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Useless radiation monitors

March 14, 2016


Half of radiation monitors around Kagoshima plant not up to the job




KAGOSHIMA – About half of the monitoring posts around an active nuclear power plant in Kagoshima Prefecture are unable to detect the high radiation levels that would spark an immediate evacuation of residents.

Of 48 monitoring posts installed within 5 to 30 kilometers of Kyushu Electric Power Co.’s Sendai plant, 22 can only detect radiation levels of up to 80 microsieverts per hour — far lower than the 500 microsieverts per hour that would spark an immediate evacuation. The plant was restarted last year.

The government’s guidelines say residents within a 5-km radius of nuclear plants must evacuate immediately in the event of a severe accident, but that those living between 5 and 30 km of the site should take shelter first and then evacuate if a radiation dose of 500 microsieverts per hour is detected.

A Kagoshima Prefectural Government official said there is “no problem” with its monitoring, because the government will make a decision on any evacuation based on data from nearby devices that can measure high radiation levels, and portable measuring devices can also be used.

But of the 44 portable devices that the government can use, 30 can measure radiation levels of up to only 100 microsieverts per hour. Moreover, the government may be unable to use the devices at the locations it wants to, such as if an earthquake or other natural disaster were to sever roads and disrupt traffic.

The local government installed the 48 monitoring posts ahead of the restart of the No. 1 reactor at the Sendai plant last August, which became the nation’s first unit to be brought back online after stricter safety regulations were introduced following the 2011 Fukushima nuclear disaster.

Meanwhile, a newspaper reported Monday that Kyoto Prefecture has missed its own target for setting up monitoring posts around Kansai Electric Power Co.’s Takahama nuclear power plant in neighboring Fukui Prefecture.

The Asahi Shimbun said Kyoto Prefecture planned to set up monitoring posts at 41 locations, but as of the end of February, 27 monitoring posts were not in place.

This means the No. 3 reactor restarted operations in January without the ability in place to assess fully the fallout from an accident. The newspaper quoted the prefecture as saying it will set up the remaining 27 posts by the end of this month.

Takahama’s No. 3 reactor was halted after the Otsu District Court last week imposed a provisional injunction on its operation.


Useless radiation tools installed for evacuations near Kagoshima plant




Nearly half of the radiation monitoring posts installed for issuing evacuation orders around the Sendai nuclear plant in Kagoshima Prefecture are actually useless for that purpose, The Asahi Shimbun has learned.

In the event of a nuclear accident, evacuation orders are issued immediately when airborne radiation levels reach 500 microsieverts per hour. But 22 of the 48 monitoring posts around the Sendai plant can only measure radiation levels up to 80 microsieverts per hour, according to a survey on the equipment.

The Kagoshima prefectural government installed the monitoring posts in a range of 5 kilometers to 30 km from the Sendai plant before Kyushu Electric Power Co. resumed its operations in August last year. The No. 1 reactor at the plant was the first to be restarted under the Nuclear Regulation Authority’s stricter safety regulations imposed after the 2011 Fukushima nuclear disaster.

An official of Kagoshima Prefecture’s nuclear safety measures division played down the limits of the radiation measuring devices if evacuations must be ordered.

“It will be no problem because we can monitor radiation levels with other monitoring posts nearby or transportable monitoring equipment,” the official said.

However, The Asahi Shimbun’s survey found that 30 of the prefecture’s 44 portable monitoring devices are incapable of surveying radiation levels exceeding 100 microsieverts per hour.

The third and fourth reactors to go online under the NRA’s stricter standards were the No. 3 and No. 4 units at Kansai Electric Power Co.’s Takahama nuclear power plant in Fukui Prefecture.

The Asahi Shimbun found that neighboring Kyoto Prefecture had installed only 14 of the planned 41 monitoring posts in the vicinity of plant at the end of February, after the No. 3 reactor resumed operations on Jan. 29 and the No. 4 unit was restarted on Feb. 26.

The Kyoto prefectural government compiled a plan to install the 41 monitoring posts within the area between 5 km and 30 km from the Takahama plant in line with the NRA Secretariat’s guideline to place them at a distance of every 5 km.

“While we were still deliberating on the locations of the monitoring posts, the plant went ahead with restarting the reactors,” said an official at the prefectural government’s Environmental Management Division.

The prefecture plans to install the remaining 27 monitoring posts by the end of this month.

“It is problematic for utility companies to restart nuclear reactors before the installation of radiation monitoring posts is sufficient,” said an official at the NRA Secretariat.

Technical problems caused the No. 4 reactor to automatically shut down only three days after it was restarted. A landmark court injunction on March 9 ordered Kansai Electric to halt operations of both reactors.

The situation concerning the monitoring posts indicates that local governments compiling evacuation plans cannot keep pace with the drive of utilities to restart their nuclear reactors.

Following the triple meltdown at the Fukushima No. 1 nuclear power plant, triggered by the Great East Japan Earthquake and tsunami in March 2011, the central government revised its guidelines for nuclear disaster countermeasures to mandate residents within 5 km of a nuclear plant to be promptly evacuated in the event of a serious accident.

Residents living between 5 km and 30 km from a plant will be required to stay indoors. The central government will then decide whether to order evacuations based on radiation levels detected by the monitoring posts.

If the radiation levels stay within 20 microsieverts per hour for an entire day, residents will be ordered to evacuate within a week. Immediate evacuations will be ordered if the radiation levels reach 500 millisieverts per hour.

The revised guideline also requires cities, towns and villages located within 30 km of a nuclear plant to map out evacuation plans and prefectural governments to install radiation monitoring posts, including those for assessing the need to issue an evacuation order.

A supplemental document compiled by the NRA Secretariat recommends the installation of stationary radiation monitoring posts to regularly survey airborne radiation levels, partly because it can be difficult to transport portable monitoring equipment following a nuclear accident.

(This article was written by Tomoya Ishikawa and Shinichi Sekine.)


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