ML18139B873

Proposed Tech Specs 3.12-8,3.12-10,3.12-11,3.12-12 & 3.16-2 Re Inoperable Control Rods,Rod Position Indicator Channels & Misaligned or Dropped Control Rod

ML18139B873
Person / Time
Site:	Surry
Issue date:	05/10/1982
From:	VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:
Shared Package
ML18139B872	List: ML18139B871 ML18139B873
References
NUDOCS 8205180373
Download: ML18139B873 (5)

Text

e* TS 3.12-8 AT and Overtemperature h T trip settings shall be reduced by the equivalent of 2% power for every 1% quadrant to average power tilt.

c. Inoperable Control Rods

1. A control rod assembly shall be considered inoperable if the assembly cannot be moved by the drive mechanism or the assembly remains misaligned from its bank by more than 12 steps.

Additionally a full-length control rod shall be considered inoperable if its rod drop time is greater than 1.8 seconds to dashpot entry.

2. No more than one inoperable control rod assembly shall be perm~tted when the reactor is critical.

3. If more than one control rod assembly in a given bank is otit of I

service because of a single failure external to the individual rod drive mechanism, i.e. programming circuitry, the provisions of Specifications 3.12.C.1 and 3.12.C.2 shall not apply and the reactor may remain critical for a period not to exceed two hours provided immediate attention is directed toward making the necessary repairs.

In the event the affected assemblies cannot be returned to service within this specified period the reactor will be brought to hot shutdown conditions.

4. The provisions of Specifications 3.12.C.l and 3.12.C.2 shall not apply during physics tests in which the assemblies are intentionally misaligned.

5. The insertion limits in TS Figure 3.12-2 apply: a. If an inoperable full-length rod is located below the 200 step level and is capable of being tripped, *a"r

.J

.e** e TS 3.12-10

2. The core quadrant power balance shall be determined by one of the following methods:

a. Movable detectors (at least two per quadrant)

b. Core exit thermocouples (at least four per quaarant)

E. Rod Position Indicator Channels

1. The rod position indication system shall be operable and capable of determining the control rod positions within +/-12 steps.

2. If a rod position ind.icator channel is out of service, then:

a. For operation above 50% of rated power, the position of the RCC shall be checked indirectly using core instrumentation (excore detectors and/or incore thermocouples and/or movable incore detectors) at least once per 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> and immediately after any motion of the non-indicating rod exceeding 24 steps,-

or

b. Reduce Power to less than 50% of rated power within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />.

During operations below 50% of rated power, no special monitoring is required.

3. If more than one rod position (RPI) indicator channel per group or two RPI channels per bank are inoperable, then the requirements of Specification 3.0.1 will be followed.

TS 3.12-11 F. Misaligned or Dropped Control Rod

• 1. If the Rod Position Indicator Channel is funcUonal and the associated full length control rod is misaligned from its group step demand postion by more than +/-12 steps (indicating postion) and cannot be realigned, the hot channel factors must be shown to be within design limits as specified by Specification 3.12.B.1 within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />. If the limits of Specification 3.12.B.1 cannot be met, then.

power shall be reduced to less than 75% of rated power within one (1) hour, and the High Neutron Flux trip setpoint shall be reduced to less than or equal to 85% of rated power within the next four _(4) hours.

2. To increase power above 75% of rated power with a full-length control rod more than +/-12 steps (indicated position) out of alignment with its group step demand postion, an analysis shall first be made to determine the hot channel factors and the resulting allowable power level based on the limits of Specification 3.12.B.1.

Basis The reactivity control concept assumed for operation is that_reactivity changes accompanying changes in reactor power are compensated by co~trol rod assembly motion. Reactivity changes associated with xenon, samarium, fuel depletion, and large changes in reactor coolant temperature (operating temperature to cold shutdown) are compensated for by changes in the soluble boron concentration. During power operation, the shutdown groups are fully withdrawn and control of power is by the control groups. A reactor trip occurring during power operation will place the reactor into the hot shutdown condition. The control rod assembly insertion limits provide for achieving hot shutdown by reactor trip at any time, assuming the highest worth control rod assembly remains fully withdrawn, with sufficient margins to meet the assumptions µsed in the accident analysis. In addition, they provide a limit

-- e TS 3.12-12 on the maximum inserted rod worth in the unlikely event of a hypothetical assembly ejection and provide for acceptable nuclear peaking factors. The limit may be determined on the basis of unit startup and operating data'to provide a more realistic limit which will allow for more flex~bility in unit operation and still assure compliance with the shutdown requirement. The maximum shutdown margin requirement occurs at end of core life and is based on the value used in the analysis of the hypothetical steam break accident. The rod insertion limits are based on end of core life conditions. The shutdown margin for the entire cycle length is established at 1.77% reactivity. All other accident analysis with the exception of the chemical and volume control system malfunction analysis are based on 1% reactivity shutdown margin.

Reiative positions of control rod banks are determined by a specified control rod bank overlap. This overlap is based on the consideration of axial power shape control.

The specified control rod insertion limits have been revised to limit the potential ejected rod worth in order to account for the effects of fuel densification.

The various control rod assemblies (shutdown banks, control banks A, B, C, and D) are each to be moved as a bank; that is, with all assemblies in the bank within one step (5/8 inch) of the bank position. Position indication is provided by two methods: a digital count of actuating pulses which shows the demand position of the banks, and a linear position indicator, Linear Variable Differential Transformer, which indicates the actual a~sembly position. The position indication accuracy of the Linear Differential Transformer is approximately +5% of span

(+/-12 steps) under steady state conditions. The relative accuracy of the linear position indicator has been considered in establishing the maximum allowable deviation of a control rod assembly from its indicated group step

_demand position. In the event that the linear position indicator is not

.e* e TS 3.16-2

4. Two physically independent circuits from the offsite transmission newtork to energize the 4,160 and 480 v emergency buses. One of these sources must be immediately available, i.e. primary source; and the other must be capable of being made available within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />; i.e. dependable alternate source.

S. Two operable flow paths for providing fuel to *each diesel generator.

• 6. Two station batteries, two chargers, and the d.c. distribution systems operable.

7. Emergency diesel generator battery, charger and the d.c. control cir-

- cuitry operable for the unit diesel generator and for the shared back-up diesel generator.

B. During power operation or the return to power from hot shutdown conditions, the requirements of specification 3.16-A may be modified by one of the following:

1, One diesel generator may be unavailable or inoperable provided the operability of the other diesel generator is d~nstrated daily. If this diesel generator is not returned to an operable status within 7 days, the reactor shall be brought to a cold shutdown condition.

One diesel fuel oil flow path may be "inoperable" for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> pro-vided the other flow is proven operable. If after 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, the inoperable flow path cannot be returned to service, the diesel shall be considered "inoperable". 'When the emergency diesel genera-tor battery, charger o~ d.c. control circuitry is inoperable, the diesel shall be considered "inoperable".