Show Your Voice｜核电英语第十期

英文:Since two or three neutrons are liberated in each of fission whereas only one is required to maintain a fission chain, it would seem that once the fission reaction were initiated, it would readily sustain itself.However, such is not the case because not all the neutrons produced in fission are available to carry on the fission chain, that is, some neutrons are lost in nonfission, whereas other neutrons escape from the system undergoing fission.

译文:由于每次裂变放出两个或三个中子，而维持临界只需一个中子，因此似乎一旦开始临界，就很容易维持下去。然而，情况并非如此，因为不是所有裂变中产生的中子都能用来进行裂变，一些中子在非裂变反应中损失了，而另一些中子则从进行裂变的系统中逃走了。

英文:The fraction of neutrons lost by escape through the geometric boundaries can be reduced by increasing the size of the fissile material. The minimum quantity of such material that is capable of sustaining a fission chain is called the critical mass.In a finite system, the critical condition is defined in terms of the effective multiplication factor （keff ）which describes all the possible events in the life of a neutron.

译文:中子由于逃出几何边界而损失的份额可以用增大易裂变物质的尺寸来减少.能维持裂变链所需要的这种（易裂变）物质的最小的数量叫做临界质量。在一个有限大小的系统（反应堆）内，临界条件可以用有效增殖因子这一术语来确定。有效增殖因子描述了中子寿期内所有可能的事件。

英文:In PWR, the fuel supply cannot be continuously replaced as it is consumed. Consequently, at the beginning of each operational period, the reactor core must contain all the fuel that will be required to produce a predetermined quantity of energy.Furthermore, additional fuel is necessary to allow for the decrease in neutron multiplication arising from fission-product poisons and from the high operating temperature, i.e., the negative temperature coefficient.

译文:在压水堆中，新燃料不可能连续地代换消耗掉的燃料。因此在每一个运行周期的一开始就必须把生产预定能量所需的全部燃料一次装入反应堆堆芯。此外，还需要一部分附加的燃料用以补偿由于裂变产物中毒和高温运行中负温度系数引起中子倍增的下降。

陈子鸣

A part-time singer n trainer, full-time engineer n dreamer. 

A Pisces, majored in nuclear physics.

转自：中核运行英语学习社