本文提出了利用改进的源倍增法测量次临界系统的绝对反应性与跳源法测量的相对反应性相比获得缓发中子有效份额βeff的方法。用改进的源倍增法测量了ADS启明星1#次临界反应堆某次临界状态下的绝对反应性为-2.235×10-3。在相同的次临界状态下,用跳源法测量了以βeff为单位的反应性ρ/βeff为-0.291 5$,二者相比得到ADS启明星1#次临界反应堆的缓发中子有效份额为0.007 667。利用MCNP建模计算的结果为0.007 783,两者在2%内符合。
The principle about measurement of the effective delayed neutron fractionβeff by modified neutron source multiplication(MNSM)method combining source jerk method was given.Firstly,the absolute reactivityβof ADS Venus 1# sub-criticality reactor measured by MNSM method is-2.235×10-3.Under the same sub-criticality condition,the reactivityρ/βeffinβeffmeasured by source jerk method is-0.291 5 $.The effective delayed neutron fraction is 0.007 667 by comparingρ/βeffwithρ.The effective delayed neutron fraction of MCNP is 0.007 783,which corresponds with the experiment result within 2%.