ML20216B847
| ML20216B847 | |
| Person / Time | |
|---|---|
| Site: | Callaway  |
| Issue date: | 06/18/1987 |
| From: | UNION ELECTRIC CO. |
| To: | |
| Shared Package | |
| ML20216B514 | List: |
| References | |
| ULNRC-1534, NUDOCS 8706300165 | |
| Download: ML20216B847 (10) | |
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- ULNRC-15 34 L..
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PROPOSED TECHNICAL" SPECIFICATION' CHANGE,
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' REACTIVITY CONTROL SYSTEMS N.
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. SHUT 00WN R00' INSERTION LIMIT I
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l-LIMITING CONOITION FOR OPERATION i
3.1.3;5 All shutdown rods shall be ftrHy withdrawny :2.25" sTefs or 4 l'<c.
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ApPLICA8!LITY: MODES 1".and 2*#.
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ACTION:
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With a maximum of one shutdown rod not feHy-withdrawg except for surveillance j
testing pursuant to Specification 4.1.3.1.2, within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> either:
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thdraw'the re d M N 5,of er;. o r-f b.
Declare the rod'to be inoperable'and apply Specification 3.1.3.1.
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..SUAVEILLANCE REQUIREMENTS l.
Each shutdown rod shall-be detsrmined to be fatty withdrawny 227. ac/f or Ahem f
4.1.3.5 WIthin 15 minutes prior to withdrawal of any rods in Control a.
Bank A, 8, C. or 0 during an approach to reactor criticality, and j
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At least once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> thereafter.
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"See Special Test Exceptions Specifications 3.10.2 and 3.10.3.
- With K,ff greater than or equal to 1.
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1 CALLAWAY - UNIT 1 3/4 1-20
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20 40 60 80 100
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~ R ATED ' THERM AL PC WER (Perc en t) s
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1 FIGURE 3.1-1 i
1 ROD BANK INSERTION LIMIT 5 VERSUS
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RATED THERMAL POWER - FOUR LOOP OPE?.ATION i
' CAL'LAWAY 1-UNIT 1.;
3/C 1-L2 M ex en No-U
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REVISION 2
HFAClIV!lY CONIROL SYSitM5 g.
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l BORATION SYSTEMS (Continued)
With the RCS temperature below 200*F, one Boration System is acceptable 1
without single failure consideration' on the basis of the stable reactivity l
condition of the reactor and the additional restrictions prohibiting CORE ALTERATIONS and positive reactivity changes in the event the single Boron l
Injection System becomes inoperable.
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The limitation for a maximum of one centrifugal charging pump to be OPERABLE and the Surveillance Requirement to verify all charging pumps except i
the required OPERABLE pump to be inoperable in MODES 4, 5, a..d 6 provides assurance that a mass addition pressure transient can be relieved by the operation of a single PORV or an RHR suction relief valve.
i The boron capability required below 100*F is sufficient to provide a i
e SHUTDOWN MARGIN of 1% ah/k after xenon decay anil cooldown from 200*F to 140 F.
This condition requires either 2968. gallons of 7000 ppm borated water from the l
boric acid storage tanks or 14,076 gallons of 2000 ppm barated water from the RWST.
m The contained water volume limits include allowance for water not available a
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because of discharge line location "d other physical characteristics.
Q The limits on contained water volume and boron concentration of the RWST I
also ensure a pH value of between 8.5 and 11.0 for the solution recirculated This pH band minimizes the evolution of within Containment after a LOCA.
lodine and minimizes the effect of chloride and caustic stress corrosion on mechanical systeins and components.
t The OPERABILITY of one Boration Systern during REFUELING ensures that this syst.em is available for reactivity control while in MODE 6.
