ML20077K174
| ML20077K174 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 07/29/1991 |
| From: | Joshua Wilson TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 91-10, NUDOCS 9108070068 | |
| Download: ML20077K174 (5) | |
Text
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-o IUA ww.ze va, w. > o% 0 3 zo m < m,.c --. um n m Jack L wason werm-xt: a n e w,w n o July 29, 1991 U.S. Nuclear Regulatory Commission ATTN:
Document Control-Desk Washington, D.C.
20555 Centlemen:
In the Matter of
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Docket Nos. 50-327 Tennessee Valley Authc rity
)
50-328 SEQUOYAH NUCLEAR PLANT (SQN)
FACILITY OPERATING LICENSES DPR-77 AND 79 - SPECIAL REPORT 91 10 CFR 50. APPENDIX R, IN ACCORDANCE L'ITH LICENSE CONDITIONS 2.C.13.C AND 2.H The enclosed special report provides details regarding a condition that was identified as resulting in noncompliance with 10 CFR 50, Appendix R, requirements. This condition involved an oil leak in Unit I reactor
. coolant pump No. I and the inability of the oil collection system to i
collect-all of the lube oil-leakage. This condition was initially reported by telephone notification at 1400 Eastern daylight time on l
July 13, 1991, and confirmed by facsimile on the next working day in l
accordance with License Condition 2.H of the Unit 2 Facility Operating License.
This condition is applicable to Unit 1 as detailed in the enclosed report. This follow-up report is being submitted in accordance with Unit 2 License Condition 2.H.
If you have any questions concerning this submittal, please telephone M. A. Cooper at (615) 843-8422.
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Very truly yours.
TENNESSEE VALLEY AUTHORITY
.50 J
L. Wilson iclosure cc:
See page 2
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9108070068 910729 1
I PDR ADOCK 05000327 PIMi i
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- j U.S. Nuclear' Regulatory Commission July 29,-1991 J
-c e (Enclosute):
Ms. S. C. Black, Deputy Director Project Directorate II-4 U.S. Nuclear Regulatory Commission One White' Flint, North.
- 11555 Rockville Pike Rockville, Maryland' 20852 Mr. D. E. LaBarge, Project Manager
- U.S. Nuclear R gulatory Commission One White Flint, North 11555 Rockville Pike Rockville, Maryland. 20852 NRC Resident Inspector-Sequoyah Nuclear Plant 2600-Igou Ferry Road Soddy-Daisy, Tennessee 37379 Mr.
B..A. Wilson, Project Chief U.S.-Nuclear Regulatory Commission Region II 101-Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 W
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ENCLOSURE 14-Day Follow-Up Report' Special Report 91-10
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Description-of Condition On July 10,-1991,-with Unit 1 operating in Mode 1 at 100 percent power, 578 degrees, and 2,235 pounds per square inch gauge, the Unit I reactor coolant pump (RCP) No. I oil level abnormal annunciator'was acknowledged.
A
-maintenance team was-established to enter-containment to add oil to the No. 1-RCP. The team reported observation of oil on the concrete containment floor below the RCP. Another observation was that oil was leaking by the oil collection pan lip where the lip fits up to the motor frame. The total amount of oil on the floor was estimated to-be between five and seven gallons.
The maintenance team did not clean up the oil at the time of discovery because of ALAF.A (as low as rbasonably achievable) concerns.
Nuclear Engineering =(NE) prepared an engineering evaluation for the situation stating that the
- probability of the occurrence of a fire resulting f rom the existing cor.dition that would affect safe shutdown of the unit'was-very low.
If a fire either started in the RCP or reached the RCP, the installed fire protection detection and suppression system would adequately. ensure the identification and suppression of the fire and the unit eculd safely operate until the next
-refueling outage, which is scheduled for the fall of 1991.
On July 13, 1991, a problem event' report was prepared describing the observations.
In'10 CFR 50, Appendix R, Section III, paragraph 0, it states
[
.that the RCP shall be= equipped with an oil collection system and that this system shall-be capable of collecting tube oil from all potential pressurized e
and nonpressurized leakage sites.
SQN's Unit 2 License Condition 2.C.13.c l-
~ states that TVA shall comply with Section III, paragraph.D.
From a review of L
the observations, it was. determined that the installed capability of the L
collection system was in noncompliance _vith Section III, paragraph 0, of Appendix R-to 10 CFR 50, and therefore constituted a violation of SQN's Unit 2 License Condition 2..C.13.c.
Accordingly, the situation was repocted to NRC-by l-
. telephone at-1400-Eastern daylight-time on July 13 1991, in accordance with Unit 2 License Condition 2.H-and confirmed-by a facsimile on the next working day, Monday, July 15, 1991.
