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Transformity Calculation of Radiation Dose to Emergy


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									   Transformity Calculation of Radiation Dose to Emergy
              ChiChang Liu, Hei-I Lo, Ching-Jiang Chen, Ching-Chung Huang
                            Radiation Monitoring Center, AEC
                    823,Cherng-Ching Road,833, Kaohsiung, Taiwan

      A tool for decision-making in ecological economic system that evaluate the energy
required to make a service or product expressed in solar energy is called as emergy analysis.
In practice, the use of emergy as quantitative measure, allows comparison across disparate
materials, energies and processes that are not usually directly comparable. To assess the
justification of a practice, factors in three categories including environment, society and
economy. However, the traditional approach seems weighted more on human health and
economy. By the concept of emergy, ecological factors could be transformed to comparable
quantities with those of human health. A modified model previously suggest by IAEA is used
to evaluate the emergy due to ionizing radiation dose to human. The quantification of ionizing
radiation hazard to non-human being is still difficult because of lacking knowledge on chronic
effect and uncertainty inherent. A new task group of ICRP is established to define the effects
and endpoint of interest. The transformity of radiation dose to emergy in Taiwan is derived as
5.211014 sej/man-Sv for worker and 6.791014 sej/man-Sv for public respectively. A case
study of fly ash reused as replacement material of cement. Cement is an important building
material, but its producing process consumes much emergy. Usage of fly-ash as replacement
is shown to be satisfied environmental justification.

       The pervasive growth of interest over this decade in the idea of asking any processes or
products to ensure that plans and activities should make an optimal contribution to sustainable
development. Radiological impact is inevitable to be included when products containing
enriched natural radioactivities. To do assessment for sustainability, it is importance to
integrate all the factors in so call “three-pillar” or “triple-base-line” (TBL) model, which is
conceptualized as three intersecting circles representing the environment, society (human
being) and economy [1]. Decision making should be based on maximizing win-win-win
condition but not on protection limit compliance. However, the economic system is likely
considered human market only that seems unfair to non-human species. The TBL model
sometimes misleads people to evaluate factors in three categories as independent.
Constructing another economical system with equal and fair valuation procedure on every
species is necessary.
       A thermodynamic framework that considers ecological and industrial systems to be
networks of energy flow permits the inclusion of ecological and economical factors. All
material and services in this network are transformed and stored forms of solar energy. Thus,
instead of using dollars value of goods, solar embodied energy (or solar emergy) is used as a
common currency for the analysis of industrial and ecological system [2]. Traditional emergy
analysis is often used in natural ecological systems and economical system without
considering the impact of wastes. Because, in natural, the waste of one life form is usually the
food of another life form, emergy method was thought to be lack of ability for emission
impact assessment [3]. Recently some modifications were made to improve traditional
method to be capable of assess the impact of waste and the index of sustainability.
       Emergy is defined as sum of the available energy of one product previously required
directly or indirectly through input pathway to output. The unit is solar emergy that

abbreviation as sej. The relationship is

transformity is the emergy per unit available energy (exergy). However, for the case of energy
fluxes or material products not directly related to solar energy flow, transformity could be
calculated as solar emergy per unit material (Volume or mass).

                                                Nonrenew       N

                 Renew          Environmental    R         Industrial       Y   Econamic
                 source            system                   process              market


                 Figure 1 Conceptual emergy flow chart of industrial system.

      To illuminate the different aspects of sustainability, several emergy indices have been
defined [4,5]. Those are shown in figure 1 and table 1.
      A modified system was introduced that emission impact is included. The typical emergy
flow diagram is shown in figure2 [6]. Emissions that might harm the ecological system are
denoted as R1 and F1 in figure 2. That may be quantified as the ecological and economic
emergy loss. By the indices defined in table 1, emission impact to environment could be
considered as one component in sustainability assessment. The environmental impact of
ionizing radiation might be evaluated by the same framework.

