IL24831A - Method and apparatus for batch irradiation of substances - Google Patents

Description

n 303 ο»ι»ιπ njn nV τρηπι ΠΒ»¾? Method and apparatus for batch irradiation of substances ATOMIC ENERGY OF CANADA LIMITED, COMMERCIAL PRODUCTS C: 23767 This invention relate s to a method and apparatus for batch irradiation of substances. The invention has application to the irradiation of substances in batch containers or bales.

It is known to pass containers of substances along defined paths adjacent single or multiple sources of irradiation. Apparatus for such irradiation has been wasteful! of the energy available from the source or sources and products have been subject to very uneven dosage s. Further , the configurations, used in prior apparatus have required large volume s of biological shielding due to inefficient layout, and the lack of provision of easy means for with-1C drawing the source for storage purpose s.

The pre sent invention envisages a compact irradiator wherein a source is movable along an axis extending between a storage position and an irradiating position and wherein substance s are batched and rotated about a number of axe s, adjacent the irradiating position of the source and coaxial V -te"¾le above -mentioned axis. The invention {provides a rapid and convenient expedient for withdrawal of the source and unimpeded acce ss to a number of rotatable platform s adapted to receive batched substances and rotatable about the aforementioned axes. The present invention envisage s other method s of stacking substances around the source, which methods will give differing 0 efficiencies of utilization of the available irradiation energy, for example , the substance s may be arranged so that the individual batche s of substances may be interlocking, intermeshing, etc. , and the platform s rotated discontinuously, thereby having a series of periods wherein selected regions of the substances move successively into position for . irradiation for the reception of desired dosages. Various such arrangements will occur to those skilled in the art. Such arrangements will enable the _>/ greatest utilization of the source energy available , ^hus, permitting the use of the lowe st possible amounts of radioactive material.

The source is stored below ground level and shielded by a plug cable results in the source and plug dropping under gravity into a biologically safe position.

It is an object of one aspect of this invention to provide a method of irradiating batched substance s.

In accordance with this object, the invention comprises the steps of: disposing an irradiating source on a first axis, disposing said substance along a second axis co-extensive and adjacent to said first axis, and, providing relative axial movement between said source and substance in accordance with a desired irradiation dosage received by all parts of said substance.

It is an object of another aspect of this invention to provide apparatus for irradiating substances.

In accordance with this object, the invention comprises: apparatus for irradiation of substances comprising: a storage container formed of a biological shielding material, said container including; a source-cage re ceiving region disposed in the interibr of said container , a plug receiving region having an opening in the upper surface of said container and com municating with said source cage receiving region, the two said regions being disposed on a first comm on vertical axis; a source cage for selective reception in said container, said cage having lifting means provided thereon; a plug for selective reception in said container, said plug effecting shielding of said source when both source and plug are received in said container, said plug having lifting means thereon; a table for receiving said substance adjacent said first axis, and, hoist means; for lifting said plug out of said container, and, for lifting said source out of said container and placing said source adjacent said substance for irradiation thereof.

A preferred embodiment of this invention will now be described with reference to the accompanying drawings, in which, Fig. 1 is a side view, partly in section, of a batch irradiator showing a source and plug in both the storage and operating positions.

Fig. 2 is a plan view, partly in section, of an irradiation room - Referring now to Fig. 1 , there is shown a source cage of radioactive material which may be Co^ or other suitable source material. The cage may be hoisted upwardly by m eans of a rod , part of which is shown at 10, the rod being secured fo the top of the cage 1.

When not in use the cage 1 is received in a source storage container 2 disposed in a cavity 3 in a concrete floor having upper surface s 32 and a cavity base 33. The container 2 includes a cage receiving region 20 and a plug receiving region 22. The container flange 5 re sts on blocks 51 and 52 which in turn re st on the floor surface 32. A feed pipe 35 is located in the cavity base 33 and is adapted to feed cooling gas 36 into the cavity 3.

Disposed on the underside of the container 2 is an orifice 23 and lower meandering cooling feed pipe s 24. Orifice 23 is located adjacent feed pipe 35 thereby prom oting the flow of gas 36 into the interior of the regions and 22 of the container 2. Upper meandering outlet pipes 25 are disposed to connect the top of region 20 with the outside of the container 2.

A biological shield plug 4 is freely received in region 22 of the container 1 and is adapted to substantially inhibit the escape of the incoming gas 36 to the outlet pipes 25. The plug 4 includes a bore 41 through which the rod 10 of the cage 1 is loosely accommodated . The plug 4 may be lifted vertically, via the bracket 63 and the hoist cable 70, by hoist means to be described .

The container top flange 5 is supported around its periphery by the floor surfaces 31 and 32 by ir Extending upwardly from the base plate 5 is a guide tube 60 coaxial top surface of container 2. Extending upwardly from the plug 4 are frame members 63 supporting a cable term inal plate 64 to which a lifting cable 70 is attached . The cable guide plate include s an aperture 65.

The lifting cable 70 passe s to a hoist as will be de scribed . Affixed , adjacent the lower end s of the --¾¾mieaa>¾rri.b r.s 63, is a pulley 69 carried for rotation in a trunnion 66 attached to shaft 10. A cable 67 is attached at one end to position 68 of the cable terminal plate 64 and passed downward s and round the pulley 69 and then upwardly through aperture 65 in the plate 64. The cable 67 serve s to raise the source cage 1 separately from the plug 4, as will be de scribed .

