Regular Diet Meeting held
On Tuesday December 10, 2013, the 27th regular Diet meeting was held in meeting room no. B103 of the House of Councilors Hall, with 45 attendees.
Firstly, Ms. Hiroe Makiyama, member of the House of Councilors, Democratic Party, spoke of “Over the Diet session” on the struggle in an adoption process of the committee or the Act on Protection of Specified Secrets and 2 memoranda on questions addressed to the cabinet regarding the Fukushima Daiichi Nuclear Power Plant.
Since then we went on to a discussion on our predetermined main theme “what should we of SVCF do right now?” At the beginning, Director Yoshio Hirai, introduced a progress report on the problem presentation, which was not fully deliberated due to a limited time in the previous Diet Meeting (October 24), and its review session, which was held separately on November 1.
Director Kunio Ito followed and presented a study titled “Selling Point of SVCF” and Vice President Kazuko Sasaki introduced views and opinions submitted during the above period by SVCF members. This discussion continued for one and a half hours.
The focal topics were cooperation with other voluntary organizations, contact with international research and development organizations for decommissioning stricken reactors, establishment of a strategic base in Fukushima prefecture and of a particular section to secure financial means, review for a distinction between “essential” and “collateral” activities, and so forth. One of the most heated issues concerned what kind of body should handle the clean-up work for the Fukushima Daiichi nuclear power plant accident.
In short, the bottom line in order for the SVCF engagement in actual work should be either in a national project or as part of TEPCO’s multi-layered subcontracting system, if there were suitable work for seniors.
A Diet meeting is not a legislative organ but a forum for free discussion among members. Though we don’t have to hurry up in solving the problem raised here, this would be greatly helpful for reviewing and considering SVCF activities.
At the meeting, Mr. Hiroshi Sakurai, member of the House of Representatives, Liberal Democratic Party and Mr. Katsutaka Idokawa, former mayor of Futabamachi in Fukushima prefecture visited and gave their greetings.
F1 Watcher Report (November 2013)
1. Cooling reactors
TEPCO’s announcement: We have acknowledged maintaining the cold shutdown status. Nitrogen gas is being permeated in the upper part of the pressure suppression chamber to reduce the risk of hydrogen explosions. In order to reduce the burden on the water processing system, as one of possibilities to reduce an amount of water influx in reactors, an air cooling method is under consideration instead of the present water cooling method for the purpose of cooling spent fuel debris.
Watcher’s view: At present it is too early to plan the alteration since the whereabouts and range of scattered debris is uncertain.
2. Retained water processing
TEPCO’s announcement: We have examined a new installation of desalinization apparatus in the building to help reduce the length of water recycling loop. 4 estimations were simulated to keep track of the process of the amount of contaminated storage water. Every case reports salty water, which is free of beta ray nuclide eliminated by Advanced Liquid Processing System, would occupy 70 to 90 percent of the total storage capacity in late 2014. If an underwater bypass facility and a sub drain activation were not provided (in case 3), a concrete levee surrounding the tank yard could be raised against leaks from tanks and a radar perception water gauge would be applied in preparation for more careful monitoring to the storage volume, which would surpass eight hundred thousand cubic meters in the first half of 2015. The present drainage from the tank yard would be channeled into the port and a continuous monitoring system would be installed. As for the Advanced Liquid Processing System, rubber lining and sacrifice anode plates to check corrosion resistance would be used against corrosion in tanks of the C line and adsorption towers. After mid-December, 3 lines are scheduled to run again serially in the contaminated water processing cycle.
Watcher’s view: It seems reasonable to install a contaminated water processing system in 1 to 3 separate lines. It is an absolute necessity that ALPS will run in a stable and continuous mode, however, the condition appears to be uncertain in the future. It should be planned out that the storage capacity is expanded for more than eight hundred thousand cubic meters.
3. Spent fuel
TEPCO’s announcement: Spent fuel removal from the cooling pool began on December 18. (Estimated completion in the end of 2014) From November 18 to 22, 22 unused fuel rods were transferred to the common cooling pool and we estimated a series of work. Consequently, we preferentially started spent fuel removal on November 26.
Watcher’s view: There is no remark about the risk control.
