ML19330A301
| ML19330A301 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 04/08/1980 |
| From: | Harold Denton Office of Nuclear Reactor Regulation |
| To: | |
| References | |
| TASK-IR, TASK-SE SECY-80-181, NUDOCS 8007170083 | |
| Download: ML19330A301 (3) | |
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k UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 Aoril 8, 1980 INFORMATION REPORT SECY-80-181 For:
The Commissioners k
Thru:
Executive Director for Operations From:
Harold R. Denton, Director Office of Nuclear Reactor Regulation
Subject:
TRITIUM CONCENTRATIONS IN GROUNDWATER MONITORING WELLS AROUND THE THREE MILE ISLAND UNIT 2 REACTOR CONTAINMENT BUILDING
Purpose:
To inform the Commission of measured tritium concentrations above background levels in the groundwater monitoring wells around the TMI-2 reactor containment building.
Discussion:
At the request of the NRC staff in July 1979, the licensee, Metro-politan Edison Company, agreed to install groundwater monitoring wells around the TMI-2 reactor containment building.
The purpose of the wells was to provide early detection of radioactivity in the groundwater adjacent to the TMI-2 reactor containment building due to the unlikely event of leakage of highly contaminated sump water from the building. The. licensee planned for the installation of eight monitoring wells at various locations around the TMI-2 re-actor containment and adjacent buildings. depicts the locations of these wells. The first wells (monitoring wells 4 and
- 7) were completed in late January of this year and groundwater samples were drawn for aaalysis of tritium concentrations. The remaining wells were completed in February and March and corres-ponding groundwater samples were drawn following well completion.
With the exception.of well MW-2 (2500 pCi/1), the concentrations were in the 100-600 pCi/l range. Although a firm background con-centration for tritium in the groundwater has not yet been estab-lished, the staff estimates that it is probably in the range of 200 pC1/1 to 300 pCi/1. Thus, the highest measured groundwater tritium concentration to date is approximately 8 to 12 times expected background levels.
It should be_noted that a tritium concentration of 2500 pCi/l is approximately 1000 times less than the maximum i
permissible concentration (MPC) of tritium in unrestricted area water (see 10 CFR Part 20, Appendix B, Table II, Column 2).
The location of the well (MW-2) indicating the highest tritium concentration is adjacent to the Unit 2 bcrated water storage tank (BWST). The staff has learned that the tank.has been a source of minor leakage (i.e., there has been no observable change in tank level) to the surrounding ground and that at least some of the water in the tank originated in Unit 1.
Thus, the Unit 2 SWST
Contact:
B. Snyder, NRR 492-7347 l
80 0 717 00g3
The Commissioners remains a likely, but unsubstantiated, source of groundwater contamination.
Additionally, the color (dark brown) of fluid pumped from wells MW-3 and MW-8 is inconsistent with that obtained from other wells on site. There is no apparent relationship between the color change and tritium concentration. While still unsubstantiated, the discoloration does not appear to be associated with biological contaminants.
Based on the preliminary results of the groundwater monitoring program, the staff has initiated.an intensive program to locate the source of the apparent radioactivity and further quantify the phy-sical characteristics, levels, and magnitude of the contamination.
The staff has outlined a list of action items to be initiated by the licensee no later then Monday, April 7.
The staff's formal request, including the list of action items, is contained in.
As additional information is obtained and evaluated, the staff will inform the Commission of its findings.
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Harold R. Denton, Director Office of Nuclear Reactor Regulation-
Enclosures:
1.
Plot plan of TMI-2 containment groundwater monitoring wells 2.
Memorandum.fm. B._Snyder to J. Collins dtd 4/3/80, action request to evaluate groundwater conditions at TMI DISTRIBUTION Commissioners i
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NUCLEAR REGULATORY COMMISSION T %' p g/. f
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April 3, 1980 MEMORAND'JM FOR:
John T. Collins, Deputy Program fianager TMI Program Office, NRR FRGM:
Bernard J. Snyder, Program Manager TMI Program Office, NRR SU3 JECT:
ACTIONS REQUESTED TO EVALUATE GROUND WATER CONDITIONS AT TMI As discussed last night and today with you, we have reviewed the currently available data obtained from the wells at the site.
As a result of the somewhat higher than expected readings of tritium in the ground water samples, I am requesting that you hEve Met Ed take, as a minimum, the actions as listed in the attachment.
It is requested that Met Ed be asked to proceed inmediately to get these actions underway with the actual work to start as -soon as possible, but no later than Monday morning, April 7.
Harold Denton has reviewed the requested actions and concurs in this apprcach.
i I understand that you will be issuing today a Pf! on this matter.
Bernard J. Snyder, Program,anager TMI Progi m Office Office of Nuclear Reactor Regulation
Enclosure:
As stated cc:
Harold R. Denton Richard H. Vollmer Joseph J. Fouchard l
dupe of 8905354 586 i
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REQUESTS FOR ACTION PLAN TO EVALUATE GROUNDWATER CONDITIONS AT TM!
1.
Take soil and groundwater samples from holes at-a minimum of 4 locations using an auger, and located as close to the reactor building as physically possible (closer than MW-2, MW-3, or MW-8).
In addition, take soil and groundwater samples in the vicinity of the leaking SWST and near the. auxiliary building.
Shelby tube samples should be used below groundwater level.
2.
Run tritium and isotopic gamma scans on all samples.
3.
Provide concentrations, activities, and history of concentrations of BWST' which is located near MW-2.
4.
Provide nuclide data from the sampling programs that were performed at MW-1 and at the monitoring well located near the interim solid waste storage area.
5.
Provide the results of recent sampling of Susquehanna River water with regard to tritium and gamma scans.
6.
Provide the containment water level history.
7.
Provide groundwater elevations from recent monitor well tests and from other available information.
8.
Provide recent tritium and gamma scan analyses of recent samples taken from MW-8.
9.
Provide detailed evaluations and conclusions regarding the source' of leakage, particularly the possibility of leakage from the containment and auxiliary buildings after the accident which may have resulted in nuclide migration away from the building.
Include the location of piping and possible pipe leaks in your analysis.
10.
Maintain ongoing records and analyses of the well ' onitoring program and m
related monitoring programs.
11.
Determine constituents of brown water samples from MW-3 and MW-8
.