ML20010E412
| ML20010E412 | |
| Person / Time | |
|---|---|
| Site: | Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png |
| Issue date: | 08/26/1981 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20010E408 | List: |
| References | |
| NUDOCS 8109040094 | |
| Download: ML20010E412 (4) | |
Text
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UNITED STATES
[
~j NUCLEAR REGULATORY COMMISSION
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- y WASHINGTON, D. C. 20555
- ,e E'1VIRONMENTAL EVALUATION BY THE OFFICE OF NUC_ LEAR REACTOR REGULATION SUPPORTING AMENDMENT NO. 40 TO FACILITY OPERATING LICENSE NO. DPR-61 CONNECTICUT YANKEE ATOMIC POWER COMPANY HADDAM NECX PLANT DOCKET NO. 50-213
1.0 INTRODUCTION
By letter dated July 16, 1980, as amended by letter dated October 16, 1980, Connecticut Yankee Atomic Power Company (CYAPC0) (the licensee) requested changes to the Environmental Technical Specifications (ETS) for the Haddam Neck Plant. The proposed changes would revise the instantaneous release D
rate limit for noble gases by incorporating a new X/Q factor and reducing the beta fraction used in the instantaneous release rate equation [Section 2.4.3.1, Equation (1)].
2.0 DISCUSSION The present limit, as specified in Equation 1 of ETS Section 2.4.3.1 is:
fQiv[94Ejy + 460 f ]
< 1 jg i
Where Qiy = release rate of nuclide i in Ci/sec Ejy = the average gamma energy per disintegration for nuclide i Tig = the average beta energy per disintegration for nuclide i The derivation of the above formula was based on maintaining the. dose rate at the critical site boundary within 10 CFR 20 limits.. The location 520 maters WNW used in the derivation was 3.2 x 10 g/Q value at a sec/m3, This X/Q was calculated prior to 1975 with data from the old meteorological l
tower at the Haddam Neck site. The old tower had temperature instrumentation at 5 ft. and 100 ft. and wind instrumentation at 100 ft.. above grade elevation so that the wind data may not have been representative of the 175 foot stack at the site.
Furthermore, the temperature sensor separation did not conform to Regulatory Guide 1.23 requirements.
For these reasons a new meteorological tower was constructed in 1974 at a different location with instrumentation levels at 33 ft.
and 196 ft. The new tower,thus,provides data more repre-sentative of the plume conditions.
i' 8109040094 810826 DR ADOCK 0500
. Also, the X/Q value of 3.2 x 10-5 sec/m3 was calculated prior to the development of Regulatory Guide 1.111 and is based on less realistic methodology.
The licensee performed calculations of annual average X/Q's using data from the new meteorological tower and the methodology of Regulatory Guide 1.111 for the years 1975,1976 and 1977, and submitted the methodology and assumptions for staff review in the latest revision to the proposed Offsite Dose Calculation Manual (W,. G. Counsil letter to B. K. Grimes dated August 1,1979). Meteorological data from the new tower for the year 1975 was submitted to the staff as part of CYAPCo's
" Demonstration of Compliance with Appendix I" (D. C. Switzer letter to Chief, Operating Reactors Branch #1, dated June 4,1976). The results of the licensee's calculations show a maximum annual average X/Q of 1.4 x 10-5 sec/m3 at the site boundary 510 meters NfM, which occurred during 1975.
The licensee, therefore requesM that the ETS be updated to include the X/Q value of 1.4 x 10 5 rather than 3.2 x 10-5 in the basis for the instantaneous release rate limit.
Since both the beta and gamma dose are directly related to the X/Q, this requires division of the constants in the release limit formula by a factor of:
3.2 x 10-5/1.4 x 10-5 = 2.3 Thus, the new limit would become:
fQiv [41Eiy+200E{[]<_ 1 Additionally, the basis for the existing Technical Specification limit provides that the total dose, gamma plus beta fractions combined, be less than 500 mrem.
This is not consistent with the present criteria for specifying instantaneous release rate limits to ensure compliance with 10 CFR 20. NUREG-0133, " Preparation of Radiological Effluent Technical Specifications for Nuclear Power Plants" dated October 1978 states:
"The instantaneous does rate in unrestricted areas... due to radioactive materials released in gaseous effluents from the site.shall be limited to the following values:
a.
The dose rate limit for noble gases shall be <500 mrem /yr to the total body and <3000 mrem /yr. to the skin...."
The existing Technicd Specification limit is more co" ervative by a factor of six for the allowable skin dose. The licens e, therefore, proposes to reduce the constant tenn in the beta fraction of the equation by a factor of six so that the new equation would become:
fQiv [41G + 34fii]
_ 1
, 3.0 EVALUATION The staff performed an independent analysis of the 1975 meteorological data, using the constant mean wind direction model of Regulatory Guide-1.111 and building wake effects, both with and without consideration for rccirculation effects.3 Without recirculation, the staff calculated a X/Q of 5.8 x 10-6 sec/ m. With recirculation, the resultant X/Q is 3
3 2.3 x 10-5 sec/m. The average of these two values is 1.4 x 10-5 sec/m,
Since the equation in question is the instantaneous release rate, the effects of recirculation would be negligible, s'o that the X/Q value proposed by the licensee is slightly more conservative than what the staff would propose. We therefore conclude that this new X/Q value of 1.4 x 10-5 sec/m3 is acceptable.
We also agree that the reduction in the beta fraction by a factor of.
siA would make the equation consistent with current criteria and we therefore conclude that it is acceptable.
As a result of these cb.ges, Equation (1) of ETS Section 2.4.3.1 may be changed to read:
34Ejg ] <_ 1 IQiv [41Ejy
+
i This will result in a factor of 10 increase in the allowable instantaneous rate. However, because the allowable quarterly and annual release rates are not changed, because the limits on the total amount of radioactive
. material allowed to be released are not changed, and because the new release rate will still be only a small fraction of the maximum permitted by 10 CFR Part 20, we conclude that the new limit is acceptable.
4.0 ENVIRONMENTAL CONCLUSION We have determined that the amendment does not authorize a change in effluent types or total amounts nor an increase in power ~ level and will not result in any significant environmental impact. Having made this determination, we have further concluded that the amendment involves an action which is insignificant from the standpoint of env'ronmental impact and pursuant to 10 CFR 51.5(d)(4) that an environmental impact statement or negative declaration and environmental impact appraisal need not be prepared in connection with the issuance of this amendment.
5.0 CONCLUSION
We have concluded, based on the considerations discussed above, that (1) because the amendment does not involve a significant increase in the probability or consequences of accidents previously considered and does
.oc involve a significant decresse in a safety margin, the amendment does not involve a significant hazards consideration, (2) there'is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (3) such activities will be con-ducted in compliance with the Commission's regu'lations and the issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public.
Date: August 26, 1981
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