Safety during plant operation

Ymer s platform management faces a number of SHE challenges, especially dnring the first period after start-np. The organisation is new and unfamiliar with the platform and the management system. Construction work on the platform has not been fully completed at start-up and continues in parallel with production and drilling. It is of major importance to avoid construction work on systems that have not been de-energised. Here, the permit-to-work system plays an important role. 

After the construction team has been demobilised, the platform goes into a period of routine operation. It is here important to maintain a high alertness to SHE challenges and to avoid complacency, although the risk is not as high as during the early phase after start-up. 

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Thermal power plant components operated at high temperatures (>500°C) and pressures, such as superheater headers, steamline sections and Y-junctions, deserve great attention for both operation safety and plant availability concerns. In particular, during plant operation transients -startups, shutdowns or load transients - the above components may undergo high rates of temperature / pressure variations and, consequently, non-negligible time-dependent stresses which, in turn, may locally destabilize existing cracks and cause the release of acoustic emission. 

A sidelight on the incident is that the operator had worked on the plant for only seven months and during that time had received five warnings for lack of attention to safety or plant operations. Howev-... 

Can safety equipment fail because of obstruction, freezing, wear or corrosion Can the availability of safety equipment be tested during plant operation ... 

The design of hydraulic engineered safety features for LWRs has traditionally been performed according to high reliability and leak proof standards. These systems are usually called into operation to protect the fuel barrier in the case of a loss of the primary system barrier. In addition, being strictly connected to the primary circuit pressure boundary, they have to be equipped with leak proof isolation devices, normally closed during plant operation. 

A computer system used in systems important to safety should be designed so that it is periodically testable during plant operation in order to verify the continued operability and lehability of the system. This may require adjustments to the computer system s architecture. 

The source or sources for each issue is provided in Section 3, that is, whether operational experience, a deviation from current standards and practices or analysis gave rise to the concern. Over half the issues had operational experience as one of their sources. This is to be expected after over 30 years of worldwide nuclear power generation. The source areas of deviation from current standards and practices and analysis each were noted in about one third of the issues. The use of analysis, particularly PSA, to identify potential issues of concern which have not been observed during plant operation is considered a sign of health with respect to industry and regulatory body concern for safety. Several of the "deviation" issues refer to W R reactors which have recently been systematically measured against international practice. 

Each main steam line goes from its steam generator and passes through the containment boundary. The first valve encountered in each line is the main steam isolation valve, which is outside the containment boundary each isolation valve has a bypass valve in parallel with it. Beyond the main steam isolation valve in each of the two steam lines are the six steam safety valves every one of these safety valves vents to atmosphere through a discharge pipe and vent stack. Downstream of the safety valves is the power-operated atmospheric relief valve, which vents to atmosphere through a vent pipe and silencer. The operation of the power-operated relief valves is automatically controlled by steam line pressure during plant operations the power-operated relief... 

Performance of any of the three types of approaches, and in particular PSA for Shutdown and Low Power Operating Mode, may support the enhancement of the safety during plant outage, and may contribute to reduction of the outage duration. Thus, a detailed analysis of shutdown operation may contribute to a more economical plant operation, improve plant safety and lower the consequences of incidents. 

In those systems to which the single failure criterion applies, if a channel is bypassed during plant operation for the purposes of maintenance, testing, repair or calibration, the remaining operable channels of the system should continue to meet the single failure criterion unless otherwise justified as discussed in paras 4.15-4.21 of this Safety Guide. 

A process industry, a refinery, a petrochemical, a fertilizer plant or a povser station are installations that can be classilled as critical. They cannot afford a breakdown during normal operation and would prefer to incorporate more safety features into the drive motors, even if these are expensive. These features can be one or more of the following. 

During regular operations to identify potential improvements for the next plant. Process improvement studies can then demonstrate the feasibility of inherent safety improvements so they can easily be incorporated into the design of the next plant or in major revamps of existing facilities. 

It is worth pointing out, however, that personality traits which do not provide people with adequate resources to maintain performance under stress, may compensate by supporting other activities during normal operations. For instance, "externals" may be more cautious than "internals" and take no chances to risk plant safety, while type A personalities may have a greater motivation to progress in their jobs and perfect their skills than type B personalities. Depending on the type of task, some personality traits will produce better performance than others. More research would be needed to develop a better understanding of the relationships between types of task and preferable personality styles. 

The minimum depth of a pond is directly proportionate to the rate of evaporation. This depth needs to allow for increases in volume, the precipitation of salts, as well as for rainfall and waves. It is estimated that the best evaporation rate can be achieved with pond depths of 0.03-0.45 m, however ponds with depths of up to 1.02 m have been shown to have reasonable evaporation rates (Mickley 2006). Similarly to pond area, a safety factor can be applied to the calculated minimum pond depth to increase the capacity and prevent the pond from overflowing. This extra depth will depend upon the expected additional discharge volume at the beginning of plant operation (Mickley 2006), and the ambient conditions during winter, at which time the pond may store water rather than reduce its volume (Ahmed et al. 2000). 

General Safety Precautions. The preparation and handling of the items covered by this specification, and the subassemblies thereof, involve hazardous operations and therefore require explosives safety precautions. Use of this specification will not be construed as to relieve the contractor or manufacturer of responsibility for the safety of his operations. Listed below are certain minimum provisions which a contractor or manufacturer (who prepares the item covered) should observe in order to fulfill his responsibility for safety. At Bureau of Naval Weapons, Navy Department, and other government plants, these provisions are mandatory. Such other warnings and precautions, pertinent to the operational effectiveness or safety during preparation of the specified items, are included in detailed technical requirements of the specification... 

AP600 Passive Safety System Details, These features reduce operator responsibilities and add an extra margin of safety over contemporary PWR designs. See Fig. 37 on p. 1121. Large volumes of water stored in the containment eliminate the need for operator action to assure make-up water, either for small leaks that may occur during normal operation or for a major loss of coolant accident (LOCA). A passive plant is a system llial assures public safety even if the operators fail to act... 

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