3/4.l.3 MOVA8LE CONTROL ASSEMBLIES 1
The specifications of this section er'sure tbst:
(1) acceptable power I
distribution limits are maintained. (2) the minimum SHUTOOWN MARGIN is main-i Lained. and (3) the potential ef fects of rod misalignment on associated acci-OPERAS!LITY of the control rod position indicators dent analyses are limited.
i<. required to determ!ne control rod positions and thereby ensure compliance rnd alignment and insertion limits. Verification that the with t.he contrb Dinital Rod Positiun Indicator agrees with the demanded position vithin t 12 l
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d 18, 24, 48, 120 and 228 steps withdrawn for the Control Ban s an t, Lops.it 210 and 228 steps withdrawn for the Shutdown Banks provides assurances that the Oigital Rod Position Indicator is operating correctly over the full range of Since the Digital Rod Position System does not indicate the actual indication.
3 indi-shutdown rod position between 18 steps and 210 steps, only points in -
rances are picked for verification of agreement with demanded p af tf on.
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CALLAWAY - UNIT 1 8 3/4 1-3
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L, ULNRC-153 4 t
Attcchmsnt 2 i
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SAFETY EVALUATION i
l This safety evaluation is in support of a license amendment L
request to revise Technical Specification Limiting Condition for j
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Operation (LCO) 3.1.3.5, Surveillance Requirements 4.1.3.5, Bases L
3/4.1.3,. and Figure 3.1-1,
" Rod Bank Insertion Limits Versus Rated Thermal Power-Four Loop Operation."
The revision would L
allow control and shutdown rod banks to be repositioned for fully withdrawn at 225 steps or higher with rod bank overlap and
. insertion limits remaining the same.
These changes are contained in Attachment 1.
BACKGROUND Callaway Plant must operate with all shutdown rods fully withdrawn and control banks fully withdrawn in accordance with i
Fig. 3.1-1.
As currently indicated in Figure 3.1-1, the fully j
withdrawn location for a rod bank is 228 steps.
Per Westinghouse j
recommendations and based on data collected from other Westinghouse plants with control rodlet wear prcblems, the RCS is
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monitored for the presence of rod absorber material to give early detection of significant control rodlet wear prior to operational J;
problems.
Through monitoring at Callaway, hafnium has been found i
in the RCS indicating the probable wear-through of control rod l
cladding.
When rod wear is indicated, the recommendations
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include axially repositioning the shutdown rods to extend life and continued operation until replacements are obtained.
The mechanism for dispersion of absorber material into the coolant is by fretting against the upper internals guide surfaca due to flow induced vibration.
Axial repositioning moves the worn clad away j
j from the guide plate, thus minimizing any significant loss of J
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absorber material and eliminating further cladding degradation at
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wear scar elevations.
KVALUATION.
The proposed change involves revising the Technical Specifications to allow operation with the rod banks repositioned to 225 steps or higher for fully withdrawn, instead of at 228 steps fully withdrawn.
At 225 steps, the rods.are less than 0.3 inches into the active core.
Since the top of the core is a very L
low reactivity worth region, the small insertion difference between fully withdrawn at 225 and 228 or greater will have a minimal effect on power distributions.
Based on core calculations and measured power distributions for the past and the current cycle, F is expected to increase by less than one percent in the bottok of the core, and the axial offset will be more negative by less than one percent.
Callaway has sufficient peaking facter margin to cover both of these effects.
l The impact on shutdown margin (SDM) is also expected to be
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slight.
Since the rod banks would be positioned 0.3 inches into the active core (at 225 steps), the SDM will be slightly reduced.
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However, based on core calculations, this reduction can be conservatively estimated as 0.02% Ao at both the beginning-of-j life (BOL) and end-of-life (EOL).
Callaway has substantial excess shutdown margin and can accommodate a slight reduction in available rod worth of 0.02% Ap.
For example, the calculated j
Cycle 2 excess shutdown margins (accounting for the worst stuck rod) at BOL and EOL are 1.95% Ap and 0.61% Ajo respectively.
These values are substantial compared to a slight reduction in worth of 0.02% Ap.
i The impact of repositioning the rod banks at 225 steps fully withdrawn hns a negligible effect on accident condition peaking racLcrs anc rod worths.
