05000499/LER-2002-001, Gaseous Waste Processing System Oxygen Monitor Automatic Trip Inoperable on 01/17/2001
| ML021080361 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 04/10/2002 |
| From: | Halpin E South Texas |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NOC-AE-02001301, STI:31427986 LER-02-001-00 | |
| Download: ML021080361 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 4992002001R00 - NRC Website | |
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April 10, 2002 NOC-AE-02001301 File No.: G25 10CFR50.73 Sfl: 31427986 U. S. Nuclear Regulatory Commission Attention: Document Control Desk One White Flint North 11555'Rockville Pike Rockville, MD 20852 South Texas Project Unit 2 Docket No. STN 50-499 Licensee Event Report 02-001 Gaseous Waste Processing System Oxygen Monitor Automatic Trip Inoperable.
Pursuant to IOCFR50.73, South Texas Project submits the attached Unit 2 Licensee Event Report 02-001 regarding the discovery that the Gaseous Waste Processing System Oxygen Monitor Automatic Trip function was inoperable for approximately 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />, which exceeds the allowed outage time in Technical Specification 3.3.3.11.
This event did not have an adverse effect on the health and safety of the public.
If there are any questions on this submittal, please contact W. R. Bealefield, Jr. at (361) 972-7696 or me at (361) 972-7849.
E. D. Halpin Plant General Manager Attachment: LER 02-001 (South Texas, Unit 2)
NOC-AE-02001301 Page 2 of 2 cc:
(paper copy)
(electronic copy)
Ellis W. Merschoff Regional Administrator, Region TV U.S. Nuclear Regulatory Commission 611 Ryan Plaza Drive, Suite 400 Arlington, Texas 76011-8064 U. S. Nuclear Regulatory Commission Attention: Document Control Desk One White Flint North 11555 Rockville Pike Rockville, MD 20852 Richard A. Ratliff Bureau of Radiation Control Texas Department of Health 1100 West 49th Street Austin, TX 78756-3189 Cornelius F. O'Keefe U. S. Nuclear Regulatory Commission P. O. Box 289, Mail Code: MNI16 Wadsworth, TX 77483 A. H. Gutterman, Esquire Morgan, Lewis & Bockius LLP M. T. Hardt/W. C. Gunst CityPublic:Service -
Mohan C. Thadani U. S. Nuclear Regulatory Commission R. L. Balcom/D. G. Tees Reliant Energy, Inc.
A. Ramirez City of Austin C. A. Johnson/A. C. Bakken m AEP - Central Power and Light Company Jon C. Wood Matthews & Branscomb C. M. Canady City of Austin Electric Utility Department 721 Barton Springs Road Austin, TX 78704
Abstract
During a review of narrative logs maintained by Gaseous Waste Processing System (GWPS) operators, an incidentwas Identified in Unit 2 where, on January 17, 2001, the GWPS Inlet Header Valve and Discharge Flow Valve control handswitches were left In the "OPEN" position for longer than four hours.
This configuration made the automatic trip feature of the oxygen monitor for the GWPS inoperable.
Technical Specification 3/4.3.3.11 states, "The explosive gas monitoring system instrumentation channels shown in Table 3.3-13 shall be OPERABLE with their Alarm/Trip Setpoints set to ensure that the limits of Specification 3.11.2.5 are not exceeded." Specification 3.11.2.5 limits the concentration of oxygen In the GWPS inlet to less than or equal to 3% by volume. The explosive gas monitoring instrumentation must be capable of performing its function automatically to be considered operable.
When the control handswitches for the inlet and discharge valves are in "OPEN", the automatic trip function of the oxygen monitor is bypassed and the instrumentation should be declared inoperable.
Four hour grab samples must be taken and the samples analyzed within the following four hours or the GWPS must shut down. No documentation could be found to show that the samples were taken or analyzed. The handswitches for the inlet and outlet control valves in this event were in the "OPEN" position for approximately 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> before being placed in the "NORMAL" position which restored the automatic trip function.
