ML20236G511

Proposed Tech Specs,Consisting of Proposed Change 132, Replacing Page 3.10-4 Re Incore Monitoring Sys

ML20236G511
Person / Time
Site:	Maine Yankee
Issue date:	07/30/1987
From:	Maine Yankee
To:
Shared Package
ML20236G499	List: ML20236G494 ML20236G511
References
NUDOCS 8708040290
Download: ML20236G511 (7)

Text

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M Alk5E Y AGdKEE ATOf slC POWER COMPANY r

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l ATTACHMENT B MN-87-87 Proposed Change No. 132 Proposed Technical Specification Changes For Revised LOCA Monitoring Limits when the Incore Monitoring System is Inoperable 8708040290 370730 PDR ADOCK 05000309 P PDR 8667L-HFJ

M6lNE YANKEE ATOMIC POWER COMPANY n .

3. .Incore detector ~ alarms shall be set at least weekly. 1 Alarms will' be based on the latest power distribution obtained, so that-the linear heat rate does not exceed the linear heat rate limit defined p

in Specification 3.10.C.1. If.four or more coincident alarms are

' received, the validity of-the alarms shall be immediately determined and,.if valid, power shall be immediately decreased below the alarm setpoint.

3.1 .If the incore monitoring system becomes inoperable, perform one of the following within 4 effective full power hours: )

1. Initiate a power reduction at a rate of at least 1% per hour ]

to a power level less than or equal to the power level given ]

l. by the following expression for the limiting location: J l

L P - [R-0.5 S]-[LHR (limit)/ .LHR (measured)], where: ]

P - % of rated power, )

R .85 for symmetric offset between ]

0.00 and +0.10, or ]

92 for symmetric offset between -]

0.00 and -0.10, 1 S - Number of steps the CEAs deviates from ]

the CEA position existing when the linear. ]

heat rate measurement was taken, ]

LHR (limit) - Linear heat rate permitted by ]

Specification 3.10.C.1, and LHR (measured) - Linear heat rate 'last measured ]

corrected to 100% power. ]

The CEAs shall be maintained'above the 100% power dependent ]

insertion limit and symmetric offset shall be monitored ]

once per shift to ensure that it remains within the above ]

range. ]

This method may be used for up to 14 effective full power ]

days from the time when the linear heat rate measurement ]

was taken; or ]

2. Comply with the LC0 given in Figure 3.10-2 while maintaining the CEAs above the 100% power insertion limit. If a power reduction is required, reduce power at a rate of at least 1% per hour; or ]

3. Comply with the LC0 in Figure 3.10-3. If a power reduction is required, reduce power at a rate of at least 1% per hour. ]

3.10-4 07/30/87 8667L-HFJ 1

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-4. The azimuthal power tilt, T q, shall be determined prior to operation above 50% of full rated power after each refueling and at least once per day during operation above 50% of full rated power.

Tq is given by the following expression:

T q- 2 (Da-Dc)2 + (Db-Dd)2 (Da+Db + Dc+0d)Z where Di is the signal from excore detector channel 1. If an excore channel is inoperable, Di are the relative quadrant powers determined from the incore system for all quadrants, i.

Tq shall not exceed 0.03.

4.1 If the measured value of Tq is greater than 0.03 but less than or equal to 0.10, or an excore channel is inoperable, assure that the total radial peaking factor (FRT) is within the provisions of Specification 3.10.C.2 once per shift.

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3.10-4a 07/30/87 8667L-HFJ

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l MalNE 'YANCtEE ATOMIC POWER COMPANY. '

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i i ATTACHMENT C  ;

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, 'MN-87-87 Basis'and Justification' l

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for Revised LOCA Monitoring Limits  ;

i When the- ~l 4

Incere Monitoring System is Inoperable :l 1

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i MAINE YANCIEE ATOMIC POWER COMPANY ATTACHMENT C HN-87-87 Basis and 141tification for Revised Monitorina of LOCA Limits When the Incore Monitorina System is Inocerable

SUMMARY

I Maine Yankee currently uses the Incore Monitoring System to monitor the LOCA Linear Heat Generation Rate (LHGR) Limits. If the incore alarms become inoperable, power operation can be continued as allowed by Technical Specification 3.10.C.3.1.1. This specification places limits on CEA position and axial symmetri; offset, and based on these restrictions., penalizes the last incore LHGR measurement for potential power peaking increases and establishes a maximum allowable power level for operation, Operation under this specification during Cycle 10 could restrict the plant output to less than full power. This attachment documents the basis and justification for an alternative specification which provides the same assurance of operation within the LOCA LHGR limits.

