ML20086P156

Interim Deficiency Rept,Item 111 Re Design Defect on RHR Reservoir Freeze Over.Initially Reported on 840104.Util Assessing Situation & Will Add Any Equipment,Instructions & Procedures Necessary to Prevent Ice Buildup

ML20086P156
Person / Time
Site:	Fermi
Issue date:	02/06/1984
From:	Wells D DETROIT EDISON CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
111, QA-84-0079, QA-84-79, NUDOCS 8402270018
Download: ML20086P156 (3)

Text

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JA10 Donald A. We!Is usagerowy Asvece (Wu 2V %'>T 2000 Second Avenue f[$$NN February 6,1984 QA-84-0079 Mr. James C. Keppler, Regional Administrator Region III U. S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, Illinois 60137

Subject:

Report of 10CFR50.55(e) Item on Design Deficiency on the RHR Ileservoir Freeze Over (#111)

Dear Mr. Keppler:

On Januarv 4, 1984, Detroit Edison's Mr. W. R. Wingfield, Quality Engineer- natruction Quality Assurance telephoned Mr. R. C. Knop of NR': Region III to report on the design deficiency on the RHR reservoir freeze over at the Fermi 2 site.

A potential problem was identified when the RHR Complex Reservoir f roze over. It was not initially considered a potentially reportable problem since nothing was physically damaged. However, it now appears there may be a design problem in the RHR building which requires evaluation. The design of the RHR building apparently causes a natural draft that removes the heat from the building; althoug,h the reservoir is part of the RHR building, there is exposure to the outside atmosphere, which apparently is sufficient to allow the reservoir water to freeze over. This could create problems for the Diesel Generator Service Water (DCSW), Emergency Equipment Service Water (EESW) and Residual Heat Removal Service Water (RHRSW) pumps.

Even though they are bottom suction pumps, this could cause crushing of the pump column or ice blockage in the pump.

The RHR Complex Reservoir is the source of water for the ultimate heat sink as described in FSAR 9.2.5. Because of the safety related nature of the heat sink, it is designed to withstand various weather conditions and phenomenon as indicated in FSAR 9.2.5.3.1. Per FSAR 9.2.5.3.1.3, enclosing the ultimate heat sink in the RHR complex was intended to prevent the reservoir water from freezing.

- The RRR reservoir did freeze over the entire surface with a depth of ice at one spot of about three (3) inches. The weather and wind conditions for the month of December, preceding the freezing, were

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.= i' Mr. James G. Keppler, Regional Administrator February 6,1984 QA-84-0079 Page 2 colder than average. In addition, miscellaneous construction activities were ta' king place in the RHR Complex at the time, so that there was no testing or other activity to add heat to or circulate the water .in the reservoir. The FSAR indicates that the safety-related pumps would not be affected by icing because they are bottom suction pumps. Further discussion with the pump manufacturer indicated that the pumps could be . damaged with a three- (3) inch layer of ice in the

. pump column.

An analysis of the safety implications indicates that a thin layer of ice is not necessarily detrimental to the deep draft pump operation.

Once ice formation is observed, corrective steps can be taken to pre-vent significant build up, (such as recirculation of the DGSW with heat provided by thc, Diesel Generators). However, if freezing in the reservoir: advanced to. the point. that the deep draf t pumps could not be started, a common mode failure potential exists with the RHRSW, EESW and DGSW systems. These systems provide a safety-related function during a' design basis accident or loss of offsite power conditions.

The RHRSW pumps are used for both ~ reactor shutdown cooling during a normal reactor shutdown and accident conditions.

To correct. this condition Detroit Edison is initiating a program to assess the situation and add any equipment, instructions and proce-dures necessary to prevent significant ice buildup. Thio program includes the following:

a) Extensive temperature monitoring in the reservoir and in the air space above to be aware of the freezing potential and bulk fluid tempe ratures .

b) Data collection on the effect of circulating the water and

. various other corrective measures under the remaining cold weather conditions of this season.

c) ' Assuring that the pumps were not, and will not in the future be adversely affected by the freezing conditions. Detroit Edison Start Up verified that the pumps were free of ice prior to being run. The. pumps have subsequently been operated to verify that no damage has occurred.

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+ Results of this evaluation will be used by Detroit Edison to determine

' which actions 'shall be taken to correct this condition and preclude recurrence. ,As part of this evaluation Detroit. Edison will assess the need for a revision to the Technical Specifications /FSAR to assure bulk reservoir temperature is maintained at acceptable levels.

t

Mr. James G. Keppler, Regional Administrator February 6,1984 QA-84-0079 Page 3 Another report on this item, either interim or final, will be sent when further information is available. If you have questions concern-ing this matter, please contact Mr. G. M. Trahey, Assistant Director-Project Quality Assurance.

Very truly yours, ,

' N l

DAW /EHN/av cc: Mr. Richard DeYoung, Director Office of Inspection and-Enforcement U. S. Nuclear Regulatory Commission Washington, D. C. 20555 Hr. Paul Byron, Senior Resident Inspector U. S. Nuclear Regulatory Commission 6450 North Dixie Highway Newport, Michigan 48166 1

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