ML20024G618

Application for Amend to License DPR-22,expanding Specs to Govern Use of 8x8 Fuel Element

ML20024G618
Person / Time
Site:	Monticello
Issue date:	02/27/1974
From:	Larkin W NORTHERN STATES POWER CO.
To:
Shared Package
ML20024G615	List: ML20024G614 ML20024G618 ML20024G619
References
NUDOCS 9102130496
Download: ML20024G618 (7)

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UNITED STATES ATOMIC ENERGY CO DHSSION l l

l NORTHERN STATES POWER COMPANY Monticello Nuclear Generating Plant Docket No. 50-263 REQUEST FOR AUTHORIZATION OF A CHANGE IN TECHNICAL SPECIFICATIONS OF APPENDIX A PROVISIONAL OPERATING LICENSE NO. DPR-22 (Change Request Dated February 27, 1974)

Northern States Power Company, a Minnesota corporation, requests authorization for changes to the Technical Specifications as shown on the attachments labeled Exhibit A and Exhibit B. Exhibit A describes the proposed changes along with reasons for change. Exhibit B is a set of Technical Specification pages incorporating the proposed changes.

This request contains no restricted or other defense information.

NORTHERN STATES POWER COMPANY

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Wade Larkin Group Vice President - Power Supply

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On thisa/ day of /<!rr4e " / , /&,, before me a notary public in and for said County, persona 111 appeared Wade Larkin, Group Vice Presi-dent - Power Supply, and being first duly sworn acknowledged that he is authorized to execute this document in behalf of Northern States Power Company, that he knows the contents thereof and that to the best of his knowledge, information and belief, the statements made in it are true and that it is not interposed for delay.

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JOHN J. SMITH Nate9 Pd' . Fewayn Coun't M:eaceota W Counss.en Empno Marcl' 3.1976 9102130496 740227 3 DR ADOCK 050

EKRIBIT A IDNTICEL1D NUCLEAR CENERATING PIANT DOCKET NO. 50-263 CHANGE REQUEST DATED FE BRUARY 27, 1974 PROPOSED CHANCES TO THE TECHNICAL SPECIFICATIONS APPENDIX A 0F PROVISIONAL OPERATING LI CENSE NO. DPR-22 Pu r su ant to 10CFR50.59, the holders of the above-mentioned license hereby propose the following changes to Appendix A Technical Specifications.

1. PROPOSED CHANCES On pace 6, TS 2.3.A.1, line 4, change the words

". . . above the curve. . . " to ". . . above the applicable curve..."

on page 7, TS 2.3. A.1, expond the equation for the scram setting to two equations as follows:

"S = 486,000 P x (7x7 fuel) 3 425,000 P (8x8 fuel)"

X on page 7, TS 2.3.B. line 4, change the words ". . .above the curve..." to "...above the applicable curve..."

on page 7, TS 2.3.B. expand the equation for the rod block trip setting to two equations as fcllows:

"RB = 437,400 P (7x7 fuel)

A RB . 382,400 P (8x8 fuel)"

X REASON FOR CHANGE These proposed changes add the appropriate equations for the scram setting and rod block trip setting for the 8x8 fuel element design described in Reference 1. These equations are derived in the same manner as were the existing equations governing 7x7 fuel design.

EXHIBIT A 2

2. PROPOSED CHANGE On page 10, Figure 2.1.1, make the following changes:

Change ".. 16 5 3.08" to "...is less than or equal to the design value" Change "For Peaking Factors > 3.08" to "For Peaking Factors Greater than Design" Change ". . . Peaking > 3.08" to ". . . Peaking > DPF" Chante "PF = Peaking Factor > 3.08" to "PF = Peaking Factor" Add the words, "DFF = Design Peaking Factor

= 3.08 for 7x7 fuel

= 3.04 for 8x8 fuel" REASON FOR CRANCE As discussed in Reference 1, the design peaking factor of 8xS fuel is 3.04 relative to a design value of 3.08 for the 7x7 fuel element design.

3. PROPOSED l'LANGES On page 12, Figure 2.3.2, change the title to " Relationship Between Peak Heat Flux and Power for Peaking Factors of 3.05 (7x7 fuel)

• and 3.04 (8x8 fuel)"

On page 12, Figure 2.3.2, add a curve of the form and with the label, "X=354,250 P (8xS fuel)"

hfASON FOR CHANGE The additional curve reflects the design of 8x8 fuel as described in Reference

1. It is derived in the same manner as the existing 7x7 curve.

4. PROPOSED CHANCES On page 14, TS Bases 2.1, third paragraph, line 2, extend the sentence ending in "... total peaking factor of 3.08." to read

"... total peaking factor of 3.08 for 7x7 fuel and 3.04 for 8x8 fuel."

4 EXHIBIT A On page 14. TS Bases 2.1, third paragraph, lines 4 and 5, delete th words, "The total peaking factor is less than

3.08 if the control rod withdrawal sequence is followed.

l However," making the words read "...(LPRM) System. To 1

maintain..."

