IR 05000269/1987016
| ML16161A809 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 04/30/1987 |
| From: | Bryant J, Peebles T, Wert L NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML16161A808 | List: |
| References | |
| 50-269-87-16, 50-270-87-16, 50-287-87-16, NUDOCS 8705190202 | |
| Download: ML16161A809 (8) | |
Text
REc NUCLEAR4UNITED STATES
'NUCLEAR REGULATORY COMMISSION
REGION II
101 MARIETTA STREET, Z
~ATLANTA, GEORGIA 30323 Report Nos. 50-269/87-16, 50-270/87-16 and 50-287/87-16
.Licensee:
Duke Power Company 422 South Church Street Charlotte, N.C. 28242 Facility Name:
Oconee Nuclear Station Docket Nos.:
50-269, 50-270, and 50-287 License Nos.:
DPR-38, DPR-47, and DPR-55 Inspection Conducted:
April 16 - April 28, 1987 Inspectors:
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J. C. Bryant Date Signed L. D. Wert-fT Date Signed Approved by:
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T. A. Peebles, Section Chief Date Signed Division of Reactor Projects SUMMARY Scope:
This special, announced inspection involved on-site resident inspection of events surrounding two violations of Technical Specifications during startup of Unit 3 and related activities of Units 1 and Results:
In the areas inspected, two violations were identified; failure to maintain two independent high pressure injection (HPI) trains operable with the reactor coolant system above 3500 F and failure to maintain two independent reactor building cooling units operable when the reactor coolant system was at greater than 2500 These violations are being considered for escalated enforcement: Technical Specification 3.3.1 states that when the reactor coolant system (RCS)
is above 350 degrees F and reactor power less than 60% full power, two independent trains, each comprised of a high pressure injection (HPI)
pump and a flow path capable of taking suction from the borated water storage tank (BWST) shall be operabl PDR ADOCK 05000269
At 10:30 am on April 10, 1987, the reactor was heated above 350 0 F with the reactor at zero power while both suction valves from the BWST to the HPI pump suction were closed with power supply breakers to the valves open and tagged out, making both trains inoperable. The condition was noted by the licensee at 7:00 a.m. on April 11 and was corrected by 7:20 B. Technical Specification 3.3.5.b states that when the RCS, with fuel in the core, is in a condition with pressure equal to or greater than 350 psig, or temperature equal to or greater than 250 degrees and subcritical, two independent reactor building cooling (RBC)
trains, each comprised of an RBC fan, associated cooling unit, and associated engineered safety feature (ESF) valves shall be operabl On April 10, 1987, at about.6:00 a.m.,
Oconee Unit 3 was heated above 250 degrees F with the low pressure service water valves to the reactor building cooling units (RBCU)
closed, therefore rendering the RBCUs inoperable for about two hour REPORT DETAILS 1. Licensee Employees Contacted
- M. S. Tuckman, Station Manager R. L. Sweigert, Operations Superintendent
- H. R. Lowery, Shift Operating Engineer J. B. Price, Assistant Shift Operating Engineer
- C. L. Harlin, Compliance Engineer
- F. E. Owens, Assistant Engineer, Compliance R. Rogers, Chairman, Onsite Review Committee P. Forrester, Nuclear Production Engineer T. Grant, Nuclear Production Specialist P. Chudzik, Relief Shift Supervisor Other licensee employees contacted included technicians, operators, and staff engineer Resident Inspectors:
- J. C. Bryant
- L. D. Wert
- Attended exit intervie. Exit Interview The inspection scope and findings were summarized on April 28, 1987 with those persons indicated in paragraph 1 above. One apparent violation of Technical Specification (TS) 3.3.1 and one apparent violation of TS 3. were identified for possible escalated enforcement actio The licensee did not identify as proprietary any of the materials provided to or reviewed by the inspectors during this inspectio. Plant Operations Fouling of decay heat removal (DHR)
coolers and reactor building cooling units (RBCU, has necessitated restricted operations of all three Oconee reactors in the past mont All three units were placed under a Confirmatory Order on April 10, 1987, due to cooler problem Oconee Unit 1 has been limited to 88 percent power due to the reduced capacity of a temporary main transformer in service, and thus has not been restrained by the Order, which restricts power to about the same leve On April 1, 1987, Unit 2 was reduced to 65 percent power due to degraded heat removal capability of RBCUs and DHR cooler On April 2, 1987, cleaning of the 2A DHR cooler was completed and power was increased to 77 percent. On April 6, 1987, Unit 2 was shut down for efficiency testing of the 2A DHR cooler. During that shutdown, a non-isolable leak was found on a reactor vessel level indication system (RVLIS) instrument line resulting in the declaration of an Unusual Even This incident will be discussed further in NRC Inspection Report No. 50-270/87-13. Necessary repairs were made, the DHR coolers were tested and found acceptable for full power operation, and the unit was placed on line on April 11, 198 Power was restricted to 87 percent, however, due to high steam generator water level Unit 3 underwent extensive cooling unit cleaning and testing during a recent refueling outage in which the main generator was disassembled and rebuilt. The unit was taken critical on March 30, 1987, and the turbine generator was placed on line for electrical testing and bearing check Following verification of generator performance, the unit was taken off line at 4:30 p.m. that afternoon and the reactor was taken to hot shutdown to facilitate generator bearing alignment and further cooling unit testin Unit 3 Shutdown To Repair