ML19246B516

Forwards Responses to NRC Comments at 790606 Meeting Re Offsite Dose Calculation Manual,For NRC Review Prior to 790716 Meeting

ML19246B516
Person / Time
Site:	Quad Cities
Issue date:	07/05/1979
From:	Naughton W COMMONWEALTH EDISON CO.
To:	Bevan R Office of Nuclear Reactor Regulation
Shared Package
ML19246B517	List: ML19246B516
References
NUDOCS 7907160294
Download: ML19246B516 (4)

Text

Commonwealth Edison One First National Plaza. Chicago, Illinois

, Address Reply to: Post Office Box 767 Chicago, Illinois 60690 July 5, 1979 Mr. Roby B. Bevan, Jr.

Project Manager ORB-3 U.S. Nuclear Regulatory Commission Washington, D.C. 20555

SUBJECT:

Quad-Cities Station Units 1 and 2 Revisions to ODCM (Offsite Dose Calculation Manual)

NRC Docket Nos. 50-254 and 50-265

Dear Mr. Bevan:

As a result of the June 6, 1979 meeting between Commonwealth Edison Ccmpa.ny and NRC Staff personnel, Commonwealth Edison has prepared responses to NRC comments at that meeting and a draft revision to the Quad-Cities Station Offsite Dose Calculation Manual (ODCM) for your review prior to our July 12, 1979 meeting.

Attachment 1 contains Commonwealth Edison's responses to comments generated at the June 6, 1979 meeting and Attachment 2 contains a draft revision of the Quad-Cities ODCM.

One (1) signed original and five (5) copies of this letter and attachments are provided for your use.

Very truly yours,

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William F. Naughton Nuclear Licensing Administrator Pressurized Water Reactors Attachments (2) j t

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ATTACHMENT 1 Docxet .os. a-Offsite Dose Calculation Manual Response to Comments Generated at CECO /NRC Meeting, Bethesda Md.

June 6, 1979

1. Comment - Add a summary of the dose calculation techniques to

_Section 1.0, Introduction.

Response - See revised Section 1.0.

2. Comment - Clarify the use of historical dispersion data by station operators in Section 3 1.2.

Response - See revised Section 3 1.2.

3 Comment - In Te.ble 7 2-8 why don't the ste.:k dose factors Si and Si have the maximum value at the unrestricted area bcundary?

Response - The S i and S factors (and as New it was discovered later, values were computed the Vi and Vi factors) ai re incorrect.

and are included in the ODCM.

N. Comment - In Section E.1.1.1 3 1, and other locations, change the beta shielding and oc'xpany factor from 0.5 to 1.0.

Response - Done 5 Ccmment - Equ'. tion 2.15 can be simplified because the - (minus) f3 C{ factor is cancelled by e + (plus) ff C{ value Response - The comment is correct but we prefer the longer equapion because it establishes the basis for the determination of C 1.

f

6. Comment - Provide data to support the Seasonal Adjustment Factor K = 0 5 in Section 2.1.2.2. .

Response - When dairy cattle are assumed to be grazing year round on pasture grass ODCM equation 2.15 has variables.

C{=0,StoredFeedConcentration fg = 1, The fraction of the year that animals grace on pasture.

(Called fp in NUREG-0133) fg = 1, The fraction of daily feed that is pasture grass when the animal graces on the pasture. (Called fs in NUREG-0133)

This leads to -

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Cf=Cf ,

(Feed Ccncentration) = (Pasture Grass Concentration)

It might reasonably be assumed frcm our discussions with local dairymen that cattle derive only half or less of their forage from

grass in the summer. The remainder coming from uncontaminated feed (C 0). Therefore fg = 0 5 would be more apprcpriate than fg = 1.[ = Consequently, C[,, C@, and the resultant dose are correspondingly reduced by 0 5 In the ODCM this factor was intro-duced into equation 2.18 by the seasonal adjustment factor K = fr.

fg = 1 X 0 5 = 0 5 for the pasture season.

Support for the value of fg f 0 5 came during a period of fresh weapon's test fallout in 1977 when a comparison study between the pasture /non-pasture situatior. was made at our Quad Cities Nuclear Station by the Idaho National Engineering Laboratory (INEL) . This study found that 100% pasture feeding produced 1-131 levels in milk 20-1500 times over those produced by normal feeding conditions on stored feed, green chop, and limited pasture. The results of that study are summe.rized below. To be conservative a factor 10 times less than the lowest factor (EL) was selected to represent

.the typical dairy conditions of northern Illinois.

Thus, by two separate arguments we have shown K = 0 5 is a con-servative adjustment factor to correct a 100% pasture grass cal-culation to normal feeding practices for the summer, pasture season.

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Dc.te On-Site Location DeckU " Turner Dairy Hansen Dairy Sampled by INEL Location tamplec by Sampled by Sanpled by

INEL CECO CECO Poor Quality G5ad F85.11ty~ Feed, Green Feed, Some Pasture Pasture Chop Pasture 10/1/77 123 pCi/1 608 pCi/1 0.4 pC1/1 4.6 pC1/1 10/9/77 102 423 5.8 -

10/11/77 78 116 -

09 10/14/77 56 346 - 1.1 10/16/77 56 271 <05 -

.. Cc= ment - In Table 7 2-1 revisp the average flow f the receiving water for fish F from 4.7 X 104 cfs to cfs.

Respcnse - Open Item.

8. Comment - In Section 5 1.1 paragraph 1, clearly specify the fre-quency of dose ccmputations performed by station personnel.

Response - Dose will be ccmputed monthly. See revised Section 5 1.'1.

9 Cc= ment - Clarify the meaning of the entries in Table 7 1-1.

Response - This was done.

10. Comment - Document the basis for r= 0 5, the crop retention factor for iodine, in Section 2.1.2.1.1 and elsewhere.

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i n the ODCM we defined the crop retention fraction to be "the fraction of deposited activity retained on crops." Depositable activity includes elemental iodine (I2) and particulate forms of iodine. The non-depositable fraction includes organic forms (principally methyl iodide, CH3 I) and certain inorganic forms .

_.(principally hypiodous acid, HOI).

For BWR's we obtained source information from Table 4.7 of reference 1, a summary of I-131 species measurements in EWR venti-lation exhausts.

Denositable Suecies Non-Denositable Suecies Mean (unweighted by 46% 54%

source contribution)

In the same publication " normalized" annual airborne releases for BWR's under power generation showed (from Tables 2-2 and 2-3):

Denositable Suecies Non-Denositable Suecies 49% 51%

Thus a value of r = 0 5 seems justifiable for BWR's. Reference 2 supports this conclusion also.

For FWR's we obtained source information from reference 3, Tables 2-7 and 2-8, average normalized I-131 releases.

Denositable Suecies Non-Denositable Suecies 31% 69%

Thus for PWR's, a value of r = 0.5 seems conservative.

In conclusion, for normal releases, a crop retention factor of 0.5 for radiciadine is approuriate. ~

estimates of projected doses' during ac(It must be cidents, noted r is that for assumed to makin?)

be 1.0 Bibliography (1) T. R. Marrer 6, Airborne Releases From EWR s for Env1rcnmental Impact Evaluations, Amendment 2 NEDO-21159-2, 77NED140, Class 1, October 1978. (Iodine-131),

(2) C. A. Pelletier, et.al. , Sources of Radiciodine at Boiling Water Reactors, EPRI NP-459, EPR1 Research Project 274-1, February 1978.

(3) A. Pelletier, et.al., Sources of Radiciodine at P-essurized Water Reactors, EPRI NP-939, EPRI Researen Projen; J7h-1, November, 1978.

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