Technical Meeting: Non-Destructive Testing of Munitions

After the Defects – Causes, Classification and Criticality Workshop, several themes, problems, and opportunities were raised and documented in a series of limited technical reports, L-271, L-272, L-273 and L-274. Subsequently several points, phrased as questions, have been proposed for further discussion in the NDT Technical Meeting.

The agenda for the meeting will be determined on the basis of a survey that is now active below. Please review the following information and then, at the end, click the link to go to the survey page.

Best Practices in the Detection of Defects

• Are there general rules or guidance available for technique development?  This may be divided for different items: fuze, missile, shell.
• What guidance is there for challenging situations, such as the two examples of O-rings in rocket motors and base gaps in artillery shells that were provided?
• Are there general rules to guide CT employment versus 2D X-ray imaging?  In any discussion, there should be a recognition of the different manufacturing contexts of a relatively few high value items, (missiles) and a large number of lower value items (artillery shells).
• Are there general rules for the most economic use of CT imaging or how to establish priorities for work?  In discussion, there should be a recognition of the nature of the information sought, for example, qualitative, binary (yes/no), quantitative, and the criticality of the information.
• Are there best practices available for this quantity of data, security, how it is stored, and how it is retrieved?
• Are there best practice guidelines for the protection of data, identification, and association of images to the original data? Outside of obvious legal or proprietary concerns, are there guidelines for separating the image from the originating data?
• Any general guidelines for determining / tracking the radiation exposure of an item in case of a long exposure or repeated exposures?

Emerging Technology in NDT

• What material conditions would make a thermal conductivity test feasible? This discussion would include extent of change in thermal conductivity and thickness of material, along with configuration with respect to a liner or outer case.  What would be a good example for testing this method?
• What material conditions would make an ultrasonic test feasible?  This discussion would consider both the case of the material microstructure and the continuity with a liner and outer case.  Would such a test be a candidate for screening artillery shells for base gaps?

Limitations & Capability Gaps in NDT

• What situations are the most challenging to image within the realm of X-ray imaging / XCT?  Two examples provided during the presentations are O-rings in rocket motors and base gaps in artillery shells. Are there any others?
• What techniques could be developed to provide different and useful information?  A discussion of the information could be drawn across scale, for example, material, component, and system. Output could be coordinated investigations of different techniques.
• What capabilities does artificial intelligence / machine learning offer for the detection of defects?

Calibration & Standards in NDT

• Would a series of seeded defects in fuzes or initiating devices be useful as standardization items?
• Would an artillery shell with a base gap be useful?  Or a device that contains defects of the same nature, that is, size, shape, orientation, and very similar detection challenge?
• Subsequently, would there be an interest in conducting a round robin test on either of the two items above?
• What standards are available for metrology and resolution that would be applicable to munition systems?

Standardisation of Acceptance Criteria

• What (numerical) acceptance criteria are in use internationally for accidental munition reactions caused by defects (e.g. the commonly quoted “one in a million”)? What are these criteria based on (e.g. requirements of national legislation)? Is standardisation achievable, or are acceptance criteria too dependent on e.g. national risk tolerability criteria, specific environmental conditions? (NB this is also related to the treatment of risk, as per the next section.)
• How are national defect acceptance specifications developed for different types of munitions / energetic materials / manufacturing techniques / loading processes? For example, are they empirically determined; determined through physical models; based on the limitations of the production process; based on the limitations of inspection processes; etc.? Could comparison of these specifications and / or development processes between nations assist understanding of defect criticality? (NB: this is also related to the treatment of risk, as per the next section.)
• Could international sharing of information from defect-related accidents help to improve understanding of criticality, and thus acceptance criteria? What might prevent this? How can we standardize the way in which the nations report and share information from their accidents/incidents?

Consideration of Risk and Consequence

• How can statistical tools be better utilised in the analysis of defects?
• How can reliable probability distributions be derived for the creation and detection of defects, and for related reactions? Noting the sparseness of empirical data due to the expense and difficulty of necessary testing, are there any feasible means by which data can be pooled from manufacturers and test centers?
• In developing criteria for acceptable levels of defects, what consideration is given to the limitations of the various non-destructive examination (NDE) techniques applied to munition systems (e.g. probability of detection of certain defect sizes vs the probability that defect will result in an accident)? Are acceptance criteria adjusted to account for the technological improvements in NDE techniques, which allow for the detection of defects that were previously not detectable? If so, is such an adjustment warranted?
• In attempting to understand the impact of defects and treat the associated risks, where should the most effort be expended: on those defects which occur frequently but present a small change to the risk profile, or on those defects which occur rarely yet may present a large change to the risk profile?

Please complete the survey here.

The meeting will be held on 13 May 2024, in advance of the EMTWG conference in Oslo, Norway, on 13 May 2024. The venue will be the Clarion Hotel, The Hub. Travel and accommodation information can be found on the EMTWG website. Attire is business casual.

Registration to the technical meeting will be open to all citizens of MSIAC member nations and is free. As placed are limited, the MSIAC National Focal Point Officer(s) will make the final decision on attendance for their respective nations.

Please note that the registration to EMTWG 2024 is independent of this technical meeting.

To register, please go to the registration page.