DS555 - Safety Assessment for the Decommissioning of Facilities

Status: STEP 3

Revision von WS-G-5.2
Ex DS376 

Beteiligte IAEO-Komitees: WASSC, RASSC, NUSSC

Specific Safety Guide

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Background Information

The Safety Guide WS-G-5.2, Safety Assessment for the Decommissioning of Facilities Using Radioactive Material, published in 2008, provides recommendations on safety assessment for all phases of decommissioning. This document ensures that

1. safety aspects are considered in the selection of the decommissioning strategy, in the development of a decommissioning plan and in the elaboration of details of associated decommissioning activities and
2. exposures of workers and of the public are kept as low as reasonably achievable (ALARA) and do not exceed the relevant dose limits or constraints.

In addition, WS-G-5.2 provides recommendations on the application of a graded approach, radiological hazards identification and control, defence in depth, application of the optimization principle in safety and on other key topics relevant to safety assessment during decommissioning.

WS-G-5.2 is recommended for revision due to several significant updates in General Safety Requirements publications and in Specific Safety Guides. For example, in GSR Part 6, Decommissioning of Facilities (2014), entombment is no longer considered a decommissioning strategy for facilities with normal operational history. The two Specific Safety Guides SSG-47, Decommissioning of Nuclear Power Plants, Research Reactors, and Other Nuclear Fuel Cycle Facilities, and SSG-49, Decommissioning of Medical, Industrial, and Research Facilities, were published in 2018 and 2019, respectively, providing details, which had not been considered in WS-G-5.2. In addition, over 80% of the references used in WS-G-5.2 are outdated or superseded.

Furthermore, since 2008 many decommissioning projects have been completed or are nearing completion, providing practical experiences on aspects related to safety assessment for the decommissioning of facilities. This experience, together with revised IAEA recommendations is not currently reflected in WS-G-5.2.

In summary, the objective of the revised Safety Guide is to provide recommendations on the development, revision, and review of safety assessments for each phase of decommissioning, which is aligned with the currently valid Safety Requirements and related Safety Guides, and which reflects the latest knowledge and experiences from Member States. Key benefits include the alignment of decommissioning strategies with GSR Part 6, the implementation of a planned exposure situation (dose constraints and risk constraints) during decommissioning (GSR Part 6, GSR Part 3) and improved recommendations on managing non-radiological and radiological risks. The revision will address the safety challenges of aging infrastructure in long term decommissioning projects, considering factors such as climate change, knowledge preservation, and degradation of structures, systems and components (SSCs). Additionally, this revision will provide more recommendations on the implementation of a graded approach to safety assessments, provide practical examples, and clarify the roles of regulatory bodies and operating organizations.