05000341/LER-2016-017, Regarding Secondary Containment Pressure Exceeded Technical Specification During Reactor Building HVAC Restart Due to High Winds

Regarding Secondary Containment Pressure Exceeded Technical Specification During Reactor Building HVAC Restart Due to High Winds

ML17037D052
Person / Time
Site:	Fermi
Issue date:	02/03/2017
From:	Polson K DTE Electric Company
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NRC-17-0009 LER 16-017-00
Download: ML17037D052 (6)

LER-2016-017, Regarding Secondary Containment Pressure Exceeded Technical Specification During Reactor Building HVAC Restart Due to High Winds

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(v), Loss of Safety Function 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)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(i)
LER closed by
IR 05000341/2017001 (1 May 2017)
3412016017R00 - NRC Website

text

Keith J. Poison Site Vice President DTE Energy Company 6400 N. Dixie Highway, Newport, MI 48166 Tel: 734.586.4849 Fax: 734.586.4172 Email: keith.posoni )dteenertgy.com DTE Energy-10 CFR 50.73 February 3, 2017 NRC-17-0009 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555-0009

Reference:

Fermi 2 NRC Docket No. 50-341 NRC License No. NPF-43

Subject:

Licensee Event Report (LER) No. 2016-017 Pursuant to 10 CFR 50.73(a)(2)(v)(C), DTE Electric Company (DTE) is submitting LER No. 2016-017, Secondary Containment Pressure Exceeded Technical Specification During Reactor Building HVAC Restart Due to High Winds.

No new commitments are being made in this LER.

Should you have any questions or require additional information, please contact Mr. Scott A. Maglio, Manager - Nuclear Licensing, at (734) 586-5076.

Sincerely, Keith J. Polson Site Vice President

Enclosure:

Licensee Event Report No. 2016-017 cc: NRC Project Manager NRC Resident Office Reactor Projects Chief, Branch 5, Region III Regional Administrator, Region III Michigan Public Service Commission Regulated Energy Division (kindschl@michigan.gov)

Enclosure to NRC-17-0009 Fermi 2 NRC Docket No. 50-341 Operating License No. NPF-43 Licensee Event Report (LER) No. 2016-017

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10131/2018 (06-2016)

,f 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 />.

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Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or bye-mail F1 (See Page 2 for required number of digits/characters for each block) to Infocollects.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 (See NUREG-1022, R.3 for instruction and guidance for completing this form means used to impose an information collection does not display a currently valid OMB control http://w nrc.gov/readin-rm/doc-collections/nureas/staff/sr1022/r3/)

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3. PAGE Fermi 2 05000 341 1 OF 4

4. TITLE Secondary Containment Pressure Exceeded Technical Specification During Reactor Building HVAC Restart Due to High Winds

5. EVENT DATE

6. LER NUMBER

7. REPORT DATE

8. OTHER FACILITIES INVOLVED MONTH DAY YEAR YEAR SEQUENTIAL REV MONTH DAY YEAR FACILITY NAME DOCKET NUMBER 7777E 177177O.YA N/A 05000 FACILITY NAME DOCKET NUMBER 12 15 2016 2016 017 00 02 03 2017 N/A 05000

9. OPERATING MODE

11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply) 1 D 20.2201(b) 20.2203(a)(3)(i)

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

E]20.2201(d) 20.2203(a)(3)(ii) 50.73(a)(2)(ii)(B)

E]50.73(a)(2)(viii)(B) 20.2203(a)(1) 20.2203(a)(4) 50.73(a)(2)(iii) 50.73(a)(2)(ix)(A)

E_ 20.2203(a)(2)(i) 50.36(c)(1)(i)(A) 50.73(a)(2)(iv)(A) 50.73(a)(2)(x)

10. POWER LEVEL 20.2203(a)(2)(ii) 50.36(c)(1)(ii)(A)

F 50.73(a)(2)(v)(A)

D 73.71(a)(4) 20.2203(a)(2)(iii) 50.36(c)(2)

E 50.73(a)(2)(v)(B) 73.71(a)(5) 20.2203(a)(2)(iv) 50.46(a)(3)(ii)

/

50.73(a)(2)(v)(C) 73.77(a)(1) 100 20.2203(a)(2)(v) 50.73(a)(2)(i)(A)

E 50.73(a)(2)(v)(D) 73.77(a)(2)(i) 20.2203(a)(2)(vi) 50.73(a)(2)(i)(B)

E]50.73(a)(2)(vii) 73.77(a)(2)(ii) 50.73(a)(2)(i)(C)

OTHER Specify in Abstract below or in If the DBA LOCA for SC concurrent with a Loss of Offsite Power had occurred during the time when the SC pressure TS limit was exceeded, the SC was sufficiently leak tight such that the SGTS would still have established and maintained vacuum greater than the TS required value.

