Tokyo, July 19 (Jiji Press)–Japan’s Nuclear Regulation Authority on Tuesday instructed Tokyo Electric Power Company Holdings Inc. to reduce the amount of highly radioactive water inside reactor buildings at its disaster-crippled Fukushima No. 1 nuclear power plant.
The nuclear watchdog also demanded TEPCO lower the water’s radiation levels and consider substantially boosting the number of water storage tanks at the plant in order to lower the risk of the contaminated water leaking out.
Currently, there are tanks only enough to store contaminated water being generated every day mainly due to inflows of groundwater.
Meanwhile, the highly radioactive water inside the No. 1 to No. 4 reactor buildings totaled some 61,600 tons as of Thursday. A lot of tanks would need to be built in order to remove the contaminated water from the buildings.
The highly radioactive water may leak out if tsunami hits the plant again, Toyoshi Fuketa, acting head of the NRA, said, demanding cuts in the amount of the water.
Nov 13 2014
The operator of the crippled Fukushima Daiichi nuclear power plant faces another challenge in its effort to address radioactive water at the complex.
It says highly contaminated water may still be flowing from reactor buildings into adjacent underground tunnels even after a work to stem the flow ended.
The water in the tunnels is believed to be leaking into the sea. Tokyo Electric Power Company plans to pump the tainted water out of the tunnels and fill them with cement.
To prepare for the process, the firm began work in April to stem the flow of radioactive water between the reactor buildings and the tunnels. It involved freezing some of the water as well as plugging the gaps with filler materials.
TEPCO finished the work on November 6th. But workers found that water levels in the reactor buildings and the tunnels are still linked. They note this suggests that the flow of radioactive water between them may not have been stopped.
TEPCO officials say that if the situation doesn’t improve, they may start filling the tunnels with cement even before they finish removing contaminated water.
October 17, 2014
The additional multi-nuclide removal equipment ALPS (advanced liquid processing system), which was installed to help make up for lost time after delays in the utility’s contaminated water processing plan, has so far been working as expected since it started trial operations in September, according to TEPCO.
In the water purifying process, cesium is first removed from the water. Then 62 additional radioactive substances, including strontium, are eliminated using ALPS. The first units of ALPS were set up in March last year.
As of Oct. 14, 355,000 tons of highly radioactive water from which just cesium has been removed is stored in tanks on the plant site.
To reduce risks in the event of contaminated water leaks from the storage tanks, TEPCO also plans to begin operations of an improved version of ALPS in the near future.
Thanks to the newly set up ALPS units and the improved model to be introduced, it is estimated that the radioactive water processing ability of the plant will rise from the current maximum of 750 tons per day to 1,960 tons, according to TEPCO.
at the Fukushima No. 1 nuclear power plant.
But many problems have been reported with ALPS since it first became operational, repeatedly forcing the plant operator to halt its operations. The utilization rate for the system between January and August was just 35 to 61 percent.
Although TEPCO replaced some components of ALPS with improved parts, problems occurred with some replaced components in late September, forcing the utility to suspend operations of some units of the system.
Whereas TEPCO has set a goal of completing the purification of all highly radioactive water stored on site, it would still be difficult to achieve that goal even if TEPCO could operate all the processing systems day and night.
According to a TEPCO estimate made in February, the amount of highly contaminated water should have been reduced to 300,000 tons by about now, but the water cleaning procedure is currently a month behind the original schedule.
To make up for lost time after delays in its water processing plan, TEPCO has worked out a series of additional countermeasures.
Earlier this month, TEPCO introduced new mobile equipment that can eliminate strontium from 300 tons of water a day. The company also announced Oct. 16 that it will start operations by the end of the year of an additional strontium removal system with a daily processing capability of 500 to 900 tons.
Although the water treated with those strontium removal systems alone still needs to be processed with ALPS to eliminate additional radioactive substances, TEPCO officials said the company will temporarily deem such water as being “purified” to achieve its initial goal of completing the processing work by the end of the fiscal year.
Another problem is that the influx of groundwater into reactor buildings is adding 400 tons of highly radioactive water a day.
In June, TEPCO began construction of a 1,500-meter frozen soil wall that will surround the basements of the reactor buildings. The utility intends to start the soil freezing procedure next spring after draining all the radioactive water accumulating in trenches around the reactors.
TEPCO originally planned to drain all 11,000 tons of contaminated water in the trenches, which are directly connected to the reactor buildings, and fill them in by June. But the planned procedures have yet to be completed.
As the trench water draining operation is behind schedule, the Nuclear Regulation Authority has called on TEPCO to seek an alternative way to fill in the trenches as soon as possible.
Whether to use another method or continue the current draining procedure is expected to be determined in early November. To start soil freezing operations next spring, the trenches have to be filled in by January, TEPCO said.
In May, the plant operator began releasing groundwater into the ocean pumped from wells on the mountain side of the nuclear plant before the groundwater can reach the reactor buildings and become contaminated.
Although TEPCO insists that its various countermeasures, including the underground water bypass project, have succeeded in reducing the influx of groundwater by up to 130 tons daily, the estimate lacks a solid basis.
The utility is also considering releasing contaminated underground water accumulating near the reactor buildings into the Pacific after purifying it, but it remains unclear when the company will be able to carry out the plan.
(This article was written by Tsuyoshi Nagano and Hiromi Kumai.)
Source: Asahi Shimbun
September 25, 2014
Kajima Corp. and analysis equipment maker Nikkin Flux Inc. have jointly developed equipment that quickly examines large quantities of water for radioactive cesium.
The box-shaped device, measuring 2.2 meters by 2.7 meters, is expected to be used at interim storage facilities for radioactive soil and debris generated from decontamination work due to the Fukushima nuclear disaster.
The equipment is able to analyze 1,800 times the amount of water that conventional systems can, and at nine times the speed, according to officials of the two companies.
For example, it can measure cesium levels in 3,500 liters of water, equivalent to 18 home bathtubs, in about 20 minutes, compared with existing systems that take more than three hours to analyze two liters of water.
The device was developed using general contractor Kajima’s waste-water processing know-how and technologies owned by Nikkin Flux, a Tokyo-based company.
The two firms also intend to sell the equipment to general waste disposal facilities, the officials said.
Source: Asahi Shimbun
Acting chief Toyoshi Fuketa expressed his opinion at a news conference on Wednesday.
Highly radioactive water flowing into tunnels at the Fukushima Daiichi plant is believed to be mixing with groundwater and leaking into the ocean.
Tokyo Electric Power Company initially planned to freeze some of the contaminated water to stop the flow and allow its removal.
Fuketa said work to freeze the water has been unsuccessful and there may be no choice but to fill the tunnels with concrete.
He said it is not desirable to keep radioactive substances within the plant, and liquefied radioactive substances worsen the situation.
Fuketa said it would be better to seal in the underground water with cement than allowing it to flow into the ocean.
He also said failure to stop the flow of contaminated underground water would prevent freezing of soil and creating a wall of ice.
Nuclear Regulation Authority officials are expected to discuss TEPCO’s idea of plugging the tunnels with cement and removing the radioactive water.