110.02 Safety Limits

Question 1

• 110.02 Safety Limits*
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LIST and EXPLAIN the general types of reactor protection provided at your plant.

Answer 1

Well trained operators - the most important

Indications and alarms - provide operator valuable information

Inherent safety features (design):

• Negative FTC
• Negative MTC
• Negative Void Coefficient

Reactor protection system - Nuclear flux, PZR, RCS Temp & Flow, S/G trips

ECCS

Question 2

• 110.02 Safety Limits*
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What are the nuclear flux trips as part of the Reactor Protection System?

Answer 2

• Source Range Hi Flux - power excursion from a subcritical condition
• Intermediate and Power Range Hi Flux Low Setpoint - power excursion from a subcritical or low power condition
• Power Range Hi Flux Hi Setpoint - power excursion from an at power condition
• Power Range Hi Positive Rate - rod ejection accident.

Question 3

• 110.02 Safety Limits*
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What are the pressurizer trips and as part of the Reactor Protection System?

Answer 3

• Low Pressure - Protects against DNB
• High Pressure - Protects the integrity of the RCS
• High Level - Prevents water relief through the pressurizer safeties

Question 4

• 110.02 Safety Limits*
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What are the RCS temperature trips as part of the Reactor Protection System?

Answer 4

• Overpower ΔT - Protects fuel integrity by limiting kw/ft produced in the core
• Overtemperature ΔT - Provides protection against DNB

Question 5

• 110.02 Safety Limits*
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What are the RCS flow trips as part of the Reactor Protection System?

Answer 5

• Low Flow - Provides protection against DNB
• RCP Bus Undervoltage and Underfrequency - Anticipatory low flow trip to protect against DNB

Question 6

• 110.02 Safety Limits*
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What are the steam generator trips as part of the Reactor Protection System?

Answer 6

•S/G Low Level - Ensure an adequate heat sink for the reactor

Question 7

• 110.02 Safety Limits*
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STATE and EXPLAIN the two safety limits at the South Texas Project as stated in the Technical Specification.

Answer 7

Reactor Core

2. 1.1 The combination of THERMAL POWER, pressurizer pressure, and the highest operating loop coolant temperature Tavg) shall not exceed the limits shown in the Core Operating Limits Report.
3. 1.1.1 In MODES 1 and 2, the departure from nucleate boiling ratio (DNBR) shall be maintained >1.17 for the WRB-1 DNB correlation and >1.14 for the WRB-2M DNB correlation.
4. 1.1.2 In MODES 1 and 2, the peak fuel centerline temperature shall be maintained < 5080°F, decreasing by 58 °F per 10,000 MWD/MTU of burnup.

APPLICABILITY: MODES 1 and 2.

Reactor Coolant System Pressure

2.1.2 The Reactor Coolant System pressure shall not exceed 2735 psig.

APPLICABILITY: MODES 1, 2, 3, 4, AND 5.

Question 8

• 110.02 Safety Limits*
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DRAW a basic diagram of the Safety Limit Curve, including flow, pressure, temperature, and power.

Answer 8

Question 9

• 110.02 Safety Limits*
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Explain the basis for the shapes of the safety limits curve.

Answer 9

Green slope for bulk boiling, red for DNB.