Plant operation load changes

This type of data, which is routinely taken over the life of a machine, is directly comparable to historical data taken at exactly the same running speed and load. However, this is not practical because of variations in day-to-day plant operations and changes in running speed. This significantly affects the profile and makes it impossible to compare historical data. 

Once this initial data has heen recorded, a running log will indicate the performance under service conditions. As the load and amhient conditions change, the plant operators will he ahle to monitor the day-to-day conditions. This estahlishes normal running. Only hy a clear understanding of what is normal can the abnormal be detected. 

Effective wastewater management in this phase of veneer and plywood production can be accomplished in part by in-plant operational changes and in part by equipment modification. For plants with hot water vats that are heated indirectly with steam coils, the discharge results from spills in loading and unloading the vat and from periodic cleaning. Plants operating in this manner need only to collect the water in small ponds or tanks and reuse it for vat makeup water. Adjustments in pH by the addition of lime or caustic soda may be required to control acidity and prevent the development of corrosion problems. 

In defining the disturbances, the need to start the plant up should be considered. A reasonable base-case set of disturbances is startup from zero flow to at least 25% of maximum flow in a single step and a 10% load change at maximum flow. A treatment system that cannot satisfy these requirements is unlikely to be adequately operable. These base-case disturbances may be used in preliminary analysis if actual data are not available. 

Control rods are used primarily for power distribution shaping and for shim control of long-term reactivity changes, which occur as a result of fuel irradiation. The flow control function, which is used to follow rapid load changes, reduces requirements on speed of control rod response and thus improves plant safety. Every 2-3 months, the control rod patterns are altered to provide more uniform fuel and control rod burnup. In normal daily operation, little control rod movement is required for depletion of reactivity. The resulting low frequency of control rod changes reduces the possibility of operator error. 

Automatic/manual control—term describing two modes in which controllers can be operated. During plant start-up, the controller is typically placed in the manual position. In this mode, only manual control affects the position of the control valve it does not respond to process load changes. After the process is stable, the operator places the controller in automatic mode, which allows the controller to supervise the control loop function. At this point, the controller will automatically open and close the control valve to maintain the setpoint. 

The OPs for normal operation should be developed to ensure that the plant is operated within the OLCs and should provide instractions for the safe conduct of all modes of normal operation, such as starting up, power production, shutting down, shutdown, load changes, process monitoring and fuel handling. The OPs should be submitted to the regulatory body for assessment and approval if required. 

The chemical and volume control system provides a means to add and remove mass from the reactor coolant system, as required, to maintain the programmed inventory during normal plant operations. Operations that are accommodated include start-up, shutdown, step load changes, and ramp load changes. 

The PLS provides automatic regulation of reactor and other key system parameters in response to changes in operating limits (load changes). The PLS acts to maximize margins to plant safety limits and maximize the plant transient performance. The PLS also provides the capability for manual control of plant systems and equipment. Redundant eontrol logie is used in some applieations to increase single-failure toleranee. 

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