rabbit vibrators sex toy monthly about hvac

rabbit vibrators sex toy,False penis color girl,sex shock toy porn

Views : 260
Update time : 2021-05-07 18:44:27

By Peng Yongsen , Liu Zhengie, Wang Junmin, Liu Chao and Fan Lewang
【Abstract】 According to the study of relevant regulations, standards and good practices at home and abroad, discusses the types and typical countermeasures of common cause failures, and summarizes the common cause failure analysis method, process and countermeasures for HVAC systems in nuclear power plants.
【Keywords】 nuclear power plant, HVAC system, common cause failure, diversity, failure analysis
* China Nuclear Power Design Company Ltd. (Shenzhen), Shenzhen, Guangdong Province, China

Forward
Common-cause failure refers to a failure caused by a single event or cause if the device, component or system fails. As an important supporting system of nuclear power plant, HVAC safety system of nuclear power plant bears the safety function of providing good environmental conditions for equipment operation and personnel operation of frontier system. Because HVAC system has the characteristics of wide service range and numerous equipment, its potential common cause failure risk may affect the function of frontier system of nuclear power plant, and then affect the safety of nuclear power plant. With the improvement of safety requirements of nuclear power plants, nuclear power plants at home and abroad pay more and more attention to common-cause fault analysis of HVAC system. A set of methodology for common-cause fault identification, analysis and response of HVAC system in nuclear power plants is established by summarizing relevant domestic and foreign codes and good practices
1.
Common fault types and typical countermeasures
The relevant regulations and standards of nuclear power plants at home and abroad put forward the following requirements for preventing common cause failure of important safety items in nuclear power plants
1)HAF 102-2016 stipulates that the possibility of common cause failure of important safety items must be considered to determine where the principles of diversity, multiplicity and independence should be applied to achieve the required reliability "
 
2)IAEA SSR-2/1-2012 stipulates that the reliability, redundancy, diversity and independence of the design support service system, as well as the characteristics of providing isolation and functional capability test for it, must be compatible with the safety importance of the system it supports. A failure of the support service system shall not be allowed to simultaneously affect the redundant components of a safety system or a system performing various safety functions and impair the ability of these systems to perform their safety functions.
 
3)IAEA SSG-62-2020 stipulates that, when applicable, common cause faults among redundant components of auxiliary systems and supporting systems used to support safety systems should be identified, and measures should be taken in design and layout to make redundant components as independent as possible. Prevent common cause failures in appropriate ways, such as physical isolation and functional independence. It is necessary to analyze the possible combination between common cause failures and assumed originating events among redundant security systems. If the consequence of this combination exceeds the limit of design basis accident, the possibility of this combination should be reduced or eliminated or additional design should be adopted to deal with this situation.
4)Common cause failures that may lead to failure of safety functions are classified into four categories in ONR-NS-TAT-GD-036.

,Functional dependency: common cause caused by shared or common functional features, such as shared power supply, shared cooling water system or shared labor Art fluid.

,Spatial dependence: common cause caused by physical characteristics shared by components in the same space, such as the same radiation or chemical conditions Same environment and same supporting structure, etc.

,Inherent dependency: common cause caused by the same technical characteristics, such as adopting the same operating principle or technology and the same failure mode (such as mechanical overload or overpressure)

④ , Human factor dependence: the common cause related to human error, due to the human factor error in the process of affecting some shared or the same personnel activities And produce, such as human error in design or manufacture, operator error in operation and maintenance process.

Functional dependency: common cause caused by shared or common functional features, such as shared power supply, shared cooling water system or shared labor Art fluid.
5)NUREG/CR-7007 gives the main countermeasures for common fault.
① Diversification: including adopting different operating conditions, different working principles, different design teams, equipment with different sizes, different manufacturers, different components and equipment with different physical principles.

