We replaced tha O-ring on M20 at T2 and brought the target station down to vacuum, which allowed the target water pump to be turned on. 

After turning the pump on, we inspected the replaced valves for any leaks and found none - the flow on the demineralizing line was adjusted to 1.2GPM (also done at T1) by turning the needle valve.

Will observe till tomorrow to ensure that the T2 system is stable before proceeding with last system check.

 We tested the actuation of the M9/M20 beam blockers on the T2 monolith (3-4pm).

Vacuum levels remained steady throughout so the M20 o-ring replacement that was performed this shutdown was successful (see strip of 1ACG4 - vacuum gauge for T2 systems interlock).

Note: M20 was actuated by contacting the control room, while M9 (labeled T2 blocker) was actuated through the physical ASU on the ground level of the meson hall (see picture).

For future shutdown work: the air supply valve must be kept open (tab lifted up), otherwise the solenoids won't see pressurized air. 

We ran into issues because the tab on the valve broke early into the shutdown and we didn't realize that it had to stay in the open position. 

Note: The flow on the T2 demin line went up to 1.5 gpm yesterday when we were on the blocks. The needle valve was likely nudged on accident.

Update:

1) the T2 demin flow was corrected and the air supply tab was replaced - see picture M20

2) T2 BB actuated successfully with replacement tab - vacuum remained stable

3) slow leaking valve connections were tightened again

4) water level in expansion tank corrected to just below 40 cm 

The water level in the T2 cooling system expansion tank dropped to below the trip treshold of 20 cm (ref Cyclotron fault #16123), requiring the beam to be 'defined' off (see attached image).

Some calculations (see attached .html) show that over the period in which the tank level was dropping (from July 12 - Aug03, 2023) approximatley 11L of water was lost. At the end of the 'drop period' the leak rate was at a maximum of approximately 1L/day or 40mL/hour. 

The tank was filled up to 39 cm and we will continue to monitor the water level in the coming days.

We will also plan to enter the BL1A tunnels in the coming maintenance day (Tuesday, Aug 08) to check for poolig water. 

Alternative to a leak, entrapped air in the system may have escaped/been displaced to allowed 11L of water from the expansion tank to drop into the cooling loop.

If the lost 11L indeed occured due to leak, at least the leak will be outside of the vacuum volume since vacuum levels remained stable.

A likely source for a leak would be one of the exchanged valves from last shutdown.

Alternatively one of the not-exchanged valves may have started leaking due to aging/radiation damage.

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 UPDATE: Aug 08, 2023

The expansion tank at T2 was topped up to ~44cm on Friday Aug 04 ~12pm.

Over the long weekend (Friday Aug 04 ~12pm to Tuesday Aug 08 ~7am), ~14cm of water was lost and the water level in the expansion tank went below the low level warning limit (30cm).

Looking at the water level trend, the leak rate seems to be increasing (see attached - rate approximately doubled/trippled to 3L/day or 120 mL/hour).

Maico and Albert entered the BL1A tunnels at Aug 08 ~1pm and found trickling water underneath the T2 cooling package (see attached). Fortunately, no pooling water was found in the BL1A tunnels.

A plan must be developed to decide the appropriate course of action to remedy this problem.

Tentatively we have two choices:

1) attempt to remedy the leak during a maintenance day by uncovering the T2 cooling station. 

2) accept the leak until the mini shutdown in October (requiring ~2-3 expansion tank 'top-ups' every week for 2 months or so).

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UPDATE: Aug 11, 2023

The expansion tank was topped up again to ~44cm on Thursday Aug 10, ~8am.

Since then the water level has dropped to ~34.5cm on Friday Aug 11, ~9am. ~10cm of water was lost within the span of a day, equating to ~6L/day or ~250mL/hour (see attached calculations).

From the data, it seems like the leak has stabilized to this value. 

An SAS job request has been filed to uncover the cooling package during the mini shutdown to fix the leak. Leading up to this, it would likely be a good idea to regularly enter the BL1A tunnel and assess the condition of the leak. 

Additionally, it will be necessary to fill the expansion tank to the brim every two days or so to keep it from tripping the beam.

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UPDATE: Aug 15, 2023

We took advantage of an unexpected maintenance window this week to uncover the blocks surrounding T2 and identified that the source of the leak was a 'pinched' o-ring on the Q2 flow meter (demin water return - see attached pictures). 

The bottom set of screws on the flow-meter o-ring plate was loose when we took it apart. The o-ring may have been pinched when it was assembled back in 2022, making it difficult to establish even loading on all screws.

The bottom screws then creeped loose over time, creating the leak. 

The o-ring was successfully replaced, the pump was turned back on with no immediate leaking at the service flow-meter, and the expansion tank was filled to 39cm.

We will monitor the water level overnight and inspect the cooling package for leaks before deciding the next steps tomorrow morning (if no leaks found, we will proceed with closing up the T2 area).

We will specifically asess whether the puddle underneath the main tank (see picture) dries up in addition to tracking the expansion tank water level.

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UPDATE: Aug 16, 2023

The water level remained stable overnight, up-close visual inspection of the serviced flow-meter and the cooling package in general confirms that the leak has been fixed.

The fill rate of the active sump in XTpage P2 also leveled.

See attached html document (updated calculations and notes) for relevant information.

Work to re-place the blocks started after confirmation of the fix.

