ML20127G650

Safety Evaluation Accepting Loading of 8x8 Fuel Assemblies in Core

ML20127G650
Person / Time
Site:	Monticello
Issue date:	03/30/1974
From:	James Shea, Ziemann D US ATOMIC ENERGY COMMISSION (AEC)
To:
Shared Package
ML20127G634	List: ML20127G631 ML20127G650
References
NUDOCS 9211170400
Download: ML20127G650 (3)

Text

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L UNITED STATES ATOMIC ENERGY C01EISS101[

SAFETY EVALUATION ET THE DIRECTORATE OF LICENSING NORTHER 1: STATES POWER COMPANY .

MONTICELIA) NUCLEAR GEliERATIIK; PLANT .

INSERTION OF 8x8 FUEL ASSE!BLIES IliTO MONTICELLO COR1:

AND, TESTING AT REACIOR POWE:1 LEVELS LESS THAN 1%

.IHTRODUCTIO;[

Uorthern States Powcr Company (USP) has requested approval (1) to insert 116 8x8 fuel assemblies into the core of the lionticello Nuclear Generating Plant. USP previously submitted a' proposed change to the Technical Specifications (2) to allow the use of Sx8 fuel assemblies in the Monticello core. The description and performance analysis of the Ox8 fuel assemblics had been suomitted by dSP(3) . Plant modifications to be completed during the March-April-May 1974 refueling outage were described by !;SP(5,6,7) and approved by the Directorate of Licensing (8) .

EVALUATIOji The Regulatory staff has evaluated the General Electric Licensing Report NEDO-20103, " General Design Information for General Electric Boiling Water Reactor Reload Fuel Connacacing in Spring 1974". and has determined (4) that the nuclear design parameters of the 8x6 fuel assemblies are similar

- to the 7:7 fuel assemblics previously loaded in the Monticello nuclear core and other boiling water reactors.

The calculational methods previously used to predict the nuclear char--

acteristics of the 7x7 fuel assemblics currently in use have been applied to the 8x8 assemblies and are considered adequately conservative to pro-vide assurance that the ex8 fuel can be accurately described as neutronically similar to the 7x7 assemblies. The 8x8 fuel assemblies can therefore be loaded into the Monticello core.

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Technical representatives of IISP and the Directorate of Licensing net (9) to review and clarify the modifications to be made during the apring 1974 refueling outage. Of particular interest was the ef fect of the new OFFIC E W 9211170400 740330 PDR ADOCK 05000263 P -PDR,, -.

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. 2-J blowdown pipe connections to the existing steam lines. This concern was resolved (10) catisf actorily by calculations that had been made by Bechtel which show negligible stresses and steam line movement resulting from the new steam blowdown line emnections. We have completed our evaluation of the nuclear steam supply system modifications (10) and have concluded that the proposed modifications are acceptable and that the integrity of the primary coolant pressuro boundaries have not been compromised (8).

With respect to reactor operation at power levels below 1%. ve noto fuel temperatures are greater than water temperatures by about 1% of the difference between fuel temperatures at 100% power icvel and the

aturated water temperature. Therefore, the fuel temperatures are sufficiently low that the stored energy is negligible and fuel clad teLxperatures following the DBA LOCA remain well below acceptaMe listits.

In fact, the peak claa temperatures would not be greater than about 450*F which is sufficiently low in contrast with the 2300*F in the Interim Acceptance Criteria for Emergency Core Cooling Syste=s for Licht Uater Reactors to assure negligible fuel damage and provides larc;e cargins with respect to emergency core cooling capability. Accordingly ,

the request to test at power levals up to 1% does not present a safety problem.

CONCLUSIONS _

iased upon the soove considerations, uo concluda that no aignificant hazards consideration la involved in loncing of 8x8 funi assemblics in the Ifouticello core and performing reutine cora measurements at power levels below 1% of rated. 'Je also have concluded that the health and safety of the public will not be endangered by this action.

N James J. Shea Gperating lienctors Dranen #2 Directorate of Licensing w\

Lennis L. ~1emann, Chief

-J Operating neactors Branch #2 Directorate of Licensing Date; u n . u 1974 omc s * ~ . . . . . . . . .

9 u 814 A M E h _

DATEb .m... t .

G*o c43 is *es.e s ae-s ea Fress AEC 318 (Rev. 9-53) AECM 0240

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) REFERENCES

1. WSP request for 8x8 Fuel loading and Testing Authorisation dated

! March 21, 1974. '

2. USP Technical Specification Change Ecquest date'd February 27, 1974.

3. 3SP Second Reload Submittal" dated November 19, 1973.

4. Directorate of Licensing 'Tachnical Report on the General Electric-Company 8x6. Fuel Assembly" dated February 5,1974.

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5. JSP submittal,. " Permanent Plant Changes to Accommodate Equilibrium 4

Core Scram Reactivity Characteristics", dated January 23, 1974.

6. NSP submittal, " Errata to January 23, 1974 Report . . . Permanent Plant Changes . . .", dated March 19, 1974.

- I 7. MSP submittal, " Supplement 1 to Janunty ' 23,1974 Report", dated March 8,1974.

S. Directorate of Licensing Approval of Plant Modifications for Fuel Cycle 3 dated March- 14, 1974.

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9. liinutes of meeting with NSP representatives on February 20 and 21,1974.

'Tlant nodifications"

' 10. Safety Evaluation by Directorate of Licensing

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dated March 14, 1974.

11. Minutes of meeting with NSP representatives on March'22,1974.

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