(10) International Publication Number WO 2014/105977 Al · PDF fileWO 2014/105977 A11ilii131111111111111111111i1111111111111111111111111111111111111111111 TN, TR, TT, TZ UA, UG, US,

(12) INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT)(19) World Intellectual Property

OrganizationInternational Bureau

(43) International Publication Date . . . • • • • • • • -3 July 2014 (03.07.2014) W I P O 1 P C T

(51) International Patent Classification:G21F 5/00 (2006.01)

(21) International Application Number:

(22) International Filing Date:

(25) F i l ing Language:

(26) Publication Language:

(30) Pr ior i ty Data:61/746,094 2 6 December 2012 (26.12.2012) U S

(71) Applicant: H O L T E C I N T E R N AT I O N A L , I N C .[US/US]; 555 Lincoln Drive West, Marlton, NJ 08053(US).

(54) Title: A RADIOACTIVE MATERIAL STORAGE CANISTER AND METHOD FOR SEALING SAME

(57) Abstract: A canister for storing radioactive materials includes a baseplate, side wall and a top plate. The top plate includes a top surface with a

251 255 t o p edge having a bevel, and with a channel set in from the top edge. Thetop plate is sealed to the sidewall by a weld formed between the beveled

245 2 4 9 t o p edge and the top of the side wail. The base plate is sealed to a bottomof the sidewall, so that a sealed vessel is formed.

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26 December 2013 (26.12.2013)

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271 2 6 7273 2 7 9 277FIG. 2A

PCT/U52013/077852

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1111111111111111111111111111111111111111111111111111M1111111111111E11111111E(10) International Publication Number

WO 2014/105977 A l

(72) Inventors: SINGH, Krishna, P.; 202 Gomez Road, HobeSound, EL 33455 (US). GRIFFITHS, John, D.; 14 Sky-hook Circle, Deptford, N J 08096 (US). M E C K L E Y,Joseph, Albert; 42 Longhurst Road, Marlton, NJ 08053(US).

(74) Agent: BELLES, Brian, L.; The Belles Group, PC, 404 S.16th Street, Philadelphia, PA 19146 (US).

(81) Designated States (unless otherwise indicated, fo r everykind o f national protection available): AE, AG, AL, AM,AO, AT, AU, AZ, BA, BB, BG, BH, BN, BR, BW, BY,BZ, CA, CH, CL, CN, CO, CR, CU, CZ, DE, DK, DM,DO, DZ, EC, EE, EG, ES, Ft, GB, GD, GE, GH, GM, GT,HN, HR, HU, ID, IL, IN, IR, IS, JP, KE, KG, KN, KP, KR,KZ, LA, LC, LK, LR, LS, LT, LU, LY, MA, MD, ME,MG, MK, MN, MW, IVIX, MY, MZ, NA, NG, NI, NO, NZ,OM, PA, PE, PG, PH, PL, PT, QA, RO, RS, RU, RW, SA,SC, SD, SE, SG, SK, SL, SM, ST, SV, SY, TH, TJ, TM,

[Continued on next page]

WO 2014/105977 Al

WO 2014/105977 A 11 ilii131111111111111111111i1111111111111111111111111111111111111111111TN, TR, TT, TZ U A , UG, US, UZ, VC, VN, ZA, ZM,ZW.

(84) Designated States (unless otherwise indicated, for everykind of regional protection available): ARIPO (BW,GM, KE, LR, LS, W V, MZ, NA, RW, SD, SL, SZ, TZ,UG, ZM, ZW), Eurasian (AM, AZ, BY, KG, KZ, RU, TJ,TM), European (AL, AT, BE, BG, CH, CY, CZ, DE, DK,EE, ES, FI, FR, GB, GR, HR, HU, IE, IS, IT, LT, LU,LV, MC, MK, MT, NL, NO, PL, PT, RO, RS, SE, SI, SK,

Published:

SM, TR), OAPI (BF, BJ, CF, CG, CI, CM, GA, GN, GQ,GW, KM, ML, MR, NE, SN, TD, TG).

with international search report (Art. 21(3))

before the expiration o f the time limit for amending theclaims and to be republished in the event o f receipt o famendments (Rule 48.2(h))

WO 2014/105977 P C T / U S 2 0 1 3 / 0 7 7 8 5 2

.A RADIOACTIVE MATERIALS STORAGE CANISTERAND NWT:1KM FOR SEALING SAME

Cross Reference to Related Applications

100011 Priority i s claimed t o U.S.. provisional application No. 611746,094, f i led

December 26, 2012, the disclosure of which is incorporated by reference in its entirety

Field of the Invention

100021 The field of the present invention relates to radioactive materials storage canisters.

Background of the Invention

10003i Virtually al l o f the used nuclear fuel produced in the United States and a

significant quantity generated overseas is stored in sealed canisters that have their parts

welded together. These canisters are sometimes referred to as multi-purpose canisters

(NIPCs). NI PCs are mostly manufactured from austenitic stainless steel but exotic alloys

such as Hastaloy, Inconel, etc., have also been considered. The typical MPG includes two

major parts, the first part being Ibrmed from an outer a cylindrical vessel having a

welded bottom bottom (base plate) and a flat top lid which is welded to the top of the cylindrical

vessel at the nuclear plant after the fuel is loaded inside the NIPC. The outer body of the

completed MPC is also referred to as an "enclosure vessel". The second part is theinternal structure, called a fuel basket, which stores the nuclear fuel in the desired

configuration. An M PC may also be used to store other forms o f high level waste,

although for ease of discussion the term "spent file!" is used to represent all forms of highlevel waste.

