IR 05000498/1990007
| ML20012D504 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 03/09/1990 |
| From: | Gagliardo D, Garrison D NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | |
| Shared Package | |
| ML20012D503 | List: |
| References | |
| 50-498-90-07, 50-498-90-7, 50-499-90-07, 50-499-90-7, NUDOCS 9003270426 | |
| Download: ML20012D504 (5) | |
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APPENDIX U.S. NUCLEAR REGULATORY COMMISSION REGION IV-NRC Inspection Report: 50-498/90-07 Operating Licenses:' NFP-76
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.50-499/90-07 NFP-80 Dockets: 50-498 L50-499 a
Licensee: Houston Lighting & Power Company (HL&P.)
P.O. Box 1700 Houston, Texas 77251 y
Facility Name: SouthTexasProject(STP)
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Inspection At: STP, Matagorda County, Texas Inspection Conducted: January 22-26, 1990 Inspector:
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d O kD D..L. Garrison, Reactor Inspector, Material &
Date Quality Programs Section, Division of Reactor Safety f
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du. M 3 I IO Approved:
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E. pagTTardo, Ihief, Operational Programs Date
.Section,l Division of Reactor Safety L
Inspection Summary
- _ Inspection Conducted January 22-26, 1990 (Report 50-498/90-07;50-499/90-07)
Areas Inspected: ' Routine, unannounced inspection of cold weather protection and followup of licensee reported events.
I-Results: Within the two areas inspected, no violations or deviations were identified.' 'The licensee had performed preliminary evaluations which were continuing Sccause of the potential for further. cold weather effects on plant systems. A plan had been implemented whereby each affected system would be
? independently reviewed by engineering and operations personnel. Necessary corrective actions were promptly taken at the time of the cold weather period in December, but because Unit I was in Mode 5 and Unit 2 was in a Mode 6, no immediate safety issues were involved. The corrective actions taken were-effective in handling the challenges which developed as a result of the cold weather.
The licensee was also considering the effects on the overall plant as part of their investigation of the problems which developed.
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DETAILS =
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-l 1.-' PERSONS CONTACTED HL&P
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' *A. Harrison, Supervising Licensing Engineer
- *W.' Kinsey, Plant Manager
- M. McBurnett, Manager Licensing
~ *S. Rosen,. Vice President,-Engineering and Construction I
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- A. McIntyre, Manager,' Support Engineering
- J~. Lovell, Manager Operations -
- T. Jordan, Manager Plant Engineering
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- G. Parkey, Supervisor Planning -
R. Chewning,-Vice President, Nuclear Assurance a
.D. Wiegand, Engineer, Fire Protection
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' T..Fryar, Consultant, Support Engineering R. Balcon, Manager, Audits / Assessments F. Comeaux, Shift Technical Advisor
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- l NRC j
- J. T. Tapia, Senior Resident Inspector a
- D. L. Garrison, Region IV
- J. E. Gagliardo, Region IV.
- Denotes those attending the exit meeting on January 25, 1990..
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In addition to the above, the inspector also held discussions with various
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licensee engineering and operations personnel.
2.
COLD WEATHER PROTECTION
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The purpose;of i.his inspection was to assess the licensee's actions following a l'
severe and unusual cold weather period in December 1989. The inspector i
examined..the areas of preparation, preventive actions taken, preventive actions
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-that would have had to be taken if the units had been at power, and future preventative actions.
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During the period of December 20-25, 1989, an unprecedented and unusually cold p
weather system _ moved through south Texas. On December 21 and 22 temperatures-as: low as 7 F were recorded at the site. Some prior warning had been given and
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corrective actions were taken, however, because of the number of areas that
were effected, all of the potentially effected areas were not recognized or were not provided with the necessary protection.
The licensee had issued a problem report (890882) to address the events caused by the cold weather. The inspector reviewed 12 of the 39 problems that were identified by the licensee on this problem report. The review was designed to
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- assess and identify any items, systems, or components effected by the cold weather which would have prevented further operation or would have interrupted plant-operations if the plant had been in operation.
_The inspector reviewed each item with appropriate station personnel and also reviewed the applicable instrument, piping and logic diagrams associated with the systems. The results of the review are documented below.
The-deaerator feed tank indication and controls were lost because of i
moisture in the instrument inline valves freezing.
If the plant had been-
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in operation, this event could have caused a low-level signal from the
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deaerator instrumentation, which would have shutdown the feedwater booster
pumps, and the main feed pumps would have tripped on a loss of suction.
Although the auxiliary feed pumps would start, their capacity would not f
i have been sufficient to maintain the steam generator levels and thus the reactor would have tripped on a low-level steam generator signal.
If the loss of level in.the deaerator were discovered promptly, compensatory action by plant operators could have prevented a reactor trip.
. Steam Generator IA Pressure Transmitters PT-514 and PT-7411 were frozen.
These units are located in the isolation valve cubicles which, if the
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plant were in operation, would have been warmed by the multitude of
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mainsteam and main feedwater piping in the cubicles. No safety issues
were identified in this area.
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The discharge pressure signal for the Number 11 and 13 steam generator feed pump turbines was lost because of frozen lines. This loss would not have been significant if the plant were operating as it only provided indication and control to the recirculation valve.
