ML20086E263

AO 50-267/74/1A:on 740114,during Initial Fuel Loading,Six Alignment Dowel Pins Found Cracked or Chipped & Fuel Plugs out-of-spec.Caused by Mfg & Shipment Handling Errors.Dowel Pins & Plugs Replaced

ML20086E263
Person / Time
Site:	Fort Saint Vrain
Issue date:	04/09/1974
From:	Swart F, Warembourg D PUBLIC SERVICE CO. OF COLORADO
To:
Shared Package
ML20086E229	List: ML20086E226 ML20086E263 ML20086E265 ML20086E282
References
AO-50-267-74-1A, NUDOCS 8312060439
Download: ML20086E263 (6)

Text

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'N "DATh: April 9, 1974 ABNORMAL OCCURRENCE X FORT ST. VRAIN NUCLEAR GENERATING STATION PUBLIC SERVICE COMPANY OF COLORADO P. O. Box 361 Platteville, Colorado 80651 REPORT NO. 50-267/74/1A i Interim Final X IDENTIFICATION OF OCCURRENCE:

This report is written to finalize Interim Report 50-267/74/1, dated Jan. 14, 1974, concerning discrepancies found during the inspection associated with Initial Fuel Loading.

This event is considered to be an abnormal occurence as defined in the Technical Specifications, paragraph 2.1F.

CONDITIONS PRIOR TO OCCURRENCE:

Steady State Power Routine Shutdown Hot Shutdown Routine Load Change Cold Shutdown X Other (specify)-

Refueling Shutdown Initial Fuel Loading Routine Startup

• The major plant pan. meters at the time of the event were as follows:

Power. RTR, N/A- MWth Elect, N/A MWe Secondory Coolant Pressure N/A' psig

. Temperature N/A- F Flow N/A -f/hr.

Frksary Coolant Pressure N/A- psig Temperature N/A~ * - 'F Core Inlet N/A 'F Core Outl'et h2 05 S

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DESCRIPTION OF OCCURENCES:

During reactor fuel loading at Fort St. Vrain the following fuel discrepancies were found:

1. Six alignment dowel pins were found to be cracked and/or chipped.

2. One fuel hole plug that extended above the surface of the element. ,

One fuel hole plug was found to be missing.

3.

See Attachment "A" APPARENT CAUSE OF OCCURRENCE:

Design Unusual Service Cond. Incl. Envir.

X Manufacture Component Failure Installation /Const. Other (specify)

Operator Handling in Preparation for Procedure Shipment.

ANALYSIS OF OCCURRENCE:

3 Dowel Pin Damage:

The dowel pin damage appears to occur randomly. 'A review of the damaged'

' elements with reference to particular manufacturing times, processes, inspections, or packaging indicated no systematic cause for the dowel damage observed.

Evaluation of the damage indicates two possible causes. The first cause is that it may be possible to improperly insert the plywood cover thatLis utilized to cover the element after it is installed for chipment in the inner shipping drum. With improper insertion of'the plywood cover, it'could be-postulated ' that sufficient force could be transmitted to the dowel pin via the cover from the outside closure to cause damage. The second, and most, probable cause is related to the use of vermiculite packing material.which:

is placed over the bagged fuel element for shipment. This. vermiculite'was

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placed using a rather heavy aluminum scoop. Striking the dowels with this 1

scoop could have resulted in the damage observed. Because the fuel elements i

are not accessible for inspection after packing and because only a sample of the fuel elements are inspected on initial arrival on site, such damage would i not be detected by the QA program until just prior to refueling when all fuel 1

elements are given a 100% inspection.

To reduce the possibility of inadvertant damage during element pack-aging, the aluminum scoop will be replaced by flexible plastic scoops. GA has taken necessary steps to incorporate the change of the scoop material into their fuel loading procedures as witnessed by a PSC audit conducted 4-2-74.

1 FUEL PLUG DISCREPANCIES Again, a thorough review of these discrepancies indicated the problem to be a random one.

In reviewing the QA procedures, all elements are given a final inspecticn; however, due to the black surface of the element and many open coolant holes, it would not be too dificult to miss a full plug during such a visual inspec-tion. To improve this inspection effort, _ GA has developed a visual templ'.te which, when placed on the fuel element, shows only the, fuel holes and covers all the coolant holes. Use of this template is being incorporated in the QC procedures as evidenced by a PSC audit conducted 4/2/74.

d CORRECTIVE ACTION k The six dowel. pins and out-of-specification fuel plugs were replaced at Fort St. Vrain, using procedures and supervisory personnel supplied by General I Atomic. A plug was inserted into the fuel hole which was found to be without one, using a procedure provided by General Atomic.

Implementation by GA of those corrective measures indicated above should

-provide satisfactory results. These changes, coupled:with-the fact that a k

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. 100% inspection-is made on site prior to fuel loading provides adequate j assurance that such defects will.be prevented and/or detected prior to i fuel element insertion into the core. "

FAILURE DATA /SIMILAR REPORTED OCCURRENCES:

l No failures of this type had previously been experienced.

PROGRAMMATIC IMPACT:

4 No programmatic impact will be experienced' insofar as repairs were 1

completed during fuel loading on site.

CODE IMPACT:

j No codes involved.

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} Prepared By: roved: ,

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A .fr. _. b m Don Warembourg /

EALu f. V ..d Frederic E. Swart--

l Director, Quality Assurance [ Superintendent,.

3 Fort St. Vrain Nuclear Generating Station ,

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