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Flashcards in Precautions And Limitations Deck (21):

For a plant start-up following a reactor trip, why must we review TRP-001?

Ensures that the cause of the trip is known and all auto responses have functioned properly and that a unit is not returned to service with unidentified safety problems.


Why must a Reactor Engineer be present as part of the control room team during approach to criticality and power changes until 30% RTP?

Ensures team has technical expertise to manage changes in reactivity IAW standards and expectations.


When changing RCS boron concentration, why do we use PZR spray and how do we accomplish this?

Minimizes the difference by PZR and loop boron concentration from a PZR out surge.

Accomplished by energizing the heaters.


When do we maintain shutdown banks fully withdrawn?

Provide additional margin when reactivity is being changed by boron or xenon changes, RC temp or motion of control banks.


If during any step involving boron dilution the SR count rate increase is greater than anticipated, why must you stop immediately and involve the SM?

Potential loss of SDM


Why are concurrent positive reactivity additions by more than one method while going critical or at low power near the POAH prohibited?

Recommendation of SOE 88-02.

Limiting addition to only one source better enables the operator to control reactivity.


What do TS 3.4.1, 3.4.4 and 3.4.5 assure?

Adequate DNBR margin during Condition I or II events in this Mode.

Ensures Integrity of secondary ESF features when a loop in no longer coupled to the secondary.


Why must the group step counters for that bank be at zero steps before withdrawing any rod bank from the fully inserted position?

To ensure proper bank overlap.


How is temperature recovered if the temperature lowers below 541*F?

Reduction in steam demand


Why would we desire to have SG Blowdown in service during a startup?

To remove impurities to prevent SG tube degradation


What is meant by mode changes with DEGRADED equipment is permissible provided OPR-001 has been performed?

Equipment cannot be physically inoperable


Why is it crucial for the operator controlling the Reactor and the operator controlling SG levels to communicate and utilize precise control?

Changing reactor power will shrink and swell SG levels.

Changing feed flow rate will raise and lower reactor power.


Why can you not energize any control or shutdown rods unless all MTI star-up STPs are complete and current?

MTI start-up surveillances can only be performed while shutdown.


Why might reactor engineering notify Operations that control rods have a much higher rod worth?

INPO SER 21-88 Commitment

The magnitude of a + MTC is reduced by decreasing boron concentration, which lowers the critical rod height. As a result, worth may be as much as 5X higher


Which instruments must be utilized as a minimum when monitoring the approach to criticality?

1. ICRR Plot (until SR NIs are de-energized)
2. Audio Count Rate (until SR NIs are de-energized)
3. Nuclear Instrumentation
4. RCS delta T
5. Reactivity Computer (if available)


Why should delta T power be monitored as a backup indication for NIs power?

SOER 90-03 Recommendation

Core thermal power is not calculated until approx 30%


Why should control rods be reinserted if the approach to criticality is suspended for an extended period of time?

Sitting close to critical for a long period of time increases the possibility of achieving an inadvertent criticality in an uncontrolled fashion.

Sitting could result in changes in reactivity parameters used in the ECP calculation.


When changing the Rod Bank Selector Switch position, why is in important to not go thru AUTO?

Precludes possibility of inadvertently driving the P-A converter to 999 due to inward demand or to prevent inadvertent rod motion


Why should the SG PORVs not be used as a planned method of RCS temperature control?

This minimizes expenditure of pure water and minimizes the noise to the surrounding communities.


Whose permission is needed to use SG PORVs as the planned method of RCS temperature control?

Ops Director


How does rod withdrawal limits help ensure MTC stays inside TS Limits?

Limiting rod withdrawal requires RCS boron reduction to raise power. Reducing boron causes MTC to be more negative