ML19225B015
| ML19225B015 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear, Crane  |
| Issue date: | 06/28/1979 |
| From: | Capra R Office of Nuclear Reactor Regulation |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 7907230324 | |
| Download: ML19225B015 (7) | |
Text
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UNITED STATES
) *e NUCLEAR REGULATORY COMMISSION
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WASHINGTON, D. C. 20555 t
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JUN ' 81979 4
Docket No. 50-313 LICENSEE:
Arkansas Power & Light Company FACILITY:
Arkansas Nuclear One, Unit 1 (ANO-1)
SUBJECT:
SUMMARY
OF MEETING HELD ON JUNE 21, 1979 TO DISCUSS EMERGENCY FEEDWATER SYSTEM RELIABILITY FOR ANO-1 A meeting was held in Bethesda, Maryland on Jene 21,1979 with represent ives of Arkansas Power & Light Company (AP&L) and Franklin Research Center to dis-cuss two recent pump failures in the ANO-1 emergency feedwater (EFW) system.
A list of attendees is included as Enclosure 1.
Background
In light of the Three Mile Island, Unit 2 accident, the Commiss!cn confirmed, by Order dated May 17, 1979, AP&L's undertaking of a series of actions, both imediate and long-term, to increase the dapability and reliability of the plant to respond to various transient even.ts.
In addition, the Order con-firmed that ANO-1 would not be restarted untij the immediate actions had been accomplished and found acceptable by the Director, Office of Nuclear Reactor Regulation. These actions were completed by the licensee and reviewed by the staff and found acceptable. The Order was lifted on May 31, 1979. One of the immediate actions, called for in the Order, was to upgrade the timeli-ness and reliability of the EFW system.
Subsequent to the lifting of the Order, failures occurred to both of the ANO-1 EFW pumps. A meeting was held, at the request of the staff, to discuss the causes of the failures and to determine what actions by the licensee will be necessary to insure these failures do not reaccur.
_Di_s cus si on :
AP&L presented a discussion of the failures which occur' red on June 16 and 17, 1979 to the two EFW pumps. The first failure occurred to the motor-driven EFW pump on June 16. During the ANO-1 heat-up from cold shutdown, a spurious signal from the Steam line Break Instrumentation & Control (SL3IC) system resulted in an isolation of the secondary systems, including main feedwater.
As a result of this action, both EFW pumps received start signals.
Since the plant was still low in temperature, there was insufficient steam pressure to run the turbine-driven pump. The motor-driven pump started and ran for 26 minutes until an operator observed smoke coming from the pump end of the unit.
The motor-driven pump was secured.
Following an inspecticn of the pump, it was determined that a failure of the outboard journal bearing of the pump iv g[oi q uones wi
JUN 2 e 1979 Meeting Sumary had caused the malfunction. During the previous shutdown, the pump was overhauled as part of ANO-l's normal preventive maintenance program.
However, when the pump was reassembled, the bearing shims were installed improperly causing uneven load distribution on the bearing.
(Enclosure 2 is a drawing of the pump end of the motor-driven pump. Item #1 is the bearing which failed.) Following maintenance on the pump, the pump passed a routine one-hour surveillance test.
It appears that the damage to the bearing occurred during the surveillance test; however, seizure of the bearing occurred after securing the pump and the subsequent cooldown of the bearing.
The following day, June 17, a surveillance test was conducted on the turbine-driven pump. While securing the pump, following the test, the operator noted abnormal noise coming from the turbine. He also noted that the inboard journal bearing of the turbine was running hotter than no rmal. He also discovered that the vent hole for the lubricating oil sight glass was clogged with dirt. Upon unclogging the vent hole, the oil sight glass level dropped cut of sight, indicating insufficient oil in the reservoir for proper lubrication of the bearing.
Inspection of the bearing showed it was wiped; it was subsequently replaced. (Enclosure 3 is a drawing of the turbine end of the turbine-driven pump.
Item #4 is the bearing which failed.)
During the discussion, a history of the two EFW pumps was presented by AP&L, which revealed the following information:
TURBINE-DRIVEN MOTOR-DRIVEN PUMP PUMP Total number of starts:
36 56 Total number cf surveillance tests:
20 21 Total hcurs of operation:
31.5 35 Longest run oeriod (hours):
4 6
Total number of failures:
2*
1**
- - The first mal function occurred on January 22. 1977. when the opoosite turbine journal bearing (outboard journal - item #24 on Enclosure
- 3) failed.
LER 77-03 refers to that failure. The second failure was the one on June 17, 1979.
- - The only failure of this pump occurred on June 16, 1979.
413 10E
Meeting Summary g 2 8 1979 The remainder of the meeting centered around staff concerns about the reliability of the EFW pumps and the actions which should be taken by AP&L to preclude a recccurrance of similar failures. The staff raised the concern about the small number of hours that the pumps had been operated.
