ML20037B595
| ML20037B595 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 07/12/1976 |
| From: | Jun Lee Office of Nuclear Reactor Regulation |
| To: | Jay Collins Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8010220713 | |
| Download: ML20037B595 (4) | |
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JUL 121976
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Docket No.50-010
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John T. Collins, Chief, Effluent Treatment Systems Branch, DSE
="E THRU: Michael J. Bell, Leader, Systems Analysis Section ETSB ab1,-
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i TRIP REPORT - DRESDEN NUCLEAR STATION d
On Hay 25 and 26, 1976, I visited the Dresden Nuclear Station with 7,..:
R. Clark (EEB/ DOR) to 1) observe the Dresden Unit No. I corrosion test loop decontamination, 2) obtain data for source term development for
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future licensing actions involving major decontamination operations, i?=
- 3) obtain information to be used to develop a branch position to in-
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clude decontamination provisions during design and construction stages, j.M.,
and 4) observe the solidification process for decontamination chemical
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wastes.
5.e The corrosion test loop being decontaminated was originally owned by 9 y:@
the AEC and operated under contract by GE to obtain data on stress
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The test loop is completely separated from the reactor coolant system E=
by physically cutting the loop from the "B" Secondary Heat Exchanger 3,g Loop of the Dresden Unit No. I primary system. The loop consists of three S.S. test vessels (diameters from 18 to 24 inches), approximately 80 feet of 4 inch S.S. 304 and 316 piping, a new S.S. 316 Chem-Pump
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with Graphitar-14 bearings, a heat exchanger, and approximately 20 gate p
and globe valves. Bimetalic weld specimens and contaminated spool
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pieces obtained from Monticello, Quad Cities, Milletone and Dresden '
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Unit.No. 2 have been inserted in the loop. There ata no deadlegs in
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.jf the]1oop and the crud in the loop is believed to be ;t-opresentative F.
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of the rest of the Dresden Unit No. I primary system based on the iso-
.t'pic survey made by GE with a scanning GeLi detector. The background
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'Jdose' rates around the decontanination area ranged from 100 to 500 rJt/hr h
-"and one hot spot had dose rates of 20 R/hr at contact with the pipe
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-f,/ insulation.
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/ The loop tests were scheduled to begin with injection of the solvent \\
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on May 21, 1976, and the solvent was to be drained from the test b
loop on May 25,1976, after 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> of circulation through the 1
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test loop. However, due to Icaks developed through screw-connected E
l thermocouple penetrations in the pressure vessels, the licensee was l
not able to proceed with the solvent injection into the loop whilo
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we were at Dresden.
(Subsequent to our visit, a successful hydrotest
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. as finally completed on June 3, 1976 and the solvent was injected
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/ into the test loop on June 4,1976.)
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c.a The major itens of discussions with GE, Dow Chemical, and Commonwealth Gl. uu fu uu n.
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E J. T. Collins JUL 121976 g =r w. -...
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1.
The present buildup of radioactive crud in the Dresden Unit No.1
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primary system has reached the point where large man-rem exposures to operating personnel are resulting from in-service inspection and maintenance, ne licensee estimates an overall savings of 500 man-
[s -E EE rem per year in operation and maintenance personnel exposures for the projected remaining ten year operating life of Dresden Unit No.1.
El=.5 The cost of the overall full scale decontamination of the primary
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system is estimated to be 38 million dollars, including construction of a 25 million dollar decontamination waste process building and
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equipment.
(ERDA is expected to pay about 8 million dollars of this cost.)
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Based on an overall savings of 5,000 man-rem for a. period of ten years the decontamination cost is equivalent to $7,600 per man-rea
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saved ($2,600 per man-rem saved, if the cost of the waste process
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future waste processing operations). Estimated exposure required
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to perform the overall full scale decontamination is 250 man-rem.
2.
The activity build-up rate (shutdown radiation levels on primary coolant circulation piping) at Dresden Unit Nos. 2 and 3, Monticello, z..
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Millstone, Nine Mile Point, and Quad Cities have been following closely the Dresden Unit No. I build-up rate (effective full power hours of operation versus radiation level).
3.
For corrective action for future BWR design, GE (Jim Holloway)
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stated that they will require the maximum cobalt impurity content
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l be less than 0.05% in all stainless steel and higher nickel alloys l
and they will replace Stellite in control rod drive rollers with
- sii!l other suitable metal. These requirements are projected to increase p
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the cost of alloys by about 5%.
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4.
Two gamma proportional counters are provided in the test loop; one.at a clean spool piece which was indicating 500 cpm background, 5
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and the other at a contaminated pipe which was indicating 500,000 cpm.
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The equilibrated readouts from these two counters are intended to G
provide an instantaneous measure of decontamination effectiveness during chemical cleaning. ne utility expects a DP of approximately 1000,as a reasonably achievable value.
'besolventcontacttimeforthetestis100hoursat255Fand iiiii 0
5.
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' fat a pH of 3.5.
Dow installed a " copper catcher" in the loop to
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' scavenge any copper pickup from the test loop.
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Dow Chemical claims that they have developed a proprietary solidi-
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,fication reagent compatible with decontamination chemical vastos l
oenerated by their NS 1 d enntnninntinn en1vont.
The tee inap orrscE >
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J. T. Collins JUL 121976
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decontamination at Dresden Unit No.1 is expected to generate approximately 1000 gallons of chemical wastes and Dow will solidify
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1 chemical waste at Dresden with their skid-mounted solidification E= El equipment using this newly developed solidifying reagent. 'Ihe 7:j licensee will show that the system is capabic of producing a solid
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matrix in conformance with NRC Branch Technical Position, ETSB lio. 11-3.
Action Recomended 2 :=
1.
No should keep informed of current GE-Utility water chemistry
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programs, EPRI corrosion product control programs, and industry
.gg;.g3 decontamination process development.
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2.
We should encourage utilities and contractors to conduct feasibility z' l'[
studies of alternatives such as on-line system decontamination for
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operating reactors to deternine if this type of system could reduce
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liquid and solid waste volumes and occupational radiation exposures
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as compared to the system proposed for use at Dresden.
Original signed by:
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Jay Y. Lee, Senior Nuclear Engineer Effluent Treatment Systems Branch Divisioa of Site Safety and Environcental Analysis i.:......:
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E. ~ g:;.4 B. Rusche e
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S. IIanauer I:g.
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