In JAERI, Kodak Personal Neutron Monitoring Film, Type A-NTA film-has been used to estimate personal exposure dose due to fast neutrons. Track fading, spectrum of track after fading and prevention of track fading of the NTA film were investigated at various relative humidities of the atomosphere.
The phenomenon of track fading of the NTA film was remarkable at higher relative humidity and the fading curves consist of two components of exponential function. Relationship of lineality between dose and number of track was found to be still maintained in the advance of fading. In addition, dose dependence of fading was not observed. As relative humidity and storage time increases, track length became shorter and grain density of track decreased. Track fading is prevented by wrapping the NTA film with vinylidene chloride film and putting in the badge case.