ML17194A373
| ML17194A373 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 12/28/1981 |
| From: | Crutchfield D Office of Nuclear Reactor Regulation |
| To: | Delgeorge L COMMONWEALTH EDISON CO. |
| References | |
| TASK-15-13, TASK-RR LSO5-81-12-086, LSO5-81-12-86, NUDOCS 8112300057 | |
| Download: ML17194A373 (6) | |
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December 28, 1981 ti ~
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Docket No. S0-237 LSOS12-086 Mr. L. Del George Dtrector of Nucle~r L1C'.ens1ng Commonwealth E41son Company Post O'fft.ce Box 767 Chicago~ 1111nois 606~:0 fl
Dear Mr:
.
- Del George :
SUBJECT:
DRESDEN 2 - SEP TOPIC XV-13. SPECTRUM OF ROD DROP ACCIDENTS Commonwealth Ed1son (T.:! Rausch) letter dated October 15, l981 transmitted for our review your safety analysts report (SAR) for SEP Toptc XV-13.
Enclosed you will find,our evaluation of this topic.
The result of our st~ff' s review indicates that the Dresden 2 plant 1 s acceptably desf gned fOr contro111ng or miti'gat1ng the radiological consequences of controll rod drop acc1 dents.
- 1 This evaluation w111 be; the basic input to the integrated safety assessment for Dresden 2 unless* yo~ fdentffy changes needed to reflect the as-built cond1t1ons at your facH tty. The assessment may be revised in the future if your" fac111ty desi gni1 is changed or 1f NRCI cttterfa relating to this subject is modff.fed bef9re the integrated assessment ts complete.
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Enclosure:
As stated cc w/enclosure:
See next page 8112300057 811228
- i' PDR ADOCK 05000237
- P
. PDR Sincerely, Dennis M. Crutchfield, Chief Operating Reactor Branch No. 5 Divfston of Licensing I
SEP :SL r
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BHerman'
~~Russel 1 PO 1 Connor
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12/62&'/81 12/ 1;-, /81
- 1 NRC FORM 318.(10-80) NRCM 0240 OFFICIAL RECORD COPY USGPO: 1981-335-960
Mr. L. DelGeorge.
cc Isham, Lincoln & Beale Counselors at law One First N~tional Plaz~. 42nd Floor Chicago, Illinois 60603 Mr.. Dou*g *sC:ott "Plant Superintendent Dresden Nuclear Power Station Rural Route fl Morris, Illinois 60450 Natural Resources Defense'Council 917 15th Street, N. W.
Washing~on, D. c. 20005
- u. S. Nuclear Regulatory Commission Res1dent Inspectors Office Dresden Station RR fl
- Morris, Illinois 60450 Mary Jo Murray Assistant Attorney General Environmental Control*Oivision 188 W. Randolph Street Suite 2315 Chicago, Illinois
- 60601 Morris Public Library 604 Liberty Street Morris, Illinois 60451 Chairman Board of Supervisors of Grundy County Grundy County-Courthouse Morris, Illinois 60450 John F. Wolfe, Esquire 3409 Shepherd Street Chevy Chase, Maryland 20015 Dr. Linda w. Little.
- 500 Hermitage Drive Raleigh, North Carolina 27612
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... ~DRESDEN 2 >. '-*/_
- :. ; > :, ;. * *.. : Docket No. 50-237
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- Region V Office ATTN:
EIS COORDINATOR 230 South Dearborn* Street**
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- Dr. Forrest J. Remick.*
305 East Hamilton Avenue State College, Pennsylvania 16801
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- xv-13 *sPEcrnuM**oF* RoD *DROP P.cc1DENTs
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I.
INTRODUCTION *
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An uncoupled control rQd may. hang up in ~he core when,tt,':T. ~co~~rol rod *i-~ *,;_;> * * :.: __,: ~
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er when the consequences are most severe.
- As a result.*
radioactivity may be released from the core to the e~~ironment via the....
turbine and condensers.
SEP Topic XV-13 is intended to review the plant *
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response and evaluate 'the radiological consequences of this accident *. *
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II.
REVIEW CRITERIA Section 50.34. of 10 CF~ Part 50 requi~es that each applicant.for a construction permit or operating license provide an*.. analysis and evaluation of* the: design
- and performance of structures, systems, and components *of the faci_lity, with the objective*of assessing the risk to public health and safety resulting from operation of the facility.
