Marla Cervantes wrote:

Marla Cervantes wrote: Marla Cervantes wrote: Wednesday, January 29 2020, 05:55   A P2N container  with heat shields, and with a UO2/C loaded graphite container was installed in the EVAP1 Chamber is currently being evacuated. Thursday, January 30, 2020, 08:56 Pressure limits: Good vacuum 1e-1 Torr Bad vacuum 5e-1 Torr Initial pressure:  IGP1=1.52e-6Torr Current ramp set to 1A/min to 10 A, voltage is stable. Current ramp increased to 1A/10s to 100 A. The pressure started raising around 80 A. Current was kept 5min at at 100 A, voltage was stable Thursday, January 30, 2020, 09:32  Current ramp set to 1A/20s to 150 A (same pressure limits) Pressure keep increasing during heating Thursday, January 30, 2020, 09:53  Current was kept at 150 min during 5 min, the voltage is stable, pressure started to stabilize: IGP1 = 0.027 Torr TGHT = 0.418 V Ramp set to 1A/min to 200 A. Thursday, January 30, 2020, 10:02 Pressure decreasing: TGHT= 153 A   Thursday, January 30, 2020, 10:15 At 155 A while pressure decreasing, the power supply tripped off, Controls has been notified, waiting for instructions.    Thursday, January 30, 2020, 11:51 Controls respond "It looks like the power supplies were tripped by either the pirani gauge (IEVAP:IGP1) or the Nuclear vent or by both. But, it did not look like that the interlock tree latched the bad condition when the power supplies tripped. I modified the PLC to properly latch the cause of the trip." and gave green light to restart the carbothermal reduction.

 Thursday, January 30, 2020, 13:09

IGP1=5.9e-6Torr

Ramp set to 1A/10s to 200 A

Pressure rising too fast at 200 A, current reduced manually to 190 A

Pressure start dropping and system tripped, notify to controls again, "The strip tool shows the vacuum level shoot down to 0 then shoot back up for a quick second but that is enough to tell the PLC that IGP is “bad”"

Thursday, January 30, 2020, 15:58 

Restarting process to try to trip the system on purpose 

Initial pressure IGP1 = 2.7e-6Torr

Ramp set to 1/A/10s to 200 A, 0.59 V

Ramp set to 2A/10s to 300 A

Max pressure during process IGP1 = 0.03 Torr

Voltage increased and stabilized (see voltage rising).

Ramp kept at 2A/10s to 400 A

Thursday, January 30, 2020, 16:48 

TGHT = 1.54 V, 399.744 A

IGP1 = 0.00016 Torr and going down

Ramp set to 2A/10s to 500 A

Thursday, January 30, 2020, 17:02 

TGHT= 1.9V, 499.2 A

IGP1 = 0.00014 Torr

Ramp set to 2A/10s to 600 A

Ramp set to 0.5 A/min to 700 A, ramp stopped at 680 A

Manually tapped to 697 A

Pressure dropping indicated that carbothermal reduction is done.

Unfortunately, the system did not trip. 

Contact Gelo for the  next run, such that he can monitor the system and we can spot the problem.