福島県文化財センター白河館「まほろん」に設置された被災文化財仮保管施設内の保存環境

摘要

2011(平成23)年3月11日の東北地方太平洋沖地震に伴って生じた津波による東京電力福島第一原子力発電所の事故により福島県内では立ち入りが規制される地域が生じ，2014年11月時点でも帰還困難区域(5年を経過してもなお，年間積算線量が20ミリシーベルトを下回らないおそれのある地域)ではインフラの復旧は遅々とした状況である。立ち入りが制限された区域内の資料館では防犯面で問題があり，また温湿度環境の制御ができず，建物内への害虫，ネズミ等の侵入による文化財への被害のおそれもあり，2012(平成24)～2013(平成25)年度に，管理できる場所への文化財搬出がおこなわれた。%In order to evacuate historical objects from museums of Tomioka town, Okuma town and Futaba town respectively, two temporary storehouses with buffer zones were built near the storage of the Shirakawa Branch of Fukushima Cultural Property Center in March 2013. The movement of temperature and relative humidity in the storehouses was measured by data loggers respectively. The inside of the storehouses was designed like a storage room for valuable objects, installed with thick insulators and airtight doors. Humidity conditioning material was also fabricated on the walls in the storehouses. Temperature was controlled by air conditioners and relative humidity by dehumidifiers with a dry desiccant system which has an ability to suppress relative humidity below 60%. Circulation fans were installed between the buffer zones and main storage rooms, and the trend of temperature and relative humidity in the buffer zones were feasibly controlled. Circulation fans were regulated to positive pressure in the storehouses against outdoor pressure of the atmosphere. No humidifier was installed. It was found that the buffer zones of the temporary storehouses were strongly affected by outdoor atmosphere. Dew formed in the buffer zones when the temperature setting of the main room was not appropriate in summer and winter. Some bugs intruded into the buffer zones every day and curators vacuumed them away. In summer, the main rooms were well conditioned. In winter, relative humidity decreased with air circulation from outdoors for workers in the storehouses. To prevent the sensitive objects from breakage under dry condition, they were packed with humidity conditioning material into cardboard boxes and sealed with plastic sheets. It was found that the objects were kept in a good condition inside the cardboard boxes.