IR 05000184/1990003
| ML20055G848 | |
| Person / Time | |
|---|---|
| Site: | National Bureau of Standards Reactor |
| Issue date: | 07/18/1990 |
| From: | Pasciak W, Sherbini S NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | |
| Shared Package | |
| ML20055G845 | List: |
| References | |
| 50-184-90-03, 50-184-90-3, NUDOCS 9007240229 | |
| Download: ML20055G848 (10) | |
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- U. S. NUCLEAR REGUIATORY COMMISSION p REGION I i L-Report N /90-03 Docket N License N IRE f Licensee: U. S. Decartment of Commerce [
National Institute of Standards and Technoloav g,aithersbura. Maryland 20849 Facilit;r name: National Institute of Standards and Technoloav 3 Inspectier. At: Gaithersbura. Maryland Inspection-Conducted: June 5-7. 26. 1990 Inspector: LA 12 7'//8/70 S. Sherbini, Senior Radiation Specialist date Facilities Radiation Protection Section Approved by: / /> rf6! 7!l8 90
/ WAasciak, Chief, Facilities Radiation
/ pate Protection Section
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Insoection Summarv: Inspection on June 5-7, 26, 1990 (Report N I 50-184/90-03)
A.reas Insoected: A routine, . unannounced inspection of the- i radiological controls program on sit Results: Within the scope of this inspection, no violations were identified. Some areas for improvement were identified and are described in the attached inspection repor G4 g qgg90k o
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~2 DETAILS 1.0 Personnel Contacted .
l T. Hobbs, Chief, Health Physics
- M. Rowe, Chief, Reactor Radiation 1 Division
- T. Raby, Chief, Reactor Operations .
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L'. Slaback, Supervisory Health Physicist J. Shubiak, Health Physicist ,
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- -Denotes attendance at the exit meetin I 2.0 Heat Exchancer Leak A primary to secondary leak developed in one or the.two main ]
reactor heat exchangers following a reactor shutdown on May 4, 1990. The . primary system contains heavy ' water and the secondary system ordinary water. Routine analysis of the secondary system water for radioactivity on May 4 did not show i- any - unusual activity levels ( sample analysis showed .102 o disintegrations per minute (dpm)/ml of secondary water) .
L However, a sample of secondary water taken on May 5 showed l- unexpectedly elevated tritium levels (3961 dpm/ml). The i tritium activity in the primary heavy water is currently about i 600 uCi/ml, and the licensee stated that the observed activity in ' the secondary water at that time represented a total primary to secondary leak volume of about one liter. The sample was taken from the cooling tower basin and the
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secondary water circulation pump was runring at that time. The ,
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. fact that the pumps were running meant that there was mixing between water in the tower basin and in the secondary sides of both main heat exchangers. The basin is common to the two .,
heat exchangers. A second sample taken about one hour-later j showed that the levels of tritium had continued to increase (6662 dpm/ml). The licensee stated that the observed rate of
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4 increase of activity in the secondary water corresponded-to '
a leak rate of approximately 10 liters per day. A third sample I taken about one and one half hours after the second sample showed still higher tritium levels (9086 dmp/ml).
Based on these water analysis data, the licensee decided to l
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- isolate the heat exchangers. Samples taken from each of the
- two- exchangers about two hours after isolation- showed the :
level of activity in 1B had remained steady at the isolation j level but that the level in 1A had increased to'about 10,000 'l dpa/ml, indicating that the leak was in 1A. The secondary ~J L water in the heat exchangers was then pumped out to the L cooling tower basin and the leaking tube in.lA was found and
- plugged on May 6. The reactor was back at power by May i Based on the sample analysis of cooling tower basin water of 10,000 dpm/ml, the licensee estimated that the total leak from ,
the primary to the . secondary system was approximately liters of heavy water. Since the ~ tritium activity. in the
- primary water ~is about 600 uci/ml, the total tritium in-the
- secondary water was estimated to have been a little over 1.7
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Ci. This--activity was released to the atmosphere by evaporation of the water in the secondary system,-after the reactor _ resumed operation, and the addition of' clean makeup water to the syste According'to the reactor's Technical Specifications, a leak j rate of greater than 36 gallons per. day requires that the j reactor be shut down.-The reactor was shut down at the time of discovery of the lea Technical - Specifications also requires that the licensee report any major degradation of one L of the several boundaries which are-designed to contain the radioactive materials resulting from the fission process. Th t licensee's. estimate of the leak was a total of 2.9 liters in about a period of less than one day. This is equivalent-to ,
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0.77 - gallons per day, which is well below the Technical Specifications shutdown requirement, and on that - basis the i leak'is also not considered to be a major degradation of a .l'
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fission product boundar reporting requirement, therefore, did not apply. The licensee, however, did report the leak-to the NRC Regional staf ;
i According to. the Technical Specifications, the maximum allowable concentration of radioactivity released from the reactor building stack, averaged over a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> period, is 10,000 times the maximum permissible concentration (MPC). In .