Sufficient margin exists between the calculated values and the safety limits to accommodate any slight changes in these parameters.
In addition, repositioning the rods at 225 steps fully withdrawn will have either negligible or no effect on DNBR margin.
The parameters which effect DNBR are flow, temperature, pressure, and power (heat transfer rate).
The first three
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parameters are not impacted by rod position.
Since the rods l
would only be positioned 0.3 inches (at 225 steps) into the core periphery, the insertion would not be deep enough to 4
significantly impact the power component of DNBR.
CONCLUSIONS Since sufficient margin exists between calculated safety parameters and safety limits, repositioning the rod banks at 225 steps or higher for fully withdrawn will not increase the l
probability or the consequences of any analyzed accident in the Final Safety Analysis Report.
In addition, the margin of safety as defined in the Technical Specifications will not be reduced.
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Repositioning the rods does not involve the addition of a new
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plant system or significantly alter the operation of the current system.
Thus, the possibility of an accident or the malfunction j
of equipment important to safety, which is different than already i
evaluated in the Final Safety Analysis Report, will not be created.
Finally, repositioning rod banks will reduce the possibility of wear-through on the hafnium rodlet cladding.
Thus, the consequences and possibility of a malfunction of the rods will be decreased and functional requirements are maintained.
Based upon the above evaluations, this amendment request would not adversely affect or endanger the health and safety of the general public and does not involve an unreviewed safety question.
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ULNRC-15 34 Attachm:nt 3 SIGNIFICANT HAZARD EVALUATION l
l This significant hazard evaluation is in support of a j
license amendment request to revise Technical Specification j
Limiting Condition for Operation (LCO) 3.1.3.5, Surveillance l
Requirements 4.1.3.5, Bases 3/4.1.3, and Figure 3.1-1," Rod Bank j
. Insertion Limits Versus Rated Thermal Power-Four Loop Operation."
I The revision would allow the rod banks to be repositioned for i
fully withdrawn at 225 steps or higher with rod bank overlap and l
insertion limits remaining the same.
In accordance with 10CFR50.92, Union Electric Company has reviewed the proposed changes and has concluded they do not involve a'significant hazards consideration.
The basis for this conclusion is that the three criteria of 10CFR50.92(c) are not compromised, a conclusion which is supported by our determinations made pursuant to 10CFR50.59.
The proposed change does not involve a significant hazards consideration because the change would not:
i 1.
Involve a significant increase in the probability or consequences of accident previously evaluated.
Repositioning the rod banks at 225 steps or higher for fully withdrawn has been evaluated to have negligible impact on power distributions, shutdown margin, accident peaking 3
factors and rodworths, or DNBR margin.
Sufficient margin exists between calculated safety parameters and safety limits to accommodate slight variations in calculated values over previous analyses.
Repositioning the rod banks will reduce. localized. wear, extend life, and decrease any consequences or possibility of malfunction.
2.
Create the possibility of a new or different kind of l
accident from any previously evaluated.
There are no new failure modes associated with repositioning the rod banks.
A design change or a new plant system is not required.
The rods continue to meet their functional requirements, and operation of the curront system is unaltered.
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3.
Involve a significant reduction in a margin of safety.
l Callaway has sufficient margin between calculated safety parameters and safety limits to accommodate slight variations in parameters due to repositioning the rods.
There is no significant reduction in the shutdown margin,
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peaking factors, or DNBR margin.
Moreover, the Commission has provided guidance concerning g
the application of standards in 10CFR50.92 by providing certain i
examples (March 6, 1986, FR7751) of amendments that are considered not likely to involve significant hazards j
consideration.
The proposed change is conservatively enveloped by the specific example of a cha..ge which either may result in some increase to the probability or consequences of a 3
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, - ;previously-analyzed accident or may reduce in some-way a safe'ty.-
margin, but.where..the results of the change are_ clearly within all acceptable criteria with-respect to the system or component specified in the Standard Review Plan.
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In conclusion,.the proposed license amendment does not involve a significant hazard consideration.
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