ML20153G003
| ML20153G003 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 05/05/1988 |
| From: | Gridley R TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| NUDOCS 8805110113 | |
| Download: ML20153G003 (7) | |
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TENNESSEE VALLEY AUTHORITY CHATTANOOGA. TENNESSEE 37401 SN 157G Lookout Place MAY 05198B U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Hashington, D.C.
20555 Gentlemen:
In the Matter of
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Docket Nos. 50-327 Tennessee Valley Authority
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50-328 SEQUOYAH NUCLEAR PLANT (SQN) - NRC INSPECTION REPORT NOS. 50-327/88-17 AND 50-328/88 RESPONSE TO UNRESOLVED ITEM (URI) 50-327, -328/88-17-02 j
Enclosed is TVA's response to F. R. McCoy's letter to S. A. White dated l
March 24, 1988, that transmitted URI 50-327, -328/88 17-02.
The change in due date to May 5, 1988, was discussed with F. R. McCoy of NRC and G. B. Kirk of j
TVA on April 21, 1988.
1 provide: TVA's response to the unresolved item.
contains a list of commitments contained in this submittal.
If you have any questions,, ! ase telephone M. R. Harding at (615) 870-6422.
Very truly yours, TENMP",SEE V EY AUTHORITY l
k R. Gridley, Director Nuclear Licensing and Regulatory Affairs I
Enclosures cc: See page 2
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An Equal Opportunity Employer
O I 4 U.S. Nuclear Regulatory Commission _
h440f U51988L cc (Enclosures):
Mr. K. P. Barr, Acting Assistant Director for Inspection Programs TVA Projects Division U.S. Nuclear Regulatory Commission Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 Mr. G. G. Zech, Assistant Director for Projects TVA Projects Division U.S. Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852 J
Sequoyah Resident Inspector Sequoyah Nuclear Plant 2600 Igou Ferry Road Soddy Daisy, Tennessee 37379 I
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ENCLOSURE 1 Unresolved Item 50-327.-328/88-17-02 "Shift Logs, Decords, and Turnover Status Lists The inspectors reviewed the shift supervisor (SS), shift technical advisor (STA), and reactor operator (RO) logs and deterinined that the logs were completed in accordance with administrative requirements.
The inspectors ensured that entries were legible; errors were corrected, initialed and dated; logbook entries adequately reflected plant status; significant operational events and/or unusual parameters were recorded; and entry into or exit from TS Limiting Conditions for Operation (LCO) were recorded promptly.
Turnover status cNchlists for R0s contained sufficient required information and indicated plant status parameters, system alignments, and abnormalities.
The following logs were reviewed:
Night Order Log System Status Log Configuration Control Log Key Log Temporary Alteration (TACF) Log During this inspection, it was determined that the below listed Limiting i
C.onditions for Operation (LCO) were unknowingly entered, not suitably controlled, and not appropriately logged:
(1) On February 26, 1988, at 12:38 p.m., the licensee made inoperable one train of the component cooling system (CCS) without recognizing it or entering TS LCO 3.7.3 until approximately eight hours later.
(2) On February 15, 1988, at 11:40 a.m., the licensee made inoperable both trains of L;ontrol Room Emergency Ventilation System (CREVS) without recognizing it or entering TS LCO 3.0.5 until 12:37 a.m. the next day.
(3) On February 9, 1988, at 12:30 a.m., the licensee failed to meet the time constraints of Surveillance Requirement 4.4.6.2.1.d without recc,gnizing it or entering TS LCO 3.4.6.2.b until 5:05 a.n.
This issue is uder review and is identified as Unresolved Item (URI) 50-327,-328/88-17-02."
Root Cause (Example 1) 4 On February 26, 1988, at 12:28 p.m. eastern standard time (EST), the CCS pump 2A-A was removed from service for a periodic oil change under Preventative Maintenance Instruction (PM) 1755-070.
With the 2A-A pump out of service, only the 2B-B and C-S pumps, which are both powered from train "B" power, remained in service.
Technical Specification (TS) 3.7.3 requires two independent component cooling water loops to be operable in modes 1 through 4.
At the time pump 2A-A was removed from service, the TS action statement was not entered; however, it was determir.ad later that the two remaining operable pumps (2B-B and C-S) did not satisfy the TS requirement.
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. Before this event, a hold order (2-88-226) was coordinated with and approved by the assistant shift supervisor (unit 2 senior reactor operator [SR03) to tag the 2A-A CCS pump out of service.
The 2A-A pump was then removed from service with no coordination or approval from the shift supervisor.
- Further, the hold order did not receive a review from the work control group before tagging the pump out of service because the hold order was not part of the PM 1755-070 work package.
The unit 2 SR0 was consciously aware that two independent CCS loops were required when the 2A-A pump was removed from service.
However, the SR0 considered having the 28-B pump mechanically aligned to train "A" equipment, and the C-S pump aligned to train "B" equipment as meeting the TS requirement for two independent loops.
The independence of the electrical power sources feeding the two remaining pumps was not considered when making the determination that two independent loops were still evallable.
Two mechanically aligned independent loops were still avallaole; however, the pumps were not electrically independent.
A shift turnover occurred at approximately 3:52 p.m. EST with a new untt 2 SR0 and shift supervisor coming on shift.
Shortly after the shift turnover, the oncoming shift supervisor noted that the CCS 2A-A pump was out of service and the remaining two operable pumps (28-B and C-S) were both powered from train B power. He considered this to be a potential problem with respect to meeting the TS requirement of the two ',ndependent loops and consulted with the STAS.
