ML20246F498
| ML20246F498 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 05/04/1989 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20246F495 | List: |
| References | |
| NUDOCS 8905120265 | |
| Download: ML20246F498 (5) | |
Text
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UNITED STATES p,
NUCLEAR REGULATORY COMMISSION 5
4j WASHINGTON, D C.20555 g.... f ENCLOSURE 3 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO.113 TO FACILITY OPERATING LICENSE NO. DPR-77 AND AMENDMENT NO.103 TO FACILITY OPERATING LICENSE NO. DPR-79 TENNESSEE VALLEY AUTHORITY SEQUOYAH NUCLEAR PLANT, UNITS 1 AND 2 DOCKET NOS. 50-327 AND 50-328
1.0 INTRODUCTION
By submittal dated May 2, 1989, the Tennessee Valley Authority (TVA) proposed Specifications (TS)yah Nuclear Plant (SQN), Units 1 and 2 Technical to modify the Sequo to revise Table 3.3-9, " Remote Shutdown Monitoring Instrumentation," and Table 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 on Table 4.2-6 (Unit 2) is also proposed to be deleted.
TVA has determined that the remote rod bottom indications currently required by TS Limiting Condition for Operation (LCO) 3.3.3.5 are not needed to achieve and maintain the SQN units in a safe shutdown condition.
The need for these proposed TS changes to be processed by the staff on an emergency basis was due to the fact that the Unit I full-length control rod E-13 was declared inoperable because of voltage fluctuations in the associated analog rod position indication (RPI) instrument channel. SQN, Unit 1 is currently at approximately 100 percent power. Since the remote rod bottom indication has been declared inoperable, SQN, Unit I has entered TS LC0 3.3.3.5, and the instrumentation must be repaired within seven days or the unit must shutdown. As stated above, TVA has determined that this instrumentation is not needed for remote safe shutdown; therefore, rather than force the shutdown of Unit I to effect repairs, TVA has submitted the proposed TS changes to delete J
the Operability and Surveillance Requirements for this equipment.
2.0 EVALUATION As described above, TVA has proposed to delete from TS Table 3.3-9, Item 8, l
" Instrument, Full Length Control Rod Position Limit Switches" and its associated Readout Location, Measurement Range, and Minimum Channels Operable.
TVA has also proposed to delete Item 8 from TS Table 4.3-6, the Instrument, Channel Check, and Channel Calibration which are the TS Surveillance Requirements for the same instrument.
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2 As TVA has described in their submittal referenced above, the purpose of the remote shutdown instrumentation h, to ensure sufficient capability to achieve and maintain a unit in a safe shutdown condition from outside the main control l
room. TVA has determined that the rod bottom indications located in the f
auxiliary instrument room (racks R41-44) are not required to achieve this
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purpose.
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i Abnormal Operating Instruction (A0I) 27, " Control Room Inaccessibility,"
provides procedural guidance to SQN operations personnel regarding appropriate actions to be taken in the event that the main control room must be abandoned.
Part A of A01-27 specifically addresses the appropriate actions if either or both units are at power.
Imediate 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 Instructions (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 bottom lights in the main control room are on, the reactor trip breakers are open, the rod position indication (RPI) instruments indicate zero steps, and the neutron flux is decreasing. The combination of all these indications provides assurance that the reactor has been shutdown.
If the verification of the above four steps indicates that the reactor has not tripped, the operator is instructed by procedure to initiate boration to the core.
Emergency boration is also initiated for the case in which any control rod is not verified to be fully inserted.
The procedurdl 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.
A01-27 also provides the guidance for maintaining the unit in hot standby and i
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 provide a status of 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 af ter the L
unit is tripped. Should any anomalies arise, boration control is still available outside the control room.
In summary, TVA has concluded that the rod bottom indicators located in the auxiliary instrument room are not required or used to achieve or maintain the SQN units shutdown from outside the main control room.
TVA has stated that shutdown is achieved and verified from the main control room before it is abandoned. The staff has evaluated the proposed TS changes and has found that the rod bottom indicators are not referenced in Section 7.4 of the SQN Final Safety Analysis Report (FSAR) as equipment required to achieve and maintain safe shutdown and, therefore, are not required equipment needed to mitigate the SQN FSAR Chapter 15 accidents. As such, their deletion from the TS does not
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alter the conclusio'ns of the SQN Safety Evaluation Report (NUREG-0011) and the rod bottom indicators are, therefore, not required to meet the intent of TS 3.3.3.5.
