ماجرای دفن پسمان‌های اتمی دیگر کشورها در ایران! فراز دیگری از کتاب تاریخ تکاملی انرژی اتمی ایران، تألیف مرحوم دکتر #احمد_نخلی. @Nuc_Technology ⚛️ فناوری هسته‌ای

ما مدیون بزرگان گم‌نام و بی‌ادعا هستیم.

کتاب سیر تکاملی انرژی اتمی در ایران، نوشته دکتر #احمد_نخلی، تقدیم شما عزیزان. پی‌دی‌اف این کتاب از طریق #پژوهش‌گاه به رایگان منتشر شده و از وب‌گاه قابل بارگیری است. بنابراین نگران حق نشر کتاب نباشید. @Nuc_Technology ⚛️ فناوری هسته‌ای

A Short Lecture on Control Rods From Britannica @Nuc_Technology ⚛️ فناوری هسته‌ای

Typically a reactor is equipped with 3 types of rods for different purposes: (1) Safety rods for starting up and shutting down the reactor; (2) Regulating Rods for adjusting the reactor’s power rate, and (3) Shim Rods for compensating for changes in reactivity as fuel is depleted by fission and neutron capture.

(A) Safety Rods The most important function of the safety rods is to shut down the reactor in either scheduled or emergency cases. These rods contain enough absorber to terminate a chain reaction under any conceivable condition. They are withdrawn before fuel is loaded and remain available in case a loading error requires their action. After the fuel is loaded, the rods are inserted, to be withdrawn again when the reactor is ready for operation. (B) Regulating Rods Regulating rods are deliberately designed to affect reactivity only by a small degree. It is assumed that at some time the rods might be totally withdrawn by mistake, and the idea is to keep the added reactivity in such cases well within sensible limits. A well-designed regulating rod will add so little reactivity when it is removed that the delayed neutrons (see above Reactor control) will continue to control the rate of power increase (ro < beta_eff). (3) Shim Rods Shim rods are designed to compensate for the effects of fuel burnup. Reactivity changes resulting from burnup can be large, but they occur slowly over periods of days to years, as compared with the seconds-to-minutes range over which safety actions and routine regulation take place. Therefore, shim rods may control a significant amount of reactivity, but they will work optimally only when constraints are imposed on their speed of movement. A common way in which shims are operated is by inserting or removing them as regulating rods reach the end of their most useful position range. When this happens, shim rods are moved so that the regulating rods can be reset. The functions of shim and safety rods are sometimes combined in rods that have low rates of withdrawal but that can be rapidly inserted. This is usually done when the effect of burnup decreases reactivity. The rods are only partially inserted at the outset of operation. However, in the event that the system must be shut down as quickly as possible, the reactor operator may “scram” the reactor. The amount of shim control required can be reduced by the use of a burnable “poison.” This is a neutron-absorbing material, such as boron or gadolinium, that burns off faster than the fissile material does over the lifetime of the core. At the beginning of operation, the inclusion of a burnable poison regulates the extra reactivity that has been built into the fuel to compensate for the amount of fuel consumed. At the end of an operating period, the absorbing material is often completely transformed through neutron capture. @Nuc_Technology ⚛️ فناوری هسته‌ای