ML19345B842
| ML19345B842 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 11/26/1980 |
| From: | Baskin K SOUTHERN CALIFORNIA EDISON CO. |
| To: | Crutchfield D Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8012020605 | |
| Download: ML19345B842 (5) | |
Text
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Southern California Edison Company l2
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November 26, 1980 Director, Office of Nuclear Reactor Regulation Attention:
D. M. Crutchfield, Chief Operating Reactors Branch No. 5 Division of Licensing i
U. S. Nuclear hgulatory Commission Washington, D. C.
20555
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Gentlemen:
Subject:
Docket No. 50-206 Steam Generator Repair c
San Onofre Nuclear Generating Station Unit 1 This letter provides information relating to the environmental impact of the current steam generator sleeving repair program at San Onofre Unit 1 which has been discussed with members of the Regulatory Staff during the post few days.
The information is contained in the enclosure to this letter.
If you have any questions concerning the enclosure, please contact me Subscribed on this 16' day of [ u am/ad
,1980.
h bedw~
By K.
P'. Baskin Manager of Nuclear Engineering, Safety, and Licensing Subscribed and sworn to before me on this AJ' day of hua d v
,1980.
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2-i AGNE A TREE I
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, wm s ;suc caurowa h Notary P ic in and for the County of 2,Qggja I,
Los Ang es, State of California 00j yy ressen bo_A327,1962 c m.- _ - - -- =
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801202060S f
ENCLOSURE, Infonnation Relating to Environmental Impact Steam Generator Sleeving Repairs San Onofre Unit 1 1.
Dose rates in steam generator channel head bowl and at tubesheet --
The dose rate in the center of the steam generator channel head bowl is estimated to be 1.5 R/Hr and the dose rate six inches from the bottom of the tubesheet is 2 R/Hr. The dose rate six inches from the bottom of the tube.5eet is the dose rate to the top of the head of workers which is limiting.
2.
Ma.1 r ALARA measures implemented during repair --
ALARA measures implemented include:
Use of a steam generator mock-up and actual tooling for training under protective clothing situations.
Remote CCTV monitoring of certain process instrumentation, plat-fom and channel head process areas.
Staging and final suit-up of steam generator entrants in low background areas prior to containment entry.
Decontamination of channel heads with a remote device.
Application of a lead curtain on steam generator divider plates.
Application of lead shielding to hot leg nozzle covers.
Design, fabrication and planned use of a sectioned tubesheet shield.
Extensive shielding of occupied areas, walkways and platfoms.
Use of a remote TV monitoring system dedicated for Health Physics use to provide coverage of platfonts and steam generator entries from a low background area.
Application of shielding to the cold leg manway opening.
Erection of " containment" tent enclosures to control contamination during process equipment maintenance.
Filtered exhaust of the opposite manway to control airborne concen-trations during channel head work.
Shift coverage for decontamination of walkway, railings and equipment.
4
. Environmental Impact Enclosure San Onofre Unit 1 Computerized dose assignment by work function and !ccation.
. - Maintenance is minimized on platform by use of an in-containment decon tent and a separate maintenance tent.
Daily exposure updates by work group and major task to upper level management.
Multiple step-off pads to closely confine contanination to the steam generator work areas.
Use of remote gamma detectors in steam generator platform areas.
Extensive use of long-reach survey instruments.
Routine air sampling, contamination and radiation surveys.
Process specific training for H. P. Technicians.
Use wherever practicable of remote or seni-remote tooling.
3.
Total number of workers --
The total number of workers expected to participate in the repair effort is estimated at 1,000.
4 Occupational radiation exposure estimate --
The total occupational radia. ion exposure to personnel is estimated at 1,783 man-rem. The basis for this estimate is as follows:
To date (3-month period) 379 man-rem Projection to complete tube cleaning 192 man-rem
- Projection to complete sleeving 1,212 man-rem **
Estimate based on cleaning 589 tubes in steam generator C at an exposure of 22 man-rem. Assuming no improvement, an extrapolation of this experience to complete tube cleaning in steam generators C and A results in an exposure of 96 man-rem and 66 man-rem, respectively. An additional 30 man-rem is expected to be incurred by project support personnel.