TEPCO’s announcement: Indoor work for an inspection of PCV repair in the reactor building one floor is scheduled to begin in 2014. At present, the reactor building inside is under high radiation. It is impossible for service personnel to work for long periods there, so unmanned heavy industrial machine is remotely controlled for debris removal to reduce the radiation toward the environmental improvement.
“What is the problem of “the flange type tank?”
In SVCF, we have our “Nuclear Power Plant Watchers Team” to study and analyze the progress of the accident clean up activity of the Fukushima Daiichi Nuclear Power Plant. On December 11, the team’s regular study meeting was held in SVCF Takinogawa Office. An editorial member of SVCF had an interview with Mr. M, cooperative member of the Team. Some points of the interview are as follows.
Editor: Please give us more details on the tank that caused contaminated water leaks, described in the NPP Watcher Monthly Report of this month (whole text is on the SVCF website).
M: One tank in the tank group called H4 area has leaked. As a result of overhaul inspection, the leakage point has been estimated; however, there was some description that made me worry very much. This tank is of the so called flanged type that is made of steel plates joined and clamped by bolts and nuts. The bolts have loosened.
Editor: From the very beginning, SVCF President Mr. Yamada pointed out “It is ridiculous to use flange type tanks instead of welded tanks for retaining contaminated water. It will certainly leak.”
M: That’s right, and the problem is not only loosened bolts at the leaking part. Although the clamping torque of the bolt was set at 950 N/m (95kg force is multiplied with 1 meter of the spanner length) at the time of assembly, it has degraded down to around 100 N/m to 240 N/m, when it was confirmed, in other words about one fourth of the required value. As for the bolts other than at the leaked part, the average value of the clamping torque was 202 N/m. That means they are not so different from the value at the part which leaked.
Editor: In other words, both clamping bolts at the leaked part and other parts are equally loosened very poorly, aren’t they?
M: Yes, they are. After all, the tank capacity is 1,000 cubic meters, and as much as 1,000 tons of weight is loaded at the tank bottom (diameter of 12 meters and the area of 113 square meters). The bolts are naturally loosened by the pressure. And water leaked from the loosened part.
Editor: In that case, it is possible to leak from somewhere again, isn’t it?
M: That is right. Besides, it is a critical problem, since the bolts are in the place where they cannot be retightened.
Editor: What does it mean?
M: In case of the side surface, the bolts can be tightened up again if they become loose. But the bottom surface of the tank cannot be retightened.
Editor: Is not the bottom surface made of one piece of steel plate?
M: No, it cannot be. Such a large plate could not be carried by a cargo truck. The steel plates are about 2.5 meters wide and five plates are joined and clamped together by bolts.
Editor: Then what kind of measures are they taking?
M: TEPCO has a plan to replace flange type tanks with welded tanks as a priority on those with higher risk of possible leak. However, since it may take a long time to carry out the plan, water-proof caulking to the tank bottom and filling sealing materials in the tank covers are to be applied as a temporary measure. A firm foundation should have been built to buttress each tank, but the bases were not built up properly. Although they say that sealing materials will be poured between the land surface and the tank to prevent hollows, I wonder if it works as expected.
Editor: Do they have other measures?
M: Yes, it is planned to raise a bank surrounding a dam in the tank yard. The bank has been made surrounding every group per 20 tanks, and it is planned to stop the leaked water from the tanks by raising the bank higher. In principle, the amount of water retained in a dam is limited to the equivalent of the volume of one tank per every 20 tanks.
Editor: It means, the dam can retain the water if ever the water leaks completely out of one tank, doesn’t it? However, you said that the bolts of every tank are loose. Does it mean that the water may leak from several tanks at a time if ever water leak happens?
M: That is right, but if they explain that one tankful of water can be retained, people may accept it without reasonable doubt.
Editor: Is it a “corrective action” only for explanation to the general public?
M: As a matter of fact, reports from TEPCO do not lie, but they tend to describe important things lightly, without special emphasis, even though they may have understood that they are important.
Editor: How about the future view?
M: In perspective, if the multi-nuclide removal equipment (ALPS: Advanced Liquid Processing System), begins steady operation and the processed water can be released in the ocean as IAEA suggested, an exit from the tunnel of “the contaminated water problem” may become realistic. Patrol for watching tanks should be carried out carefully and strictly for more than one year until then.
Editor: The role of the nuclear power plant watcher team will be very important in that sense, isn’t it? Thank you.