Nuclear Regulation Authority (NRA) implemented a “Call for Scientific
and Technical Comments for the Draft Report on the Application for
Permission to Alter Installed Kyushu Electric Power Company (Kyushu
EPCo) Sendai Nuclear Power Station Units 1 and 2 Power Generating
Nuclear Reactors” from July 17 to August 15, 2014. More than 17,000
public comments were submitted, but the citizens' opinions were ignored
in the NRA's decision to evaluate the Sendai reactors as passing the
new safety requirements.
This was an important
call for public opinions in the moves to prevent the restart of the
Sendai Nuclear Power Station, and CNIC also submitted comments. Here we
summarize the main comments submitted by CNIC.
1. Negligent screening
Under the former nuclear power administration system in Japan, the
Nuclear and Industrial Safety Agency (NISA) existed under the Ministry
of Economy, Trade and Industry. NISA was responsible for screening
nuclear reactor construction and alteration permit applications and had
the power to approve such applications. At the same time the Advisory
Committee on Reactor Safeguards (ACRS) of the former Nuclear Safety
Commission (NSC) also carried out double-check screenings on
applications. However, this has not been carried out in the current
inquiry even though the ARCS still exists under the NRA.
Until now, when verifying the validity of the analytical materials
submitted by power companies, the Japan Nuclear Energy Safety
Organization (JNES) also carried out its own analysis as a part of the
screening process. However, this has been limited to a partial analysis
in the current screening “because we are validating (some of the
materials) by a separate analysis” (April 3, NRA Chairperson Shunichi Tanaka in
reply to a question in the House of Representatives special committee
on the study of nuclear power issues).
This deficiency in the screening system is an extremely serious issue.
The NRA should have crosschecks carried out by both organizations.
In addition, the “guarantee of peaceful use” of nuclear materials, as
in the past, has been confirmed only through a formalistic check that
assumes the materials are for use in commercial power generation and
that there is no change in the policies of storage and reprocessing of
spent nuclear fuel. Japan’s nuclear materials, however, especially the
amounts of plutonium in storage, have aroused strong international
concern. Since the NRA is carrying out screening for the first time, we
think that it should indicate a direction toward reform that would
result in the implementation of a more meaningful screening process.
As well as the above, there are also numerous statements in the report
which simply accept the viewpoint of the applicant (the power company),
and with regard to human-induced accidents (so-called ‘terror’
incidents) there are many instances where insufficient consideration is
notable. We feel that these matters should be given more substantive
2. Probabilistic risk assessment (PRA)
The “Interpretation of Regulations Stipulating Standards for the
Location, Structure and Equipment of Commercial Power Generating
Nuclear Reactors and their Auxiliary Facilities” requires that the
accident sequence group (the combination of occurrence of contributing
factors and the loss of the various safety functions that lead to
reactor core damage, etc.) should be assessed by the use of probabilistic risk
assessment (PRA) and other methods. The applicant has used PRA to carry
out the assessment and the NRA has judged this assessment as
appropriate. However, the Recommendations for Autonomous and Continual
Safety Improvements in Nuclear Power, published by the Ministry of
Economy, Trade and Industry (METI) Advisory Committee for Natural
Resources and Energy’s Working Group on Voluntary Efforts and
Continuous Improvements of Nuclear Power on May 30, 2014, points out
that “PRA, especially with respect to external factors, has thus far
not necessarily been put to use in an active manner in Japan.”
On the premise that all nuclear power businesses position PRA as a part
of their risk management programs, the same Recommendations suggests
several procedural reforms for quality improvement, but we can see no
evidence that these have been referred to in the drafting of the report.
Thus both experience of the implementation of and screening for PRA are
shallow, and knowhow concerning implementation and screening are
In addition, the NRA takes single equipment failure as the premise, as
in the past, assuming only a concomitant loss of power, but this is
inadequate. We think that a probabilistic calculation that fully
incorporates the simultaneous failure of multiple pieces of equipment
(common cause failures) should be required.
The applicant altered the reference seismic motion from 540 cm/s2 to 620 cm/s2
in the screening panel meeting held on March 5, 2014. This alteration was
said to have been “evaluated by the NRA member responsible as ‘Kyushu
EPCo has a high level of awareness’” (Mainichi Shinbun, July 16, 2014),
but it was also reported in the Yomiuri Shinbun of March 14, 2014 that
“Kyushu EPCo said that ‘If we oppose everything, the restart will be
delayed’ (top official) … and regarding the hike in the reference
seismic motion, (the official) said that ‘in a sense, some parts were
raised by a horrifying amount.” This alteration thus appears to have
been the result of a profit-and-loss calculation on the part of the
applicant, and is neither scientific nor meaningful from the viewpoint
of constructing a culture of safety.This is exactly the same as the
“attitude of attempting to seek out the minimum values that will fulfil
the new standards” (by NRA) that was criticized in the “Current
Assessment of the State of Ohi Units 3 and 4” in July 2013.