Leak On March 31, 1987, at 3:50 p.m. with Unit 3 in hot shutdown, a leak was detected i the recently installed RVLIS instrumentation piping. The leak was less than one gallon per minute, but was in a 3/4 inch diameter line tapping into the low pressure injection suction drop line and was non-isolable. It was initially believed that the reactor would have to be defueled and drained in order to repair' the lea In that vein, a cooldown to cold shutdown was initiated according to Procedure N OP/3/A/1102/10, the controlling procedure for Unit Shutdow Enclosure 4.9 to that procedure Shutdown Tagging List, was initiate This enclosure is normally performed when shutting down for refuelin When the unit was below 350 degrees F, valves 3HP-24 and 3HP-25, (HPI pump suction valves from the BWST), were deactivated by opening and red tagging the breakers supplying power to the valve operator The valves are normally closed except during an engineered safety features (ESF)
actuatio By 7:00 on April 1, 1987, the unit was in cold shutdow At 3:30 a.m. on April 2, Enclosure 4.9 was complete The licensee then determined that the RVLIS system leak could be repaired wet, that is, without defueling and draining the reacto The repair and welding procedures were discussed with the inspector and activities directed toward defueling and draining the reactor were terminate Preparations for Reactor Startup On April 4, 1987, repairs to the RVLIS instrument line were completed and on April 5, OP/3/A/1102/1, the controlling procedure for unit startup, was initiated at the point reached during shut down for defueling and drainin a. Heatup With HPI Isolated At 2:45 on April 9, 1987, Step 4 of Enclosure 4.4 to the referenced procedure was signed off signifying that all red tags which would affect unit heatup were cleare Red tag stubs are kept in the Unit Supervisor's office. As required, tags are removed from the office and actions taken to clear the ta They are then signed off in the red tag lo Approximately 200 red tags were installed, then cleared and signed off in the log between March 31 and April 1 Fifty-two red tags remained outstanding at the time review was required by the startup procedure. All red tags required for startup were then cleared except for 3HP-24 and 2 On April 10, 1987, at 10:00 a.m.,
Unit 3 was at 340.5 degrees F and at 11:00 it was at 359.4 0 Apparently at about 10:30 a.m. it exceeded 350 Technical Specification 3.3.1 states that, when temperature is above 350 degrees F and reactor power is below 60 percent of full power, two independent HPI trains shall be operabl Since later developments revealed that 3HP-24 and 25 valve operator breakers were open and tagged out, the HPI system was not capable of taking suction from the BWST. In the event of an ESF signal, the HPI pumps could have taken suction from the letdown storage tank for only a few minutes, then they would have pumped dry if the closed path from the BWST had not been opene Indications Available To and Checks Made By Operators OP/0/A/1102/20, Enclosure 5.4, Shift Turnovers Checklist, RCS temperature >250 degrees F to Just Prior to Criticality, Step 3.1.1, states, " If RCS temperature >3500 F, verify two HPI pumps and two HPI trains operable."
This procedure is performed by the reactor operator in about the last hour of each shif When performed between 6-7:00 on April 10 and 6-7:00 on April 11 the checklist indicated the systems were operabl However, this is simply a check of the removal and restoration log and of completed files to determine if anything has changed since the last time the check list was performed. On that basis, the two operators involved did not err in calling the systems operabl Valves 3HP-24 and 25 have their positions indicated by red and green lights on the ESF pane The closed light was lit on both valves indicating the correct positio However, these lights are not powered by the breakers that were left ope On the reactor operator's console, valve 3HP-24's position and control lights are powered from the breaker that was ope On a console light cheEk sheet performed on the night shift from 7:00 April 10 to 7:00 a.m., April 11, valve 3HP-24 was shown as having no indication. This check sheet is performed early in the shift by a nuclear equipment operator (NEO) on his rounds. The check sheets are reviewed by the Unit Superviso For 3HP-24 neither the "G" or "R" (Green or Red) was checked; a line was drawn through them and it was initialed by the NE Other valves had the "G" or "R" checked, with no line or initial Apparently the Unit Supervisor failed to detect the anomal In addition to the above, each shift prints out a summary of computer alarms which have been placed in a mode in which they are not displayed continuously on control room screen This summary is called the "Operator Ignore Summary" or "No Alarm Check" and it is reviewed on each shift to verify that any alarms placed in that mode properly belong there. These alarms are placed in the no alarm mode for equipment that is not in service due to plant status, in order to prevent unnecessary alarm The position of 3HP-24 and 3HP-25 breakers had been placed in this status when the breakers were opened during unit cooldow These printouts are not retained as permanent record The condition of valve 3HP-24 and 25 breakers should have been detected at 7:00 p.m. on April 1 Upon reviewing the "No Alarm" list, the oncoming operator at 7:00 a.m. on April 11 noticed that the breakers for valves 3HP-24 and 25 showed "bad coil" which is the proper alarm when de-energized. He immediately checked the reactor operator's console and found that 3HP-24 indicated no powe He took immediate corrective action and the breakers were closed at 7:20 a.m. when the red tags were cleare The red tags stubs for the two valves were found later on the control room desk under other paper It is assumed they were removed from the Unit Supervisors box, prior to heat up, for the purpose of having them cleared and the breakers close b. Reactor Building Cooling Isolated During Heatup On April 27, 1987, in reviewing completed testing of the reactor building cooling units (RBCU), the licensee determined that there had been another apparent violation of TS during heatup of Unit 3 on April 1 TS 3.3.5 b requires that when the reactor is above 250 degrees F, two independent RBC trains, each comprised of an RBC fan, associated cooling unit, and associated ESF valves shall be operabl On April 10, 1987, Unit 3 was at 2500 F at 6:00 a.m., with all three RBCU cooler low pressure service water (LPSW)
