Nuclear reactor with passive means of adjusting the pH of post accident water
AssigneeWestinghouse Electric Corp.
InventorTerry L. Schulz
Life of this patent
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Abstract
A nuclear reactor has a passive system for adjusting the pH of post accident water in the containment vessel. A basic liquid is stored in the containment vessel at an elevation above the maximum post accident water level. When radiation levels in the containment vessel exceed a predetermined, normal level the basic liquid is gravitationally drained into sumps located in the containment vessel below the maximum post accident water level where it mixes with emergency core cooling system water, raising the pH of the water to about 7.
Claims19
A nuclear reactor, comprising a containment vessel that may be flooded to a maximum post accident water level, a reactor core contained within the containment vessel and means for adjusting the pH of post accident water in the containment vessel, characterized in that the means for adjusting the pH comprises:
- a tank for containing a basic substance located at an elevation above the maximum post accident water level;
- means for providing a first signal indicative of a radiation level within the containment vessel greater than a predetermined radiation level;
- and
- valve means in fluid communication with the tank for allowing the basic substance to drain by gravity into the the containment vessel in response to the first signal.
A nuclear reactor, comprising a containment vessel that may be flooded to a maximum post accident water level, a reactor core contained within the containment vessel, first and second ECCS sumps within the containment vessel, and means for adjusting the pH of post accident water in the containment vessel;
- characterized in that the means for adjusting the pH comprises:
- (a) a tank being capable of containing sufficient liquid NaOH to adjust the pH of post accident water in the containment vessel to about 7 and located at an elevation above the maximum post accident water level;
- (b) first and second pH sumps together being capable of holding the contents of the tank located proximate the ECCS sumps;
- (c) sensor means for providing a trigger signal, characterized by:
- (i) a plurality of spaced apart radiation sensors in the containment vessel, each radiation sensor being capable of providing a radiation signal indicative of a radiation level at the sensor;
- and
- (ii) logic means for providing a trigger signal in response to receiving radiation signals indicative of radiation levels in excess of predetermined radiation levels from at least two of the radiation sensors;
- (d) first and second drain lines extending downward from and in fluid communication with a lower end of the tank;
- (e) first and second squib valves connected to the first and second drain lines respectively and responsive to the trigger signal;
- (f) third and fourth drain lines extending downward from the first and second squib valves respectively;
- (g) means for routing the contents of the tank to the first and second pH sumps in about equal proportions.
A method of adjusting the pH of post accident water in a nuclear reactor, the nuclear reactor being characterized by a containment vessel that is capable of being flooded to a maximum post accident water level and a reactor core located within the containment vessel at an elevation below the maximum post accident water level, comprising the steps of:
- storing a basic liquid in the containment vessel at an elevation above the maximum post accident water level;
- monitoring the radiation level within the containment vessel;
- and
- draining the basic liquid by gravity to a location in the containment vessel below the maximum post accident water level when the monitored radiation level exceeds a predetermined radiation level.
Dependencies are inferred from the claim text.