ML20235P427
| ML20235P427 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 07/13/1987 |
| From: | Bailey J GEORGIA POWER CO., SOUTHERN COMPANY SERVICES, INC. |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| GN-1382, NUDOCS 8707200484 | |
| Download: ML20235P427 (9) | |
Text
Georgia Fowzr Company l
- Post Office Box 282 l
Waynesboro, Georgia 30830 Telephone 404 554-9961 404 724 8114 Southern Company Services, Inc.
l.
Post Office Box 2625 b
l Birmingham, Alabama 35202 l
Telephone 205 870 6011 VOgtie Project July 13, 1987 l
United States Nuclear Regulatory Commission Document Control Desk File:
X7BC35 l
Washington, D. C.
Log:
GN-1382 NRC DOCUMENT NUMBERS 50-424 AND 50-425 l
OPERATING LICENSE NPF-68 1
CONSTRUCTION PERMIT NUMBER CPPR-109 V0GTLE ELECTRIC GENERATING PLANT UNITS 1 AND 2 DIESEL FUEL OIL STORAGE TANKS C0ATING Gentlemen:
i The Operating License dated March 16, 1987, had a licensing condition concerning the above subject. The licensing condition stated:
" Prior to restart following the first refueling, GPC shall (1) replace the zinc coating in the diesel generator fuel oil storage tanks with a coating which does not contain zinc or (2) by March 1,1988, provide an acceptable justification to. the staff that the present fuel oil storage tank zinc-based coating will not affect the operability and reliability of the diesel generators over the life of the plant as specified in:IE Circular 77-15."
The technical considerations related to the VEGP license condition with regard to the inorganic zine coating of the Vogtle diesel fuel oil storage tanks have been thoroughly reviewed.
Enclosed is a report that addresses those technical issues' and sets forth conclusions that there is an important benefit from the tank coating by substantially extending the life of the diesel fuel oil storage tanks and at the same time will be compatible with the type of diesel fuel oil used at Vogtle.
The low acidity and high quality of the diesel fuel oil received and in storage at the Vogtle site have been confirmed by multiple tests.
Results are included in the enclosed report.
This review has confirmed that there is a substantial advantage to having the inorganic zinc coating on the Vogtle Units 1 ano 2 diesel fuel oil storage tanks.
Thus, we are hopeful that this information will be adequate to resolve the technical -issues related to the associated license condition and to permit NRC acceptance of the inorganic zinc coating of the VEGP Units 1 and 2 storage 8707200484 070713 PDR ADDCK 0500 4
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Diesel Fuel Oil Storage Tanks Coating i
File:
X7BC35 Log:
GN-1382 I
Page two i
I tanks with the continued use of the existing technical specification provisions that limit fuel oil neutralization number to not more than 0.2 and mercaptan content to not more than 0.01%.
1 Should you have any questions, please inquire.
Sincerely, l
k-J. A. Bailey Project Licensing Manager i
JAB /wk1 Enclosure j
xc: NRC Regional Administrator NRC Resident Inspector J. P. O'Reilly R. E. Conway L. T. Gucwa R. A. Thomas J. E. Joiner, Esquire M. A. Miller (2)
G. Bockhold, Jr.
j R. Goddard, Esquire D. Feig R. W. McManus Vogtle Project File l
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VEGP DIESEL FUEL OIL STORAGE TANKS j
INORGANIC ZINC COATING STATEMENT OF THE PROBLEM The diesel fuel oil storage tanks at units 1 and 2 of the VEGP are internally coated with an inorganic zinc coating. Based upon incomplete information in regard to issues identified in I. E. Circular 77-15, the NRC included a condition in the VEGP unit 1 operating license that GPC either remove the inorganic zine coating prior to start-up of the unit following the first refueling, or justify the acceptability of the inorganic zine coating.
It is GPC's intent, through this submittal, to justify the operational acceptability of the inorganic zine coating, and to explain that the inorganic zine coating provides an important benefit of adding corrosion control for and extending the life of the diesel fuel oil storage tanks at VEGP.
TANK CORROSION CONTROL The diesel fuel oil storage tanks at the VEGP are internally coated with Ameron's Dimetcote #6 inorganic zinc coating. This coating is applied to the entire interior surface of each tank and will protect the tank from internal corrosion in the vapor region of the tank above the liquid fuel level, and in the sump area where water will collect. The majority of the tank interior surface, which is always immersed in diesel fuel, will see very little corrosion.
