ML19319D782

Nonroutine Rept 1:on 740921,during Zero Power Startup Testing,Ejected Rod Worth of 1.24% Measured W/Control Rods Positioned Near Tech Spec Rod Insertion Limit for Zero Power.Allowable Limit for Normal Operation Exceeded

ML19319D782
Person / Time
Site:	Oconee, Rancho Seco
Issue date:	10/18/1974
From:	Mattimoe J SACRAMENTO MUNICIPAL UTILITY DISTRICT
To:
Shared Package
ML19319D783	List: ML19319D782 ML19319D787
References
RJR-74-401, NUDOCS 8003250783
Download: ML19319D782 (4)

Text

'

4 AEC DISTRIBUTION FOR PART 50 DOCKE_T MATERI AL, (TEMPORARY FORM)

CONTROL NO: 10906 FILE:

FROM:

SMUD DATE OF DOC DATE REC'D LTR TWX RPT OTHER Sacramento, Calif 10-18-74 10-22-74 xxx ORIG CC l ON N E M """"

D e tor te of Licensing l

SENT LOCAL PDR xmxxxx CLASS UNCLASS PROPINFO INPUT NO CYS REC'D DOCKET NO:

xxxxxx m 1

50-312 DESCRIPTION:

ENCLOSURES:

Ltr Trans the Following:

Report: Ejected" Rod Worth Measurement'"

..... and a proposed change to the Tech-Spect p p 7 py m y, m % p/

vi.--. L,, w_. s J.T..L of the FSAR..... formal change will be bQ hg ng;,g y f PLANT N AME:

Rancho Seco Unit 1 FOR ACTION /INFORMATION 10-25-74 JGB BUTLER (L)

SCHWENCER (L) ZIEMANN (L)

REGAN (E)

W: Copies JjCopies W/ Copies W/ Copies CLAR K (L)

STOLZ (L)

DICKER (E)

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W/ Capies W/ Co !es W/ Copies W/ Copies PAR R (L)

VASSA LLO (L)

KNIGHTON (E)

THIS DOCUMENT CONTAINS W/ Copies W/ Copies W/ Copies W/ Copies P00R QUAllTY PAGES KNIEL (L)

PURPLE (L)

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W/ Copies W/ Copies W/ Copies W/ Copies INTERNAL DISTRIBUTION

[EGFffE-TECH REVIEW DENTON LIC ASST A/T IND EC PDR GRIMES BRAITMAN GC, ROOM P 506A SCHROEDER GAMMILL DIGGS (L)

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8. HURT CASE KNIGHT BALLARD ULBOURNE (L)

GIAMBUSSO PAWLICKl SPANGLER KREUTZER (E)

PLANS BOYD SHAO LEE (L)

MCDONALD

/OOR E (L) (BWR)

STELLO ENVIRO MAIG RET (L)

CHAPMAN DEYOUNG (L) (PWR)

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DUBE w/ input SKOVHOLT (L)

NOVAK UICKER SERVICE (L)

E. COUPE GOLLER (L)

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P. CO LLINS IPPOLITO YOUNGBLOOD SLATER (E)

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DENISE TEDESCO REGAN SMITH (L)

KLECKER

_G OPR LONG

\\ P,ROJECT L R TEETS (L)

EISENHUT FILE & REGION (3)

LAIN AS

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WI LLI AMS (E)

MORRIS BENAROYA HARLES WILSON (L) 4g STEELE VOLlMER o n n 9 9 2; O

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EXTERN AL DISTRIBUTION

- LOCAL PDR Sacramento, CA.

d-- T:C ABERNATHY) (1)(2)(10)- PIATIONAL LABS 1

PDR-SAN /LA/NY NSIC (BUCHANAN) 1 - ASLBP(E/W Bldg, Rm 529) 1 - BROOKHAVEN NAT LAB 1 - ASLB 1 - W. PENNINGTON, Rm E-201 GT 1 - G. ULRIKSON, ORN L 1 - Newton Anderson 1 - B&M SWINEBROAD, Rm E-201 GT 1 - AGMED (RUTH GUSSMAN)

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$SMUD SACRAMENTO MUNICIPAL UTILITY DISTRICT C 6201 S Street. Box 15830 Sacramento. Californis RJR 74-401

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October 18, 1974

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.l Director p,V' Directorate of Licensing

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-pe Office of Regulation Y!M M United States Atomic Energy Commission Washington, D. C.

20545 Re: AEC Docket No. 50-312 Rancho Seco Nuclear Generating Station, Unit flo.1 Non-Routine Report No. 1

Dear Sir:

The Rancho Seco Technical Specifications, Section 6.12.20.1, ruuire a urittcn ucrt.a aitnin thir-

'avs upon disco =^

e of any suostantial errors in ae transient or accident analyses, or in the methods used for such analyses, as described in the Final Safety Analysis Report or in the Technical Specifications.

In compliance with these specifications, we are enclosing a report titled " Ejected Rod Worth Measurement" and a proposed change to the Technical Specifications and the FSAR. A formal change will be submitted at a later date.

Sincerely yours, b3

'J.

. Mattimoe Assistant General Manager and Chief Engineer 9],,'>,

cc:

R. H. Engelken 03

~. :,A Director of Regulatory Operations, Region V g

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GGT 221974 > U RECULAT":"

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4

Ejected Rod Worth Measur'ement On September 21, 1974, during the Rancho Seco zero power startup

. testing, an ejected rod worth of 1.24% Ap was measured with the control rods positioned near the technical specification rod insertion limit for zero This value is in excess of the allowable limit of 1% ao for normal power.

operation (not applicable during testing) and disagre,ed with a prediction that the ejected rod worth would be approximately.9% Ap.

Following this measurement on September 21, 1974, with a discrepancy between the measured 1.24% ao and the predicted 0.3T as/4 at Rancho Seco, the Babcock and Wilcox Nuclear Engineering Group re-evaluated the data by performing additional calculations and developing the correlation shown in Figure 1 which shows j

the relationship between ejected rod worth and inserted rod worth, where the data points include all availsble calculations and measurements, including measurements of stuck rod worth.

The results of this correlation indicate excellent agreement between measurements and calculations.

It is also apparent from the shape of a curve that a prediction of ejected rod j

worth based on a linear fit of the data available for insert (d rod worth up to approximately 3% Ao would lead to an underestimate of ejected rod worth for greater amounts of inserted worth.

As a result of these measurements, it is necessary to modify the l

existing rod insertion limits to insure that the maximum potential ejected rod worth will be less than the 1% ao required for normal operation at 2

>525'F and zero power.

Based on the measured and predicted data shown in Figure 1, it has been decided to conservatively limit the maximum potential ejected rod worth to.85% Ao.

This corresponds to a maximum inserted rod worth of 3.8% 60 which would occur at a control rod insertion limit of 49%

withdrawn.on Bank 5 at >525*F and zero power.

Following this measurement in subsequent operations the maximum insertion of Group 5 control rods has been limited to 49% whenever the reactor is critical.

Consistent with this limitation, the attached pages 14.2-20 and 14.2-21 contain proposed changes to the Final Safety Analysis Report which shows that the 0.65%-oc/K ejected rod.being the worst case at power and for rod worths <1% 4K/K at zero powcr the thermal power

-transient is less.

Page 3-33a and Figure 3.5.2-1 contain proposed changes to the. Technical Specifications to restrict rod position limits on Control Rod Group 5 to greater than 49% at power levels up to 23%. The FSAR changes will be submitted formally as Amendment No. 29 and the changes to the Technical Specifications will be submitted formally within sixty d,ays.

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