ML20137B076
| ML20137B076 | |
| Person / Time | |
|---|---|
| Site: | Callaway  |
| Issue date: | 01/09/1986 |
| From: | Schnell D UNION ELECTRIC CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| ULNRC-1237, NUDOCS 8601150042 | |
| Download: ML20137B076 (17) | |
Text
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UNION ELECTRIC COMPANY January 9, 1986 1901 Grotiot Street St. Louis Donald F. Schnell Vice President Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C.
20555
Dear Mr. Denton:
ULNRC-1237
/
DOCKET NUMBER 50-483 CALLAWAY PLANT FUEL HANDLING ACCIDENT IN CONTAINMENT DOSE ANALYSIS Union Electric Company is transmitting three original and 40 conformed copies of an application for amendment to Facility Operating License No. NPF-30 for Callaway Plant.
This amendment request results from a new fuel handling accident dose analysis for inside containment in which no credit is taken for operation of the hydrogen mixing fans or containment coolers during fuel handling operations.
The present analysis as described in Callaway Standard Plant Final Safety Analysis Report (FSAR) Section 15.7.4 is based on two hydrogen mixing fans and two containment coolers being operated on high speed during fuel handling operations.
Operation of the mixing fans and containment coolers results in drafts and high noise levels in areas where maintenance is being parformed during outages and thus hampers communication.
In addition operation of two mixing fans and two containment coolers could hinder or prevent repairs and maintenance work on associated equipment and, therefore, is not desirable.
The new analysis results in doses which are still well below the guidelines of Standard Review Plan, Section 15.7.4, but are higher than the doses presently reported in the Callaway FSAR.
Under the criteria of 10CFR50.59, this new analysis is deemed to involve an unreviewed safety question in that the consequences of an accident previously evaluated in the FSAR may be increased and, therefore, Commission approval is required prior to implementation.
The attachments to this letter include:
A) Safety Evaluation, B) No Significant Hazards Evaluation, and C) proposed marked-up FSAR pages.
The FSAR pages will be incorporated in a future FSAR revision following Commission approval.
No Technical Specification changes are required as a result of the new analysis.
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[g(p 8601150042 860109 PDR ADOCK 05000403
$$f 3 g7 1
P PDR Mailing Address: PO Box 149 St. Louis MO 63166
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It is requested ~that NRC review this amendment request on an expedited basis.
Refuel 1 for Callaway will begin on or about February 28, 1986 and NRC approval will help facilitate an orderly and efficient refueling outage.
Enclosed is a check for the $150.00 application fee as required by 10CFR170.12.
Very truly yours,
~
/
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[
Dona Schnell i
DS/lw Attachments:
A)
Safety Evaluation B)
No Significant Hazards (Evaluation)
C)
Proposed Marked-up FSAR Pages i
A
STATE OF MISSOURI )
)
Robert J.
Schukai, of lawful age, being first duly sworn upon oath says that he is General Manager-Engineering (Nuclear) for Union Electric Company; that he has read the foregoing document and knows the content thereof; that he has execute d the same for and on behalf of said company with full power and authority to do so; and that the f acts therein stated are true and correct to the best of his knowledge, information and belief
/
By Robe d Schukai General Manager-Engineering Nuclear SUBSCRIBED and sworn to before me this [/h day of gnaep, 198f hfl U
BARBAR b Ad [ f NOTARY PUBUC, STATE OF MISSOURt MY COMMISS10M EXP1RES APRIL 22,1989 ST. LOUIS COUNTY
cc:
Gerald Charnoff, Esq.
Shaw, Pittman, Potto & Trowbridge 1800 M.
- Street, N.W.
Washington, D.C.
20036 Nicholas A.
Petrick Executive Director SNUPPS
- 5. Choke Cherry Road Rockville, Maryland 20850 G. C. Wright Division of Projects and Resident Programs, Chief, Section lA U.S. Nuclear Regulatory Commission Region III 799 Roosevelt Road Glen Ellyn, Illinois 60137 Bruce Little Callaway Resident Office U.S. Nuclear Regulatory Commission RRil Steedman, Missouri 65077 Tom Alexion Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Mail Stop P-316 7920 Norfolk Avenue Bethesda, MD 20014 Ron Kucera, Deputy Director Department of Natural Resources P.O. Box 176 Jefferson City, Missouri 65102 l_
Attachment A ULNRC-1237 SAFETY EVALUATION FUEL HANDLING ACCIDENT IN CONTAINMENT NEW DOSE ANALYSIS Union Electric has performed a new analysis of the fuel handling accident in containment for site boundary and low population zone (LPZ) doses.
