05000317/LER-2016-004

LER-2016-004, High Energy Line Break Barrier Breeched Due to Human Performance Error Causing Both Service Water Trains to be Inoperable

Calvert Cliffs Nuclear Power Plant, Unit 1
Event date:	11-13-2015
Report date:	07-20-2016
Reporting criterion:	10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor
3172016004R00 - NRC Website

LER 16-004-00 for Calvert Cliffs, Unit 1 Regarding High Energy Line Break Barrier Breeched Due to Human Performance Error Causing Both Service Water Trains to be Inoperable

ML16204A377
Person / Time
Site:	Calvert Cliffs
Issue date:	07/20/2016
From:	Flaherty M D Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
LER 16-004-00
Download: ML16204A377 (7)

I. DESCRIPTION OF EVENT:

Energy Industry Identification System (EIIS) codes are identified in the text as [XX].

A. INITIAL CONDITIONS:

Unit 1 was operating at 100 percent power in Mode 1 prior to the event.

B. EVENT:

On October 19 and 21, 2015, the No. 11 Service Water (SRW) [BI] pump [P] motor [MO] was replaced, which required opening of a high energy line break (HELB) barrier, specifically Door 214 [DR]. This door separates the turbine building [NM] from the SRW pump room. During the SRW motor replacement activity, a new SRW motor was moved into the SRW room and the old SRW motor was moved out. The movement of the motor involved using a chain fall to move the motor from a cart stationed on one side of the door to a cart stationed on the other side of the door. The barrier was opened for approximately three and a half minutes for each movement.

Compensatory measures were taken to station dedicated personnel at the barrier to restore the barrier to its design basis configuration during any plant transient or event. The HELB barrier was restored to its design configuration following each motor move. The work order which controlled the open barrier did not consider the barrier blocked during motor movement based on an existing station procedure (EN-1-135, Control of Barriers).

This HELB barrier breech should have been evaluated in accordance with procedure CC-AA-201, Plant Barrier Control Program. This procedural process provides for an evaluation of a barrier breech and provides compensatory actions. The barrier control actions developed per this procedure should have been part of the work orders for the SRW pump motor replacement, but were not included because the procedure was not followed. This procedure provides more comprehensive guidance than the station procedure for this situation. The procedure was not followed because the Maintenance Planners were not aware of the procedure's implementation because they were unaware of the barrier control procedure requirements. The apparent cause of the event was that the assigned change management agent (an Engineer) failed to inform Maintenance Planners of the implementation of the barrier procedure.

As a result of not following the barrier control program, the risk associated with opening the barrier was not sufficiently understood and the impact to equipment operability for equipment protected by the barrier was not understood. Additionally, appropriate compensatory measures were not properly evaluated. If the barrier control program had been correctly utilized, Technical Specification (TS) Conditions should have been entered for affected equipment. This would have required both trains of SRW to be declared inoperable because they are not qualified for the steam environment that is postulated to exist following a HELB. Declaring both trains of SRW inoperable results in a loss of safety function for a system needed to respond to a HELB to provide safe shutdown of the reactor, remove residual heat and mitigate the consequence of an accident. In addition, this condition also results in an unanalyzed condition that significantly degrades plant safety and a common cause inoperability of independent trains.

A single train of Auxiliary Feedwater (AFW) [BA] was also affected, as were support equipment for other TS components.

TO THE EVENT:

There were no structures, systems, or components inoperable at the start of the event that contributed to the event.

D. DATES AND APPROXIMATE TIMES OF MAJOR OCCURRENCES:

October 19, 2015 — SRW HELB barrier is opened for approximately three and a half minutes to move SRW pump motor into the SRW pump room. The SRW HELB barrier closed following the move of the SRW pump into the SRW pump room.

October 21, 2015 — SRW HELB barrier is opened for approximately three and a half minutes to move old SRW pump motor out of the SRW pump room. The SRW HELB barrier closed following the move of the old SRW pump out of the SRW pump room.

November 13, 2015 — Issue Report (IR) 2586773 was written to document that the work order (WO 120070650) did not contain a barrier impairment permit as required by procedure CC-AA-201.

February 9, 2016 — Inspection Report 05000317/2015004 and 05000318/2015004 was issued from the NRC describing the green Non-Cited Violation (NCV) of Technical Specification 5.4.1 for failure to implement procedures as required by Regulatory Guide 1.33, Appendix A.

February 14, 2016 — IR 2625943 was written to require appropriate evaluation of the green NCV. An evaluation was completed and corrective actions developed.