The radiological consequences of the DBA LOCA for SC contained in Chapter 15 of the Fermi 2 UFSAR result in doses that are below 10 CFR 50.67. The SC is assumed to be at 0.0 inches vacuum water gauge at the onset of the LOCA. For this particular event, had the DBA LOCA for SC actually occurred, there would be no increase in magnitude of radiological dose because the highest recorded pressure of 0.044 inches vacuum water gauge is below the assumed SC pressure of 0.0 inches water gauge.

CAUSE OF THE EVENT

The effect of the high winds outside the Reactor Building (RB) ((NG)) combined with the RBHVAC startup caused the momentary loss of SC vacuum.

SGTS typically maintains SC pressure close to 0.4 inches vacuum water gauge with light winds. Due to wind at the time of this event, SC pressure was being sustained at approximately 0.3 inches vacuum water gauge. The RBHVAC exhaust fans ((FAN)) start upon system startup and the supply fans start five seconds later. When the supply fans start, the exhaust pressure control modulating dampers ((CDMP)) take some time to respond to the higher pressure which results in a pressure spike. Because SC pressure was sustained around 0.3 inches vacuum water gauge at the time of RBHVAC startup rather than 0.4 inches vacuum water gauge, the pressure spike resulted in SC pressure exceeding the TS requirement.

The high winds outside the RB are known to cause large and rapid changes in RB differential pressure (i.e., between inside and outside the RB). There are two divisions to monitor SC pressure. Each division has four pressure transmitters

((PT)) located on the RB fifth floor, one on each of the four RB walls, with a pressure probe that penetrates the wall to the outside, and a recorder. The recorder indicates the highest pressure of the four inputs from the transmitters. Using the equation provided in Section 6.2 of the Fermi 2 UFSAR, wind speeds of 30 to 60 miles per hour (mph) on the RB result in an external pressure change of -0.27 to -1.07 inches water gauge on the leeward side of the building. The negative change on the leeward side of the building results in a higher indicated RB pressure. As a result, high wind gusts are sufficient to cause momentary indicated loss of SC vacuum even with no other contributing causes.

CORRECTIVE ACTIONS

No corrective actions were required to restore compliance with TS SR 3.6.4.1.1 as pressure was restored at the time of the event without further Operator action when the RBHVAC startup sequence was completed.

Corrective actions for a similar event were identified in LER 2016-005 including adopting Technical Specification Task Force Traveler (TSTF) 551, "Revise Secondary Containment Surveillance Requirements," when it is approved by the U.S.

Nuclear Regulatory Commission. This TSTF would eliminate the need to declare SC inoperable due to momentary pressure indications exceeding the TS limit, such as those caused by high winds as described in this LER. Another corrective action from LER 2016-005 involved increasing the time delay between the starting the exhaust and supply fans from two to five seconds. Although this modification increased margin to the TS limit for SC vacuum, additional corrective actions related to wind effects were still in progress at the time of this event and, therefore, could not have prevented the event described in this LER.

LERs 2016-003, 2016-004, 2016-007, 2016-008, 2016-010, 2016-013, 2016-014, and 2016-016 all involved the loss of SC vacuum due solely to high winds. As part of the corrective actions in response to these events, an RB pressure recorder modification was completed on December 23, 2016, to prevent momentary SC vacuum indications due to high winds from being received.

PREVIOUS OCCURRENCES

As noted in the Corrective Actions section above, a similar event involving loss of SC vacuum during startup of RBHVAC due to high winds was reported in LER 2016-005. Additionally, LERs 2016-003, 2016-004, 2016-007, 2016-008, 2016-010, 2016-013, 2016-014, and 2016-016 all involved the loss of SC vacuum due solely to high winds. As part of the corrective actions in response to these events, an RB pressure recorder modification was completed on December 23, 2016, after the event in this LER occurred, to prevent momentary SC vacuum indications due to high winds from being received. Therefore, the corrective actions taken in response to these previous events could not have prevented the event described in this LER since they were completed subsequent to this event.

LER 2016-015 documented a similar event on December 14, 2016. Due to the short timeframe between these events, the corrective actions taken in response to this event on December 14, 2016, could not have prevented the event described in this LER.Page 4

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