05000482/LER-2018-002, Modification Activities Affected Control Room Envelope Boundary Causing a Condition Prohibited by Technical Specifications

Modification Activities Affected Control Room Envelope Boundary Causing a Condition Prohibited by Technical Specifications

ML19065A049
Person / Time
Site:	Wolf Creek
Issue date:	02/27/2019
From:	Bayer R Wolf Creek
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
WO 19-0001 LER 2018-002-00
Download: ML19065A049 (6)

LER-2018-002, Modification Activities Affected Control Room Envelope Boundary Causing a Condition Prohibited by Technical Specifications

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)(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)(iii) 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)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(1), Submit an LER, Invalid Actuation
4822018002R00 - NRC Website

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Robert J. Bayer Plant Manager U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555 February 27, 2019 WO 19-0001

Subject:

Docket No. 50-482:

Licensee Event Report 2018-002-00, "Modification Activities Affected Control Room Envelope Boundary Causing a Condition Prohibited by Technical Specifications" To Whom It May Concern:

The enclosed Licensee Event Report (LER) 2018-002-00 is being submitted pursuant to 10 CFR 50.73(a)(2)(i)(B) as an operation or condition prohibited by Technical Specifications.

This letter contains no commitments. If you have any questions concerning this matter, please contact me at (620) 364-4015, or Ron Benham at (620) 364-4204.

RJB/rlt Enclosure cc:

S. A. Morris (NRG), w/e B. K. Singal (NRG), w/e N. H. Taylor (NRG), w/e Senior Resident Inspector (NRG), w/e Sincerely, Robert J. Bayer P.O. Box 411 / Burlington, KS 66839 / Phone: (620) 364-8831 An Equal Opportunity Employer M/F/HCNET

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3150-0104 EXPIRES: 03/31/2020 (04-2018)

, the NRG may not conduct or sponsor, and a

it**""'...

person is not required to respond to, the information collection.

3.Page Wolf Creek Generating Station 05000 482 1

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4. Title Modification Activities Affected Control Room Envelope Boundary Causing a Condition Prohibited by Technical Specifications

5. Event Date

6. LER Number

7. Report Date

8. Other Facilities Involved Year Year I Sequential I Rev Facility Name Docket Number Month Day Number No.

Month Day Year 05000 Facility Name Docket Number 02 19 2018 2018 -

002 -

00 02 27 2019 05000

9. Operating Mode

11. This Report is Submitted Pursuant to the Requirements of 10 CFR §: (Check all that apply)

D 20.2201(b)

D 20.2203(a)(3)(i)

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

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

D 20.2201(d)

D 20.2203(a)(3)(ii)

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

D 50.73(a)(2)(viii)(B) 1 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)(1)(i)(A)

D 50.73(a)(2)(iv)(A)

D 50.73(a)(2)(x)

10. Power Level 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)

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)

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

D 73.77(a)(1) 100 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)

[Z] 50.73(a)(2)(i)(B)

D 50.73(a)(2)(vii)

D 73.77(a)(2)(ii)

. ' :, ')},t:t

<,, D 50.73(a)(2)(i)(C)

D Other (Specify in Abstract below or in Mitigating actions were immediately initiated. These included verifying self-contained breathing apparatus (SCBA) equipment is readily available and that all personnel required to be in the CRE are qualified and trained in their use.

The availability of SCBA equipment would mitigate the internal exposure concern and provide protection from smoke or chemical inhalation. Whole body and beta skin doses have such large margins, that even with the reduced pressure provided by the 'B' train of CREVS, no further mitigating actions were required as later verified.

Later on March 5, 2018, STS PE-004 was performed again. During the initial test, essentially no control was maintained over ingress and egress through the various Control Building doors. During the second test, there was better control over Control Building doors. The pressure readings were more consistent, but still fell below the acceptance criteria.

On March 6, 2018, at 1308 CST, Required Action B.2 was completed when the mitigating actions were verified such that CRE occupant radiological exposure will not exceed regulatory limits, and that CRE occupants are protected from chemical and smoke hazards. On this same day, as part of troubleshooting for the failed surveillance test, walkdowns were performed of the various boundaries of the Control Building. During these activities it was identified that a plant modification was in progress which created penetrations in the floor of the 2032' elevation of the Control Building down into the rooms of the 2016' elevation directly below. During development of this modification, design documents were reviewed to determine if the implementation of this modification would create a breach in either the CRE or CBE. Since the penetrations were completely contained within the CBE, and were not within the CRE at all, it was thought that the interim configuration of the modification would not impact the CRE pressures. The penetrations were initially created on September 17, 2017. Breach permits were created at this time which required continuous fire watch, along with compensatory measures for fire and flood protection to be installed at the end of every dayshift. On February 19, 2018, fire dampers were installed into these penetrations. At this point, the compensatory measures were no longer required for fire or flood protection. However, the dampers did not restrict the flow of air between levels in the Control Building.

