ML18024A349

Updated Final Safety Analysis Report (Ufsar), Amendment 27, 14.9 Table - Dose Sensitivity Evaluation

ML18024A349
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Site:	Browns Ferry
Issue date:	10/05/2017
From:	Tennessee Valley Authority
To:	Office of Nuclear Reactor Regulation
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BFN-18 TABLE 14.9-1 DESIGN BASIS ACCIDENT RADIOLOGICAL DOSES (REM) WHOLE BODY THYROID

2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> 30 day 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> 30 day Accident (1400 m) (3218 m) (1400 m) (3218 m)

Loss of Coolant 2.2 x 10

-1 6.1 x 10-1 2.9 x 10 0 3.6 x 10 1 Refueling 4.9 x 10

-2 1.9 x 10-2 3.1 x 10 1 4.2 x 10

-1 Control Rod Drop 1.2 x 10

-2 4.3 x 10-2 6.1 x 10 0 7.0 x 10 0 Steam Line Break 1.7 x 10

-2 8.0 x 10-3 3.0 x 10 1 1.0 x 10 1

BFN-18 Table 14.9-2 (Sheet 1)

SENSITIVITY OF DOSES TO VARIATION OF ASSUMPTIONS LOSS-OF-COOLANT ACCIDENT

Factor Affecting Design "Base" Assumed AEC Assumptions Case Case Thyroid Dose Whole Body Dose Fission products 1.8 percent noble gases 1 100 percent noble gases 625 220 released to drywell 0.32 percent iodines 50 percent iodines and from 25 percent of the 1 percent solids in fuel rods which are total core inventory. assumed to be perforated. 5 percent of total 1 percent of total iodine iodines in organic form.

in organic form. Negligible solids.

Iodine retained Based on partition factor None 12.5 3 1 in water of 100 between the volumes of air and water in pressure suppression chamber and drywell.

Elemental iodine 50 percent 50 percent 1 1 plateout in drywell Leakage rate from Function of drywell 0.635 percent volume per 1.3 (2-hr) 2 1.3 (2-hr) primary containment pressure; peaks close day, constant ~1 (30-day) ~(30-day) to 0.5 percent volume throughout accident per day Uniform mixing Yes No 22 (2-hr) 28 (2-hr) in Reactor Building 1.2 (30-day) 1.1 (30-day)

Iodine filter 99 percent 90 percent 10 1 efficiency (95 percent for solids)

Effectiveness of stack Yes Yes 1 1 NOTE: 11 percent of iodines released in organic form, which is not reduced by fallout or drywell and reactor building. Elemental iodines are carried into pressure suppression pool during blowdown, and a fraction retained according to the assumed equilibrium partition factor of 100. Iodines become airborne in the pressure suppression chamber and drywell before leaking out to the secondary containment.

22-hr dose is evaluated at site boundary of 1400 meters; 30-day dose is evaluated at low-population zone of 3218 meters.

3Takes into account the organic iodine fraction.

BFN-18 Table 14.9-2

(Sheet 2)

SENSITIVITY OF DOSES TO VARIATION OF ASSUMPTIONS

REFUELING ACCIDENT

Factor Affecting Design "Base" Assumed AEC Assumptions Case Case Thyroid Dose Whole Body Dose Fission product 1.8 percent noble gases, 20 percent noble gases, 13.8 4.9 release to reactor 0.32 percent iodines from 10 percent iodines from water 1 111 perforated fuel 49 perforated fuel rods, solids negligible rods 2 Iodines retained Equilibrium partition 4 90 percent 2 0.4 1 in water factor of 100 for iodines and water

Plateout of iodines None 50 percent 0.5 1 in Reactor Building Uniform mixing in Yes No 14 (2-hr) 3 18 (2-hr) refueling chamber ~1.3 (30-day) ~1.1 (30-day)

Fission Products Fission products exponentially released exponentially released from water to Reactor from water in 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> Building till exhausted

Iodine filter 99 percent 90 percent 10 1 efficiency (95 percent for solids)

Effectiveness of Yes Yes 1 1 stack

NOTE: 1Accident occurs 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after shutdown.

2Assumptions in Hatch (Docket No. 50.321) evaluation.

32-hr dose is evaluated at site boundary of about 1400 meters. 30-day dose is evaluated at low-population zone of 3128 meters.

4Amount of retention depends on the ratio of air space to water space. In this case, the equivalent value of 75 percent is obtained.

BFN-18 Table 14.9-2

(Sheet 3)

SENSITIVITY OF DOSES TO VARIATION OF ASSUMPTIONS CONTROL ROD DROP ACCIDENT

Factor Affecting Design "Base" Assumed AEC Assumptions Case Case Thyroid Dose Whole Body Dose Fission products 1.8 percent noble gases, 100 percent noble gases, 156 55 released to water 0.32 percent iodines from 50 percent iodines from 330 perforated fuel 330 perforated rods, solids negligible fuel rods Noble gases carry- Uniformly mixed with 100 percent 1 10 over to condenser steam, carried over hotwell at 5.0 percent steam flow rate, isolation valve closure at 10.5 sec.

Iodine carryover to Retention in water, 1 10 percent 2700 1.0 condenser hotwell uniform mixing in steam dome, carryover at 5.0 percent steam flow, and isolation at 10.5 seconds Iodine plateout in None 50 percent 0.5 1 condenser hotwell

Release mechanism 1800 cfm from vapor Leak rate of 0.5 percent per 5.5 X 10

-4 (2-hrs) 5.5 X 10

-4 (2-hrs) space of condenser and day from condenser 1.13 X 10

-2 (30-days) 1.13 X 10

-2 (30-days) turbine, stack release to environs

NOTE:

1Amount of retention in condenser hotwell water depends on relative ratio of steam space to water space. The "base" case uses an equilibrium partition factor of 100 and a steam-water space ratio of about 12.

BFN-18 Table 14.9-2

(Sheet 4)

SENSITIVITY OF DOSES TO VARIATION OF ASSUMPTIONS STEAM LINE BREAK ACCIDENT

Factor Affecting Design "Base" Assumed AEC Assumptions Case Case Thyroid Dose Whole Body Dose Steam and Water 185,000 lb 185,000 lb 1 1 Mass Lost in (25,000 lb steam blowdown (10.5 160,000 lb water) sec. closure)

Total fission 146 curies iodines Proportional to 10.5 10

.5 2 gases released and 5.7 curies operating limit, noble gases 1 10.5 times the base case value

Concentration in Equilibrium separation Equilibrium separation 1 1 water and steam

Steam cloud rise No No 1 1

NOTE:

1Based on fission product concentrations in coolant such that the offgas release rate at stack reaches the maximum expected value of 10,000 FCi/sec.

2In the steamline break accident, the noble gases contribution to the whole body dose is insignificant.