05000259/LER-2010-002, Drywell Pressure Instrument Channel Inoperability Due to Improper Tubing Slope

Drywell Pressure Instrument Channel Inoperability Due to Improper Tubing Slope

ML103220260
Person / Time
Site:	Browns Ferry
Issue date:	11/15/2010
From:	Polson K Tennessee Valley Authority
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
LER 10-002-00
Download: ML103220260 (10)

LER-2010-002, Drywell Pressure Instrument Channel Inoperability Due to Improper Tubing Slope

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)(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
2592010002R00 - NRC Website

text

Tennessee Valley Authority, Post Office Box 2000, Decatur, Adabama 35609-2000 November 15, 2010 10 CFR 50.73 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 Browns Ferry Nuclear Plant, Unit 1 Facility Operating License No. DPR-33 NRC Docket No. 50-259

Subject:

Licensee Event Report 50-259/2010-002-00 The enclosed Licensee Event Report provides details of operation with inoperable drywell pressure channels for longer than allowed by the Browns Ferry Nuclear Plant Technical Specifications. The Tennessee Valley Authority is submitting this report in accordance with 10 CFR 50.73(a)(2)(i)(B), any operation or condition which was prohibited by the plant's Technical Specifications.

There are no new regulatory commitments contained in this letter. Should you have any questions concerning this submittal, please contact James Emens, Nuclear Site Licensing Manager, at (256) 729-2636.

Respectfully, K. J. Poiso~n 00 Vice President Enclosure: Drywell Pressure Instrument Channel Inoperability Due to Improper Instrument Tubing Slope cc (w/ Enclosure):

NRC Regional Administrator - Region II NRC Senior Resident Inspector - Browns Ferry Nuclear Plant

Enclosure Browns Ferry Nuclear Plant Unit 1 Docket 50-259 Drywell Pressure Instrument Channel Inoperability Due to Improper Instrument Tubing Slope SEE ATTACHED

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVEDBY OMB NO. 3150-0104 EXPIRES 08/31/2010 (9-2007)

, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.

3. PAGE Browns Ferry Nuclear Plant Unit 1 05000259 1 of 8

4. TITLE: Drywell Pressure Instrument Channel Inoperability Due to Improper Instrument Tubing Slope

5. EVENT DATE

6. LER NUMBER

7. REPORT DATE

8. OTHER FACILITIES INVOLVED SEUNILRVFACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR SEQUENTIAL REV MONTH DAY YEAR N/A N/A NUMBER NO.

N

/

FACILITY NAME DOCKET NUMBER 09 16 2010 2010 002 00 11 15 2010 N/A N/A

9. OPERATING MODE

11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)

El 20.2201(b)

El 20.2203(a)(3)(i)

El 50.73(a)(2)(i)(C)

El 50.73(a)(2)(vii)

El 20.2201(d)

[I 20.2203(a)(3)(ii)

El 50.73(a)(2)(ii)(A)

El 50.73(a)(2)(viii)(A)

El 20.2203(a)(1)

[I 20.2203(a)(4)

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

[I 50.73(a)(2)(viii)(B)

E] 20.2203(a)(2)(i)

-] 50.36(c)(1)(i)(A)

El 50.73(a)(2)(iii)

El 50.73(a)(2)(ix)(A)

10. POWER LEVEL E] 20.2203(a)(2)(ii)

El 50.36(c)(1)(ii)(A)

El 50.73(a)(2)(iv)(A)

El 50.73(a)(2)(x)

El 20.2203(a)(2)(iii)

El 50.36(c)(2)

El 50.73(a)(2)(v)(A)

El 73.71(a)(4)

E] 20.2203(a)(2)(iv)

El 50.46(a)(3)(ii)

El 50.73(a)(2)(v)(B) 0l 73.71(a)(5) 100

[] 20.2203(a)(2)(v) 0l 50.73(a)(2)(i)(A)

[E 50.73(a)(2)(v)(C) 0l OTHER El 20.2203(a)(2)(vi)

Z 50.73(a)(2)(i)(B)

[E 50.73(a)(2)(v)(D)

Specify In Abstract below or in NRC Formn 368A

12. LICENSEE CONTACT FOR THIS LER NAME TELEPHONE NUMBER (Include Area Code)

Eric Bates, Licensing Engineer 256-614-7180MANU-REPORTABLE

CAUSE

SYSTEM COMPONENT MANU-REPORTABLE

CAUSE

SYSTEM COMPONENT FACTURER TO EPIX FACTURER TO EPIX

14. SUPPLEMENTAL REPORT EXPECTED

15. EXPECTED MONTH DAY YEAR SUBMISSION IZ YES (If yes, complete 15. EXPECTED SUBMISSION DATE)

[

NO DATE NA NA ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)

On September 16, 2010 it was determined that a condition initially identified on December 8, 2008 reflected inoperability of a drywell pressure channel for longer than allowed by Technical Specifications.

Subsequent review for extent of this condition identified the inoperable condition existed from October 2, 2008 until corrected on December 9, 2008. Additionally, a subsequent occurrence of an inoperable drywell pressure channel between May 25, 2010 and October 6, 2010 was discovered. Corrective actions taken on December 9,-2008 and October 6, 2010 involved purging trapped water in the instrumentation sensing line. The immediate cause was improperly sloped instrument sensing lines that allowed water to condense and collect in the sensing lines, resulting in non-conservatively biased instrumentation output signals. The instrument sensing lines are being modified during the current refueling outage to eliminate water traps and provide proper slope to assure no accumulation of condensed water. The condition resulted from modifications in 2005 which did not assure adherence to the design specifications for proper instrument sensing line slope. The cause for improper instrument slope is attributed to human error and unclear procedural guidance. The Browns Ferry procedures and processes are being revised to clearly require the verifications for proper slope.

NRC FORM 366 (9-2007)

(If more space is required, use additional copies of (If more space is required, use additional copies of (If more space is required, use additional copies of (If more space is required, use additional copies of (If more space is required, use additional copies of (If more space is required, use additional copies of (If more space is required, use additional copies of NRC Form 366A) (17)

1.

Implement Unit 1 and Unit 3 design changes that reconfigure sensing lines to eliminate water traps. Unit 1 modifications are being made during the current refueling outage. Unit 3 modifications will be scheduled within the corrective action program.

2.

Revise the general modifications procedure to specifically address implementation requirements to assure the design specification standards for instrument sensing line slopes are met. This change is scheduled within the corrective action program.

3.

Engineering design specifications were revised to require Quality Control inspection of sensing lines associated with instruments which perform a primary safety function.

This change was completed subsequent to Unit 1 Restart modifications.

VII. ADDITIONAL INFORMATION

A.

Failed Components None B.

PREVIOUS LERS ON SIMILAR EVENTS None C.

Additional Information

The corrective action documents for this report are PER 159710, PER 219150, PER 242068, and PER 279760. The BFN corrective action program is also addressing issues associated with untimely evaluations of the condition and operability determination.

D.

Safety System Functional Failure Consideration:

This event is not classified as a safety system functional failure according to NEI 99-02.

E.

Unplanned Scrams With Complications:

This event did not include a reactor scram.

VIII. COMMITMENTS

None