Form 2
THE PATENTS ACT, 1970
(39 OF 1970)
AND
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(Section 10; rule 13)
1. TITLE OF THE INVENTION:
An apparatus and method for gamma irradiation
2. APPLICANT:
a. Name: Walchandnagar Industries Ltd.
b. Nationality: An Indian company incorporated under The Companies Act,
1956
c. Address: Walchand House, 15/1/B- G.A Kulkarni Path, Kothrud,
Pune - 411038, Maharashtra, India.
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed.

Field of the invention:
The present invention relates to an apparatus and method for gamma irradiation. More particularly it relates to four side irradiation of a product. The invention employs an assembly that moves in a circular direction such as a 'Giant wheel' (or a Spider) and facilitates the movement of the products around the radiation source for effective and optimum irradiation.
Background of the invention:
Gamma irradiators are used to deliver a pre-determined amount of gamma radiation dose in a controlled manner to desired products. Gamma Radiation is effected by a highly radioactive isotope of Cobalt, i.e. Co-60. Gamma rays from Co-60, are highly energetic and can penetrate practically any material to a significant distance. They are lethal to any living organisms including human beings. Therefore, gamma irradiation is toughly regulated by national and international regulatory norms.
Gamma irradiators, in general, consist of a biological shield, a Tradition source, Source movement system, product conveying mechanism, control room, dosimetry lab for regulating dose delivery to products, necessary safety interlocks and features. Guidelines for safety are provided by Regulatory Bodies and are mandatory to follow. There are two types of irradiators based on their product movement - Continuous and Batch.
Continuous irradiators comprises of continuous product rnovement system from outside the ceil to inside the ceil and vice versa. Products to be processed continuously go in and come out of the radiation cell after traveling a definite path for predetermined residence time.
Batch irradiators have discontinuous product movement system. Two separate systems are required, one for loading the products inside the cell and another for movement of product boxes within the cell. Product boxes are loaded in a definite arrangement in the cell, using either an automated mechanism or manually. The cell is then closed for predetermined batch time during which product boxes are exposed to radiation.

Whenever, shuffling of product boxes is required, in continuous irradiators it is automated while; in present batch irradiators mostly it is manual. Shuffling in Batch Irradiators requires radiation cell opening and human intrvention. Any requirement like, personnel entry into irradiation cell, inherently adds to stringent safety requirements from concerned safety authorities and it also contributes to loss of efficiency of the system. Batch type irradiators, have the advantage of catering to different dose requirements of various products and range of process volume. These irradiators require lower capital investment and can be custom designed.
Although, a number of batch irradiators are available, their designs have some inherent limitations, viz, requirement of excessive human interference, requirement of personnels for loading/ unloading of products inside the radiation cell. Available designs of batch irradiators possesses cell size, almost as same as of continuous irradiators, hence capital investment is almost same.
Present invention aims to overcome inherent disadvantages of batch irradiators and present a novel concept as detailed hereunder.
Summary:
The present invention aims at:
•• An apparatus for irradiation with smaller foot print.
•• An apparatus for irradiation requiring minimum human interference into the
radiation processing cell. • An apparatus for irradiation for optimum source utilization •• An apparatus for irradiation having reduced capital investment
Statement of the invention:
The present invention therefore is an apparatus for gamma irradiation comprising of an irradiation cell, a biological shield surrounding cell area including an access door, a product loading/unloading window and a water pool for storage of a source of radiation, plurality of tote carriers being mounted on an assembly such as Spider, housing the products for movement, the movement of the said tote carriers is circular such as Giant wheel, a means of circular motion provided for movement of the plurality of tote carriers, the said totes being able to rotate around their mounted axis, A radiation source rack

