05000237/LER-2005-004, Regarding Plant Main Steam Target Rock Safety/Relief Valve as-Found Setpoint Outside of Technical Specification Allowed Value
| ML052850324 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 09/23/2005 |
| From: | Bost D Exelon Generation Co, Exelon Nuclear |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| SVPLTR# 05-0038 LER 05-004-00 | |
| Download: ML052850324 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 2372005004R00 - NRC Website | |
text
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Exelon Generation Company, LLC www.exeloncorp.com Nu e Dresden Nuclear Power Station udear 65oo North Dresden Road Morris, IL 60450-9765 10 CFR 50.73 September 23, 2005 SVPLTR # 05-0038 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Dresden Nuclear Power Station, Unit No. 2 Renewed Facility Operating License No. DRP-19 NRC Docket No. 50-237
Subject:
Licensee Event Report 237/2005-004, "Unit 2 Main Steam Target Rock Safety/Relief Valve As-Found Setpoint Outside of Technical Specification Allowed Value" Enclosed is Licensee Event Report 237/2005-004, "Unit 2 Main Steam Target Rock Safety/Relief Valve As-Found Setpoint Outside of Technical Specification Allowed Value," for Dresden Nuclear Power Station. This event is being reported in accordance with 10 CFR 50.73(a)(2)(i)(B), 'Any operation or condition which was prohibited by the plant's Technical Specifications."
Should you have any questions concerning this report, please contact Mr. Pedro Salas, Regulatory Assurance Manager, at (815) 416-2800.
Respectfully, Danny G. Bosy Site Vice Pr.ident Dresden Mclear Power Station Enclosure cc:
Regional Administrator - NRC Region IlIl NRC Senior Resident Inspector - Dresden Nuclear Power Station
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 06/3012007 (6-2004)
, the NRC may digitscharacters for each block) not conduct or sponsor, and a person Is not required to respond to, the
- 3. PAGE Dresden Nudear Power Station Unit 2 05000237 1 OF 4
- 4. TITLE Unit 2 Main Steam Target Rock Safety/Relief Valve As-Found Setpoint Outside of Technical Specification Allowed Value S. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR SEQUENTIAL REV MONTH DAY YEARI N/A NIA NUMBER NO.
FACILITY NAME DOCKET NUMBER 07 25 2005 2005 -
004 -
00 09 23 2005 N/A N/A
- 9. OPERATING MODE
- 1. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR§: (Check all that apply) o 20.2201(b) 0 20.2203(aX3Xi) 0 50.73(aX2XiXC) 03 50.73(aX2Xvii) 1 3 20.2201(d)
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El 50.73(aX2)(iii) 03 50.73(aX2XixXA)
- 10. POWER LEVEL 0 20.2203(aX2XIi) 0 50.36(cXlXiiXA)
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[3 50.73(aX2XvXB)
[3 73.71(aX5) 10 20.2203(aX2Xv) 03 50.73(aX2XiXA)
D3 50.73(aX2XvXC) a OTHER o 20.2203(aX2Xvi) 0 50.73(aX2XiXB)
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- 12. LICENSEE CONTACT FOR THIS LER FACII rrV MAI=
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A.,4 Cnnel Dresden Nuclear Power Station - George Papanic Jr.
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ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)
On July 25, 2005, with Unit 2 at approximately 100 percent power, Dresden Nuclear Power Station discovered during a vendor inspection of a Unit 2 Main Steam Target Rock Safety/Relief Valve, that the valve's second stage disc and seat had steam cutting. This valve had been removed from Unit 2 service in December 2004 and subsequently did not pass its setpoint test on February 17, 2005. The valve lifted at approximately 1091 pounds per square inch gage which is lower than specified in Technical Specification 3.4.3, "Safety and Relief Valves," Allowed Value of 1135 pounds per square inch gage, plus or minus 11.4 pounds per square inch gage. The discovery of the steam cutting of the valve's second stage disc and seat provided sufficient evidence for Dresden Nuclear Power Station to conclude that the valve's setpoint did not meet its Technical Specification requirements while it was installed in the plant during 2004.
The apparent cause of the Target Rock Safety/Relief Valve low setpoint and steam cutting of its second stage disc and seat, was most likely caused by foreign material (e.g., rust, crud) lodged between the valve's second stage seat and disc that was introduced into the valve during in-plant testing with Reactor Coolant System steam in November 2003. A corrective action was previously implemented in November 2004 to eliminate the requirement for in-plant testing with Reactor Coolant System steam.
NR FOM_0620)PITE NRCCE AE NRC FORM 366 (6-2004)
PRINTED ON RECYCLED PAPER (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 Forrn 3664) (17) in May 2004, a Target Rock S/RV had a test result of 1094 psig that was attributed to a groove in its bellows cap, which reduced the preload on the spring force.
D.
Safety Analysis
The safety significance of the event is minimal. The S/RV can actuate in the safety mode or the relief mode. The valve's safety mode function is to automatically actuate to prevent the over pressurization of the RCS. The steam cutting of the second stage seat and disc lowered the valve's setpoint. Thus, the steam cutting would not have prevented the valve from meeting its safety mode function of preventing RCS over pressurization. Additionally, the steam cutting did not lower the valve's setpoint significantly to cause a spurious actuation of the valve at normal RCS pressure. The steam cutting did not affect the relief mode of the S/RV. Therefore, the consequences of this event had minimal impact on the health and safety of the public and reactor safety.
E.
Corrective Actions
On January 15, 2004, DNPS requested a revision to TS Surveillance Requirements 3.4.3-2, 3.5.1-6 and 3.6.1.6-2 that would eliminate the requirement to retest the S/RVs with RCS steam. The NRC approved DNPS's request for the TS change on October 19. 2004. DNPS implemented the TS change in November 2004.
DNPS replaced the Target Rock S/RV in December 2004.
F.
Previous Occurrences
A review of DNPS Licensee Event Reports (LERs) for the last three years did not identify any similar events with the Target Rock S/RVs.
G.
Component Failure Data
Target Rock S/RV Model 67F