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| Measures to prevent a recurrence of nuclear power
incidents - encouraging a climate and creating a corporate system that assures
compliance |
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Since the end of August 2002, a series of incidents
connected with inspection and maintenance work at our nuclear power stations
have come to light. We would like to offer our sincere apologies for the
inconvenience and anxiety caused, not only to residents living near power
plants but also to all our customers and society as a whole.
Since the autumn of 2002, we have made a pledge of the "Four Commitments" as
a measure to prevent recurrence. All of our employees have been working flat
out to encourage a climate and create a corporate system that assures compliance
with rules and regulations. Now, thanks to the support and guidance of society
(particularly residents living near power plants), as well as the government
and relevant bodies, our measures to prevent recurrence have started to take
effect.
In this Special Feature, we report on measures that are already in motion
or are being practiced.
| Outline of incidents connected with inspection and
maintenance work at nuclear power stations |
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• Of 29 cases for which GE (*) pointed
out inappropriate practice concerning inspection and maintenance work at
our nuclear power stations, it was finally concluded that there were "16
cases in which inappropriate practices were recognized" (Investigation Report
published on September 17th, 2002). These included cases of concealment and
falsifying maintenance records.
(*) General Electric Company. "GE" is used here to refer
to the company as well as its subsidiaries and others.
The Chairman and President accepted overall responsibility for the incidents,
and resigned from their posts as directors of the company. The Executive
Vice-President, who has overall responsibility for the nuclear power division,
also resigned, while other employees connected with nuclear power suffered
demotion, pay cuts or other penalties.
• On investigating, at our own initiative, the company's past
record of inspection and maintenance work, we discovered 8 new cases in which
there were suspicions of inappropriate practice (all of these involved cracks
in nuclear reactor recirculation pipes; announcement made on September 20th,
2002).
• Inappropriate practices were discovered to have been committed
in inspections to measure the level of leakage from the primary containment vessel
at Fukushima Daiichi Nuclear Power Station Unit No.1 (the 15th and 16th periodic
inspections in 1991 and 1992, respectively). These practices included attempts
to reduce the leakage rate by injecting air, and involved several TEPCO employees
(Interim Report published October 25th, Final Report published December 11th,
2002).
Since these practices were in violation of the Law on the Regulations of
Nuclear Source Material, Nuclear Fuel and Reactors (the Law on Regulation
of Nuclear Reactors, etc.), the Minister of Economy, Trade and Industry issued
an order for operations at the Fukushima Daiichi Nuclear Power Station Unit
No.1 to be suspended for one year.
One employee with overall responsibility for inspections who was involved
in this case was dismissed, three others were demoted, two were reprimanded
and three were given severe cautions.
| Motives, background, etc. |
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• For maintenance division employees
involved in inspecting and repairing nuclear power facilities, a matter of
the utmost concern is to complete periodic inspections on schedule and restore
grid power (send power to transmission lines). These employees felt a strong
sense of responsibility to achieve this, as did the management staff in the
nuclear power division.
• This kind of awareness engendered a reluctance to report faults
to the government if this would prolong periods of inactivity in nuclear power
stations. The pressures of severe social reaction to nuclear power faults, and
an over-confidence that we understood nuclear power better than anyone, led to
the mistaken assumption that "things don't have to be reported as long as safety
is not endangered". This in turn led to the situation in question.
• The situation was aided and fostered by inadequate functioning
of the system of checks (such as the system of surveillance of safety management
and quality guarantees for nuclear power) and by a closed organizational culture.
• In many respects, the fact that such practices could not be
prevented, and the problems of the organizational culture that fostered them,
need to be addressed not only by the nuclear power division but also by the company
as a whole.
• It is also a fact, however, that one aspect of the background
to these incidents cannot be solved by TEPCO alone - namely, that the same standards
have to be used for both "design standards" when constructing and "maintenance
standards" when operating.
To ensure that such problems cannot occur again, TEPCO has pledged "Four
Commitments" as a measure to prevent recurrence, and has made a decision,
at a Meeting of the Board of Directors, to exert utmost efforts to this end.
Nuclear Reactor Recirculation System
A forced recirculation system in which cooling water inside the nuclear reactor
vessel is extracted from the vessel and pressurized by a pump before being
returned to the vessel. The reactor output can be increased or decreased
by changing the pump speed.
Periodic Inspection
Periodic inspections, mandatory under the Electricity Utilities Industry
Law, are undertaken by the government once every 13 months with the aim of
keeping the facilities of power stations in safe condition, preventing faults
and ensuring safe operation. The facilities subject to inspection are nuclear
reactors and other related facilities, and steam turbines belonging to power
stations, as defined in the Enforcement Provisions of the Law. Besides these
government inspections, autonomous inspections are carried out by power companies
during periodic inspections, with a view to independent security. Meanwhile,
in an Amendment to the Electricity Utilities Industry Law in December 2002,
autonomous inspections undertaken voluntarily until now are positioned by
law as "Periodic Utility Inspections".
Leakage Rate Tests of Nuclear Reactor Primary Containment Vessels
Tests in which the leakage rate of gas (nitrogen gas) inside the containment
vessel is calculated by measuring time-lapse pressure changes inside the
containment vessel (a sealed steel vessel to enclose radioactive material,
with walls about 20-30 mm thick). During periodic inspections of nuclear
power stations, leakage rate tests are carried out in the presence of a government
inspector.
The Law on the Regulation of Nuclear Source Material, Nuclear Fuel
and Reactors
More commonly known as the Law on Regulation of Nuclear Reactors. It establishes
necessary regulations on the refining, processing, storage, reprocessing
and disposal of nuclear source materials and nuclear fuels, as well as the
installation and operation of nuclear reactors. The aim of this is to maintain
public safety by ensuring that the uses of these materials, fuels and reactors
are limited to peaceful purposes and conducted in planned fashion, as well
as preventing disasters caused by these and protecting nuclear fuels. The
Law also includes necessary provisions on the use of internationally regulated
materials, to ensure compliance with treaties and other international commitments
on research, development and use of nuclear power.
In December 2002, the Law was partly amended in response to problems including
the falsification of autonomous inspection records at TEPCO nuclear power
stations. The amendment made it possible to require reports from companies
conducting maintenance and inspections, as well as to impose increased fines
and incremental penalties for corporations (100 times the normal fine).
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