05000423/LER-2016-003, Regarding Loss of Safety Function-Supplementary Leak Collection and Release System
ML16165A488 | |
Person / Time | |
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Site: | Millstone ![]() |
Issue date: | 06/08/2016 |
From: | Daugherty J Dominion Nuclear Connecticut |
To: | Document Control Desk, Office of Nuclear Reactor Regulation |
References | |
16-207 LER 16-003-00 | |
Download: ML16165A488 (6) | |
Event date: | |
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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)(i) |
LER closed by | |
IR 05000245/2016002 (25 July 2016) | |
4232016003R00 - NRC Website | |
text
Dominion Nuclear Connecticut, Inc *.
Rope Ferry Rd., Waterford, CT 06385 Mailing Address: P.O. Box 128 Waterford, CT 06385 dam.com U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 DOMINION NUCLEAR CONNECTICUT, INC.
MILLSTONE POWER STATION UNIT 3 LICENSEE EVENT REPORT 2016-003-00 JUN 0 8 2016 Serial No.
MPS Lic/AVM Docket No.
License No.16-207 RO 50-423 NPF-49 LOSS OF SAFETY FUNCTION-SUPPLEMENTARY LEAK COLLECTION AND RELEASE SYSTEM This letter forwards Licensee Event Report (LER) 2016-003-00 documenting a condition discovered at Millstone Power Station Unit 3, on April 9, 2016. This LER is being submitted pursuant to 10CFR50.73(a)(2)(v)(C) as a condition that could have prevented the fulfillment of a safety function for systems or structures to control the release of radioactive material, and 10CFR50.73(a)(2)(v)(D) to mitigate the consequences of an accident.
If you have any questions or require additional information, please contact Mr. Thomas G.
Cleary at (860) 444-4377.
Sincerely, John!J..D~
Site Vice President - Millstone Attachments: 1 Commitments made in this letter: None
cc:
U.S. Nuclear Regulatory Commission Region I 2100 Renaissance Blvd.
Suite 100 King of Prussia, PA 19406-2713 R.V. Guzman Serial No.16-207 Docket No. 50-423 Licensee Event Report 2016-003-00 Page 2 of 2 NRC Senior Project Manager Millstone Units 2 and 3 U.S. Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike Mail Stop 08 C-2 Rockville, MD 20852-2738 NRC Senior Resident Inspector Millstone Power Station
ATTACHMENT Serial No.16-207 Docket No. 50-423 Licensee Event Report 2016-003-00 LICENSEE EVENT REPORT 2016-003-00 LOSS OF SAFETY FUNCTION-SUPPLEMENTARY LEAK COLLECTION AND RELEASE SYSTEM MILLSTONE POWER STATION UNIT 3 DOMINION NUCLEAR CONNECTICUT, INC.
RC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2018 (11-2015)
, the NRG may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 3. PAGE Millstone Power Station Unit 3 05000423 1 OF 3
- 4. TITLE Loss of Safety Function-Supplementary Leak Collection and Release System
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORTDATE
- 8. OTHER FACILITIES INVOLVED I
SEQUENTIAL I REV FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR MONTH DAY YEAR NUMBER NO.
