CN101344496A - Gamma source three-source combined full view exposure method for macrotype spherical storage tank - Google Patents

Abstract

The invention relates to a panoramic exposure method with three-source Gamma source combination of a large-scale spherical storage tank, which adopts the irradiation with three-source bound combination, can obtain a basically even panoramic radiation field, completely satisfies the standard fog density and sensitivity requirements of photographic plates, has greatly shortened irradiation time and novel techniques, is simple, convenient, safe, reliable and environment-protective, and can improve the nondestructive examination quality. The panoramic exposure method comprises the following technical steps: a central point of the spherical storage tank is obtained by measurement, a Gamma source head is packed on a nylon belt and positioned at the central point of the spherical storage tank, and the nylon belt is fixed in centers of an upper inlet orifice and a lower inlet orifice and strung by an euphroe, thus avoiding swinging; a source tank is connected with a drive device, and source transmission pipes and a drive hose are straightly positioned with the bend radius no less than the least Phi 500; the three source transmission pipes are bound together, and under the precondition that the geometric unsharpness is ensured, three irradiation heads turn outward in a petal shape so as to reduce mutual influence, increase irradiation area and reduce fade zone.

Description

The macrotype spherical storage tank gamma source three-source combined full view exposure method

One, technical field:

The present invention relates to a kind of lossless detection method of spherical tank, especially relate to a kind of macrotype spherical storage tank gamma source three-source combined full view exposure method.

Two, background technology:

In the background technology, along with the development and utilization of rock gas, big volume (5000m on the market ³～10000m ³) spherical storage tank quantity in continuous increase.According to the special equipment management expectancy, spherical tank is when making and deciding prosecution system quality in the labour phase, and a requisite job is exactly Non-Destructive Testing, takes which kind of film making method will directly have influence on the manufacturing cost of spherical tank so and examines maintenance cost surely.Now, domestic Non-Destructive Testing company when carrying out the spherical tank flaw detection general adopt X ray, single source, general industry iridium source and special industry iridium source Dan Yuan (three kinds of methods of source strength 〉=250Ci) are arranged.For panoramic exposure technology, everybody generally uses Ir192 Dan Yuan center transillumination, owing to be subjected to source of bank savings equipment surface to leak quantitative limitation, generally the highest limiting the quantity of only made 100Ci.Prolongation in time, the often not enough 100Ci of source strength decay during to use.Therefore under the situation that the maximum activity in single source can not increase, along with the increase of tank diameter or thickening of tank skin, unique changeable parameter is the time shutter.But facts have proved that when film making time during greater than 18 hours, the fog density of egative film obviously increases, sensitivity seriously descends, and exposure effect can not satisfy the evaluation requirement.Time exposure in addition, radioactive source increases the influence of surrounding environment, and corresponding safety cost will increase considerably.Simultaneously with the prolongation of time shutter, operate in blown, rained, prolongation, operate under the restriction of natural conditions such as being blown, rain, high temperature tans by the sun, protect film, the difficulty of realization duration also in continuous increase.

Three, summary of the invention:

The present invention is in order to solve the weak point in the above-mentioned background technology, a kind of macrotype spherical storage tank gamma source three-source combined full view exposure method is provided, it adopts three source binding combination transilluminations, can obtain basic panorama radiation field uniformly, standard-required is satisfied in Fog degree, sensitivity fully, time shutter can shorten greatly, technology novelty, simple, convenient, safe and reliable, environmental protection and can improve the Non-Destructive Testing quality.

For achieving the above object, the technical solution used in the present invention is:

A kind of macrotype spherical storage tank gamma source three-source combined full view exposure method is characterized in that: adopt the γ source combination exposure that three intensity do not wait, it is tight and tie up panoramic exposure together that three source triangular shape Φ 80 tie up together panoramic exposure or three sources.

Processing step comprises: measure and to find out the spherical tank central point, the γ source is bound in places the spherical tank center on the nylon tape, by hand-hole center fixation up and down and with euphroe nylon tape is tightened up, prevent swing; Connect source case and drive unit then, defeated source capsule and driving flexible pipe are answered straight putting, and the bending radius minimum is not less than Φ 500; Three defeated source capsules bundle, and under the prerequisite that guarantees geometric unsharpness, three photohead petal-shaped outwards curve, and to reduce interacting of self, the Enhanced Radiation Reduced Blast area reduces the blind area.

