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- Assorted 45 cm long epoxy cores with varying amounts of K and Th (Isotope Products Labs, Burbank, CA).
- NOTE! Although some of the epoxy IPL cores state a U concentration, the U salts were not included in these standards!
- Two 60 cm long plaster cores with U (produced by Dr. Grigor Chubaryan, Texas A&M University Cyclotron Institute)
- Disk-shaped 137Cs, 60Co and 152Eu radioactive sources (Eckert & Ziegler Isotope Products, Valencia, CA).
The activity of the epoxy and plaster cores is extremely low—significantly lower than background levels—and can be handled safely even for extended periods of time. The disk-shaped sources are 1 µCi nominal activity and should be handled only by properly trained operators. They do not represent a short-term hazard, but long-term exposure would be harmful.
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- If air conditioning (AC) is not functioning properly
- If atmospheric condensation forms on the NGRL and other instrument surfaces, shut down the high-voltage supplies to all the detectors to avoid an electrical short.
- Shut down other NGRL equipment (fans, cooling crates, iSEG crates, delivery system, and computer) only when very long AC interruptions with heavy condensation formation are expected or occur. Note that condensation typically occurs when the AC is restored; it can also happen if humid fresh air continues to be pumped in but the AC is not working.
- After partial shutdown, do not power back up for at least 4 hours after AC is functional without additional condensation.
- If an extended ship’s power supply shutdown is scheduled
- Full shutdown may be necessary.
- During short power supply interruptions, the power supply UPS, through which all NGRL electronics connect to the power line should provide enough electricity until power returns; however, it is important to monitor the AC situation and if humidity becomes an issue, a shutdown is needed.
- After full shutdown, wait at least 4 hours after normal AC function returns and condensation disappears.
Figure 8, below, shows the location of the main power switch and the two NIM 4001B crate power switches.
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- Take your time. Let the electronics settle. This is not a race.
- Voltages across any given NaI(Tl) detector may be monitored with a volt-meter at the bias box with 8 red touch points and a white single ground point.
- Do not change the voltage at any NaI(Tl) detector at the junction box!!! Remember if you need to switch off the High Voltage you must switch off the whole right-hand NIM crate (right-hand NIM crate button in Fig. 12), which will turn the high voltage off from all NaI(Tl) detectors simultaneously.
- Follow all steps in the Partial Shutdown procedure first.
- Turn off the power switch to the iSEG voltage control crate (behind iSEG unit).
- Turn off the fast signal processing electronics (Fig. 13; leftmost NIM rack).
- Shut down the computer.
- Turn off the master power switch above the middle NIM rack (blue circle in Fig.
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- 13).
- The fans are connected to the
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- uninterruptible power supply (UPS) and must be unplugged to turn off.
Figure 13. Master Power Switch.
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