                                Table 1 Emergy based indices [5].
                Indices                 Expressio                 Significant
                   EIR                   F/(N+Y)     The ratio of emergy feedback from
       (Emergy investment ratio)                   purchased resources to the indigenous
                                                                emergy input.
                  EYR                      Y/F     Ratio of the output emergy Y divided
          (Emergy yield ratio)                            by the feedback emergy.
                  ELR                    (F+N)/R Ratio of feedback F and nonrenewable
     (Environmental loading ratio)                    emergy N to free environmental
                                                                  emergy R.
                   ESI                  EYR/ELR      The emergy yield ratio devided by
        (Index of sustainablility)                      environmental loading ratio.

                                                Nonrenew       N

                 Renew          Environmental    R         Industrial           Y   Econamic
                 source            system                   process                  market

                                  R1                 F1                 W



      Figure 2 Modified chart with waste W and impact F1 as increasing input cost R1.

       In ICRP no. 26, it suggested that “if man is adequately protected then other living
things are also likely to be sufficiently protected"[7]. ICRP no.60 States “The committee
believes that the standards of environmental control needed to protect man to the degree
currently thought desirable will ensure that other species are not put at risk”[8]. However, it is
difficult to convincingly demonstrate that the environment has been or will be adequately
protected in different circumstance. In ICRP no. 91, it is concluded that "a systematic
approach for radiological assessment of non-human species is needed in order to provide the
scientific basis for managing radiation effects in the environment"[9]. ICRP established a new
task group to continue the work with defining effects and endpoint of interest [10].
       We try to use emergy analysis as a tool to evaluate the justification or optimization for
environment before a practice/intervention is suggested. The most challenge is lacking of
suitable transformity tables. Setup a procedure to transform radiation hazard to equivalent
solar energy is the first step.

       The health-cost that people "willingness to pay" suggested by IAEA is [11]:
      Y=L(G/N).                                                                (1)
      Y = cost loss due to health effect per man-Sv,
      L = life shortening per man-Sv (man-year),
      G = gross national product,
      N = national population.
The emergy loss per man-Sv could be derived by equation (1) with considering Y as emergy
loss, L as risk per man-Sv and G as gross national emergy. The risk value suggested by ICRP
is shown in table 2[8].

                            Table 2 Risk value for ICRP 60[8]
                                      Worker (Sv-1)         Members of public (Sv-1)
    Fatal cancer               4.010-2                    5.010-2
    Nonfatal cancer detriment 0.810-2                     1.010-2
    Sever genetic effect       0.810                      1.310-2
    Total                      5.610-2                    7.310-2

      Base on the radiation source condition and exposure scenarios, the dose could be
evaluated by Resrad-family computer codes [12], Cap88-PC packages [13] or the fast and
conservative screen models [14, 15, 16]. The annual national emergy of Taiwan at 1990 was
evaluated to be about 2.141023 sej/yr [17]. Assume the population of Taiwan is about 23
million. Base on these data, we could easily derive the transformities of effective dose to
emergy as 5.211014 sej/man-Sv for worker and 6.791014 sej/man-Sv for public respectively.

      In ICRP no.91, development of a common approach to radiation protection that would
support informed policy and management of decision making with regard to public health and
environmental risks for the same environmental situation is shown as figure 3. The conditions
for human and non-human should be both considered.


                              Environmental radionuclide concentration(s)

                           Reference Man                   Reference fauna and flora
                          With look-up tables                 With look-up tables

                           Secondary reference             Secondary reference
                           Man (infant, child, etc.)         Fauna and flora
                                                              (as necessary)

                        Protective action levels           Derived consideration levels
                             For humans                        For fauna and flora

                 Informed policy and management decision making with regard to public
                health and environmental protection for the same environmental situation.
      Figure 3 Developing a common approach for radiological protection of human and
                                non-human organisms.[9]

1. Consideration of non-human species
       The emergy table of some natural processes was derived in literature and summarized
in table 3.[18]. If the risk to biota could be calculated, emergy loss due to radiation could be
derived. Traditional ecological risk assessment concept is to yield a limited concentration by
     CC=PNEC/SF                                                                  (2)
     CC         critical (limited) concentration,
     PNEC predict no effect concentration of toxicity,
     SF         safety factor, traditionally from 10 to 100.

