ML20153A974
| ML20153A974 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 03/11/1988 |
| From: | NRC OFFICE OF SPECIAL PROJECTS |
| To: | |
| Shared Package | |
| ML20127A683 | List:
|
| References | |
| NUDOCS 8803210315 | |
| Download: ML20153A974 (2) | |
Text
a l
,pa arog'o UNITED STATES E'
m [g; NUCLEAR REGULATORY COMMISSION
/ l WASHINGTON, D. C. 20555
)
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SAFETY EVALUATION REPORT BY THE OFFICE OF SPECIAL PROJECTS EMPLOYEE CONCERN ELEMENT REPORT 17301 "INSTRUMENT LINE SLOPE" TENNESSEE VALLEY AUTHORITY SEQUOYAH NUCLEAR POWER PLANT, UNITS 1 AND 2 DOCKET NOS. 50-327 AND 50-328 I.
SUBJECT Category:
Construction (10,000)
Subcategory:
Instrument line installation as related to construction (17,300)
Element:
Instrument Line Slope (17,301)
Employee Concern:
IN-85-68-N07 IN-86-222-001 IN-85-119-001 IN-85-197-001 IN-85-218-001 IN-85-982-002 IN-85-985-001 PH-85-001-002 XX-85-046-001
$0P AA-001-001 The basis for Element Report 17301, Rev' 4, prepared January 7,1987 are ten employee concerns related to probleR G instrument line slope.
Seven of s
the ten concerns about instrument sensing line slope address specific instances where slope criteria were not met. Three concerns generically address slope criteria non-compliance. The issue raised in all concerns was that instrument sensing lines were not installed in accordance with the minimum slope criteria specific by design document.
i II.
SUMMARY
OF ISSUE The issue raised by this element report about instrument line slope not confonning to the requirements on design document is factual.
The installed cnnfiguration of sensing lines do not create an operating or safety concern durirg normal operating conditions as evidenced by the plant operation.
However, for abnonnal or accident conditicos there may be problems.
There appears to be a number of different problems with the instrument sensing line.
Some instrument lines have insufficient positive slope while others have a regative slope.
Some instrument lines, such as those within the auxiliary feedwater system have been relocated to assure system functionality, while others in effluent gas treatment systems require the addition of condensate i
collection chambers.
Instrument line slope can have an effect on instrument sensor accuracy which ceuld lead to instrument sensor accuracy not detecting processes outside safety limits and could affect the Chapter 15 accident analysis.
Instrument sensing lines act as a coupling between the process and sensor and to be effective it must be filled with the known fluid.
Proper slope
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. gives a high degree of confidence that the sense line is properly filled with the known fluid. With insufficient slope, gas may become entrapped with the liquid medium or liquid may condense frnm gas medium and may cause a degradation in instrument accuracy.
III. EVALUATION TVA has submitted a six volume report titled, "ECTG Slope Closure" describing the problem with the instrument line slope and resolutien of the problem.
Staff is reviewing this report under Sequoyah NPP Volume II scope and it's finding will be included in the Volume II SER.
IV. CONCLUSION Based on our review, we conclude that the employee concerns regarding instrument line slope were valid.
TVA's investigation, evaluation and corrective action plans for the concerns are being reviewed under Sequoyah NPP, Volume II SER and will be documented in the Volume II SEP.
.