ML19339A056
| ML19339A056 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 09/18/1974 |
| From: | Heider L YANKEE ATOMIC ELECTRIC CO. |
| To: | NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| WYR-74-26, NUDOCS 8010310692 | |
| Download: ML19339A056 (3) | |
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Mgi'g u.j Telephone 617 366-9011 rwx 710-390-0739 YANKEE ATOMIC ELECTRIC COMPANY urR 74-26 20 Turnpike Road Westbc.-ovgh, Massachusetts 01581
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Reference:
License No. DPR-3 (Docket No. 50-29)
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Dear Sir:
Yankee Atomic flectric Company submits the attached Unusual Occurrence Report relative to discrepancies between calculated and measured control rod worths for Core XI.
Supplemental information shall be forwarded on a timely basis to provide a conplete report.
We trust you will find this information satisfactory; however, should you desire additional information feel free to contact us.
Very truly yours, YANKEE ATOMIC ELECTRIC COMPAhT M IIO L. H. Heider
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Manager of Operations
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UNUSUAL OCCURRENCE REPORT Pursuant to our Technical Specifications and Regulatcry Guide 1.1.6, Rev.1, Yankee Atomic Electric Company submits the following unusual
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occurrence report.
On August 18, 1974, the analysis of Core XI start-up-physics measure-ments of control rod worths was completed, and indicated that measured centrol rod worths were less than the values reported in Sections 103 Nuclear Design, and 409 Steam Line Rupture Accident, of the FHSR as modified by Amendment No. 9.
Measured control rod worths were obtained with the aid of the Westinghouse reactivity computer and were confirmed by analysis of end point critical boren concentrations.
A review of the accident and transient analyses in the license, as modified by Amendeent No. 9, has been conducted. The review has shown that'the measured control rod worths exceed the worths used in the analyses of all events except a Steam Line Rupture.
In addition, peaking frctors as ceasured by the in-core instrumentation ere below the design values used in the accident analyses. Thus these analyses are still applicable to the core, with the exception of the Steam Line Rupture.
For the Steam Line Rupture accident, the measured rod worths are less than the values used in the analysis by no more than 0.9% ap. The review of this analysis indicated that even with the measured rod worths, the core will not return to critical during the course of the accident as long as the all-rods-out, full power concentration of boron is not less than 400 ppo.
(For lower concentrations, the moderator temperature coefficient of reactivity may become sufficiently negative so that the cooldown accompanying the accident introduces enough positive reactivity to return the core to criticality.)
Thus plant operation can proceed at full power down to an all-rods-out botoc cencentration of 400 ppm without re-analysis of any accidents. This boren concentration will not be reached for at least six months. Plant operation below 400 ppm all-reds-out critical boron will be addressed in a later report.
Investigations to determine the cause of the control rod worth discrepancies are being conducted and will be reported prior to December 1, 1974.
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AEC DISTRIBUTION FOR PART 50 DOCKET MATERI AL_
(TEMPORARY FORM)
CONTROL NO: 10137 FILE:
FRO!.1: tankee Atomic Elec. Co.
DATE OF DOC DATE REC'D LTR TWX RPT OTHER tiestborough, Mass. 01581 Mr. L.11. Heider 9-18-74 10-9-74 x
TO:
ORIG CC OTHER SENT AEC PDR xxx AEC 1 signed SENT LOCAL PDR CLASS UNCLASS PROP lNFO INPUT NO CYS REC'D DOCKET NO:
.U2 1
50-29 DESCRIPTION:
ENCLOSURES:
Ltr trans the following....
Abnormal Occurrence Report....on 8-18-74 concerning..... control rod worth discrepancic (1 cy encl rec'd)
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PLANT NAME:
Yankee Rowe FOR ACTION /INFORMATION 10-15-74 JB BUTLER (L)
SCHWENCER (L) ZIEMANN (L)
REG AN (E)
W Copies W/ Copies W/ Copies W/ Copies CLARK (L)
STOLZ (L)
DICKER (E)
LEAR (L)
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.t PAR R (L)
VASSALLO (L)
KNIGHTON (E)
W/ Copies W/ Copies W/ Copies W/ Copies KNIEL (L)
/ PURPLE (L)
YOUNGBLOOD (E)
W! Copies W/[ Copies W/ Copies W/ Copies INTERNAL DISTRIBUTION
[ REG FM TECH REVIEW DENTON LIC ASST A/T IN D AEC PDR GRIMES B R AITM AN
/OGC, ROOM P-506A /SCHROEDER GAMMILL DIGGS (L)
SALTZMAN
/pUNTZING/ STAFF /MACCARY KASTNER GEARIN (L)
B. HURT
/ CASE
/ KNIGHT BALLARD GOULBOURNE (L)
/PAWLICKI SPANGLER KREUTZER (E)
PLANS BOYD
/JHAO LEE (L)
MCDONALD MOORE (L) (BWR)
/STELLO ENVIRO M AIGRET (L)
CHAPMAN DEYOUNG (L) (PWR) e/ HOUSTON MULLER R EED (E)
DU BE w/ input SKOVHOLT (L)
/NOVAK DICKER SERVICE (L)
E. COUPE GOLLER (L)
/h0SS KNIGHTON
/ SHEPPARD (L)
P. CO LLINS
/IPPOLITO YOUNGBLOOD SLATER (E)
- D. THOMPSON (2)
DENISE
/TEDESCO REGAN SMITH (L)
- KLECKER
/RE_G OPR
V EISENHUT FILE & REGION (3) v" LAI N AS WILLI AMS (E'
/MOR RIS
/BENAROYA HAR LESS WILSON (L)
/STEELE
/VOLlMER EXTERNAL DISTRIBUTION I - LOCAL PDR
/1 - NSIC (BUCHANAN) 1 - ASLBP(E/W Bldg. Rm 529) 1 - BROOKH AVEN NAT LAB 1 - ASLB 1 - W. PENNINGTON, Rm E-201 GT 1 - G. ULRIKSON, ORN L
/ g Nev. ton AndersonACRS M9VW Sent to 1 - CONSULTANTS Rm B-127 GT 1 - B&M SWINEBROAD, Rm E-201 GT 1 -- AGMED (RUTH GUSSMAN)
Sheppard NEWMARK/BLUME/AGBABIAN 1 - R. D. MUELLER, Rm E-201 10-15-74 GT