Preliminary hazard review

First, the importance of learning lessons from past process safety incidents is highlighted in Section 3.2. The subsequent section presents preliminary hazard review procedure, risk matrix, what-if method, plot plan and layout review, pressure relief system review and fire safety design aspects. Section 3.4 presents PHA techniques and procedures hazards and operability analysis (HAZOP), failure modes and effects analysis (FMEA), instrumented protective system (IPS) design, fault trees, event trees, layer of protection analysis (LOPA) and finally SIS life eyele. The importanee of revision of PSI is highlighted in Seetion 3.5. 

Preliminary Hazard Review during Conceptual Design... 

Preliminary hazard review is intended to evaluate major hazards at the early stages of technology development and/or proposal development and project planning. Inherently safer design, high risk process elimination, appropriate safeguards and the need for further studies are identified at this stage. This would help the project team to understand major on- and off-site risks and the kind of domino effects from events, which may impact the environment and corporate reputation. 

The outcome of the preliminary hazard review is also useful to document into formal permits or notification to the authorities. 

Conduct preliminary hazard review and code analysis ergonomics, safety, electrical, clearance zones, materials of construction, etc. 

FIGURE 7-1. Preliminary Hazard Review Decision Diagram. (Adapted from Guidelines for Hazard Evaluation Procedures, AlChE, 1985, p. 1-9.)... 

The high-high probe is completely independent of the other probes and is hardwired to shut down the system completely, independent of the computer. (In the preliminary safety review, the hazards associated with HF overfeed were identified as important thus the independent high-high shutdown probe system was installed.) All systems are designed to fail into safe conditions. The HF control valves are air operated and of a design that makes it impossible for HF to contaminate the air supply. 

Assessment. An analysis of the hazards present in this laboratory show the most significant hazard to be the release of vapor CSM from engineering controls and into the workplace. The significance of this hazard mandates further efforts in system safety in the form of a Preliminary Hazard List (PHL) and a Preliminary Hazard Analysis (PHA). The user must in this instance take an active role in the design review process. 

Other possible preliminary safety analysis methods are concept safety review (CSR), critical examination of system safety (CE), concept hazard analysis (CHA), preliminary consequence analysis (PCA) and preliminary hazard analysis (PHA) (Wells et al., 1993). These methods are meant to be carried out from the time of the concept safety review until such time as reasonably firm process flow diagrams or early P I diagrams are available. 

Several qualitative approaches can be used to identify hazardous reaction scenarios, including process hazard analysis, checklists, chemical interaction matrices, and an experience-based review. CCPS (1995a p. 176) describes nine hazard evaluation procedures that can be used to identify hazardous reaction scenarios-checklists, Dow fire and explosion indices, preliminary hazard analysis, what-if analysis, failure modes and effects analysis (FMEA), HAZOP study, fault tree analysis, human error analysis, and quantitative risk analysis. 

A PHA was prepared as part of the Parsons/Honeywell EDP, in accordance with MIL-STD-882C. The PHA is based on a preliminary hazards list that describes unmitigated hazards the list will be updated as the design process progresses (DOD, 1993). Numerous PHA work sheets were generated, and recommendations were made to reduce risk. The PHA results were reviewed by a multidisciplinary group from the Parsons/Honeywell team, which will track the means of mitigating hazards. 

Level 1 System Purpose Assumptions Constraints Responsibilities Requirements l/F requirements System goals, high-level requirements, design constraints, limitations Preliminary Hazard Analysis, Review s... 

At this stage in the MOC process, it is useful for the Coordinator to conduct a high-level hazards review, and to develop a preliminary risk ranking for the proposed change. 

Furthermore, when simpler techniques (i.e., what-if analyses, checklist analyses) reveal hazardous situations needing additional review, the substance of the preliminary hazard analysis technique may be used. In reality, the technique needs a new name because it has achieved broader use than the original intent, which was as a preliminary assessment system to be used in early concept and design stages for a product or system. 

Many hazard analysis and risk assessment techniques have been developed. These are just a few of the methodologies mentioned in the literature preliminary hazard analysis gross hazard analysis hazard criticality ranking catastrophe analysis change analysis energy flow/barrier analysis energy transfer analysis event tree analysis human factors review the hazard totem pole and double failure analysis. There are many other hazard analysis systems. 

Potential external events were identified by reviewing previous Safety Analysis Reports of similar DOE facilities (Restrepo 1995) and the recommended list of external events used to evaluate commercial nuclear power plant risks (NRC 1983). In addition, an attempt was made to identify any other potential external-initiating event unique to the site that had not been considered in previous studies. It is important to note that operational accidents (e.g., criticality, internal fires) occurring inside the HCF and assodated radioactive material storage facilities are not considered in this screening process. These types of "internal initiating events are identified separately using preliminary hazard checklists (see Appendix 3A). 

A typical system safety task for hazard identification would be the preparation of a preliminary hazard list (PHL). Hazard identification or discovery is accomplished by reviewing lessons learned, accident reports, and other historical data. A PHL may be prepared through an informal conference, the use of checklists, and occasionally other techniques such as energy trace and barrier analysis (ETBA). 

The purpose of the project evaluation tree is to provide a relatively simple, straightforward, and efficient method of performing an in-depth evaluation or analysis of a project or operation. It is best suited for performing operating hazard analysis and accident analysis. It can also be a valuable review and inspection tool. If adequate information is available, PET analysis may be helpful in performing preliminary hazard analysis, subsystem hazard analysis, and system hazard analysis. 

The Basis for Interim Operation (BIO) document for K>Reactor in Cold Standby and the L- and P-Reactor Disassembly Barins was pr ared in accordance vrith the draft DOB standard for BIO preparatiott (dated October 16, 1993). The actives for tte BIO preparation process included hamd iden carion, hazard categorization, and a preliminary hazards analysis. These actmties, along with the review of the K-Reactor Safety Anafysis R rt (SAR), K-, and P>Reactor Technical Spedfications (TS), K-Reactor Cold Standby Plan, L-Reactor ( Id Shutdown Plan, P-Reactor Standby Plait, and other safety documents, were used to compile the BIO. 

The operations of the K-Reactor Purification Area and the K-, L-, and P-Reactor Disassembly Basins have been examined in this BIO to ensure the adequacy of tiie safety envelope, and to develop and promulgate any new requirements ensuing from the Preliminary Hazards Analyses and the Hazards Assessment Documents. The existing K-, L-, and P-Reactor Technical Spedfications were also reviewed. The review revealed the need for new admimstrative controls to preserve the safi ty anatytis assumptions. 

Stages Safety Review Checklist Relative Ranking Preliminary Hazard Analysis What-if Checklist HAZOP FMEA Cause- Consequence Analysis Human Reliability Analysis Fault Tree Event Tree... 

D. Initial Capital Expenditure Safety Review Capital expenditure requests at financial levels requiring divisional or corporate approval must be accompanied by a Preliminary Safety Review, completed by the Safety Review Team and including as many of the subjects applicable as outlined in Table 1. Comments would be included giving assurance that the hazards and risks identified can be properly addressed. 

Determine that hazards identified in the preliminary safety review and the subsequent design review have been properly addressed... 

Due to the need to check all safety measures, this part of the system analysis can become very voluminous. The method becomes difficult due to the constant change from the overall review of the plant to the review of individual components. For this reason it is important, in the case of major systems, to place preliminary hazard analysis and system structure analysis ahead of the evaluation of the planning concept. The advantages of this work plan are the following ... 

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