• Title, Summary, Keyword: Passive Safety System

Search Result 173, Processing Time 0.042 seconds

The concept of the innovative power reactor

  • Lee, Sang Won;Heo, Sun;Ha, Hui Un;Kim, Han Gon
    • Nuclear Engineering and Technology
    • /
    • v.49 no.7
    • /
    • pp.1431-1441
    • /
    • 2017
  • The Fukushima accident reveals the vulnerability of existing active nuclear power plant (NPP) design against prolonged loss of external electricity events. The passive safety system is considered an attractive alternative to cope with this kind of disaster. Also, the passive safety system enhances both the safety and the economics of NPPs. The adoption of a passive safety system reduces the number of active components and can minimize the construction cost of NPPs. In this paper, reflecting on the experience during the development of the APR+ design in Korea, we propose the concept of an innovative Power Reactor (iPower), which is a kind of passive NPP, to enhance safety in a revolutionary manner. The ultimate goal of iPower is to confirm the feasibility of practically eliminating radioactive material release to the environment in all accident conditions. The representative safety grade passive system includes a passive emergency core cooling system, a passive containment cooling system, and a passive auxiliary feedwater system. Preliminary analysis results show that these concepts are feasible with respect to preventing and/or mitigating the consequences of design base accidents and severe accidents.

ASSESSMENT OF CONDENSATION HEAT TRANSFER MODEL TO EVALUATE PERFORMANCE OF THE PASSIVE AUXILIARY FEEDWATER SYSTEM

  • Cho, Yun-Je;Kim, Seok;Bae, Byoung-Uhn;Park, Yusun;Kang, Kyoung-Ho;Yun, Byong-Jo
    • Nuclear Engineering and Technology
    • /
    • v.45 no.6
    • /
    • pp.759-766
    • /
    • 2013
  • As passive safety features for nuclear power plants receive increasing attention, various studies have been conducted to develop safety systems for 3rd-generation (GEN-III) nuclear power plants that are driven by passive systems. The Passive Auxiliary Feedwater System (PAFS) is one of several passive safety systems being designed for the Advanced Power Reactor Plus (APR+), and extensive studies are being conducted to complete its design and to verify its feasibility. Because the PAFS removes decay heat from the reactor core under transient and accident conditions, it is necessary to evaluate the heat removal capability of the PAFS under hypothetical accident conditions. The heat removal capability of the PAFS is strongly dependent on the heat transfer at the condensate tube in Passive Condensation Heat Exchanger (PCHX). To evaluate the model of heat transfer coefficient for condensation, the Multi-dimensional Analysis of Reactor Safety (MARS) code is used to simulate the experimental results from PAFS Condensing Heat Removal Assessment Loop (PASCAL). The Shah model, a default model for condensation heat transfer coefficient in the MARS code, under-predicts the experimental data from the PASCAL. To improve the calculation result, The Thome model and the new version of the Shah model are implemented and compared with the experimental data.

Performance analysis of the passive safety features of iPOWER under Fukushima-like accident conditions

  • Kang, Sang Hee;Lee, Sang Won;Kang, Hyun Gook
    • Nuclear Engineering and Technology
    • /
    • v.51 no.3
    • /
    • pp.676-682
    • /
    • 2019
  • After the Fukushima Daiichi accident, there has been an increasing preference for passive safety features in the nuclear power industry. Some passive safety systems require limited active components to trigger subsequent passive operation. Under very serious accident conditions, passive safety features could be rendered inoperable or damaged. This study evaluates (i) the performance and effectiveness of the passive safety features of iPOWER (innovative Power Reactor), and (ii) whether a severe accident condition could be reached if the passive safety systems are damaged, namely the case of heat exchanger tube rupture. Analysis results show that the reactor coolant system remains in the hot shutdown condition without operator actions or electricity for over 72 h when the passive auxiliary feedwater systems (PAFSs) are operable without damage. However, heat exchanger tube rupture in the PAFS leads to core damage after about 18 h. Such results demonstrate that, to enhance the safety of iPOWER, maintaining the integrity of the PAFS is critical, and therefore additional protections for PAFS are necessary. To improve the reliability of iPOWER, additional battery sets are necessary for the passive safety systems using limited active components for accident mitigation under such extreme circumstances.

