Munitions are encountered in a variety of underwater environments as unexploded ordnance (UXO) or discarded military munitions (DMM). The objective of this project was to validate an underwater suite of tools that can be used to render safe underwater UXO and DMM. Testing was conducted on inert Navy 5-inch/38- caliber projectiles in a test tank (demonstration #1) and in the ocean off a pier (demonstration #2). The suite of tools tested accomplished the following objectives:

  1. Clean an inert munition of external bio-encrustations using a high-pressure waterjet cleaning tool and three-axis underwater gantry,
  2. Position and attach a cut and capture apparatus on the target item using a three- axis underwater gantry,
  3. Cut an access hole in the side of the target item using a high-pressure entrainment style abrasive waterjet cutting head and remove the resulting steel plug with a magnetic head,
  4. Wash out the internal contents of the target item using a high-pressure washout head, and
  5. Capture the effluent generated during high-pressure cutting and washout using a continuous flush and capture tank.

Technology Description

The proprietary technology for underwater demilitarization of munitions utilized a suite of tools that accomplished the following; cleaned a munition of external bio-encrustations using a high-pressure waterjet cleaning tool, positioned a cut and capture apparatus on the munition, cut an access hole in the side of the munition using a high-pressure entrainment- style abrasive waterjet cutting head, removed the resulting plug, washed out the internal contents of the munition using a high-pressure washout head, and captured the effluent generated during operations without leakage to the environment.

Interim Results

In this project two demonstrations were conducted. During the first demonstration, 48 inert projectiles that included some covered in concrete were processed in a test tank. During this demonstration, all system functions were successfully demonstrated in a controlled environment. After this demonstration, numerous equipment upgrades were identified and implemented before executing the second demonstration.

During the second demonstration, 45 inert projectiles were processed off a pier at Naval Support Activity Panama City, Florida. The goal was to achieve a 80% reliability (success rate) of a given operation during the demonstration. Statistical analysis of the data yielded the following reliability results at 90% confidence: 89% success rate of mating to the projectile, 75% success rate in cutting the access hole, 91% success rate in removing the plug, and 80% success rate in removing the entire fill of the projectile. This analysis assumed each test was identical and independent. In reality, the cutting parameters were changed during the demonstration because initial cut tests yielded an uncut sliver of steel that prevented    the plug from being removed. After the cutting parameters were changed, successful cuts were continually achieved and yielded a reliability of 91%.

Overall, this project has shown that Gradient Technology’s high-pressure waterjet demilitarization technology can be reliably utilized underwater in a highly controlled environment where the supporting equipment is located above water.


In this project, the projectiles were positioned horizontally and were processed in that specific orientation relative to the tool. The equipment, as currently configured, is thus only capable of demilitarizing items that rest on their sides. This limitation was recognized but accepted so that the core of the technology could be validated. Additional efforts can now be focused on manipulating the tool underwater to demilitarize ordnance in varying positions.

  • High Pressure Penetration and Disposal of Munition Content,

  • Water Jet and Abrasive,

  • Dockside Tests,