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Hot functional tests are conducted only once during the plant life. The hot functional test is conducted at elevated temperature and at a flow rate, which is greater than during normal plant operation to assure covering the range of operating flows with margin. The hot functional tests consist of operation with all pumps for a minimum of ten days. The hot functional tests ensures that the flow-induced load cycling (vibration) of the reactor pressure vessel internals will be well into the high cycle range of their material fatigue design curves, thus providing assurance that the high cycle fatigue usage of the reactor pressure vessel internals will be low throughout the plant design life.

These are system cycling, thermal cycling and flow induced vibration. System cycling System cycling refers to changes in the reactor system operating conditions which cause variations in pressure and temperature. Examples of system cycling are startups, shutdown, SCRAM and safety/relief valve (SRV) actuation. Some system cycling events only affect a portion of the vessel. For example, loss of feedwater heaters is significant to the feedwater nozzle and sparger, but has no noticeable impact elsewhere in the vessel.

This guideline was revised in 1996. Table 4-3a to c show the operating values of the revised VGB Guideline. 4550 (core shroud region) and the EPRI Guideline were taken into account for this revision. However there are some discrepancies between this guideline and the EPRI Guideline. e. use of stabilized stainless steels. 44 TABLE 4-2a EPRI WATER CHEMISTRY GUIDELINES REACTOR WATER –NWC- POWER OPERATION (>10% Power) a Note: This table applies to site specific target components exposed to NWC environments or not protected to –230 mV(SHE) by HWC.

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