ML17338A845

Ack Receipt of Util Responding to NRC Request for Evaluation of Postulated Fuel Handling Accident Inside Containment.Potential Consequences of Postulated Accident Are within 10CFR100 Guidelines & Are Acceptable

ML17338A845
Person / Time
Site:	Turkey Point
Issue date:	05/30/1979
From:	Schwencer A Office of Nuclear Reactor Regulation
To:	Robert E. Uhrig FLORIDA POWER & LIGHT CO.
Shared Package
ML17338A846	List: ML17338A845 ML17338A847
References
NUDOCS 7907130133
Download: ML17338A845 (20)

Text

WRussell BGrimes TJCarter Docket No-60=250 SO-251 Based on that review which is discussed in. the enclosed Safety Evaluation, we have concluded that the potential consequences of this postulated accident are appropriately within the exposure guidelines of 10 CFR Part.100 and are. therefore, acceptable.

TAC 8798/8799 Distribution Doc et 0-WV So

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,NRC PDR 50-251 LOCAL PDR ORB1 Reading NRR Reading ASchwencer MGrotenhuis

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CParrish Dr. Robert E. Uhrig OELD Vice President 9>8E.(3)

Florida PoHer 5 Light Company ACRS (16)

Advanced Systems 8 Technology JBuchanan Post Office Box 529100 TERA Miami, Florida 33152 VStello SEisenhut

Dear Dr. Uhring:

RVollmer Your letter dated March 21, 1977 was submitted in response to our request for an evaluation of a postulated fuel handling accident inside containment.

We have completed our review of your evaluation and have,"-,performed our independent evaluation -of the consequences of this postulated accident.

Sincerely,

Enclosure:

Safety Evaluation dated cc w/enclosures:

See next page A. Schwencer, Chief 4/

Operating Reactors Branch gl Division of Operating Reactors orrlcII~

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Enclosure

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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION REGARDING FUEL HANDLING ACCIDENT INSIDE CONTAINMBHT FLORIDA POWER AND LIGHT COMPANY TURKEY POINT NUCLEAR GENERATING STATION UNIT NOS.

3 AND 4 DOCKET NOS. 50-250, 50-251 Introduction Hy letter dated March 21, 1977, Florida PoWer and Light Company, (the licensee) submitted an evaluation of a postulated Fuel Handling Accident Inside Containment (FHAIC) at the Turkey Point Plant Unit Nos.

3 and 4.

In the evaluation the licensee assumed that the FHAIC occurred 50 hours5.787037e-4 days <br />0.0139 hours <br />8.267196e-5 weeks <br />1.9025e-5 months <br /> after plant shutdown on the basis that this is the earliest time that fuel

'andling operations may begin.

The licensee stated that the potential consequences of this postulated accident are 46 Rem thyroid and 0.2 Rhmlehole body at the Exclusion Area Boundary (EAB).'he licensee concluded that, these doses are well below the guidelines of 10 CFR Part 'l00.

Evaluation We have completed our review of the licensee's March 21, 1977, submittal which addresses the potential consequences of an accident invMving spent fuel hand1ing inside containment.

We have also performed an independent analysis of the FHAIC.

In our evaluation we have assumed a minimum decay time of 50 hours5.787037e-4 days <br />0.0139 hours <br />8.267196e-5 weeks <br />1.9025e-5 months <br /> between plant shutdown and handling of irradiated fuel.

This time is shorter than that practiced by most operating pressurized water reactors.

Therefore, we will not require the-licensee to modify the Technical Specifications to require a minimum decay time before handling spent fuel.

Our r'emaining assumptions and the resulting potential consequences at the EAB are given in Table>1.

Our evaluation supports that of the licensee in that the calculated poten-tial consequences of the postulated fuel handling accident inside contain-ment are appropriately within the guidelines of 10 CFR Part 100'hnd are, therefore, acceptable.

