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Webserver Date: 23-November-2017

Nuclear India

 
 
Published by the
Department of Atomic Energy
Government of India
Vol. 35/No. 7-8/Jan.-Feb. 2002
Manufacturing Technology Development of Roof Slab Sector of Prototype Fast Breeder Reactor (PFBR)

 

 

 

It was necessary to develop manufacturing technology for some of the critical components of PFBR on account of different design features and large scale up factor compared to Fast Breeder Test Reactor (FBTR) in operation at IGCAR, Kalpakkam. One such components is Roof Slab (RS).

 

RS is a large box type annular structure made from boiler quality carbon steel material with controlled chemistry and supplementary mechanical properties. RS consists of top and bottom plates which are inter-connected by inner and outer shells and radial stiffner plates. The diameter/height/weight of RS are 12.9 m/1.8 m/250 t. Sixteen penetrations are provided for supporting various components. The bottom plate and vertical shells of the penetrations are cooled, by forced circulation of air through cooling passages inside roof slab.

 

The component safety classification is class 1 (highest) and the manufacturing requirements are very stringent. The manufacture of RS involves the following important operations:-

  1. Rolling and welding of shells to close profile tolerances of 0.2% on radii.
  2. Post weld heat treatment of the thick flanges.
  3. Controlling distortion on Carbon steel/stainless steel/dissimilar metal welds to achieve close tolerances.
  4. Integration of sectors.
  5. Helium Leak testing.
  6. Machining of flanges to achieve very close tolerances on flatness, parallelism, perpendicularity, by special purpose machines.
  7. Dimensional Measurement by electronic cordinate determinate system.
  8. Filling heavy density concrete (250 t) in the roof slab for radiation shielding.
  9. Shop and site fabrication due to transportation limitations by rail & road.

75 degree full size sector (weight 40 t) is chosen for developing manufacturing technology. Shop and site manufacturing features have been adopted in the manufacture of the above sector.

 

M/s. L&T, Hazira have successfully completed the development and the same is ready for despatch.

 

Indigenous development of materials for Prototype Fast Breeder Reactor:

 

Structural materials chosen for Prototype Fast Breeder Reactor (PFBR) should be compatible with liquid sodium, should have adequate high temperature mechanical strength, good weldability, freedom from sensitization in case of austenitic stainless steel in welded condition and available in design code. The core structural materials should be resistant to radiation damage also. Requirements for the steam generator (SG) materials, in addition, include resistance to aqueous stress corrosion cracking (both chloride and caustic) and decarburisation. Alloy D9 (15 Ni–14Cr–2 Mo+Si+Ti) with 20% cold work has been chosen for clad and wrapper, stainless steel (SS) 316LN for hot leg (>673K) components, SS 304 LN for cold leg components (<673K) and modified 9 Cr-1 Mo steel for Steam Generators (SG).

 


Buckling of inner vessel model under mechanical load

 

Specifications for PFBR materials are more stringent than ASME standards. The chemical composition is controlled within close limits to avoid scatter in properties and in turn scatter in constitutive models to facilitate inelastic analysis. Lower limits are specified for residual elements such as sulphur, phosphorous and silicon to improve weldability and on the inclusion content to ensure a high degree of cleanliness. Grain size specification is based on optimum high temperature creep properties and for facilitating ultrasonic examination for austenitic stainless steel. Most of the materials used in the construction of Fast Breeder Test Reactor (FBTR) were imported. For PFBR, it has been decided to develop the indigenous sources for the supply of materials for the major components. These development projects have been undertaken by IGCAR with public sector undertakings and private industries.

 

There are 1758 core sub-assemblies requiring initially 50,000 fuel clad tubes of 6.6 mm OD x 0.45 mm wall thickness, 2700 mm long and 10,000 radial blanket tubes of 14.33 mm OD x 0.6 mm wall thickness 2400 mm long with the annual requirement of 10,000 and 3000 respectively in D9 material. These tubes should be of very high quality to withstand a burn up of >100,000 MWd/t. The tube manufacturing quality standards are stringent compared to heat exchanger tubing for example, as the wall thickness is quite small, the inclusion contents allowed are much lower than for 316 LN & 304 LN to minimize radiation embrittlement and sodium attack on inclusions. A number of laboratory melts of D9 were produced at IGCAR to optimize melting, casting, forging and solution annealing treatments. Ti/C ratio of 6 has been selected for the first core. Based on the laboratory studies commercial heats were produced at M/s. Midhani. Clad tubes meeting chemical, mechanical, ultrasonic and eddy current requirements have been produced successfully at Nuclear Fuel Complex (NFC). Initially 700 D9 material hexcans of 131.6 mm across flat (outer) x 3.2 mm wall thickness x 3000 mm length are required and 200 annually. Feasibility of manufacturing hexcans of FBTR size has been demonstrated and the procurement of necessary equipment for manufacturing PFBR hexcan at NFC is underway.

 

Two thousand tonnes of SS 316 LN & 304 LN plates in widths of 3 m, length 8 m and thicknesses varying from 5 to 120 mm are required for Nuclear Steam Supply System components. With the modernization and upgradation of technology carried out by some of the steel plants, it is possible to manufacture these high quality steel plates. Major difficulty lies in obtaining the desired sizes to limit the number of welds on large diameter reactor assembly components. SAIL has facilities at Alloy Steel Plant for the production of SS and modified 9 Cr-1 Mo steel. However, due to the limitations of the rolling facilities, presently the solution annealed plates of 1400 mm width, 4 m length and 12 mm thickness can only be produced at ASP. The possibility of producing plates of larger dimensions by combining alloy melting facilities at ASP with rolling at Rourkela Steel Plant (RSP) was explored. It required upgradation of furnace at RSP to carry out solution annealing of SS and normalisation of modified 9 Cr-1 Mo steel plates. The plates of 2 m width, 8 m length and 30 mm thickness in SS, modified 9 Cr-1 Mo and A48P2 (carbon steel plates required for top shields) are under production at SAIL. 316 LN and modified 9 Cr-1 Mo steel slabs meeting stringent specifications are also under production at ASP and will be rolled at RSP shortly to produce the plates.

