TEPCO : analyse de l'accident Fukushima

Description

Analyse de l'accident de Fukushima, Tepco.

Sujets

• Analyse
• The Tokyo Electric Power Company
• Accident
• Fukushima (Fukushima)

Informations

• Publié par: Fil_actu
• Publié le: 29 février 2016
• Nombre de lectures: 10
• Langue: English
• Poids de l'ouvrage: 10 Mo

Extrait

Fukushima Nuclear Accident Analysis Report
















June 20, 2012
Tokyo Electric Power Company, Inc.

?Foreword

TEPCO sincerely apologizes for the extreme anxiety and inconvenience it has
caused to the local residents around Fukushima Daiichi Nuclear Power Station,
the residents of Fukushima Prefecture, and the broader public due to the accident
at the power station.
In particular, TEPCO is deeply apologetic that numerous people have been
forced to continue evacuating even now because of the emission of radioactive
materials due to the accident.

On the path toward management and stabilization of the accident, Step 2
conditions of reactor cold shutdown as defined in "Roadmap towards Restoration
from the Accident at Fukushima Daiichi Nuclear Power Station," released last
December, have been met. Efforts are currently being made to achieve the
Mid-and-Long-Term Roadmap formulated jointly with the central government
aimed at plant decommissioning measures.
Since the accident, TEPCO has been deeply indebted to the government,
various related agencies, vendors and many individuals and organizations, both
domestic and international, for their meaningful support and cooperation.

TEPCO recognizes that it is its social obligation as a party to this accident to
identify its causes and reflect the lessons learned in business administration
policies to prevent recurrence of a similar accident. Last June, the company set
up an internal Fukushima Nuclear Accident Investigation Committee and has
since been moving ahead to impartially and thoroughly investigate and examine
the accident.
On December 2, 2011, the results of investigations completed by that time and
countermeasures to address the causes and recurrence prevention mainly
regarding equipment were summarized and released as the Interim Report.
Subsequently, information was gathered by conducting hearings and interviews
with concerned parties, checking records, and confirming the field to the extent
possible focusing on items that are especially important to learn as many lessons
as possible from this major accident that resulted in reactor core damage. This
included whether safety-important facilities functioned even after the earthquake,
how data and understanding of conditions of equipment were collected under the
stressful conditions of total loss of power in the field, whether there were mistakes
made in the accident response operations, and whether the chain of command
including the headquarters functioned properly. Further investigations were
conducted to objectively examine event progression assessment results using
collected data and an analytical methodology.
Furthermore, items not covered in the Interim Report have been investigated
and examined, such as initial support of the power station when the accident
occurred, information disclosure, evaluation of radiation control conditions, and
release of radioactive materials.

The results of these investigations have been organized and compiled into this
Fukushima Nuclear Accident Analysis Report.
Based on the facts identified through investigation, this report provides detailed
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?descriptions regarding past and current efforts toward nuclear safety, the
earthquake intensity, tsunami height and their impact on facilities, accident
responses that were taken, and the facility and administrative countermeasures
developed based on the lessons learned.
As a party to this accident, it is the obligation of TEPCO to accurately convey in
detail the facts concerning what happened inside and outside the power station;
what the people involved thought, what judgments they made, and what actions
they took as the accident progressed; and how initiatives were taken toward
securing nuclear safety. Thus, the company has been striving to clarify such facts
to the full extent.
Also, in compiling this report, the Nuclear Safety and Quality Assurance Meeting
Accident Investigation Verification Committee, which is made up of external
experts, was consulted. In addition to reflecting the committee’s “opinions” when
releasing the Interim Report, it also provided various objective advice from the
perspective as experts and as a third party.
This report was developed with a focus on what needs to be done to ensure
nuclear safety. The lessons learned and self-critique will be reflected in the
administration of operations moving forward. Furthermore, it is hoped that this
report will contribute to the improvement of safety at plants both domestic and
abroad and that it is read widely by the broader public.

