ML19340D053
| ML19340D053 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 12/15/1980 |
| From: | Hovey G METROPOLITAN EDISON CO. |
| To: | Barrett L Office of Nuclear Reactor Regulation |
| References | |
| TLL-657, NUDOCS 8012190518 | |
| Download: ML19340D053 (7) | |
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Metronoliun Edison Company 4-r )
Post Of f,ce Box 480 Il { '
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F Middletown, Pennsylvania 17057 717 944-4041 Wnter's Direct D al Numner December 15, 1980 TLL 657 5
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TMI Pr oe. rn O f fic e Attn:
Mr. Lake Barrett, Deputy Director U.S. Nuc lear Regulatory Cmamission G
c/o Three Mile Island Nuclear Station
[]
Middletown, Pennsylvania 17057
Dear Sir:
Three Mile Island Nuclear Station, Unit 2 (TMI-2)
Operation License No. DPR-73 Docket No. 50-320 Cork Seal Contamination Report The purpose of this letter is to provide a description of tne cork seal con-tamination, to report the action taken to date, and to report our plans for
. future act ions to mitigate the ef fects of the contamination.
-7v Cork seal contamination was first discovered on November 26, 1980 during a routine radiation survey in the Control / Service Building area.
Following this discovery the onsite NRC staf f was informed of the problem. As a result'of these surveys, it was discovered that the cork construction seam between the Air Intake Tunnel and the Service Building was contaminated. The cork is used as a j aint filler between the various construction joints in the concrete.
An investigation was initiated to determine if radioactive contamination was migrating along these seams, to determine the point of origin of this cent amin-l ation and to determine the corrective action required to contain and isolate this contamination.
The investigation resulted in the following actions being taken.
Surface samples and depth samples of the cork were taken along the seams in the Auxi-l liary Building, Control Building and Service 9F sf1rg and analyzed for radio-act ive isotopes.
The construction and structural drawings were checked to determine possible sources of contamination. Radioactive waste disposal pro-cedures were checked to ensure against unauthorized dumping of contaminated l
liquids; groundwater monitoring wells were sampled; and samples of standing l
water in various part s of the Unit were taken and analyzed.
1 To date, the results of the investigation have yielded the fo llowing :
1 00 o migo 5/T f
q Metropohtan Edison Comoany is a Member of the General Pubhc Utities System
I Lake Barrett 1.
Water stops (barriers) are located across joints which are ia contact with the ground.
(See attached sketch) These stops consist of a hard rubber material imbedded into the concrete which form barriers to prevent groundwater from seeping into the building. They are specially shaped to provide a tortuous path for the water to travel and thus can inhibit waterborne cont amination from migt ating to the outside environment.
In addition, plastic membranes are located at the bottom of the building mats and along the walls to provide an additional water barrier.
2.
A total of 64 cork samples have been nalyzed, the results of which are presented in Table 1.
Conclusions dr2wn from these analyses are as follows :
'I a.
Cesium concentration is highest along the east-west building seam.
(See attached drawing for location) b.
The contamination is highest near the corner of the seal injection valve room and decreases with distance.
c.
The radioactive contamination is uniformly distributed over depth l
except that the samples taken near the corner of the seal injection valve room, showed a trend for cesium specific activity to increase with depth.
The cause of this relatively even distribution may be due to cesium being readily soluble and there fore easily transported by wa te r.
4 d.
At depths greater than two feet, the cork is water saturated to t'.ie point of deterioration.
~
3.
The environmental groundwater monitoring wells have shown no increase in activity due to seepage from the cork seals.
4.
Floor drains were checked and disposal procedures were verified to ensure that radioactive contaminants were not being routed to areas that would have a potential path to the environment.
l The origin of the contamination has not been determined by the samples analyzed l
thus far but a likely source appears to be leakage from the auxiliary building into the east-west seam approximately 3 feet from the reactor building peripheral This seam is adjacent to areas flooded during the accident and walls seam.
which received a gross washdown during decontamination of the auxiliary building.
l Samples of cork have been sent to an in' dependent laboratory to chemically separate the cesium and perform detailed analyses in order to study less soluble isotopes.
