1. Increasing the fuel enrichment in a commercial PWR from 2.5% to 4.0% causes the value of the resonance escape probability to decrease. ... FALSE: fewer U-238 atoms means less resonance absorption, and greater escape probability.

2. Increasing the physical size of a commercial PWR or BWR core causes the value of the non-Leakage probability to increase because of the larger surface area. ... FALSE: leakage depends on the ratio of surface area to volume. As size increases, surface area increase is by the square of the dimension, while volume increase is by the cube of the dimension.

3. The time required for reactor power to change by a factor-of-e is called the reactor startup rate. ... FALSE: the time for power to change by a factor-of-e is called the reactor period.

4. For power reduction from 100% to 20% rated in a commercial PWR or BWR, the doppler coefficient of reactivity will contribute positive reactivity, requiring control rod insertion to maintain criticality. ... TRUE: the doppler coefficient is negative for increasing fuel temperature. As power is reduced, fuel temperature decreases.

5. The conditions required for a reactor to be subcritical are: k_eff must be less than 1.0 and power must be decreasing with time. ... FALSE: the only requirement for defining subcriticality is that k_eff is less than 1.0.

6. Delayed neutrons act as source neutrons by initiating chain reactions. ... TRUE: delayed neutrons are present from shutdown to full power and always act as a neutron source. See NUKEFACT #2.

7. The fraction of the neutron production that consists of precursor atoms is represented by the Greek letter beta. ... TRUE: beta is the precursor yield fraction, not the delayed neutron population fraction.

8. The strongest neutron source in the core is always the delayed neutron source. ...FALSE: for equilibrium subcritical multiplication conditions, the delayed neutron source is of equal strength to the non-fission source at reactivity = -0.0065. For greater negative reactivities the delayed neutron source is weaker than the non-fission source. See NUKEFACT #2 .

9. Prompt drop occurs in reactor rate during reactor scram. ... FALSE: prompt drop occurs in reactor power, not reactor rate. See NUKEFACT #27.

10. The rule-of-thumb value for the single precursor group effective decay constant (lambda- effective) when supercritical is 0.15 seconds^-1. ...FALSE: the rule-of-thumb value is 0.1 seconds^-1.

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