ML20045B949
| ML20045B949 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 06/14/1993 |
| From: | Farrar D COMMONWEALTH EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 9306210304 | |
| Download: ML20045B949 (5) | |
Text
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1.
- Comm:nwzalth Edison ri 1400 Opus Place Do';iners Gro'.e,lilinois 60515 June 14, 1993 Office of Nuclear Reactor Regulation U.S.
Nuclear Regulatory Commission Attn:
Document Control Desk Washington, D.C.
20555
Subject:
LaSalle County Nuclear Power Station Units 1 and 2 Reply to Request for Information Inspection Report Nos. 50-373/93009; 50-374/93009
Reference:
T. Martin letter to L.
DelGeorge dated May 20, 1993 transmitting NRC Inspection Report 50-373/93009; 50-374/93009 Enclosed is Commonwealth Edison Company (CECO) response to request for information.
The enclosed discusses specific concerns identified with LaSalle Emergency Operating Procedure, LGA-RT-03, Alternate Boron Injection.
If you have any questions concerning this information, please contact Sara Reece-Koenig, Regulatory Performance Administrator,
'i 708(663-7250).
Sincerely, c~L ?. s
^
D.L.
Farrar Nuclear Regulatory Director cc:
G.L. Martin, Regional Administrator - RIII R.
Stransky, Project Manager - NRR D.E.
Hills, Senior Resident Inspector - LaSalle
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l June 7, 1393 In Reply, please refer to CHRON # 119628 To:
G.F.
Spedl subject:
Clarification of Hot Shutdown Boron Weight in EOPs This letter provides supplemental'information to CHRON.#
119621, which reviewed a Station evaluation of the adequacy of the target Boron concentrations for LGA-RT-03.
In that letter, Engineering concurred with the station " white paper that the-a UFSAR input parameters for SBLC do not necessarily correspond.to the EOP alternate Boron injection procedures, and verified the Boron concentrations in LSCS Calculation 0-91-001.
Engineering has been asked to confirm that the Hot Shutdown Bcron Weight adequacy will be bounded by verification of the Cold Shutdown Boron Weight.
This is always the case, i.e. whenever either SBLC or the EOP procedures achieve injection of the Cold Shutdown Boron Weight, they then necessarily have injected sufficient Boron for Hot Shutdown.
It should be noted however, that the adequacy of the HDSBW calculation does not depend on this bounding argument because the target concentration and weight calculations are verified in separate calculations for the Hot and Cold Shutdown Conditions, in the above referenced calculation.
If you have any questions regarding this issue, please contact me or Bill Kirchhoff at extension 2927.
" ,a
,4 /
0 - l, Y_T.,
e,- M ller Side igineering and Construction Plent Support Supervisor cc:
R.M.
Shields L.M.
Shearer NEDCC l
SEC CHRON File
May 27, 1993 In Reply Please refer to CHRON:
{ggggi To:
G.F. Spedl Subjact:
Engineering Review of LGA-RT-03 Boron Concentrations Per your request, Site Engineering has reviewed the attached discussion from Systems Engineering regarding the basis and acceptability of the target Baron concentrations used for LGA-RT-03.
The review performed was a " top down" review of the Licensing and Technical basis for the assumptions used, and an independent review and performance of the concentration calculations themselves.
Engineering agrees that the UFSAR parameters for the SBLC system do not necessarily correspond to those for EOPs.
Specifically, the 25% ' inadequate mixing' penalty is not applicable to EOPs as the Boron weight assumptions are required to assume even mixing, and the EOPs themselves contain actions to ensure this mixing.
The technical input assumptions for reactivity conditions, RPV inventory and temperature effects, and Boron isotope mass fractions are conservative.
The independent calculations resulted in minor variations due to rounding and calculation sequence differences.
These differences are insignificant, and do not affect the acceptability of the results of LSCS Calculation 0-91-001, or the conclusions in the referenced discussion.
If you have any questions or concerns, please contact me at extension 2694 or William Kirchhoff at ext. 2927.
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F-A 7-f_1
' il Q Jeff Miller Site Engineering and Construction Plant Support Supervisor cc:
R.M. Shields L.M. Shearer NEDCC SEC CHRON FILE
s Response to specific concerns identified with LGA-RT-03 in inspection report 373/374-93009.
Issue:
No justification for not including the UFSAR required conservatism in the calculation of the required boron to be included in the alternate boron injection procedure.
Response
LaSalle concluded that certain additional cou?ervatisms contained in the UFSAR regarding the amount of boron in the SBLC tank are not applicable to calculations of boron weights required under1 conditions beyond-the design basis. The EOP calculations of the required boron amounts to be injected into the RPV are based on the conservative assumptions outlined in the EPG SER appendix C and NEDO-31331 definitions.
As specified in the SER, the definitions are:
HOT SHUTDOWN BORON WEIGHT "The Hot Shutdown Boron Weight is defined to be the least weight of soluble boron which, if injected into the RPV and mixed uniformly, will maintain the reactor shut down under hot standby conditions."
COLD SHUTDOWN BORON WEIGHT "The Cold Shutdown Boron Weight is defined to be the least weight of soluble boron which, if injected into the RPV and mixed uniformly, will maintain the reactor shut down under all conditions."
These definitions assume that the boron injected into the RPV will be uniformly mixed. The LaSalle calculation of the HSDBW and CSDBW are consistent with this definition. This calculation i
applies to both the SBLC and alternate injection boron..The basis of the weight of boron injected during the alternate boron injection procedure, LGA-RT-03, is consistent with these calculations. Therefore.the alternate boron injection support procedure'is correct in this regard and uses the same basis as the flowchart EOP with SBLC for HSDBW and CSDBW. The UFSAR assumptions are used for the design criteria for SBLC. The SBLC system meets these design criteria..
The generic values used for CSDBW could be 500 ppm per reference 2, however the value of 660 was used for conservatism.
If the 25% for imperfect mixing-is included with the 500 ppm-value, the present 660 ppm used for CSDBW would be sufficient if f
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imperfect mixing did occur.
The dilution factor-for shutdown cooling is addressed in these calculations directly by using the increased water volume when shutdown cooling is initiated as part of the calculation for the required cold shutdown boron weight concentration in the RPV.
The definition for CSDBW requires that the mass of water in the shutdown cooling loop be included in the calculation of CSDBW.
Shutdown cooling is not placed in service until the cold shutdown boron weight is injected into the RPV(per LGA-10) to avoid dilution until sufficient boron to remain shutdown under all conditions is already in the RPV. The UFSAR description provides the additional amount in ppm of boron which must be added to the RPV to account for the subsequent dilution by shutdown cooling.
The intent of the UFSAR(ie to account for shutdown cooling dilution) is met.
References:
- 1. LaSalle CALC EOP-91-001.
- 4. NEDO-31331, supplement A, revision 4.
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