ML20205J631
| ML20205J631 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 02/07/1986 |
| From: | NRC |
| To: | |
| Shared Package | |
| ML20205J629 | List: |
| References | |
| NUDOCS 8602260215 | |
| Download: ML20205J631 (3) | |
Text
-.
SAFETY EVALUATION OF THE TEMPORARY REACTOR VESSEL WATER FILTRATION SYSTEM 4
==
Introduction:==
Operation of the Defueling Water Cleanup System (DWCS) revealed that the differential pressure across its filter canisters tends to increase rapidly.
As the differential pressure increases, the reactor coolant processing flow rate decreases. Consequently, only a relatively small amount of reactor coolant can be processed before the maximum-design pressure is reached and the filter canisters have to be replaced. The probable cause of this problem is the growth of micro-organisms in the reactor coolant.
This phenomenon has increased such that the amount of reactor coolant that can be processed between filter canister change-outs decreased from 250,000 gallons initially to about 45,000 gallons during the third change-out. While the licensee is 1
investigating the problem and developing a program to permanently correct the situation, a Temporary Reactor Vessel Water Filtration System (TRVWFS) has been proposed to improve the visibility in the reactor vessel such that defueling activities can continue.
System
Description:
The TRVWFS consists of a 75 gpm pump, a diatomaceous earth precoated filter assembly, a spent filter precoat waste collection drum, a gamma radiation monitor, radiation shields around the filter assembly and the waste drum, and the shadow shield wall enclosing the entire system.
Reactor coolant suction and return hoses are secured in the Internals Indexing Fixture (IIF) and submerged to no more than two feet below the' normal reactor coolant level (327'6"). The filter is housed in a shielded container and filtration is provided by about 10015 inch long by i inch diameter filter bags on which about 7 lbs of diatomaceous earth precoat is attached. The filter media can be regenerated by recirculation flow or the spent filter media can be drained to the waste drum and clean diatomaceous earth recharged. When the contact dose rate of the filter assembly reaches a predetermined limit (currently 3 R/hr), the filter media will be removed and recharged.
Criticality:
To approach criticality, either at the filter assembly or at the waste drum, a minimum of 70 kg of U0, has to accumulate. Several considerations will ensure that even a small fraction of that amount will..ot be accumulated.
(1) The filter assembly surface will be _ continuously monitored for gamma radiation. Filter change-out will take place prior to the radiation level reaching a conservative set-point (currently 3 R/hr).
In order for -
the amount of U0 to reach 70 kg, the corresponding radiation level would 9
have reached 15,000 R/hr. Therefore, there is a safety factor of about 5,000. The safety margin at the waste drum would also be a factor of about 500, assuming that it contains 10 filter media change-outs with each batch at the maximum radiation level prior to change-out.
9602260215 860207 l
PDR ADOCK 05000320 p
,ym.
. (2) The suction of reactor coolant will be taken through a hose in the IIF at no more than two feet below the normal reactor coolant level which is more than 10 feet above the top of the core debris bed.- At the maximum flow rate of 75 gpm through the 11" I.D. suction hose, there will be no velocity effects to pickup any significant amount of ' fuel debris from the debris bed. Only materials suspended in the reactor coolant will be removed.
It is estimated that no more than about 0.2 kg of.00 will 7
accumulate in the filter media after 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> of continuous operation assuming that the reactor coolant contains 1 ppm of'U0,.
This assumed U0, concentration is conservative.since analysis of th6 DWCS fluid has shbwn no detectable fissile material.
In ~ addition, it is estimated that the radiation level at the surface of the filter assembly containing-0.2 kg of U0 would be above 30 R/hr; a factor of about ten-above the radiation lehel when filter media change-out would have taken place.
(3) Sample analysis for gross alpha radioactivity will be performed on~ the waste drums. Although the amount of U0 in each spent filter media batch p
is expected to be no more than a few grams, analysis of the grab sample-from the waste drums will provide further assurance that no.significant quantities of U0 accumulate in each waste drum.
2 Radiation Dose Considerations:
Lead shielding will be provided for the filter assembly. and the waste drum.-
In addition, shadow shields will be installed around the entire system. A gamma radiation detector with remote read-out will continuously monitor the contact radiation level of the filter housing.
This radiation level is currently limited to 3 R/hr. At 3 R/hr, the dose rate to workers outside of-the shields on the defueling platform is expected to be no more than 5 mR/hr.-
The only times an operator must enter the shadow shields are during initial startup of a recharged filter to monitor filter differential pressure rise, during filter regeneration or replacement, and during waste. drum transfer.
4 During initial filter monitoring, the radiation levels are expected to be less than 10 mrem /hr. During filter regeneration or replacement, the shielding on the filter will reduce the radiation levels to less than 100 mrem /hr and the expected dose to the operator is about 50 mrem.
