05000346/LER-2019-001, Emergency Ventilation System Train Inoperable Due to Non-specific Test Description of Damper Operation
| ML19282A383 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 10/07/2019 |
| From: | Bezilla M FirstEnergy Nuclear Operating Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| L-19-211 LER 2019-001-00 | |
| Download: ML19282A383 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(ix) 10 CFR 50.73(a)(2)(iv), System Actuation 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)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(i) |
| 3462019001R00 - NRC Website | |
text
FENOC' FirstEnergy Nuclear Operating Company Mark B. Bezi/la Vice President, Nuclear October 7, 2019 L-19-211 ATTN: Document Control Desk United States Nuclear Regulatory Commission Washington, D.C. 20555-0001
Subject:
Davis-Besse Nuclear Power Station, Unit 1 Docket Number 50-346, License Number NPF-3 Licensee Event Report 2019-001 5501 North State Route 2 Oak Harbor. Ohio 43449 419-321-7676 10 CFR 50.73 Enclosed is Licensee Event Report (LER) 2019-001, "Emergency Ventilation System Train Inoperable due to Non-specific Test Description of Damper Operation." This event is being reported pursuant to 10 CFR 50. 73(a)(2)(i)(B).
There are no regulatory commitments contained in this letter or its enclosure. The actions described represent intended or planned actions and are described for information only. If there are any questions or if additional information is required, please contact Mr. James M. Vetter, Manager - Site Regulatory Compliance (Acting), at (419) 321-7393.
Sincerely, tlldY!J GMW Enclosure: LER 2019-001 cc: NRG Region Ill Administrator NRG Resident Inspector NRR Project Manager Utility Radiological Safety Board
NRCFORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3150-0104 EXPIRES: 3/31/2020 (04-2018)
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
3.Page Davis-Besse Nuclear Power Station, Unit 1 05000 346 1 OF 4
- 4. Title:
Emergency Ventilation System Train Inoperable due to Non-specific Test Description of Damper Operation
- 5. Event Date
- 6. LER Number
- 7. Report Date
- 8. Other Facilities Involved I
Sequential I Rev Facility Name Docket Number Month Day Year Year Number No.
Month Day Year 05000 Facility Name Docket Number 06 21 2019 2019 -
001 00 10 07 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) 1 D 20.2201(d)
D 20.2203(a)(3)(ii)
D 50. 73(a)(2)(ii)(B)
D 50. 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)(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) 181 50.73(a)(2)(i)(B)
D 50.73(a)(2)(vii)
D 73.77(a)(2)(ii)
-,oc D
D 50.73(a)(2)(i)(C)
Other (Specify in Abstract below or in
DESCRIPTION OF EVENT
(continued}
Differential Controller PDC5000 [VC-PDC] in automatic mode, resulting in the discharge damper not opening and the recirculation damper opening fully, resulting in no definitive change in pressure with EVS Fan 1 operating.
00 A review of test data was completed on August 6, 2019, for the previous Surveillance Test performed on June 21, 2019. This review determined the previous test showed similar results to the July 19, 2019 test, indicating the dampers were not positioning properly to draw down the annulus area between the Shield Building and the Containment Vessel. Due to the potential for radiation, the ventilation systems in the Auxiliary Building are designed to maintain a negative pressure. Therefore, negative pressure is expected and may exist regardless of whether the Emergency Ventilation System is in operation or not. However, due to the large exhaust airflow rate of approximately 8000 cubic feet per minute (cfm}, the EVS is expected to cause a noticeable decrease in pressure when aligned to exhaust to the station vent stack.
CAUSE OF EVENT
The cause of the EVS recirculation and exhaust dampers not aligning properly to draw down the annulus area was due to a degraded differential pressure controller. The controller experienced a premature failure, having been in operation for only 609 days after the same model controller failed in 2017.
The cause for not identifying the controller failure during the June 21, 2019 monthly Surveillance Test was due to the lack of specific controller and damper response not being described in the Surveillance Test, and the Test acceptance criteria not explicitly describing what "operated properly" meant.
A contributing cause for not meeting the June 21, 2019 monthly Surveillance Test acceptance criteria was due to a knowledge gap within the operations crew. The crew did not recognize that with a sustained draw down pressure of approximately -0.45 inches water gauge differential pressure, the EVS exhaust damper should be full open attempting to further draw down to the desired value_ Information contained in the monthly Surveillance Test procedure about wind affecting indications and door usage was used by the operating crew to determine indications were as expected, when in fact they were not.
ANALYSIS OF EVENT
The DBNPS EVS does not serve any function in preventing core damage. The negative pressure areas created by EVS serve to mitigate releases once core damage has occurred. Thus, there is no increase to Core Damage Frequency (CDF} related to this condition. Also, the DBNPS Probabilistic Risk Analysis (PRA}
does not credit EVS to mitigate releases during an accident. Any releases from Containment are considered to be released directly to the environment. Therefore, there is no increase in the calculated Large Early Release Frequency (LERF} due to the unavailability of one train of EVS. Since there is no increase in CDF or LERF, the risk associated with the inoperable EVS train is considered to be very low safety significance.
Reportability Discussion:
YEAR 2019 SEQUENTIAL NUMBER 001 REV NO.
00 In accordance with the guidance in NUREG-1022, there is no firm evidence the degraded differential pressure controller existed prior to discovery during the monthly Surveillance Test on June 21, 2019_ Based upon the review of the previous surveillance test information on August 6, 2019, EVS Train 1 was considered not capable of performing its required TS function from the performance of the monthly Surveillance Test on June 21, 2019, until the pressure controller was replaced on July 21, 2019. This 30-day period is in excess of the 7-day plus 36-hour shutdown time described in TS LCO 3.7.12_ Therefore, this issue represents operation or condition which was prohibited by the plant's Technical Specification, which is reportable as a Licensee Event Report per 10 CFR 50. 73(a)(2)(i)(B). This report is being submitted within 60 days of the discovery of the reportable condition on August 6, 2019_ Because EVS Train 2 remained operable per LCO 3_7_12 during the time period in question and only EVS Train 1 was affected by this issue, no loss of safety function occurred.
CORRECTIVE ACTIONS
Completed Actions:
On July 21, 2019, after replacement of Containment Annulus Pressure Differential Controller PDC5000 and successful Surveillance Testing, EVS Train 1 was declared Operable at 0135 hours0.00156 days <br />0.0375 hours <br />2.232143e-4 weeks <br />5.13675e-5 months <br />.
The EVS monthly Surveillance Tests have been revised to clarify the intent of the Notes specific to expected/required damper positions and for clarification of the test acceptance criteria requirements.
Scheduled Actions:
- The 2017 and 2019 failed differential pressure controllers will be shipped to the Original Equipment Manufacturer (OEM) for failure analysis.
PREVIOUS SIMILAR EVENTS
There have been no Licensee Event Report (LERs) in the past 3 years at the DBNPS involving the EVS_ Page4 of 4