Advanced directions of peaceful application of nuclear energy in the Republic of Azerbaijan

ADVANCED DIRECTIONS OF PEACEFUL APPLICATION OF NUCLEAR

ENERGY IN THE REPUBLIC OF AZERBAIJAN

A .A . G A R IB O V

Azerbaijan National Academy of Sciences, Institute o f Radiation Problems, H.Javid Avenue, 31a, Baku, Azerbaijan, A Z 1143

Tel: (99412) 4393391; Fax: (99412) 4398318; e-mail: gabulov@azdata.net

ABSTRACT

Application o f nuclear energy is the actual during last years due to depletion o f organic sources o f raw materials. Therefore, each country develops the programs on peaceful application nuclear energy and using alternative as well as other energy sources on the basis o f the analysis of fuel-energy balance and energy demand state. The Republic o f Azerbaijan has huge hydrocarbon resources and alternative energy sources. However, taking into account the fact that hydrocarbon resources can cover increasing energy demand at maximum 50 - 6 0 years and renewable energy sources can not meet large energy demand during near future then the discovering o f advanced ways on peaceful application o f nuclear energy is o f great importance.

1. INTRODUCTION

Since the seventies o f XX century, wide spectrum o f scientific researches on the discovering advanced ways on peaceful application of nuclear energy are carried out in the Republic o f Azerbaijan. Among o f them it is necessary to mark the following directions:

a) radiation modification of the properties o f polymers, absorbents, catalysts, metals and alloys, semiconductors, dielectrics, ferroelectrics and various devices;

b) radiation oil-chemistry processes; c) radiation polymerization;

d) radiation-heterogeneous processes; e) atomic-hydrogen energy;

f) scientific problems o f radiation safety and nuclear security;

g) discovering possibilities for using radiation technologies in the solution o f environmental problems; h) radiation sciences o f materials and radiation physics;

i) radiation biology and medicine;

j) application o f isotope sources in the medicine; k) application of isotope sources in oil-gas industry;

l) application o f isotope sources in radiography and different fields o f technique

It is know that radiation technology studies, develops and improves the methods, technique and devices in which ionizing sources are used. Therefore, all scientific-research works and technological applications in this field are based on radioactive sources.

The following types o f ionizing radiation sources are used in radiation technology: gamma-radiation sources 60Co and 137Cs; electron accelerators; beta-radiation sources - 90Sr + 90Yr; ionic implants; nuclear reactors or specially created radiation sources [1-3].

The following types of ionizing radiation sources are used in Azerbaijan:

a) Institute o f Radiation Problems uses gamma-radiation sources given in the table 1 and electron accelerator for scientific purposes.

2. ISOTOPE RADIATION SOURCES

Table 1.

No. Radioactive source Date of manufacture T (years) Specific activity (Ci)

1 6UCo (URJ60) 1969 5.3 3019.0 2 60Co (MRH-y-25) 1974 5.3 907.0 3 60Co (RHUND20000) 1975 5.3 285.0 4 60Co (RHM-y-20) 1969 5.3 215.5 5 137Cs (“KOLOS”) 1975 30.0 2600.0 6 Ra-226 1590.0 0.018

b) The following isotope sources use in the medicine: 60Co, 137Cs, 226Ra, "Tc, 13]I and etc. in addition there are a big variety o f X-ray apparatus.

c) Ministry o f Agriculture uses 60Co and 137Cs.

d) Oil industry uses 60Co, 137Cs, 241 Am and 241Am+Be during oil-and-gas exploration, petroleum production, petroleum processing and connected fields.

e) 192Ir uses in radiography o f materials.

f) Radioactive sources o f special-purpose use in different areas o f technique.

3. MAIN RESULTS AND RECOM MENDATIONS ON RADIATION-CHEMICAL

TECHNOLOGIES.

Main criteria for radiation-chemical technology is as following [4]:

- Used raw materials and by-products should be available, inexpensive and clean, - Availability o f energy and practical needs for radiation-chemical processes,

- Compatibility with the conditions o f process realization should be kept for nuclear reactors and radiation contours for raw materials, by-products and technological systems,

- Providing nuclear security and radiation safety,

- Providing the least power-consuming regime o f physical-chemical conditions,

- Providing a regime o f effective transformation o f radiation sources energy into the chemical energy o f - Revealing the ways for full waste recovery

Azerbaijan Republic has no nuclear technology or nuclear reactors and the main attention in the area o f radiation-chemical technology concentrated at isotope sources and electron accelerator.

