05000331/LER-2006-001, Regarding Inoperability of Control Building/Standby Gas Treatment System (Cb/Sbgt) Instrument Air Compressor IK-4
| ML061430465 | |
| Person / Time | |
|---|---|
| Site: | Duane Arnold  (DPR-049) |
| Issue date: | 05/04/2006 |
| From: | Vanmiddlesworth G Duane Arnold |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NG-06-0360 LER 06-001-00 | |
| Download: ML061430465 (5) | |
| 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) 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)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 3312006001R00 - NRC Website | |
text
FPL Energy.
Duane Arnold Energy Center FPL Energy Duane Arnold, LLC 3277 DAEC Road Palo, Iowa 52324 May 4, 2006 NG-06-0360 10 CFR 50.73 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555-0001 Duane Arnold Energy Center Docket 50-331 License No. DPR-49 Licensee Event Report #2006-001-00 Please find attached the subject Licensee Event Report (LER) submitted in accordance with 10 CFR 50.73. This letter contains no new NRC commitments.
Gary D. Van Middlesworth Vice President, Duane Arnold Energy Center FPL Energy Duane Arnold, LLC cc:
Administrator, Region Ill, USNRC Project Manager, DAEC, USNRC Resident Inspector, DAEC, USNRC
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 06/30/2007 6-2004)
, the NRC (See reverse for re uired number of mot onduct or sposr and a person is not required to respond to, the digits/characters fri each block) information coliection
- 1. FACILITY NAME Z DOCKET NUMBER
- 3. PAGE Duane Arnold Energy Center 05000 331 X
OF 4
- 4. TITLE Inoperability of Control Building/Standby Gas Treatment System (CB/SBGT) Instrument Air Compressor IK-4
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED MONTH YEAR SEQUENTIAL REV MONTH DAY YEAR FACILITY NAME DOCKET NUMBER DAY NUMBER NO.
05000 FACILITY NAME DOCKET NUMBER 03 05 2006 2006 1
0 05 04 2006 05000
- 9. OPERATING MODE 1I.
THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check alt that apply) 1 20.2201(b)
Q 20.2203(a)(3)(i) 50.73(a)(2)(i)(C)
D 50.73(a)(2)(vii) o20.2201(d)Q 20.2203(a)(3)(Ii)Q 50.73(a)(2)(ii)(A) 50.73(a)(2)(viii)(A) o 20.2203(a)(1)
Q 20.2203(a)(4) a 50.73(a)(2)(ii)(B)
D 50.73(a)(2)(viii)(B)
D 20.2203(a)(2)(i)
Q 50.36(c)(1)(i)(A) a 50.73(a)(2)(iii)
D 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL D 20.2203(a)(2)(ii) 0 50.36(c)(1)(li)(A)
Q 50.73(a)(2)(lv)(A)
I 50.73(a)(2)(x) 9 D 20.2203(a)(2)Ciii)
Q 50.36(c)(2)
D 50.73(a)(2)(v)(A)
Q 73.71(a)(4) 96o 20.2203(a)(2)(tv) 0 50.46(a)(3)(ii) 0 50.73(a)(2)(v)(B) 5 73.71(a)(5) a 20.2203(a)(2)(v) 5 50.73(a)(2)Q)(A) 5 50.73(a)(2)(v)(C) a OTHER o
20.2203(a)(2)(vl) z 50.73(a)(2)(i)(B) 5 50.73(a)(2)(v)(D)
Specify in Abstract below or i (If more space is required, us addhonal copies of ARC Folm 366A)
I. Description of Event
On March 5, 2006, with the plant operating at 96% power in Mode 1, during testing of Control BuildinglStandby Gas Treatment System (CBISBGT) Instrument Air Compressor 1 K-4 per Surveillance Test Procedure (STP) 3.7.9-02, 'CB/SBGTS Instrument Air Compressors System Leakage and Capacity Test, it was necessary to shutdown Compressor 1 K-4 due to overheating. An unplanned Limiting Condition for Operation (LCO) was entered.
