05000369/LER-1983-005, Forwards LER 83-005/03L-0.Detailed Event Analysis Encl

Forwards LER 83-005/03L-0.Detailed Event Analysis Encl

ML20071E971
Person / Time
Site:	McGuire
Issue date:	02/25/1983
From:	Tucker H DUKE POWER CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20071E974	List: 05000369/LER-1983-005, Forwards LER 83-005/03L-0.Detailed Event Analysis Encl 05000369/LER-1983-005-03, /03L-0:on 830127,while in Mode 5,evaluation of Initial Ice Condenser Basket Weights Found Numerous Accessible Row 8 & 9 Baskets Had Net Ice Weights Below Tech Specs.Caused by Heat Loading & Air Current
References
NUDOCS 8303140379
Download: ML20071E971 (3)

LER-1983-005, Forwards LER 83-005/03L-0.Detailed Event Analysis Encl

Event date:
Report date:
3691983005R00 - NRC Website

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= 3 "n 1 mo. Sy February 25, 1983 Mr. James P. O'Reilly, Regional Administrator U. S. Nuclear Regulatory Commission Region II 101 Marietta Street, Suite 2900 Atlanta, Georgia 30303 I

Re: McGuire Nuclear Station, Unit 1 Docket No. 50-369

Dear Mr. O'Reilly:

Please find attached Reportable Occurrence Report R0-369/83-03 (Interim).

This report concerns T.S.

3.6.5.1, "The ice bed shall be operable...".

This incident was considered to be of no significance with respect to the health and safety of the public.

A followup report will be submitted upon completion of an evaluation af ter Row 8 and 9 ice weights are corrected and the ice condenser returned to service.

Very truly yours,

1. B M :/7pc/

Hal B. Tucker PBN:j fw Attachment cc: Director Records Center Office of Management and Program Analysis Institute of Nuclear Power Operations U. S. Nuclear Regulatory Commission 1100 Circle 75 Parkway, Suite 1500 Washington, D. C.

20555 Atlanta, Georgia 30339 Senior Resident Inspector McGuire Nuclear Station gyyICI AL COM B303140379 830225 w'~ '

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o DUKE POWER COMPANY McGUIRE NUCLEAR STATION O

REPORIABLE OCCURRENCE REPORT NO. 83-05 (Interim)

REPORT DATE: February 25, 1983 FACILITY: McGuire Unit 1, Cornelius, NC IDENTIFICATION:

Inoperability of the Unit 1 Ice Condenser Due to Light Ice Basket Weights

DESCRIPTION

The Unit 1 Ice Condenser was declared inoperable on January 27, 1983 as a result of low ice weights identified in accessible Row 8 and 9 ice baskets.

Numerous Row 8 and 9 baskets in each of the 24 bavs were found to have net ice weights of less than the Technical Specification require-ment of 1269 pounds. Pursuant to Technical Specification 3.6.5.1, operation under this condition is less conservative than the minimal requirement.

The initial ice weights were completed on January 27 per procedure, " ice Basket Weight Determination" and evaluated per periodic test " Ice Bed Analysis".

At this time Unit I was in Mode 5 following a schedaled naintenance outage which began on January 21 for steam generator malification cr.d thernal sleeve removals.

This incident is a result of Design Deficiency, due to excessively high sublimation rates in Rows 8 and 9 that are attributed to heat loading from the crane wall area and subsequent air currents in the ice bed.

EVALUATION: Sublimation is a generic problem associated with the operation of ice containments throughout the industry and is a documented phenomenon with the MNS Ice Condenser. Low ice weights, attributed to sublimation, resulted in a similar incident, R0-369/82-59, in June 1982. At that time ice weights were increased by addition of flaked ice and borated water.

This "fix" was temporary; however, it allowed the Ice Condenser to be returned to an operable status and provided additional time to develop techniques for removing and reloading the ice.

Light ice weights were anticipated for Row 8 and 9 baskets due to heat Joading associated with their location near the crane wall and previous experiences.

Rows 1 through 7 ice weights have not indicated excessive sublimation rates in the past and were expected to be above the minimum ice weight. Therefore, only accessible Row 8 and 9 baskets were weighed for the initial evaluation. The high incidence of low ice weights resulted in initiation of ice removal and addition prior to completing the required Ice Condenser ice weights evaluation.

Ice removal is being accomplished by grinding the ice with an auger which is lowered into the baskets. The ground ice falls through the basket mesh to the lower Ice Condenser compartment and is removed. Pneumatic impact tools were initially used to chip the ice so that it could be vacuumed from the baskets.

Problems with the chippers becoming brittle in the Ice Condenser environment L.

Report No. 83-05 (Interim)

February 25, 1983 Page 2 and the excessive weight of the chipper extensions proved that these tools were not suitable for ice removal.

Reloading of the baskets is to be accomplished with cylinders of compressed flake ice.

These cylinders are approximately 11 x 11 1/2 inches and weigh 32 to 37 pounds. Baskets loaded with these cylinders will have a higher net ice weight than baskets loaded with flake ice due to the density of the cylinders.

Increased ice weights should increase the time between ice loads.

Cruciforms, internal X-shaped ice supperts spaced at 6 feet intervals, are being removed from the baskets as they are encountered. These stationary supports are b2ing replaced by spring locking supports as the baskets are reloaded.

Future removal of cruciforms should be expedited by this modifi-cation.

SAFET( ant. LYSIS: Row 8 and 9 ice weights taken prior to the Ice condenser ucing declared inoperable are not representative of the total ice content.

Therefore, an evaluatian of the effect of the low ice weights on the Ice Condeneer System is premature at this time. This evaluation will be delayed until Row 8 and 9 ice weights are corrected and the Ice Condenser is returned to service. A followup to this report will be submitted.

CORRECTIVE ACTION

Deficient Row 9 ice baskets will be completely unloaded, if possible, and reloaded with compacted ice cylinders. This should restore the ice weight to approximately the maximum allowed weight, 1627 pounds of ice per basket. Light weight Row 8 ice baskets will be unloaded to the third cruciform, 18 feet, and reloaded with the ice cylinders. Additional weight gained from this addition should increase the ice baskets weights sufficiently above the minimum weight of 1269 pounds of ice per basket.

Row 8 and 9 ice baskets will be weighed after the ice additions to verify their weights conform to Technical Specification Surveillance Requirements 4.6.5.1.

A representative cross section of ice baskets will be weighed after completion of ice additions. These weights will be evaluated to verify the operability of the Ice Condenser pursuant to Technical Specification 3.6.5.1.

Should this evaluation identify a deficiency, additional ice or borated water will be added to increase the weight of light ice baskets.