At the planning o f scientific researches in the radiation technology area energy output (G), efficiency o f energy source using and process productivity are taken into account as main criteria under the condition that other parameters are kept.

Integral value o f radiation-chemical output (G) o f the products o f radiation-chemical processes is determined by [4]

G = ‘- \ g d t (1)

Here: G - integral radiation-chemical output o f molecules/100 eV; g - actual output g=dn/dE; t - irradiation time.

At t^ O , G ^ g

v = g D 10'2 (2)

Expression o f output dependence from irradiation time is determined by reaction kinetics and the conditions o f its carrying out. It is seen from expression (2) that radiation-chemical processes rate depends on two main

factors namely radiation-chemical output and absorbed radiation dose rate. Absorbed energy o f radiation field in a unit o f time at radiation-chemical processes is determined as:

— - a N (3)

dt

Where a = A5a, A - irradiator activity, 5 - geometrical factor is conditioned by configuration and positional relationship between irradiator and absorber; a - coefficient characterizing absorbent properties o f a medium;

N - molecules number in the absorbent medium.

dE

Increasing process rate could be gained by increasing value g and D . Expression -— is directly proportional

dt

with density for equal systems and therefore, radiation source energy efficiency could be obtained by increasing density o f the irradiated systems. Radiation-chemical processes optimization could be gained

dE

using g and — as well as theirs characteristic parameters.

dt

It is revealed that system efficiency for using and transformation radiation source energy is obtained with participation o f oxide catalyst [6,7].

I. Radiation-heterogeneous processes increasing the catalysts radiation-catalytic activity of oil fraction cracking.

The influence o f preliminary irradiation on catalyst activity has been carried out into two directions: 1)

2)

Creation o f structural defects and their contribution in catalyst activity. It is determined the contribution o f electron-acceptor centers in catalyst activity.

Catalyst catalyst - S

Additional proton-donor centers were created in the system o f catalyst + adsorbed substances using radiation-heterogeneous processes.

Catalyst + H 20 catalyst - S H

R - H T- 723K---- ► R , - H + Y jC , + K

1=1

where R - H is a catalyst o f oil fraction with C>9; Rj - H is liquid products o f cracking with lowest length o f chain; is gas products o f cracking; K is coke sediments.

i=l

It is determined that radiation-heterogeneous processes in the system o f catalyst + H 20 allow to create additional stable active centers for the processes o f petroleum hydrocarbons as a result o f that the benzine fractions yield is increase up to 15-20%, the content o f isofraction is increased up to 20-25%, the gas and coke by-products yield is decreased. It is determined also the optimal conditions o f catalyst activation.

1. It is developed the flowing systems for both catalyst activation and carrying out of catalytic cracking of kerosene - gas-oil stock

The diagram o f flowing system for radiation-heterogeneous processes o f zeolite containing catalyst activation at the oil cracking process o f kerosene - gas-oil stock is shown at figure 1.

I

here 1,2 are ionizing radiation sources; 3 is catalytic cracking reactor; 4 is a regenerator; 5 is a catalyst feed system; 6 is cracking products; 7 is regeneration gases. 60Co, 137Cs isotopes and other sources o f gamma- radiation can be used as radiation sources.

2. Radiation-thermal cracking of individual and oil fractions.

Radiation-thermal cracking has carried out under action o f electron stream in electron accelerator.

R - H T - 623+773K

“ MM

Radiation-thermal cracking advantages are the following: - Process temperature is decreased up to 100 - 150°C, - Increasing olefin hydrocarbons yield up to 30%, - Increasing hydrocarbon isostructures up to 15 - 20%, - Decreasing coke and gas products yield.

3. Liquid products of petroleum pyrolysis are undergoing radiation-chemical transformations under the action of accelerated electrons stream and gamma-irradiation.

Oil fractions

with boiling temperature ^ 1000 Gray T = 1 3 0 - 190°C

tar + aromatic hydrocarbons

Tar yield is up to 20 - 25 percent by weight.

Obtained tar is used at the construction materials manufacture and other fields.

