IR 05000269/1986026
| ML16161A772 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 10/23/1986 |
| From: | Bryant J, Peebles T, Sasser M NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML16161A771 | List: |
| References | |
| 50-269-86-26, 50-270-86-26, 50-287-86-26, NUDOCS 8611030222 | |
| Download: ML16161A772 (14) | |
Text
gt REGU'
UNITED STATES 0 oNUCLEAR REGULATORY COMMISSION
REGION II
101 MARIETTA STREET, ATLANTA, GEORGIA 30323 Report Nos.:
50-269/86-26, 50-270/86-26, and 50-287/86-26 Licensee:
Duke Power Company 422 South Church Street Charlotte, Facility Name:
Oconee Nuclear Station Docket Nos.:
50-269, 50-270, 50-287 License Nos.:
DPR-38, DPR-47, and DPR-55 Inspection Conducted:
S ptember 9 - October 14, 1986 Inspectors:
,2
M. K. asser Si e
Approved by:
/
'
,
T. Peebl s, Sec ion Chief mat Signed Division of Reactor Projects SUMMARY Scope: This routine, announced inspection involved resident inspector inspection on-site in the areas of operations, surveillance, maintenance, verification of engineered safety features lineups, followup of events, followup items of non-compliance, and performance indicator Results:
Of the seven areas inspected, no items of non-compliance or deviations were identifie PDR ADOCK 05000269 a
REPORT DETAILS Licensee Employees Contacted
- M. S. Tuckman, Station Manager T. B. Owen, Maintenance Superintendent R. L. Sweigart, Operations Superintendent J. M. Davis, Technical Services Superintendent
- C. L. Harlin, Compliance Engineer
- F. E. Owens, Assistant Engineer, Compliance N. A. Rutherford, System Engineer, Licensing Other licensee employees contacted included technicians, operators, mechanics, security force members, and staff engineer Resident Inspectors
- J. C. Bryant
- M. K. Sasser
.
- Attended exit intervie.
Exit Interview The inspection scope and findings were summarized on October 16, 1986 with those persons indicated in paragraph 1 abov The licensee did not identify as proprietary any of the materials provided to or reviewed by the inspectors during this inspectio.
Licensee Action on Previous Enforcement Matters Violation 50-269/86-20-04 (Closed)
Failure to Document Independent Verificatio The inspectors reviewed corrective action and verified training was conducte Violation 50-269/86-05-01 (Closed)
Failure to Provide Adequate Respiratory Protective Equipment to Maintain Intakes of Radioactive Material as Low as Reasonably Achievabl Upon review by Region II, this violation was cancelle.
Unresolved Items Unresolved items were identified during this inspection and are discussed in
- n paragraph 1.
Licensee Event Reports The inspectors reviewed nonroutine event reports to verify the report details met license requirements, identified the cause of the event, described corrective actions appropriate for the identified cause, and adequately addressed the event and any generic implication In addition, as appropriate, the inspectors examined operating and maintenance logs, and records and internal investigation report Personnel were interviewed to verify that the report accurately reflected the circumstances of the event, that the corrective action had been taken or responsibility assigned to assure completion, and that the event was reviewed by the licensee, as stipulated in the Technical Specification The following event reports were reviewed:
LER 50-269/83-12 (Open)
Emergency discharge valve opened without command due to component malfunction:
New cable has been laid in a more protected area to avoid accidental damag The modification to connect the new power supply is scheduled for December 198 LER 50-269/85-13 (Closed) "IC" gaseous waste disposal tank was pressurized and isolated without taking a hydrogen concentration sample due to personnel erro LER 50-269/86-05 (Closed)
Vent gaseous radiation monitor 1RIA-45 removed from service during refueling operations due to personnel erro LER 50-270/85-07 (Closed) Fire Watch Patrol Not Established While Fire Detector String was Inoperabl The Station Directives have been revised to clarify Statalarm reflash capabilities and other corrective actions have been complete LER 50-270/84-01 (Closed)
Both Unit 2 RBS Trains Made Unavailable During Testing. Corrective actions have been completed and reviewed by the resident.
Inspector Followup Items IFI 50-269/84-25-03:
50-270/84-24-03; 50-287/84-24-03:
(Closed)
Improvement of NEO Qualification Record Keeping Practice The inspectors reviewed records of instructions to supervisors and changes made in Operations Management Procedure 3-2 concerning qualification of non licensed operators. These changes require signoff by the supervisor as each step of qualification is complete The inspectors also selected, at random, several NEO qualification books and verified that signoff was over a
- s reasonable time perio.