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the case of tritium releases, the MPC is 2E-7 uCi/ml, and the corresponding maximum concentration is therefore 0.002 uC1/ml.
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Assuming that the 1.7 Ci of tritium were released during a period not exceeding 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, and using an air flow rate in the stack of 7.8E8 ml/ min (the standard flow rate during reactor operation), the average concentration of tritium ;
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m during the 24-hour period was 1.5E-6 uCi/al, which is well below the maximum allowable concentratio !
Based on the above data, there does not appear'to have been
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any violation ef regulatory or other requirements as a result of tho' lea .0 Release of Activity tr the Storm Drain 1 The' cooling tower basin is equipped with a steam line that was l used in the past to heat the water in the basin during cold I weather to keep it from freezing. Experience has demonstrated that-the steam was not needed, and was therefore no longer ,
used, but the steam line had not been removed. Under normal- l operating conditions, the line is submerged in.the water in the basin. On May 5, an operator noticed during a routine tour of the tower area that the open end of the line, projecting from the side of the basin, was leaking water onto the ground 4 adjacent'to the tower. The water from that area eventually
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reaches the storm drain. This leak was found about 2-hours I after discovery of the primary to secondary leak in the heat I exchanger, discussed ~in Section 2.0 above. Apparently, the !
steam pipe section that is submerged in the basin water had I corroded and basin water had entered the pipe and leaked out 1 of the basin via that route. The tritium activity in the basin I water at that: time was 6000 dpm/ml, and the licensee estimated - l that the total volume of water that leaked out of the tube was I L not more than 30 gallons. The total tritium released was therefore about 307 uci. The licensee stated that they diluted i the leak with about 12,000 gallons of clean water, giving an I average tritium concentration in the effluent ot 6.8E-6 uci/ml. This is substantially below the concentration of 3E-3 uCi/ml allowed for releases into sewerage systems by 10 CFR Part 20.303,
On M "' 7, 1990, a second inadvertent release of tritiated watet into the storm drain took place. The reactor was still- l shut down but preparations were underway for startup, which- )
took place on the following day. The release occurred when the
- ' water in the cooling tower basin, still contaminated - with L tritium from the heat exchanger leak, overflowed onto the ground around the tower. The overflow occurred at one point on the edge of the basin, a low point in the structure. The L
licensee's investigation of the incident determined that the b ,
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leak was caused ' by expansion of a large air bubble in a secondary pipe- leading to the basin.-The expanding bubble'
pushed water ahead of it into the basin, raising the water level and causing the overflow. The concentration of tritium int the water .at that' time was about SE-3 uCi/ml, and-the vrlume of water that overflowed was estimated to be about'200 gallons. The amount of tritium in the spilled water based on this data was about 3.8 mci. The licensee diluted this spill.-
with 7000 gallons of clean water. to give an_ average -
concentration of 1.4E-4 'uCi/al, which is less than the maximum allowable' concentration of 3E-3 specified in 10 CFR ' Part 20.303. The dilution water was supplied to the site of the spill by means of a hose connected.to a water hydrant. The licensee stated-that they estimate the flow rate from the hos by using.a bucket of known volume to collect a sample in a
= measured time interva .0 Review of Personnel Dosimetry Records A review of the personnel dose records for the reactor facility showed that there were no exposures above applicable limits during' calendar year 1989. A total of 335 persons were monitored for radiation exposure during this period, both for external whole body exposure and for internal tritium exposure. The collective dose for 1989 was 13.604 man-rem, with the seven highest exposed individuals contributing 4.110 man-rem (30.2%) and the 17 highest exposed persons (5.1%)_
contributed 8.033 man-rem (59.0%) . - The individual doses for the seven highest exposed individuals were in the range of 500
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750 arem. The 1989 collective dose is lower than the corresponding dose for 1988 of 20.534, but the reactor was shut down during_the second half of 1989 for modifications connected with installation of the new cold neutron facilit The same exposure pattern was evident in 1988 as in 1989: for 1988 about 7.8% of the exposed individuals (a total of 335, the same as during 1989) contributed about 64% of the collective dose. A review of the exposure records showed that the highest exposed persons.were usually reactor operator The licensee stated that the reactor operators perform all the
' routine maintenance and repair work on the reactor systems and that was the reason for their relatively high dose P
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- 5.0' Environmental Releases The records for releases of radioactivity-to the environment j'
during 1989 and the early part of 1990 were reviewed during this inspection. The. liquid effluent releases were as follows:
Year Volume, al Tritium. Ci Bata/ Gamma. Ci '
1989 4.51E8 2.85 3.89E-3
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, 1990 3.11E8 1.28 5.94E-4
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The liquid-releases are made to the. sanitary sewer via--the !
