1.1 Introduction
Westinghouse Electric Company designed an advanced 600 MWe (1933 MWt)
nuclear power plant called the AP600. The AP600 uses passive safety systems
to enhance plant safety and to satisfy US licensing requirements. The use of
passive safety systems provides significant and measurable improvements in
plant simplification, safety, reliability, investment protection and plant costs.
These systems use only natural forces such as gravity, natural circulation, and
compressed gas to provide the driving forces for the systems to adequately cool
the reactor core following an accident. The AP600 received Design Certification
by the Nuclear Regulatory Commission in December 1999.
Westinghouse then developed the
AP1000 standard nuclear reactor design
based closely on the AP600 design. The AP1000, with a power output of
approximately 1000 MWe (3400 MWt), maintains the AP600 design
configuration, use of proven components and licensing basis by limiting the
changes to the AP600 design to as few as possible. The AP1000 received
Design Certification by the Nuclear Regulatory Commission in January 2006.
The AP1000 reactor and passive safety features retain the same configuration
as the AP600. The capacities of the major reactor components have been
increased to support the increased power rating. The approach to designing the
passive safety features (core cooling and containment cooling) is to evaluate
each feature to determine if changes are necessary to provide proper safety
margins at the higher power rating. Preliminary safety evaluations have shown
that the AP1000 passive safety systems provide adequate performance during
limiting design basis accidents.
Figure 1-1 shows the AP1000 plant layout, Figure 1-2 shows the AP1000
containment layout, and Figure 1-3 shows the AP1000 site layout.
1.2 Plant Overview
1.2.1 Design Origin and Overall Plant Description
The AP1000 is a two-loop, 1000 MWe pressurized water reactor (PWR) with
passive safety features and extensive plant simplifications to enhance the
construction, operation, and maintenance. The AP1000 design is derived
directly from the AP600, a two-loop, 600 MWe PWR. The AP1000 retains the
AP600 approach of using proven PWR technology and safety features that rely
on natural forces.
The AP1000 passive safety systems are the same as those for the AP600,
except for some changes in component capacities. The safety systems
maximize the use of natural driving forces such as pressurized gas, gravity flow,
and natural circulation flow. Safety systems do not use active components (such
国家核电技术公司 AP1000培训教材
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as pumps, fans, or diesel generators) and are designed to function without
safety-grade support systems (such as alternating current [ac] power,
component cooling water, service water, or heating, ventilation, and
air-conditioning (HVAC). The number and complexity of operator actions
required to control the safety systems are minimized; the approach is to
eliminate required operator action rather than to automate it. The net result is a
design with reduced complexity and improved operability.
The approach in uprating the AP600 to the AP1000 was to increase the power
capability of the plant within the space constraints of the AP600, while retaining
the credibility of proven components and substantial safety margins. Therefore,
the AP1000 retains the AP600 licensing basis.
Some of the high-level design characteristics of the AP1000 are as follows:
• Net electrical power is approximately 1090 MWe, and nuclear steam supply
system (NSSS) thermal power is 3415 MWt.
• Rated performance is achieved with up to 10 percent of the steam generator
tubes plugged and with a maximum hot leg temperature of 6170F.
• Major safety systems are passive; they require no operator action for 72
hours after an accident, and maintain core and containment cooling for a
protracted time without ac power.
• Predicted core damage frequency will be similar to AP600 (1.7E-07/yr) and
will be well below the 1E-04/yr requirement. The frequency of significant
release will be similar to AP600 (1.8E-08/yr) which is well below the 1E-06/yr
requirement.
• The core is designed for an 18-month fuel cycle.
• Overall plant availability is greater than 93 percent, including forced and
planned outages; the goal for unplanned reactor trips is less than one per
year.
• The plant is designed to accept a 100-percent load rejection from full power
to house loads without reactor trip or operation of the -pressurizer or steam
generator safety valves. The design provides for a turbine capable of
continued stable operation at house loads.
• The plant is designed with significantly fewer components and significantly
fewer safety-related components than a current pressurized water reactor of a
comparable size.
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核电技术公司 AP1000培训教材
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• The plant design objective is 60 years without the planned replacement of
the reactor vessel, which itself has a 60-year design objective based on
conservative assumptions. The design provides for the replaceability of other
major components, including the steam generators.
• The design of the major components required for power generation - such as
the steam generators, reactor coolant pumps, fuel, internals, turbine, and
generator - is based on equipment that has successfully operated in power
plants. Modifications to these proven designs were based on similar
equipment that had successful operating experience in similar or more severe
conditions.
发表于 2010-12-1 23:04:48