Thesis Abstracts 2003
Archived Content
Information identified as archived on the Web is for reference, research or recordkeeping purposes. It has not been altered or updated after the date of archiving. Web pages that are archived on the Web are not subject to the Government of Canada Web Standards. As per the Communications Policy of the Government of Canada, you can request alternate formats on the "Contact Us" page.
Galactic and Solar Radiation Exposure of Aircrew Over a Solar Cycle
By: Marc Desormeaux MASc. (Nuclear Engineering)
Supervisors: Dr. B.J. Lewis and Dr. L.G.I. Bennett
Abstract
Legislation has been implemented in the European community to recognize aircrew as occupationally exposed, as recommended in report 60 of the International Commission on Radiological Protection (ICRP 60). Although Canada has yet to implement such regulations formally, Transport Canada has expressed its intent in an advisory circular to regulate such exposure in the near future.
For over a decade, research is being performed at the Royal Military College of Canada to evaluate the impact from cosmic radiation at various altitudes over the full magnetic field potential of the Earth (i.e., over all latitudes) and for any period in the solar cycle. This research has been encapsulated into a semi-empirical computer model termed Predictive Code for Aircrew Radiation Exposure (PCAIRE). However, various improvements were desirable before the model could be used in an effective dose management program for aircrew exposure prediction. They included a more consistent way to analyze the data, and a better accounting of route dose measurements taken during low altitude flights, as well as during extreme solar modulation conditions. Finally, PCAIRE could not estimate the impact due to sporadic solar radiation events, which can significantly increase the total cosmic radiation exposure over a short period of time.
As such, this thesis work concentrated on these model improvements, which were implemented into the latest version of the PCAIRE code (V7.2). The revised model was then validated against a database composed of 232 measured flights. In all, the revised code demonstrated excellent results, where most route doses, including those in low-altitude and extreme solar modulation conditions, were predicted to within an error range of ? 20%.
In addition, a new solar radiation model was developed and validated against two measured flights during a solar event, where the predicted doses reflected the actual measurements to within instrument and prediction error. This model was further used to estimate the impact from a very large event, compared to the career dose, which arises from the more important galactic cosmic ray component. The results from this case study demonstrated that, although very small over a career, large solar radiation events might be of concern to pregnant aircrew and aircrew on a high-altitude flight.