 

Forgings are needed in SS316 LN and modified 9 Cr-1 Mo in various shapes and sizes. Development of SS 316 LN tube sheet forgings (1600 mm OD, 400 mm ID x 160 mm thickness) required for Intermediate Heat Exchangers (IHX) meeting the desired chemical, mechanical and Non-Destructive Experiment (NDE) requirements have been completed successfully. SG tube sheet disc forging (1250 mm dia x 260 mm thickness) and ring support forging (1510 mm OD/1125 mm ID x 85 mm thickness) in modified 9 Cr–1 Mo steel meeting all the requirements including Nil Ductility Transition temperature (RTNDT) and NDE requirements have been produced successfully at M/s. Midhani. Presently the development of dished end forging (1250 mm dia, 90 mm thickness) with integral nozzles is in progress.

 


SS316 LN tube sheet forgings for heat exchangers

 


Modified 9 Cr-1 Mo steel seamless tubes successfully produced by combining facilities at M/s Midhani and Nuclear Fuel Complex are under use during manufacture of SGTF Steam Generator

 

Modified 9 Cr-1 Mo steel seamless tubes of 23 m fixed length of size 17.2 mm OD and 2.3 mm wall thickness required for SG have been successfully produced by combining facilities at M/s. Midhani and NFC. Material meeting stringent requirement has been produced at M/s. Midhani employing electroslag remelting. The material was converted into tubes of 23 m length successfully by modifying some of the existing facilities at NFC. Permissible variation in wall thickness was limited to +20%, -0% and wall thickness eccentricity was limited to 5%. These tubes are now being used in the manufacture steam generator meant for 5.5 MWt steam generator test facility. Seamless tubes for IHX in SS 316 LN material of 19 mm OD x 0.8 mm wall thickness in fixed lengths of 8 m were also successfully produced at NFC. Tolerance on wall thickness was limited to + 10%. These tubes have been successfully used in development of IHX tube to tube sheet weld qualification mock up block.

 

Manufacture of components envisages extensive use of Manual Metal Arc (MMA) and Tungsten Inert Gas (TIG) welding processes. Consumables are required to join 316 LN/304 LN and modified 9 Cr-1 Mo steel, while D9 clad tubes to end plug in 316 LN are welded without filler metal. For welding SS 316 LN and 304 LN components, 16-8-2 filler wire for TIG welding and 18-12-2 electrodes for MMA welding have been selected. Basic coated, modified 316 non-synthetic welding electrodes are being developed. The most critical requirement is the achievement of toughness values in as welded and after thermal ageing while ensuring good slag detachability. The development of these electrodes is in advanced stage at two manufacturers works. Development of 16-8-2 and Gr.91 filler wires required for GTAW welding of Stainless Steel & modified 9 Cr–1 Mo steels respectively has been taken up through M/s. Midhani. Weld deposit chemistry along with the mechanical properties has been specified, as against only chemistry requirements as per AWS specifications. Detailed studies were carried out to know the loss of carbon and nitrogen elements during welding process. Based on these losses, chemistry of welding wire was optimized. GTAW wires of 1.6 & 2.1mm diameter in 16-8-2 and Gr 91 wires are under testing.

 

Various materials produced in the country are undergoing extensive testing at the Materials Development Laboratory at IGCAR to generate the long term data. The exercise of taking up indigenous development of materials has given the confidence that major materials required for PFBR can be procured from indigenous sources.

 

V. K. Sethi, S. L. Mannan & S. C. Chetal
(Source: IGC Newsletter Vol. 49)

 

Techonological Innovations in Desalination
P. K. Tewari and B. M. Misra
Desalination Division,
Bhabha Atomic Research Centre

 

 

The cost of desalted water depends on three factors namely, energy input, depreciation and interest and operation and maintenance cost. Each of the three components contributes roughly one third to the total water cost. The cost of desalted water is coming down due to continued R&D and technological innovations in both thermal and membrane desalination. In the field of thermal desalination, efforts are directed towards utilizing the low grade heat and the waste heat as energy input for desalination, lesser chemical treatment and the advantage of scale up to higher capacity as a cost reduction strategy. In membrane desalination, work is being carried out on newer pre-treatment methods such as use of ultrafiltration, energy reduction using energy recovery devices and higher membrane life from better quality membranes. Work is pursued on hybrid desalination for producing different quality of product water for process industries and for potable use at lower cost.

 

Table 1 gives the specific capital cost and desalted water cost for seawater desalination for the year 1980-2000. A projection for the year 2010 is also given. It is expected that the specific capital cost of seawater desalination plant will come down in the range of US $ 500-700/daily m3 and water cost in the range of US $ 0.5-0.7/m3 by the year 2010. The cost for brackish water and effluent treatment by membrane processes are known to be even lower.

 

Table 1: Seawater desalination cost:

 

Year Capital Cost
(US $/daily m3)
Water Cost
(US $/m3)
1980 1500 1.25
1990 1000-1200 1.0-1.2
2000 800-1000 0.8-1.0
2010 500-700 0.5-0.7

 

Desalination Division of BARC has been engaged in R&D on desalination since 1970's. The desalination activities were part of a programme of setting up a number of demonstration plants for the energy intensive processes such as desalination of sea water, electrolytic production of hydrogen and electro-thermal production of phosphorus. These activities are presently termed by IAEA as "Non-Electrical Application of Nuclear Energy". The activities on desalination in the beginning were based on thermal processes. Later the programme of membrane processes was also included in the 1980's when this process showed commercial viability.

 

Table 2 gives the list of the pilot plants installed and operated/operating. These plants provided useful design data for larger capacity plants and for bringing in further technological innovations.

