ML20126G680
| ML20126G680 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 03/24/1981 |
| From: | Garrity J Maine Yankee |
| To: | Clark R Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20126G683 | List: |
| References | |
| FMY-81-45, JHG-81-94, NUDOCS 8103310246 | |
| Download: ML20126G680 (2) | |
Text
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' EAllE BRIINEE 'AT0ml0 POWER 00MPARS *
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ENGINEERING OFFICE FRAMINGHAM, MASSACHUSETTS 017ot ei7.s72.stoo T7J 2.C.2.1
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United States Nuclear Regulatory Commission 9
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Washington, D. C.
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Attention:
Office of Nuclear Reactor Regulation Robert A. Clark, Chief 4
Operating Reactors Branch No. 3 Division of Licensing
References:
(a) License No. DPR-36 (Docket No. 50-309)
(b) Letter from USNRC to MYAPC dated January 17, 1977 (c) Letter from MYAPC to USNRC dated March 18, 1977 (d) Letter from USN?.C to MYAPC dated November 30, 1978 (e) John N. Hamawi, "SKIRCN: A Computer Code for Determining Atmospheric Dispernion Conditions for Design basia Accident Evaluacions," Yankee Atomic Electric Company Technical Report, YAEC-1138, October 1977 (f) Regulatory Guide 1.XXX, " Atmospheric Dispersion Models for Potential Accident Consequence Assessments at Nuclear Power Flants,"
U.S. Nuclear Regulatory Commission, October 1978 (g) Letter from MYAPC to USNRC dated February 5,1981.
(h) Letter from USNRC to MYAPC dated January 23, 1981 (i) NRC Regulatory Guide 1.145, " Atmospheric Dispersion Models for Pctential Accidenc Consequence & Assessments at Nuclear Power Plants", 1979.
Dear Sir:
Subj ec t :
Evaluation of Radiological Consequences of a Postulated Spent Fuel Handling Accident Inside Containment.
Your letter (reference h) indicated that you were unable to verify the appropriateness of the value of the one hour Exclusion Area Boundary (EAB) atmospheric dispersion factor (X/Q) used in our calculations of radiological consequences of the hypothecical fuel handling accident inside containment
( FRAIC); therefore you assumed X/Q = 7.7 x 10-4 sec/m3 in your independent calculations. Use of your assumed value in your calculations resulted in an EAB thyroid dose of 163 Rem.
Our calculations, using a value of X/Q = 5.36 x 10-4 sec/m3 derived from site meteorological data, indicated an EAB thyroid dose of 114 Mem.
Both calculations show the EAB thyroid dose attributable to a hypothetical FHAIC at Maine Yankee to be considerably lower than the upper limit of 300 Rem thyroid set forth in the Commission's regulations (10CFR Part 100).
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' I; United States Nuclear Regulatory Commission Page Two Attn: Robert A. Clark, Chief March 24, 1981 i
The X/Q value used in Maine Yankee's analysis was obtained by application of the SKIRON code (reference e), fully described in attachment.1, to site meterological data spanning the period. from January ~ to December 1977, adjusted to~take account of the change in acceptable exceedance probability from the
. value of 0.6% called for in the draft of Regulatory Guide 1.XXX.at the time th'e calculation was originally performed' to the current acceptable exceedance probability of 0.5%, specified.in Regulatory Guide - 1.145 (reference i).
At the 0.6% exceedence probability, the 1977 data resulted in X/Q = 5.133 3
x 10-4 sec/m. Adjustment to the 0.5%.exceedance probabilty yields X/Q =
3 5.36 x 10-4 sec/m, the value used in our analysis.-
-Attachment 2 documents the atmospheric dispersion factor calculation described above.
An additional calculation of one' hour X/Q values was performed using site data collected during 1979 The resultant'X/Q,'the worst of the 16 sector X/Q's calculated at 0.5% exceedance probability, is X/Q = 5.40 x 10-4 3
sec/m, essentially identical to that used.in the FRAIC consequence calculation.
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' documents the atmospheric dispersion factor calculation described above using 1979 meterological dataa Maine Yankee's technical specification 5.8.1.b requires that written procedures be. utilized to govern refueling operations. These procedures will
.j be reviewed and revised as necessary prior.to the 1981 refueling'to ensure the availability of adequate containment integrity during movement of irradiated fuel within the contcinment.
t We trust this additional information is sufficient to. allow you to verify
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the appropriateness of the atmospheric dispersion factor we used in-assessing the FHAIC.
I Sincerely yours, i
MAINE YANKEE ATOMIC F0WER COMPANY i
John H. Garrity, Diredpor
-Nuclear Engineering & Licensing JHG/bjp Attachments s
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