Appropriately within the guidelines df 10 CFR Part 100 has been defined as less than 100 Rem to the thyroid.

This is based on the robabilit of t is ev orrics~~

"A.*wl va uate aga ere"also-exam iyed radioiso

-this"postii)'n"%hose-v st 0 CFR Par ned~"but-they oges prior to ted accjdent 100 exposur guidelines.

Whole body d are-not"cont H fng-due 4o decay ef-she fuel...hand)fag.....T.he..put,elf. al...cons.aguen t the Low Pop Talion Zone oundary are 1

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~s2w A recent study-has indicated that dropping a spent fuel assembly into the core during refueling operatians may potentially cause damage to more fuel pins than has been assumed for evaluating the Fuel Handling Accident Inside Containment.

This study has indicated Shat up to all of the fuel pins in two spent fuel assemblies, the one dropped and the one hit, may be damaged because of the'mbrittlement of fuel cladding material from radiation in the core.

The probability of the postulated fuel" handling accident inside containment is small.

Not only have there been several

'hundred reactor-years of plant operating experience with only a few accidents involving spent fuel being dropped into the core, but none. of these accidents has resulted in measurable releases of activity.

The potential damage to spent fuel estimated by the study was based on the, assumption that a spent fuel assembly falls about 14 feet directly onto one other assembly in the core; an impact which results in the greatest energy available for crushing the fuel pins in both assem-blies.

This type of impact is unlikely because the falling assembly would be subjected to drag forces in the water which should cause the assembly to skew out of a vertical fall path.

Based on the above evaluations.

we have concluded that the likelihood of a spent fuel assembly falling into the core and damaging all the fuel pins in two assemblies is sufficiently small that refueling inside containment is not a safety concern which requires immediate remedial action.

We have, however, conservatively calculated the potential radiological consequences of a fuel assembly drop onto the reactor core with the rupture of all the fuel pins in two fuel assemblies.

We have also assumed for this postulated accident that the source term for both spent fuel assemblies is that given in Regulatory Guide 1.25.

This is conservative bec'ause (1) these two assemblies should not have the power peaking factor and clad gap activity recommended in RegulatoYy Guide 1.25 and (2) the pool decontamin-ation factor for inorganic iodine is expected to be greater than that recommended in Regulatory Guide 1.25.

The calculated potential radiological consequences at the exclusion area boundary for the complete rupture of fuel pins in two assemblies are twice the values given in Table 1.

These conservatively calculated potential consequences, due to the lower proba-bility of two assembly failures, have been judged against and found less than the guidelines of 10 CFR Part 100.

Consequently, we have concluded that the potential consequences of this postulated accident are acceptable.

1 J.

N. Sin h, "Fuel Assembl Handlin Accident Anal sis,"

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Environmental Considerations

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The environmental impacts'of an accident involving the handling of spent fuel inside containment have been addressed in Section Y.E of the Turkey Point 3/4 Environmental Statement (FES) dated July, 1972.

This evaluation of a postulated FHAIC shows that the impacts fil:limithinthe range of impacts founded by the evaluation in the RES.

Conclusion The staff -has evaluated the licensee's analysis of the postulated FHAIC.

After performing an independent analysis of the radiological consequences of a FHAIC to any individual located at. the nearest exclusion area

boundary, the staff concludes that the doses for one assembly failure are appro-pr iately within the guideline values of 10 CFR Part 100 and for failure of two assemblies within the guideline values of 10 CFR Part 100 and are, therefore.

acceptable.-

Date:

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UNITEDSTATES NUCLEAR R EGU LATORYCOMMISSION WASHINGTON;D. C. 20555 Docket No.

50-250'0-251 hfAY q g t97g Dr. Robert E. Uhrig Vice President Florida Power 8 Light Company Advanced Systems

& Technology Post Office Box 529100 Miami, Florida 33152

Dear Dr. Uhring:

Your letter dated March 21, 1977 was submitted in response to our request for an evaluation of a postulated fuel handling accident inside containment.