② Entity separation: geometric separation or barrier separation (such as separation from barrier mode and orientation) is adopted.
③ Functional isolation: measures such as effective isolation and electrical isolation between safety system and non-safety system. Combined with the requirements of the above specifications, typical common-cause personnel failures and countermeasures of nuclear power plants are summarized, as shown in Table 1

Table 1 Common Cause Fault Types and Typical Countermeasures
countermeasure
Functional dependency Function isolation, effective isolation between safety system and non-safety system, electrical isolation and other measures shall be adopted to prevent the sharing between safety functions and between safety functions and non-safety functions Due to wind
Spatial dependencyEntity separation uses geometric separation or barrier separation (such as distance orientation) to prevent an initial event or secondary event from causing multiple systems or disabling multiple parts of a system
Inherent dependence, human dependenceDiversified design, set up two or more multiple components or systems to perform a certain function, and make these different mails or systems have different attributes, so as to reduce the possibility of common cause failure


2.Methodology and process of common cause fault analysis of HVAC system

In order to reduce the common-cause faults of HVAC system in an all-round way, it is necessary to identify all the potential common-cause fault points of the system effectively, and then make a reasonable and feasible improvement scheme to minimize the risk of wind. Combined with the types of common-cause faults mentioned above, the overall process of common-cause fault analysis of HVAC system is formulated, as shown in Figure 1. Change the design of air-to-air system support system to improve the design of electrical and cooling water system. Revision 1. Overall process of common-cause fault analysis of HVAC system, as shown in Figure 1.






 

Fig. 1 Overall process of common cause fault analysis of HVAC system

2.1Identification of Common Cause Risk of System

For different types of common-cause faults in HVAC systems, targeted identification methods should be adopted. For common-cause faults with inherent and human factors depending on class, safety analysis methods are generally used to identify common-cause risks in HVAC system design. For functional dependency, find the risk point of common cause of support system through failure analysis of support system of HVAC system; For spatial dependence, common cause risk points are identified by disaster analysis.

2.1.1 Identification of Common Cause Risk of HVAC System As a part of nuclear power plant support system, HVAC system provides ventilation and cooling for nuclear power plant frontier process systems and other support systems (such as electrical and instrument control cabinets). Failure of HVAC system may lead to common cause failure of safety functions of the power plant, which may lead to serious consequences, especially the failure of defense-in-depth system of nuclear power plant caused by HVAC system. The weakness of HVAC system design can be identified through nuclear power plant safety analysis, such as failure consequence analysis and initial event analysis, and avoided through diversified design of HVAC system. The methods to identify risks are as follows:
1)Through accident analysis of nuclear power plant, according to the principle that the safety system for dealing with high-frequency accidents of nuclear power plant needs to adopt diversified design, with high-frequency events as the main line, analyze whether its support system (HVAC system) is diversified. Table 2 gives an example of small breach accident analysis in nuclear power plant. It should be noted that the indirect consequences of HVAC system failure also need to be analyzed, such as distribution cabinets E1 and E2 or control in the above cases The ambient temperature of cabinets ⅱ 1 and 12 is controlled by the same HVAC system or two HVAC systems with common cause risk, which may indirectly lead to the failure of medium-pressure safety injection and low-pressure safety injection systems due to common cause failure of HVAC systems, so the failure analysis should be comprehensive.

Table 2 Analysis Cases of High Frequency Accidents-Small Breakage Accidents
Main line of defense Support system of main defense line Diversified defense line Support system of diversified defense lines Common Cause Risk Analysis of HVAC
Medium pressure safety injection system Distribution cabinet E1 Control cabinet 11 HVAC system A Low pressure safety injection system Distribution cabinet E2 Control cabinet I2 HVAC system A HVAC system A serves both medium-pressure safety injection and low-pressure safety injection systems, and its failure will lead to over-temperature of rooms of medium-pressure safety injection and low-pressure safety injection systems, which will lead to simultaneous failure of both systems. The safety analysis results are unacceptable, so it is necessary to consider the diversification of HVAC systems.

2) Through the initial event analysis of the support system, find the initial event caused by the failure of the HVAC system, if the initial event does not exist. Effective means to alleviate, it is necessary to consider the part of the HVAC system for diversified improvement, to prevent the occurrence of the incident. Through the above two methods, we can find the HVAC system that needs to be designed in various ways, and then further analyze this part of the system and make a reasonable improvement plan.


