ML20056B477
| ML20056B477 | |
| Person / Time | |
|---|---|
| Site: | 07000025 |
| Issue date: | 08/23/1990 |
| From: | Mckenney S ROCKWELL INTERNATIONAL CORP. |
| To: | NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| References | |
| NUDOCS 9008280330 | |
| Download: ML20056B477 (4) | |
Text
flockwell international Corporat6on Rockwe.ll Corporate offee 625 Liberty Avenue Pittsburgh, Pennsylvania 15222 3123 IntOrnadOnal i
i i
August 23, 1990 1
Director, Office of Nuclear Material Safety and Safeguards The U.S. Nuclear Regulatory Commission Washington, D.C.
20555 Gentlemen:
Enclosed for your information is a copy of a letter dated July 23, 1990 (which was not received until August 8, 1990) from H.
Thomas Robins to Mr. Donald R. Beall, Chairman of the Board, Rockwell International.
While the contents of the letter may not require notice to you under the Energy Reorganization Act of 1974 or regulations promulgated pursuant thereto, we believe that you should be made aware of the letter.
Effective March 10, 1989, Rockwell International sold the business conducted by its former Raleigh Plant to Edward Valvas, Inc., a subsidiary of BTR Dunlop, Inc.
Accordingly, we do not have the relevant data and records to evaluate this matter, By separate letter, we are forwarding to BTR Dunlop, Inc. a copy i
of this letter and of the letter attached hereto.
Very truly yours, S. S. M * \\
S. S. McKenney Assistant General Counsel l
1 SSM/ sly l
Enclosure I
CERTIFIED MAIL:
l RETURN RECEIPT REQUESTED:
9008280330 900823
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July 23, 1990 Mr. Donald R. Beali, Chairman of the Board i
Rockwo11 International-2230 East Imperial Highway i
El Segundo, California 90245
Dear Mr. Beall:
.There is one purpose to this letter - to bring your attention to a possible engineering flaw in the Nuclear Valves manufactured by your Raleigh plant.
I may be wrong; however, the consequences of a valve failure are so serious that I am writing to describe this problem as well as give you the logic behind my concern.
During the mid-1970's I was one of your engineering employees at the Raleigh Plant.
My responsibility was to
- i design a Lo-Boy Trailer as a test rig for transporting and live steam testing an order of 13 Nuclear Main Steam Valves pJ for Westinghouse.
This trailer was one that served to not only transport this huge valve to the test site at a nearby
~
non-nuclear power plant,.but was designed so that the valve was lifted up by a crane and placed back on it in an upright position to allow testing in the actual operating position it would assume in the nuclear plant.
Included in my job was the responsibility for designing the huge 7" thick steel end plates to seal the openings of-these valves and allow pressurization.
These end plates were under tremendous loads; and, as human life was involved should they fail, I carefully began an investigation of the steel castings that held the bolts securing the plates.
What I discovered was-a serious problem - the steel castings were filled with voids!
Apparently the casting process was defective and was producing voids throughout these valve castings - not only on the one valve I was working on but the smaller valves as well.
The t
standard procedure at the Raleigh Plant was to repair these defective castings by laboriously grinding out and removing.the casting material back to solid metal then building up the. casting wall.-
The restructuring of the wall was accomplished by welding
. bead-upon-bead of weld material until the hole was closed.
The veld repairsivere then furnaco annealed.
Static Pressure tests on the repaired valve checked the integrity.
In my opinion, as an engineer this was not a' good repair for a defective casting.
The first priority should be to clean up the casting process
-itself.
L
/5,48C AUG 31990
.Mr. Donald R. Beall
-Rockwell International
' July 23, 1990
+
Page Two Any veld has the small voids ar.G inclusions that, although as small as a mustard seed, can become the source of fatigue cracks.
The result of repairing these defective castings -
some valves had holes as large as a basketball before the veld build-up began - could easily be that the entire repaired area could come out while the nuclear plant is in operation.
i Since these repairs were all over the body of the valve, function ofEthe valve is also in question should a failure occur.
Just as we logically do not build Nuclear Plants over The San Andreas Fault, so too it seems.that a metallurgical
. fault should not be tolerated.
4 My findings regarding these voids in these huge castings were put into an. engineering uemo to my superiors with the suggestion that Rockwell initiate a Research and Development Program to discover and correct the basic cause of the problem.
My thinking was that innovative techniques---perhaps vacuum casting - would be needed to solve this problem and make a strong, homogeneous casting without voids.
To me, it seemed extremely important that each one of these castings be absolutely sound so that our nation might have the best valve possible in'each one of our nuclear power plants as well as in the many strategic places these valves are used in our nation's defenses.
t Sometime after writing this memo I lost my job with Rockwell.
There was a completely closed mind by Raleigh Management to this most serious casting problem.
This memo was not the only reason.
In attempting to develop a safe design for this test rig, I missed a management-imposed target date.
For over 14 years now I have not aaid anything about this
. defect in these castings because, until recently, I honestly felt that the static pressure test performed on each valve was adequate to insure the safety of <>ur nation's nuclear power i
plants.
However, the one failure of the Aloha Airlines Jet in which a portion of the hull failed in flight after extremely long service time has caused me to reconsider this problem in terms of long-term fatigue.
The engineering unknowns of loads over an extended time - fatigue and/or stress corrosion cracking --
mean any of these valves still in service could pose 0 real danger.
The reality of the situation is that these should be
(
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Mr. Donald R. Beall Rockwell International July 23, 1990 Page Three checked because of the serious risk involved.
It would seem likely that a catastrophic failure of a huge section of a working 32" Main Steam Valve could, not only cause the valve to become inocerative, but the resulting steam pressure loss could put a huge step change in the operating level of the nuclear plant that could have extremely serious consequences.
How would you like to be working or living around such a valve?
From the weld repairs I saw in the Raleigh Plant, it seems possible to me that long-term fatigue failure could actually cause a valve to split in half!
I also belkve that the kind of failure potential we have here would not be considered as likely in any fail-safe study.
In my opinion, there is first of all a need to address this problem intelligently.
Consider the Aloha Aircraft failures rather than letting it happen, may I suggest that your people honestly look at the recorded histories of each one of the valves shipped from the Raleigh Plant during the time this casting problem existed.
If this defect has been corrected, that would date which valves are free fron,such a fatigue failure.
May I suggest that these records and any problems revealed be the basis for a careful engineering and metallurgical evaluation.
Because this fatigue type failure is difficult or impossible to detect, these valves should be replaced with Laod hardware - castings made after a Research and Development Program has solved the void problem.
Only such a Development Program in my opinion can lay a good, solid foundation for future nuclear plants.
Although the growth of our nation's nuclear program has nearly stopped, it would seem to me that the solution of the problem pointed out in this letter is one way to begin to build the kind of integrity and reliability that will allow it to Jestart.
One thing I have learned in industry is that complete openmindedness and frankness in dealing with problems produces an environment in which real progre:ss is made.
That is the spirit of this letter.
Sincerely,'
-rV arm m
H. Thomas Robir.s 1 Rocksolid Road Cave Spring, Georgia 30124 cc Senator Sam Nunn i