DISCUSSIQN The current Technical Specification 3.10.C.3.1.1 allows continued power operation for'up to two weeks after the Incore Monitoring System becomes inoperable. The following conditions must be met:

o CEAs are maintained above the 100% power insertion limit.

o Excore symmetric offset remains within 0.05 of the value measured when the last incore readings were taken.

o Core power is reduced to less than or equal to P (% of rated power),

where P is given by:

P = 0.85 x R, where R is the minimum ratio of (Linear Heat Rate Permitted by Specification 3.10.C.1 x 1QQ1__

(Latest Measured Peak Linear Heat Rate Corrected to 100% Power)

The intent of this specification is to permit continued operation based on the latest measured LOCA LHGR margin to limits. The penalty factor of 0.85 acccants for the maximum possible loss in margin due to peaking increase that could result from operation within the restricted CEA and symmetric offset limits. The flyspeck analysis used in the determination of the Reactor Protection System setpoints forms the basis of this penalty factor, which is evaluated each cycle. Therefore, the equation ensures that operation within the LOCA LHGR limits is maintained.

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MAINE YANKEE ATOMIC POWER COMPANY The proposed specification separates this combined penalty factor into CEA and symmetric offset components and expresses the penalty as a function of CEA movement relative to the CEA position at the time of the measurement. In addition, the proposed specification defines two symmetric offset ranges to cover the most likely conditions of core operation. The proposed specification requires that the following conditions be met:

o CEAs are maintained above the 100% power insertion limit.

o Excore symmetric offset is between 0.00 and 10.10.

o Core power is reduced to less than or equal to P (% of rated power),

where P is given by the following expression for the limiting core location:

P - [R - 0.5 S) [LHR (Limit)/LHR (Measured)],

where:

R - 85 for Symmetric Offset Between 0.00 and +0.10, or 92 for Symmetric Offset Between 0.00 and -0.10 S - Number of Steps the CEAs Deviate From the CEA i Position Existing When the LHR Measurement was Taken LHR (Limit) - Linear Heat Rate Permitted by Specification 3.10.C.1 LHR (Heasured) - Liner Heat Rate Last Measured, Corrected to 100% Power As is the case in the current specification, the numerica1' values used in the equation are based on the flyspeck analysis, which is a parametric study of the peaking changes due to CEA and symmetric offset conditions. These values will be evaluated each cycle to ensure that operation within the LOCA LHGR limits is ensured by use of the equation.

CEA movement from all-rods-out to the 100% power insertion limit is a total of 18 steps in insertion for Cycle 10. According to the equation, a total penalty factor of 0.92 (S - 0) to 0.33'(S - 18) between 0.00 and - 0.10 ,

symmetric offset and 0.85 (S - 0) to 0.76 (S - 18) between 0.00 and +0.10 j symmetric offset would be applicable if the last measurement was taken in an all-rods-out condition. The result of the specification change is the potential for maintaining full power operation dJe to less restrictive penalty factors if CEA movement is minimized.

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MAINE YANKEE A70MIC POWER COMPANY 4

CONCLUSIDH The proposed specification provides a more detailed representation of allowable power level as a function of the separate effects of CEA and symmetric offset variations. Both the current and proposed representations rely upon the same flyspeck analysis data used in the Reactor Protection System setpoints determination. Both the current and proposed specification ensure that the LOCA LHGR limits are maintained during operation when the Incore Monitoring System is inoperable. The proposed specification provides the flexibility to trade-off CEA and symmetric offset restrictions.

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