ML17209A254

Proposed Change to Tech Spec Section 3/4.9.14 & Bases, Correcting Error in Fuel Pool Cask Drop Analysis.Safety Evaluation Encl

ML17209A254
Person / Time
Site:	Saint Lucie
Issue date:	10/16/1980
From:	FLORIDA POWER & LIGHT CO.
To:
Shared Package
ML17209A253	List: ML17209A251 ML17209A254
References
NUDOCS 8010210416
Download: ML17209A254 (5)

Text

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'/4.9. 14 DECAY . TQK STOPAGE POOL LIMITING .CONDITION %OR OPEBAZXCB 3.9.14 The ixradiated, fuel assemblies in the fuel storage pool shall have decayed for at least 1180 hours0.0137 days <br />0.328 hours <br />0.00195 weeks <br />4.4899e-4 months <br />, unless more than one-third. core is placed into the pool, in which case the irradiated fuel assemblies shall have decayed for 1490 hours0.0172 days <br />0.414 hours <br />0.00246 weeks <br />5.66945e-4 months <br />.

APPLZCABILXTY: Prior to movement of the spent fuel 'cask into the fuel, cask compartaumt.

ACZZ(RI:

With irradiated. fuel assemblies having a decay time of less than 1180 hours0.0137 days <br />0.328 hours <br />0.00195 weeks <br />4.4899e-4 months <br />, or 1490 hours0.0172 days <br />0.414 hours <br />0.00246 weeks <br />5.66945e-4 months <br /> in the case of more than one-third core discharge, suspend all activities involving movenent of the spent fu'el cask into the fuel cask canpartment. The provisions of Specification 3.0.3 are not applicable.

.:SURVEIIZ'JSCE .RE UXREHENTS 4.9.14 The irradiated, fuel assariblies in the fuel storage pool have been determined to have decayed for at least 1180 hours0.0137 days <br />0.328 hours <br />0.00195 weeks <br />4.4899e-4 months <br />, 'hall or 1490 hours0.0172 days <br />0.414 hours <br />0.00246 weeks <br />5.66945e-4 months <br /> in the case of mare .than one-third. core discharge, by verification of the date and time from the aast recent sub-criticality prior to mveaent of the spent fuel cask into the fuel cask compar tment.

ST. LUCXE - UiiXT 1 3/4 9-16 10-16-80 8 $ 10210/1 4

REFUELING OPEPATIONS BASES k

3/4.9 12 FUEL POOL VENTILATION SYSTEVi-FUEL STORAGE The limitations'n the fuel handling building ventilation system ensures that a'll radioactive material released from an irradiated fuel assembly will be filt red through the HEPA filters and'charcoal prior to discharge to the atmosphere. Th OPERABILITY of this system adsorber and th resulting iodine removal capacity are consistent with the assumptions of the accident analyses.

3/4.9 13 SPENT FUEL CASK CRANE The maximum load which may be handled by the spent fuel cask cran is limited to a loaded single element cask which is equivalent to approximately 25 tons. 'his restriction is provided to ensure the structural .integrity of the spent fuel pool in the event of a dropped cask accident. Structural damage caused by dropping a load in excess of a loaded single element cask could cause leakage from the spent fuel pool in excess of the maximum makeup capability.

3/4.9.14 DECAY TINE - STORAGE POOL The minimum i.equir'ements for decay. of the irradiated fu*el assemblies 'i' the entire spent fuel storage pool prior to movement of the spent fuel cask into the fuel cask compartment insure that sufficient time has elapsed to allow radioactive decay of the fission products. The decay time of 1180 hours0.0137 days <br />0.328 hours <br />0.00195 weeks <br />4.4899e-4 months <br /> is based upon one-third of a cor'e: placed in the spent fuel pool each year during refueling for ten years to fil,l the .

p'ooT. The"dec'ay'timef'1490 hours0.0172 days <br />0.414 hours <br />0.00246 weeks <br />5.66945e-4 months <br /> is based upon one-third of a core being placed inthe spent fuel pool each year during refueling for seven years following which. an entire core is placed in the-pool to fill'it.

The cask drop analysis assumes that all of the irradiated fuel in the filled pool (3-1/3 cores) is ruptured and follows Regulatory is Guide 1.25

'applied.to methodology, except that a Radial Peak'ing Factor of 1.0 all.irradiated assemblies.

