ML20137W390

Forwards Response to 850729 Comments Re Seismic Design Criteria Analysis Transmitted in .Waste Storage Areas,Discussed in Section 3.1.2.10,located in Reactor Bldg, Auxiliary Bldg & Fuel Handling Bldg

ML20137W390
Person / Time
Site:	Three Mile Island
Issue date:	09/27/1985
From:	Standerfer F GENERAL PUBLIC UTILITIES CORP.
To:	Travers W Office of Nuclear Reactor Regulation
References
0321A, 321A, 4410-85-L-0188, 4410-85-L-188, NUDOCS 8510040299
Download: ML20137W390 (5)

Text

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d GPU Nuclear Corporation NggIg{ Post Office Box 480 Route 441 South Middletown, Pennsylvania 17057-0191 717 944 7621 TELEX 84 2386 Writer's Direct Dial Number:

(717) 948-8461 4410-85-L-0188 Document 10 0321A September 27, 1985 0 -,

U :l cn a Ej i.c R.m TMI Program Office U $$

Attn: Dr. W. D. Travers ,, OP M'

Deputy Program Director 3:

US Nuclear Regulatory Commission 3 c/o Three Mile Island Nuclear Station a ,',

Middlet. awn, PA 17057 o -

Dear Dr. Travers:

Three Mile Island Nuclear Station, Unit 2 (TMI-2)

Operating License No. DPR-73 Docket No. 50-320 Seismic Design Criteria Your letter dated July 29, 1985, forwarded comments concerning the GPU Nuclear Seismic Design Criteria Analysis which was transmitted by our letter dated April 16, 1985. The attachment restates each comment and provides a specific GPU Nuclear response.

Sincerely, d .

F. R. Standerfer Vice President / Director, TMI-2 FRS/RDW/eml Attachment cc: Program Director - TMI Program Office, Dr. B. J. Snyder 8510040299 850927 PDR ADOCK 05000320 oc9S v

l\

GPU Nuclear Corporation is a subsidiary of the General Public Utilities Corporation

- ATTACHMENT (4410-85-L-0188)

Section 3.1.1.3(1)

NRC Comment: The referenced samples were from the core debris bed in the upper portion of the core. Do you consider this sample to be limiting and/or to be representative of all the core zones?

GPU Nuclear Response: The sample analysis documented in Reference 31 of the Seismic SER demonstrates that less than 1.5% of the core debris particulate matter is less than 45 pm at the H8A sample location. Analyses of ten (10) additional samples indicate that less than 1% of the particles are less than 30 pm. These samples were taken from varying depths in the loose core debris bed at two horizontal locations (H8 and E9). A report is currently being prepared by EG&G which documents the results of these: additional sample.

analyses.

Though.the size distribution at a particular " zone" may

'~

vary, GPU Nuclear considers the percentage of small particulates, i.e., less than 45 pm, cited in the SER as a representative characterization of the_ loose rubble bed region. Additionally, the' lower reactor head region has been observed by video camera. Based on this e

observation, majority of the core material appears to be composed of relatively large pieces, i.e., golf ball size or larger.

NRC Comment: You indicate that only 1.5% of the material is less than ,

45 m. Since particles larger than 45 pm (perhaps up to 100 pm) can be pyrophoric, what percentage of the core region is in this particle size range?

1-2 GPU Nuclear Response: There are no sample results to date which explicity identify the particulate fraction in the size range "less i then 100 pm". However, inferences of this range can be gained from the samples referenced in the SER and the subsequent additional samples taken by EG&G.

The ten (10) samples analyzed by EG&G contained the following size ranges:

o less than 30 pm c 30 to 74 pm o 74 to 149 pm One sample analyzed consisted of 3.7% particulates in the 30 to 74 pm range and 3.5% in the 74 to 149 pm-range. These results were for the sample pulled from the lower hard stop probing limit of the debris bed. The remaining' samples have less than 2.0% total of particles of a size less then 149 pm and less than.1.5% total for all particles less than 74 pm.

' ATTACHMENT (4410-85-L-0188)

It is noteworthy that, other factors being equal, the larger the particle size, the less the chance for a pyrophoric reaction. Tests on the TMI-2 material (Reference 1) indicate no pyrophoric potential for any size range considered.