       If concentration of toxicity is smaller than CC, the situation is considered not to present
a risk. Otherwise, a risk exist, requiring implementation of an action. This approach, reducing
the complex to simple, drive a great uncertainty concerning the capacity of the protection
system to effectively meet its object.
The first international recommendation is list in table 4. Due to the different appreciation of
dose promoting risk, limited knowledge on chronic exposure and uncertainties inherent to
how such radiation effects, the most recent recommendations by Russia and Canada yield

lower limits, by approximately one order of magnitude, and are still subject to modification
                          Table 3 Transformities of natural processes.
Mass emergy of Global Flows          sej/J   Plant & products             sej/J sej/g(109)
Global Solar Insolation                    1 Gross production, estuary      4,700
Surface wind                           1,496 Plantation Pine                7,511        0.1
Convective Earth Heat                  6,055 Estuarine organic matter      11,000
Oceanic rain, chemical potential       7,435 Peat                          19,000      0.36
Physical energy, rain on land         10,488 Mulberry leaves               24,000
Chemical energy, rain on land         18,199 Rain Forest Logs              32,000      0.39
Volcanic Heat                         18,000 Coal                          40,000
Global sedimentary cycle             sej/J   Corn                          83,000      1.43
Shale                            10,000,000 Charcoal                      106,000
Limestone                          1,620,000 Cotton                       860,000
Sandstone                        20,000,000 Smaller Estuarine animals 1,500,000
Coal                                  40,000 Silk                       3,400,000         72
Sedimentary Iron Ore             62,000,000 Wool                        4,400,000
Potassium fertilizer               3,000,000 Aquaculture shrimp        13,000,000

          Table 4 the first dose limit for the protection of the fauna and the flora.[19]
                       Biota                       mGy day-1 mGy year-1
                       Terrestrial plants               10          3650
                       Aquatic animals                  10          3650
                       Terrestrial animals               1           365
                       Human(for comparison)         0.0027           1

       The weighting differences of radiobiological effect in biota are of interested. For man,
that RBE value is suitable for dose calculations are well accepted. But the situation is far less
clear for fauna and flora where a large array of different RBE values have been reported,
which vary not only with species but also with effect endpoints considered. IAEA advised to
calculate dose to biota by including a weighting factor Wr according to
     Weighted absorbed dose-rate= dose-rate (Low-LET) + Wr dose-rate (High-LET).
The Wr is a function to be clarified that depends on the organism, on the dose rate, and on the
effect endpoint [20].
       To calculate emergy loss due to ionizing radiation should be wait until the final
recommendation on effect endpoints and biological effect by new ICRP task group.
2. Consideration of human being
       To assess the exposure of humans, an increase in radiation in air, water, soil and
vegetation should be predicted based on the radio-nuclides’ transport, dispersion and
deposition. The screening model is fast and conservative to ensure regulation compliance
before releasing radionuclide to environment. The dose factors defined as collective dose per
activity of selected radio-nuclides could be found by looking up tables in NCRP no.123 [15].
For example, consider the ground disposal model based on the period after administrative
control loss. Details about models and parameters could be found in the report [15]. The
annual dose factors for different pathway of selected nuclides are extracted from table D.1 in
NCRP no.123 and shown in table 5. The more accurate calculation should be based on site
specific information to precisely describe the overall exposure analysis details. There exist
many available computer packages could be used. For consideration of environmental

 justification, conservative screen model could be efficiently used for decision making about
 whether the requirement is met or more extensive calculations are needed.

