IR 05000282/1981015
| ML20030C783 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 08/07/1981 |
| From: | Burgess B, Feierabend C, Little W NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | |
| Shared Package | |
| ML20030C782 | List: |
| References | |
| 50-282-81-15, 50-306-81-18, NUDOCS 8108280142 | |
| Download: ML20030C783 (5) | |
Text
{{#Wiki_filter:- . . U.S. NUCLEAR REGUIATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT
REGION III
Report No: 50-282/81-15; 50-306/81-18 Docket No: 50-282; 50-306 License No: DPR-42; DPR-60 Licensee: Northern States Power Company 414 Nicollet Mall Minneapolis, MN 55401 Facility Name: Prairie Island Nuclear Generating Plant Inspection At: Prairic Island Site, Red Wing, MN 55066 Inspection Conducted: July 1-31, 1981 Inspectors: ) C. D.
eierabend W1Y* I B. L. Burgess y / 8/ , _f Approved By: W.
. Little, Chief f*f 7 [[ Reactor Projects Section 2C / /~ Inspection Summary Inspection on July 1-31, 1981 (Report No: 50-282/81-15; 50-306/81-18) Areas Inspected: Routine resident inspection of plant operation, maintenance, surveillance, radiation protection, replacement of reactor coolant pump and independent verification of systems. The inspection involved a total of 193 inspector hours onsite by 2 NRC inspectors including 68 inspector hours on-site during of f-shif ts.
Results: No items of noncompliance were identified.
8108280142 gioggg gDRADOCK 05000282 PDR i . ..... ._. _ _ _ _ _ _ _ _ _ _ _ _ . DETAILS 1.
Personnel Contacted F. Tierney, Plant Manager J. Brokaw, Plant Superintendent, Operations and Maintenance E. Watzl, Plant Superintendent, Plant Engineering and Radiation Protection A. Ilunstad, Staff Engineer R. Lindsey, Superintendent, Operations J. Nelson, Superintendent, Maintenance M. Mulhausen, Maintenance Supervisor W. Allar, Maintenance Supervisor J. Ilof fman, Superintendent, Technical Engineering D. Schuelke, Superintendent, Radiation Protection M. Klee, Superintendent, Nuclear Engineering S. Northard, Nuclear Engineer D. llaugland, Engineer B. Stephens, Engineer G. Lenertz, Engineer G. Miller, Engineer D. Ilansen, Inservice Inspection Engineer D. Cragoe, Shift Supervisor G. Edon, Shift Supervisor R. Flack, Shif t Supervisor J. Meath, Shift Supervisor M. Balk, Shif t Supervisor T. Goetsch, Shift Supervisor D. Walker, Shif t Supervisor P. Valtakis, Shift Supervisor 2.
Operational Safety Verificat' - a.
General Unit 1 operated at power throughout the month. Unit 2 was restarted af ter replacement of the No.21 reactor coolant pump, and was back on line July 24th. A reactor trip from approximately 407. power on July 24th delayed power escalation about 8 hours. The unit operated routinely for the rest of the month, b.
Control Room Observations The inspector observed control room operations, reviewed applicable logs, conducted discussions with control room operators and observ2d shift turnovers. The inspector verified the operability of selected emergency systems, reviewed equipment control records and verified proper return to service of affected components. On July 21st the containment ventilation monitor indicated an increase in particulate activity of about one decade. The licensee analyzed a containment air sample confirming a small amount of gaseous activity, indicating a very small primary system leak. The licensee conducted a thorough inspection of Unit 1 containment, however, the leak was too small to find. The licensee is continuing to monitor activity levcis and reactor coolant system leak rate measurements, even though the apparent leak is too small to be of concern.
-2-
c.
Tours Tours of the auxiliary, turbine and containment buildings and external areas were conducted to observe plant equipment conditions, including potential fire hazards, and to verify that maintenance work requests had been initiated for equipment in need of maintenance. The inspectors made several tours of Unit 2 containment in conjunction with replacement of the No.21 reactor coolant pump and preparations for restarting the unit.
d.
Independent Verification The inspector performed a walkdown of accessible portions of the Rad Waste Systems. Observations included confir ation of selected por-tions of the licensee's procedures, checklists, plant drawings, ver-ification of correct valve and power s,pply breaker positions to insure that plant equipment and instrumentation are properly aligned, and com-parison of posted radiation levels with radiation levels measure 6 by the inspector.
3.
Reactor Coolant Pump (RCP) Shaft Failure Fhutdown of the No.21 RCP on June 11, 1981, juetoexcessivevibrationwas described in a previous inspection report. -- The licensee continued inves-tigation of the causes, after decontaminating the pump internals to the extent practicable. This reduced exposure levels by a factor of about 30, minimizing personnel exposure during handling and disassembly.
Initial inspection showed rubbing on the impeller, req; iring further dis-asaembly, including removal of the impeller, diffuser and pump shaft. The pump shaf t was then moved to the " hot machine shop" lathe for check of straightness, which showed runout of approximately 100 mils (0.100 inches).
