Equipment configuration issues

Safety issues in batch reaction systems relating to equipment configuration and layout are presented in Table 3. This table is meant to be illustrative but not comprehensive. A few key issues are presented below. 

The results obtained from analytical equipment measuring the composition of a reactor output are normally reported in mol fractions. In most cases the mol fractions of components at the outlet are automatically re-normalized so that their sum is one. This is correct as far as mol fractions are concerned, but the atomic balances of the output may well be off due to both analytical error and the process of re-normalization applied to the measured mole fractions. This is an issue that needs to be addressed in each instance, regardless of reactor configuration or the mode of reactor operation. At the same time this is a particularly well conditioned problem to address in the case of the voluminous data from a TSR experiment. 

DQ checks that the design documentation matches the requirements stated in the EDS. Layout drawings, operating and maintenance procedures, parts lists and system descriptions are included in the DQ. Both hardware and software configuration are reviewed together with the supplier s product documentation. DQ offers the opportunity to monitor the progress of project validation as well as any operational and safety issues, such as the use of radioactive instruments or access to analysis equipment for maintenance. 

All these factors lead to the central issue of selecting the type and configuration of the reactor (the central issue in Fig. 6.1). That choice converts into costs as we identify the processing conditions and configurations and the required ancillary equipment. If a catalyst has been selected, then the reaction cycle and the catalyst replacement/regeneration become important. If a batch or semi-batch reactor is selected, then the cycle times become issues. 

The user equipment manual should contain the application-specific information on how the equipment should be installed, configured, operated, and maintained to achieve the required performance in the operating environment, particulady noting any performance issues, such as performance or life expectancy degradation due to process application or ambient environment extremes. The user manual may require a subset of the allowable options in the manufacturer manuals or require specific alternatives that have been determined through operational history to be necessary for the application. 

The NRC issued a letter in 1994 to the nuclear industry reemphasizing NRC guidance on voluntary online maintenance. Specifically, the letter stated that l)the practice should represent a net safety benefit and be warranted by operational necessity, not by convenience, 2) the practice should not be abused by repeated entry into and exit from the limited condition of operation, 3) the removal from service of safety systems and important non-safety equipment should be minimized, 4) Any component testing or maintenance that increases the likelihood of a plant transient should be avoided plant operation should be stable, and 5) Configuration control and system/train unavailability must be effectively managed to minimize risk during maintenance activities. 

Increasing popularity of Technical specifications for shutdown clearly indicate that the shutdown safety is to a large extent the configuration control issue. Technical specifications in most cases introduce somewhat rigid requirements, which is somewhat detrimental for shutdown operations, where the necessary availability of equipment and allowed configurations depends highly on the decay heat level etc. 

Once the design has been developed to a stage where it is known how the requirements are to be fulfilled and how the major plant systms and components will be configured, the design documentation is usually issued as specifications for procurement. In negotiating the contracts for plant systems and equipment, the designer... 

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