the accident advancement and results have been analyzed. Operation intervention is given and the effects with it are discussed. And the emergency strategy for development and verification of Emergency Operating Procedures (EOP) is given.

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.

LOCA Break Spectrum Analysis of the Westinghouse Small Modular Reactor

2013 ◽  
Author(s):  
Vefa N. Kucukboyaci ◽  
Jun Liao
Keyword(s):  
Spectrum Analysis ◽  
Evaluation Model ◽  
Reactor Core ◽  
Reactor Vessel ◽  
Passive Safety ◽  
Plant Design ◽  
Pressurized Water ◽  
Passive Safety Systems ◽  
Small Modular Reactor ◽  
Safety Systems

The Westinghouse Small Modular Reactor (SMR) is an 800 MWt (> 225 MWe) integral pressurized water reactor with all primary components, including the steam generator and the pressurizer located inside the reactor vessel. The reactor core is based on a partial-height 17×17 fuel assembly design used in the AP1000® reactor core. The Westinghouse SMR utilizes passive safety systems and proven components from the AP1000 plant design with a compact containment that houses the integral reactor vessel and the passive safety systems. A break spectrum analysis on the Westinghouse SMR LOCA has been performed to investigate the performance of the SMR passive cooling. The break type includes both the double-ended guillotine (DEG) break and the split break with the break size ranging from 0.5 inch to the diameter of direct vessel injection (DVI) line. The break spectrum analysis was performed using the WCOBRA/TRAC-TF2 code, which is designed to simulate PWR LOCA events from the smallest break size to the largest break size. The break spectrum analysis demonstrates that excellent performance of the passive safety system of the Westinghouse SMR in variable LOCA conditions. The study is also a necessary step to develop an evaluation model for the analysis of design basis LOCA accident.

Modeling Passive Safety in the Westinghouse Small Modular Reactor: Assessment of Wall Condensation and CMT Natural Circulation

2013 ◽  
Author(s):  
Jun Liao ◽  
Vefa N. Kucukboyaci
Keyword(s):  
Natural Circulation ◽  
Passive Safety ◽  
Reactor Safety ◽  
Heat Transfer Mechanism ◽  
The Core ◽  
Design Basis ◽  
Loss Of Coolant Accident ◽  
Small Modular Reactor ◽  
Loss Of Coolant ◽  
Safety Design

Passive safety design that utilizes gravity, natural circulation, heat sink and stored potential energy for reactor safety functions is being increasingly adopted in advanced reactors, especially in the small modular reactor (SMR) designs. The passive safety design of the Westinghouse SMR is described in details and compared with the AP1000® passive safety design. The natural circulation loops and heat transfer mechanism in a postulated Westinghouse SMR loss of coolant accident (LOCA) are discussed. The key thermal hydraulic phenomena pertinent to the passive safety design of the Westinghouse SMR have been identified in the small break LOCA Phenomena Identification and Rank Table (PIRT). Among the identified phenomena, condensation on the containment wall and natural circulation in core makeup tank (CMT) loop are highly ranked. Those passive safety phenomena are expected to be assessed using the WCOBRA/TRAC-TF2 LOCA thermal hydraulic code, which will provide the design basis LOCA analysis in the SMR design control documentation. In this paper, the progress on the assessing two key phenomena in passive safety of Westinghouse SMR is reported. The preliminary assessments against UCB tube condensation tests and Westinghouse core makeup tank tests reveals the capability of WCOBRA/TRAC-TF2 code to reasonably predict the condensation on the containment wall and natural circulation in the core makeup tank (CMT) loop.

scholarly journals The Investigation of Nonavailability of Passive Safety Systems Effects on Small Break LOCA Sequence in AP1000 Using RELAP5 MOD 4.0

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Anwar Hussain ◽  
Amjad Nawaz
Keyword(s):  
Active Region ◽  
Reactor Core ◽  
Passive Safety ◽  
Primary System ◽  
Passive Safety Systems ◽  
Passive Safety System ◽  
Stage 4 ◽  
Loss Of Coolant ◽  
Core Cooling ◽  
Safety Systems

The passive safety systems of AP1000 are designed to operate automatically at desired set-points. However, the unavailability or failure to operate of any of the passive safety systems will change the accident sequence and may affect reactor safety. The analysis in this study is based on some hypothetical scenarios, in which the passive safety system failure is considered during the loss of coolant accidents. Four different cases are assumed, that is, with all passive systems, without actuation of one of the accumulators, without actuation of ADS stages 1–3, and without actuation of ADS stage 4. The actuation of all safety systems at their actuation set-points provides adequate core cooling by injecting sufficient water inventory into reactor core. The LOCA with actuation of one of the accumulators cause early actuation of ADS and IRWST. In case of LOCA without ADS stages 1–3, the primary system depressurization is relatively slow and mixture level above core active region drops much earlier than IRWST actuation. The accident without ADS stage 4 actuation results in slow depressurization and mixture level above core active region drops earlier than IRWST injection. Moreover, the comparison of cladding surface temperature is performed in all cases considered in this work.

