ML20149J025

Tech Spec Change Pages B.3.8-2 & B.3.8-5 to Amend Re Spent Fuel Pool Personnel Access Doors

ML20149J025
Person / Time
Site:	Prairie Island
Issue date:	06/30/1997
From:	NORTHERN STATES POWER CO.
To:
Shared Package
ML20149G295	List: ML20149G293 ML20149J025
References
NUDOCS 9707280012
Download: ML20149J025 (2)

Text

C B.3.8-2 REV 129A 6/30/97 3.8 REFUELING AND FUEL HANDLING Bases continued The Spent Fuel Pool Special Ventilation System (SFPSVS)(Reference 3) is a l j safeguards system which maintains a negative pressure in the spent fuel I enclosure upon detection of high area radiation. The Spent Fuel Pool Normal Ventilation System is automatically isolated and exhaust air is drawn through filter modules containing a roughing filter, particulate filter, and a charcoal filter before discharge to the environment via one  ;

of the Shield Building exhaust stacks. Two completely redundant trains are provided. The exhaust fan and filter of each train are shared with the corresponding train of the Containment In-service Purge System. High efficiency particulate absolute (HEPA) filters are installed before the charcoal adsorbers to prevent clogging of the iodine adsorbers in each SFPSVS filter train. The charcoal adsorbers are installed to reduce the potential release of radioiodine to the environment. Doors to the spent fuel enclosure are required to be maintained closed when SFPSVS OPERABILITY is required. Opening of personnel doors for personnel use is acceptable (blocking a door open is not allowed)(Reference 9).

During movement of irradiated fuel assemblies or control rods, a water level of 23 feet is maintained to provide sufficient shielding.-

The water level may be lowered to the top of the RCCA drive shafts for latching and unlatching. The water level may also be lowered below 20 feet for upper internals removal / replacement. The basis for these j allowance (s) are (1) the refueling cavity pool has sufficient level to -

allow time to initiate repairs or emergency procedures to cool the core, (2) during latching / unlatching and upper internals removal / replace-ment the level is closely monitored because the activity uses this level as a reference point, (3) the time spent at this level is minimal.

The Prairie Island spent fuel storage racks have been analyzed (Reference

8) in accordance with the methodology contained in Reference 5. That methodology ensures that the spent fuel rack multiplication factor, K,gt, is less than 0.95 as recommended by ANSI 57.2-1983 (Reference 6) and NRC guidance (Reference 7). The codes, methods and techniques contained in the methodology are used to satisfy this criterion on K,rg. The resulting Prairie Island spent fuel rack criticality analysis allows for the storage of fuel assemblies with enrichments up to a maximum of 5.0 weight percent U-235 while maintaining K re s 0.95 including uncertainties and credit for soluble boron. In addition, sub-criticality of the pool (K.cz

< 1.0) is assured on a 95/95 basis, without the presence of the soluble boron in the pool. Credit is taken for radioactive decay time of the spent fuel and for the presence of fuel rods containing Gadolinium burnable poison.

The Prairie Island specific criticality analysis (Reference 8) utilized the following storage configurations to ensure that the spent fuel pool will remain suberitical during the storage of fuel assemblies with all possible combinations of burnup and initial enrichment:

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B.3.8-5 REV 129A 6/30/97 3.8 REFUELING AND FUEL HANDLING Rages continued When the concentration of boron in the spent fuel pool is less than required by Specification 3.8.E.2.a. immediate action must be taken to preclude the occurrence of an accident or to mitigate the consequences of an accident in progress. This is most efficiently achieved by immediately suspending the movement of fuel assemblies. The concentration of boron is restored simultaneously with suspending movement of fuel assemblies. The suspension of fuel movement is not intended to preclude movement of a fuel assembly to a safe position.

-References

1. USAR, Section 10.2.1.2

2. USAR, Section 14.5.1

3. USAR, Section 10.3.7

4. " Criticality Analysis of the Prairie Island Units 1 & 2 Fresh and Spent Fuel Racks", Westinghouse Commercial Nuclear Fuel Division, February 1993.

5. WCAP-14416-NP-A, "Westinghoase Spent Fuel Rack Criticality Analysis Methodology", Revision 1, November 1996.

6. American Nuclear Society, "American National Standard Design Requirements.for Light Water Reactor-Fuel Storage Facilities at Nuclear Power Plants", ANSI /ANS-57.2-1983, October 7, 1983.

7. Nuclear Regulatory Commission, Letter to All Power Reactor Licensees from B. K. Grimes, "0T Position for Review and Acceptance of Spent Fuel' Storage and Handling Applications", April 14, 1978.

8. " Northern States. Power Prairie Island Units 1 and 2 Spent Fuel Rack Criticality Analysis Using Soluble Boron Credit", Westinghouse Commercial Nuclear Fuel Divicion, February 1997.

9. Safety Evaluation 50-475, " Spent Fuel Pool Personnel Access Doors."

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