The original analysis as described in FSAR Section 15.7.4 assumed that, following a fuel handling accident in containment, the radioactive release mixed uniformly with 20 percent of the containment volume prior to release into the environment.
Twenty percent corresponds to 500,000 cubic feet.
This assumption was based on the premise that two hydrogen mixing fans and two containment coolers would be operating at full speed during fuel handling operations in containment.
The new analysis assumes that, prior to release into the environment, the release mixes with 0.96 percent of the containment volume which corresponds to 24,000 cubic feet.
This assumption is based on an analysis which models the radioactive release as a plume originating in the refueling pool over the upender and traveling to the purge duct.
This analysis determined that the plume would mix with 24,000 cubic feet with no hydrogen mixing fans or containment coolers operating.
Although the release was modeled as originating from the refueling pool, the dose calculation still utilized 1.2 failed fuel assemblies as a basis for the release.
The release origi-nation point in the refueling pool was utilized for conservatism as it was the nearest point to the purge duct where fuel handling operations are carried out.
All other assumptions and parameters used in the new analysis are the same as those used in the original analysis detailed in FSAR Section 15.7.4.
The new analysis was performed since the original analysis assumed the operation of two hydrogen mixing fans and two containment coolers during all fuel handling operations in containment to support the dose calculation.
Operation of the mixing fans and containment coolers results in drafts and high noise levels in areas where maintenance is being performed during outages and thus hampers communication.
In addition, operation of the fans and coolers can hinder repair and maintenance work during outages and, therefore, is not desirable.
The physical layout inside containment is such that in order to perform certain work on a reactor coolant pump requires removal of its associated hydrogen mixing fan.
The results of the original dose calculation and the new dose calculation are shown below.
As can be seen, the doses for both analyses are well below the guidelines in the Standard Attachment A ULNRC-1237 Review Plan (SRP), Section 15.7.4, which calls for twenty-five percent of the 10CFR100 dose allowables of 25 rem whole body and 300 rem thyroid (i.e.,
6 rem whole body and 75 rem thyroid.)
SITE BOUNDARY DOSE (REM)
THYROID WHOLE BODY THYROID WHOLE BODY NEW ANALYSIS 20.0 0.07 2.6 0.0091 OLD ANALYSIS 1.1 0.004 0.15 0.00052 As discussed in detail in the attached No Significant Hazards Evaluation (Attachment B), the proposed new analysis does not increase the probability of an accident or malfunction previously evaluated, does not create the possibility of an accident or malfunction of a different type than previously evaluated, nor reduce the margin of safety as defined in the Technical Specification Bases.
The re fore, since the proposed change only affects the consequences of an accident previously evaluated and the conse-quences are still well below the applicable regulations and supplen. ental guidance, this amendment request does not adversely affect the health and safety of the general public.
2-
Attachment B ULNRC-1237 NO SIGNIFICANT HAZARDS EVALUATION A revised fuel handling accident analysis for inside containment has been performed.
This analysis does not take credit for any forced convection mixing of the release with the containment free volume.
The proposed change deletes the commitment in FSAR Section 15.7.4 to run two hydrogen mixing fans and two containment coolers during fuel handling operations in containment.
The commitment was made to support the assumption that the radioactive release resulting from a fuel handling accident inside the containment would be uniformly mixed with 20 percent of the containment free volume prior to release of the radioactivity into the environment.
The operation of the mixing fans and containment coolers results in drafts and high noise levels in areas where maintenance is being performed during outages.
Further, planned operation of two mixing fans and two containment coolers could hinder or prevent repairs and maintenance work on associated equipment and, therefore, is not desirable.
The following evaluations, performed in accordance with 10CFR50.91 and 10CFR50.92, verify that no significant hazard will result from this change:
1.
