ML13331A976
| ML13331A976 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 08/31/1987 |
| From: | SOUTHERN CALIFORNIA EDISON CO. |
| To: | |
| Shared Package | |
| ML13331A970 | List: |
| References | |
| NUDOCS 8709080429 | |
| Download: ML13331A976 (9) | |
Text
3.10 INCORE INSTRUMENTATION AppIlcability:
Applies to the frequency which the incore instrumentation will be used to verify linear power density values.
13 Objective:
To specify the frequency of incore measurements used to verify linear power density values.
Specification:
Except as provided for in Specification E:
18 1/10/75 A.
A power distribution measurement shall be performed every 30 effective full power days (EFPD) and after attainment of equilibrium xenon upon return to power following a refueling shutdown.
If the measurement 13 cannot be made within the prescribed time, a maximum of 11/13/73 15 EFPD will be allowed for equipment correction.
Except as provided for in Specification E:
17 12/20/74 B.
The incore instrumentation system shall be used to accomplish the Correlation Verification of incore 18 versus excore data for the axial offset monitoring 1/10/75 system prior to exceeding 90% of rated thermal power following each refueling. Subsequent to the Correlation Verification and for the duration of each cycle, incore instrumentation shall be used to perform a Correlation Check of the axial offset monitoring system every 30 EFPD.
If the Correlation Check cannot be made within the prescribed time, a maximum of 15 EFPD will be allowed for equipment correction. If the Correlation Check and the Correlation Verification do not substantiate the existing incore versus excore correlation within an area defined by +3 percent on incore axial offset and +1 percent on excore axial offset, a complete recorrelation shall be determined.
C.
A core thermocouple map shall be taken every 30 EFPD and after attainment of equilibrium xenon upon return 17 to power following a refueling shutdown.
If the 12/20/74 measurement cannot be made within the prescribed time, a maximum of 15 EFPD will be allowed for equipment correction.
D.
In the event that Specification A, B, and C cannot be met during the 15 EFPD allowed for corrective action, plant operation shall be limited to 90% of rated thermal power until these specifications can be met.
87090110429 870831 PDR ADOCK 05000206 1PDR 3-91 Revised:
10-30-78
E.
For the period of time between the effective date of Amendment No. 8 and the end of Cycle 4, the power distribution measurements and the correlation check of the axial offset monitoring system in Specifications A 18 and B shall be performed every 90 effective full power 1/10/75 days (EFPD).
Basis:
The flux mapping system is used to measure the core power distribution and to correlate incore versus excore data for the axial offset system. Measurements made with the flux mapping system every 30 effective full power days and upon return to power following a refueling shutdown will monitor the core power distribution to confirm that the maximum linear power density remains below allowable values.
The axial offset system will monitor the axial core power distribution in a continuous manner.
If the Correlation Verification or Correlation Check is not performed, the 90%
of full thermal power restriction assures safe operation of the reactor.
In addition, core thermocouples provide an independent means of measuring the balance of power among the core quadrants.
17 12/20/ 74 The flux mapping system and the thermocouple system are not integral parts of the Reactor Protection System. These systems are, rather, surveillance systems which may be required in the event of an abnormal condition such as a power tilt or a control rod misalignment.
Since such a condition cannot be predicted, it is prudent to have the surveillance systems in an operable state.
The 90% of full power restriction, used when the these measurements cannot be taken as scheduled, is applied to minimize the probability of exceeding allowed peaking factors.
3-92 Revised:
10-30-78
3.11 CONTINUOUS POWER DISTRIBUTION MONITORING Applicability:
Applies to axial offset limit.
17 12/20/74 Objective:
To provide corrective action in the event that the axial offset monitoring system limits are approached.
21 Specification:
A.
The incore axial offset limits shall not exceed the 17 functional relationship defined by:
12/20/74 For positive offsets:
IAO =
2.89/P -
2.1225 -3.0 6
0.03021
-3.60 2.89/P_____
6/8/818 For negative offsets:
IAO 2.89/P -
2.1181+3.0
.03068 where 17 12/20/7 4 IAO = incore axial offset 21 P = fraction of rated thermal power 5/13/75 18 B.