05000 04 09 2016 2016 -
003 00 06 08 2016 FACILITY NAME DOCKET NUMBER 05000
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply) n20.2201(b) n 20.2203(a)(3)(i) n 50.73(a)(2)(ii)(A) n 50.73(a)(2)(viii)(A) 1 n20.2201(d) n 20.2203(a)(3)(ii) n 50.73(a)(2)(ii)(B) n 50.73(a)(2)(viii)(B) n20.2203(a)(1) n 20.2203(a)(4) n 50.73(a)(2)(iii) n 50.73(a)(2)(ix)(A) n20.2203(a)(2)(i) n 50.36(c)(1)(i)(A) n 50.73(a)(2)(iv)(A) n 50.73(a)(2)(x)
- 10. POWER LEVEL n20.2203(a)(2)(ii) n 50.36(c)(1)(ii)(A) n 50.73(a)(2)(v)(A) n73.71(a)(4)
D 20.2203(a)(2)(iii) n 50.36(c)(2) n 50.73(a)(2)(v)(B) n73.71(a)(5) 024 n
20.2203(a)(2)(iv) n 50.46(a)(3)(ii) lx150.73(a)(2)(v)(C) o13.11(a)(1) n 20.2203(a)(2)(v) n 50.73(a)(2)(i)(A) lxl 50.73(a)(2)(v)(D) n 73.77(a)(2)(i) n 20.2203(a)(2)(vi) n 50.73(a)(2)(i)(B) n
- 50. 73(a)(2)(vii) n
- 73. 77(a)(2)(ii) n 50.73(a)(2)(i)(C) noTHER Specify in Abstract below or in NRG Form 366A
- 12. LICENSEE CONTACT FOR THIS LER LICENSEE CONTACT TELEPHONE NUMBER (Include Area Code)
Thomas Cleary, Manager Nuclear Station Licensing (860) 444-4377 CAUSE SYSTEM COMPONENT MANU-REPORTABLE I
CAUSE
SYSTEM COMPONENT MANU-REPORTABLE TO EPIX FACTURER TOEPIX FACTURER
- 14. SUPPLEMENTAL REPORT EXPECTED
- 15. EXPECTED MONTH DAY YEAR nYES (/fyes, complete 15. EXPECTED SUBMISSION DATE) fXl NO SUBMISSION DATE ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)
On April 9, 2016, while in MODE 1 and reducing power to enter a scheduled refueling outage (RFO), Millstone Power Station Unit 3 (MPS3} performed the 'B' train Supplementary Leak Collection and Release System (SLCRS) Negative Pressure Verification Surveillance. This test was completed with unsatisfactory results. Technical Specification (TS} Limiting Condition for Operation (LCO) 3.6.6.1 was entered. Later, on April 9, 2016, with the reactor in MODE 1 and approximately 24 percent power, MPS3 operators conducted the 'A' train SLCRS Negative Pressure Verification Surveillance with unsatisfactory results. Because both trains of SLCRS failed the required surveillances, TS LCO 3.6.6.2 was entered. Operations continued with the planned plant shutdown associated with the RFO and entered COLD SHUTDOWN, MODE 5 at 1241 on April 10, 2016.
SLCRS did not meet the acceptance criteria due to the aggregate impact of a number of dampers not providing effective isolation.
SLCRS was restored to operable condition prior to entering MODE 4 when starting back up from RF017. Detailed procedural steps are being developed for verifying the closed position of SLCRS isolation dampers and being incorporated into the damper post maintenance testing matrix. Associated surveillance procedures are being revised to improve monitoring program for SLCRS isolation dampers.
Since both trains of SLCRS failed to meet TS acceptance criteria, this condition is reportable pursuant to 10CFR50.73(a)(2)(v)(C) as a condition that could have prevented the fulfillment of a safety function for systems or structures to control the release of radioactive material and 10CFR50.73(a)(2)(v)(D) to mitiaate the conseauences of an accident. (11-2015)
U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2018
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LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET
- 1. FACILITY NAME
- 2. DOCKET Millstone Power Station Unit 3 05000423
1. EVENT DESCRIPTION
, the NRG may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 6. LER NUMBER I
SEQUENTIAL I NUMBER YEAR 2016 003 REV NO.
00
- 3. PAGE 20F3 On April 9, 2016, while in MODE 1 and reducing power to enter a scheduled refueling outage (RFO),
Millstone Power Station Unit 3 (MPS3) performed the 'B' train Supplementary Leak Collection and Release System (SLCRS) Negative Pressure Verification Surveillance. This test was completed at approximately 1521 hours0.0176 days <br />0.423 hours <br />0.00251 weeks <br />5.787405e-4 months <br /> and did not meet the acceptance criterion of -0.4 inches water gauge._
Technical Specification (TS) Limiting Condition for Operation (LCO) 3.6.6.1 states "With one Supplementary Leak Collection and Release System inoperable, restore the inoperable system to OPERABLE status within 7 days or be in at least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />."
