Tech Specs Flashcards
Reactivity Control and Power Distribution Limits
3.1.1 Shutdown Margin
List LCOs and Applicability
LCO
SDM Shall Be:
A. >= 0.38% dk/k with the highest worth control rod analytically determined; or
B. >= 0.28% dk/k with the highest worth control rod determined by test.
Applicability: Modes 1-5
3.1.1 Shutdown Margin
List all conditions that require action in 1 hour or less.
SDM Not within Limits
Mode 3:
Insert all insertable control rods.
Mode 4:
Insert all insertable control rods
Initiate action to restore primary containment to OPERABLE
Initiate action to restore isolation capability in each required primary containment penetration flow path not isolated
Initiate action to close one door in each primary containment air lock
Mode 5:
Suspend CORE ALTS except for control rod insertion and fuel assembly removal.
Initiate action to insert all insertable control rods in core cells containing one or more control rods.
Initiate action to restore primary containment to OPERABLE
Initiate action to restore isolation capability in each required primary containment penetration flow path not isolated
Initiate action to close one door in each primary containment air lock
3.1.1 SDM Bases
What are the 3 reasons for having SDM requirements?
1. Reactor can be made subcritical from all operating conditions and transients and Design Basis Events.
2. Reactivity transients associated with postulatd accident conditions are controllable within acceptable limits.
3. The reactor will be maintained sufficiently subcritical to preclude inadvertant criticality in the shutdown condition.
3.1.1 SDM Bases
Regarding safety analysis, what does an adequate SDM provide?
Adequate SDM provides assurance that inadvertant criticalities and potential rod drop accidents involving high worth control rods (namely the first control rod withdrawn) will not cause significant fuel damage.
3.1.1 SDM Bases
Discuss the difference between analytical and tested values of SDM.
Tested values are representative of the actual configuration. Uncertainty exists in design calculations that are accounted for with the extra value.
3.1.1 SDM Bases
Discuss the bases of the applicability requirements for SDM.
Modes 1 & 2 the SDM must be provided because subcriticality with the highest worth control rod withdrawn is assumed in the rod drop accident.
In modes 3 & 4, SDM is required to ensure the reactor will be maintained subcritical with margin for a single withdrawn control rod.
Mode 5 is to prevent inadvertant criticality during the withdrawal of a single control rod from a core cell containing one or more fuel assemblies.
3.1.2 Reactivity Anomalies
List LCOs and applicabilities
LCO
The reactivity difference between the monitored rod density and the predicted rod density shall be within +/- 1% dk/k.
Applicability
Modes 1 & 2
3.1.2 Reactivity Anamolies Bases
Why is the reactivity anamoly LCO established?
Ensure plant operation is maintained within the assumptions of the safety analysis.
3.1.2 Reactivity Anamolies Bases
Discuss the importance of a 1% deviation in predicted to actual reactivity.
> 1% difference is considered larger than expected and should be evaluated. Accurate prediction of reactivity is an implicit and explicit part of safety analysis calculations.
3.1.3 Control Rod Operability
List LCOs and Applicabilities
Are there any notes associated with this LCO?
LCO
Each control rod shall be operable.
Applicability
Modes 1 & 2
Notes
Separate Condition entry is allowed for each control rod.
3.1.3 Control Rod Operability
What 1hr or less actions are associated with this LCO?
Condition One withdrawn control rod stuck.
Action
Immediately: Verify stuck control rod separation criteria are met.
3.1.3 Control Rod Operability Bases
From a safety analysis standpoint, what does insertion of control rods provide?
Assurance that the assumptions for scram reactivity in the DBA and transient analysis are not violated.
3.1.3 Control Rod Operability Bases
What major factors are considered when determining control rod operability?
Scram Insertion Times, Control Rod Coupling Integrity, and Control Rod Position Indication.
3.1.3 Control Rod Operability Bases
When is a control rod considered stuck?
Considered stuck if it will not insert (using all available methods of insertion) by either CRD drive water or scram pressure.
3.1.3 Control Rod Operability Bases
Regarding stuck control rods, what is separation criteria?
There are two different separation criterias established in 3.1.3 Bases
Slow and stuck control rods, and Bank Position W/D Sequence
For stuck control rods and slow control rods
A stuck control rod may not occupy a location adjacent to a “slow” control rod.