In addition, samples of the water which is underneath the cork will f
be taken and analyzed. To determine if the water stops are functional, core samples of cork in the Air Intake Tunnel and the Fuel Handling Building / Reactor i
Building interface will be taken.
Several methods to isolate and contain the cork contamination are being studied.
These include cork excavation, desiccant drying agents and the use of sealants and strippable coatings.
l i
I
Lake Barrett The solution of ti.is problem depends upon determinatien of the cause and ext ent of contamination.
We anticipate that our prograu described above will enable us to develop corrective actions and we should be able to provide a follow up report on January 16, 1981 describing our program for resolving this problem.
Sinc erely,
K g
. K. Hovey Vic e-Pres id ent and Director, TM1-2 GKH: RPW: 1h cc:
Bernard J. Snyder
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TABLE 1 1
SAMPLE ANALYSES RESULTS Total Concentration ( u Ci) i POINT DEPTH C -134 C,-137 s
1 Surface 1.5 E+1 1.0 E+2 l
2 Surface 1.5 E-0 1.0 E+1 3*
Surface 4.0 E-3 2.9 E-2 4
Surface 6.7 E-3 5.4 E-2 5
Surface 7.0 E-3 4.3 E-2 6
Surface 1.4 E-3 8.7 E-3 7
Surface 3.0 E-4 2.5 E-4 i
8 Sur f ace 3.0 E-4 2.5 E-4 I
9 Surface
- 5. 2 E-2 3.7 E-1 i
10 Surface 2.9 E-1 1.9 E-0 EW-1 6"**
8.9 E-2 6.1 E-1 12" 4.6 E-0 3.2 E+1 18 4.8 E-1 3.3 E-0 g
24 5.2 E-1 3.5 E-0 30 8.0 E-1 5.4 E-0 36 1.2 E-0 7.9 E-0 EW-2 6
5.7 E-3 4.0 E-2 f
12 2.2 E-1 1.5 E-0 t
18 5.8 E-1 4.0 E-0 24 2.1 E-0 1.5 E+1 30 1.6 E-0 1.1 E+1 36 4.6 E-0 3.1 E+1 EW-3 6
Results not available i
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TABLE 1 (Cont inued)
Total Concentration ( pCi)
POINT CEPTH C -134 C,-137 s
EW-3 24 Results not available 30 36 NS-1 6
1.0 E-3 7.1 E-3 12 3.2 E-3 2.1 E-2 18 6.1 E-3
- 4. 2 E-2 24 9.6 E-3 7.1 E-2 30 9.0 E-3 6.5 E-2
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36 1.5 E-2 1.0 E-1 NS-2 6
5.9 E-5 5.1 E-4 12 1.3 E-4 7.4 E-4 18 1.6 E-4 1.4 E-3 24 1.9 E-4 1.3 E-3 30 6.6 E-3 5.0 E-2 y
36 1.7 E-2 1.2 E-1 NS-3 6
1.1 E-4 12 2.7 E-4 18 3.8 E-4 24 3.4 E-4 30 3.5 E-4 36 No isotopes detected NS-4 6
No isotopes detected 12 No isotopes detected 18 No isotopes detected 7.9 F-5 24
TABLE l_ (Cont inued)
Total Concentration ( u Ci)
POINT DEPTH C -134 C -137 s
s NS-4 30 No isotopes detected 36 No isotopes detected P-1 6
6.1 E-2 4.4 E-1 12 2.4 E-2 1.7 E-1 18 9.7 E-2 6.9 E-1 24 6.3 E-2 4.6 E-1 30 1.6 E-1 1.2 E-0 36 3.7 E-2 3.9 E-1 P-2 6
5.3 E-3 3.5 E-2 12 3.6 E-3 2.8 E-2 18 3.2 E-3 2.2 E-2 24 4.8 E-3 3.2 E-2 30
- 9. 2 E-4 5.6 E-3 36 1.4 E-3 1.0 E-2 r
P-3 6
3.3 E-4 4.3 E-4 12 4.2 E-4 18 24 3.2 E-4 30 4.5 E-4 2.9 E-4 36 Ce-144 -
2.3 E-4
- 3.5 E-4
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