ML20101K601

Proposed TS Figure 3.1.1-1 Re Change to Moderator Temp Coefficient

ML20101K601
Person / Time
Site:	Calvert Cliffs
Issue date:	03/28/1996
From:	BALTIMORE GAS & ELECTRIC CO.
To:
Shared Package
ML20101K595	List: ML20101K591 ML20101K601
References
NUDOCS 9604020439
Download: ML20101K601 (6)

Text

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ATTACHMENT (1)

DETERMINATION OF SIGNIFICANT HAZARDS ne proposed change has been evaluated against the standards in 10 CFR 50.92 and has been determined to not involve a significant hazards consideration, in that operation of the facility in accordance with the proposed amendments:

1. Would not involve a significant increase in the probability or consequences of an accident previously evaluated.

The safety analyses for the current fuel cycles assume 500 tubes per steam generator (SG) are plugged and the maximum beginning-of-cycle moderator temperature coefficient (MTC) is assumed to follow the curve in Technical Specification Figure 3.1.1-1. For the fuel cycle to be iristalled in Unit 1 in spring 1996, Baltimore Gas and Electric Company (BGE) assumes in the analyses that more SG tubes are plugged than the current limit, and it is necessary to credit a more restrictive (less positive) limit on the maximum positive MTC to mitigate the Reactor Coolant System pressure and temperature increase analyzed for these events. Herefore, we are proposing a change to the allowable positive MTC limits shown on Technical Specification Figure 3.1.1-1.

The proposed limit will be more restrictive than the existing limit to match the analytical assumptions. Since the safety analyses supporting an increase in the number of plugged SG tubes are applicable to both Units 1 and 2, BGE is requesting this change for both Units.

The proposed change makes the limit on the maximum positive MTC more restrictive. From an operational standpoint, a more restrictive limit on MTC will help mitigate the effect of plant transients on control of plant parameters (e.g., reactor power, pressurizer pressure, pressurizer level, etc.). Herefore, the probability of a previously analyzed accident will not be significantly '

increased The reason for the proposed change is to mitigate the effect (increased reactor coolant temperatures) of increased SG U-tube plugging on the results of the affected safety analyses.

Using the more restrictive limit on the maximum positive MTC, the Loss cf Load, Loss of ,

Feedwater Flow, Feed Line Break, and Control Element Assembly Withdrawal events were reanalyzed using previously accepted methodologies. The results of these cralyses are within the acceptance limits for these events. Therefore, the consequences of a prcoously analyzed accident will not be significantly increased.

The proposed change is similar to the c:_mples of amendments that are considered not likely to involve significant hazards considerations given in the Statements of Consideration for 10 CFR 50.92 (51 FR 7744). He example ofinterest is, "A change that constitutes an additional limitation, restriction, or control not presently included in the technical specifications, e.g., a more stnngent surveillance requirement." He proposed change provides a more restrictive limit on the positive MTC given in Technical Specification Figure 3.1.1-1. Based on the above arguments and the similarity to an example in the Federal Register, BGE has determined that the proposed change does not involve a significant increase in the probability or consequences of an accident previously evaluated.

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ATTACHMENT (1) i DETERMINATION OF SIGNIFICANT HAZARDS Il I lil I IllI

2. Would not create the possibility of a new or dferent type of accident from any accident previously evaluated.

The proposed change makes the limit on the maximum positive MTC more restrictive. The proposed change does not involve installation of new or different equipment, modify the interfaces with edsting equipment, change the equipment's function, or change the method of operating the equipment. The proposed change does not affect normal plant operations or configurations. He more restrictive MTC limit will help mitigate the effect of plant transients on control of plant parameters.

Therefore, the proposed change does not create the possibility of a new or different type of accident from any accident previously evaluated.

3. Would not involve a signifcant reduction in a margin ofsafety.

He proposed change provides for a more restrictive limit for the allowable positive MTC. The more restrictive limit on the maximum positive MTC was evaluated using presiously approved methodologies and compared to the existing acceptance criteria. The analyses show that the proposed change preserves the margin of safety by ensuring that the results of the safety analyses for the Loss of Load, Loss of Feedwat.:r Flow, Feed Line Break, and Control Element Assembly Withdrawal events meet cstablished NRC acceptance limits for these events.

In addition, this proposed change is similar to the examples of amendments that are considered not likely to involve significant hazards considerations given in the Statements of Consideration for 10 CFR 50.92 (51 FR 7744). The example ofinterest is, "A change that constitutes an additional limitation, restriction, or control not presently included in the technical specifications, e.g., a more stnngent surveillance requirement." The proposed change provides a more restrictive limit on the positive MTC given in Technical Specification Figure 3.1.1-1. Based on the above arguments and the similarity to an example in the Federal Register, BGE has determined that the proposed change does not involve a significant reduction in the margin of safety.

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ATTACHMENT (2) 1 UNIT 1 MARKED-UP TECHNICAL SPECIFICATION PAGE 3/41-7 1

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