05000458/LER-1917-006, Re Potential Loss of Safety Function of Onsite Power Sources Due to Inoperability of Control Building Chiller

Re Potential Loss of Safety Function of Onsite Power Sources Due to Inoperability of Control Building Chiller

ML17200C938
Person / Time
Site:	River Bend
Issue date:	07/13/2017
From:	Maguire W Entergy Operations
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
RBF1-17-0082, RBG-47772 LER 17-006-00
Download: ML17200C938 (5)

LER-1917-006, Re Potential Loss of Safety Function of Onsite Power Sources Due to Inoperability of Control Building Chiller

Event date:
Report date:
Reporting criterion:	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)(ix)(A) 10 CFR 50.73(a)(2)(iv)(A), System Actuation 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)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(i)
4581917006R00 - NRC Website

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RBG-47772 July 13, 2017 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555

Subject:

RBF1-17-0082 Licensee Event Report 50-458 I 2017-006-00 River Bend Station - Unit 1 Docket No. 50-458 License No. NPF-47

Dear Sir or Madam:

Entergy Operations, Inc.

River Bend Station 5485 U.S. Highway 61 N St. Francisville, LA 70775 Tel 225-381-4157 William F. Maguire Site Vice President In accordance with 1 o CFR 50. 73, enclosed is the subject Licensee Event Report. This document contains no commitments. If you have any questions, please contact Mr.. Tim Schenk at 225-381-4177.

Sincerely, WFM/dhw Enclosure cc:

U. S. Nuclear Regulatory Commission Region IV 1600 East Lamar Blvd.

Arlington, TX 76011-4511 NRC Sr. Resident Inspector P. 0. Box 1050 St. Francisville, LA 70775 INPO (via ICES reporting)

Licensee Event Report 50-458 I 2017-006-00 July 13, 2017 RBG-47772 Page 2 of 2 Central Records Clerk Public Utility Commission of Texas 1701 N. Congress Ave.

Austin, TX 78711-3326 Department of Environmental Quality Office of Environmental Compliance Radiological Emergency Planning and Response Section Ji Young Wiley P.O. Box 4312 Baton Rouge, LA 70821-4312 J

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NRCFORM366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 I

EXPIRES: 03/31/2020 (04-2017)

I

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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 />.

LICENSEE EVENT REPORT (LEA)

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

F Send comments regarding burden estimate to the Information Services Branch (T-2 F43), U.S.

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(See Page 2 for required number of digits/characters for each block)

Nuclear Regulatory Commission, Washington, DC 20555-0001, or by e-mail to lnfocollects.

Resource@nrc.gov, and to the Desk Officer, Office of Information and Regulatory Affairs, I

NEOB-10202, (3150-0104), Office of Management and Budget, Washington, DC 20503. If a means (See NUREG-1022, R.3 for instruction and guidance for completing this form used to impose an information collection does not display a currently valid OMS control number, htm://www.nrc.gov/reading-rm/doc-ggllections/nuregs/staff/sr1022/r3D the NRG may not conduct or sponsor, and a person is not requirSd to respond to, the information collection.

1

1. FACILITY NAME

~. DOCKET NUMBER

3. PAGJ:

River Bend Station - Unit 1 05000-458 1 OF3

4. TITLE Potential Loss of Safetv Function of Onsite Power Sources due to Inadvertent lnooerabilitv of Control Buildina Chiller

5. EVENT DATE

6. LER NUMBER

7. REPORT DATE

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

I 05000 I

FACILITY NAME DOCKET NUMBER 05 15 ~ 2017 2017 006 00 07 13 2017 I

I 05000

9. OPERATING MODE

11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply) 1 D 20.2201 (bl D 20.22os(a)(3)(i)

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

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

D 20.2201 (d)

D 20.22os(a)(3)(ii)

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

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

D 20.22os(a)(1)

D 20.22os(a)(4)

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

.0 50.73(a)(2)(ix)(A)

D 20.22os(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 20.22os(a)(2)(ii)

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

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

D 1:p1(a)(4)

D 20.22os(a)(2)(iii)

D so.36(c)(2)

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

D 1:3.11(a)(S) 100 D 20.2203(a)(2)(iv)

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

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

D 73.77(a)(1)

D 20.2203(a)(2)(v)

D 50.73(a)(2)(i)(A) 181 50.73(a)(2)(v)(D)

D 73.77(a)(2)(i)

D 20.2203(a)(2)(vi)

D 50.73(a)(2)(i)(B) 0 50~73(a)(2)(vii)

D 73.77(a)(2)(ii)

D 50.73(a)(2)(i)(C) 00THER Specify in Abstract below or in NRC,Form 366A

12. LICENSEE CONTACT FOR THIS LER LICENSEE CONTACT IELEPHONE NUMBER.(/nc/ude Area Code) h"im Schenk, Manaoer - Reoulatorv Assurance

~25-381-4177 CAUSE SYSTEM COMPONENT MANU-REPORTABLE

CAUSE

SYSTEM COMPONENT MANU-REPORTABLE FACTURER TOEPIX FACTURER TO'EPIX none

14. SUPPLEMENTAL REPORT EXPECTED

15. EXPECTED MONTH DAY YEAR 0 YES (If yes, complete 15. EXPECTED SUBMISSION DATE) 181 NO SUBMISSION DATE ABSTRACT (limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)

