ML16245A294

LER 16-008-00 for Davis-Besse Nuclear Power Station, Unit 1 Regarding Application of Technical Specification for the Safety Features Actuation System Instrumentation

ML16245A294
Person / Time
Site:	Davis Besse
Issue date:	08/30/2016
From:	Boles B D FirstEnergy Nuclear Operating Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
L-16-239 LER 16-008-00
Download: ML16245A294 (6)

Text

FE NOCŽ RrstEnergy Nuclear Operating Company Brian D. Boles Vice President, Nuclear August30,2016 L-16-239 ATTN: Document Control Desk United States Nuclear Regulatory Commission Washington, D.C. 20555-0001

Subject:

Davis-Besse Nuclear Power Station, Unit 1 Docket Number 50-346, License Number NPF-3 Licensee Event Report 2016-008 5501 North State Route 2 Oak Harbor. Ohio 43449 10 CFR 50.73 419-321-7676 Fax: 419-321-7582 Enclosed is Licensee Event Report (LER) 2016-008-00, "Application of Technical Specification for the Safety Features Actuation System Instrumentation." This event is being reported pursuant to 10 CFR 50. 73(a)(2)(i)(B).

There are no regulatory commitments contained in this letter or its enclosure.

The actions described represent intended or planned actions and are described for information only. If there are any questions or if additional information is required, please contact Mr. Patrick J. McCloskey, Manager-Site Regulatory Compliance, at (419) 321-7274.

Sincerely, Brian D. Boles vaw

Enclosure:

LER 2016-008-00 cc: NRC Region Ill Administrator NRC Resident Inspector NRR Project Manager Utility Radiological Safety Board NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 1013112018 (11-2015)

Estimated burden per response to comply with this mandatory collection requ*est:

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.

Send D commenls regarding burden estimate to the FOIA, Privacy and Information Collections Branch (T-s =

• LICENSEE EVENT REPORT (LER) 5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by internet e-:i mail to lnfocollects.Resource@nrc.gov, and to the Desk Officer, Office of Information and Regulatory

..... (See Page 2 for required number of Affairs, NEOB-10202, (3150-0104), Office of Management and Budget, Washington, DC 20503. digits/characters for each block) 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 2. DOCKET NUMBER 3. PAGE Davis-Besse Nuclear Power Station, Unit 1 05000 346 1 OF 5 4. TITLE: Application of Technical Specification for the Safety Features Actuation System Instrumentation

5. EVENT DATE 6. LER NUMBER 7. REPORT DATE 8. OTHER FACILITIES INVOLVED I SEQUENTIAL I REV FACIL\1Y NAME DOCKET NUMBER MONTH DAY YEAR YEAR NUMBER NO. MONTH DAY YEAR 05000 FACIL\1Y NAME DOCKET NUMBER 06 30 2016 2016 -008 -00 08 30 2016 05000 9. OPERATING MODE 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR§: (Check all that apply) D 20.2201 (b) D 20.2203(a)(3)(i)

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

D S0.73(a)(2)(viii)(A) 1 D 20.2201 (d) D 20.2203(a)(3)(ii)

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

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

D 20.2203(a)(1)

D 20.2203(a)(4)

D so.73(a)(2)(iii)

D 50.73(a)(2)(ix)(A)

D 20.2203(a)(2)(i)

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

D 50.73(a)(2)(iv)(A)

D 50.73(a)(2)(x)

10. POWER LEVEL D 20.2203(a)(2)(ii)

D 50.36(c)(1)(ii)(A)

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

D 73.71(a)(4)

D 20.2203(a)(2)(iii)

D so.36(c)(2)

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

D 73.71(a)(5)

D 20.2203(a)(2)(iv)

D so.46(a)(3)(ii)

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

D 73.77(a)(1) 100 D 20.2203(a)(2)(v)

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

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

D 73.77(a)(2)(i)

D 20.2203(a)(2)(vi)

[gj 50. 73(a)(2)(i)(B)

D 50.73(a)(2)(vii)

D 73.77(a)(2)(ii) li*1; f.;). t\Jci<. {,'t ;'j < :: D 50.73(a)(2)(i)(C)

