Reactor regulating system

Kervalishvili, P. 2010. Some neutron absorbing elements and devices for nuclear reactor regulation system. NATO Sci. Peace Secur. Ser. B 147-155. 

E. No credit is taken for CEA motion prior to the reactor trip. Normally the Reactor Power Cutback System (RPCS) would automatically effect a partial scram to rapidly reduce reactor power. The Reactor Regulating System (RRS) would also (slowly) insert CEAs to reduce reactor power. 

Reactivity control 1 Reactor regulating system 2 Shutdown system 1, shut-off rods 3 Shutdown system 2, Gd poison mjection 4 Loss or dilution of DjO moderator 1 A 2 P 3 P 4 P Power manoeuvres mclude ramp setback, stepback and tnp 2 and 3 are engmeered safety systems for tnp 1 can serve m an assisbng role to shutdown sy stems No 1 and 2 In 4 HjO from ECC or leakage or boilmg down of moderator leads to subcnticality... 

REACTOR SHUTDOWN SYSTEMS (Special Safety Systems) AECB R-8 CSA N290 1 DBE There are two passive frdlv capable, fasl-acbng independent and diverse shutdown systems independent of the reactor regulating system... 

REACTOR REGULATING SYSTEM CSA N290 4 Provides for control of the reactor power and neutron fla distnbution dunng plant operabon It also has the capability to shut down the reactor for anUcipated operabonal occurreoces... 

The fundamental design requirement of the reactor regulating system is to control the reactor power at a specified level and, when required, to maneuver the reactor power level between set limits at specified rates. The reactor regulating system combines hie reactor s neutron flux and thermal power measurements by means of reactivity control devices and a set of computer programs to perform three main functions ... 

Reactor regulating system action is controlled by digital computer programs that process the inputs from various sensing devices and activate the appropriate reactivity control devices. 

The nuclear instrumentation systems are designed to measure reactor neutron flux over the full operating range of the reactor. These measurements are required as inputs to the reactor regulating system and safety systems. The instrumentation for the safety systems is independent of that used by the reactor regulating system. 

The function of fhe zone control system is to maintain a specified amount of reactivity in the reactor, this amount being determined by the deviation from the specified reactor power set point. If the zone control system is imable to provide the necessary correction, the program in the reactor regulating system draws on other reactivity control devices. Positive reactivity can be added by withdrawal of absorbers. Negative reactivity can be induced by insertion of mechanical control absorbers or by automatic addition of poison to the moderator. 

The reliability of the reactor regulating system is of paramount importance and is achieved through having... 

The majority of pressure tube HWRs have protective functions in the reactor regulating system—a normally operating process system—that reduce reactor power when required to maintain process conditions in a safe operating range and provide protection of components and equipment. The power reduction can be gradual (power setback) or rapid due to absorber rod drop into the core (stepback). 

In addition to the reactor regulating system provisions, current HWR designs have two diverse, independent, fast-acting, equally effective and fail-safe safety SDSs, referred to as SDSl and SDS2 (Figure 4.10). 

A very small LOCA (or leak) is defined as having a break discharge flow rate that can be handled by the heavy water makeup system without the need for any safety system intervention. A small break LOCA is defined as a pipe break that carmot be compensated by the heavy water makeup system and extends multiple feeder pipe ruptures such that the reactor regulating system, without credit for stepback action, is capable of limiting any power excursion. A large break LOCA is defined as a pipe break beyond the range of breaks in multiple feeder pipes which give rise to uncompensated coolant void reactivity and a resultant power excursion. 

All control and shutdown devices, and in-core instrumentation are located within tubes perpendicular to the fuel channels and function within the low temperature and low pressure environment of the moderator. All CANDU reactors have two completely independent reactor shutdown systems of different designs, each capable of shutting down the reactor these safety systems are in addition to the reactor regulation system. 

Graphite Reflector Downcomer Tubes BeO Reflector Reactor Regulating System... 

Reactor Protective System Reactor Regulation System Primary Heat Transport System Moderator System... 

Reactor regulating system Normal operation or inactive, whichever is worse a set-back is generally not credited unless it tends to blind the trip. Choose so as to delay reactor trip. 

Since normal action of the reactor regulating system (RRS) can compensate for the slow increase in reactivity due to coolant void, and delay the trip on high power, two cases are considered that with the RRS inactive and that with the RRS operating normally. 

RRS. Reactor regulating system. Digital system that controls reactivity devices and the major process systems. 

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