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(If more space is requird, use additional copies of logbook entry dated January 17, 2001, indicates the GWPS inlet and outlet valve control handswitches were placed In the "OPEN" position and remained In that position for approximately 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> with process flow present. The Mechanical Auxiliary Building operators in this event were interviewed, but could not provide any additional Information and they could not remember if the handswitches were periodically placed back in the-
"NORMAL" position. The logbook documents the GWPS being placed in operation at 2130 on January 16, 2001 with the inlet and outlet flow valve handswitches in the 'OPEN" position. The next entry in the logbook pertaining to the GWPS was at 0930 on January 17, 2001 stating that GWPS was placed In "AUTO".
Technical Specification 3.3.3.11 states: "The explosive gas monitoring instrumentation channels shown in Table 3.3-13 shall be OPERABLE with their Alarm/Trip Setpoints set to ensure that the limits of Specification 3.11.2.5 are not exceeded." Action b. of T/S 3.3.3.11 states: "With less than the minimum number of explosive gas monitoring instrumentation channels OPERABLE, take the ACTION shown in Table 3.3-13." Table 3.3-13 requires the Oxygen monitor (Process) to be OPERABLE during GASEOUS WASTE PROCESSING SYSTEM operation with ACTION "51" to be taken if It is not operable. ACTION "51" states: 'With the number of channels OPERABLE less than required by the Minimum Channels OPERABLE requirement, operation of this GASEOUS WASTE PROCESSING SYSTEM may continue provided grab samples are collected at least once per 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> and analyzed within the following 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />."
Based on the logbook entries and the lack of any record of grab samples being taken or analyzed, the requirements of T/S 3.3.3.11 for the GWPS were not met for a period of 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> on January 17, 2001.
This event was determined to be reportable In accordance with 10CFR50.73(a)(2)(i)(B), "Operation or condition prohibited by technical specifications n A licensee event report is required if the condition lasted longer than permitted by the T/S without the required compensatory action taken.
NRC, (if more space Is required, use additonal copies of NRC Form 366A) (17)
EVENT SIGNIFICANCE With the oxygen monitor inoperable, the automatic trip function of the GWPS for high oxygen levels was incapable of isolating the system. A high oxygen concentration could lead to an unsafe explosive mixture in the system. There is no record of alarms or instrument indication of high oxygen concentrations during the 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> period of this event.
The GWPS is not used to prevent or mitigate core damage accident sequences as described in the STP Probabilistic Risk Assessment (PRA). Fire detection and suppression systems were unaffected by this event. If a fire or explosion were to occur in the GWPS, a reactor trip would not be expected and therefore initiating event frequency is unaffected. Based on this evaluation, this event did not affect core damage frequency and was not risk significant.
The explosive gas monitoring Instrumentation does not meet the 1 0CFR50.36(c)(2)(ii) criteria for limiting conditions for operation and is not included in NUREG 1431, Revision 2, Improved Technical Specifications, Westinghouse Plants. STP submitted a license amendment request in October 2001 to relocate the explosive gas monitoring instrumentation requirements to the STP Technical Requirements Manual.
CAUSE OF EVENT
Root Cause:
The root cause of this incident was a lack of understanding of the Technical Specification requirements for GWPS operability.
CORRECTIVE ACTIONS
- 1. This Licensee Event Report will be included in the Licensed Operator and Plant Operator requalification programs to include a discussion of the Technical Specification requirements associated with the operation of the GWPS and procedural changes. This corrective action will be completed by June 13, 2002.
- 2. Plant procedure OPOP02-WG-0001, Gaseous Waste Processing System Operations, has been revised to include specific requirements for notifying the control room and declaring the oxygen monitor Inoperable when inlet or outlet valve control handswitches are taken to the "OPEN" position. This corrective action was completed on February 25, 2002.
ADDITIONAL INFORMATION
This is the only event involving the GWPS. inlet and outlet control valves found in the Mechanical Auxiliary Building Operators logbook from January 1999 thru March 2002.