 

Table 2: Pilot plants installed and operated so far:

 

Thermal
15 m3/d MSF experimental facility
30 m3/d low temperature evaporation unit
425 m3/d MSF plant
1 m3/d thermo-compression desalination unit
Membrane
3 x 30 m3/d brackish water RO plants providing drinking water in villages of Andhra Pradesh, Gujarat and Rajasthan
50 m3/d RO industrial effluent treatment plant at RCF
15 m3/d RO-DM plant at VECC for production of low conductivity water
2 x 10 m3/d RO units for treatment of radioactive liquid effluents
24 m3/d NF plant for a phar-maceutical industry
40 m3/d SWRO plant at Trombay being upgraded to 100 m3/d capacity

 

Coupling of 6300 m3/d hybrid MSF-RO plant with PHWR (MAPS, Kalpakkam):

 

In order to gainfully employ the years of experience and expertise in various aspects of desalination activity on laboratory scale/pilot scale and to bring down the cost of water by scaling up, BARC has undertaken installation of a hybrid desalination plant as a demonstration project coupled to 170 MW(e) PHWR station at Kalpakkam, which would be good enough to meet the dual needs of process water for nuclear power plant and drinking water for the neighbouring people.

 

Nuclear Desalination Demonstration Project (NDDP) at Kalpakkam aims at demonstrating safe and economic production of good quality water by nuclear desalination of seawater and comprises 4500 m3/d Multi-Stage Flash (MSF) and 1800 m3/d Reverse Osmosis (RO) plant. MSF plant uses low pressure steam from Madras Atomic Power Station (MAPS), Kalpakkam.

 


Nuclear Desalination Demonstration Project (NDDP) at Kalpakkam

 

The objectives of the NDDP (Kalpakkam) are as follows:

  1. To establish the indigenous capability for the design, manufacture, installation and operation of nuclear desalination plants.
  2. To demonstrate the safe and economic production of water.
  3. To generate necessary design inputs and optimum process parameters for large size nuclear desalination plant (10 MGD).

The hybrid plant is envisaged to have a number of advantages:

  1. A part of high purity desalted water produced from MSF plant will be used for the makeup demineralised water requirement (after necessary polishing) for the power station.
  2. Blending of the product water from RO and MSF plants would provide requisite quality drinking water.
  3. The RO plant will continue to be operated to provide the water for drinking purposes during the shutdown of the power station.

The 6300 m3/d combined MSF-RO nuclear desalination project is located between MAPS and proposed PFBR at Kalpakkam. The MSF plant uses the required quantity of Low Pressure (LP) steam for seawater desalination. To avoid any chance of ingress of radioactivity (tritium) to MSF process and product water, an isolation heat exchanger between MAPS steam supply and the brine heater of MSF has been incorporated. The LP steam is tapped from the manholes in the cold reheat lines after HP turbine exhaust from both the nuclear reactors (MAPS-1&2). The moisture content is removed through a moisture separator. The steam is sent to intermediate isolation heat exchanger to produce process steam for brine heater of the MSF plant. It is designed to keep the steam temperature in brine heater below 130oC to avoid scaling on the tube side. The condensate from the isolation heat exchanger is returned back to the deaerator section of the power station. Adequate provisions for monitoring and control have been incorporated for isolation of the steam supply in case of shutdown of the power station or desalination plant.

 

NDDP requires around 2000 m3/hr of seawater. After detailed study, it has been decided to use process cooling water from MAPS outfall as a source of seawater supply for NDDP. Normally, the cooling water discharge has no debris since the intake water passes through the trash rack and travelling water screens. It is reported to have less biofouling potential.

 

Useful design data are expected from the plant. This will also help in scaling up and taking the advantage of the economy of scale to larger size (10 million gallon per day) commercial plants.

 

India will share the operational and maintenance experience of the NDDP with the member states of IAEA.

 

Low temperature evaporation plant utilizing waste heat from research reactor (CIRUS):

 

As the energy cost contributes about one third of the total water cost, efforts are directed towards the utilization of waste heat which is available free of cost. Desalination Division has an active programme to study the possibility of use of large amount of waste heat of nuclear research reactor and PHWR for seawater desalination using low temperature evaporation technology. The know-how for the desalination plant based on Low Temperature Evaporation (LTE) utilizing low-grade waste heat (as low as 530C) for producing pure water from sea water was developed. A 30 m3/d pilot plant was installed and operated for endurance test. This unit is eco-friendly because it does not require exhaustive chemical pre-treatment.

 

Such plants would be ideal for industries where waste heat is available in the form of flue gas and process heat. It is an attractive alternative for producing pure water from high salinity or sea water for the rural areas where waste heat from DG sets/solar energy is available. Consultancy services were provided to the Union Territory of Lakshadweep in utilizing the waste heat of the DG sets for LTE desalination. A 10 m3/d LTE desalination plant utilizing the waste heat of 400 KVA generator has been operating in Kavaratti for producing pure water from sea water.

 

The total water requirement for the LTE desalination plant is quite high. Work has been initiated to bring down the total water requirement by 20-30 times by coupling a cooling tower and recycling the condenser water. It will be a totally indigenous, reliable and rugged desalination system. Energy requirement can be further brought down by employing more number of effects. The design of such plants of larger capacity for Advanced Heavy Water Reactor (AHWR) program has also been taken up. Studies are undertaken towards utilizing low quality waste heat from the steam and feed water system of AHWR for producing De-Mineralised (DM) water from high salinity water or sea water.

 

Innovative Developments:

 

  1. Improved heat transfer for MED: Basic studies carried out earlier on a horizontal tube thin film (HTTF) boiling indicate that the bubble nucleation in the thin film on the tube takes place with rapid bubble growth. The application of forced convection due to liquid spray on the tube increases the convective contribution and results in early removal of bubble adhering to the surface which increases bubble frequency. The overall heat transfer co-efficient in the range of 3-4 kW/m2K was obtained which is about three times the heat transfer coefficient as compared to submerged tube evaporator. High heat transfer coefficient implies low heat transfer area requirement and in turn low capital cost. The data collected on the fluid flow and heat transfer aspect of the boiling in a thin film were used in the design and installation of 1 m3/d HTTF desalination unit for MED . Low temperature vapour compression desalination plants of 50-200 m3/d capacities are suitable for providing drinking water in the rural/water scarcity areas and process water/boiler feed water for industries. MED with mechanical vapour compression is ideal for areas where only electrical energy is available and sufficient cooling water is not available. MED with thermocom-pression are suitable for the regions where high pressure (5-10 bar) steam is available.

