W3P90-0311, Clarifies NRC Misunderstanding of Open Item 8 in Insp Rept 50-382/89-39 Re Use of Open Terminal Blocks Installed at Conax Penetrations for Core Exit Thermocouples.Util Did Not State That Addl Analyses Would Be Performed
| ML20006A206 | |
| Person / Time | |
|---|---|
| Site: | Waterford  |
| Issue date: | 01/19/1990 |
| From: | Burski R LOUISIANA POWER & LIGHT CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| W3P90-0311, W3P90-311, NUDOCS 9001250453 | |
| Download: ML20006A206 (3) | |
Text
e qL Louisiana Power & Light Company-. t Z*
_. 317 Baronne Street P. O. Box 60340 -
Now Ortoans, LA 70160 0340' Tot 204 595 2005 -
o R. F. Burski Nuclear Safoty & Rogulatory Affairs-Manager W3P90_0311:
A4.05 QA January 19; 1990 t
U.S.; Nuclear Regulatory Commission.
ATTN: Document Control Desk Washington,'D.C. 20555-Subj ect :,- Waterford 3 SES.
f Docket No.-50-382 License.No NPF-38 NRC Inspection Report 50-382/89-39 Gentlemen:
i The purpose of this letter is to clarify an apparent misunderstanding'by.-
the NRC regarding-an LP&L' letter for open item 382/8632-08, reference NRC Inspection Report 50-382/89-39.
The issue concerns the use of.open terminal-blocks' installed at theLConax:
-penetrations for the Core Exit Thermocouples_(CETs). LP&L' prepared and issued LP&L letter W3B87-0222 in response to IEN 84-47._.IEN:84-47; discussed a Sandia National Laboratories (SNL) LOCA/MSLB simulation _ test-which showed that a moisture film vill form on the surface.of terminal blocks reducing insulation resistance between termitial points: and ground. and thus allowing'-
some leakage current to flow to ground. LP&L letter W3B87-0222 in assessing the applicability of the SNL test results to-Waterford 3 made
- some statements about the conditions and configuration of'the~SNL test-(NUREG CR-3691).
Specifically, LP&L letter'W3B87-0222 stated:
"The NUREC CR-3691 analysis assumes the_ reference junction inside containment which is not the' case for Waterford 3.
It also-assumed a cable routing configuration that 18 less conservative than the Waterford 3 design.- The resulting temperature readouts show a range of-error of t 300*F using-the: worst case arrangement closest to Waterford 3 design. -The,-
actual Waterford 3 error is expected to be much-less than this."
Apparently, the NRC inspector misunderstood the statement of the i 300'F; error to mean.this was the magnitude of the error at Waterford 3 when in fact the statement was referring to the magnitude of the' error for the SNL test configuration. The interpretation by the NRC is documented in inspection report 50-382/89-39 section 3.a which states:
^
"During this inspection, the licensee provided a response to IEN 84-47 stating that-the maximum exit thermocouple temperature error would be less -
than 1300'F and that this value was sufficient for the application.!
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W3P90-0311 January 19.-1990 Page 2 LP&L letter W3B87-0222 in. fact stated that the actual-Waterford 3 error is expected to be much less than i 300*F.
LP&L also notes'that nowhere in LP&L letter W3B87-0222 is any statement'made that the 1 300'F error is sufficient for Waterford 3 application as' documented in section 3.a of inspection report SG-382/89-39.
Subsequent to LP&L letter W3B87-0222,- LP&L' issued LP&L letter W3P87-0543.
The ' letter discussed the result of a Waterford 3 plant specific analysis" utilizing the SNL test and analysis.
The. assumptions used by SNL in their analysis of thermocouple circuits were based on worst case design features employed lat other nuclear power plants. The conservative design used at Waterford 3 mitigates every.
concern raised by SNL. The use:of larger wire sizes, the location of the-cold reference junction outside containment, the absence of dissimilar metal connections, the neutral pH of the containment spray, and the significantly lower post accident containment temperature combine to' eliminate any concern about the accuracy,of the information generated by' the core exit thermocouples. The maximum CET temperature ~ errors were; determined to be 6% at-550*F with' a spurious EMF of 0.5 volts, 3% at 1000*F with a spurious EMF of 0.5 volts, and in all cases 0% if no spurious:EMFs are generated. LP&L thus concluded in LP&L letter W3P87-0543 I
i:he CETs will perform their design function in postulated post-accident environments.
The NRC inspector was apprised of and provided a copy of the Waterford 3 plant specific anclysis and LP&L letter W3P87-0543.
LP&L finally notes that inspection report 50-382/89-39 section 3.a-states, "The licensee acknowledged the inspectors' concern and.will reanalyze the effect of this error (meaning i 300*F) on system operation." Although a member of our staff acknowledged that a 300*F error would be significant, the nature of the follow-up action conveyed to the NRC inspector'was to review the matter with cognizant LP&L personnel.
However, there was no intent to convey that LP&L would perform additional analysis.
An analysis.
of the i 300'F error would not be appropriate based on the facts concerning
~
this issue.
LP&L respectfully requests that based on this letter and other'information provided to the inspector open item 382/8632-08 should be closed by the NRC.
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1 W3P90-0311 January = 19, 1990 Page 3 Please contact me or Robert J. Murillo should there be any, questions.
concerning this matter RFB/RJM/ddd cc: Messrs. R.D.' Martin, NRC Region IV C. Paulk, NRC Region IV F.J. Hebdon, NRC-NRR D.L. Wigginton, NRC-NRR E.L. Blake W.M. Stevenson NRC Resident Inspectors Office NS140284E
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