The freeze caused a loss of the essential cooling water (ECW) seal water pressure alarm and the Train "A" ECW pump seal water flow alarm. A loss of the seal water-to the pumps would have possibly destroyed the pump seals, which would have led to a decrease of the pump capacity. The major problem that would have been experienced was the wetting of other components in the area.
i The freeze resulted in the failure to get a start permissive signal for l
any of the circulating water pumps. With the plant in operation, the start permissive would not have been needed, but if it had been needed, operator action could have been taken to start the pumps manually.
The "A" and "B" component cooling water (CCW) expansion tank low-level i
switches failed low because of the freeze.
If this had resulted in a low-level signal, several nonsafety-related loads would have been isolated and, if a low-low-level signal were received, safety-related loads would have been isolated. This occurrence was not likely during normal
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operation because of the building would have been warmer. The fact that two trains were lost, however, caused the licensee to enter Technical Specification 3.03 action statement and required corrective actions.
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r The mechanical auxiliary building (MAB) and fuel handling building cooling
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and ventilation coils were ruptured by-the freeze. There was no impact on the facility because cooling was not needed.
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The seal water lines on all feedwater booster pumps and feedwater pumps
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were frozen. During plant operation the pump seal water would have been
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warm and probably would not have frozen.
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The freeze caused erroneous reactor coolant system boron concentration-
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analysis results, which presented technical problems in adjusting core
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reactivity.
If the plants had been operating, operator action would have been necessary to maintain the boron concentration within the specified limits.
In addition to the above problem areas, the inspector performed an extensive inspection of the firewater system which included the:
The overall f acility including the pumphouse, tanks, and instrumentation
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Hydrant Station 10, which included the inventory (i.e., spanner wrenches,
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hoses, nozzles, and support tools)
Auxiliary Fuel Oil Storage Tank Valve House
Deluge Valve House No. 12
Valve House No. 12 in Unit 2 l
The fire protection group had apparently prepared for the cold weather in that
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the _ fire water system was fully functional throughout the cold weather period.
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The inspector was concerned regarding the weak design for the control of
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ventilation under low ambient temperature conditions in three plant structures
(IVC,MAB,andECW). The problems associated with the equipment in these structures might not have occurred had the design and control of the ventilation l
been regulated or thermostatically controlled. The licensee relied on the
outside air supply being controlled manually. As a result, the cold air supply was not secured and the low temperatures in these structures were exacerbated by
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cold air being drawn into the buildings by the ventilation system.
In conclusion, the licensee failed to perform an adequate review and
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preparation for cold weather plant operations. The licensee did begin to take appropriate anticipatory actions at the beginning of the freeze but was quickly overwhelmed by the magnitude and number of problems. A corrective action plan
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to prevent future problems during cold weather was being draf ted. Because the plants were in Mode 5 and Mode 6, respectively, at the time of the freeze, no problems of a safety nature were identified.
The inspector did observe that the chemical operators response and the cold weather preparation of the fire protection system were noteworthy strengths.
No violations or deviations were identifie ;
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3. -FOLLOWUP ON EVENTS RELATING TO THE UNIT 2. NO. 22 STANDBY DIESEL ENGINE
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3.1 Stress Analysis
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After the failure of the No. 4 connecting rods (left and right) in Diesel Engine No. 22, on November 28, 1989, the licensee implemented a plan of action which required a finite stress analysis of the rod areas which failed. The failures were the result of a manufacturing defect caused by overdrilling an oil passageway. During the investigation it was found that other parts had been overdrilled to varying depths, and an analysis was required _to assess the
generic effects of the issue. The licensee originally committed in their-justification for continued operations (JCO), that the analysis would be completed by January 15, 1990; however, the modeling required to do the analysis proved difficult, and a 30-day extension was needed to complete the i
analysis.
3.2 Fuel Injection Pump Failures On December 28,1989, after 700 hours0.0081 days <br />0.194 hours <br />0.00116 weeks <br />2.6635e-4 months <br /> of operation on the No. 22 diesel, the number four lef t cylinder was found to have loose nuts on two of the four hold down studs-for the fuel injection pump to the engine. At the time, the licensee was. concerned that the pump might be seizing, and it was replaced. After 80 additional hours of operation, the replacement pump seized because of contamination in the fuel and was again replaced. After only 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of service, the newly installed pump was ejected from the engine because of the failure of the hold down studs. A new pump with new studs and nuts was installed, and no problems have since been experienced.
The-inspector concluded that engineering should have realized that the hold down studs (which are hollow and designed to break under stress rather than destroy a pump or other engine parts) should have been replaced after the seizure of the
.second pump, and thus the third pump would not have been ejected. The vendor
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equipment manual did not address stud replacements, and the licensee stated that I
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revised instructions on pump replacement will be prepared to address stud
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l replacement.
l The licensee's program for completing the stress analysis was satisfactory. The problems associated with the fuel injection pumps were difficult to assess, but l
a more effective root cause analysis would prevent future problems of this
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nature.
No violations or deviations were identified.
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4.
EXIT INTERVIEW l
The inspector met with Mr. Warren Kinsey and other members of the plant staff denoted in paragraph 1 on January 25, 1990, and discussed the results of the inspection. The licensee did not identify any information discussed at this
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meeting as proprietary.
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