100041 The enclosure vessel i s responsible f o r maintaining confinement o f i ts

radiological contents including gaseous matter, under al l normal, off-normal, and

accident design conditions. The physical integrity o f the pressure retention and

confinement boundary of an NI PC is a fundamental safety requirement during storage and

transport. Accordingly, to ensure maximum protection against leakage, the enclosure

vessel is made using the rules of ASME Section III Class 1, which is the most rigorous

pressure vessel code in use in the United States. Pursuant to the provisions for Class

components in SeCtiOn 111 of the Code, all pressure boundary material in the Enclosure

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Vessel is ultrasonically examined and all body welds are subject to 100% volumetricexamination (e.g. radiography or ultrasonic testing (UT)). The state of the art, however,does not enable 100% volumetric examination of the top lid of the MIPC because the toplid can only be welded in the field, after the canister has been loaded with spent fuel. Theprocess of sealing the canister is therefore necessarily performed in the presence of a highradiation field around the canister, so that weld crews have limited physical access to thecanister when it is sealed due to the high radiation doses to which they would be exposed.Prompted by the need to prevent large dose exposure to the crew, the lid-to-shell (UrS)weld joint has historically been made as a partial penetration half-V groove or l-grooveweld (see Fig. 1), Such a weld is readily made by an automated weld machine having aweld arm designed to traverse the circular weld-path. The drawback is that the partialpenetration weld cannot be 100% volumetrically examined with an acceptable level ofaccuracy. However, the USNRC permits the root weld and successive passes to beexamined using by the less robust method of liquid penetrant (LP) examination. BecauseLP is a surface examination tool, the soundness o f the weld mass located betweensuccessive LP examinations cannot actually be examined,[00051 Efforts to devise a UT process to volumetrically examine the partial penetrationclosure weld thus far have not been successful. State-of the-art UT technology is capableof providing high quality volumetric examination of the entire closure weld mass withonly a small "blind spot" located at the tip of the root pass area, There are proposals toperform liquid penetrant examination of the root pass to confirm its quality, and after theroot pass has been checked for soundness, the balance of the weld mass may be examinedby UT. Regardless, although the risk of a hidden flaw in the closure weld propagatingunder a storage or transport event is extremely small, given the use of highly fractureresistant austenitic stainless steel material in the MPCs, the lack of the ability to subjectthe entire weld mass to 100% volumetric examination remains a weakness for enclosurevessels,

Summary of the Invention

100061 The present- invention is directed toward a canister for storing radioactivematerials, The lid of the canister is conflaured so that the entire V o 1 um e of the weld

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between the lid and the side wall of' the. canister may be subjected to a volumetricexamination

[0007] In a first separate aspect of the present invention, a canister for storing radioactivematerials includes a top plate, a base plate, and a side wall sealed together to form asealed vessel. The top plate includes a top surthee with a top edge having a bevel andwith a channel set in from the top edge. The top plate is sealed to the side wall by a weldformed between the beveled top edge and the top of the side wall. The base plate is sealedto the bottom of the side wall.

100081 In a second separate aspect of the present invention, a method of forming a sealedcanister includes placing a top plate on a top opening of a side wall, with the bottom ofthe side wall being sealed to a base plate. The top plate includes a top surface with a topedge having a bevel and with a channel set in from the top edge. A weld is formedbetween the beveled top edge and the top opening of the side wall to seal the top plate tothe side wall, thereby forming the sealed canister,100091 in a third separate aspect of the present invention, a method of storing radioactivematerials includes placing radioactive materials in a cavity formed by a side wall havinga bottom sealed to a base plate, ,A top plate is placed on a top opening of the side wall,wherein the top plate includes a top surface with a top edge having a bevel and with achannel set in from the top edge. A weld is formed between the beveled top edge and thetop opening of the side wall to seal the top plate to the side wall, so that the c-avity ishermetically sealed. A first probe is placed in the channel and a second probe is placedadjacent the side a l l opposite the first probe, such that the weld is disposed between thetwo probes. The first and second probes are activated to determine an integrity of avolume of the weld between the probes, and the probes are moved synchronously around

the top plate to determine the integrity of an entire volume of the weld,[0010] In a fourth separate aspect of the present invention, any of the foregoing aspectsmay be employed in combination,100111 .Accordingly, an imprOVed canister for storing radioactive materials and a method

of sealing the same are disclosed. Advantages of the improvements will be apparent fromthe drawings and the description of the preferred embodiment.

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Brief Description of the Drawings

100121 The foregoing summary, as well as the folkrwing detailed description o f the

exemplary embodiments, wi l l be better understood when read in conjunction with the.

appended drawings. It should be understood, however, that the invention is not limited to

the precise arrangements and instrumentalities shown in the following figures:

1001.3.1 Fig. I illustrates the top lid welded to the side wall of a canister according to the

prior art;

[0014] Fig. 2A illustrates a double-walled .M.PC having lids configured to allow 100%

volumetric examination of the respective closure weld;

[00151 Fig. 28 illustrates a single walled MPC: having a lid configured to allow 100c,'4volumetric examination of the closure weld;

100161 Fig 2C illustrates a detailed sectional view of a lid and closure weld, the lid beingFig.

configured to allow 100% volumetric examination of the closure weld;

100171 Fig. 3 illustrates a top elevation view o f a first l id configured to allow 0 %volumetric examination of the closure weld',