It was felt that for a system to be reliable, it must be operated more frequently and for longer periods of time.
It was pointed out that the ANO-1 auxiliary feedwater pump (startup pump) is also a standby pump (as are the EFW pumps); however, the auxiliary feedwater pump is placed in operation during every startup and shutdown of the unit.
Often this pump is run for periods in excess of 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> at a time, and has shown excellent reliability.
AP&L discussed the following actions it was taking to improve the relia-bility of the EFW system and to insure that similar failures do not reoccur:
(1) Maintenance procedures are being reviewed to insure that personnel perfoming the maintenance are provided with clear and unambiguous steps to follow.
(The lack of sufficient detail in the procedure used to overhaul the motor-driven pump may have led to the improper installation of the bearing shims.)
(2) Maintenance procedures are being reviewed by AP&L's Quality Assurance Section to insure that the procedures contain the proper quality control, hold-points, inspection requirements, and testing requirements.
(3) As a short-term solution to the improper venting of the oil reservoir sight glass, AP&L has loosened the bearing vent caps to insure proper venting. As a pemanent solution, AP&L will either modify the vent line with a goose-neck arrangement or will provide a more positive oil level indication such as a dip-stick.
(4) AP&L is reviewing the surveillance test requirements for these pumps to see if the procedures could be modified to provide a more positive detemination of the status of the equipment. Examples being con-sidered are: (a) longer run times for the tests; (b) conduct the test, secure the equipment, start the equipment again following cooldown of the components; (c) collect additional infomation during the test such as bearing oil temperature and vibration information.
During the course of the meeting, AP&L was notified by phone that at about 1:30 p.m. on June 21, 1979, the turbine-driven pump had experienced another problem during a post-maintenance surveillance test.
This failure was related to the turbine tripping on overspeed due to a malfunction of the governor.
==
Conclusion:==
The staff proposed and AP&L committed to perform an endurance test of both EFW pumps, following any corrective maintenance which was being performed on the pumps at the present time. The test procedure will be written by AP&L and a 413 103
M 2 8 $9 Meeting Summary
_4 copy submitted to the staff for review. The test should be run as soon as possible and should include the following aspects:
(1) Total run time for each pump should be at least 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> and preferably 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
(2) Both pumps will be tested; however, they will not be dono concurrently.
(3) The test should be conducted under the same (or as close as possible) conditions as the pumps would experience if called upon to feed the steam generators for an extended period of time, ie., flow rate and discharge pressure.
(4) The pump and turbine vendors should be contacted prior to the test in order to factor their recommendations into the test procedure.
(5) The test procedure should have definite acceptance criteria specified.
(6) These tests should be witnessed by a member of the NRC staff (IE).
(7) The test procedure should specify the parameters that will be measured and recorded during the test.
(8) The test will be conducted on a not-to-inter'ere-basis with the scheduled plant startup.
M d. Cy^ ^
Robert A. Capra, B&W Project Manager Bulletins & Orders Task Force Division of Project Management
Enclosures:
1.
List of Attendees 2.
Drawing - Motor-driven pump 3.
Drawing - Turbine-driven pump kl)
ENCLOSURE 1 LIST OF ATTENDEES MEETING HELD JUNE 21,1979 - EFw SYSTEM FOR ANO-1 Arkansas Power & Light Co.
Don Rueter Director, Tech. & Lic. servicer Rick Lane Manager, Mechanical Engineering Basil Baker Operations Superintendant J. P. O'Hanlon General Manager William Cavanaugh Vice-President, Generation &
Construction Franklin Research Center Harry Rippel E
Guy Vissing Projecs Mgr., ANO-1, 00R H. A. Wilber Inspection & Enforcement Headquarters R. W. Reid Chief, ORRranch #4, 00R P. R. Matthews B&O Task Force T. Novak B&O Task Force Kevin Mahan Opertter Licensing Branch, DPM George Johnson Engineering Branch, 00R James Conway Quality Assurance, DPM Walter P. Haass Quality Assurance Branch Chief, DPM E. V. Imbro Reactor Safety Branch, DOR R. A. Capra B&O Task Force k$J
.s ENCLOSURE 2 Step 2 Q
Set dial indicator so that tip rests against the end of the shaft. (Plain Bearing End).
v-Step 3 Push rotor so that faces "A"
and "B" are metal to metal. Set dial indicator at Zero.
Step 4 Tighten end cover "E"
and check dial indicator. This reading equals the gap between "A" and "B". Select the number of shims "C" required to obtain a gap of
.002" to.005" between "A" and "B".
Step 5 Remove end cover boiting, bearing housing lock r'ut, lock washer, distance sleeve, and inrust bearing. Install shims "C".
Step 6 Repeat the abcve procedure until the gap between "A" and "B" equals.002" to
.005
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