Later, on April 9, 2016, at approximately 2141 hours0.0248 days <br />0.595 hours <br />0.00354 weeks <br />8.146505e-4 months <br /> with the reactor in MODE 1, MPS3 operators conducted the 'A' train SLCRS Negative Pressure Verification Surveillance.and it also did not meet the acceptance criterion of -0.4 inches water gauge. Because both trains of SLCRS failed the required surveillances, TS LCO 3.6.6.2 was entered (SLCRS directly affects the operability of -
Secondary Containment). The LCO states that "Secondary Containment shall be OPERABLE in MODEs 1, 2, 3, and 4, and with Secondary Containment inoperable, restore Secondary Containment 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 be in at least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />." Operations continued with the planned plant shutdown associated with the RFO and entered COLD SHUTDOWN, MODE 5 at 1241 hours0.0144 days <br />0.345 hours <br />0.00205 weeks <br />4.722005e-4 months <br /> on April 10, 2016.
Since both trains of SLCRS failed to meet TS acceptance criteria, this condition is reportable pursuant to *10CFR50.73(a)(2)(v)(C) as a condition that could have prevented the fulfillment of a safety function for systems or structures to control the release of radioactive material, and. _ __
10CFR50.73(a)(2)(v)(D) to mitigate the consequences of an accident.
2. CAUSE
SLCRS did not meet the acceptance criteria of -0.4 inches water gauge due to the aggregate impact of a number of dampers not providing effective isolation.
3. ASSESSMENT OF SAFETY CONSEQUENCES
Although the SLCRS draw down tests did not meet the acceptance criterion of -0.4 inches water gauge, the test results and the consideration of conservatisms in the design basis radiological consequences analyses supp0rt a conclusion of low safety significance.
SLCRS is *designed to mitigate the radiological consequences of postulated accidents by filtering the exhaust air from the Secondary Containment. SLCRS is comprised of two redundant trains of exhaust fans and filter units. The safety function of SLCRS is to maintain a negative pressure in the secondary containment to ensure there is no unaccounted, unfiltered leakage to the outside environment from these areas in the event of a loss of coolant accident. U.S. NUCLEAR REGULATORY COMMISSION APPROVED ~y OMB: NO. 3150-0104 EXPIRES: 10/31/2018 (11-2015)
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- 1. FACILITY NAME
- 2. DOCKET
, the NRG may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 6. LER NUMBER YEAR REV NO.
- 3. PAGE Millstone Power Station Unit 3 05000423 I
SEQUENTIAL I NUMBER 3 OF3 2016 003 00 The SLCRS system and the auxiliary building filtration portion of the auxiliary building ventilation system start on receipt of a Safety Injection Signal. SLCRS is required to draw down the secondary containment to a negative pressure within 120 seconds after the accident.
The negative pressure provided by SLCRS ensures the containment releases occur through the release pathways modeled in the~design basis analysis. As long as negative pressure is maintained in all the buildings associated with SLCRS, then the dose consequences are consistent with the analyzed results, which are within the regulatory limits for control room (5 REM TEDE) and offsite doses (25 REM TEDE).
The test acceptance criterion is based primarily upon developing sufficient negative pressure to counteract a relatively high wind speed. The as-tested values of negative pressure from either of the SLCRS trains would have been sufficient to develop negative pressure for the majority of the wind conditions during Cycle 17 operation.
Additionally, there are other conservatisms iii the design basis.dose calculation relative to expected (i.e., best-estimate) dose consequences. Notably, atmospheric dispersion factors would be significantly less adverse than those used in the design basis dose consequences analysis if the relatively high wind speeds considered in the development of the test acceptance criterion were actually occurring at the site. An additional conservatism is that the containment integrated leak rate testing performed in 2011 showed a leakage rate nearly 1/5th of that assumed in the design basis dose consequences analysis.
4. CORRECTIVE ACTION
Following troubleshooting and maintenance of both SLCRS trains, the surveillance t.est was performed satisfactorily on both trains prior to entering MODE 4 when starting back up from RF017.
Detailed procedural steps are being developed for verifying the closed position of SLCRS isolation dampers following maintenance. The master post maintenance testing matrix for dampers is being updated to refer to these detailed procedural steps. Associated surveillance procedures are being revised to improve monitoring program for SLCRS isolation dampers.
5. PREVIOUS OCCURRENCES
There have been no previous occurrences within the last three (3) years with the same underlying reason or consequences.
- 6. ENERGY INDUSTRY IDENTIFICATION SYSTEM (EllS) CODES:
Damper-DMP Containment Leakage Control-BD