ML20197J417
| ML20197J417 | |
| Person / Time | |
|---|---|
| Site: | 07000903 |
| Issue date: | 12/18/1985 |
| From: | Kinneman J, Stearns C NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | |
| Shared Package | |
| ML20197J402 | List: |
| References | |
| 70-0903-85-02, 70-903-85-2, NUDOCS 8605200035 | |
| Download: ML20197J417 (5) | |
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a U.S. NUCLEAR REGULATORY' COMMISSION Region I Report No.
70-903/85-02 L
70 903 Docket No.
i License No.
SNM-871 (Terminated)
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s Licensee:
Gulf United Nuclear Corporation Pawling, New York i, \\
Present Owner:
National Park Service Facility Name:
Former Waste Storage Building; Inspection At:
Same Inspection Conducted:
October 15, 1985 2,
Mw itl86lBf
~ Inspector:
5 C. F. Stearns, Radiation Specialist date e
Approved By:
jw
/2/8Pfar
. O. Kinneman, Chief, Nuclear Materials
'd a t'e ection A Inspection Summary:
Inspection on October 15, 1985 (Inspection No. 70-903/85-02)
Areas Inspected:
The inspection was limited to a survey of the former Waste Storage Building.
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Results:
Radiation levels exceeding 2 mrem /hr were found at several locations, primarily in the vicinity of a hole made in the concrete floor to remove activity found in recent surveys, t
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C Enci (1)
DETAILS 1.
Persons Contacted Ms. Sibyll M. Gilbert, Member, Conservation Advisory Board, Town of Pawling Mr. Kenneth Lutters, Office of Parks and Recreation, Taconic Region 2.
' Background This facility had been released for unrestricted use more than ten years ago.
The current inspection was conducted to review a radiation level of 5 millirem per hour in the Waste Storage Building reported by a member of the Conservation Advisory Board, Town of Pawling in a letter dated September 30, 1985.
3.
Instrumentation Used in Survey Radiation level measurements were made at all locations using a Ludlum Model 14C, Serial #17304, with a thin end window GM probe sensitive to beta and gamma radiation, caliorated July 9, 1985. Confirmatory measure-ments were also made using a Keithley Model 361000, Serial #9882 ionization chamber instrument at all points where levels exceeding 2 millirem per hour were found with the Ludlum GM.
4.
Survey Technique The floor of the former Waste Storage Building was surveyed for beta gamma radiation levels using the thin end window of the Ludlum GM probe. At locations where levels exceeding 2 millirem per hour were found, a reading was also taken at 3 feet above the floor, and gamma readings were taken at the surface using the cylindrical wall of the GM probe as a shield. As noted above, confirmatory readings, using the Keithley ionization chamber instrument, were also made at these locations.
5.
Results Almost all surface readings exceeding 2 millirem per hour were found within a few inches of the hole resulting from the removal of a portion of the concrete floor where radioactivity had been detected by recent surveys.
See Exhibit B for photographs of this hole.
In photograph #1, for example, the brown area, farthest from the wall in the background, is the portion of hole where all the concrete was removed down to loose dirt, whereas the rear portion of the hole is more shallow, since some concrete remains.
The photographs in Exhibit 8 also show that the hole is within a light colored square area.
This approximately 4 foot by 4 foot section had been painted to delineate where contamination was found in an earlier survey.
All readings beyond this painted area were found to be less than 0.05 mrem per hour in the current survey, except for three spots shown in Exhibit A.
i d
3 The maximum level found on the surface of the floor, measured by the Ludlum Model 14C GM, was 5.6 mrem / hour (0.4 mrem / hour when shielded by cylindrical wall of GM probe). The reading at 3 feet above the floor was 0.1 mrem / hour.
The beta-gamma reading at the surface using the Keithley ion chamber instru-ment was 4.4 mrem / hour.
A reading of 14 mrem / hour was obtained near the north wall of the building, approximately three feet from the hole, but this was apparently a tiny spot of activity in the loose debris on the floor, rather than on the floor itself.
This assumption that the spot is small is based on the precision found to be required in positioning the GM probe in order to reproduce the reading.
The inspector demonstrated that the activity was in loose debris, rather than on the surface of the floor itself, by pushing the debris slightly towards the wall, and noting that the position where the 14 mrem / hour reading was thence obtained shifted accordingly.
The gamma reading at the surface was 0.2 mrem / hour and the reading at three feet was 0.06 mrem / hour.
Readings of 1 mrem / hour or more were found at several other locations.
(See Exhibit A for the locations of these readings relative to the hole in the concrete floor).
In general, at all points where levels exceeding 2 mrem / hour were found, readings were taken with shield as well as open window on the surface of the floor, and also at 3 feet above the floor.
Readings at these points with the Keithley ionization chamber instrument were always appreciably lower than the GM readings, possibly due to the.
poor geometry of reading rather small spots of activity with an instrument having a relatively large ion chamber. However,.the Keithley readings were generally comparable to the GM readings with the exception of the 1.4 mrem / hour reading which was only 10 percent of the 14 mrem / hour GM reading at that spot.
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