Failure potential

Contraindications to the use of 3 blockers are asthma and other bronchospastic conditions, severe bradycardia, atrioventricular blockade, bradycardia-tachycardia syndrome, and severe unstable left ventricular failure. Potential complications include fatigue, impaired exercise tolerance, insomnia, unpleasant dreams, worsening of claudication, and erectile dysfunction. 

Rituximab An++, C+, D++, M+, P+, R++ Severe, fatal hypersensitivity reaction possible. Tumor lysis syndrome has caused acute renal failure. Potentially fatal mucocutaneous reactions reported,... 

Bolsin S, Jones S, Acute renal failure potentiated by gentamicin and calcium. Anaesth Intensive Care (1997) 25, 431-2. 

Identify the causes for each failure mode. A failure cause is defined as a design weakness that may result in a failure. Potential causes for each failure mode should be identified and recorded... 

Schuck PF, et al. Acute renal failure potentiates meth-ylmalonate-induced oxidative stress in brain and kidney of rats. Free Radic Res. 2013 47(3) 233-40. 

Decision trees (DT) represent progressive method of human reliability analysis, developed worldwide in a number of (plant specific) variants in early and middle nineties (Beare et al., 1991). The method typically splits the human failure potential among a set of well specified individual contributors, taking into account also interactions among them to some extent. Simulator data collection was used in several projects to provide elementary HEPs for individual decision tree branches, as in Paks WWER plant studies (Bareith Karsa, 1998). The method has been found particularly useful for analysis of crew actions performed in response to IE occurrence, which are well covered with... 

From Czech HRAs perspective, widely known and used second generation HRA method (Hollnagel, 1998), particularly devoted to failures of (highly) cognitive control room crew actions, i.e. such a field, which is not well covered with somewhat static schemes of other well known HRA methods. In fact, the method strucmre is similar to HEART to some extent, where the failure potential is specified by definition of activity type and by evaluation of a set of factors positively or negatively influencing the potential for action success. The spectrum of influencing factors seems to be more complete and mutually consistent than in HEART case. 

The analysis frameworks as well as methods of human failure potential quantification listed in the previous section, which are commonly applied in HRA nowadays, follow a set of both general and method-specific rules necessary for reaching sufficient level of quahty of analysis. In addition, there are references playing an informal role of HRA standards quite well, which, if followed, can further increase credibility of analysis results. Using (NUREG-1792, 2005), for example, HRA under development can be confronted with very systematic and reasonable up-to-date rules of rather general nature, which are furthermore exploited in (NUREG-1842,2006) to take into consideration some specifics of individual HRA methods. The references (ASME RA-S-2002, 2002), (IAEA... 

This point is connected with previous one. To avoid overconfidence and optimism, final evaluation of human failure potential and measuring it by probability should be done by the expert, who is 1) independent 2) is equipped with probability sense 3) is provided with all possible information about the matter. 

The way, plant crew follow procedures, may be often seen as decisive for determination of human related risk contribution The reason is that cognitive features of crew activities contribute very significantly to the total crew failure potential and the extent and scope, these features take a share in crew actions, are very directly influenced with the typical ways of procedures using (if the crew is strongly obligated to use procedures step by step, the level of necessary cognition is highly suppressed and vice versa). 

For years, simulator data collection has been seen and proposed as rich and good additional data source helping in HRA quantitative part. Although simulator exercises observation can help significantly in qualitative analysis of some factors influenciDg failure potential (team work), the idea of grounding HEP quantification just on simulator data is fairly naive, because the statistics is clearly insufficient to produce direct estimates and because of common simulator fidelity problems. 

Rule 13 Human factor importance must no be mistakenly mismatched with human factor quality. This very important point is valid both for concrete individual factors influencing human failure potential and for total importance of human factor in plant risk profile. Frequently, there is tendency to interchange importance and quality - both on local level leading to wrong assumptions and inputs into the analysis and on plant PSA level leading to significant misinterpretation of analysis results. 

Rule 14a Human error probability n/10 does represent quite reasonable estimation of failure potential for typical safety important action driven by procedures, including both some information processing and manipulations. 

As it is discussed in (Mosleh et al., 1998), residual CCF represents relatively high failure potential caused by common manufacturer, design, environment, operational conditions, procedures, maintenance etc. As a consequence, although identical , the redundant, added trains do not have the same conditional failure probability p when used as one more backup of so far operated main frontline system train, which already failed with p probability rather the overall failure probability of the backup is typically of 10 ... 

The problematic, common aspect of using both classic redundancy and diversity is the difficulty of expression of failure potential of such systems. For common redundancy achieved by identical trains, a number of studies has been done, including (Mosleh ef a/., 1998), providing some quite general quantitative values of CCF probability parameters. For diversified systems, CCF potential is realistically estimated as much lower than for classic redundancy and sometimes, optimistically as close to a system with absolutely independent branches . 

NEW APPROACHES TO EVALUATION OF DIVERSITY IMPACT ON SYSTEM FAILURE POTENTIAL... 

When hardware failure is a root cause for software error (1. b), we could keep this event within the boundary of hardware component failure when we loose just recovery action (made by software). The problem is that those types of hardware failures are so called soft errors , i.e. stochastically occurring events automatically repaired and it is questionable, whether they were reported when data for reliabihty parameters were gathered. Nevertheless, the uncertainty of e.g. processors failure rates is typically so high that treatment of hardware-software interface failures as just hardware errors seems to be justifiable. Moreover this kind of failures is basically not suspected fi om CCF (Common Cause Failures) potential. 

Risk Mathematically, expected loss the probability of an accident multiplied by the quantified consequence of the accident (SSDC) an expression of the possibility of a mishap in terms of hazard severity and hazard probability (MIL-STD-882) note Hazard exposure is sometimes included (AFR 800-16) as defined in NHB 5300.4(10-2), The chance (qualitative) of loss of personnel capability, loss of system, or damage to or loss of equipment or property (NSTS 22254) a measure of both the probability and the consequence of all hazards of an activity or condition. A subjective evaluation of relative failure potential. In insurance, a person or thing insured (ASSE). 

Chapter 11 of this text discusses the use of fault tree analysis in determining system reliability, failure potential, and even accident cause factors through examination of specific or general fault paths. Additional information on the application and use of probability values in fault tree analysis is also provided in Chapter 11. 

In the decision-making process, however, a major difference exists in this system that is of particular interest to safety professionals. In the semiconductor industry s FMEA form, Cr appears at the top of a column. This is a Critical Failure Symbol. A Y is to be entered for yes if the failure potential is considered safety-critical. 

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