ML19341B195
| ML19341B195 | |
| Person / Time | |
|---|---|
| Site: | Grand Gulf  |
| Issue date: | 01/23/1981 |
| From: | Mcgaughy J MISSISSIPPI POWER & LIGHT CO. |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, AECM-81-43, NUDOCS 8101300424 | |
| Download: ML19341B195 (5) | |
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MISSISSIPPI POWER & LIGHT COMPANY Helping Build Afississippi P. O. B O X 16 40 J AC K S O N. MIS SIS SIP PI 39205 TuSf,aNEd'd*
January 23, 1981 Office of Inspection & Enforcement U. S. Nuclear Regulatory Commission Region II 101 Marietta Street, N.W.
Suite 3100 Atlanta, Georgia 30303 Attention: Mr. J. P. O'Reilly, Director
Dear Mr. O'Reilly:
SUBJECT:
Grand Gulf Nuclear Station Units 1 and 2 Docket Nos. 50-416/417 File 0260/15525/15526 PRD-81/02, Status Report No. 1, RHR Pump Damage AECM-81/43 On January 16, 1981, Mississippi Power & Light Company noti-fied Mr. M. Hunt of the NRC of a Potentially Reportable Deficiency (PRD) at the Grand Gulf Nuclear Station (GGNS) construction site.
This deficiency concerns the damage to the RHR "B" Pump during construction testing.
Investigative activities into this discrepancy by the con-structor to determine the extensiveness of the evaluation and re-pair are in progress; however, reportabi'lity of the discrepancy under the provisions of 10CFR50.55(e) cannot be determined until information is obtained from the pump manufacturer.
A status report is attached. We expect to establish reporta-bility and provide a final report by August 27, 1981.
Yours truly, g J. P. McGaughy, Jr.
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Attachment iI cc: See page 2 u 4AT
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O MISSISSIPPI POWER & LIGHT COMPANY Mr. J. P. O'Reilly AECM-81/43 NRC Page 2 cc:
Mr. N. L. Stampley Mr. R. B. McGehee Mr. T. 3. Conner Mr. Victor Stello, Director Division of Inspection & Enforcement U. S. Nuclear Regulatory Co= mission Washington, D.C. 20555 Mr. G. B. Taylor South Miss. Electric Power Association P. O. Box 1589 Hattiesburg, MS 39401
Attachm:nt to AECM-81/43 Page 1 of 3 STATUS REPORT NO. 1 TO PRD-81/02 I.
Description of the Deficiency The RHR "B" pump had been run approximately 138 hours0.0016 days <br />0.0383 hours <br />2.281746e-4 weeks <br />5.2509e-5 months <br /> prior to 12/08/80. The pump had been started numerous times with no his-tory of problems. On 12/08/80 the pump was started and ran under full flow for approximately 15 hours1.736111e-4 days <br />0.00417 hours <br />2.480159e-5 weeks <br />5.7075e-6 months <br />. Water was being circulated thru the three (3) RHR pumps, "A",
"B", and "C",
to heat the water in the reactor pressure vessel to a minimum temperature of 160 F prior to the Reactor Pressure Vessel System hydrostatic test.
On 12,09/80, the Condensate System had been utilized to fill the reactor. The RPV was filled and the vessel isolated from the Con-densate System with valves B21 F065 A and B.
One or both of the F065 valves were leaking since constant flow existed from the 0" vent line at the top of the vessel head. While preparing to secure one condensate and one booster pump, the N21 F003 valve was throttled in the closed direction. When valve N21 F003 was throttled closed, leakage thru the F065 A and B valves increased, thereby increasing pressure in the RPV. As the system became solid, the leakage from the condensate system with the pu=ps running resulted in a pressure spike in the reactor and RHR system of approximately 520 PSI. The pressure spike occurred at approximately 5:15 a.m. on 12/09/80.
RHR "B" pu=p was i= mediately throttled back to approximately 1300 gal / min.
The mini =um flow rate of this pump is 1000 gal / min.
At approximately 6:00 a.m., vibration data was taken on the pump and noted to be within tolerance. At approximately 10:00 a.m., RHR "B" pump was tripped to allow verification of valve lineup. Pumps "A"
& "C" tripped due to a loss of power (unrelated to the over-pressurization) approximately one hour later. Prior to restart, on 12/09/80, pumps "A", "B"
& "C" could not be turned by hand. All three pu=ps were bumped electrically and allowed to coast down.