Does the proposed change involve a significant increase in the probability or consequences of an accident previously evaluated?
A new dose analysis has been performed for the fuel handling accident in containment which does not take credit for the operation of any mixing fans or containment coolers and uses 0.96 percent mixing.
This mixing volume (24,000 cubic feet) was calculated assuming that the radioactive release originates in the refueling pool over the upender machine and travels as a plume to the containment purge exhaust duct.
This release origination point is used as it is the closest point to the purge exhaust duct where any fuel handling operations are carried out.
In spite of the assumed release origination point, the dose calculation utilizes 1.2 failed fuel assemblies as the basis for the release, as required by R.G. 1.25.
Likewise, no parameters or assumptions other than the mixing volume have changed from the original dose analysis which is detailed in Callaway FSAR Section 17.5.4.
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Attachment B ULNRC-1237 The results of the new dose analysis are tabulated below:
Site Boundary Dose (REM) / Low Population Zone Dose (REM)
Thyroid 20.0 2.6 Whole Body 0.07 0.0091 The guidelines set forth in 10CFR100.11 stipulate that doses to individuals at the site boundary and in the low population zone (LPZ) following a postulated fission product release, shall not exceed 25 rem to the whole body or 300 rem to the thyroid.
The Standard Review Plan, Section 15.7.4, provides further guidance that whole body and thyroid doses at the exclusion area and LPZ boundaries be well within the 10CFR100,11 guidelines.
"Well within" is defined as 25 percent or less of the 10CFR100.ll guidelines or 75 rem to the thyroid and 6 rem to the whole body.
As can be seen, the resultant doses for the fuel handling accident inside containment with no mixing fans or containment coolers operating are well below the guideline doses in SRP Section 15.7.4, and are likewise a fraction of the 10CFR100.11 guideline doses.
Also, since there are no adverse pressure or tempera-ture ef fects due to a fuel handling accident, dele', tion of the commitment to run the mixing fans and containment coolers during fuel handling in containment will have no effect on these parameters.
Therefore, there will be no significant increase in the conse-quences of any accident previously evaluated.
Similarly, it can be seen from the discussion above that the only accident during refueling for which operation of the fans and coolers is assumed is the fuel handling accident.
For this accident, their operation was assumed to mitigate the consequences of the accident - not to prevent the accident.
Not operating the fans and coolers during refueling does not affect any other safety related equipment.
There-fore, the deletion of the FSAR commitment to run two hydrogen mixing fans and two containment coolers during fuel handling operations in containment will not increase the probability of any accident previously evaluated.
Note that operators may run one or more hydrogen mixing fans and containment coolers while handling fuel in containment, if desired, to maintain temperature and air flows at a comfortable level.
Use of the fans and coolers does not invalidate the new dose analysis for a fuel handling accident inside containment as air flow Attachment B ULNRC-1237 fr.om the fans and coolers would only mix a radioactive release with a greater percentage of the containment air volume.
2.
Does the proposed change create the possibility of a new or different kind of accident from any evaluated?
l As detailed above, the subject change is a deletion of 1
an FSAR commitment to operate hydrogen mixing fans and containment coolers during fuel handling operations in containment.
Operation of the fans and coolers was based only on the need to provide mixing in the event i
of a fuel handling accident and for personnel comfort.
These fans and coolers perform no other function during 3
refueling.
The reanalysis demonstrates the accept-ability of not operating tte fans and coolers with respect to a fuel handling accident and the operators can still operate them as needed for personnel comfort.
Therefore, it is apparent that a change of this nature will not create the possibility of a new or different kind of accident from any evaluated previously occurring.
3.
Does the proposed change involve a significant reduction in a margin of safety?
The proposed change, as discussed previously, involves a deletion of the commitment in FSAR Section 15.7.4 to run hydrogen mixing fans and containment coolers during l
fuel handling operations in containment.
As indicated, the subject change has been evaluated for its effects i
on the site boundary and LPZ doses due to a fuel handling accident inside containment, and it has been verified that these doses are well below the guideline doses in SRP Section 15.7.4.
