Code on Implementation and Review of Nuclear Power Plant Ageing Management Programs: 2021（AESJ-SC-P005E:2021）

内容紹介

The “Code on Implementation and Review of Nuclear Power Plant Ageing Management Programs 2021”
was established by the Atomic Energy Society of Japan (AESJ) through discussions in PLM
Subcommittee followed by deliberations in System Safety Technical Committee and then in Standards
Committee. The Code sets forth the method for implementation of ageing management measures to be
adopted by Japan’s electric utilities which are in charge of operation and management of light water
reactor-type nuclear power plants.
For the purpose of this Code, ageing management of nuclear power plants means the implementation
of activities taking into consideration long-term plant operation through evaluation of the effects of
ageing phenomena, which are expected to occur in structures, systems and components constituting a
nuclear power plant, on their safety functions.
In Japan, electric utilities carry out periodic inspections of their nuclear power plants by shutting down
operation at regular intervals in order to ensure safe and stable operation of nuclear power plants. These
inspections are intended to verify the consistency with the technical standards specified in the
“Regulations on the Technical Standards for Commercial Power Reactors and Associated Facilities
(issued by the Nuclear Regulation Authority)”. At the same time the electric utilities are implementing
the maintenance programs for plant structures, systems and components to confirm their integrity,
maintain their intended safety functions and maintain and improve their reliability. In addition, while the
plant is operating, the electric utilities carry out condition monitoring, including trend monitoring, plant
walkdowns and surveillance tests, to identify abnormal indications of plant structures, systems and
components.
The original version of Code on Implementation and Review of Nuclear Power Plant Ageing
Management Programs was issued in March 2007. The original version set forth the method of
implementing ageing management measures for plants operating more than 30 years. Drafting the revised
version started immediately after issuance of the original Code in conjunction with the work toward
establishment of a new inspection system for nuclear power plants. This new version of the Code
specifies the details of ageing management measures to be taken from the early stage of operation, when
the plant marks its 10th and 20th year of operation, and enhances ageing management measures to be
implemented every ten years after a plant marks its 30th year of operation.
AESJ-SC-P005:2008 which was issued in February 2009 includes major changes. First, the definition
of ageing management measures was reviewed and maintenance activities to be conducted to address
ageing phenomena were identified according to the number of operating years to determine the details
of an ageing management program in conjunction with the maintenance program. In addition, “summary
sheet of ageing phenomena” were formulated showing expected ageing phenomena according to nuclear
power plant component based on knowledge obtained by nuclear power plants which had implemented
a plant life management technical evaluation. The summary sheet of ageing phenomena are attached to
this Code as a regulatory requirement and this Code requires electric utilities to perform ageing
management from the early stage of plant operation according to the summary sheet of ageing
phenomena. This Code also includes another attachment which identifies the ageing management
measures to be taken when a plant marks its 10th and 20th year of operation and enhances ageing
management measures to be implemented every ten years after the plant marks its 30th year of operation
by specifying the standardized methods for evaluation of individual ageing phenomena.
The summary sheet of ageing phenomena in AESJ-SC-P005: 2010 (Amendment 1), 2011 (Amendment
2) and 2012 (Amendment 3) include the results of ageing management technical evaluation for the 8
units (i.e., Tsuruga-1, Fukushima Daiichi-4, 6, Hamaoka-2, Tokai No.2, Mihama-1 and Ohi-1, 2) as the
latest knowledge, which were described in the reports submitted to Nuclear Safety Commission of Japan
from November 2007 to the end of October, 2010.
AESJ-SC-P005:2015 includes the following major changes:
・ Incorporating the “Regulatory Guide for the Implementation of Ageing Management Program for
Commercial Nuclear Power Generation Facilities” (issued by the Nuclear Regulation Authority,
December 6, 2013) and lessons learned from the Great East Japan Earthquake, the scope of
components subject to the evaluation and the evaluation period were reviewed and modified, and
descriptions about technical evaluation of plants in a long-term shutdown state, tsunami safety
evaluation and evaluation of the effectiveness of the Assessment of ageing management measures
were added.
