05000387/LER-2015-007, Regarding B Inboard Main Steam Isolation Valve, HV141 F022B Closed During Surveillance Test Which Caused a Scram

Regarding B Inboard Main Steam Isolation Valve, HV141 F022B Closed During Surveillance Test Which Caused a Scram

ML16011A102
Person / Time
Site:	Susquehanna
Issue date:	01/08/2016
From:	Franke J Susquehanna, Talen Energy
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
PLA-7429 LER 15-007-00
Download: ML16011A102 (4)

LER-2015-007, Regarding B Inboard Main Steam Isolation Valve, HV141 F022B Closed During Surveillance Test Which Caused a Scram

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(viii)(B) 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(ix)(A) 10 CFR 50.73(a)(2)(x) 10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.73(a)(2)(v)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
3872015007R00 - NRC Website

text

JAN 0 8 2016 Jon A. Franke Site Vice President U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Susquehanna Nuclear, LLC 769 Salem Boulevard Berwick, PA 18603 Tel. 570.542.2904 Fax 570.542.1504 Jon. Franke@talenenergy.com SUSQUEHANNA STEAM ELECTRIC STATION LICENSEE EVENT REPORT 50-387/2015-007-00 UNIT 1 LICENSE NO. NPF-14 PLA-7429 TALEN ~

ENERGY 10 CFR 50.73 Docket No. 50-387 Attached is Licensee Event Report (LER) 50-387/2015-007-00. The LER reports an event in which the Unit 1 'B' Inboard Main Steam Isolation Valve (HV141F022B) closed during a planned surveillance test which caused a SCRAM on Unit 1. This event was determined to be reportable in accordance with 10 CFR 50.73(a)(2)(iv)(A) as a condition that resulted in a system actuation of the reactor protection system (RPS).

There were no actual consequences to the health and safety of the public as a result of this event.

r ~~regulatory commitments.

. A. Franke Attachment: LER 50-387/2015-007-00 Copy:

NRC Region I Mr. J. E. Greives, NRC Sr. Resident Inspector Mr. M. Shields, P A DEP/BRP MS. T. E. Hood, NRC Project Manager

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 0113112017 (02-2014)

Estimated burden per response to comply with this mandatory collection request: 80 hours9.259259e-4 days <br />0.0222 hours <br />1.322751e-4 weeks <br />3.044e-5 months <br />.

• ~~-

. ~ '

Reported lessons learned are incorporated into the licensing process and fed back to industry.

\\~ '1.i LICENSEE EVENT REPORT (LER)

Send comments regarding burden estimate to the FOIA, Privacy and Information Collections

"\\".......

• Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by (See Page 2 for required number of internet e-mail to lnfocollects.Resource@ nrc.gov, and to the Desk Officer, Office of Information and Regulatory Affairs, NEOB-10202, (3150-01 04), Office of Management and Budget, Washington, DC digits/characters for each block) 20503. If a means used to impose an information collection does not display a currently valid OMB control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.

1. FACILITY NAME

12. DOCKET NUMBER

~-PAGE Susquehanna Steam Electric Station Unit 1 05000387 1 OF 3

4. TITLE Unit 1 'B' Inboard Main Steam Isolation Valve, HV141 F022B closed during surveillance test which caused a SCRAM on Unit 1

5. EVENT DATE

6. LER NUMBER

7. REPORT DATE

8. OTHER FACILITIES INVOLVED YEAR I SEQUENTIAL I REV FACILITY NAME DOCKET NUMBER MONTH DAY YEAR NO.

MONTH DAY YEAR 05000 NUMBER c'8

'"UJ /b FACILITY NAME DOCKET NUMBER 11 12 2015 2015

- 007

- 00 o l 05000

9. OEPRATING MODE

11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §:(Check all that applv!

1 D 20.2201(b)

D 20.2203(a)(3)(i)

D 50.73(a)(2)(i)(C)

D 50.73(a)(2)(vii)

D 2o.2201(d)

D 20.2203(a)(3)(ii)

D 50.73(a)(2)(ii)(A)

D 50.73(a)(2)(viii)(A)

10. POWER LEVEL D 20.2203(a)(1)

D 20.2203(a)(4)

D 50.73(a)(2)(ii)(B)

D 50.73(a)(2)(viii)(B)

D 20.2203(a)(2)(i)

D 50.36(c)(1 )(i)(A)

D 50.73(a)(2)(iii)

D 50.73(a)(2)(ix)(A) 098 D 20.2203(a)(2)(ii) 0 50.36(c)(1)(ii)(A)

[8] 50.73(a)(2)(iv)(A)

D 50.73(a)(2)(x)

D 20.2203(a)(2)(iii)

D 50.36(c)(2)

D 50.73(a)(2)(v)(A)

D 73.71(a)(4)

D 20.2203(a)(2)(iv)

D 50.46(a)(3)(ii)

D 50.73(a)(2)(v)(B)

D 73.71(a)(5)

D 20.2203(a)(2)(v)

D 50.73(a)(2)(i)(A)

D 50.73(a)(2)(v)(C) 0 OTHER D 20.2203(a)(2)(vi) 0 50.73(a)(2)(i)(B)

D 50.73(a)(2)(v)(D)

Specify in Abstract below or in

CONDITIONS PRIOR TO EVENT

Unit 1 - Mode 1, 98 percent Rated Thermal Power There were no structures, systems, or components that were inoperable at the start of the events that contributed to the event.