100181 Fig, 4 illustrates a top elevation view of a second lid configured to allow 100%

volumetric examination of the closure weld;

[00I9j Fig. SA illustrates a weld arm positioned to form a closure weld and probes

positioned to volumetrically examine the closure weld; and

100201 Fig. 5B illustrates a detailed sectional view of a lid, the weld head, and the probesof Fig,. SA.

Detailed Description of the Invention

10021 The description of illustrative embodiments according to principles of the present

invention is intended to be read in connection with the accompanying drawings, which

are to be considered part o f the entire written description. I n the description o f

embodiments of the invention disclosed herein, any reference to direction or orientation

is merely intended for convenience of description and is not intended in any way to limit

the scope of the present invention. Relative terms such as lower," "upper," "horizontal,"

"vertical," -above," "below," "up," "down," left," "right," "top" and "bottom" as well as

derivatives thereof (e.g., "horizontally," "downwardly," "upwardly," etc.) should be

construed to refer to the orientation as then described or as shown in the drawing under

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discussion. These relative terms are for convenience o f description only and do not

require that the apparatus be constructed or operated in a particular orientation unless

explicitly indicated as such. Terms such as "attached," ''affixed,— "connected,"

"coupled," "interconnected," and similar refer to a relationship wherein structures are

secured or attached to one another either directly or indirectly through intervening

structures, as well as both movable or rigid attachments or relationships, unless expressly

described otherwise. Moreover, the features and benefits of the invention are illustrated

by reference to the preferred embodiments. Accordingly, the invention expressly should

not be limited to such preferred embodiments illustrating some possible non-limiting

combinations of features that may exist alone or in other combinations o f features; the

scope of the invention being defined by the claims appended hereto.

100221 The lid 11 and top portion of a side wall 13 for an MPC of the prior art are shown

in Fig, 1, The top surface 15 of the lid 11 includes a beveled edge 17, and the closure

weld 19 joining the lid i i to the side wall 13 is formed in the space between the half V-

shaped space between the beveled edge 17 and the top portion of the side wall 13. As

shown, the weld is a through-thickness single groove weld V-shaped groove, although the

groove could instead be .1-shaped, Due the physical configuration of the lid, the sidewall,

and the closure weld, this type of closure weld is not susceptible to 100% volumetricexamination.

10023.1 A dual-walled MPC 201 is illustrated in Fig, 2A, and this N4PC 201 is configured

so that the closure weld may be subjected to 100% volumetric examination. The dual-

walled NIPC 201 may be used with any style of fuel basket, such as the one described in

United States Patent 5,898,747, issued Apri l 27, 1999. In some instances i t may be

possible to use the dual-walled NIPC 201 without a fuel basket, depending on the

intended function. Furthermore, the dual-walled MPC 201 may be used to store and/or

transport any type. of high level radioactive materials and is not limited to spent nuclearfuel,

100241 As will become apparent from the structural description below, the dual-walled

MPC 201 creates two independent containment boundaries about the storage cavity 203

which operate to contain both fluidic (gas and liquid) and particulate radiological matter

within the cavity 203, As a result, i f one containment. boundary were to fail, the other

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containment boundary will remain intact. \Vhjie theoretically the same, the containment

boundaries formed by the dual-walled MPC 201 about the cavity 203 can beliteralized in

many ways, including without. limitation a gas-tight containment boundary, a pressure

vessel, a hermetic containment boundary, a radiological containment boundary, and a

containment boundary f o r fluidic and particulate matter. These terms are used

synonymously throughout this application. in one instance, these terms generally refer to

a type of boundary that surrounds a space and prohibits all fluidic and particulate matter

from escaping from and/or entering into the space when subjected to the required

operating conditions, such as pressures, temperatures, etc.

[0025] Finality, while the dual-walled MPC 201 is illustrated and described in a vertical

orientation, i t is to be understood that the dual-walled MPC 201 can be used to store

andlor transport us load in any desired orientation, including at an angle or horizontally.

Thus, use o f all relative terms through this specification, including without limitation

"top," "bottom," "inner" and "outer," are used for convenience only and are not intended

to be limiting of the invention in such a manner.

10026.1 The dual-walled MPC 201 includes a first shell that acts as an inner shell 2.05 and

a second shell that acts as an outer shell 207. The inner and outer shells 205, 207 are

preferably cylindrical tubes and are constructed of a metal. Of course, other shapes can beused if desired. The inner shell 205 is a ttibular hollow shell that includes an inner surface

209, an outer surface 210, a top edge 212 and a bottom edge 215. The inner surface 209

of the inner shell 205 forms a cavity/space 2.03 for receiving and storing SNI". The cavity

203 is a cylindrical cavity formed about a central axis.

[0027] The outer shell 207 is also a tubular hollow shell that includes an inner surface

221, an outer surface 223, a top edge 225 and a bottom edge 227. The outer shell 207

circumferentially surrounds the inner shell 205. The inner shell 205 and the outer shell

207 are constructed so that the inner surface 221 o f the outer shell 207 is in substantiallycontinuous surface contact with the outer surface 223 o f the inner shell 205. In other

words, the interface between the inner Shell 205 and the outer shell 207 i.s substantially

free of gaps/voids such that. the two shells 205, 207 are in conformal contact. This can be

achieved through an explosive joining, a cladding process, a roller bonding process

andlor a mechanical compression process that bonds the inner shell 205 to the outer shell

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207. The continuous surface contact at the interface between the inner shell 2.05 and the

outer shell 207 reduces the resistance to the transmission of heat through the inner and

outer shells 205, 207 to a. negligible value. Thus, heat emanating from the spent nuclear

fuel loaded within the cavity 203 can efficiently and effectively be conducted outward

through the shells 2.05, 207 where it is removed from the outer surface 223 of the outershell via convection.