The staff has concluded that the proposed TS deletions for remote rod bottom indication from Tables 3.3-9 and 4.3-6 is acceptable.
The staff also notes that TVA has proposed to delete an expired footnote on TS Table 4.3-6 for purposes of clarity and completeness.
The staff has evaluated this proposed deletion and has concluded that this change is purely administrative in nature, adds clarity to TS Table 4.3-6, in no way affects safety, and is, therefore, ccceptable.
- 3. 0 FINAL NO SIGNIFICANT HAZARDS CONSIDERATION DETERMINATION The State of Tennessee was informed by telephone on May 3, 1989, of the staff's no significant hazards consideration determination.
The State contact has no comments on the determination.
TVA has evaluated the proposed technical specification (TS) change and nas determined that it does not represent a significant hazards 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 p oposed 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 rou bottom indicators are not dssumed 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, and as such, will not increase the probability or consequences of any previously evaluated accident.
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4 (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 f
'is not required or relied upon to achieve and maintain a plant shutdown from outside the main control room.
No changes are
-i being made to the. rod control system.
The system will continue j
to function as previously evaluated.. Because the remote rod bottom indicators are not currently relied upon'or required, the 1
plant response for control room abandonment. remains. unchanged.
l 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 4.3-6 do.not create the possibility of a new or' Ldifferent kind of accident from any previously' analyzed..
-(3)
Involve a significant reduction in the margin of safety. The bases of Specification 3.3.3.5 state that the remote. shutdown u
f 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 [ room] 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 boration or residual heat removal systems required to ensure safe shutdown capabilities. As such, the conclusions drawn in Section 7.4 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.
The staff has reviewed TVA's evaluation and agrees that the proposed TS changes do not represent a significant hazards consideration.
4.0 FINDINGS OF EMERGENCY WARRANTING AN AMENDMENT WITHOUT NOTICE The licensee's application for the TS change has been timely.
The licensee stated that on April 29, 1989, the rod bottom circuitry for Unit I was declared inoperable because of voltage fluctuations in the analog RPI instrument channel.. Failure to have remote shutdown instrumentation for full-length control rod position indication resulting from this unanticipated failure of the RPI would cause a shutdown of Sequoyah, Unit 1 as currently required by 1
The staff concurs that failure to grant the proposed changes in a timely manner would cause a shutdown of Sequoyah, Unit 1.
We find that the licensee could not reasonably have avoided the situation, that the licensee has responded in a timely manner, and has not delayed its application to take advantage of the i
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i Emergency License Amendments provision of 10 CFR 50.91.
Furthermore, sin'ce the staff agrees that the remote rod bottom indicators are not required to meet the underlying purpose of TS 3.3.3.5 and the TS are the same for both units, it is desirable to change both sets of TS at the same time. Accordingly, the staff concludes that the licensee has satisfied the requirements of 10 CFR 50.91(a)(5), and that a valid emergency exists.
5.0 ENVIRONMENTAL CONSIDERATION
These amendments involve changes to a requirement with respect to the installation or use of a facility component located within the restricted areas as defined in 10 CFR Part 20 and changes to the surveillance requirements. The staff has determined that amendments involve no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has made a final no significant hazards consideration finding with respect to these amendments.
Accordingly, the amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(C)(9).
Pursuant to 10 CFR 51.22(b),
neither environmental impact statement nor environmental assessment needs to be prepared in connection with the issuance of the amendments.
6.0 CONCLUSION
We have concluded, based on the considerations discussed above, that:
(1)the amendments do not (a) significantly increase the probability or consequences of an accident previously evaluated, (b) create the possibility)or a new orsignificantly different kind of accident from any previously evaluated or, (c reduce a safety margin and, therefore, the amendments do not involve significant hazards consideration; (2) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (3) such activities will be conducted in compliance with the Commission's regulations, and the issuance of these amendments will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor:
T. Rotella Dated May 4, 1989 1
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