ML20247F933
| ML20247F933 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 03/27/1989 |
| From: | Roche M GENERAL PUBLIC UTILITIES CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 4410-89-L-0032, 4410-89-L-32, NUDOCS 8904040079 | |
| Download: ML20247F933 (3) | |
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GPU Nuclear Corporation 9 Nuclear
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Middletown, Pennsylvania 17057 0191 717 944-7621 TELEX 84 2386 Writer's Direct Dial Nurnber:
(717) 948-8461 March 27,1989 4410-89-L-0032/0456P US Nuclear Regulatory Commission 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 Additional Information on the Post-Defueling Monitored Storage Programmatic Environmental Impact Statement This letter is in response to your reauest, dated February 14, 1989, for additional information on Supplement 3 to the Programmatic Environmental Impact Statement dealing with Post-Defueling Monitored Storage.
Attached are GPU Nuclear's responses to your auestions.
Sincerely, h
M. B. Roche Director, TMI-2 EDS/ emf Attachment cc:
T. A. Moslak - Acting Senior Resident Inspector, TMI W. T. Russell - Regional Administrator, Region I J. F. Stolz - Director, Plant Directorate I-4 L. H. Thonus - Project Manager, TMI Site
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GPU Nuclear Corporation is a subsidiary of the General Public Utilities Corporation 1
ATTACHMENT 4410-89-L-0032 NRC QUESTION 1 What ouantity of tritium is expected to remain in the reactor building at the start of PDMS? Provide the basis for your response.
GPU NUCLEAR RESPONSE The cuantity of tritium in the Reactor Building (RB) is expectea to be about 1.9 curies at entry into PDMS. There are two sources of tritium in the RB:
the water in the RB sump and the water in the concrete of the RB basement walls and floor.
Prior to PDMS, the water in the RB basement and sump will be drained to the extent possible. It is anticipated that about 1 foot of water will remain in 3
the RB sump; the volume of sump water would be about 56 ft. The tritium activity in the RB basement water during 1988 has been determined to be about 0.066 uCi cm-3 Thus, the quantity of tritium in the RB sump water would be about 0.1 curies at entry into PDMS.
Tritiated water was absorbed into the RB basement walls and floor when the basement contained water to a depth of 8.5 ft. Since the initial basement water processing was completed by September 1981, it is expected that some of the tritiated water would have diffused out of the concrete and into the RB atmosphere.
The cuantity of tritium in the concrete is calculated from the tritium activity in the RB basement water in 1979 and the volume of water that diffused into the concrete. The activity level of the water in 1979, about 1.0 uCi cm-3, was decay-corrected to 1989. From numerous concrete core bores of the various concrete walls and the floor of the basement, it is known that radioactive material penetrated no more than 5 mm into the 3000 and 5000 psi compression strength concrete walls and floor, and completely through the block wall. The maximum ouantity of water absorbed into concrete is 0.21 g cm-3 (13 lbm ft-3) per ANSI / ASTM Standard C90-75. The Quantity of 6 and 5.8 x affected 3000 and 5000 psi, and block wall w ocrete is 9.6 x 10 3
106 cm-3 (340 and 204 ft ), respectively. Thus, the cuantity of tritium in the basement concrete at entry into PDMS in 1989 is estimated to be about 1.8 curies.
Therefore, the total tritium in the RB basement at entry into PDMS is estimated to be about 1.9 curies.
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ATTACHMENT
,i 4410-89-L-0032 i
NRC QUESTION 2 What fraction of the activation products in the reactor coolant system (including the reactor vessel and any internals expected to be present during PDMS) exist as particulate debris or corrosion films as opposed to activated metal? What fraction of this material could be considered smearable or easily removable? Provide the basis for your response.
GPU NUCLEAR RESPONSE The primary activation product
- identified at TMI-2 is cobalt 60 (Co-60). The amount of this activation product existing as particulate or corrosion films is a small fraction of the total activation products in the Reactor Coolant System (RCS). The activated metal of the Reactor Pressure Vessel (RPV) and RPV internals has been determined by measurements. The total Co-60 inventory of the RPV and int ^rnals, decay corrected to July 1988, ranges from 21,000 to 36,900 curies. The reactor core former is estimated to contain 94% of the activity.
For the remainder of the RCS, gamma spectrometry measurements have been performed on a section of the hot leg piping. The results of these measurements showed that the Co-60 activity was 0.76 uCi cm-2 The total 5 2 8 cm2 (3 x 10 ft ); most of surface area of the RCS is about 2.8 x 10 this area is in the Once Through Steam Generators (OTSGs). The total fixed (corrosion films) and removable (particulate debris) activity is about 212 curies. Therefore, the ratio of fixed and removable activity to total activated material is at most 0.01 (212 curies /21,200 curies).
Attempts to remove the Cc-60 activity were performed on RCS surfaces in the OTSGs; about 0.00007 uCi cm-2 Co-60 was removed. The activity fraction removed was about 0.0001 (0.00007 uCi cm-2/0.76 uCi cm-2).
This irdicates that the activation activity on the RCS surfaces is tightly adherent.
- Fission products were not considered since the Question addressed activation products.
NRC QUESTION 3 Page 13 of GPU's July 12, 1988 comment letter on the Draft PEIS Supplement 3 (Standerfer to Masnik) indicates that the cesium-137 to strontium-90 ratio for the 3000 psi concrete slab wall is approximately 2:1.
Data provided in an attachment to a February 2, 1988 memorandum (J. J. Byrne to W. D. Travers,
Subject:
PDMS Environmental Evaluation Information), indicates that the ratio for the painted 3000 psi wall is closer to 20:1 and for the unpainted wall 23:1. What is the appropriate cesium-137 to strontium-90 ratio in the 3000 psi concrete slab walls?
GPU NUCLEAR RESPONSE i
The 2:1 ratio of cesium-137 to strontium-90 was an early conservative estimate based on radiation dose analyses.
Subseauent analysis of actual core samples indicate that the appropriate cesium-137 to strontium-90 ratio in the 3000 psi concrete slab walls is 23:1.
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