05000237/LER-2002-005, Pressure Switches Found Above Technical Specification Allowable Values
| ML022200456 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 08/02/2002 |
| From: | Hovey R Exelon Nuclear |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| RHLTR: #02-0059 LER 02-005-00 | |
| Download: ML022200456 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 2372002005R00 - NRC Website | |
text
Exekon.
Exelon Generation Dresden Generating Station 6500 North Dresden Road Morris, IL 60450-9765 Tel 815-942-2920 www exeloncorp.corn Nuclear 10 CFR 50.73 August 2, 2002 RHLTR: #02-0059 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Dresden Nuclear Power Station, Unit 2 Facility Operating License No. DPR-19 NRC Docket No. 50-237
Subject:
Licensee Event Report 2002-005-00, "Pressure Switches found above Technical Specification Allowable Values" Enclosed is Licensee Event Report 2002-005-00, "Pressure Switches found above Technical Specification Allowable Values," for the Dresden Nuclear Power Station (DNPS). This event is being reported in accordance with 10 CFR 50.73(a)(2)(i)(B), "Any operation or condition which was prohibited by the plant's Technical Specifications."
Corrective Actions
Pressure switches were immediately adjusted within procedure tolerances.
A review was performed on all Technical Specification related instrument maintenance procedures that test Bourdon Tube sensor type pressure switches and the identified instrument maintenance station procedures were revised to maintain operating pressure at the pressure switch during the performance of the surveillance.
Design Engineering will evaluate setpoints and tolerances for DIS 0250-03.
If you have any questions, please contact Jeff Hansen, Regulatory Assurance Manager at (815) 416-2800.
Respectfully, R. J. Hov F-Site Vi President
'L Dre en Nuclear Power Station
U.S. Nuclear Regulatory Commission August 2, 2002 Page 2 Enclosure cc:
Regional Administrator - NRC Region Ill NRC Senior Resident Inspector - Dresden Nuclear Power Station
Abstract
On June 4, 2002, the Instrument Maintenance Department (IMD) began performance of monthly calibration surveillance for the pressure switches associated with reactor pressure vessel relief valves. During the performance of the surveillance IMD discovered that the pressure switch setpoint for valve 2-203-3A (as found at 1134.6 psig) exceeded the Technical Specification (TS) Allowable Value (AV) of < / = 1133.5 psig. The pressure switch was readjusted to within as left tolerances per station procedure. Following calibration of the pressure switch for valve 2-203-3A, IMD began the calibration for pressure switch associated with valve 2-203-3B and discovered that the pressure switch setpoint (as found at 1110.6 psig) exceeded the TS AV of < / = 1110.5 psig. The pressure switch was readjusted to within as left tolerances per station procedure. The remaining three pressure switches were tested and found to be within the TS required AV.
The cause of this event was determined to be deficient procedural instruction. A review was performed on all Technical Specification related instrument maintenance procedures that test Bourdon Tube sensor type pressure switches and the identified instrument maintenance station procedures were revised to maintain operating pressure at the pressure switch during the performance of the surveillance. The as-found condition of the two (2) pressure switches would have resulted in a slight delay in the opening of their associated reactor pressure vessel relief valves. The as-found pressures for valve 2-203-3A and 2-203-3B were 1.1 and 0.1 psig higher than their associated TS AV, respectively. Therefore, no failure of the valves actually occurred. Both valves would have operated to mitigate reactor pressurization events. Additionally, the reactor pressure vessel safety valves were operable at the time of this occurrence to aid in the mitigation of pressure transients. At no time did this condition compromise the health and safety of the public.U.S. NUCLEAR REGULATORY APPROVED BY OMB NO.3150-0104 COMMISSION EXPIRES 07/31/2004 (7-2001)
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
FACILITY NAME (1)
DOCKET NUMBER (2) lER NUMBER (6 PAGE (3)
YEAR SEQUENTIAL REVISION Dresden Nuclear Power Station Unit 2 05000237 NUMBER NUMBER 2002 005 00 2 of 3 (If more space is required, use additional copies of NRC Form 366A)(17)
A.
Plant Conditions Prior to Event:
Unit: 02 Event Date: 06-04-2002 Event Time: 1800 CST Reactor Mode: 1 Mode Name: Run Power Level: 95 percent Reactor Coolant System Pressure: 1002 psig B.
Description of Event
This event is being reported in accordance with 10 CFR 50.73(a)(2)(i)(B), "Any operation or condition which was prohibited by the plant's Technical Specifications."
On June 4, 2002, the Instrument Maintenance Department (IMD) began performance of a monthly calibration surveillance for the pressure switches associated with reactor pressure vessel relief valves. During the performance of the surveillance IMD discovered that the pressure switch setpoint for valve 2-203-3A (as found at 1134.6 psig) exceeded the Technical Specification (TS) Allowable Value (AV) of < / = 1133.5 psig. The pressure switch was readjusted to within as left tolerances per station procedure. Following calibration of the pressure switch for valve 2-203-3A, IMD began the calibration for pressure switch associated with valve 2-203-38 and discovered that the pressure switch setpoint exceeded the TS AV of < / = 1110.5 psig (as found at 1110.6 psig).
The pressure switch was readjusted to within as left tolerances per station procedure. The remaining three pressure switches were tested in accordance with the station procedure and found to be within the TS required AV.
C.
Cause of Event
During the performance of the pressure switch calibration procedure, test pressure is reduced to zero after "as-found" data is collected and before the pressure switch is calibrated. This current practice of reducing pressure to zero has been determined to promote instrument drift. These pressure switches utilize a 50-1200 psig range Bourdon Tube sensor. The practice of reducing pressure allows the Bourdon Tube sensor to fully relax. Relaxing of the Bourdon Tube sensor creates a shift in the Bourdon Tube sensor elasticity that promotes setpoint drift.
The cause of the event was determined to be procedure instruction deficiency which reduces test pressure to zero after 'as found' data is collected and before the pressure switch is calibrated which promotes instrument setpoint drift. (NRC Cause Code D)
D.
Safety Analysis
The as-found condition of the two (2) pressure switches would have resulted in a slight delay in the opening of their associated reactor pressure vessel relief valves. The as-found pressures for valve 2-203-3A and 2-203-3B were 1.1 and 0.1 psig higher than their associated TS AV, respectively. Therefore, no failure of the valves actually occurred. Both valves would have operated to mitigate reactor pressurization events. Additionally, the reactor pressure vessel safety valves were operable at the time of this occurrence to aid in the mitigation of pressure transients. At no time did this condition compromise the health and safety of the public.U.S. NUCLEAR REGULATORY APPROVED BY OMB NO.3150-0104 COMMISSION EXPIRES 07131/2004 (7-2001)
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
FACILITY NAME (1)
DOCKET NUMBER (2)
LER NUMBER l6 R PAGE (3)
YEAR SEQUENTIAL I REVISION Dresden Nuclear Power Station Unit 2 05000237 l
NUMBER NUMBER 2002 005 00 3 of 3 (If more space is required, use additional copies of NRC Form 366A)(17)
E.
Corrective Actions
Pressure switches were immediately adjusted within procedure tolerances.
A review was performed on all Technical Specification related instrument maintenance procedures that test Bourdon Tube sensor type pressure switches and the identified instrument maintenance station procedures were revised to maintain operating pressure at the pressure switch during the performance of the surveillance.
Design Engineering will evaluate setpoints and tolerances for DIS 0250-03.
F.
Previous Occurrences
None G.
Component Failure Data
N/A