05000416/LER-2018-002, Both 208 Containment Air Lock Doors Simultaneously Inoperable

Both 208 Containment Air Lock Doors Simultaneously Inoperable

ML18094A172
Person / Time
Site:	Grand Gulf
Issue date:	04/04/2018
From:	Emily Larson Entergy Operations
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
GNRO-2018/00014 LER 2018-002-00
Download: ML18094A172 (8)

LER-2018-002, Both 208 Containment Air Lock Doors Simultaneously Inoperable

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 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), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(i)
4162018002R00 - NRC Website

text

• ~Entergy GNR0-2018/00014 April 4, 2018 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Entergy Oper~tions, Inc.

P. 0. Box756 Port Gibson, MS 39150 Eric A. Larson Site Vice President Grand Gulf Nuclear Station Tel. (601) 437-7500 10CFR50.73

SUBJECT:

Licensee Event Report 2018-002-00, Both Containment Air Lock Doors Simultaneously Inoperable

Dear Sir or Madam:

Grand Gulf Nuclear Station, Unit 1 Docket No. 50-416 License No. NPF-29 Attached is Licensee Event Report 2018-002-00, Both Containment Air Lock Doors Simultaneously Inoperable. This report is being submitted in accordance with 10CFR50.73(a)(2)(i)(B) as a condition prohibited by Technical Specifications and 1 OCFR50. 73(a)(2)(v)(C) as a condition that could have prevented fulfillment of a-safety function (i.e., control the release of radioactive material).

This letter contains no new commitments. If you have any questions or require additional information, please contact Douglas Neve at 601-437-2103.

, Sincerely,

~

c;_ -/.----

Eric A. Larson Site Vice President Grand Gulf Nuclear Station EAL/tdf

Attachment:

Licensee Event Report 2018-002-00 cc: see next page

GNRQ.;201"8/00014 Page 2 of 2 U.S. Nuclear Regulatory Commission ATTN: Mr. Siva Ling am Mail Stop OWFN 8 81 Rockville, Mo-2oa52.:273a NRC Senior Resident Inspector Grand Gulf Nuclear Station Port Gibson, MS 39150 U. S. Nuclear Regulatory Commission ATTN: Mr. Kriss Kennedy, NRR/DORL (w/2)

Mail Stop OWFN 8 81 Washington, DC 20555-0001

GNR0-2018/00014 Page tof 1 Attachment Licensee Event Report (LER) 2018-002-00

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 03/31/2020 (04-2017)

, the NRC may not conduct or

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form sponsor, and a person is not required to respond to, the information collection.

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~o http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1022/r3/)

13.PAGE Grand Gulf Nuclear Station, Unit 1 05000 416 1 OF4

4. TITLE BOTH 208 CONTAINMENT AIR LOCK DOORS SIMULTANEOUSLY INOPERABLE

5. EVENT DATE

6. LER NUMBER

7. REPORT DATE

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

MONTH DAY YEAR NIA 05000 N/A 2

10 18 2018-002-00 4

4 FACILITY NAME DOCKET NUMBER 2018 NIA 05000 N/A

11. THIS REPORT IS SUBMITTED PURSUANT TO lliE REQUIREMENTS OF 10 CFR §: (Check all that apply)

9. OPERATING MODE D 20.2201 (b)

D 20.2203(a)(3)(i+*)

0 50.73(a)(2)(ii)(A)

D 50. 73(a)(2)(viii)(A) 1 D 20.2201(d)

D 20.2203(a)(3)(ii)

D 50. 73(a)(2)(ii)(B)

D q0.73(a)(2)(viii)(B)

D 20.2203(a)(1)

D 20.2203(a)(4)

D 50. 73(a)(2)(iii)

D 50.73(a)(2)(ix)(A)

.D 20.2203(a)(2)(i)

D.50.36(c)(t)(i)(A)

.0.50.73(a)(2)(iv)(A)

.0.50.73(a)(2)(x)

D 20.2203(a)(2)(ii)

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

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

D 73.71(a)(4)

10. POWER LEVEL D 20.2203(a)(2)(iii)

D 50.36(c)(2)

D 50. 73(a)(2)(v)(B)

D 73.71(a)(5)

D 20.2203(a)(2)(iv)

D 50.46(a)(3)(ii) l8150.73(a)(2)(v)(C)

D 73.77(a)(1) 68%

D 20.2203(a)(2)(v)

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

D 50. 73(a)(2)(v)(D)

D 73.77(a)(2)(i)

D 20.2203(a)(2)(vi) 181 50.73(a)(2)(i)(B)

D 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 =

A. PLANT CONDITIONS PRIOR TO THE EVENT At the time of discovery, Grand Gulf Nuclear Station (GGNS) Unit 1 was in Mode 1 at 68% reactor power, and in Technical Specification (TS} 3.6.1.2, "Primary Containment Air Locks," Condition A with the 208 foot upper air lock outer door tagged o_ut for planned maintenance. There were. no other structures,. systems or*

components out of service that contributed to this event.