housing a radioactive source Cobalt 60 being placed at the center of the circular product movement path for optimum irradiation.
These plurality of tote carriers further house plurality of small tote boxes, which then further contain the products being housed in plurality of product boxes for irradiation. The tote carriers have a side-opening for loading the small tote boxes. The central positioning of the said source is brought about by an initial upward movement of source rack from the said water storage followed by tilting the said source rack by a suitable tilting mechanism to hold the source rack, by a suitable mechanism, in a horizontal position. The said tilting mechanism is a guide rail or rack and pinion arrangement or the like and the holding mechanism is a magnetic or mechanical brake or the like. The said source rack achieves a vertical position upon release of holding mechanism and moves downward vertically due to gravity to rest in the water pool /storage.
The present invention is also a method of product irradiation in two half cycles comprising in the first half cycle, loading the said products in the product boxes and then in the plurality of small tote boxes, these small tote boxes are being placed in the plurality of tote carriers, then tote carriers are rotated in a circular motion such as that of a giant wheel, at a predetermined constant speed inside the radiation cell. Then the source is brought at the central position and irradiation is effected by exposing the tote carriers from all four sides namely bottom, left, top and right sides respectively to the radiation source. For effective irradiation, the small tote boxes and said product boxes are shuffled or changed for the remaining half cycle to cause effective irradiation. The process of unloading the irradiated products and loading new products from window without entering the irradiation cell and repeating the aforesaid steps. The said shuffling or changing of the plurality of the said product boxes in a small tote box exposes the inner surfaces of each product box during the remaining half cycle. After the product box shuffling, the shuffling or changing of the said plurality of small tote boxes is done so that the positions of exterior totes are interchanged with interior totes for effective irradiation.
Embodiments of the present invention:
Product Movement System
Product movement system consists of Giant Wheel type construction referred to as
'Spider'. A plurality of tote carriers, mounted on spider, rotates around the source.

Individual tote carrier is free to rotate on its mounting axis. On account of this novel design, product boxes are getting exposed to gamma radiation from four sides.
Source Movement System
Source movement system consists of vertical movement of the source from water pool and after reaching predetermined position, it starts tilting gradually to horizontal position. Source is cylindrical in shape and when fully exposed, it attains concentric position with tote carriers. On account of cylindrical shape of source and concentricity, all tote carriers are always equidistant from the source.
Product loading/unloading to Radiation Cell
A product loading/ unloading window of predetermined dimensions, hereafter referred to
as "Product window", is provided on one of the vertical walls, of biological shielding. An
indexing arrangement is provided for spider, for locating and locking individual tote
carrier with "Product window', for loading/unloading operation. On account of this novel
design, no human entry into the radiation cell is required during loading/unloading
operation.
Shuffling of Product Boxes
Shuffling of product boxes is carried out outside the radiation cell. Shuffling is carried out
as follows,
STEP-1
In this step shuffling is carried in such a way that the inner surfaces of each product box
which were not exposed during first half cycle are brought out for exposure to source for
remaining half cycle. This can be achieved by following two methods or any other
method.
Individual product boxes marked as b1, b2, b3, b4 in the attached sketch are rotated by 180° around their own axis,
OR

Position of box-1 and box-4 are interchanged, at the same time position of box 2 and box-3 are interchanged.
STEP-2
Positions of exterior totes are interchanged with interior totes i.e. Position of small tote 't1' and tote 't2' are interchanged at the same time position of small totes named as tote 't3' and tote 't4' are interchanged.
When small totes are taken out of cell for shuffling, first Step-1 is carried out and the step-2 follows step-1 and boxes are reloaded in tote carriers inside the cell.
On account of this novel loading and shuffling arrangement, an effect equivalent to 2+2 pass conveyor system in continuous irradiator is achieved. It guarantees higher dose source uniformity and utilization.
Description of the invention:
Embodiment of the present invention describes a simple and cost effective method for gamma irradiation appropriate for applications covering different dose ranges.
Working of the present invention:
The working of the present invention is described with the help of figure no.1, figure
no.2, figure no.3, figure no.4 and figure no.5.
Figure no. 1 shows the Plan / Top view of the irradiation system in the present invention comprising of the following embodiments:
The numerals to the left indicate the numerals used for the respective items/part in the drawings.
1 - Source irradiation position/exposure
2 - Source storage position/shield
3 - PAD (Personal Access Door)
4 - Product Loading/Unloading window
5 - Tote carriers
6 - Biological shield