.Cause of the Condition The area.where-the RCP motor housing and the oil lift system collection pan fit together is not a-machined. surface-type-fit. A note on the vendor 3
drawingsurequires that caulking be applied to the area between the. mating surfaces.
It was determined that the caulking is not applied to this area r
and as a result, the lube oil is-leaking down onto the concrete floor below
-the RCP.
Based on an investigation conducted to date, it has.been concluded.
that the-caulking requirement was'not implemented on the initial installation nor_was the vendor drawing note addressed in the maintenance' instructions used for the1 removal and replacement of the RCP motors since-initial installation.
Although the exact'cause of these errors could not be definitively established, the failure to incorporate this requirement is presumed to have been an oversight possibly as a result of unclear guidance in both the vendor and TVA documents.
+....,
Analysis of-Condition At this-time, the No. 1 RCP'on Unit ifis the only;known RCP among both units to be experiencing a leak. The orientation of the mating surfaces for the other seven RCPa is unknown.
For the present condition of the oilLleak on RCP No.1, it is_ conservatively estimated that 50 percent of the leaking oil is
- being directed-to the auxiliary reactor building sump and the remaining
?50 percent is being spilled in the general area of the No. 1 RCP platform.
L(This percentage was based on estimates of the size and depth of the existing-oil around the No. 1 RCP on Unit 1.) While this is an undesirable condition, it.is not considered'to present'a safety concern for the following reasons.-
1.
The catastrophic failure of the lube oil system is not' expected under any circumstances because the system has'been designed and installed to seismic Category 1 requirements, and there are no indications that the existing deficiency on the No. 1 RCP on Unit 1 degrades that qualification.
L 2.- The leak rate of the oil onto the floor of the containment is estimated to be-approximately 1.5 gallons-per month.--This is based on the amount of-oil added, the amotnt estimated to be Don the containment floor,_and the
. time since_the last inspection.
3.
Surveillance Instruction (SI) 137.1, " Reactor Coolant System Unidentified Leakage Measurement,"' requires that the sump for the oil collection system be monitored and pumped down to the extent pcssible on'a shiftly basis.
This would indicate any serious leakage p.ovlem from any RCP and ensures that adequate; volume exists to collect the majority of oil resulting from a catastrophic fa!1ure of.the RCP lube oil system, Additionally, it would be' expected that the floor drain system:would collect a portion of the oil
. spilling to the floor.
4.
The design of SQN is such that the presence of up to'100 gallons of oil in the area of the RCPs.is acceptable because the oil would not come into contact with hot piping and ignition sources. A review of the location of l-
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the spilled oil in. relation to the hot piping and other potential ignition sources indicates that this would still be the case.
In summary,_ continued operation is considered acceptable until the next l-refueling outage.
('
Corrective Action
(-
TVA's Maintenance Instruction 0-MI-EMM-68-002.3, " Removal and Replacement of Reactor Coolant Pump Motor,"_ which contains instructions for the removal and l!
' replacement of an RCP and all'its appendages, will be revised to include the
- caulking of the subject orea to direct the oil to the proper collection point.
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- TVA -has prepared an engineering evaluation -stating - that continued operation is justified on the condition _that the oil leak does not exceed 100 gallons.
In its present condition, it has-been conservatively estimated that 50 percent of the oil leaking from the RCP is dripping onto the floor.
Therefore, more than 200 gallons would have to be added to the RCP before the condition would l
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- represent a threat-to the operation and exceed _the fire suppression capabilities in-the area.
Sequoyah Standard-Practice SQM54, " Reactor Coolant Pump Motor Lubricating 011-Maintenance-Program - DPM No. SEQ 80M14," will bei Trevised by August 19. 1991, to_ direct NE to perform an engineering evaluation on any addition of oil to any RCP.
During_the next refueling outageIfor the' respective ~ unit, each RCP and.its associated oil lift system will_be inspected and evaluated to further assess the extent and cause of the condition. The RCP oil collection mating surfaces will be caul.ked and/or the system will be modified as required during the next refuelin; outage.-
Crumitments 1.
Maintenance Procedure 0-MI-EMM-68-002.3 will be revised by October 4,1991, to address caulking the area between the RCP motor I
housing and the oil lift system collection pan lip.
-2.-
Each RCP oil collection _ mating surface will be caulked as required _and/or l
the system will be modified during the next-refueling outage for each unit.
3.
During the-next refueling outage for the respective unit, each RCP and its associated oil collection and: lift system will-be inspected and evaluated to-further' assess the-extent-and cause of conditions.
4.
SQM54 will be revised by August 19, 1991,- to direct NE to perform an-engineering _ evaluation on any addition of oil to any RCP.
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