Plant Operations The inspectors reviewed plant operations throughout the reporting period to verify conformance with regulatory requirements, technical specifications (TS),
and administrative control Control room logs, shift turnover records, and equipment removal and restoration records were reviewed routinely. Interviews were conducted with plant operations, maintenance, chemistry, health physics and performance personne Activities within the control rooms were monitored on an almost daily basi Inspections were conducted on day and on night shifts, during week days and on weekend Some inspections were made during shift change in order to evaluate shift turnover performanc Actions observed were conducted as required by Operations Management Procedure 2-1. The complement of licensed personnel on each shift inspected met or exceeded the requirements of T Operators were responsive to plant annunciator alarms and were cognizant of plant condition Plant tours were taken throughout the reporting period on a routine basi The areas toured included the following:
Turbine Building Auxiliary Building Units 1 and 2 Penetration Rooms Units 1,2, and 3 Electrical Equipment Rooms Units 1,2, and 3 Cable Spreading Rooms Station Yard Zone within the Protected Area Standby Shutdown Facility Condenser Circulating Water Intake Structure Unit 2 Reactor Building During the plant tours, ongoing activities, housekeeping, security, equipment status, and radiation control practices were observe Unit 1 began the report period at 100% power and continued until power was reduced to 25% at 4:45 on September 21, in order to make repairs on reheater drain lines (paragraph 10). The reactor was returned to 100% power beginning at 1:20 a.m. on September 22, and continued at 100% until shutdown was begun at 9:00 a.m. on October 2, when the Emergency Condenser Circulating Water (ECCW)
system was declared inoperable (paragraph 11).
Unit 1 remained at cold shutdown the remainder of the reporting perio Unit 2 began the report period at refueling shutdown and remained shut down throughout the period. The anticipated startup on October 10 was delayed due to ECCW inoperabilit Unit 3 began the report period at 100% power and operated at that power until manually tripped on September 17 due to failure of a reheater drain line. It was returned to 27% power on September 18 while repairs were made
and to 100% power on September 2 The unit remained at full power until October 2 when it was shut down due to ECCW inoperability, and remained shutdown through the end of the perio No violations or deviations were identifie.
Surveillance Testing The surveillance tests listed below were reviewed and/or witnessed by the inspectors to verify procedural and performance adequac The completed tests reviewed were examined for necessary test prerequisites, instructions, acceptance criteria, technical content, authorization to begin work, data collection, independent verification where required, handling of deficiencies noted, and review of completed wor The tests witnessed, in whole or in part, were inspected to determine that approved procedures were available, test equipment was calibrated, prerequisites were met, tests were conducted according to procedure, test results were acceptable and systems restoration was complete Surveillances witnessed in whole or part:
PT/3/A/600/13 Motor Driven Emergency Feedwater Pump Performance Test PT/3/A/0160/06 Reactor Building Cooling Unit Heat Exchanger Performance Test PT/2/A/261/06 Condenser Circulating Water System, Gravity and Recirculation Flow PT/2/A/610/15 Emergency Power Switching Logic, ES Actuation, Keowee Emergency Start Test MP/0/A/1800/23 Remove Oil Samples from 3A MDEFWP PT/1,2,3/A/261/07 Emergency CCW System Gravity Flow Test During the inspection and review of the Keowee Emergency Start (Load Shed)
Test the inspector's noted an apparent deficiency in the methods used for testing the load shed logic. As currently written and conducted, the test verifies that 4160 kv loads which are required to load s.hed during loss of AC power, do in fact load shed. However, the test does not provide positive verification that all non load shed components remain on the 4160 kv buses upon their being re-energized by the onsite emergency power supply (Keowee).
