System Analyses

It is unclear whether previously published fire risk analyses have adequately ircaicd dependent failures and systems interaetions. Examples of either experienced or postulated system interactions that have been missed include unrelated systems that share common locations and the attendant spatially related physical interactions arising from fire. Incomplete enumeration of causes of failure and cavalier assumptions of independence can lead to underestimation of accident l rci uencies by many orders of magnitude, 

The responsibility for accurate and timely test reports generally lies with the laboratory, but many problems can arise before and after the analysis of the submitted specimens. To monitor and control these errors, it is essential to perform a systems analysis of the laboratory and to identify the types of preanalytical variables. 

The operation of the clinical laboratory can be viewed as a series of processes, each of which has potential sources of error. Table 19-1 shows the processes that take place from the time of the physician s initial request for a test to the time of the final interpretation of the test result. This systems analysis identifies the critical processes for a typical laboratory however, each laboratory situation is somewhat different, and there may be additional processes and additional sources of error. It is important for each laboratory to perform a 

TABLE 19-1 Laboratory Testing Processes and Their Potential Errors 

Handwriting not legible Wrong patient identification Special requirements not specified Cost or delayed order Incorrect tube or container Incorrect patient identification Inadequate volume Invalid specimen (e.g. hemolyzed or too dilute) 

Collected at wrong time Improper transport conditions Instrument not calibrated correctly 

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Hiller, D., and Ermert, H., System Analysis of Ultrasound Reflection Mode Computerized Tomography, IEEE Trans. Sonic Ultrasonic SU-31, pp 240-250, (1984). 

G.H. Peters, D.M.F van Aalten, O. Edholm, S. Toxvaerd, and R. Bywater. Dynamics of proteins in different solvent systems Analysis of essential motion in lipases. Biophys. J., 71 2245-2255, 1996. 

Table 8 summarizes the Chem Systems analysis of the cost of production of BTX from these feeds, resulting ia a recommendation of the best-suited technology for each feedstock. 

FIG. 17-66 Electrostatic-precipitator-system model. (Nichols and Ogleshy, Electrostatic Precipitator Systems Analysis, AIChE annual meeting, 1970.)... 

Even when a total system analysis is unnecessai y, the methodology of mathematical modeling is useful, because by considering each component of a system as a block of a flow sheet, the interrelationships become much clearer. Additional alternatives often become apparent, as does the need for more equipment-performance data. 

System Analysis The choice of a specific handling system must take into consideration trade-offs that can be made among different... 

Reactant system Analysis, volume %" Pyrolysis Air -1- steam Steam (cychc-air) Steam -1- oil (cychc-air) Oxygen plus steam at pressure... 

Costs based on plant processing 26,105 Mg/d (28,776 US ton/d) of Ilbnois No. 6 coal. Source Direct Coal Liquefaction Baseline Design and Systems Analysis, prepared by Bechtel and Amoco under DOE contract no. DE-AC22-90PC89857, March 1993. 

In addition to performing the system analysis, a number of details or pecuharities of the units must be considered with respec t to ... 

Theory of overvoltages Analysis of ungrounded and grounded systems The necessity of grounding an electrical system Analysis of a grounded system ... 

Thermal system analysis is aetually a variation of Ohm s Taw. There are equivalent eireuit elements whieh map direetly to the elements within the eleetrieal domain (refer to Table A-1). 

This section discusses the principal causes of overpressure in refinery equipment and describes design procedures for minimizing the effects of these causes. Overpressure is the result of an unbalance or disruption of the normal flows of material and energy that cause material or energy, or both, to build up in some part of the system. Analysis of the causes and magnitudes of overpressure is, therefore a special and complex study of material and energy balances in a process system. 

Qieck Valve - A check valve is acceptable in a process pressure reheving path, provided that (1) the valve opens in the pressure reheving direction, (2) the valve is of the swing-check or wafer type with no external actuation or dampen mechanism, and (3) the pressure drop is included in the system analysis. 

This section describes the most commonly used method for complex systems analysis - fault tree analysis. The previous section introduced cutsets as physically cutting through an RED, here, cuiscis. ire presented mathematically. The symbols of fault trees are introduced and a heuristic... 

Function event trees include primarily the engineered safety features of the plant, but other systems provide necessary support functions. For example, electric power system failure amid reduce the effectiveness of the RCS heat-removal function after a transient or small UJ( A. Therefore, EP should be included among the systems that perform this safety function. Siipfiort systems such as component-cooling water and electric power do not perform safety functions directly. However, they significantly contribute to the unavailability of a system or group of systems that perform safety functions. It is necessary, therefore, to identify support systems for each frontline ssstcm and include them in the system analysis. 

System Analysis Code Usage in Past PSAs... 

S, RA System Analysis and Eisk Asves.snienl. system displays and manipulates cutsets generated by IRR.AS. 

RISKMAN is an integrated Microsoft Windows , personal computer software system for [H. i forming quantitative risk analysis. Used for PSAs for aerospace, nuclear power, and chemical [iroccsses, it has five main modules Data Analysis, Systems Analysis, External Events Analysis, Event Tree Analysis, and Important Sequences. There are also modules for software system maintenance, backup, restoration, software updates, printer font, and page control. PEG has also integrated the fault tree programs CAFTA, SETS, NRCCUT, and IRRAS into RISKMAN. 

Review of procedures and information froiii system analysis... 

SAINT Systems Analysis of Integrated Networks of Tasks Swain, 1989... 

Human reliability [lata NJUREG/CR-1278 was supplemented by judgment of system analysts and plant personnel. Human error probabilities were developed from NUREG/CR-12 8, human action time windows from system analysis and some recovery limes from analysis of plant specific experience. Data sources were WASH-1400 HEPs,Fullwood and Gilbert assessment ot I S power reactor Bxp., NUREG/ CR -127K. and selected acro ptice li.it.j... 

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