DRAWINGS UPLOADED IN PDF, DOWNLOAD TO VIEW ALL DRAWINGS, PREVI
---------------------------------------------
Jan 27:
T1-MK1 was moved to the storage pit in position #4. M9BB was moved to the hot cell for shutdown maintenance (o-ring replacement, air cylinder servicing, etc.).
When M9BB work is done, it will be returned to the target station and replaced with T2-MK1 for servicing (target exchange, measurement target installation, etc.).
---------------------------------------------
Jan 29:
Maintenance operations on the M9BB were completed on the hot cell.
- The air cylinders actuated and lowered smoothly, and at 42 psi as indicated in the instructions document.
- The felt wiper on the shaft seal was replaced.
- 3 o-rings were replaced on the bronze shaft seal bracket and lubricated with vacuum grease
- upper limit switch actuation was confirmed after reassembly
- BB returned to the adapter plate on the turntable and reoriented for pickup
---------------------------------------------
Feb 03:
M9BB returned to target station:
- o-ring groove on monolith cleaned,
- replacement o-ring with vacuum grease placed
- during return, we noticed pieces of 'scrap metal' on the bottom of the beamblocker, it was removed and when scanned registered a count that exceeded the radiation cave monitor's dial, this will be stored/disposed as active waste.
- M9 ASU still disconnected, could not 'push-down' M9BB with gas line connected, gas line left disconnected for now.
- T handle plate removed, limit switch rod returned
T2-MK1 moved from target station to hot cell roof, north hook used for flask, south hook used to adjust the position of the alignment frame:
- section of hot cell roof railing had to be removed for the flask to clear when handled by the north hook, there is also a similar functioning cutout on the wall by the storage pits
- peak fields are 1100 uSv/hr at the hot cell opening by the target.
T2-MK1 servicing started on hot cell roof:
- T2-MK1 water flush completed, ~1 min air purge cycles completed for all target positions, left at position 5 (plugged) for longer term air purging (~3 hours).
- A broken ceramic cap was found on the top of the target vacuum flange.
- 4 quarter circle segments from what looks like the old-style graphite targets were found on the base of the target ladder.
- The coupling between the potentiometer gearbox and the ladder drive screw has a rubber section, we will have to inspect it and decide whether to replace it with a metal coupling during this shutdown, if so, we should also replace the plastic ferrules and update the bulkhead plate to be more servicable.
---------------------------------------------
Feb 05:
T2 station was surveyed, peak fields were found by the blanked off T2 opening: 4mSv/hr. Immediately at the cover fields were around 16 mSv/hr.
No fallen pieces of suspected graphite target segments were found on the monolith, it may be a good idea to check inside the monolith hole with a remote viewing camera to make sure nothing is obstructing the locating feature on the base of the target ladder (to be included in the T2 return work permit).
---------------------------------------------
Feb 10:
The T2-MK1 target ladder underwent a water rinse and several days of air purging.
5 psi compressed air was run through each target position (including position 5 which is plugged) for several hours each. Then, the ladder was fully dried using the leak detector and cold trap on Feb 07.
The leak detector was calibrated with Vacuum Group's external source to 8.7e-8 mbar-L/s prior to operation. The leak detector and vacuum line up to the target service panel connections were checked to be leak tight prior to testing (0 leak rate and <1e-3 Torr pressure).
A single pump-down cycle was sufficient to get vacuum to establish within reasonable time:
- Total pump-down duration was ~55 minutes
- 60 seconds to go into 'fine vacuum' mode.
- 2 min 13 seconds to get to ~1e-3 Torr vacuum in ladder
- leak rate was initially ~1e-8 Torr-L/s and slowly dropped to 0.0e-10 Torr-L/s over the course of the pumpdown (48 minutes to bottom out)
- the ladder was left at the bottomed out leak rate for around 5 minutes prior to venting.
- approximately a 1cm thick, 10cm diameger puck of ice formed on the side of the LN2 vessel of the cold trap.
Upon closer inspection with Isaac Earle, the following were observed for graphite pieces on the T2-MK1 target ladder base:
- The surface finish on the chips strongly suggest that they are graphite target materials
- Curiously the graphite chips are all of different thicknesses, to our understanding, the graphite material used in the old targets are of consistent thickness.
- The rounded faces of the chips had no clear sign/evidence of brazing when compared to sample pieces that can be found in the Hot Cell Lab office.
- No clear signs of beam spots can be found on the flat faces of the chips, near the corner edge.
- No clear signs of brazing on the targets were observed.
The above observations suggest that the chips did not originate from an operational target that has seen beam.
---------------------------------------------
Mar 21:
The T2-MK1 target ladder was leak tested with 3psi x 0.5s doses of He.
The baseline initial leak rate of the ladder was ~1e-8 Torr-L/s but reached around 1e-10 Torr-L/s when allowed to pump down over ~1 hour. Fine test was reached after 30s of pumping down (with cold trap), ladder pressure was stable at ~1e-3 Torr throughout.
