Confronting the Larger Problem: A History of Accidents

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the legal authrority to review and approve the decommissioining plan from a safety perspective and can withdraw that approval if it doesn’t like what it sees. The IMC teams have substantial influence and control of the decommissioning plans as well because their members come from government Ministries that control the NDF and the NRA.

Figure 5.12 illustrates this tension. The Figure is a composite of selected organizational charts that have been issued by the NDF, NRA, and other oversight components of the Japanese government.

TEPCO clearly is responsible for executing decommissioning tasks, but legally it must take direction from at least three authorities: from the NDF for executing decommissioning tasks, from the NRA for maintaining appropriate safety standards, and from the Nuclear Emergency Response Headquarters at the ministerial level for any issue it might identify. Ideally, TEPCO should be responsible only to a single authority. The current arrangement is almost guaranteed to result in conflicting guidance to TEPCO, giving TEPCO the opportunity to follow the guidance that it finds most congenial. There is real ambiguity with respect to who is actually in charge of the Fukushima decommissioning project, but one thing is certain: complex technical projects that lack a clear chain of command are rarely successful.

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Looking at the numbers in the Japan Nuclear Energy Safety Organization (JNES) database, it is possible to make only very gross comparisons (See Figure 5.13). Japan’s event rate per reactor was notably high in the 1960s, but gradually dropped to a few per reactor in the 1970s, stabilized at less than one accident per reactor per year in the mid-1980s, and remained at that level throughout the 1990s and 2000s. We note that in 2014, five events were reported when there were no reactors generating power at the time.While the overall trend in the number of incidents and accidents has been mostly favorable, compared to to the UK, France, and the US, Japan’s record has not been outstanding. Adjusting for differing reporting standards, Japan’s record might even be significantly worse.

Japan’s most serious accidents have been unprecedented in scope and complexity. The Fukushima Daiichi accident did not happen in isolation; it was accompanied by a series of accidents at the neighboring Fukushina Daini power plant, located 12 km (7.5 mi) south of Fukushima Daiichi.

Fukushima Daiichi has six reactors and Fukushima Daini four reactors. According to the JNES database, these two plants had a total of eight accidents during the 3.11 disaster, including one Level 7 (that applies to the entire Daiichi plant site), three Level 5s (that apply to the three Daiichi reactors that suffered core meltdowns) and four Level 3s (that apply to the four Daini reactors) (See Table 5.4). We suggest that the accidents involving three melted cores and the breach of

containment vessels should each be separately rated as Level 7 accidents (vice Level 5). We show both ratings in Table 5.4.

Table 5.4 The Nuclear Accidents at Fukushima Daiichi and Fukushima Daini

The JNES database reports that Japan had 8 INES Level accidents at Fukushima Daiichi and Fukushima Daini Nuclear Plants on 11 March 2011. Our is also shown on table.

Sourc e:

Table creat ed by autho rs based on interp retati on of data from Source: JNES, 2014.

Accident Period

Plant/Reactor Name Date JNES Report Authors

View

On 11 March 2011 or soon afterwards

Fukushima Daiichi Nuclear Plant

11 March 2011 Level 7 3 Level 7 because of damage to 3 cores and 3 explosions Fukushima Daiichi 1 11 March 2011 Level 5

Fukushima Daiichi 2 11 March 2011 Level 5 Fukushima Daiichi 3 11 March 2011 Level 5

Fukushima Daiichi 4 11 March 2011 Level 3 Level 3 Fukushima Daini 1 11 March 2011 Level 3 Level 3 Fukushima Daini 2 11 March 2011 Level 3 Level 3 Fukushima Daini 4 11 March 2011 Level 3 Level 3

Total 1 Level 7 3 Level 5

4 Level 4

3 Level 7 4 Level 3

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Figure 5.13 Trends in Nuclear Accidents and Accidents per Reactor, Fiscal Year 1966-2015

Note: Total Number of Accidents = 772. Accidents per reactor is calculated based on the number of accidents divided by the number of operating reactors in the particular fiscal year. In FY2014, although there were 54 dormant reactors and no operating reactors, there were 5 accidents. Because it is not possible to divide 5 accidents by 0 reactors, the chart shows no accident.

Source: Created by the authors based on analysis of data from Japan Nuclear Energy Safety Organization (JNES), 2014; Japan Atomic Industy Forum (JAIF), 2014a, 2016; Nuclear Regulation Authority (NRA), 2016.

FY 19 66

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* 20 15 No of Accidents 13 6 4 3 3 13 9 5 13 8 24 17 22 26 25 36 26 27 18 19 19 19 23 22 24 20 20 17 14 14 14 14 14 17 19 11 8 11 20 15 15 23 23 15 16 8 6 5 5 4 Accidents per Reactor 13 6 4 2 1 3 2 1 2 1 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 2 2 5 0 2

0 2 4 6 8 10 12 14

0 5 10 15 20 25 30 35 40

Accident per Reactor

Number of Accidents

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We have rated the Fukushima accident ourselves because there have been disputes over the

authoritativeness of the INES rating system as it has been applied to Fukushima.. For example, the Fukushima Daiichi nuclear accident was originally rated as INES 5, but then upgraded to INES 7 when the events of Units 1, 2 and 3 were combined into a single accident. Considering that change, we judge that the INES rating for the Fukushima accident is very likely to be revisited. Others say that the INES scale is inconsistent, that the scores provided by the IAEA are incomplete, and that many significant events have not been given an INES rating (Minh, Journé, 2014; Wikipedia, 2018c).

Taking into account the limitations of the INES rating system it is nevertheless apparent that Japan has had a greater number of more serious accidents than any other country in the world (See Table 5.5). Of a total of 25 serious accidents worldwide rated INES 3 or higher, Japan had 7 of them, or 28 percent of the world total.

 Japan’s share of serious accidents is disproportionally large for a country that had 54 nuclear reactors, which is 12 percent of the 450 power reactors that were in service worldwide as of March 2011. (A comparison of the respective sizes of the current worldwide nuclear power reactor fleets can be found at Appendix B).

INES ratings of 3 or higher should be considered as the tip of an iceberg. Many accidents have occurred on a worldwide basis at lower levels of severity and still more have been recorded as incidents that could be construed as a kind of “near miss.” Thus, it is possible to conclude that Japan not only has had the highest number of nuclear events per reactor but also has had more accidents of a serious nature than any other country. Looking across all accidents with an INES rating of 3 or more, Japan has had twice as many serious accidents as the United States and more than three times as many as France (JAIF, 2014b).⁴⁵