IR 05000325/2019040
| ML19289A011 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 10/16/2019 |
| From: | Bradley Davis Division Reactor Projects II |
| To: | Krakuszeski J Duke Energy Progress |
| Reeder D | |
| References | |
| IR 2019040 | |
| Download: ML19289A011 (14) | |
Text
October 16, 2019
SUBJECT:
BRUNSWICK STEAM ELECTRIC PLANT - NRC SUPPLEMENTAL INSPECTION REPORT 05000325/2019040 AND ASSESSMENT FOLLOW-UP LETTER
Dear Mr. Krakuszeski:
On September 26, 2019, the NRC completed a supplemental inspection using Inspection Procedure 95001, Supplemental Inspection for One or Two White Inputs in a Strategic Performance Area. On September 26, 2019, the NRC inspection team discussed the results of this inspection and the implementation of your corrective actions with you and other members of your staff. The results of this inspection are documented in the enclosed report.
The NRC performed this inspection to review your stations actions in response to the White Reactor Coolant System Leakage performance indicator (PI), which you reported in the first quarter of 2019. On August 20, 2019, you informed the NRC that your station was ready for the supplemental inspection.
The NRC determined that your staffs evaluation identified that the primary root cause of the White PI was the inappropriate selection of Tinel, a titanium-nickel alloy, for long term application in the reactor water level instrument lines due to susceptibility to hydrogen embrittlement. Specifically, a 1 Cryofit (cryogenic) coupling located on the steam side of a reference leg instrument line, experienced a 360-degree circumferential separation. This opened a path for steam from the reactor to leak into the drywell. The licensee performed a reactor shutdown in accordance with licensee procedures. The licensees immediate corrective action was to replace the failed coupling with a welded connection. Additionally, the licensee replaced all Cryofit couplings in instrument lines that contained steam (most susceptible to hydrogen embrittlement) in both units, to address extent of condition. The corrective actions to prevent recurrence was to revise the Brunswick piping specifications to restrict the use of Cryofit couplings to locations that are not subject to hydrogen embrittlement; and to incorporate hydrogen embrittlement of Cryofit couplings (aging mechanism) into the Aging Management Program. Based on the results of this inspection, the NRC determined that Brunswick appropriately evaluated and understood the root and contributing causes, and the completed and planned corrective actions were sufficient to address the performance issue that led to the White PI, thus satisfying all objectives found in IP 95001. Additionally, the White PI had since returned to the Green performance band as of the 2nd quarter, following isolation of the leak and replacement of the failed coupling with a welded fitting.
Based on the guidance in Inspection Manual Chapter 0305, Operating Reactor Assessment Program, and the results of this inspection, the White PI will be closed, and Brunswick Unit 1 will transition from the Regulatory Response Column of the NRCs Action Matrix to the Licensee Response Column as of the date of the cover letter to this report.
The NRC inspectors did not identify any finding or violation of more than minor significance.
This letter, its enclosure, and your response (if any) will be made available for public inspection and copying at http://www.nrc.gov/reading-rm/adams.html and at the NRC Public Document Room in accordance with 10 CFR 2.390, Public Inspections, Exemptions, Requests for Withholding.
Sincerely,
/RA/
Bradley J. Davis, Chief Reactor Projects Branch 4 Division of Reactor Projects
Docket No. 05000325 License No. DPR-71
Enclosure:
As stated
cc w/ encl: Distribution via LISTSERV
SUMMARY
The U.S. Nuclear Regulatory Commission (NRC) continued monitoring the licensees performance by conducting a 95001 supplemental inspection at Brunswick Steam Electric Plant in accordance with the Reactor Oversight Process. The Reactor Oversight Process is the NRCs program for overseeing the safe operation of commercial nuclear power reactors. Refer to https://www.nrc.gov/reactors/operating/oversight.html for more information.
List of Findings and Violations
No findings or violations of more than minor significance were identified.
Additional Tracking Items
Type Issue Number Title Report Section Status LER 05000325/2019-002-00 LER 2019-002-00 for Brunswick Steam Electric Plant, Unit 1 Regarding Degraded Principal Safety Barrier, Technical Specification Shutdown, and Automatic System Actuation.