Referring now to Fig. 2 , there is shown a plan view, partly in section, of a biologically shielded irradiation room ,i:in..w.hich the apparatus shown in Fig. 1 is installed in chamber Z. Entrance to the chamber is made through opening Y from a corridor X and a sliding door W having an interlock V. The se arrangem ents will be familiar to those skilled in the art.

Cable s 70 and 67, shown in Fig. 1 , are passed over pulleys, not shown, and their re spe ctive positions are e stablished by a hoisting mechanism 100 which is controlled at a control panel 101 having a number of control functions led into the chamber Z through a meandering tube 102.

The operation of the apparatus will now be de scribed .

Initially the source cage 1 is disposed in region 20 and plug 4 is disposed in region 22 of the container 2 , and in the se positions radiation for the source cage 1 is biologically shielded horizontally by the container 2 and concrete walls 3 and vertically. by the container 2 and the plug 4. Cooling gas 36 will be provided whenever a source is pre sent in the apparatus .

Substance s to be irradiated identified by B , are setiup on the turntables 53 and per sonnel withdrawn from the chamber Z and the door W closed .

The plug 4 is then hoisted upwardly via cable 70 by the hoist 100 until the plug 4 is positioned as shown dotted in Fig. 1 . then be left stationary at the elevated position throughout the irradiating -period or it may be gradually raised throughout the irradiation period so as to expose each part of the substance to a de sired dosage .

Alternatively, the source 1 may be oscillated along its vertical axis during exposure .

When the dosage required for given %ubst.ance_;is. . J.?i¾ifial,:; the displacement of the source 1 as a function of time may be programmed and automatically controlled by the hoist. Alternatively, radiation counters may be positioned adjacent the substance and the displacement of the source controlled either manually or automatically in response to signals generated by the radiation counters. Such displace ents inherently require somewhat longer period s of exposure at the¾owest -and highe st lim its of the vertical height of the substance .: .

After the substance has been irradiated, the source 1 is returned to the region 20 of the container 2 and then the plug 4 lowered down into region 22 to complete the shielding/ It will be appre ciated that the sam e hoist 100 may also be used for lifting the entire container 2 complete with its source 1 and plug 4 for replacement of the source or for other servicing. Since the source and plug are lifted against the gravitational force, failure of and plug the hoist and /or lifting cables will result in the sxwirce/fal ling under gravity into their re spective storage positions .

The above disclosed method and apparatus for irradiating substance s of provide s extrem e simplicity of operation, controllable dosage s -ο*· irradiation, and safety of personnel.

Claims (1)

1. 24831/2 G IM5 1· A method of irradiating batches of a substance by means of a radioactive source comprising the steps of: (i) disposing an irradiating source on a first axis* (ii) disposing said batches along a second axis coextensive with and adjacent to said first axis, and (iii) providing relative axial moveiaent between said source and batches in accordance with a desired irradiation dosage received by all parts of said substance., 2» The method as defined in Claim 1 wherein said relative axial movement is iaposed by automatic control as a function of said desired irradiation* 3« The method as defined in Claim 2 including the additional step of generating a signal in response to the irradiation received by said substance and utilizing said signal to operate said automatic control, the resultant irradiation dosage being in accordance with desired dosages throughout said substanceβ 4β Apparatus for irradiation of substances comprising: (i) a storage container formed of a biological shielding material, said container includin % (a) a source cage receiving region disposed in the interior of said container* (b) a plug receiving region having an opening in the upper surface of said container and com®- unicating with said source cage receiving region, the two said regions being disposed on a first common vertical axis* (ii) a source cage for selective reception in said container, said ca e havin liftin means rovided thereon 24831/2 (iii) a plug for selective reception in said container, said plug effecting shielding of said source ¾hen both source and plug are received in said container, said plug having lifting means thereon* (iv) a table for receiving said substance adjacent said first axis, and, (v) hoist means (a) for lifting said plug out of aaid container, and (b) for lifting said source out of said container and placing said source adjacent said substance for irradiation thereof* 5e Apparatus as defined in Claim 4 wherein said table is rotatable about a second axis adjacent and co-extensive with first common axis* 6« Apparatus as defined in Claim 4 wherein said hoist means includes a source position control* 7o The apparatus as defined in Claim 6 further including an irradiation dosage counter adjacent said substance, said counter producing an output signal responsive to dosage received by said substance, and said position control being responsive to said signal whereby desired dosages of irradiation with said substance is maintained* 8· The apparatus as defined in Claim 4 wherein said lifting means on said source cage is a rod, wire or cable, joined to the upper surface of said cage, and wherein said plug includes an aperture through which said rod, wire, or cable is passed, said rod, wire, or cable and said lifting means on said plug both being associated with said hoist means whereby said source cage and said plug may be moved independently* 248^1/2 9β Apparatus as defined in Claim 5 including a prime mover for rotating said table* 10. Apparatus as defined in Claia 9 including a plurality of said tables each rotatable about an individual second axis, lie Apparatus as defined in Claim 10 including common drive means for rotating all of said tables* s & PAMKBR3