ML20237L148
| ML20237L148 | |
| Person / Time | |
|---|---|
| Site: | La Crosse File:Dairyland Power Cooperative icon.png |
| Issue date: | 08/21/1987 |
| From: | DAIRYLAND POWER COOPERATIVE |
| To: | |
| Shared Package | |
| ML20237L147 | List: |
| References | |
| NUDOCS 8709080235 | |
| Download: ML20237L148 (4) | |
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REVISED Document Control Desk LAC-12333 page 2 August 21, 1987 Reference 2 requires that r4ecific circumstances must be present for the Commission to grant an exemption.
Two of the specific circumstances listed apply to this exemption request. They are:
50.12.(a)(2)(ii) Application of the regulation in the particular circumstances would not serve the underlying purpose of the rule or is not necessary to achieve the underlying purpose of the rule; and 50.12.(a)(2)(iii) Compliance would result in undue hardship or other costs that are significantly in excess of those contemplated when the regulation was adopted, oc that are significantly in excess of those i
incurred by others similarly situated; The primary purpose of the Type A test is to assure that the containment boundary is maintained in a condition such that its leakage will not exceed an allowable amount when subjected to the peak internal pressure of the design basis accident.
The maximum allowable leakage rate is associated with l
the maximum allowable accident dose to a person at the Exclusion Area Boundary (EAB) per 10 CMt 100.
The maximum allowable dose to an individual at the EAB is 25 rem whole body or 300 rem thyroid within a 2-hour period immediately following the onset of the release.
Since the reactor at LACBWR has been permanently shut down, the design basis accident, which is a recirculation line break while operating at full power, can no longer occur.
There is no postulated accident remaining which can pressurize the Containment Building.
Therefore, the Containment Building no longer needs to act as a post-accident pressure boundary.
The Fuel Element Storage Well (FESW) is located in the Containment Building.
All irradiated fuel is now being stored in the FESW.
The previously analyzed fuel damage accidents involving fuel in the FESW have been re-examined using the existing fuel loading.
These 2 accidents are a l
fuel handling accident in which 2 assemblies are damaged and a cask drop j
event in which the cladding of all the spent fuel is ruptured.
The cask drop accident is the more severe event.
The assumptions used in the re-evaluation were similar to those used in the re-racking analyses (References 8 and 9).
The only significant gaseous fission product available for release is Kr-85.
It was conservatively assumed that 30% of the Kr-85 inventory would be released to atmosphere.
No credit was taken for containment integrity.
The fuel inventory projected for October 1987 was used.
Attachment I documents the dose calculations.
If a ground level release was assumed, the projected whole body dose to a person at the exclusion area boundary was approximately 40 mrem within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> of the cask drop accident.
If an elevated release was assumed, the maximum offsite whole body dose was approximately 4.2 mrem.
Both these estimated doses are considerably below the 10 CFR 100 dose of 25 Rem (25,000 mrem) whole body within a 2-hour period.
PC4 3"a I
87090002.F 870828 PDR ADO. 05000409 P
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ATTACIMENT 1 DOSE CALCULATIONS These calculations are based on the fuel inventory projected for October 1987.
A.
Fuel Handling Accident This accident involves the rupture of the cladding of the two spent fuel assemblies with the highest inventory of Kr-85 during a fuel handling accident. The maximum dose to an individual at the Exclusion Area Boundary (EAB) from the release of Kr-85 is determined conservatively.
There is about 1.192 E+5 Curies of Kr-85 remaining in the 333 spent fuel assemblies located in the FESW.*
Fuel assemblies #4-3 and #4-18 from fuel cycle 11 should have the highest Kr-85 inventory. These fuel assemblies are computed to have 1438 Curies of Kr-85 total.
1.
Ground level release, assuming no containment building integrity for hold-up.
This is a conservative calculation and should represent a worst case situation for this type of accident.
Fumigation conditions at the EAB are assumed with a release duration of 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> commensurate with 10 CFR 100 and Regulatory G2 ides 1.24 and 1.25.
