ML20246C914

Proposed Tech Specs,Deleting Remote Shutdown Instrumentation Requirements for full-length Control Rod Position Limit Switches Contained in Tables 3.3-9, Remote Shutdown Instrumentation & 4.3-6, Remote Shutdown Monitoring..

ML20246C914
Person / Time
Site:	Sequoyah
Issue date:	05/02/1989
From:	TENNESSEE VALLEY AUTHORITY
To:
Shared Package
ML20246C890	List: ML20246C887 ML20246C914
References
NUDOCS 8905100065
Download: ML20246C914 (13)

Text

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ENCLOSURE 1.

PROPOSED TECHNICAL SPECIFICATION CHANGE SEQUOYAH NUCLEAR PLANT UNITS 1 AND 2 DOCKET NOS. 50-327 AND 50-328 (TVA-SQN-TS-89-23)

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ENCLOSURE 2 PROPOSED TECHNICAL SPECIFICATION CHANGE SEQUOYAH NUCLEAR PLANT UNITS 1 AND 2 DOCKET NOS. 50-327 AND 50-328 (TVA-SQN-TS-89-23)

DESCRIPTION AND JUSTIFICATION FOR DELETING THE REMOTE SHUTDOWN INSTRUMENTATION REQUIREMENTS FOR FULL-LENGTH, CONTROL ROD POSITION LIMIT SWITCHES i

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l ENCLOSURE 2 Description of Change ,

a The Tennessee Valley Authority proposes to modify the Sequoyah Nuclear Plant (SQN) units 1 and 2 technical specifications to revise Tables 3.3-9,

" Remote Shutdown Monitoring Instrumentation," and 4.2-6, " Remote Shutdown Monitoring Instrumentation Surveillance Requirements." The proposed change deletes the requirements for full-length, control rod position limit switches (item 8) from these tables. A footnote for the unit 2 entry is also deleted.

Reason for Change At 1030, EDT, on April 29, 1989, the rod bottom circuitry for unit 1, full-length control rod E-13 was declared inoperable because of voltage fluctuations in the analog rod position indication (RPI) instrument channel. A simplified diagram of an RPI channel is included in Attachment 1. The primary rod bottom indications are located in the main control room (control building elevation 732) on panel M-4. The remote rod bottom indications are a part of the bistable cards located in equipment racks in the auxiliary instrument room (control building elevation 685). The remote shutdown panels are located in the auxiliary building electrical equipment area on elevation 734. 3 l

TVA has determined the remote rod bottom indications currently required by Specification 3.3.3.5 are not needed or used to achieve and maintain a unit in a safe shutdown condition. TVA therefore proposes to delete the requirements for remote rod bottom indication. A footnote for the unit 2 l entry is also deleted for completeness. '

Justification for Change 1

As described in the bases' for Specification 3.3.3.5, the purpose of the l remote shutdoen instrum;ntation is to ensure sufficient capability to I achieve and maintain a unit in a safe shutdown condition from outside the main control room. It has been determined that the rod bottom indications

. located in the auxiliary instrument room (racks R41-44) are not required -

to achieve this purpose.

Abnormal Operating Instruction (A0I) 27, " Control Room Inaccessibility," j provides procedural gu! dance to SQN Operations personnel regarding j appropriate actions to be taken in the event that the r:ain contret room ^

must be abandoned. Part A of AOI-27 specifically addresses the appropriate actions if either or both units are at power. In immediate operator actions, step III.A states that, when it is decided that the main control room must be abandoned, the reactor is to be tripped in accordance with emergency instructions.

Emergency Instruction (E or ES) 0, " Reactor Trip or Safety Injection,"

provides the actions necessary to verify the proper responses following a manual or automatic reactor trip. Immediate Action 1 of E-0 verifies that '

the reactor is tripped. This is accomplished by verifying that the rod i

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s 3 bottom lights in the main control room are on, the reactor trip breakers are open, the RPIs indicate zero steps, and the neutron flux is decreasing. The combination of all these indications provides assurance that the reactor has been shut down. If the verification of the above four steps indicates that the reactor has not tripped, the operator is instructed to follow the actions of Function Restoration Guideline (FR)

S.1, " Response to Nuclear Power Generation /ATWS." FR-S.1 provides guidelines for the insertion of negative reactivity into the core.

Immediate Action 2 of FR-S.1 initiates boration to the core. For a verified reactor trip, the operator transitions to ES-0.1, " Reactor Trip Response." ES-0.1 (Step 4) again verifies the insertion of control rods.

Emergency boration is initiated for any control rod not verified to be fully inserted.

The procedural steps described above provide the necessary action to ensure that the reactor is shut down before the control room is abandoned. The remote rod bottom indications located in the auxiliary instrument room are not relied upon to achieve shutdown of the reactor.

AOI-27 also provides the guidance for maintaining the unit in hot standby and for taking the unit to cold shutdown. Again, the remote rod bottom indicators located in the auxiliary instrument room are not relied upon.

The remote reactor trip breaker position indicators provided a status of l the rod drive system's ability to move rods. The source range indication in the auxiliary control room provides an indication of anomalies in this neutron flux after the unit is tripped. Should any anomalies arise, boration control is still available outside the control room.

