Many people fear radiation disasters, including health care providers, ^{Reference Hasegawa, Takahashi and Nemoto1} and establishing a radiation disaster medical system is a difficult task. Based on experiences following the Great East Japan Earthquake and nuclear power plant accident in 2011, the medical response system for radiation disasters in Japan was revised. ^{Reference Ojino and Ishii2} Following guidelines related to the Act on Special Measures Concerning Nuclear Emergency Preparedness, Nuclear Emergency Core Hospitals (NECHs) were designated as centers for radiation disaster management in Japan. ^{Reference Tsujiguchi, Suzuki and Kashiwakura3} Designated NECHs must meet the following 3 requirements. First, NECHs need to accept and treat patients suffering from radiation exposure regardless of their contamination status. Second, in the event of a nuclear accident, NECHs need to form radiation disaster medical teams, including physicians, nurses, and radiologists with professional knowledge of radiation medicine. Third, NECHs need hospital staff (physicians, nurses, radiation technician, pharmacists, administrative staff) with specific knowledge of radiation medicine. As of August 1, 2020, there are 50 NECHs certified in prefectures in Japan in which nuclear power plants are located or are nearby. Other NECHs are also designated in prefectures in which nuclear power plants are located or are in neighboring prefectures. This is significant, because once a nuclear power plant accident occurs, a wide area will be affected. Therefore, response by a network of NECHs is suitable. The radiation disaster medical system in Japan consists of 3 layers (Figure 1), and the NECHs are in the second layer. The first layer consists of Nuclear Emergency Medical Cooperative Institutions, which are hospitals and health organizations responding to a radiation disaster locally. The third layer is a group of 5 High-standard Radiation Medicine Support Centers and 4 Radiation Disaster Medicine General Support Centers. The role of High-standard Radiation Medicine Support Centers is to serve as referral hospitals for radiation disaster patients and to provide training and education in radiation disaster medicine. The role of Radiation Disaster Medicine General Support Centers is to coordinate the radiation disaster medical team’s deployment and establish the network for radiation disaster medicine. The 5 High-standard Radiation Medicine Support Centers and 4 Radiation Disaster Medicine General Support Centers provide expert support for radiation disaster medicine, accepting patients who cannot be treated at NECHs, and coordinate the dispatch of medical teams. In 2018, the Ministry of Health, Welfare and Labor requested that all disaster center hospitals, the core of the disaster response in the local areas, create business continuity plans. ^{Reference Sasaki, Maruya and Abe4} Earthquakes are considered an assumption of risk assessment for disaster center hospitals in Japan, and radiation disasters such as nuclear power plant accidents have not been considered. Therefore, it is important for NECHs to create business continuity plans as part of the radiation disaster program.

Figure 1. Three layers of the radiation disaster medical system in Japan.

Historically, the medical response system for radiation disasters in Japan was established after the Tokaimura nuclear accident in 1999. ^{Reference Miyamoto, Watanabe and Yukawa5} Three workers were exposed to high levels of radiation in a small plant preparing fuel for an experimental reactor, and 2 died despite extended treatment in the intensive care unit. Hospitals in Fukushima Prefecture were faced with difficulties at the time of the Great East Japan Earthquake and nuclear power plant accident on March 11, 2011. Eleven people injured by the hydrogen explosion of Unit 3, Fukushima Daiichi Nuclear Power Plant station were accepted by designated hospitals on March 14, 2011. During the first 2 weeks after the accident, more than 60 people died during transportation from the evacuation zone in Fukushima. ^{Reference Ohtsuru, Tanigawa and Kumagai6} Since the evacuation zone expanded every day due to the deteriorating situation at the Fukushima Daiichi Nuclear Power Plant, patients in hospitals and nursing facilities within the evacuation zone were forced to stay without sufficient supplies or logistic support. Most hospitals outside the stricken area had no capacity to accept the patients at that time. These patients were especially vulnerable, including the elderly, mentally ill, or bedridden. When they were rescued, most were in critical condition and died during transportation to receiving facilities. Additionally, many hospitals had difficulty maintaining operations because social functions were widely affected by fear of radiation effects among staff. ^{Reference Hachiya, Tominaga, Tatsuzaki and Akashi7}

Preparedness for radiation disasters is important, and, therefore, efforts such as ensuring the availability of decontamination facilities, stockpiling of countermeasures or measuring devices, human resources, and training, are mandatory. Risk communications for first responders in case of a radiation disaster have already been established. ^{Reference Mori, Tateishi and Hiraoka8} Hachiya et al. reported that a basic knowledge of radiation for first responders was important to deal with the difficulties of the radiation disaster in Fukushima. ^{Reference Hachiya, Tominaga, Tatsuzaki and Akashi7} Although the importance of radiation disaster medicine and risk communications among health care workers is widely acknowledged, these have not yet been adequately established. ^{Reference Ingram9,Reference Svendsen, Yamaguchi and Tsuda10}

Several studies have been conducted to investigate hospital preparedness for chemical, biological, or radio/nuclear incidents. Mortelans et al. conducted a survey of 93 hospitals in the Netherlands and reported that even after the Fukushima disaster in 2011, most hospitals in the Netherlands were not well-prepared. ^{Reference Mortelmans, Gaakeer and Dieltiens11,Reference Mortelmans, Van Boxstael, De Cauwer and Sabbe12} Other studies also showed that most hospitals did not have adequate facilities, stockpiles of supplies, or training. ^{Reference Belsky, Klausner, Karson and Dunne13,Reference Murakami, Ono and Tsubokura14} The present study aimed to investigate the current status of NECHs in Japan and identify areas for improvement.

Results

Of 43 NECHs designated by 2018, 36 (83%) participated in this study. The characteristics of the NECHs are shown in Table 1. Of these, 67% are categorized as tertiary emergency hospitals, and 47% own separate facilities for radiation medicine that serve as the initial treatment area for triage, decontamination, and radiation measurement. However, only 31% of the hospitals have conducted a concrete risk assessment for a radiation disaster, and less than 40% have prepared standard operating procedures or manuals for the management of patients during a radiation disaster. Although the importance of business continuity plans and risk communications is recognized, specific plans or appropriate human resources have not been prepared. NECHs were categorized by the distance to the closest nuclear power plant and differences were evaluated based on this distance (see Supplementary Table S1). There were no differences found, implying that the sense of urgency does not vary with distance from the nuclear power plant.

Table 1. Characteristics of nuclear emergency core hospitals

Table 2 shows respondents’ attitudes toward NECHs and considerations for risk communications during a radiation disaster. Hospital staff and the local community understand the importance of designation as an NECH. However, similar to the results shown in Table 1, specific plans for risk communications have not been prepared.

Table 2. Attitudes regarding designation as a nuclear emergency core hospital and considerations for risk communications during a radiation disaster

Figure 2 shows the result of KH coder text mining analysis of free text comments. Frequent terms included “nuclear,” “disaster,” “response,” and “communication.” Figure 3 summarizes the free text descriptions of attitudes toward the NECH and considerations for risk communications during a radiation disaster categorized into 7 groups based on hierarchical cluster analysis. The 7 categories include media response, communications to hospital staff, risk communications, radiation effects on children, planning for radiation disasters in the region, rumors, and the role of the NECH in the region.

Figure 2. Results of KH Coder analysis of free text responses by co-occurrence network of words.

Figure 3. Results of the hierarchical cluster analysis.