Patent Publication Number: US-11391550-B1

Title: Cook-off mitigation systems

Description:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     The invention described herein may be manufactured and used by or for the government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor. 
    
    
     FIELD 
     The embodiments generally relate to insensitive munitions. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view of an outgassing pad, according to some embodiments. 
         FIG. 2A  is a section view of an outgassing pad with a shell, according to some embodiments. 
         FIG. 2B  is a section view of an outgassing pad without a shell, according to some embodiments. 
         FIG. 3A  is a nose end perspective view of the outgassing pad in  FIG. 1 , according to some embodiments. 
         FIG. 3B  is a tail end perspective view of the outgassing pad in  FIG. 1 , according to some embodiments. 
         FIG. 4  a close-up of a partial section view of a charging well, according to some embodiments. 
         FIG. 5  is a partial section view of a cook-off mitigation system in a generic munition, according to some. 
         FIG. 5A  is a partial cutaway section view of the tail end of the system in  FIG. 5 , according to some embodiments. 
         FIG. 6  is an exemplary exploded view of a eutectic device that can be used in some embodiments. 
         FIG. 7  is a close-up partial section view of a gas sealing device shown in its operating environment. 
         FIG. 8  is an inverted isometric view of some components in the charging well from  FIG. 4 . 
     
    
    
     It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not to be viewed as being restrictive of the embodiments, as claimed. Further advantages of the embodiments will be apparent after a review of the following detailed description of the disclosed embodiments, which are illustrated schematically in the accompanying drawings and claims. 
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Embodiments may be understood more readily by reference in the following detailed description taking in connection with the accompanying figures and examples. It is understood that embodiments are not limited to the specific devices, methods, conditions or parameters described and/or shown herein, and that the terminology used herein is for the purpose of describing particular embodiments by way of example only and is not intended to be limiting of the claimed embodiments. Also, as used in the specification and appended claims, the singular forms “a,” “an,” and “the” include the plural. 
     Embodiments generally relate to insensitive munitions (IM) improvements, especially with respect to cook-off mitigation systems. Some embodiments employ an outgassing pad in the nose of the munition. Additional embodiments employ a releasable (two-part) charging well. Further embodiments combine these approaches with a releasable tail closure mechanism. 
     Although the embodiments are described in considerable detail, including references to certain versions thereof, other versions are possible. Examples of other versions include orienting and/or attaching components in different fashion. Therefore, the spirit and scope of the appended claims should not be limited to the description of versions included herein. 
     Components and Materials Used 
     In the accompanying drawings, like reference numbers indicate like elements. Reference characters  100 ,  400 , and  500  are used to depict various embodiments. Several views are presented to depict some, though not all, of the possible orientations of the embodiments. Some figures depict section views and, in some instances, partial section views for ease of viewing. The patterning of the section hatching is for illustrative purposes only to aid in viewing and should not be construed as being limiting or directed to a particular material or materials. Unless stated otherwise, components depicted are dimensioned to be close-fitting and to maintain structural integrity both during storage and while in use. 
     Components used in several embodiments, along with their respective reference characters, are depicted in the drawings. Reference character  100  depicts an outgassing pad. In some embodiments, the outgassing pad  100  includes a shell  102  and an outgassing agent  104 , such as a powder and binder mix. The shell  102  can be an elastomeric shell such as silicone, rubber, or silicone-rubber. The outgassing agent  104  is a powder and binder mix. The elastomeric shell  102 , may also be referred to as an outgassing shell, container, or bladder, and can be used to house the outgassing agent  104  as a technique for controlled fragmentation, enhanced gas containment, and as a reduction in compatibility concerns. A person having ordinary skill in the art will recognize the term compatibility concerns to be synonymous with assuring that chemicals coming in contact with an explosive fill are chemically compatible. 
