Ongoing scandals at TEPCO’s Kashiwazaki-Kariwa Nuclear Power Station


TEPCO’s long history of safety mismanagement and Niigata Prefecture’s investigative committees

By Yamaguchi Yukio (CNIC Co-Director)

Tokyo Electric Power Company HD, the largest electric power company in Japan, has ten nuclear power reactors in Fukushima Prefecture, at Fukushima Daiichi and Daini nuclear power plants (10 units, 9,096 MW), and seven that sit astride the border between Kashiwazaki City and Kariwa Village in Niigata Prefecture (8,212 MW), all the electricity from the three nuclear power plants once being supplied to the Tokyo metropolitan area. However, the earthquake that occurred off the Pacific coast of the Tohoku region (magnitude 9.0) in March 2011 triggered an unprecedented accident that resulted the closure of both the Fukushima Daiichi and Daini nuclear power plants. Currently, TEPCO owns only the seven nuclear power reactors in Kashiwazaki-Kariwa. They have been suspended since March 3, 2011, but in December 2017, TEPCO received approval from the Nuclear Regulation Authority (NRA) to restart Units 6 and 7. Further, in September 2020, NRA gave it its rubber stamp of “compliance” (with the new safety regulations) to operate the plant again, and was set to gain the consent of residents.

However, it is not that easy to gain consent from residents. The majority of residents in Niigata Prefecture are critical of nuclear power. In recent years, three earthquakes have struck the area: the Niigata Earthquake (1964, M7.5), the Niigata Chuetsu Earthquake (2004, M6.8), and the Niigata Chuetsu Offshore Earthquake (2007, M6.8). In particular, the 2007 earthquake was the first time ever in history that a nuclear power plant was hit directly by an earthquake.


The Niigata Method

In a nutshell, there is a method of safety management of nuclear power plants called the Niigata method.

In order to deal with the uncertainties associated with science, it is essential for experts to consider matters from multiple perspectives. Conventional expert councils and committees select experts who will make the views of the establishing organization clear, such that the outcome is predetermined and reaches the expected conclusion. To avoid the criticism that this is too blatant, a search is made for committee members who hold critical views. These are so-called gas-venting members.

In the summer of 2002, the notorious “TEPCO coverup incident” occurred. Niigata Prefecture inaugurated a “Technical Committee on Safety Management of Nuclear Power Plants in Niigata Prefecture” (hereinafter, “Technical Committee”) consisting of nine members in February 2003. However, when the Niigata Chuetsu Offshore Earthquake occurred in the summer of 2007, the number of committee members was increased to 14, and 2 subcommittees (six and eight committee members, respectively, for the “Subcommittee on Earthquakes, Geology and Ground” and the “Sub-Committee on Equipment Soundness and Seismic Safety”) were established under the Technical Committee, each of which appointed several experts who are critical of nuclear power. In general, it is difficult to deepen discussions when the number of members of a research committee exceeds ten. If there are too few people, the argument may be biased. In Niigata Prefecture, therefore, the subcommittees hold substantial discussions and the Technical Committee makes necessary additional comments. This is a completely revolutionary mechanism.


Three Research Committees and the Verification Supervisory Committee

A series of scandals at TEPCO and the system of three verification committees stood in the way of what seemed to be a stage set for the current governor of Niigata Prefecture, Mr. Hanazumi, to agree to the restart.

In fact, on September 20, 2020, it was discovered that a person employed at Unit 7 entered the main control room of Unit 7 through the illegal use of an ID card, resulting in a violation of the obligation to protect nuclear material. TEPCO reported this to the Nuclear Regulation Agency on the 21st. However, the Agency did not inform the NRA of this security violation and on September 23, the NRA decided to give a pass mark on all inspections regarding Unit 7.

