05000298/LER-2018-002, Lack of Procedural Guidance Results in Work Scheduling Error Causing Breach of Secondary Containment and Condition Prohibited by Technical Specifications
| ML18353A278 | |
| Person / Time | |
|---|---|
| Site: | Cooper  |
| Issue date: | 12/10/2018 |
| From: | Dent J Nebraska Public Power District (NPPD) |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NLS2018064 LER 2018-002-00 | |
| Download: ML18353A278 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 2982018002R00 - NRC Website | |
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Nebraska Public Power District Always there when you need us NLS2018064 December 10, 2018 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555-0001
Subject:
Licensee Event Report No. 2018-002-00 Cooper Nuclear Station, Docket No. 50-298, DPR-46
Dear Sir or Madam:
The purpose of this correspondence is to forward Licensee Event Report 2018-002-00.
There are no new commitments contained in this letter.
Sincerely, Dent, Jr.
Vice President Nuclear-Chief Nuclear Officer
/jo Attachment: Licensee Event Report 2018-002-00 cc:
Regional Administrator w/attachment USNRC - Region IV Cooper Project Manager w/attachment USNRC - NRR Plant Licensing Branch IV Senior Resident Inspector w/attachment USNRC-CNS SRAB Administrator w/attachment COOPER NUCLEAR STATION NPG Distribution w/attachment INPO Records Center w/attachment via ICES entry SORC Chairman w/attachment CNS Records w/attachment P.O. Box 98 / Brownville, NE 68321*0098 Telephone: (402) 825-3811 / Fax: (402) 825-5211 www.nppd.com
- NRCFORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3150-0104 EXPIRES: 03/31/2020 (04-2018)
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. Page Cooper Nuclear Station 05000298 1 of 4
- 4. Title
)
Lack of Procedural Guidance Results in Work Scheduling Error Causing Breach of Secondary Containment and Condition Prohibited by Technical Specifications
- 5. Event Date
- 6. LER Number
- 7. Report Date
- 8. Other Facilities Involved Sequential Rev Facility Name Docket Number Month Day Year Year Month Day Year Number No.
05000 10 10 2018 2018 -002
- - 00 12 10 2018 Facility Name Docket Number 05000
- 9. Operating Mode Abstract (Limit to 1400 spaces, i.e., approximately 14 single-spaced typewritten lines)
During maintenance on Residual Heat Removal Service Water piping, secondary containment was breached due to work being performed simultaneously on the piping in both the reactor building and the control building basement. Upon discovery of the breach, work was stopped and direction given to install temporary covers for each breach. Upon investigation, it was discovered that multiple work orders for work on different areas of the piping had been approved, with the assumption that the work would not be scheduled to be performed concurrently.
Limiting Condition for Operation (LCO) 3.5.2, Condition C, was previously entered for a planned Water Inventory Control Activity to replace Control Rod Drive Mechanisms. As directed by the LCO, a contingency plan was established to maintain a secondary containment boundary by closing door R102, if needed. It was not known during this time that pipe repairs were ongoing or planned; thus the contingency plan used to enter the LCO did not include actions to be taken if secondary containment were breached via the piping.
Guidance will be developed for review and approval of outage work orders. Procedures will be revised to clarify secondary containment review requirements during the work order approval process.
NRG FORM 366 (04-2018)
PLANT STATUS YEAR 2018 SEQUENTIAL NUMBER
- - 002 Cooper Nuclear Station (CNS) was in Mode 5, Refueling, at O percent power, at the time of the event.
BACKGROUND REV NO.
- - 00 Secondary containment provides a controlled volume in which fission products can be contained, diluted, and processed prior to release to the environment and consists of four subsystems, one of these subsystems is the reactor building [EIIS:NG], which encloses the Reactor Pressure Vessel [EIIS:RPV] and primary containment [EIIS:NH]. Secondary containment penetration flow paths form a part of the secondary containment boundary. Reactor building personnel airlock doors R101 and R102 form part of the secondary containment boundary.
The Residual Heat Removal [EIIS:BO] Service Water Booster (RHRSWB) System is designed to provide cooling water for the Residual Heat Removal (RHR) System heat exchangers [EIIS:HX]. The RHRSWB System removes heat from the suppression pool via the RHR System to limit the suppression pool temperature and primary containment pressure following a loss of coolant accident.
The RPV water level must be controlled in Modes 4 and 5 to ensure that if an unexpected draining event should occur, the reactor coolant water level remains above the top of active irradiated fuel. CNS Technical Specifications (TS) Limiting Condition for Operation (LCO) 3.5.2, RPV Water Inventory Control, requires the drain time of RPV water inventory to the top of active fuel be >/= 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.
Prior to entering LCO 3.5.2, Condition C, verification that secondary containment boundary is capable of being established in less than the drain time, verification that each secondary containment penetration flow path is capable of being isolated in less than the drain time, and verification that one Standby Gas Treatment Subsystem [EIIS:BH] is capable of being placed in operation in less than the drain time, is required.
