Gaseous Radwaste Flashcards
Total release rate is limited to…
50 scfm. Normal discharge rate for the primary path is 45 scfm. The secondary path flows through a pressure reducer and the RU-12 monitor at 5 scfm
Radwaste building exhaust ventilation is required to run at…
> 25,000 scfm to ensure adequate H2 dilution.
The purpose of the Gaseous Radwaste system is…
Collects and processes potentially radioactive gases generated within the plant so that exposure of onsite and offsite personnel is kept within acceptable limits.
Stores waste gasses in an oxygen free environment to allow for radioactive decay (short lived isotopes) and subsequent release.
The GRS has been sized to provide the capability of holding radioactive gas for a 45 day decay period.
Describe the Gas Surge Header Containment Isolation Valves GR-UV-1 and GR-UV-2.
GR-UV-1 is a motor operated valve and is located inside containment. GR-UV-2 is a solenoid operated valve and is located outside containment. Both valves will close upon receipt of a containment isolation actuation signal (CIAS).
Override capability is provided.
Describe the Decay Tank Disch Header Isolation Valves (GRN-UV-34A, 34B) and control handswitches.
HS-34A is located in the radwaste control room and can be used to open and close both UV-34A and UV-34B. HS-34B is located in the main control room on B07 and provides the open permissive signal and the ability to close UV-34A and UV-34B.
These valves fail closed upon a loss of air.
The gaseous discharge isolation valves (GRN-UV-34A, 34B) will automatically close on:
high discharge flowrate (sensed on FIT-33)
low radwaste building exhaust flow (sensed by PDSH 40/41)
high radiation level in the discharge line (sensed by RU-12)
Waste gas discharge pressure Hi (sensed by PSH-32)
Gas Compressors (GRN-C01A, C01B) will trip on any of the following conditions:
high-high O2 concentration
discharge pressure high
Describe the High O2 Alarm, High-High Oxygen condition and actions that occur.
High oxygen (2%) alarm
A high-high oxygen condition (3.75%) in the WGST or the surge header will result in the following:
After a 5 minute time delay, nitrogen dilution valve AV-169 automatically opens to purge the tank and clear the alarm.
Trips and locks-out both waste gas compressors. When the alarm clears, it will be necessary to reset the compressors manually by taking handswitches HS-15 and HS-16 to “stop” simultaneously; return to “auto” position, as necessary, for continued operation.
IF a high-high oxygen alarm and subsequent auto dilution occurs, then the dilution should be stopped as soon as possible after the WGST reaches 25 psig.
Describe the Control Room alarm RADWASTE SUMP/PANEL TRBL.
The Control Room Alarm comes in after the Alarm in the RW Control Room has been in for 5 minutes. All Radwaste Systems Alarm to the Radwaste Control Room. (GR,LR,and SR)