D OTHER Specify in Abstract below or in NRC Form 366A 12. LICENSEE CONliJ\CT FOR THIS LER LICENSEE CONTACT: !TELEPHONE NUMBER (Include Area Cqde) Vicki Wadsworth, Senior Nuclear Engineering Specialist-Regulatory Compliance (419) 321-7690 13. COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT CAUSE SYSTEM COMPONENT MANU-REPORTABLE I CAUSE SYSTEM COMPONENT MANU-REPORTABLE FACTURER TOEPIX FACTURER TOEPIX 14. SUPPLEMENTAL REPORT EXPECTED 15. EXPECTED MONTH DAY YEAR [gj YES (ff yes, complete 15. EXPECTED SUBMISSION DATE) ONO SUBMISSION 10 31 2016 u DATE ABSTRACT (Limit to 1400 spaces, i.e .. approximately 15 single-spaced typewritten lines) On June 30, 2016, at 0829, with the Davis-Besse Nuclear Power Station in Mode 1 and at approximately 100 percent power, a Borated Water Storage Tank (BWST) level transmitter for Safety Features Actuation System (SFAS) Channel 1 was declared inoperable for scheduled maintenance and Technical Specification (TS) Limiting Condition of Operation (LCO) 3.3.5, Condition A was entered. At 2342 hours0.0271 days <br />0.651 hours <br />0.00387 weeks <br />8.91131e-4 months <br />, a power supply in SFAS Channel 2 failed and a separate condition of TS LCO 3.3.5, Condition A entered. On July 1, 2016 at 0245 hours0.00284 days <br />0.0681 hours <br />4.050926e-4 weeks <br />9.32225e-5 months <br />, upon recognition that two channels of SFAS were inoperable, TS LCO 3.3.5, Condition B for two channels of SFAS being inoperable was entered upon realization of the omission.

At 0330 hours0.00382 days <br />0.0917 hours <br />5.456349e-4 weeks <br />1.25565e-4 months <br />, it was believed that SFAS Channel 1 could be considered operable with manual and compensatory actions and Condition B was exited with no action having been taken to initiate a plant shutdown.

After further management review, it was later determined the compensatory actions could not be supported and therefore, TS LCO 3.3.5, Condition B was re-entered at 1325. SFAS Channel 1 was restored and declared operable at 1351 hours0.0156 days <br />0.375 hours <br />0.00223 weeks <br />5.140555e-4 months <br />. The cause of this event is under evaluation.

The condition is being reported in accordance with 10 CFR 50. 73(a)(2)(i)(B) as. an operation or condition prohibited by the plant's Technical Specifications.

' NRC FORM 366 (11-2015)

Page 2 of 5 NRC FORM 366A (11-2015)

U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2018 LICENSEE EVENT REPORT (LER) CONTINUATION SHEET 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.

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 internet e-mail to lnfocollects.Resource@nrc.gov, and to the Desk Officer, Office of Information and Regulatory Affairs, NEOB-10202, (3150-0104), Office of Management and Budget, Washington, DC 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 2. DOCKET NUMBER Davis-Besse Nuclear Power Station Unit 1 05000-346 YEAR 2016 NARRATIVE Energy Industry Identification System (EllS) codes are identified in the text as [XX]. DESCRIPTION OF OCCURRENCE:

System

Description:

3. LER NUMBER SEQUENTIAL NUMBER 008 REV NO. 00 The Safety Features Actuation System (SFAS) [JE] at the Davis-Besse Nuclear Power Station (DBNPS) is designed to automatically prevent or limit fission product and energy release from the core, to isolate the containment vessel and to initiate the operation of Engineered Safety Features equipment in the event of a loss of coolant accident and main steam line break. The SFAS operates in a distributed manner to initiate the appropriate systems. The SFAS does this by determining the need for actuation in each of four channels monitoring each actuation parameter.

Once the need for actuation is determined, the condition is transmitted to automatic actuation logics, which perform the two-out-of-four logic to determine the actuation of each end device. Four plant parameters are used for automatic SFAS actuation.

The fifth parameter, the Borated Water Storage Tank (BWST) [BP-T] Level -Low Low, is used to provide a permissive to allow manual transfer from the BWST to the containment emergency sump. The SFAS consists of four ideritical redundant instrument (sensing) and logic channels and two identical redundant actuation channels, and each instrument channel includes trip bistable modules with digital isolation devices. The isolated output of the trip bistable module is used to comprise coincidence matrices with the terminating relays within the actuation channel of the SFAS. The trip bistables monitor the station variables and normally feed continuous electrical (fail-safe) signals into two-out-of-four coincidence matrices.

