ML20077N184

Proposed Tech Specs Re Max Allowable Linear Heat Rate Limits & Borated Water Storage Shutdown Margin Bases

ML20077N184
Person / Time
Site:	Three Mile Island
Issue date:	08/09/1991
From:	GENERAL PUBLIC UTILITIES CORP.
To:
Shared Package
ML20077N174	List: ML20077N169 ML20077N178 ML20077N184
References
NUDOCS 9108140243
Download: ML20077N184 (3)

Text

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The. quantity of boric acid in storage from_either of the three'above mentioned sources is suffi_cient_to borate the reactor coolant system to a one percent suberitical margin in the cold condition at the worst time in core life with a stuck control rod assembly. Minimum volumes of 906 ft' of 8700 ppm boron as concentrated boric acid solution in the boric acid mix tank.or in a reclaimed boric acid storage tank or 60,000 gallons of 2270 ppm boron as boric acid solution in the borated water ;torage tank will each satisfy this requirement. Technical Specification 3.3 assures that at least

'two of these supplies are available whenever the reactor is critical so that a single _ failure will not prevent boration to a cold condition. The minimum volumes of boric acid tolution given include the boron necessary to account for xenon decay.

The primary method of adding boron to the reactor coolant system is to pump the concentrated boric acid solution (6700 ppm boron, minimum) into the makeup tank using either the 10 gpm boric acid pumps or the 30 gpm reclaimed boric acid pumps. Using only one of the two 10 gpm boric acid pumps, the '

required volume can be injected in less than 13 hours1.50463e-4 days <br />0.00361 hours <br />2.149471e-5 weeks <br />4.9465e-6 months <br />. The alternate method of addition is to inject boric acid from the_ borated water storage tank using the makeup and purification pumps. The 60,000 gallons of boric acid can be injected in less than four hours using only one of the makeup and l purification pumps, Concentration of boron in the boric acid mix tank or a reclaimed boric acid ^

storage tank may be higher than the concentration which would crystallize at ambient conditions. Fer this reason, the boric acid mix tank is provided with an immersion electric heating element and the reclaimed boric acid tanks are provided with low pressure steam heating jackets to maintain the temperature of their contents well above (10*F or more) the crystallization

• temperature of the' boric acid solution contained in them. Both types of heaters are controlled by temperature sensors immersed in the solution contained in the tanks. Further, all piping, pumps and valves associated with the boric acid mix tank and the reclaimed boric acid storage tanks to transport boric acid solution from them to the makeup and purification system are provided with redundant electrical heat tracing to ensure that the boric acid solution will be maintained 10'F or more above its crystallization temperature. The electrical heat tracing is controlled by the temperature of the external surfaces of the piping systems. Once in the makeup and purification system, the boric acid solution is sufficiently well mixed and diluted so that normal system temperatures assure boric acid solubility.

References (1) UFSAR, Section 9.1 " Makeup and Purification System" (2) UFSAR, Section 9.2 " Chemical Addition and Sampling Systems" (3) UFSAR, Figures 6.0-1, 6.0 Simplified ECCS Diagrams l

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