ML18082B021

Submits Response to NRC Concerns Re Effects of Dissolved Solids Other than Sodium Chloride on Steam Generators as Source of Auxiliary Feedwater

ML18082B021
Person / Time
Site:	Salem
Issue date:	09/03/1980
From:	Mittl R Public Service Enterprise Group
To:	Schwencer A Office of Nuclear Reactor Regulation
References
NUDOCS 8009050332
Download: ML18082B021 (4)

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Public Service Electric and Gas Company 80 Park Plaza Newark, N.J. 07101 Phone 201/430-7000 September 3, 1980 Director of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C.

20555 Attention:

Mr. A. Schwencer, Acting Chief Licensing Branch 3

.Div.is.ion of Li.censing Gentlemen:

ADDITIONAL INFORMATION USE OF SALT WATER IN STEAM GENERATORS NO. 2 UNIT SALEM NUCLEAR GENERATING STATION DOCKET NO. 50-311 PSE&G hereby submits, in the enclosure to this letter, its response to your concerns regarding the effects of dissolved solids other than sodium chloride on the steam generators when using service water as a source of auxiliary feedwater.

Should you have any questions, do not hesitate to contact us.

Encl.

CC:

Mr. L. Norrholm Salem Resident Inspector M P80 75 11 The Energy People Very truly yours, f-!f!f;t/

R. L. Mittl General Manager -

Licensing and Environment Engineering and Construction 8 0090 50 :s 3~.

f 95-0942

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r EV.UATION OF USE OF SALT WATa_....

• rN STEAM GENERATORS NO. 2 UNIT SALEM NUCLEAR GENERAT'ING STAT~~~-j

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Further to tne discussion submitted on July 1, 1980, concerning the potential effects of using salt water as the source of long-tenn auxiliary feedwater at the Salem plants, the following infonnatiori provides additional data on the behavior of concentrating bfine solutions under ~team generator "no load" conditions.

A guide to the behavior of sea water constituents other than sodium chloride

_. can* be found in studies addressing the operation of desalination equipment *

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.... *~~ - This type.of equipment is operated at temperatures and pressures lower than those experienced in an off-load PWR steam generator, but heat. transfer fouling effects *ar~ essentially similar for these two types of boiler.

At elevated tempe.ratures, the acid forming auto-hydrolysis of sea water prevents the precipitation of carbonate species from the bulk solution. Thus, the first salt to be precipitated from a concentrating.sea water solution at high tem-perature will be calciu!TI sulphate. See References l and 2.

Reference l indicates that calcium sulphate precipitation begins when a sea water concentration factor greater than 3 is attained. Reference 2 indicates that the precipitation of sulphate species continues through the sodium chloride precipi-tation phase, but is complete prior. to the precipitation of species such as MgC12, MgS04, NaBr, and KCl.

Verification of this precipitation sequence can aiso be found in tables of solubility data - such as Reference 3. These tables also show that the only major sea water precipitant exhibiting retrograde solubility characteristics is calcium sulphate. Thus, further discussion of species likely to be precipitated from sea water within the* steam generator, under the conditions postulated for a loss of offsite power 1ncid~nt, may, properly, be limited to a consideration of the case of calcium sulphate.

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For the purposes of the previously submitted discussion, it was assumed that the "conservative case" use of the Auxiliary Feedwa ter System would be when the Delaware river contained a sea water chemistry represented by ASTM Specification 01141.

Using this specification, and assuming that all c:f the sulphate present in the sea water will be precipitated as calcium sulphate, there will be 3.557g CaS04/liter of sea *water available for precipitation as rhombic anhydrite crystals. Using parameters generated during the previous discussion converts this calcium sulphate concentration to a total mass of 5~143 x 106 grams of Caso4 contained in 3 steam generators by the time that the RHR system is in operation.

Reference 1 sryows that calcium sulphate precipitation results *in crystal growth on ali wetted surfaces.

For the purposes of conservatis~, we have chosen to neglect the effect of precipitation on carbon steel surfaces within the steam generators,. and will assume that precipitation takes place only on the tube wall surfaces of the 3 available steam generators.

In addition, it is assumed that no calcium sulphate remains in solution. This,, again, provides additional con-servatism, since Reference 2 establishes that up to 20% of the available calcium sulphate content of sea water is still in solution at the onset of sodium chloride precipitation. Based upon these assumptions, and using a nominal tube surface area of 51,000 ft. 2/SG, the precipitation of all of the calcium sulphate onto the available tube surface would produce a layer of crystals 0.0048 11 thick. This

'prscipitation would begin approximately 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after a loss of offsite power incident, with decay heat removat requiring a water supply of about 8,000 gallons/hour (133~3 gpm).

Based upon the referenced decay heat removal requirements, it is reasonable to assume that the 0.005 11 layer of calcium sulphate will be precipitated

~t a linear rate throughout the time period under consideration. This being the case, a Caso4 build-up rate of 0.00020 to 0.00021 inches per hour can be anticipated.

No adverse effects on overall heat removal capability woul:d be anticipated by the accumulation of a layer of calcium sulphate under the conditions described in this discussion.

In addition, the margins established in the previously submitted dis-cussion, based upon recorded versus assumed*salt contents of the Delaware river, are applicable to the calculation outlined in this discussion *

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REFERENCES

1. Desalination Vol. 16, June 1975.

A. E. Austin et. al.

Battelle, Columbus Lab., Ohio

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Evaporation of Seawater Borchert Academic Press Inc., 1965

3.

CRC Handbook of Chemistry and Physics

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