Ultrasonic testing provided indication that a defect existad in the shaf t below the radial bearing. Further investigation required removal of a sleeve that covered the defect.
A lack of drawings on site hampered the licensee in performing the necessary steps to remove the sleeve. The only information available was from the vendor representative who stated it was a " shrink-fit" sleeve. Af ter un-successfully attempting to drive the sleeve off, it was cut in half and i ( removed. A circumferential crack about 3/4 through the shaf t was cicarly visible, passing directly through a drill hole into the shaf t that was made i during original assembly for securing the sleeve to the shaf t.
The licensee shipped the shaft to the pump vendor for further investigation of the failure mechanism. The licensee war verbally informed that tae mecha-I nism was fatigue failure. The licensee installed a replacement pump.. The unit was back on line on July 24th, and bac;. up to full power on July 27th, The licenst e has forwarded an event report 2/ and will provide additional information concerning failure mechanism when it becomes available.
1/ IE Inspection Report No. 50-306/81-15 2/ Licensee Event Report No. 81-008 dated 7/17/81-3- .. - ._ ._
.-- - . _.. ..__ . 4.
Surveil'.ance The inspectors witnessed portions of surveillance testing of safety related systems and components. Witnessing included verifying that the tests were scheduled and performed within Technical Specification requirements, ob-serving that procedures were being followed. that LCO's were not violated and that system restoration was completed.
a.
S P-1093 Diesel Generator Manual ar.d 4KV Voltage Rejection Scheme Test Test was satis factory. The inspector independentiv confirmed return of D2 to operable statra after completion of the test.
b.
SP-2072-Eli Local Leak Rate Test - Equipment llatch, Unit 2 Test was satisfactory. This test was required because the equipment hatch was opened to move the reactor coolant pump into containment.
c.
SP-1003 Analog Protection Functional Test, Unit 1 The inspector observed portions of the test to insure pro-cedural compliance and verify that Technical Specifications (TS) were met.
During the performance of the test, #12 Steam Generator (SG) Power Operated Relief Valve (PORV) controller failed when placed in Automatic Mode, signaling the valve to open. The logic had apparently failed during the test, as the valve had remained closed with the con-troller in Automatic before the test started. Repairs were completed prior to returning the PORV to service, which was completed within time allowable by TS.
The inspector ob-served completior, of the repairs and return to service.
d.
SP-2032 Safeguards Logic Test, Unit 2 Test was required prior to Unit startup. Test was satisfactory.
5.
R,eview of Plant Operations, Unit 2 The inspectors observed plant operations during Unit 2 shutdown and confirmed that Te:hnical Specification requirements were met.
The inspectors reviewed checklists during preparations for re. start and indepenuently verified select-ed portions of the system for proper lineup.
The inspectors confirmed that the required testing was scheduled and per-formed and observed portions of fill and vent and heatup operations.
No areas of concern were identified.
6.
Unit 2 Reactor Trip On July 24,1981 at 10:21 A.M., the inspector observed & Unit 2 Reactor trip from 397, power due to low steam generator level. Low steem generator level was caused by a clo3ged strainer in the condensate polishing system, -4- . _. _ _. _ _ _. , -.. _ _ _ _ _ _ _. _ , . _. _ _ _ -
- -.__ - .-
.. plus a condensate pump recirculation valve opening. This lowered condensate header pressure to the feed pump trip setpoint and caused a low steam gen-erator icvel trip.
All systems responded as expected and the unit was brought to hot shutdown.
The cause of the trip was verified by log review and discussion with control room operators. Technical Specifications and plant procedures were review-ed and all requirements were met for rescart. Unit 2 was brought to critical- , ity and tied to the grid at 6:33 P.M. on July 24, 1981.
. 7.
Exit Interviews The inspectors attended an exit interview conducted by RIII inspectors, I. N. Jackiw and D. L. Robinson on July 14, 1981. No areas of concern were identified.
The inspectors conducted interim interviews and an exit interview with Messrs.
Tierney, Vatz1 and Hunstad at the conclusion of the inspection. The inspectors stated that they observed work in progress, during testing and restart of the plant af ter replacement of the No.21 reactor coolant pump. The inspectors stated that they observed that performance and cooperation of the radiatian protection and maintenance personnel was such that radiation exposure was minimized by shielding and timekeeping, during decontamination and dis-assembly of the pump. The inspector also commented that operator perform-ance was excellent during recovery from the reactor trip on July 24th.
The inspectors identified an inaccuracy in the licensee's response, o an item of noncompliance identified in a previous inspection report. 2 The licensee stated that the error was partially due to a desire to meet a response deadline, although the personnel involved were not available to confirm the facts. The licensee stated that a revised response will be forwarded to correct the inaccuracy.
, l 3/ IE Inspection Report Mo. 50-282/81-11; 50-306/81-13-5- - - - -. _ - - ,- - }}