In the vapor region of the tank, the inorganic zinc coating is estimated to provide 10 to 15 years of complete corrosion protection, after which small areas of corrosion are likely to start to develop. Thereafter, corrosion of the steel substrate would be a gradual process. Water vapor condensing on the roof of the tank and any water carried in with new loads of fuel will collect in the sump of the tank.
The coating life and subsequent corrosion rate of the steel in the sump area will depend on how well water is kept out of the tank (see paragraph on water removal).
The coating in the sump area is l
estimated to provide 5 to 10 years of complete corrosion protection. The l
estimated life of the inorganic zinc coatings assumes that the coating is subjected to direct contact with water and water vapor.
l Thus, the inorganic zine coating is estimated to add from 5 to 15 years of l
corrosion-free life to the tanks and reduce the corrosion rate of the steel l
substrate from thereon for an additional 5 to 15 years. By postponing and j
reducing the corrosion, the inorganic zine coating will extend the useful life I
of the tanks and reduce the production of corrosion products and particulate l
contamination of the fuel. Therefore, it is concluded that the inorganic zine I
coating is a positive design feature of the tanks with respect to tank life, l
corrosion control and the control of particulate contamination.
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t EFFECTS ON FUEL QUALITY l
I. E. Circular 77-15 discusses an occurrence at the Cooper Station where the I
diesel engine performance was degraded due to a partially clogged str&iner in l
a float-operated shutoff valve which apparently was not known to exist by the l
Cooper plant staff and thus had not been cleaned periodically or monitored.
This occurrence wao not due to the presence of inorganic zine coatings (the Cooper tanks are not coated internally). In addition to the described occurrence, the circular provided information regarding diesel fuel quality, 1
in particular, that the presence of zinc may tend to form soluble soaps which may be deposited on the engine injection nozzles, and may affect engine performance. Theoretically, two types of reactions might occur to a very limited extent, in the first, it is postulated that zine reacts with water to form a zine hydroxide gel. In the second, it is postulated that zine reacts j
with napthenic acids to the extent present in the fuel to form zinc j
napthenate, that may remain soluble in the fuel. However, it is not expected that these theoretical effects will be of any significance in the actual VEGP diesel fuel oil systems, or will affect the operability of the diesel generators for the types of diesel fuel oil used at VEGP, and for which the amount of water in the tanks is controlled such as to be at a very low level.
l Transamerica DeLaval (TDI), the engine manufacturer, was contacted and they I
only specify the use of No. 2 diesel fuel oil.
Ameron, the coating J
manufacturer, has stated that their coating can be used with diesel fuel as long as the neutralization number is no greater than 0.4 and the mercaptan content is no greater than 0.01%.
l Therefore, based on these sources, it is concluded that it is acceptable to I
store diesel fuel in the VEGP inorganic zine-lined tanks and that proper l
attention needs to be given to assuring fuel quality (control of the neutralization number, mercaptan content, and water removal).
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l GPC ACTIONS TO ASSURE FUEL QUALITY j
Af ter discussions with the NRC in January 1987, the following program was l
included in the VEGP Technical Specifications which allowed GPC to retain the tank coatings and required GPC to analyze the diesel fuel for neutralization number and mercaptan content:
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" f. At least once per 92 days and from new fuel prior to addition to the i
storage tank obtain a sample and verify that the neutralization number is less than 0.2 and the mercaptan content is less than 0.01% #,##.
- Mercaptan content shall not be required to be verified within specification for new fuel prior to its addition, for up to 15,000
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gallons of fuel added to the tank, if the last tank sample had a j
mercaptan content of less than 0.007%. All subsequent new fuel addition will require mercaptan content verification prior to its i
addition until the tank contents are verified to be less than 0.007%.
- Neutralization number will not have to be verified less than 0.2, for new fuel prior to its addition, until 60 days after license issuance.
Until that time verification of new fuel specifications will be completed within 30 days of addition."
This program is implemented through procedures 00261-C, 13145-1, 14980-1 and 30080-C. Major areas of the program include procurement, receiving, I
inventory, testing and water removal.
1.
Controlling Neutralization Number and Mercaptan Content l
Laboratory analyses of neutralization number and mercaptan content was done l
off-site by an independent laboratory prior to February 20, 1987, and is now done on-site by GPC lab technicians. The procedures for testing the f
neutralization number and the mercaptan content follow ASTM standards and l
utilize potentiometric titrations. Testing of the diesel fuel oil in storage began in August 1986, and testing of individual shipments began in January I
1987. It was found that the diesel fuel oil in use in the vicinity of the
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i VEGP could be expected to have a neutralization number of about 0.1 or less I
with very low amounts of mercaptan. The data in Table I was obtained by an I
independent lab and by GPC lab technicians, with the results being reasonable and consistent.
