What Is Heap Spraying?

According to the core melting process, severe accidents in pressurized water reactor nuclear power plants can be divided into two categories: high pressure fusion reactors and low pressure fusion reactors. In the high pressure melter accident, the primary circuit system of the reactor is under a continuous high pressure state. When the lower head of the pressure vessel melts through, the melt may be sprayed from the lower head of the pressure vessel to the reactor cavity and a high pressure melter spray may occur.

According to the core melting process, severe accidents in pressurized water reactor nuclear power plants can be divided into two categories: high pressure fusion reactors and low pressure fusion reactors. In the high pressure melter accident, the primary circuit system of the reactor is under a continuous high pressure state. When the lower head of the pressure vessel melts through, the melt may be sprayed from the lower head of the pressure vessel to the reactor cavity and a high pressure melter spray may occur.

Chinese name

High-pressure melt-blow

Foreign name

Thehigh-pressure core melt injection

Aftermath of the accident

High-pressure meltdown accidents are often preceded by insufficient core cooling (such as the loss of a secondary heat sink and a small breach in the primary circuit), covering most serious accident sequences. Saturated water, steam, and hydrogen that are subsequently discharged may push and carry core debris away from the reactor cavity and reach other areas of the containment. The diffused high-temperature core debris may directly and rapidly carry thermal and chemical energy (fragment oxidation). Geothermally heating the atmosphere inside the containment, even destroying the integrity of the containment, results in very serious radioactive release consequences, "direct containment heating" occurs, and may cause early failure of the containment. Therefore, it is necessary to take corresponding primary circuit pressure relief measures.