     

    It produces low conductivity water directly from the high salinity water. It is planned to carryout high temperature MED studies using Nano-Filtration (NF) in the upstream for the makeup feed pre-treatment. Laboratory data on NF indicate substantial reduction of the scale causing constituents in seawater when it is passed through it. The use of NF permeate as makeup feed to MED will provide high Gain Output Ratio (GOR) by operating it at higher top brine temperature. NF helps in removing the total hardness thus, reducing the energy and chemical consumption.

  2. Improvements in reverse osmosis for desalination: The RO desalting industry is looking for continued reduction of the cost of desalted water. This calls for the development of better quality membranes offering higher output while maintaining the optimum salt rejection, reduced chemical pre-treatment, longer membrane life and low energy requirement.

     

    R&D work on indigenous development of advanced polyamide based Thin Film Composite (TFC) membranes has been undertaken at the Division to meet these objectives. After successful development of brackish water RO desalination plants to demonstrate the utility of RO desalination systems in meeting the drinking water needs of brackishness affected villages, a 40 m3/d seawater RO plant has been setup in Trombay for producing drinking quality water. The plant is being upgraded to 100 m3/d capacity. The conventional pre-treatment system has been setup, which includes chlorination, clarification, media filtration, chemical dosing and cartridge filtration. It is planned to introduce membrane based pre-treatment system using ultrafiltration (UF) and Nano-Filtration (NF). The adoption of UF and NF is envisaged to reduce the elaborate feed treatment for removal of scaling constituents, suspended impurities, organics and microbial load. UF installed upstream of RO is very effective as a pre-treatment setup. Preliminary investigations have been carried out by using NF as a means to improve the performance of desalination plant. NF reduces the hardness ions of calcium, magnesium and sulfate to a great extent. It also partially reduces the TDS of seawater. This results in reduced seawater treatment and higher recovery.

     

    A brackish water RO plant is setup in Rajasthan in cooperation with Defence Laboratory, Jodhpur, for providing drinking water to the villagers from high salinity brackish water sources. Another RO plant is to be set up at village Chadi (Barmer) for removal of excess fluoride and nitrate apart from brackishness.

  3. Effluent treatment and zero discharge: Due to an increasing demand for good quality water, attempts have been directed to treat the waste water for reuse and recycle. The approach is further reinforced by the need to preserve the environment and to follow a zero discharge concept wherever possible. R&D work in the field of thermal and membrane processes has been pursued for the treatment of waste water and removing pollutants from the effluent stream for safe discharge into environment and recovery of significant fraction of the water for reuse. Selection of a process for treatment of a particular waste water is based on product requirements, influent water characteristics and cost. Industrial waste water often is the combined product of a number of different manufacturing processes in the complex. The membrane processes that are useful for waste water treatment include: microfiltration, ultrafiltration, nanofiltration and reverse osmosis. The suspended solids in waste water are successfully removed by microfiltration. Ultrafiltration is useful in separating macro-molecules and the sub-micron particles including oil emulsion and very large molecules such as polymeric compound having a polymeric weight of 1000 and above. Nanofiltration is capable of separating molecules in the range of 300-1000 molecular weight. It also helps in selective separation of low molecular weight organics from salt solution. Reverse osmosis has very small pore size (5-10 A) suitable for removing ions and molecules. Laboratory scale studies are continuing on development of such membranes and their performance evaluation. As no two waste waters are exactly alike, it is necessary to carryout laboratory evaluations to determine the flux rate under different temperatures and pressures for individual waste water samples.
  4. Barge mounted desalination unit: Barge mounted desalination plant offers a suitable choice for remote locations and small islands or coastal communities where the necessary manpower and infrastructure to support desalination plants are not available. It can be installed anywhere anytime depending on the need in coastal regions. It can supply potable water to remote coastal regions or islands where both good quality water and the energy sources are severely lacking. It does not require intake or outfall infrastructure. It is planned to setup a barge mounted 50 m3/d seawater RO plant. The preliminary details have been worked out. The design considerations of a barge mounted plant are different from those of land based plant. The limitations due to marine environment including conditions of sea and wind, space availability, weight limitations and technical considerations including pump cavitation and vibration are considered in the design stage.

Conclusion:

 

The development work has generated capability in the country to design, fabricate, commission and operate small and large size desalination plants. Efforts are now directed towards reducing the cost of desalted water through technological innovations. In the case of thermal processes, this calls for capital cost reduction through heat transfer enhancement and use of cheaper materials, low grade or waste heat utilization and least chemical pre-treatment. Today, production of boiler quality water and high quality process water from sea water desalination is cheaper than that produced from conventional DM plant using raw water where the raw water contains 500 ppm or more salinity. In the case of membrane processes, attempts are continued towards the development of better membranes, least pre-treatment, longer membrane life and reduced energy consumption. Effluent treatment and water reuse through desalination route, as a step towards zero discharge, appears promising. The development of barge mounted desalination units will go a long way as a means of pure water supply to remote coastal areas anywhere and at anytime. The technological innovations in desalination would lead to its large scale application and provide opportunities for the socioeconomic development of water scarcity areas and large coastal arid zones of the country.

 

Radiation Processing of Food Products
Arun Sharma
Head, Food Technology Division & Project Manager,
Food Irradiator Project,
Bhabha Atomic Research Centre

 

 

Food security of a nation, to a large extent, determines its economic stability and self-reliance. With the fast growing population, shrinking arable land and increasing costs of agricultural inputs, we should not only aim to increase our agricultural productivity but also effectively preserve and conserve what is produced.

