ML19220A733
| ML19220A733 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 05/29/1974 |
| From: | Arnold R Metropolitan Edison Co |
| To: | Anthony Giambusso US Atomic Energy Commission (AEC) |
| References | |
| NUDOCS 7904240189 | |
| Download: ML19220A733 (3) | |
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METPOPOLITAN EDISON CCMPN
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R2a:WG. as.Nsytwa "Mr ILI?-CLE 29 - 2n- -
Zay 29, 10~L Mr. A. Giamb us so Deputy Director for Operating Reactors.
Directorate of Licensing Office of Razulation i
U.S. Atomic Energy Cocnission
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Jashin2 ton, DC 20545
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Dear Mr. Gia busso:
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SU3 JECT: THREE MILE ISLA';D NUCLEAR STATION C;IT 2 DOCKET NUM3ER 50-320 FLUID 3 LOCK AND PETETF.\\ TION PREESURIZATION SYSTE" In the I'4I Unit 2 FSAR, Metropolitan Edison indicated that the fluid block and penetration pressurization systens had not been included in the final des 12n of this facility. Your letter of April 25, 1974 stated that if the applicant wished to pursue this course of action, additional infor.ation was required. This letter is submitted in order to provida that information.
A Fluid Block and Pressurized Penetration System (?3 & PPS) was incorporated in the Three vile Island Unit 1 design based ca early un-certainty and concerns _ about diffusion meteorology at the rite.
Now that four years of neteorological data measured at the site ara available
'ehich resolves the uncertainty, the Apolicant proposes to de.ete these systens from Three Mile Island Unit 2.
A eneck of cast records reveals that the following secuence of events occurred during the early planning stages. At the tire of conceptual fesign of Uni: 1 (early 1967), initial site studies indicated that the tiffusion meteevologv might be peor, based on an unusually high frequency
( f cal =s rom tne neares eeather statica at Cims tead Air Force 3ase, 13cated two miles north. A ccenarisen with records fren other contenpcrarj n telear sizes shcwed that Olmstead had a factor of 10 higher frequency of cala winds. This coccarisen is shown in Table 1 attached. Although the 01:s:ead data were highly suspect at the time, there was a significant uncertainty as to what the diffurdon meteorology would be.
The Applicant decidec to install the sys.ters en the basis that such a systen would provide the additional assurance that offsite doses, in the event o f an accident, eculc be much lower than indicated by the accident analyses.
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. In the licensinz crocess it became apparent that no offsite dose reduction would be allowed for the F3 s ??S system and that the AEC would require other reasures to reduce doses if required to meet Part 100 guidelines.
When it was decided to construct Unit 2, these systems were incorporated in the design of IMI-2 because they existed in IMI-1.
Since the conceptual design decision in 1967 to provide tne F3 5 PPS, ceteorological conditions have been monitored at the site and studied in detail. The four years of data available from the site show that the frequency of calms is less than about a percent? much less than 40 percent indicated by Olmstead Air Force Base data.
Tab le 1 presents a co=parison of Ol= stead data (used to =akt the original decision) with TMI reasured site data.
Additionally, since 1967 the AEC has been more def
'.tive on defining appropriate meteorological conditions for accident e'raiua tions,
i.e., 5 percent probable X/Q with cala speeds assured to be less than 1.0 rph.
The 1971-72 site data were accepted by the AEC at the operatinz license stage for TMI Unit 1 as the basis upon which accident doses would be calculated.
Since the ceteorology is not as unfavorable as originally contemplated, and since calculations show that the plant as designed will control accident doses to well within 10 CFR Part 100 dose guidelines, without taking credit for any reduction of leakage due to the fluid block and penetration pressurization systers, these syste=s are not necessarv to protect the health and safety of the public and therefore have been deleted from the desizn. Although it =ay be argued that these systems may have a beneficial effect in the unlikely event of an accident, the applicant does not believe that the small potential incre= ental benefit is co==ensurate with the cost of installing the systecs which exceeds 3900,000.
Very truly yours, R. C. Arnold
" ice President asb Attachment
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