[002t1 The inner and outer shells 205, 207 are preferably both made of a metal. As used

herein, the term metal refers to both pure metals and metal alloys. Suitable metals include

without limitation austenitic stainless steel and other alloys including 1-lastelloy a n dInconel-1.m. Of course, other materials can be utilized. The thickness of each of the inner

and outer shells 205, 207 is preferably in the range o f 5 min to 25 mut The outer

diameter of the outer shell 207 is preferably in the range of 1700 InIn to 2000 mm. The

inner diameter of the inner shell 205 is preferably in the range of 1700 mm to 1900 mm.

The specific size and/or thickness of the shells 205, 207, however, is a matter of designchoice[0029] In some embodiments, i t may be further preferable that the inner shell 205 be

constructed o f a metal that has a coefficient o f thermal expansion that is equal to or

greater than the coefficient of thermal expansion of the metal of which the outer shell 207

is constructed. Thus, when the spent nuclear fuel that is stored in the cavity 203 emits

heat, the outer shell 207 will not expand away from the inner shell 20f.-; This ensures thatthe continuous surface contact between the outer surface 210 of the inner shell. 205 and

the outer surface 223 of the outer shell 207 will be maintained and a gaps will not formunder heat loading conditions.

100301 The duakvalled NIPC 201 also includes a first top plate that acts as an inner top

lid 229 for the inner shell 205 and a second top plate that acts as an outer top lid 231 for

the outer she'll 207. The inner and outer top lids 229, 231 are plate-like structures that are

preferably constructed of the same materials discussed above with respect to the shells

205, 207. Preferably the thickness of the inner top lid 229 is in the range of 99 min to 300

mm, The thickness of the outer top lid 231 is preferably in the range o f 50 min to 150

inm 'File invention is not however„ limited to any specific dimensions, ix lnch will be

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dictated on a case-by-case basis and the radioactive levels of the spent nuclear fuel to bestored in the cavity 203,

[00311 The inner top l id 229 includes a top surface 233 with a beveled edge 235, a

bottom surface 237, an outer lateral surface/edge 239, and a channel 241 formed in the

top surface 233 and set in from the bevelled edge 235, The outer top lid 231 includes a top

surface 243 with a beveled edge 245, a bottom surface 247, an outer lateral surface/edge

249, and a channel 251 formed in the top surface 243 and set in from the beveled edge

245. When fully assembled, the outer lid 2.31 is positioned atop the inner lid 229 so that

the bottom surface 247 of the outer lid 231 is in substantially continuous surface contact

with the top surface 233 of the inner lid 229 Both the inner top lid 229 and the outer top

lid 231 also include vent and/or drain ports 253, 255,

[0032] During loading procedure involving spent nuclear fuel, the cavity 203 is loaded

with the spent nuclear fuel, then the inner top lid 229 is positioned so as to enclose the

top end of the cavity 203 and rests atop brackets (not shown). Once the inner top lid 229

is in place, a closure weld is formed to seal the inner top lid 229 to the inner shell 205.

The top l id 229 may be welded to the inner shell 205 using any suitable welding

technique or combinations of techniques that use a filler material. Examples of suitable

welding techniques include, resistance seam welding, manual metal arc welding, metal

inert gas welding, tungsten inert gas welding, submerged arc welding, plasma arc

welding, gas welding, electroslag welding, thermit welding,

[0033] After the cavity 203 is sealed by the closure weld, it may then be evacuated/dried

via the appropriate method and backfilled with nitrogen, helium or another inert gas using

the ports 249 of the inner lid 229 that form passageways into the cavity 203. The ports

249 may thereafter be filled with a metal or other wise plugged so as to hermetically seal

the cavity 2,03,

[0034] The outer shell 207 has an axial length that is greater than the axial length of the

inner shell 205—As such, the top edge 225 of the outer shell 207 extends beyond the top

edge 211 o f the inner shell 205. Similarly, the bottom edge 227 of the outer shell 207

extends beyond the bottom edge 215 of the inner shell 205

[0035] The offset between the top edges 211, 225 o f the shells 205, 207 allows the top

edge 211 o f the inner shell 205 to act as a ledge for receiving. and supporting the outer top

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lid 231. When the inner top lid 2.29 is in place, the inner surface 209 of the inner shell

205 extends over the outer lateral edges 239_ When the outer top l id 231 i s then

positioned atop the inner lid 229, the inner surface 221 o f the outer shell 207 extends over

the outer lateral edge 249 of the outer top lid 231. The top edge 225 of the outer shell 207

is substantially flush with the top surface 253 of the outer top lid 231. The inner and outer

top lids 229 231 are welded to the inner and outer shells 205, 207 respectively after the

fuel is loaded into the cavity 203. Similar to the inner top lid 229, once the outer top lid

231 is in place_ a closure weld is formed to seal the outer top lid 231 to the outer shell

207. The outer top l i d 231 m a y be welded t o the outer shell 207 using any

suitable welding technique or combinations o f techniques that use a fi l ler material.