NRC Comment: Since portions of your detailed defueling strategy are not finalized, how will you assure that these activities will not ' generate significant additional quantitles of fines in the size range of concern?' Such activities may include plasma arc cutting, mechanical breaking of the suspected fused zone, and core boring.

GPU Nuclear Response: GPU Nuclear believes that defueling operations will not generate i significantly higher percentage of small parti cul a :e s . Our belief is based on the objective of defueling which is to remove large chunks of fuel and not to reduce the core to a size smaller than necessary for loading lito fuel canisters. The first step in this process is a mechanical breaking and chipping process.

Various cutting tools, e.g., plasma arc, abrasive water jets, may also used. These tools will clearly generate some particulate matter of varying sizes. However, the proportion of the fines generated from cut material, relative to the total mass of material cut, would be expected to remain small. Further, these fines will be regularly vacuumed or removed through the Defueling Hater Cleanup System, which would tend to limit the fine fraction in the core.

Additionally, the possibility of concentrated fines in one location was considered in various accident sequences analyzed in the Seismic Safety Evaluation. For example, in Table 3.1 of sequence 238, the Safety Evaluation analyzed the effects of a drop of a filter canister with its entire inventory assumed to be less than 10 pm.

' ATTACHMENT (4410-85-L-0188)

Section 3.1.2.10 NRC Comment: What is the basis for the maximum inventory in the waste storage area? Is this controlled in some manner, i.e.,

by orocedure?

GPU Nuclear Response: The waste storage areas discussed in Section 3.1.2.10 are located in the reactor building (RB), the auxiliary building and the fuel handling building (FHB).

The volume and isotopic inventory that was assumed for the reactor building is the same as has been used in previous submittals to the staff (Reference 2 and 3).

The original calculation (Reference 4) for storage trash assumed that the entire designated trash area was covered with contaminated trash in bags filled 3 feet high.

Furthermore, this trash area is bounded by physical barriers such as walls, elevator shaft, equipment, ropes and painted lines.

The larger inventory of the two RB storage areas, i.e.,

6000 lbs., was assumed to apply to both the 305' elevation and 347' elevation areas. The isotopic inventory assumed was deduced from the average dose, i.e.,-30 mR/hr, of a compacted radwaste drum and a parametric evaluation of TMI-2 radwaste for compliance with land disposal requirements. It is possible that a new type of compactible trash storage area, which will have a different isotopic distribution, will be defined for defueling operations. However, the consequences of a contaminated trash fire will remain bounded by other accident sequences analyzed in the Seismic Safety Analysis.

In the auxiliary building there is a waste. storage area in the Spent Fuel Cooler Room which consists of open shelving. Using the total volume of this shelving could result in IS00-lbs. of contaminated trash. Similarly, using the total volume of the open storage bins in the FHB storage area, 2560 lbs. of contaminated trash could be accumulated. These contaminated trash volumes were the basis for calculations performed in Reference 3.

Fifty-five gallon steel drums were also conservatively included in the vot to make up the total capacity assumed in the Safat) Analysis, (e.g., 22,000 lbs.).

These drums would typically be closed and isolated as a radionuclide source d" 'ng a fire. The radionuclide inventory was based on a typical radwaste trash inventory and assumed for conservatism, that a saturated HEPA filter bank was in the storage area and involved in the fire.

ATTACHMENT

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References (1) GEND-043, "TMI-2 Pyrophoricity Studies, "V. F. Baston, et.al., November, 1984.

(2) SER 15737-2-G07-107, " Removal of the Equipment Hatch," Revision 3, GPU Nuclear letter 4410-85-L-0006, F. R. Standerfer to Dr. B. J. Snyder dated January 18, 1985.

(3) Technical Specifications Change Request No. 49, GPU Nuclear letter 4410-85-L-0110, F. R. Standerfer to Dr. B. J. Snyder dated June 18, 1985.

(4) GPU Nuclear memorandum 9240-84-239, " Curie Controls of RB Radwaste Storage Area," H. K. Peterson to R. L. Rider, dated July 10, 1984.