ST. LUCIE UNIT 1 B 3/4 9-3 10-16-80

SAFETY EVALUATION FOR STORAGE POOL DECAY TllIE

1. INTRODUCTION The Final Safety Analysis Report, (FSAR) fox St. Lucie Unit No. 1, at. page 9.1-33m, states that, the radius 'of fall of spent fuel shipping *cask into the spent fuel pool is 133 inches. This value was used in the Safety Evaluation which was submitted with FPL's request, dated August 31, 1977/ to increase the storage capacity of the spent fuel pool from 310 to 728 fuel assemblies; As used in that evaluation, 'this xadius of fall fox a potential cask drop would have resulted in a total of 168 fuel assemblies being impacted. The radiological'valuation performed followed that. described,.in the FSAR, using Regulatory Guide 1.25 methodolog'y and assuming to be'he equivalent of the

.each of the impacted assemblies highest burnup assembly. It was Qetermined that the release thus calculated would remain within 10% of 10 CFR Part 100 if limits the fuel decay time for the 168 assemblies were 1553 hours0.018 days <br />0.431 hours <br />0.00257 weeks <br />5.909165e-4 months <br /> or greater. Amendment No. 22 to Operating License the increased storage capacity was therefoxe issued ... DPR-67'pproving on March 29, 1978, with a, decay time of 1553 hours0.018 days <br />0.431 hours <br />0.00257 weeks <br />5.909165e-4 months <br /> required for those assemblies stored in the modules nearest the fuel

~ 'ask compartment.

It I has'ince been determined analysis for the drop of the that. an error existed in the FSAR spent fuel:cask i.nto the spent

. fuel pool. The 'analysis was'a originally performed assuming a single pendulum which 'gave drop radius of 133 inches. The FSAR methodology, however', specifies a double pendulum, which, gave a Qrop r'fidius of 248 inches. This meant that a dropped cask could impact more fuel elements.

2. 'ISCUSSION The proposed amendment to the Technical Specifications would.

require that, prior to movement, of the spent fuel cask into the fuel cask compartment, all irradiated fuel assemblies in the spent fuel pool have a decay time of at least 1180 hours0.0137 days <br />0.328 hours <br />0.00195 weeks <br />4.4899e-4 months <br />, unless more than one-third of a-full core is discharged to the pool at once, in which case the decay time is to be 1490 hours0.0172 days <br />0.414 hours <br />0.00246 weeks <br />5.66945e-4 months <br />.

These decay times are baseQ upon an analysis which conserva-tively assumes that all of the fuel in a full pool (3-l/3 cores) is ruptured as a result of a potential cask drop. The

'analysis is identical to that used, in the FSAR and the safety evaluation accompanying FPL's request to increase spent fuel storage capacity, except that the appropriate value for assembly burnup has been used.. The earlier analysis used a Radial Peaking Factor (RPF) of 1.65 as specified in Regulatory Guide 1.25 to represent the highest burnup fuel assembly to which all, the impacted fuel assemblies would be equated.

While this value may be appropriate for the analysis of a postulated accident involving a single assembly, it conservative when applied to an analysis involving 1/3 of a is grossly whose fuel assemblies have various exposure histories. 'ore An. RPF of 1.0 has been selected as being more representative for=the off-load of orie or more regions from the core anQ has been applied to each assembly. in the present analysis. The resultant decay times are those which. are necessary to assure that offsite exposures will be within 10% of 10 CFR Part 100 limits. Two cases have been evaluated:

'Ca'se X One-third of a'ore is placeQ in the spent fuel pool each year Quring refueling for ten years.

Case XX- One-third of a core is placed in the spent fuel pool each year during refueling for seven years; Following the ei.ghth year of operation, the entire core is removed from the'reactor and placed into the pool at once.

A summary of the results of the evaluation is shown in the

.table below.

DECAY TIME (HRS.) AND DOSE (HEM)

• Case I (10-yeap) Case XI (8-year)

(HRS.) (REM) (HRS.) ( REM)

Thyroid: 1180 29. 6'6 1'490 29. 27 Whole Body: 1180 0.076 1490 0.078

• Regulatory Guide 1.25 methodology used, except that the Radial Peaking Factor for each. assembly is equal to 1.0.

3. CONCLUSXONS Since, as described above, the resultant exposures remain within the limits stated in the FSAR, it is concluded that the. requested amendment does not involve an unreviewed safety question.

Further, the amendment requested does not involve signifi-cant new safety information of a type not considered by a previous Commission safety review of .the facility. Xt does not, involve a significant, increase in the probability or consequences of an accident, does not involve a

significant decrease in a safety margin, and, therefore does not involve a significant hazards consideration.

It is therefore concluded that there is reasonable assurance that the health and safety of the public will not be endangered by this action.