ML20203L895
| ML20203L895 | |
| Person / Time | |
|---|---|
| Site: | McGuire, Mcguire  |
| Issue date: | 08/25/1986 |
| From: | Tucker H DUKE POWER CO. |
| To: | Harold Denton, Youngblood B Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8609020035 | |
| Download: ML20203L895 (8) | |
Text
.
o DUKE POWER CsOMPANY P.O. ItoX 03180 CHAMLOTTE, N.O. 28942 IIAL 15. TUCKER TEL8 m e s (704) orneo,
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August 25, 1986 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C.
20555 A?tENTION:
Mr. B.J. Youngblood, Director PWR Project Directorate No. 4
Subject:
McGuire Nuclear Station Docket Nos. 50-369 and 50-370 Radiological Aspects of RTD Bypass Removal
Dear Mr. Denton:
4 By letter of October 29, 1985 Duke Power Company submitted proposed changes to i
l McGuire's Technical Specifications in support of a planned modification to remove the RTD Bypass System. On January 21, 1986, the NRC Staff requested additional I
information regarding the radiological aspecte of the modification.
Attached are DPC's responses to the six questions raised in the Staff's letter.
Please notify us if you require additional information for your review.
Very truly yours,
/ *p ip v Hal B. Tucker SAC /27/jgm Attachments i
0 f1 o ' \\
0609020035 060025 PDR ADOCK 05000369 p
Harold R. Denton Augur;t 25, 1986 Page.'
xc Dr. J. Nelson Grace, Regional Administrator U.S. Nuclear Regulatory Commission - Region II 101 Marietta Street, Suite 2900 Atlanta, Georgia 30323 Mr. W.T. Orders Senior Resident Inspector McGuire Nuclear Station Mr. Dayne Brown, Chief Radiation Protection Branch Division of Facility Services Department of Human Resources P.O. Box 12200 Raleigh, N.C.
27605 e
Response to NRC Request for Additional Information
_ Radiological Aspects of RTD Bypass Modification 1.
Question:
Describe the actual hardware changes and activities that will be made to accomplish RTD bypass piping removal.
Include those construction steps which result in radiological exposure to personnel or generate radioactive waste.
Identify differences, if any, in these changes and activities for the two McGuire units.
Response
A summary of the RTD modification including hardware changes and construc-tion activities follow. Please note that there is no significant difference between the work at each unit. Also, note that the work steps are not nec-essarily in order.
1.
Work will begin with the erection of scaffolding, temporary shielding, and the set up of temporary lighting and service lines.
2.
The RID bypass legs will be cut at the three tot leg RTD scoops on each loop.
3.
The hot leg penetrations at each hot leg scoop will be machined and threaded.
4.
A hole will be drilled in the bottom of each hot leg scoop.
5.
An RTD well and narrow-range fast-response RTD will be installed in i
each hot 'eg scoop.
6.
The retarn crossover legs will be cut and capped.
7.
The cold leg RTD bypass loop piping will be cut at the cold leg nozzle, 8.
Two RTD wells and narrow-range, fast-response RTD's will be installed in each cold leg.
One will be ins',alled in the remaining part of the line to the RTD bypass manifold that is to be severed; the other RTD
will be installed in a new nozzle to be welded onto the cold leg.
9.
New cables will be pulled and connected to the replacement RTD's.
- 10. The piping, valves, and support / restraints associated with the RTD bypass loop will be removed from containment.
- 11. A general clean-up of the affected areas including the removal of temporary scaffolding, etc. will be the last stop in the modification.
2.
Question:
Provide an estimate of the occupational radiation dose determined for the overall RTD Bypass Modification at McGuire 1 & 2.
This should include the following:
a) Doses and manpower for major subtasks b) Typical doserates expected c) Maximum doserates expected and locations
Response
a) The estimated occupational radiation exposure for each RTD bypass modi-fication is shown below.
The estimate is based on anticipated staytimes for each major subtask and actual area doserate measurements. Appro-priate adjustments have been made to account for shielding effective-ness, and other exposure reduction techniques.