     In other embodiments, the shell  102  can be a non-elastomeric shell such as plastic. In yet other embodiments, the shell  102  can be eliminated. In embodiments without a shell  102 , the outgassing pad  100  is the outgassing agent  104 , as discussed further below. The surface contours of the outgassing pad (reference character  100 ) with a shell (reference character  102 ) as well as the outgassing pad without the shell are the same. Section views best illustrate the outgassing pad  100  embodiments. Generically, the outgassing pad is depicted with reference character  100 . Reference character  100 A depicts the section view of an outgassing pad with a shell, as shown in  FIG. 2A . The embodiment in  FIG. 2A  can also be referred to as a confined or canistered outgassing pad  100 A. Conversely, as shown in  FIG. 2B , reference character  100 B depicts the section view of an outgassing pad without a shell, and can be referred to as an unconfined or uncanistered outgassing pad. 
     The shell  102  has unique geometrical configurations, including surface contours having a sigmoid shape, ogee shape, or a cyma recta shape. A person having ordinary skill in the art will recognize that ogee and cyma recta are understood to be types of sigmoid shapes. A person having ordinary skill in the art will recognize that a sigmoid shape is a shape similar to the letter S. Likewise, a person having ordinary skill in the art will recognize that an ogee shape is descriptive of an S-shape and, moreover, is characteristic of two curves meeting at a point. Additionally, a person having ordinary skill in the art will recognize that a cyma recta shape is descriptive of double curvature, combining both convex and concave features. A person having ordinary skill in the art will also recognize, after viewing  FIG. 2A , that the shell  102  can have a first portion  210 A that is characteristic of a rounded trapezoid, truncated ogive or truncated ogival shape, and a second portion  212 A that is sigmoid-shaped, ogee-shaped, or cyma recta-shaped. Likewise, the first portion  210 A can also have a meplat shape. A person having ordinary skill in the art will recognize that the word meplat is used in ballistics and is a technical term for a flat or open tip on the nose of a bullet. The selected shapes are based on reducing stress concentration during obturation and also shock wave focusing during target penetration. 
     Likewise, the surface contour shapes are also applicable to the embodiment depicted in  FIG. 2B  by reference characters  100 B,  210 B, and  212 B. Specifically, the outgassing pad without the shell (reference character  100 B) can also have a first portion  210 B that is characteristic of a rounded trapezoid, or meplat, truncated ogive, or truncated ogival-shape, and a second portion  212 B that is sigmoid-shaped, ogee-shaped, or cyma recta-shaped. The selected shapes are based on reducing stress concentration during obturation and also shock wave focusing during target penetration. 
     Selection of the outgassing agent  104  is based on several factors including volume-to-mass ratio of decomposition products, activation temperature, compatibility and stability, cost, material availability, and environmental concerns. The outgassing agent  104  is a powder-binder mix. Suitable powders for the outgassing agent  104  include a blowing agent mixed with an activator. Suitable blowing agents include oxydibenzenesulfonyl hydrazide (OBSH) or azodicarbonamide (ADC), due to their cell structures. The blowing agent is mixed with the activator to tune the decomposition temperature and rate. In the embodiments, zinc oxide is a suitable activator. Depending on application-specific requirements, other activators can also be used. Additionally, in other embodiments, an activator may not be needed depending on the blowing agent selected or other system requirements. Suitable binders for the outgassing agent  104  include wax, tar, or an energetic binder. Binder formation includes melt cast methods for waxes, cast-curing from a mold, and press-molding for the powder-binder mixes. 
     In the unconfined embodiment ( 100 B in  FIG. 2B ), the outgassing pad  100  is an outgassing agent  104  held in a specific geometry by incorporating a binder. Thus, in some embodiments, the elastomeric shell  102  can be eliminated by mixing the outgassing agent&#39;s  104  powder (such as azodicarbonamide and zinc oxide) and an activator such as zinc oxide with a binding agent such as, for example, asphaltic hot mix or Epolene wax. The mixture allows for the application of the outgassing agent (and hence the outgassing pad  100 B) and binder to be applied directly to the wall of the munition  502  as a liner. 
     The powders in the outgassing agents  104  will compact appreciably during target penetration, which is undesirable. Adding the binder to create a powder-binder mix eliminates this concern because the binder fills the void spaces between the particles of the powder which constitutes the powder, thus reducing the compaction. The mixture of the powder-binder is determined based on application-specific conditions. In some embodiments, the powder (azodicarbonamide and zinc oxide) is a range of about 66 to about 68 percent and the binder is 30 percent. The variation in constituents is from varying percentages of additive(s) used to tune the peak exothermal temperature. 