2.1.2 Identification of Common Cause Risk of HVAC Support System

The supporting systems of HVAC system mainly include cooling water system, electrical system and instrument control system, which may lead to the failure of several HVAC systems, so special attention should be paid to the consequences of failure. Through the analysis of the failure consequences of the support system, the risk of common cause failure of HVAC system caused by the failure of the support system is identified. Combined with the analysis results in Section 2.1.1, the failure mode of the support system that causes the failure of HVAC system with diversified requirements is identified, and then the improvement measures are formulated accordingly. Common fault of control and electrical system of nuclear power plant can be analyzed with reference to NUREG /CR-7007.

2.1.3 identification of common cause risks caused by disasters

Through the analysis of internal and external disasters, this paper studies the spatial dependence of HVAC systems, analyzes the possibility and consequences of simultaneous failure of multiple redundant HVAC systems caused by internal and external disasters, and identifies the common failure risk points of HVAC systems caused by internal and external disasters.

2.2determination of HVAC system improvement scheme

According to the identified common cause risk points of HVAC system, sort out all potential improvement schemes, evaluate the benefits of each improvement scheme in terms of safety and engineering cost item by item, and determine the final scheme in combination with various factors such as feasibility and technical maturity of the scheme. For the common cause risk points of HVAC system itself, various methods are mainly used to improve it. Chapter 3 will elaborate the process and methods in detail; For the common cause risk points of HVAC system support system, the method of supporting system diversification is mainly used to improve it. This part is not the scope of HVAC system design, so we can refer to the achievements in related fields and do not discuss it in this paper; For the common cause risk points caused by disasters, it is mainly improved by optimizing the layout and improving the identification requirements of HVAC equipment.

 

2.3implementation of HVAC system improvement scheme

After determining the improvement scheme, it is necessary to carry out impact analysis on the improvement scheme, determine the impact scope and implementability of the improvement, determine that the scheme is executable, and implement the improvement scheme. If it is found that the improvement scheme cannot be implemented, it is necessary to re-determine the scheme.

3 Diversified design analysis of HVAC system

3.1 HVAC system diversification strategy formulation There are two main types of strategies for HVAC diversification: design diversification and equipment diversification.
1) design diversification: mainly refers to the different principles of realizing functions, such as designing one set of air conditioning system with active cooling and one set of passive cooling The cooling system, two sets of systems stand by each other, this strategy makes the HVAC system have natural diversification, but this way is difficult to achieve in the current nuclear power project. It should be noted that even if there are big differences in system design, such as using the same type of equipment, it is still necessary to evaluate the degree of diversification of equipment.
2) Equipment diversification: equipment with different manufacturers, different components, different physical principles and different sizes is adopted to realize diversification Chemical design, this strategy does not need to make major changes to the system design, and is relatively easy to implement. It is also common in international nuclear power engineering at present The diversification strategy adopted, this paper will focus on the diversification strategy of equipment.
3.2 Introduction to Equipment Diversification Strategy For HVAC systems with diversified needs, it should be noted that not all equipment in the system needs diversification. If the equipment is reliable enough or its failure will not lead to the loss of system safety function, such equipment may not be diversified. Therefore, it is necessary to accurately identify the equipment components that need to be designed in various ways, and take reasonable and feasible improvement measures to make the benefit-cost ratio of improvement within a reasonable range. See fig. 2 for diversified analysis flow of HVAC equipment, and each step will be introduced in detail later.

3.2.1 Identify the equipment that needs diversification                                                                                                              
 1) possibility.
Ideally, the possibility and probability of failure mode are estimated according to the statistical data of failure mode. According to BS 60812-2018[6], it is very important to consider the boundary conditions (applied environment, machinery and/or stress) of each component that affect the probability of failure. For data statistics of equipment failures, please refer to Equipment Reliability Data Report of China Nuclear Power Plant (2015 Edition) and NUREG/CR-69288, and the failure probability of typical HVAC equipment is shown in Table 3
Generally, equipment that needs diversification can be identified through failure mode, impact and hazard analysis (FMECA). FMECA analyzes all possible failure modes of equipment in the system, determines the influence of each failure mode on the system function, and determines its harmfulness according to the severity of the failure mode and its occurrence probability. FMECA includes failure mode impact analysis (FMEA) and hazard analysis (CA). Engineers can carry out analysis according to BS60812-2018[6], and list every failure of components Hazard analysis is carried out on this mode to find out the key failure modes that need attention. There are two aspects to be considered in evaluating the attention of equipment failure modes:

 Table 3 Failure Probability of Typical HVAC Equipment
equipment failure mode failure probability source
Water chilling unit Startup failure 9.21*10-3/demandNormal operation mode is operation NUREG
Startup failure 2.45*10-5/demandNormal operation mode is standby NUREG
Startup failure 3.06*10-3/demand China nuclear power plant data
Operation failure 6.93*10-5/demandNormal operation mode is operation NUREG
Operation failure 2.20*10-4/demandNormal operation mode is standby NUREG
Operation failure 1.62*10-6/demand China nuclear power plant data
Electric water valve Switching or closing failed 8.22*10-4/demand NUREG
Switching or closing failed 5.03*10-4/demandOpen failure China nuclear power plant data
Switching or closing failed 2.36*10-4/demandClose failure China nuclear power plant data
malfunction 3.24*10-8/h NUREG
malfunction 4.45*10-8/h China nuclear power plant data
water pump Startup failure 7.94*10-4/demand NUREG
Startup failure 2.02*10-4/demand China nuclear power plant data
Operation failure 3.79*10-6/h NUREG
Operation failure 3.48*10-6/h China nuclear power plant data
fan Startup failure 5.43*10-4/demandNormal operation mode is operation NUREG
Startup failure 6.52*10-4/demandNormal operation mode is standby NUREG
Startup failure 1.62*10-4/demand China nuclear power plant data
Operation failure 4.41*10-6/demandNormal operation mode is operation NUREG
Operation failure 3.77*10-4/demandNormal operation mode is standby,Running time is less than 1h NUREG
Operation failure 1.99*10-4/demandNormal operation mode is standby,Running time is less than 1h NUREG
Operation failure 1.86*10-6/h China nuclear power plant data
Electric air valve Failure of opening or closing 2.26*10-4/demand NUREG
misoperation 2.92*10-8/h NUREG
check valve Opening failure 9.24*10-6/demand NUREG
Opening failure 1.76*10-5/demand China nuclear power plant data
safety valve Opening failure 2.42*10-3/demand NUREG
Opening failure 2.47*10-3/demand China nuclear power plant data
Closing failure 8.86*10-4/demand NUREG
Closing failure 6.67*10-5/demand China nuclear power plant data
Note: 1)/demand refers to the failure probability of the equipment when completing a single demand action 2) /hrefers to the failure probability per hour when the equipment maintains a certain state

2)Severity.
Analyze the consequences of this failure mode, that is, the degree of affecting the safety function. If the system safety function is completely lost due to the failure of equipment components, the severity is considered to be high; If the safety function is degraded, the severity is considered as medium; If the safety function is not affected, the severity is considered as low. Through the hazard assessment of each failure mode of HVAC equipment from two aspects of the possibility and severity of failure mode, Table 4 is adopted for screening, and the failure modes with high hazard (underlined in the table) need further diversified improvement analysis.

Table 4 Hazard Assessment Matrix

probability

ponderance

LowSafety functions are not affected

MiddleSafety function degradation

HighLoss of safety function

High

The frequent occurrence of common causes is the leading factor leading to system failure

There is no need for diversification

May not need diversification, need to use engineering judgment for further analysis

Further analysis and improvement are needed

Middle

The frequency of common causes is average, which is not the leading factor of system failure

There is no need for diversification

There is no need for diversification

Further analysis and improvement are needed

Low

There is no relevant common cause fault record, which has almost no effect on system failure

There is no need to diversify, and there is no need to pay too much attention to the usability and maintainability of conventional desig

There is no need for diversification

Usually there is no need for further analysis and improvement, but a detailed explanation is needed

Combined with relevant engineering experience at home and abroad and FMECA analysis of typical HVAC systems, the equipment with high failure probability and harmfulness in HVAC systems and their main failure modes are shown in Table 5.
Table 5 Failure modes of HVAC equipment