 

Peaceful uses of atomic energy include generation of power and utilization of radio isotopes and radiation for the benefit of industry, agriculture, food and medicine. Atomic energy has played an important role in improving crop productivity by providing mutants with desirable agronomic traits. It is also destined to play an important role in conserving what farmers produce with their hard work. Radiation processing can complement agricultural productivity by improving food security, food hygiene and trade in food, both national and international.

 

Insects and microbes cause major economic losses to stored crops. Many of our food products are contaminated with disease causing germs and toxin producing molds. Our agricultural commodities cannot find international markets without improvement in microbial quality and/or getting properly treated to overcome quarantine barriers. Fumigants currently being employed for disinfestations and disinfection are not only less effective but also leave harmful residues on the treated commodities. These fumigants are also harmful to the environment. The fumigants are now being phased out around the world.

 

Preservation of food by radiation:

 

Preservation of food by radiation involves controlled application of energy of ionizing radiations such as gamma rays, X-rays and accelerated electrons to agricultural commodities, foods and food ingredients, for improving storage life, hygiene and safety. Radiation processing of food employs either gamma rays emitted by radio nuclide sources such as cobalt-60 or high energy electrons and X-rays generated from machine sources.

 

Technological benefits:

 

Major technological benefits that can be achieved by radiation processing of food include:-

  1. Disinfestation of stored products.
  2. Disinfestation of fruits and vegetables for quarantine.
  3. Inhibition of sprouting in tubers, bulbs and rhizomes.
  4. Delay in ripening and senescence in fruits and vegetables.
  5. Destruction of microbes responsible for food spoilage and
  6. Elimination of parasites and pathogens.

On the basis of dose requirements these benefits could be classified into low dose, medium dose and high dose applications (Table 1):

 

Table 1: Applications of Radiation Processing

 

Low dose applications (Less than 1 kGy) Medium dose applications (1-10 kGy) High dose applications (above 10 kGy)
Inhibition of sprouting in potato and onion Elimination of spoilage microbes in fresh fruits, meat and poultry Sterilization of food for special requirements
Insect disinfestation in stored grain, pulses and products Elimination of food pathogens in meat and poultry Shelf-stable foods without refrigeration
Destruction of parasites in meat and meat products Hygienization of spices and herbs Gray is the unit of absorbed dose of radiation = 1Joule/kg. The old unit of dose is rad (lGy=100 rad)

 

Advantages of Radiation Processing of food:

 

Preservation of food by ionizing radiations offers several advantages listed below. These advantages acrue from the highly penetrating nature of the ionizing radiations:-

  1. It is a physical non-additive process.
  2. It causes minimal changes in food.
  3. Preserves food in natural form.
  4. It is a cold process and does not destroy heat-labile aroma constituents.
  5. It is highly effective.
  6. Can be applied to pre-packed food.
  7. Eco-friendly process and does not leave harmful residues and
  8. Process is safe to workers.

Though irradiation offers several advantages to food processors and allows them to supplement or complement the existing technology, it is not a panacea. It can be applied only to those foods that have been established by experimentation to benefit from the technology. It cannot inactivate many viruses or enzymes in food. Therefore, for certain processes it may need to be coupled with mild heat treatment such as blanching to get rid of these enzymes and viruses.

 

Wholesomeness and Safety Aspects:

 

No other method of food processing has been subjected to such a through assessment of safety as the radiation processing. The various aspects of wholesomeness and safety of radiation processed foods have been studied in great detail. These include investigations on:-

  1. Possibility of induced radioactivity.
  2. Microbiological safety.
  3. Safety of chemical changes.
  4. Nutritional adequacy.
  5. Animal feeding.
  6. Human trials.

At the energies of the gamma rays from cobalt-60 (1.3 MeV) and those recommended for using X-rays (5 MeV) and accelerated electrons (10 MeV), there is no induction of radioactivity. The microbiological aspects of radiation processed foods have been studied in detail. None of these studies have indicated that foods preserved by radiation pose any special problems in relation to microflora. It has been found that there are no unique radiolytic products formed and free radicals in the system disappear depending on the nature of the commodity and its post-irradiation storage and treatment. In fact, the chemical differences between radiation processed foods and non-irradiated foods are too small to be detected easily. Though rough composition of food remains largely unchanged, some losses in vitamins may be encountered. However, these losses are often minor and could be made up from other sources.

 

Animal feeding studies have been the most time consuming and expensive feature of wholesomeness testing. None of the short or long-term feeding studies and also detailed mutagenicity testing studies on animals, as well as trials on human volunteers, has revealed any adverse effect of consumption of irradiated diet. In fact, astronauts and cosmonauts have been taking radiation processed food as part of their ration on the various space flights from Apollo to space shuttle.

 

International Approval:

 

In 1980 a Joint FAO/IAEA/WHO Expert Committee on Food Irradiation (JECFI) reviewed the extensive data on wholesomeness collected up to that time and concluded that irradiation of any commodity up to an overall dose of 10 kGy presents no toxicological hazards and introduces no special nutritional or microbiological problems. An Expert Group constituted by WHO in 1994 once again reviewed the wholesomeness data available till then and validated the earlier conclusion of JECFI. In 1998 another Expert Group constituted by WHO/FAO/IAEA affirmed the safety of food irradiated to doses above 10 kGy. Codex Alimentarius Commission that sets standards for food world-wide and the World Trade Organization have also recognized the technique. In addition, a number of scientific bodies and associations have also endorsed the safety of radiation processed foods. These include, to name a few:-

  1. American Medical Association.
  2. The American Gastroentrological Association.
  3. American Dietetics Association.
  4. American Meat Institute and
  5. Institute of Food Technologists.

