A dispute between Taipower and New Taipei City over interim spent-fuel storage is complicating the shuttering of nuclear power plants.
After the second reactor of the Chinshan nuclear power plant reached the end of its 40-year licensing period last July, the plant became the first of Taiwan’s three nuclear power facilities to enter the stage of decommissioning. The step is in line with the Tsai Ing-wen administration’s goal of transforming Taiwan into a “nuclear-free homeland” by 2025.
Over the next 25 years, the plant – located within New Taipei City along the island’s northern coast – is to be decontaminated, its equipment dismantled and disposed of, and its buildings demolished. The ultimate aim is to restore the site to greenfield conditions, with no trace of radioactivity. The same procedures would apply to the other two nuclear plants – Kuosheng in the north and Maanshan in the south – as their licenses expire.
A dispute between New Taipei City and the state-owned Taiwan Power Co. (Taipower) over the storage of spent nuclear fuel is threatening to delay the process, however. The onsite cooling pools at the Chinshan plant, where spent fuel has been stored for decades, have reached maximum capacity. As a result, the spent fuel in the reactors’ cores cannot be unloaded, as there is nowhere to store it.
In the U.S. and many other nations, spent fuel that has sat in cooling pools for at least a year is transferred for temporary storage to “dry casks.” These huge drums – typically six meters tall and 2.5 meters in diameter and weighing 100 tons when filled – can safely store spent fuel for up to 40 years. Although Taipower built a dry cask storage facility on the Chinshan site, the New Taipei City government has withheld the soil and water permits necessary for it to operate, contending that the construction deviated from the official plan without approval from the city’s planning board.
The city government insists that the issue is one of meeting construction and safety regulations, particularly with regard to soil and water conservation, and has no wider policy implications related to nuclear energy.
“Soil and water conservation is the responsibility of the builder, and any major construction should take care of it,” says Fire Commissioner Huang De-ching. “How can we tell the public that they didn’t take care of the soil and water conservation requirements, but we let them go ahead with the project?”
The New Taipei City government says that the issues it has raised are all fixable and that it is waiting for Taipower to take care of them so that the soil and water permits can be granted and the cask-storage system approved. “If construction is done according to the regulations, we will approve it according to the regulations,” says Huang.
Taipower representatives describe the situation quite differently, however. They say that the city is determined not to accept dry-cask storage within its boundaries and is therefore raising technical demands that are impossible to implement.
“If these matters could be easily fixed, why wouldn’t Taipower take care of them?” asks Edward H.C. Chang, director of Taipower’s Department of Nuclear Backend Management. “The technical side is not the major problem. The political side is the major problem. They want to tell the public that New Taipei City is not going to be the place for dry-cask storage.”
New Taipei City Mayor Hou Yu-ih is maintaining the policy initiated under his predecessor, Eric Li-luan Chu, of refusing to allow dry-cask storage within the city limits without a solid plan in place for permanent disposal of the spent fuel. “What the city government wants is assurance that the spent fuel will not be stored permanently in New Taipei City,” Hou told Taiwan Business TOPICS. “They need to tell us clearly where they will permanently store it, but they cannot say.”
Permanent storage of spent fuel is a global issue that so far has gone without a solution (see the related story). In Taiwan, the Ministry of Economic Affairs is the agency responsible for selecting a site for a permanent repository. It has identified two potential locations: in mountainous Daren township in Taitung County on Taiwan’s east coast and the uninhabited Hsiaochiou islet in the Kinmen archipelago off the coast of mainland China. But final approval is dependent on passage of a local referendum, which both county governments have blocked from taking place.
Meanwhile, the stalemate continues.
Both of Chinshan’s 636-megawatt (MW) reactors were shut down before reaching the end of their licensures. Unit 1 went offline on December 28, 2014, well before its scheduled closure on December 5, 2018, when the handle on a fuel rod assembly broke during refueling. The Atomic Energy Council (AEC) approved the repairs, but the strong anti-nuclear public sentiment at the time kept the reactor from restarting.
Unit 2 ceased operations on June 3, 2017, nearly two years ahead of schedule, when a transmission tower at the site collapsed. The unit was never restarted.