EVENT DESCRIPTION
Work orders to replace sections of RHRSW piping, located in the reactor building, were approved on March 19, 2018. This work was scheduled to be performed during Refueling Outage 30 (RE30). On September 29, 2018, two requests to add work to the RE30 schedule were initiated. These requests were to repair additional RHRSW piping in the control building basement. The requests were approved on September 30,
- 2018.
On September 29, 2018, at 20:53, CNS commenced RE30 and subsequently entered Mode 5 on October 2, 2018, at 02:41.
On October 8, work began on the RHRSW piping and continued on October 9 and October 10, 2018. Page 2 of 4 (04-2018)
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\\~1j LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET (See NUREG-1022, R.3 for instruction and guidance for completing this form http://www.nrc.gov/readinq-rm/doc-collections/nuregs/staff/sr1022/r3!)
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 1. FACILITYNAME 2 DOCKET NUMBER
- 3. LER NUMBER YEAR Cooper Nuclear Station 05000-298 2018 SEQUENTIAL NUMBER
- - 002 REV NO.
- - 00 On October 9, 2018, at 18:44, Operations pre-planned for actions to be taken in LCO 3.5.2, Condition C, and subsequently entered LCO 3.5.2, Condition C, for a planned Water Inventory Control Activity to begin Control Rod Drive Mechanism replacements at 00:10 on October 10, 2018. This activity included verifying that a contingency plan for establishing secondary containment boundary was in effect. This contingency plan (RE30-0009 R101/R102, Containment Closure Plan) contained actions to close door R102 to maintain secondary containment, if needed.
On October 10, 2018, it was identified that welders had cut into the RHRSW piping in the control building basement per the applicable work order. At that time, it was discovered that work was on-going on the same RHRSW piping in the reactor building, thus causing a breach of the secondary containment boundary. Work on the piping in the control building basement was immediately stopped upon discovery of the breach.
Temporary covers were subsequently installed for each breach in the RHRSW piping in the control building basement.
Following this event, the process of emergently approving work orders during an outage was reviewed. It was identified that assumptions were made that work on the RHRSW piping in both buildings would not be scheduled to be performed concurrently. However, information was not provided in the plant impact statement of the work orders, nor to the work schedulers, that the work could not be performed concurrently.
In *addition, during independent verification for entry into LCO 3.5.2 on October 9, 2018, it was not known-that pipe repairs were ongoing or planned in either the reactor building or control building basement. As such, pipe repair work was not included in the contingency plan used to meet the required action for LCO 3.5.2, Condition C.
BASIS FOR REPORT This event is being reported per 10 CFR 50.73(a)(2)(i)(B) as an operation or condition which was prohibited by TS due to entering LCO 3.5.2, Condition C, without fully verifying the ability to establish the secondary containment boundary.
SAFETY SIGNIFICANCE
During refueling.outages, risk from work that breaches secondary containment is managed through implementation of containment closure plans that re-establish containment should an event occur that may threaten reactor fuel integrity. The failure to implement a plan for the RHRSW piping breach had the potential to preclude the ability to minimize radioactive exposures to the public in the event of a fuel damage event. However, based on the small likelihood of a fuel failure and the short amount of time in which the breach existed, the nuclear risk from this event is negligible. Page 3 of 4 (04-2018)
U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3150-0104 EXPIRES: 3/31/2020 LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET (See NUREG-1022, R.3 for instruction and guidance for completing this form http://www.nrc.gov/reading-rm/doc-collections/nureqs/staff/sr1022/r3!)
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 1. FACILITYNAME
- 2. DOCKET NUMBER
- 3. LER NUMBER YEAR Cooper Nuclear Station 05000-298 2018
CAUSE
SEQUENTIAL NUMBER
- - 002 REV NO.
- - 00 The cause of this event was the assumption that the work activities scheduled in the reactor building and the control building basement would not be performed in parallel. In addition, information was not provided in the plant impact statement of the work orders, or directly to the schedulers, that this work could not be performed in parallel.
CORRECTIVE ACTIONS
Work was immediately stopped and temporary covers were installed to re-establish the secondary containment boundary. Outage scope was immediately reviewed with no other actual breaches identified.
Operations reviewed RE30 clearance orders to see if this condition existed elsewhere; no additional concerns were identified. In addition, a containment closure plan was developed and approved.
Guidance will be developed for review and approval of outage work orders.
Procedures will be revised to clarify secondary containment review requirements during the work order approval process.
PREVIOUS EVENTS On October 12, 2016, it was discovered that a contingency plan was not established for venting Control Rod Drives (CRD) via CRD-V-156/157 valves. Work was stopped and a contingency plan was developed and activated to allow continued venting of CRD drives. (CR-CNS-2016-06830)
On October 18, 2012, it was discovered that HPCI-V-53 and HPCI-V-54 were found open and left unattended during draining of the High Pressure Coolant Injection (HPCI) system, causing a breach of secondary containment. (CR-CNS-2012-07511) Page 4 of 4