ML19317E111
| ML19317E111 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 04/15/1977 |
| From: | Moseley N NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | Parker W DUKE POWER CO. |
| References | |
| NUDOCS 7912130822 | |
| Download: ML19317E111 (1) | |
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APP > 151977 In Reply Refer To:
IE:II:NCM 50-269 50-270 50-2S7 Duke Fe er Cc=yany N"C;:
M.r. 'a'illi a: O. Parker, Jr.
Vice President cf Stes: Froduction L22 South Church Street F. C. Sox 2176 Charlotte,?;crth Carclina 282h2 Gentlemen:
The enclosed Circular 77-08 is forwarded to you for information.
l If there are any questions related to your understanding of the actions required, please contact this office.
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Norman C. Moseley Director
Enclosure:
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Circular 77-08 Date:
April 15, 1977 Page 1 of 2 FAILURE OF FEEDWATER SAMPLE PROBE DESCRIPTION OF CIRCUMSTANCES:
Recent events involving failure of sample probes are of concern to the NRC.
During surveillance testing at the Cooper Nuclear Station on January 21, i
1977, a High Pressure Coolant Injection (HPCI) system check valve was found to be non-functional.
Inspection of the valve revealed a length of feedwater sample probe lodged in the valve.
The piece of sample probe prevented the check valve from fully closing which allowed feedwater to flow backward into the HPCI system injection line, hewever, the blocked check valve would not have prevented the HPCI syste= from supplying coolant to the feedwater system in the event
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it was requried at the time.
A simii r probe f ailure occurred at the Brunswick f acility on February 17, 1976. This piece of feedwater sample probe was found outbcard of the lodged in the feedwater check valve located just primary containment.
These feedwater sample probes are schedule 120 stainless steel, 1-inch OD, about 14-inches in length with 3 holes spaced to serve as the The sample probes are inserted and welded to the sample entry ports.
feedwater lines at multiple locations.
The Cooper sample probe was located directly opposite and above the "T" connection with the HPCI discharge line.
Due to the non-functioning HPCI check valve at Cooper, the feedwater syste= pressurized the HPCI system suction piping when HPCI surveil-lance test was attempted. This pressurization caused the flange to be blown out of the check valve located in the HPCI suction gasket piping from the torus. This would no: have prevented the HPCI frem it had been required.
supplying emergency cooling water in :he event i
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J Circular 77-08 Date: April 15, 1977 Page 2 of 2 Soth the Cooper and Brunswick failed sample probes sere examined by metallographic analysis.
NRC was orally informed that the probable failure mechanism was intergranular stress corrosion cracking which was probably induced by chlorides.
There was no evidence of fatigue failure.
Because there are a number of such sample probes used in light water nuclear power reactors, these failures indicate a need for licensees to verify the integrity of similar components in their facilities.
In addition, licensees should review the potential for such failures their facilities and should assess the potential consequences etshould such a failure occur. Particular attention should be given to those installations where a failure and subsequent blockage could lead to overpressurization of components of icwer system design Operators should be made aware of these failures and pressure.
indications of such failures to enable them to respond properly should such an event occur.
No written response to this Circular is required.
If you need additional information regarding this matter, contact the Director of the cognizant NRC Regional Office.
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