This standard establishes the nuclear safety criteria and functional design requirements of structures, systems, and components of stationary pressurized water reactor (PWR) power plants. Operations, maintenance, and testing requirements are covered only to the extent that they affect design provisions.

A methodology is given for classifying all equipment into one of three Safety Classes according to its importance to nuclear safety or into a Non-Nuclear Safety Class. Another methodology is given for identifying and categorizing into one of five Plant Conditions the normal operations and events for which the plant shall be designed. Acceptance criteria are given for each Plant Condition.

Specific design requirements are given for each major system in a typical plant. These requirements are related to other more specific design standards and are intended to amplify the criteria given in the Code of Federal Regulations, Title 10; "Energy," Part 50, "Licensing of Production and Utilization Facilities," Appendix A , "General Design Criteria for Nuclear Power Plants" [1]¹

Purpose. Incorporating the requirements of this standard provides a degree of assurance that, in their entirety, plants are designed and constructed so that they can be operated without undue risk to the health and safety of the public. It is intended that this standard lead to attainment of this objective by defining existing practices that are consistent with the licensing requirements of the U.S. Nuclear Regulatory Commission (NRC), appropriate industry codes, and good engineering practice. References to regulations, codes, and other standards are included where appropriate.

A designer of a plant has a responsibility, even at the design stage, going beyond conformance to the criteria defined in this standard. In addition to considering this standard, the NRC regulations, and other published guidance, the designer must ensure that the design bases and expected operational characteristics are supported, to the extent practical, by design analyses, experimental verifications, and comparisons to accepted designs or experience gained from similar designs.

Consideration of alternate or additional criteria and requirements may be necessary to accommodate unique site characteristics.

This standard is written specifically for a PWR nuclear power plant. A PWR plant is based on closed-cycle circuits, utilizing two separate fluid systems that interface at two or more heat exchangers called steam generators. These circuits are known as the reactor coolant (or primary) system and the power conversion (or secondary) system. The reactor coolant system contains the reactor core, a water-cooled and water-moderated nuclear assembly that utilizes fissionable fuel. Heat is transferred by the reactor coolant system from the reactor core to the power conversion system at the steam generators. The power conversion system converts thermal energy into electrical energy by means of a turbine generator. Both the reactor coolant system and the power conversion system are provided with a number of auxiliary systems that supply, service, and control circulated fluids, processes and environmental conditions, and remove undesirable byproducts, distribute power, and ensure safe conditions, during normal or accident conditions. A number of structures are provided to house, contain, protect, and shield both equipment and personnel. For the purpose of this standard, a PWR plant has the following characteristics:

a. Solid ceramic fuel enclosed in metallic cladding,

b. Fixed geometry for the fuel and coolant (which acts as the moderator),

c. Core and core coolant enclosed in an envelope of high integrity, and

d. Core and core coolant envelope enclosed in a primary containment barrier of high integrity.

¹Numbers in brackets refer to corresponding numbers in Section 5, References.

Customers who purchased ANS 51.1
also purchased

• IEEE 323 : Qualifying Class 1E Equipment for Nuclear Power Generating Stations
• IEEE 384 : Standard Criteria for Independence of Class 1E Equipment and Circuits
• IEEE 603 : Standard Criteria for Safety Systems for Nuclear Power Generating Stations
• ASME B16.11 : Forged Fittings, Socket-Welding and Threaded

See More Documents