ML20115E995
| ML20115E995 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 04/09/1985 |
| From: | Hukill H GENERAL PUBLIC UTILITIES CORP. |
| To: | Martin T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| 5211-85-2069, NUDOCS 8504190364 | |
| Download: ML20115E995 (7) | |
Text
.
ENuclear Eu"a';ftre""
Route 441 South Middletown, Pennsylvania 17057-0191 717 944 7621 TELEX 84 2386
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Writer's Direct Dial Number:
April 9, 1985 5211-85-2069 Mr. Thomas T. Martin, Director.
Division of Radiation Safety and Safeguards Region I U.S. Nuclear Regulatory Commission 631 Park Avenue 7
King of Prussia, Pa.
19406
Dear Mr. Martin:
Three Mile Island Nuclear Station Unit 1 (TMI-1)
Operating License No. DPR-50 Docket No. 50-289 Response to IR 85-04 Inspection Report 85-04, dated March 11, 1985, reported the results of the review of worker allegations relative to radiological controls implemented for certain steam generator tasks.
It was requested that GPUN submit a plan to implement the long term corrective actions set forth in Section 3.3 of the inspection report. The following information describes the actions that were taken to complete the long term corrective actions. We believe no further action is necessary.
1.
Radiological Engineering will ensure that in-head samples, representative of work breathing zones, are collected to support future 0TSG entries by February 15, 1985.
Response
Immediately following identification of OTSG airborne activity concerns, work in the OTSG head was terminated until a new ALARA review was conducted (see Section 3.3 of the Inspection Report). The revised ALARA review requires a sample to be taken by a lapel air sampling device (RAS pump) for each entry into the OTSG head area. This will provide an accurate and representative air sample of the worker's breathing zone.
All ALARA reviews for OTSG in-head work since December 28, 1984 have required a breathing zone air sample.
2.
Radiological Engineering will re-evaluate past OTSG entries and determine if the respirator protection afforded was commensurate with measured concentrations, considering past sanpling techniques by March 1, 1985.
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Response
A review'of OTSG air sample data, stay times, respiratory devices-in
.use. and whole body count data was conducted.. Based on reviewing the above items, it is concluded that adequate respiratory protection was e
.provided for all previous OTSG entries.
It must be.noted that while
.such a comprehensive evaluation of airborne radioactivity protection had not been done previously, evaluation of this area has been ongoing
- throughout all OTSG work periods, as required by the Radiological
' Protection Plan.
A review of OTSG air samples taken from 1/3/85 to 3/11/85 in ficates that ventilation unit suction air samples will typically yield results that agree with measured in-head concentrations within a factor of 10, provided that,both samples are started and stopped at approximately the same time. See Attachment 1.
1983)g work associated with kinetic expansion (Fall 1982 to. Summer Durin
,cVentilation unit air samples typically ranged from SE-9 to -
~3 -
If actual in-head concentrations are assumed to be up.to a factor of 10 higher than samples taken at the ventilation unit suction, the resulting MPC-Hour fraction with a respiratory protection factor of 1000 is 0.054 MPC-Hrs /Hr. - See Attachment 2.
The maximum in-head air sample activities seen during several recent evolutions including welding, grinding, and stabilization was 1.3E-7 uCi/cc Co-60 and 1.7E-10 uCi/cc gross alpha. Samples of OTSG
^
contaminants sent to an outside laboratory for. analysis determined the
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alpha emitting activity to be due to Pu-238, Pu-239/240, Am-241 and Cm-243/244. See Attachment 3.
Since the maximum time any individual could spend in the OTSG in one
. quarter is 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> due to_ external exposure limitations, the maximum MPC-hrs, an individual could receive is 0.2 MPC-hrs. Based on a protection factor > 1000 for respirators utilized throughout all work evolutions, the airborne activity concentration would have to be approximately IE-5 uCf/cc Co-60 to exceed the protection factor of the respirator.
Respirators with a protection factor of 50 were used on some OTSG entries for inspection only. The maximum time spent by any individual in the OTSG area with this type of respiratory protection in.any calendar quarter was less than two hours. Since airborne activities during.these inspections are less than those during periods when actual work is. performed, the maximum MPC-hrs. an individual could have received during any quarter is < 2 MPC-hrs.
It is also unlikely that the protection factor of these respirators would have been exceeded at any time. This is supported by the results of bioassay conducted during the OTSG repairs. There were no cases of whole body counts showing activities greater than 20 nCi of Co-60 that were not attributable to a specific incident (e.g., skin contamination). This also includes whole body counting done as a quality control check on the respiratory protection program performed on 10 random individuals per quarter.
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. 5211-85-2069 i L
' 3. ' Radiological Engineering will have OTSG. samples analyzed for alpha
-emitters and adjust "MPC-Hour" assignments as appropriate by March 31, 1985.
Response
OTSG smears were obtained and sent to an offsite vendor for alpha
- spectrometry analysis to define specifically which alpha emitting radioisotopes were present. This qualification allows comparison of air concentration to the appropriate MPC value in 10 CFR 20. MPC-hr.
assignments have been adjusted and are contained in the Evaluation'.of Internal Dose (see Exposure History file) and the REM System for the affected workers.