71153 Closed
INSPECTION SCOPES
Inspections were conducted using the appropriate portions of the inspection procedures (IPs) in effect at the beginning of the inspection unless otherwise noted. Currently approved IPs with their attached revision histories are located on the public website at http://www.nrc.gov/reading-rm/doc-collections/insp-manual/inspection-procedure/index.html. Samples were declared complete when the IP requirements most appropriate to the inspection activity were met consistent with Inspection Manual Chapter (IMC) 2515, Light-Water Reactor Inspection Program - Operations Phase. The inspectors reviewed selected procedures and records, observed activities, and interviewed personnel to assess licensee performance and compliance with Commission rules and regulations, license conditions, site procedures, and standards.
OTHER ACTIVITIES
- TEMPORARY INSTRUCTIONS, INFREQUENT AND ABNORMAL
71153 - Followup of Events and Notices of Enforcement Discretion
Event Report (IP Section 03.02)
The inspectors evaluated the following licensee event report (LER):
- (1) LER 05000325/2019-002-00, Degraded Principal Safety Barrier, Technical Specification Shutdown, and Automatic System Actuation (ADAMS Accession Number ML19143A375). The circumstances surrounding this LER were previously documented in Inspection Report 05000324,325/2019002 Section 71153. (Closed)
95001 - Supplemental Inspection for One or Two White Inputs in a Strategic Performance Area
Inspectors reviewed the licensees root causes, contributing causes, extent of condition, and extent of cause determinations. Inspectors assessed whether the licenses corrective actions to address the root and contributing causes were sufficient to prevent recurrence. The results of the performance review and NRCs assessment are documented below.
1. Problem Identification
A green self-revealing non-cited violation (NCV) associated with the event which resulted in the reactor coolant system leakage performance indicator (PI) to cross the green-white threshold was previously documented in inspection report 05000324,325/2019002.
a. The event occurred on March 28, 2019, with Unit 1 operating at 100 percent power. A 1-inch Cryofit (cryogenic) coupling (Tinel-a titanium-nickel alloy), located on an instrument line, experienced a 360-degree circumferential separation. This opened a path for steam from the reactor to leak into the drywell which resulted in increased drywell pressure and drywell floor drain leakage. The coupling failure was determined to be due to hydrogen embrittlement. The increase in leakage resulted in a White PI.
The inspectors reviewed documentation related to the licensees evaluation of the White PI. The inspectors determined that the root cause evaluation (RCE)documented how the issue was identified and under what conditions the issue was identified.
b. The licensees RCE determined the root cause of the event was the selection of Tinel was inappropriate for long term application in the reactor water level instrument lines (RC-1). The issue had existed since selection and installation of the couplings in approximately 1983. The licensee's RCE identified several prior opportunities for potential identification, including:
i. Hydrogen Water Chemistry Implementation (1989-1990)ii. Seabrook Event - INPO notice and NRC Information Notice 91-87 (1991)iii. License Renewal Aging Management Review (2004)iv. Online Noble Metal Chemistry Implementation (2014-2015)
The inspectors determined that the licensees evaluation was adequate with respect to identifying how long the issue existed and prior opportunities for identification.
c. The licensees RCE documented the safety significant impacts including nuclear, radiological, and industrial, as listed below:
i. The licensees PRA sensitivity analyses demonstrated that the increase in core damage frequency for this event was less than 1E-06 (Green)ii. Breach of the reactor pressure vessel pressure boundary which caused a loss of inventory and increase in containment pressure iii. Abnormal operating procedure for increased drywell leakage entered iv. Notice of Unusual Event declaration for elevated drywell leakage (more than 10 gpm) for greater than 15 minutes v. Reactor shutdown, in accordance with licensee procedures vi. Slightly increased off site radiological releases (within technical specification limits) due to venting to control containment pressure vii. Individuals received emergent dose to perform repairs in the drywell (within administrative limits)viii. Forced outage on Unit 1 and extension of the refueling outage on Unit 2 to address extent of condition
Additionally, the inspectors reviewed the licensees Cryogenic Coupling Risk Review which documented for each coupling (by system), the location, consequence of failure and probability of failure. The inspectors determined that the licensee appropriately considered and documented the risk consequences (safety impacts)and compliance concerns associated with the issue.