The licensee has committed to revise this test procedure to test all logic for load shed and non load shed components. As this test is conducted on a refueling outage frequency it will be revised prior to the next refueling outage at the station. This will be listed as inspector followup item, IFI 50-270/86-26-01:
Revisions to the Keowee Load Shed Surveillance Tes During the load shed test conducted on October 1, the LPSW flow control valve closed on a loss of powe The sister valve on the A cooler failed open as designed. When the control valve failed closed decay heat cooling on Unit 2 was lost for a short period of time. During an ES actuation
concurrent with a power failure on these valves they should fail open to ensure decay heat coolin During subsequent testing by I&E maintenance, LPSW-252 worked satisfactoril At the end of the report period the licensee was continuing evaluation of the problem that occurred during the load shed tes This will be listed as inspector followup item, IFI 50-270/86-26-02: Questionable Operation of Decay Heat Cooler Flow Control Valv No violations or deviations were identifie. Maintenance Activities Maintenance activities were observed and/or reviewed during the reporting period to verify that work was performed by qualified personnel and that approved procedures in use adequately described work that was not within the skill of the trade. Activities, procedures and work requests were examined to verify proper authorization to begin work, provisions for fire, cleanliness, and exposure control, proper return of equipment to service, and that limiting conditions for operation were me Maintenance witnessed in whole or in part:
a. WR 52147E-MOVATS Test of Valve LPSW-5 b. Refurbishment of Various Limitorque Operators c. Modifications to Condenser Circulating Water Pump Suction Lines d. Inspection of Reactor Building Cooling Unit Coolers Paragraph 11 of this report describes the CCW system problems leading to the shutdown on units 1 and 3 at the same time that Unit 2 was still in a refueling and maintenance outag During these outages the licensee completed work to satisfy NRC commitments on all three units in the following areas; a. Refurbishment of Environmentally Qualified Limitorque Operators b. Inspection of Wiring on EQ Limitorque Operators c..Lubrication of EQ Limitorque Operators with Qualified Lubricant However, open items associated with these items will remain open pending further review by the inspector No violations or deviations were identifie.
Unit 2 -
Ruptured Reheater Drain Tank Line Description of Event At 1:35 on September 17, 1986, with the reactor at 100% power, a 10 inch carbon steel elbow in the line from the "B" 1st stage reheater drain tank to "B" heaters failed catastrophicall The 525 psig design line carries water at 400 to 450 psi Upon hearing a loud noise and escaping steam, reactor operators (RO) immediately began a rapid power decrease. At
1:36 p.m.,
on being informed that the turbine building was full of steam, the RO initiated a manual scra A number of people were working in the turbine building, but none were in the immediate vicinity and there were no injurie Also, due to the location of the elbow and direction of force, there was no apparent damage to other equipmen Concurrent Events Other events occurred prior to, during, and following the line break which complicated operator actions, but cannot necessarily be said to have caused or resulted from the break. These events are described belo At 1:22 p.m. the Unit 3 integrated control system (ICS) was taken to manual in order to perform an RPS on-line CRD breaker tes Due to feedwater oscillations which developed, the test was stopped in order to return the ICS to auto. As the ICS was returned to auto, the 10 inch line rupture When the reactor was tripped, both main feedwater pumps (FWP)s tripped on high discharge pressure. All emergency FWP's actuated immediatel The turbine driven EFWP was secure The A train of EFW initiated flow to A steam generator and raised the SG level to 80 inches in the extended startup range rather than stopping at the normal 25 inch startup leve The A train was taken to manual control to avoid possible overfil During the performance of immediate manual actions following the scram, the ICS inverter system trouble alarm activated and all ICS stations tripped to manua The inverter tripped to regulated ac power. The pressurizer power operated relief valve (PORV)
opened for about 2 seconds, then reseate There was no real system pressure rise sufficient to cause this event. One main steam code safety valve continued to relieve for twenty-nine minutes after the scram until steam header pressure was reduced to reseat it. Also, one 600 V a.c. motor control center tripped during the recovery following the scra Reheater Drain Tank Line Fourteen hours after the scram the reactor was returned to critical and low power, with the reheater system isolated, as ultrasonic (UT)
examinations were made of sister elbows (10 and 12 inch) in the reheater system and as repairs were made. Also, power was reduced on Unit 1 and the reheater lines UT'ed. Results of the UT and repairs made were as follow Nominal wall thickness Minimum allowable 10 inch line.365 inch 0.186 inch 12 inch lines 0.375 inch 0.208 inch Unit 3 a.(Failed line)
Min. thickness found=0.10 inch 10 inch lines Replaced 3 elbows and connecting straight sections
7 Minimum found=0.08 inch Replaced 2 elbows and connecting straight section 12 inch lines Minimum found=0.22 inch Weld repair of pipe UT good Unit 2 10 inch lines Replaced I elbow UT good 12 inch lines a. & UT good Unit 1 10 inch line Minimum found=0.13 inch Replaced 1 elbow UT good 12 inch lines UT good Minimum found=0.155 inches Replaced 1 elbow Concurrent Anomalies There is no evidence that returning the ICS to auto had any relationship with failure of the heater drain tank line nor that the reactor trip had any bearing on the subsequent loss of the IC Apparently, a momentary interruption of power to the inverter caused the inverter static transfer switch to activate, switching ICS power to regulated ac power. The immediate return of inverter dc power caused the static transfer switch, which seeks the preferred power source, to attempt to return ICS power to the inverter. However, the switch was then out of synchronization and the result was blown fuses in the switch and inverter, which then caused the ASCO switch to transfer power to the ICS from the regulated ac source. The ASCO switch requires 60 milliseconds to transfer, resulting in a power interruption to the IC Instrumentation reflected the interruption, causing pressurizer level instruments to spike, turbine bypass valves to go to-manual, pressurizer heaters to go off, and other instruments to spik The brief opening of the PORV was due to an amplifier spike in the control circui The FWP trip was the result of FWP discharge valves closing faster than FWP turbines could respond, resulting in a trip due to high discharge pressur Improper control exhibited by the A train of emergency feedwater was found to be a bad card in the control system and was unrelated to other event Continuing blow down of one main steam safety valve was not necessarily a malfunctio Main steam pressure is maintained at or above 1010 psig following a trip in order to maintain steam generator level Two of the safety valves relieve at 1050 psig, + 11 psi with a nominal blowdown of 4%.