4.
Radiological Engineering will reassess the validity of the 2E-12 uCi/cc, alpha permissable concentration value as it pertains to the assignment of personnel "MPC-Hours" by March 31, 1985.
Response.
The 2E-12 uCi/cc MPC in air for Plutonium is for sol'uble Plutonium-239 and is utilized in procedure as a conservative.value for unknown alpha emitting mixtures. Experience in Light Water Reactor operation has shown that Plutonium stemming from reactor fuel coninonly found-in systems and waste is of the insoluble form. By contrast, Cesium, which~
is the predominant radioactive element in TMI-1 at this time cannot normally be found.in high activity samples associated with the steam generators due to its solubility. The predominant isotope associated with the steam generators is Cobalt, and remains in the generator (as it isinsoluble).
In performing isotopic analysis of generator alpha activity, it was found that radioisotopes of Plutonium, Americium and Curium are present.
In the case that these elements were readily soluble, one would not expect to see their presence on samples, especially in light of the very high beta / gamma to alpha ratio, where only very small quantities of alpha activity are present.
. Utilization of soluble Plutenium-239 can_ be seen as overly conservative. A more accurate, yet conservative MPC value of 3E-11 uCi/cc based on insoluble Plutonium-238 can be applied when a specific case isotopic abundance is unknown, based on known plant radioisotope presence of Pu-238, Pu-239 Pu-240, Pu-241, Pu-242, Am-241, l
Cm-242, Cm-243, Cm-244.
As indicated in the Inspection Report, applicable procedures would be revised if necessary. As a result of the evaluation of the incident, a procedure change has been made for MPC-hour assignment to utilize 3E-11 uC1/cc for unknown abundance alpha so that overly conservative alpha MPC-hr. values will not be assigned to individuals.
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5211-85-2069.
r In addition, clarification of some of the material contained in the report is necessary.
In Section 3.1, Initial Findings, the verbage " licensee refusing to provide respirator protective equipment" is found. A refusal implies that.some request was associated with respirator issuance. No such request was ever made at the. pre-job briefing. Also, under Section 3.1 the report states:
" Subsequent Whole Body Counts (WBC) performed by the licensee revealed unexpected high results on five of the individuals involved, i.e., 50 to 100 nanocuries, predominately Co-60.
Such levels required the assignment of personnel exposure due to internal deposition of radioactive material."
The range of whole body counts' was made from non-detectable to 110.7 nanocuries. This was provided during the inspection via Radiological
-Investigation Report 84-014. The assignment of personnel exposure was only necessary in three cases out of_ five.
l IR 85-04, Section 3.2, Details, did not mention the fact that a formal pre-job briefing was held with all involved workers.
Sincerely, 2
Director, THI-1 HDH/SM0/spb:0222A
' Attachments cc:
R. Conte J. Thoma 1
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ATTACIMENT 1 COMPARISON OF AIR SAMPLE DATA VENT UNIT ACTIVITY IN-HEAD ACTIVITY In-Head Activity DATE Time On Time Off Activity Activity Time On Time Off Vent unit Activity 01/03/85 0845 0941 8y 7.2E-11 8y 3.3E-10 0852 0932 4.6 01/04/85 1001 1055 8y 7.7E-11 8y 3.2E-10 1022 1052 4.2 01/08/85 1017 1043 Co-60 2.1E-9 8y 1.9E-8 1013
-1042 9'. 0 01/24/85 0923 1003 8y 1.8E-10 Co-60 1.8E-9 0931 1001 10.0 01/25/85 1220 1328 Co-60 2.1E-9
- 8. y 2.6E-9 1240 1243 1.7 8y 5.3E-10 1245 1305 8y 3.6E-9 1307' 1311 8y 2.0E-9 1314 1325 02/15/85 0904 1058 8y 6.4E-11 8y 5.6E-10 0921 1025 8.8 8y 3.7E-10 1026 1044 02/16/85 0817 0954 8y 1.2E-10 8y 2.57E-9 0850 0929 21.4 03/11/85 0930 0955 8y 6.9E-11 8y 3.7E-10 0933 0938 5.4 r
ATTACHMENT 2
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.MPC FRACTION CALCULATION SE-7 uC1/cc Co-60 MPC-Hrs
- 054 1*,
=
(9E-9 uC1/cc)(1000)
Hr 1.3E-7 uCi/cc Co-60 MPC-Hr
.014 2.-
=
(9E-9 uC1/cc)(1000)
Hr 1.7E-10 nCi/cc Pu-238 MPC-Hr
.005
=
(3E-11 uCi/cc)(1000)
Hr
--n---
--,e--u
--m-,--.
ATTACHMENT 3 ISOTOPE SAMPLE 1 SAMPLE 2 SAMPLE 3 AVERAGE Pu-238 28.6%
27.9%
29.4%
28.6%
Pu-239/240 27.2%
32.5%
28.7%
29.5%
Am-241 33.8%
34.8%
30.9%
33.2%
Cm-243/244 8.7%
3.9%
7.4%
6.7%
98.3%
99.1%
96.4%
98%
Isotopes with average proportions <1% of total activity are not incided.
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