On May 15, 2017, an engineering investigation determined that a modification installed in 2014 on two of the four safety-related main control building chillers had a design error. The nature of that error was such that the performance of a regularly scheduled preventative maintenance (PM) task to draw an oil sample from'the chiller gearbox inadvertently caused the chiller to be incapable of responding to an automatic start signal. A review of the. history of the PM found that, on three occasions since the modification was installed, the task was performed on the operable chiller that was in the standby condition. The inadvertent inoperability of the standby division of the main control building chillers causes the loss of safety function of the supported electrical distribution systems in the building. The control building chilled water system provides cooling to the equipment rooms housing the battery chargers and inverters for the safety-related onsite electrical distribution systems. The loss of cooling to the various equipmeht rooms in the control building requires that the supported equipment in those areas be declared inoperable. The Technical Sp~cifications for the I

Division 3 DC distribution system requires that the high pressure core spray (HPCS) system be immediately declare.d inoperable. This condition potentially causes the HPCS system to be incapable of performing its safety function, and is, thus, reportable in accordance with 10 CFR 50.73(a)(2)(v)(D). The error in the subject modification is considered a legacy issue since its design was completed and approved in July 2012. The PM task will be revised to preclude its performance on chillers in the standby configuration. At no time during the three performances of the PM on the operable standby chiller was there an actual demand for its automatic start. This condition was, thus, of minimal significance with respect to the health and safety of the public.

I NRC FORM 366 {04-2017)

REPORTED CONDITION

SEQUENTIAL NUMBER 006 REV NO.

00 On May 15, 2017, an engineering investigation determined that a modification installed in 2014 on two of the four safety-related main control building chillers (**CHU**) had a design error. The nature of that error was such that the performance of a regularly scheduled preventative maintenance (PM) task to draw an oil sample from the chiller gearbox inadvertently caused the chiller to be incapable of responding to an automatic start signal. A review of the history of the PM found that, on three occasions since the modification was installed, the task was performed on the operable chiller that was in the standby condition. The inadvertent inoperability of the standby division of the main control building chillers causes the loss of safety function of the supported electrical distribution systems in the building.

The control building chilled water system [VI] provides cooling to the equipment rooms housing the battery chargers and inverters for the safety-related onsite electrical distribution systems. The loss of cooling to the various equipment rooms in the control building requires that the supported equipment in those areas be declared inoperable. The Technical Specifications for the Division 3 DC distribution system requires that the high pressure core spray (HPCS) system be immediately declared inop~able. This condition potentially causes the HPCS system to be incapable of performing its safety function, and is, thus, reportable in accordance with 10 CFR 50.73(a)(2)(v)(D).

INVESTIGATION The subject modification was installed on the Division 1 "C" chiller in August 2014, and on the Division 2 "D" chiller in April 2014. (Each division has a redundant chiller that has yet to be modified.) The purpose of the modification was to upgrade the chiller controls to a digital system. An error occurred in the development of the modification design that involved the controls for the motor-driven chiller oil pump. The switch for the oil pump is on the main control room panel, and is normally in the "AUTOMATIC" position. The work instructions in the PM require that the control switch be placed in the "RUN" position to start the pump. The effect of the design error is that the automatic start feature of the chiller is disabled when the switch is in the "RUN" position.

The review of the PM history found that the "C" chiller was sampled on February 2nd and August 3rd in 2015. The "D" chiller was sampled on March 21, 2017. In each case, the subject chiller was operable and configured for an automatic start should the operating chiller in the opposite division unexpec,tedly trip. The execution of the PM step to place the oil pump control switch in "RUN" rendered the chiller inoperable.

IMMEDIATE CORRECTIVE ACTIONS

When this condition was discovered, the oil pump control switches on the "C" and "D" chillers were "CAUTION" tagged to prohibit taking the switch to the "RUN" positio~ if the chiller is in the standby configuration.

CORRECTIVE ACTIONS TO PREVENT RECURRENCE The error in the subject modification is considered a legacy issue since its design was completed and approved in July 2012. Since that time, a comprehensive root cause analysis on the issue of quality in engineering products was conducted in 2015, which resulted in numerous programmatic changes. Therefore, no new causal analysis was Page 2 of 3 (04-2017)

U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 3/31/2020 LICENSEE EVENT REPORT (LEA)

CONTINUATION SHEET (See NUREG-1022, R.3 for instruction and guidance for completing this form http://www.nrc.gov/reading-rm/doc-collections/nureqs/staff/sr1022/r3/)

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 Information Services Branch {T-2 F43), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by 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 OMS control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.

3. LER NUMBER YEAR River Bend Station - Unit 1 05000-458 2017 performed for this event.

SEQUENTIAL NUMBER 006 REV NO.

00 rrhe PM task will be revised to preclude its performance on chillers in the standby configuration. This action is being

~racked in the corrective action program.

PREVIOUS OCCURRENCE EVALUATION River Bend Station has reported no similar events in the last three years.

SAFETY SIGNIFICANCE

~t no time during the three performances of the PM on the operable standby chiller was there an actual demand for its automatic start. This condition was, thus, of minimal significance with respect to the health and safety of the public.

(NOTE: Energy Industry Identification System component function identifier and system name of each component or system referred to in the LER are annotated as (**XX**) and [XX], resp'ectively.) Page 3 of 3