DOE-HDBK-1017/2-93Brittle FractureHEATUP AND COOLDOWN RATE LIMITSHEATUP AND COOLDOWN RATE LIMITSPersonnel operating a reactor plant must be aware of the heatup and cooldownrates for the system. If personnel exceed these rates, major damage could occurunder certain conditions.EO 1.12IDENTIFY the basis used for determining heatup and cooldownrate limits.EO 1.13IDENTIFY the three components that will set limits on the heatupand cooldown rates.EO 1.14STATE the action typically taken upon discovering the heatup orcooldown rate has been exceeded.EO 1.15STATE the reason for using soak times.EO 1.16STATE when soak times become very significant.BasisFigure 6 Heatup and Cooldown Rate LimitsHeatup and cooldown rate limits, asshown in Figure 6, are based upon theimpact on the future fatigue life of theplant. The heatup and cooldownlimits ensure that the plant's fatiguelife is equal to or greater than theplant's operational life. Largecomponents such as flanges, thereactor vessel head, and even thereactor vessel itself are the limitingcomponents. Usually the mostlimiting component will set the heatupand cooldown rates.Thermal stress imposed by a rapidtemperature change (a fast ramp oreven a step change) of approximately20F (depending upon the plant) isinsignificant (106cycles alloweddepending upon component) and has no effect on the design life of the plant.Rev. 0Page 11MS-04
Integrated Publishing, Inc. - A (SDVOSB) Service Disabled Veteran Owned Small Business