4. Radiation-thermal process of ethylbenzene dehydrogenation under the action of electron stream.

2 0 ^ 5 C2H5

“ A N

E e=5 MeV; 1=40 mkA T=623+ 773K

C6yH 5 - C2H 4 + H 2

Styrene yield in the investigated temperature interval is changed in the range from 19 to 30 percent by weight.

5. Radiation-thermal dehydrogenation of kerosene - oil-gas fraction.

e

C M in+2 \j\S ” Cnu 2n (a- state)+ H 2

T=573+ 723K

Obtained a-oleflns are used at the detergent synthesis.

6. Dichlorethane dehydrogenation under the action of electrons stream.

C2H 4Cl2 e ^ C2H 2Cl2 (vinyl chloride) + n

nC2H2Cl2 _______ f _______ =_ ( - CH2Cl - CH2Cl - ) n (polyvinyl chloride) polymerization

7. Radiation dehydrogenation of paraxylol

e, T

paraxylol --- cycloparaxylol + H 2

Cycloparaxylol is obtained by radiation-chemical method is effective surfacing for semiconductor devices. 8. Atomic-hydrogen energy.

It is developed a scientific basis o f radiation-catalyst processes for the obtaining o f molecular hydrogen from water.

H 2Os c a t a l y s t

\ N

o

2

The main principles of catalyst selection for radiolytic processes of water decomposition were revealed. They are as follows:

- The presence of nonrelaxed states on the surface o f the catalyst is need in order to create strong adsorption links with a substance is subject to radiolysis,

- Catalyst band-gap width should correspond an energy value o f dissociative levels o f substances in the surface adsorbed complexes Eg > E&

- The catalyst should have crystalline structure,

- High-dispersity o f catalyst samples, i.e. the dimension o f single particles, crystals or layer thickness between hollows should be in the range o f values o f a length for transfer o f energy (R < Xn),

- Radiation and heat resistance o f the used catalysts, compatibility with the conditions for nuclear reactors or radiation-technology plants,

- The presence o f conditions for migration both nonequilibrium charge carriers and excitons; absence of atomic impurities and defects for trapping both nonequilibrium charge carriers and excitons; the ratio o f cation and anion radiuses o f catalyst for the migration o f both excitons and holes should satisfy a condition

rc/ra<0.41, at which oxide anions osculate with each other forming dense packing.

It is determined that limit values o f radiation-chemical yield of water decomposition at the presence o f optimal oxide catalysts under optimal conditions are limited by total potential yield o f nonequilibrium charge carriers and excitons in the oxide systems under the action o f ionizing radiation and they are as follows:

X G(-H20 ) = G() (nonequilibrium charge carrier)+ G0 (exciton) ~ 8.0 molecules/100 e V

H 20 3 + nonequilibrium charge carrier — ► H + OH H 20 3 + exciton + H 20 3* » / / + OH

G(H2)= G 0 (nonequilibrium charge carrier)+ G0 (exciton) ~ 8.0 molecules/100 eV

The dependence o f G(H2) on water vapor density (a) at the presence o f BeO and temperature dependence o f radiation-chemical hydrogen yield (b) at D = l l . l Gray/sec are shown in figure 2. Here (1) T=673K; (2)

T=723K; (3) T -773K '

In case o f chain transformation o f intermediate products into the end products we will have G (endproducts) > Go (nonequilibrium charge carrier) + Go (exciton).

Radiation-catalytic decomposition in the system o f CH4> CH4 + H 20 , where G(H2+CO)~120 - 150

molecules/100 eV can be an example o f such systems.

> O) o o o O) O C X o eT

The dependence o f radiation-chemical yield of molecular hydrogen at radiation-catalytic decomposition in the system o f CH4 + H 20 from methane content in the mix proportion at 300K (1), 473K (2), 773K (3), 973K (4) at D=5.62 Gray/sec is shown in figure 3.

The dependence o f radiation-chemical yield o f CO from methane content in the system o f Al20 3 + CH4 +

H20 at T=973K is shown in figure 4.

The creation o f special nuclear reactors, in which fuel elements can serve as the catalysts for obtaining hydrogen from water, is one o f the possible ways for carrying out of radiolytic processes with the purpose o f molecular hydrogen obtaining [9].

