Radiation dose effect

United Nations, Radiation, Doses, Effects, Risks, United Nations Environment Programme (UNEP), Nairobi, Kenya, 1985... 

Preliminary evaluations about the effects of additional release of FP gas on evaluation of radiation dose, effects of mechanical energy on the pressure boundary and on coolability suggest that there should be no serious safety concerns.)... 

Peterson, H.T., Jr. 1984. Regulatory implications of radiation dose-effect relationships. Health Phys. 47 345-359. 

Radiation Doses, Effects, Rides, United Nations Sales No. E.86.III.D.4, 1985. 

Most of the data on radiation health effects have come from medical monitoring of Japanese atomic bomb survivors. For survivors who received radiation exposures up to 0.10 Sv, the iacidence of cancer is no greater than ia the geaeral populatioa of Japanese citizens. For the approximately 1000 survivors who received the highest radiation doses, ie, >2 Sv, there have been 162 cases of cancer. About 70 cases would have been expected ia that populatioa from aatural causes. Of the approximately 76,000 survivors, as of 1995 there have beea a total of about 6,000 cases of cancer, only about 340 more cases than would be expected ia a group of 76,000 Japanese citizens who received only background radiation exposure (59). 

For radiation doses <0.5 Sv, there is no clinically observable iacrease ia the number of cancers above those that occur naturally (57). There are two risk hypotheses the linear and the nonlinear. The former implies that as the radiation dose decreases, the risk of cancer goes down at roughly the same rate. The latter suggests that risk of cancer actually falls much faster as radiation exposure declines. Because risk of cancer and other health effects is quite low at low radiation doses, the iacidence of cancer cannot clearly be ascribed to occupational radiation exposure. Thus, the regulations have adopted the more conservative or restrictive approach, ie, the linear hypothesis. Whereas nuclear iadustry workers are allowed to receive up to 0.05 Sv/yr, the ALARA practices result ia much lower actual radiatioa exposure. 

Nonetheless, these methods only estimate organ-averaged radiation dose. Any process which results in high concentrations of radioactivity in organs outside the MIRD tables or in very small volumes within an organ can result in significant error. In addition, the kinetic behavior of materials in the body can have a dramatic effect on radiation dose and models of material transport are constandy refined. Thus radiation dosimetry remains an area of significant research activity. 

The reader should note tliat since many risk assessments have been conducted on the basis of fatal effects, there are also uncertainties on precisely what constitutes a fatal dose of thennal radiation, blast effect, or a toxic chemical. Where it is desired to estimate injuries as well as fatalities, tlie consequence calculation can be repeated using lower intensities of exposure leading to injury rather titan dcatli. In addition, if the adverse healtli effect (e.g. associated with a chemical release) is delayed, the cause may not be obvious. Tliis applies to both chronic and acute emissions and exposures. 

Figure 8 Effect of radiation dose on copolymerization of acrylamide with DAEA-HCl. O = q(%) = [tj].

There are a number of important factors that must be considered before applying gamma radiation-induced grafting. These factors include the radiation sensitivity of the polymer/monomer system, radiation dose and dose rate, type and concentration of inhibitor, type of solvent or diluent, and monomer concentration. The effect of such parameters on the grafting efficiency during mutual grafting is given below. 

Figure 6 Effect of radiation dose on the graft yield (%) of grafted cotton linters.

Table IV. Effect of Radiation Dose on Pouch Sealability...

This section will deal briefly with some aspects of expls safety peculiar to neutron activation analysis expts. We are concerned here with a) the possible effect of the ionizing radiation dose on the energetic material which will cause it to be more sensitive or hazardous to normal handling as an expl, and b) the potential direct expl hazards involved in the physical and mechanical transportation of samples to and horn the irradiation source and in a nuclear counting system... 

It is shown by Grossmann that for his phenyl compounds the results are qualitatively the same in the presence and in the absence of strong radiation doses, yet the results of Nowak and various others show that for alkyl metals radiation effects are more important. 

Radiation doses required to effect desirable changes in polymers (2-10 Mrad) can be delivered to the product in question in a matter of seconds [39] whereas, it might have taken hours to accomplish the same with 7-radiation sources of reasonable intensity [33]. 

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