B. DESCRIPTION

February 6, 2018, GGNS completed the door seal air system leak test, TS Surveillance Requirement (SR) 3.6.1.2.4, on the upper containment air lock inner door [EIIS:NH][AL][DR] and the acceptance criteria were determined to be met. On February 9, 2018, TS 3.6.1.2 Condition A was entered when the.upper containment air lock outer door was taken out of service for maintenance and testing. At 1835 hours0.0212 days <br />0.51 hours <br />0.00303 weeks <br />6.982175e-4 months <br /> central standard time (CST) on February 10, while the outer door was tagged out, an additional review of the paperwork for the inner door determined that the s~rveillance test on the inner door was actually unsatisfactory. Technical Specification 3.6.1.2 Condition C was entered for both doors being inoperable for reasons other than those stated in Conditions A and B.

Technical Specification *3.6.1.2 Action C requires restoration of the air lock to operable status within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or comply with Condition D and be in Mode 3 within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. Maintenance of the outer door was completed, the air lock was returned to operable status, and Condition C was exited at 0835 on February 11, 2018, prior to exceeding the Technical Specification required action completion time of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. The unit remained in TS 3.6.1.2 Condition A while maintenance and testing was performed on the inner door, which was completed on February 18, 2018. Condition A was exited and full operability restored at that time.

When the surveillance test on the inner door was completed on February 6, TS 3.6.1.2 Condition A should have been entered, and the outer door should have been verified closed within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> and locked closed within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. With Condition A required actions not met, Condition D requires the plant be in Mode 3 within the following 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. This requirement was not met and therefore the pla.nt was in a condition prohibited by the Technical Specifications. In addition, from 2045 hours0.0237 days <br />0.568 hours <br />0.00338 weeks <br />7.781225e-4 months <br /> on February 7 until 0835 hours0.00966 days <br />0.232 hours <br />0.00138 weeks <br />3.177175e-4 months <br /> on February 11, while the outer door was out of service, both doors were inoperable concurrently with no redundant equipment in the same system operable, which constitutes a condition that could have prevented

• fulfillment of a safety function.

NRC FORM (4-2017) 366A U.S. NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT (LER)

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/r30

1. FACILITY NAME

2. DOCKET Grand Gulf Nuclear Station, Unit 1 05000 416 APPROVED BY OMB: NO. 3150-0104 EXPIRES: 3/31/2020

, 'the NRG may not conduct or sponsor, and a person is not required to respond to, the information collection.

YEAR I

3. LEA NUMBER SEQUENTIAL NUMBER 2018-002-00 I

REV..

NO.

The containment air lock door seals [EIIS:NH][AL][DR][SEAL] are pneumatic inflatable seals that are maintained at a 70 psig nominal pressure by the seal air flask and pneumatic system, which itself is maintained at a pressure of 90 psig. Each door has two seals to ensure they are single failure proof in maintaining the leak tight boundary of the door. SR 3.6.1.2.4 performs a pressure decay test on the pneumatic system to assure sufficient pressure is maintained for the 30 day mission time of the air lock

• seals.An analysis of the inner door test results compared the seal leakage rate to the functional requirements specified by the vendor. To assure functionality, a minimum differential pressure of 30 psig is required between the seal system and the maximum peak containment pressure of 12.1 psig, or a minimum seal pressure of 42.1 psig (i.e., 56.8 psia). Based on a constant leak rate determined from the results of the surveillance test, the analysis calculated a final seal system pressure after 30 days of 59.2 psia, which is greater than the 56.8 psia required to proyidE:Ul.n.adequate sealing barrier. The analysis is conservative, since (1) pressure loss is expected to slow ~s pressure decays and (2) the post-accident pressure in containment would decay over the duration of the event, and demonstrated that the air lock remained functio~al during the event.

A review determined that the inner door on the primary containment 119 foot lower air lock had failed the same door seal air system leak test (SR 3.6.1.2.4) on April 15, 2015, and on August 11, 2016. A successful.

surveillance test on the inner door was subsequently performed on January 19, 2017.

When the surveillance test on the lower air lock inner door was completed on April 15, 2015, and the acceptance criteria not met, TS 3.6.1.2 Condition A should have been entered, and the outer door should have been verified closed within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> and locked closed within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. With Condition A required actions not met, Condition D requires the plant be in Mode 3 within the following *12 hours. This requirement was not met and therefore th~ plant was in a condition prohibited by the Technical Specifications. During

• the period when the lower air lock inner door was inoperable, the outer door was operable except when taken out of service for preplanned maintenance activities on January 13, 2016, for a total of 63 hours7.291667e-4 days <br />0.0175 hours <br />1.041667e-4 weeks <br />2.39715e-5 months <br />, and again on August 14, 2016, for a total of 39 hours4.513889e-4 days <br />0.0108 hours <br />6.448413e-5 weeks <br />1.48395e-5 months <br />. Conditions during these maintenance activities, with both doors inoperable concurrently with no redundant equipment in the same system operable, constituted a condition that could have prevented fulfillment of a safety function.