Comparative Experiments to Assess the Effects of Accumulator Nitrogen Injection on Passive Core Cooling During Small Break LOCA

  • Li, Yuquan;Hao, Botao;Zhong, Jia;Wang, Nan
    • Nuclear Engineering and Technology
    • /
    • v.49 no.1
    • /
    • pp.54-70
    • /
    • 2017
  • The accumulator is a passive safety injection device for emergency core cooling systems. As an important safety feature for providing a high-speed injection flow to the core by compressed nitrogen gas pressure during a loss-of-coolant accident (LOCA), the accumulator injects its precharged nitrogen into the system after its coolant has been emptied. Attention has been drawn to the possible negative effects caused by such a nitrogen injection in passive safety nuclear power plants. Although some experimental work on the nitrogen injection has been done, there have been no comparative tests in which the effects on the system responses and the core safety have been clearly assessed. In this study, a new thermal hydraulic integral test facility-the advanced core-cooling mechanism experiment (ACME)-was designed and constructed to support the CAP1400 safety review. The ACME test facility was used to study the nitrogen injection effects on the system responses to the small break loss-of-coolant accident LOCA (SBLOCA) transient. Two comparison test groups-a 2-inch cold leg break and a double-ended direct-vessel-injection (DEDVI) line break-were conducted. Each group consists of a nitrogen injection test and a nitrogen isolation comparison test with the same break conditions. To assess the nitrogen injection effects, the experimental data that are representative of the system responses and the core safety were compared and analyzed. The results of the comparison show that the effects of nitrogen injection on system responses and core safety are significantly different between the 2-inch and DEDVI breaks. The mechanisms of the different effects on the transient were also investigated. The amount of nitrogen injected, along with its heat absorption, was likewise evaluated in order to assess its effect on the system depressurization process. The results of the comparison and analyses in this study are important for recognizing and understanding the potential negative effects on the passive core cooling performance caused by nitrogen injection during the SBLOCA transient.

Design and Application of Harmonic Passive Filter (고조파 수동필터의 설계 및 적용)

  • Jeon, Jeong-Chay;Kim, Jae-Hyun;Yoo, Jae-Geun
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.13 no.11
    • /
    • pp.5397-5402
    • /
    • 2012
  • Accidents involving electric equipment and economical loss by power quality deterioration related to harmonics show a rising tendency A passive filter is economic and efficient in suppressing harmonics but many engineers and designers are reluctant to install a passive filter to defect harmonics at their power system because of problems such as harmonic amplification and the probability of generating series or parallel resonance with the power system. This work introduces that passive filters will be very available to defeat harmonic problems of the power system if passive filters are well designed. We describe method and process of harmonic passive filter design. And the passive filter for the power system having harmonic problems due to use of nonlinear loads like as 100HP DC motor system, an extruding machine, an air blower and other loads are designed. Experimental results verify the performance of the passive filter designed by the described method and procedure.

Development of an Air-Water Combined Cooling System (공냉-수냉 혼합냉각계통 개발)

  • Kwon, Tae-Soon;Bae, Sung-Won
    • The KSFM Journal of Fluid Machinery
    • /
    • v.17 no.6
    • /
    • pp.84-88
    • /
    • 2014
  • A long term passive cooling system is considered as the most important safety feature for the nuclear design after the Fukushima Daiichi nuclear power plant accident in 2011. The conventional active pump driven safety systems are not available during a station Black Out (SBO) accident. The current design requirement on cooling time of the Passive Auxiliarly Feedwater System (PAFS) is about 8 hours only. To meet the 72 hours cooling time, the pool capacity of cooling water tank should be increased as much as 3~4 times larger than that of current water cooling tank. In order to extend the cooling time for 72 hours, a new passive air-water combined cooling system is proposed. This paper provides the feasibility of the combined passive air-water cooling system. The current pool capacity of water cooling system is preserved, and the cooling capability is extended by an additional air cooler.

Design of Passive Filter for Harmonic Elimination of the Load System (부하설비의 고조파 저감을 위한 수동필터 설계)

  • Son, Jae-Hyun;Kang, Chang-Seob;Lee, Hong-Gee;Yoon, Chul-Sup
    • Proceedings of the KIEE Conference
    • /
    • /
    • pp.276-278
    • /
    • 1997
  • The aim of this study is to design a passive filter for the elimination of harmonics. For this design, the harmonics wave generating from the six pulse rectifier was measured and its characteristics were analyzed. We also calculated the quantity of harmonic current by changing the system operational conditions. According to this field data and calculated results. we determined the elements of the passive filter. The simulation results indicate the efficiency of designed passive filter.