 See Cyclotron fault 16553. 

"B1A:T2CS:FGTGT readback is toggling at the warn limit of 3.0 GPM and over the last week has started crossing over the trip threshold of 2.8 GPM, tripping off the water package. Initial Action Taken: 1A is scheduled to take beam on December 13."

Upon reviewing the flow trend over the past semester, the flowrate has been hovering around 3.0 GPM the whole time.

Meanwhile, the water temperatures in/out of the T2 target has remained stable between 24C to 31C with the warn and trip limits > 35C. 

It should therefore be safe to run the target cooling water at a lower flowrate.

As a temporary solution, the low trip limit was adjusted to 2.5 GPM. While the trip was kept at 3.0 GPM.

We will look at how flowrate through the target can be increased in the coming shutdown.

For reference, the T1 target flow trip was set to 2.0 GPM an warn was set to 2.3 GPM (see MH-RH ELOG 331).

The resin flask on the T2 cooling package was exchanged today (new resin can prepped in the morning). 

The newly installed resin flask was placed slightly off-set from the marking on the platform to ensure that the braided hose will clear the blocks when replaced at the end of shutdown.

The spent resin can was dropped off in the hot cell, ready to be prepped for drying. 

See attached image for illustration of the rigging solution used, ~20 ft was covered by two sligs and a shackle to clear the MH mezzanine.

The lower amplifier for the T2 target station air supply was removed for teardown, inspection, and rebuild. 

The goal of this operation is to understand wear development in the air amplifier over ~13 years of operation, and potentially determine a recommeded service interval.

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The T2 volume was vented for an unrelated maintenance operation during this time.

During testing, prior to removing the lower amplifier, both regulators were set to ~20 psi. 

The upper air amplifier resulted in ~125 psi at the outlet while the lower air amplifier resulted in ~120 psi at the outlet.

The upper air amplifier had more audible air flowing out from the muffler than the lower amplifier. 

'Scratching' sounds in both amplifiers were comparable.

The following cycle times were recorded with the M20 BB raised/out (min:sec):

    UPPER: 1:22 / 1:00 / 2:06

    LOWER: 2:30 / 1:46 / 2:12

The following times were recorded to raise the M20 BB (sec): 

    UPPER: 8.36 / 8.76

    LOWER: 8.56 / 9.10

These times will be compared against after completing the teardown and rebuild of the lower amplifier, at which point this ELOG will be updated.

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UPDATE (Feb 23, 2024):

The lower air amplifier was serviced (photos in 'S:\Albert Kong\Shutdown Files\2024\Feb20 T2 Lower Amplifier Cleanup'):

1. Full assembly cleaning.
2. Piston and barrel was cleaned and lubricated, o-rings and plastic components replaced (with new lubricated ones).
3. Pilot valve components replaced (except plug).
4. Check valves (4x) cleaned and plastic/rubber components replaced (with new lubricated ones). 
5. Muffler cleaned (blown out with compressed air).
6. Spool and sleeve assembly cleaned, o-rings replaced (with new lubricated ones), and rubber stopper replaced.
7. Clamping rods tightened to ~17 ft-lbs. 

Note: the piston o-rings were difficult to seat on the piston body/teflon ring. During assembly, we instead seated the o-ring in the barrel on the piston plates (see picture), which allowed the oring to be seated properly, before placing the piston body onto the piston rod.

After servicing, the amplifier was returned to the station, air connections reconnected, and tested. 

Note: it is recommended to do torque-ing of the clamping rods as a final step to simplify mounting of the amplilfier and re-doing connections to the rest of the compressed air system.

The first observation we made was how silently the lower amplifier now operates when cycled: only the exhaust sound from the muffler can be heard.

Note that the piston's motion can be heard when listening ~5cm away from the amplifier barrel. 

The following times were recorded to raise the M20 BB (sec):

    UPPER: ~8.5 

    LOWER: ~7.7s

The following cycle times were recorded with the M20 BB in the out/raised position (min:sec):

    UPPER: 1:05 / 1:04

    LOWER: 1.22 / 1:45

The outlet pressure from the amplifier registers 120 psi with the regulator set only to 15 psi (improvement from previous performance as well as the upper air amplifier's performance).

We will check in on the amplifier next week to see if it still operates silently and can actuate the beam blockers/profile monitor without issue, at which point this ELOG will be updated. 

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UPDATE (Feb 26, 2024):

The lower amplifier was inspected this morning, higher volume sound could be heard from the drum in concert with the motion of the piston, but still much quieter than before servicing.

At ~8am on May 06, the expansion tank level sensor for the T2 cooling system suddenly became noisy. 

Cyclotron fault ref: 16915

Approximately 11:00 am today, the noisy sensor was replaced with a spare, upon which it was learned that the spare sensor is broken (registers 0 level and not detected on PC through USB adapter).

The old (noisy sensor) was then replaced at around 12.00 pm onto the expansion tank and it was found that the noise had subsided.

A possible explanation to the noise would be loose connections/grounding wire.

We will continue to monitor the sensor in the coming days, and order replacement sensors has been placed and we will be able to replace the sensor soon should it become noisy again.

Edit 2024-05-07 - A. Newsome: EPICS monitoring shows the sensor appears to be behaving normally since the aforementioned events. Most likely attributed to improper grounding. The fault will be closed. See attached screenshot.