If the incore limit defined by Specification A, as 1/10/75 measured by the excore axial offset system, is exceeded by both axial offset monitoring channels, reactor power shall be reduced until Specification A is satisfied.
C.
If it is determined that one of the excore axial offset monitoring channels is inoperable, the other axial 17 offset channel shall be used to provide power 12/20/74 distribution information. In addition, one NIS channel current shall be logged every two hours and axial offset information determined from this data until the inoperable channel has been returned to service.
D.
If both channels should be declared inoperable, at least three NIS channel currents shall be logged every two hours and offset information determined from these data.
If no method for determining axial offset is available, reactor power shall be reduced to 90% of rated thermal power.
Basis:
The percent full power axial offset limits are conservatively established considering the core design peaking factor, analytical determination of the relationship between core peaking factors and incore axial offset 21 considering a wide range of maneuvers and core conditions, 5/13/75 and actual measurements relating incore axial offset to the 17 12/20/74 3-93 Revised:
6/23/81
axial offset monitoring systems.
The axial offset limit established from the incore versus excore data have been reduced by an amount equivalent to 3 percent on incore axial offset to allow for uncertainties in the correlation.
Should a specific cycle analysis establish that the analytical determination of the relationship between core peaking factors and incore axial offset has changed in a manner warranting modification to the existing envelope of peaking factor (1,2), then a change to functional relationship of Specification A shall be submitted to the Commission. The incore-excore data correlation is checked or verified periodically as delineated in Specification 3.10.
Reducing power in cases when limits are approached or exceeded, will assure that design limits which were set in consideration of accident conditions are not exceeded.
Prior to installation of the axial offset monitoring system, the NIS system was used to monitor axial offset and showed 17 there is considerable margin between axial offset normally 12/20/74 seen and limits established in consideration of design peaking factors.
References:
(1) Supporting Information on Periodic Axial Offset Monitoring, San Onofre Nuclear Generating Station, Unit 1, September, 1973 (2) Supporting Information on the Continuous Axial Offset Monitoring System, San Onofre Nuclear Generating Station, Unit 1, July, 1974.
(3) Description and Safety Analysis, Including Fuel 21 Densification, San Onofre Nuclear Generating Station, 5/13/75 Unit 1, Cycle 5, January, 1975, Westinghouse Non-Propriety Class 3.
3-94 Revised:
10/30/78 3.10 INCORE INSTRUMENTATION APPLICABILITY:
MODE 1 above 90% RATED THERMAL POWER OBJECTIVE:
To specify the type and frequency of incore measurements used to verify linear power density values.
SPECIFICATION:
- a. A power distribution measurement shall be performed every 30 effective full power days (EFPD) and after attainment of equilibrium xenon upon return to power following a refueling shutdown.
- b. The incore instrumentation system shall be used to accomplish the Correlation Verification of incore versus excore data for the axial offset monitoring system prior to exceeding 90% of RATED THERMAL POWER following each refueling and at least once per 180 effective full power days (EFPD) thereafter.
Subsequent to the Correlation Verification and for the duration of each cycle, incore instrumentation shall be used to perform a Correlation Check of the axial offset monitoring system every 30 EFPD.
- c. A core thermocouple map shall be taken every 30 EFPD and after attainment of equilibrium xenon upon return to power following a refueling shutdown.
ACTION:
A. If the correlation check, power distribution measurement or core thermocouple map described above cannot be made within the prescribed time, a maximum of 15 EFPD will be allowed for equipment correction.
B. In the event that Specification a, b and c cannot be met during the 15 EFPD allowed for corrective action, within one hour action shall be taken such that THERMAL POWER is restricted to less than or equal to 90% of RATED THERMAL POWER until these specifications can be met.
BASIS:
The flux mapping system is used to measure the core power distribution and to correlate incore versus excore data for the axial offset system. Measurements made with the flux mapping system every 30 effective full power days and upon return to power following a refueling shutdown will monitor the core power distribution to confirm that the maximum linear power density remains below allowable values.