2. Root Cause, Extent-of-Condition, and Extent-of-Cause Evaluation
a. The licensee used the following investigation techniques to complete RCE 2265623.
i. equipment reliability form ii. failure mode - metallurgical report iii. why staircase iv. industry experience v. safety culture evaluation
The inspectors determined that the licensee evaluated the issue using systematic methodologies to identify root and contributing causes.
b. The licensee's RCE included an event narrative, a description of Cryofit coupling use and installation, historical use of the couplings for the licensee, an operating experience (OE) review, and a metallurgical report of the failed coupling. The licensee's root cause identified a single item, the selection and installation of Tinel couplings was inappropriate for long term application in the reactor water level instrument lines.
The inspectors determined that the RCE was conducted to a level of detail commensurate with the significance of the problem.
c. The licensee evaluated prior occurrences and operating experiences within the RCE. There were no prior occurrences of Cryofit coupling failures due to hydrogen embrittlement with this licensee. However, the OE considered was a 1991 Cryofit coupling failure at the Seabrook plant on a sample line in the pressurizer steam space that resulted in the NRC issuing Information Notice (IN) 91-87, Hydrogen Embrittlement of Raychem Cryofit Couplings, and prompted INPO to issue OE as well. The licensee evaluated their internal response to IN 91-87, and recognized a failure to implement a 1991 recommendation by the corporate metallurgist, as a contributing cause in the RCE (CC-1).
The inspectors determined that the RCE appropriately considered prior occurrences of the issue and knowledge of prior operating experience.
d. The licensee's RCE used the same-similar methodology to concurrently consider the extent of condition and extent of cause, which included:
i. The extent of condition determined that other Cryofit couplings are susceptible to hydrogen embrittlement (EOC-AS1).
ii. The extent of cause evaluated the susceptibility of other pressure retaining components to hydrogen embrittlement (EOCa-AS2).
iii. The extent of cause also evaluated the susceptibility of other pressure retaining components to another degradation mechanism (EOCa-AS1).
The inspectors determined that the licensee's RCE adequately addressed the extent of condition and extent of cause for the issue.
e. The licensee's review appropriately considered safety culture traits during their determination of the root cause, extent of condition and extent of cause. The licensee determined the issue was a historical issue, and no current safety culture weaknesses were identified. However, the safety culture analysis determined the most relevant aspects included design margins, resolution, and operating experience. Specifically, the licensee identified the resolution aspect (lack of follow-up to resolve an issue) as a contributing cause since the licensee failed to implement a 1991 recommendation by a corporate metallurgist, after evaluating the Seabrook OE.
The inspectors determined that the RCE included an appropriate consideration of whether a weakness in any safety culture component was a root cause or significant contributing cause of the issue.
3. Corrective Actions
a. The licensee corrective actions to address the performance issue:
i. The licensees immediate action to correct the condition was to replace the failed coupling with a welded fitting (COND-AS1). As part of the extent of condition, the licensee also replaced Cryofit couplings on instrument lines that contain steam for both Units 1 and 2, with welded fittings (EOC-AS1).
ii. The licensee revised the piping specification to ensure Cryofit couplings are not installed in process medium that may facilitate hydrogen embrittlement (RC1-AS1). This was a corrective action to preclude repetition (CAPR) to address the root cause.
iii. Additionally, the licensee incorporated hydrogen embrittlement of Cryofit couplings (aging mechanism) into the Aging Management Program (AMP)
(EOCa-AS4). This action was also a CAPR, to address extent of cause.
iv. Planned corrective actions include replacement of a minimum of two Cryofit couplings from different instrument lines in the drywell for each Unit for the next two outages (four outages total) (EOC-AS2/3/4/5), and perform metallurgical analysis on the replaced Cryofit couplings, to further inform the AMP.
v. The identified contributing cause was failure to act on a recommendation by the corporate metallurgist in 1991 after the Seabrook plant coupling failure (CC-1).
The licensee determined the contributing cause to be a historical issue and concluded that no additional associated corrective actions were necessary.