t1,t2,t3,t4-Small tote boxes
Figure no.1 describes the whole irradiation system placed in the biological shield, with the tote carriers getting exposed to the central source, position of the source at irradiation and storage position (in the water pool), product loading/unloading window for taking out exposed products and introducing new products for irradiation, personal access door for personal entry during maintenance of the system.
Figure no. 2 shows the Elevation / Front in the present invention comprising of the following embodiments:
4 - Product Loading/Unloading window
5 - Tote carriers
6 - Biological shield
7 - Water pool
8 - Spider
b1, b2, b3, b4 - Product boxes/ Shipping cartons
Figure 2 shows the said irradiation system along with the product boxes and tote carriers mounted on Giant wheel assembly such as spider.
Figure no. 3 shows side view of the irradiation system in the present invention comprising of the following embodiments:
1 - Source irradiation position/exposure
2 - Source storage position/shield

5 - Tote carriers
6 - Biological shield
7 - Water pool 8-Spider

9 - Bearing housing
10 - Support structure
11 -Tilting mechanism
Figure 3 shows the said irradiation system where spider is mounted on a bearing housing which is supported by a support structure and a titling mechanism guiding source
Figure no. 4 shows product loading in the tote carrier for the present invention comprising of the following embodiments:
b1, b2, b3, b4 - Product boxes/ Shipping cartons
t1, t2, t3, t4 - Small tote boxes
5 - Tote carrier
Figure no.5 shows method of shuffling for the present invention comprising of the following embodiments:
b1, b2, b3, b4 - Product boxes/ Shipping cartons
t1, t2, t3, t4 - Small tote boxes
Figure 5A - Arrangement of product boxes before shuffling
Figure 5B - Arrangement of product boxes after shuffling (option 1)
Figure 5C - Arrangement of product boxes after shuffling (option2)
Figure 5D - Arrangement of small totes before shuffling
Figure 5E - Arrangement of small totes after shuffling

The irradiation system in the present invention comprises of:
1. Biological shield
Biological shield (6) of predetermined dimensions, made up of concrete having appropriate density is provided. Biological shield (6) is provided to keep the radiation level outside the cell below permissible limits, thus it protects human and environment outside the cell against radiation exposure.
Access into the radiation cell is through:
a. Personnel Access Door (PAD): PAD (3) is provided for human access
to the radiation cell. PAD (3) is a hinged type construction. Access to
radiation cell is required only in case of maintenance inside the
radiation cell.
b. Product window for loading/ unloading (4): 'Product Window' is
provided for loading and unloading of small totes (t1, t2, t3, t4) into
tote carriers (5), mounted on product movement system called Spider
(8) inside the radiation cell. Shutter of appropriate construction
material is provided to seal the window for radiation attenuation.
Opening of shutter is mechanically interlocked with source movement.
'Small totes (t1, t2, t3, t4)' are cuboidal in shape and are placed inside
the 'tote carriers'(5) with their length parallel to axis of rotation of
spider (8).
2. Radioactive Source
Radioactive source, Cobalt 60, is used in the apparatus of irradiation. It is double encapsulated by Stainless Steel, and is in a form of pencil. Suitable source pencil, is selected which is approved by Regulatory bodies.
3. Water pool for source storage
Water pool (7) of an appropriate size and depth is provided below the ground surface, inside the radiation cell. Water pool (7) is made up of concrete and is lined with SS 304 L plates from inside. Water pool (7) is provided for shielding the radiation/ source, during storage i.e., when the source is not in use. Proper