See attached image for detected leak rates, overall all joints performed well, with the highest leak rate of 4.2e-9 Torr-L/s registered by one of the joints on ladder position 1.
---------------------------------------------
April 02:
The T2-MK2 target ladder was moved to the target station from storage pit #3.
During the return procedure, from visual inspection of the target tube, there doesn't seem to be any dropped material in base of the tube.
We encountered some difficulty seating the o-ring on the monolith flange's groove because the o-ring was stored in a coil. Extra vacuum grease was used to keep the o-ring stuck flush in the groove.
When lowering the ladder onto the monolith flange, the chain hoist bottomed out just short and we had to lower the flask with the crane for the target ladder to make contact. Edi from vacuum group helped us pump down on the vacuum volume and at first glance it seems to be pumping down ok.
We will return in the coming days to re-do the service connections to the target ladder and do a final check of the system.
---------------------------------------------
April 03:
The plug in pos#5 and the 5cm target (SER# 301) in pos#3 on the T2-MK1 target ladder were removed in the hot cell and bagged and moved to the East hot cell.
The loose graphite material on the base of T2-MK1 was also bagged and labelled and moved to the East cell.
The measurement target bracket TRH1766 was installed in position 5 and a 5cm target cassette (SER # 308) was installed in position 3.
The target bracket was cleaned in an ultrasonic cleaner with simple green, then tap water before being dried. The tube screws were switched with DIY vented screws.
The pos 3 and 5 male Swagelok threads and conical sealing face were 'cleaned' with the conical scotch-brite tools (cone and cup) with the air ratchet and blown out with a compressed air can.
The Swagelok nuts on the new target cassette and bracket was first tightened till the Swagelok gap inspection gauge could not fit in the gap.
The ladder was then leak checked and initially only pumped down to 3e-3 Torr with 2.5e-8 T-L/s leak rate. After some tightening of the Swagelok nuts on pos 3 and pos 5, the pressure and baseline leak rate eventually bottomed out to 1e-3 Torr and 0.0e-10 T-L/s respectively.
With 3psi x 0.5s He, the highest leak rates were found in position 2b, 3b, and 5a, all being less than 3e-9 Torr-L/s.
Of note, there is a 'ding' on the 'right' side bellows (as viewed from hot cell widow with target ladder rotated closer toward the window), the highest leak rate was found when we sprayed He directly at this 'ding'.
---------------------------------------------
April 03 (Continued):
We moved the T2 flask alignment frame off from the T2 station, re-connected all target services to T2-MK2 and re-connected the compressed air line to the T2/M9 blocker.
The T2-MK2 profile monitor drives in/out properly without timing out.
The target ladder drives up and down smoothly between pos 0-3.
We tuned the demin flowrate to 1.1-1.2 gpm for the T2 target in position 3 (5cm Be), and for the T1 target in position 1 (12mm Be, actually done end of Mar).
After some time allowing the pump to flow, all process variables in the cooling package reached operational ('green') levels.
As normal though, the T2 target flowrate was relatively low and close to the lower warn limit of 3gpm. We should look into upgrading the pump on this cooling package or adjust the warn/trip limits according to some Engineering analysis.
---------------------------------------------
April 09:
- We attempted to open the needle valve on the T1 heat exchange further but it was already fully open. Flow through the heat exchange is still fluctuating around 6.3 GPM, occasionally dipping below 6 GPM. It may be possible that the heat exchange paddle wheel needs to be changed for the flow rate to increase again.
---------------------------------------------
April 11:
- After re-inspecing the supply and return lines for the T1 heat exchanger in the BL1A tunnels, no metering/flow adjusting valve was found (also true for the T2 line). The flow through the T1 heat exchange will have to hover around the 6gpm mark (flow changed likely because other upstream systems are receiving flow).
- The flow through the T2 target (12mm Be) hovers around 3GPM, for both position 3 and 5 so we will have to deal with it hovering around the warn limit for the coming operational period (pending thermal analysis to justify changes to the warn limit)
- The M9/T2 and M20 blocker movement was tested and confirmed.
- The profile monitor movement for both the T1 and T2 target ladders were confirmed.
- We also tested a method of powering off the cooling pump by disconnecting the PLC signal/control cable to the 480V power box on the mezzanine.After disconnecting the signal cable, the T2 pump successfully turns off and upon reconnecting, the control room successfully regains control over the pump.
---------------------------------------------
Jun 25:
- T2-MK1 target elevations was measured from Jun 20-24.
- The target flange was levelled to within 0.2 degrees during the measurements.
- Generally, the target centres line up with past measurements from 2020.
- The new completed form can be found here.
- The measurement jig centres was also measured (see hand written note).
- During measuring there was a brief instance where the profile monitor made contact with the target in position 1, we were able to verify that the profile monitor centre did not change (measurement immediately before and after stayed the same).
- We will re-verify that the electrical system of the profile monitor and that the vacuum of the target ladder is not compromised.
|