ML19338D538
| ML19338D538 | |
| Person / Time | |
|---|---|
| Site: | 07000371 |
| Issue date: | 08/21/1980 |
| From: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Ganley N UNITED NUCLEAR CORP., UNITED NUCLEAR CORP. (SUBS. OF UNC, INC.) |
| References | |
| NUDOCS 8009230416 | |
| Download: ML19338D538 (4) | |
Text
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. UNITED STATES 8
6:
NUCLEAR REGULATORY COMMISSION I
' REGION I 631 PARK AVENUE KING OF PRUSSIA, PENNSYLVANIA 19406 August 21, 1980 Docket No'. 70-371-UNC. Naval PEoducts Division of United Nuclear Corporation.
A UNC RESOURCES Company
' ATTN: Mr. D. E. Ganley.
President and General Manager 67 Sandy Desert Road-Uncasville, Connecticut 06382 Gentlemen:
The enclosed IE Circular No. 80-20, " Changes In Safe-Slab Tank Dimensions," is forwarded to you for information.
No written response is required.
If you desire additional information regarding this matter, please contact this office.
Sincerely, 6%M N.
8 e H. Grier irector
Enclosures:
1.
IE Circular No. 80-20 2.
List of Recently Issued IE Circulars CONTACT:
H. W. Crocker.
(215-337-5217) 8009230416
C SSINS:1 6830 Acc ssion.Na.:
i8006190036
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IEC 80-20 UNITED STATES NUCLEAR REGULATORYLCOMMISSION.
. OFFICE OF INSPECTION.AND ENFORCEMENT % q m q
ri WASHINGTON, D.C.
20555 O
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&&mg 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 l
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 rev.aled that the large faces of two of the tanks had bulged and increased the tt.sckness 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 witn the tank edges and large faces supported and stiffened by 3/16-in. angle fron.
'The cause of the~ bulging was believed to bs overpressurization due to partial plugging of'the' tank vent lines.
Contributing factors'may have been excessive transfer rates,- metal fatigue aggravated by mrrosion, 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 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 tien 1-1/2-in.': vent line to the process offgas (P0G) system at a point irmediately above each tank.
This provided a positive overflow as well as a second vent in' case a plug occurred in the main P0G 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 Lmade with calipers or similar equipment to assure detection of significant
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Edistortion.
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IEC 80-20
' August 21, 1980 Pcge 2 of 2-Notice to Licensees:
All licensees using ' safe-slab tanks should be aware of the possible, changes in tank 1'imensions.resulting from hydraulic ~or pneumatic forces.
Certain steps should be taken to prevent or detect changes.in safe-slab' tank dimensions.
These actions include the following:
(1) _ Structural analyses should be reviewed for all vessels designed.to'be geometrically safe to assure that'the possibility'of pressurization 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 should be provided if pressurization by vent line plugging is possible.
(3) Provision should be made for routine dimensional checks of geometrically safe vessels..These checks should be made whether or not the vessels are subject to pressurization.
No written response to this circular is required.
If additional information regarding this subject is required, contact the Director of this office.
1 r
i AIE Circulcr 80-20 Enc 1csure 2
~
' August 21,_1980-RECENTLYcISSUED IE CIRCULARS Circular Date of No.
Subject Issue Issued to 80-19 Noncompliance with~ License 8/26/80' All. holders of-Requirements for Medical a medical license Licensees 80-18
'10 CFR 50.59 Safety Evalu-8/22/80
.All holders'of ations for Changes to a power reactor
-Radioactive Waste OL or~CP Treatment Systems 80-17 Fuel Pin Damage-Due to Water 7/23/80 All holders of a
' Jet from Baffle _ Plate Corner PWR power reactor OL or CP 80-16
. Operational Deficiencies In 6/27/80 All holders of a Rosemount Model~51000 Trip power reactor Units and Model 1152 Pressure OL or CP Transmitters 80-15 Loss of Reactor Coolant Pump 6/20/80 All holders of a Cooling and Natural Circulation power reactor Cooldown OL or CP 80-14 Radioactive Contamination of 6/24/80 All holders of a Plant Demineralized Water power or research System and Resultant Internal reactor OL or CP, Contamination of Personnel and fuel cycle licensees 80-13 Grid Strap Damage in 5/18/80-All holders of a Westinghouse Fuel Assemblies power reactor OL or.CP 80-12 Valve-Snaft-To-Actuator Key 5/14/80 All holders of May Fall'Out of Place When a power reactor Mounted Below Horizontal Axis OL or CP 80-11:
Emergency Diesel Generator 5/13/80 All' holders of a Lube Oil Cooler Failures power reactor OL or CP 80-10 Failure to Maintain 4/29/80 All holders of a Environmental Qualification-power reactor of Equipment OL or CP 80-09 Problems With Plant Internal 4/28/80
'All holders of a Communications Systems power reactor OL or CP 80 BWR' Technical Specification 4/18/80 All holders of a Inconsistency - RPS Response-Genera 1LElectric Time.
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