05000261/LER-2023-001, Condition Prohibited by Technical Specification Due to Missed Entry Into Limiting Condition for Operation: Difference between revisions
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~-I 001 1-0 Prior to the event, H. B. Robinson Steam Electric Plant, Unit No. 2 (RNP) was in Mode 1 at 100% power with no structures, systems or components out of service that contributed to this event. The pressurizer [PZR] Power Operated Relief Valves (PORV) and their respective block valves are provided for plant operational flexibility and for limiting the number of challenges to the pressurizer safety valves. The normal source of motive power for PORVs is the plant nitrogen system [LK]. An accumulator in series with each PORV provides multiple cycles of operation if the nitrogen supply is lost. | ~-I 001 1-0 Prior to the event, H. B. Robinson Steam Electric Plant, Unit No. 2 (RNP) was in Mode 1 at 100% power with no structures, systems or components out of service that contributed to this event. The pressurizer [PZR] Power Operated Relief Valves (PORV) and their respective block valves are provided for plant operational flexibility and for limiting the number of challenges to the pressurizer safety valves. The normal source of motive power for PORVs is the plant nitrogen system [LK]. An accumulator in series with each PORV provides multiple cycles of operation if the nitrogen supply is lost. | ||
The alternate source of motive power is the instrument air system [LD]. If the nitrogen pressure to the valve operator falls below a preset value, instrument air is automatically aligned to the valve. | The alternate source of motive power is the instrument air system [LD]. If the nitrogen pressure to the valve operator falls below a preset value, instrument air is automatically aligned to the valve. | ||
The event described below is reportable per 10 CFR 50. 73(a)(2)(i)(B): "Any operation or condition which was prohibited by the plant's Technical Specifications except when: (1) The Technical Specification is administrative in nature; (2) The event consisted solely of a case of a late surveillance test where the oversight was corrected, the test was performed, and the equipment was found to be capable of performing its specified safety functions; or (3) The Technical Specification was revised prior to discovery of the event such that the operation or condition was no longer prohibited at the time of discovery of the event." This criterion requires a Licensee Event Report be submitted within 60 days of the event date. | The event described below is reportable per 10 CFR 50. 73(a)(2)(i)(B): "Any operation or condition which was prohibited by the plant's Technical Specifications except when: (1) The Technical Specification is administrative in nature; (2) The event consisted solely of a case of a late surveillance test where the oversight was corrected, the test was performed, and the equipment was found to be capable of performing its specified safety functions; or (3) The Technical Specification was revised prior to discovery of the event such that the operation or condition was no longer prohibited at the time of discovery of the event." This criterion requires a Licensee Event Report be submitted within 60 days of the event date. | ||
EVENT DESCRIPTION On June 12, 2023, at 16:41 Eastern Daylight Time (EDT), a containment vessel [NH] entry was performed to identify a nitrogen leak in containment. The operator found the "A" Accumulator Low Pressure Safety Relief Valve [RV] lifting. | |||
==EVENT DESCRIPTION== | |||
On June 12, 2023, at 16:41 Eastern Daylight Time (EDT), a containment vessel [NH] entry was performed to identify a nitrogen leak in containment. The operator found the "A" Accumulator Low Pressure Safety Relief Valve [RV] lifting. | |||
PCV-3, Train "A" Nitrogen Regulator [RG] (Victor Model SR700MD (1/2")), pressure indicated greater than 130 psig. The normal setpoint for PCV-3 is 90-95 psig. An attempt to adjust the regulator to the correct pressure was unsuccessful. This resulted in the decision to close OPP-25, Train "A" Isolation for nitrogen. Closure of OPP-25 resulted in isolation of the nitrogen line and nitrogen accumulator from pressurizer PORV PCV-456. Instrument air backup was still available. | PCV-3, Train "A" Nitrogen Regulator [RG] (Victor Model SR700MD (1/2")), pressure indicated greater than 130 psig. The normal setpoint for PCV-3 is 90-95 psig. An attempt to adjust the regulator to the correct pressure was unsuccessful. This resulted in the decision to close OPP-25, Train "A" Isolation for nitrogen. Closure of OPP-25 resulted in isolation of the nitrogen line and nitrogen accumulator from pressurizer PORV PCV-456. Instrument air backup was still available. | ||