Compared with prior art, the advantage and the effect that have of the present invention is as follows:

Adopt strong single source to carry out the characteristics that the large-size spherical tank radiographic inspection exists at existing construction market, the present invention is consulting on the basis of data of literatures, through serious analysis, scrutinize, imagination is under existing source apparatus condition, make full use of little activity source, adopt the multi-source combination to increase source strength and improve exposure, to reduce the adverse effect that time lengthening is brought.But because the physical characteristics of solid source, the γ source combination that three intensity does not wait exposes, whether simply addition of source strength; Whether blocking between source and the source can influence the even of panorama radiation field; Focal spot size increases egative film sensitivity, whether the egative film geometric unsharpness satisfies standard; The problems such as increase degree that source strength strengthens the back scattered ray occur immediately, and these queries then need to come analysis verification by test.

Given this, the present invention has carried out detailed verification calculation theoretically.Suppose that the three sources source strength that together exposes is the simple mathematical addition, consider the homogeneity of radiation field, consider the size of blind sector, the factors such as influence degree of scattered ray and fog density, design three source array modes, calculate the time shutter, carry out light exposure test, quality index such as the uniformity coefficient of mensuration various combination mode, the exposure of film under the time shutter and the fog density of egative film, sensitivity.By test, the hypothesis on the proof theory is set up, and the correct array mode of multi-source can overcome the influence of blocking between source and the source, gets rid of minimum blind sector, obtains the egative film that every quality index satisfies standard-required.

By after the repetition test repeatedly, the present invention is at 2 5000m of Xianyang natural gas companies ³Spherical tank regularly detects in the engineering project, and natural gas companies gas storage station, Xi'an 10000m ³Natural Gas Spherical regularly detects is tested application in the engineering, and has obtained very satisfied mass effect.Technological parameter according to the different size spherical tank of Theoretical Calculation, test figure design is made film has obtained checking on case history, meet field condition fully.Three source binding combination transilluminations can be obtained basic panorama radiation field uniformly, and standard-required is satisfied in Fog degree, sensitivity fully, and the time shutter can shorten greatly.

Construction technology novelty of the present invention, simple, convenient, safe and reliable, environmental protection and can improve the Non-Destructive Testing quality are advanced technologies that is worthy to be popularized.

Four, description of drawings:

Fig. 1 is a process chart of the present invention;

Fig. 2 is film cloth sheet mode figure;

Fig. 3 and Fig. 4 paste the character code location drawing on the camera bag.

Among the figure, 1-jar number, the 2-welding seam No, the 3-centre mark, 4-egative film numbering, on the 5-date, 6-overlaps mark, 7-source capsule, 8-source.

Five, embodiment:

1, Fa Ming concrete grammar step and the technological parameter in the process thereof

1.1 engineer testing (mainly being to determine the binding mode in three sources and the possibility of checking source strength addition)

1.1.1 industrial analysis

It is that the source of penetrating is placed the spherical tank center that spherical tank is used the gamma-rays panoramic exposure, and the weld seam of reciprocity path position carries out 360 ° of single exposure imagings, once takes the photograph sheet and can reach more than 70% of global weld seam.Generally speaking, re-expose can be finished 100% film making of global weld seam, and can move continuously, be not subjected to start shooting the continuously influence of ability of equipment, volume is little, in light weight, not electricity consumption, water not, greatly reducing human and material resources, time, cost, is that a kind of efficient is very high, the method for remarkable in economical benefits.But all there is certain half life period in the γ source.Along with the prolongation of time, its source strength reduces gradually, and the time shutter is restricted.Energy is fixing can't be regulated, so can have sharpness and the low sight of remolding sensitivity X ray.In order to overcome the above problems, I pass through earnest analytical study at company's nondestructive testing personnel, inquire into and adopt three source combined full view exposure technologies.There is following difficult point in force in this technology:

1) source strength: transillumination thickness spherical storage tank big, that diameter is big in single source, general industry iridium source shows the source strength deficiency, and the time shutter is long, and whether combination back, three sources source strength can increase by the existing source strength numerical value in three single sources.

2) after the different source strength three sources combinations, because the physical characteristics of solid source, self blocks between the source, and the even situation of panorama radiation field how.

