The major issue in designing safety and control systems for power reactors is preventing accidents or reducing the hazard imposed. Any change in reactor power causes a change in temperature and material densities of the system that will affect the reactivity, which in turn, causes transients/accident conditions. The analysis of main safety parameters is essential for any change to ensure the safe operation of the reactor in both steady and transient situations. In this paper, the impact of temperature, moderator density, boron concentration and control rods position changes on the safety parameters is studied to assess the behavior of the reactor under accident conditions. The main safety parameters as temperature reactivity coefficients, power peaking factor, effective delayed neutron fraction and generation time are evaluated under accident conditions for VVER-1000 core using MCNP6 code and ENDF/B-VII.1library. The results evidenced that the reactivity coefficients are still negative, under accident conditions, which guarantee the safe operation of the reactor. The effective delayed neutron fraction increased as a result of increased temperature, decreased moderator density and addition of the soluble boron. The worth of the control rods is sufficient to make the reactor into a subcritical state either in emergency situations or with regular shutdown.

设计动力反应堆安全和控制系统的主要问题是防止事故或减少危害。反应堆功率的任何变化都会导致温度和系统材料密度的变化，从而影响反应性，进而导致瞬态/事故情况。主要安全参数的分析对于任何更改都至关重要，以确保反应堆在稳定和瞬态情况下均能安全运行。本文研究了温度，调节剂密度，硼浓度和控制棒位置变化对安全参数的影响，以评估反应堆在事故条件下的行为。主要安全参数包括温度反应系数，功率峰值因子，使用MCNP6代码和ENDF / B-VII.1库，在事故条件下对VVER-1000堆芯评估了有效的延迟中子分数和生成时间。结果表明，在事故条件下，反应性系数仍为负值，这保证了反应堆的安全运行。由于温度升高，减速剂密度降低和可溶性硼的添加，有效的延迟中子分数增加。控制杆的价值足以使反应堆在紧急情况下或定期停机时进入亚临界状态。由于温度升高，减速剂密度降低和可溶性硼的添加，有效的延迟中子分数增加。控制杆的价值足以使反应堆在紧急情况下或定期停机时进入亚临界状态。由于温度升高，减速剂密度降低和可溶性硼的添加，有效的延迟中子分数增加。控制杆的价值足以使反应堆在紧急情况下或定期停机时进入亚临界状态。