12.251. In order to provide protection against possible sabotage, the reactor installation must be enclosed within at least two separate barriers with a “protected area” between them. An isolation zone, clear of all objects, must surround the protected area. Both the protected area and the isolation zone must be illuminated at night and continuously monitored to detect the presence of unauthorized persons or vehicles. Access to the protected area must be strictly controlled, and packages delivered to the area must be checked. Barriers are provided to control access by vehicles to vital plant areas. Alarms must be located at important points to indicate any unauthorized entry.

12.252. The capability of continuous communication must be main­tained between guards at the nuclear plant and a central alarm station. In addition, the alarm station must maintain communications contact with local law enforcement authorities. The owner of the plant is required to maintain liaison with these authorities so that they can be called upon to provide assistance should it be necessary.

12.253. Safeguards for the protection of nuclear installations are under continuous study and review by the NRC. As better techniques are de­veloped, plant licensees are required to adopt them. If the requirements are properly implemented, the hazard to the general public from sabotage of a nuclear reactor (or a spent-fuel reprocessing) plant should be extremely small.

INTRODUCTION

13.1. The practice of nuclear engineering is focused on the design and operation principles of commercial nuclear power plants. In previous chap­ters we have discussed many such principles that apply particularly to light — water reactors (LWRs). A brief overview of pressurized-water (PWR) and boiling-water reactors (BWR) was given in Chapter 1 to provide a general background and the material in subsequent chapters tended to further develop an understanding of such systems.

13.2. The purpose of this chapter is to provide additional details of some typical commercial LWRs as well as the Canadian heavy-water mod­erated reactor (CANDU). Although no new reactors have been ordered in the United States for some years, vendors do offer various improvements for operating reactors from time to time, particularly in fuel assembly design. The specifications listed here are primarily for orientation purposes, and are not necessarily representative of the latest trend.

13.3. Space limits the discussion of details of reactor technology, which are available in other sources [1]. Descriptive information is included with

safety analysis reports submitted to the NRC and available as public doc­uments. Reactor vendors also generally provide technical brochures in response to commercial inquiries.

13.4. So-called evolutionary designs have been developed by reactor vendors for new commercial LWRs in the lOOO-MW(el) size class. These incorporate many improvements, particularly in the safety and cost re­duction area, which will be discussed in this chapter. Advanced reactors, many with passive safety features, will be covered in Chapter 15.