Operator Actions

For each alarm, a specific action is expec ted from the process operator. Operator actions such as call maintenance are inappropriate with modern systems. If maintenance needs to know, modern systems can inform maintenance directly. 

Provide batch sequencing interlocks that demand operator action... 

Mitigai Design provisions, safety or relief devices, or operational actions that can m te the 2cts of failure should be listed. 

List of the possible misdiagnoses and subsequent operator actions under consideration which could give rise to system interactions from operator diagnostic errors,... 

Operator action tree used to develop the errors, and the. specific time reliability curves u.sed and how they were developed,... 

The Operator Action Tree (OAT) is a time reliability correlation method (NUREG/ CR-3010). specifically designed to estimate HEPs for actions requiring decision making on the part of the plant operator. It employs two steps (1) the development of an operator action tree which reflects the specific actions that may be taken by an operator faced with a particular decision, and (2) a time... 

Techniques for quantifying Techniques used were basically from NUREG/CR-1278 or PRA Procedun s Guide, Chapter 4. (l)THERP (1980 version NUREG/CR-1278 with appropriate factors for a tree was used in procedure defined events. (2) A time dependent modeling approach was used to quantify operator actions during a sequence. THERPmethixlr. were ii ,cd as described in WASH- Id ... 

The passive containment cooling system can remove residual heat from the containment for three days without operator action. 

Excess reactivity Failure of automatic rod control Heat imbalance lemper- ature increase Control rod drive Operator action, interlocks HIE... 

Plant design features and response strategies, including operator actions as. spccilied by SRS procedures, are incorporated... 

Operator error probability under stressful conditions depends upon the time to complete a sequence of events. The total time available for limiting sequences was 7.9 hours which is the time to completely drain the cooling water basin. Sequence (6) required the most operator actions (11) was... 

Beare. H. N. et al., Criteria for Safety-Related NPP Operator Actions iniii.i BWR Simulator Exercises, November 1982. 

Hall, R. E. et al., Post-Event Human Decision Errors Operator Action Tree/Time Reliability Correlation, BNL, November 1982. 

Wreathall, J., 1982, Operator Action Trees, An Approach to Quantifying Operator Error Probability during Accident Sequences, NUS Report 4655, July. 

Using binary notation for the coordinates of a given particle, and the definition of the -operator action on single bits 0 0 = 0, O l = 0, 1 0 = 0, 1 1 = 1, we demonstrate below that by masking off some sets of bits (i.e.. 

Operator action event trees are treelike diagrams that represent the sequence of various decisions and actions that the operating team is expected to perform when confronted with a particular process event. Any omissions of such... 

The OAET is a logical method of structuring information concerning operator actions resulting from a particular initiating event. 

Are the documentary procedures routinely checked, compared with operator action and revised as appropriate ... 

FIGURE 5.11. Operator Action Tree for ESD Failure Scenario (Kirwan, 1990). 

The establislunent of emergency response procedures, both on plant sites and off (facility owner and operator actions, as well as the actions of local emergency and medical persomicl)... 

Wirkungs-weise, /. mode of acting, mode of Operation, action, -wert, m. effective value (of an acid, etc.) strength efficacy. 

Positive displacement pumps are self-priming by their normal operating action and are designed to cope with mnning dry. Centrifugal pumps are not inherently selfpriming, and need to be provided with assistance in the form of ejectors, as in Figure 32.56 or dry vacuum pump systems. In these systems, a dry vacuum pump allows air to be drawn out and where an automatic valve prevents... 

The solution to stratification problems is to avoid mixing fuel grades, keep tank temperatures lower rather than higher, provide mechanical agitation where practical, and supplement operational actions with the use of a polymeric antisettling dispersant. 

An automatic control system is a preset closed-loop control system that requires no operator action. This assumes the process remains in the normal range for the control system. An automatic control system has two process variables associated with it a controlled variable and a manipulated variable. 

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