ML20205Q611
| ML20205Q611 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 04/15/1999 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20205Q610 | List: |
| References | |
| NUDOCS 9904210327 | |
| Download: ML20205Q611 (3) | |
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UNITED STATES 5
E NUCLEAR REGULATORY COMMISSION
~{t WASHINGTON, D.C. 20S5fHX101 e
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- *.. +,o SAFETY EVALUATION BY THE OFFICE OF N_U_ CLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. P1n TO FACfLITY OPERATING LICENSE NO. DPR-50 METROPOLITAN EDISON COMPANY JERSEY CENTRAL POWER & LIGHT COMPANY PENNSYLVANIA ELECTRIC COMPANY GPU NUCLEAR. INC.
THREE MILE ISLAND NUCLEAR STATION. UNIT NO.1 l
DOCKET NO. 50-289
1.0 INTRODUCTION
By letter dated October 15,1998, General Public Utilities Nuclear, Inc. (the licensee),
submitted an application for approval of a proposed change to the Updated Final Safety Analysis Report (UFSAR) for the Three Mile Island, Unit 1, (TMI-1) nuclear power plant. The proposed change will amend the atmospheric dispersion (x/Q) values and conforming dose conversions for the exclusion area boundary (EAB) and low population zone (LPZ) in some of the postulated accident dose consequence assessments. By letters dated February 3 and 12, 1999, the licensee submitted additionalinformation regarding the proposed change. The revised x/O values and resultant dose estimates are higher than those previously calculated for the postulated accidents to which they apply. The February 3 and 12,1999, letters were within the scope of the original application and did not change the staff's no significant hazards consideration determination.
2.0 EVALUATION The licensee has proposed a revision to some of the x/Q values using the methodology described in Regulatory Guide 1.145, " Atmospheric Dispersion Models for Potential Accident Consequence Assessments at Nuclear Power Plants," to ensure consistency with the TMI-1 EAB and LPZ distances defincd in Section 5.1.1 of the TMI-1 Technical Specifications (TS).
Previous calculations assumed a variable EAB. In addition, the licensee has used a larger population of more recent meteorological data to provide a better statistical representation of meteorological cor.ditions in the sits vicinity than the data used in the previous calculations.
The licensee performed calculations to determine x/O values at the EAB and LPZ using onsite meteorological data measured during calendar years 1992,1993,1995, and 1996. Wind measurements at the 30.3 meter level were adjusted to represent winds at the 10 meter level.
Atmospheric stability was based upon delta-temperature measurements made between the 45.5 and 10 meterlevels. The above x/O calculations were made on a direction-dependent 9904210327 990415 PDR ADOCK 05000289 P
PDR I
O 2-basis assuming a fixed EAB of approximately 610 meters and an LPZ distance of approximately 3200 meters (two miles) as described in the TMI-1 technical specifica,tions (Figure 5-1 indicates the exclusion area is a stretched circle centered equidistant between the TMI 1 and TMI-2 reactor buildings with a circular radius of 610 meters centered at each reactor building). Distances wers then calculated to represent the minimum distance frorn the edge of the TMI-1 reactor building to the EAB or LPZin each of the 16 direction sectors. Calculations were made for each hour of the 4-year period and cumulative probability distributions constructed for each of the sectors. The larger of the maximum 0.5 percentile direction-dependent and 5 percentile direction-independent x/O valus was chosen as the representative x/Q value. The highest 1-hour 0.5 percansle x/Q value calculated for the EAB was detarmined to be 8.0 E-4 sec/m* at a distance of 588 rueters in the North sector. x/O values for the LPZ for longer time periods were determined by plotting a straight-line log-log interpolation between 1
the 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> x/O plotted at 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> anr' the annual average x/O values. The t:irection in which the selected x/O values occurred as shown below varies over the time periods.
The staff reviewed the licensee's analysis and performed confirmatory calculations using the atmospheric dispersion model described in Regulatory Guide 1.145 and information provided by the licensee. The licensee's estimates are approximately 10 to 20 percent lower than the staff's calculations and the directional sector in which the maximum value occurred varied dependent upon the period examined. The staff concludes that these variances are due to differences in the specifics of the calculational procedures, including use of different computer codes. The staff further concludes that these differences are not significant and that the licensee's calculat;ons are acceptable. The results are as follows:
Licensee's Staff Accident Revised x/Q s x/Qs Period Location (s/m )
(s/m )
0 - 2 hrs EAB 8.0 E-4 8.3 E-4 0 - 2 hrs LPZ 1.4 E-4 2 - 8 hrs LPZ 6.0 E-5 0 - 8 hrs LPZ 6.2 E-5 8 - 24 hrs LPZ 3.9 E-5 4.1 E 5 1 - 4 days LPZ 1.6 E-5 1.7 E-5 4
4-30 days LPZ 4.0 E-6 4.9 E-6 The licensee did not re-analyze the radiological consequences resulting frc a the design basis accidents analyzed in Chapter 14 of the TMI-1 UFSAR. Instead, the licenswa recalculated the radiological consequences by the ratio of the revised x/Q to the xiQ in the UFSAR. Since the radiological consequences are directly procortional to r/Q, the staff finds that the direct conversion of the doses in the UFSAR is acceptable. Therefore, the staff has determined that the proposed revisioi, of bie x/O values and conforming dose conversions is acceptable. The doses resulting from the revised x/O values are being reviewed under a separate licensing action.
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3.0 STATE CONSULTATION
in accordance with the Commission's regulations, the Pennsylvania State official was e,qtified of the proposed issuance of the amendment. The State official had no comments.
4.0 ENVIRONMENTAL CONSIDERATION
i I
The amendment changes a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20. The NRC staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation expocu. n. The Commission has previously issued a proposed finding that the amendment invd no significant hazards consideration, and there has been no public comment on sucn nnding (63 FR 64117). Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b) no environmentalimpact I
statement or environmental assessment need be prcpared in connection with the issuance of the amendment.
5.0 CONCLUSION
The Commission has concluded, based on the considerations discussed above, that: (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor: L. Brown Date: April 15,1999 i