05000285/LER-2011-002, Regarding Failure of an RPS Trip Unit

Regarding Failure of an RPS Trip Unit

ML110950134
Person / Time
Site:	Fort Calhoun
Issue date:	04/04/2011
From:	Reinhart J Omaha Public Power District
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
LIC-11-0022 LER 11-002-00
Download: ML110950134 (5)

LER-2011-002, Regarding Failure of an RPS Trip Unit

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
2852011002R00 - NRC Website

text

LlC-11-0022 April 4, 2011 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001

Reference:

Docket No. 50-285

Subject:

Licensee Event Report 2011-002, Revision 0, for the Fort Calhoun Station Please find attached Licensee Event Report 2011-002, Revision 0, dated, April 4, 2011.

This report is being submitted pursuant to 10CFR50.73(a)(2)(i){8). If you should have any questions, please contact me.

Sincerely,

~

fl~

J fr y Reinhart Site >ice President JARlepm Attachment c:

E. E. Collins, Jr., NRC Regional Administrator, Region IV L. E. Wilkins, NRC Project Manager J. C. Kirkland, NRC Senior Resident Inspector INPO Records Center

NRC FORM 366 (10-2010)

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION (10-2010)

LICENSEE EVENT REPORT (LER)

(See reverse for required number of digits/characters for each block)

APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2013

, the NRC may not conduct or sp onsor, and a person is not required to respond to, th e

information collection.

1. FACILITY NAME Fort Calhoun Station

2. DOCKET NUMBER 05000285

3. PAGE 1 OF 4

4. TITLE Failure of an RPS Trip Unit

5. EVENT DATE

6. LER NUMBER

7. REPORT DATE

8. OTHER FACILITIES INVOLVED MONTH DAY YEAR YEAR SEQUENTIAL NUMBER REV NO.

MONTH DAY YEAR FACILITY NAME DOCKET NUMBER 05000 2 4 2011 2011 - 002 -

0 4 4

2011 FACILITY NAME DOCKET NUMBER 05000

9. OPERATING MODE 1

11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply) 20.2201(b) 20.2203(a)(3)(i) 50.73(a)(2)(i)(C) 50.73(a)(2)(vii) 20.2201(d) 20.2203(a)(3)(ii) 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)(ii)(A) 50.73(a)(2)(iv)(A) 50.73(a)(2)(x) 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) 20.2203(a)(2)(v) 50.73(a)(2)(i)(A) 50.73(a)(2)(v)(C)

OTHER 20.2203(a)(2)(vi) 50.73(a)(2)(i)(B) 50.73(a)(2)(v)(D)

Specify in Abstract below or in LICENSEE EVENT REPORT (LER)

CONTINUATION SHEET CONCLUSION A root cause analysis is in progress. The results of the analysis will be reported in a revision to this LER.

CORRECTIVE ACTIONS

The wire between terminals T-74 and relay contact terminal 12 was replaced. Additional corrective actions will be documented in a revision to this LER.

SAFETY SIGNIFICANCE

The overall effect on the one SG Low Pressure trip setpoint was less than 10 pounds per square inch (psi) at 39 millivolts and not more than 30 psi at the highest ever recorded difference of 120 millivolts recorded on May 14, 2009.

Even with a failed instrument channel, the margin of safety as defined in the basis of the FCS TS was maintained. The plant was always able to trip on Low SG pressure in, at least, a two out of two reactor protection logic. Even with these RPS channels inoperable, the single failure criteria for the RPS system was met. Therefore the health and safety of the public was not impacted by this RPS failure.

SAFETY SYSTEM FUNCTIONAL FAILURE This event does not result in a safety system functional failure in accordance with NEI-99-02.

PREVIOUS EVENTS:

No previous LER have documented problems with this circuitry in RPS.