     Instances having different ranges are also possible and can be dependent on the processing of the material such as particle size, particle geometry, packing fraction, and wettability. Additionally, the cost of manufacturing/processing the material can drive one process over another which can correspondingly change the requisite ranges. Based on this, in other embodiments, the range is about 60 percent to about 70 percent powder, and a binder range of about 30 to about 40 percent, with the remaining constituents being additive(s) used to tune the peak exothermal temperature. Likewise, when tuning the powder-binder mix to expel a munition&#39;s explosive billet, the unique characteristics of that specific munition can drive the percentages. As such, a larger/different range can be beneficial in addressing the maintaining of the mass properties of a munition system by adjusting the powder-binder mixture to closely match the density of the munition&#39;s main explosive billet, thus avoiding changes to flight or performance characteristics. 
     Reference character  400  depicts a charging well that is housed entirely in the munition casing  504 , with no portion inside the explosive fill. The charging well  400  employs a charging well component  408 , fasteners  414 , a cutting device  415 , sometimes referred to as a cutter, knife blade or other variation, and a eutectic charging tube extension  413 . The charging well component  408  is generically depicted because the embodiments are applicable to a variety of charging well components without detracting from the merits or generalities of the embodiments. The charging well component  408  is contoured to match the munition case  504  interior contours, defined by a cavity  402  in the munition case  504 . Additionally, a person having ordinary skill in the art will recognize the specific components used in charging wells. The charging well component  408  is a structural material and, in most embodiments, is steel. A protective liner  411  is shown in some embodiments. Suitable liner materials include asphaltic hot melt, wax coating, and plastic. 
       FIG. 5  depicts a cook-off mitigation system  500  in a generic munition  502 . In addition to the outgassing pad  100  and charging well  400 , the system  500  includes a munition casing  504  with an interior wall  506  defining at least one interior compartment configured to house an explosive fill  508 . The interior wall  506  is the interior surface of the munition casing  504 . As such, reference character  506  is used herein for both the interior wall and the interior compartment since the interior wall defines the interior compartment. At times the explosive fill  508  is referred to as an explosive billet or simply as an explosive without detracting from the merits or generalities of the embodiments. Steel conduit  518 , sometimes referred to as a charging tube, can be used to house cable (not shown for ease of view) transmitting power and/or signals between the charging well  400  and a steel fuze well  511 . References to the use of steel herein also include steel alloys. A releasable tail closure mechanism  512  employs a base plug  514  and releasable base plate  516 . 
     Additional components are shown for orientation purposes and to assist in understanding operating environments. In particular,  FIG. 5  is very useful for illustrating an operating environment for several of the features employed in the embodiments. A synthetic felt pad  520  is generically shown and can be used in some munitions to provide ullage space, but is not needed in all munitions. Sealant  522  is also generically shown, and is used to prevent slumping of the explosive billet  508  during curing in some, but not all munitions. A steel fuze well retaining ring  524  assists in securing the fuze well  511  to the munition casing  504 . Eutectic devices, such as eutectic retaining nuts and plates, are used and are discussed in greater detail below. 
     Apparatus and System Embodiments 
     An outgassing pad for cook-off mitigation is depicted by reference character  100  in  FIGS. 1, 3A, 3B , &amp;  5 . The outgassing pad for cook-off mitigation  100  is sometimes referred to simply as an outgassing pad, pad, and the like, without detracting from the merits or generalities of the embodiments.  FIG. 1  is a side view of the outgassing pad  100 .  FIG. 1  is generic with respect to its application of an outgassing pad with a shell and an outgassing pad without a shell and, thus, is generically depicted using reference character  100 . Specific section views of an outgassing pad with a shell and an outgassing pad without a shell are depicted by reference characters  100 A &amp;  100 B in  FIGS. 1A &amp; 2B , respectively. As such,  FIG. 2A  is the section view of the outgassing pad with shell along cut plane  2 A- 2 A in  FIG. 1 .  FIG. 2B  is the section view of an outgassing pad without a shell along cut plane  2 B- 2 B in  FIG. 1 .  FIGS. 3A &amp; 3B  show the outgassing pad  100  from nose end and tail end perspective views, respectively. 