The inspector observed that header pressure was over 1010 psig about fifteen minutes after the trip while the safety valve was still blowing down. Since the system was not cooling down, header pressure was not decreasing, and many other events were in progress, getting the safety valve closed was not a high priority ite After about twenty-nine minutes, with the plant stabilized, header pressure was reduced to 850 psig to close the code safety valve. Since the pressure was dropped rapidly it cannot be determined at what pressure the valve close A modification planned to be installed in the near future will record at what pressure main steam code safety valves open and clos Investigation into the cause of the 600Vac motor control system (MCC)
tripping revealed no problems. At the time the trip occurred, an unusually large number of valves powered from the MCC were being operate However, it is believed that the very high moisture content of turbine building air caused short circuits in pumps and other equipment, tripping the MC The MCC was reset three times before it stayed energize System Recovery Unit 3 was returned to critical at 3:15 on September 18 and repairs were accomplished at 27% power with drains and associated steam extraction isolated. Repairs were completed at 6:30 on September 18, equipment was removed from isolation and power ascension began with Unit 3 reaching 100% power at 1:10 a.m. on September 2 On September 20 at 7:54 a.m., Unit 1 began power reduction to 75% for UT of elbows, and at 4:45 on September 21 power reduction to 25% began for repair Power increase to 100% began at 1:20 a.m. on September 2 The inspector observed operation in the control room during plant stabilization after the scra In his opinion, the staff handled the situation in a professional manner and were in control of the plant at all time No violations or deviations were identifie.
Degraded Emergency Condenser Circulating Water (ECCW) System Description of Event On October 1, 1986, with Unit 2 in refueling shutdown, while performing a Load Shed Test, which results in power being cut off to the CCW Pumps, suction to the Low Pressure Service Water (LPSW)
pumps was lost about an
hour and a half into the test due to a loss of prime in the CCW siphon flo The LPSW pumps take suction from Condenser Circulating Water (CCW) crossover lines between Units 1, 2 and CCW lines supply cooling water to the condenser During subsequent testing during the evening of October 1, it was determined that gravity flow following load shed of the CCW pumps not only could not be maintained, but probably had not been established. Gravity flow relies on a siphon effect aided by vacuum pumps and, when needed, steam air ejector Technical Specification 3.4.5 requires that if the ECCW system becomes inoperable during operation above 250 degrees Fahrenheit, and the system is not restored to operable status within seven days, then the unit shall be brought to hot shutdown within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and below 250 degrees within another 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. Testing of Unit 2 determined that failure to establish ECCW flow was due to air inleakage which could not be repaired on an operating uni At 9:00 a.m. on October 2, shutdown of Units 1 and 3 was initiated and cold shutdown was reached within the allotted tim The CCW systems for all three units are tied together by crossover lines and valves. During normal operation the three systems are isolated from each other by valves, to reduce the threat of turbine building flooding in the event of a CCW line ruptur During station blackout events, after 20 seconds heat is removed by recirculating emergency feedwater using the main condenser via the turbine bypass valves with the gravity flow system providing continuous condenser coolin Therefore, the licensee shut down all three units since testing and safety evaluation determined that the plant might not meet requirements for the design basis acciden When the load shed test was performed on October 1, the CCW lines were isolated. Units 1 and 2 cooling was being supplied by two low pressure service water (LPSW)
pumps taking suction from the Unit 2 crossover lin CCW flow was being supplied by one of the four CCW pumps. This CCW pump was load shed during performance of the surveillance test. Normally in this situation, the CCW pump discharge remains open and gravity flow is established automatically, providing adequate water supply for the two LPSW pumps indefinitel However, during this test, the Unit 2 condenser emergency discharge valve was closed and in pull to lock position, effectively blocking condenser gravity drain, since this was not part of the tes Due to an anomaly which occurred during the load shed test, the plant remained in the post test configuration considerably longer than norma After 70 minutes, alarms were received which were associated with LPSW and HPSW header pressures. Also, systems in Units 1 and 2 being cooled by LPSW indicated rising temperatures. Operators reacted to open crossover valves between Units 1 & 2 and to start a CCW pump on Unit Systems were essentially normal in about 10 minute During the evening of October 1 the test was repeated but this time the gravity drain feature was also tested. The results were virtually the same,
