Page 22 - Dynamics and Control of Nuclear Reactors

2.6 Generation IV reactors 13

2.4 Generation III reactors
New designs, called Generation III reactors, have been developed and constructed.
They are evolutionary improvements over Generation II reactors. Features of Gen-
eration III reactors include:
• Standardized designs that expedite licensing, reduce capital cost, and reduce
construction time
• Passive safety features that reduce the need for actuation and proper operation of
engineered safety systems
• Longer intervals between refueling achieved by use of higher fuel enrichment and
burnable poisons (materials that absorb neutrons, but whose strength declines
along with fuel consumption)
• Ability to operate with mixed oxide fuels (Uranium and Plutonium)
• Simpler designs that expedite construction and operation.

The first Generation III reactor to begin operation was the Kashiwazaki-6 ABWR
(Advanced Boiling Water Reactor) in 1996 in Japan. AP600 is a Generation III
PWR design by Westinghouse Electric Company.

2.5 Generation III+ reactors
Generation III+ reactors offer modular design and a significant improvement in
safety over Generation III reactors. These designs incorporate passive safety features
such as natural circulation and gravity coolant feed, and rely less on actuators
(valves, pumps, etc.) and operator actions. Examples of Gen-III+ designs are
AP1000 (Westinghouse), Advanced CANDU reactor (ACR1000), APR-1400
(Korean Advanced Pressurized Water Reactor), VVER-1200, and the European
Pressurized Reactor (EPR). The 1650MWe EPR is also known as Evolutionary
Power Reactor in the international market. Ref. [3] provides important design fea-
tures of the Generation III+ VVER-1200 system.
Included in Generation III+ reactors are small modular reactors (SMRs). These
range in capacity from 25MWe to 200MWe. Light water SMRs dominate current
design and development. Further details of integral and small modular reactors
are given in Appendix B. The International Atomic Energy Agency (IAEA) refers
to small and medium reactors as SMRs, with a power range of 25–350MWe.

2.6 Generation IV reactors
Work is under way to develop new reactor designs for possible construction in the
future. Currently (2019), six concepts are under consideration. The objective is to
achieve improved safety, improved proliferation resistance, reduced waste, and
reduced cost. Generation IV reactor designs provide high temperature operation.