       FIG. 4  is a close-up partial section view of a charging well for cook-off mitigation, as depicted by reference character  400 .  FIG. 8  is an inverted isometric view of some components and their associated structural features in the charging well  400 . The charging well for cook-off mitigation  400  is sometimes referred to simply as a charging well and other similar variations, without detracting from the merits or generalities of the embodiments.  FIG. 5  illustrates a cook-off mitigation system  500  in a generic munition  502 .  FIG. 6  is an exploded view of a eutectic device  600  that can be used in some embodiments.  FIG. 7  is an exploded view of a gas sealing system  700  that may be used in some embodiments. 
     Referring to  FIG. 2A , the outgassing pad with a shell (reference characters  100 A and  102 ) houses an outgassing agent  104 . Referring to  FIGS. 1 &amp; 5 , a generic munition is depicted with reference character  502  having a munition casing  504  with an interior wall  506 . The munition  502  has a nose end  503  and a tail end  505 . The interior wall  506  defines an interior compartment that is configured to house an explosive fill  508 . The outgassing pad  100  is positioned inside the interior compartment  506  and adjacent to the interior nose end  510  of the munition  502 . 
     Outgassing pad  100  positioning and, therefore, the shell  102 , such as in the embodiment depicted in  FIG. 2A  by reference character  100 A, is notable because previous attempts at using an outgassing pad were, if employed at all, positioned in an aft vent and not in the nose end. Similarly, the embodiment depicted in  FIG. 2B  by reference character  100 B is also notable for the same reason. Furthermore, previous attempts at using outgassing pads, if used at all, were flat, circular discs and not shaped as disclosed herein. 
     The shell  102  has at least two sides  210 A &amp;  212 A, synonymous with the first and second portions mentioned above, that are diametrically-opposed to each other with one of the two sides being adjacent to the interior nose end  510  of the munition  502 . Viewing  FIGS. 2A &amp; 5  simultaneously, it is readily apparent that the side depicted by reference character  210 A is adjacent to the interior nose end  510  of the munition  502 . The other side, depicted by reference character  212 A, is adjacent to the explosive fill  508  housed in the interior compartment  506  of the munition  502 . The explosive fill  508  holds the shell  102  adjacent to the interior nose end  510 . Adhesive can be used, if desired, to adhere the shell  102  adjacent to the interior nose end  510 . 
     Similarly, the outgassing pad without a shell (reference character  100 B in  FIG. 2B ) also has at least two sides  210 B &amp;  212 B, synonymous with the first and second portions mentioned above, that are diametrically-opposed to each another with one of the two sides being adjacent to the interior nose end  510  of the munition  502 . Viewing  FIGS. 2B &amp; 5  simultaneously, it is readily apparent that the side depicted by reference character  210 B is adjacent to the interior nose end  510  of the munition  502 . The other side, depicted by reference character  212 B, is adjacent to the explosive fill  508  housed in the interior compartment  506  of the munition  502 . The explosive fill  508  holds the outgassing pad without a shell (reference character  100 B) adjacent to the interior nose end  510 . Adhesive can be used, if desired, to adhere the outgassing pad without a shell (reference character  100 B) adjacent to the interior nose end  510 . Additionally, the outgassing pad without a shell (reference character  100 B) can be adhered to the interior wall  506  of the munition by selecting a binding agent such as, for example, asphaltic hot mix or Epolene wax, which allows for the application of the outgassing agent and binder to be applied directly to the interior wall of the munition  502  as a liner. 
     Referring to  FIG. 4 , the components in the charging well  400  are shown assembled. The charging well  400  includes a charging well cavity  402  that is a void that penetrates the munition casing  504 . The charging well cavity  402  has a proximal end  404 , a distal end  406 , and threaded surface, sometimes referred to as a threaded interior surface (not shown for ease of viewing). A counterbore  403 , sometimes referred to as a spot face, transitions to the proximal end  404  of the cavity  402  and is configured as shown to create a smooth, flat surface to assist with mating. 
