ML20070F903
| ML20070F903 | |
| Person / Time | |
|---|---|
| Site: | Waterford  |
| Issue date: | 11/15/1982 |
| From: | Maurin L LOUISIANA POWER & LIGHT CO. |
| To: | Jay Collins NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, 91, W3I82-0091, W3I82-91, NUDOCS 8212210281 | |
| Download: ML20070F903 (2) | |
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I I0UISIANA P O W E R & L I G H T! P O 60x 6XM i m o nNoE s1 m 1
- NEW CALE ANS. LOUlslANA 70174
- 4504) 366 2345 wumot s
November 15, 1982 tv uAumu Vice Presxient Nuclear Otwratens W3I82-0091 Q-3-A35.07 q
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Mr. John T. Collins, Regional Administrator, Region IV y
U. S. Nuclear Regulatory Commission i
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611 Ryan Plaza Drive, Suite 1000 Arlington, Texas 76012 ll.h
SUBJECT:
Waterford SES Unit No. 3 J
Docket No. 50-382 Potential Reportable Deficiency Report No. 91
" Material of Operator Base Plate Hubs for MSI Valves"
REFERENCE:
Telecon from M. A. Livesay (LP&L) to L. Martin (NRC) on October 19, 1982
Dear Mr. Collins:
On Octobr-19, 1982 a problem with operator base plate hub material on MSIV's was reportad to your office as Potential Reportable Deficiency #91.
I This letter is to inform you that after further evaluation, this specific problem is not considered to be reportable pursuant to the requirements of 10CFR50.55(e).
l The following is a brief description of the subject problem and our evaluation.
ACF/WKM Industries informed Ebasco Services Incorporated that they had discovered some cracking on the operator base plate hubs for the MSIV's in the heat affected zone (HAZ). This indicated that there was a possibility that the base plate hub material could have been made from an alloy material rather than carbon steel, as required.
Sanple filings were taken from valves of the same design and analyzed for the elements of Cr and Ni.
The results of the analysis showed that a small percent of the hubs contained high chromium which indicated the hub material to be an alloy material, probably 4130. Welding 4130 material into A316 Gr. 70 (plate material), using a low carbon steel welding procedure, could result in the welded connection having a higher hardness in the HAZ, due to differences in material composition.
This could cause some cracking in this area.
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8212210281 821115 PDR ADOCK 05000382 S
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Mr. John T. Collins j
W3182-0091 Page 2 i
A similar analysis was performed on the sample filings taken from the l
Waterford #3 MSIV's base plate hubs. The results of '.he analysis revealed j
that one hub on each valve base plate has a high chromium content.
i i
The cracking in the HAZ of the low alloy (4130) material is a result of i
the residual stress resulting from the welding process and lack of post weld stress relieving'. It is the nature of crack propogation that once the I
stress is relieved, crack growth is stopped. Therefore, the possibility i
of a catastrophic crack failure resulting in immediate loss of actuator i
fluid pressure is practically nil. With cracking in the HAZ, gradual loss i
i of system pressure will take place over a period of time. The system is designed with low pressure alarms and will automatically repressurize the j
systen. However, the continued leakage will depicte the system's hydraulic fluid, if not physically observed and corrected, causing closing of the i
j valves. The above deviation / defects would not affect the safety function of i
i the MSIV's, because MSIV's are closed by main steam isolation signal (MSIS).
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Also, the fail safe position for the MSlV's is closed position. This event is considered a design transient, j
l Based on the above evaluation, we consider this not reportable.
I Very truly yours, I
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j L. V. Maur l
LMV/ MAL:keh I
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