The inspectors determined that the licensee specified appropriate corrective actions for each root and contributing cause, as well as extent of condition and extent of cause.
b. The licensee established a program to analyze the Cryofit coupling failure, and a systematic method to evaluate future actions regarding Cryofit couplings based on metallurgical data.
i. The actions to address the root cause including the CAPRs were addressed above. Other corrective actions taken and planned to address extent of cause (EOCa) and extent of condition (EOC) include:
1. Reviewed the piping specification 248-117 'Installation of Piping Systems'
to identify legacy issues similar to the Cryofit coupling failure (ENHN1) and verify legacy potential incompatible process fluid operating conditions (EOCa-AS1),
2. Determined the acceptability of Cryofit couplings identified installed in
noncompliant process fluids through specifications for pressure retaining components (EOCa-AS2, ENHN2, ENHN3),
3. Resolved the temperature difference in the piping specification, 248-117
'Installation of Piping Systems' and design temperatures of the installed couplings (EOCa-AS3),
4. Incorporated a new aging mechanism, hydrogen embrittlement, to the
AMP for Cryofit couplings to ensure the intended function of the coupling is consistent with the license basis (EOCa-AS4),
licensee fleet for potential application to license renewal (ENHN4),
6. Metallurgical data gathered as part of the AMP will be collected in the
following refueling outages: Unit 1, B1R23 in 2020 (EOC-AS2) and R1R24 in 2022 (EOC-AS4), Unit 2, B2R25 in 2021 (EOC-AS3) and B2R26 in 2023 (EOC-AS5). The AMP data will result in evaluations of the Cryofit couplings as a modification to the plant. [planned]
The inspectors noted that all corrective actions above were completed with the exception of EOC-AS2/3/4/5. The inspectors determined the licensees corrective actions have been appropriately prioritized with respective due dates, and with consideration to risk significance and regulatory compliance in the type of corrective action chosen.
c. The licensee's corrective actions to address and preclude repetition of hydrogen embrittlement of Cryofit couplings installed in susceptible environments were promptly planned and completed. At the time of inspection, both the CAPRs were completed (RC1-AS1 and EOCa-AS4).
The inspectors determined that the licensee adequately established a schedule and formal tracking mechanism for implementing and completing the taken and planned corrective actions.
d. The licensee established measures to determine the effectiveness of the corrective actions documented in the RCE.
i. The CAPR associated with RC1-AS1 was completed in July 2019, and the effectiveness review will be completed within 6-12 months, with an initial due date of February 2020 (RC1-EREV1).
ii. The CAPR associated with EOCa-AS4 was competed in September 2019, and the effectiveness review will be completed after the planned coupling replacements (EOC-AS2/3/4/5), with an initial due date of July 2023 (RC1-EREV2)
The inspectors reviewed the effectiveness review plans, and determined each appropriately specified assessment methods, attributes, quantitative and/or qualitative measures of success and timeliness goals for each CAPR.
e. There was no notice of violation associated with the White PI. The NRC previously documented a self-revealing Green NCV (05000324,05000325/2019002-04)associated with the Cryofit coupling failure that resulted in the White PI. The inspectors verified that corrective actions adequately addressed the NCV.
4. Evaluation of IMC 0305 Criteria for Treatment of Old Design Issues.
The licensee did not request credit for self-identification of an old design issue; therefore, the risk-significant issue was not evaluated against the IMC 0305 criteria for treatment of an old design issue.
5. Assessment of licensees evaluation and corrective actions.
The inspectors determined that the licensee performed a comprehensive evaluation of the issue, and understood the root and contributing cause of the issue. The inspectors also determined that completed or planned corrective actions were sufficient to address the issue that led to the White PI. Thus, all objectives in IP 95001 were met. In accordance with IMC 0305, when all objectives of IP 95001 have been met for the performance issue and the PI has returned to Green, the licensee may transition back to the Licensee Response Column (Column 1) as of the date of the assessment follow-up letter.
INSPECTION RESULTS
No findings were identified.
EXIT MEETINGS AND DEBRIEFS
The inspectors verified no proprietary information was retained or documented in this report.
- On September 26, 2019, the inspectors presented the 95001 supplemental inspection results to Mr. John Krakuszeski and other members of the licensee staff.
- On September 26, 2019, NRC management, the Branch Chief, Division of Reactor Projects, Projects Branch 4, held a regulatory performance meeting with Mr. John Krakuszeski, Site Vice President, and other members of the licensee staff, in accordance with IMC 0305, Section 10.02.b.4. The NRC and licensee discussed the issues related to the White PI, including the causes, corrective actions, and extent of condition, extent of cause, and the criteria for returning Brunswick Unit 1 to the Licensee Response Column of the Action Matrix.