It is developed active forms of uranium-containing silicate catalysts (U 0 2)x(BeO)y (S i0 2)2 for carrying out o f heterogeneous-flssion-fragment water radiolysis and they are recommended as a fuel element at the creation o f radiolysis nuclear reactors.

9. It is developed radiation-chemical processes for both gasification and obtaining adsorbents from different types of coal and graphite.

a) It is revealed effective ways o f organic components gasification for different types o f coal. It is proposed the recommendations for radiation-chemical obtaining methods o f coke and energy carriers from coal. b) It is revealed scientific basis for adsorbents obtaining by radiation-chemical method.

10. It is revealed homogeneous and heterogeneous radiation-chemical processes of nitrogen fixation from atmosphere.

11. Using radiation-chemical processes at the solution of environmental problems.

a) It is revealed radiation-chemical processes for purification o f emissions from injurious impurities such as

SO* NOx and CO.

b) It is developed scientific basis o f radiation-chemical processes for purification o f natural gas from H 2S. c) It is revealed radiation-chemical method for purification of drinking water from chloroform.

12. It is developed radiation-chemical method for vulcanization of rubber products on the basis of butadiene-rubber. It is obtained wear and chemical resisting rubber products and they were applying in industry.

13. It is revealed radiation methods of modification of physical and physical-chemical properties of polymeric, ferroelectric, semiconductor oxide dielectrics.

The results of physical properties modification for polymeric, ferroelectric, semiconductor

oxide dielectrics under the action of ionizing radiation are given in the tab le 2.

No. Carried out researches Observed events and results 1. Converted Ge has been irradiated

by accelerated electrons and then annealed

The canducüvity o f Ge is changed at lighting. The effect depends on primary density o f defe cts, temperature and lighting

intensitv. 2. GaAs has been irradiated by

accelerated electrons and then cooled at different temperatures

The transition ohmic state to low ohmic state is observed o f conductivity from high under cooling o f irradiated GaAsup to SOK

3. Irradiation o f Si and Ge photocells bv electrons

Radiation resistance o f Si and Ge photocells is increased

4. Irradiation o f GaTe, GaS, GaS(Er) by y-rays

Under irradiation by high doses o f y-radiation the hole density in GaTe, GaS, GaS(Er) is

decreased and under small doses is possibility to increase hole density

5. irradiation o f B203n BeO, Al - Si, Sİ02 oxide dielectrics, ferroelectrics by y - rays

Energetic levels o f radiation defects have been determined. Low dose effect is observed. Interrelation between defect

formation energy and Egis determined The methods for control o f defect formation, recombination, localisation and surface diffusion processes have been developed.

4. RADIATION TECHNOLOGY FOR TREATM ENT OF FOODSTUFF AND

BIOLOGICAL SYSTEMS.

It is developed and introduced radiation methods for presowing treatment o f agricultural seed (such as wheat, cotton, tobacco-plant, vegetables and etc.). These methods allow to increase final efficiency from 10 to 30%. Radiation treatment o f herbs is carried out and as a result o f this the shelf life is increased. It is planed to expand the application o f radiation treatment technology for foodstuff.

5. HYDROGEN SAFETY OF W ATER-COOLED NUCLEAR REACTORS.

Existing conception o f hydrogen safety o f water-cooled nuclear reactors based mainly on the following criteria:

• Radiolysis processes into the core are characterized by the components radiolysis parameters being in the reactor environment (H20 - G(H2) ~ 0,45 m olecules/100 eV);

• Solid materials do not influence on radiolytic processes;

• The acceptors injection prevents the accumulation o f explosive gases; • Temperature factor does not influence on radiolytic processes;

The following additional processes are taken into account during emergency state o f nuclear reactors: • Steam radiolysis;

• Vapormetal reaction

Actual operating conditions of nuclear reactors are characterized by high concentration o f explosive gas mixtures into the reactor and untimely breakdown o f the materials.

It is necessary to reveal the regularity o f hydrogen accumulation during radiation, thermal and radiation- thermal heterogeneous processes in the contact o f constructional materials (Zr, Zr + l%Nb, Al, stainless steel) with water for safety operating regime o f nuclear reactors.