July 1, 2016 — Regulatory Assurance personnel were contacted by the NRC Resident Inspector requesting information related to a Licensee Event Report (LER) for the above described issue.

No LER was located. IR 2688409 was written.

E. FAILURE MODES:

There are no equipment failure modes.

F. METHOD OF DISCOVERY:

The event should have been determined to be a reportable event following determination that the correct barrier control procedure was not followed on November 13, 2015. However, at that time, the conduct of maintenance for this work order was believed to be acceptable. Receipt of NRC Inspection Report 05000317/2015004 and 05000318/2015004 was an additional opportunity to address the reportable aspect of this event. This event is documented in the site's Corrective Action Program under IRs 2586773 and 2625943.

II. CAUSE OF EVENT

The cause of the event was human performance related. The work order that provided direction for the movement of the SRW motor into and out of the SRW pump room did not contain the required barrier impairment permit as required by procedure CC-AA-201. The reason the work order did not contain the barrier impairment permit is that the implementation of the procedure was not effectively communicated to Maintenance Planners by the Engineer responsible for the procedure implementation. Therefore, the Maintenance Planners were not aware that a barrier impairment permit was needed for the work order. Use of the barrier impairment permit process would have resulted in different actions being taken to perform this maintenance task.

The apparent cause of the event was that an Engineer failed to provide adequate change management for the implementation of the barrier procedure. Therefore, Maintenance Planners did not include the proper barrier controls in the work order that opened the HELB barrier.

Corrective actions were to brief affected groups about the barrier control procedure. Corrective action for the human performance issue was handled through the performance management system.

A. SAFETY CONSEQUENCES:

The safety consequence of this event was that equipment required to respond to a HELB event in the turbine building was not protected from the HELB event itself. Equipment required to respond to a HELB event is listed in UFSAR Table 10A-6, "Mechanical and Electrical Equipment Required to Place the Plant in a Safe Shutdown Condition." The table lists the SRW pump, the motor-driven AFW pump [P] and components that rely on the safety related saltwater air compressors (SWACs) [LE] [CMP] as equipment that is located outside a steam environment during a turbine building HELB. With the SRW pump room door open, this equipment would have been exposed to a steam environment that it was not analyzed for. Therefore, the equipment would be assumed unavailable to respond to a HELB event to bring the plant to a safe shutdown condition. A loss of SRW would result in the loss of one of two emergency diesel generators [DG], which would leave one emergency diesel generator to respond to the event and bring the plant to a safe shutdown condition. The loss of the motor driven AFW train would leave two steam driven AFW pumps to respond to the event and bring the plant to a safe shutdown condition. The loss of the SWACs would require operator action during the course of an event to mitigate that loss.

When the HELB barrier was opened, the SRW systems behind the barrier should have been declared inoperable per the TSs. For the SRW system, TS LCO 3.0.3 should have been entered. For the, auxiliary feedwater system, TS LCO 3.0.9 should have been entered for one train out of service. There is no TS for the SWACs. These TSs have Actions that are longer than the approximately three and a half minutes that the SRW pump room door was opened.

Therefore, no TSs were violated during this event.

The subject condition satisfies the criteria in NUREG-1022, Revision 3, for an event or condition that could have prevented the fulfilment of a safety function for a system needed to respond to a HELB to provide safe shutdown of the reactor, remove residual heat and mitigate the consequence of an accident, due to the loss of both trains of SRW. Therefore, this event is reportable pursuant to 10 CFR 50.73(a)(2)(v)(A) and (B) and (D). In addition, this condition also results in an unanalyzed condition that significantly degrades plant safety based on the loss of safety function and is reportable pursuant to 10 CFR 50.73(a)(2)(ii)(B). This condition also caused a common cause inoperability of independent trains, since the open barrier (common cause) affected both (independent) trains of SRW. This is reportable pursuant to 10 CFR 50.73(a)(2)(vii).

B. CORRECTIVE ACTIONS:

IR 2625943 was written to require appropriate evaluation of the green NCV received from the NRC in Inspection Report 05000317/2015004 and 05000318/2015004. The work group evaluation determined that the apparent cause of the event was that an Engineer failed to provide adequate change management for the implementation of the barrier control procedure by not briefing all affected organizations. Action was taken to provide a briefing to all potentially affected work groups on site. Corrective action for the human performance issue was handled through the performance management system.

III. PREVIOUS SIMILAR EVENTS:

A review of Calvert Cliffs' events over the past several years was performed and no similar instances were found.

COMPONENT

IEEE 803 IEEE 805

FUNCTION ID SYSTEM ID

None