ML19305D267
| ML19305D267 | |
| Person / Time | |
|---|---|
| Site: | La Crosse File:Dairyland Power Cooperative icon.png |
| Issue date: | 04/01/1980 |
| From: | Linder F DAIRYLAND POWER COOPERATIVE |
| To: | Ziemann D Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML19305D270 | List: |
| References | |
| FOIA-80-274 LAC-6846, NUDOCS 8004140312 | |
| Download: ML19305D267 (4) | |
Text
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DitIlt1LSNIb I*0 WEIT C00I*EItatTIVE Ss Cronw, 01hcor sir, 54601 April 1, 1980 In reply, please refer to LAC-6846 DOCKET NO. 50-409 Director of Nuclear Reactor Regulation ATTN:
Mr. Dennis L.
Ziemann, Chief Operating Reactors Branch #2 Division of Operating Reactors U.
S. Nuclear Regulatory Commission Washington, D.
C.
20555
SUBJECT:
DAIRYLAND POWER COOPERATIVE LA CROSSE BOILING WATER REACTOR (LACBWR)
PROVISIONAL OPERATING LICENSE NO. DPR-45 REQUEST FOR RELIEF FROM TECHNICAL SPECIFICATION LIMIT
References:
(1)
NRC Letter, Ziemann to Linder, dated February 4, 1980.
(2)
DPC Letter, LAC-6767, Linder to Ziemann, dated January 28, 1980.
(3)
DPC Letter, LAC-6739, Linder to Ziemann, dated January 17, 1980.
(4)
NRC Letter, Ziemann to Linder, dated May 25, 1979.
Gentlemen:
In the Safety Evaluation Reports (SER's) for LACBWR license amend-ments No. 16 and No. 19 (References 4 and 1 respectively), the NRC staff noted that the turbine trip and generator load rejection pressurization transients with postulated failures of the bypass valves had not been performed.
Since it was thought that these transients might produce limiting ACPR's or primary system pressure increases at, or near, the End of Cycle-All Rods Out (EOC-ARO) conditions, DPC and the NRC staff agreed to preclude operation near EOC-ARO conditions by limiting the average exposure of the lead burnup fuel assembly to 15,600 MWD /MTU until DPC provided analyses showing that the pressurization transients will not penetrate the Cycle 6 approved operating MCPR's or produce unacceptable pressure increases in the system.
These analyses are provided as Attachment 2 to this letter.
The results of these analyses show that the ACPR's produced by the postulated turbine trip / generator load rejection pressurization transient without bypass are smaller than the ACPR's previously cal-culated for the control rod withdrawal transient (See Attachment 2). 80 0.414 0 3 / A
4 Mr. Dennis L.
Ziemann, Chief LAC-6846 Operating Reactors Branch 62 April 1, 1980 Therefore, the control rod withdrawal transient remains the con-trolling transient with respect to the allowable operating limit MCPR's and the operating limit MCPR's currently in the LACBWR Technical Specifications are applicable at the EOC-ARO condition.
The analyses in Attachment 2 also show that the maximum primary system pressure during the postulated transient is only 1349 psig, conservatively below a conservative relieving pressure of 1376 psig for the safety valves.
(Setpoint = 1390 psig).
The analyses in Attachment 2 conservatively assumed that the reactor was initially operating at 102% of rated power with end of cycle core conditions and all control rods fully withdrawn.
It was con-servatively assumed that the turbine trip results in an instantan-cous and total loss of steam flow to the turbine, that turbine bypass flow to the condenser does not occur, and that no steam flows to the shutdown condenser until the system pressure reaches 1325 psig.
No credit is taken for the reactor partial scram (13 control rods) or the recirculation pump run back to 80% of full flow caused by the turbine stop valve closure.
No credit is taken for a reactor scram on high power to flow ratio at 115% of rated power.
It is assumed that a reactor scram is initiated when reactor power reaches 120% of rated power, but it is very conservatively assumed that negative reactivity insertion by control rods is delayed an additional 1.5 seconds (see Scram Reactivity Curve in Attachment 3) oven though rod insertion would begin in much less than 0.5 seconds.