In any case, it would have been necessary to shut both reactors prematurely, as the lack of storage capacity prevented the removal of spent fuel for replacement with fresh fuel. The reactor cores remain fueled to this day.
In this situation, control rods containing boron and other elements inhibiting nuclear reactions are inserted into the reactor core along with the fuel assemblies. Experts say that the continued fueling of Chinshan’s reactors in itself should present no safety concerns.
Managing residual heat is an issue, though. Because the reactors remain fueled, they must be maintained as if in a temporary shutdown, which requires extra personnel and active cooling systems. The fuel in the reactor presents a greater risk than if stored in the spent-fuel cooling pools, due to the smaller size of the reactor cores’ coolant systems, says Yeh Tsung-kuang, director of the Nuclear Science and Technology Development Center at National Tsing Hua University.
In addition, two-thirds of the fuel in the reactor cores is still usable. While less radioactive than spent fuel, it will remain hot longer. In the event that all power to the plant is lost, Taipower would have only one hour to invoke its Ultimate Response Guidelines and flood the core with seawater from mobile pumps on standby.
Fuel is cooler and less reactive when stored in a cooling pool, providing more leeway in any emergency. Removing the fuel from the reactor and placing it into cooling pools would increase safety, while removing the spent fuel from the cooling pools and placing it into dry-cask storage would be even safer.
“All spent fuel should be transferred from wet to dry storage within five years of discharge from the reactor core,” which can be achieved with existing technologies, the Union of Concerned Scientists notes in its report, Safer Storage of Spent Nuclear Fuel.
AEC acceptance last July of Taipower’s plan for decommissioning the Chinshan plant followed approval by the Environmental Protection Administration of an environmental impact assessment.
A key point, however, is that for decommissioning to proceed, the fuel must be removed from the spent-fuel pools. Taipower’s solution of choice remains dry-cask storage, which globally is the most common form of interim storage for spent fuel. It is endorsed by the U.S. Nuclear Regulatory Commission as well as the anti-nuclear Union of Concerned Scientists as a safer option than storage in spent-fuel cooling pools.
Typically, dry casks are steel cylinders that are either welded or bolted closed, providing a leak-tight confinement of the spent fuel. Each cylinder is surrounded by additional steel, concrete, or other material to provide radiation shielding.
Dry casks are intended to “cool the fuel to prevent heat-up to high temperatures from radioactive decay, shield workers and the public from the radiation emitted by radioactive decay in the spent fuel and provide a barrier for any releases of radioactivity, and prevent criticality accidents,” according to a report by the U.S. National Academies of Sciences, Engineering, and Medicine on the safe storage of nuclear spent fuel.
With assistance from the U.S. nuclear engineering firm NAC International, Taipower completed the construction of dry-cask storage facilities at the Chinshan site in 2013, but due to New Taipei City’s objections it was never commissioned. City government representatives say that the area’s dense population and active geology make it a poor candidate for long-term storage of spent fuel.
In any case, additional storage capacity will be needed, as the current facility can accommodate only 1,680 fuel assemblies, while 7,000 will eventually need to be stored. One possible solution to the city government’s objections would be interior dry-cask storage, in which the casks are themselves placed inside a storage facility.
“The public feels that interior dry-cask storage is safer than external dry-cask storage,” notes Fire Commissioner Huang.
Tsing Hua University’s Yeh, however, disagrees that interior dry-cask storage offers any major advantage. He notes that the Fukushima Daiichi nuclear power plant had interior dry-cask storage. The tsunami destroyed the building in which the casks were stored, while the casks themselves remained undamaged. “Now they are no longer doing interior dry-cask storage,” he says.
Taipower also notes that interior dry-cask storage raises issues with heat buildup within the structure.
As negotiations between the city and utility continue, the cost of maintaining the Chinshan reactors in standby mode is eating into the Backend Fund, established to pay for the costs of decommissioning. The fund is financed by a tax on every kilowatt-hour of electricity generated by nuclear power.
The most recent figures released by Taipower showed that the fund had accumulated NT$233 billion (US$7.79 billion), while the total cost of decommissioning all the nuclear plants has been estimated at NT$335 billion (US$11.2 billion).
“New Taipei City has been dealing with this for so long, the central government needs to face this issue,” says New Taipei City Mayor Hou.