IR 05000455/1990022
| ML20217A164 | |
| Person / Time | |
|---|---|
| Site: | Byron  |
| Issue date: | 11/13/1990 |
| From: | Hinds J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | |
| Shared Package | |
| ML20217A161 | List: |
| References | |
| 50-455-90-22, NUDOCS 9011200200 | |
| Download: ML20217A164 (7) | |
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U. S. NUCLEAR REGULATORY COMMISSION
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REGION !!!
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Docket No. 50-455 License No. NPF-66 Licensee:
Commonwealth Edison Company Opus West III 1400 Opus Place Downers Grove, IL 60515 Facility Name: Byron Nuclear Power Station, Unit 2 Inspection at: Byron Site Byron, Illinois Inspection Conducted: October 2, 1990 through November 7, 1990 Inspector:
Kropp,
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Approved By.
Nudt.,
r.,
hief I \\ - IS 5.-
Reactor Projec ection 1A Date Inspection Sumary Inspection from October 2, 1990 through November 7, 1990 (Report No.
50-455/90022(DRP)).
Areat Inspected: Special, reactive safety inspection by the resident inspector to review the circumstances that pertained to the clo:;ed Unit 2 intermediate head safety injection throttle valve, 2SI8822A.
Results: One violation was identified during this inspection.
However, the violation was a licensee identified item and, in accordance with 10 CFR Part 2. Appendix C,Section V.G.1, a Notice of Violation was not issued.
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DETAILS 1.
Persons Contacted Commonwealth Edison Company
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- R. Pleniewicz, Station Manager
- G. Schwartz, Production Superintendent
- D. Winchester, Quality Assurance Superintendent
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- T. Schuster, Nuclear Licenring Administrator
- P. Johnson, Technical Staff Supervisor
- D. Brindle Operating Engineer
- D. Berg, Onsite Nuclear Safety
- M. Rauckhorst, PWR Projects Principal Engineer
- T. Johnson, Technical Staff Group Leader
- H. Snow, Regulatory Assurance Supervisor
- E. Zittle, Regulatory Assurance Staff
- E. Fuerst, Nuclear Operations, Vice President-Nuclear Staff The inspector also contacted and ir.tervie.*d other licensee and contractor personnel during the course of this inspection.
- Denotes those present during the exit interview on November 7, 1990.
2.
Purpose (93702)
This inspection was conducted to review the circumstances that pertained to the closed Unit 2 intermediate head safety injection (SI) throttle va'..e for loop "A", 2 SIB 822A. The valve was discovered closed by the
. licensee during a technical specification (TS) surveillance on September 28, 1990.
'3.
Description of the Event The licensee entered the second refueling outage for Unit 2 on September 1, 1990. During the evening on September 28, 1990, at 9:30 p.m., with no fuel in the reactor vessel, the licensee was performing TS surveillance, 2BVS 0.5-2.SI.2-1, " Safety Injection System-Valve Stroke Test". The surveillance frequency was every 18 months and could only be performed in Mode 6.
Step F 1.7 of the surveillance-procedure required verification of flow through the intermediate head Si cold leg flow check valves, 2SI8819A-D.
The flows required were to be greater than or equal to 146.4 gallons per minute (gpm). During the surveillance test, flow through valves 2SI8822A-D were measured ts verify flow through check valves 2SI8819A-D. The flows measured were:
2SI 8822A 0 gpm 2S! 8822B 148,1 gpm 2SI 8822C 152.5 gpm 251 8822D 163.3 gpm
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The licensee identified during the surveillance that valve 2 SIB 822A was
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closed. On September 29, 1990, the licensee made a containment entry for Unit 1 to verify the throttled position for all twelve Unit 1 emergency
core cooling system (ECCS) valves and determined the valves were in the correct throttle position except for valve, 1SIBB10A.
Valve, 1518810A, i
for the intermediate head 51 cold leg injection for loop "A", was open
.1" more than required. On October 1, 1990, the licensee performed a special procedure, SPP-90-20. " Unit 2 Safety Injection Cold Leg Injection
Flow Balance", to balance the intermediate head safety injection flow into the reactor coolant system cold legs.
4.
Chronology of Events
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January 14, 1989 - Mechanical Maintenance individual obtained "as-found" (throttled) micrometer neasurement for throttle valve 2 SIB 822A per NWR B 64048. Measurement was recorded on NWR as.09S inches.
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January 16,.1989 - Shift authorization to commence work on check valve, 2518819A, which was located downstream of 2 SIB 822A.