In summary, it has been demonstrated that the rod bottom indicators located in the auxiliary instrument room are not required or used to achieve or maintain a unit shutdown from outside the main control room.

Rather, shutdown is achieved from the main contrci coom and verified before it is abandoned. The rod bottom indicators are not referenced in FSAR Section 7.4 as equipment necessary to achieve safe shutdown. As cuch, their deletion from the TSs does not alter the conclusions drawn in -

Section 7.4 of the SQN Safety Evaluation Report (NUREG-0011). Therefore, they are not required to meet the underlying purpose of i specification 3.3.3.5, and their deletion from Tables 3.3-9 and 4.3-6 is acceptable.

The deletion of the unit 2 footnote for item 8 is purely an administrative change for clarity and completeness.

Environmental Impact Evaluation The proposed change request does not involve an unreviewed environmental question because operation of SQN units 1 and 2 in accordance with this change would not:

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1. Result in a significant increase in any adverse environmental impact previously evaluated in the Final Environmental Statement (FES) as modified by the Staff's testimony to the Atomic Safety and Licensing Board, supplements to the FES, Environmental Impact Appraisals, or in any decisions of the Atomic Safety and Licensing Board.

2. Result in a significant change in effluents or power levels.

3. Result in matters not previously reviewed in the licensing basis for SQN that may have a significant environmental impact.

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ENCLOSURE 3 l

l PROPOSED TECHNICAL SPECIFICATION CHANGE l

SEQUOYAH NUCLEAR PLANT UNITS 1 AND 2 DOCKET NOS. 50-327 AND 50-328 (TVA-SQN-TS-89-23)

DETERMINATION OF NO SIGNIFICANT HAZARDS CONSIDERATIONS 1

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ENCLOSURE 3 l

Significant Hazards Evaluation TVA has evaluated the proposed technical specification (TS) change and has determined that it does not represent a significant nazards consideration based on criteria established in 10 CFR 50.92(c). Operation of SQN in accordance with the proposed amendment will not:

(1) Involve a significant increase in the probability or consequences of an accident previously evaluated. The rod control system, as described in Final Safety Analysis Report (FSAR) Section 7.7, provides for reactor power modulation by manual or automatic control of full-length control rod banks. The RPI system provides a direct continuous readout of each control rod assemblies' position. This position indication is produced for each control assembly by a linear variable transformer. A rod bottom indication is also provided for each RPI channel.

The proposed change to the SQN TS is to delete the requirements for the remote rod bottom instrumentation. The bases for specification 3.3.3.5 state that the remote shutdown instrumentation is provided to achieve and maintain a plant shutdown from outside the control room. The SQN procedures that would be used for control room abandonment do not rely upon the remote rod bottom indicators to achieve'or maintain safe shutdown of the unit. Because the remote rod bottom indicators are not assumed to be the cause of a previously evaluated accident, their deletion from Tables.3.3-9 and 4.3-6 will not increase the probabilities of such accidents. Because the remote rod bottom indicators are not used to determine operator responses, their deletion will not alter plant responses to previously evaluated accidents, and the consequences of such accidents are not increased.

The deletion of the unit 2 footnote is an administrative change made for clarity and completeness, an6 es such, will not increase the probability or consequences of any previously evaluated accident.

(2) Create the possibility of a new or different kind of accident from any previously analyzed. As described above, the proposed change deletes instrumentation from Tables 3.3-9 and 4.3-6 that is not required or relied upon to achieve and maintain a plant shutdown from outside the main control room. No changes are being made to the rod control system. The system will continue to function as previously evaluated. Because the remote rod bottom indications are not currently relied upon or required, the plant response for cor trni room abandonment remains unchanged. The deletion of the unit 2 footnote is made for completeness and is administrative in nature.

Therefore, the proposed changes to Tables 3.3-9 and 4.3-9 do not create the possibility of a new or different kind of accident from any previously analyzed, t

(3) Involve a significant reduction in the margin of safety. The bases of specification 3.3.3.5 state that the remote shutdown instrumentation ensures the capability to permit shutdown, maintenance of hot standby conditions, and the potential for subsequent cold shutdown from outside the main control room. Because the remote rod bottom indicators are not currently relied upon in control abandonment or reactor trip response procedures, their deletion from Tables 3.3-9 and 4.3-6 does not impact the remote shutdown capabilities at SQN; and compliance with 10 CFR 50 General Design Criterion 19 is maintained, The rod bottom indicators are not discussed in FSAR Section 7.4 as being necessary equipment to achieve safe shutdown. .Their deletion from the TSs does not alter the i boration or residual heat removal systems required to ensure safe shutdown capabilities. As such, the conclusions drawn in Section 7.4

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of the SQN Safety Evaluation Report (NUREG-0011) are not changed, and .

compliance with Table 7-1 of the Standard Review Plan is maintained.

The unit 2 footnote deletion is administrative in nature and made for ,

clarity and completeness. Therefore, the proposed changes do not reduce the margin of safety.

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