Approval of radiation processing of food in India:

 

In 1994 Government of India amended Prevention of Food Adulteration Act (1954) Rules and approved irradiation of onion, potato and spices for domestic market. Additional items were approved in April 1998 and in May this year (Table 2):-

 

Table 2: Items of Food Permitted for Irradiation under Indian Prevention of Food Adulteration Act (PFA) Rules

 

Sr. No. Name of Food Dose of irradiation (kGy) Purpose
    Min Max  
1 Onion 0.03 0.09 Sprout inhibition
2 Potato 0.06 0.15 Sprout inhibition
3 Shallots (small onion) 0.03 0.15 Sprout inhibition
4 Rice 0.25 1.0 Insect disinfestation
5 Semolina (sooji or rawa), Wheat Atta and Maida 0.25 1.0 Insect disinfestation
6 Pulses 0.25 1.0 Insect disinfestation
7 Dried sea-food 0.25 1.0 Insect disinfestation
8 Raisins, Figs and dried Dates 0.25 0.75 Insect disinfestation
9 Mango 0.25 0.75 Shelf-life extension and quarantine treatment
10 Meat and Meat products including chiken 2.5 4.0 Shelf-life extension and pathogen control
11 Fresh sea-food 1.0 3.0 Shelf-life extension
12 Frozen sea-food 4.0 6.0 Microbial pathogen control
13 Spices 6.0 14.0 Microbial decontamination

 

Radiation processed spices launched at Mumbai:

 


Dr. Anil Kakodkar, Chairman, AEC and Secretary, DAE, speaking on the occasion of the launch of radiation processed spices by SHRADDHA. Seen in the picture: Smt Prema Purao, Secretary, Annapurna Mahila Mandal, Shri. B. Bhattacharjee, Director, BARC and others

 

Annapurna Mahila Mandal launched the sale of radiation processed spices under the trade name ‘Purnanna’ at their outlet SHRADDHA at Dadar, on 24th November, 2001. Dr Anil Kakodkar, Chairman, AEC was the chief guest. Shri. B. Bhattacharjee, Director, BARC had presided over the function. Smt. Prema Purao, Secretary, Annapurna Mahila Mandal, welcomed the gathering and stressed the importance of radiation processing technology. She was confident that the use of this technology will benefit for public at large and generate employment for the needy women. She also mentioned that the stall run by Annapurna Mahila Mandal at Anushaktinagar was getting good response from the customers. Dr. Kakodkar lauded the efforts of Annapurna Mahila Mandal in launching of radiation processed spices in Mumbai and for the first time in the country. He expressed the hope that the radiation processed spices will not only cover Maharashtra and other states in India but also the export market. He assured cooperation of the scientific community to the efforts of Annapurna Mahila Mandal in taking radiation processing technology to kitchen. Shri. B. Bhattacharjee in his presidential remarks also greatly appreciated the efforts of Annapurna Mahila Mandal. He provided an overview of the advantages of the radiation processing technology for spices and its benefits to farmers and traders. Dr. (Smt.) A. M. Samuel, Director, Bio-Medical Group cleared the doubts related to safety of radiation processed foods and allayed the fears in public mind about the technology. Shri. W. M. Sonawane, Asstt. Commissioner, FDA, Thane region explained the role of FDA in licensing and sale of radiation processed products. Radiation processed spices kept for sale at the counter by Annapurna Mahila Mandal, had good consumer response.

 

Today worldwide some 40 countries including India, have approved the use of food irradiation for over 100 food items and about 30 of them are applying the technology on a limited commercial scale. In India commercial food irradiation could be carried out in a facility licensed to do so. The license could be obtained after fulfilling the requirements of the Atomic Energy Regulatory Board (AERB). A technology demonstration facility for irradiation of spices commissioned by the Board of Radiation and Isotope technology (BRIT) is at present functioning in Vashi, Navi Mumbai. Construction work on the plant for radiation processing of onion and potato started by BARC is nearing completion at Lasalgaon in Nashik district of Maharashtra.

 

Commercial Prospects:

 

Radiation processing of food and agricultural commodities can be undertaken both for export and domestic markets. For export food could be processed for shelf-life extension and hygienization. The technology can be used to overcome quarantine barriers for the export of fruits and vegetables as well as for cut flowers. Radiation processing can be used for restructuring costs of bulk commodities in export markets and for selling value added packaged commodity directly in retail markets. India has one of the world’s largest domestic markets. Huge quantities of cereals, pulses, their products, fruits and vegetables, sea-foods and spices are procured, stored and distributed throughout the length and breadth of the country. For domestic consumption radiation processing can be used to facilitate storage, movement and distribution of agricultural commodities from production centres to consumption centres and to prevent post-harvest losses during these operations.

 


Spice Plant in operation at Vashi, Navi Mumbai. The plant is a big boon to spice exporters

 

166 Ho-Ha: A New Radiopharmaceutical for Treatment of Arthritis

 

It is estimated that about 1% of the global adult population suffers from one or the other type of arthritis affecting some of the 264 synovial joints present in the human system. The total expenditure for providing medical treatment and rehabilitation of these patients could be exorbitantly high in addition to the productivity loss and social inequality.

 

There are techniques for diagnosis of synovitis (inflamation of the synovial joints). However, none of the conventional techniques for diagnosis of synovitis (inflamation of synovial joints) conclusively tell about the progression of the disease.

 

Options such as CT and MRI scan will yield comprehensive information, but these diagnostic procedures are too expensive to be used routinely. Specialized biochemical techniques can also be used for the diagnosis of certain type of arthritis. Radio nuclide imaging of the affected joint can also yield information with respect to the extent of damage caused to the cartilage and bone by the intruding synovium. Imaging of the inflamed synovial joints using radio nuclides involve the use of both non-specific and specific radiopharmaceuticals.

 

Rheumatism is a systemic disease. Different modes of treatment are available which include systemic therapy trying to slow down the inflammatory process.

 

Disease Modifying Anti-Rheumatic Drugs (DMARD) which act either by immunosuppression, immuno-stimulation or immune-modulations are used. The current line of treatment of arthritis involves any one or combinations of the above modes of therapy. These are aimed at providing pain relief and improved joint mobility. But none of these arrest the progression of the disease. The treatment practised are economical but prolonged usage and frequent dose adjustments are required. Long term use of the drugs is associated with side effects. Recently, antimetabolites have been tried with limited success.