     Referring to both  FIGS. 4 &amp; 8 , the charging well component  408  has a threaded exterior surface  802 . The charging well component  408  is attached inside the charging well cavity  402  by threading engagement of the charging well component&#39;s threaded exterior surface  802  to the threaded interior surface of the charging well cavity. Stated another way, the threaded exterior surface  802  can be referred to as mating threads that attach the charging well component  408  to the munition casing  504 , i.e. inside the charging well cavity  402 . Both the charging well cavity  402  and charging well component  408  have appropriate thread relief features. 
     Referring to  FIGS. 4 &amp; 5 , the munition casing  504  has a nose end  503  and a tail end  505 . The charging well component  408  is electrically connected, sometimes referred to as in electrical communication with, a munition fuze  513  via the conduit  518 , which can be referred to as a communication conduit and/or power cable conduit. The munition fuze  513  is housed in a fuze well  511  at the tail end  505 . A eutectic charge tube extension  413  has a first end  416  and a second end  418 . The first end  416  of the eutectic charge tube extension  413  is configured for mating engagement with the charging well component  408 . The second end  418  is configured for mating engagement with the communication conduit  518  (the opposing end of the communication conduit—opposite from the end connected to the fuze well  511 /fuze  513 . 
     An explosive fill  508  is generically shown in  FIG. 5  and is housed in the munition casing  504 . The munition casing  504  is steel and has an interior protective liner  411  separating the munition casing and the charging well  400  and, hence, the charging well cavity  402  and charging well component  408  from the explosive fill  508 . 
     The cutter/cutting device  415  is positioned adjacent to the eutectic charge tube extension  413  and is attached to the charging well component  408  by fasteners  414 . Other attachment methods can be used including adhesives. The eutectic melt temperature of the eutectic charging tube extension  413  is less than the outgassing temperature of the outgassing agent. The cutter/cutting device  415  is held in a fixed position and is configured to cut the cable(s) inside the conduit  518  and eutectic charge tube extension  413  after the eutectic charge tube extension has melted during a cook-off event. This prevents the cable(s), conduit  518 , and any portion of the eutectic charging tube extension  413  remaining to move toward the tail end  505 . 
     Void spaces  420 A &amp;  420 B are shown in  FIG. 4 . The void spaces  420 A &amp;  420 B are shown for attachment with communication plugs (not shown for ease of viewing) to transfer power or information via the void spaces through the eutectic charging tube extension  413 , communication conduit  518 , and finally to the munition fuze  513 . Thus, the charging well component  408  is a communication interface between communication plug(s) and the fuze  513 . A cutter device void space  422  exposes the cutting device  415  internally in the charging well component  408  for efficient cutting. 
       FIGS. 5 &amp; 5A  depict another embodiment. A cook-off mitigation system  500  in a generic munition  502  is shown. In particular, the system  500  includes the outgassing pad  100 , the charging well  400  and associated components discussed previously. The charging well  400  and associated components are electrically-connected to the fuze well  511  to provide power to a munition fuze  513  that is housed in the fuze well, and shown generically for ease of viewing. As depicted in  FIG. 5 , the charging well  400  is located (positioned) at about the midpoint (middle) of the munition  502 , which is about half way between the nose end  503  and tail end  505 . As discussed above, mating threads attach the charging well  400  and associated components to the munition casing  504 . A releasable tail closure mechanism  512  (depicted in  FIG. 5A ) is attached to the tail end  505  of the munition casing  504  and is configured to house an explosive fill  508  in the interior compartment  506 . 
       FIG. 5A  is a partial cutaway section view of the tail end  505  of the system  500  in  FIG. 5 . The releasable tail closure mechanism  512  has a base plug  514  that is concentric about the fuze well  511  and is attached to the munition casing  504 . The base plug  514  is steel or steel alloy. A thermally-releasable base plate  516  is concentric about the fuze well  511  and fits on the outer periphery of the base plug  514  and is attached to the base plug and the munition casing  504 . As shown in  FIG. 5A , the releasable tail closure mechanism  512  includes both the base plug  514  and the thermally-releasable base plate  516 . In some embodiments, the thermally-releasable base plate  516  is a eutectic device. However, the method the base plate  516  uses to release does not have to be only eutectic as long as it releases prior to the outgassing of the material. Thus, alternative materials include a shape memory alloy or a polymeric material. Components depicted are dimensioned to be close-fitting and to maintain structural integrity both during storage and while in use. 