The
axial offset system will monitor the axial core power distribution in a continuous manner. If the Correlation Verification or Correlation Check is not performed, the 90%
of full thermal power restriction assures safe operation of the reactor. In addition, core thermocouples provide an independent means of measuring the balance of power among the core quadrants.
The flux mapping system and the thermocouple system are not integral parts of the Reactor Protection System. These systems are, rather, surveillance systems which may be required in the event of an abnormal condition such as a power tilt or a control rod misalignment. Since such a condition cannot be predicted, it is prudent to have the surveillance systems in an operable state. The 90% of full power restriction, used when these measurements cannot be taken as scheduled, is applied to minimize the probability of exceeding allowed peaking factors.
Operation for a 180 effective full power day period prior to reperforming the correlation verification is acceptable on the basis that the allowed incore axial offset limits are reduced by the amount in percent of incore axial offset that the monthly correlation check differs from the correlation.
e 9
3.11 CONTINUOUS POWER DISTRIBUTION MONITORING APPLICABILITY:
MODE 1 above 90% RATED THERMAL POWER OBJECTIVE:
To provide corrective action in the event that the axial offset monitoring system limits are approached.
SPECIFICATION:
The incore axial offset limits shall not exceed the functional relationship defined by:
2.89/P -
2.1225 For positive offsets:
IAO =
FCC 0.03021 2.89/P - 2.1181 For negative offsets:
IAO = ---------------
+ FCC
-. 03068 where IAO = incore axial offset P = fraction of RATED THERMAL POWER FCC = The larger of 3.0 or the value in percent of incore axial offset by which the current correlation check differs from the incore-excore correlation.
ACTION:
A. If the incore limit defined by the Specification, as measured by the excore axial offset system, is exceeded by both axial offset monitoring channels, within one hour action shall be taken such that THERMAL POWER is restricted to less than or equal to 90% of RATED THERMAL POWER until these specifications can be met.
B. If it is determined that one of the excore axial offset monitoring channels is inoperable, the remaining OPERABLE excore axial offset channel shall be used to provide power distribution information. In addition, one NIS channel current shall be logged every two hours and axial offset information determined from this data until the inoperable channel has been returned to OPERABILITY.
C. If both excore axial offset channels are declared inoperable, at least three NIS channel currents shall be logged every two hours and offset information determined from these data. If no method for determining axial offset is available, within one hour action shall be taken such that THERMAL POWER is restricted to less than or equal to 90% of RATED THERMAL POWER until these specifications can be met.
BASIS:
The percent full power axial offset limits are conservatively established considering the core design peaking factor, analytical determination of the relationship between core peaking factors and incore axial offset considering a wide range of maneuvers and core conditions, and actual measurements relating incore axial offset to the axial offset monitoring systems.
The axial offset limit established from the incore versus excore data have been reduced by an amount equivalent to FCC to allow for burnup and time dependent differences between the periodic correlation verification and the monthly correlation check. Correcting the allowed incore axial offset limits by an amount equal to FCC maintains plant operation within the original safety analysis assumptions.
Should a specific cycle analysis establish that the analytical determination of the relationship between core peaking factors and incore axial offset has changed in a manner warranting modification to the existing envelope of peaking factor (1,2), then a change to functional relationship of the specification shall be submitted to the Commission. The incore-excore data correlation is checked or verified periodically as delineated in Specification 3.10, INCORE INSTRUMENTATION.
Reducing power in cases when limits are approached or exceeded, will assure that design limits which were set in consideration of accident conditions are not exceeded.
Prior to installation of the axial offset monitoring system, the NIS system was used to monitor axial offset and showed there is considerable margin between axial offset normally seen and limits established in consideration of design peaking factors.
References:
(1) Supporting Information on Periodic Axial Offset Monitoring, San Onofre Nuclear Generating Station, Unit 1, September, 1973 (2) Supporting Information on the Continuous Axial Offset Monitoring System, San Onofre Nuclear Generating Station, Unit 1, July, 1974 (3) Description and Safety Analysis, Including Fuel Densification, San Onofre Nuclear Generating Station, Unit 1 Cycle 5, January, 1975, Westinghouse Non-Proprietary Class 3.
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