ML20132C653

Proposed Tech Specs,Sections 2.1.A Re SLMCPR & 3.11.C Re Olmcpr.Changes Revise SLMCPR Values & Deletes Sentence Re OLMCPR Limit Penalty for Single Recirculation Loop Operation

ML20132C653
Person / Time
Site:	Monticello
Issue date:	11/25/1996
From:	NORTHERN STATES POWER CO.
To:
Shared Package
ML20132C629	List: ML20132C623 ML20132C636 ML20132C653
References
NUDOCS 9612180428
Download: ML20132C653 (8)

Text

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Exhibit B MONTICELLO NUCLEAR GENERATING PLANT License Amendment Reauest Dated November 25.1996 Proposed Changes Marked Up on Existing Technical Specification Pages

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2.0 SAFETY LIMITS LIMITING SAFETY SYSTEM SETTINGS 2.1 FUEL CLADDING INTEGRITY 2.3 FUEL CLADDING INTEGRITY Aeolicability Aeolicability Applies to the interrelated variables associated Applies to trip settings of the instruments and with fuel thermal behavior devices which are provided to prevent the reactor system safety limits from being exceeded.

Obiective:

Obiective:

To define the level of the process variables at To establish limits below which the integrity which automatic protective action is initiated to of the fuel cladding is preserved. prevent the safety limits from being exceeded.

Specification:

Specification: The Limiting safety system settings shall be as specified below:

A. Core Thermal Power Limit (Reactor Pressure >800 psia and Core Flow is >10% of Rated) A. Neutron Flux Scram When the reactor pressure is >800 psia and core 1. APR1 - The APRM flux scram trip setting flow is >10% of rated, the existence of a shall be:

minimum critical power ratio (MCPR) less than a. For two recirculation loop operation

[.O 1.^;7 for two recirculation loop operation, or (TLO):

less tly M or single loop operation, shall S $ 0.66W + 70% where, constitute violation of the fuel cladding S - Setting in percent of rated integrity safety limit. thermal power, rated power being 1670 MWT W - Percent of the drive flow required to produce a rated core flow of 57.6 x 106 lb/hr

b. For single recirculation loop operation (SLO):

S $ 0.58(W - 5.4) + 62%

c. No greater than 120%.

2.1/2.3 6

REV 134 1/27/93

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Bases:

2.1 The fuel cladding integrity limit is set such that no calculated fuel damage wot ld occur as a result of an abnormal operational transient. Because fuel damage is not directly obsel vable, a step-back approach is used to establish a Safety Limit such that the MCPR is no less thanl'i-97. This limit represents a conservative margin relative to the conditions required to maintain fuel cladding integrity. The fuel cladding is one of the physical barriers which separate radioactive materials from the environs. The integrity cZ this cladding barrier is related to its relative freedom fron perforations or cracking. Although some corrosion or use related cracking may occur during the life '

of the cladding, fission product migration from this source is incrementally cumulative and continuously measurable. Fuel cladding perforations, however, can result from thermal stresses which occur from reactor operation significantly above design conditions and the protection systems safety settings.

While fission product migration from cladding perforation is just as measurable as that from use related cracking, the thermally caused cladding perforations signal a threshold, beyond which still greater thermal stresses may cause gross rather than incremental cladding deterioraticm. Therefore, the fuel cladding Safety . Limit is defined with margin to the conditions which would produce onset of  :

transition boiling. (MCPR of 1.0). These conditions represent a significant departure from the i condition intended by design for planned operation. The concept of MCPR, as used in the CETAB/GEKL critical power analyses, is discussed in Reference 1. i A. Core Ther==1 Power Yf=ft (Reactor Pressure) > 800 nsia and Core Flow > 10% of Rated.) Onset of transition boiling results in a decrease in heat transfer from the clad and, therefore, elevated ,

clad temperature and the possibility of clad failure. However, the existence of critical power, or boiling transition, is not a directly observable parameter in an operating reactor. Therefore, i the margin to boiling transition is calculated from plant operating parameters nuch as core power, core flow, feedwater temperature, and core power distribution. The margin for each fuel assembly is characterized by the critical power ratio (CPR) which is the ratio of the bundle power which would produce onset of transition boiling divided by the actual bundle power. The '

minimum value of this ratio for any bundle in the core is the minimum critical power ratio (MCPR). It is assumed that the plant operation is controlled to the nominal protective setpoints via the instrumented variables. The Safety Limit (T.S.2.1.A) has sufficient conservatism to assure that in the event of an abnormal operational transient initiated from the Operating MCPR Limit (T.S.3.11.C) more than 99.9% of the fuel rods in the core are expected to avoid boiling

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transition. The margin between MCPR of 1.0 (onset of transition boiling) and the Safety Limit i

2.1 Bases 10 i!

REV 52 1/9/81 I l

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_ & C?A OftnT 3.0 LIMITING CO TIONS FOR OPERATION 4.0 SURVEILIANCE REQUIREMENTS C. MinimumO[iticalPowerRatio(MCPR) C. Minimum Critical Power Ratio (MCPR)

All

' 'Phe- hall be greater than or equal to' MCPR shall be determined daily the imi provided in the Core Operating during reactor power operation at Limits Report. >25% rated thermal power and Tollowing any change in power level eO PR 1 mit r one - rculat o o or distribution which has the

ope tion is I highe than the e arable potential of bringing the core to g\ loop va e its operating MCPR Limit.

