Second, it is not possible to establish a causal linkage between the Cheonan’s sinking and the torpedo. The JIG’s EDS and XRD analysis data on the adhered substances obtained from the hull, a torpedo and the underwater explosion experiment do not have any linkage with an explosion.

Third, the JIG failed to demonstrate that the torpedo was manufactured by the DPRK. The fact that the inscription “1?(No.1 in English)” was perfectly preserved in the explosion is scientifically unexplainable and goes against a regular court of law.

The ROK Civ-Mil JIG’s positions regarding these assertions are:

“First, the JIG’s conclusion on the external explosion is groundless. The conditions of the salvaged hull, as well as the bodies of survivors and deceased crew members, do not indicate the signs of an external impact.”

The ROKS Cheonan was split and sunk due to shockwave and bubble effect generated by a non-contact underwater explosion  (depth 6~9m).

A non-contact underwater explosion occurred below the gas turbine room, splitting the hull from the forward and aft sections of the gas turbine room, and partially detaching the gas turbine room structures (Figure 1). The fractured surface is the forward and aft parts of the gas turbine room, and shearing fractures were observed along the area where the gas turbine room was ripped off due to the enormous external pressure exerted from the lower part, and brittle fractures were identified on the rest of the fractured surface. The gas turbine shell plates, under which a non-contact underwater explosion took place, were deformed in concave shape resembling the shape of the bubble (Figure 1). The stern bottom fractured surface, connected to the severed hull, also shows a spherical shape deformation (Figure 2).

Bottom Shell Plates of Gas Turbine Room

Deformation Of Bow Hull Bottom

A shockwave, which is produced by a non-contact underwater explosion, is spherical wave and the pressure inside is very high. However, since the shockwave dissipates swiftly in all-directions and collapses accordingly, it does not apply a significant damage on the hull. Even though the magnitude of bubble effect generated after the shock wave release is less in its pressure, and slower in its speed compared to the shock wave, the process of expansion and contraction of the gas bubble causes damage to the hull, and the hull is severed by the water jet produced from the bubble collapse. This does not deliver a fatal impact to the bodies of the crew members within the ship. The survived and deceased crew members of the ROKS Cheonan suffered fractures, lacerations, and bruises. The physical conditions correspond with what would result from bubble jet effect generated by an underwater explosion. The 8 severely wounded crew members suffered fractures on the lumber (3), rib(2), right clavicle(1), spine(1), and thighbone(1). Fractures, lacerations, and bruises were also observed from the recovered bodies of the 40 deceased crew members.

“The JIG’s EDS and XRD analysis data on the adhered substances obtained from the hull, torpedo, and underwater explosion experiment do not have any linkage with an explosion.”

Prof. Lee and Suh’s arguments are that 1) although crystallized aluminum is visible in XRD [1] data of the adhered substances from the underwater explosion experiment conducted by the JIG, it is absent in XRD data of the adhered substances obtained from the ROKS Cheonan hull and the recovered torpedo part. Therefore, the ROK Cheonan incident was not caused by a torpedo. 2) According to the furnace experiment conducted by them, both crystallized aluminum and crystallized aluminum oxide were generated by the melting and cooling of aluminum. Based upon the reasons above, they asserted that the JIG’s report, which found that mostly amorphous aluminum oxide was produced, is invalid, leading to the conclusion that the JIG’s data were fabricated.

The JIG explanation for these assertions, however, is that the crystallized aluminum was detected in XRD analysis result of the adhered substances from the underwater explosion experiment, because the presence of only a little amount of adhered substances limited XRD measurements and hence, the analysis had to be conducted while the adhered substances were still attached to the aluminum plate, which was originally placed on the water tank for the experiment.

The detection of aluminum components in the EDS [2] analysis result of the adhered substances obtained from the Cheonan hull and recovered torpedo part, coupled with the lack of such aluminum components in the XRD data (XRD confirms the crystallization of chemical compound), prove that the aluminum oxide was indeed in amorphous form.

On the contrary, the furnace experiment by Prof. Lee is only a demonstration of a change in thermodynamics. In the experiment, aluminum was heated up to 1100 degrees C for 40 minutes, followed by the cooling of the substance for 2 seconds through immersion. As a result, only parts of the surface were oxidized while the rest simply remained as crystallized aluminum.

An explosion of an explosive containing aluminum typically occurs at high temperatures of above 3,000 degrees C, at above 200,000 atmospheric pressure, and within one-thousandth to one-ten thousandth of a second. Given that aluminum undergoes rapid cooling following a rapid reaction to the oxygen components of an explosive in these extreme conditions, most of the aluminum becomes amorphous aluminum oxide.

It is clear that the data from the Prof. Lee’s experiment cannot be used to verify these results, since the furnace experiment carried out by Prof. Lee cannot produce the chemical reactions under extreme conditions such as would have occurred in the ROKS Cheonan incident.

Analysis of Adhered Substances:

Collection of the adhered substances: Bow, stern, stack, and torpedo propulsion motor (10 locations)

Underwater explosion experiment
• Condition : Size of water tank: 2m?1.5m?1.5m / seawater 4.5ton

Explosive charge : 15g (RDX, TNT, AL powder, etc.)

EDS Result: Identical explosive elements were detected: (C, O, AL)