Pumps "A"
& "C" coasted down normally. Pump "B" coasted down within a shorter period than the other pu=ps and came to an abrupt halt at the end of the coast down. After stopping, Pump "B" could not be rotated by hand.
A Byron-Jackson Representative was contacted and arrived at GGNS on the af ternoon of 12/11/80. Attempts were made to free the pump "B" by use of the adjusting plate. Condition Report (CR) #5126 was issued documenting the pump had seized with possible damage.
The CR was screened as not being potentially reportable. On 12/
12/80, the pump shaf t broke loose and turned 3 or 4 revolutions, by hand, then re-seized. On 12/15/80, efforts resumed to deter-mine cause and extent of damage. On 12/16/80, debris, which seemed to be weld slag, was found in the suction and discharge sides of the pump.
On 12/17/80, the mechanical seal and upper bearing were removed.
Attempts to remove the throttle bushing failed. A jack was applied to the bushing, at which point it was detected that the shaft moved with the bushing. It was determined that the bushing was galled to the shaft. CR #5183 was issued to allow removal of Unit II pump parts in the event they were necessary to meet the schedule for
Attachment to AECM-81/43 Page 2 of 3 system turnover. On 12/18/80, the bushing came loose and was removed. CR #5175 was issued on 12/18/80 which states, "Due to the nature of visible damage to the pump shaft of RHR "B" pump, internal damage to upper thrust bearing in the pump motor should be considered as a distinct possibility and an inspection of said motor should be performed." CR #5176 was also issued on 12/18/80 to require an inspection of the interior and ex-terior of the pump barrel for hidden damage. These two CR's were screened as not being potentially reportable. At this time, on 12/18/80, a decision was reached to use the Unit II shaft, since early indications were that it would take a considerable amount of time to ship the shaft to the manufacturer for the minor repairs.
On 12/22/80, the 3rd stage of the pump was removed. On 12/23/80 the remaining two stages were removed. All three stages showed signs of overheating in that te=per films were present on mating surfaces of the impeller and wear rings. The total damage was visible at this point. On 1/6/81, a decision was reached to use Unit II pump assembly and CR #5126 was supplemented to docu-ment the additional damage. The damaged components will be cor-rected as follows:
- 1) The throttle bushing will be replaced.
- 2) Head shaft will be repaired by the manufacturer and used on Unit II pump.
- 3) Impellers - mating surface to case wearing rings will require buffing.
- 4) Case wearing rings will be replaced with a set machined to suit the impellers.
The pump internals are in the process of being returned to the manufacturer for the repairs outlined above.
On 1/15/81, Nonconformance Report #5302 was issued to document the inability to insert the rebuilt "B" pu=p internals into the pump barrel. Inspection of the pump barrel revealed an out-of-round condition at the lower support ring. This condition is still under investigation.
11.
Proposed Resolution of the Deficiency
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Mississippi Power & Light Company is working with the constructor to evaluate this deficiency and to make the following determina-tions:
- 1) The cause, including the extent of the problem. The cause has not been fully determined at this time, but is suspected to be debris in the pump, which caused excessive wear and heat. The overpressurization has been determined not to be a factor in the failure in that the temperature / pressure relationship was below the design basis of the system. It should also be noted that all three RHR pumps sere subjected to the same pressure spike.
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Attachmtnt to AECM-81/43 Page 3 of 3 i
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- 2) Corrective action to be taken other than that presently un-
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derway as noted in I above.
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- 3) Action to preclude recurrence will be determined af ter the cause of failure has been established.
Our decision as to r.eportability under 10CFR50.55(e), will be t
based on the cost to evaluate and repair the damaged pump. The 2
Office of Inspection & Enforcement Manual titled, " Guidance-10CFR50.55(e) Construction Deficiency Reporting", will be uti-lized as our basis for determining whether this damage falls within the meaning of extensive. The expenditures associated with the damage will be compared with the original cost of the i
pump to determine if the repair cost is disproportionate with the original cost.
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III. Status of Proposed Resolution The constructor is in the process of returning the damaged parts
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to the manufacturer for repair. Unit II pump parts are presently being installed in the Unit I' pump.
These inputs should be available to MP&L for evaluation by July 31, 1981.
IV.
Reason for Delav in Final Report The evaluation is not complete.
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V.
Final Report Date We expect to file our final report by August 27, 1981.
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