ML19338D506
| ML19338D506 | |
| Person / Time | |
|---|---|
| Site: | Framatome ANP Richland |
| Issue date: | 08/21/1980 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Estey H SIEMENS POWER CORP. (FORMERLY SIEMENS NUCLEAR POWER |
| References | |
| NUDOCS 8009230367 | |
| Download: ML19338D506 (4) | |
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UNITED STATES 8' ' -
NUCLEAR REGULATORY COMMISSION.
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REGION V 1990 N. CALIFORNI A BOULEVARD -
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August 21, ~1930 Docket No. 70-1257' f
Exxon Nuclear Company-2101 Horn Rapids Road Richland,' WA 99352 Attention:.Mr. H.-P.'Estey, Ma' nager, Licensing and Compliance, Operating Facilities 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, (Y$C1>mcSN-I R. H. Engelken Director
Enclosures:
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IE Circular Ho. 80-20 2.
Recently issued IE. Circulars e
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8006190036 IEC 80 UllITED STATES flVCLEAR, REGULATORY COMMISSION OFFICE OF INSPECTION Afl0 ENFORCEMENT T
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20555 de d J 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
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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 51/2 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 stiffener strength, indicated that required dimensions would be maintained. A 4
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 P0G line. ' Additionally, each tank was'provided with a 2" x 4" inspection port at the top with a cover free L
te " 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 distortion.-
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IEC'80-20 August 21, 1980 Page 2 of 2
. Notice to Licensees:
A11' 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 dirensions.
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
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been adequatelyiconsidered. iThe 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.
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IEC 80 August 21, 1980
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RECENTLY ISSUED IE CIRCULARS Circular Date of
~No.
Subject Issue Issued to-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 510D0 Trip facilities with an Units And Model 1152-Pressure OL or a CP Transmit'2rs 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 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-Shaf t-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 Environmental-Qualification
.0Ls and cps of Equipment J80-09.
Problems With Plant. Internal 4/28/80 All. holders of a power Communications-Systems reactor OL or CP s
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