05000423/LER-2010-003, Secondary Containment Rendered Inoperable Due to Misaligned Dampers
| ML102310506 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 07/26/2010 |
| From: | Jordan A Dominion Nuclear Connecticut |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 10-420, FOIA/PA-2011-0115 LER 10-003-00 | |
| Download: ML102310506 (6) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(i) 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)(v), Loss of Safety Function |
| 4232010003R00 - NRC Website | |
text
,:Dominiown Dominion Nuclear Connecticut, Inc.
Millstone Power Station Rope Ferry Road Waterford, CT 06385
,JUL 2 6 2010 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 Serial No.
NSS&LANVEB Docket No.
License No.10-420 RO 50-423 NPF-49 DOMINION NUCLEAR CONNECTICUT, INC.
MILLSTONE POWER STATION UNIT 3 LICENSEE EVENT REPORT 2010-003-00 This letter forwards Licensee Event Report (LER) 2010-003-00 documenting a condition discovered at Millstone Power Station Unit 3 on May 27, 2010. This LER is being submitted pursuant to 10 CFR 50.73(a)(2)(i)(B), as a -condition prohibited by technical specifications and 10 CfR 50.7a(a)(2)(v)(C) as a condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to control the release of radioactive material.
If you have any questions or require additional information, please contact Mr. William D. Bartron at (860) 444-4301.
Sincerely, Site President - Millstone Attachments: 1 Commitments made in this letter: None.
Serial No.10-420 Docket No. 50-423 LER 2010-003-00 Page 2 of 2 cc:
U.S. Nuclear Regulatory Commission Region I 475 Allendale Road King of Prussia, PA 19406-1415 C. J. Sanders NRC Project Manager U.S. Nuclear Regulatory Commission Mail Stop 08B3 One White Flint North 11555 Rockville Pike Rockville, MD 20852-,2738 NRC Senior Resident Inspector Millstone Power Station
Serial No.10-420 Docket No. 50-423 ATTACHMENT LICENSEE EVENT REPORT 2010-003-00 DOMINION NUCLEAR CONNECTICUT, INC.
MILLSTONE POWER STATION UNIT 3
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 315.0-0104 EXPIRES: 0813112010 (9-2007)
, the NRC may not conduct or sponsor, diits/characters for each block) and a person is not required to respond to, the information collection.
PAE Millstone Power Station - Unit 3 05000423 1 OF3
- 4. TITLE Secondary Containment Rendered Inoperable Due to Misaligned Dampers
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED SEUNILRVFACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR NUMBER N
MONTH DAY YEAR 05000 FACILITY NAME DOCKET NUMBER 05 27 2010 2010-003-00 07 26 2010 05000
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR :.Check all that apply)
- 9. OPERATING MODE 20.2201(b) 20.2203(a)(3)(i) 50.73(a)(2)(i)(C) 5D.73(a)(2)(vii) 20.2201(d) 202203(a)(3)(i) 50.73(a)(2)(ii)(A) 50.73(a)(2)(viii)(A) 20.2203(a)(1) 20.2203(a)(4) 50.73(a)(2)(ii)(B) 50.73(a)(2)(viii)(B)_
-- '-20.2203(a)(2)(i) 50.36(c)(1)(i)(A) 50.73(a)(2)(iii) 50.73(a)(2)(ix)(A) 20.2203(a)(2)(ii) 50.36(c)(1)(i)(A) 50.73(a)(2)(iv)(A) 50.73(a)(2)(x)
- 10. POWER LEVEL 20.2203(a)(2)(iii) 50.36(c)(2) 50.73(a)(2)(v)(A) 73.71(a)(4) 20.2203(a)(2)(iv) 50.46(a)(3)(ii) 50.73(a)(2)(v)(B) 73.71 (a)(5) 100 20.2203(a)(2)(v) 50.73(a)(2)(i)(A)
X 50.73(a)(2)(v)(C)
OTHER 20.2203(a)(2)(vi)
X 50.73(a)(2)(i)(B) 50.73(a)(2)(v)(D)
Specify in Abstract below or in
- 1.
Event Description
On May 27, 2010, with Millstone Power Station Unit 3 (MPS3) at 100% power in Mode 1, during a panel walkdown, operators discovered that two sets of auxiliary building tunnel exhaust dampers, 3HVR-AOD196A/3HVR-AOD197A and 3HVR-AOD196B/3HVR-AODi97B [DMP] were misaligned and open at the same time. This configuration created a pathway from the secondary containment to the outside and rendered secondary containment inoperable. The condition was immediately corrected by placing the dampers in their correct position with one damper set isolated.
With both damper pairs open, the East and West MCC Rod Control areas, which are part of the Supplementary Leak Collection and Release System (SLCRS) boundary, were interconnected via the ventilation exhaust ducts with the North and South-Cable Tunnels (auxiliary building cable tunnels), which are not SLCRS boundaries. This configuration constitutes a secondary containment boundary breach and rendered secondary containment inoperable per the requirements of Technical Specification (TS) 3.6.6.2 "Secondary Containment". The SLCRS system, including the fans and filters, remained operable based on completed surveillances.
The correct damperposition should have been established prior to-entry into Mode 4 on May 13, 2010. Secondary Containment was inoperable from May 13, 2010 until corrected on May-27, 2010. Therefore, this condition is being reported pursuant to 10 CFR 50.73(a)(2)(i)(B) as a condition prohibited by plant technical specifications.
Secondary: Containment ensures that the release of radioactive materials from the primary containment atmosphere will be restricted to those leakage paths and associated leak rates assumed in the safety analysis.
Therefore, this condition is being reported pursuant to 10 CFR 50.73(a)(2)(v)(C) as a condition that could have prevented the fulfillment of the safety function for controlling the release of radioactive material.
- 2.
Cause
The cause of the misalignment was inadequate communications and instructions for existing procedure status between operating shifts.
- 3.
Assessment of Safety Consequences
The safety consequences associated with the breach of secondary containment via the auxiliary building tunnels is considered low. The purpose of secondary containment is to restrict leakage paths and associated leak rates of radioactive materials from the primary containment atmosphere. The Auxiliary Building tunnel exhaust damper misalignment resulted in a secondary containment breach by a pathway to the ventilation exhaust ducts of North and South Cable Tunnels. The limiting scenario associated with this damper misalignment is considered to be a design basis loss of coolant accident. The secondary containment in-leakage associated with this secondary containment breach was assessed. With the secondary containment breach, the ability of one train of SLCRS to draw a sufficient negative pressure in secondary containment could not be assured. However, since both trains of SLCRS were available, adequate SLCRS flow was available to compensate for the increased flow into the secondary containment supplied through the breach of secondary containment.
- 4.
Corrective Action
An apparent.cause evaluation was conducted to provide corrective actions, such as revised procedures and log entry requirements in accordance with the corrective action program.
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- 5.
Previous Occurrences
No previous similar events/conditions were identified.
Energy Industry Identification System (EIIS) codes are identified in the text as [XX].
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