TOKYO -- The combined costs of paying compensation for the Fukushima nuclear disaster and the decommissioning of the plant's reactors may be double the initial estimate, rising to more than 20 trillion yen ($176 billion), according to estimates by the country's industry ministry.

At the end of 2013, the Ministry of Economy, Trade and Industry calculated the cost at 11 trillion yen, which has since become the government's official estimate.

As electric companies other than Tokyo Electric Power Co., the operator of the crippled plant, will also pass part of the cost on to consumers through higher rates, an increase in the public burden is unavoidable.

According to multiple sources, the ministry has already conveyed its new estimates to members of its expert panel, which is in discussions on reforming the management structure at Tepco and measures to secure funds.

The ministry aims to reach an agreement with the Ministry of Finance during planned discussions over the expansion of an interest-free loan program from 9 trillion yen to support Tepco.

The 11-trillion estimates foresaw 5.4 trillion yen for compensation payments; 2.5 trillion yen for decontamination work; 1.1 trillion yen for the construction of interim radioactive waste storage facilities; and 2 trillion yen secured by Tepco to scrap the reactors.

The new estimates see compensation payments costing 8 trillion yen and 4-5 trillion yen for decontamination.

The cost of decommissioning reactors -- a process which will span at least 30-40 years -- are projected to swell to hundreds of billions of yen a year from the current 80 billion. That would add several trillion yen to the overall cost.

Combined with the cost of building interim storage facilities, the total cost is forecast to exceed 20 trillion yen.

The snowballing costs are due mainly to the expansion of the number of people eligible for damages and the difficulty of conducting decontamination work, neither of which was fully understood when the initial estimates were made.

As conditions inside the reactors gradually become clear ahead of the retrieval of fuel debris scheduled for early in the 2020s, it is becoming increasingly certain that decommissioning will cost more than 2 trillion yen.

(Nikkei)