A FESW water decontamination factor of 1.0 (no decontamination) for Kr-85 is assumed. The plenum or gap Kr-85 activity represents about 15% of the total, or 279 Curies. However, for conservatism and commensurate with Table 1 of the Safety Evaluation for License Amendment No. 18, dated February 4,1980, 30% of the total Kr-85 activity, or 431.4 Curies, is assumed to be released in this accident scenario.
2.
Average Kr-85 Release Rate 6.00 E-2 Ci/sec 431.4 Curies
=
2 hrs. x 3600 sec/hr E
3.
Worst case Q for two hours at 338m NE or 338m SSE, using Regulatory Guide 1.25 = 2.2 E-3 see 3
m
- The fuel radionuclides inventory was calculated using an internal computer program, FACT, which looks at number of fuel assemblies, their power level and exposure, fission product production rate, nuclide activity, nuclide decay constant, and decay time.
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IT4-20a 1
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4.
Kr-85 average concentration at 338m.
6.00 E-2 Ci/sec x 2.2 E-3 sec = 1.32 E-4 C1 nP nP 5.
Immersion Dose Conversion at 338m.
Kr-85 Gamma Whole Body Dose Factor (Regulatory Guide 1.109):
1.61 E+1 mrem /yr x 106 uci x 1.142 E-4 yr = 1,839 mrem /hr.
uCi/m3 Ci hr Ci/m3 Whole Body Dose at 338m:
1,839 mrem /hr x 1.32 E-4 gi x 2 hr = 0.49 mrem Ci/m3 m3 Kr-85 Beta / Gamma Skin Dose Factor (Regulatory Guide 1.109):
1.34 E3 mrem /hr x 106 uci x 1.142 E-4 yr = 1.53 E5 mrem /hr uCi/m3 Ci hr Ci/sP Skin Dose at 338m:
1.53 E5 mrem /hr x 1,32 E-4 gi x 2 hr = 40.39 mrem Ci/m3 mP B.
Cask or Heavy Load Drop Accident This accident involves the rupture of the cladding of all 333 spent fuel assemblies located in the FESW, due to the droppage of a spent fuel shipping cask on top of the two-tiered racks containing the fuel.
There is about 1.192 E+5 Curies of Kr-85 present inside the 333 fuel assemblies.
Thic analysis is a conservative calculation assuming no containment integrity and a ground level release, Again, 30% of the Kr-85 inventory is assumed to be released to the atmosphere which is at least a factor of two times the fuel plenum (gap) Kr-85 inventory.
Therefore, 35,760 Curies of Kr-85 is released within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> post-cask drop accident.
1.
Average Kr-85 Release Rate 4.967 Ci/sec l
35.760 Ci
=
2 hrn x 3600 sec/hr 2
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2.
Worst Case X/Q, ground level / immersion at 338m = 2.2 E-3 sec/m3 3..
Kr-85 average concentration at 33Bm.
4.967 Ci/sec x 2.2 E-3 sec/m 1.093 E-2 Ci 3 =
m3 4.
Whole Body Dose at 338m.
1.093 E-2 Ci x 1839 mrem /hr x 2'hr. = 40.19 mrem nP Ci/m3 5.
Skin Dose at 338m:
1.53 E5 mrem /hr x 1.093 E-2 ci x'2 hr = 3.345 Rem Ci/m3 m3 C.
Elevated Releases Elevated releases, which would be more likely, would result in an estimated highest X/Q at 500m E of 2.3 E-4 sec/m3 for 0-2 hours.
Therefore, for the two accident scenarios, the offsite whole body and skin doses would be:
1.
Fuel Handling Accident a.
2.3 E-4 x 0.49 mrem = 0.05 mrem whole body penetrating 2.2 E-3 b.
1.0456 E-1 x 40.39 mrem = 4.22 mrem skin 2.
Cask Drop Accident a.
1.0456 E-1 x 40.19 = 4.20 mrem whole body penetrating b.
1.0456 E-1 x 3345 = 350 mrem skin
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