05000336/LER-2009-005, Both Containment Air Lock Doors Open in Mode 1
| ML100560359 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 01/29/2010 |
| From: | Jordan A Dominion Nuclear Connecticut |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 10-042, FOIA/PA-2011-0115 LER 09-005-00 | |
| Download: ML100560359 (6) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(viii)(B) 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(iv)(A), 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)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2) |
| 3362009005R00 - NRC Website | |
text
Dominion Nuclear Connel:[il:ut, Inc.
M illslOne Power Station Rope Ferry Road
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Wate:rford, CT 06385 U. S. Nuclear Regulatory Commission Attention: Document Control Desl<
Washington, DC 20555 DOMINION NUCLEAR CONNECTICUT, INC.
MILLSTONE POWER STATION UNIT 2 LICENSEE EVENT REPORT 2009-005-00 JAN 292018*
Serial No.
.10-042 MPS LicrrGC RO Docket No.
50-336 License No.
DPR-65 This letter forwards Licensee Event Report (LER) 2009.:.005-00 documenting a condition discovered at Millstone Power Station Unit 2, on December 2,2009. This LER is being submitted pursuant to 10 CFR 50. 73(a)(2)(v)(C) as a condition that could have prevented the fulfillment of the safety function of the containment air locks 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.
SincerE~ly,
~dan Site Vice President - Millstone Attachments: 1 Commitments made in this letter: None
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cc:
U.S. Nuclear Regulatory Commission Region I 475 Allendale Road King of Prussia, PA 19406-1415 Ms. C. J. Sanders Project Manager U.S. Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike Mail Stop 0883 Rockville, MD 20852-273B NRC Senior Resident Inspector Millstone Power Station
- --------------------.--'---------------c-Serial No.10-042 Docket No. 50-336 Ci'cemsee Event Report 2009-005-00 Page 2 of 2
Serial No.10-042 Docket No. 50-336 Licensee Event Report 2009-005-ob ATTACHMENT LICENSEE EVENT REPORT 2009~005~OO MILLSTONE POWER STATION UNIT 2 DOMINION NUCLEAR CONNECTICUT, INC.
U.S. NUCLEAR REGULATORY COMMiSSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 08131/2010 (9-2007)
- .the NRC may not conduct or sponsor.
digits/characters for each block) and a person is not requiied to respond Ill, the informallon coIection.
- 3. PAGE Millstone Power Station - Unit 2 05000336 10F3
- 4. TITLE Both Containment Air Lock Doors Open in Me-de 1
- 5. EVENT DATE
- 6. LER NUMBEF
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR SEaUENTIA REV MONTH DAY YEAR 05000 LNUMBER NO.
FACILITY NAME DOCKET NUMBER 12 2
2009 2009 - 005 - 00 01 29 2010 05000
- 9. OPERATING MODE r-- 11. THIS REPORT IS~MlnED PURSUANT TO THE~UIREMENTS OF 10 CFR :
Check aU that apply) 20.2201 (b) 2O.2203(a)(3)(i) 50.73(a)(2)(i)(C) 50.73(a)(2)(vii) f--
~
I--
1 20.2201 (d) 20.2203(a)(3)(ii) 50.73(a)(2)(ii)(A) 50.73(a)(2)(viii)(A)
~ 20.2203(a)(1)
I-- 20.2203(a)(4) f-- 5O.73(a)(2)(ii)(B) 50.73(a)(2)(viii)(B) r--
I--
I--
20.2203(a)(2)(i) 50.36(c)(1)(I)(A) 50.73(a)(2)(iii)
SO.73(a)(2)(ix)(A)
~
I--
'-- 20.2203(a)(2)(ii) ~ 50.36(c)(1 )(ii)(A)
I-- 50.73(a)(2)(iv)(A) 5O.73(a)(2)(x)
- 10. POWI:R LEVEL 20.2203(a)(2)(iii)
SO.36(c)(2) 50.73(a)(2)(v)(A) 73.71(a)(4)
I--
I--
20.2203(a)(2)(iv)
SO.46(a)(3)(ii) 7 50.73(a)(2)(v)(B) 73.71 (a)(5)
~
OTHER 100 20.2203(a)(2)(v) 50.73(a)(2)(i)(A) 50.73(a)(2)(v)(C)
~
f----
20.2203(a)(2)(vi) 50.73(a)(2)(Q(B) 50.73(a)(2)(v)(D)
Specify in Abstract below or in NRC Fonn 366A
- 12. LICENSEE CONTACT FOR THIS LER FACILITY NAME TELEPHONE NUMBER (Include Area Code)
William D. Bartron, Nuclear Station Licensing 860-444-4301-
CAUSE
SYSTEM COMPONENT MANU*
REPORTABLE
CAUSE
SYSTEM COMPONENT MANU-REPORTABLE FACTURER TO EPlX FACTURER TO EPIX r-
- 14. SUPPLEMENTAL REPORT EXPECTED is. EXPECTED MONTH DAY YEAR [J
YES (Ifytts, complete 15. EXPECTED SUBMIS~*ION DATE)
~ NO SUBMISSION DATE ABSTRACT (Umit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)
On November 13, 2009, with Millstone Power Station Unit 2 exiting a refueling outage and preparing to go from Mode 5 to Mode 4, both the inner and outer containment personnel hatch air lock doors were closed, verified closed and successfully pressure tested.
