ML19317H016
| ML19317H016 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 04/29/1977 |
| From: | Walbridge W SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| To: | Reid R Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8004020693 | |
| Download: ML19317H016 (8) | |
Text
DI5TRIBUTION AFTER ISSUANGE UY UFP HA11NG L.1LENbb NUMBE u.s.NUCLEAQ RE!ULATOCY COMM,lSSION OCC5M0.h1Q RC PCRM 196
, NQ OlSTRIBUTION Poa PART 50 DOCKET MATERIAL
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Mr. Robert W. Reid SMUD 08/29/77 Sacramento, California 95813 o4TE RECEivEo Wm. C. Walbridge 09/06/77 cETTER ONOTORIZED PROP INPUT PQRM NUMSER OF COPtES MECEIVED Xp31GINAL UNCt.ASSIPIE D OCoPY
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- sCRIPrios ENCLosu RE Consists of additional in' formation regarding zero power physics tests and power test listed in Section 9 of previously submitted repo f BAW-1460, " Rancho Seco Nuc. Generating Station,.-
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$5 MUD SACRAMENTO MUNICIPAL UTILITY DISTRICT O 6201 S Street, Box 15830 Sacramento, California 95813; (916) 452-3211 August 29, 1977 Director of Nuclear Reactor Regulation ATTN:
Robert W. Reid, Chief
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U. S. Nuclear Regulatory Commission Washington, D. C. 20555 Docket No. 50-312 Rancho Seco Nucit:ar Generating Station Unit No. 1
Dear Mr. Reid:
In your letter of August 17, 1977, you requested additional information needed to complete your review of the zero power physics tests and power tests listed in Section 9 of our previously submitted report, BAW-1460, " Rancho Seco Nuclear Generating Station, Unit 1, Cycle 2 Reload Report."
The requested information is attached to this letter, includ-ing our commitment for submitting to NRC a report on the results 'of this testing in our Annual Report, per the provisions of Regulatory Guide 1.16.
Sincerely,
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Wm. C. Walbridge 6'
General Manager Attachment x
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SACRAMENTO MUNICIPAL UTILITY DISTRICT ADDITIONAL INFORMATION RELATIVE TO DOCKECT NO. 50-312 CYCLE 2 RELOAD TESTING 1.
Critical Baron Concentration A single measurement'is made at a nominal 332 F, 2155 psig, all full-length Control Rod Assemblies (CRA) fully withdrawn, and Axial Power Sh: ping Rods (APSR) positioned at the core midplane. The measured value is to be within 100 ppmB of the predicted All Rods Out (AR0) boron con-centration.. The measurement is accomplished by adjusting the boron con-centration to be just critical with CRA Group 7 controlling with approx-imately 0.1%AK/K inserted reactivity. Starting from a power level below sensible heat, Group 7 is fully withdrawn which establishes a stable po-sitive period. The positive [ reactivity is detemined and the measurement-is terminated by Group 7 in'sertion prior to reaching the level power associated with sensible heat.
Using the predicted value for differential boron worth, the measured reactivity is converted into an 'quivalent baron e
concentration change and added to the measured Reactor Coolant System (RCS) baron concentration.
If the acceptance criteria is not met, the re-sults will be evaluated and appropriate adjustments made.
2.
Temperature Coefficient of Reactivity Two measurements are made:
one corresponding to the all control rods fully withdrawn configuration, the other near the maximum rod in-sertion limit.
In both cases, the measurements are at a nominal 532 F,,
1 2155 psig, APSR are positioned at the core midplane, and the neutron power i
maintained below that indicative of sensible heat.
Starting from a just-critical condition, the reactor coolant O
system average temperature is changed by about S F, after which the j
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stable reactivity is recorded. Then the temperature is changed by approx-
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. imately 10 F in the opposite direction, after which the stable reactivity 0
is recorded, followed by returning to near the original temperature, and again reco,rding the stable reactivity. Adjustments in controlling CRA group position. are utilized to maintain the neutron flux within desired limits for accurate reactivity measurements. The temperature coefficient calculated from the largest temperature change will be compared to the test acceptance criteria. The value shall not be more positive-than
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0 0 and should be within 0.4(10-2)%aK/K/F of the predicted
+0.5(10-2)%aK/K/F value.
Failure to meet these criteria will be cause for evaluation of results and/or prediction.
3.
CRA Group Worth The integrated worth of the three regulating CRA groups.will be measured by exchanging CRA for dissolved boron.
Starting from near all rods out, the APSR positioned at the core midplane with a nominal 532 F, 2155 psig, the RCS will be deborated in such a manner that the regulating CRA groups are inserted in discreet steps. The sumation of the resulting CRA reactivity insertions is then the worth of the individual regulating control rod groups. The groups,will be -inserted in a sequence such that J
each'will be fully inserted prior to the following group beginning its travel. The measurements will terminate near the rod insertion limit (Group 5atzeropercentwithdrawn).
If the total worth of; Group 7, 6, and 5 is within 10% of predicted worth, then no further measur'ement is required.
If this criteria is not met, then the remaining Groups, one through four, will be dropped and the inserted reactivity measured by a suitable reactivity meter. No acceptance criteria is assigned to such a rod-drop reactivity measurement.
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- 4.. Ejected Rod Worth Measurement Starting with the RCS and. makeup systems in equilibrium with respect to boron concentration, and near the maximum CRA Group insertion
, limit, the APSR positioned at the core midplane, and critical at below the sensible heat range, the predicted worse case ejected CRA is to be
" ejected" by boration. The ejected CRA will be withdrawn in discreet
, steps while compensating for the additional' boron.