Examples of suitable welding techniques include resistance seam welding, manual metal

arc welding, metal inert gas welding, tungsten inert gas welding, submerged arc welding,

plasma arc welding, gas welding, electroslag welding, thenuit welding. The closure

welds sealing the inner and outer top lids 229, 231 to the inner and outer shells 205, 207

may be subjected to 100°,1,; volumetric examination once the welds are formed. It is to be

understood that the closure weld for the inner top lid 2.29 is to undergo volumetric

examination before the outer top lid 231 put in place.

100361 The dual-walled N1PC 201 also includes a first plate that acts as an inner base

plate 265 and a second plate that acts as an outer base plate 267. The inner and outer base

plates 265, ) a re rigid plate-like structures having circular horizontal eross-seenuns,

The invention is not so limited, however, and the shape and size of the base plates is

dependent upon the shape of the inner and outer shells. The inner base plate 265 includes

a top surface 269. a bottom surface 271 and an outer lateral surface/edge 273. Similarly,

the outer base plate 267 includes a top surface 275 a bottom surface 277 and an outerlateral surface/edge 279.

E00371 The top surface 269 of the inner base plate .265 forms the floor of the cavity 203.

The inner base plate 265 rests atop the Miter base plate 267, Similar to the other

corresponding components of the dual-walled NIPC: 201, the bottom surface 271 o f the

inner base plate 265 is in substantially continuous surface contact with the top surface

275 of the outer base plate 2.67. As a result, the interface between the inner base plate 265

and the outer base plate 267 is free o f gaseous gaps/voids for thermal conduction

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optimization —An explosive joining, a cladding process, a roller bonding process and/or a

mechanical compression process can be used to effectuate the contact between the base

plates 265, 267. Preferably, the thickness of the inner base plate 265 is in the range of 50

mm to 150 mm, The thickness of the outer base plate 267 is preferably in the range of 99

mm to 200 MID Preferably, the length from the top surface of the outer top lid 231 to the

bottom surface of the outer base plate 267 is in the range of 4000 mm to 5000 mm, but

the invention is in no way limited to any specific dimensions.

[0038l The outer base plate 267 may be equipped on its bottom surface with a grapple

ring (not shown) f i r handling purposes, The thickness of the grapple ring is preferably

between 50 mm and 150 mm. The outer diameter o f the grapple ring is preferablybetween 350 inm and 450 mm,

[0039] The inner shell 205 rests atop the inner base plate 265 in a substantially upright

orientation. The bottom edge 215 of the inner shell 205 is connected to the top surface

275 of the inner base plate 265 by a through-thickness single groove (V or 3 shape) weld.

The outer surface 210 of the inner shell 205 is substantially flush with the outer lateral

edge 273 o f the inner base plate 265. The outer shell 207, which circumferentially

surrounds the inner shell 205, extends over the outer lateral edges 273, 279 of the inner

and outer base plates 265, 267 so that the bottom edge 227 o f the outer shell 207 is

substantially flush with the bottom surface 277 o f the outer base plate 267. The inner

surface 221 o f the outer shell 207 is also connected to the outer base plate 267 using a

through-thickness edge weld. In an alternative embodiment, the bottom edge 227 of the

outer shell 207 could rest atop the top surface 275 of the outer base plate 267 (rather than

extending over the outer later edge of the base plate 267). in such an embodiment, the

bottom edge 227 o f the outer shell 207 could be welded to the top surface 275 of the

outer base plate 267.

[0040] When all o f the seal and closure welds discussed above are completed, the

combination of the inner shell 205, the inner base plate 2.65 and the inner top l id 229

forms a first hermetically sealed structure surrounding the cavity 203, thereby creating afirst pressure vessel. Similarly, the combination of the outer shell 207, the outer base

plate. 267, and the outer top l id 231 form a second sealed structure about the first

hermetically sealed structure, thereby creating a second pressure vessel about the first

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pressure vessel and the cavity 2.03. Theoretically, the first pressure vessel is located

within the internal cavity o f the second pressure vessel_ Each pressure vessel i s

engineered to autonomously ineet the stress limits of the ASN4E Code with significant

margins.

10041] Fig. 2B illustrates a single-walled MPC 285 which is constructed in a similar

manner as each pressure vessel o f the double-walled IMPC 201 discussed above. This

single-walled N4PC 287 includes a side wall 289 seal welded to a base plate 291, and a

top plate 293. 'the top surface 295 of the top plate 293 includes a beveled top edge 297

and a channel 2,99 set in from the top edge 297. Having the l id configured with the

channel 299 makes i t so that the closure weld may be subjected to 100% volumetric.

examination. A l l other parts o f the single-walled NIPC 285 may be constructed in thesame manner described above.

100421 A detailed view a top plate 311 and the closure weld 313 sealing the top plate 311

to a side wall 315 o f an 1\4PC are illustrated in Fig, 2C. The channel 317 in the top

surface 319 is set in from the beveled top edge 321. The channel 317 extends below the

top surface 319 at least as much as does the bevel of the beveled top edge 321 i n some

embodiments, depending upon the configuration o f the probe being used, i t may be

desirable to have the channel 317 extend deeper below the top surface than the bevel in

order to accommodate the probe. The channel 317 is sufficiently wide so that a probe

used for examining the closure \veld may be placed within the channel 317 and moved

circumferentially around the top plate 311 for purposes of achieving 100% volumetric

examination of the closure weld. For some types of probes, the channel may be as wide

as 2" to 3”, although these dimensions may vary significantly to accommodate the

configuration of the probe used to examine the closure weld. The side wall 323 o f the

channel 317 nearest the beveled top edge 321 is placed at an angle that is approximately

parallel to the angle o f the beveled top edge 321. However, in some embodiments the

angle of this channel side \vall may vary from the angle of the top beveled edge by 5' —

20' or more, depending upon the configuration of probe being used. The side wall 323,

however, may be formed at any angle relative to the beveled top edge 321. The opposite

wall 325 of the channel 317 may have any configuration, from a well-defined wall, as is

shown, to a curved or flat surface adjoining the bottom 327 of the channel 317.