3) combination of three sources increases total volume source focal spot size increases, and can egative film imaging geometry indistinctness, sensitivity satisfy code requirement.

4) source strength increases and shortens the time shutter, and can egative film sensitivity meet the demands.

5.1.2 engineer testing

With 5000m of transillumination ³Spherical tank is an example, spherical tank diameter of phi=21.2m, and spherical shell wall thickness δ=38mm uses three source strengths to be respectively two of one of 100Ci, 80Ci and carries out transillumination.

1) focus is calculated:

According to standard JB4730, GB3323-87 AB level quality requirements, must satisfy:

A.L ₁≥10dL ₂ ^2/3

B.Ug≤1/10L ₂ ^1/3

Existing 5000m ³Spherical tank: L ₁=(spherical tank inside radius) 10.6m; L ₂=(spherical tank wall thickness) 38mm

D=focal spot size mm

Get d≤93.8mm by the A formula

Get Ug≤0.34mm by the B formula

Three sources tight and the time, actual when getting d=13:

$\mathrm{Ug}=d\&times;{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="A20081015001300181.png"\; state="\{\{state\}\}">L</figure-callout>}}_2/L_1=13\&times;\frac{80}{10600}=0.05$

Three sources become triangular shape, and are during Φ 80, actual when getting d=80:

$\mathrm{Ug}=d\&times;{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="A20081015001300181.png"\; state="\{\{state\}\}">L</figure-callout>}}_2/L_1=13\&times;\frac{80}{10600}=0.10$

After calculating three sources combinations, when a source diameter＜80mm, focal spot size and geometric unsharpness satisfy standard-required.

2) time shutter calculates:

Suppose that three sources combination source strength is the mathematics addition, the time shutter can calculate with following formula:

$t=\frac{{\mathrm{<figure-callout\; id="2"\; label="XR"\; filenames="A20081015001300181.png"\; state="\{\{state\}\}">XR</figure-callout>}}^2{2}^{\mathrm{\&delta;}/\mathrm{Tn}}}{\mathrm{Akr}(1+n)}.........1$

In the formula: the t=time shutter (h)

X-exposure (C/kg) presses blackness 2.5, and the T7 film is tabled look-up: 5.16 * 10 ^-4C/kg

R-spherical tank radius: 10.6m

δ-transillumination thickness: get 38mm

Th-half-value layer (cm) is tabled look-up: get 11mm

The h-scattering ratio is tabled look-up: get 1.124

A-source radiation activity (Bg): get 260Ci, get 260 * 3.7 * 10 ¹⁰Bg

Kr-Ir ¹⁹²Constant $32.9\&times;{10}^{-12}\frac{C\&CenterDot;{\mathrm{cm}}^2}{h\&CenterDot;\mathrm{kg}\&CenterDot;\mathrm{Bq}}$

Above-mentioned value substitution 1 formula was got t=7.76 hour.

3) actual transillumination test

After obtaining focus theoretical value, time shutter theoretical value, it is tight and tie up together the panoramic exposure mode and test to adopt three source triangular shape Φ 80 to tie up together panoramic exposure and three sources respectively.Relatively desire to obtain the empirical data of the following aspects by the dual mode result.

A. combination back focus in three sources enlarges the influence to geometric unsharpness and egative film contrast;

B. the even situation of radiation field, the impact effect that blocks between the dual mode source;

C. combination source strength in three sources increases, and the time shutter reduces, the comparison of Fog degree;

D. two kinds of cloth source side formulas, transillumination dead range are relatively;

E. revise the source strength calculated value, obtain empirical value;

F. obtain other construction parameter.

4) experimental technique condition

A. normative reference: JB4730 " Nondestructing Detection of Pressure Vessels "

B. contract technical parameter requirement.

C. equipment and material:

Source Type: Ir ¹⁹²

One of source strength: 100Ci, two of 80Ci;

Test specimen specification: 300 * 100

One of test specimen quantity: δ=36mm, three of δ=38mm (tow sides all weld the high weld seam of 2mm);

Film type: T7 Ah can send out;

Intensifying screen: preceding screen 0.1, back screen 0.2;

Penetrameter model: GB5618-II

The special-purpose cover of punching soup type: Li Weina medicine " double star "; Temperature, normal temperature is to be measured.