It has also been verified that the subject change will have no affedt on containment pressure and temperature following a fuel j
handling accident in containment.
i j
Likewise, the proposed change only deletes the_
commitment to run mixing fans and containment coolers during fuel handling.
As noted, the operators still have the option to run mixing fans and/or contal'nm'ent coofers durin,g shutdown or fuel handling operations inside containment.
Therefore, there will be no reduction in the safety and comfort of operators and maintenance personnel inside containment.
Conclusion From the previous evaluation performed in accordance with 10CFR50.91 and 10CFR50.92, it is concluded this amendment request doen not involve a significant increase in the probability or consequences of an accident or other adverse condition over t
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Attachment B ULNRC-1237 previous evaluations; nor create the possibility of a new or different kind of accident or condition over previous evaluations; nor involve a significant reduction in a margin of safety.
Based on the foregoing, the requested amendment does not present a significant hazard.
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Attachment C ULNRC-1237 PROPOSED MARKED-UP STANDARD PLANT PSAR PAGES Page 15.7-13 Tables:
15.7-2, Sheet 3 15.7-7, Sheet 1 and 2 15.7-8 Insert Page
SKUPPS I
Kr-85, and 10 percent of the total radioactive iodine
,,4 contained in the fuel rods at the time of the accident.
, f.
The pool decoritamination factor.is 1.0 for noble gases.
f
- g. ' The effective pool decontamination factor is 100 for iodine.
h.
The iodine above the fuel pool is assumect to be composed of 75 percent inorganic and 25 percent organic species.
'i., The activity which escapes from the pool is asrumed to be available for release to the environment in a time period of 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />.
j.
No credit for decay or depletion during transit to the site boundary and outer boundary of the low-population zone is assumed.
k.
No credit is taken for mixing or holdup in the fuel building atmosphere.
The 111ter efficiency for the ESF emergency filtration system is assumed to be 90 percent for all species of iodine.
(
l.
Fortheinsidethlereactorbuildingcase, conservative
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credit has been taken for the uixing of the radio-activity that is evolved from the refueling pool with a portion of the reactor building free volume. t-
-h a s-bee n-a ss ume d -tha tr-b'a s e de -the-no rma l-ve n tila ti o n.
air-curants-uithin-the-reactor-building established-
-by-tho-centesnment air eccler: (normal.-flow-rate-of-
-140 000-ofm-pet-air-cooler-) -and-the-hydro ;.en-mixing-
, Ws 7
-fanc (norma 4-f4ew-rate-of 85,000- cfa-per--mixing-fan.)-
\\
4,he-releaWrem the -d:: ged -fuel-will-mix uniformly
-i n-a-m i nimum -o f-20-pe rce nt-of - the -- con tainment-free-
-volume-(-500, 000 cubic-feet-).
ceneidering one train-af-air-coolers-(4So 400-cfm) and-one-tran-of-hydrogen r
-mi-M i ng-(4-70 r000-c fm ) r-one--co mplete-vol ume-cha nge-o f
--the-containment-atmosphere-every 6 minutes is expected, m.
The containment purge rate is 20,000 cfm.
n.
The containment purge is isolated within 25 seconds from the time the activity reaches the purge duct.
15.7.4.5.J.3 Mathematical Models Used in the Analysis Mathematical models used in the analysis are described in the following sections:
I a.
The mathematical models used to analyze the activity released during the course of the accident are de-scribed in Appendix 15A, Section 15A.2.
15.7-13 I
SNUPPS TABLE 15.7-2 (Sheet 3)
Regulatory Guide 1.25 Case 1 Case 2 Position (in Fuel Building)
(in Reactor Building) decontamination factor of 100 (i.e., 99% of the total iodine released from the damaged rods is retained by the pool water).
This difference in decontamination factors for inorganic and organic iodine species results in the l
iodine above the fuel pool being i
composed of 75% inorganic and
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25% organic species.
h.
The retention of noble gases in complies.
A decon-Complies.
A decon-the pool is negligible (i.e.,
tamination factor of 1 tamination factor decontamination factor of 1).
is used.
of 1 is used.
i.
The radioactive material that Complies.