Should any of the station variables exceed their trip setpoints, the corresponding bistables in each of the four channels will trip and cease sending output signals. If two of the four channel bisfables monitoring the same station variable cease to send output signals, the corresponding normally-energized terminating relays on all channels will trip. The SFAS is a fail-safe, de-energize to trip, system. Therefore, if the power supply to a channel is lost, that cha.nnel will trip, reducing system coincidence matrices from two-out-of-four to one-out-of-three mode. The terminating relays of sensing and logic channels 1 and 3 must both be de-energized to activate safety actuation channel 1. Similarly, sensing and logic channels 2 and 4 must both be de-energized to activate safety actuation channel 2. The terminating relays (also known as output relays) [JE-RL Y] act on the actuation control devices such as motor controllers and solenoid valves. The BWST supplies borated water for emergency core cooling via the Decay Heat Removal/Low Pressure Injection (LPI) System [BP] and High Pressure Injection (HPI) System [BJ], and as a source of borated water for the Containment Spray System [BE]. During accident conditions, the BWST provides containment cooling and depressurization, core cooling, and replacement inventory and is a source of negative reactivity for reactor shutdown.

The BWST ensures that an adequate supply of borated water is available to cool and depressui"ize the containment in the event of a Design Bases Accident (OBA); to cool and cover the core in the event of a Loss of Coolant Accident (LOCA.), and to ensure an adequate level exists in the containment sump to support ECCS and containment spray pump operation in the recirculation mode. The BWST level is monitored by four independent level transmitters.

Each of the differential pressure signals . generated by these transmitters is monitored by a bistable to provide a trip signal at a low low level. The

• BWST allowable value of greater than or equal to 101.6 inche.s of water and less than or equal to 115.4 NRC FORM 366A (11-2015)

Page 3 NRC FORM 366A (11-2015)

U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2018 LICENSEE EVENT REPORT (LER) CONTINUATION SHEET 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.

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 internet e-mail to lnfocollects.Resource@nrc.gov, and to the Desk Officer, Office of Information and Regulatory Affairs, NEOB-10202, (3150-0104), Office of Management and Budget, Washington, DC 20503. If a means used to impose an information collection does not display a currently valid OMB control number, the NRG may not conduct or sponsor, and a person is not required to respond to, the information collection.

1. FACILITY NAME 2. DOCKET NUMBER 3. LER NUMBER Davis-Besse Nuclear Power Station Unit 1 05000-346 YEAR SEQUENTIAL NUMBER REV NO. 2016 008 NARRATIVE DESCRIPTION OF OCCURRENCE: (continued) inches of water was chosen to provide the operator with an alarm and a permissive to allow timely operation of the BWST outlet and containment emergency sump valves to the long term recirculation position.

This is to protect the pumps from cavitation for lack of proper net positive suction head and allow transfer of ECCS suction to the containment emergency sump from the BWST during the recirculation mode of operation before the inventory of the BWST is depleted.

Technical Specification(s):

Technical Specification (TS) Limiting Condition for Operation (LCO) 3.3.5 requires four channels of SFAS instrumentation for each parameter to be operable in each SFAS train. Failure of any instrument renders the affected channel( s) inoperable and reduces the reliability of the affected parameter and affected systems or components.

With one or more parameters with one channel inoperable, Condition A requires one channel be placed in trip in one hour. With one channel placed in trip in an hour and Condition A not met, or one or more parameters with two or more channels rendered inoperable, Condition B requires the unit to be in Mode 3 in 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and Mode 5 within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. DESCRIPTION OF EVENT: The evaluation of this event is ongoing. The following description of the event is preliminary and subject to change, and will be updated via revision to this Licensee Event Report upon completion of the evaluation.

On June 30, 2016, at 0829, the DBNPS operating in Mode 1 at approximately 100 percent power, BWST SFAS Channel 1 Level Transmitter LT1525A was taken out of service for maintenance to replace the enclosure box and for calibration activities.

SFAS Channel 1 was declared inoperable and TS LCO 3.3.5, Condition A was entered and the associated bistable for BWST Level was tripped. At 2342 hours0.0271 days <br />0.651 hours <br />0.00387 weeks <br />8.91131e-4 months <br /> with LT1525A still out of service, a failure of SFAS Channel 2 +15 Volt Power Supply occurred, rendering the SFAS Channel 2 inoperable, including SFAS Channel 2 BWST level instrument LT15258. BWST Level Transmitters for SFAS Channel 3 (LT1525C) and SFAS Channel 4 (LT1525D) remained operable.