 

Surgical synovectomy involves removal of the inflamed synovial lining. This mode of treatment is expensive, needs hospitalisation and involves long convalescent periods. Also, the expense to benefit ratio is low.

 

Radiation synovectomy offers a viable and attractive alternative for the effective management of synovitis, especially in the early stages of the disease.

 

Radiation Synovectomy (RS) involves intra-articular injection of a pemitting radio nculide of appropriate nuclear, chemical and biochemical characteristics in the form of a radiopharmaceutical into the affected synovial joint in order to counteract and control the excessive proliferation of the synoviocytes. This mode of therapy was tried several years ago with limited success.

 

Development of colloidal particles such as silicates, citrates and hydroxides of the isotopes 90Y and 169Er reduced the incidence of leakage from the joint. The radiation exposure to healthy organs due to the labelled particles escaping from the injected joint cavity was still a point of concern. The current approach is to make the particles of appropriate size and then label them with the radio nuclide of choice.

 

The mode of action of radio nuclides in therapeutic applications is due to the cytotoxic effects of the particulate radiation emitted by them while undergoing transmutation.

 

Radiation synovectomy is the invasive type of treatment for arthritis. Relief lasts for 3-4 years and, in case of recurrence, the treatment can be repeated. This method has got high potential as an alternative to the currently available modes of treatment.

 

The Radio pharmaceuticals Division of BARC has taken up a programme for the development of radio synovectomy agents. The radio isotopes of choice are the ones which can be easily produced in large quantities in medium flux reactors.

 

166 Ho (Holmium) is one of the radio nuclide selected as it has several advantages. 166 Ho was produced in Dhruva reactor and the radio nuclidicpurity of the isotope formed was estimated and 166 Ho labelled hydroxy apatite particles suitable for radio synovectomy application were successfully developed.

 

The biological evaluation of the radio pharmaceutical done at the Radiation Medicine Centre and the clinical trials conducted at the Ruby Hall Clinic, Pune, which has been practising radiation synovectomy using imported products have demonstrated that the present product could be used as a replacement for the expensive commercially available synovectomy agents. The radio isotope 166 Ho can be prepared in adequate quantities in the Dhruva reactor and hence the radio pharmaceutical could be made available to a large number of needy patients at reasonable cost.

 

The indigenous availability of this product for RS would be an important milestone and render this treatment mode widely available at affordable cost for the needy patients of our country.

 

The product is earmarked for regular deployment on a large scale through the Board of Radiation and Isotope Technology (BRIT).

 

(Source: BARC Newsletter Vol. 208)

 

HWB tie-up to market environment friendly technology:

 

Chemithon Engineers Ltd. (CEL), a joint venture of Chemithon Corporation of United States of America, has bagged an order for supply of a plant for control of particulate emission from the Gujarat Electricity Board’s Ukai thermal power station. The order is for supply of a dual flue gas conditioning system.

 

The dual flue gas conditioning technology is based on sulphur trioxide (SO3) conditioning technology of Chemithon and the ammonia (NH3) conditioning technology developed indigenously by the Heavy Water Board (HWB) of DAE. This technology is in use at HWB’s captive power plant at Manuguru in Andhra Pradesh which has demonstrated the suitability of the technology for control of particulate emission from coal based thermal power stations.

 

Successful trials have been conducted by Chemithon and HWB at the Guru Nanak Dev Thermal Power Station, Bathinda. Similar trials will be conducted at Maharshtra State Electricity Board’s Koradi thermal power station.

 

Miscellany:

 

Gamma scanning of vacuum column for manglore refinery & petro-chemicals limited:

 

The malfunctioning of a vacuum column at Mangalore Refinery & Petrochemicals Limited, Mangalore (MRPL), was resulting in production of low quality product and the company was losing about Rs 20 lakhs per day.

 

Isotope Applications Division, BARC, carried out gamma scanning of 9.5 metre diameter vacuum column for MRPL. This is the first time that gamma scanning technology has been used for trouble-shooting for such a large diameter and thick walled industrial process column.

 

A specially fabricated composite material source container-cum-collimator system was used for this work. The Company has found the damage to the column internals as per the scanning report. Successful pin-pointing of the problem by gamma scanning enabled the MRPL to reduce the shut down considerably, thus avoiding huge production loss.

 

Production of optical quality Electroless Nickel (EN) coating on copper substrate:

 

The technology for production of optical quality electroless nickel coating on copper substrate developed at BARC, is available for transfer. This technology finds applications in the areas of advanced astrophysical, directed energy weapons systems, lasers and alternative energy applications. In defence applications, a few of the products that require optical components and system are Fire control systems, Pointer-trackers, Forward Looking Infrared System, Night Vision Systems and Advanced surveillance device and others.

 

It is a material dependent and variable hardness technique suitable for production of high quality coated metal optics. It is a group of coatings. The selection of type of electroless nickel needs to be made keeping in view its end applications. This coating is nanocrystalline with grain size of 10-15 A (1-1.5 nm) and can be deposited with zero stress or slight compressive stress.

 

The four different specifications of copper available in the market for making substrates are: Commercial copper (ASTM B-846), Electrolytic Tough Pitch (ETP) copper (ASTM B5), Deoxidized High Phosphorous (DHP) copper (ASTM B-846) and Oxygen Free High Conductivity (OFHC) copper (ASTM B-170). The solution that gives Ni-P alloy coating (p-content around 10.5%) is used. One such plating solution, Ginplate Ni 422 is commercially available in three liquid concentrates.

 

The part to be plated is ultrasonically cleaned by suspending it in organic solvent. In final cleaning process acid bright dip, using Gictane Q 533 can also be used. After proper preparation of solution, parts to be EN coated are immersed in the Ginplate 422 solution for the required time to obtain the desired thickness of EN coating.

