05000263/LER-2010-002, Regarding Secondary Containment Briefly Degraded
| ML102150541 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 07/30/2010 |
| From: | O'Connor T Northern States Power Co, Xcel Energy |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| L-MT-10-043 LER 10-002-00 | |
| Download: ML102150541 (4) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(ix)(A) 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(x) 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)(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) 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 10 CFR 50.73(a)(2)(viii)(B) |
| 2632010002R00 - NRC Website | |
text
jXcelEnergy@
Monticello Nuclear Generating Plant 2807 W County Road 75 Monticello, MN 55362 July 30, 2010 L-MT-1 0-043 10 CFR 50.73 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555 Monticello Nuclear Generating Plant Docket No. 50-263 Renewed License No. DPR-22 LER 2010-002. "Secondary Containment Briefly Dearaded" The Licensee Event Report (LER) for this occurrence is attached.
Summary of Commitments This letter contains no new commitments and no revisions to existing commitments.
T.3-7"TimothyJ. 0C Site Vice President, Monticello Nuclear Generating Plant Northern States Power - Minnesota Enclosure cc:
Administrator, Region Ill, USNRC Project Manager, Monticello, USNRC Resident Inspector, Monticello, USNRC
NRC FORM 366 U.S. NUCLEAR REGULATORY APPROVED BY OMB NO. 3150-0104 EXPIRES 8-31-2010 (9-2007)
COMMISSION
, the NRC may not conduct or sponsor, and a digits/characters for each block) person is not required to respond to, the information collection.
FACILITY NAME (1)
DOCKET NUMBER (2)
PAGE (3)
Monticello Nuclear Generating Plant 05000263 1 of 3 TITLE (4)
Secondary Containment Briefly Degraded EVENT DATE (5)
LER NUMBER (6)
REPORT DATE (7)
OTHER FACILITIES INVOLVED (8)
MO DAY YEAR YEAR SEQUENTIAL REV MO DAY YEAR FACILITY NAME DOCKET NUMBER NUMBER NO 05000 FACILITY NAME DOCKET NUMBER 06 03 2010 2010 002 00 07 30 2010 05000 OPERATING 1
THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply) (11)
MODE (9) 20.2201(b) 20.2203(a)(3)(ii) 50.73(a)(2)(ii)(B) 50.73(a)(2)(ix)(A)
POWER 100%
20.2201 (dj 20.2203(a)(4) 50.73(a)(2)(iii) 50.73(a)(2)(x)
LEVEL (10) 20.2203(a)(1) 50.36(c)(1 )(i)(A) 50.73(a)(2)(iv)(A) 73.71 (a)(4) 20.2203(a)(2)(i) 50.36(c)(1)(ii)(A) 50.73(a)(2)(v)(A) 73.71 (a)(5) 20.2203(a)(2)(ii) 50.36(c)(2) 50.73(a)(2)(v)(B)
OTHER
- - Specify in Abstract below or 20.2203(a)(2)(iii) 50.46(a)(3)(ii)
X 50.73(a)(2)(v)(C) in NRC Form 366A 20.2203(a)(2)(iv) 50.73(a)(2)(i)(A)
X 50.73(a)(2)(v)(D) 20.2203(a)(2)(v) 50.73(a)(2)(i)(B) 50.73(a)(2)(vii) 20.2203(a)(2)(vi) 50.73(a)(2)(i)(C) 50.73(a)(2)(viii)(A)
S
~~~~~20.2203(a)(3)(i) 50.73(a)(2)(ii)(A) 50.73(a)(2)(viii)(B)
LICENSEE CONTACT FOR THIS LER (12)
NAME TELEPHONE NUMBER (Include Area Code)
Ron Baumer j 763-295-1357 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)
MANU-REPORTABLE MANU-REPORTABLE
CAUSE
SYSTEM COMPONENT FACTURER TO EPIX
CAUSE
SYSTEM COMPONENT FACTURER TO EPIX SUPPLEMENTAL REPORT EXPECTED (14)
EXPECTED MONTH DAY YEAR NO SUBMISSION YES (If yes, complete EXPECTED SUBMISSION DATE).
