ML20093J002

Interim Deficiency Rept 55-84-13 Re Suppression Pool Temp Monitoring Sys.Initially Reported on 840607.A/E Will Perform Evaluation of Current Design Adequacy to Meet Accidents Resulting in Uncovering of Pool Temp Sensors

ML20093J002
Person / Time
Site:	Clinton, 05000467
Issue date:	07/09/1984
From:	Hull D ILLINOIS POWER CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
1605-L, 55-84-13, U-10176, NUDOCS 8407250490
Download: ML20093J002 (2)

Text

- ._ .- .-- - - _ . -__ -- - _ - - - -

, .., b rn 0 16 05-L ILLINOl8 POWER COMPANY U-10176 CLINTON Ju y PSWER 9, 1984 STATION. P.O. BOX 678. CLINTON

. _ Docket No. 50-461

. Mr. James G. Keppler l Regional Administrator F Region III.

U.3. Nuclear Regulatory Commission ,

799 Roosevelt Road Glen Ellyn, Illinois 60137

Subject:

Potential 10CFR50.55 (e) Deficiency 55-84-13:

Suppression Pool Temperature Monitoring System

Dear Mr. Keppler:

On June 7,1984, Illinois Power Company notified

~

Mr. P. Pelke, NRC Region III (Ref. IP memorandum Y-21918 dated June 7, 1984), of a potentially reportable deficiency concerning

, the Suppression Pool Temperature Monitoring System. Our investigation of this issue is continuing, and this letter is submitted as an interim report in accordance with the n requirements of 10CFR50.55(c)(3).

Statement of Potentially Reportable Deficiency / Background l

The Suppression as designed, meets the PoolGE Temperature Monitoring Sy'for design requirements Normal Poolstem (SPTMS),

i.

Monitoring," but does not meet the GE recommendation for providing a " Post-LOCA Pool Monitoring" capability.

The twenty (20) RTD units (16 safety related, 4 non-safety related) that comprise the SPTMS are physi 7 ally located with the temperature sensing tip at Elevation 730'6", which permits temperature monitoring even at low water level (LWL) alarm set t

point of Elevation 730'11"; but, in a post-LOCA condition, the RTDs could be uncovered resulting in loss of temperature monitoring. If the Suppression Pool water level is drawn down below the level of the temperature sensors, the Operator could be misled by erroneous readings and required safety actions could be delayed resulting in excessive Suppression Pool temperatures and subsequent damage to the Containment and/or containment structures.

JUL 10 E64

! 8407250490 e4o7o9 PDR ADOCK OSoOO4M 8

. PM pg

lir. James G. Kcppler Page 2 Investigation Results/ Corrective Action Illinois Power has prepared and is implementing an investigation plan to determine the extent of this problem at Clinton Power Station (CPS). The investigation plan includes:

1. The Architect / Engineer Sargent & Lundy (S&L) will perform a review / evaluation of the current design for adequacy to meet design basis accidents which could result in the uncovering of the suppression pool temperature sensors. The results of this evaluation will be submitted to Illinois Power for review.

2. Nuclear Station Engineering (NSED) will review the results of the S&L evaluation to determine the significance to safety of operations of the Clinton Power Station.

3. Appropriate corrective action necessary to resolve identified deficiencies and preclude recurrence will be addressed once the root causes have been identified.

To date NSED has directed S&L to develop and issue a redesign of the suppression pool temperature monitoring system to preclude the possibility that the temperature sensing elements would be uncovered during a design bases accident.

Safety Implications / Significance I

Illinois Power Company's investigation of this potentially reportable deficiency is continuing. The safety implications and significance of the issue will be assessed after further background information is evaluated. It is anticipated that approximately ninety (90) days will be needed to complete our investigation and to file a final report on the matter.

We trust that this interim report provides you sufficient background information to perform a general assessment of this potentially reportable-deficiency and adequately describes our overall approach to resolve the problem.

Sincerely yours,

/

. . Hall Vice President RLC/ lag cc: NRC Resident Office Director, Office of I&E, US NRC, Washington, DC 20555 Illinois Department of Nuclear Safety INPO Records Center