Plant Operating Standard

CRD-86 Control Rod Drive System

A. Normal Operations

• 1. All 21 drive mechanisms operable in assigned groups with proper limit switch action, position indication, drive speeds, hydraulic balance, and scram ability.
• 2. One hydraulic pump operating at 3075 psig, and a second set for AUTO start and fed electrically by the opposite main Switchboard bus. Drive system electrical busses energized and ABT's set for AUTO transfer. Reactor head insulation and oil drip shield are to be in place before pressurizing the oil system.
• 3. Associated reservoirs valved together by the equalizing line and oil levels in operating range.
• 4. Bias control by manual bias pressure regulating valve.
• 5. No oil leaks in any portion of the hydraulic system.
• 6. Setpoints as listed in set point list standard.
• 7. Cubicle doors closed and blower operating.
• 8. Test-Engaged switches in NORMAL.
• 9. No alarms Present.
• 10. Rods in group maintained within 1/2 inch of the group indicator.
• 11. Control rod movement at any time is to be controlled from the console.
• 12. Hydraulic oil sampling kept on a minimum frequency of once every week. (4 oz. oil sample) Cleanliness of the hydraulic oil must be maintained within the vendor's specifications, as follows:
  • 0 particles greater than 100 microns
  • 2 particles in 50-100 microns range
  • 3 particles in 25-50 microns range
  • 10 total number of particles between 14-100 microns
  • 13. Both oil coolers operable with oil temperature maintained between 65F and 155F.
  • 14. Oil level to be greater than 9" above bottom of sight glass.

  B. Minimum Condition for Reactor Operation

  • Nineteen (19) rods shall be available for scram for continued operation from the control room. A rod is defined as unavailable for scram if any of the three following conditions exist:
    • a) Physically stuck
    • b) Low accumulator gas alarm
    • c) Liquid detector alarm

    Operation with more than two rod unavailable, by the above criteria, shall continue only after an operator has been stationed in the electrical cubicle with communication to the control room.

    Indication of five (5) rods unavailable for scram is cause for shutting the reactor down.

  • 2. The reactor shall be shut down immediately upon any indication that more than one control rod drive line stop is not engaged with its drive carriage.
  • 3. Hydraulic oil is maintained below maxiumum temperature (155F).

  C. Shutdown Conditions

  • 1. An attempt should be made to keep the hydraulic system in operation except during required maintenance.
  • 2. The rods must be exercised at least once every two weeks during a prolonged outage. Exersize must consist of at least two (2) inches of movement to clear the backup packing.

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  My text copyright 2020 Tommy Johnson, all rights reserved. I believe the Savannah documentation is property of MARAD or the US government.