Troubleshooting was performed and-it was determined that flow was blocked in a segment of cooling water piping containing 1I manual valve V13-0141 (1 K-4 Emergency Service Water (ESW" Supply Header Isolation) and cooling water inlet check valve V13-0121. The check valve was disassembled and no signs of failure were discovered. On March 7, 2006, the section of piping containing V13-0141 and V13-0121 was removed, and upon inspection, it was discovered that the valve stem and disc of VI 3-0141 were separated.
The STP had last been performed successfully on January 30, 2006, as indicated by a cooling water return temperature of 56° F.
On February 7, 2006, valve V13-0141 had been dosed to provide an isolation boundary for maintenance. It is concluded that the disc fractured while attempting to re-open the valve on February 8, 2006.
Technical Specification (TS) LCO 3.7.9 states that two CBISBGT Instrument Air subsystems shall be OPERABLE in MODES 1, 2, and 3. With one CB/SBGT Instrument Air subsystem inoperable (Condition A), required features, supported by the inoperable CBI SBGT Instrument Air subsystem, are to be declared inoperable when the redundant required features are inoperable (4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> from discovery of Condition A concurrent with inoperability of redundant required features), and the CBISBGT Instrument Air subsystems are to be restored to OPERABLE status (within 7 days).
A review of electronic log entries for 'A' SBGT (redundant required feature) indicates that on February 27, 2006 (at 2108), planned TS LCO 3.6.4.3 Condition A (One SBGT subsystem inoperable) was entered. On March 1, 2006 (at 2359), the LCO was exited. A redundant ('A' SBGT) required feature was therefore inoperable for a period of 50.85 hours9.837963e-4 days <br />0.0236 hours <br />1.405423e-4 weeks <br />3.23425e-5 months <br />. Evidence indicates that the VI3-0141 disc/stem separation occurred on February 8, 2006. Therefore the Completion Times associated with LCO 3.7.9 Condition A (4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> to declare equipment supported by 1 K4 inoperable when 'A' SBGT was inoperable from February 27 to March 1, and 7 days to restore CB/SBGT Instrument Air subsystem to OPERABLE status), and Condition B (be in mode 3 in 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and mode 4 in 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />) were exceeded.
II. Assessment of Safety Consequences
The instrument air system is comprised of three main compressors (1 K-90A, B, and C) and a backup air compressor (1 K-1) which supply air to loads during normal operation. Since I K-90A, B, and C are powered from non-essential sources,-these compressors -
do not operate during loss-of-offsite power events.
Instrument air compressors I K-3 and I K-4 are classified as safety related, and as such are relied upon to initiate and maintain air pressure necessary for operation of essential loads. However, the backup air compressor 1K-1, although not classified as safety related, can be manually aligned to receive power from an essential source. As such it is capable of supplying required loads during loss-of-offsite power events. This capability reduces reliance on 1 K-3 and 1 K-4 for achieving a safe shutdown state.
Compressor I K-4 (normally in standby mode) supplies air for control of equipment relied upon for responding to design basis accidents. The importance of the compressor in mitigating core damage or preventing a significant radiological release to the environment, however, is relatively low. The DAEC's instrument air system contains redundant components and power supplies, which serves to decrease reliance on 1 K-4 for support of safe shutdown systems. Also, many components that rely on instrument air for operation remain in, or change to a fail-safe state with regard to their primary function. The inability of the I K-4 instrument air compressor to perform its intended safety function of supplying compressed air to other systems is judged to have a low impact on plant risk.
(if more space is required, use addcional copies of ARC (if more space is required, use addiional copies of AINC Form 366A)
V. Additional Information
Previous Similar Occurrences:
A review of LERs at the DAEC over the last 3 years identified no LERs with similar events.
EIIS System and Component Codes:
_Emergency Service Water System: B1 Gate Valve (Shutoff Valve): SHV
Reporting Requirements
This report is being submitted pursuant to 10CFR50.73(aX2)(i)(B).