Early in the following year, on January 13, 2021, TEPCO announced that all safety measures had been completed. Four days later, however, TEPCO announced that some construction work had not been completed, and on March 3, TEPCO announced that there was a fourth location where construction was incomplete. So, what is the truth? Are there any other problems? Many people, including residents of the prefecture, were growing increasingly suspicious of TEPCO repeatedly altering its announcements.

Strikingly, on March 16, the NRA came out with the most serious “red” assessment, the worst on a four-point scale, for the incident involving violations of the protection of nuclear materials. On April 14, the NRA issued a fuel loading ban on TEPCO, the first time that has happened for a commercial reactor, signifying that there was no prospects for the restart of the reactor.

In response to the Fukushima accident, former Niigata Governor Yoneyama established the three-committee verification system and a verification supervisory committee (chaired by Ikeuchi Satoru, a well-known scientist). The three committees are the Committee on the Cause of the Fukushima Nuclear Accident (the Technical Committee), the Committee on the Impacts on Health and Livelihood, and the Committee on Safe Evacuation Methods, and the work of these committees is summarized by the Niigata Prefecture Nuclear Power Station Accident Verification and Supervisory Committee. In sum, the purpose was to clarify the cause of the Fukushima accident from a technical point of view, to examine how the accident would affect the health and livelihoods of the residents of the prefecture, whether a safe evacuation method could be implemented in the event of an accident, and, overall, to prepare for an accident at Kashiwazaki-Kariwa Nuclear Power Station.


Background to the TEPCO scandal

The NRA requested TEPCO to submit a report on the January 27, 2021 incident in which the company lost part of the function of its nuclear material protection facilities. In response, TEPCO submitted six documents on September 22. One of these, the 156-page Verification Report of the Independent Verification Commission on Nuclear Material Protection, has a very interesting graph. The bar graph shows the time taken to restore facilities at a plant after a breakdown, relative to other companies. At TEPCO’s Kashiwazaki-Kariwa plant, times taken were far, far longer – 5 to 50 times longer than for other companies, showing that responses are sluggish. To save on expenses, they have stopped relying on specialized companies, leaving their own technologically unskilled employees to handle problems by themselves.

This is in violation of the second of the September 17, 2020 “seven pledges” submitted when the regulatory committee approved the revised safety regulations. The second pledge states that TEPCO “will make necessary investments in safety measures at the Kashiwazaki-Kariwa Nuclear Power Station.” The third pledge, “The premise of the operation of nuclear power plants is the securing of safety,” was also violated.

A further scandal, which emerged in autumn 2021, regarding damage to the Kashiwazaki-Kariwa Unit 6 foundations, again shows how weak TEPCO’s plant management is. This scandal is discussed in detail in the following article.

Thoughts on the Damaged Foundation Incident at Kashiwazaki-Kariwa NPP

By Takemoto Kazuyuki  (No Nukes! Protectors of Kariwa Village)

It all began with a revelation in a report dated November 2, 2021 titled “Regarding Damaged Piles in the Unit 6 Large-object Carry-in Building” that was presented at a regular press conference with the director of the Kashiwazaki-Kariwa Nuclear Power Station in November and a news report from a press conference on November 10 with Nuclear Regulation Authority (NRA) Chairman Fuketa, who said “Damage is estimated to have occurred due to an earthquake, and an on-site inspection will be conducted.” This new information drew nationwide concern.

There are a total of eight piles (underground columns serving as a structural foundation) under the 11 × 28-meter large-object carry-in building at Unit 6, with four on the right and four on the left. Each of these cast-in-place piles has a diameter of 1.8 meters and length of 12 meters. In the No.8 pile at the southeast corner, seven of the 18 main steel reinforcements are damaged and the other 11 are deformed. All of the other piles show bulging on their surfaces and four have been confirmed to be cracked.

In December, page 1 of  the local newspaper carried an article saying, “1,800 similar piles” had “to be removed without even being checked.” A “cast-in-place pile” is a column created by digging a deep hole in the place where it is to be, standing reinforcing steel rods in it and pouring in concrete to fill it up rather than by driving steel pipes or concrete piles into the ground, as is common. Presumably cast-in-place piles were adopted because the location was adjacent to a nuclear reactor building.