  Table 5 Transformities of selected radio-nuclides and different pathway for ground disposal
                                  Direct Inhalation      Soil       Water Vegetables
       Dose factor (Sv/Bq)
       Cs-137                 4.60E-12 1.80E-16 5.90E-14 7.70E-14             9.40E-12
       Co-60                  2.20E-17 1.40E-21 3.70E-20 2.20E-19             2.40E-18
       Am-241                 6.10E-17 3.80E-16 3.10E-12 5.90E-13             2.50E-12
       I-131                     ---      ---      ---   5.60E-40                ---
       Transformity (sej/Bq)
       Cs-137                 3.12E+03 1.22E-01 4.01E+01 5.23E+01            6.38E+03
       Co-60                  1.49E-02 9.51E-07 2.51E-05 1.49E-04            1.63E-03
       Am-241                 4.14E-02 2.58E-01 2.11E+03 4.01E+02            1.70E+03
       I-131*                    ---      ---      ---   1.90E-26               ---
 * Consider thyroid risk only

 3. A case study—cement with fly ash
       Cement is an important building material in Taiwan because most of the houses were
 made of concrete reinforce. However, it had shown that production of cement consumed
 emergy about 2109 sej/g [21]. Fly-ash is often used as waste if not reused. The emergies for
 collecting and disposal are about 2107 and 4107 sej/g respectively [21]. Replace cement by
 fly-ash is not suggested to be more than 30%. Cement with flay ash can save emergy upto
 about 7108 sej/g.

            Table 6 Activity concentration of cement and flyash samples in Taiwan.
                                                                                  Unit Bq/kg
         U-series   Th-series   K-40                           U-series Th-series    K-40
Cement-1  673%      366%     7313%              Flyash-1     813%     834%    2595%
Cement-2  346%     1911%     2498%              Flyash-2     583%     627%    3786%
Cement-3  384%     1313%     1655%              Flyash-3    1692%    1994% 12511%
Cement-4  335%     1414%     2066%              Flyash-4     823%     745%    3084%
Cement-5  524%     2112%     1358%              Flyash-5    1572%     626%    1209%
Cement-6  434%      227%     1387%              Flyash-6    2015%    2223% 1678%
Cement-7  284%      198%     2284%              Flyash-7    2165%    2153% 1637%
Cement-8  206%     1910%     2235%              Flyash-8    2254%    2143% 1787%
Average 39.383.88 20.383.92 177.19.5            Average    148.66.5 141.46.5 212.310

       The natural radio-activities contained in fly-ash and cement is shown in table 6. Fly-ash
 obviously contained enriched natural radio-activities. Dose in a house of 444 m3 with
 fly-ash-cement as one of the components of concrete could be simulated by MicroShield 
 package Ver 5.01. The net dose increased is about 7.2810-11 Sv/yr/g-fly-ash. The risk is
 about 5.310-12. Emergy due to radiation hazard is transformed to be about 4.3104 sej/g.
 Compared with emergy saved, reuse of fly-ash is highly recommended because of satisfying
 environmental justification.

Conclusion and perspective
       Although it is not yet accepted as legal standards, recommendation draw towards dose
level below 10 mGy day-1 for non-human species become accepted in some countries.
Constructing a scientific framework for protecting environment is needed for public
       Emergy analysis have been used for sustainablility and resource evaluation of natural
ecological system. We found it could also be used for impact assessment. Transformities can
be derived based on the effective dose related risk and national emergy product. Although till
now, only human health risk could be considered. Emergy analysis provide a equal and fair
framework to valuate natural and industrial process. When radio-ecological risk assessment
system is well developed, radiation hazard to non-human species should be included in
transformity calculation. Right now emergy analysis is suitable to be used for TENORM
reuse/recycling evaluation. If the TENORM is disposed as waste may increase much more
environmental burden than radiation hazard induced by reuse/recycling. The comparison
could be made through emergy analysis.
       From the view point of environmental radiation monitoring, revises should be
considered because current monitoring plan is human risk oriented. How to properly make a
radio-ecological system oriented environmental monitoring plan has become a challenge in
the future.

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