Main Turbine-Generator

The non-safety-related Standby ac Power Supply consists of two diesel generators. Each diesel generator (DG) provides 6.9 kVac power to one of the two load groups whenever the main turbine generator and the normal preferred off-site power source are not operating. When operating, the standby ac power supply provides power to safety- related loads and to non-safety-related investment protection loads. Other non-safety-related loads are not powered from the standby power source. 

The System 80+ Standard Design includes an onsite electrical distribution system which employs two redundant and independent Class IE load group divisions. The Class IE safety loads, are capable of being supplied, in decreasing priority, from the unit main turbine generator, unit main transformers, the emergency diesel generators and the alternate AC source (See CESSAR-DC, Section 8.1). 

This building houses the main turbine generator and the majority of the conventional plant. The principal items are the ... 

The turbine building houses the main turbine, generator and associated fluid and electrical systems. It provides weather protection for the laydown and maintenance of major turbine / generator components. The turbine building also houses the make-up water purification system. 

During normal power generation mode, the main turbine generator supplies electric power to the plant auxiliary loads through the unit auxiliary transformers. This is the normal power supply. 

Most large generator designs also incorporate a regenerative FW heating facility where from 20 to 30% of the throttle steam may be withdrawn from the turbine at various points to provide the necessary heating. In addition, the primary steam requirement for the FW pump turbines is extracted from the main turbine at the IP to LP crossover point. 

Nuclear and magneto-hydrodynamic electric power generation systems have been produced on a scale which could lead to industrial production, but to-date technical problems, mainly connected with corrosion of the containing materials, has hampered full-scale development. In the case of nuclear power, the proposed fast reactor, which uses fast neutron fission in a small nuclear fuel element, by comparison with fuel rods in thermal neutron reactors, requires a more rapid heat removal than is possible by water cooling, and a liquid sodium-potassium alloy has been used in the development of a near-industrial generator. The fuel container is a vanadium sheath with a niobium outer cladding, since this has a low fast neutron capture cross-section and a low rate of corrosion by the liquid metal coolant. The liquid metal coolant is transported from the fuel to the turbine generating the electric power in stainless steel... 

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,... 

The final stage(s) in the turbine comprise a free turbine. These stages are mounted on the shaft of an electric generator, rather than the shaft of the main turbine. To generate 60-cycle power, the free turbine rotates at 3,600 RPM. Note that the main turbine rotates at 8,500 RPM. The exhaust gas from the free turbine is sent to the steam generator. 

Anticipated operational occurrences. Anticipated operational occurrences mean those conditions of normal operation which are expected to occur one or more times during the life of the nuclear power unit and include but are not limited to loss of power to all recirculation pumps, tripping of the turbine generator set, isolation of the main condenser, and loss of all offsite power. 

The main turbine and turbine control valves, were analyzed to identify capability to mange the new steam generation rate from the nuclear reactor, control capability of the turbine control valves, considering that the pressure in the reactor vessel was unchanged related to the original design pressure. For such purposes tests were successfully performed to show the capability of the control system. 

Schematic sketch of nuclear power station with a pressurized water reactor (1) reactor, (2) steam generator, (3) main pump for primary cooling circuit, (4) turbines/generator, (5) steam drum,...

A Turbine Bypass System (TBS) is provided which passes steam directly to the main condenser under the control of the pressure regulator. The TBS has the capability to shed 40% of the turbine generator rated load without reactor trip or operation of a SRV. The TBS does not serve or support any safety-related function and has no safety design. 

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