ML20236Y307
| ML20236Y307 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 12/04/1987 |
| From: | Standerfer F GENERAL PUBLIC UTILITIES CORP. |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| 4410-87-L-0184, 4410-87-L-184, NUDOCS 8712110231 | |
| Download: ML20236Y307 (3) | |
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ATTACHMENT 4410-87-L-0184 l
NRC COMMENT 10 During the maximum credible accident (a major fire), will the filtration systems in the RB and AFHB handle the smoke produced by the fire? Please provide the basis for your answer.
GPU NUCLEAR RESPONSE The maximum credible accident (a major fire) defined by the PDMS Envirorrnental Evaluation assumed a fire in the vicinity of the blockwall which provided a driving force to exhaust contamination from the Reactor Building via a HEPA filter. This acc dent also bounds a fire accident for the Auxiliary and Fuel Handling Buildings during PDMS. For the purpose of determining loading on a HEPA filter due to smoke produced by a fire the following assumptions were made.
1.
Because of the lack of a credible combustion source in the vicinity of the blockwall, the maximum credible fire event for the TMI-2 Reactor Building was conservatively selected as ignition and combustion of the reservoirs from one reactor coolant pump (i.e., 138 gallons) which is remote from the blockwall. This combustion source was chosen because it represents the largest single source of combustible material in the Reactor Building. However, as this oil is contained within the Reactor Coolant Pump structure, ignition of this oil is considered to be highly unlikely.
2.
The fire provides the driving force for exhausting the smoke through the Reactor Building Passive Breather filtration.
3.
A combustion efficiency of 33% was assumed. This combustion efficiency was chosen for the maximum fire event in order to provide a conservative estimate of smoke loading on the HEPA filter.
4.
ERDA 76-21, Tat le 9-1, states for a 50 cfm filter which bounds the filtration ran for the iWactor Building Passive Breather System, 600 gm of carbon produces a pressure drop of 4 inches water gauge in HEPA filters.
Thus, the maximum quantity of combustion material allowed to 3
accumulate on the HEPA filter at a filtration rate of 50 ft / min was set at 600 gm of combustion residue (defined as carbon for calculational l
purposes).
5.
The fire (i.e., combustion) and subsequent smoke (i.e., carbon) was assumed to occur instantaneously and be uniformly distributed throughout the Reactor Building.
6.
NRC Letter dated December 30, 1986, J. F. Stolz to H. D. Hukill, states, "Although it is not possible to predict the nature and duration of a fire on any location, the staff expects that within one hour a fire would have been detected and controlled and near ambient conditions restored."
l Additionally, it is notworthy that the potential for a fire in TMI-2 is i
significantly reduced during PDMS.
8712110231 s71204 DR ADOCK 05000320 PDR
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ATTACHMENT 4410-87-L-0184 Thus, if the calculated time to achieve maximum filter loading (i.e., 600 grams carbon) is equal to or greater than one (1) hour, it can be reasonably postulated that the Reactor Building filtration system can handle the smoke produced from the maximum credible for accident.
Based on the above assumptions, GPU Nuclear calculated the time to load 600 grams of carbon on the HEPA filter as follows:
The postulated combustion volume of 138 gallons equates to approximately o
1036 lbm of oil or 2383 lbm wood equivalent based on BTU /lbm of material.
l o
At a filtration efficiency of 33%, the 2383 lbm wood equivalent results l
in a carbon content of 0.16 gm carbon per cubic foot Reactor Building atmosphere.
3 At a HEPA filter flow rate of 50 ft / min, the time to load 600 grams of o
carbon is:
t=
(600 gr C)
= 75 min or 1.25 hours2.893519e-4 days <br />0.00694 hours <br />4.133598e-5 weeks <br />9.5125e-6 months <br /> (50 ft3/ min)(0.16 gr c) ft3 Therefore, it can be reasonably postulated that the Reactor Building filtration system will handle the smoke produced by the maximum credible fire event as defined in the PDMS Environmental Evaluation.
It should also be noted that the location of this fire is remote from the blockwall and, therefore, would involve a smaller source term. Thus, the releases as a result of this fire would be smaller than that assumed in the PDMS Environmental Evaluation.
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GPU Nuclear Corporation J 9 Nuclear
- 'eress48o e
Middletown. Pennsylvania 17057-0191 717 944-7621 TELEX 84-2386 Wnter's Direct Dial Number:
(717) 948-8461 December 4, 1987 4410-87-L-0184/0277P l
US Nuclear Regulatory Commission I
Attn: Document Control Desk Washington, DC 20555
Dear Sirs:
Three Mile Island Nuclear Station, Unit 2 (TMI-2)
Operating License No. DPR-73 Docket No. 50-320 Post-Defueling Monitored Storage Environmental Evaluation Comment Responses i
NRC TMICPD Letter NRC/TMI-87-069, dated September 2, 1987, provided 18 additional NRC comments on the Environmental Evaluation for Post-Defueling Monitored Storage submitted by GPU Nuclear letter 4410-87-L-0025, dated March 11, 1987.
Attached is the response to NRC Comment 10. The responses to the remaining comments were previously submitted via GPU Nuclear letters 4410-87-L-0155, dated November 5, 1987; 4410-87-L-0170 dated November 25, 1987; and 4410-87-L-0179 dated December 4, 1987.
Sincerely,
,_ / i-l
/F. R. Standerfer l
Director, TMI-2 l
RDW/eml Attachment cc: Regional Administrator, Region 1 - W. T. Russell DLrector, TMI-2 Cleanup Project Directorate - Dr. W. D. Travers
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GPU Nuclear Corporation is a subsidiary of the General Public Utilities Corporation