                                                              failure mode
water pump Motor drive system failure
Electric water valve Actuator failure, transmission system failure
refrigeration unit Compressor, motor failure, control system failure, refrigerant leakage
fan Faults of motor and transmission system
Electric air valve Actuator failure, transmission system failure
Air handing unit Fan failure

3.2.2 Evaluation of Equipment Diversification Improvement Scheme After finding the HVAC equipment that needs to be considered for diversification improvement, the diversification improvement scheme is determined according to the failure mode with high harmfulness, and the scheme evaluation is carried out to find the scheme that can effectively improve the diversification degree, mainly by means of probabilistic safety analysis and deterministic analysis. 1) probabilistic safety analysis (PSA) PSA is used to determine the importance of components from the overall common cause failure of the system and its influence on core damage or radioactive release. For equipment that needs further analysis, PSA modeling analysis needs to be carried out through the following steps.
①modeling each type of equipment with high harmfulness in different common fault groups.
② Analyze the influence of increasing redundancy to consider whether extra redundancy is needed as a part of coping with common cause faults
③ Sort the equipment failures according to their importance and consider the overall risk level to support the subsequent judgment. After the PSA analysis and modeling is completed, the risk and benefit can be evaluated through Table 6.

Table 6 PSA analysis income classification

Risk and return
High Common fault of system is the main risk and the leading factor of core damage or radioactive release. Equipment diversification can greatly reduce the failure probability of the whole system.
Middle System common cause failure is of medium risk, and equipment diversification has a major contribution to reducing the whole system common cause failure, or system common cause failure is of high risk, so equipment diversification can generally reduce the system failure probability.
Low The risk of system common cause failure is low, or the common cause failure is medium and high risk, but the diversification of equipment has little influence on the failure probability of the system.
3)Deterministic analysis According to the criteria for evaluating diversity in NUREG/CR-7007, the analysis of diversity can be carried out, and the dimensions of analysis can be analyzed See table 7. Taking the wind turbine of safety level as an example, this paper analyzes two schemes of adopting the same equipment design with different suppliers and adopting different designs with the same suppliers, and makes quantitative analysis in the form of Table 8, and determines the final scheme in combination with other factors such as engineering realization. Combining the analysis of probability and certainty theory, we can analyze the diversity of HVAC system and determine the appropriate improvement strategy.

Table 7 Diversification score

score
                  1 2 3 4
Design diversity Same technology The technology is the same, but some components are different There are significant technical differences The technology is completely different
Equipment diversity Same manufacturer, same model Same manufacturer and different models Different manufacturers (or different technologies of the same manufacturer), but the parts/sub-suppliers may be the same Different manufacturers (or different technologies of the same manufacturer), most parts adopt different technologies/the whole supply chain is different
Life cycle diversity Same design team and operation and maintenance team Because the manufacturer is the same, the design team and the operation and maintenance team may be different, but it is not mandatory Due to differences in manufacturers, design teams are likely to be different, and maintenance may be similar or different Due to different manufacturers and technologies, the design and maintenance teams are likely to be different

Table 8 Evaluation of Fan Diversification Scheme

Improvement scheme 1: diversification of suppliers Improvement scheme 2: technology diversification
describe score describe score
 
