Project

Engineering Services and Support of QA: Enhancement of TRACE Model for NPP Gösgen. TRACE_KKG Model Verification and Validation against KKG full scope simulator.

Goals of the project

• The main goals of this project are, as follows:
• Implementation of plant models (Main and GUI models) improvements and optimizations.
• To identify present TRACE_KKG model limitations which require improvements.
• To present results from the calculations for LOOP, MCP2 trip and SGTR scenarios which are performed with the TRACE V5.0 computer code by applying the KKG plant model.
• To describe the chronology of the main events during the accident progression.
• To analyze the results and to comment the major differences found.
• To graphically represent comparison of the main parameters between TRACE V5.0 calculations and reference scenarios.

Scope of the project

The scope of the calculations covers the following scenarios (all of the scenarios are compared against KKG full scope simulator reference runs):

• Scenario 1: Loss of off-site power supply (Notstromfall) with all RR pumps in operation. Cooling by ARV with 100 K/h till the moment when secondary pressure reaches 80 bar.
• Scenario 2: Loss of off-site power supply (Notstromfall) with 1 out of 2 RR pumps in operation. Cooling by ARV with 100 K/h till the moment when secondary pressure reaches 5 bar (corresponds to steam temperature 150 oC).
• Scenario 3: Loss of off-site power supply (Notstromfall) with SG1 SRV stuck in open position after the first opening by signal.
• Scenario 4: Loss of off-site power supply (Notstromfall) with SG1 isolation and stepwise cooling with ARV for SG2 and SG3.
• Scenario 5: MCP2 trip without any operator actions consideration.
• Scenario 6: SGTR from the hot part of the tube bundle without Notstromfall and without any operator actions for accident management.
• Scenario 7: SGTR from the hot part of the tube bundle with Notstromfall and without any operator actions for accident management.

Status of the project

Completed

Outputs of the project

• Update of the TRACE_KKG model in compliance with the current status of the NPP systems. 
• Implementation of in-dept improvements of the TRACE_KKG model. 
• Identified differences between KKG full scope simulator and presentation of their substantiation. 
• Presentation of the good agreement between the TRACE and full scope simulator results for the considered IE (see Figure 1 ÷ Figure 6).