ML19256A848

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Discusses Status of Proposed Tech Spec Revision Increasing Response Time of Encl Bldg Filtration Sys.Disagrees W/Nrc Dose Calculations.Contends 151 Rems Thyroid Dose & 3.8 Rems Whole Body Does Are Conservative
ML19256A848
Person / Time
Site: Millstone Dominion icon.png
Issue date: 01/09/1979
From: Counsil W
NORTHEAST UTILITIES
To: Reid R
Office of Nuclear Reactor Regulation
References
TAC-46174, NUDOCS 7901160231
Download: ML19256A848 (2)


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January 9, 1979 Docket _No. 50-336 Director of Nuclear Reactor Regulation Attn: Mr. R. Reid, Chief Operating Reactors Branch #4 U. S. Nuclear Regulatory Commission Washington, D. C. 20555

References:

(1) D. C. Switzer letter to R. Reid dated February 23, 1978.

(2) W. G. Counsil letter to R. Reid dated December 15, 1978.

(3) R. Reid letter to W. G. Counsil dated December 8,1978.

Gentlemen:

Millstone Nuclear Power Station, Unit No. 2 Cycle 2 Radiological Consequences Evaluation In Reference (1), Northeast Nuclear Energy Company (NNECO) proposed to revise the Millstone Unit No. 2 Technical Specifications by increasing the response time of the Enclosure Building Filtration System (EBFS) . Since the EBFS filters radioactive releases following a postulated LOCA, an increased response time would increase the calculated of fsite doses. Reference (1), therefore, also included a dose calculation utilizing the increased EBFS response time. All assumptions used in that calculation are consistent with Regulatory Guide 1.4.

However, new X/Q values were computed using meteorologinel data gathered over the past several years. It is in the development of these X/Q's that an error has been discovered. The (0 - 1) hour X/Q for the site boundary did not take the effect of fumigation into account. The correct X/Q for this time period is, therefore,1.03 x 10-4 sec/m3 rather than the 2.14 x 10-6 sec/m3 reported for this time interval in Table 2 of Reference (1) . Therefore, the calculated site boundary doses for this incident, as3uming the increased EBFS initiation time, are 151 rems to the thyroid and 3.8 cems whole body, rather than the 116 rems to the thyroid and 1.2 rems whole body reported in the Reference (1) letter.

These corrected doses are identical to those reported in Reference (2) in support of the power uprating effort and no correction to that submittal is necessary. Note that these corrected doses have incorporated dose conversion factors from Regulatory Guide 1.109 as discussed in Reference (2) .

Since in Reference (3) the NRC's Safety Evaluation approved the Technical Specification change proposed in Reference (1) and calculated doses of 210 rems to the thyroid and 7 rems whole body, the effect of this letter is merely to correct our analysis of Reference (1) . The corrected doses remain bounded by the NRC calculations and are within the limits of 10CFR Part 100. Note also that the 7 90116 0 2M f

o analyses of both Reference (1) and (2) were performed at the stretch power level of 2700 MWt. Therefore, no changes to the NRC's evaluation of this incident are anticipated to be necessary to review that portion of Reference (2) which evaluates the radiological consequences of the LOCA at 2700 MWt, since the Rcference (3) SER is bounding.

Please be advised that NNECO does not concur with the NRC Staff that the correct doses for the LOCA are the Reference (3) values, but rather, contends that the values of 151 rems thyroid dose and 3.8 rems whole body dose as reported in Reference (2) are appropriately conservative. NNECO's lack of concurrence in this regard does not invalidate the determination that the Reference (3) values are bounding for this analysis.

Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY

/ }l l A ;i.'U' W.' G . Counsil Vice President