ML20053C202
| ML20053C202 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 05/19/1982 |
| From: | Falter H MORRISON-KNUDSEN ENGINEERS, INC. |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| REF-PT21-82 NUDOCS 8206010570 | |
| Download: ML20053C202 (4) | |
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80 CREATORS OF ELECTRICAL
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POWER SUPPLY SYSTEMS
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&# A2.;OLCET.JE' f /c gag, ;g;- wa> mns May 19, 1982 Nuclear Regulatory Commission Region II Office 101 Marietta St., N.W.
Suite 3100 Atlanta, GA 30333 Attention:
J.D. O'Reilly, Regional Director
Reference:
Possible Reportable Defect 10CFR21 Component:
Robertshaw Controls Company Temperature Control Valve Models 1284 & 1825 Size 5" & 6"
Dear Sir:
Attached is a copy of a letter from the Robertshaw Controls Company dated May 13, 1982.
The nut referred to is shown on the attached partial drawing N84984-F3.
We have furnished only one valve for nuclear service and have notified the owner to inspect the valve and verify to Power Systems Division the result of the inspection. The installation in which this valve is installed has not as yet been placed into service.
We have reviewed the reported defect and have determined that the emergency diesel engine on which this valve is installed could perform its safety function because the valve would fail in the " safe" direction. Therefore, in our case, the defect is not considered reportable.
Power Systems will, however, verify that any corrective action required is completed.
Since we are not aware of other applications and the effect of these instal-lations, we considered it to be prudent to notify you of this potential defect.
Very truly yours, POWER SYSTEMS A MORRISON-KNU SEN4IVISION
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Harry W. Falter, P.E.
Division Engineer HWF/voa (g I
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D. Pennington H.Inne M. Cake E. Martin File H. Falter -
P. King T. Fryar J. Barnes ROBERTSHAW CONTROLS COMPANY l
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FULTON SYLPHON DIVISION j
2318 KINGSTON PIKE, S.W.
P.O Box 400. KNOXVILLE. TENNESSEE 37901 AREA CCCE 615. TELEPHCNE 546-0550. TwX 810 - 583 - 0143
- ~I May 13, 1982
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Power Systems Division 3
8 A Morrison Knudsen Division 3
P. O. Box 1928 MAY 1 '71982 Rocky Mount, North Carolina 27801 P0'ATR SYSIES Of!iilDi g g i m.p n g g q Purchasing Agent hj@j@.hd,[l f,l],, ld,,
Gentlemen:
This letter is to inform you of an incident involving a Robertshaw thermostatic valve supplied for use at a nuclear power plant. This information should be evaluated by the criteria set forth in Title 10 of the Code of Federal Regulations Part 21 (10CFR21).
Robertshaw Models 1284 and 1825 in the 5" and 6" sizes incorporate a lower overrun assembly which absorbs movement generated by the thermal assemblies under certain conditions. The overrun assembly consists of a spring restrained between two end pieces whose length and " breakdown" is set by an axial bolt and nut.
Under normal conditions, this assembly acts as a rigid member.
Should the nut not be firmly affixed in place and " backoff" the longer length of the overrun assembly results in valve stroke which is not generated by the thermal assembly.
This additional stroke makes the thermal assembly control at a lower temperature, thus, over cooling the system.
In the Fall of 1977, it was reported to us that the nut had com-pletely " backed off" in one valve intended for nuclear service.
This allowed the valve to go into the full cooling position.
At that time the design of the overrun assembly called #or the nut to be staked in place.
The design was revised to rr quire solder-ing the nut to the bolt.
No further reports were received of any difficu.Ity.
In mid-April of this year, the Chief Project Engineer responsible for the design of these thermostatic valves visited the Virgil C. Summer Nuclear Station to aid in the investigation of over cooling of the engines used in the Stand-3y Diesel Generators.
l Plant personnel reported to him that when the valves were opened for inspection at an earlier date, one valve had the nut missing from the lower overrun assembly.
This group of valves hcd been l
supplied prior to the described design revision.
It was deter-minad that iraroper overrun assemSlies rere not responsible for the engine over cooling at thia site.
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Power Systems Division Rocky Mount, 'Iorth Carolina Attn:
Mr. Henry F. Williams Page May 13, 1932 Our investigation following the report from the Virgil Summer site disclosed that the design change made in 1977 was a "USE" change, i.e., completed overrun assemblies and completed ther-mostatic valve assemblies were "used" before the design change was implemented.
These overrun assemblies are also used in com-mercial valves, and it is impossible to determine how many, if any, assemblies with the staked construction were supplied to j
nuclear power plant after the design change was made.
In our investigation, we also discovered that at least one lot of overrun assemblies for the 5" size valves had been placed in our stock without solder locking the nut in place.
Again, since this is also used in commercial valves, we cannot determine if any of this group was actually supplied to you for use at a nuclear power plant site.
In our judgement, this type of failure does not constitute sub-stantial safety hazard; however, we cannot adequately evaluate the effect of over cooling in your application for these valves.
Therefore, as required by 10CFR21, we request that you evaluate this information concidering your application.
Yours very truly, ROBERTSHAW CONTROLS CCMPANY Fulton Sylphon Division j &&JJt' T. T. Howell Quality Manager TTH:g ec:
Mr. I. O. Johnson Mr. J. A. Howell, Jr.
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