05000263/LER-2013-003, Regarding Inadequate External Flooding Procedure

Regarding Inadequate External Flooding Procedure

ML13212A026
Person / Time
Site:	Monticello
Issue date:	07/30/2013
From:	Schimmel M Northern States Power Co, Xcel Energy
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
L-MT-13-068 LER 13-003-00
Download: ML13212A026 (4)

LER-2013-003, Regarding Inadequate External Flooding Procedure

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)(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 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(ii)
LER closed by
IR 05000263/2016004 (13 February 2017)
2632013003R00 - NRC Website

text

Xcel Energy@

July 30, 2013 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Monticello Nuclear Generating Plant Docket 50-263 Renewed Facility Operating License No. DPR-22 LER 2013-003 "Inadequate External Flooding Procedure" A Licensee Event Report (LER) for this occurrence is attached.

Summary of Commitments Monticello Nuclear Generating Plant 2807 W County Road 75 Monticello, MN 55362 L-MT 068 10 CFR 50.73 This letter contains no new commitments and no revisions to existing commitments.

Mark A. Schimmel Site Vice President, Monticello Nuclear Generating Plant Northern States Power Company-Minnesota Enclosure cc:

Regional Administrator, Region III, USNRC Project Manager, Monticello Nuclear Generating Plant, USNRC Resident Inspector, Monticello Nuclear Generating Plant, USNRC

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB NO. 3150-0104 EXPIRES 10/31/2013 (10-2010)

, the NRC may not conduct or sponsor, and a person is no required to respond to, the information collection.

3. PAGE Monticello Nuclear Generating Plant 05000 - 263 1 OF 3

4. TITLE Inadequate External Flooding Procedure

5. EVENT DATE

6. LER NUMBER

7. REPORT DATE

8. OTHER FACILITIES INVOLVED YEAR I SEQUENTIAL I REV FACILITY NAME DOCKET NUMBER MONTH DAY YEAR NUMBER NO MONTH DAY YEAR FACILITY NAME DOCKET NUMBER 5

31 13 2013 - 003 - 00 7

30 2013

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)(i)(C)

D 50.73(a)(2)(vii) 4 D 20.2201 (d)

D 20.2203(a)(3)(ii)

D 50.73(a)(2)(ii)(A)

D 50.73(a)(2)(viii)(A)

D 20.2203(a)(1)

D 20.2203(a)(4)

[gJ 50.73(a)(2)(ii)(B)

D 50.73(a)(2)(viii)(B)

D 20.2203(a)(2)(i)

D 50.36(c)(1)(i)(A)

D 50.73(a)(2)(iii)

D 50.73(a)(2)(ix)(A)

10. POWER LEVEL D 20.2203(a)(2)(ii)

D 50.36(c)(1 )(ii)(A)

D 50.73(a)(2)(iv)(A)

D 50.73(a)(2)(x)

D 20.2203(a)(2)(iii)

D 50.36(c)(2)

D 50.73(a)(2)(v)(A)

D 73.71 (a)(4) 0%

D 20.2203(a)(2)(iv)

D 50.46(a)(3)(ii)

D 50.73(a)(2)(v)(B)

D 73.71(a)(5)

D 20.2203(a)(2)(v)

D 50.73(a)(2)(i)(A)

D 50.73(a)(2)(v)(C)

D OTHER Specify in Abstract below or in D 20.2203(a)(2)(vi)

D 50.73(a)(2)(i)(B)

D 50.73(a)(2)(v)(O)

EVENT DESCRIPTION

Prior to discovery of the condition the Monticello Nuclear Generating Plant (MNGP) was in Mode 4 at 0%

power.

In preparation for the NRC's 10 CFR 50.54(f) flooding audit, an assessment of the external flooding walkdowns was performed at MNGP during the week of May 21, 2013. This effort resulted in the identification of external flooding weaknesses in the Procedure A.6, "Acts of Nature," for mitigation of a Probable Maximum Flood (PMF) event. Examples of issues identified by the assessment team include:

Procedure A.6 does not consider the Emergency Diesel Generator Emergency Service Water drains.

A walkdown revealed that the drain is not visible in the expected location, and that it may be covered.

As a result, it is not clear if this drain would allow flood waters to bypass the levee.

Yard drains around the security access facility were not accounted for by the procedure. These would allow water to flow under the levee, if left unsealed during a PMF event.

Construction drawings contained errors that would have created a gap between the intake structure and bin wall. Additionally, there were questions on bin wall construction once access is lost from the river side of the bin wall as there are interferences on the plant side of the bin wall that would complicate construction.

On May 31,2013, an aggregate review of issues identified, such as the examples above, called into question the adequacy of Procedure A.6, "Acts of Nature," to protect the site from a Probable Maximum Flood. As a result, the MNGP submitted Event Notification 49085 for an unanalyzed condition.

EVENT ANALYSIS

This event is reportable in accordance with 10 CFR 50.73(a)(2)(ii) as an unanalyzed condition that significantly degraded plant safety. This condition is not considered a safety system functional failure.

SAFETY SIGNIFICANCE

The MNGP is required to be protected from flooding as described in the licensing basis. The procedural inadequacies could have affected the ability to protect the site during a PMF event. Since there has been no external flood approaching the PMF elevation, there were no adverse consequences to the health and safety of the public or the plant and its personnel as a result of the identified deficiencies.

Additional efforts are being conducted to determine the aggregate potential safety impact of the identified deficiencies and will be provided in the supplement to this Licensee Event Report.

CAUSE

The root cause is under investigation by the site. A supplement to this Licensee Event Report will be submitted following completion of the investigation and will outline the root cause.

CORRECTIVE ACTION

Actions have been taken to address identified deficiencies. For example, Procedure A.6, "Acts of Nature,"

was revised to address the leakage pathways that were identified in the list above. Construction drawings for the bin wall were also updated to correct the gap identified.

The root cause is under investigation by the site. A supplement to this Licensee Event Report will be submitted following completion of the investigation and will outline corrective actions to address the root

PREVIOUS SIMILAR EVENTS

On November 26, 1990 the site identified, in a Licensee Event Report (LER), that there were procedural inadequacies with the external flooding procedure related to protective measures for the Emergency Diesel Generator Fuel Oil Transfer House. The LER was supplemented April 24, 1991 with additional detail, including the cause of the event, which was procedural inadequacy. As a result, the external flooding procedure was revised to build a small levee around the Fuel Oil Transfer House. This action was recently deemed not reasonable because it would interfere with surrounding buildings and limit access to the Diesel Fuel Oil Storage Tank. The current protection method relies on an earthen levee that surrounds the site. The smaller levee around the Fuel Oil Transfer House is an optional back-up method of protection in the current revision of A.6, "Acts of Nature," and does not impact the ability to protect the Emergency Diesel Generator Fuel Oil Transfer House from a PMF.