ML18348A698

Letter Addendum to Cycle II Start-Up Report

ML18348A698
Person / Time
Site:	Palisades
Issue date:	04/29/1977
From:	Hoffman D Consumers Power Co
To:	Schwencer A Office of Nuclear Reactor Regulation
References
Download: ML18348A698 (8)

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consumers Power company General Offices: 212 West Michigan Avenue, Jackson, Michigan 49201

• Area Code 517 788-0550 April 29, 1977 Director. of Nuclear Reactor Regulation Att:

Mr: Albert Schwencer,. Chief Operating Reactor Branch No 1 US Nuclear Regulatory Commission Washington, DC 20555 DOCKET 50-255 - LICENSE DPR PALISADES PLANT - ADDENDUM TO CYCLE II ST.ART-UP REPORT On August 30, 1976 we transmitted "Palisades Plant Special Report No 9, Cycle II Start-Up Report" which was amended by our November ll, 1976 letter.

The attached report is an addendum to the Cycle II Start-Up Report.

David P Hoffman (Signed)

David P Ho f:f'ma.n Assistant Nuclear Licensing Administrator CC:

JGKeppler, USNRC

ADDENDUM TO CYCLE II ST.ART-UP REPORT Palisades Plant February 25, 1977

ADDENDUM TO PALISADES CYCLE II START-UP REPORT The measured reactivity worths reported in the Palisades Cycle II start-up report were significantly smaller than the calculations predicted. It has been found that much of the error can be attributed to an underestimate of the effective delayed neutron fraction, Seffective' which has a direct bearing on measured reactivity worths.

Seff was originally computed using delayed neutron data from Reference 1 which was published in 1965 and used in the industry for many years.

However, more recent evaluations based on measurements performed over the last ten years, such as the one in Reference 2, show a significant increase in the values of delayed neutrons per fission for all the important isotopes of uranium and plutonium.

Seff was recalculated using the data from Reference 2 yielding a value of.00727 versus the old value of.00690, representing an increase of 5.4%.

Since Seff is used to convert reactivity in cents from the reactivity computer to % 6p, this change represents a 5.4% increase in the measured reactivity worths.

It was found that, upon applying this correction, the measured values of dropped rod worth, ejected rod worth, moderator temperature coefficients and soluble boron worth are all still within the pre~etermined acceptance criteria.

However, the differences between the measured and predicted control rod bank worths, which previously had exceeded the acceptance criteria, are significantly reduced.

Table 1 showing_ the corrected rod bank worths compared to calculated values is similar to Table 5 from the start-up report.

As can be seen from the table, the differences between the revised measurements and calculations for the individual rod bank worths (4 through B) are within the acceptance criteria of either 0.2% 6p or 15% difference and the total rod worth is within the acceptance criterion of 10%.

The revised measured total rod worth when factored into the shutdown margin table results in a 0.43% 6p increase in net shutdown rod worth at end of cycle.

The attached Table 2 is similar to Table 6 containe~ in the start-up report.

. This increase results in 36 inches more allowable control rod insertion at zero power.

Unfortunately, the allowable insertion is still not within the envelope outlined by the Technical Specifications PDIL curve because of the 10% uncertainty penalty on the measurement.

The new PDIL curve is shown as Figure 1.

The sharp drop at about 75% of Group 3 is where the shutdown margin curve inter-sects the existing Technical Specifications curve.

Because the power defect assumed in this analysis conforms to our submittal regarding operation at in-creased pressure, the curve is applicable to 2100 psi operation as well as 1800.

Table 1 Measured Group Rod Worths Control Rod Measured Calculated Difference/

Group Worth Worth Difference Calculated, %

4

.66

.70

-.04 7 3

.91

.95

-.04

-4.2 2

.84

.72

+.12

+16.6 1

1.92 2.20

-.28

-12.7 Total Regs 4.33 Regs (Overlap).

