Chubu reactor safety improvements mixed bag

Chunichi Shimbun

The Fukushima No. 1 nuclear plant crisis prompted the government to ask untilities nationwide to draw up mid- and long-term countermeasures against future earthquakes and tsunami.

Among six power plants that supply electricity for commercial use in the Chubu region, only two — the Hamaoka facility in Shizuoka Prefecture operated by Chubu Electric Power Co., and Hokuriku Electric Power Co.’s Shika plant in Ishikawa Prefecture — will be able to complete the construction of new seawalls by the end of this year.

On preventing hydrogen explosions — a major problem at Fukushima No. 1 — measures have started at all of the reactors except units 1 and 2 at the Oi plant in Fukui Prefecture, where Kansai Electric Power Co. had taken preventive steps before the Fukushima disaster.

The crisis in Fukushima started when massive tsunami submerged the emergency power system. The resulting loss of the cooling functions for the reactors triggered meltdowns, leading to a large amount of radioactive fallout.

Right after the crisis erupted last March, the Nuclear and Industrial Safety Agency instructed the country’s power utilities to bolster their safety measures. Then in June it ordered them to prepare for severe accidents.

The Chunichi Shimbun polled six nuclear plants in the Chubu region to access the progress of preventive measures that will take months to complete, including efforts to prevent hydrogen explosions, seawall construction and installation of emergency generators on higher ground.

Both the Shika and Hamaoka plants have already started building seawalls 15 to 18 meters above sea level. Shika aims to complete construction this fall and Hamaoka in December.

However, none of the four nuclear power plants in Fukui Prefecture has started construction. Kepco’s Mihama plant and Takahama plant in Fukui Prefecture will not see new seawalls completed until fiscal 2015.

Steps to prevent hydrogen explosions include installing hydrogen-bonding equipment that creates water by combining hydrogen in a reactor containment vessel with oxygen.

Of the 16 reactors in the Chubu region where preparations have been under way to install the equipment, unit 1 at the Tsuruga plant run by Japan Atomic Power Co., two reactors at the Shika plant and three reactors at the Hamaoka plant are either in the process of installation or have already introduced part of the equipment. The work is to be completed for unit 1 at Tsuruga by the end of this month.

Installation work has not started at the region’s 10 other reactors. The work is expected to be finished by the end of fiscal 2013.

Situating emergency power generators on higher ground has been completed at the Mihama, Oi and Takahama plants. The Hamaoka plant expects to complete the work by the end of this year. The Tsuruga plant is still searching for suitable sites.

Meanwhile, the government is asking utilities to install exhaust ventilation systems to help release pressure in reactors in case of an accident. Kansai Electric and Japan Atomic Power plan to install the system at 13 reactors in four plants.

All six of the nuclear plants in the Chubu region are offline for scheduled maintenance. But the Nuclear Safety Commission has been assessing the results of stress tests for the Oi plant’s reactors 3 and 4, which could be the first to resume operations since the Fukushima calamity. The final result of the assessment will be announced by the end of this month.

This section, appearing Saturdays, features topics and issues from the Chubu region covered by the Chunichi Shimbun. The original article was published on March 5.