Limiting Condition for Operation (LCO) 3.4.11 was entered on June 14, 2023, at time 11: 11 EDT to replace PCV-3. The PORV was returned to service and the LCO exited on June 14, 2023 at time 11 :52 EDT. | Limiting Condition for Operation (LCO) 3.4.11 was entered on June 14, 2023, at time 11: 11 EDT to replace PCV-3. The PORV was returned to service and the LCO exited on June 14, 2023 at time 11 :52 EDT. | ||
Upon further review, closure of OPP-25 isolated the nitrogen supply to the "A" PORV which resulted in the inability to meet Surveillance Requirement (SR) 3.4.11.4 to verify accumulators are capable of operating a PORV through one complete cycle. Technical Specification (TS) LCO 3.4.11 Condition A should have been entered for an inoperable PORV. The required actions are to close and maintain power to the associated PORV block valve within one hour or, as required by TS LCO 3.4.11 Condition D, be in Mode 3 within six hours and Mode 4 in twelve hours. The failure to perform the TS required actions within the required completion time resulted in a condition prohibited by the TS which is reportable in accordance with 10 CFR 50. 73(a)(2)(i)(B). | Upon further review, closure of OPP-25 isolated the nitrogen supply to the "A" PORV which resulted in the inability to meet Surveillance Requirement (SR) 3.4.11.4 to verify accumulators are capable of operating a PORV through one complete cycle. Technical Specification (TS) LCO 3.4.11 Condition A should have been entered for an inoperable PORV. The required actions are to close and maintain power to the associated PORV block valve within one hour or, as required by TS LCO 3.4.11 Condition D, be in Mode 3 within six hours and Mode 4 in twelve hours. The failure to perform the TS required actions within the required completion time resulted in a condition prohibited by the TS which is reportable in accordance with 10 CFR 50. 73(a)(2)(i)(B). | ||
CAUSAL FACTORS An incorrect conclusion was reached by Duke Energy licensed operators on applicability of TS 3.4.11. Specifically, it was not identified that isolating the nitrogen accumulator resulted in the inability to meet TS SR 3.4.11.4 to demonstrate the accumulators are capable of supplying sufficient nitrogen to operate the PORVs. | CAUSAL FACTORS An incorrect conclusion was reached by Duke Energy licensed operators on applicability of TS 3.4.11. Specifically, it was not identified that isolating the nitrogen accumulator resulted in the inability to meet TS SR 3.4.11.4 to demonstrate the accumulators are capable of supplying sufficient nitrogen to operate the PORVs. | ||
A contributing factor to this event is that Operations Work Procedure OWP-016, Safety Injection System, includes a Precaution that inaccurately states: "Isolating Nitrogen to the PORVs has no impact on Tech Spec operability of the PORVs or plant risk profile provided the PORVs are supplied by Instrument Air as a backup motive force and the PORVs can be cycled manually". This contributed to the operators' decision on applicability of TS 3.4.11. | A contributing factor to this event is that Operations Work Procedure OWP-016, Safety Injection System, includes a Precaution that inaccurately states: "Isolating Nitrogen to the PORVs has no impact on Tech Spec operability of the PORVs or plant risk profile provided the PORVs are supplied by Instrument Air as a backup motive force and the PORVs can be cycled manually". This contributed to the operators' decision on applicability of TS 3.4.11. | ||
CORRECTIVE ACTIONS Completed Actions: | |||
==CORRECTIVE ACTIONS== | |||
Completed Actions: | |||
: 1. PCV-3 was replaced, and nitrogen supply restored. | : 1. PCV-3 was replaced, and nitrogen supply restored. | ||
: 2. A Crew Learning was shared with Operations. | : 2. A Crew Learning was shared with Operations. | ||
| Line 72: | Line 76: | ||
: 2. Revise Precaution in OWP-016. | : 2. Revise Precaution in OWP-016. | ||
: 3. Provide training to Licensed Operators on the event to include a discussion on SR 3.0.1. | : 3. Provide training to Licensed Operators on the event to include a discussion on SR 3.0.1. | ||
Any changes to the corrective actions or completion schedules will be made in accordance with the site's corrective action program. | Any changes to the corrective actions or completion schedules will be made in accordance with the site's corrective action program. | ||
SAFETY ANALYSIS This condition was assessed utilizing the zero test and maintenance probabilistic risk assessment model for RNP and was determined to have a very low safety significance. This event resulted in no impact to the health and safety of the public. | |||