We have completed our review of your evaluation. and have performed our independent evaluation of the consequences of this postulated accident.

Based on that review which is discussed in the enclosed'afety Evaluation, we have concluded that the potential consequences of this postulated accident are appropriately within the exposure guidelines of 10 CFR Part 100 and are, therefore, acceptable.

Sincerely, r

A. Schwencer, Chief Operating Reactors Branch fl Division of Operating Reactors

Enclosure:

Safety Evaluation dated cc w/enclosures:

See next page

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Robert E. Uhrig Florida Power and Light Company Hay 30, 1979 cc:

Nr. Robert Lowenstein, Esquire Lowenstein, Newman, Reis and Axelrad 1025 Connecticut

Avenue, N.M.

Sui.te 1214

. Mashington, 0.

C.

20036 Environmental and Urban Affairs Library Florida International University Miami, Florida 33199

. Hr. Norman A. Coll, Esquire

Steel, Hector and Oavis 1400 Southeast First National Bank Building tiiami, Florida 33131:."

r Nr. Henry Yaeger Pl'ant Manager Turkey Point Plant

-'Florida Power and Light Company -:---

P. -0.

Box 013100:

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Miami, Florida 33101.

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t1r. Jack Shreve Office of the Public Counsel Room 4, Holland Building Tallahassee, Florida 32304 h

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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 EncIosure SAFETY EYALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION REGARDING FUEL HANDLING ACCIDENT INSIDE CONTAINMENT FLORIDA POWER AND LIGHT COMPANY TURKEY POINT NUCLEAR GENERATING STATION UNIT NOS.

3 AND 4 DOCKET NOS. 50-250, 50-251 Introduction By letter dated March 21,'977, Florida Power and Light. Company, (the licensee) submitted an evaluation of a postulated Fuel Handling Accident Inside Containment (FHAIC) at the Turkey Point Plant Unit Nos.

3 and 4.

In the evaluation the licensee assumed that the FHAIC occurred 50 hours5.787037e-4 days <br />0.0139 hours <br />8.267196e-5 weeks <br />1.9025e-5 months <br /> after plant shutdown on the basis that this is the earliest time that fuel handling operations may begin.

The licensee stated that the potential consequences of this postulated accident are 46 Rem thyroid and 0.2 Rem'.whole body at the Exclusion Area Boundary (EAB).

The licensee concluded that these doses are well-below the guidelines of 10 CFR Part 100.

Evaluation We have completed our review of the licensee's March 21, 1977, submittal which addresses the potential consequences of an accident involving spent fuel handling inside containment.

We have also performed an independent analysis of the FHAIC.

In our evaluation we have assumed a minimum decay time of 50 hours5.787037e-4 days <br />0.0139 hours <br />8.267196e-5 weeks <br />1.9025e-5 months <br /> between plant shutdown and handling of irradiated fuel.

This time is shorter than that practiced by most operating pressurized water reactors.

Therefore, we will not require the licensee to modify

. the Technical Specifications to require a minimum decay time before handling spent fuel.

Our remaining assumptions and the resulting potential consequences at the EAB are given in Table.l.

Our evaluation supports that of the licensee in that the calculated poten-tial consequences of the postulated fuel handling accident inside contain-ment are appropriately within the guidelines of 10 CFR Part 100 hnd are, therefore, acceptable.

Appropriately within the guidelines of 10 CFR Part 100 has been defined as less than 100 Rem to the thyroid.

This is based on the probability of this event relative to other events which are eva1uated against 10 CFR Part 100 exposure guidelines.

Whole body doses were also examined, but they are not controlling due to decay of short-lived radioisotopes prior to fuel handling.

The potential consequences of this postulated accident at the Low Population Zone Boundary are less than those given for the EAB in Table 1.