D. test specimen arrangement

Adopt 4 test specimens evenly to arrange by 13.5m such as figure two.Consider to be derived from that body stops and source capsule stops, respectively put one at source front end, side; Consider the degree of uniformity of radiation field, put one for 45 ° that point in the source; Consider the dead angle, putting one near the source capsule place.

E. film cloth sheet mode

Every test specimen pastes three films (80 * 100); The back side prevents backward scattering with sheet lead; The II penetrameter is sticked in every workpiece front; The test block numbering is as Fig. 2, and the egative film numbering is respectively 1-1; 1-2; 1-3; 2-1; 2-2 etc.

1.1.3 test figure relatively

Transillumination is tightly tied in A, three sources

Thickness of workpiece (mm)	38	36	38	38	38	36	38	38	38	36	38	38
													The egative film numbering	1-1	2-1	3-1	4-1	1-2	2-2	3-2	4-2	1-3	2-3	3-3	4-3
Time shutter (hour)	4	4	4	4	6	6	6	6	8	8	8	8

Photographic density	In vain	In vain	In vain	In vain	1.8	1.8	1.3	1.0	2.5	2.3	2.1	2.0
													The punching temperature-time (minute)	10	10	10	10	10	10	10	10	8	8	8	8
The visible radical of penetrameter					8	8	8	8	9	9	9	8

B, three sources become triangle Φ 80 to put:

Thickness of workpiece (mm)	38	36	38	38	38	36	38	38	38	36	38	38
													The egative film numbering	1-1	2-1	3-1	4-1	1-2	2-2	3-2	4-2	1-3	2-3	3-3	4-3
Time shutter (hour)	4	4	4	4	6	6	6	6	8	8	8	8
													Photographic density	In vain	In vain	In vain	In vain	1.6	2.0	1.6	1.6	2.5	2.5	2.5	2.4
The punching temperature-time (minute)					8	8	8	8	8	8	8	8
													The visible radical of penetrameter					8	8	8	8	9	9	9	9

1.1.4 interpretation of result

A, can find out two kinds of cloth source side formulas by test datas such as blackness, picture element index, film rinsing times, in the source strength performance is consistent, prolong with the time shutter, negative quality descends, in optimum exposure time, the imaging geometry indistinctness is that sensitivity can be satisfied the requirement of standard " JB4730 " to negative quality fully.

The panorama radiation field of B, two kinds of cloth source side formulas is even substantially, and the single strong in a steady stream size in combination back, three sources hour is described, the influence of radiation field is eliminated because of mutual superposition, and the phenomenon that the stack of little source increases source strength exists.But after the combination of three sources, the friendship density of iridium metals has often caused blocking by test mutually between three sources to be confirmed, three sources are tightly tied the mode transillumination and are laterally reached inverse direction in the source, photographic density obviously reduces, in the same time shutter, compare vertically and the inverse direction photographic density can not meet the demands, and three sources when tying up transillumination with Φ 80 diameters above-mentioned phenomenon can be eliminated, satisfied transillumination effect is arranged.

C, the parameter of utilizing test to obtain are at 2 5000m ³Spherical tank adopted 100Ci, 80Ci, three source combined full view exposures of 70Ci 8 hours, negative quality, construction period have all been obtained optimum efficiency, negative quality is good, meet " JB4730 " code requirement fully, egative film sensitivity reaches the requirement of x-ray film, transillumination time ratio list source transillumination shortens 10 hours, has reduced time exposure effectively to the influence of surrounding environment and the unfavorable natural conditions risk of damage to egative film, and therefore construction cost descend.

1.1.5 conclusion

Using proof three source combined full view transilluminations by test and engineering is easy, economic, suitable, safe transillumination technologies, and the three kind methods cited than the front show following advantage:

A, method are easy.After the process implementing process only needs device transformed a little, just can with the same distribution mode of using safely of single source transillumination mode, the still available single source side formula of source strength calculating is carried out.

B, economy, suitable.Utilize combination back, three sources source strength nature increase characteristics, can utilize the value in little Curie's iridium source fully, be merged into big source transillumination main equipment,, expanded the usable range in iridium source, greatly reduce construction cost separately when little source transillumination mini-plant.

C, safety.Adopt three general industry iridium source combinations to replace the special super large list of source strength 250Ci source to carry out transillumination, solved the difficulty in the radioactive source safety management of super large source effectively, make the transportation of radioactive source, keeping meet the nation's security requirement more.

