ML19338D528

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

ML19338D528
Person / Time
Site:	Barnwell File:Allied-General Nuclear Services icon.png
Issue date:	08/21/1980
From:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
To:	Holden R ALLIED GENERAL NUCLEAR SERVICES
References
NUDOCS 8009230400
Download: ML19338D528 (4)

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UNITED STATES 8'

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In Reply Refer To:

RII:JPO OTJ Allied-General Nuclear Services Attn:

R. B. Holden, President P. O. Box 847 Barnwell, SC 29812 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, G

e James P. O'Reilly Director

Enclosures:

1.

IE Circular No. 80-20 2.

List of Recently Issued IE Circulars

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8006190036 IEC 80-20

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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 2 1/2 in beyond the design thickness of 5 1/2 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 wa.s 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.

i l-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 stiffener strength, indicated 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 (POG) 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 b.e,

made with calipers or similar equipment to assure detection of significant distortion.

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.y IEC 80-20 August' 21, 1980 Pcg2 2 cf 2 Notice to Licensees:

All' licensees using safe-slab' tanks should be aware of the possible changes in tank dimensions resulting from hydraulic or pneumatic forces.

Certain steps should be taken to prevent or detect changes in safe-slab tank dimensions.

These actionsfinclude the following:

(1) Structural analyses should be reviewed for all vessels designed to be s

geometrically safe to assure that the possibility of preseurization has been adequately considered. The 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 special overflow mechanisms c'muld be provided if pressurization by vent line plugging is possible.

(3) Provision should be made for roscine dimensional checks of geometrically safe vessels. These checks shotld be made whether or not the vessels are subject to pressurization.

No writtsu response to this circular is required.

If additional information regarding this subject is required, contact the Director of this office.

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IEC 80-20 August 21, 1980 S

RECENTLY ISSUED IE CIRCULARS Circular Date of

'No.

Subject Issue Issued to 80-20 Changes in Safe-Slab 8/21/80 All Part 50 and Part Tank Dimensions 70 Fuel Facility e-Licensees 80-19 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 510DU Trip facilities with an Units And Model 1152 Pressure OL or a CP Transmitters 80-15 Losa of Reactor Coolant Pump 6/20/80 All power reactor l

Cooling and Natural Circula-facilities with an tion Cooldown OL or CP 80-14 Radirective Contamination of 6/24/80 All holders of power Plant Demineralized Water and research reactor System and Resultant Internal licenses (operating Contamination of Personnel and construction.

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 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 Envirr" mental Qualification OLs and cps of Eqaipment 80-09_

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

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