Operational challenges of positive pressure systems for radiation protection in medical facilities

松本 智紘*; 田邊 翔太*; 山本 知佳*; Zhao, T.*; 澤野 豊明*; 野中 沙織*; 加藤 秀之*; 山口 文恵  ; 高原 省五 ; 田中 知明*; 坪倉 正治*

Matsumoto, Chihiro*; Tanabe, Shota*; Chika, Yamamoto*; Zhao, T.*; Sawano, Toyoaki*; Nonaka, Saori*; Kato, Hideyuki*; Yamaguchi, Fumie; Takahara, Shogo; Tanaka, Tomoaki*; Tsubokura, Masaharu*

During nuclear disasters, shelter-in-place (SIP) is often a safer alternative to evacuation for patients in medical facilities who may be particularly vulnerable. In Japan, medical institutions located near nuclear facilities have been equipped with positive-pressure systems (PPS), designed specifically for radiation protection. However, operational protocols to execute and manage SIP and PPS remain poorly defined. This study aimed to investigate the challenges in implementing SIP at the time of nuclear catastrophe while maintaining essential clinical functions. A case study was conducted at the Matsue Red Cross Hospital, located within an urgent protective action planning zone. Data were gathered through participation in the hospital's nuclear disaster countermeasures committee and through analysis of meeting minutes, facility documents, and technical specifications. The findings revealed a fundamental conflict between the technical requirements of PPS and the continuity of clinical services. Four critical sub-challenges were identified: (1) the unavoidable presence of certain staff and patients in non-protected zones within the hospital; (2) the potential inability to maintain sufficient positive pressure in protected zones during active clinical service; (3) the difficulty in regulating indoor temperature and humidity as a consequence of PPS operation; and (4) the increased risk of external radiation exposure in the vicinity of PPS units when outdoor ambient dose rates are elevated. For facilities that already have PPS installed, further investigations into PPS operations and the development of countermeasures are necessary. Furthermore, when installing PPS in the future, it is desirable for the government, hospitals, and installation companies to thoroughly discuss operations and design systems to minimise the impact on hospital functions.