ML19338D515

Forwards IE Circular 80-20, Changes in Safe-Slab Tank Dimensions. No Written Response Required

ML19338D515
Person / Time
Site:	07001220, 07001308, 07001309
Issue date:	08/21/1980
From:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
To:	Van Hoomissen GENERAL ELECTRIC CO.
References
NUDOCS 8009230383
Download: ML19338D515 (4)

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NUCLEAR REGULATORY COMMISSION

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REGION lli "e'g 799 ROOSEVELT ROAD 8

GLEN ELLYN. lLLINOls 60137

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Docket No. 70-1308 AU6 21 '$@

Docket No. 70-1309 Docket No. 70-1220 General Electric Company ATTN:

Mr. J. E. ' Van Hoomissen.

Manager,-Spent Fuel-Services Operation 175 Curtner. Avenue San Jose, CA 95125 Gentlemen:

The enclosed IE Circular No. 80-20 is forwarded for your information.

If there are any questions related to the suggested actions, please contact this office.

Sincerely, gh a -E.~Yk1~

Jn 0 James G.-Keppler Director

Enclosure:

IE Circular No. 80-20 cc w/ encl:

Mr. E. E. Voiland, Manager Morris Operation Mr. D. M. Dawson, Manager, Licensing and Transportation Central Files PDR Local PDR NSIC Mr. Dean Hansell, Office of Assistant Attorney General Mr. Gary N. Wright, Chief

' Division of Nuclear Safety T.D

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NUCLEAR REGULATORY COMMISSION

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August 21, 1980 IE Circular No. 80-20: -CHANGES IN SAFE-SLAB TANK DIMENSIONS Description of Circumstances:

During a ' routine inspection at a fuel facility, an NRC inspector received a report of significant dimensional changes in safe geometry tanks.

The tanks were used,to store low-enriched uranium solutions from_a scrap dissolver. The problem was first identified when a sight glass mounted on the large face of one of three' safe-slab tanks cracked from the strain of tank dimensional changes.

Further investigation and measurements revealed that the large faces of two of the tanks had bulged and increased the thickness dimensions of the tanks.

The maximum bulge occurred at the center of one of the tanks, increasing the tank thickness 21/2 in. beyond the design thickness of 51/2 in.

The bulge tapered from the tank centers to the designed 5 1/2 in. at the tank edges.

The tanks were made of 1/8-in. type 304 stainless steel with the tank edges and large faces supported and stiffened by 3/16-in angle iron.

The cause of the bulging was believed to be overpressurization due to partial plugging of the tank vent lines.

Contributing factors may have been excessive transfer rates, metal fatigue aggravated by corrosion, and the high specific gravity of the stored. solution.

Replacement tanks were provided with tie-bars and heavier 1/4-in. angle iron stiffeners-to' preserve the thickness dimensions.- Conservative calculations, taking into account the weight of solution, tank dimensions, and tie-bar'and

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stiffener strength, indicatec; that required dimensions would be maintained.

A precondition for the calculations required that the tank vent system be designed to prevent accidental pressurization.

To prevent accidental pressurization, a 1-1/2-in. overflow line was connected -

to the 1-1/2-in. vent line to the process offgas (P0G) system at'a point immediately.above each tank.

This provided a positive overflow as well as a second vent in case a plug occurred in the main POG line.

Additionally, each tank was provided with a'2" x 4" inspection port at the top with a cover free to :' float" should pressurization occur.

The tank _ dimensions were approximately 62" x 62" x 5 1/2".

The tank locations were parallel'to and about 1 ft removed from the scrap recovery area walls.

The-visual detection of the 2-1/2-in. deflection of the large tank-face from a point in front'of:the tank;is usually difficult so that measurements should be made with calipers or similar equipment to assure detection of significant d

distortion.

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Page 2 of 2

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'NM.iceito' Licensees":

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4 JAllilicensees-usingl safe-slab-:: tanks.should be aware of'the possible changes'in Jtank4 dimensions:resulting1from hydraulic or'pneumati.c'.. forces. : Certain steps:

should be taken to prevent:or detectichanges;in safe-slab' tank dimensions.

These. actions; include the.following:

L(1)- Structural analysesDshbuld be. reviewed.for all vessels designed to bel cgeometrically-safeito assure thatLthe~ possibility'of'p'ressurization'has; been. adequately considered.' 1The use of tie-bars and: rigid steel supports:-

should be! considered in; designs for:new tanks.'

'(2).- The: possibility of. vent: lines becoming' plugged should be studied and' o

special overflow mechanisms should'be provided1.if pressurization byf vent' linc. plugging is possible.

'(3) -Provision,should'be made for routine 0 aansional-checks-of; geometrically-safe vessels.

These checks should-be made whether or not the vessels are-subject;to pressurization.

No written re'ponse to.this: circular ~is' required. LIf additional information regarding thi!/ subject isErequired, contact the Director of this office.

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IEC 80-20 August 21, 1980

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i RECENTLY. ISSUED IE CIRCULARS Circular Date-of No.

Subject Issue Issued to 19

-Noncompliance with 8/26/80 All medical licensees License Requirements for Medical Licensees 80-18 10 CFR 50.59 Safety.

8/22/80 All power reactor Evaluations for Changes to facilities with an Radioactive Waste: Treatment OL or CP Systems 80-17 Fuel Pin Damage Due to Water-7/23/80 All holders of PWR Jet from Baffle Plate Corner OLs and PWR cps 80-16 Operational Deficiencies In 6/27/80 All power reactor Rosemount Model 51000 Trip facilities with an Units And Model 1152 Pressure OL or a CP Transmitters 80-15 Loss of Reactor Coolant Pump 6/20/80 All power reactor Cooling and Natural Circula-facilities with an tion Cooldown OL or CP 80-14 Radioactive Contamination of 6/24/80 All holders of power l

Plant Demineralized Water and research reactor System and Resultant Internal licenses (operating Contamination of Personnel and construction l

permits), and fuel cycle licensees 80-13

. Grid Strap Damage in 5/18/80 All holders of reactor Westinghouse Fuel Assemblies OLs and cps 80-12 Valve-Shaft-To-Actuator _ Key 5/14/80 All holders of reactor May_ Fall Out of Place When OLs and cps

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Mounted Below Horizontal Axis

.80-11 Emergency Diesel Generator 5/13/80 All holders of a power Lube Oil Cooler Failures reactor OL or CP 80-10 Failure to Maintain 4/29/80 All holders of reactor LEnvironmental Qualification OLs and cps

.of Equipment

09 Problems With Plant Internal 4/28/80 All holders of a' power Communications Systems-reactor OL or-CP j

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