	Introduction

Comparative Analysis of International Regulatory Systems for Radiological Characterization during the Nuclear Power Plant Decommissioning Planning Phase

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Keywords: Nuclear power plant decommissioning, Radiological characterization, IAEA, NRC

For the decommissioning of a nuclear power plant, radiological characterization assessments tailored to specific purposes are conducted at various stag-es. Although the terminology used by the IAEA and the United States to define these assessments differs slightly, they can be broadly classified into three phases: ‘during the establishment of a decommis-sioning plan,’ ‘during decommissioning,’ and ‘after the completion of physical decommissioning.’

During the establishment of a decommissioning plan, the types of radionuclides present in the target facility, as well as their radioactivity levels and dis-tributions, are predicted. This work serves as a cri-terion for determining not only the timing of the de-commissioning start (immediate or delayed decom-missioning) but also the methods for executing de-tailed decommissioning processes. Furthermore, the results of this properly conducted assessment serve as a significant asset in planning to decommission the target facility economically and safely.

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	Materials and Methods

Although the IAEA published various technical reports and documents regarding decommissioning in the 1980s, it gave little consideration to radiological characteristics. Globally, as the number of nuclear power plants entering the permanent shutdown phase increased from the late 1980s, the need for strategies and objectives for evaluating radiological characteristics was recognized to proceed with decommissioning in a systematic manner, and research was conducted on this.

To this end, a group meeting related to this was held in Vienna in February 1996, and as a result of transnational discussions, a guide [1] on evaluating radiological characteristics when establishing decommissioning plans was developed.

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	Results and Discussion

Figure 1 illustrates the radiological characteriza-tion procedures recommended by the IAEA and those provided by the NRC.

The fundamental difference between the two pro-cedures stems from variations in the possession of decommissioning technology and experience.

The IAEA focuses on guiding countries to secure the necessary technologies for decommissioning in advance. Consequently, it mandates the preparation of preliminary decommissioning plans even during the construction and operation of nuclear power plants.

Figure 1. Analysis of radiological characteristics

In contrast, the United States possesses sufficient nuclear decommissioning technology through exten-sive experience. This experience has confirmed that the radiological impact of decommissioning activi-ties is minimal compared to operational levels. Therefore, the enactment of the Long-Term Reform Act (LTR) in 1996 established a regulatory frame-work for nuclear decommissioning tailored to the realities of the United States.

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	Conclusion

This study compared and analyzed the regulatory frameworks for evaluating the radiological charac-teristics of nuclear power plant decommissioning in the United States, a leading nuclear power nation, and the International Atomic Energy Agency (IAEA).

The IAEA focuses on requirements for safe decom-missioning rather than on a nation's experience or characteristics, and thus includes decommissioning plans in its licensing procedures. In contrast, the United States grants discretion to operators regard-ing decommissioning plans and limits licensing to only the final radiological evaluation prior to site opening, thereby reducing unnecessary require-ments and providing regulatory flexibility.

Since Korea currently lacks experience in nuclear power plant decommissioning, it follows the IAEA's regulatory framework, which requires decommis-sioning plans as licensing documents. However, once decommissioning experience and the expertise of regulatory personnel are secured in the future, adopting a flexible regulatory framework similar to that of the United States could be a viable option.

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Acknowledgments

This study was conducted as part of the nuclear safety research project organized by the Nuclear Safety and Security Commission.

References

IAEA, "Radiological Characterization of Shut Down Nuclear Reactors for Decommissioning Purposes," Technical Report Series No. 389(1998)

NRC, "Technology, Safety and Costs of Decommissioning a Reference Pressurized Water Reactor Power Station," vol.1, NUREG/CR- 0130(1978)