Tsunami expectation and Final Report

The Feb. 7, 2016 morning edition of Nikkei posted an article titled "Road to recovery (6): Was Fukushima beyond expectation?" The article started as follows:
"TEPCO's Fukushima Daiichi Nuclear Power Plant (NPP), flooded with the water from tsunami, lost its cooling function for the nuclear reactor and its core melted. Was the accident really beyond expectation? If TEPCO had prepared the plant with discreet judgement, the accident could have been contained."
The tsunami preparation study group of the Association for the Study of Failure (ASF) had reached the same conclusion with the Nikkei reporter. Moreover, IAEA in its final report [1] clearly stated that the huge tsunami was predictable.
Our study group, after reviewing the Furukawa paper [2] that raised the question, started with Motoharu Furukawa, Ritsuo Yoshioka, Masao Fuchigami, and myself, Kenji Iino to find answers to the questions:

1. Predictability of huge tsunami at Fukushima, and
2. What could have prevented the Fukushima accident from turning into a disaster?

We collected advices from experts in our association and other organizations to reach the conclusion in our Report (Sept. 30, 2015, in Japanese).
Yoshioka reported the results in the 2015 Winter Annual Meeting of ASF with a heavy comment:
We revised our 2015 report, and here is the summary:

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Report: "Fukushima Nuclear Power Plant Tsunami Preparation Study Group"
Feb. 1, 2016
ASF tsunami preparation study group
Introduction
The Atomic Energy Society of Japan (AESJ) monthly journal ATOMΣ reported in its March 2015 issue about activities related to the Fukushima Nuclear Power Plant accident by academic societies. Further in its September issue, it declared its intension to "cooperate with other academic societies." This September article quoted ASF's opinion that "In addition to analyzing the accident, we should construct a rich knowledge basis by studying what actions, different from the actual course of events, could have been taken to lead to success and not failure."
There are as many as 10 investigation reports about Fukushima NPP accident, however, they all discuss the "process of how the accident developed" and none explains "If there was a way to avoid failure."
ASF carried out 4 Forums since February of 2014, and through the discussions organized "Study on tsunami preparation at Fukushima NPP" in April and June of 2015. The studies were aimed at clarifying answers to the following two questions. Details of our conclusion in on our home page (currently only in Japanese) [3].

1. Was the huge tsunami after the great earthquake at Fukushima NPP predictable?
2. If the huge tsunami was predicted, what preparations at Fukushima NPP could have saved it from the disaster?

The Government investigation report and Diet investigation report have some descriptions that address question 1. We further looked into the problem. Then for question 2, we did not find any studies by nuclear experts and before we carried out our studies we solicited participants through the AESJ mailing list, and over 10 experts and journalist joined the work.

Question 1: Was the huge tsunami predictable?
We list notable events along the time scale:

1. 1997 - 1998: TEPCO's report in response to "Guideline for Enhancing Tsunami Preparation in Local Disaster Management Plans" by 7 ministries
2. 1999: Tsunami inundation forecast at Fukushima Daiichi NPP, by National Land Agency
3. 2008: TEPCO tsunami expectation at Fukushima NPP based on 2002 earthquake prediction by The Headquarters for Earthquake Research Promotion of Ministry of Education, Culture, Sports, Science and Technology
4. 2009: TEPCO's calculation results based on wave source of Jyogan Tsunami

All the above results predicted waves that exceed the land elevation to flood the buildings.

5. The IAEA final report, in addition to 3. and 4. above, discuss the following three points
   1. The Japanese evaluation based only on past earthquakes and tsunami was violating international standards.
   2. The international practice was evaluation based on largest earthquake. The pacific had experienced M9.5 Chilian Earthquake and M9.2 Alaskan Earthquake, thus, great earthquake of that level should have been assumed. The IAEA final report does not refer to it, but the US government in 2006, reported prediction and evaluation of an M9 earthquake and resulting tsunami from Japan trench.
   3. Since past events were uncertain, taking the safer stance could have predicted the height of the 2011 tsunami.

Question 2: How the severity of the accident could have been avoided?
The direct cause of the Fukushima NPP accident was the simultaneous loss of AC power, DC power, and ultimate heat sink.
If the following minimum preparations were made at the plant, the nuclear accident could have avoided its severity. The most demanding task is to manually hook up DC power to RCIC and HPCI after recognizing the loss of AC and DC power, and the remaining procedures have some options with time slack.

1. Enough numbers of 125V/250V batteries
2. Emergency response vehicle with high AC power generator
3. Water pump for alternate RHRS water pumping
4. Training against loss of AC power, DC power, and seawater pump and motor.

The above is the minimum preparation against the 3.11 tsunami, and a complete preparation should include the following measures.

5. Watertight preparation of RCIC and HPCI
6. AC portable generator for driving the Unit-1 Isolation Condenser AC vales inside the containment vessel (CV)
7. Portable compressor in case compressed air for driving vent line air-operated valves is lost
8. Fire engine

References

1. "The Fukushima Daiichi Accident, Technical Volume2, Safety Assessment," 2015, IAEA
2. Motoharu Furukawa, "3.11 Severe Nuclear Accident and TEPCO's Criminal Liability," Asahi Judicial (in Japanese) [http://judiciary.asahi.com/fukabori/2014030700001.html]
3. Final report, Tsunami preparation at Fukushima NPP, rev.1 (in Japanese), 2016, ASF, http://www.shippai.org/images/html/news881/Report160201.pdf
   

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