・ The findings obtained from the International Generic Ageing Lessons Learned (IGALL) were
incorporated into Attachment (Reference) “List of Ageing Phenomena”.
・ Attachment (Provisions) “Methods for Implementing Technical Evaluation of Ageing Phenomena”
and Attachment (Provisions) “Method for Implementing Seismic Safety Evaluation” were modified
incorporating the latest knowledge.
・ The summary sheet of ageing phenomena included in Attachment (Provisions) was revised to
include the results of ageing management technical evaluation for the 5 units (i.e., Fukushima
Daiichi-1, Fukushima Daini-1, Genkai-2, Ikata-2 and Mihama-2) as the latest knowledge, which
were described in the reports submitted to Nuclear Safety Commission of Japan from November
2010 to the end of October, 2012. In addition, the combinations of component portions and ageing
phenomena, which should be subject to seismic safety evaluations taking into account aging
phenomena, were identified in the Summary Sheet of Ageing Phenomena for each plant component
based on the knowledge obtained by nuclear power plants which had implemented a plant life
management technical evaluation.
The summary sheet of ageing phenomena in AESJ-SC-P005: 2016 (Amendment 1) , 2017 (Amendment
2), 2018 (Amendment 3) and 2019 (Amendment 4) include the results of ageing management technical
evaluation for the 18 units (i.e., Tsuruga-2, Fukushima Daini-2, 3, 4, Shimane-1, Hamaoka-3, Onagawa-
1, Kashiwazaki Kariwa-1, Mihama-3, Takahama-1,2 (including evaluation of the cold shutdown
condition), Takahama-3, 4, Genkai-1 and Sendai-1, 2) as the latest knowledge, which were completed
the examination by Japanese Government from November 2013 to the end of October, 2017.
AESJ-SC-P005:2021 includes the following major changes:
・ The scope of studies for feedback of latest findings and knowledge and operating experience was
modified.
・ Attachment (Provisions) “Method for Implementing Ageing Management Program every Ten
years”, Attachment (Provisions) “Methods for Implementing Technical Evaluation of Ageing
Phenomena” and Attachment (Provisions) “Method for Implementing Seismic Safety Evaluation”
were modified incorporating the latest knowledge.
・ The findings obtained from IGALL and the suggestions in Atomic Energy Association (ATENA),
“Report on Expanding Knowledge on Aging Phenomena for Safe Long Term Operation”, which
was based on the result of comparison of this Code and the report of Generic Ageing Lessons
Learned for Subsequent License Renewal (GALL-SLR) aiming at 80-year operation in the United
States were incorporated into Attachment (Reference) “List of Ageing Phenomena”, and the
Attachment was modified as provisions.
・ Attachment (Reference) “Philosophy for Ageing Management Based on Ageing Phenomenon
Characteristics” to AESJ-SC-P005:2015 was specified as Attachment (Provisions) in this Code so
that the philosophy for ageing management based on ageing phenomenon characteristics can be
applied to change or select the aging management method when it becomes necessary to change or
select aging management methods in incorporating operating experience or the latest knowledge.
・ The basic concept of ageing management from design to decommissioning of a nuclear power plant
was summarized and newly added as Attachment (Reference).
AESJ-SC-P005:2021 includes following Attachments, but the Attachments (Reference) are not an
integral part of the provisions.
Attachment A (Reference): Philosophy for Ageing Management
Attachment B (Provisions): Selection of Ageing Management Based on Ageing Phenomenon
Characteristics
Attachment C (Provisions): Ageing Management According to Summary Sheet of Ageing Phenomena
Attachment D (Provisions): Identification of Ageing Phenomena According to List of Ageing
Phenomena
Attachment E (Provisions): Method for Implementing Ageing Management Program every Ten years
Attachment F (Provisions): Methods for Implementing Evaluation of Ageing Phenomena
Attachment G (Provisions): Method for Implementing Seismic Safety Evaluation