Safety response time, scenario

As an alternate or addition to scenario assessments, simulated exercises or dry-runs could be developed to test the effectiveness of the new organization. This could be similar to table-top exercises commonly run by companies to test the effectiveness of the emergency response plans as well as the use of process simulators to test response of operations personnel to process upsets. The assessment should verify that individuals can complete their critical safety responsibilities in a reasonable amount of time. 

Consequently, small reactor designs having features that allow operation with reduced crew size are favoured. Such operation requires a greater level of safety autonomy, that is, the reactor would have to achieve a safe, stable end state by passive means for all realistic upset scenarios without operator assistance and it would have to provide a sufficient response time for any eventual intervention using off-site resources. 

Table B.1 provides an example of criteria that can be established for operator action as an IPL. According to this example, the risk reduction allocation is related to the protection layer allocation, human response time and the complexity of the action. The human response time should be less than the available prooess safety time, when an operator response to an alarm is being considered for reducing the risk of a specified hazard scenario. The available process safety time is the time it takes the process to go from the alarm condition to the hazardous condition. Human error occurs when an operator fails to respond oorreotly within the available process safety time.

Toxic operations must be supported by a good communications system. In laboratories where communications are inadequate, workers will naturally use "runners" for communication needs. This practice results in avoidable traffic in and out of toxic areas which increases the opportunities for contamination to spread. In emergencies, a phone or intercom can help ensure that assistance is tailored to the actual need. An "all purpose" response to an alarm will normally be less rapid at a time when speed may be of the essence. Video cameras trained on critical operations add a measure of safety, but annoy the workers who may feel that the purpose of the system is to "spy" on them. As a minimum, the laboratory doors should have windows so that entering personnel don t blunder into a rapidly developing scenario. 

Detailed investigation of accident scenarios modeled in Czech PSA projects has led to the conclusion that, at least for major subset of aU actions performed in response to initiating event occurrence and driven by symptom based procedures, lack of time should not be relevant issue. Thus, the time-versus-reliabiUty curves (for short time windows) are used just in some few very special cases of potential lack of time (with time windows shorter than 30 minutes), mostly connected with necessity to recover plant critical safety functions. 

Six months into the two-year project, one of the major subcontractors responsible for multistory steel-beam erection had employees working over 30 feet in the air without fall protection. After the second observation of this violation, the plant safety manager ordered the workers down, informed the contractor of the repeat violation, and initiated the process to terminate the contract. The contractor was removed from the project and replaced by a firm that accomplished all the goals initially established by the textile manufacturer. The plant manager in this scenario did not compromise. As a result, the project was completed on time with only one OSHA-recordable injury. 

Thank you for your interest in occupational safety and health. We hope you find this information helpfui. Piease be aware that the enforcement guidance contained in this response represents the views of OSHA at the time the letter was written based on the facts of an individual case, question, or scenario and is subject to periodic review and clarification, amplification, or correction. It could also be affected by subsequent rulemaking past interpretations may no longer be applicable. In the future, should you wish to verify that the guidance provided herein remains current, you may consult OSHA s website at http // www.osha.gov. If you have any further questions, please feel free to contact the [Office of General Industry Enforcement] at (202) 693-1850. 

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