systems isolate The condition was corrected at 7:30 Thus, for over an hour, the requirements of TS 3.3.5 b were not me Apparently the sequence of events which led to the violation was as fol lows:
o A work list was provided by day personnel to the shift on April Item 2 of the work list stated that Performance would be doing an LPSW flow test on RBCUs, and that afterward the RBCUs could be declared operabl Item 3 of the work list stated that after the flow test was completed, LPSW flow to cooling units should be cut off and the reactor building (RB)
heated. Item 4 of the work list stated that the RB needed to be heated to allow Performance to test RBCU efficiency. It added that the test had to be reviewed by Design before exceeding hot shutdow o It was believed that the RBCU LPSW outlet valves, which open on an Engineered Safeguards (ES)
signal, were leaking through; therefore, in order to heat up the building more rapidly, the RBCU inlet valves (nonES) were also closed at 5:00 p.m. on April Procedure OP/0/A/1102/6, Enclosure 3.1, Removal of Station Equipment (R&R) was execute o The Shift Supervisor and Unit Supervisor were aware of the R&R, but did not review i They were aware that the cooling units were performance tested on April 9, 1987, and declared operabl They assumed that the R&R applied to the outlet (ES)
valves only. The reactor operators stated that they were aware that the inlet valves were closed and that they would have to open them in the event of an ES actuatio They were not aware that the supervisors did not understand the situatio They stated that they were also aware that they could not go above hot shutdown until the RCBU efficiency test was complete They added that this led them to believe that it was alright to leave the RCBUs isolated until the test and therefore past the 250 degrees platea o The error was detected by the on coming reactor operator at 7:00 a.m. on April 10, 1987, and correcte The duty engineer was informed of the possible TS violation and that the operators had been aware that they would have to open the valves in the event of an ES signa He discussed this with his supervisors and Compliance. They concluded that it was not a TS violation since there was an R&R and the operators would have opened the valves on an ES actuatio This position would have been correct had there been a prior safety review made and documented and the operators specifically directed to open the valves upon an ES signa The licensee's review on April 27, determined that the evaluation was not correct, since there had been no safety review and no formal instruction to the operator The licensee reported the apparent violation to NRC according to Part 50.72 (iii)(B).
6 Licensee Investigation The licensee's investigation began on Saturday, April 11, shortly after discovery of the closed HPI valves and the Safety Review Group began its investigation at that tim Conclusions have not yet been finalized. The supervisor and operator errors in failing to detect the closed valves are obvious, as is the failure of licensed personnel in the control room to detect the absence of indication on 3HP-24 during their routine duties, and the inadequate communications concerning the RBCU The procedure control system is being reviewed to determine if changes are needed for unusual conditions such as this; that is, the reactor was being taken to refueling shutdown, but instead only went to cold shut dow However, procedures were in use which should have started up the unit properl The review group is investigating the possibility that the startup of Unit 3, shutdown for testing, shut down to refuel, changed to cold shutdown, coupled with the shut down and startup of Unit 2 along with the Confirmatory Order created unusual pressures on the operations staff which were not properly considered in startup plannin It also appears that the staff did not provide a clear path for operational personnel, leaving too much to be reviewed and determined by operations. The possible impact of pressure to get the units on line is also being considere. Inspection Findings Heating Unit 3 above 250 degrees F with the RBCUs isolated and above 350 degrees with the HPI system isolated are violations of Technical Specification Though there were two events, they did not occur simultaneously; that is, the RBCU problem was corrected about three hours before heatup reached the point that the HPI system was in violatio Although the licensee identified the situations, corrected them when identified, and reported them to the NRC, opportunities were missed to detect them before and after the violation They reflect a hurried and improperly coordinated operatio In that vein, the above described events constitute violations 50-287/87-16-01, failure to maintain two independent high pressure injection operable when the RCS was above 350 0 F and 50-287/87-16-02, failure to maintain two independent reactor building cooling units operable when the reactor coolant system was greater than 2500F.