On December 2, 2009, while in Mode 1 at '100% power, personnel entered the containment for a planned entry.
Subsequently, while in the process of entering the containment, a second entry team opened the outer air lock door and observed the inner door ajar. This condition should have been prevented by a design interlock Which prevents opening the outer air lock door if the inner air lock door is not closed. The interlock failed to perform its design function because it was not properly reset during the refueling outage due to inadequate procedures.
The outer air lock door was immediately closed. The time both air lock doors were open was less than one minute.
The procedlures that restore and verify the containment air lock door interlock have been revised. This condition is being reported pursuant to 10 CFR 50.n(a)(2)(v)(C) as any event or condition that at the time of discovery could have prevented the fulfillment of the safety function of structures or systems that are needed to control the release of radioactive material.
r'RI. FORM 366 (9-2007)
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1
Event Description
2009 005 00 On November 13, 2009, with Millstone Pcwer Station Unit 2 eXiting a refueling outage and preparing to go from Mode 5 to Mode 4, both the inner and outer containment personnel hatch air Jock doors [DR] were closed, verified closed and successfully pressure tested.
On December 2, 2009, while in Mode 1 a1 100% power, personnel entered the containment for a planned entry.
Subsequently, while in the process of entHring the containment, a second entry team opened the outer air lock door and observed the inner door ajar. This condition should have been prevented by a design interlock which prevents opening the outer air lock door if the inner air lock door is not closed. The interlock failed to perform its design function because it was not properly reset during the refueling outage due to inadequate procedures. The outer air lock door was immediately closed. The time both air lock doors were open was less than one minute.
This condition is being reported pursuant to 10 CFR 50_73(a)(2)(v)(C} as any event or condition that at the time of discovery could have prevented the fulfillment of the safety function of structures or systems that are needed to control thli:l release of radioactive material.
2
Cause
The interlock failed to perform its design function because the interlock had not been properly reset in Mode 5 prior to entering Mode 4 on November 13, 2009. Although the interlock had not been properly reset on November 13, 2009, both doors were fully closed and a successful pressure test of the air lock was completed prior to restarting from a refueling outage. (The c::mtainment air Jock interlock mechanism is defeated in Modes 5 and 6 during refueling outages.)
The caUSE~ of the interlock not being properly reset was an inadequate procedure that did not provide sufficient details to complete the interlock restoration. A contributing cause is that the surveillance procedure credited with verifying the proper restoration of the interlock was not adequate and incorrectly concluded that the interlock had been restored.
3 Assessmemt of Safety Consequences This condition is judged to be of very low ::;afety significance. The requirements on containment penetration closure and operability ensure that a release of radioactive material within containment to the environment will be minimized.
Plant Technical Specification (TS) 3.6.1.3 "Containment Air Locks" and 3.6.1.1 "Containment Integrity" apply.
TS 3.6.1.:3a states that the containment a r lock shall be operable with both doors closed except when the air lock is being used for normal transit entry and exit through containment, then at least one air lock door shalfbe closed_
Upon discovery and recognition the inner air lock door was ajar; the outer door was immediately closed.
Although TS 3.6.1.3 Action b (Action b stctes in part, "With only the containment air lock interlock mechanism inoperable, verify an OPERABLE air lock door is closed within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> and lock an OPERABLE air lock door closed within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.") was met, this conditions being reported as a condition which could have prevented the fulfillment of the safety function of the containment air locks to control the release of radioactive material.
N"C "ORM 366A (9-2007)
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4 CorrectivEl Action 2009 005 -
00 Upon discovery that the inner air lock door was ajar, the outer door was immediately closed.
The maintenance procedure which restores the containment air lock interlock has been revised to provide clearer steps for restoration of the interlock. The surveillance procedure has been revised to ensure that restoration of the interlock has been achieved.
Additional corrective actions are being addressed in accordance with the Millstone Corrective Action Program.
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Previous Occurrences
No previous similar events/conditions were identified.
Energy Industry Identification System (EllS) codes are identified in the text as [XX}.
tJR::: F' )RM 366A (9-2007)
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