On the evening of March 6, 2018, the ductwork for the modification was finished which sealed off the penetrations and an informational CRE pressure test was run. These results indicated the CRE was maintaining the required pressure. Since the modification activities were not yet complete, it was agreed to wait until these were completed before formally running the surveillance to allow exit from TS LCO 3. 7.10 Condition B.

After final completion of the modification activities, on March 12, 2018, the test was performed with the intent of declaring the 'B' train of CREVS operable and exiting TS LCO 3.7.10 Condition B. However, this test was not successful. Further troubleshooting was performed which resulted in adjustments being made to several Control Building door seals. It was also identified that several test conditions were different than those performed earlier, such as time of day (which likely could result in more ingress and egress through Control Building doors) and the Auxiliary Building ventilation system being in different line-ups ('normal' mode rather than 'emergency exhaust' mode).

STS PE-004 was successfully performed using the 'B' train of CREVS on March 15, 2018. For this test, ingress/egress limitations were expanded to include additional Control Building doors. The pressure readings were well above the acceptance criteria. This test was also conducted for the 'A' train of CREVS. This test performance was also well above the acceptance criteria. Following consolidation of the information regarding testing and troubleshooting, at 1144 Central Daylight Time (CDT), on March 16, 2018, TS LCO 3.7.10 Condition B was exited due to CRE boundary being restored and the 'B' train of CREVS being declared operable.

REPORT ABILITY This event is being reported in accordance with 10 CFR 50.73(a)(2)(i)(B) as an operation or condition prohibited by TS.

The 'B' train of the CREVS was initially declared inoperable for the failure of its surveillance test associated with maintaining required positive pressure in the CRE. There were a number of factors present that all contributed to the inability to maintain CRE pressure. These include the penetrations associated with the modification, adjustments made to several door seals, and inconsistent test conditions such as ingress/egress control and equipment lineups. For most of the possible contributors, there exists no firm evidence regarding how long these conditions existed. However, there is firm evidence that the interim configuration of the modification existed since February 19, 2018. This can be considered to be the date for which the 'B' train of CREVS would be considered inoperable due to the inability to maintain required positive pressure in the CRE.

TS LCO 3.7.10, Condition Bis entered for a CREVS train inoperable due to an inoperable CRE or CBE boundary. Action B.1 states to initiate action to implement mitigating actions with a completion time of immediately. Action B.2 states to verify mitigating actions to ensure CRE occupant radiological exposures will not exceed limits and CRE occupants are protected from chemical and smoke hazards with a completion time of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. LCO 3. 7.10 Condition C requires that if all of the required actions and completion times are not met in Condition B, then the plant must be in Mode 3 within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />, and Mode 5 within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. The identified condition existed for approximately 14 days. Since the completion times of Actions B.1 and B.2 were exceeded, and the plant never shutdoi.:vn in accordance with the required actions of Condition C, the plant was in a condition prohibited by TS.

Inspection Report 2018-003, dated November 7, 2018 (ADAMS accession number ML18311A384), includes a Severity Level IV non-cited violation for failure to submit a Licensee Event Report (LER) due to the CRE being inoperable for longer than the TS allowed outage time. This LER fulfills the requirement of 10 CFR 50.73(a)(1) pertaining to that violation.

CAUSE

There were two probable causes which are considered major contributors:

1) The interim configuration of the modification, combined with an overall reduction in margin as evident by door seal adjustments, was found to affect CRE pressure.

2) The control of conditions present during performance *of STS PE-004, including the system lineup and ingress/egress allowances, does not allow for consistent pressure readings. This made it impossible to tell how much of an impact each of the possible vulnerabilities made to the test failure.

CORRECTIVE ACTIONS

1) The Control Room Habitability Program implementing procedure (AP 23-009) will be revised to identify the specific boundaries (interior and exterior) that make up the CRE and CBE boundaries. WCRE-35 will then be revised to be consistent with AP 23-009.

2) STS PE-004 will be revised to require a consistent method for system alignment and control of ingress/egress during testing in order to obtain consistent and trendable data.

SAFETY SIGNIFICANCE

The safety significance of this event is low. While the 'B' train of CREVS was not able to maintain the 0.25 in w.g.

pressure above the outside air, it was able to maintain a positive pressure, which would continue to mitigate the intrusion of chemical and radiological contaminants into the CRE. Mitigating actions were put into place to ensure that CRE inhabitants were adequately protected from these hazards. In addition, the 'A' train of CREVS was still considered operable due to its higher margin in maintaining positive pressure in the CRE even with the penetrations in the floor of the 2032' elevation of the c*ontrol B1..1ilding present. Finally, there were no radiological releases that would have challenged the regulatory limits for intake for CRE occupants, nor were there any smoke or chemical hazards pres(;}nt during the time the 'B' train was unable to maintain the required level of positive pressure.

OPERATING EXPERIENCE/PREVIOUS EVENTS None. Page 5

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