Summaries of articles in this issue

Abstract

Discrepancy between DS86 calculated and measured neutron activation data in Hiroshima N Hunter and M W Charles (345-356) The thermal neutron activation measurements carried out over many years in Hiroshima and Nagasaki have been the subject of ongoing debate in recent years because they indicate that current DS86 neutron doses may have been significantly underestimated in Hiroshima. In this article we show that this discrepancy appears to be reinforced by using the latest thermal neutron activation data. However, some very recent fast neutron activation data suggest that the discrepancy may not be so great as that indicated by the majority of previous thermal neutron data. The extent of the revision needed to the DS86 neutron component remains subject to ongoing neutron activation measurements and re-analysis of existing published measurements.The impact of possible revisions to the DS86 dosimetry on neutron risk and relative biological effectiveness N Hunter and M W Charles (357-370) The current DS86 dosimetry system for the Japanese bomb survivors indicates that neutron doses were too low to directly derive useful neutron risk estimates. We have investigated the impact on neutron risks of increasing neutron doses in Hiroshima in line with the majority of thermal-neutron activation measurements. These increases, if substantiated, would have no significant impact on gamma radiation risk estimates but would allow useful neutron risk estimates to be made for solid cancers and leukaemia. Whether the Japanese bomb survivors can indeed form the basis for useful, directly determined, neutron risks depends on the reliability of existing thermal and fast neutron activation data. This is the subject of current research and debate.New methods for addition of doses from different environmental pathways W C Camplin et al (371-388) A new method for estimating radiation doses to UK critical groups is proposed for discussion. Results of surveillance at nuclear sites by the Food Standards Agency and the Scottish Environment Protection Agency are published in the Radioactivity in Food and the Environment (RIFE) report series. In these reports, doses to critical groups are normally estimated separately for gaseous and liquid discharge pathways. Simple summation of these doses would tend to overestimate doses actually received. Three different methods of combining the effects of both types of discharge in an integrated assessment are considered and ranked according to their ease of application, transparency, scientific rigour and presentational issues. The best method is then further developed using surveillance data for the calendar year 2000.Doses to organs and tissues from radon and its decay products G M Kendall and T J Smith (389-406) It is generally accepted that inhalation of radon decay products leads to a risk of lung cancer. But are there also risks to other organs or tissues? Is it justifiable to ignore the contribution from radon gas? While attention is usually concentrated on inhalation, is there a potential risk from ingestion of water containing radon or from deposition of decay products on the skin? This paper considers these questions, both by comparing the doses calculated for different tissues under different circumstances and also by examining the evidence from epidemiology.Radiological assessment of the level of safety in logging operations in the petroleum industry A A Abison (407-415) A study was initiated in 1993 in the Niger delta area to examine the radiological issues arising from the use of radioactive materials during hydrocarbon exploration and production activities spanning over forty years. The study was aimed at determining the level of radiological safety among various industrial establishments, but it could not make much progress without an assessment protocol. This paper describes such a protocol and the numerical result of its application to establishments involved in logging operations. The individual elements chosen for inclusion in the protocol are common sense and compatible with approaches such as loss prevention philosophy.Ge-doped optical fibre as a thermoluminescent dosimeter Y A Abdulla et al (417-421) This article describes the use of Ge-doped optical fibre as a thermoluminescent dosimeter for measuring the percentage depth dose of 6 and 10 MV x-rays. The results indicate that the Ge-doped optical fibre is in good agreement with the results obtained from a cylindrical ionisation chamber and TLD-100.