Nuclear steam supply control system

Nuclear steam supply control system— Implements the operator s control decisions and automatically changes the plant to and maintains it at selected operating states. Reactor protection system—Protects the reactor core and the NSSS by monitoring operating parameters and initiating safeguard actions on the detection of abnormal conditions. 

Nuclear Island Cooling Water Building Normal Operating Pressure Net Positive Suction Head Nuclear Steam Supply System Operating Basis Earthquake Outer Neutron Control Assemblies Outer Pyrocarbon Peak Accelerograph Protective Action Guidelines Private Automatic Exchange... 

The CANDU 3 nuclear steam supply system includes the reactor, the heat transport system, the moderator system, the shutdown cooling system, the fuel handling system and associated control and service systems located within the reactor building (Figure 5.8.1 A) and the emergency core cooling system. The followng sections provide detail on specific NSSS system. 

The heat produced by controlled fission in the fuel is transferred to the pressurized heavy water coolant and circulated through the fuel channels and steam generators in a closed circuit. In the steam generators, the heat is used to produce light water steam. This steam is used to drive the turbine generator to produce electricity. The nuclear steam supply system (NSSS) is illustrated in Figure 4.2. 

PRISM employs passive safety, digital instrumentation and control, and modular fabrication techniques to expedite plant construction [1-4]. PRISM has a rated thermal power of 840 MW and an electrical output of 311 MWe. Each PRISM module has an intermediate sodium loop that exchanges heat between the primary sodium coolant from the core with water/steam in a sodium-water steam generator (SG). The steam from the sodium-water SG feeds a conventional steam turbine. A diagram of the PRISM nuclear steam supply system (NSSS) is shown in Figure 6.2. 

In general, it is the performance of a number of key components (Including fuel, primary pumps, control devices, steam generators, and reactor vessel or pressure tubes) that dictates the performance of the nuclear steam supply system. Except for fuel, malfunction of these key components inevitably leads to a unit outage, and repair or replacemnt is difficult, time consuming and costly. Fuel failures also pose operating problems, particularly for reactors that are fuelled off power. 

The VKR-MT nuclear steam supply system uses a direct cycle vessel-type boiling water reactor, which includes (see Fig. X-10 and X-11) (a) The reactor vessel (b) The reactor vessel cover (c) An internal metallic shaft (d) The core (e) Two stages of the centrifugal separators (f) The block of protective tubes (g) Radiation and thermal shielding of the reactor vessel (h) The supporting structure (i) Jet pumps (j) Control rod drives (k) The reloading system for micro fuel elements. 

The primary components of each RS (core, reflectors, and associated supports, restraints, and controls) are contained in the reactor vessel. The nuclear heat is generated in the reactor core. Removal of the heat energy is provided by the Heat Transport System (HTS) with the main circulator providing the driving force to supply helium coolant into an upper core inlet plenum and to draw heated coolant from a bottom core outlet plenum. The primary coolant is distributed to numerous coolant channels running vertically through the core. The outlet plenum directs the flow to the central portion of the coaxial cross duct which channels the helium flow to the steam generator vessel (see Chapter 5). 

---