SCG56-01

Room:103

Time:May 27 09:10-09:25

Four cases of interference by electric power industry in earthquake risk evaluation
TAKASHI, Soeda1∗
1none

A fair procedure is a key for reliable risk evaluation of earthquakes and tsunamis to judge safety of design and operation of
nuclear power plants (NPP). However, we have found, since 1997, 4 cases of unfair interference by an electric power industry inearthquake risk evaluation by governmental institutes or academic societies.
1. Interference in a guideline for tsunami disaster mitigation formulated by the Japanese Government (1997)
Ministries in charge of tsunami disaster mitigation formulated a guideline for tsunami disaster mitigation (the guideline) in1997. It is stated in the guideline that tsunami assumed in the disaster mitigation planning should be made by taking into accountnot only a maximum experienced tsunami, but also a maximum tsunami supposed by latest seismological studies. Based on
the guideline, the maximum tsunami is estimated to be 8.6m at the Fukushima Diichi NPP, which are much greater than 3.5m assumed by the Tokyo Electric Power Company (TEPCO). The Federation of Electric Power Companies of Japan (FEPC)
tried to put pressure via the Agency of Natural Resources and Energy to the secretariat in charge of the guideline to modify thedescription on the maximum tsunami and stop the public announcement of the maximum tsunami to avoid ”a social disorder.”2. Manipulation to reduce a safety factor for NPPs and ignore tsunami earthquakes from maximum tsunami estimation(2002)In designing NPPs in 1990s and before, only maximum experienced tsunamis were taken into account. There was almost nomargin of safety in NPPs to account for uncertainty in the tsunami estimation. To authorize the tsunami risk evaluation policyby the FEPC, the FEPC set up the Tsunami Evaluation subcommittee in the Japan Society of Civil Engineering in 1999. In 2002
the subcommittee published the Tsunami Assessment Method for Nuclear Power Plants in Japan, in which tsunami earthquakes
are ignored and the safety factor is not introduced. More than a half of the subcommittee is from the nuclear power industry thatcovered all the expense of the subcommittee.
3. Interference in revision of the Regulatory Guide for Reviewing Seismic Design for Nuclear Power Facilities (Regulatory Guide) (2001-2006)
The Nuclear Safety Commission revised the Regulatory Guide in 2006. During the revision process, the FEPC supported
specific committee members to speak for the nuclear power industry. An example is a manipulation on an evaluation period of
active faults. There was an argument that it should be substantially extended to, e.g., 130,000 years. It is written in documents of
the FEPC that ”We will ask the cooperative members to propose an alternative proposal, as a counter to the proposal of 130,000
years. The alternative one should be operationally realistic, feasible, and less influential to present power plants.”
4. Interference in the long-term evaluation of seismic activity (2011)
The Headquarters for Earthquake Research Promotion (HERP) had revised the long-term evaluation of seismic activity in theJapan Trench since 2009. The HERP showed the revised evaluation to the power industry before public announcement on March
3, 2011. The TEPCO requested the HERP to modify the revised evaluation so that repeating occurrence of the Jogan earthquakes
is uncertain. The secretariat of the HERP met the request without consultation with committee members.
The risk evaluation process should be more transparent to get rid of the interference by the industry. Conflict of interest should
also be clarified. When the TEPCO has a meeting with seismologists relevant to regulation of the NPPs, ”technical instruction
fee”has been paid for a long time. While the fund donation and cooperative research with the industry have been disclosed, more
items such as payments for technical instruction, lecture, meal, travel are also to be disclosed. The transparency is necessary for
Earth scientists to be trusted by society.

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SCG56-02

Room:103

Time:May 27 09:25-09:40

Seismological problems in the NRA’s permission for the Sendai NPS: Effects of greatinterplate and intraslab earthquakes
ISHIBASHI, Katsuhiko1∗
1

Emeritus Professor, Kobe University

On September 10, 2014, the NRA (Nuclear Regulation Authority, Japan) granted permission for change in reactor installationof Sendai NPS (Nuclear Power Station) Units 1 and 2 as applied by Kyusyu Electric Power Co., Inc. This was a regulatory stepto grant permission for the basic design of nuclear reactors and related facilities applied from the operator. The applied designand safety features of Sendai NPS Units 1 and 2 were deemed to meet the NRA’s new regulatory requirements.
According to the new regulatory requirements, the ”standard seismic motion” (earthquake ground motion that rarely occurs,
but may possibly occur in service period of the facilities and have a significant effect on the facility) used for the seismic designof facilities shall be formulated as the ”earthquake ground motion formulated with a hypocenter specified for each site” and the”seismic motion formulated without a hypocenter.”
The ”earthquake ground motion formulated with a hypocenter specified for each site” shall be formulated by selecting multiple earthquakes that are predicted to have a significant effect on the site (”earthquakes for investigation”) as to inland crustal
earthquakes, interplate earthquakes and oceanic intraplate earthquakes, and by implementing the evaluation of ground motions
for each selected earthquake for investigation.
Kyusyu Electric Power, however, by referring to the catalog of past destructive earthquakes in and around Kyushu, consideredthat even the largest interplate and intraplate earthquakes did not affect so much the Sendai NPS site and that earthquakes forinvestigation did not need to be selected for interplate and intraplate events.
NRA overlooked this judgment without question and accepted the standard seismic motion, Ss-1 (PGA 540 gals), formulated
based merely on inland crustal earthquakes.
But, the judgment by Kyushu Electric Power using the past earthquake catalog only is very insufficient. Possible and probableinterplate and intraplate earthquakes including the anticipated great Nankai trough earthquake and large intraslab earthquakes insouthern Kyushu are inferred to have considerable effects on Sendai NPS. Therefore, these events shall be selected as earthquakes
for investigation in order to formulate a proper standard seismic motion.
Keywords: Sendai nuclear power station, Nuclear Regulation Authority, permission for change in reactor installation, standard
seismic motion, anticipated great Nankai trough earthquake, large intraslab earthquakes