A separate entry into TS LCO 3.3.5 Condition A was made at 2342 hours0.0271 days <br />0.651 hours <br />0.00387 weeks <br />8.91131e-4 months <br />, but no entry into TS LCO 3.3.5 Condition B was made. On July 1, 2016, at 0245 hours0.00284 days <br />0.0681 hours <br />4.050926e-4 weeks <br />9.32225e-5 months <br /> following a plant Duty Team discussion where the condition was re-assessed, the proper additional TS LCO 3.3.5, Condition B was entered as required for two channels of BWST level functions inoperable, which requires a plant shutdown to Mode 3 in 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />. Following further discussions, between Operations and some Duty Team personnel, it was believed that SFAS Channel 1 could be considered operable with manual and compensatory actions due to the BWST Level -Low Low level being a transfer permissive that allows transfer to the Emergency Sump with less than nine feet of level in the BWST. The compensatory actions were specific to SFAS Channel 1. Therefore, Operations exited TS LCO 3.3.5 Condition B at 0330 hours0.00382 days <br />0.0917 hours <br />5.456349e-4 weeks <br />1.25565e-4 months <br />. 06 After further management review, at 1325 hours0.0153 days <br />0.368 hours <br />0.00219 weeks <br />5.041625e-4 months <br /> it was determined the compensatory actions associated with BWST Level -Low Low level transmitter could not be supported and the previous operability determination for SFAS Channel 1 was invalid. Operations re-entered TS LCO 3.3.5, Conditions A and B. NRC FORM 366A (11-2015)

Page 4 of 5 NRC FORM 366A (11-2015)

U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2018 LICENSEE EVENT REPORT (LER) CONTINUATION SHEET 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.

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 internet e-mail to lnfocollects.Resource@nrc.gov, and to the Desk Officer, Office of Information and Regulatory Affairs, NEOB-10202, (3150-0104), Office of Management and Budget, Washington, DC 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 lo, the information collection.

1. FACILITY NAME 2. DOCKET NUMBER Davis-Besse Nuclear Power Station Unit 1 05000-346 NARRATIVE DESCRIPTION OF EVENT: (continued)

YEAR 2016 3. LER NUMBER SEQUENTIAL NUMBER 008 Upon completion of maintenance and successful testing, SFAS Channel 1 BWST Level Transmitter (L T1525A) was declared operable at 1351 hours0.0156 days <br />0.375 hours <br />0.00223 weeks <br />5.140555e-4 months <br /> and TS LCO 3.3.5 Condition B was exited. Upoh replacement and testing of the +15 Volt power supply, SFAS Channel 2 was declared operable and TS LCO 3.3.5 Condition A was exited at 1800 hours0.0208 days <br />0.5 hours <br />0.00298 weeks <br />6.849e-4 months <br /> on July 1, 2016. CAUSE OF'EVENT ) The cause of this event is under evaluation and will be provided in a revision to this Licensee Event Report. ANALYSIS OF EVENT The BWST Level Transmitters monitor the BWST Level and initiate an SFAS Level 5 signal on BWST Level -Low Low. This output signal provides a passive permissive interlock to allow operators the ability to shift ECCS suction from the BWST to the Emergency Sump by allowing operators to open the Decay Heat Pump Suction From Emergency Sump Valves and close tlie associated BWST Isolation Valves. The transfer of suction source from the BWST to the Emergency Sump is a manual transfer.

The Probabilistic Risk Analysis (PRA) models failure of the SFAS Level 5 permissive signal, as well as failure of the valves 'to be repositioned

• (or failure of the human action to manually transfer the suction), which could result in the inability of the plant to shift ECCS suction from the BWST to the Emergency Sump. The four-channel SFAS system is a 2-out-of-four circuit, such that any two level instruments which sense a BWST Level -Low Low will actuate the permissive interlock for both trains. With both L T1525A and L T1525B out of service, the SFAS BWST Level -Low Low passive permissive transfer was active (i.e., the valves could be repositioned to shift from the BWST to the Emergency Sump) as indicated by Annunciator 5-3-A., BWST LO-LO LVL XFER TO EMER SUMP. Since the permissive interlock was met, a failure of this SFAS Level 5 permissive signal is not possible.

