September 23, 2016

Advanced Candu reactors for China will be able to use recycled uranium from light water reactors

Canada and China have agreed to form a new joint venture to develop to market and construct the Advanced Fuel Candu Reactor (AFCR) in China. The deal was signed by Canada's SNC-Lavalin, China National Nuclear Corporation (CNNC) and Shanghai Electric. The reactor reuses used fuel from light water reactors.

The joint venture company is expected to be registered in mid-2017. This would be followed by the formation of two design centres - one in Canada and the other in China - to complete the AFCR technology. SNC-Lavalin said this could lead to the construction of the world's first two ACFR units in China and "possible subsequent builds in China and around the world".

The AFCR is described as "a 700 MW Class Generation III reactor based on the highly successful Candu 6 and Enhanced Candu 6 (EC6) reactors with a number of adaptations to meet the latest Canadian and international standards." The reactor features a heavy-water moderator and heavy-water coolant in a pressure tube design and can use both recycled uranium and thorium as fuel. Candu reactors can be refueled online.
Units 1 and 2 of the Qinshan Phase III nuclear power plant in China use the Candu 6 pressurized heavy water reactor technology, with Atomic Energy of Canada Limited (AECL) being the main contractor of the project on a turnkey basis.

The Candu 6 reactors should be modified to become full AFCRs.

The AFCR efficiently uses RU (recycled Uranium) from the spent fuel of LWR (light water reactors)

Current CANDU reactors, as a result of favorable reactor core physics characteristics and on-power fuelling, use approximately 30% less natural uranium per each kilowatt-hour of electricity as compared to PWR designs.

The AFCR uses advanced fuels specifically direct use of recycled uranium (DRU) fuel or low enriched uranium/thorium (LEU/Th) fuel. DRU fuel represents a gradual transition from NU-based fuels that are used in current CANDU 6 reactors. DRU fuel is similar to the already proven natural uranium equivalent (NUE) fuel in that it is composed of RU, from reprocessed pressurized water reactor (PWR) spent fuel but has a slightly higher fissile content (contains about 0.95%wt. 235U) than the NUE fuel.

The AFCR, although specifically designed for DRU and LEU/Th fuels, retains the ability to easily adapt to various fuel cycle options, such as NU, NUE and Pu/Th.

The DRU fuel is recycled uranium (RU) based fuel, arranged in a 43-element CANFLEX fuel bundle. The nominal enrichment of the RU is 0.95 wt% 235U to achieve a target burnup of 10,000 MWd/tHE.

The low-enriched uranium (LEU) and thorium (Th) fuel is a heterogeneous combination of the constituent fuels arranged in a 43-element CANFLEX fuel bundle. The fuel is designed to achieve a target burnup of 20,000 MWd/tHE.

Adopting alternative fuel cycles such as NUE, DRU, and LEU/Th significantly improves the uranium utilization rates while meeting nuclear power generation requirements. In fact, an AFCR twin-unit plant using DRU fuel would save approximately 10,000 tonnes of natural uranium over its 60-year design life.

AFCR Generation III enhancements include:
•  Extended plant life of 60 years
•  Increased operating and safety margins
•  Advanced fuel design
•  Robust design against internal and external events
•  Inherent accident resistance
•  Enhanced safety features for extended station blackout
•  Enhanced core damage prevention features and severe accident response
•  Advanced fire protection system

Reactivity control in the AFCR is a triple layer of defence that ensures reactor shutdown at all times (no loss of shutdown event)

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