ML17341A887
| ML17341A887 | |
| Person / Time | |
|---|---|
| Site: | Turkey Point  |
| Issue date: | 02/10/1982 |
| From: | Robert E. Uhrig FLORIDA POWER & LIGHT CO. |
| To: | Varga S Office of Nuclear Reactor Regulation |
| References | |
| L-82-49, NUDOCS 8202180142 | |
| Download: ML17341A887 (20) | |
Text
REGULATORY FORMATION DISTRIBUTION S't
-M (BIDS)
ACCESSION NBR:8202180142 DOC ~ DATE: 82/02/10 NOTARI'ZED:
YES DOCKET FACIL:50-250 -Turkey Point *Planti 'Uni:t 3i Florida Power =and Light C
05000250 50"251 Turkey Point ~Planti Unit 4i Florida 'Power and Light C
05000251 AUTH BYNAME AUTHOR AFFILIATION UHRIGi R ~ E ~
Florida Power L Light Co, R EiCI P ~ NAME REC IP IENT A F F IL'IA'TI ON VARGAiS ~ A, Operating Reactors Branch 1
SUBJECT:
For wards response to NRC 820121 request for addi info re
,proposed license amend for removal of boron in)ection tanks Info provided re LOFTRAN analysesiproposed hardware mods 8
reactiviity feedback results'ISTRIBUTION CODE:
A001S
~COPIES RECEIVED:LTR.J ENCL./
SIZE:
~4 TITLE: General Distri'bution for after Issuance of.Operating License NOTES:
RECIPIENT ID CODE/NAME ACTION ORB 01 BC 01 INTERNAL: ELD NRR/DHFS DEPY08 RR OPAB EG FIL 04 EXTERNAL: ACRS 09 NRC PDR 02 NTI'S
~COPIES LTTR ENCL 13 13 1
0 1
1 1
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1 10 10 1
1 1
1 RECIPIENT ID CODE/NAME IE NRR/DL D IR NRR/DS I/RAB LPDR NSIC 06 03 05 COPIES LTiTR ENCL
'2 2
1 1
1 1
1 1
1 1
TOTAL NUMBER OF COPIES l)EQUIRED:
L'TTR 35 ENCL 33
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.O. BOX 529100 MIAMI,F L 33152 Err'"~i FLORIDAPOWER & LIGHTCOMPANY February 10, 1982 L-82-49 Office of Nuclear Reactor Regulation Attention:
Mr. Steven A. Varga, Chief Operating Reactors Branch gl Division of Licensing U.
S. Nuclear Regulatory Commission Washington, D.C. 20555
Dear Mr. Varga:
Re:
Turkey Point Units 3
8 4 Docket Nos. 50-250 5 50-251 Proposed License Amendment Removal of Boron Injection Tank t;C This letter responds to your request for additional informatio January 21, 1982 regarding the subject license amendment.
On February 1.
1982 and on February 8, 1982, we provided verbal responses to your Mr. Jack Guttman.
Attached to this letter are our formal responses.
Should questions remain after your review of these responses, please contact us at your earliest convenience.
Very truly yours, Robert E. Uhrig Vice President Advanced Systems 8 Technology REU/SHS/cab Attachment ool S
cc:
J.
P. O'Reilly, Region II Harold F. Reis, Esquire 8opoie p"oR ~oociP e>ohio
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1 A 1:
Page 2.1.6 References the K ~f versus temperature reactivity utilized in the LOFTRAN code.
fhe Keff referenced was for 1000 psi.
Confirm that the LOFTRAN analyses ut>lazed other tables at the appropriate pressures during the postulated events.
In LOFTRAN, the reactivity is computed as a function of power, coolant density.
boron concentration, etc.
The Keff is not an input to LOFTRAN.
Therefore, the effect of. pressures.
other than 1000 psi, is considered when the effect on reactivity caused by moderator conditions are evaluated.
This item is discussed in detail in WCAP-7878, section 5.2 and 5.3.
Q 2:
A 2:
What were the limiting single failures used in the analyses'e.g.,
,Pg. 2.1.6-4 states 2 SI pumps were assumed operational).
The single failure assumption made in the safety analysis report was the failure of one safeguards train (minimum safeguards) to deliver borated safety injection water to the reactor coolant system.
As stated in section 14.2.5 of the FSAR, minimum safety injection capability corresponding to two out of four safety injection pumps in operation is considered.
For more detail, see WCAP-9226.
This single failure was assumed for both the case with and without the boric acid tank.
Q 3:
Provide a schematic diagram of the system, as presently designed, and another with the proposed hardware modifications (bypassing the BIT tank).
A 3:
On 2/4/82 FPL telecopied copies of plant drawings showing the BIT
- system, as presently
- designed, and marked-up plant drawings showing the proposed modified configuration as well as an alternate, administratively modified, configuration.
In a conference telephone call on 2/8/82, FPL answered NRC's questions on these drawings.