- Estimate based on:
(1) hands-on inethodology for sleeve insertion, hard roll of lower sleeve joint and some aspects of upper joint fabrication and (2) machine methodology for remaining aspects of upper joint fabrication and non-destruc-tive e'xamination, together with some contingency to account for equipment maintenance, repairs and/or replacement.
Hands-on methodology (20% contingency) 756 man-rem Machine methodology (40% contingency) 224 man-rem Non-destructive examination calibration 16 man-rem Equipment changes for upper joint fabrication 16 man-rem Project support 200 man-rem i
l l
E.,vironmental Impact Enclostre Sat, Onofre Unit 1 5.
Airborne releases, liquid releases and solid wastes --
The airborne and liquid releases and the solid waste generated during the repairs are estimated as follows:
Airborne Releases As anticipated, the steam generator repair has resulted in minimal airborne effluents. For comparison, station records indicate that during June,1980 2 x 10 5 Ci gross By was released. During October,1980, the only identi-fied effluent was Co-60. The total release was 2 x 10 6 C1. Future activities are expected to generate no significant changes. Assuming a five-month completion date, a total release of approximately 12 uCi could be estimated.
If October,1980 tritium airborne release (0.78 Ci) remains the same for a five-month duration, total effluent would be approximately 4 Cf.
Liquid Releases The steam generator repair has resulted in no measurable increase in liquid effluents. For comparison, in June,1980, a total of 2.29 x 10 2 Ci of Co-60 were released. October,1980 effluent records indicate 2.89 x 10 2 Ci of Co-60 were released and the total identified releases less tritium were 7.12 x 10 2 Ci. The October releases included treated process fluids as well as balance of plant input. No significant deviation from this trend is ancicipated. Upon completion of tube cleaning, steam generator repair input te liquid waste treatment systems will be minimal. The total volume of tube cleaning liquid is anticipated to be approximately 10,000 gallons. Based on a five-month completion date and liquid input remaining at the current rate, the estimated total liquid release is approximately.36 Ci. If tritium effluent remains the same as the October,1980 release (0.189 C1), the estimated total would be approximately 1 Cf.
Solid Waste Suninary Two 85 ft3 liners of solidified decontamination grit containing approxi-mately 3pCi/ml of gross sy activities - Total 15 Ci.
Compacted solid waste - with three steam generators in active repair, approximately 70 gallon containers are being generated per week.
Tni; production rate is as expected for a major maintenance activity.
Assuming the production rate will be constant, the content of each drum is 40 mC1, and project completion is five months, the resulting volume and content would be approximately 10,250 ft3 and 56 Ci respectively.
Twelve shielded casks containing ten spent decontamination filters and absorbent material. Assuming each filter contains approximately two pounds of spent grit and a measured grit concentration of 3 uCi/ml, the total volume and content is approximately 120 ft3 and 120 mci respectively.
Non-salvaged equipment utilized in tube cleaning resulting in a total of 300 ft3 and 10 Ci, if Co-60 is assumed' to be the isotope of interest.
Environmental Impact Enclosure San Onofre Unit 1 Approximately 10 to 15 filters utilized in the tube cleaning process 3 of space. Measurements indicate that each occupying approximately 5 ft volume and content may be 75 ft3 and 15 Ci total, if Co-60 is considered the isotope of interest.
6.
Steam generatar repair costs --
The estimated cost of the steam generator repair is $30 million. The estimated cost for replacement power (generated by oil-fired generation) is
$532,000 per day (average for 1980 and 1981).
7.
Steam generator repair completion date --
t The steam generator repair is expected to be completed during the first quarter of 1981, a more specific completion date can be provided in a few days, following detailed schedule reassessment which is now in progress.
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