ULNRC-06142, SR-14-002 Callaway, Unit 1 - Special Report 2014-02-PAM Report Inoperability of Post Accident Monitoring (PAM) Instrument

SR-14-002 Callaway, Unit 1 - Special Report 2014-02-PAM Report Inoperability of Post Accident Monitoring (PAM) Instrument

ML14259A591
Person / Time
Site:	Callaway
Issue date:	09/16/2014
From:	Hall D Ameren Missouri, Union Electric Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
ULNRC-06142 SR-14-002
Download: ML14259A591 (5)

Text

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WAmeren Callaway Plant MISSOURI September 16, 2014 ULNRC-06142 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Ladies and Gentlemen:

DOCKET NUMBER 50-483 CALLAWAY PLANT UNIT 1 UNION ELECTRIC CO.

FACILITY OPERATING LICENSE NPF-30 SPECIAL REPORT 2014 PAM REPORT INOPERABILITY OF A POST ACCIDENT MONITORING (PAM) INSTRUMENT

Reference:

ULNRC-06139 dated September 2, 2014, "Special Report 2014 PAM Report Inoperability of a Post Accident Monitoring (PAM) Instrument" Enclosed Special Report 2014-02 (PAM Report) addresses inoperability of the Reactor Vessel Level Indicating System (RVLIS). Since the period of inoperability for the Reactor Vessel Level Indicating System (RVLIS) has exceeded the Completion Times specified within Technical Specification (TS) 3.3.3 Condition C and is projected to exceed the Completion Time of Condition A, TS 3.3.3 Conditions Band F (ofTS 3.3.3) require submittal of a report in accordance with TS 5.6.8, "PAM Report."

No new commitments are identified in this correspondence. None of the material in this report is considered proprietary by Union Electric.

If you have any questions or require additional information, please contact Mr. Thomas Elwood, Supervising Engineer, Regulatory Affairs and Licensing at 314-225-1905.

Sincerely, tf/a /1/-k )/

D. Matt Hall Director, Nuclear Operations CSP Enclosure

• • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • PO Box 620 Fulton, MO 65251 AmerenMissouri.com **************

STARS

• Alliance

ULNRC-06142 September 16, 2014 Page 2 cc: Mr. Marc L. Dapas Regional Administrator U.S. Nuclear Regulatory Commission Region IV 1600 East Lamar Boulevard Arlington, TX 76011-4511 Senior Resident Inspector Callaway Resident Office U.S. Nuclear Regulatory Commission 8201 NRC Road Steedman, MO 65077 Mr. Fred Lyon Project Manager, Callaway Plant Office ofNuclear Reactor Regulation U.S. Nuclear Regulatory Commission Mail Stop 0-8B 1 Washington, DC 20555-2738

ULNRC-06142 September 16, 2014 Page 3 Index and send hardcopy to QA File A160.0761 Hardcopy:

Certrec Corporation 4150 International Plaza Suite 820 Fort Worth, TX 76109 (Certrec receives ALL attachments as long as they are non-safeguards and may be publicly disclosed.)

Electronic distribution for the following can be made via Responses and Reports ULNRC Distribution:

F. M. Diya D. W. Neterer L. H. Graessle B. L. Cox S. A. Maglio T. B. Elwood Corporate Communications NSRB Secretary STARS Regulatory Affairs Mr. John O'Neill (Pillsbury Winthrop Shaw Pittman LLP)

Enclosure to ULNRC-06142 Page 1 of2 Special Report 2014-02 PAM Report Requirement Callaway Plant Unit 1 Technical Specification (TS) 3.3.3, "Post Accident Monitoring (PAM)

Instrumentation," contains requirements for the Reactor Vessel Level Indicating System (RVLIS) instrumentation. TS 3.3.3 Limiting Condition For Operation (LCO) requires two channels ofRVLIS instrumentation to be Operable while in MODES 1, 2, and 3. With one of the required RVLIS instruments inoperable for more than 30 days, Required Action B.1 specifies, "Initiate action in accordance with Specification 5.6.8." With two of the required RVLIS instruments inoperable for more than 7 days, Required Action F.l also specifies, "Initiate action in accordance with Specification 5.6.8."

