IR 05000413/1987001

Insp Repts 50-413/87-01 & 50-414/87-01 on 870107 & 28.No Violations or Deviations Noted.Major Areas Inspected: Investigation of Auxiliary Bldg High Radiation Levels & Subsequent Onsite & Offsite Dose Estimates

ML20211A389
Person / Time
Site:	Catawba
Issue date:	02/03/1987
From:	Kahle J, Kuzo G NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
To:
Shared Package
ML20211A338	List: IR 05000413/1987001 ML20211A334
References
50-413-87-01, 50-413-87-1, 50-414-87-01, 50-414-87-1, NUDOCS 8702190163
Download: ML20211A389 (4)

Text

- _ _ _ _ _ _ _ _ _ _ _ _ _ .

p rf 4f,' UNITE 3 STATES

'o NUCLEAR REGULATORY COMMISSION

"

[" , REGION il g

j 101 MARIETTA STREET * ATLANTA, GEORGI A 30323 s., * " * * /

FEB 0 61987

, Report Nos.: 50-413/87-01 and 50-414/87-01 Licensee: Duke Power Company j 422 South Church Street  !

Charlotte, NC 28242 Docket Nos.: 50-413 and 50-414 License Nos.: NPF-35 and NPF-52 J Facility Name: Catawba 1 and 2 Inspection Conducted: January 7 and 28, 1987 Inspector: trat @ k) 3 bl% 1737 Date Signed G.5.Ku{o Accompanying Personnel: J. B. Kahle Approved by: _Mhj[Ald 2/7/J 7 J./B Kame, Section Chief Data Signed Erhe ency Preparedness and Radiological

\ rotection Branch Division of Radiation Safety and Safeguards SUMMARY Scope: This reactive announced inspection involved investigation of auxiliary building high radiation levels and subsequent onsite and offsite dose estimates

. associated with unplanned gaseous releases from the Waste Gas Decay Tank (WGDT)

syste Results: No violations or deviations were identified, i

i B7021'/0163 070206 PDR i

0 ADOCK 05000413 PDH l

. - - - . . - . . _-_ - __

__.-_ . - _ . ,. - . -

. _ _ _ - - - - - - - . - -.-

-

.

REPORT DETAILS Persons Contacted Licensee Employees

. J. W. Hampton, Plant Manager

• P. Deal, Station Health Physicist B. N. Kimray, Health Physics Shift Supervisor S. G. Powell, Health Physics Shift Supervisor C. L. Hartzell, Licensing and Project Engineer s

• P. N. McNamara, Health Physicist

A. Duckworth, Radwaste Chemistry Coordinator l *P. Simbrat, Health Physicist

R. E. Sorber, Health Physicist, General Office i

Other licensee employees contacted included engineers, technicians, operators, and office personnel, i * Attended exit interview

! Exit Interview

"

! The inspection scope and findings were summarized on January 28, 1987, with

those persons indicated in Paragraph 1 above. The inspector noted that this 1 investigation concerned the unplanned radioactive release and subsequent i onsite and offsite exposures. Investigation of the causes and licensee i actions resulting in the release event were to be reviewed by the NRC

resident inspectors and documented in Inspection Report Nos. 50-413/86-51 and 50-414/86-54. The inspector noted that the released concentrations and

'

j

subsequent exposures did rot exceed regulatory compliance limits. The

licensee did not identify as proprietary any of the materials provided to or i

reviewed by the inspector during this investigation.

] Unplanned Waste Gas Decay Tank Releases

Notification and Event Details

, On November 6,1987, NRC Region II representatives were notified of an j unplanned gaseous release from the Catawba Nuclear Station (CNS) Waste i Gas Decay Tank (WGDT) syste On January 7,1987, NRC Region 11 Radiological Effluents and Chemistry (REC) section personnel were dispatched to the Catawba site to review licensee actions regarding the

event. Preliminary investigation determined that the release occurred ,

i as the result of maintenance activities and the mechanical failure of a i WGDT system compressed air drain trap valve in Room 213 of the j auxiliary building (543 elevation). The inspectors reviewed WGDT j system piping diagrams, and toured the WGDT piping and drain trap 4 system areas, to confirm licensee descriptions of the indicated release point and areas where elevated noble gas concentrations were reported,

]

f

__ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ . ._ ___ __ ___

-

.

Detailed investigation of the causes and licensee actions resulting in the unplanned release were conducted by the NRC resident inspectors (documented in Inspection Report Nos. 50-413/86-51 and 50-414/86-54).