water quality is maintained with on line conditioning and filtration plant. Water evaporation losses are made up from over head DM water tank, as and when required, using suitable interlock with water level in the pool. All the requirements of regulatory bodies are met for assuring safety. Water pool (7) is further used for loading or replenishment of source pencils. Water pool (7) also helps in cooling the source when it is in storage i.e. in water pool (7).
4. Tote carriers
A plurality of tote carriers (5), of appropriate dimensions, are mounted on "Spider'(8). A tote carrier (5) is a cage like metallic structure. A plurality of 'small totes' (t1, t2, t3, t4) are accommodated inside tote carrier (5). Tote carrier (5) holds the 'small totes'(t1, t2, t3, t4) in place during rotation of spider (8). A 'small tote' (t1, 12, t3, t4) accommodates a plurality of 'product boxes/ shipping cartons' (b1, b2, b3, b4).
5. Product Movement System inside Radiation Cell
Product movement system consists of a 'Spider' (8) mounted on a shaft with bearing housing (9). The shaft with bearing housing (9), is supported on a stand or support structure (10). Support structure (10) is fixed firmly in the walls, or on the ground floor. Spider (8) rotates through the shaft using suitable mechanism, which is placed either inside or outside the radiation cell. A plurality of tote carriers (5) are mounted on the spider (8) to hold the 'small totes' (t1, t2, t3, t4) containing 'product boxes' (b1, b2, b3, b4). The product movement system ressembles to a 'Giant wheel'. The complete product movement system can be dismantled for repair and maintenance work.
6. Source Movement System
Cylindrical source rack, containing the source, held by wire ropes, rests on the floor of the water pool (7) during storage. The source rack is in vertical /shielded position (2) inside water pool (7). For irradiation, source is lifted with the help of wire ropes and guided by means of a suitable tilting mechanism (11) to rest in a horizontal / irradiation position (1) which is concentric to the product movement

path. Such tilting mechanism (11) can be guide rails or 'rack and pinion' arrangement or any such other arrangement.
7. Shuffling of Products
Suitable arrangement for shuffling of product boxes (b1, b2, b3, b4) and small totes An irradiation cell;
> A biological shield surrounding cell area including an access door, a product loading/unloading window and a water pool for storage of a source of radiation;
> Plurality of tote carriers, being mounted on an assembly such as Spider, housing the products for movement, the movement of the said tote carriers being circular such as a Giant wheel;
> A means for circular motion provided for movement of the plurality of tote carriers, the said totes being able to rotate around their mounting axis;
> A radiation source rack housing a radioactive source of Cobalt 60 being placed at the center of the circular product movement path for optimum irradiation.

2. The apparatus as claimed in claim 1, wherein the plurality of tote carriers house plurality of small tote boxes, the said small tote boxes contain products being housed in plurality of product boxes for irradiation.
3. The apparatus as claimed in claim 2, wherein the plurality of tote carriers have a side-opening for loading the small tote boxes.
4. The apparatus as claimed in claim 1, wherein the central positioning of the said source is brought about by an initial vertical upward movement of source rack from the said water storage followed by tilting the said source rack by a suitable tilting mechanism to hold the source rack, by a suitable holding mechanism, in a horizontal position.

5. The apparatus as claimed in claim 4, wherein the tilting mechanism is a guide rail or rack and pinion arrangement or the like and the holding mechanism is a magnetic or mechanical brake or the like.
6. The apparatus as claimed in claim 1, wherein the said source rack achieves a vertical position upon release of holding mechanism and moves downward vertically due to gravity to rest in the water pool / storage.
7. A method of product irradiation in two half cycles comprising:

> In the first half cycle, loading the said products in the product boxes and then in the plurality of small tote boxes;
> The said small tote boxes being then placed in the plurality of tote carriers;
> Causing the tote carriers to move in a circular motion such as that of a giant wheel, at a predetermined constant speed inside the radiation cell;
> Bringing the source at the central position;
> Effecting irradiation of the products, by exposing the tote carriers from all four sides namely bottom, left, top and right sides respectively to the radiation source;
> Shuffling or changing the said product boxes, followed by shuffling of small tote boxes, for the remaining half cycle, to cause effective irradiation;
> Unloading the irradiated products and loading new products from product window without entering the irradiation cell and repeating the aforesaid steps.
8. A method of product irradiation as claimed in claim 7, wherein said shuffling or
changing of the plurality of the said product boxes in a small tote box exposes
the inner surfaces of each product box during the remaining half cycle.

9. The method of product irradiation as claimed in claim 7, wherein said shuffling or changing of the said plurality of small tote boxes is done so that the positions of exterior totes are interchanged with interior totes for effective irradiation.
10.The apparatus and method as claimed in claims 1 to 9 above, substantially such as herein described with reference to the drawings.