4

A recent study-has indicated that dropping a spent fuel assembly into the core during refueling operations may potentially cause damage to more fuel pins than has been assumed for evaluating the Fuel Handling Accident Inside Containment.

This study has indicated that up to all of the fuel pins in two spent fuel assemblies, the one dropped and the one hit, may be damaged because of the embrittlement of fuel cladding material from radiation in the core.

The probability of the postulated fuel handling accident inside containment is small.

Not only have there been several hundred reactor-years of plant operating experience with only a few accidents involving spent fuel being dropped into the core, but none of these accidents has resulted-in measurable r'eleases of activity.

The potential damage to spent fuel estimated by the study was based on the assumption that a spent fuel assembly falls about

.14 feet directly onto one other assembly in the core; an impact which results in:the greatest energy available for crushing the fuel pins in both assem-blies.

This type of impact is unlikely because the falling assembly would be 'subjected to drag forces in the water which should cause the assembly

.to skew out of a vertical fall path.

Ba's'ed on the above evaluation.,

we have concluded that the likelihood of a sp'ent fuel assembly falling into the core and damaging all the fuel pins in two assemblies is sufficiently small that refueling inside containment

'i's'not a safety concern which requires immediate remedial action...

Me" have, however, conservatively calculated the potential'adiological consequences of a fuel assembly drop onto the reactor core with the rupture of 'all the fuel pins in two fuel assemblies.

Me have also assumed for this postulated accident that the source term for both spent fuel assemblies is-that given in Regulatory Guide 1.25.

This is conservative because (1).

these two assemblies should not have the power peaking factor and clad gap activity recommended in Regulatory Guide 1.25 and (2) the pool decontamin-ati'on factor for inorganic iodine is expected to be greater than that recommended in Regulatory Guide 1.25.

The calculated potential radiological co'nsequences at the exclusion area boundary for the complete rupture of fuel pins in two assemblies are twice the values given in Table 1.

These conservatively calculated potential consequences, due to the lower proba-bil.ity of two assembly failures, have been judged against and found less than the guidelines of 10 CFR Part 100.

Consequently, we have concluded that the potential consequences of this postulated. accident are acceptable.

1 J.

N. Singh, "Fuel Assembly Handling Accident Analysis,"

EG8G Idaho Technical Report RE-A-78-227, October 1978.

Environmental Consideration The environmental impacts of an accident involving the handling of spent fuel inside containment have not changed from those given in Section V.E of the Turkey Point 3/4 Environmental Statement (FES) dated July 1972.

Conclusion The staff has evaluated the licensee's analysis of the postulated FHAIC.

After performing an independent analysis of the radiological consequences of a FHAIC to any individual located at the nearest exclusion area

boundary, the staff concludes that the doses for one assembly failure are appro-priately within the guideline values of 10 CFR Part 100 and for failure of two assemblies within the guideline values of 10 CFR Part 100 and are, therefore, acceptable.

Date:

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Table 1

ASSUMPTIONS FOR AND POTENTIAL CONSEQUENCES OF THE POSTULATED FUEL HANDLING ACCIDENTS AT THE EXCLUSION AREA BOUNDARY FOR TURKEY POINT PLANT UNITS 3 AND 4 Assumptions:

Guidance in Regulatory Guide 1.25 Power Level Fuel Exposure Tine Power Peaking Factor Equivalent Nunber of Assem-bli es damaged Number of Assemblies in core Charcoal Filters available Decay time before moving fuel 0-2 hours X/0 Yalue, Ex-clusion Area Boundary (ground level release) 2244 Mwt 3 years 1.65 157 Hone 50 hours5.787037e-4 days <br />0.0139 hours <br />8.267196e-5 weeks <br />1.9025e-5 months <br />

-5 3

5.5 x

10 sec/n

Doses, Rem Thvroid I~<hole 8od Exclusion Area Boundary Consequences from Acci dents Ins i de Conta inment 16

0. 07

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