Control rod drive system

The drives do not interfere with refueling and are operative even when the head is removed from the reactor. Furthermore, this location makes them more accessible for inspection and servicing. Such an arrangement makes maximum use of the water in the reactor as a neutron shield, while yielding the least possible neutron exposure to drive components. 

The locking piston drive provides the highest scram forces and operating force margins of all known types of drive mechanisms. This provides high operational reliability, particularly in the scram function. 

The use of water of reactor quality as the operating fluid eliminates the need for special hydraulic systems, with their inherent leakage and maintenance problems. 

The continuous inflow of high-purity water through the drives minimizes the contamination deposits within the drives from foreign material that may be in the reactor vessel. 

The number of drives supplied with a reactor is selected to give the optimum power distribution in the core and to give the operator the maximum degree of control flexibility during startup, maneuvering, and flux shaping. 

---

Nuclear Boiler Assembly. This assembly consists of the equipment and instrumentation necessary to produce, contain, and control the steam required by the turbine-generator. The principal components of the nuclear boiler are (1) reactor vessel and internals—reactor pressure vessel, jet pumps for reactor water circulation, steam separators and dryers, and core support structure (2) reactor water recirculation system—pumps, valves, and piping used in providing and controlling core flow (3) main steam lines—main steam safety and relief valves, piping, and pipe supports from reactor pressure vessel up to and including the isolation valves outside of the primary containment barrier (4) control rod drive system—control rods, control rod drive mechanisms and hydraulic system for insertion and withdrawal of the control rods and (5) nuclear fuel and in-core instrumentation,... 

Control Rod Drive System. Positive cure reactivity cuulrol is maintained by the use of movable control rods interspersed throughout the core. 

The system considered is the Stand-By Liquid Control (SBLC) system analyzed by Wu (2007). The SBLC system provides an independent alternative method to the control rod drive system which is the primary system for shutting down the reactor. 

In the design of NHR-200 the loads of GGW are cooling of coolant purification system, condenser of liquid waste treatment system, and cooling of the control rod drive system. Among them there are no safety-related systems, therefore, the GGW is classified as a non-safety related. 

Control rod drive system X 177 fine motion control rod drives... 

Control rod drive system tests in cold and hot condition. 

The BWR is the only light water reactor system that employs bottom-entry control rods. Bottom-entry and bottom-mounted control rod drives allow refueling without removal of control rods and drives and allow drive testing with an open vessel prior to initial fuel loading or at each refueling operation. The hydraulic control rod drive system, which incorporates... 

Control rod drive system Control rods, control rod drive mechanisms, and hydraulic system for insertion and withdrawal of the control rods... 

Enhancement of the ABWR and ESBWR converts from the complex mechanical-hydraulic control rod drive system to a simple fine motion control rod drive (Figure 3.11). 

The MASLWR is a light water reactor that relies strongly on existing LWR technology. The reactor fuel materials, the fuel bundle geometry, and the control rod drive system are based on the established LWR technology. Similarly, the secondary side steam turbine/generator set considered for implementation is an industry standard. However, there are several innovative... 

Operation and maintenance instructions control rod drive system for Browns Ferry nuclear plant, GER-9585/9586, June 1971. 

All but one licensee chose to install a backfill modification which would constantly purge the reference leg with a very low flow rate of water supplied by the control rod drive system. The constant flow of water up the reference leg would prevent dissolved gases from moving down the reference leg. One licensee has installed condensing chamber vents to prevent the buildup of gases. 

Tests are completed on the control rod drive system that demonstrate that the control rods have been latched, that the control and position indication systems are functioning properly and that the rod drop time under hot full flow conditions is less than the Tech-Specs limit. 

Expansion, vibration and dynamic effects testing of high-energy piping and components Control rod drive system testing ... 

Coolant inventory (high pressure) Control rod drive system Feedwater system Isolation condenser system. 

This mode of core cooling was adequate until about 6 00 p.m., when loss of control air prevented further manual control of the remaining (4 out of 11) operable pressure-relief valves. The valves closed, and pressure in the vessel started building up again. As pressure increased above 2.4 MPa (350 psi), the condensate booster pumps could no longer inject water into the vessel and thus only the control-rod-drive-system pump was adding water. 

Continuing NRC review of this event identified a potential for unacceptable interaction between the control rod drive system and the nonessential control air system therefore, IE Bulletin 80-17 Supplement 3 was issued on August 22, 1980. This Supplement required affected BWR licensees to implement operating procedures within five days, which required an immediate manual scram on low control air pressure, or in the event of multiple rod drift-in... 

DPSOL 1-82222, "Actuator Synchro System Checkout" (Reference 18), is used for checking proper operation of the control rod drive system synchronizer units. This procedure provides documentation of the electrical signals generated in... 

---