Page 245 - Dynamics and Control of Nuclear Reactors

246 APPENDIX B Advanced reactors

B.5 Large evolutionary reactors
Large reactors feature large power production capability, including units with power
production of as great as 1500 MWe. Each employs all or some of the features
described in Section B.1.
Numerous large advanced power reactors are offered by reactor vendors and sev-
eral have been built and operated at the time of preparation of this book (early 2019).
But there have been problems with cost overruns and construction delays, causing
problems for some vendors and for buyers of these advanced systems. For example,
Westinghouse Electric Company and General Electric have undergone major
restructuring.
Nevertheless, enthusiasm for advanced large reactor implementation continues in
the United States and especially in other countries. Russia, China and India have
robust programs that are much larger than U.S. programs. These countries offer Gen-
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eration III, III and even Generation IV for domestic and export markets.

B.5.1 Pressurized water reactors
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Generation III and III pressurized water reactors are offered by companies in several
countries, including The United States, France, Japan, China and Russia. These
PWRs have many common features and all strive to provide the features described
in Section B.1. Describing the unique features of each of these reactors is beyond the
scope and purpose of this book. Rather, one system, the Westinghouse AP 1000 has
been chosen for a brief description here.
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The AP1000 (for Advanced Passive) is a Generation III reactor with a thermal
power of 3400MW and an electrical power of 1117MW [6, 7]. Two AP1000 units
are operating in China (as of June 2019). Two AP1000 reactors are under construc-
tion in the U.S.
The reactor core of the AP1000 is similar to preceding Westinghouse PWRs. The
new features include fewer components in the heat removal systems, especially the
safety systems. The safety systems depend entirely on natural phenomena: gravity,
natural circulation, and compressed gas to induce coolant flow from reservoirs of
water. There are no safety-related pumps, fans, chillers or other rotating machinery.
The safety systems operate automatically. These require no operator action or elec-
trical power. The safety systems are designed to protect the fuel from overheating
indefinitely with no human intervention and without a need for electrical power.
The spent fuel pool provides indefinite cooling for spent fuel.
The safety injection systems are as follows:
• Core Makeup Tanks (CMT). These tanks provide flow to the reactor coolant
system while the pressure is still high after an accident. They contain borated
water at normal reactor coolant system pressure. Water from the CMT flows into
the reactor coolant system by gravity when isolation valves open automatically.