1.2 technological process brief introduction (is example with 5000 cubic metres of spherical tank flaw detections)

1.2.1 the checking of technological parameter

Large-size spherical tank at first will carry out the checking of series of parameters such as focus, time shutter when adopting three source combined full view exposures to construct.

1.2.2 transillumination condition test

According to the method that the previous process principle is introduced, by person in charge of the technology aspect and quality owner and professional responsibility teacher, establishing criteria sensitivity requires to determine the transillumination condition, determines time shutter and development time, temperature.

1.2.3 draw cloth sheet figure

The requirement and the detection technique of being set type by container in person in charge of the technology aspect's establishing criteria require to draw cloth sheet position on cloth sheet figure, determine every weld seam paster number, position that character code is put and centre mark sensing.

1.2.4 equipment and environmental acceptance

By on-the-spot responsible official spherical tank is possessed testing conditions and confirm, show simultaneously and list or other distinguishing mark.The keypoint part of confirming has: the factor that whether framing scaffold is stablized firmly, weld appearance has or not the overslaugh detection and egative film is evaluated, the on-the-spot requirement of carrying out production strictly in line with rules and regulations, the orientation of spherical tank, the position that No. is stitched etc. of whether meeting of detection, and handle to join after confirming to finish and sign for formality.

1.2.5 weld seam label

By professional responsibility teacher, mark clear in its tangible mode every weld seam according to cloth sheet figure.

1.2.6 setting-out cloth sheet

Is unit by on-the-spot responsible official with the weld seam bar, according to cloth sheet figure, and the centre mark of every the egative film that draws and egative film numbering.The perps centre mark places the right side to point to large size downwards; The transverse joint centre mark places upside to point to large size to the right, and the transverse joint centre mark places downside large size dorsad left bottom.

1.2.7 slide glass pack

Organize the related personnel to pack in strict accordance with dark room operation rules slide glass.

1.2.8 paste character code on the camera bag

Character code comprises: identification marking and telltale mark.Telltale mark has centre mark and overlap joint mark.The edge video that can adopt adjacent egative film lap is as the overlap joint mark.Identification marking has spherical tank numbering, welding seam No and egative film numbering.Mark should be noted: go up big ring centre mark and point to a left side; Every per ten of seams must have the date; Every at least one of seam must have penetrameter.Be rainproof, camera bag will seal with adhesive tape.Pasted the film of character code mark, by the seam number, successively put in transport box in order.Character code position such as Fig. 3 and Fig. 4:

At first select the paster time, avoid summer the sun tan by the sun, rainwater waters pouring.Distribute the paster task by on-the-spot responsible official establishment officer then.Everyone corresponding own institute divides welding seam No 2, finds egative film accurately and numbers 4, and corresponding centre mark 3 localities are affixed on tank skin with adhesive tape with film, during the film above-below direction, should make magazine cap mouth down, and adjacent overlap joint is no less than 15mm.White sheet occurs for reducing the dead angle, take upper and lower hemispheres two parts cloth sheet respectively, the comprehensive film making of re-expose.To jar interior contrast penetrameter putting position of selecting, many three places of contrast penetrameter quantity, one at every place selects test film (promptly getting chip select in advance) to be no less than 10 with circumferencial direction, with the further adjustment time shutter.

1.2.10 focusing

Find out the spherical tank central point by the measurement of on-the-spot responsible official establishment officer, the γ source is bound in places the spherical tank center on the nylon tape, nylon tape is tightened up, prevent swing by hand-hole center fixation up and down and with euphroe.Connect source case and drive unit then, defeated source capsule and driving flexible pipe are answered straight putting, and the bending radius minimum is not less than Φ 500.Three defeated source capsules bundle, and are guaranteeing that three photohead petal-shaped outwards curve under the prerequisite of geometric unsharpness, with reduce self interact, the Enhanced Radiation Reduced Blast area reduces the blind area.

1.2.11 the safety zone arranges that the metering warning device is verified.

Submit the source of putting to the construction responsible official of construction unit and apply for, be responsible for notifying all may enter the relevant personnel of working-yard when the time comes by construction unit.By on-the-spot responsible official, security official, arrange safe police circles by calculating 100 meters circumferences of radius, draw and hang police circles' flag, alarm light is set, check that individual's metering is intact with alarm.Notified police circles' scope with interior personnel in one hour in advance, and notice units concerned's safety director and relevant leader.

