On March 11, 2011, we watched in horror as a triple tragedy -- earthquake, tsunami and nuclear meltdown --befell Japan.

One year later, Fukushima Daiichi Nuclear Power Station may be in ''cold shutdown'' but the effects of the accident there are still being felt on a daily basis.

In contrast to devastated towns and villages elsewhere, rebuilding of the communities around the plant has barely begun. Inevitably, an unprecedented number of Japanese are asking whether nuclear power should have any place in their country's energy policy.

Whatever Japan decides, however, it needs a much more robust system of nuclear regulation. (After all, even if Japan were to phase out nuclear energy tomorrow -- and that hardly seems possible -- the management of nuclear waste must be overseen.)

Since the accident, criticism of the Nuclear and Industrial Safety Agency (NISA) has focused on its lack of independence from the Ministry of Economy, Trade and Industry, which is responsible for promoting nuclear power. Quite rightly, NISA is now being reconstituted under the Ministry of the Environment. However, regulation in Japan has other problems that must be addressed.

As well as lacking independence from government, NISA also lacked independence from industry. Amakudari (''descent from heaven''), the practice of giving senior regulators jobs at the helm of industry, has been stopped. However, amaagari (''ascent to heaven''), in which industry safety experts are employed by regulators, still continues.

Industry safety experts certainly have an important -- indeed irreplaceable -- role in regulation. However, NISA and its technical support organization, the Japan Nuclear Energy Safety Organization, have probably become over-reliant on them. Fostering a new generation of independent experts is a key challenge -- and one that cannot be solved by legislation alone.

Perhaps partly because of its over-reliance on industry expertise, NISA showed a lack of imagination about potential threats to nuclear power plants.

Its strong focus on seismic safety appears to have come at the expense of considering other risks. We have no doubt that Japan's new regulator will take tsunami safety very seriously. However, there are many other potential threats, ranging from extreme meteorological effects resulting from climate change to terrorism.

To properly consider all these risks, Japan's nuclear regulator must engage with experts from many different fields and move beyond the relative insularity that has been a hallmark of much of the Japanese nuclear sector in the past.

NISA's most fundamental failing was, however, that it appeared to believe that a major accident was simply not possible. Perhaps only this can explain why it did not issue regulations covering the long-term loss of electricity in a nuclear power plant or insist on the development of robust procedures for managing a severe accident.

In the years to come, a major challenge for the new regulator will be avoiding complacency. Leadership will be required from within -- as will public scrutiny from without. Ultimately, the best way to avoid a repeat of Fukushima is to remember that one is always possible.

This article originally appeared in Kyodo News.