ML20003A193
| ML20003A193 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 02/09/1977 |
| From: | Bixel D CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8101300855 | |
| Download: ML20003A193 (4) | |
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Y DOCKET 50-155 - LICENSE DPR BIG RCCK POIHT PLAHT - MAPLHGR LIMITS FOR RELOAD G A'iD G-lU FUEL The purpose of this letter is to provide responses to questions concerning the more restrictive MAP EGR limits imposed by Consumers Power Cc=pany cn the reload G and reload G-1U fuels installed at the Big Rock Point Plant.
These questions are a result of a phone conversation with your staff on February 3, 1977 The questions involved explaining the basis for the self-imposed restrictive limits, the development of the restrictive limits, and the =cnitoring of the restrictive limits to ensure cc=pliance.
On Septe=ber 23, 1976, Consumers Power Cc=pany was informed by Exxon, that for the Exxon G-3 fuel, it had been discovered that the limiting break for unexpcsed fuel was approximately.25 ft2 "his was inconsistent with the earlier findings that the limiting break for the G and G-1U fuels was the Design Basis Accident (DBA).
Because the intermediate break was limiting for G-3, it was selected for the MAPLEGR versus exposure curves.
Since smaller breaks are not as sensitive to initial stored energy, this curve did not show the gradual increase with exposure that is seen with the DSA.
It was concluded that the G and G-lU curves vould probably exhibit the same tendency if evaluated at the intermediate break point. The decisien was made to reevaluate the MAPLRGR limits for reload G and reload G-lU fuels based upon the intermediate break size. The results of that analysis have been submitted as a proposed change to the Technical Specifications for the Big Rock Point Plant, Docket 50-155, License DPR-6, dated December 17, 1976.
However, in the interi=, it was determined by Consumers Pcver C0=pany that some more rectrictive set of MAPEGR curves be developed for the G and G-1U fuels. These more restrictive MAPEGR curves were generated utilizing the G-3 curves after correcting for the proper nu=ber of rods for both G and G-lU.
The actual MAPLHGR curves used in the ir Lerin basis consisted of the value for either the current Technical Specifications MAPLHGR or the cor-rected G-3 value, whichever was more conservative.
Enclosures 1 and 2 list the current Technical Specifications MAPLHGR limits, the proposed MAPEGR
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limitc, and the interi MAPEGE limits currently in effect for both G-1 and G-1U fuels.
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= On October 28,~1976 a Licencee Event Report was issued explaining the situa-tion-and indicating that_ Consumers Power Co=pany had'i= posed the more_re--
srct i tive limits.: It should be noted that since that date G-and G-lU fuels have been maintained within the self-imposed restrictive MAPLHGR limits, and it-is the. intent'of Consumers Power Company to continue operation bound by these limits until the Technical Specifications. changes are approved.
The primary method utilized for ensuring core parameters are maintained within their. Technical Specifications limits (MAPLEGR, MCHFR and Heat Flux) is GROK, a
- one-group diffusion theory code based on FLARE.- Power distribution calculations are performed based on actual core operatin6 conditions (rod patterns,,pover-
' level, core flow, etc). These calculations.are then adjusted to correlate vith power distribution measurements made by the insertion of flux vires into the core. The thermal hydraulic results of these calculations are_ then compared to Technical Specifications limits and a maximum allovable power level _is
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established. Out-of-core-instrumentation (ga==a compensated ion chambers) is calibrated to read 1005 power at the established maximum allovable power level,
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and an administrative limit is established to which the results of the heat balance are compared.
'The primary function of the in-core _ instrumentation is to determine the necessity for new flux vire calculations by observing trends or chan6es in power distribution.
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David A Bixel Nuclear Licensing' Administrator CC: JGKeppler, USNRC
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'Enclosura 1-I (
-MAPLHGR LIMITS FOR RELOAD G FUEL
-Exposure Current Tech.
Proposed Tech Interim
'(MW/ST)'
!&PLHGR 0
6.38 6.h53 6.38 21h 6.750 6.887'.
437 6.978--
885 6.929 1,758 1,814.
6.Th6-2,041 6.79-3,h9h 6.885 h,536 6.76 5,hh3 6.660 6.838 6,939 1
6.643 9,072 9,979 6.86 6.8h7 10,h22 13,608 6.97 6.867 13,938 6.629 14,515 6.621 18,144 19,051 6.95 6.905 21,022 25,h01 7 05 6.580 27,216 27,778 6.8h3 6.703 34,013
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Enclosura 2'
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MAPLHGR LIMITS FOR RELOAD ~G-1U FUEL Exposure Current Tech Proposed Tech Int erim'-
(!G/ST)
Spec MAPLHGR' Spec MAPLEGR
'MAPLHGR 0
6.ho 6.h91 6.ho 2lk-6.758 437 6.888 88h'
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6.960 6.86 907 6.86 1,769-6.970
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1,814
'6.87 6.87-3,37h
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6.887 3,545 6.983 h,536 6.90-
.5,hh3 6.837 7,085 6.987 9,072 T.05-6.819 10,690 7.019
- 1h,355 7.069 lh 515 -
T.25 6.805-18,1hh T.25 6.796 21,8h3 7.171 27,216 T.28 6.755-29,08h T.161 35,322-6.958
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50-IS$
f FILE NUM'ER NRC DISTR.lBUTION FOR PART 50 DOCKET MATERI AL j
FROM: Consumers Pwr Co DATE OF DOCU TO:
NRC -...
Jackson, Michidan D A Bixel DATE RECEIVED p WLfitE R
.ONOTORizED PR OP INPUT FORM NUMBER OF COPIES RECEIVED Co21GINAL gy NC LAS$3 p g E D One signed 8 QOPY 1
DESC RIPT ION ENCLOSU RE
-Ltr trans the following:
Response to NRC questions re MAPLHCR limits imposed by Consumers 'pwr for reload C & GlU, fuel.........
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Big ROCK Pt SAFETY FOR ACTION /INFORMATION Fmtrun 2-14-77 ehf ASSIGNED AD:
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PROJECT MANAGER:
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INTERN AL DISTRIBUTION V
REG FILE j SYSTEMS SAFETY PLANT SYSTEMS SITE SAF_EIY_&
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HEINEMAN TE_DESCO ENVIRO ANALYSIS
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SCHROEDER BENAROYA DENTON & MUT.T.FR
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/ GOSSICK & STAFF ENGINEERING IPPOLITO ENYIR0_ TECH.
MIPC MACARR.Y KIRIGOOD ERNST CASE KNICHT BALLARD I
HANAUER SIINEIL OPERATING REACTORS SPANGLER HARLESS PAE3L fKI STELLO SITE TECH.
PROJECT MANAGEMEttr REACTOR SAFETY OPERATING TECH.
CAMMILL BOYD ROSS
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SHAO HUIlMN HOUSTON ROS_ZTOCZY
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BAER PETERSON CHECK
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BUTLER SITE ANALYSIS MELTZ
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CRIMES VOLLMER HELTEMES AT & I B'JNCH SKOVHOLT SALTZMAN
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J. COLLINS RIITBERG KREGER EXTERNAL DISTRIBUTION CONTROL NUMBER
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