05000458/LER-2018-001, Potential Loss of Safety Function of Control Building HVAC Due to Legacy Design Flaw

Potential Loss of Safety Function of Control Building HVAC Due to Legacy Design Flaw

ML18164A214
Person / Time
Site:	River Bend
Issue date:	06/07/2018
From:	Maguire W Entergy Operations
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
RBG-47871 LER 2018-001-00
Download: ML18164A214 (5)

LER-2018-001, Potential Loss of Safety Function of Control Building HVAC Due to Legacy Design Flaw

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2) 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
4582018001R00 - NRC Website

text

Entergy.

RBG-47871 June 7, 2018 Attn: Document Control Desk U.S. Nuclear Regulatory Commission 11555 Rockville Pike Rockville, MD 20852-2738

Subject:

Dear Sir or Madam:

Licensee Event Report 50-458/2018-001-00 River Bend Station, Unit 1 Docket No. 50-458 License No. NPF-47 Entergy Operations, Inc.

River Bend Station 5485 U.S Highway 61N St. Francisville. LA 70775 Tel 225*381*4374 William F. Maguire Site Vice President In accordance with 10 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/twf Enclosure cc:

(with Enclosure)

U.S. Nuclear Regulatory Commission Attn: Ms. Lisa M. Regner, Project Manager 09-D-14 One White Flint North 11555 Rockville Pike Rockville, MD 20852 U.S. Nuclear Regulatory Commission Region IV 1600 East Lamar Blvd.

Arlington, TX 76011-4511

RBG-47871 Page 2 of 2 NRC Senior Resident Inspector Attn: Mr. Jeff Sowa 5485 U.S. Highway 61, Suite 1 St. Francisville, LA 70775 Public Utility Commission of Texas Attn: PUC Filing Clerk 1701 N. Congress Avenue P. O. Box 13326 Austin, TX 78711-3326 INPO (via ICES reporting)

RBF1-18-0108

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150~1 04 EXPIRES: 03/31/2020 (04-2018)

Estimated burden per response 10 comply with this mandalory collection request 80 hours9.259259e-4 days <br />0.0222 hours <br />1.322751e-4 weeks <br />3.044e-5 months <br />.

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LICENSEE EVENT REPORT (LER)

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

[f-2 F43}, u.S. Nudear Regulatory Comml.sion, WashinglDn, DC 20555-0001, or by e-mail

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10 Inlocolects.Resource@nrc.gov, and to the Desk OfBcer, OIIIce 01 Informatlor1 and 0

Regulatory Affairs, NEOS-l0202, (31S()'()104), Office of Managoment and Budge~

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person Is not required to respond 10, thelnformaton ooIection.

3. Page River Bend Station -

Unit 1 458 3

05000 1

OF

4. Title Potential Loss of Safety Function of Control Building HVAC due to Legacy Design Flaw

5. Event Date

6. LER Number

7. Report Date

8. Other Facilities Involved Day

Yea, Yea, I Sequential I Rev Month Facility Name Docket Number Month

Numbe, No.

Day Year NA 05000 Facility Name Docket Numbe' 04 10 2018 2018 -

001 -

00 06 07 18 NA 05000

9. Operating Mode

11. This Report Is Submitted Pursuant to the Requirements of 10 CFR §: (Check all that apply) 0 20.2201 (b) 0 20.2203(a)(3)(I) 0 50.73(a)(2)(II)(A) 0 50.73(a)(2)(vlll)(A) 0 20.2201 (d) 0 20.2203(a)(3)(II) 0 50.73(a)(2)(II)(B) 0 50.73(a)(2)(vlll)(B) 1 0

0 0

0 20.2203(a)(1 )

20.2203(a)(4) 50.73(a)(2)(III) 50.73(a)(2)(lx)(A) 0 20.2203(a)(2)(1) 0 50.36(c)(1 )(I)(A) 0 50.73(a)(2)(lv)(A) 0 50.73(a)(2)(x)

10. Power Level 0 20.2203(a)(2)(1I) 0 50.36(c)(1 )(II)(A) 0 50.73(a)(2)(v)(A) 0 73.71(a)(4) 0 20.2203(a)(2)(III) 0 50.36(c)(2) 0 50.73(a)(2)(v)(B) 0 73.71(a)(5) 0 20.2203(a)(2)(iv) 0 50.46(a)(3)(II) 0 50.73(a)(2)(v)(C) 0 73.77(a)(1 )

100 0 20.2203(a)(2)(v) 0 50.73(a)(2)(I)(A) 0 50.73(a)(2)(v)(O) 0 73.77(a)(2)(I) 0 20.2203(a)(2)(vl) 0 50.73(a)(2)(I)(B) 0 50.73(a)(2)(vll) 0 73.77(a)(2)(1I) 0 50.73(a)(2)(I)(C) 0 Other (Specify in Abstract below or in CAUSAL ANALYSIS The control logic problem was traced to a latent deficiency in a 1987 modification, which rerated the chillers from 50%

capacity to 100% capacity each, based on actual building loads being lower than those originally calculated. Accordingly, it would not be necessary for both chillers in either Division to be operable for the Division to be considered operable.

The modification established a level of redundancy that was not previously creditable. To do this, a redesign of the control logic for the multi-unit system was required, setting up a relationship between (pre-selected) lead and standby units, while still assuring the correct restart of the system following a LOP.

The 1987 modification inadvertently created the logic issue identified in this event.

The 1987 modification represents a legacy human performance related event. Further investigation into the 1987 modification is not possible, due to the passage of time and unavailability of personnel involved.

CORRECTIVE ACTION TO PREVENT RECURRENCE Compensatory measures have been incorporated into procedures that direct operators to secure the Division I HVK Chilled Water Pump if both the Division I and Division II HVK Chilled Water Pumps are found running following a LOP.

~n extent of condition was performed on all River Bend Station ventilation systems. No other occurrence of this design flaw was identified_

'A permanent modification will be performed to eliminate the HVK control logic error and is being tracked by the Corrective iA-ction Program.

PREVIOUS OCCURRENCE EVALUATION No similar events have been reported by River Bend Station in the last three years.

SAFETY SIGNIFICANCE

In the unlikely event of a LOP coincident with a failure of the Division II HVK time delay relays, control room operators would have responded to the event with established procedures for a loss of Control Building Ventilation to restore the safety

~unction _ Operators would have responded similarly in the event of a LOP with Division I HVK running and Division II in standby_ Thus, this event was of minimal significance 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 [XXl, respectively.) Page 3

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