1.2.12 exposure

After all are ready to, synchronously the source is shaken out, the time shutter is as the criterion with test parameters and writes down out source time.Radiation index situation on the overview alarm device.Recording controller shakes the number of turns, confirms that the source puts in place.

1.2.13 keep the source

The scene is left to few stay-at-home scene of two people, and rear personnel Ying Lu looks for screen to be shown as zero in gauge and reaches under alarm gap chimes of doom and the alarm red light flicker situation frequently, confirms that the γ source is always at normal exposure.Want strict nurse operation site simultaneously, forbid to have the people blindly to enter and put the source region.When site environment is complicated, construction unit should the cooperation personnel guard the passage that might enter.

1.2.14 receipts source

During the receipts source, three people respectively are with alarm, receive the source synchronously.Two alarm gauge all prove receipts source situation simultaneously respectively, have slept into the source case in the affirmation source, can notify police circles to locate, and the people can enter the scene.

1.2.15 get sheet

Provide the time shutter by test, got test film in one hour in advance, flushing in advance in order to the further affirmation time shutter, is confirmed to get sheet after errorless.Handle with care when getting sheet, forbid to throw out without care disorderly and get rid of, and put in transport box, prevent crimping by the seam order.On-the-spot responsible official is responsible for checking one by one by weld seam, transhipment darkroom, errorless back.

1.2.16 gather raw readings

Raw readings comprises: γ source testing scheme result, conclusion, cloth sheet figure, facility environment are delivered for a check list, setting-out cloth sheet personnel assignment record, camera bag and are pasted character code, quantity number record, paster, seam number and person's record, the source time that exposes to record, keep source roster record, check situation record, recorder and responsible official's signature after getting sheet.

1.2.17 film rinsing

The dark room operation rules are pressed in strictness, wash in order by welding seam No, and strict record punching quantity, and 50 sheets of every development increase 300mL and replenishes liquid.Strict control temperature (normal temperature) is identical with test condition, and strictness provides flush time by conclusion (of pressure testing).

1.2.18 comment sheet, reexamine

Comment sheet, reexamine and to hold RT II level card the above persons and carry out.Comment sheet to carry out in the dim sheet chamber of commenting of light.It is intact to pick up tabula rasa, and anti-antidiarrheal is leaked reflected light influence evaluation.The viewbox high-high brightness is not less than 100,000 Cd/m2, and the stray radiance of observing is adjustable.Comment sheet record to remove to have jar number, seam number, sheet number and defect recognition and rank, the negative quality of having still needed evaluation refers to blackness, resembles the matter index, identification marking and cleaning scuffing degree that the failure will not evaluate, and comments sheet people signature, the people that reexamines signature.

1.2.19 provide report

The above persons provide report by secondary.Report comprises at least: the specifications and models of engineering project title, name of product, material, specification, detection method, position, ratio, operative norm, qualified rank, checkout equipment instrument and equipment, environmental baseline, the detection data relevant with detection gather, detect the position synoptic diagram, detect conclusion, speaker, person approving, sign after examination and the date.

1.3 the key point of this technology is: satisfying under the prerequisite of standard, for realizing maximum irradiated area, maximum irradiation energy, minimum interacting, key is the mode of tying up and the selection of putting position and time shutter in three γ sources.

Claims (2)

1, a kind of macrotype spherical storage tank gamma source three-source combined full view exposure method is characterized in that: adopt the γ source combination exposure that three intensity do not wait, it is tight and tie up panoramic exposure together that three source triangular shape Φ 80 tie up together panoramic exposure or three sources.

2, macrotype spherical storage tank gamma source three-source combined full view exposure method according to claim 1, it is characterized in that: measure and find out the spherical tank central point, the γ source is bound in places the spherical tank center on the nylon tape, nylon tape is tightened up, prevent swing by hand-hole center fixation up and down and with euphroe; Connect source case and drive unit then, defeated source capsule and driving flexible pipe are answered straight putting, and the bending radius minimum is not less than Φ 500; Three defeated source capsules bundle, and under the prerequisite that guarantees geometric unsharpness, three photohead petal-shaped outwards curve, and to reduce interacting of self, the Enhanced Radiation Reduced Blast area reduces the blind area.

Images