Collected effective dose

Table 3.3 summarizes the radiation exposure doses due to the industrial exploitation of phosphate rock, expressed in terms of collective effective dose equivalent commitments resulting from the decision to use a unit mass of marketable ore to accomplish a defined purpose, as reported by UN Scientific Committee on Effects of Atomic Radiation (United Nations, 1982). 

Collective effective dose equivalent commitments per unit of marketable phosphate ore (10 man Sv t" )... 

The collective effective dose committed by an event, a decision or a finite portion of a practice k, 5, is given by ... 

The linear relationship between dose and effect, as illustrated by eqn. (18.4) and the line a in Figure 18.10, are based on the assumption that cancer induction is a stochastic single hit process independent of dose rate or dose fractionation. Thus the detriment to the population is die same whether one person receives 20 Sv, or 20 000 receive 1 mSv each. Using the dose-effect relation of (18.4) there will be a 100% chance of cancer in both cases. We can express this by saying that the collective (ffective dose is 20 man sieverts (manSv). The collective effective dose, is the sum of the effective doses to all n individuals ... 

The collective (effective) dose concept is commonly applied to natural radiation background. At an average level of 3 mSv/y 0.015% (18.4) of the population should die of cancer each year from natural radiation. For a population of 50 M people, the collective dose becomes 150 000 manSv/y and corresponds annually to 7 500 additional cancers (out of an expected 100000 cancer deaths/y). Consequently, the background radiation may be responsible for about 5 — 10% of all cancers a more prudent statement is 10% of all cancers". This claim is not possible to confirm by epidemiological investigations. 

TABLE 22.1. Collective effective dose to the public from radionuclides released in effluents from the nucUar Jiiel cycU 1995-97 (UNSCEAR 2000)... 

The collective effective dose shall be ALARA. The target for annual collective effective dose averaged over the plant life is 0.5 man Sv per unit. 

In the accident duration (30 days) the acceptable collection effective dose of residents in the region of 80km radius should be less than 2 x 10 man Sv, the same value also for collection thyroid effective dose. 

The collective dose quantity represents the total consequences of exposures of a population or group. The use should be limited to situations in which the consequences are truly proportional to both the dosimetric quantity and the number of people exposed. The collective equivalent dose, Sr, is the average dose to a tissue or organ T in the exposed group multiplied by the number of individuals in the group. If several groups are involved, the total collective quantity is the sum of the collective quantities for each group. The collective effective dose, S, has similarly been defined by ICRP ... 

Averaged (individual) effective doses and collective effective doses from diagnostic medical X-ray examinations in some counties are listed in O Table 55.22. 

Effective dose/mSv Country Per examination Per capita Collective effective dose/man-Sv... 

From the average effluents data UNSCEAR determined the collective doses for a model site based on nuclide specific dose-conversion coefficients, which were calculated applying a simple dispersion model, nuclide specific transport parameters, and population density data of 400 km for 1-50 km, 20 km for 50-2,000 km. The normalized collective effective doses... 

Normalized collective effective doses from radionuclides released from reactors, 1990-1994 (UNSCEAR 2000U)... 

Reactor type Collective effective dose per unit electric. Airborne effluents Noble gas 1 tl energy generated (man-Sv/GWy) Liquid effluents Particulates Others ... 

The global collective effective dose estimated for 10,000 years amounts to 50 man-Sv/GWy. The main contribution is from globally dispersed C from reactors and reprocessing. The longer-term trends in collective effective doses per unit electrical energy generated show decreases due to reductions in the release of radionucKdes from reactors and fuel reprocessing plants. 

The collective effective dose (not including dose to the thyroid) received by about five million residents living in the areas of Belarus, the Russian Federation, and Ukraine contaminated by the Chernobyl accident ( Cs deposition on soil of >37 kBq/m ) was approximately 40,000 man-Sv during the period 1986-1995. The groups of exposed persons within each country received an approximately equal collective dose. The additional amount of collective effective dose projected to be received between 1996 and 2006 is about 9,000 man-Sv. The collective dose to the thyroid was nearly 2 x 10 man-Gy, with nearly half received by persons exposed in Ukraine. 

The plutonium decreased exponentially with the half-life of about 14 months. The sizes of the particles ranged from 5 pm to 58 pm. The sured and the collective effective dose from the 2,100 man-Sv. 

Cosmos-954 A satellite of the USSR, Cosmos-954, reentered the atmosphere over Northwest Canada on January 24, 1978. The satellite was believed to have contained 20 kg of highly enriched uranium. Released fission products were estimated since the reactor worked for 128 days at 100 kW. 75% of the particulate radionuclides were estimated to be dispersed in the atmosphere and 25% to be deposited on uninhabited regions in Northeast Canada. The vaporized radionuclides, and Cs, were dispersed in the atmosphere. The collective effective dose was 20 man-Sv in the world. 

Ciudad Juarez, Mexico A medical source of 16.7 TBq of Co was discarded by mistake in December 1983 at Ciudad Juarez in Mexico, and the 6,000 pellets of that source contaminated many products of steel, which were sold in Mexico and the USA. About 1,000 people were exposed by this source and the collective effective dose was estimated to be 150 man-Sv. 

Mochmedia, Morocco A lr source for the radiography of welding at construction sites was accidentally dropped in a street in September 1984, and a passenger picked it up and went home with it. All eight people of his household were exposed to 8-25 Sv and died, and the collective effective dose was estimated to be 80 man-Sv. 

Goiania, Brazil A medical source of 50.9 TBq of Cs was disposed of in September 1987 and was dismantled by a trader of scrap metal. Subsequently, 20 exposed people were hospitalized and 4 people died. For the decontamination, 42 houses were decontaminated and the total volume of 3,500 m waste was produced and the collective effective dose was estimated to be 60 man-Sv. 

Practice Number of monitored workers collective effective dose/man-Sv dose per unit energy generated/man-Sv (GWy)-i For monitored workers Measurably exposed workers... 

The general principles for exen tion are reformulated by requiring that radiation risks to individuals and the collective radiological impact are both "sufficiently low as not to warrant regulatory control". In addition, it is stated that practices and sources may be exempted "without further consideration" provided that individual doses do not exceed 10 ftv/y and the collective effective dose committed by one year of the practice is no more than about 1 man.Sv. Compliance with these conditions allows for "automatic exemption". 

Fig. 7.2. Relative frequencies (upper panel) of various X-ray examination categories and their relative contribution to the collective effective dose (lower panel) in Germany in 2004...

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