Once again, TEPCO is keenly aware of its responsibility for the accident.
TEPCO will thoroughly enforce safety first in its business operation in order never
to bring about similar situations again, and will steadily proceed with mid- and
long-term endeavors toward the decommissioning of reactors at Fukushima
Daiichi Nuclear Power Station.

Chairman of the Tokyo Electric Power Company, Inc.
Fukushima Nuclear Accident Investigation Committee
Masao Yamazaki
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?Objectives, Framework and Status of the Accident Investigation

1. Objective
As the party concerned in the accident, to clarify causes of the accident by
investigating and verifying facts, and to incorporate the lessons learned into future
business administration.


2. Framework
(1) Fukushima Nuclear Accident Investigation Committee
?? (Committee members)
Chairman: Executive Vice President Masao Yamazaki
Members: Executive Vice President Masaru Takei
Managing Director Hiroshi Yamaguchi Yoshihiro Naito
General Manager of Corporate Planning Department
General Manager of Engineering Department
General Manager of the Corporate Affairs Department
General Manager of the Nuclear Quality Management Department
Total: 8 members

(2) Accident Investigation Verification Committee
A committee consisting of external experts was established under the Nuclear
Safety and Quality Assurance Meeting as an advisory board to provide comments
from a technical and independent point of view on the investigation results compiled
by the Fukushima Nuclear Accident Investigation Committee.

(Committee members)
Chairman : Genki Yagawa (Professor Emeritus, University of Tokyo)
Members: Yuriko Inubushi (Vice Chair, Consumption Science Federation)
Takeshi Kohno (Professor, Keio University)
Yoshihisa Takakura (Director, Tohoku Radiological Science Center)
Nobuo Shuto (Professor Emeritus, Tohoku University)
Hideki Nakagome (Attorney at Law)
Masao Mukaidono (Professor, Meiji University)

3. Method
(1) Fukushima Nuclear Accident Investigation Committee
The following investigations and verifications were carried out:
Manuals related to this accident, such as the nuclear operator Operation Plan
for Disaster Preparation and various operating procedures in use since before
the accident, were examined and checked.
Earthquake and tsunami data collected at the time of this accident, charts
showing plant behavior, data on alarm records, and other records of plant
parameters collected, as well as daily operating journals recorded at the time of
the accident, white boards, and various other records were examined and
checked.
Analytical assessments using data collected at the time of this accident such as
the tsunami inversion analysis, seismic response analysis, and core damage
analysis.
Field survey studies were conducted on major indoor and outdoor facilities by
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~?~????~?~????TEPCO employees and robots.
Fact-finding investigations by interviews and various records.
(Fact-finding was performed via interviews with a total of 600 people mostly
consisting of disaster response personnel at the power station and comparison with
various records.)

(2) Accident Investigation Verification Committee
Explanations from the Fukushima Accident Investigation Verification Committee
were verified mainly on the following points:
Are the investigation and verification methods proper?
Are the facts based on objective evidence? Are the investigations in keeping
with the progression of the event, and not from a retrospective point of view?
Are the details of the investigation appropriate?
Are the explanations easy for third parties to understand?
In every meeting of the Verification Committee, in addition to members of the
Fukushima Accident Investigation Committee, the site superintendents of
Fukushima Daiichi Nuclear Power Station, Fukushima Daini Nuclear Power Station,
and Kashiwazaki-Kariwa Nuclear Power Station also attended.

4. Committee meetings
(1) Fukushima Nuclear Accident Investigation Committee
June 11, 2011: 1st Meeting of the Fukushima Nuclear Accident Investigation
Committee
Summary of Fukushima Nuclear Power Stations, the conditions of the
earthquake and tsunami and conditions of damage caused by the earthquake
and tsunami
July 26, 2011: 2nd Meeting of the Fukushima Nuclear Accident Investi