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10043] One embodiment of a top plate 331 is shown in Fig. 3 with ports 333 positioned

in the central portion 335 of the top surface 337 of the top plate 331, radially inward from

the channel 339. The ports 333 may SeltVe any desired purpose for the IVIPC for which the

top plate 331 is used and the different ports may be used for different purposes.

Examples of purposes tbr the ports include their use as vent ports, as vacuum ports, as

drain ports, as backfill ports, as test ports, among others. Another embodiment of a top

plate 341 is shown in Fig. 4 I n this embodiment, the ports 343 are positioned within the

channel 345. In other embodiments, ports may be positioned both within the channel and

in the central portion of the top surface of the top plate.

[0044] Figs. 5 A and 5B illustrate the process o f performing the 100%i volumetric

examination of the closure weld after it has been formed. With the top plate in place on

the top opening of the sidewall, the top plate having a channel as described above, the

closure weld may be formed by automated equipment, such as is well known in the art. In

order to volumetrically examine the closure weld, probes are mounted on a support arm

capable of rotating and positioning the probes to perform the volumetric examination of

the closure weld. For example, the probes may be mounted on the same type of weld arm

that is used in the automated process for forming the closure weld. The volumetric

examination may be carried out once the entire weld is formed.

100451 Only the end of the support arm 371 is illustrated in Fig. 5A to simplify the

drawing. I t i s to be understood that the support arm may have any appropriate

configuration that is capable of supporting the probes and moving them around the top

plate to perform the volumetric examination, as many different types and configurations

of such support a rms a r e well-known i n t h e arts, including combination

rotary/articulating robotic arms. Two probes 373, 375 are affixed to the end o f the

support arm 37 t, and the support arm is confiaured for automated or remote positioning

of the probes so that the volumetric examination of the closure weld may be performed.

The first probe 373 is positioned on the outside of the top o f the side wall 377, and the

second probe 375 is shown just prior to being positioned within the channel 379 formed

in the top surface 381 o f the top plate 383. This second probe 375 is shown positioned

within the channel 379 in Fig. 5B Once the two probes are in position, the entire volume

of a portion of the closure weld is disposed between the two probes, and that entire

12

WO 2014/105977 P C T / U S 2 0 1 3 / 0 7 7 8 5 2

volume may be volumetrically examined. By activating the two probes and moving themsynchronously around the top plate, maintaining their relative position \vith respect to theclosure weld, the entirety o f the weld is passed between the two probes in onecircumscription of the top plate, It is therefore possible, with the appropriate examinationtechnology, to perform a 100% volumetric examination of the closure weld. Using well-known processes associated with the selected examination technology, the integrity of theentire closure weld may be determined from the examination,[0046] In the embodiment of Fig. 5A, the entire closure weld is formed first, followed bythe volumetric examination of the closure weld. In the embodiment of Fig. 513, the weldhead 385 extends from the same support arm (not shown in Fig, 58) as the probes 373,375. The weld arm then moves the weld head around the top edge of the top plate to formthe closure weld, and the probes trail the weld head to perform the volumetricexamination. This embodiment may be used to form the weld and substantiallyconcurrently volumetrically examine the weld. For a multi-pass closure weld, having theprobes trail the weld head in this manner enables a separate volumetric examination ofeach pass of the closure weld. Due to the heat generated from the welding process, whichmay interfere with the examination process, this embodiment may be best suited for usein pools or in the presence of a coolant, such as a flow of demineralized water[00471 in certain embodiments, a Linear Scan-Phased Array UT system may be used toexamine the closure weld, and for such embodiments the probes are ultrasoundtransducer probes. Such a I T system is capable of conducting,' the 100% vohtmetricexamination of the closure weld within a matter of minutes. Beneficially, with the topplate configured as described above and with use of the two probes, no human activityneeds to be directly involved for placing the top plate, forming the closure weld, orexamining the integrity of the closure weld, so that work crews are not exposed to anysignificant doses of radiation.

100481 In embodiments where a UT system is used outside of a pool of water or otherfluid, a coupling agent, such as demineratized water or an appropriate gel, may beintroduced between the transducer probes and the top plate and/or side wall to increasethe amount of ultrasound energy that passes into the closure weld, thereby improving thevolumetric examination. As is well known in the art of UT, only small amounts of the

13

WO 2014/105977 P C T / U S 2 0 1 3 / 0 7 7 8 5 2

coupling agent are needed to form a thin f i lm, minimizing air gaps, between the

transducer probe and the parts o f the NIPC into which the ultrasound energy is being

directed. Therefore, a simple drip system suffices to introduce a coupling agent such as

demineralized water to the process of volumetric examination described herein.

100491 in embodiments involving a high heat load canister, to ensure that the metal

temperature o f the weld mass is not too high for an accurate UT reading, i t may be

necessary to circulate cooling water through the MPC using the vent and drain ports in

the lid before performing the volumetric examination. As an alternative, the use o f a

coupling agent fo r ultrasound eneray, such as demineralized water, between the

transducer probes and the IMPC. helps to insure that the volumetric examination is

performed at a uniform temperature, thereby preserving the UT calibration integrity.