liquid radwaste system, which collects all liquids from-the reactor building in a 1000 gallon retention tank and a 5000 -
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gallon waste holdup tank. The contents of the retention tank- +
are periodically pumped into the holdup tank, and the contents 1 of the holdup tank are released periodically ~ after the t
contents _are sampled for radioactivity. The total activity released during 1989 from the reactor- facility, other than tritium, is substantially below that allowed by.10'CFR'Par (20.303). The activities released by other buildings on site are substantiallv lower than those from the reactor building. The licensee 'was granted a regulatory exemption from the total activity limit on tritium specified in 20.303(d):of-5 Ci_per year (change No. S to the license, April 4, 1972). l Nevertheless, the total activity released was below that 1 limi l l
The gaseous releases from the reactor building stack-during 1988, 1989 and up to March 31, 1990 were as follows:
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Year Arcon. Ci Tritium. Ci 1988 899 393 1989 328 461 1990 0 8 ,
The releases during 1989 were not typical because of the I extended reactor shutdown during the second half of the yea I The argon-41 releases are quantified by using the total counts accumulated during specified time intervals (5000 minutes) by a stack monitor and converting these counts to a corresponding
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activity using a calibration constant- and an air flow rate
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from the stack of 7.8E8 al/ min. Monthly grab samples of _ stack (
air are also taken to verify. proper operation of'the stack ,
monitor. Tritium releases are quantified using one hour col trap grab samples. The average concentrations of argon and tritium for 1989, based-on the licensee's calculations,-were approximately 8E-7 uCi/ml and ' l.2E-6 uCi/ml,- respectively.
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These values are below the average annual concentration limits permitted by Technical Specification .0 Environmental Monitorina Section 5.9 of the Technical Specifications requires that an j
environmental monitoring program be implemented.to determine !
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the levels of radioactivity in the environment in the vicinity
- of - the - reactor facility. The program is to include as a minimum the quarterly analysis of samples from area streams,.
vegetation or soil, and air monitoring. The licensee has implemented such a program, with monthly sampling of water, grass and soil. Grass is sampled during the growing season and soil is sampled during the non-growing season. Air monitoring is accomplished using environmental thermoluminescent dosimeters (TLD) .. The TLDs are exchanged on a quarterly basis and are- distributed around the NIST site perimeter and at l various other locations within the site as well as off sit :
The. soil and grass samples are analyzed on a gamma j spectrometer, and the water samples are analyzed on a' gamma 'l spectrometer and are also analyzed for tritium content, j
i The results of environmental sampling for 1989 and the early '
part of 1990 were reviewed during this inspection, and no indications of environmental impact of reactor operations were identified. The licensee stated that they review each month's analysis results to determine if thera were any significant l deviations from those of the previous two or three months. The l
,.. comparison with previous results is done qualitatively. The l l, licensee also stated that they have not to date identified any !
radioactivity or radiation levels that are attributable to
'i reactor operation. The inspector stated'that. comparison of f current monthly environmental sample . analysis results with I those from the previous two or three months to detect a trend J may not be a sufficiently sensitive method to detect slow, low I h
level buildup. The licensee stated that they will consider a
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quantitative plot of selected parameters over extended time I
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periods to help discern long term trends if any are presen s Staffina and'Oualifications
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i There have been no changes in the_ structure of the reactor _
L health physics organization since the previous NRC inspection, but there have been changes in personnel occupying some of the ,
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positions. The Chief, Reactor Radiation Division retired recently and a new chief has been appointe A health physicist and a physical science technician were also hired *
to fill- two vacant positions in the health physics '
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organization. The'licensse stated that the staff is quite
, stable:and'that most of the current staff have been at NIST for~a long time.-The licensee also stated that.the minimum qualifications requirements for the -physical- science technician positions are those specified- in -the office of Personnel Management (OPM) classification scheme. This scheme does not guarantee that the physical science technician would p also be trained in health physics, but any deficiencies in the p' technician's health physics background are corrected by onsite -
training in the areas of weakness.