 

Details can be obtained from:

 

Head, Technology Transfer & Collaboration Division,
Bhabha Atomic Research Centre,
Trombay, Mumbai, 400 085.
Fax: 091-022-5505151
Website: www.barc.ernet.in

 

Kaiga Epidemiological Report Released:

 

The survey report, "Effects of low-dose ionizing radiation among the employees at the Kaiga Generating Station: A cross-sectional study", released recently, by the Department of Community Medicine, Kasturba Medical Collage, Manipal, Karnataka, indicates no cancer prevalence in employees of KGS and their families. Studies on neighboring population is in advanced stage of progress.

 

The objective of the epidemiological survey was to investigate whether any health hazard is associated with occupational radiation exposure. The survey covered 1553 employees of Kaiga Generating Station, 1162 spouses and 1343 off-springs of the employees. The Kaiga Station, situated in the district of Uttar Kannada, Karnataka has two units each of 220 MWe. These units had become operational in 1999 and 2000. Similar surveys have been carried out at all the operating nuclear power stations in India. The information collected is a base line which will be useful in future studies.

 

Tenth ISMAS-WS 2002:

 

Indian Society for Mass Spectrometry (ISMAS), Mumbai, in association with the Institute of Physics, Bhubaneswar, Orissa is organizing the 10th ISMAS Workshop on Mass Spectrometry, during February 25 to March 1, 2002 at Puri. With the theme "Advances in Mass Spectrometry", the workshop is aimed at introducing the subject of mass spectrometry to novices, providing the mass spect-rometrists information regarding the latest developments in the field and exposing the participants to innumerable applications and challenges facing each user of the technique. The programme of the workshop will consist of lectures by specialists from R&D Establishments, Universities and Industries from within India and overseas. Following topics will be covered:-

  1. Latest Advances in Mass Spectrometry Instrumentation.
  2. Recent Trends in Various Applications of Mass Spectrometry.
  3. Accelerator based Mass Spectrometry.
  4. Lasers and Time-of-Flight Mass Spectrometry.
  5. Liquid Chromatography-Mass Spectrometry for Biomedical Applications.
  6. Mass Spectrometry in Isotope Geology and Earth Sciences.
  7. Mass Spectrometry in Petroleum, Environmental, Biological and Nuclear Sciences.
  8. Stable Isotope Ratio Mass Spectrometry (H,C,N,O,S).
  9. Qualitative and Quantitative Analyses by Mass Spectrometry.
  10. Fundamental Aspects of Mass Spectrometry.

For further details please contact:-

 

Smt. D. Alamelu
Convener, Workshop Organising Committee (10th ISMAS-WS 2002)
Fuel Chemistry Division, BARC, Trombay,
Mumbai, 400 085, India
Telephone: 91-22-559 3740 (O)
Fax: 91-22-550 5151
Email: alamelu@magnum.barc.ernet.in
Website: www.barc.ernet.in

 

Symposium on Cyclone Emergency Preparedness:

 

India’s coastal areas have been experiencing moderate to severe cyclonic storm almost every other year. Some of the units of DAE, such as Orissa Sands Complex (OSCOM), Indian Rare Earths Limited (IREL) and IGCAR, being located on east coast of India are quite prone to be affected by cyclonic storms. While each such unit is expected to have its own cyclone emergency preparedness plan, the Symposium on Cyclone Emergency Preparedness, to be held at Kalpakkam during January 30-31, 2002 will generate discussions amongst the different concerned units and also state government agencies dealing with cyclone emergency plans. The Symposium, with the focus on cyclone protection and relief, is jointly being organized by the Indian Rare Earths Ltd., Indira Gandhi Centre for Atomic Research and DAE’s other units at Kalpakkam.

 

Amongst others, representatives from the states of Andhra Pradsesh, Orissa and Tamil Nadu will be sharing their expertise and rich experience in cyclone emergency preparedness. The symposium will have invited talks by specialists from Structural Engineering Research Centre, Indian Meteorological Department, Port Trusts, Forest Department and other institutions.

 

Details are available on Website: www.igcar.ernet.in

 

Common Selection Procedure for Recruitment to the four Training Schools of DAE:

 

DAE offers excellent career opportunities through one year Orientation Course for Engineering Graduates & Science Post-Graduates at BARC Training School staring in September every year (since 1957). Selected applicants, after successful completion of the Courses are appointed as Scientific Officers in DAE organisations.

 

To meet the growing demand for highly qualified manpower in the R&D sector of hi-tech areas, Industrial & Mineral Sector and Nuclear Power Programmes of the DAE, additional Training Schools have been started as affiliates of the BARC Training Schools, at the Centre for Advanced Technology, Indore (September 2000), Nuclear Fuel Complex, Hyderabad (September 2001) and Nuclear Power Corporation of India Ltd (through its Training Centres at Rawatbhata, Kalpakkam & Tarapur since 1980).

 

Now, commencing from September 2002, a common selection procedure will be adopted for recruitment to all the four training schools.

 

  1. For Engineering Graduates:- A valid GATE score (as on September 2002) will be a prerequisite condition for applyng in the eight engineering disciplines (Mechanical, Chemical, Metallurgy, Electrical, Electronics, Computer, Instrumentation and Optics & Optoelectronics*). Candidates for final selection interview will be short listed from the merit list drawn on the basis of GATE score. Other eligibility criteria (such as minimum of 60% marks in the qualifying BE degree, age etc) remain same.
  2. For Science Post-Graduates:- There will be no change in the eligibility criteria. A common Written Test for all the Training Schools (with separate question paper for each specified discipline) will be conducted on February 24, 2002 at different Centres. Candidates for final selection interview will be short listed from merit list drawn on the basis of Written Test Score of the applicants.

Admission to different Training Schools will be made from the merit list drawn on the basis of final selection interviews (to be held during June-July 2002) and choice given by the candidate subject to the allotted vacancies.

 

The detailed information is available at website www.barc.ernet.in