On May 31, the low active water in BL1A was turned off briefly and upon re-starting, the flow to the T1 heat exchanger was very close to the reported warn limit (~6 gpm). 

To see if this low flow could be remedied, we entered the BL1A tunnels briefly on Jun 06 but found no flow regulator valves for the T1 heat exchanger. 

The low flow to the heat exchanger after the secondary water pump was re-started may be a normal characteristic of the system. Alternatively, this may have been caused by entrapped air in the heat exhanger after it was drained during 2023 shutdown to replace a leaky valve. 

The latter is grounded in the fact that the flow in T2 recovered immediately after the flow was re-started. T2 was drained through a drain line in the tunnels whereas T1 was drained at the cooling station through a filter/copper line. 

The difference in draining methods may have resulted in entrapped air and thus flow issues in T1 but not T2.