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SCG56-03

Room:103

Time:May 27 09:40-09:55

Scientific issues in the ban injunction to the Oi nuclear power plant
KOKETSU, Kazuki1∗
1

Earthquake Research Institute, University of Tokyo

The issues of science and technology in the verdict can be summarized as follows: (1) The cliff edge (if ground motion isbeyond this, the plant will lose overall safety) was determined to be 1,260 gal in the stress test. It is impossible to assume nochance of ground motion larger than the cliff edge based on a sound scientific basis. (2) The design basis (if ground motion
is beyond this, S-class structures will lose functional safety) was determined to be 700 gal in the stress test. Ground motion
between 700 and 1260 gal can possibly occur, but any measure may not be applied at the worst because of difficulties in event
grasp, multiple case, training, and so on. (3) The seismic safety regulation does not require structures and facilities of B or C
class to keep functional safety under the design basis ground motion. Therefore, even in a case of ground motion smaller than700 gal, external electricity and main water supply, which are not ranked at S class, have danger to lose functional safety. (4)Because a pool of nuclear waste does not have such a firm confining structure as a pressure vessel for a reactor, it has danger toemit radioactive substances.
Among the above, (1) and (2) are emergencies at the worst, so that science cannot deny the occurrence and also cannot provetheir certain occurrence in the future. On the other hand, (3) and (4) can be thought to have sure danger. When we consider
only (3) because of the lack of concreteness in (4), we find it quite probable for ground motion smaller than 700 gal to occur
and for external electricity to be damaged. In addition, we recall that damage to external electricity was one of causes of theFukushima Daiichi accident, and therefore it can be scientifically correct to assume the Oi nuclear power plant to have danger tosuffer an accident. Furthermore, this point in the verdict suggests the Nuclear Regulation Authority’s decision of keeping external
electricity at B class to be wrong, though two independent routes have been required after the Fukushima Daiichi accident.

Keywords: Fukui district court, Oi nuclear power plant, ban injunction, issue of science and technology

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SCG56-04

Room:103

Time:May 27 09:55-10:10

A guide to JAEE report and its supplement on road map for seismic safety research ofnuclear power plants
KAGAWA, Takao1∗
1

Tottori University Graduate School of Engineering

A report and its supplement by Japan Association for Earthquake Engineering (JAEE) are introduced for information sharing
between researchers of earth science and engineering.
JAEE published a report on road map for seismic safety research of nuclear power plants in 2011 by a research committee
on seismic safety of nuclear power plants. The committee originally planned to complete the report in March 2011. However,
the report was finally published in October 2011 with newly proposed supplement considering severe casualty of the Fukushima
Daiichi Nuclear Power Station due to the 2011 off the Pacific coast of Tohoku earthquake.
The report is useful to know design concept of engineering and to recognize strenuous demands on nuclear politics for theearth science researches.
Keywords: Nuclear Power Plant, seismic safety, Japan Association for Earthquake Engineering, road map

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SCG56-05

Room:103

Time:May 27 10:10-10:40

The role by earth scientists in problems about nuclear power plants
IZUTANI, Yasuo1∗
1

Shinshu University

One of the causes of the severe accidents of Fukushima nuclear power plants during the Great Tohoku Earthquake of 2011 isthat the tsunami hight to design the nuclear power plants was fixed by earth scientists and engineers in spite of their knowledge
on tsunami was very limited. The same problem exists in how to fix the ground motion level to ensure safety of nuclear power
plants, because knowledge on ground motions for future earthquakes is very limited. In the circumstances, the ground motion
level must be fixed by taking into account not only the limited scientific knowledge but also social factors, such as, risk of humanlife and environment, and so on. The role by earth scientists is not to fix the ground motion level but to provide the society with
scientific knowledge and to empower the society so that the society may fix it through discussions among people with various
opinions.

