ML18136A070
| ML18136A070 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 10/16/1979 |
| From: | Stallings C VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | Schwencer A Office of Nuclear Reactor Regulation |
| References | |
| 820, NUDOCS 7910190487 | |
| Download: ML18136A070 (15) | |
Text
e VIRGINIA ELECTRIC AND POWER COMPANY RICHMOND, VIRGIN IA 2 32 61 October 16, 1979 Mr. Harold R. Denton, Director Serial No. 820 FR/RWC:
plc Office of Nuclear Reactor Regulation Attn:
Mr. Albert Schwencer~ Chief Operating Reactors Branch No. 1 Division of Operating Reactors U. S. Nuclear Regulatory Connnission Washington, DC 20555
Dear Mr. Denton:
Docket No.
50...;281 License No. DPR~37 SUPPLEMENTAL INFORMATION TO AMENDMENT TO THE OPERATING LICENSE TECHNICAL SPECIFICATIONS CHANGE NO. 78 SURRY.POWER STATION ~-uNIT NO. 2 Pursuant to 10 CFR 50.90, the Virginia Electric and Power Company, in our letter of May 31, 1979 (Serial No. 388), requested an amendment to Operating License DPR...;37.
The amendment requested was Change No.- 78 to the Technical Specifications which was based on a.LOCA-ECCS analysis *which will support the continued full rated power operation of both Surry Unit Nos. 1 and 2 after replacement.of their respec-tive steam generators.
Transmitted herewith is supplemental information to our May 31, 1979,sub-mittal regarding power distribu.'tion monitoring requirements. provides a safety.evaluation which supports elimination of the requirement for frequent axial power distribution surveillance based on the maximum analytically predicted total peaking factor values for Cycle 5 of Surry Unit 2 which are less than the limit established by the LOCA-ECCS submittal of May 31, 1979. also supports a related modification of the Axial Flux Difference limits. provides the appropriate additional changes to the Technical Specifications.
This proposed amendment has been reviewed and approved by both the Station Nuclear Safety and Operating Committee and the System Nuclear Safety and Operating Committee.
It has been determined that this request does not involve an unreviewed safety question as defined in 10 CFR 50.59.
Your review of the attached Technical Specifications change is requested by December 1, 1979.
Should you have questions, we would be happy to meet with you at your earliest convenience.
Attachments:
(1)
Safety Analysis (2)
Proposed Technical Specifications cc:
Mr. James P, O'Reilly, Director, Office Very truly yours,
~a_,#.r:
C. M. Stallings
~
Vice President-Power Supply
\\
and Production Operations l)IPc,,,\\\\
7910] 901-~
of Inspections and Enforcement Region II
e ATTACHMENT 1
e e
ATTACHMENT 1 SAFETY EVALUATION (TOTAL PEAKING FACTOR) FOR SURRY UNIT NO. 2 The maximum total peaking factor values (FQ(Z)) obtainable during Cycle 5 routine steady-state and assumed load follow (Condition I) operation have b22n determined to be less limiting than the allowable LOCA-ECCS total peaking factor limits defined in Reference 1.
These analytically predicted total pea..<ing factor values were determined using the methodology documented in Refere222 2.
Since violations of the current LOCA-ECCS allowable total peaking factor v;,l u.es are not predicted, the requirement for frequent axial power distribu.~ion surveillance currently in the Technical Specifications can be e limina-ced.
.tLxial flux difference requirements a,re an integral part of the methodology used to determine the total peaking factor, (FQ(Z)),values associ-ated with Condition I operation.
Based on the results of the Cycle 5 peaking factor analysis for Condition I operation, which. demonstrate that all C.ondi tion I FQ(Z) values will be below the LOCA-ECCS limiting FQ(Z) values, the axial flux difference limits have been modified in accordance with the methodology developed by Westinghouse and presented in Reference 3.
e e
References
- 1. Letter from Vepco (C. M. Stallings) to NRC (H. R. Denton) dated May 31, 1979, Serial No. 388.
- 2.