  • PDF

A Study on the Energy Improvement Plan of using Passive Design with Exterior Envelopes and Renewable Energy for Bio Safety Labotratory (외피의 Passive Design 요소와 신재생에너지를 적용한 생물안전 밀폐시설의 에너지 시스템 개선방안 연구)

  • Hwang, Ji Hyun;Bum, Do;Hong, Jin Kwan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
    • /
    • v.26 no.10
    • /
    • pp.491-496
    • /
    • 2014
  • In general, the entire air supply of a bio-safety laboratory (BSL) should be exhausted on the outside to ensure bio-safety, and the air conditioning system should always be operated to maintain a difference in the room pressure. As a result, the annual energy consumption of such a building is approximately five or ten times higher than that of an office building of the same magnitude. Thus, this study applies an actual operating system that targets BSL. The energy consumption is analyzed using the Energy Plus V8.0 program (an energy analysis program), and five kinds of cases that depend on the energy consumption of the basic BSL system are also analyzed. As a result, the energy consumption in Case 1 (basic system) is of 324.95 GJ. When the basic system of Case 1 is compared to that in Case 2 (basic system+passive design with exterior envelopes), an annual energy savings of is 6.9% is achieved. For Case 3 (basic system+Photovoltaic, PV) 12.7% is achieved, and for Case 4 (Solar Geothermal Hybrid System of renewable energy, SGHS) 49.5% is achieved. If a passive design with exterior envelopes and renewable energy system (PV+SGHS) is combined, as in Case 5, the energy consumption would be 118.15 GJ. Therefore, when this last system is compared to a basic system, the passive design with exterior envelopes and renewable energy system (PV+SGHS) can reduce energy consumption by 63.6%.

Optimal Design of Hybrid Control System through Inter-Building Connection (빌딩간 연결을 통한 복합제어시스템의 최적설계)

  • Park, Kwan-Soon;Ok, Seung-Yong
    • Journal of the Korean Society of Safety
    • /
    • v.32 no.6
    • /
    • pp.81-88
    • /
    • 2017
  • This study deals with the optimal design of a hybrid control system composed of a combination of active control system and passive control system for effective seismic performance improvement of two adjacent structures. The proposed hybrid control system adopts a configuration of installing an active control device in one building and connecting two adjacent structures with a passive control device so that the one-side active control force can be bi-directionally applied to both buildings through the passive connecting devices. In order to derive the optimal performance of the proposed system, the design parameters of the passive and active control systems were searched using the genetic algorithm. Numerical simulations of 10-story and 8-story buildings have been performed to verify the effectiveness of the proposed technique. For the purpose of comparison, the conventional independent control system with two identical active control systems being installed separately for each structure was also optimally designed and its seismic response has been evaluated as well. From the comparative results of the two control systems, it is demonstrated that the proposed hybrid control system requires larger control force for its one-side active control device than the conventional independent control system does for each of both-side active devices, but quite less than the total control force required for both-side devices of the independent control system, while maintaining similar seismic performance. Therefore, the proposed system is more economical and reliable than the conventional independent control system with two identical active devices.

Multivariate analysis of critical parameters influencing the reliability of thermal-hydraulic passive safety system

  • Olatubosun, Samuel Abiodun;Zhang, Zhijian
    • Nuclear Engineering and Technology
    • /
    • v.51 no.1
    • /
    • pp.45-53
    • /
    • 2019
  • Thermal-hydraulic passive safety systems (PSSs) are incorporated into many advanced reactor designs on the bases of simplicity, economics and inherent safety nature. Several factors among which are the critical parameters (CPs) that influence failure and reliability of thermal-hydraulic (t-h) passive systems are now being explored. For simplicity, it is assumed in most reliability analyses that the CPs are independent whereas in practice this assumption is not always valid. There is need to critically examine the dependency influence of the CPs on reliability of the t-h passive systems at design stage and in operation to guarantee safety/better performance. In this paper, two multivariate analysis methods (covariance and conditional subjective probability density function) were presented and applied to a simple PSS. The methods followed a generalized procedure for evaluating t-h reliability based on dependency consideration. A passively water-cooled steam generator was used to demonstrate the dependency of the identified key CPs using the methods. The results obtained from the methods are in agreement and justified the need to consider the dependency of CPs in t-h reliability. For dependable t-h reliability, it is advisable to adopt all possible CPs and apply suitable multivariate method in dependency consideration of CPs among other factors.