Run back of the recirculation pumps to 80% of full flow is also initiated at 120% of rated power, but actual reduction of recircul-ation is conservatively delayed for 0.5 seconds.
Based on the satisfactory results of the analysis of the turbine trip without bypass pressurization transient at the EOC-ARO conditions described above and other justification set forth in detail in References 1, 2 and 3 and summarized below, Dairyland Power Cooper-ative requests that LACBWR Technical Specifications 4.2.4.2.5 and 5.2.17.5 be changed so that the exposure limitation applies only to fuel assemblies in the interior of the core and the exposure limit on peripheral assemblies is deleted.
The proposed Technical Specifi-cation wording and the revised bases for Technical Specifications 4.2.4.2.5 and 5.2.17.5 are presented in Attachment 1 to this letter.
The present core configuration, Cycle-6, contains only 12 Allis-Chalmers (A-C) Type II fuel assemblies and they are all located on the periphery of the core.
The lead assembly 2-58 is presently operating at only 0.53 times core average assembly power, and none of the Type II assemblies are operating at greater than 0.6 times average assembly power.
The peripheral fuel assemblies do not experience the large local power peaking present above the tips of control rods or the rapid power changes as control rods are moved since the outer Mr. Dennis L.
Ziemann, Chief LAC-6846 Operating Reactors Branch #2 April 1, 1980 control rods are fully withdrawn at the beginning of cycle and remain withdrawn during normal cycle operations.
Any minor clad defects that may be present or may develop during continued opera-tion would be expected to develop very slowly, and the consequences of such failures would be minimal.
The probability of a failed fuel rod propagating a failure in an adjacent rod is remote because of the low power densities present in the peripheral core positions.
All fuel assemblies located in the higher powered inner regions of the LACBWR core are the new improved Type III (EXXON) assemblies except for two Type I (A-C) assemblies in core positions B-5 and B-6.
The Type III assemblies are designed for a batch average exposure of 16,800 MWD /MTU, which corresponds to a maximum assembly exposure of approximately 21,500 MND/MTU.
When the present fuel cycle (Cycle-6) reaches the EOC-ARO condition, the maximum Type III assembly exposure will still be less than 14,300 MWD /MTU.
It is anticipated that beginning with the next fuel cycle, the LACBWR core configuration will contain only Type III assemblies except for the two Type I assemblies which will be moved to peripheral core positions for 2 or 3 more cycles.
We believe that no precipitous deterioration of the fuel condition will occur during additional operation to higher fuel exposures.
Any deterioration that might possibly occur is expected to develop slowly and would be apparent at an early stage from increases in the reactor coolant and off-gas radioactivity.
The Technical Specifica-tion limits for these activities provide assurance that the LACBWR fuel assemblies will not exhibit unacceptable degradation dur'-n future operation.
The plots of reactor coolant and off-gas radioacil'ity presented in Reference 3 have been updated and are included for your information as Attachment 4 to this letter.
These plots indicate that there has been essentially no change in the fuel condition in the last several months and provide siditional confidence that the current fuel cycle may be continued for some time wi thout experiencing unacceptable degradation of the fuel.
The information submitted with this request has been reviewed by LACBWR committees as prescribed in Technical Specif ications.
DPC respectfully asks that the review of this request be expedited so that a decision may be received before the present Technical Specification limit is reached on about the 9th of May, 1980.,
Mr. Dannie L.
Zicmann, Chief LAC-6846 Operating Reactors Branch #2 April 1, 1980 If you have any questions, please feel free to call us at any time.
Very truly yours, DAIRYLAND POWER COOPERATIVE 0
Cml%&
Frank Linder, General Manager FL:SJR:af cc:
James J.
Keppler, Reg. Dir., NRC-DRO III STATE OF WISCONSIN )
)
COUNTY OF LA CROSSE)
Personally came before me this day of April, 1980, the above named Frank Linder, to me known to be the person who executed the foregoing instrument and acknowledged the same.
J Notary Publid, La Crosse County, Wisconsin.
My Commission Expires February 26, 198C