Evaluation criteria of diversification degree
Diversified design Direct fans are used, but the motor voltages can be different. According to FMEA Analysis shows that motor failure is the main failure reason, even if different types are adopted The fan can not solve this problem either 2 Different types of fans are used, such as direct fan and belt driven fan 3
Equipment diversification Due to different suppliers, it is diversified. However, key sub-components may come from the same secondary supplier and need to be avoided by proper management 3 Because of different principles, different parts may be used, but some parts may be completely 3
Life cycle diversification Because of different suppliers, the design is completed by different teams. However, maintenance and debugging may be carried out by the same team 3 Because of different principles, the procedures of design, maintenance and debugging may be different by different teams 4
Comprehensive score     2.85   3.4
PSA analyse   Common cause failure of fan is the leading factor of common cause failure of HVAC system  
Engineering experience consideration   The failure rate of belt conveyor fan is higher, and its reliability is worse than that of direct fan  
assessment result   The scores of fans with different suppliers and different principles are close, and motors with different voltages can be used in both schemes. In addition, due to the difference of operating conditions, the probability of partial common cause can be reduced, so both schemes can reduce the common cause of fans to a reasonable and feasible level. Scheme selection should be combined with engineering realization, cost and other factors
3.3 Determination of diversification improvement scheme
After determining the diversified improvement strategy of HVAC system, it is necessary to combine the diversified improvement analysis of the supporting systems of HVAC system to determine diversified potential improvement schemes, and compare and select the potential schemes from the aspects of nuclear safety impact, technology maturity, feasibility, cost, etc., and finally determine a reasonable and feasible scheme, and reduce the risk of common-cause failure of HVAC system to an acceptable level. The methodology of scheme comparison is mature, so this paper will not discuss it again.
4 Conclusion
This paper discusses the types of common-cause faults in nuclear power plants, and summarizes the methods, processes and countermeasures applicable to common-cause fault analysis of HVAC systems in nuclear power plants, which provides reference for domestic nuclear power plants to carry out common-cause fault analysis of HVAC systems. Common cause fault analysis of HVAC system in nuclear power plant involves many fields such as nuclear power plant safety analysis, equipment FMECA analysis, PSA analysis, disaster analysis, etc. It is necessary to comprehensively analyze to identify all common cause risk points, and formulate reasonable and feasible countermeasures to minimize risks and improve the safety level of nuclear power plant.

References:
[1]national nuclear safety administration, design safety regulations for nuclear power plants: HAF102-2016[S]. Beijing: national nuclear safety administration, 2016:24[2] International Atomic Energy Agency. Safety of nuclear power plants: design specific safety requirements: IAEA ssr-2/1-212s. Vienna:IAEA2012:26-28

[2] International Atomic Energy Agency. Design of auxiliary systems and supporting systems for nuclear power plants: IAEA SSG-62-2020 [S]. Vienna:IAEA,2020;24-30
[3] ONR. Redundancy, diversity, segregation and layoutof mechanical plant: ONR-NS-TAST-GD-036 [S].London: ONR, 2017: 2-14
[4] U. S. Nuclear Regulatory Commission. Diversity strategies for nuclear power plant instrumentation and control systems: NUREG/CR-7007 [S]. Oak Ridge:NRC,2008:121-225
[5] BSI. Failure modes and effects analysis (FMEA and FMECA): BS 60812-2018[S]. London: BSI, 2018:19-75
[6] Data Report on Equipment Reliability of China Nuclear Power Plant of National Nuclear Safety Administration [M]. Beijing: National Nuclear Safety Administration, 2015:8-13
[7] U.S Nuclear Regulatory Commission. Industry-average performance for components and initiating events at U.commercial nuclear power plants: NUREG/cr-6928[S]. Oak Ridge: NRC, 2015: 99-108

Source: Journal of HV&AC Heating Ventilating & Air Conditioning
Related sex shock toy porn
Read More >>
팬 코일 유닛의 유형과 일반적인 결함은 무엇입니까? 팬 코일 유닛의 유형과 일반적인 결함은 무엇입니까?
Nov .09.2021
팬 코일 유닛의 유형과 일반적인 결함은 무엇입니까
ما هي أنواع وعيوب مشتركة من وحدات لفائف مروحة؟ ما هي أنواع وعيوب مشتركة من وحدات لفائف مروحة؟
Nov .06.2021
ما هي أنواع وعيوب مشتركة من وحدات لفائف مروحة؟
¿Cuáles son los tipos y fallas comunes de las unidades de fan coil? ¿Cuáles son los tipos y fallas comunes de las unidades de fan coil?
Nov .04.2021
¿Cuáles son los tipos y fallas comunes de las unidades de fan coil
Fan bobin ünitelerinin tipleri ve yaygın hataları nelerdir? Fan bobin ünitelerinin tipleri ve yaygın hataları nelerdir?
Nov .02.2021
Fan bobin ünitelerinin tipleri ve yaygın hataları nelerdir
webmaps