ML19254E182
| ML19254E182 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 10/19/1979 |
| From: | Hendrie J NRC COMMISSION (OCM) |
| To: | Deutch J ENERGY, DEPT. OF |
| References | |
| NUDOCS 7910310250 | |
| Download: ML19254E182 (5) | |
Text
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UNITED STATES C OMC
,,y 'Q 3 g NUCLEAR REGULATORY COMMISSION CD AR E
WASHINGTON, D. C. 20555
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October 19, 1979 CHAIRMAN The Honorable John M. Deutch Under Secretary U. S. Department of Energy Washington, D. C.
20545
Dear Mr. Deutch:
I am writing you concerning the need for developing and implementing a plan for the post-accident examination of the Three Mile Island Unit-2 (TMI-2) power station.
The accident was a highly regrettable occurrence, but the infomation that can be derived from a careful examination of the facility before and during cleanup can be invaluable in providing both understanding of the accident and reactor safety information.
Several discussions have been held on this subject. At a meeting of senior staff representatives of DOE, EPRI, GPU and NRC, it was concluded that it would be useful to develop a coordinated program under the aegis of a joint Coordinatino Committee.
I support this approach and reconmeN that DOE give strong consideration to the allocation of funds and other i escurces for this effort.
Some areas in which such information can be obtained are:
(a) fission product behavior, transport, and plateout; (b) the extent and location of core damage from thermal and chemical degradation; (c) other primary system structural damage, if any; and (d) damage and deterioration of equipment in the containment.
Such information is not only valuable to the mission of the NRC and DOE, but will be equally valuable to the international community. The enclosure hereto contains a more detailed preliminary listing of data needs.
7 910310 z. So 1247 348
The Honorable John M. Deutch In essence, TMI-2 can provide a large amount of information which might not be available from limited scale experiments or simulations.
It is important that these data not be lost in the recovery of the facility. Your attention to this matter is appreciated.
If you have any questions in this regard, please do not hesitate to contact me or Dr. Charles N. Kelber of our Division of P.eactor Safety Research,
(
incerely,i i t s
oseph M. Hendrie
Enclosure:
As stated 1247 349 e
S ifety Related Examinations During TMI Recovery Operations The TMI 2 plant, in its present accident aftermath state, contains a wealth of infortration of potentially great value to the NRC for understanding the nature of accident initiated effects on plant, equipment, and fluids. To guide future activities in preventing and mitigating the effects of accidents ar,d to identify sources of potential decontamination and requalification difficulties it is of great importance that careful attention be given during recovery operations to obtaining data which could otherwise be forever lest without adequate planning and control.
An early objective should be to determine and compare the values of alternative data needs and to establish their relative priorities prior to the various recovery operation steps during which they would take place.
A preliminary listing of desired information examples by category is given as follows for early planning purposes (taken from a more extensive lt coopiled from all sources within NRC staff):
Listing of Data Interests for TMI Recovery Examinations General Guidelines 1.
The recovery plan should be integrated with safety related examinations to minimize the loss of valuable information. A management mechanism has been suggested to assure proper coordination.
2.
Provision should be made for careful recording and filing of photographs, TV tc.nes, voice records, etc., made during the recovery process.
3.
Provision should be made for library samples for possible future tests.
Examoles of Specific Examinations, A.
Cor.tainment Bui' ding Interior Prior to Start of Decontamination 1.
The disposition of radionuclides on walls and operating floors, and adsorption on concrete, should be sampled by swipes, trepanning or similar techniques.
2.
Examination for damage associated with hydrogen burn.
3.
All glass light bulbs and glass covers should be collected, identified for specific location and saved for eventual analysis. These items could provide an excellent indication of integrated dose to various parts of the containment since it is known that the amount of darkening (or change in optical density) is related to dose.
4.
Check operating floor areas for any evidence that the containment spray was limited in lateral extent.
5.
Assess debris in sum to determine type, size, and initial and final location if (and how) clogging took place.
1247 350
' B.
Tests after Decontamination of Containment Building 1.
Perform a detailed examination of safety grade electrical equipment including cables, instruments, and motors.
2.
Check conditior of thermal insulation.
3.
Check conditior. of valves, blowdown lines, valve packing and gaskets.
4.
Determine extent ef external corrosion on reactor pressure vessel (including head), steam generators, pressurizer, piping and carbon steel valves inside containment.
5.
Identify radionuclides and their location within the damaged steam generator.
6.
Perform containment leak rate test to ascertain containment integrity subsequent to hydrogen explosion and intense radiation exposure.
C.
Core and Reactor Vessel 1.
Reactor Vessel, CRDM's, etc. (External) a.
extent and location of sites of contamination; characterization of radionue des present, b.
examination for signs of overheating, thermal distortions.
2.
Reactor Vessel, CRDM's, Instruments (Internal) a.
melting, distortion, fission product entrapnent, etc., effects on control systems, thermal shields, upper and lower core support s tructures,
b.
examination of vessel interior for damage and for signs of various accident conditions.
3.
A visual examination of the cc e geometry with appropriate photographs; precise axial and radial locations of abnormalities.
4.
Determination of extent of gross assembly-to-assembly core damage /
distortion; estimation of flow blockages or other hydraulic phenanena, and distribution of thermal effects.
5.
Detennine distribution of (fuel and clad) debris and formation and composition o' debris deposits and debris beds.
6.
Assessment of the conditions of core instrumentation prior to renoval.
7.
Removal and inspection of fuel bundles to determine if ruptured or melted.
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, 8.
Poolside examination of any intact fuel bundles for degree of ballooning and flow restriction.
4 Removal and examinations of portions of guide tabes, control rods, instrumentation tubes, and upper and lower core structural components.
10.
Removal of small samples from selected regions of the core.
11.
Hot cell examination vf samples for:
an estimate of the maximum clad and fuel temperatures reached a.
in different portions of the core; b.
extent of oxidation of cladding in different temperature zones; c.
extent of damage to grids spacers; d.
evidence of UO mel ting; 2
e.
evidence of Zr/UO liquid phase formation; 2
f.
evidence of hydriding of zirconium cladding and the extent of hydride formation; structural integrity of fuel pins as a function of temperatures g.
reached; and h.
geometry of damaged fuel to assist estimates of coolability.
D.
Survey Auxiliary Building and Contents 1.
Radionuclide deposition E.
Flooding damage 3.
Contamination of steam relief valves, lines and let-down heat exchangers.
E.
Primary Coolant 1.
Coolant before and during decontamination to provide archival samples for analysis.
(It may be desirable to interrupt decon-tamination to dissolve lanthanides to obtain a sample of their abundance.)
1247 352
.