DOCUMENTS REVIEWED
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
95001
Corrective Action
Documents
NCR 2265623
Unit 1 Reactor Shutdown Due to Unidentified Drywell
Leakage
3/28/2019
NCR 2267651
Cryogenic Coupling Design Temperature
4/9/2019
NCR 2269746
Brunswick Unit 1 RCS Leakage NRC PI Indicator Turned
White
4/24/2019
NCR 2286932
Mock 95001 / Self Assessment AFI 1 - Part 21
8/14/2019
NCR 2286935
Mock 95001/ Self Assessment AFI 2 - RCE Comments
8/14/2019
NCR 2286939
Mock 95001 / Self Assessment AFI 3 - NCV Closure
8/14/2019
NCR 2286941
Mock 95001 / Self Assessment AFI 4 - Hardness/Strength
8/14/2019
NCR 2288231
Mock 95001 / Self Assessment AFI 5&6 - Hydrogen
Embrittlement
8/22/2019
RCE 2265623
Root Cause Evaluation Report - Failure of 1" Cryofit Coupling 3/28/2019,
Revision 1
Corrective Action
Documents
Resulting from
Inspection
293922
Cryofit coupling evidence of historical moisture
9/25/2019
Engineering
Changes
415249
Evaluation of Cryogenic Fittings Installed in the Brunswick
Nuclear Plant Unit 1
415268
Evaluation of Cryogenic Fittings Installed in the Brunswick
Nuclear Plant Unit 2
415807
Cryofit Coupling Hydrogen Embrittlement License Renewal
Aging Management Review and Program Update
Revision 1
416073
Evaluation of Cryogenic Fittings Installed in the Brunswick
Nuclear Plant
Revision 0
UFSAR Change
Number 19
FSAR-007
Add a new license renewal program description to the
UFSAR of the Cryofit Hydrogen Embrittlement Program
9/18/2019
Miscellaneous
Presentation: Brunswick Oversight Review Committee, CR
265623 Cryofit Coupling Failure
Aerofit, Aerospace Shape Memory Alloy Fluid Fitting System,
Product Handbook & Engineering Data
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
License Renewal Cryofit Coupling Hydrogen Embrittlement
Program
0E&RC-2212
Calibration/Operation of Genie Gamma Spectroscopy
System, Counting Analysis Data sheet
9/25/2019
Analysis Number
171771
Email discussion of gamma spectroscopy results of smears
from cryogenic couplings
9/26/2019
EOF Evaluation
Serial# B5164
Misapplication of Raychem "Cryofit" Couplings
9/16/1991
ESR NO 00-
00343
Cryofit Fitting, Consult with Dr. Richard Smith on Cryofit
Fittings Failures at Seabrook Plant
19-02
Brunswick RCS Leakage
5/22/2019
NRC Request 19
Cryogenic Coupling Risk Review
NRC Request 35
Summary of Installation Timeframe
QP 0583
Qualification Package for Raychem Cryofit Pipe and Tube
April/1984
Specification No.
248-108
Purchase and Installation of Cryogenic Mechanical Couplings 5
Specification No.
248-092
Specification for Instrumentation and Tubing Fittings
NDE Reports
Metallurgy Services, Bend Testing of BNP Cyrofit Couplings,
Metallurgy File #5960 - Addendum 1
9/10/2019
Procedures
248-117
Installation of Piping Systems
AD-PI-ALL-0100
Corrective Action Program
AD-PI-ALL-0101
Root Cause Evaluation
Self-Assessments AR 2283331
BNP Cryofit Coupling Failure 95001 Self-Assessment &
Mock Inspection
8/8/2019
Work Orders
20152403
Unit 1, Replace Cryogenic Coupling during B1R23, on Rx
Instrument Line thru X-69D
20152404
Unit 1, Replace Cryogenic Coupling. during B1R23, on Rx
Level Instrument line thru X-53A
20153256
Unit 2, Replace Cryogenic Coupling During B2R25,
Instrument line to B21-LT-N026A
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
20153257
Unit 2, replace cryogenic couplings during B2R25, on
instrument piping 2-B32-710
20319949 01
Unit 1, replace cryogenic coupling on Rx Level Instrument
Line
4/3/2019
20319949 16
Unit 1, replace cryogenic coupling on Rx Level Instrument
Line
4/9/2019