ON ASSESSMENT OF STRENGTH AND LIFETIME OF POWER EQUIPMENT IN TERMS OF MODERN CAPABILITIES

Abstract

The normative documents, which determine requirements to the scope, procedure and methods of assessing the strength and lifetime of equipment of TPP, NPP and HPP developed in the 1970s-1980s relied on the technical capabilities available at the time. The calculations were mainly based on analytical approaches and were consistent with the safety factors taking into account the inaccuracy of calculation, possibilities of technologies of manufacture and diagnostics of resource defining elements, features made inherent at the stage of design of operating conditions.

Currently, numerical approaches based on the finite element method (FEM) are widely used. They enable to perform simulation without adopting various kinds of assumptions, suppositions and simplifications, which is one of the significant advantages of this method. However, the accuracy of the calculation largely depends on the quality of the design model: specified external loads, conditions of matching of the elements, set boundary conditions.

For long and ultra-long useful life of equipment, exceeding the design life two-fold or with a larger factor, application of conventional approaches based on regulatory requirement would lead to failure to meet safety factors, although their technical state is satisfactory. In this case, an improved approach is required, which would take into account specific features of particular equipment and extensive opportunities off ered by modern computational methods.

The paper describes the basic principles of approaches currently used by JSC «NPO CKTI» to assess the strength and lifetime of power equipment [1 – 3].