In addition, of the 16 earthquakes required by the NRA, the applicant
excluded the top two earthquakes, citing differences in geological
structure. However, this should not be accepted since, based on the
2010 Nationwide Seismic Motion Forecast Map, the reference seismic
motion should be set at M7.1 as the baseline for the “greatest
magnitude of an earthquake for a land area where the seismic source
fault cannot be easily specified in advance.”
|Volcanoes in the region of Kyushu EPCo Sendai Nuclear Power Statio
A Cumulative volume-time diagram1, from which the frequency of
eruptions can be deduced, can be drawn up with a certain degree of
confidence if eruptions are repeated frequently and are observed, but
when only extremely poor observational records are available, the
method is not reliable. The applicant prepared an average diagram
for the five volcanoes that have shown Ultra Plinian2 eruptions in the
Quaternary Era (the period from roughly 2,600,000 years ago to today)
claiming that the eruption occurrence risk was low, but this is
exceedingly unscientific and should not be adopted as evidence in favor
of a restart.
The applicant has also set up countermeasures against the potential
accumulation of volcanic ash from eruptions of Sakurajima, but this not
set up in a way that matches with forecasts of the timing of eruptions.
At the same time, the ability to predict the timing of eruptions is a
premise for Ultra Plinian eruptions, for which countermeasures are very
difficult to establish. It is contradictory to accept that eruption
forecasts are difficult to make with regard to cases where
countermeasures can be taken and that it is possible to deal with
situations using forecasts in cases where countermeasures are not
possible. We believe Ultra Plinian eruptions should also be treated as
Additionally, since it is also conceivable that magma could accumulate
rapidly over a period of around ten years, a plan should be submitted
stipulating that when the stage is reached where monitoring shows the
applicant should begin to take countermeasures (GPS expansion
5cm/year), the nuclear reactors should be stopped and the process to
remove nuclear fuel set in motion.
The evacuation plan was one issue that was not considered in the
current screening, and since the NRA has already prepared a guideline
on countermeasures for nuclear disasters, it is irresponsible that
there should be no screening to test for compliance with the guideline.
The applicant claims that “the possibility of the occurrence of a steam
explosion is exceedingly small,” and the NRA has judged that this claim
is “reasonable.” However, the occurrence of an explosion involves a
large number of factors, such as the proportion and uniformity of
contaminants. If the conditions for an explosion exist, then there is
the potential for an explosion to occur quite easily, and therefore it
should be a requirement that the possible occurrence of steam
explosions be taken into account and countermeasures be taken against
The applicant has cited a management review as part of quality
assurance, but the idea that safety measures should not prioritize
economic efficiency over safety is one of the important lessons of the
Fukushima Daiichi Nuclear Power Station accident. We believe it is
necessary to devise a process whereby the conflict between safety
measures and management issues can be resolved.
Further, a large number of other deficiencies are seen in various parts
of the report, including worker's radiation exposure at the time of accidents,
measures for groundwater issues, the reliability of measuring
instruments, the problem of extreme aging of facilities, and so on.
8. Upcoming procedures
Following the end of the period for public comments, having received
approval for the construction plan and changes in the safety
regulations, the procedures call for a pre-operational inspection of
the installations and improvements that have actually been implemented.
The approval of the governor of Kagoshima Prefecture, where the Sendai
nuclear plant is located, and the mayor of Satsuma Sendai City, as well
as the assemblies of both the prefecture and city, are also required.
Finally, calls for comments by administrative government agencies are
of two types, one which is based on the Administrative Procedure Act
and one where the agency implements the call at its own discretion. The
call for comments described in this article is of the latter type. In
the future, it will be necessary to maintain vigilance with regard to
whether or not public comments are appropriately called for in the case
of new standard compliance screenings for other nuclear power
(Hajime Matsukubo, CNIC)
1. A chronological
chart of a volcano’s cumulative discharge showing cumulative discharged
material on the Y-axis and time on the X-axis.
2. A catastrophic eruption in which underground magma rises to the surface in a single burst.
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