Letter from Westinghouse (C. Eicheldinger) to NRC (J. F. Stolz) dated April 6, 1978, Serial No. NS-CE-1749.
- 3.
T. ~orita, et. al., nPower Distribution Control and Load Following F::-ocedures, 11 WCAP-8385, Westinghouse Electric Corporation, September, 1974.
~--***
1/*
e e
ATT ACI:LMENT 2 ti -------
/
Unit 1 F
< 2.05 x K(Z)
Q
~N ILOCA
< 1.38
- LE Assm.
_2'i LOCA
.!:','17= Rod
< 1. 4s e
DELETED e
Unit 2 FQ.::_ 2.19 x K(Z),
FN ILOCA
< 1.476 L\\H Assm.
FN
- 1 LOCA < 1. 55 L\\H Rod TS J.12-4a
r-e TS 3.12-4b DELETED
I
//. *-.,._.,_ *~ --- -* - ' - --. *-~- ----..
e e
TS 3.lZ.-5
- 3.
The reference equilibrium indicated axial flux difference (called the target flux difference) at a given power level P0, is that indicated axial flux difference with the core in equilibrium xenon conditions (small or no oscillation) and the control rods more than 190 steps* withdrmm.
The target flux difference at any other power level, P, is equal to the target value at P0 multiplied by the*ratio; P/P0
- Tb.e target flux difference shall be measured at least once per equivalent full power quarter.
The target flux difference must be
~pdated c~riil6 ecch eff~ctive full power month of operation either by actual ~eas.irement, or by linear interpolation using the most recent value and the value predicted for the end of the cycle life.
- 4.
F.~cept as modified by 3.12.B.4.a, b, c, or d below, the indicated 2-xial flux difference shall be maintained within a +5% band about the target flux difference (defines the target band on.axial flux difference).
- a.
At a power level greater than 90 percent of rated power, if the indicated axial flux difference deviates from its target band, within 15 minutes either restore the indicated axial flux difference to within the target band, or reduce the reactor power to less than 90 percent of rated power.
- b. At a power level no greater than 90 percent of rated power, (1)
The indicated axial flux difference may deviate from its target band for a maximum of one hour (cumulative) in any 24-hour period provided the flux difference is within the limits shown on Figure 3.12-10.
e TS 3.12-6 One minute penalty is accumulated for each one minute of operation outside of the target band at power levels equal to or above 50% of rated power.
(2)
If 3.12.B.4.b(l) is violated, then the reactor power shall be reduced to less than 50% power within 30 minutes an_d the high neutron flux setpoint shall be reduced to no greater than 55% power within the next four hours.
(3)
A power increase to a level greater than 90 percent of rated power is contingent upon the indicated axial flux difference being within its target band.
(4)
Surveillance testing of the Power Range Neutron Flux Chann~1s may be performed pursuant to Table 4.1-1 provided the indicated AFD is maintained within the limits of Figure 3.12-10.
A total of 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> of operation may be accumulated with the AFD outside of the target band during this testing without penalty deviation.
- c.
At a power level no greater than 50 percent of rated power, (l)
The indicated axial flux difference may deviate from its target band.
- (2)
A power increase to a level greater than 50 percent of rated power is contingent upon the indicated axial flux difference not being outside its target band for more than one hour accumulated penalty during the preceding 24-hour period.
One half minute penalty is accumulated for each one minute of operation outside of the target band at power levels between 15% and 50% of rated power.
- d.
The axial flux difference limits of Specifications 3.12.B.4.a, b, and c may be suspended during the performance of physics tests provided:
(1)
The power level is maintained at or belo~ 85% of rated power, and (2)
The limits of Specification 3.12.B.1 are maintained.
The power level shall be determined to be< 85% of rated power at least once per hour during physics tests. Verifi-cation that the limits of Specification 3.12.B.1 are being met shall be demonstrated through in-core flux mapping at least once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
-TS 3.12-18 DELETED
TS 3.12-19 DELETED The procedures for axial power distribution control are designed to mini-mize the effects of xenon redistribution on the axial power distribution during load-follow maneuvers.
