Reactor designs safe types

This p r postulates that new technologies, or novel combinations of existing technologies are necessary to the design of safe and economic small reactors. The paper then suggest a set of requirements that must be satisfied by a small reactor design, and defines a pool type reactor that utilizes lead coolant and TRISO fuel which has the potential for meeting these requirements. 

Passively Safe Pool-Type Reactor Designs... 

The selection of a particular type of reduction depends on technical feasibiUty and the economics of the process as well as on physicochemical considerations. In particular, the reducing agent should be inexpensive relative to the value of the metal to be reduced. The product of the reaction, RX, should be easily separated from the metal, easily contained, and safely recycled or disposed of. Furthermore, the physical conditions for the reaction should be such that a suitable reactor can be designed and operated economically. 

There are a variety of ways of accomplishing a particular unit operation. Alternative types of process equipment have different inherently safer characteristics such as inventory, operating conditions, operating techniques, mechanical complexity, and forgiveness (i.e., the process/unit operation is inclined to move itself toward a safe region, rather than unsafe). For example, to complete a reaction step, the designer could select a continuous stirred tank reactor (CSTR), a small tubular reactor, or a distillation tower to process the reaction. 

In Chapter 3, the reaction system is discussed using the heat and mass balances, and interaction with the equipment. Scale-up affects both temperature and pressure profiles, which vary with types of reactor systems and sizes. Relevant test methods for scale-up and for process design are covered, including discussions on the methods as well as the relative advantages and disadvantages. Typical approaches for safe design and for defensive measures are presented. The theoretical and experimental subjects in Chapters 2 and 3 are illustrated by the use of examples. 

The scope of this book includes several aspects of safe process design and operation, such as the choice of reactor type, safe operating conditions, and the selection of protective systems, primarily related to chemical reactivity. However, even in a process plant where these aspects have been carefully considered and thoroughly applied, there are still numerous events that can occur and can lead to hazardous incidents. Examples of such events are ... 

In the past 20 years, several advanced versions of the LWR, collectively called advanced LWRs (ALWRs), have been designed, but only one type has been built the advanced boiling-water reactor (ABWR), which was built in Japan. These reactors are generally known today as Generation III reactors. Some of these designs have been certified as safe by the Nuclear Regulatory Commission (USNRC), but no orders have materialized for them in the United States. New versions of light-water reactors are now under review for safety certification by the USNRC. 

Reactor systems for carrying out CVD processes must provide several basic functions that are common to all types of reactors. They must allow controlled transport of the reactant and diluent gases to the reaction zone, provide heat to the substrate to maintain a defined temperature and safely remove the gaseous byproducts. These functions should be fulfilled with sufficient control and maximal effectiveness, which requires good engineering design and automation. 

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