The following experimental results have been determined:

- Emitting secondary electron irradiation from metal, formation o f surface active states and transfer o f additional energy in the contacting environment have happen during the influence o f ionizing radiation on metal materials:

Me -► es + S (es is secondary electron irradiation, S is surface active states es + H2O -► H2 + ...

dN H, # . •

--- — = G ( H 2) • VH 0 • D (here, G (H2) is hydrogen yield; VH20 is water volume; D is absorbed dose rate

d r

D H20 = (pH20 / pM) EH 20 • D (y) (here, pH20 and pM are mass absorption o f water and metal *

respectively; EH20 is mass part o f water in the metal-water system; D (y) is dose rate). Absorbed dose rate is determined in heterogeneous systems as follows:

D het = D H20 + A D

p

A D = Kn • S/V

(here, A D is absorbed dose rate is connected with secondary electron irradiation and Kn is a constant is characterizing secondary electron emitting).

Heterogeneous processes o f water decomposition: Wr = Kn • S/V

G(H2) K r x S/V D0 + K n * 5 W

As a result o f the heterogeneous processes contribution at T = 300K, the gain AG for system Zr-H20 is as follows:

AG = 0,11 -^0,16 molecules/100 eV

The following processes happen at T>473K in Me-H20 system: Me + oxidation products MeO — ► H20

Me-MeO \ K T

H2 + products (radiation-catalytic decomposition o f water) Me + H20 — ► MeO + H2 (vapormetal reaction)

H + H20 — ► H2 + OH (thermal second processes o f chain development) WPT (H2) ^ WP (H2) + WT (H2)

Kinetic curves o f hydrogen accumulation at the heterogeneous processes with contact of Zr (1-3) and (4) Zr+l%Nb with water are shown in figure 5. Here thermal (1) at T = 473K; radiation-thermal at T = 473K (2), T = 773K (3), T = 873K (4).

The regularity o f WPT (H2) = f (pH20 , D , T) is determined.

The amount o f molecular hydrogen is determined for the active zone o f nuclear reactor at absorbed dose rate y- and (3-irradiations D = 125 watt kg-1 at T < 573K in 1 kg o f coolant.

No. Temperature, K Water density, mg/cm3 Gamma-Radiation power, Wkg'1 Hydrogen accumulation rate, W(H2), g kg''hour'1 1 300 1 x 103 125 0.05 2 473 5 125 0.05 3 573 5 125 0.39 4 773 5 125 39.21 5 923 5 125 54.13

The accumulation o f defined part o f hydrogen as a hydride in Zr, Fe, A1 metals happens at specified regimes (T, pH20 , Me). Hydride formation leads to the embrittlement o f metals and their breakdown.

6. THE CONTRIBUTION OF RADIATION-HETEROGENEOUS PROCESSES DURING

THE OXIDATION FAILURE OF METALS IN THE CONTACT WITH HEAT CARRIER

(H20 ) .

The surface oxidation in 2 stages happen as a result of ionizing radiation influence on metals (Zr, stainless steel, Al, Zr + l%Nb).

1. oxidation area with formation protective oxidation layer at the surface Me-MeO 2. catastrophic oxidation o f metal

Kinetic curves of Zr+l%Nb allow oxidation at radiation-thermal (D=7.16 Gray/sec), (1) T=473K;

(3) T=873K; (5) T=1073K; (6) T=1273K (o) and thermal (2) T=873K; (4) T=1073K; (6) T=1237K

(û) processes in the contact with water are shown in figure 6.

The dependence o f specific surface for Zr - Z r02 system from oxide phase quantity (in semi-logarithmic coordinates) on the zirconium surface at radiation-thermal oxidation o f Zr in the contact with water at T=873K; pH20 = 5 mg/cm3, D=5.98 Gray/sec is shown in figure 7.

The presence of discrete states in the anion sub-lattice and the formation o f high-porous oxide layer lead to the catastrophic oxidation of metals.

Development new methods o f radiation-oxidation treatment o f metals for getting high stability o f metals. The purpose was the creation of stable protective oxide film. Stable oxide film has to be characterized by the following parameters:

1. Low level o f defect concentration in anion sub-lattice,

During scientific researches has been established that it is possible to get high stable protective oxide film as a result o f preliminary oxidation treatment o f zirconium in the contact with water at the specified regimes. Zr + H2O2 --- v n i ► Zr-Zr02 + H2

\ J \ )

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