ML17255A384

Forwards Ginna Plant Criticality Safety Analysis for New Fuel Storage Racks & Responses to Questions on 820223 Request to Change Tech Specs to Permit Storage of Higher Enrichment Fuel at Facility

ML17255A384
Person / Time
Site:	Ginna
Issue date:	09/12/1983
From:	Maier J ROCHESTER GAS & ELECTRIC CORP.
To:	Crutchfield D Office of Nuclear Reactor Regulation
Shared Package
ML17255A385	List: ML17255A384 ML17255A386
References
NUDOCS 8309160055
Download: ML17255A384 (8)

Text

REGULATOR INFORh1ATION DISTRIBUTION

. TEM (RIDS)

ACCESSION'BR:S309160055 DOC,DATE: S3/09/12 NOj'ARIZED: NO DOCKET FACIL-50 244 Rober t Emmet Ginna Nucl"ear Plants Unit iP Rochester G

05000244 AUTH,NAME AUTHOR AFFILIATION MAIERPJ.E.

Rochester Gas,8 Electr ic Cor p.

RECIP ~ NAME RECXPIENJ AFFIL'IATION CRUTCHFIELDP 0 ~

Oper sting Reactors Branch. 5

SUBJECT:

Fdrwar ds "Ginna Plant Criticality 'Safetv.Analysis"for Nek Fuel Sabotage Racks" 8, nesponses to, guestions on, 830223 nequest to change Tech. Specs to-permit storage of<<

higher'nrichment fuel at:-facilitv.

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~ 89 EAST AVENUE, ROCHESTER, N.Y. 14649 YORK JOHN E. MAIER Vloo President TCLKPHONE

• nei cooc 7lo 546-2700 September 12, 1983 Director of Nuclear Reactor Regulation Attention:

Mr. Dennis M. Crutchfield, Chief Operating Reactors Branch No.

5 U.S. Nuclear Regulatory Commission Washington, D.C.

20555

Subject:

Change to Technical Specification 5.4.2 R. E. Ginna Nuclear Power Plant Docket No. 50-244

Dear Mr. Crutchfield:

On February 23, 1982 RGaE requested a change to the technical specifications to permit storage of higher enrichment fuel at Ginna.

Attached are our responses to several questions from members of the NRC Staff.

Very truly yours, John E. Maier Attachments 8309160055 830912 PDR ADOCK 05000244 p

PDR

Cg 0

w

Attachment 1

Q.

Since Technical Specification 5.4.2 refers to both new and spent fuel storage

racks, we need to perform an analysis for the fuel being stored in the new fuel storage racks under optimum moderation.

A.

The requested analysis is provided in Attachment 2.

2.

Q.

In the criticality analysis did we assume fuel of infinite axial length at the 4.25 weight percent enrichment'.

Yes.

A reactivity perturbation due to axial neutron leakage was calculated and added to the basic cell K infinity.

3.

Q.

Explain in more detail why the neutron multiplication factor increases above 68 F, but initially decreases for 0

pool water densities below 1 g/cc.

A.

The explanation of these results may be obtained by examining the calculated neutron balance as a function of energy for the conditions of interest.

By examining the k~ of the rack in the thermal neutron energy range only (k m.), it can be seen that nearly all the change in total rack km (k m

) can be attributed to changes in T

k~

over the limited water density and temperature range 4

of interest here.

c E'0

Even though in the case of increasing temperature the fuel assembly km decreases, rack k~

increases due to 4

the reduction in thermal neutron absorption in the water and stainless steel exterior to the fuel assembly.

The stainless steel absorption actually increases slightly but the water absorption decreases significantly.

Conversely, in the case of reducing water density at constant temperature, the fuel assembly k~

again decreases but k~

also decreases due to an increase in 4

neutron absorption in the water and stainless steel.

in the later case, the absorption in the water remains about constant but the stainless steel absorption significantly increases over the range of interest.

This difference in behavior in thermal neutron absorptions is due to the changes in thermal microscopic absorption cross sections

(~a

) which occur as the 4

result of changes in temperature and water density.

When the temperatuare is increased over the range of

~ 4

interest, there is a much larger reduction in ~ a for stainless steel and water than the reduction which occurs when only the water density is decreased.

Such changes have been verified by detailed analysis of the calculational results reported in the licensing sub-mittal.

4