[00501 While the invention has been described with respect to specific examples

including presently preferred modes of carrying out the invention, those skilled in the art

will appreciate that there are numerous variations and permutations o f the above

described systems and techniques. I t is to be understood that the concepts and ideas

disclosed herein can be applied to other areas of high level radioactive waste storage,

transportation and support. I t is also to be understood that other embodiments may be

utilized and structural and functional modifications may be made without departing from

the scope of the present invention. Thus, the spirit and scope of the invention should be

construed broadly as set forth in the appended claims,

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WO 2014/105977 P C T / U S 2 0 1 3 / 0 7 7 8 5 2

What is claimedClaims

1. A canister for storing radioactive materials, the canister comprising:a base plate;a side wall having a bottom sealed to the base plate; anda top plate including a top surface with a top edge having a bevel and with a

channel set in from the top edge, wherein a weld is formed between the beveled top edgeand a top of the side wall to seal the top plate to the side wall, and

wherein the base plate, side wall, and top plate form a sealed vessel.

") T h e canister of claim I. wherein the base plate, side wall, and top plate form ahermetically sealed vessel.

3. T h e canister of any of the preceding claims, wherein the circumferential channelis approximately as deep as the bevel extends below the top surface,

4. T h e canister of claims 1 or 2, wherein the circumferential channel is deeperthe bevel extends below the top surface,

5. T h e canister of any of the preceding claims, wherein the bevel is formed as one ofa J-cut or a half-V-cut.

6. T h e canister of any of the preceding claims, wherein the top plate includes one ormore ports therethrough,

7. T h e canister of claim 6, wherein at least one of the ports is disposed in thechannel.

8. T h e canister of any of the preceding claims, wherein the side wall forms one oftwo walls of a double-walled canister.

A method of forming a sealed canister, the method comprising

1.5

WO 2014/105977 P C T / U S 2 0 1 3 / 0 7 7 8 5 2

placing a top plate on a top opening of a side wall, a bottom of the side wall being

sealed to a base plate, wherein the top plate includes a top surface with a top edge having

a bevel and with a channel set in from the top edge; and

forming a weld between the beveled top edge and the top opening of the side wall

to seal the top plate to the side wall

10_ T h e method of claim 9, further comprising:

placing a first probe in the channel and a second probe opposite the first probe

and adjacent the side wall, such that the weld is disposed between the two probes;

activating the first and second probes to determine an integrity of a volume of theweld between the probes; and

moving the first and second probes synchronously around the top plate to

determine the integrity of an entire volume of the weld,

11. T h e method of claims 9 or 10, wherein the base plate, side wall, and top plate

form a hermetically sealed vessel.

12, T h e Method of any of claims_ 9 through -11,. wherein the Cite unfei'entiM Channel is

approximately as deep as the bevel extends below the top surface,

3. T h e method of any of claims 9 through 11, wherein the circumferential channel

deeper than the bevel extends below the top surface.

14. T h e method of any of claims 9 through 13, wherein the bevel is formed as one ofa ,l-cut or a half V-cut_

15. T h e method of any of claims 9 through 14, wherein the first and second probes

comprise ultrasound probes.

16. A method of storing radioactive materials, the -method comprising:placing radioactive materials in a cavity formed by a side wall having a bottom

Sealed to a base plate;

placing a top plate on a top opening of the side wall, the top plate including a top

surface with a top edge having a bevel and with a Channel set in from the top edge;

1.6

WO 2014/105977 P C T / U S 2 0 1 3 / 0 7 7 8 5 2

.:forming a weld between the beveled top edge and the top opening of the side wall

to seal the top plate to the side wall, so that the cavity is sealed;placing a first :probe in the channel and a. second probe opposite the first probe

and adjacent the side wall, such that the weld is disposed between the two probes;activating the first and second probes to determine an integrity of a volume of the

weld between the probes, andmoving the -first and second probes synchronously around the top plate to

determine the integrity of an entire volume of the weld,

FT, T h e Method of claim 16, ,4eteiti the circumferential channel is approximately asdeep as the bevel extends below.the top surface,

18, T h e Method of claim 16, wherein the circumferential channel is deeper than the'bevel extends below •the top surface,

19. T h e method of any of claims 16 through 18; wherein the bevel is formed as one ofa J-cut or a half V-cut,

20, T h e method of any of claims 16 through 19, wherein the cavity is hermetically bythe formed weld,

17

WO 2014/105977 P C T / U S 2 0 1 3 / 0 7 7 8 5 2

1/8

LI-

WO 2014/105977 P C T / U S 2 0 1 3 / 0 7 7 8 5 2

245

229 241 2 4 7239

W 4 I

233235

253 o s o 2 3 7

225

221223

269

227

231243

2/8

271

273 2 7 9FIG. 2A

251 255

249

211

205

207

209

210

203

275215

265

267277

WO 2014/105977 P C T / U S 2 0 1 3 / 0 7 7 8 5 2

3/8

FIG. 2B

285

WO 2014/105977

4/8

PCT/US2013/077852

WO 2014/105977

5/8

333

FIG. 3

PCT/US2013/077852

331

333

WO 2014/105977

6/8

FIG.4

PCT/US2013/077852

WO 2014/105977

7/8

FIG. 5A

PCT/US2013/077852

WO 2014/105977 P C T / U S 2 0 1 3 / 0 7 7 8 5 2

Cr)