After reviewing the condition, the STAS reported to the shif t supervisor, who' subsequently made the determination, that the TS requirements were not satisfied because the two remaining operable pumps were not electrically independent. At approximately 8 p.m. EST, the TS action statement was entered with the action time clock retroactive to 12:28 p.m. EST, when the 2A-A pump was removed from service.
The TS action requires that, with only one CCS loop operable, at least two operable loops be restored within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or be in at least hot standby within six hours and in cold shutdown (mode 5) within the next 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.
Because this action w&s complied witn, no TS was violated.
The 2A-A CCS pump was returned to operable status at approximately 10:12 p.m. EST.
Corrective Action 1.
Plant Operations Review Staff (PORS) will issue a formal interpretation to better define what constitutes two independent CCS loops and what restrictions apply.
2.
Additional management emphasis stressing the importance of assessing overall plant status and communications before removing equipment from service was discussed with Operations personnr:1 during meetings conducted on March 14-15, 1988.
_ Root Cause (Exampla 2)
The event was caused by an inadequate review of the applicable TS before removing a dicsel generator (D/G) from service.
The sh',ft supervisor stated he was cognizant that removing D/G 1A-1 from service would make train A of CREVS inoperable; however,.he did not confirm the TS required action that must be taken when both trains of CREVS are inoperable.
The fact that both trains of CREVS had been incperable almost continually from July 1987 to January 1988, wnlle SQN was in mode 5 (reference LER SQRO-50-327/87039), most likely contributed to the shif t supervisor's belief that it was acceptable to have both trains of CREVS out of service.
1 A contributing cause of this event was inadequate procedures.
The procedures that were used to remove 0/Gs from service for routine testing (i.e., the System Operating Instruction (501] 82 series of instructions) did not contain the necetsary warni gs and precautions.
Specifically, the section of the subject 501s that is used for manually rolling the 0/Gs should have cautioned personnel that performance of those instructions would cause the D/G to become inoperable. Additional precautions should have been provided to warn of the.
potential for entering LCO 3.0.5 if other trained equipment was out of service.
Corrective Action As immediate corrective action, SQN Operations personnel placed D/G 1A-A back in service thereby returning train A of CREVS to operable status.
As a result, LCO 3.0.5 was exited at 12:37 a.m. EST on February 16, 1988.
TVA has recently established a work control group at SQN.
The work control group, which is composed of SR0s and reactor operators (R0s), has been tasked with assisting the control room shift crew by determining the impact of work activities on the plant.
This is accomplished by reviewing work requests, screening Surveillance Instruction (SI) packages that could affect plant operation, and preparing hold orders.
Establishment of this work control group has reduced the amunt of activt ty in the main control room and allowed the shift supervisor to focus more attention on his primary function of safely operating the plant.
In addition, the procedures that are used to remove 0/Gs from service (i.e., the 50I-82 series of instructions) have been revised to include caution statements warning that performance of certain steps in these instructions will cause a D/G to become inoperable.
These caution statements specifically address the potential of causing other equipment or systems to be inoperable when 0/Gs are taken out of service.
As a result of this and other events that occurred at SQN during the interval from January 14 to March 9, 1988, TVA has implemented corrective actions (in addition to those described above) that should prevent the recurrence of this event. These additional recurrence controls are as follows:
Administrative controls have been eetablished to limit the interchanging of plant operators from a cold shutdown unit to an operating unit.
As a result, SQN operators who may have become accustomed to plant operation in mode 5 will not arbitrarily be placed in situations tnat could require significantly different actions from those that would be taken on a cold shutdown unit.
Administrative Instruction (AI) 30, "Nuclear Plant Conduct of Operation,"
has been revised to increase that level of communication among operators by specifying interface requirements that must be satisfied when major equipment (e.g., the 0/Gs) is taken out of service.
Signs emphastaing plant operating mode have been placed in the n:aln 1
control room and auxiliary equipment room.
Training on the above described change to AI-30 has been performed.
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Scenarios emphasizing the use of TSs will be incorporated into the opert, tor simulator training program before restart (mode 2) of unit 1.
Note:
The actual time of the event was 11:40 p.m. not 11:40 a.m., as shown in the NRC Inspection Report.
Root Cause (Example 3)
This event was caused by Operations personnel not initiating the performance of SI-137.2, "Reactor Coolant System Water Inventory," untti just before the time it should have been completed. Once the SI was initiated, complications with obtaining a steam generator liquid sample extended the completion of the subject SI beyond the time interval allowed by the TS LCO. A contributing cause of this event was the operattonal activity level in the main control room resulting from a recovery of a; engineered safety feature actuation that had previously occurred.
The reew ery from this event diverted the attention of Operations personnel from the routine performance of SI-137.2.
Corrective Action As immediate corrective action, Chemistry personnel completed Part C of SI-137.2 and the action statement was exited at 8:59 a.m. EST on February 9, 1988.
To prevent recurrence of this event, Operations personnel,
have been instructed to allow sufficient time to complete SI-137.2 without entering the 25-percent extension allowed by TS 4.0.2.
In addition, TVA has revised SI-137.2.
SI-137.2 no longer controls the starting time of the steam generator sampling. A new procedure (SI-137.5) has been written to cover leak rate determination.
This should allow adequate time and preclude recurrence of this event.
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ENCLOSURE 2 l
List of Commitments l
1.
P0RS will issue a formal interpretation to better define what constitutes l
two independent CCS loops and what restrictions apply.
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Scenarios emphasizing the use of TSs will be incorporated into the operator simulator training program before restart (mode 2) of unit 1.
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