4.20 Regs (Average) 4.26 4.57

-.31

-6.8 B

1.54

1. 55

....;..01

-0.6 Regs + B 5.80 6.12

-.32

-5.2 A

3.19*

3.37

-.18

-5.3 All Rods 8.99 9.49

-.50

-5.3

• The Group A worth was estimated from the calculation and the total observed calculation/measurement difference for Groups 1, 2, 3, 4 and B.

3.37 x (1 -.052) = 3.19

e e

Table 2 Palisades Cycle II SJ:m.tdown Margin BOC EOC HZP HE'P HZP HE'P Total Measured Full. Length Rod Worth 8.99 8.99 9.15*.

9.15*

stuck Bod Worth 3.22 3.22 3.52 3.52 Total Minus Stuck Rod 5.77 5.77 5.63 5.63 Uncertainty

.58

.58

.56

.56 Net Shutdown Rod Worth 5.19 5.19 5.07 5.07 Doppler Def'ect 0

1.00 0

l.00 Moderator Temperature.

0

.20 0

.80 Moderator Void Def'ect 0

0 0

.10 Axial Flux Redistribution 0

0 0

.50 Required Shutdown Margin 3.40.

2.00 3.40 2.00 Total Reactivity Allowances 3.40 3.20 3.4o 4.40 Available For Maneuvering l.79 l.99 1.67 0.67.

PDIL Rod Insertion l.43 0.07 l.67 0.15 Excess Margin 0~36 1.92 o.oo 0.52 BOC Measured

• EOC Rod Worth = EOC (Calculated) x BOC calculated

. I

. e Table 3

• ~*..

Palisades PDIL Calculation for End of Cy'cle II Net Shutdown Required Sum of Allowable Rod Rod Power Rod Worth Margin Power Defects*

! Insertion Position Insertion

%At' AE1

%Ae

---

% Ae ___ --- -- in.

0 5.07 3.4o 0

1.67 3@ 24 3 @ 81.8 10 5.07 3.26 0.24 1.57 3@ 31 3 @ 76.5 20 5.07 3.12 o.48 1.47 3@ 39 3 @70.5 30 5-.07 2.98-0.72 1.37 3@ 48 3 @ 63.6 4o 5.07 2.84 0.96 1.27 3 @ 57 3.@ 56.8 50 5.07 Z~70 1.20 1.17 3 @ 68 3 @ 48.5 60 5.07 2.56 1.44 1.07 3@ 76 3 @ 42.4 70 5.07 2.42 1.68 0.97 4@ 05 4 @ 96.2 80 5.07 2.28 1.92 0.87 4@ 13

• 4@ 90.2 90 5.07 2.14-2.16 0.17 4@ 21 4 @ 84.1 100 5.07 2.00 2.40 0.67 4@ 30 4@ 17.3

• Doppler+ Moderator Temperature-+ Void +_Axial Flux Redistribution

• ~

. 60

~

0 a..

40 0

0 20 PALISADES PLANT CONTROL ROD INSERTION LIMITS ALLOWABLE POWER LEVEL (% OF 2200 MW) vs CONTROL ROD INSERTION (o/o) BY ROD GROUP 40 60 80 100 0

©

. 0 -- --

.. 20

.40

... -- 60. -

CONTROL __ ROD INSERTION _ o/o

• • - -**---- __ Figure l __

20 40 80

. 100

References

l. G R Keepin, Physics of Nuclear Kinetics, Addison-Wesley, MA (1965)

2.

R J Tuttle, "Delayed-Neutron Data for Reactor Physics Analysis",

Nucl. Sci. *and Eng., 56, p 37,'.~ {1975).

3.

D A Bixel to J G Keppler, "Palisades Plant Special Report No. 9, Cycle II Startup Report, August 30*, 1976.

4.

D A Bixel to A Schwencer, "Palisades Plant - SpeciaJ. Report No. 9, Revision of Table 6, November 9, 1976 *