TS 5.6.8, "PAM Report," states, "When a report is required by Condition B or F ofLCO 3.3.3, 'Post Accident Monitoring (PAM) Instrumentation,' a report shall be submitted within the following 14 days.

The report shall outline the preplanned alternate method of monitoring, the cause of the inoperability, and the plans and schedule for restoring the instrumentation channels of the Function to OPERABLE status."

Background:

The Reactor Vessel Level Indicating System (RVLIS) provides an indication of reactor vessel level from the bottom of the reactor vessel to the top of the reactor under natural (narrow range) and forced (wide range) circulation conditions. In addition to the two differential pressure transmitters that support this function, resistance temperature detectors (RTDs) are provided on the sensing lines to these transmitters to allow for density compensation of the fluid within the sensing lines. This system solely supports the Post Accident Monitoring functions required by Technical Specification 3.3.3 Function 5.

Summary of the PAM Instrument Inoperability On August 7, 2014, B Train RVLIS was declared inoperable due to intermittent spiking within the narrow range (static) level indication. This loop was restored to service on August 18, 2014 following replacement of the power supply card for this instrument loop.

On August 19, 2014, A Train RVLIS was declared inoperable due to a failed RTD input to the narrow range (static) and wide range (dynamic) level indications. From a review of the plant computer archives, evidence exists that this input had been experiencing performance concerns back to July 3, 2014.

On August 26, 2014, B Train RVLIS was again declared inoperable due to intermittent spiking within the narrow range level indication. Additional reviews of the plant computer archives determined that intermittent spiking concerns in this instrument loop appear to have been present dating back to April 2014.

The above was previously reported in accordance with Technical Specification 3.3.3 Conditions Band F since firm evidence of these operational concerns existed prior to the date of discovery. (Refer to Callaway Special Report 2014-01 submitted under Ameren letter ULNRC-06139 dated September 2, 2014.)

Enclosure to ULNRC-06142 Page 2 of2 On September 2, 2014, the seven-day Completion Time of Technical Specification 3.3.3 Condition C was exceeded when neither RVLIS train was returned to service following entry into this condition on August 26,2014.

On September 10,2014, A Train RVLIS was returned to service following the rework of an electrical splice in the affected RTD circuit. However, this loop was declared inoperable on September 11, 2014, following a recurrence of the operational concerns with this RTD.

Neither of these trains will be returned to service prior to September 18, 2014. As a result, this report also addresses the following:

1. Exceeding the 30-day Completion Time for Technical Specification 3.3.3 Condition A since both trains of RVLIS will not be restored prior to this date, and

2. Exceeding the 7-day Completion Time for Technical Specification 3.3.3 Condition C since neither of the RVLIS trains will be restored prior to this date.

Preplanned Alternate Method of Monitoring An alternate means of monitoring, as described in TS Bases 3.3.3 Required Action F.1, is monitoring the core exit thermocouples, pressurizer level indication, and Reactor Coolant System subcooling monitor indication. These three parameters provide diverse information for verifying adequate core cooling.

Cause of the Inoperability As noted above, the reported concerns within both RVLIS trains have been intermittent in nature.

The first attempt to restore the B Train RVLIS cabinet on August 18, 2014 was based upon addressing one of the two potential causes that could contribute to intermittent spiking within the loop (loop power supply card). Following recurrence of this concern on August 26, 2014, temporary recording equipment was capable of capturing a subsequent transient within this loop. The data revealed the corresponding level transmitter as the source of the concern.

The first attempt to restore the A Train RVLIS cabinet on September 10, 2014 was based upon reworking an inner containment penetration splice. This rework was pursued due to a correlation that was observed between the failed A Train RVLIS RTD and variations in containment temperatures. This rework activity did reveal a loose termination within a spliced connection, which provided reasonable assurance that the source of this concern had been identified. Following recurrence of this concern on September 11, 2014, additional troubleshooting was performed while the loop was failed which revealed the RTD or its corresponding leads as the source of this concern.

Plans and Schedule for Restoring the Instrumentation Channel to OPERABLE status Replacement of the A Train R TD and its corresponding leads will be pursued during the upcoming fall 2014 refueling outage (currently scheduled to begin on October 11, 2014).

The potential for performing an online replacement of the B Train transmitter is currently under evaluation. Replacement of this transmitter will be pursued no later than the forthcoming fall2014 refueling outage.