       FIG. 6  illustrates a eutectic device, generically depicted with reference character  600 , which can be used in some embodiments, including the thermally-releasable base plate  516  shown in  FIG. 5A . The eutectic feature in  FIG. 6  is based on U.S. Air Force venting configurations. The eutectic device  600  is shown in an exploded view and is representative of the eutectic device  516  shown in  FIG. 5A , respectively. The eutectic device  600  includes a hub ring  602  having a proximal side  604  and a distal side  606 . The distal side  606  has a plurality of threaded recesses  608 . Suitable materials for the hub ring  602  include steel and steel alloys. A eutectic ring  610  has an inner surface  612 , an outer surface  614 , and a rib  616  on its outer surface. The inner surface  612  of the eutectic ring  610  is concentric about the hub ring  602 . Suitable materials for the eutectic ring  610  include metal alloys having about 58 percent bismuth (Bi) and about 42 percent tin (Sn). The eutectic ring  610  composition is tuned to a desired aft closure release temperature. Adjusting the percentages may change the melt temperature, which may allow for tuning of the desired release. Thus, in some embodiments, the bismuth (Bi) composition may be about 50 to 60 percent and the tin (Sn) composition is about 40 to 50 percent, depending on the desired release temperature. 
     A spring ring  618  is concentric about the eutectic ring  610 . The spring ring  618  has a slot  620  that is dimensioned to engage the rib  616  on the eutectic ring  610 . Suitable materials for the spring ring  618  include steel and spring back steel. The rib  616  and slot  620  engagement prevents axial movement of the spring ring  618  about the eutectic ring  610 . A retainer ring  622  has a plurality of apertures  624  that are thru-holes in the retainer ring. Suitable materials for the retainer ring  622  include steel. When assembled, the retainer ring  622  is abutted against the hub ring  602 , the eutectic ring  610 , and the spring ring  618 . A plurality of screws  626  fasten the retainer ring  622 , the spring ring  618 , the eutectic ring  610 , and the hub ring  602  together by being inserted through the plurality of apertures  624 , through the retainer ring  622 , and into the plurality of threaded recesses  608  on the distal side  606  of the hub ring  602 . The screws  626  can be steel or steel alloy cap screws. 
       FIG. 7  depicts a gas sealing device  700 , sometimes referred to as a sealing device or mechanism. The sealing device  700  is co-extensive with a portion of the protective liner  411 . The sealing device  700  has a steel O-ring holder  701  configured to hold an O-ring  702 . Rubber is an appropriate material. More accurately, a high temperature rubber material is selected, such as silicone or a fluoropolymer elastomer rubber. The O-ring holder  702  may be positioned at the forward end of the full internal diameter of the munition casing  504 . 
     Theory of Operation 
     Outgassing pad  100  positioning in the interior nose end  510  in conjunction with the defined geometry, described herein, aids in containing decomposition products to more effectively control the expulsion of explosive billet  508  out of the munition  502  after the release of the tail closure mechanism  512  and charging tube extension  413 . Less outgassing agent  104  can be used and provides for a more focused outgassing environment. Outgassing agent  104  quantity can change due to the quantity of gases needed to expel the explosive billet  508 . Positioning the outgassing pad  100  in the nose end  503  of the munition  502  reduces the risk of shock initiation of the explosive fill  508  in hard target penetration munitions. 
     The outgassing pad  100  location, geometry, and outgassing agent  104  selection is based on the anticipated gaseous products and reaction temperature for a specific munition. Employing an elastomeric shell  102  allows contained expansion and uniform pressure upon the explosive billet  508  until the elastomeric shell ruptures. Decomposition of the outgassing agent  104  occurs prior to reaction of the explosive fill (at a temperature range of about 280 degrees F. to about 320 degrees F. for some explosive fills and about 280 degrees F. to 350 degrees F. for other explosive fills). 