This report details the released quantities and subsequent exposure estimates to persons on and off-sit ,

b. Auxiliary Building Eleveted Noble Gas Concentrations The inspectors discussed 'and reviewed licensee reports detailing identification and investigation of elevated noble gas concentrations in selected areas of the auxiliary building on January 5,198 Initial high background readings were observed at approximately 1030 hours0.0119 days <br />0.286 hours <br />0.0017 weeks <br />3.91915e-4 months <br /> for friskers located 'in the Decon and Change Rooms on the auxiliary building 594 elevatio Followup surveys and air samples indicated elevated noble gas concentrations in these areas with highest exposure (5 mR) in the glove port of the Grit Blaster located in the Decon Roo Additional licensee investigation of auxiliary building area friskers indicated high background levels also on the 543 elevation. Additional gross radiation surveys on this elevation indicated elevated background readings in the Gas Decay Tank (Room 213)

and Floor Drain Pump (Room 214) Rooms. Additional detailed surveys and air sampling of Rooms 213 and 214 were then conducted. The ultimate source of the gaseous release into the auxiliary building areas was determined to be a malfunctioning WGDT system compressed air drain trap valve in Room 213. Radioactive gases were released from the WGDT system trap into Rooms 213 and 214 during maintenance work on waste gas valves. Furthermore, the gas was dispersed from these rooms Sto the Decon and Change Rooms and finally through the Unit 1 stack vent to atmosphere by normal auxiliary building ventilation. From observations of the in-service tank differential pressure, the release was initiated at approximately 0900 hours0.0104 days <br />0.25 hours <br />0.00149 weeks <br />3.4245e-4 months <br /> and subsequent licensee actions to isolate the tank and terminate the release from the WGDT system were completed at approximately 1600 hours0.0185 days <br />0.444 hours <br />0.00265 weeks <br />6.088e-4 months <br />. All frisker, area monitors and stack vent monitors indicated normal background levels of activity for the auxiliary building by 2200 hours0.0255 days <br />0.611 hours <br />0.00364 weeks <br />8.371e-4 months <br /> on January 6,198 The inspector discussed exposure to individuals working on the WGDT system and personnel conducting surveys to determine the source and extent of the high background problems in the auxiliary buildin Surveys conducted in the vicinity of the WGOT maintenance work (Elevation 543) indicated normal readings throughout the even Highest concentration of gaseous contaminatiun was indicated for Room 213, approximately 73 MPC. There was no indication of unmonitored exposures to personnel in the areas (Decon Roum, Change Room, Room 213, and Room 214) having elevated noble gas concentrations. The inspectors reviewed dose assessment records for personnel exposed during survey and air sampling activities in these area A total of 8 individuals were assigned a beta skin exposure ranging from approximately 0.3 to 23 mre Followup body burden analyses did not indicate uptake of radioactive contaminants by the exposed individual .

o 3 Offsite Releases The inspector discussed radionuclide accountability for the offsite release with cognizant licensee representatives. During the unplanned release from the in-service WGDT into the auxiliary building, gaseous input to the tank also was occurring from normal operations. Thus, the volume of gases released could not be accurately determined from the WGDT pressure differential measurement Licensee representatives utilized the Unit 1 Plant Vent Monitor (IEMF-36) activity and flow readings to estimate the WGDT release rats and total activity release The release from the WGDT system was estimated to have lasted for 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br />, however, elevated readings for the plant vent were recorded from 1030 hours0.0119 days <br />0.286 hours <br />0.0017 weeks <br />3.91915e-4 months <br /> on January 5 through 2200 hours0.0255 days <br />0.611 hours <br />0.00364 weeks <br />8.371e-4 months <br /> on January 6,198 Radionuclide determination of grab samples collected on January 4 and 5,1987, from the WGDT system were utilized to determi e the nuclide composition of the released gas. The estimated total a civity released was 65.94 C1 of noble gases and 0.0012 Ci of tritium. Licensee data for the composition of gases released were as follows: Xe-133, 64.4 Ci; Xe-133m, 0.74 C1; Xe-135, 0.37 Ci and Xe-131m, 0.4 C1. The licensee calculated dose estimates using Offsite Dose Calculation Manual (0DCM) methodology. Based on the total activity and composition of noble gases and tritium released from the WGDT system, the 50 year -

whole body dose commitment was estimated to be 0.0136 mrem for a person at the site boundary' (0.5 mile). The inspector noted that the concentrations released and estimated doses were within regulatory compliance limits.

No violations or deviations were identified.