ML19347C468
| ML19347C468 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 03/04/1977 |
| From: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Groce R YANKEE ATOMIC ELECTRIC CO. |
| References | |
| NUDOCS 8011190542 | |
| Download: ML19347C468 (1) | |
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UNITED STATES 4
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- g NUCLEAR REGULATORY COMM!sSION g
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531 PARK AVENUE O
3 KING OF PRUSSIA. PENNSYLVANI A 19406 f
April 18,1977 Docket No. 50-29 Yankee Atomic Electric Company ATTN: Mr. Robert 3. Grace E
Licensing Engineer y
20 Turnpike Road 9
Westborough, Massachusetts 01581
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Gentlemen:
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1 IE Circular, 77-08 is forwarded to you for information.
If there i
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are any questions. related to your understanding of the actions required, J
please contact this office.
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7 Sincerely, l
James P. O'Reilly
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Director r
Enclosure:
IE Circular 77-08 cc w/enci:
H. Autio, Plant Superintendent Donald G. Allen, President bec w/ encl:
/ IE Mail & Files (For Appropriate Distribution)
Central Files Public Docu=ent Room (PDR) local Public Document Room (LPDR)
Nuclear Safety Information Center (NSIC)
. Technical Infomation Center (TIC) i REG:I Reading Room l
Commonwealth of Massachusetts
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NUCLEAR REGULATORY COMMISSION f
0FFICE OF INSPECTION AND ENFORCEMENT 4
WASHINGTON, D.C.
20555 I
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}j Date: April 18,1977
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j FAILURE OF FEEDWATER SAMPLE PROBE j
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DESCRIPTION OF CIRCUMSTANCES:
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Recent events involving failure of sample probes are of concern to the I
1 NRC.
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During surveillance testing at the Cooper Nuclear Station on January 21, 1977, a High Pressure Coolant Injection (HPCI) system check valve was if found to be non-functional.
Inspection of the valve revealed a length
?d of feedwater sample prob'e lodged in the valve. The piece of sample 3
probe prevented the check valve from fully cit. sing which allowed feedwater y
to flow backward into the HPCI system injection line; however, the g
blocked check valve would not have prevented the HPCI system from supply-W ing coolant to the feedwater system in the event it was required at the g
time.
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A similar probe failure occurred at the Brunswick facility on February k
17, 1976. This piece of feedwater sample probe was found lodged in the feedwater check valve located just outboard of the primary containment.
E These feedvater sample probes are schedule 120 stainless steel,1-inch j
00, about 14-inches in length with 3 holes spaced to serve as the sample entry ports.
The sample probes are inserted and welded to the feedwater s
lines at multiple locations. The Cooper sample probe was located directly
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opposite and above the "T" connection with the HPCI discharge line.
K Due to the non-functioning HPCI check valve at Cooper, the feedwater s
system pressurized the HPCI system suction piping when HPCI surveillance j
test was attempted. This pressurization caused the flange gasket to be p.-
blown out of the check valve located in the HPCI suction piping from the torus. This would not have prevented the HPCI from supplying emergency i
cooling water in the ~ event it had been required.
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Date: April 18,1977 Page 2 of 2 5
Both the Cooper and Brunswick failed sample probes were examined by metallographic analysis.
NRC was orally informed that the probable failure mechanism was intergranular stress corrosion cracking which was g
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 far licensees to t
verify the integrity of similar components in their facilities. In addition, licensees should review the potential for such failures at their facilities and should assess the potential consequences should t
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 lower system design pressure.
Operators should be made aware of these failures and indications of such failures to enable them to respond properly should such an event occur.
1 No written response to this Circular is required.
If you need addi-tional information regarding this matter, contact the Director of the cognizant NRC Regional Office.
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