with indications that LPSW flow would be lost within a relatively short period of tim Cooling water for Oconee is supplied by Lake Keowee, which has a normal full pond level of 800 feet above sea leve Each unit is supplied by four CCW pumps feeding a common header. While the pump motors are above 800 ft., the shaft extends downward to 760 feet where the impellers are mounted. At 791 feet the pump discharge piping is suspended from a nonbolted flange. The CCW crossover lines connect to the main CCW lines underground, inside the plant fence, at elevation 770 ft. -CCW flow is through the condensers and return to Lake Keowee. The high point of the CCW lines is just down stream of the pumps at elevation 800.5 f The ECCW lines take off from the discharge side of each condenser at elevation 789 feet and, in a common line, empty into the Keowee tailrace at 730 f The unbolted flange from which the intake line and pump are suspended is normally nine feet below the surface of Lake Keowee when it is at full pon However, due to drought conditions in the southeast, on October 1 Keowee was at about 785 feet, or six feet below the flang Technical Specifications permit plant operation with lake levels as low as 775 fee During operation at reduced lake levels, water leakage at the flange has been observed. The amount of water leakage was insignificant during plant operation; however, since ECCW depends on a siphon, air inleakage would easily stop the water flo Early action taken by the licensee was to remove the CCW pump motors and lift the pumps on 10 of the 12 CCW pumps, having one pump operable for Units 1 and 2, and one for Unit 3, or with crossover lines to supply all three units. An "0" ring and sealant was installed in the flange of one pum Gravity flow was established and continued for several hours, demonstrating that the flange was at least the major source of air inleakage; however, the temporary seal deteriorated after a few hour No other sources of inleakage were identifie A permanent fix was made on the Unit 2 pumps with a steel skirt welded to the upper pipe and a 3/8x4x4 inch angle rolled and welded to the lower pip These were joined by a 3/8" thick rubber boot, banded and bolted to the skirt and angle bea A meeting was held in the Region II offices on October 8 with the licensee, NRR, and Region II participating to discuss actions being taken and planned by the licensee to repair and demonstrate operability of the plant. Actions to be taken and required conditions prior to restart of the units were also discusse System Testing after Repairs At 10:00 on October 9 to 2:00 October 10, an ECCW Gravity Flow test was conducted on Unit Three LPSW pumps were in service taking suction from Unit 2 and no vacuum priming was used. A valving error at the
beginning of the test lost condenser water box vacuum, but the test was continued with degraded tailrace flow. At the start of the test, LPSW flow was 22,000 gpm and this flow was continued throughout the tes Tailrace flow was 1200-1400gpm. Vacuum at the intake structure was 13"Hg at the beginning of the test and had decayed to 11 1/2" when the test was terminated four hours late The calculated minimum vacuum required to sustain siphon flow was 9.14 "H Another test began at 6:00 on October 10 under the same conditions except that there was no valving error and condenser water box vacuum was not los LPSW flow was 22,000 gpm and tailrace flow was approximately 22,000 gpm. Vacuum at the intake structure was 13" Hg at initiation of the tes At 11:00 a.m.,
with flows essentially the same, LPSW flow was transferred to Unit 1, and HPSW pumps were shut dow Tailrace flow remained at approximately 22,000 gp By 3:00 p.m.,
tailrace flow had decreased to about 20,000 gpm and vacuum at the intake had decayed to 9 1/2" H The test was then terminate The tests described above appear to have satisfactorily demonstrated that condenser gravity flow can be established under blackout conditions and that LPSW flow and condenser cooling can be maintained by gravity flow on Unit The initial CCW Gravity Flow test on Unit 1 was conducted on October 1 During the test LPSW pump suction was being taken from the Unit 2 CCW piping, the normal lineup during station operation. During the test gravity flow was maintained for the entire duration but at the tail race flow rates were judged to be less than adequat Air leakage around CCW pump shaft seals were thought to be the cause of the reduced flow rates (approximately 10,000 gpm).