When the damage to the Unit 6 piles was discovered, the corresponding piles at Unit 7 were checked. On June 8, 2020, the large-object carry-in building at Unit 7 had its designation under the “Summary of Application for Approval of Safety Code Changes” from June 2018 rescinded due to its location in a control area for radiation. It was dismantled and rebuilt to include earthquake-proof reinforcements and liquefaction countermeasures. After this was completed, it regained its designation. An explanatory sectional view shows that there are five piles rather than four, which are thicker, and that the walls of the building have been made thicker, but there is no information at all about the type, diameter, length or number of piles.

Kashiwazaki-Kariwa NPP Underwent Largest Tremors Ever to Hit a Nuclear Plant Anywhere

The Kashiwazaki-Kariwa NPS was designed and constructed for basic earthquake ground motion S1 of 300 gals and S2 of 450 gals. During the 2007 Chuetsu Offshore earthquake, the Unit 1 reactor was hit by tremors of 1,699 gals—about four times the limit set by the safety standard. In 2009, to resume operation of the reactors after the Chuetsu Offshore earthquake, Tokyo Electric Power Co. (TEPCO) set the basic earthquake ground motion Ss to 2,300 gals on the Arahama side and 1,200 gals on the Ominato side, and restarted them. The company applied to the NRA on September 27, 2013 for examination of its conformity to the new standards enacted after the Great East Japan earthquake and tsunami of 2011, and passed that on December 27, 2017. The tremors recorded in the reactor buildings during the Chuetsu Offshore earthquake were smallest at the Unit 6 reactor. The fact that the piles were damaged at the Unit 6 reactor, where the tremors were smallest, suggests damage must have occurred at the other units as well.

This only raises suspicions that the Unit 7 building may have been dismantled and removed to cover up damage there.

Liquefaction Damage from 2004 Chuetsu Earthquake and 2007 Chuetsu Offshore Earthquake

The Kashiwazaki-Kariwa NPP was hit by the 2004 Chuetsu earthquake and 2007 Chuetsu offshore earthquake, suffering great damage. To the east of the plant is the village of Kariwa, where the author lives. Kariwa Village has 1,682 households with a population of 4,778 (2015 national census). The table below lists the damage to buildings in Kariwa Village from the Fire Defense Agency’s records of damage.

In my experience with housing reconstruction and subsurface investigations after both earthquakes, what left an impression was prominent damage from liquefaction at the foot of sand dunes and in residential land prepared from former rice paddies. TEPCO announced that there had been liquefaction of the plant’s grounds during the 2007 Chuetsu offshore earthquake, but did not announce liquefaction damage occurring during the 2004 Chuetsu earthquake.

Why Were the Damaged Piles Discovered Now? Are there No Other Issues? Complete Loss of Credibility for National Government’s Inspections and Prefectural Government’s Verification

The damaged piles were ones that had been designed and constructed at the time of the buildings’ construction. Units 6 and 7 received approval for construction as Japan’s first advanced boiling water reactors (ABWR) in May 1991. Unit 6 began operating in 1996 and Unit 7, in 1997. After that, as noted above, the buildings underwent tremors exceeding expectations from the Chuetsu offshore earthquake, but they passed inspection for resuming operations. In 2017 they were also found in conformity with the new “strictest in the world” regulatory standards established by the NRA on the basis of what happened in the 2011 Great East Japan earthquake and tsunami. This means that the national government carried out three rounds of examinations, which the reactors passed, but none of them included effective inspections. The prefectural government also conducted its own verifications, finding no problems. The new knowledge coming to light lately concerning the ground that the Kashiwazaki-Kariwa NPP was built on includes issues with the important anti-quake building and the seawall on the Arahama side. Use of the important anti-quake building as an emergency response center was halted, as it was unable to withstand displacement by tremors. That was in 2017. The important anti-quake building had been built following the Chuetsu offshore earthquake, but a similar building had been completed in Fukushima a half-year prior to the Fukushima nuclear accident and had become a source of pride to TEPCO because it had proven effective in the emergency response at the plant. The one at the Kashiwazaki-Kariwa NPP proved unable to withstand basic earthquake ground motion and could no longer be used.