     The selected shape of the outgassing pad  100  is such that it expands as a wedge and obturates the explosive fill  508 . One having ordinary skill in the art will recognize that obturate is a term for sealing by expanding. Thus, the outgassing pad  100  expands as a wedge and further expands the portion of the explosive billet  508  at the interior nose end  510  against the interior wall  506 , further sealing the expanding gas at rupture. Silicone is used for the elastomeric shell  102  to allow for contained expansion at elevated temperatures and uniform pressure upon the explosive billet  508  until the elastomeric shell ruptures. 
     To avoid possible detrimental fragmentation effects to the nose end  503  of the munition  502 , the outgassing pad  100  and, especially the elastomeric shell  102 , can also contain fragmentation control patterns to contour the explosive charge and influence preferential fragmentation. With the internal pressure created by the outgassing agent  104 , the explosive billet  508  can be expelled from the munition  502  using the releasable tail closure mechanism  512  prior to ignition of the explosive billet. Thermal release of the eutectic devices occurs at a range of about 280 degrees F. to about 320 degrees F. This allows the explosive billet  508  to burn totally unconfined, thus producing a passing reaction by reducing the severity of the munition reaction to standardized IM cook-off testing, often referred to as slow cook-off (SCO) and fast cook-off (FCO). The cook-off temperatures are greater than the munition&#39;s operational temperatures. One skilled in the art will recognize that insensitive munitions testing includes identifying the system&#39;s response to standardized testing. Munitions responses are assessed depending on multiple variables and an acceptable reaction, sometimes referred to as a passing reaction or passing test. 
     The charging well  400  is configured to remain functional at operational temperatures but weaken at cook-off temperatures, allowing for the unimpeded expulsion of the explosive billet  508 . The eutectic charge tube extension  413  is a eutectic material, that maintains structural integrity of the eutectic charge tube extension during operation through munition  502  impact, but will soften and/or melt before the outgassing pad  100  outgasses. The eutectic charge tube extension  413  in one embodiment is bismuth, tin, and indium. In other embodiments, the charge tube extension  413  does not have to be eutectic provided that it softens at a high temperature, such as a polymer. The cutting device  415  will cut the eutectic charge tube extension  413  (if needed) and cables (not shown) in the conduit  518  as the explosive billet  508  is pushed toward the tail end  505  of the munition case  504  when the outgassing pad  100  outgases. Additionally, the entire charging well cavity  402  and component  408  is outside of the explosive billet  508 , as shown in  FIG. 4 . Thus, lateral movement of the explosive billet is not to be limited by the charging well  400 , communication conduit  518 , or eutectic charging tube extension  413 . Once the eutectic charge tube extension  413  is thermally released or severed, the conduit  518  is concurrently released, while the explosive billet  508  is moving laterally from the nose end  503  through the tail end  505 , as the thermally-releasable base plate  516  releases. 
     In an embodiment employing an unconfined/uncanistered outgassing pad  100 B, as depicted in  FIG. 2B , the outgassing pad is in direct contact with the explosive billet  508 . The outgassing pad  100 B is selected to be chemically compatible with the explosive billet  508 . As with the embodiment employing a shell  102 , the unconfined/uncanistered outgassing pad  100 B generates gas. The generated gas is applied to the explosive billet  508  and the release process described above occurs and the explosive billet is expelled. 
     The sealing device  700  can be used to reduce leakage of gas and to push the explosive billet  508 . A steel ring holder  701  with O-Ring  702  pushed all the way to the forward transition between the full inside diameter and ogive of the munition case  504  before the protective liner  411  is applied. The location of the sealing device  700  is at the transition of the interior wall  506  from being straight (having a constant internal diameter) to the portion of the interior wall having a tapered internal diameter due to the ogive shape of the munition  502 . The sealing device  700  is as an extra safety measure in case the outgassing pad  100  does not expand as a wedge. In those instances, the sealing device  700  will obturate and influence the explosive billet  508  to move to the tail end  505  during cookoff events. 
     While the embodiments have been described, disclosed, illustrated and shown in various terms of certain embodiments or modifications which it has presumed in practice, the scope of the embodiments is not intended to be, nor should it be deemed to be, limited thereby and such other modifications or embodiments as may be suggested by the teachings herein are particularly reserved especially as they fall within the breadth and scope of the claims here appended.