When a research reactor is scrammed after operating at a constant power level of 2.7 megawatt, it is observed that the power drops to 1 watt in 15 minutes. how much negative reactivity was inserted when the reactor was scrammed.

negative reactivity is equal to 1.68 × 10⁻³Bq

Explanation:

given,

constant power level  = 2.7 MW

power drop of 1 watt in 15 minutes.

power rises in the form of non linear form of reactivity

assuming Pj = 1

Tp = 60.77 s

the approximate Tp is calulated now to calculate reactivity

ρ = - 1.68 × 10⁻³Bq

hence, negative reactivity is equal to 1.68 × 10⁻³Bq