After establishing equilibrium boron in the RCS and mak up systems with the " ejected" rod out, the worth of the ejected rod is cal-culated using the change in boron concentratton and the predicted dif-ferential boron worth. A second measure of this rod's worth is' then obtained by reinserting the " ejected" rod and compensating for its worth by withdrawing Group 5, the controlling group.
The change h Group 5 4
position is then converted into reactivity by use of the Group 5 integral worth calibration curve done earlier. The " measured" ejected rod worth is then taken to be the average of the two techniques. The measured worse case ejected CRA is then corrected for controlling CRA group' withdrawal (Group 5 more than zero percent withdrawn) and for uncertainties associated with the use of predicted rod worths and the boron exchange method. This aeasurement will be acceptable if within 20% of predicted.
If this criteria is not met,the evaluation will include reviewing the selection of " worse case" ejected rod, its predicted worth and the predicted dif-ferential boron worth.
5.
Core Power Distribution Verification During Power Escalation The reactor is to be established at near nominal conditions of temperature, pressure, power, and equilibrium Xenon (exceptfor the O
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40% FP test). CRA controlling Group 7 is to be within 3% WD of the pre-dicted position, and core imbalance to be within 2% FP of that in the predicted case. The results are acceptable for the test power level i,f ~
the worst case linear heat rate is less than the LOCA limit specified in technical specifications, and the minimum DNBR is greater than 1.30.
1 Extrapolt; tion cf.the minimum DNBR to the overpower trip setpoint must be greater than 1.30 or the extrapolated value of imbalance must fall outside the RPS Power / Imbalance trip envelope.
The value obtained,from the extrapolation of the worst case maxi-mum LHR to the overpower trip setpoint of the next power plateau must be less than the fuel melt l'imit or the extrapolated value of imbalance must fall outside the RPS Power / Imbalance trip envelope.
6.
Power Imbalance Detector Correlation This test will be started after establishing nominal equilibrium conditions at 75% full power. Control rods will be positioned at near the
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nominal full-power configuration and the resulting power imbalance adjusted l
to be near zero. This configuration will be maintained until the core has established eouilibrium Xcnon for the test power level.
Having established these initial conditions, the core power will be varied over a range of negative-to-positive imbalance by changing the position of the Axial Power Shaping Rod (APSR) group.
At the various im-posed imbalances, data will be taken from the incore flux detectors and compared to the imbalance observed on the out-of-core nuclear instrumenta-l tion and backup incore recorder systems. The observed data, when plotted, j
is acceptable if it shows the correlation as predicted and assumed in the i
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p design analysis. (Basically this correlation is a one-to-one imbalance relationship.) Adjustment of the amplifier gains for the out-of-core
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nuclear instrumentation is required if the. correlation limits are
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exceeded. Changing the amplifier gain requires a retest to determine '
and verify the correlation. Additionally, fuel perfonnance is evaluated at each imbalance plateau. Minimum allowed DNBR is 1.30, and the linear heat rate is to be less than the LOCA limit, or if outside the LOCA limit, less than the fuel melt limit for those conditions of power and imbalance which are within the RPS trip envelope. When extrapolated to the overpower trip setpoint, the minimum'DNBR is to remain greater than 1.30, or the imbalance is to lie outside the RPS trip setpoint. The extrapolated worse case LHR is to be less than the fuel melt limit for those conditions of power and imbalance which lie within the RPS trip envelope.
Power will not be raised above a level at which the corresponding overpower trip set-point exceeds any of the above criteria.
7.
Power Doppler Reactivity Coefficient.
With equilibrium conditions at near full power, including core Xenon, the differential worth of the controlling rod group will be determ-ined by the fast insert /withdraval method.
Power will then be decreased about 5% full power by controlling.CRA group after which the controlling group differential rod worth will again be determined. The average CRA differential worth, and the change in controlling group positior, asso-ciated with the power change, then determine the power dopper coefficient.
The measurement will be acceptable if it is more negative than -0.55(10-2)g AK/K/%FP. The reactor will not be operated at full power unless this cri-
'aricn is satisfied.
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Temperature Reactivity Coefficient With equilibrium conditions at near full power, including core Xenon, the differential worth of the controlling rod group will be determ-ined by the fast insert / withdrawal method. The RCS average _ temperature U
will then be decreased about S F, without a significant power change, after which the controlling group differential rod worth will again be determined. The average differential CRA worth and the change in controlling group position associated with the temperature change then determine the temperature coefficient. The measurement will be acceptable if it is not positive at power levels above 95% FP. The reactor will not be operated at full power unless this criterionis satisfied, j
9.
Dropped Contr.o1 Rod Power Distribution t
With the reactor core near equilibrium Xenon and at about 40% full power with control rods positioned to provide a nominal zero imbal'ance, the control rod identified to create the most adverse thermal conditions in the core will be fully inserted and the resulting power distribution analyzed.
This analysis will verify that the minimum observed DNBR, when extrapolated to 100% full power, will be greater than 1.30, and that the maximum linear heat rate,when extrapolated,will remain less than the fuel melt limit. Add-itionally, the test will provide an opportunity to verify the proper func-tioning of the Asymmetry Alarm and Fault features of the Control Rod Drive System.
If acceptance criteria are not met, the situation will be evaluated and action taken to correct the deviant parameter.
- 10. Test Report Under the provisions of' Regulatory Guide 1.16, we will include in our annual report a brief summary of the above-described tests and a comparison of the results with the applicable acceptance criteria.
6.
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