iB1350: A Generation III.7 Reactor After the Fukushima Daiichi Accident

2016 ◽  
Author(s):  
Takashi Sato ◽  
Keiji Matsumoto ◽  
Kenji Hosomi ◽  
Keisuke Taguchi
Keyword(s):  
Cooling System ◽  
Boiling Water ◽  
Passive Safety ◽  
Active Safety ◽  
Water Reactor ◽  
Airplane Crash ◽  
Passive Safety Systems ◽  
Active Safety Systems ◽  
Fukushima Daiichi ◽  
Safety Systems

iB1350 stands for an innovative, intelligent and inexpensive boiling water reactor 1350. It is the first Generation III.7 reactor after the Fukushima Daiichi accident. It has incorporated lessons learned from the Fukushima Daiichi accident and Western European Nuclear Regulation Association safety objectives. It has innovative safety to cope with devastating natural disasters including a giant earthquake, a large tsunami and a monster hurricane. The iB1350 can survive passively such devastation and a very prolonged station blackout without any support from the outside of a site up to 7 days even preventing core melt. It, however, is based on the well-established proven Advance Boiling Water Reactor (ABWR) design. The nuclear steam supply system is exactly the same as that of the current ABWR. As for safety design it has a double cylinder reinforced concrete containment vessel (Mark W containment) and an in-depth hybrid safety system (IDHS). The Mark W containment has double fission product confinement barriers and the in-containment filtered venting system (IFVS) that enable passively no emergency evacuation outside the immediate vicinity of the plant for a severe accident (SA). It has a large volume to hold hydrogen, a core catcher, a passive flooding system and an innovative passive containment cooling system (iPCCS) establishing passively practical elimination of containment failure even in a long term. The IDHS consists of 4 division active safety systems for a design basis accident, 2 division active safety systems for a SA and built-in passive safety systems (BiPSS) consisting of an isolation condenser (IC) and the iPCCS for a SA. The IC/PCCS pools have enough capacity for 7-day grace period. The IC/PCCS heat exchangers, core and spent fuel pool are enclosed inside the containment vessel (CV) building and protected against a large airplane crash. The iB1350 can survive a large airplane crash only by the CV building and the built-in passive safety systems therein. The dome of the CV building consists of a single wall made of steel and concrete composite. This single dome structure facilitates a short-term construction period and cost saving. The CV diameter is smaller than that of most PWR resulting in a smaller R/B. Each active safety division includes only one emergency core cooling system (ECCS) pump and one emergency diesel generator (EDG). Therefore, a single failure of the EDG never causes multiple failures of ECCS pumps in a safety division. The iB1350 is based on the proven ABWR technology and ready for construction. No new technology is incorporated but design concept and philosophy are initiative and innovative.

Improved Occupant Protection through Cooperation of Active and Passive Safety Systems – Combined Active and Passive Safety CAPS

2006 ◽  
Author(s):  
Alfred Kuttenberger ◽  
Sybille Eisele ◽  
Thomas Lich ◽  
Thorsten Sohnke ◽  
Jorge Sans Sangorrin ◽  
...  
Keyword(s):  
Passive Safety ◽  
Occupant Protection ◽  
Passive Safety Systems ◽  
Safety Systems

scholarly journals Modeling The Frontal Collison In Vehicles And Determining The Degree Of Injury On The Driver

2015 ◽  
Vol 67 (1) ◽  
pp. 115-120
Author(s):  
Oana Victoria Oţăt
Keyword(s):  
Dynamic Behaviour ◽  
Research Study ◽  
Research Paper ◽  
Passive Safety ◽  
Steering Wheel ◽  
Passive Safety Systems ◽  
Frontal Collision ◽  
Safety Systems

Abstract The present research study aims at analysing the kinematic and the dynamic behaviour of the vehicle’s driver in a frontal collision. Hence, a subsequent objective of the research paper is to establish the degree of injury suffered by the driver. Therefore, in order to achieve the objectives set, first, we had to define the type of the dummy placed in the position of the driver, and then to design the three-element assembly, i.e. the chair-steering wheel-dashboard assembly. Based on this model, the following step focused on the positioning of the dummy, which has also integrated the defining of the contacts between the components of the dummy and the seat elements. Seeking to model such a behaviour that would highly accurately reflect the driver’s movements in a frontal collision, passive safety systems have also been defined and simulated, namely the seatbelt and the frontal airbag.

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