ADDITIONAL INFORMATION An operating experience (OE) search was conducted and no previous Licensee Event Reports were found at RNP regarding any operation or condition which was prohibited by the plant's Technical Specifications within the past five years. | ==SAFETY ANALYSIS== | ||
This condition was assessed utilizing the zero test and maintenance probabilistic risk assessment model for RNP and was determined to have a very low safety significance. This event resulted in no impact to the health and safety of the public. | |||
==ADDITIONAL INFORMATION== | |||
An operating experience (OE) search was conducted and no previous Licensee Event Reports were found at RNP regarding any operation or condition which was prohibited by the plant's Technical Specifications within the past five years. | |||
Energy Industry Identification System (EIIS) codes for systems and components relevant to this event are identified in the text of this document within brackets [ ]. Page 3 | Energy Industry Identification System (EIIS) codes for systems and components relevant to this event are identified in the text of this document within brackets [ ]. Page 3 | ||
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Latest revision as of 18:29, 2 January 2025
| ML23222A257 | |
| Person / Time | |
|---|---|
| Site: | Robinson  |
| Issue date: | 08/10/2023 |
| From: | Basta L Duke Energy Progress |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| RA-23-0202 LER 2023-001-00 | |
| Download: ML23222A257 (1) | |
| Event date: | |
|---|---|
| Report date: | |
| 2612023001R00 - NRC Website | |
text
( -, DUKE ENERGY Date: August 10, 2023 Serial: RA-23-0202 United States Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 H. B. ROBINSON STEAM ELECTRIC PLANT, UNIT NO. 2 DOCKET NO. 50-261/RENEWED LICENSE NO. DPR-23 Subject: LICENSEE EVENT REPORT NO. 2023-001-00:
Laura A. Basta H. B. Robinson Steam Electric Plant Unit 2 Site Vice President Duke Energy 3581 West Entrance Road Hartsville, SC 29550 0 : 843 9511701 Laura.Basta@duke-energy.com 10 CFR 50.73 CONDITION PROHIBITED BY TECHNICAL SPECIFICATION DUE TO MISSED ENTRY INTO LIMITING CONDITION FOR OPERATION Ladies and Gentlemen:
Pursuant to 10 CFR 50. 73, Duke Energy Progress, LLC is submitting the attached Licensee Event Report. There are no unresolved corrective actions necessary to restore compliance with NRC requirements. This event did not impact the health and safety of the public. Please direct any questions regarding this submittal to Phillip D. Mason, Manager Nuclear Support Services, at (843) 951-5797.
This document contains no new regulatory commitments.
Sincerely, Laura A. Basta Site Vice President LAB/mjh Attachment c:
Region Administrator, NRC, Region 11 NRC Resident Inspectors, HBRSEP Mr. Luke Haeg, NRC Project Manager, NRR
United States Nuclear Regulatory Commission Attachment to Serial: RA-23-0202 4 Pages (including this page)
H. 8. ROBINSON STEAM ELECTRIC PLANT, UNIT NO. 2 LICENSEE EVENT REPORT NO. 2023-001-00:
CONDITION PROHIBITED BY TECHNICAL SPECIFICATION DUE TO MISSED ENTRY INTO LIMITING CONDITION FOR OPERATION
Abstract
On June 12, 2023, at 16:41 Eastern Daylight Time, with H. B. Robinson Steam Electric Plant, Unit No. 2 in Mode 1 at 100% power, the nitrogen supply to the "A 11 Pressurizer Power Operated Relief Valve (PORV) was isolated due to a nitrogen leak. By design, Instrument Air was available to the "A 11 PORV allowing it to perform its safety function.
After further review, it was determined that isolating the nitrogen supply to the "A 11 PORV resulted in inability to meet Surveillance Requirement (SR) 3.4.11.4 and Technical Specification (TS) Limiting Condition for Operation (LCO) 3.4.11 Condition A should have been entered for an inoperable PORV. The cause was improper application of the TS. This event did not impact the health and safety of the public.
BACKGROUND 050 052
- 2. DOCKET NUMBER
- 3. LER NUMBER I
00261 NUMBER NO.
I YEAR SEQUENTIAL REV
~-I 001 1-0 Prior to the event, H. B. Robinson Steam Electric Plant, Unit No. 2 (RNP) was in Mode 1 at 100% power with no structures, systems or components out of service that contributed to this event. The pressurizer [PZR] Power Operated Relief Valves (PORV) and their respective block valves are provided for plant operational flexibility and for limiting the number of challenges to the pressurizer safety valves. The normal source of motive power for PORVs is the plant nitrogen system [LK]. An accumulator in series with each PORV provides multiple cycles of operation if the nitrogen supply is lost.