The expected dose to the operator during waste drum transfer is about 50 mrem. Based on these estinates, the staff concludes that the-projected occupational exposure is within the scope of considerations made in Supplement 1 to the Programmatic Environmental Impact Statement on TMI-2 Cleanup (PEIS).
==
Conclusion:==
Based on the above evaluation, the staff concludes that the operation of the TRVWFS does not pose a significant risk to the public or the occupational work force. The staff further concludes that its operation does not present an unreviewed safety question per 10 CFR 50.59 and the potential environmental consequences fall within the scope of activities already discussed in the-PEIS.
s i
i p
k
-e y
,w-y g
r-t
[/3 Dr. Thomas Murtry Willis'slabyv Sit 2 Manager
' Regional AdmiAistrator. Region I U.S. Departmext of Energy U.S. huclear Regulatory Cossatssion P.O. Bos 88 631 Park Avenue Middletown. PA 17057 0311 King of Prussia. PA 19406 David J. McGoff John L Wolfe. Eso.. Chairman.
Division of Three Mile Island Programs Administrative Jud9e ht.23 p
3409 Shepherd St.
U.S. Department of Energy Chevy Chase. MO.
20015 Washington. 0.C.
20545 Dr. Oscar H. Paris William LoChstet Administrative Judge 104 Davey Laboratory Atomic Safety and Licensing Per.nsylvania State University goard Panel University Park. PA 16802 U.S. huclear Regulatory Comunission Washington. D.C.
20555 Randy Myers. Editorial The Patriot Dr. Frederick H. Shon 812 Market St.
' Administrative Judge
- Harrisburg. PA 17105 Atomic Safety and Licensing Board Panel Robert 8.'Borsum U.S. muclear Regulatory Comission 84bcock & Wilcom Washington, D.C.
20555 Nuclear Po-ee Generation Division Suite 220 Karin W. Carter 7910 Woodmount Ave.
Assistant Attorney General Sett.esda, MD.
20814 505 [secutive House P.O. Som 2357 Michael Churchhl11. (sq.
harrisburg. PA 17120 PILCOP 1315 Walnut St.. Suite 1632 Dr. Judith H. Johnsrud Philadelphia. PA 19107 Environmental Coalttion on Nuclear Power Linda W. Little
+.
433 Orlands Ave.
5000 Hermitage DR.
5 tate College. PA 16801 Raleigh,wC 27612 i
George F. Trowbridge. Esq.
Marvin I. Lewis
~
Shaw. Pittman. Potts and 6504 Bradford Terrace Trowbridge Philadelphia. PA 19149 1800 M. St., kW.
Washington. D.C.
20036 Jane Lee
.g
. 'd 183 Valley Rd.
{[
Atomic Safety and Licensing Board Panel Etters.PA 17319 U.S. Nuclear Regula tory Comission
- p*
Washington, D.C.
20555 J.E. Liberman. Esquire
-1 Berlack.Israels. Liberman Atomic Safety and Licensing Appeal Panel 26 $ roadway s.
U.S. huelear segulatory Comission hew York, af.10004 J. -
Washington. D.C.
20555 Walter W. Cohen. Consumer Advocate Secretary Department of Justice U.S. huclear Regulatory Comission Strawberry Square. 14th Floor
~
ATTN; Chief. Docketing & Service Branch Harrisburg, PA 17127 Washington, D.C.
20555 Ed-ard O. Swart:
Mr. Larry Hochendoner Board of Supervisors Dau;Mn County Comissioner P.O. Ses 1295 Londonderry Township Ha rris burg.* PA 17103 1295 RFD #1 Geyers Church Rd.
Middletown. PA 17C57 John E. Minnich. Chairperson.
Robert L. Knupp. Esquire
~
Dauphin Ccunty Board of Comissioners Assistant Solicitor Dauphin County Courthouse Enupp and Andrews Front and Market Streets P.O. Bos P Harrisburg. PA 17101 407 N. Front St.
Harrisburg. PA 17168 0,avohin County Office of Emergency Prepa rednes s Court House. Room 7 John Levin. Esquire Front & Market Streets Pennsylvania PubliC Utilities Com.
P.O. Som 3265 Harrisburg, PA 17101 Harrisburg. PA 17120 U.S. Environmental Protection Agency Region 111 Of fice ATTN: CIS Coordinator Curtis 6utiding (Sisth Floor) 6th & Walnut 5treets Pniladelpnfa. PA 19106 Mr. Ed-in Eintner' (secutive Vice President
\\
Thomas M. Gerusky. Director Gene a! Public Utilities Nuclear Corp.
Eureau of Radiation Protection 100 tr.:ersace Park =ay Departpent of Environmental Resources Parsipa ny. kJ 07054 P.O. 6os 2053 Harrisburg. PA 17120 v
L.e r, Lennecy be Vern D % t'Ln wommenu> naenm L * *" M * * *** U t e
r pa se. F ia. doam cu. Aemu ce:
]Qap",
v., 2n.
ne n s:re+;. 5 1712f l.
)