ML19351A327

Proposed Tech Specs 6.1 Re Defueling Phase Document Design Features

ML19351A327
Person / Time
Site:	Fort Saint Vrain
Issue date:	10/13/1989
From:	PUBLIC SERVICE CO. OF COLORADO
To:
Shared Package
ML19351A325	List: ML19351A324 ML19351A326 ML19351A327
References
P-89395, NUDOCS 8910200042
Download: ML19351A327 (7)

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l ATTACHMENT 2 l

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.j PROPOSED CHANGES 4

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~ Fort St. Vrain #1 k

Technical Specifications L

Amendment No.

Page 6.1-5

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within the spacer blocks.

The middle layer of lower 7

reflector elements, excluding, the central element in each I

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core region, contains 25 weight percent boronated graphite pellets enclosed in hastalloy-X cans.

The top layer of i

reflector above the hexagonal columns contains I weight percent crushed boronated graphite.

The top layer of l

reflector above the permanent side reflector blocks a

contains I weight percent boronated graphite enclosed in steel cans.

l Defueling i

l Defueling elements containing no fuel and made from grade l

H-091 graphite, which is equivalent to the grade HLH l

graphite used for permanent side reflector blocks, will be l

used to replace fuel elements during defueling.

The l

defueling elements have the same outer dimensions as the l

fuel elements that they will be replacing.

All defueling

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elements are of the same design, regardless of whether they l

are used to replace standard fuel elements or control l.

column fuel elements from the central column of the region.

l Defueling elements do not have control rod channels o-I reserve shutdown holes.

(The control rods will not be l

reinstalled in a defueled region.) Each defueling element l

has ninety (90) coolant channels which will align with the l

coolant channels of the elements above and below.

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addition, twelve (12) holes are blind drilled and loaded l

with boronated graphite lumped poison pins (LPP), with a

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. Fort St. Vrain #1 Technical Specifications Amendment No, v

O Page 6.1-Sa

.l boron loading equivalent to about 350 ppm of homogeneous l

natural boron to replace the negative reactivity of the l

control rods, t

e ll The. essentially right circular cylindrical geometry of the

.ll core that is modeled in the GAUGE code will be retained ll during defueling.

The outer ring of fuel elements (Regions l' l 20-37) will be replaced with defueling elements first. The ll next most outer ring of fuel elements (Regions 8-19) will

-l l be replaced second The central regions of fuel elements ll (Regions 2-7 and 1) will be replaced last.

l The top layer reflectors may be replaced with reflectors l

not containing boronated graphite in selected regions l

during defueling to maintain neutron count rate.

Neutron i

l source material, Californium 252, will also be added as l

necessary to maintain a neutron count rate above the l

required minimum until a demonstration of suberiticality

'l has been perfermed in _which all control rods have been

.I withdrawn with a calculated k(eff) not greater than 0.95 1

assuming the conditions specified by SR 4.1.4 for SHUTDOWN

.l MARGIN determination. After the demonstration, the startup i

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channel low count rate rod withdrawal prohibit may be l

bypassed and the minimum count rate need not be maintained.

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However, the startup channel high count rate scram will l

remain in service to respond to any approach to I

criticality.

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Fort St. Vrain el l

,3 Technical SpecificaBions i

Amendment No, Page 6.1-Sb

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!f Basis for Specification DF 6.1 l

l The above specifications form the general design bases and j

l' criteria for the overall design' features of the reactor t

core 'which were used to evaluate its general performance.

Further details concerning these design features are given l

in Section III of the FSAR, the Safety Analysis Report for Fort St. Vrain Reload.1 Test Elements FTE-1 through FTE-8, l

General Atomic Document GLP-5494, June 30,1977, and the l

$afety Analysis Report For ' Reactor Defueling, General 1

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. Atomics Document GA-C19694, i,

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t ATTACHMENT 3 TO P-89395 NO SIGNIFICANT HAZARDS CONSIDERATION ANALYSIS l1 f l

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NO SIGNIFICANT HAZARDS CONSIDERATION ANALYSIS i

E.)

f BACKGROUND:

The defueling elements are constructed similar to fuel elements.

The defueling elements.contain lumped poison pins (LPP's) that replace

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.the negative reactivity'of the control rods.

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Shutdown margin will be maintained during defueling in accordance E ~

with Reactivity Technical Specification LCO 3.1.4, LC0 3.1.6, -SR f

4.1;4', and SR 4.1.6 similar to a refueling, j

The Safety-Analysis Report, GA-C19694, analyzed the FSAR accidents contained in Chapter 14 of the Fort St.

Vrain FSAR for potential 4

effects of defueling. All accidents during defueling were determined to be. bounded by current FSAR analysis or were no longer applicable, i.

The. analysis of earthquake, reactivity accident, column deflection and ' misalignment, misplaced fuel element, blocking of coolant L

channel, electrical incidents,. loss of normal shutdown cooling, i

moisture ingress, fuel storage accidents, and permanent loss of a

forced circulation (DBA-1) were determined to be bounded by current analyses. Another five accidents, all involving loss of primary I

coolant,~were determined.to be no longer applicable.

EVALUATION:

PSC has ' evaluated the proposed amendment request for.significant hazards consideration using the standards in ' Title 10, Code of Federal Regulations, Part 50.92.

The proposed amendment request involves no significant harards,'since the proposed amendment would not:

1.

Involve a significant increase in the probability or consequences of an accident previously evaluated.

i The reactor fuel elements will be replaced with defueling elements that contain boronated graphite and no fuel.

The startup. channels will continue to monitor core reactivity.

r The structural and thermal characteristics of the reactor will remain unchanged.

Procedures for removing the fuel r

elements will be maintained similar to a refueling.

The i n se'rtion of the defueling elements will also be similar to l'

a refueling except that the defueling elements will contain

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boron carbide, will not contain fuel, and control rods will l'

not be reinstalled. Adequate shutdown margin will continue to be assured in accordance with Ret.ctivity Technir.al Specifications LCO 3.1.4, LCO 3.1.6, SR 4.1.4, and SR 4.1.6.

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l The Safety Analysis Report, GA-C19694, analyzed the FSAR-accidents. contained in Chapter 14 of the Fort' St. Vrain '!SAR for potential effects of defueling. All accidents during 1

defueling were determined to be. bounded by current FSAR' 5

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' analysis: or yere. no~ longer applicable. The analysis of earthquake, reactivity a'cci dent, column deflection.

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misalignment, misplaced fuel. element, blocking of coolant

channel, electrical incidents, loss of normal shutdown cooling, moisture ingress, fuel storage accidents, and i

permanent loss. of forced circulation (DBA-1). were determined 1

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'to be bounded by current analyses. Another five accidents,

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<all. involving loss of primary coolant, were determined to be

- F no longer applicable.' '

L 2.

Create.the' possibility 'o f a new' or different' kind of I

accident from any accident previously evaluated, s

No significant change is being made to plant operation or

'I safety system operation as described in Item 1.

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Involve a significant reduction in a margin of safety.

I No significant change is being made to refueling procedures I

-(which will be used for defueling),

core-materials, reactivity monitoring systems, ' core structural design, or

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shutdown margin determinations as. described in Item 1.

Therefore, no significant change in any margin of safety is j

involved.

t CONCLUSION:

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Based on the above evaluation, it is concluded that operation (Defueling) of Fort St. Vrain in accordance with the proposed changes will involve no significant hazards consideration.

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