ML19206B374
| ML19206B374 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 04/02/1979 |
| From: | Kenneke A NRC OFFICE OF POLICY EVALUATIONS (OPE) |
| To: | Ahearne J NRC COMMISSION (OCM) |
| References | |
| NUDOCS 7905090257 | |
| Download: ML19206B374 (6) | |
Text
e f' M%q'e UNITED STATES p
8 NUCLEAR REGULATORY COMMisslOfJ
$,g,, ; /. 3 s
V. ASHINGTON, D. C. 20555 WS4/*'l
%. ',1. "
April 2, 1979 MEMORANDUM FOR:
Ccmmissigner Ahearne n
('-
FRCM:
A eke, Acting Director, OPE
SUBJECT:
FACTORS IN DECONTAMIflATION OF TMI At your request, OPE has prepared some preliminary thoughts for decontam-ination of TMI.
It must be noted that the true 6)Sent to which TMI is contaminated is unknown at this point.
There is substantial fission product activity within containment as well as in the reactor coolant system.
(How-ever, corrosion levels are expected to be low as a result of TMI heing a new plant.) Accurate estimates of the decontamination job can only be estimated at a time when a detailed radiological survey of the affected buildings and containment can be made. Attachment I presents a first cut at preliminary steps in decontamination and Attachment 2 cites experience relevant to power reactor decontamination.
Enclosures:
As stated cc:
Chairman Hendrie Commissioner Gilinsky Commissioner Kennedy Commissioner Bradford Leonard Bickwit Sam Chilk CONTACT:
Ted Quay (OPE) 634-3295 Dennis Rathbun (OPE) 634-3295
- i
():
I L
i905000Z W l'
PRELIMI'1ARY STEPS IN DECONTAMINATION Decontamination must proceed., a planned, orderly fashion with two overriding Ab)CchrVC.L
- - ~
~ n-1=eca+as.
1)en.fL/
=r+ exposures to workers and public a
- 2) obtain information on plant to ensure diagnosis of accident can be made.
(a) Training and manning of an adequatelf qualified work force will be complicated by the radiation levels within containment. Worker exposure limits will limit the available labor force. An early step will be for the utility to locate and mob'lize the necessary labor resources for the job of decontamination.
b) An essential first step will be to conduct -a detailed radiological survey of the affected TMI buildings as well as the containment building itself. Large quantities of contaminated gas in containment must be removed, stored, and shielded.
(c)
Cool down of reactor coolant system (RCS) and continued purification of the RCS.
Decontamination of RCS depends upon the quantity of failed fuel, and cleanup will depend upon quantity of fission products and transuranics released from failed fuel.
Decontamination work where transuranics are present is particularly difficult due to the risk of inhalation of alpha emitters.
(d) Remove fluid inventory from the reactor containment.
Cleanup of this fluid will use ion exchange, filters and evaporators in order to remove
\\I4 c).3 f.-
_2_
the fission products.
The presence of failed fuel will substantially exacerbate handling of spent filters, ion exchange resins as well as solicification of evaporator bottoms. Addition of sodium hydroxide --
which is chemically caustic -- further complicates decontamination. (The sodium hydroxide wac added by spray actuation in the containment vessel.)
(e)
Defueling is likely to be one of the most complicated decontamination operations for TMI.
Defueling will entail procedures modified as neces-sary to deal with contamination and the damaged condition of the fuel. In this regard it may be expected that some of the fuel elements cannot be
.cked up normally.
Io past instances where fuel has failed, some fuel elements have aither been fused or wedged together.
If this is the case, separation by remote operations will be requireo prior to re noval of fuel.
Such operations as reactor head removal will undoubtedly be substantially complicated by the presence of fission products and transutanics on its inner surface.
It may be necessary to insert failed fuel elements in containers before movement to storage.
(f) Containment vessel decontamination:
Some fission products will have been deposited on the containment walls and equipment surfaces (e.g. iodine plate-out as a result of xenon decay). To remove longer-lived nuclides within the containment involves wash down with water or mild soap and water solutior. (so mild as not to effect rad waste systems).
(g) Present water storage facilities (around 200,000 gallons) appear to be grossly inadequate for rad waste storage; and tamporary additions are u3
m currently being put in place. The additiUns will incorporate protection measures such as overflows lines and concrete dikes.
Overflow lines will need to be rerouted to rad waste handling facilities in auxiliary buildings.
Treatment of large quantities of liquid wastes will probably existing plant capability and it may be necessary to bring in additior.al equipment.
(h) The auxiliary building will require decontamination, i.e. wash-down and other action as appropriate.
\\16 o3 c.
Experience Relevant to Pcwer-Reactor Decontamination and Rehabilitation Preliminary Information from DOE (April 2,1979) 1 Most relevant experience:
NRX, Chalk River, Ont., Canada Accident, in 1950's, involved emergency core cooling, meltdown, use of river water.
Heavy water reactor.
Uncontained.
Complete removal and burial of reactor.
- Restored to operation about 1961 or 1962.
Further recovery operations in 1971-72 included decontamination and replacement of top shield.
DOE contact described the decontamination and rehabilitation work as good work: good planning, tooling up, and execution; good organization and procedures; disciplined program. Advance estimates of exposures found accurate.
U.S. heloed.
DOE contact thought AECL and Ontaric Hydro could render valuable help on TMI and would want to help if asked.
f q.3 u
_2_
2.
Relevant IJ.S. Exoerience:
(a)
Elk River (Consumers Power) -- dismantled by Nuclear Engineering Services Co.
(b)
SL-1, Idaho (Armv low-power reactor): fatal criticality accident ( 1961).
D&D by GE.
(c). Enrico Ferni Reactor, D&D by Argonne.
(d)
SRE (Sodium Reactor Experiment, Atomics International, Santa Susanna, California) -- dismantling; shipment to Beatty, Nev.
(e)
K West Reactor, Hanford. Fuel damage.
Cleanup in 1950's did not include cleanuo of graphite moderator, which is still contaminated; will need cleanup at decommissioning.
3.
Relevant studies and planning:
(a) Nuclear Engin2ering Services preparing handbook on D&D for DOE.
(b) United Nuclear (Hanford) developing D&D plans for Hanford production reactors.
(c) Battelle Northwest:
D&D studies for LWR's.
4 General corrents by DOE contact:
(a) DOE would undoubtedly wish to assist if asked, with in-house apd contractor resources, in planning and conduct of TMI rehabilitation.
(b) Where to take contaminated materials and equipment could be a problem.
Barnwell may be the only available place now.
May have to store temporarily at TMI plant site till off-site arrangements are made.
v \\l
<