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In response to the fracture of the secondary
system piping at Mihama Unit 3, the Kansai Electric Power Co., Inc. (Kansai
Electric) is now inspecting its nuclear power plants by sequentially shutting
them down in a carefully planned manner, in order to investigate the causes
of the accident and to develop immediate measures. Following the inspections,
Kansai Electric today confirmed the integrity of Mihama Unit 2*, Takahama
Unit 2 and Ohi Unit 4, and is taking the following actions.
Immediate Actions to Be Taken (Refer
to the attachment for details.)
1. Assurance of industrial safety
2. Organizational reform
- Strengthening the organization of
the Nuclear Power Division
- Strengthening the system of notifying
Fukui Prefecture
3. Stricter management of the secondary
system pipe thinning (establishment of a proactive management system)
- Improving the secondary system pipe
thinning control card
- Reviewing the thinning controlling
tasks of the secondary system pipe
- Change control of the secondary system
pipe thinning control card
4. Establishment of a task force to review
the enhancement of nuclear maintenance functions
Kansai Electric will carefully take these
actions in order to prevent similar accidents and to assure the safety
of nuclear power plants while restoring confidence in Kansai Electric.
* The integrity of two sections of the
secondary system piping at Mihama Unit 2 had already been confirmed through
the application of the "note" in the technical standards of
thermal power generating facilities when Kansai Electric evaluated the
wall thickness of the relevant sections in September 2003. However, considering
the Nuclear Industrial Safety Agency's opinion against the application
of the "note" in evaluating the wall thickness, we evaluated
again using the actual values of the relevant material, without relying
on the method used in September 2003. The result showed that there was
no safety problem. Nevertheless, we will replace these piping facilities
to reassure the local citizens.
(Attachment)
Immediate Actions to Be Taken in Relation
to the Fracture of Secondary System Piping at Mihama Unit 3
1. Assurance of industrial safety
- In principle, Kansai Electric will
not initiate preparations for the coming periodical inspection during
operation of reactors until the integrity of the secondary system piping
has been confirmed. All possible accident prevention measures, including
wearing fire retardant clothing, will be taken where necessary.
- 2. Organizational reform
- (1)Our president will take overall
charge of the Nuclear Power Division, and will take the initiative to
investigate causes of the accident and develop measures to prevent recurrence.
(2)We will appoint a senior engineering official to be resident in Fukui
Prefecture to appropriately deal with engineering issues.
- 3. Stricter management of the secondary
system pipe thinning
- (1) Improvement of the secondary system
pipe thinning control card
- Kansai Electric checked skeleton diagrams
(cubic diagrams of piping) against the guidelines for the secondary
system pipe thinning control of nuclear facilities (PWR) (hereinafter
referred to as the "control guidelines") to improve the card by examining
whether the status of sections where thinning control is needed are
entered in the control card.
- (2) Review of the thinning control
tasks of the secondary system pipe
- As for the secondary system pipe thinning
control, heavy reliance has been placed on the contractors concerning
the inspection planning and evaluation of inspection results. Kansai
Electric will be directly engaged in the thinning control in view of
the management guidelines.
(3) Change control of the secondary
system pipe thinning control card
- In order to precisely reflect modifications
of the secondary system facilities into the secondary system pipe thinning
control card, Kansai Electric will review the change control system
and establish the rules of this system. In addition, we will conduct
a periodic review to check that all designated sections are inspected.
- 4. Establishment of the Task Force
for the Enhancement of Nuclear Maintenance Functions (provisional)
- In response to the Mihama Unit 3 accident,
Kansai Electric will establish the Task Force for the Enhancement of
Nuclear Maintenance Functions (provisional). The task force will include
staff from Kansai Electric (including those not involved in nuclear
power) and experts outside the company, and will identify weaknesses
of the current maintenance system as well as consider how to restructure
the system including manufacturers, and how to improve maintenance tasks.
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