05000280/LER-2001-003
| Document Number | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded |
| 2802001003R00 - NRC Website | |
FACILITY NAME (1)
SURRY POWER STATION
DOCKET
05000 - 280 05000 - 281 LER NUMBER PAGE (3) OF3 18) 1.0 DESCRIPTION OF THE EVENT With Unit 1 at Refueling Shutdown conditions for a scheduled refueling outage, a "bare head" visual inspection of the Reactor Pressure Vessel (RPV) [EllS-RCT] head commenced on October 20, 2001. This inspection was performed as requested by NRC Bulletin 2001-01. As a result of the visual inspection, two control rod drive mechanism (CRDM) [EllS-AA] penetrations (Nos. 27 and 40) required additional examination.
Ultrasonic test (UT) examination of these penetrations- revealed no indications in the penetration tube material. Supplemental liquid penetrant examinations were performed and revealed surface indications in the J-groove weld material. Based on the nature of these indications, it was determined that repairs were required. On October 28, 2001, a non-emergency 8-hour notification was made to the NRC in accordance with 10CFR50.72(b)(3)(ii)(A) and 10CFR50.73(a)(2)(ii)(A) reporting apparent through-wall indications on these two penetrations.
Further examination of four additional penetrations (Nos. 18, 47, 65, and 69) was also required. UT examination revealed no indications in these penetration tubes. However, liquid penetrant examination of the penetration welds on these four penetrations revealed indications. Excavation of the indications was performed to determine the nature of the indications. While the flaws were not confirmed as through-wall indications, they were not acceptable under ASME Section XI, IW B-3600 and required repair. O On November 2, 2001, two addenda to the initial non-emergency 8-hour notification were made to the NRC reporting the unacceptable indications on the four additional penetrations.
Technical Specification 3.1.4.0 prohibits a non-isolable fault in a Reactor Coolant System component body, pipe wall, vessel wall, or pipe weld. This report is being submitted in accordance with 10CFR50.73(a)(2)(i)(B) for a condition prohibited by Technical Specifications, as well as 10CFR50.73(a)(2)(ii)(A) for a principal safety barrier being seriously degraded.
2.0 SIGNIFICANT SAFETY CONSEQUENCES AND IMPLICATIONS Reactor Coolant System (RCS) [EIIS-AB) leakage is evaluated daily. Prior to shut down of Unit 1 for the scheduled refueling outage, the RCS unidentified leakage had been relatively consistent at values significantly less than the unidentified leakage limits specified in Technical Specification 3.1.C.2. In addition, based on the results of the penetration examinations and the nature of the indications, catastrophic failure of a CRDM penetration is considered unlikely. If catastrophic failure of a CRDM penetration were to occur, it would be bounded by current accident analysis. Therefore, the health and safety of the public were not affected.
Sent By: VIRGINIA POWER - NLOS; 804 273 3715; Mar -5-02 2:19PM; Page 5/6 FACILITY NAME (1)
SURRY POWER STATION
DOCKET
05000 - 280 05000 - 281
LER NUMBER
1 6) 2001 � -- 003 -- � 00 3.0 CAUSE The apparent cause of the six penetration weld indications is believed to be Primary Water Stress Corrosion Cracking (PWSCC). Cracking due to PWSCC in pressurized water reactor (PWR) nozzles and other RPV head penetrations is not a new issue and has been identified since the late 1980s. NRC Bulletin 2001-01, dated August 3, 2001, documents cracked and leaking RPV head penetrations at four PWRs. The Bulletin directs addressees to inspect RPV head penetrations, repair as required, and provide a response to the NRC.
4.0 IMMEDIATE CORRECTIVE ACTION(S) The six penetrations were modified and repaired, and Unit 1 was returned to power operation. Discussion of the Unit 1 RPV head inspection, penetration examinations, and required repairs will be provided in the response to NRC Bulletin 2001-01.
5.0 ADDITIONAL CORRECTIVE ACTIONS None.
6.0 ACTIONS TO PREVENT RECURRENCE Further corrective actions will be provided in our response to NRC Bulletin 2001-01.
7.0 SIMILAR EVENTS removal of a Reactor Coolant Pump (RCP) Motor for maintenance, the RCP lower radial bearing Resistance Temperature Detector (RTD) connection revealed a through-wall leak of the thermowell. Technical Specification 3.1.C.4 prohibits a non-isolable fault in a RCS component body, pipe wall, vessel wall, or pipe weld. Prior to Unit operation, the defect was repaired in accordance with appropriate codes and standards.
8.0 MANUFACTURER/MODEL NUMBER - Westinghouse/SB-167 Alloy 600 nozzles 9.0 ADDITIONAL INFORMATION Surry Unit 2 was shut down to perform an inspection as requested by NRC Bulletin 2001-01. No repairs were required on Unit 2.