A 0-2 hour
-The-release fra-peel-escapes from the pool to the release from the pool
-to-the-building is pgt building is released from the to the building to the aute= tically ise-building 2 over a 2-hour time environment is assumed.
lated upon--detection h
period.
ef-the-f4-rst-trace.
of relcacc.
Thuc, the
-release -is-contained-
-in-the reacter building
-after--iselat4 erb j.
If it can be shown that the build-Not applicable:
No credit is taken ing atmosphere is exhausted through complies with Regula-for the normal purge adsorbers designed to remove iodine, tory Guide 1.52 as de-filters.
the removal efficiency is 90% for scribed in Table 9.4-2 inorganic species and 70% for organic species.4 i
SNUPPS
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TABLE 15.7-7 T
PARAMETERS USED IN EVALUATING THE RADIOLOGICAL CONSEQUENCES OF A FUEL-HANDLING ACCIDENT In Fuel Building In Reactor Building I.
Source Data a.
Core power level, MWt 3,565 3,565 b.
Radial peaking factor 1.65 1.65 c.
Decay time, hours 100 100 d.
Number of fuel assem-1.0 1.2 blies affected e.
Fraction of fission product gases con-tained in the gap region of the fuel assembly Per R.G.
1.25 Per R.G.
1.25 II.
Atmospheric Dispersion Factors See Table 15A-2 See Table 15A-2 III.
Activity Release Data a.
Percent of affected fuel assemblies gap activity released 100 100 b.
Pool decontamination factors 1.
Iodine 100 100 2.
Noble gas 1
1 c.
Filter efficiency, percent 90 0
d.
Building mixing vo-lumes assumed, percent of total volume 0
24-Q.%
e.
HVAC exhaust rate, cfm 9,000 20,000 f.
Building isolation time, sec ESF filters, no 25 isolation re-quired 9
Activity release period, hrs 2
Release terminated after 25 seconds b
.. D SNUPPS J
TABLE 15.7-7 (Sheet 2) h.
Activity released to the environment Isotope 0-2 hr (ci) 0-2 hr (ci)
I-131 5.34E+1
-1. 00E : 1 \\.%%Y 41 l
I-133 6.23E+0 l r24E+& L\\%U (
Xe-131m 6.19E+2 1.23":1 LW1*).
Xe-133m 1.17E+3
- 2. 30:::1 5.celb t Xe-133 9.89E+4 1.^7Et3 1.MU %
Xe-135 8.30E+1 1.05":0 1.%% U \\
3.75E+3-7.00":1 \\.h h h M
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.~- c--
.-7
._w,
..._m--
i SNUPPS TABLE 15.7-8 RADIOLOGICAL CONSEQUENCES OF A FUEL HANDLING ACCIDENT Doses (rem)
C2112.127
':.'ci f C :ch In Fuel Building Exclusion Area Boundary (0-2 hr)
Thyroid 5.6E+0 0.2E+0 Whole-body 1.9E-1 1.4C-1 Low Population Zone Outer Boundary (duration)
Thyroid 7.3E-1 5.5C 1 Whole-body 2.5E-2 1.02-2 In Reactor Building C
Exclusion Area Boundary (0-2 hr)
Thyroid 1.ose 1.10:0 0.00-1 Whole-body 7.cE-1L 0.02 0 0.00-0 Low Population Zone Outer Boundary (duration)
Thyroid 2..WE MD 1. 5 0 -1 1.15 1 Whole-body R.sE-3 5.25 0 0.0 0
l Rev. 44-W L-
INSERT 1 It is assumed that no containment coolers or hydrogen mixing fans are operating.
An analysis was performed to estimate the volume of air which would mix with the release as it traveled from the refueling pool to the containment purge ducts.
For conservatism, the release was modeled as originating from the upender machine since thir. is the area of the refueling pool closest to the containment purge duct.
This analysis determined that the release would mix with approximately 24,000 cubic feeg which is 0.96% of the total containment free volume (2.5 X 10 cubic feet).
INSERT 2 The containment shutdown purge lines are automatically isolated upon detection of high radioactivity in the containment.
It is conservatively assumed that isolation does not occur until 25 seconds after the release.
Therefore, the greatest portion of the activity is contained in the reactor building following the event.
a e
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