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Experience of Implementation of Information Technologies for Preparation for the Decommissioning and Decommissioning

29.04.2013

Authors: V. Tikhonovsky, D. Chuyko, V. Kononov, N. Salnikov (NEOLANT, JSС)

INTRODUCTION

Preparation for and decommissioning of a nuclear facility constitute a complex engineering task requiring a large amount of various information be taken into consideration and processed properly at these phases of the facility’s lifecycle. If the facility has experienced damages caused by accidents during operation, then the number of factors to be considered in planning decommissioning activities increases manifold.

Use of information technologies can be of a significant help for such a planning. This paper presents the practical experience NEOLANT company has in applying information technologies to pre-decommissioning and decommissioning activities at nuclear facilities in the Russian Federation.

Basic classes of information systems described herein are:

  • Decommissioning databases (information systems to support the decommissioning);
  • Simulation models.
Fig. 1. Forms of information in decommissioning database
Fig. 1. Forms of information in decommissioning database

DECOMMISSIONING DATABASES

For the most of the nuclear facilities utilizing SAFSTOR method of decommissioning, the objective of the decommissioning database is to provide the future generations of specialists with well-structured design and maintenance data on both the facility and its operational infrastructure. Other purposes of the database are to maintain reliable and relevant information to support the facility dismantlement.

The key features of these solutions include (Fig. 1):

  • 3D models of nuclear facilities and their infrastructure (built using re-engineering techniques and laser scanning);
  • 2D diagrams and drawings;
  • Facility-attribute models;
  • An archive of documents;
  • A system for collecting radiation exposure data from fixed-position radiation detectors and portable devices collecting radiation data on-site.

TURBINE HALL DISMANTLEMENT PLANNING

In practice, the above techniques were applied to planning the dismantlement of a turbine hall at Beloyarsk NPP (Fig. 2). The results obtained are the following:

  • Planning and justification of the dismantlement were substantially simplified (using 3D models) making it possible to generate an effective dismantlement procedure;
  • The amount of radioactive waste to be arisen from the dismantlement was estimated using 3D models;
  • 3D simulation models were used as personnel training tools animating the dismantlement procedure and visualizing the radiation exposure data measured by gamma- scanners.
Fig. 2. Beloyarsk NPP decommissioning planning
Fig. 2. Beloyarsk NPP decommissioning planning

SIMULATION MODEL

A simulation model deals with the virtual reality simulating processes the way they would occur in reality. To do the simulation, the model involves 3D graphics and information about physical parameters of the objects being modeled. The simulation model identifies and highlights collisions the objects may have.

Fig. 3. Reactor dismantlement planning
Fig. 3. Reactor dismantlement planning

Such kind of simulation system has been used to verify the efficiency of the dismantlement procedure for “AMB-100” and “AMB-200” reactor cores (Fig. 3). Due to the number of accidents occurred in the past, the graphite stack now contains spent nuclear fuel spills and damaged graphite bricks, either cracked or clustered.

The most crucial process of the dismantling project was verified, the process being a layer-by-layer disassembling of the graphite stack by a remotely controlled robot. All dismantlement operations were to be done inside a specific dome erected over the reactor.

The specifics of the disassembling process are to:

  • Simulate the interaction of the obj ects (graphite stack, dome, robots and robotic tools);
  • Control the dismantlement the way the process is controlled in reality (using the simulator’s control panel and observing the entire scene through available video cameras);
  • Adjust the initial situation of the simulation (possibility of selecting on each layer the graphite blocks with a certain type of damage);
  • Maintain a simulation records database (including records classification and ability to attach key event marks to the records).

The simulation model allowed bottlenecks of the dismantlement to be identified. Corrective actions were proposed. The bottlenecks, as identified, include:

  • Robotic arm ’s tools replacement;
  • Video cameras positioning to observe the dismantlement;
  • The dome's floor configuration.

CONCLUSION

The experience in applying information technologies to planning the nuclear facilities decommissioning shows that such technologies are capable of improving safety, predictability and efficiency of the dismantlement activities as well as provide the future generations of specialists with relevant and reliable information they will need to deal with the dismantlement of the nuclear facilities that are shut down now and safely awaiting decommissioning.


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