05000416/LER-2021-005, Oscillation Power Range Monitors (Oprms) Technical Specification Noncompliance
| ML22033A065 | |
| Person / Time | |
|---|---|
| Site: | Grand Gulf  |
| Issue date: | 02/02/2022 |
| From: | Hardy J Entergy Operations |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| GNRO2022-00006 LER 2021-005-00 | |
| Download: ML22033A065 (1) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 4162021005R00 - NRC Website | |
text
- - PEntergy GNRO2022-00006 February 2, 2022 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Entergy Operations, Inc.
P.O. Box 756 Port Gibson, Mississippi 39150 Jeffery A. Hardy Manager Regulatory Assurance Grand Gulf Nuclear Station Tel: 802-380-5124 10 CFR 50.73
SUBJECT:
Grand Gulf Nuclear Station, Unit 1 Licensee Event Report 2021-005-00, Oscillation Power Range Monitors ( OPRMs) Technical Specification Noncompliance.
Grand Gulf Nuclear Station, Unit 1 Docket No. 50-416 Renewed License No. NPF-29 Attached is Licensee Event Report 2021-005-00, Oscillation Power Range Monitors (OPRMs)
Setpoint Error Causes Technical Specification Noncompliance. This report is being submitted in accordance with 10 CFR 50.73(a)(2)(i)(B), as an operation or condition prohibited by the plant's Technical Specification.
This letter contains no new Regulatory Commitments. Should you have any questions concerning the content of this letter, please contact Jeff Hardy, Regulatory Assurance Manager at 802-380-5124.
JAH/fas Attachments: Licensee Event Report 2021-005-00
GNRO2022-00006 Page 2 of 3 cc:
NRC Senior Resident Inspector Grand Gulf Nuclear Station Port Gibson, MS 39150 U.S Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001
GNRO2022-00006 Page 3 of 3 Attachment Licensee Event Report 2021-005-00
Abstract
On June 21, 2021, while operating in MODE 1 at approximately 100 percent power, Grand Gulf Nuclear Station identified that the Detect and Suppress Solution - Confirmation Density (DSS-CD) settings for the Oscillation Power Range Monitors (OPRM) had not been updated to the current licensing basis as required per NEDC-33075P Rev 7 Licensing Topical Report General Electric Hitachi (GEH) Boiling Water Reactor Detect and suppress Solution - Confirmation Density. As a result, the Oscillation Power Range Monitors (OPRM) upscale setting requirements specified in Technical Specification (TS) Table 3.3.1.1-1, Reactor Protection System Instrumentation, function 2, Average Power Range Monitors (APRM), Sub-Function "f' OPRM upscale limits were not fully met.
This event is reportable under 10 CFR 50.73(a)(2)(i)(B), any operation or condition prohibited by the plant's Technical Specifications.
The direct cause of this event was that the setpoints were not implemented correctly during Maximum Extended Load Line Limit Analysis Plus (MELLLA+) implementation. The direct cause was corrected by changing the Maximum Oscillation
- Period, T max setpoint to 4.0 seconds on all four (APRM) channels. This corrected the OPRM setpoints for DSS-CD.
Plant Conditions
Grand Gulf Nuclear Station (GGNS) Unit 1 was operating at 100 percent power in MODE 1. There were no Structures, Systems, or Components that were inoperable that contributed to this event.
Event Description
On June 21, 2021, while performing analysis for a future fuel load, GGNS identified that the Detect and Suppress Solution
- - Confirmation Density (DSS-CD) settings had not been updated to the current version of the General Electric Hitachi (GEH) recommended report. Additionally, the Instrument and Control (l&C) Calibration procedures were not updated for the Average Power Range Monitor (APRM) channels. Specifically, the Maximum Oscillation Period, maximum time period (T max), setpoint was set at 3.5 seconds instead of 4.0 seconds as required in the licensing basis per NEDC-33075P, Rev 7 Licensing Topical Report GEH Boiling Water Reactor DSS-CD.
The settings for the maximum period installed in the plant were non-conservative with respect to the licensing basis.
The Oscillation Power Range Monitors (OPRM) Upscale setting requirements specified in the Technical Specifications (TS) 3.3.1.1, Reactor Protection System (RPS) Instrumentation, Table 3.3.1.1-1, Reactor Protection System Instrumentation, function 2, Average Power Range Monitors, Sub-Function "f', OPRM Upscale limits were not fully met.
This event is reportable under 10 CFR 50. 73(a)(2)(i)(B), as any operation or condition prohibited by the plant's Technical Specifications.
Safety Assessment
The actual consequences for this event were very low. There was no radiological release from the primary containment as a result of this calibration error. There were no other actual consequences to safety of the general public, nuclear safety, industrial safety, or radiological safety. No Technical Specification Safety Limits were violated.
Event Cause(s):
The direct cause of this event was that the setpoints were not implemented correctly during Maximum Extended Load Line Limit Analysis Plus (MELLLA+) implementation.
Causal Factors 1 - The technical basis for the change in OPRM settings was not clearly communicated such that consequences of not executing the work were well understood.
Causal Factors 2 - GGNS-NE-16-00007, the engineering report for the June 17, 2016, OPRM SCRAM, was inappropriately revised in a way that contradicted the Power Range Neutron Monitor (PRNM) DSS-CD Settings Report causing confusion regarding the actual licensing basis. The report was also inappropriately used to state T max = 3.5 seconds was acceptable, also contradicting the PRNM DSS-CD Settings Report.
Corrective Actions
The direct cause was corrected by changing the T max setpoint to 4.0 seconds on all four APRM channels. This corrected the OPRM setpoints for DSS-CD.
Reperform an extent of condition on MELLLA+ Implementation for settings/setpoint changes. Tracked by the Corrective Action Program. Page 2 of 3 (08-2020)
U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3150-0104 EXPIRES: 08/31/2023 LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET (See NUREG-1022, R.3 for instruction and guidance for completing this form https://www.nrc.gov/readinq-rm/doc-collections/nureqs/staff/sr1022/r3D
- 3. LERNUMBER YEAR Grand Gulf Nuclear Station, Unit 1 05000-416 2021 SEQUENTIAL NUMBER
- - 005 REV NO.
- - 00 Revise GGNS-NE-16-00007 to delete the changes made by revision 2 for CR-GGN-2021-06434, CA-0010. Revision 3 of GGNS-NE-16-00007 evaluates the DSS-CD settings for T min = 1.05 and T max = 3.5 and PBDA Sp= 1.15.
Converting back to Revision 1 for CR-GGN-2021-6434, CA-10. This action is complete
Previous Similar Events
LER 2016-009-00 I LER 2016-009-01 Entry into Mode of Applicability with the Oscillation Power Range Monitor Upscale Settings Incorrectly Set. The direct cause of this event was the failure to ensure the required procedure changes were incorporated and performed prior to the unit entering the mode of applicability.
Prior corrective actions did not prevent recurrence because, the technical basis for the change was not clearly communicated.
The settings were updated in an evaluation engineering change. This engineering change type is considered a document only change. Page 3 of 3