05000461/LER-2016-003

LER-2016-003, Bypassing Both Divisions of Reactor Water Cleanup Leak Detection System is a Reportable Loss of Safety Function

Clinton Power Station, Unit 1
Event date:	03-24-2016
Report date:	5-23-2016
Reporting criterion:	10 CFR 50.73(a)(2)(v)(C), Loss of Safety Function - Release of Radioactive Material
4612016003R00 - NRC Website

LER 16-003-00 for Clinton Power Station, Unit 1 Regarding Bypassing Both Divisions of Reactor Water Cleanup Leak Detection System is a Reportable Loss of Safety Function

ML16146A543
Person / Time
Site:	Clinton
Issue date:	05/23/2016
From:	Stoner T R Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
SRRS 5A.108, U-604283 LER 16-003-00
Download: ML16146A543 (5)

Reported lessons teamed 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 intemet e-mail to Infocollects.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.

PLANT AND SYSTEM IDENTIFICATION

General Electric—Boiling Water Reactor, 3473 Megawatts Thermal Rated Core Power Energy Industry Identification System (EIIS) codes are identified in the text as [XX]

EVENT IDENTIFICATION

Bypassing Both Divisions of Reactor Water Cleanup Leak Detection System is a Reportable Loss of Safety Function A. Plant Operating Conditions before the Event Clinton Power Station, Unit 1 05000461 Unit: 1 Event Date: 03/24/16 Event Time: 1157 Mode: 1 Mode Name: Power Operation Reactor Power: 99 percent

B. DESCRIPTION OF EVENT

On March 24, 2016, it was determined that placing both Reactor Water Cleanup System (RT) Leak Detection System (LD) bypass switches in the Bypass position per Clinton Power Station (CPS) Procedure 3301.01, "Reactor Water Cleanup" when the RT Filter/Demineralizer (F/D) was placed in service following backwash and pre-coat operations was a reportable condition. It was determined from the Operations Log for January 25, 2016 that both divisions of the RT LD were bypassed for seven minutes.

The following Operations log entries document the actions taken on January 25, 2016:

0940: Placed 'A' RT F/D in Hold for backwash and pre-coat per procedure CPS 3303.01 section 8.1.3 and procedure CPS 3303.02, "Reactor Water Cleanup Filter Demineralizer Operating Procedure," sections 8.2 and 8.5.

1155: Placed RT F/D 'B' in Hold.

1157: When pressurizing RT F/D 'A' received RT differential flow alarm. Placed both divisions of RT LD in Bypass, this will render both RWCU differential flow instruments INOPERABLE.

Verified Dose Equivalent Iodine 1-131 specific activity is x 10e-6 µCi/gm) per CPS 3303.01 step 6.9 and Technical Specification (TS) Limiting Condition for Operation (LCO) 3.3.6.1, "Primary Containment and Drywell Isolation Instrumentation." Entered the following action statements: - LCO 3.3.6.1, Required Action D.1 - Place channel in trip in 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and LCO 3.3.6.1 Required Action E.1 - Restore RT isolation capability in 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />.

1159: Placed RT F/D 'B' on Service following backwash of 'A' F/D.

1202: Placed RT F/D 'A' on Service following backwash.

1204: Placed both divisions of RT LD bypass switches in Normal. Performed channel check SAT. Exit LCO 3.3.6.1 Required Action D.1 and E.1 actions.

An evaluation determined that placing both divisions of the RT LD switches in the Bypass position represented a loss of safety function that was not part of a planned evolution for maintenance or testing. Backwashing and pre-coating a RT F/D, as indicated in the Operations Log, is a normal system operation and not considered maintenance. Therefore, placing both divisions of RT LD switches in Bypass was reportable. The Updated Safety Analysis Report (USAR), the TS Bases, and NRC reporting requirements were reviewed as part of an evaluation regarding event reportability. Based on this review, it was determined that the RT LD system is credited to mitigate a break in the RT system piping inside containment accident as described in USAR Chapter 6. As a result, it was concluded that placing both divisions of RT LD switches in Bypass as described in this LER, represented a condition that could have prevented the fulfillment of the safety function of a system that is needed to mitigate the consequences of an accident described in USAR Chapters 6 and 15. This condition is reportable under 10 CFR 50.73(a)(2)(v)(C).

A change to the RT system procedure was implemented in 1989 to allow placing RT LD bypass switches into Bypass to prevent an unwanted or unwarranted isolation of the RT system during system manipulations. The associated safety evaluation went through several levels of management concurrence. Based on the reporting guidelines in place at the time, placing both divisions of RT LD in Bypass did not constitute a reportable event. However, NUREG-1022, Rev.

3 indicates that a report is required when SSCs are inoperable in a required mode unless as part of a planned evolution for maintenance or surveillance testing when done in accordance with an approved procedure and the plant's TS.

C. CAUSE OF EVENT

The apparent cause of the failure to report this event was the failure to perform plant procedure revisions when Exelon Generating Company (EGC) fleet reporting procedure requirements changed with the implementation of NUREG-1022, Revision 3. Plant procedure revisions did not occur because the change management process applied in this instance did not require an Operations cross-functional review when the EGC fleet reporting procedure was issued.

D. SAFETY ANALYSIS

This event had no actual nuclear safety consequences.

RT recirculates a portion of reactor coolant through a filter demineralizer to remove particulate and dissolved impurities from the reactor coolant. It also removes excess coolant from the reactor system under controlled conditions. RT is not required to function during or immediately following an accident and is isolated from post-accident fluids.

The purpose the RT LD System is to monitor RT components, activating a system isolation should a system leak of sufficient magnitude occur. Other operational controls remained available to monitor RT parameters, including temperature detection in the affected areas to allow isolation of the RT System.

E. CORRECTIVE ACTIONS

A standing order was put into place to require reporting if both divisions of RT LD bypass switches are placed in Bypass unless if it is part of a planned evolution for maintenance or testing.

CPS Procedures 3303.01 and 5000.02, "Alarm Panel 5000 Annunciators —Row 2," have been revised to indicate that placing both RT leak detection system switches in the bypass position at the same time while in modes 1, 2 or 3 for reasons other than to support maintenance or testing is a reportable event per 10CFR50.72 and 10CFR50.73. An action was also created to review other Operations procedures to determine if a safety function is bypassed for reasons other than maintenance or testing.

F. PREVIOUS SIMILAR OCCURENCES

No previous events were identified associated with the failure to report bypassing a safety function.

G. COMPONENT FAILURE DATA

There were no component failures associated with this event.