The alternate source of motive power is the instrument air system [LD]. If the nitrogen pressure to the valve operator falls below a preset value, instrument air is automatically aligned to the valve.
The event described below is reportable per 10 CFR 50. 73(a)(2)(i)(B): "Any operation or condition which was prohibited by the plant's Technical Specifications except when: (1) The Technical Specification is administrative in nature; (2) The event consisted solely of a case of a late surveillance test where the oversight was corrected, the test was performed, and the equipment was found to be capable of performing its specified safety functions; or (3) The Technical Specification was revised prior to discovery of the event such that the operation or condition was no longer prohibited at the time of discovery of the event." This criterion requires a Licensee Event Report be submitted within 60 days of the event date.
EVENT DESCRIPTION
On June 12, 2023, at 16:41 Eastern Daylight Time (EDT), a containment vessel [NH] entry was performed to identify a nitrogen leak in containment. The operator found the "A" Accumulator Low Pressure Safety Relief Valve [RV] lifting.
PCV-3, Train "A" Nitrogen Regulator [RG] (Victor Model SR700MD (1/2")), pressure indicated greater than 130 psig. The normal setpoint for PCV-3 is 90-95 psig. An attempt to adjust the regulator to the correct pressure was unsuccessful. This resulted in the decision to close OPP-25, Train "A" Isolation for nitrogen. Closure of OPP-25 resulted in isolation of the nitrogen line and nitrogen accumulator from pressurizer PORV PCV-456. Instrument air backup was still available.
Limiting Condition for Operation (LCO) 3.4.11 was entered on June 14, 2023, at time 11: 11 EDT to replace PCV-3. The PORV was returned to service and the LCO exited on June 14, 2023 at time 11 :52 EDT.
Upon further review, closure of OPP-25 isolated the nitrogen supply to the "A" PORV which resulted in the inability to meet Surveillance Requirement (SR) 3.4.11.4 to verify accumulators are capable of operating a PORV through one complete cycle. Technical Specification (TS) LCO 3.4.11 Condition A should have been entered for an inoperable PORV. The required actions are to close and maintain power to the associated PORV block valve within one hour or, as required by TS LCO 3.4.11 Condition D, be in Mode 3 within six hours and Mode 4 in twelve hours. The failure to perform the TS required actions within the required completion time resulted in a condition prohibited by the TS which is reportable in accordance with 10 CFR 50. 73(a)(2)(i)(B).
CAUSAL FACTORS An incorrect conclusion was reached by Duke Energy licensed operators on applicability of TS 3.4.11. Specifically, it was not identified that isolating the nitrogen accumulator resulted in the inability to meet TS SR 3.4.11.4 to demonstrate the accumulators are capable of supplying sufficient nitrogen to operate the PORVs.
A contributing factor to this event is that Operations Work Procedure OWP-016, Safety Injection System, includes a Precaution that inaccurately states: "Isolating Nitrogen to the PORVs has no impact on Tech Spec operability of the PORVs or plant risk profile provided the PORVs are supplied by Instrument Air as a backup motive force and the PORVs can be cycled manually". This contributed to the operators' decision on applicability of TS 3.4.11.
CORRECTIVE ACTIONS
Completed Actions:
- 1. PCV-3 was replaced, and nitrogen supply restored.
- 2. A Crew Learning was shared with Operations.
I
- 2. DOCKET NUMBER
- 3. LER NUMBER 18 SEQUENTIAL REV NUMBER NO.
00261
- - I 1-G 001
- 3. Missed Technical Specification entered into corrective action program Planned Actions:
- 1. Evaluate a change to the TS and TS basis to ensure the operability requirements are clear and the SRs are correct to test the system requirements.
- 2. Revise Precaution in OWP-016.
- 3. Provide training to Licensed Operators on the event to include a discussion on SR 3.0.1.
Any changes to the corrective actions or completion schedules will be made in accordance with the site's corrective action program.
SAFETY ANALYSIS
This condition was assessed utilizing the zero test and maintenance probabilistic risk assessment model for RNP and was determined to have a very low safety significance. This event resulted in no impact to the health and safety of the public.
ADDITIONAL INFORMATION
An operating experience (OE) search was conducted and no previous Licensee Event Reports were found at RNP regarding any operation or condition which was prohibited by the plant's Technical Specifications within the past five years.
Energy Industry Identification System (EIIS) codes for systems and components relevant to this event are identified in the text of this document within brackets [ ]. Page 3
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