X NO DATE (15)
ABSTRACT At 1050, June 3, 2010, with the plant operating in Mode 1 at 100% power, DOOR-72 and DOOR-82 for airlock 413 (985' Pump Room) were inadvertently opened simultaneously, breaching the Secondary Containment (SCT) boundary. Personnel immediately identified the situation and closed both doors within four to five seconds (estimated). Shift supervision was notified; with both doors open, the station's Technical Specification TS) surveillance requirement 3.6.4.1.3 states (verify one Secondary Containment access door in each access opening is closed) was failed. The TS LCO statement 3.6.4.1 was declared not met and Action A, (Restore secondary containment to Operable status) entered. The doors were verified closed.
With SCT restored, TS 3.6.4.1 was met at 1110. The cause of the event was the design of the interlock between the doors in the 985' Pump Room does not prevent a simultaneous entry.
Corrective actions taken: the doors were closed and the interlock mechanism was verified to operate per design.U.S. NUCLEAR REGULATORY COMMISSION (9-2007)
LICENSEE EVENT REPORT (LER)
FACILITY NAME (1)
DOCKET (2)
LER NUMBER (6!
PAGE (3)
SEQUENTIAL REVISION Monticello Nuclear Generating Plant 05000263 YEAR NUMBER NUMBER 2 of 3 2010 002 00 TEXT (If more space is required, use additional copies of NRC Form 366AX17)
Event Description
At 1050, June 3, 2010, with the plant operating in Mode 1 at 100% power, DOOR-72 and DOOR-82 for airlock [AL] 413 (985' Pump Room) were inadvertently opened simultaneously, breaching the Secondary Containment (SCT) [VF] boundary. Personnel immediately identified the situation and closed both doors [DR] within four to five seconds (estimated). Shift supervision was notified; with both doors open, the station's Technical Specification TS) surveillance requirement 3.6.4.1.3 states (verify one Secondary Containment access door in each access opening is closed) was failed. The TS LCO statement 3.6.4.1 was declared not met and Action A, (Restore secondary containment to Operable status) entered. The doors were verified closed. With SCT restored, TS 3.6.4.1 was met at 1110.
This event was not the result of a cognitive error. Plant employees (Radiation Protection and Laborers) were transferring material from the contaminated area step off pad to the 985' Pump Room. The two employees entered the airlock at the same time; one from within SCT and the other from the pump room. Neither door has a window, so neither employee could see the other operating the opposite door. Both door electromagnets are normally de-energized on this airlock; when a door opens, the opposite door electromagnet energizes to prevent the door from opening. When both doors opened simultaneously, each door moved away from the electromagnet before it could energize. The employees immediately shut the airlock doors and notified Operations supervision per plant procedures. Plant personnel tested the airlock; the interlock functioned as designed.
Event Analysis
The event is reportable to the NRC under 10 CFR 50.73(a)(2)(v)(C and D) - Event or Condition that could have Prevented Fulfillment of a Safety Function. The station reported the event to the NRC under 10 CFR 50.72 (b)(3)(v)(C and D) on June 3, 2010.
This event is considered a Safety System Functional Failure because for approximately five seconds SCT was inoperable and could not prevent a ground level release of radiation if there had been a release of activity within SCT.
Safety Significance
There were no nuclear, radiological or industrial safety significant consequences related to this event.
The Monticello risk assessment group reviewed the event for risk impact. It was determined that there was no additional risk of core damage associated with this momentary breach ofU.S. NUCLEAR REGULATORY COMMISSIOIý (9-2007)
LICENSEE EVENT REPORT (LER)
FACILITY NAME (1)
DOCKET (2)
LER NUMBER (6!
PAGE (3)
SEQUENTIAL REVISION Monticello Nuclear Generating Plant 05000263 YEAR NUMBER NUMBER 3 of 3 2010
-- 002 00 TEXT (If more space is required, use additional copies of NRC Form 366AX17) secondary containment, and there was no significant increase in the risk of a Large Early Release. In conclusion, the risk impact of the event was very low.
Cause
The cause of the event was the design of the interlock between the doors in the 985' Pump Room does not prevent a simultaneous entry.
Corrective Action
The following actions were taken or are planned and will be tracked under AR01235877:
" The doors were closed and the interlock operating mechanism was verified to be operating properly.
Based on the infrequent use of the doors and low probability of occurrence, no modification of the door interlocks will be performed.
- The station will evaluate other means of maintaining air lock integrity other than a modification.
Failed Component Identification None
Previous Similar Events
In February 2007 DOOR-72 and DOOR-82 were simultaneously opened (AR01078818).
Actions taken were to shut the doors and verify the latch mechanism was working properly.
Due to the low usage of the doors, it wasdetermined that no modification of the interlocks would be performed.