Q 4
~
A 4:
Page 2.1.6-12 states
-"The power transient shown in Figure 2.1.6-8 is conservative due to the underprediction of the feedback in the low flow condition."
- Discuss, in detail, the reasons as to why underprediction of the reactivity feedback results in a conservative predi cti on.
In low flow condition (see the answer to question 5), the cooldown is slower, resulting in stronger negative feedback.
LOFTRAN underpredicts the negative temperature feedback.
- Hence, higher power levels are predicted compared to power levels calculated by 3-dimensional neutronics codes.
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Q 5:
A 5:
'Provide details as to why the steam line break event, with offsite power available,. is limiting over the same event with offsite power not available.
It is our understanding that LOFTRAN utilizes the broken loop cold leg temperature when evaluating the moderator temperature reactivity feedback.
Since the primary coolant residence time through the steam generator is extended during the loss-of-oftsite power event, the moderator temperature at the stuck rod sector of the core could result in a more limiting condition for DNBR considerations.
Oescribe why this event is not limiting and how LOFTRAN conservatively evaluates the consequences of this event.
LOFTRAN uses a weighted temperature in evaluating the moderator temperature reactivity feedback.
This is explained in the response to question 6.
Q 6:
On the steam break event, with loss of offsite power, the reactor coolant pumps start to coast down, resulting in reduced primary coolant flow.
The lower reactor coolant flow decreases the heat transfer coefficient in the steam geneator and slows the cooldown.
This is reflected in the core returning critical later in the transient.
The lower flow also increases the negative feedback around the power generating stuck rod locations resulting from a moderator temperature reduction.
The lower power that can be supported in the power generating stuck rod location under low flow conditions make this case less limiting than the case with offsite power.
It is our understandi ng that LOFTRAN thermal-hydraulical'ly homogenizes (assumes perfect mixing) the reactor coolant entering the vessel from the broken and intact recirculation loops.
This assumption provides identical hot leg temperatures for all loops.
Of concern is that the broken loop cold leg temperature may be non-conservatively elevated since the broken loop hot leg temperature could be appreciably lower than analyzed.
Should this be the case, then the moderator temperature at the stuck rod location would be non-conservatively analyzed.
Justify your analyti'cal model with regard to the above concern.
A 6:
Because LOFTRAN is a multiloop PWR simulation code, provision has been made to allow coolant to mix" among the loops in the reactor vessel inlet and outlet plena.
Independent inputs for the inlet and outlet are available to vary the extent of mixing between no mixing and perfect mixing.
The loop-associated core inlet and core average parameters must be combined into a single reactivity feedback input for use in the point kinetic core model.
This is accomplished by a
. separate weighting factor which places relative importance on specified sectors of the core, thus enabling L'OFTRAN to predict reactivities which are in agreement with multi-dimensional neutron design codes.
To show the modeling capability of-LOFTRAN, the exit temperature in the cold leg and entrance temperature of the hot leg, for both faulted and unfaulted loops, are presented in Figs. I and 2, respectively.
Figure 3 presents the basic fluid system model utiilized by LOFTRAN (refer to WGAP-7878).
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The requirement fox use of the BIT tanks for Mitigation of the Main Steam Line Break accident has been x'emoved following installation of, t5e godel 44F Steam Generators The required.
supporting analyses can 'be found in L-81-502,. dated ll/30/81.
The temperature requirement. above 145' is no longer'pplicable.
Therefore, the heat tracing requirement is not necessary.
There is'no Boron Concentration requixement $n the BIT.
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FLORIDA POWER 8I LIGHT COMPANY INTER-OFFICE CORRESPONDENCE To R;E.
Uhl ig FRoM J.W.
Wi 1 1 iams, Jr.
sUB~EOT:
TURKEY POINT UNITS 3 5 4 BIT REMOVAL TECH SPEC LOCATION DATE COPIES TO General Office FEB 10 19B2 R.J.
Acosta D.W. Jones C.S.
Kent J.A. Labarraque H.N. Paduano/932.1TP H.E. Yaeger/J.K.
Hays J. Yespica P RN-LI-82-54 A letter in response to NRC questions on the above subject is attached f'r your 'review and forwarding to the
- NRC,
$kd~
J.W.,Williams, Jr.
PL'P/mbd Attachment PEOPLE... SERVING PEOPLE FORM 1008 REV. 1/78
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STATE OF FLORIDA
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COUNTY Or DADE
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ss Robert E. Uhrig being first. duly sworn, deposes and says:
Tha-he is Vice President of Florida Power Light Company, the herein; That he has executed the foregoing document; that the state-ments made in this said document are true and correct to the best of his knowledge, information, and belief, and that he is authorized to execute the document on behalf of said Robert E. Uhrig Subscr'bed and sworn to befor me th's
,4'0 day of Y
-NOTARY PUBLIC, in d for the County of Dade, Sta'"e g~f'-'Florida gotey Public. State of Florida at Largo Ny COmmiSSiOn eXpireS:
MV Commissicn Exo!t"'tober 30,.1983
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