Valve 2 SIB 822A, was used as an isolation point to
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work on valve, 2SI8819A.
The out-of-service position for valve 2SI8822A was closed.
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January 24,.1989 - Work on valve, 2S:8819A completed by mechanical contractor.
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February 12, 1989 - Surveillance, 28VS 0.5-2.51.2-1, " Safety Injectior.
System Valve Stroke Test" performed to verify operability of 2 SIB 819A after maintenance work.
February _13, 1989 - Mechanical maintenance individual (different individual than on January 14,1989) per NWR 64048 obtained micrometer measurement for valve 2SI8822A
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after repositioning for the correct throttled
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position. Measurement recorded for "as-left" was
.090 inches.
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September 28, 1990 - During performance of surveillance 2BVS 0.5-2.SI.2-1, flow through valve 2SI8822A, (intermediate head loop "A" cold leg injection) was noted as 0 gpm.
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September 29, 1990 - Unit 1 containment entry by licensee personnel to verify all Unit 1 ECCS throttle valves were in the correct position.
October 1, 1990 -
Unit 2 ECCS flow balance for intermediate head cold leg injection performed in accordance with special procedure SPP 90-70, Revision 0, " Unit 2 Safety Injection Cold Leg Injection Flow Balance".
5.
Evaluation of the Event Based on the inspector's review of surveillance re ords, maintenance history, nuclear work requests (NWRs), procedures and control room logs, the inspector has concluded that the intermediate head cold leg injection
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throttle valve, 2SI8822A, had been closed from February 13, 1999; to Saotember 28, 1990. The review of the licensee's maintenance history determined that valve, 2SI8822A had no maintenance activities performed on the valve after February 13, 1989 that could have caused the misposition of-the valve to a close position. Valve, 2 SIB 822A, had been used as an isolation point in January - February, 1989, for maintenance activities described in NWR B63373 for check valve, 2SI8819A.
Prior to closing vgive 2 SIB 822A for the out-of-service (005), a mechanical maintenance individual was assigned to record the "as-found" throttled position of the valve as stipulated in NWR B64048 on January 14, 1989.
.At the time, the Byron station utilized NWRs to record the "as-found" position of ECCS throttle valves prior to manipulation for an 00S for an isolation point or maintenance activities. The same NWR would then be used to reposition the throttle valve to the "as-found" position after the 005 was lifted.
On February 13, 1989, a different mechanica?
maintenance individual was directed to position the throttle valve back to the "as-found" position as documented in NWR B64043. The position of the valve was then also recorded on NWR B64043. Due to the design of throttle valve, 2SI8822A, the throttle position was measured with a depth micrometer.
Due to the design of the valve, a 2" plug valve that has a 1" stem travel from full open to full close, a small change in the throttle position would significantly affect flow. Therefore, a depth micrometer was required to verify the proper throttled position for all-four intermediate head cold leg. injection valves, 2 SIB 822A(B)(C)(D), to ensure proper ECCS flow balance. The directions on NWR B64043 required the maintenance personnel to measure the distance from the top of the stem to the top of the handwheel nut. The "as-found" measurement (throttled )osition), using a depth micrometer on January 14, 1989, was
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.095".
On r bruary 13, 1989, the maintenance individual that was directed e
to return the throttle valve, 2 SIB 822A, to the "as-found" position, recorded a reading of.090" with a depth micrometer. The inspector could not ascertain the position of valve, 2SI8822A, when the measurements were
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obtained by maintenance personnel, since the 005 records for the maintenance activity on the check valve, that required the closure of valve 2518822A were not available for review. 005 records were retained for six months and then discarded in accordance with the licensee's program for record retention.
The inspector did review the results of a surveillance test, 2BVS 0.S.2.SI-2-1, " Safety Injection System' Valve Stroke Test", that was performed on February 12, 1989.
The review of the results did indicate that throttle valve, 2SI8822A was open on February 12, 1989; since flow through check valve, 2 SIB 819A was obtained.
However, the performance of this surveillance was probably accomplished by opening valve 2SI8822A by a temp lift of the 005 with the valve returned to the 00S position (closed) after the surveillance.
The inspector could not confirm this scenario since temp lif records were only retained for six months.
Through discussions with the station's technical staff, the inspector determined that with throttle valve, 2 SIB 822A, fully closed, a micrometer reading of.090 inches was obtained on September 29, 1990 (height of the r
stem was below the reference point which was the handwheel nut).