The piles underpinning the seawall on the Arahama side of the plant, constructed after the Great East Japan earthquake and tsunami (a 10 m high, pile-based, inverted-T retaining wall structure extending 1.5 km) were found to have been damaged as a result of ground liquefaction. An emergency response center constructed at the Unit 3 reactor was damaged by seawater intrusion from the tsunami and could no longer be used. Because of that, its functions were relocated to the Unit 5 reactor building.

Liquefaction-alleviating Facilities for Structures Aside from Kashiwazaki-Kariwa Nuke’s Reactor and Turbine Buildings

Aside from its reactor buildings and turbine buildings, which are located on bedrock, most of the Kashiwazaki-Kariwa NPS could not be constructed on ground that had a confirmable effective load-bearing layer, so spread foundations and piles were used.

After Units 6 and 7 were found in conformity with the regulatory standards, the large-object carry-in buildings were not the only facilities for which TEPCO considered its planned liquefaction countermeasures necessary. It listed 10 types of facilities needing countermeasures. Those were (1) inlet channels, (2) gas turbine generators, (3) filter vents, (4) fuel transfer system ducts, (5) kerosene tank foundations, (6) seawater storage dam breakwater joints, (7) access routes (vehicular roads and walkways), (8) large-object carry-in entrances, (9) service buildings and (10) the back-up power source for the Unit 5 emergency response center. As non-liquefaction layers for these facilities, both spread foundations and piles were used. Six types of countermeasures were planned, (a) lift prevention measures, (b) ground improvement around piles, (c) ground improvement of detrimental liquefying layers, (d) roadbed reinforcement as a countermeasure to road subsidence, (e) dismantling and rebuilding and (f) seismic strengthening of structures. Countermeasure (b) was adopted for the Unit 6 large-object carry-in building in question.

Liquefaction of Grounds during 2007 Chuetsu Offshore Quake

The 2007 Chuetsu Offshore earthquake, which was the first earthquake anywhere to strike a nuclear plant directly, caused damage that rendered the entire grounds of the plant irregular. The roads became wavy and peripheral parts of structures collapsed. On the question of whether the fault had shifted immediately after the earthquake, the cause of this subsidence damage was said to have been that backfilled areas subsided while the areas bearing structures had not, and that liquefaction (at or below the groundwater level) and shaking down (at or above the groundwater level) had occurred. The basic earthquake ground motion was upwardly revised, just as it had been when applying for inspection under the new regulatory standards. However, without taking any measures against liquefaction, after the Chuetsu Offshore earthquake, four reactors were restarted.

Considerations on Building Nukes on Sites Requiring Liquefaction Countermeasures

We live our lives making use of the Earth’s surface, which has places with old, hard ground (mountainous and hilly areas) and soft, new ground (plains). We employ measures such as the use of piles to deal with soft strata so that we can have roads and buildings that we can use on the Earth’s surface. Many of the sites where nuclear power plants are located in Japan are on old, hard ground with structures built directly on bedrock.  As for the Kashiwazaki-Kariwa NPP site, while the reactor buildings and turbine buildings were built directly on the Nishiyama formation (mudstone), the other facilities use pile-foundation structures, with the pile tips serving as the foundation, or spread foundations on non-liquefying strata. Even if the piles are not damaged, the actual state of measures for coping with ground issues at the Kashiwazaki-Kariwa NPS, where liquefaction countermeasures are necessary, such as pile-foundation structures, the ground there has been shown to be unsuitable for siting nuclear power plants.

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