ML19274E757
| ML19274E757 | |
| Person / Time | |
|---|---|
| Site: | Vermont Yankee  |
| Issue date: | 04/19/1979 |
| From: | Denise Edwards VERMONT YANKEE NUCLEAR POWER CORP. |
| To: | Ippolito T Office of Nuclear Reactor Regulation |
| References | |
| WVY79-43, NUDOCS 7904240348 | |
| Download: ML19274E757 (9) | |
Text
{{#Wiki_filter:e 5 ) V Min 1ONT Y A N K Ele N UCLMAR POWER COR PORNPION N^$ scvcnTv seven cROvc sTRccT B.3.2.1 RUTI. AND, VEIO10 NT 05701 HEPLYTO. ENGINEERING OFFICE TURNPIK c RO A D WcSTHORO. M ASS ACHUScTTS 01581 TELEPHONE 617 366 9011 WY 79-43 April 19, 1979 United States Nuclear Regulatory Commission k'ashington, DC 20555 Attention: Office of Nuclear Reactor Regulation Thomas A. Ippolito, Chief Operating Reactors Branch #3
References:
(a) License No. DPR-28 (Docket No. 50-271) (b) USNRC letter to VYNPC dated March 19, 1979, Request for Information on the Radiation Measured in the Vicinity of the Turbine Puilding
Dear Sir:
Subject:
Site Surveys Conducted in the Vicinity of the Turbine Building Enclosed for your information as requested in (Reference b), are copies of ion chamber surveys conducted in the vicinity of the turbine building and the site boundary of Vermont Yankee Nuclear Power Station. Surveys were performed prior to and after the installation of a concrete turbine shield. A description of the high pressure ion chamber and its perfomance specifications are also included. Should you have any questions regarding the information provided, please contact Carmine Pierno of our Radiological Engineering Group. Very truly yours, VERMONT YANKFE NUCLFAR P0FER CORPORATION
, :2V D. k'. Edwards Assistant to Vice President RHC/ sew Enclosure 00\
\
7904240$ Y g
HICH PRESSURE ION CHAMBER SURVEYS A high pressure ion chamber survey was perfonmed on October 27, 1975 at the Vermont Yankee Nuclear Pouer Power Plant. This survey was taken during full power operation and the results are listed in Table 1. At the time of the survey an average background reading of 8.0 p R/hr was used from previous surveys at 0% power and should be subtracted f rom the actual measured reading in Table 1 to determine the incremental exposure due to plant operation. Figure 1 shows the location of the survey sites with the incremental exposure rates. On December 10, 1975 another ion chamber survey was performed at Vermont Yankee. this survey covered the area within the inner security fence which was not covered in the October 25 survey (Figure 2). Table 2 shows the results of this survey during 100 percent power operation. Vermont Yankee installed a twenty-four inch concrete shield adjacent to the turbine on the west side of the plant to reduce turbine shine on the land side boundary fence in August 1976. Prior to plant startup, background gamma radiation measurements of 8.6 p R/hr were recorded with two MLI high pressure ionization chambers. The chambers were positioned on the western site boundary at a point on the fenceline documented (Location 6, Figure 1) as having the highest incremental exposure. Instrument readings were taken up to 95 percent of plant power levels, and an analysis of the data demonstrated a maximum increase above background of approximately 2.5 uR/hr. It was determined that the increment at 100 percent power would not exceed 2.9 pR/ hr. The turbine shield accounted for a 71 percent reduction in exposure for this location. The most recent ion chamber survey was performed in October 1977. The results of this survey are listed in Table 3. The background exposure rates were measured at each location (Figure 3) during refueling outages or other shutdovns, and the gross exposure rates were recorded at these locations. All gross exposure rates were recorded during 100 percent power level or normalized to the exposure rate expected at 100 percent gross electric output. The background exposure was subtracted from the gross exposure to determine the incremental exposure rates. All ion chamber surveys used the Measurements Laboratories Inc. (MLI) ionization chamber model 260/A environmental radiation monitor designed according to specifications in HASL-260. The MLI ionization chamber is filled with 25 atmospheres of argon. The chamber wall is made of 0.115 inch of stainless steel with a flat energy response to gamma radiation from 50 KcV to 5 McV. The system is linear up to 200 u R/hr with a sensitivity of 3x10-14 amps per pR/hr, and has an accuracy of 0.5 ER/lhr. To insure proper operation of the chamber, observation of the instrument's zero 1cvel and its response to a Cs-137 check source precede and f ollou cach exposure rate measurement . The accuracy of the ion chamber was verified by calibrating the chamber with a Ra-226 source which was certified ~ by the National Bureau of Standards.
