RELAP5 model for the INPP

1. INTRODUCTION

The purpose of this project is to develop a RELAP5 model of the Ignalina Nuclear Power Plant (INPP) for use in the analysis of operational transients. This model was developed in two stages. First, a best-estimate model of the plant was developed based on the best data available. The second stage included benchmarking the model against existing plant data. The benchmarking was intended to demonstrate the fidelity of the RELAP5 model in representing a variety of plant upset conditions. This calc-note documents the development of the computer model, including the general parameters, hydro-components, heat structures, material properties, and reactor physics.

The scope of the RELAP5 model includes the following:

• reactor vessel,

• recirculation loops,

• main steam system to the turbine control valves,

• feedwater system, and

• emergency core cooling system (ECCS).

Figure 1 provides a nodalization diagram for the RELAP5 model. The left-hand-side (LHS) of the diagram depicts a lumped representation of the plant, while the right-hand-side (RHS) depicts a more detailed model. Table 1 lists and describes each node that is discussed in this calc-note.

All input data and assumptions are described in detail in Section 3.0, Analytical Methods and Calculations.