05000272/LER-2005-002
| Salem Generating Station - | |
| Event date: | 4-19-2005 |
|---|---|
| Report date: | 6-20-2005 |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown |
| 2722005002R00 - NRC Website | |
PLANT AND SYSTEM IDENTIFICATION
Westinghouse - Pressurized Water Reactor High Pressure Safety Injection System / Pipe Spool - {BQ/PSP}* * Energy Industry Identification System (ENS) codes and component function identifier codes appear in the text as (SS/CCC).
IDENTIFICATION OF OCCURRENCE
Event Date: April 19, 2005 Discovery Date: April 19, 2005
CONDITIONS PRIOR TO OCCURRENCE
Salem Unit 1 was in Mode 1 (POWER OPERATION) at approximately 100% power at the time of the event. No structures, systems or components were inoperable at the time of the occurrence that contributed to the event.
DESCRIPTION OF OCCURRENCE
On April 19, 2005 at approximately 0400 hours0.00463 days <br />0.111 hours <br />6.613757e-4 weeks <br />1.522e-4 months <br />, an operator identified a small leak of approximately 200 drops per minute at the weld of a 45-degree 3A-inch elbow that was located immediately upstream of local Boron Injection Tank sample valve 1SJ6 {BQ/PSP}.
It was determined that characterizing the flaw for a structural integrity could not be performed in accordance with Technical Specification (TS) Section 3.4.10.1, Action b, and isolating the leak would have resulted in isolation of all Safety Injection flow via the charging pumps to the Reactor Coolant System. At 2052 hours0.0238 days <br />0.57 hours <br />0.00339 weeks <br />7.80786e-4 months <br /> on April 19, 2005, the Boron Injection Tank flow path was declared inoperable due to the weld failure and TS 3.0.3 was entered. At 2105 hours0.0244 days <br />0.585 hours <br />0.00348 weeks <br />8.009525e-4 months <br /> Salem Unit 1 began a shut down to perform appropriate repairs.�The unit entered Mode 4 at approximately 0429 hours0.00497 days <br />0.119 hours <br />7.093254e-4 weeks <br />1.632345e-4 months <br /> on April 20, and repairs were completed at approximately 1839 hours0.0213 days <br />0.511 hours <br />0.00304 weeks <br />6.997395e-4 months <br /> on the same day.
This event is being reported pursuant to 10CFR50.73(a)(2)(i)(A), Plant Shutdown Required by Technical Specifications.
CAUSE OF OCCURRENCE
The crack in the pipe weld was caused by stress corrosion cracking that was influenced by the presence of dissolved oxygen in the water located inside the pipe. Fatigue failure was determined not to be a contributing factor to the failed weld.
PREVIOUS OCCURRENCES
Salem LERs for years 2002 through 2005 were reviewed for similar occurrences of pipe failures.
2005. The failure mechanism of the tubing was chloride-induced transgranular stress corrosion cracking initiated on the outside diameter surface.
Based on this review actions associated with these LERs would not have prevented this occurrence.
SAFETY CONSEQUENCES AND IMPLICATIONS
There were no actual safety consequences associated with this event.
The original design function of the 1SJ6 valve was a chemistry local sample line for the Boron Injection Tank (BIT), which had contained a higher concentration of boron. The function of the BIT was changed and the sample was no longer required. The valve was not in any operating procedures, nor was it used during any mode of plant operation.
The leak rate at the cracked weld was well below the Technical Specification limit for identified and unidentified leakage. A subsequent structural integrity analysis showed that the pipe was fully capable of performing its intended function when the crack existed. Therefore, nuclear safety implications are minimal.
The measured leakage was within the analyzed limit for Emergency Core Cooling System leakage outside containment during the recirculation phase of post LOCA recovery, therefore, GDC 19 compliance was maintained.
Based on the above, there was no impact to the health and safety of the public.
A review of this event determined that a Safety System Functional Failure (SSFF) as defined in the Nuclear Energy Institute (NEI) 99-02 did not occur.
CORRECTIVE ACTIONS
1. The Salmi Unit 1 piping with the cracked weld was replaced (associated with valve 1SJ6).
2. Salem Units 1 and 2 extents of condition walk-downs were performed to determine the presence of similar leaks. No leaks were found.
3. The Salem 2 piping associated with valve 2SJ6 was modified during the Refueling Outage 2R14 to preclude a similar failure.
COMMITMENTS
This LER contains no commitments.