SUBTASK
!!AN-ilollRS DOSE EST!!! ATE (Person-Rem)
- 1) Preparation for RTD liypass 33 1.090 flodi fica t ion
- 2) Shieldir.g Inntallation/Rer,toval 64 9.600
- 3) Remove / Replace pipes, hangers, manifolds, 417 11.100 electrical interferences
r
- 4) Modify RTD 120 12.000 Total per loop 634 33.790 Total per unit (4 loops) 2536 135.160 NOTE:
Man-hour estimates are actual in-area estimates supplied by craft supervisors.
b) Typical general area doserates are anticipated to range from 20-100 mr/hr with an average doserate of 50 mr/hr.
c) Maximum doserates should range from 1-3 R/hr on contact and 200-400 mR/hr general area at NC valves and RTD manifolds.
3.
Question:
Provide a comparison of dose incurred during task performance and dose avoided (e.g. reduced operations, maintenance, ISI for system components, seismic restraints / snubbers) over plant life by removal of the RID bypass piping system.
Response
Upon removal of the RTD bypass piping system a significant amount of dose associatori with valve and manifold maintenance,ISI, and snubber inspection will be eliminated.
As a result, over the life of the plant,1250 person-rem will be avoided for each unit.
Therefore, a not exposure savings of 1114.8 person-rom is anticipated.
r 4.
Question:
Identify measures to be taken to assure that doses to workers during task performance will be ALARA.
This should cover, for example, task planning, special training, use of mockups, area and system decontamination and air-borne radioactivity, efforts to minimize numbers of workers, and applica-tion of experience from similar efforts in the industry.
Response
ALARA preplanning will be utilized to identify potential exposure concerns during PTD bypass modification and effect solutions.
Visual inspections and area photographs will assure. proper tools and equipment are available for each subtask and worker knowledge of the area.
Temporary shielding will be utilized whenever and wherever practical.
The use of special tooling will also be evaluated and utilized when appropriate.
Job observations and constant communication between job supervisors. H. P.
technicians and ALARA personnel will be used to identify additional exposure reduction methods.
These techniques will ensure worker doses are maintained ALARA.
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5.
Question:
Identify the types and volumes of radioactive waste which are expected
~
to be generated (e.g.,
piping, components, insulation) and discuss disposal plans for these wastes.
Response
The types and volumes of radioactive waste expected are summarized below:
a) RTD Loop Material 3
Description Quantity Volume (ft )
Manifold 8
11.2 Valves 49 30' 3" Dia. Pipe 168 ft.
14.3 2" Dia. Pipe 100 ft.
3.9 Insulation
3" Pipe 168 ft.
83.4 2" Pipe 100 ft.
42.0 TOTAL 184.8 per unit Radiation and Contamination
.2 R/hr to 2.0 R/hr contact 30 nr/hr to 2.55 R/hr smearable b) Hanger Materials 3
Description Quantity Volume (ft )
Hangers 90 56 per unit Contamination Levels If reasonable measures are taken to minimize cross contamination, hangermaterialsurfg'cescanprobablybedecontaminatedtoless than 1000 dpm/100 cm Total Curie Content (est.) = 4.2 per unit Currently, Duke 1e considering four options for disposal of the RTD waste.
These are:
- 1) Burial at Barnwell as low-level waste.
2 On-site decontamination by Duke, sell as scrap.
3 On-site decontamination by vendor, sell as scrap.
4 Off-site decontamination by vendor.
)
I 5.
Question l
Identify anc t;riefly discuss, any special radiological problems which may be associated with this task (e.g., very high doserates, very high contamination levels, high radiciodine levels, need for multiple dosimetry).
I
Response
1 The following special problems, and resolutions, have been identified l
through ongoing pre-job planning.
a) Standard portaband saws, used to cut NC piping, show excessive blade wear after 2 cuts. Continued use will result in excessive exposure of workers.
Carbide tip blades are being sought for portaband saws.
1 j
Otherwise, standby saws will be available.
i b) Manual removal and reconfiguration of RTD Scoop welds was going to result in excessive personnel exposures.
Remote tooling was developed to perform the task and thus, reduce exposures to an acceptable level.
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