i Technical Soecifications Surveillances Records indicating performance of surveillances required by
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Technical Specifications were reviewed during this inspectio The records reviewed included those for recent-completion of _;
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the following surveillances:
l-o Operability of confinement closure system o Source trip for the closure system o Integrated leak rate tests for the confinement building L o operability.of the N-16 monitor on the secondary-L cooling system L o Calibration of the N-16 monitor l o Operability of the emergency exhaust system o operability of the emergency control station o Absolute filter testing on exhaust systems o Charcoal absorber testing on exhaust systems o operability of area and fission product monitors o Calibration of area and fission product monitors
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L The -records indicated that the operability checks, 3 calibrations, and tests were being performed on_ time.and at the required frequencie .
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One ite.a-for improvement was identified in connection with
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ca]ibration of the area monitors. The procedures do not :;
specify acceptable ranges for as found and after calibration ;
monitors readings. For example, the records showed one monitor was considered calibrated when it read 50 R/hr in a known r
field of 36 R/hr. .Other similar examples- were found. . The -
l; licensee stated that it is difficult to obtain 'an accurate i reading from the meters on these monitors because the scales ;
are logarithmic and the interval between major scale readings are not marked. Nevertheless, the licensee stated that they l will consider this item for possible changes -in the procedure to specify acceptable range ]
I 9.0 Procedures I a The . procedures used by the health physics staff,.the HPI j L
procedures (Health Physics Instructions) were reviewed during I this inspe: tion. Although many of the procedures were found
'1 to be clearly written and comprehensive, some were found to be outdated and no longer reflected current practices. As an l example, HPI 2-3, " External Dosimetry", written in 1984, describes: badging practices that are no longer.in effect at the facility. Other procedures do- not provide sufficient information to allow effective implementation of the-activit ;
For example, HPI 2-4, " Dosimetry Quality Assurance", written =l in 1986, describes the method to be used to irradiate QA
~ dosimeters, but does not describe the methods to be used to ,
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analyze the results or determine acceptability _ of the !
l performance of th dosimetry processo _HPI 8-2, )
" Environmental' Sampling", written in 1937, describes the methods to be used to obtain and analyze environmental samples, but does et describe the criteria to be used to ;
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assess the data. Tl licensee stated that they are updating L these procedures as .he opportunity presents'itself and that procedure reviews are low in the list of priorities established for the reactor health - physics operation. The licensee also stated'that HPIs are not required by Technical Specifications and that they are used as guides for the health physics staff. However, Section of the Technical Specifications, " Procedures", states that " Written procedures
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shall be provided.and utilized for the following:...", "(4) .
radiation and radioactive contamination control". This 1 category would include at least some of the HPIs.- The licensee -
stated that.they will review the matter and take appropriate
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actio .0 Rabbit System Contamination The rabbit system used at the reactor facility is a system of- l tubes that is used to transport samples of material, sealed ,
in small-plastic containers called rabbits, from a laboratory 1 in the reactor facility to a location inside the reactor. In l the reactor, the sample is exposed to a high neutron flux, which renders some - or all of the isotopes in the sample radioactive. The rabbit system than' transports the sample back to the laboratory, after a predetermined irradiation time', for radiochemical analysis. During the period of this inspection, on June 7, two radiochemists 'were found to have been
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contaminated on their. hands and feet upon leaving the_ rabbit laboratory. The contamination was found during a routine exit frisk in the hand and foot monitor adjacent to the laborator Surveys of the laboratory showed contamination on the floor, table-tops, and hoods. The-contamination was analyzed on a -) '
gamma spectrometer _and found to contain mainly manganese-56 (Mn-56) and sodium-24 (Na-24). The- licensee conducted ,
investigaticns in an attempt _to isolate the source of the i contamination. At the end of this. inspection, the source of contamination had not been identified, but the licensee stated that the - most likely source was the - rabbits used in the i irradiations.-This is based:on tests in which clean rabbits l were sent empty into the rabbit system for short irradiation periods and came-back contaminated both inside and out. The
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contamination consisted mainly of Mn-56 and Na-24. The licensee stated that the investigation will continue, but in 'l the meantime, work practices in the rabbit laboratory have been changed to guard against personnel contamination and the spread of contamination to other area .0 Exit Meetina l
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An exit meeting was held with licensee representatives on June 26, 1990. During the meeting, the purpose and scope of the ;
inspection were reviewed and the inspection findings were i
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discusse :
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