Valve, 2 SIB 822A was the only ECCS throttle valve where the stem height could be below the handhweel nut when the valve was throttled or fully closed.
This could have resulted in maintenance personnel positioning the
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throttle' valve 2 SIB 822A on February 13, 1989, in the closed position by mistake since the directions on NWR 86/043 did not provide clear instructions (minus or plus.095) in regards to stem position versus
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reference point (handwheel nut).
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6.
Corrective Actions Initiated by the Licensee t
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When throttle valve, 2SI6822A, was found closed on September 28, 1990, the licensee made a Unit 1 containment entry to inspect all ECCS injection throttle valves for correct position. All twelve valves (4 for
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high head injection, 4 for intermediate head injection and 4 for hot leg injection) were in the correct position except valve, 1 SIB 810A, the high head cold leg injection which was open.1 inches more than required by procedure, BVP 900-4, " Unit 1 ECCS Throttle Valve Position Measurement".
All Unit 1 ECCS systems were considered operable by the licensee.
In addition,.the licensee verified the correct position of Unit 2 ECCS throttle valves for high head injection and hot leg injection and y
)erformed a ECCS flow balance on October 1, 1990, for the intermediate lead cold leg injection using special procedure SPP 90-70. The licensee also will tack weld all 12 ECCS injection throttle valves in the correct throttled position.
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Prior to identifying throttle valve, 2SI8822A, closed on September 28, 1990, the licensee had :lready issued new procedures to i
e tablish a consistent methodology and recording for ECCS throttle valve pos'tions. The procedures eliminated the need for NWRs to document
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"as-f a nd" and "as-left" throttle valve positions to cupport the DOS program.
The procedures were BVP 900-4, Revision 0, " Unit 1 ECCS Throttle Valve Position Measurement", approved February 7, 1990, and BVP 900-5, Revision 0, " Unit 2 ECCS Throttle Valvo Position Measurement",
approved August 30, 1990. Both procedures establish acceptance criteria for throttle valve position, the method for obtaining the micrometer
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readers and require dual verification of proper positions which was not i
performed previously when NWRs were used to ensure proper throttle valve position. However, procedures BVP 900-4 (Unit 1) and BVP 900-5 (Unit 2)
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were not consistent in measuring techniques and the licensee plans to
revise these procedures to provide a clear uniform method.
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Conclusion The inspector could not definitely establish the root cause for ECCS throttic valve, 2 SIB 822A, being closed from February 13, 1989 to September 28, 1990.
However, the following weaknesses were identified with the methodology used in January - February, 1989 to ensure valve 2SIBB22A'was in the correct throttled position after maintenance activities:
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There was no dual verification to ensure valve 2SI8822A was in the
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correct throttled position.
Directions on NWR B64043 to obtain "as-found" and "as-left"
positions for valve 2SI6822A were not clear since the valve was the only(ECCS throttle valve where the stem could be below the handwheel nut reference point for micrometer) and still be throttled.
Both of these weaknesses have been addressed by the issuance of new
. procedures that delineate the methodology for ensuring proper position for ECCS throttle valves. These procedures were approved prior to the licensee identifying throttle valve 2 SIB 822A closed on September 28.
1990..
The licensee.also requested Westinghouse to perform a safety analysis with the' intermediate head cold leg injection to loop "A" isolated.-
Westinghouse's analysis concluded that no regulatory or design limit associated with a toss of Coolant Accident (LOCA) would be exceeded.
The analysis' concluded that there would be no effect on the peak cladding
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temperature (PCT) for a large break LOCA.
However, for a small break LOCA, there would be an increase of 178 degrees F in the PCT. The 178 degrees F increase would not result in exceeding the 10 CFR 50.46 limit of 2200 degrees F (1473.1 + 178.0 =-1651.1 degrees F).
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In conclusion, the failure to have a ECCS balance flow through the i
intermediate head cold leg injection lines due to valve 2518822A being
closed is a violation of Technical Specification.
However, since this
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was a licensee identified item with limited safety consequence and in i
accordance with 10 CFR Part 2. Appendix C,Section V.G.1, a Notice of Violation was not issued.
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Exit Interview (30703)
The inspectors met'with the licensee representatives denoted in o'
paragraph 1 during the inspection period and at the conclusion of the
inspection on November 7, 1990. The inspectors summarized the scope and
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E results of the inspection and discussed the likely content of this
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inspection report.
The licensee acknowledged the information and did not
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E indicate that any.of the informaticn disclosed during the inspection
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could be considered proprietary in nature.
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