Regarding BPWS
Control rods not in compliance with BPWS must be separated by at least two OPERABLE control rods in all directions, including diagonal. This is only applicable <= 19% RTP.
3.1.3 Control Rod Operability Bases
Discuss the requirements when a large amount of control rods are INOPERABLE. What is the basis of this criteria?
When 9 or more control rods are inoperable, a mode change to Mode 3 is required.
The occurrence of a large number of inoperable control rods is indicative of a larger problem, and the control rods should be placed in a position where a scram is not required.
3.1.4 Control Rod Scram Times
List the LCOs and Applicabilities
LCO
A. No more than 13 OPERABLE control rods shall be slow IAW Table 3.1.4-1 AND
B. No OPERABLE control rod that is slow shall occupy a location adjacent to another OPERABLE control rod that is “slow” or a withdrawn control rod that is stuck.
Applicability
Modes 1, 2
3.1.4 Control Rod Scram Times
What is the criteria for a control rod to be considered slow?
Review the table attached.
Based on certain steam dome pressures, there is a maximum time from different notch positions. If the control rod does not fully insert from these positions in this time, the rod is considered slow.
3.1.4 Control Rod Scram Times
How slow can a control rod be before it is considered INOPERABLE?
What actions are required for a control rod that meets this criteria?
Any rod that takes longer than 7 seconds to scram is considered INOP.
Enter required actions for LCO 3.1.3 “Control Rod Operability”
3.1.4 Control Rod Scram Times Bases
What does the Scram function of the CRD system protect?
How does this change with Reactor pressure?
What do these protected features ensure?
Protects the MCPR Safety Limit and the 1% cladding plastic strain fuel design limit. (MCPR, LHGR, APLHGR).
Above 950 psig, the scram function is designed to insert negative reactivity at a rate fast enough to prevent the actual MCPR from becoming less than the MCPR Safety Limit during the analyzed limiting power transient.
Below 950 psig, the scram function is assumed to perform during the control rod drop accident, and, therefore, also provides protection against violating fuel damage limits during reactivity insertion accidents.
Ensures no fuel damage will occur if these limits are not exceeded.
3.1.4 Control Rod Scram Times Bases
How are scram times classified as slow for intermediate steam dome pressures?
Linear Interpolation.
3.1.5 Control Rod Scram Accumulators
List the LCO and Applicabilities.
What actions have requirements of 1 hour or less?
LCO
Each control rod scram accumulator shall be OPERABLE.
Applicability
Modes 1 & 2
NOTE
Separate condition entry is allowed for each control rod scram accumulator
1 Hour or Less Actions
For Action B
When steam dome pressure is > 600 psig and two or more scram accumulators are inoperable, complete the following:
Within 20 Minutes from discovery of entry into condition, restore charging water header pressure to >= 1520 psig.
AND
Within 1 hour-
Declare the associated control rod scram time as “slow”.
Note: This action is only applicable if the associated control rod scram time was satisfactory in the most recent scram time test.
*OR
Declare the associated control rod inoperable.
For Action C
With steam dome pressure < 600 psig, if charging water header pressure is < 1520 psig, immediately verify all control rods associated with inoperable accumulators are fully inserted
AND
Within 1 hour, declare the associated control rods inoperable.
For Action D
If the required actions of Action B.1 or C.1 are not met, immediately place the mode switch in shutdown.
Note: This requirement is not applicable if all control rods associated with inoperable accumulators are already fully inserted.
3.1.5 Control Rod Scram Accumulators Bases
Why is the operability of the scram accumulators required and what determines their operability?
Ensures that adequate scram insertion capability exists when needed over the entire range of reactor pressures.
Operability is based on maintaining adequate accumulator pressure.
3.1.6 Control Rod Pattern
List the LCO and Applicability.
What 1 Hour or less actions are associated with this LCO?
LCO
Operable control rods shall comply with the requirements of the banked position withdrawal sequence.
Applicability
Modes 1 & 2 at RTP <= 19%.
1 Hour or less actions
Action B
With 9 or more operable control rods not in compliance of the BPWS, immediately suspend withdrawal of control rods and place the mode switch in shutdown within 1 hour.