BACKGROUND Main Steam Isolation Valves (MSIVs) are held in the OPEN position by one AC solenoid and one DC solenoid. To have a closure of an MSIV, both of the solenoids would need to become de-energized. The surveillance testing that was being performed at the time of the SCRAM was, by design, creating a 1/2 isolation on the AC solenoid (de-energized). If a failure of either the AC or DC solenoids were to occur while the other channel has been de-energized, the MSIV would fast-close, resulting in an automatic SCRAM due to plant transient.

EVENT DESCRIPTION

On 11/12/2015 Maintenance was scheduled to perform a quarterly functional test of 'C' and 'D' Main Steam Flow Channels.

Current through the DC solenoids was read with an ammeter at a value of 58 maDC. Per the procedure, which states "approximately 50 maDC," this was an acceptable value. At 1132 hours0.0131 days <br />0.314 hours <br />0.00187 weeks <br />4.30726e-4 months <br /> the crew raised the test pressure on FIS-B21-1 N008A to obtain AC channel trip. According to personnel statement forms and operations logs, after 3-5 seconds of increased pressure the

'B' inboard MSIV closed, resulting in an automatic SCRAM of Unit 1.

Below is a series of events that led up to the SCRAM:

06/08/2015-Successfully performed surveillance 1907860 24 Month Calibration of MSIV flow channels 08/13/2015-Sl-183-207, Quarterly Functional Test of Main Steam Line C Flow Channels AlB was successfully performed with no issues.

11/06/2015-The Direct Current continuity lights, which are on each MSIV for monitoring, are found out on the Main Steam Isolation valves and control. Operations replaced the bulbs but they still did not work.

11/09/2015-A work order is generated to replace the Sector Gear on Unit 1 Channel 'C' Main Steam Line High Flow Switches 11/09/2015-The 24 Month Calibration of Main Steam Line 'C' Flow Channels FIS-B21 and 'D' Flow Channels are successfully performed.

11/09/2015-Electrical Maintenance verified the DC operability by observing the current approximately 40 Milliamps across the coil.

11/10/2015-A work order was generated to perform troubleshooting.

11/12/2015 at 1100- Maintenance performed SI-183-207(Quarterly Functional Test of C&D Flow Channels).

1132-The crew raised the test pressure on FIS-B21-1 N008A to obtain AC channel trip 1132-Automatic scram of unit 1 on high reactor pressure

CAUSE OF EVENT

The direct cause of the event was an undetected failure of a solenoid assembly located on the 1 B inboard MSIV as indicated by a measured resistance of 8 Megaohms. A report from Exelon Labs determined that the 1 B inboard MSIV solenoid assembly failed due to a burned open magnet wire at the soldered lead wire connection.

The root cause is that the station did not evaluate recommendations made in 2011 by the BWROG I&C Maintenance Committee to mitigate PC IS Group 1 Surveillance Testing Risk. While I&C Maintenance did review the owners group recommendations made in 2014, the review resulted in no action beinq taken. It was also determined as a causal factor (02-2014)

LICENSEE EVENT REPORT (LER)

CONTINUATION SHEET

1. FACILITY NAME

2. DOCKET U.S. NUCLEAR REGULATORY COMMISSION

6. LER NUMBER

3. PAGE Susquehanna Steam Electric Station Unit 1 05000387 YEAR I

SEQUENTIAL I REVI SION NUMBER NUMBER 30F 3 2015

- 007

- 0 that there was not specific guidance contained in Sl-183-306 (24 Month Calibration Main Steam C/D), which led to an inaccurate field decision when determining the cause of the extinguished light. The specified value that was obtained during troubleshooting was 40 maDC. The calculated resistance on that measurement was 88% above the vendor recommended specifications for expected resistance. The procedure allowed for interpretation of a value that did not have margin.

ANALYSIS/SAFETY SIGNIFICANCE

There were no actual consequences of this event. Unit 1 automatically shut down based on the designed activation of the safety features that are a part of the Reactor Protection System (RPS). The Unit 1 risk significance and potential consequences for the initiating event was less than 1 E-6 for Core Damage Probability (CDP) significance threshold and less than 1 E-7 for the Large Early Release Probability (LERP) significance threshold as outlined in NRC Inspection Manual Chapter (IMC) 0609. These thresholds represent a GREEN significance level and are of "Very Low Safety Significance".

CORRECTIVE ACTIONS

1.

Evaluate the BWROG I&C Maintenance Committee Recommendation to mitigate PCIS Group 1 Surveillance Testing Risk.

2.

Design and implement one of the proposed modifications from the BWROG.

3.

Using the newly developed template for performing MSIV Surveillance Testing, revise the population of procedures included in the extent of condition.

4.

Determine a conservative current reading through the MSIV's DC pilot solenoids for the I&C surveillance procedures.

5.

Identify and review the population of BWROG recommendations that were issued between January 2011 and December 2013 to ensure they have been reviewed.

COMPONENT FAILURE INFORMATION

The 1 B Inboard MSIV solenoid assembly failed due to a burned open magnet wire at the soldered lead wire connection. Although a contributing factor could not be identified, Exelon Labs stated that this is a common failure location due to either tool indentations and/or mechanical stress during fabrication.

PREVIOUS SIMILAR EVENTS

No other similar events were identified. *