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I TABLE 1 VEGP DIESEL FUEL OIL TESTING RESULTS DIESEL FUEL IN STORAGE Date Tank Neutralization #_
Mercaptan, %
08/14/86 A
0.07 0.0004 08/14/86 B
0.09 0.0002 11/20/86 A
0.08
< 0.0002 11/20/86 B
0.10
< 0.0002 02/20/87 A
0.10 0.0004 02/20/87 8
0.10 0.0006 04/20/87 A
0.07 0.0008 04/20/87 B
0.08 0.0005 06/20/87 A
0.06 0.0008 06/20/87 B
0.07 0.0011 INDIVIDUAL FUEL SHIPMENTS Date Neutralization #
Mercaptan, %
01/12/87 0.08 0.0014 i
01/13/87 0.06 0.0011 01/15/87 0.08 0.0015 04/17/87 0.03 Note 2 l
Notes:
- 1. Two shipments were received on 1/14/87, but the samples were unacceptable for testing when received at the off-site lab, so no 1
l data are available.
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- 2. Analysis of mercaptan not required by the Technical Specifications.
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1 2.
Operational Procedures The VEGP Technical Specifications require sampling of the fuel oil stored in the storage tanks at least once every 31 days to verify that the particulate contamination is less than 10 mg/ liter. Operations procedures 11885-C, 13145-1 and 14980-1 require logging the differential pressure across the duplex fuel j
oil filters (which allows the operator to switch from one filter element to i
the other without interrupting the fuel oil flow) during the monthly testing
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of the diesels; and notifying the shift supervisor when values exceed desired i
limits. In addition, at anytime during diesel generator operation a high differential pressure across the duplex fuel oil filter would be annunciated l
locally and in the control room.
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As part of the TDI Owners Group DR/QR, " pop" tests are performed on the fuel injectors every 18 months.
The pop test is performed to check the spray i
pattern from the fuel injector, the pressure at which the injector opens and to ensure that it seals tightly after closing. As part of this test, all injectors are disassembled, cleaned, inspected, and damaged or worn parts replaced.
I The above described procedures and tests are considered to be adequate to l
l provide an indication of potential declining fuel quality well in advance of l
impacting diesel operation.
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I 3.
Water Removal
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The VEGP Technical Specifications require that water be checked for and l
l removed from the storage tanks at least once every 31 days.
Since the l
l Technical Specifications also require the tanks to be kept relatively full, i
the volume of the vapor region is small, and the amount of condensation is minimized. This conclusion can be substantiated by the results of the water removal activities, summarized in Table 2, which also shows that GPC has kept the water content in the tanks to a very low level.
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TABLE 2 l
WATER TESTING RESULTS FROM VEGP UNIT 1 DIEEEL FUEL OIL STORAGE TANKS Date Tank Water I
f 12/20/86 A
none l
12/20/86 B
none l
12/30/86 B
none l
01/19/87 A
trace 01/19/87 B
none 02/19/87 A
none l
02/19/87 B
none 1
03/22/87 A
none 03/22/87 B
trace 04/21/87 A
none 04/21/87 B
none i
l 05/22/87 A
none 1
05/22/87 B
none 1
06/20/87 A
none 06/20/87 B
none l
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CONCLUSIONS The mechanisms which are hypothesized for potential effects on diesel fuel quality when stored in tanks lined with inorganic zine are caused by water in
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the tank and by procurement of fuel with a high neutralization number j
(acidity). GPC has taken the necessary action to:
1.
obtain data to verify that the acidity and mercaptan content of the VEGP fuel is low.
2.
remove and control water in the diesel fuel oil storage tanks.
In addition, GPC has done the following to ensure fuel quality and proper engine operation:
1.
monitor and control particulate contamination 2.
monitor pressure drop across fuel filters
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provide duplex fuel oil filters 4.
perform pop tests on the fuel injectors l
This comprehensive program will provide adequate assurance that the fuel in l
the VEGP diesel fuel oil storage tanks will be acceptable to operate the standby diesel generators. Therefore, it is GPC's conclusion that the l
existing inorganic zine coating applied to the VEGP diesel fuel oil storage tanks is preferable for use, compatible with the diesel fuel being used at VEGP, will extend the life of the tanks by 5 to 15 years, will reduce the corrosion rate of the tank for an additional 5 to 15 years, and will reduce the quantity of particulate contamination within the tanks. Thus the coating should be left in place for the unit 1 & 2 diesel fuel oil storage tanks.-
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