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On page 14 TS Bases 2.1, third paragraph, last line, change the words,

. . . peaking factor in excess of 3.08." to ". . . peaking factor

] in excess of the design value."

REASON FOR CllANCE As discussed above, these changes reference the characteristic peaking

factor of the Bx8 fuel design. The sentence removed from lines 4 and 5 is a generalization which is incorrect in certain situations. In par-l ticular, during plant startups with transient xenon conditions, the '

peaking factor is likely to exceed the design peaking factor at low reactor power levels. It is for this very reason that Specifications 2.1 and 2.3 make ,

provisions for peaking factors greater than design values for reduced reactor power levels.

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, 5. PROPOSED CHANGE On page 16 TS Bases 2.1, first paragraph, second line, change the woras, ". . . time constert of the fuel which is 8-9 seconds."

to read, " time constant of the fuel."

! Rr.ASON FOR CilANGE i

Stating a numerical value for the fuel time constant of a given fuel design is an over-simplication of the heat transfer mechanism. Extensive discussions of this subject is found in Reference 2 where the effects of fuel pellet

density, gap size and conductance, stored energy, etc., are considered.

6. PROPOSED CHANGES

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l On page 19, TS Bases 2.3.A, third paragraph, expand the phrase,

". . . peaking factor of 3.08." to read ". . . peaking factor of 3.08 for 7x7 fuel and 3.04 for 8x8 fuel."

On page 19 TS Bases 2.3. A, third paragraph, third line, change the number "3.08" to read "the design value."

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On page 19, TS Bases 2.3. A, third paragraph, sixth line, change the number "3.08" to read "the design value."

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EXHIBIT A 4

On page 19, TS Bases 2.3. A. third paragraph, change the last sentence to read, "If the APRM scram setting should require a change due to an abnormal peaking condition, it will be done by increasing the APRM gain and thus reducing the slope and intercept point of the flow-biased scram curve by the reciprocal of the APRM gain change."

REASON FOR CHANGES Changes are proposed, as appropriate, to acknowledge the unique peaking factors of 7x7 and 8x8 fuel as discussed in Reference 1.

A change is proposed in the way settings are altered to allow operation with peaking factors in excess of design values. By increasing the gain on an APRM to an artifically high reading, one is in effect lowering both the scram and rod block settings by the same factor. This method adjusts the scram curve in the same manner as the safety limit is adjusted for operation with excessive peaking factors.

For exampic, looking at the safety limit for 7x7 fuel (page 10), suppose the short term peaking factor exceeds decign by the factor k such that k = PF/3.0S. The APRM gain would then be increased such that indicated power, P, would be P (indicated) = k x P- (actual). This, in effect, would decrease the scram and rod block settings (required by Specification 2.3. A.1) to S S (1/k) x (0.65 W + 55.0); RB s(1/k) x (0.65 W + 43.0) . The slopes of these curves would therefore change in the same manner as the safety limit curves (page 10); that is, SL = (1/k) x Slo.

7. PROPOSED CHANGES On page 21 TS Bases 2.3.B, first paragraph, line two, expand the words, ". . . peaking factor was 3.08" to read " peaking factor was 3.08 for 7x7 fuel and 3.04 for 8x8 fuel."

On page 21, TS Bases 2.3. B, first paragraph, fif th line, replect the number "3.08" with the words "the design value."

On page 21, first paragraph, change the last sentence to read, "The rod block setting is changed by increasing the APRM gain and thus reducing the slope and intercept point of the flow-biased rod block curve by the reciprocal '

of the APRM gain change."

REASON FOR CRAhGES 1

These proposed changes acknowledge the unique peaking factors 7x7 and 8x8 fuel as discussed in Reference 1.

Item 6, above, discusses die proposed method for adjusting the scram setting when peaking factors exceed design. That discussion is equally applicable to the rod block setting referenced in this item.

4 EX11TBIT A

8. PROPOSED CilANCES On page 190, TS 5.1. A. change the name " Great Northern Railway." to "Burlington Northern Railway."

REASON FOR CilANCE The consolidation of railroad compsnies has led ta a new name for the company holding the right-of-way discussed.

9. PROPOSED CilANGE on page 190, TS 5.2. A, change the Specification to read, "A. The reactor core shall consist of not more than 484 fuei assemblies of 49 or 63 fuel rods each."

REASON FOR CllANCE This proposed change incorporates the 8x8 fuel design into the discussion of reactor design features.

REFERENCES

1. "Second neload Submittal," L 0 Mayer (ESP) to J F O' Leary (USAEC),

November 19, 1973.

2. General Electric topical report NEDO-20181, Revision 1, "GEGAP-III:

A Model for the Predection of Pellet-Cladding Thermal Conductance in BRR Fuel Rods," November 1973.

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t EXHIBIT B i

2 This exhibit consists of the following pages revised to 3 incorporate the proposed changes:

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PAGES 6 '

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10 I 12 14 16

! 19 21 i 190 1

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