The control rod drop accident is_one of the postulated accidents used to evaluate the adequacy_ of these structures, systems, and components "with respect to the pub 1 i c hea.lth and safety.
In addition, 10 CFR Part 100.11 provides guidelines concerning the general approach to calculations of the. consequences of postulated accidents involv-ing fission product release.
III.
RELATED SAFETY TOPICS Topic II-2~C, 11Atmospheric Transport and Diffusion Characteristics for Accident* An~lysis 11 provides the meteorologic~l data used. to e~aluat~ ~~... <':.*.*:,*'*,
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- off site doses.
Topic 111-8.B, "Control Rod Drive Mechanism Integr_itya e~aluates the reli~bility and operability of con~rol rod dri~es. _Various.
other SEP topics evaluate such items as containment isolation. containment leak testing and ESF systems.
IV.
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The review *of the radiological consequences of a control. rod.drop.i~;: _
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ace i dent :--~~s condu~ted.. in accordance with the.Appe~di*~:* t~ st*~~~a;:~~: Revi ~~.. :::*,_:.~.. ::~~*i*..
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Plan 15.4.9. The plant is considered* adequ_ately desi.g;ned against a control*
rod drop accident and_:the consequences ~ccept~ble if the resulting. doses at the exclusion area and low population zone boundaries are well within the guideline.values.of 10 CFR Part 100.
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EVALUATION The licensee in his submittal dated October 15, *198l, submitted an evalu~
tfon of the radiologic.al consequences. of a rod. drop accident. The licensee*:
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determined that even u~ing conservative assumptions., u;tll11e effects are still orders of magnitude be.low those identified in *10 CFR Part 100.
The* staff independently calcu!_ated the radiological consequences f*ollowing the postulated
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control rod drop accjdent.
We used the applicant's estimate that 850 fuel rods could perforate: if a rod drop accident occurred_ at the power of 2561 MWt.
The staff assumed tllat 10% of the noble gas inventory' and 10% of the iodine inventory are released.from the perforated fuel rods to the primary coolant.
The staff estimated no fuel melting for this accident.
All other assumptions used in the radiological consequence analysis; are consistent with the assumptions given in the review procedures.section of SRP Section 15.4.9, *Appendix A, Rev. 1. A summary of these assumptions
- is pro~ided by th~ ~tt~ched *table to this SEP e~~l~~ti:~. ** *,-'.*.-: *
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VI.
CONCLUSIONS Using the assumptions outlined above the resultant doses at the nearest exclusion area boundary are 0.3 rem to the thyroid and 0.04 rem to the
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whole body. * *rhe resuVtant* doses at the LPZ boundary are 0.09.rem to.the.
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SRP Section 15.4.9 Appendix. A,* Rev~ 1 '*and are well. withi~-the *guideline**_,.. *
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,y~lues of lb CFR Part 100.11 *
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like the licensee, the *~taff concludes that th~ Dresden-2 Nucl'ear static~
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consequences from the *postulated control rod dr:-op accident *. *
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TABLE XV-13.1
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Dresden-2 Assumptions for the Calculation of Radiological
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Consequences Following a Control Rod Drop Accident*
Amount of fuel failures*
Peaking factor Power Activity rele~_se from failed fuel
=
- 850 rods
=
1.5
=. 2561 MWt
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10% iodin~
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- 10% noble gases.
Amount of activity transported to the -
- condenser prior to MSIV closu~e
-Partition factor in the crindenser.
Leak rate from condenser Leak duration Breathing rate (0-8 hr)
(8-24)
Exclusion area X/Q (0-2 hr)
- Low population Zone X/Q (0-8 hr)
- tow population Zone X/Q (8~24 hr)
Total rods in th~ core
- Ground level values for X/Q 10% iodine 100% noble gases
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lOfor iodine 1 for noble gases 1% per day*
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24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />
=-
j.47 x 10-4 m3/sec
= 1.75 x 10-~ m3/sec
= 2.6
-4 3
x 10 sec/m
=.. 1. 1. x 10-5 sec/m3
=
1.4 x io-6 sec/m3 45612
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