Basically, control of flux difference is required to limit the difference between the current value of flux dif-ference (ll) and a reference value which corresponds to the full power equilibrium value of axial offset (axial offset= ~I/fractional power).
The reference value of flux difference varies with power level and burnup, but expressed as axial offset it varies only with burnup.
~---***--
e TS 3.12-20 The technical specifications on power distribution control given in 3.12.B.4 together with, the surveillance requirements given in 3.12.B.2 assure that the Limiting Condition for Operation for the heat flux hot channel factor is met.
The target (or reference) value of flux difference is determined as
£c*1ows.
At any time that equilibrium xenon conditions have been estab-l~5hed; the indicated flux difference is noted with the full length rod co::.;__-'-ol 02.rrk wore than 190 steps withdrawn (i.e. normal full power opera-t-fn~ position 2.pprcpriate for the time i.n life, usually withdrawn farther as b~r:!.up proceeds).
This value, divided by the fraction of full power at w-ri1ch the core was operating is the full power value of the target flux difference.
Values for all other core power levels are obtained by multiplying the full power value by the fractional po,ver.
Since the indi-cated* equilibrium value was noted, no allowances for excore detector error are necessary and indicated deviation of +5% t.I are permitted from the indicated reference value.
During periods.where extensive load following is required, it may be impractical to establish the required core conditions for measuring the target flux difference every month.
For this reason, the specification provides two methods.for updating the target flux difference.
Strict control of the flux difference (and rod position} is not as neces-sary during part power operation.
This is because xenon distribution control at part power is not as significant as the control at full
e e
TS 3.12-21 power and allowance has been made in predicting the heat flux peaking factors for less strict control at part power.
Strict control of the flux difference is not always possible during certain physics tests or during excore detector calibrations.
Therefore, the specifications on power distribution control are less restrictive during physics tests and e.xcore detector calibrations; this is acceptable due to the low probabili-ty or a significant accident occurring during these operations.
1..2.s;:22 i::.1stc.::ces of rapid ;init power reduction automatic rod motion will e.2.c:..s2 the flux df-fference to deviate from the target band when the reduced pc~e= level is reached.
This does not necessarily affect the xenon dis-tribu~ion sufficiently to change the envelope of peaking factors which can be reached on a subsequent return to full power within the target bc::d; however, to simplify the specification, a limitation of one hour in any period of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> is placed on operation outside the band.
This ens~"es that the resulting xenon distributions are not significantly different.from those resulting from operation within the target band.
The instantaneous consequences of being outside the band, provided rod insertion limits are.observed, is not worse than a 10 percent increment in peaking factor for the allowable flux difference at 90% power, in the range+ 13.8 percent *(+10.8 percent indicated) where for every 2 percent below rated power, the permissible flux difference boundary is extended by 1 percent.
As discussed above, the essence of the procedure is to maintain the xenon distribution in the core as close to the equilibrium full power condition
e
~ TS Table 3.12-lB THIS TABLE HAS BEEN DELETED.
e AXIAL FLUX DIFFERENCE LIMITS AS A FUNCTION OF RATED POWER SURRY POWER STATION TS FIGURE 3.12-10
'.: +':-~, ~~~-j-~~+-.,-rl-t~:-cj'
===r:=::=--
-+-*-t----->--~' -'--,: '++-',-+' '-'-+',-"-,-+-'-
,1:11,,:....,,,
'!......L.~,
- I I
I I
- -~',-\\-1-*...+-'---+c---,-+--,--~,-_.;--\\-L,....,-~-f-'-, --,-+:..,..
- i--
' '+-:---c- *
~
---+-
i-
~-~--=: __ :- !--;-, '
- ....... --11.~,~*
- - -r---:----~r
- +=..:(--= *~ =i==+--t~ ' : : : ' : r--'--T+--'--
~'
-40
-30
-20
-10 0
10 20 30 40 50 FLUX DIFFERENCE (~I) %
I l
1 I I l I l 1
I i I