If at any time during operation it is determined  ;

that the limiting value for MCPR is being exceeded, action shall be initiated within 15 minutes to restore operation to within the prescribed limits. Surveillance and corresponding action shall continue until reactor operation is i within the prescribed limits. If the steady state '

MCPR is not returned to within the prescribed limits within two hours, reduce thermal power to less than 25% within the next four hours.

l The next page is 216 3.11/4.11 213 REV 120 9/28/89

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. 1 Exhibit C i MONTICELLO NUCLEAR GENERATING PLANT  !.

License Amendment Reauest Dated November 25.1996 t t

Revised Monticello Technical Specification Pages ,

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2.0 SAFETY LIMITS LIMITING SAFETY SYSTEM SETTINGS

• 2.1 FUEL CIADDING INTEGRITY 2.3 FUEL CIADDING INTERGRITY I

Anolicability Anolicability -

1 Applies to the interrelated variables associated Applies to trip settings of the instruments and l with fuel thermal behavior. devices which are provided to prevent the reactor r system safety limits from being exceeded. [

Obiective: Obiective:  ;

To establish limits below which the integrity To define the level of the process variables at  ;

of the fuel cladding is preserved. which automatic protective action is initiated to  ;

prevent the safety limits from being exceeded.

Snecification: Specification: l A. Core Thermal Power Limit (Reactor Pressure >800 The Limiting safety system settings shall be as '

psia and Core Flow is >10% of Rated) specified below: 1 When the reactor pressure is >800 psia and core A. Neutron Flux Scram.  !

flow is >10% of rated, the existence of a 1. APRM - The APRM flux scram trip setting -

minimum critical power ratio (MCPR) less than shall be:

1.08, for two recirculation loop operation, or a. For two recirculation loop operation less than 1.09 for single loop operation, shall (TID): i constitute violation of the fuel cladding S $ 0.66W + 70%

i integrity safety limit. where S - Setting in percent of rated thermal power, rated power ,

being 1670 MWT I W - Percent of the drive flow  !

required to produce a rated i i

core flow of 57.6 x 10' lb/hr

b. For single recirculation loop operation i (SID): .

SS 0.58(W - 5.4) + 62%  ;

c. No greater than 1204. -

2.1/2.3 6 i REV i

1 Beses: ,

2.1 The fuel cladding integrity limit is set such that no calculated fuel damage would occur as a result of an abnormal operational transient. Because fuel damage is not directly observable, a step-back approach is used to establish a Safety Limit such that the MCPR is no less than the values specified in Technical Specification 2.1.A. This limit represents a conservative margin relative to the conditions required to maintain fuel cladding integrity. The fuel cladding is one of the physical barriers which separate radioactive materials from the environs. The integrity of this cladding barrier is related to its relative freedom from perforations or cracking. Although some corrosion or use related cracking may occur during the life of the cladding, fission product migration from this source is incrementally cumulative and continuously measurable. Fuel cladding perforations, however, can result from thermal stresses which occur from reactor operation significantly above design conditions and the protection systems safety settings. While fission product migration from cladding perforation is just as measurable as that from use related cracking, the thermally caused cladding perforations signal a threshold, beyond which still greater thermal stresses may cause gross rather than incremental cladding deterioration. Therefore, the fuel cladding Safety Limit is defined with margin to the conditions which would produce onset of transition boiling. (MCPR of 1.0). These conditions represent a significant departure from the condition intended by design for planned operation. The concept of MCPR. as used in the GETAB/GEXL critical power analyses, is discussed in Reference 1.

A. Core Thermal Power Limit (Reactor Pressure) > 800 osia and Core Flow > 10% of Rated.) Onset of transition boiling results in a decrease in heat transfer from the clad and, therefore, elevated clad temperature and the possibility of clad failure. However, the existence of critical power, or boiling transition, is not a directly observable parameter in an operating reactor. Therefore, the margin to boiling transition is calculated from plant operating parameters such as core power, core flow, feedwater temperature, and core power distribution. The margin for each fuel assembly is characterized by the critical power ratio (CPR) which is the ratio of the bundle power which would produce onset of transition boiling divided by the actual bundle power. The minimum value of this ratio for any bundle in the core is the minimum critical power ratio (MCPR). It is assumed that the plant operation is controlled to the nominal protective setpoints via the instrumented variables. The Safety Limit (T.S.2.1. A) has sufficient conservatism to assure that in the event of an abnormal operational transient initiated from the Operating MCPR Limit (T.S.3.ll.C) more than 99.9% of the fuel rods in the core are expected to avoid boiling transition. The margin between MCPR of 1.0 (onset of transition boiling) and the Safety Limit 2.1 Bases 10 REV c - - . - _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ - _ _ _ _ _ _ _ - _________.__ __-- _

3.0 LIMITING COh0ITIONS FOR OPERATION 4.0 SURVEILIANCE REQUIREMENTS ,

C. Minimum Critical Power Ratio (MCPR) C. Minimum Critical Power Ratio (MCPR)

All MCPRs shall be greater than or equal to MCPR shall be determined daily during the MCPR Operating limits provided in the reactor power operation at it25% rated Core Operating Limits Report. thermal power and following any change in I power level or distribution which has the If at any time during operation it is potential of bringing the core to its determined that the limiting value for MCPR operating MCPR Limit.

is being exceeded, action shall be initiated within 15 minutes to restore operation to within the prescribed limits. Surveillance and corresponding action shall continue until reactor operation is within the prescribed limits. If the steady state MCPR is not returned to within the prescribed limits within two hours, reduce thermal power to less than 25% within the next four hours.

The next page is 216 213 3.11/4.11 REV

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