Analysis of the inner door test results from 2015 and 2016 again concluded th.e seal system would have maintained functionality for the 30 day post-accident mission time: In both cases, bp.sed on the test results the final calculated pressure after 30 days was in excess of 85 psia, well above the required 59.2 psia.

• These analyses demonstrated that the.lower air lock remained functional during the interval between the failed 2015 test and the successful 2017 test.

C. REPORTABILITY

The events are being reported under 10CFR50.73(a)(2)(i)(B) as a condition prohibited by Technical Specifications and 1 OCFR50.73(a)(2)(v)(C) as a condition that could have prevented fulfillment of a safety function (i.e., control the release of radioactive material). For 50.73(a)(2)(i)(B), Condition D required the plant to be in Mode 3 within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> when ACTION 3.6.1.A was not met, and for 50.73(a)(2)(v)(C) containment was inoperable with both air lock doors in,operable.

NRC FORM (4-2017) 366A U.S. NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT (LER)

CONTINUATION SHEET (See NUREG-1022, R.3 for instruction and guidance for completing this form http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1022/r3L}

1. FACILITY NAME

2. DOCKET Grand Gulf Nuclear Station, Unit 1 05000 416 APPROVED BY OMB: NO. 3150-0104 EXPIRES: 3/31/2020

, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.

YEAR

3. LER NUMBER.

SEQUENTIAL NUMBER 2018-002-00 REV.

NO.

The event was initially reported under 1 OCFR50.72(b)(3)(v)(C) on February 10, 2018, via Event Report 53201.

Entergy has performed an analysis of the event and has determined the airlocks would have been able perform their safety function and therefore in accordance with the guidance provided in NEI 99-02, Revision 7, Regulatory Assessment Performance Indicator Guideline, Section 2.2, Mitigating Systems Cornerstone,*.

Sub-Section, Safety System Functional Failures, Page 30, Lines 27 though 30; this condition will riot be counted as a safety system functional failure against Performance Indicator MS05, Safety System Functional Failures.

D. CAUSE

Test values were not transcribed correctly and test personnel misread the test results. The causes were all related to human performance. The risk analysis for the original test procedure was inadequate in that the risk of not performing an independent or engineering acceptance review was not recognized and included in the procedure. In addition, a technical task risk review was not completed prior to performing the test, as

• required by human performance procedures, which resulted in not fully understanding the risk of the task or level of reviews needed for successful performance.

E. CORRECTIVE ACTIONS

The following actions are completed or planned.

Completed:

An extent of condition evaluation was performed to identify other surveillance test procedures which lack adequate acceptance reviews Planned actions included in the corrective action program which may be changed in accordance with the program:

. :*:.*,.:~*:.. '/)itfi-1~~;,

Procedure 06-ME-1 M23-R~0001_,* Pe'f~cfrmel Air lock Door Seal Air System Leak ~est, will be revised to add a dedicated attachment for the test calculations which will include a preparer and reviewer sign off.

A briefi.ng describing the event will be developed and distributed to engineering supervisors to establish a threshold for the risk review process.

The expectation to utilize human performance tools to preclude risk significant event errors will be reinforced through_ an all hands meeting.

NRC FORM (4-2017) 366A U.S. NUCLEAR REGULATORY COMMISSION*

LICENSEE EVENT REPORT (LER)

CONTINUATION SHEET (See NUREG-1022, R.3 for instruction and guidance for completing this form http://www.nrc.gov/reading-rm/doc-collectio"ns/nuregs/staff/sr1022/r3L)

1. FACILITY NAME

2. DOCKET APPROVED BY OMB: NO. 3150-0104 EXPIRES: 3/31/2020

, the NRG may not conduct or sponsor, and a person is not required to respond to, the information collection.

3. LER NUMBER YEAR Grand Gulf Nuclear Station, Unit 1 05000 416 I

SEQUENTIAL

• NUMBER I

REV.

' NO.

2018-002-00

F. SAFETY SIGNIFICANCE

The seal system pressure for both air locks would have remained above the 56.8 psig required to assure functionality for the entire 30 day mission time. Safety margins are assured by the conservatisms in the analysis; (1) the assumed constant pressure loss in the seals would be expected to slow as pressure decays, and (2) the assumed post-accident pressure iri containment would decay over the duration of the event. As shown by the analysis, there was no safety system functional failure. The inner doors and the air locks remained functional, containment integrity was assured throughout the events, and there was no significant impact on the health and safety of the public..

G. PREVIOUS SIMILAR OCCURRENCES There were no recent similar occurrences.