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Message ID: 1419     Entry time: Thursday, January 12, 2017, 14:24
Author: David Wang 
Category: ITW 
Type: Standard Operation 
Module: TM2 
Target/Number:  
Subject: ITW primary and secondary vacuum vessel winter shut down leak check. 

TM2 is located in ITW for this leak check. Leak detector is installed between ITW BV2s as before. LD base leak rate 0.0XE-9atm.cc/sec, base pressure 0.0XE-4 Torr. First , I leak checked dump module top flange seal which a small leak was found in last year winter shut down. This time,all ITW  turbo-pumps cooling fans are switched off during the check. Lots helium are sprayed around the dump module top flange this time. I did not see any response on LD.  The check is repeated 3 times. The results are same. There is no leak has been found on ITW dump module top flange seal at this moment. The  further confirming check will be repeated  when TM2 is moved back to ITW with dummy Febiad target  at the end of this month. The rest check result:  1 small leak(1.2 xE-8 atm.cc/sec) is found on one TM2 blue nylon bottom o-ring. This o-ring will be replaced when module is moved out of ITW.  It will be an easy job. Another small leak( 1.1XE-8 atm.cc/sec) is found on exit module 1 service cap top plate to frame o-ring seal. Its location is on east-south side of the exit module 1.This side is close and parallel to exit module 2 west-south side. Vacu- seal sprayer is used to fix this problem.  After two times spray, the leak is disappeared. This is not a permanent fix. The big top plate o-ring replacement is a complicate and dose taking job. It need to be well planned. The leak rate is small, and the leak source is close to ITW TP3 so there is no rush to replace the big o-ring on exit 1 service cap top plate at this moment. But, we need to close watching on this issue and have a job plan for this o-ring replacement since it could get worse in the future. There is no leak has been found on big T tank seal this year as well. All other primary and secondary vacuum seals  in ITW are good. TM2 water lines helum pressurize will be fulfilled In ITW or at TCS later. I will update this e-log when further test are finished.

 2017-01-25:  The O-ring on 60KV bias blue nylon stand is replaced at TCS. I leak check it. It is perfectly good now.

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