8/8

Form PCT/ISA/210 (second sheet) (July 2009)

INTERNATIONAL SEARCH REPORT International application No. •PCT/US 13/77852

A. C L A S S I F I C A T I O N OF SUBJECT M AT T E RIPC(8) - G21 F 5/00 (2014/01)USPC - 588/16

'According to International Patent Classification (IPC) or to both national classification and IPC

B. F I E L D S SEARCHED

Minimum documentation searched (classification system followed by classification symbols)USPC - 588/16IPC(8) - G21 F 5/00 (2014/01)

Documentation searched other than minimum documentation to the extent that such documents are, included in the fields searchedIPC(8) - G21F 5/00 (2014/01)USPC - 588/16,1,17; 250/505.1,506.1,507.1 (keyword limited; terms below)

Electronic data base consulted during the international search (name of data base and, where practicable, search terms used)PatBase; PubWEST; Google Scholar; ScienceDirectSearch Terms Used: container, weld, seal, lid, cover, channel, probe, bevel, radioactive, nuclear, hazardous, canister, groove, integrity,holder.

C. D O C U M E N T S CONSIDERED TO BE RELEVANT -

Category* Citation of document, with indication, where appropriate, o f the relevant passages Relevant to claim No.

Y US 2008/0265182 Al (SINGH et al.) 30 October 2008 (30.102008), entire document, 1-4, 9, 10, 11/(9), 11/(10),especially; FIG 1, para [0002], [0021), [0023], [0046]-[0050], [0054], [0058] 16-19

Y US 4,596,688 A (POPP) 24 June 1986 (24.06.1986), entire document, FIG 3, col 1, In 6-13, col 1-4, 9, 10, 11/(9), 11/(10),2, In 17-41, col 5, In 54 to col 6, In 22 16-19

Y US 5,161,413 A (RAKER et al.) 10 November 1992 (10.11.1992), entire document, col 7, In 54to col 8, In 25

10, 11/(10), 16-19.

A US 2004/0020919 Al (HIRANO et al.) 05 February 2004 (05.022004), entire document 1-4, 9, 10, 11/(9), 11/(10),16-19

,A US 2011/0049155 Al (LEVINE et al.) 03 March 2011, (03.03,2011), entire document 1-4, 9, 10, 11/(9), 11/(10),

16-19

Further documents are listed in the continuation o f Box C.

* S p e c i a l categories of cited documents: " T " la ter document published after the international filing date or priority"A" document defining the general state of the art which is not considered d a t e and not in conflict with the application but cited to understand

to be of particular relevance t h e principle or theory underlying the invention"E" earl ier application or patent but published on or after the international " x " document of particular relevance; the claimed invention cannot be

filing date c o n s i d e r e d novel or cannot be considered to involve an inventive- "L" document which may throw doubts on priority claim(s) or which is s t e p when the document is taken alone

cited to establish the publication date of another citation or other „ Y" document of particular relevance; the claimed invention cannot bespecial reason (as specified) c o n s i d e r e d to involve an inventive step when the document is

" 0 " document referring to an oral disclosure, use, exhibition or other c o m b i n e d with one or more other such documents, such combinationmeans b e i n g obvious to a person skilled in the art

"P" document published prior to the international filing date but later than "84" document member of the same patent familythe priority date claimed

Date of the actual completion of the international search Date o f mailing of the international search report

29 April 2014 (29.04.2014) 2 1 MAY.2014Name and mailing address of the ISA/US Authorized officer:Mail Stop PCT, Attn: ISNUS, Commissioner for Patents Lee W. YoungP.O. Box 1450, Alexandria, Virginia 22313-1450

PCT Helpdesk: 571-272-4300Facsimile No, 571-273-3201 PC T OSP: 571-272-7774

INTERNATIONAL SEARCH REPORT International application No.PCT/US 13/77852

Box No. I I Observa t ions where certain claims were found unsearchable (Continuation of item 2 of first sheet)

This international search report has not been established in respect of certain claims under Article I7(2)(a) for the following reasons:

1 C l a i m s Nos.:because they relate to subject matter not required to be searched by this Authority, namely:

2. E l Claims Nos.:because they relate to parts of the international application that do not comply with the prescribed requirements to such anextent that no meaningful international search can be carried Out, specifically:

3.E Claims Nos.: 5-8; 12-15, 20because they are dependent claims and are not drafted in accordance with the second and third sentences of Rule 6.4(a).

Box No. l i t Observat ions where unity of invention is lacking (Continuation of item 3 of first sheet)

This International Searching Authority found multiple inventions in this international application, as follows:

I. D A s all required additional search fees were timely paid by the applicant, this international search report covers all searchableclaims.

2. E l A s all searchable claims could be searched without effort justifying additional fees, this Authority did not invite payment ofadditional fees.

3. A s only some of the required additional search fees were timely paid by the applicant, this international search report coversonly those claims for which fees were paid, specifically claims Nos.:

4. N o required additional search fees were timely paid by the applicant. Consequently, this international search report isrestricted to the invention first mentioned in the claims; i t is covered by claims Nos.:

Remark on Protest • T h e additional search fees were accompanied by the applicant's protest and, where applicable, thepayment of a protest fee.

▪ T h e additional search fees were accompanied by the applicant's protest but the applicable protestfee was not paid within the time limit specified in the invitation.

• N o protest accompanied the payment of additional search fees.

Form PCT/ISA/210 (continuation of first sheet (2)) (July 2009)