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SCG56-06

Room:103

Time:May 27 10:40-10:45

Discussion
KAWAKATSU, Hitoshi1∗ ; KANESHIMA, Satoshi2 ; SUETSUGU, Daisuke3 ; HASHIMOTO, Manabu4
1Earthquake Research Institute, University of Tokyo, 2 Department of Earth and Planetary Sciences, Kyushu, 3 Institute of Research on Earth Evolution, Japan Agency for Marine-Earth Science and Technology, 4 Disaster Prevention Research Institute,Kyoto
To ensure the safety of nuclear power plants in an earthquake/volcano prone country like Japan, understanding of earthquakes
and volcanic eruptions phenomenon, and predictions of disaster based on it are essential. But the understanding is very limited,and thus predictions of disaster have huge uncertainties. We discuss how this situation should be considered, dealt with andcommunicated among earth scientists, related engineers, policy-makers and the society.

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SCG56-07

Room:103

Time:May 27 11:00-11:15

Insufficient guideline and reviews on the volcanic risks to the Japanese nuclear power
stations
KOYAMA, Masato1∗
1CIREN, Shizuoka University

The 2011 East Japan earthquake and tsunami disaster caused the severe accident of the Fukushima Daiichi Nuclear Power
Station (NPS) and the trust in national nuclear power management was completely lost. The Japanese government newly established the Nuclear Regulation Authority (NRA) in September 2012 and started to make the New Regulatory Requirements forlight-water NPSs (NRR). After nine-months discussion by the working team, the NRR was fixed in July 2013.
The NRR includes a new guideline for considering risks of volcanic eruptions (Volcanic effects Assessment Guide: VAG),
which did not exist before the 2011 disaster. However, the VAG shows no quantitative criteria to prohibit construction of NPS
and thus enables arbitrary interpretation. The VAG also includes unrealistically optimistic views on both long-term and shortterm predictions of volcanic eruptions. The VAG does not show any attention to large uncertainty in long-term estimate oflarge-scale eruptions. Moreover, the VAG explicitly supposes that large-scale eruptions of caldera volcanoes can be predicted
several years before the eruption by monitoring.
In spite of opposition from many volcanologists, the VAG has been adopted for the conformity review of each NPS since July
2013 and the Sendai NPS was first authorized to satisfy the NRR in September 2014 under the condition that the volcanic activities of nearby calderas are always monitored. Although the Sendai NPS, located on the south Kyushu Island, is surrounded byat least 5 caldera volcanoes and was overlain by two large-scale pyroclastic flows for the past 120,000 years, there is no official
damage estimate of nuclear disasters, which can be triggered by large-scale eruption of the caldera volcanoes.
Keywords: nuclear power station, volcanic risk assessment, guideline, conformity review, Sendai NPS, insufficient evaluation

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SCG56-08

Room:103

Time:May 27 11:15-11:45

A suggestion on prediction of very large eruptions and volcano monitoring from the Volcanological Society of Japan
ISHIHARA, Kazuhiro1∗
1Kyoto University

1. BackgroundSome of members of the Volcanological Society of Japan (VSJ) have been involved directly or indirectly in disaster measuresof national and local governments, evaluation of volcanic activity and nuclear energy as a matter of duty or experts. Related to
the 2009 L’Aquila Earthquake in Italy, scientists including a volcanologist involved in a national committee were indicted forthe responsibility of victims due to their misjudgment. This event urged scientists to reconsider how scientists should have to dowith society and administrative problems. In Japan, the Cabinet Office, Government of Japan (CAO) issued “A suggestion on
the disaster measures for large volcanic eruption” in May 2013. In June 2013, the Nuclear Regulation Authority (NRA) issued“Guide on the evaluation of influence/impact of volcanoes on nuclear power plants” . The guide demands enterprises of nuclear
power generation to do volcano monitoring and to get advices of volcanologists in evaluation of volcanic activity: whether verylarge eruption, which may impact on nuclear power plants, occurs or not. To exchange information and opinion on problems of
nuclear power plants and very large eruptions, VSJ set up the committee on problems related to nuclear energy. The committee
summarized results of discussion as “A suggestion on prediction of very large eruptions and volcano monitoring” and presented
it at the general meeting of VSJ in November 2014. The suggestion is placed in Home Page of VSJ to let members of VSJ know
it and to inform of society of the suggestion of VSJ.
2. Main issues of discussion and suggestion
The committee discussed problems related to very large eruptions and nuclear energy, those are, the guide of NRA, the suggestion of CAO, eruption alert operated by Japan Meteorological Agency (JMA), and opinion and information from the membersof committee.
The Guide of NRA supposes that signs of very large eruption is detectable by volcano monitoring and necessary operation on
atomic reactors is completed before eruption. This is opposed to the suggestion of CAO: the research on the prediction of verylarge eruptions and disaster measures has not initiated. In addition, the guide had made without discussion with CAO and JMA.
Problems related very large eruptions including nuclear energy should be discussed at some meetings in which the government
offices participate. The results of discussion are expected to be reflected to the safety measures of nuclear power plants and soon.
Volcanologists should explain the present status on the prediction of eruptions by volcano monitoring including possibility,limitation and uncertainty to the publics and the government offices concerned.
Research on prediction of very large eruptions and disaster measures is an important subject of VSJ and Japan, and should bepromoted. The results should be applied to eruption alert level by JMA and the guide on nuclear power plants.

Keywords: very large eruption, nuclear power plant

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