ISO 23467:2020 原子力発電所の配管のアイスプラグ分離 | ページ 2

Foreword

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This document was prepared by Technical Committee ISO/TC 85, Nuclear energy, nuclear technologies, and radiological protection, Subcommittee SC 6, Reactor technology.

Introduction

This document provides terms and definitions for basic concepts of nuclear energy, nuclear technologies, and radiological protection. Terminological data are taken from ISO standards developed by ISO/TC 85 sub-committees and other technically validated documents.

In the field of nuclear power, when the equipment or pipeline is to be disassembled or removed to overhaul, it is often necessary to isolate the equipment or pipeline. Under normal circumstances, the upstream and downstream of the equipment will be isolated or the internal media will be sprinkled. Taking into account the safety (some reactor systems like the hot trap needs to be filled at any time and care need to be taken as some liquid systems are radioactive) and economy (system mass, sparse for a long time, heavy water degradation, etc.) during the maintenance it is necessary that there will be no isolation equipment or isolation equipment near the equipment or pipeline.

Based on years of practical experience, the development of this document is feasible. At the theoretical level, the relevant literature has been studied and reported on the ice plug isolation technology. In the actual maintenance work, the use of ice plug technology to the pipeline equipment isolation achieve good results. Based on these theoretical and practical experiences, it is recommended that some technical indicators in the process of ice plug operation be standardized.

This document is designed to provide a standardized procedure for on-line isolation through the freezing of the internal medium of the pipeline. This document includes methods for technologies to isolate equipment without isolation facilities by ice plug technology. Standardized ice plug isolation technology will facilitate the maintenance work.

1 Scope

This document specifies requirements for the ice plug technique with liquid nitrogen or dry ice as refrigerant (cryogenic medium) on metal pipes of nuclear power plants. The freezing liquid can be water or water mixture (e.g. boric acid mixture).

This document specifies technical requirements of ice plug generation, formation judgment and removal, measures before, during and after ice plugging and requirements for personnel and non-destructive testing.

The application of the ice plug isolation technique is principally not allowed on cladded pipes or pipes with internal coatings. The application for pressure test is not in the scope of this document and will be qualified separately.

2 Normative references

The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

3 Terms and definitions

For the purposes of this document the following apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

Bibliography