Having the transfer permissive interlock active while the BWST was still full could permit operators to inadvertently transfer suction from the BWST to the Emergency Sump (violating procedure guidance) before there was adequate volume in the Emergency Sump. Additionally, having the transfer permissive annunciator 5-3-A lit significantly prior to reaching the BWST Level procedurally directing the transfer to the Emergency Sump could potentially increase the probability that the Operators would not take the action to transfer suction when the appropriate level was reached. However, by procedure and by 'training, Operators would monitor, log, and trend BWST level, so they would be aware when the proper time to transfer occurred, and there would be minimal increase in the failure to perform the required action. Based on the above, the condition of having two BWST Level Transmitters out of service does not result in an increase in CDF, as calculated by thePRA model, and this condition would be considered to have a very low safety significance.

NRC FORM 366A (11-2015)

REV NO. 00 Page 5 of 5 NRC FORM 366A (11-2015) .U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2018 LICENSEE EVENT REPORT (LER) CONTINUATION SHEET 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.

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 internet e-mail to lnfocollects.Resource@nrc.gov, and to the Desk Officer, Office of Information and Regulatory Affairs, NEOB-10202, (3150-0104), Office of Management and Budget, Washington, DC 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 2. DOCKET NUMBER Davis-Besse Nuclear Power Station Unit 1 05000-346 NARRATIVE Reportability Discussion:

YEAR 2016 3. LER NUMBER SEQUENTIAL NUMBER 008 On June 30, 2016, at 2342 hours0.0271 days <br />0.651 hours <br />0.00387 weeks <br />8.91131e-4 months <br />, with the failure of SFAS Channel 2 Power supply, and SFAS Channel 1 BWST Level Transmitter previously declared inoperable for maintenance, TS 3.3.5, Condition B should have been entered due to the BWST parameter being inoperable for two channels of SFAS, requiring a 6-hour shutdown of the unit. However, as described above, while Condition B was entered on July 1, 2016 at 0245 hours0.00284 days <br />0.0681 hours <br />4.050926e-4 weeks <br />9.32225e-5 months <br />, it was inappropriately exited at 0330 hours0.00382 days <br />0.0917 hours <br />5.456349e-4 weeks <br />1.25565e-4 months <br />, and no shutdown initicited.

Because the unit continued to operate after July 1, 2016, at 0542 hours0.00627 days <br />0.151 hours <br />8.96164e-4 weeks <br />2.06231e-4 months <br /> with two channels of SFAS inoperable, this represents continued operation or condition prohibited by the plant's Technical Specifications, which is reportable per 10 CFR 50.73(a)(2)(i)(B).

On July 10, 2016, a retrospective notification was made to the NRC (Event Number 52079) for initiation of a plant shutdown as required by the TS that should have been made in accordance with 10 CFR 50.72(b)(2)(i).

All safety systems performed as required in response to the event, and no loss of safety function occurred.

CORRECTIVE ACTIONS: Completed Actions:

Upon completion of maintenance and successful testing, SFAS Channel 1 BWST Level Transmitter . (L T1525A) was declared operable .at 1351 hours0.0156 days <br />0.375 hours <br />0.00223 weeks <br />5.140555e-4 months <br /> on July 1, 2016. Upon replacement and testing of the +15 Volt power supply, SFAS Channel 2 was declared operable at 1800 hours0.0208 days <br />0.5 hours <br />0.00298 weeks <br />6.849e-4 months <br /> on July 1, 2016. A standing order was issued on July 6, 2016 to reinforce the expectations for review of TS and Operability Determinations, and Duty Team and Licensed Operator standards and expectations.

Scheduled Actions: Because the cause of this issue is still under evaluation, additional corrective actions will be provided in a revision to this Licensee Event Report. PREVIOUS SIMILAR EVENTS '/ DBNPS LER 2015-001 documents that the seismic BWST had been aligned in the past to the non-seismic Spent Fuel Pool system for purification.

This rendered the BWST inoperable for periods of time longer than allowed per Technical Specification 3.5.4 while the plant was operating in Modes 1 through 4. However, this previous condition was not associated with the SFAS transfer permissive on BWST Level -Low Low, and the corrective actions taken for the previous event are not applicable to the current event. NRC FORM 366A (11-2015)

REV NO. 00