Following repair of the shaft air leakages, the test was repeatec twice on October 13. In each case the flow rates to the discharge tailrace began at acceptable rates (exceeding 20,000 gpm)
but degraded significantly within several hours. Both times the test staff found that the condenser water box vacuum was decreasing, causing the flows to be reduced. Air inleakage was found at a CCW vent on the piping downstream of the normal condenser discharge valve On the evening of October 14 the Unit 1 test was repeated, this time with the CCW flow to the condensate coolers isolated. Flow rates for this test met all acceptance criteri Tailrace flows were maintained in excess of 19,000 gpm during the 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> test duratio Normal condensate cooler flow is from a 30" line off the 153" CCW condenser inlet pipe, through the condensate coolers, discharging back into the CCW piping between the condenser outlet valves and the CCW vent where air inleakage occurred during the previous two test The condenser outlet valves close on loss of CCW pumps in order to set up gravity flow through
the condenser emergency discharge lines. Additionally, on loss of CCW pumps the isolation valve for the vent on the condenser CCW discharge line is designed to open in order to prevent water hammer which could occur from any back flow in the condenser discharge when the outlet valves clos Because there is no longer a significant driving force through the condensate coolers when the CCW pumps are off, and there is an elevation difference of greater than 30 feet between the condensate cooler inlet and the vent off the condenser discharge piping, it is thought that reverse flow is induced in the condensate coolers when the CCW pumps are stoppe Reverse flow continues, with air inleakage through the vent valves, causing air inleakage to occur to the condenser waterbox inlet, such that vacuum is lost several hours into the test. The licensee is evaluating information obtained during the test to determine corrective actions to prevent loss of water box vacuum which could occur when gravity flow is require The CCW Gravity Flow test was conducted for Unit 3 on October 14 with acceptable results. During the test the Unit 3 LPSW was supplied from Unit 3 CCW. Flow rates of greater than 13,000 gpm were maintained throgh the LPSW system and at the tailrace greater than 19,000 gpm was maintained during the test. During the test CCW flow through the condensate coolers had been isolate Conclusions Licensee response to discovery that gravity flow had not been attained on Unit 2 was prompt and thorough in that Units 1 and 3 were shut down from full power since it could not be verified that Units 1 and 3 could operate LPSW pumps upon loss of CCW pump Repairs to all 12 pumps have been completed as of the end of this report period. Unit 2 is expected to be in hot shutdown by midnight October 1 Several items will remain open pending further review to determine possible enforcement action. Unresolved items or followup items currently known are described belo UNR 50-269,270,287/86-26-03 Questionable design of ECCW syste It appears that gravity (or siphon) flow could not have been established in the system as originally designed and built, due to the potential for air in leakage at the suction pipe join b. UNR 50-269,270,287/86-26-04 Inadequate procedures and testing to verify gravity flow. It appears that the ECCW tests were not of sufficient duration to determine that gravity flow was establishe Since the volume of water in the CCW lines provided LPSW flow of at least 15,000 gpm for over an hour on October 1, it appears *that testing personnel, in the past, had been misled into thinking gravity flow had been establishe c. UNR 50-269,270,/86-26-05 Inoperable high point vacuum line In determining reasons why gravity flow could not be established on Unit 2, the licensee found that the buried high point vacuum lines on Units 1 and 2 contained blind flange These vacuum lines aid in esta blishing and maintaining gravity flow. The blind flanges probably had been in place since construction testing. They would tend to indicate that a proper vacuum had been attained and would help to mask failure of gravity flo d. IFI 50-269,270,287/86-26-06 Licensee corrective actions to ECCW operability. Based on discussions with the NRC and through information gained during testing on all three units, the licensee is taking actions, both physically and administratively to ensure that the design basis is met at all time Final review of these is necessary to determine acceptability.