The parametric values listed in Table 6 are estimated for TRIGA reactors from calculations correlated with measurements made on other reactors of the same generic type. Although each reactor is slightly different due to its core configuration, the values given here are reasonable extrapolations. No unqualified estimate of the accuracy of the information presented herein has been made but, in general, it should be good within about 5%.

3.2. TRIGA Pulsing Performance

For transient (pulsing) operation the reactor is first brought to criticality at a low power level (usually 10 to 300 watts). This is accomplished by drawing only the standard control rods and leaving the transient rod in the core. Some facilities bring the reactor critical with all controls rods and then lower the transient rod to produce a subcritical pulse. Reactivity insertion is calculated by evaluating the differential transient rod worth curves and selecting the transient rod height. The pulse is then produced by rapidly firing the transient rod out of the core pneumatically within a fraction of a second. The reactor power will increase sharply to a value that will result in a fuel temperature increase, which will compensate for the excess reactivity inserted. At this point the peak reactor power will occur. The fuel temperature will continue to rise resulting in an increasing loss of reactivity, and the reactor power will decrease to a comparatively low level. This final power level depends on the reactivity insertion and the heat transfer characteristics of the fuel element. The power level after the transient is referred to as the after-pulse tail and is produced from the power decay of the original pulse and the delayed neutron affects. After initiation of the transient pulse, the reactor is automatically scrammed after a few seconds to clip the power tail for operational convenience. A typical TRIGA reactor pulse for a reactivity insertion of $ 1.994 is shown in Figure 9. A pulse for a FLIP reactor will be narrower with a higher peak power for the same reactivity insertion.