. VERMONT YANKEE Table 1 VY Ion Chamber Survey of October 27, 1975 - 100% Power Prior to Turbine Shield Installation Exposure Survey Rate (MICRO-R/ hour)
Points Location (including background)
#1 On fence line, 170 feet north of bend in fence 14.5
#2 On fence line, 220 feet north of bend in fence 17.0
#3 On fence line, 270 feet north of bend in fence 19.0
#4 On fence line, 320 feet north of bend in fence 19.0 (30 feet south of future Ion Chamber location)
#5-380 On fence line, 30 feet north of future Ion 19.0 Chamber location
#6-430 On fence line, 80 feet north of future Ion 19.3 Chamber location
#7 On fence line, 130 f eet north of future Ion 18.5 Chamber location
#8 At future Ion Chamber location on fence line 18.5 and on center line of turbine
#9 On fence line, 180 f eet north of future Ion 17.5 Chamber location
#10 At inner fence, on turbine center line 144.0
#11 On turbine center line, 180 feet from inner fence 60.0
#12 50 feet north of location #11 60.0
#13 50 feet south of location #11 54.0
# 14 280 feet from inner fence, 100 f eet south of 35.0 turbine center line
#15 on turbine center line, 280 fece f ro, inner fence 36.0
#16 100 feet north of #15 35.0
#17 On turbine center line, 380 feet from inner fence 28.0
#18 On center line, 480 feet f rom inner fence 23.0
# 19 100 feet south of #18 25.0
#20 100 feet north of #18 23.0
#21 At flag pole at Vernon Elementary School 10.0
. Table 2 VERMONT YANKEE PRESSURIZED ION CHAMBER SURVEY December 10, 1975 Prior to Turbine Shield Installation Location Description Results (MICRO-R/hr)
(Including Background) No. 1 30 feet south of 40.1 northwest corner of turbine building 6 feet from building No. 2 30 f eet south of No. 1 73.0 next to turbine building No. 3 30 feet south of No. 2 86.5 No. 4 11.6 feet south of No. 3 194.1 No. 5 86 feet west of No. 4 116 No. 6 18.5 feet south of No. 5 145 No. 7 30 feet south of No. 6 160 No. 8 30 feet south of No. 7 165 No. 9 61 feet east of No. 8 218 (25 feet west of turbine building) No. 10 30 feet south of No. 8 142 No. 11 6 feet south of No. 10 138 (on turbine center line) No. 12 30 feet south of No. 11 85 No. 13 30 feet south of No. 9 132 No. 14 6 feet south of No. 13 116 on turbine center line No. 15 6 feet north of No. 13 145 No. 16 6 feet north of No. 15 160 No. 17 6 feet north of No. 16 172 No. 18 6 feet north of No. 17 189 No. 19 24 fcet east of No. 14 58 (next to building on turbine centerline)
Table 2 VERMONT YANKEE PRESSURIZED ION CHAMBER SURVEY (continued) Prior to Turbine Shield Installation Location Description Results (MICRO-R/hr) (Including Background) No. 20 6 feet west of No. 13 142 No. 21 30 feet west of No. 20 155 No. 22 30 feet north of No. 21 193.0 No. 23 60 feet west of No. 21 157.0 No. 24 30 feet south of No. 23 116 No. 25 30 feet north of No. 23 155 4
Table 3 VY Ion Chamber Survey - October 1977 Af ter Installation of Turbine Shield 100% power Background Average Average Increacntal Reading Reading Exposure Survey Sites (uR/hr) (u R/hr) (uR/hr)
- 1. On fence line, 245 yards from 11.2+0.4 8.6+0.4 2.6+0.6 outside center of turbine building
- 2. On fence line, 80 feet south of 11.310.4 8.4+0.5 2.9,+0.6 site 1
- 3. On fence line, 25 feet south of 11.4+0.5
, 8.410.5 3.0+0.7 site 1
- 4. On fence line, 270 feet south of 10.6+0.3 8.4+0.5 2.2+0.6 site 1
- 5. 204 yards from outside center of 12.9*+0.3 8.210.5 4.7+0.6 turbine building
- 6. 337 yards from outside center of 9.1+0.3 7.7+0.7 1.4+0.8 turbine building
- 7. South end of cornfield at south 9.010.3 7.7+0.7
, 1.310.8 fence
- 8. 385 yards from outside center of 9.0+0.2 8.5+0.4 0.510.4 turbine building
- 9. North-east classroom of Vernon 9.0+0.3 8.9+0.2 0.1+0.3 Elementary School
- 10. Outside of Vernon Elementary 7.8+0.4 7.5+0.3 0.3+0.5 School
- Plant operating at 96% power correct for 100% power level.
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