RCF 19-03, Rensselaer - Requests a Revision to the RPI Critical Experiments Facility, License CX-22, Technical Specifications
| ML19205A066 | |
| Person / Time | |
|---|---|
| Site: | Rensselaer Polytechnic Institute |
| Issue date: | 07/11/2019 |
| From: | Ji W Rensselaer Polytechnic Institute |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| RCF 19-03 | |
| Download: ML19205A066 (7) | |
Text
DEPARTMENT OF MECHANICAL, AEROSPACE, AND NUCLEAR ENGINEERING RCF 19-03 July 11, 2019 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 To Whom It May Concern:
This letter requests a revision to the RPI Critical Experiments Facility, license CX-22, Technical Specifications.
Background
The RPI Critical Experiments Facility (RCF) is surrounded by two fences. The outermost fence is the civil exclusion zone. The inner fence defines the restricted area. These two fences are identified in the Technical Specification, section 5.1, as:
"An inner fence of greater than 30 feet radius defines the restricted area. An outer fence and riverbank of greater than 50 feet radius defines the exclusion area."
Construction work around the RCF resulted in relocating the fences. Closer to the facility at some points and further away at others. However, the relocation did not move the fences such that the statement in theTechnical Specification was untrue.
An NRC Inspection in September 2018 noted that rough measurements of the fence do not match those used in an analysis performed after the relocation and more accurate measurements should be made and evaluated for agreement with the Technical Specifications.
Discussion The Technical Specification description of the fence location does not detail just where the reactor is within those two areas. It isn't clear where the center of the 30 feet and 50 feet circles is located, or if they share the same center.
The results of detailed measurements are in Table 1 below.
North South West East Rx center to Bldg
, exterior, feet 39.4 13.3 21.3 26.7 Bldg exterior to inner fence, feet -14.7 15.0 24.8 15.4 Total to inner fence, feet 54.0 28.3 46.0 42.1 Inner fence to outer fence, feet 11.3 7.1 12.0 12.3 Total to outer fence, feet 65.3 35.4 58.0 54.3 Table 1: RCF Fence Location Relative to Reactor Centerline
Figure 1 shows the construction drawing of the fence locations. North is up on the Figure. Based on the measurements in Table 1, the center of the reactor is identified relative to the South and East building exteriors. The measurements and Figure 1 show the bias. The reactor is closest to the southern fence boundary. The measurements also show that, in fact, the reactor is within an area with 30 feet radius,just not at the center of that area. Attachment 1 is a 10CFRS0.59 evaluation made after the September inspection. The evaluation used the information from Table 1 above and concluded that a change to the RCF Technical Specification was appropriate to clarify the separation from the reactor provided by both fences.
Figure 1: RCF Building Footprint and Exterior Fences Radiation levels were measured during the relicensing process at a reactor power of 13 watts and extrapolated to the 100 watt license limit. No locations on the outer fence exceeded the 2 mr/hr limit for exposure to the general public in 10CFR20. The shortest distance from the reactor to the fence for that measurement was 45 feet and the extrapolated dose rate was 1.15 mr/hr. The
exclusion area fence is now 35.4 feet from the center of the reactor. Assuming a 1/r2 relationship, the dose rate at that outer fence location would be 1.85 mr/hr, below the 2 mr/hr limit.
Proposed Technical Specification Revision is a markup of the page in the Technical Specification that describes the location of the fences relative to the reactor.
RPI requests approval for this change to the RCF Technical Specification.
Dr. Wei Ji, Facility Director RPI Critical Experiments Facility Attachments:
- 1. Safety Evaluation ofRCF Fence Line Reconfiguration
- 2. Mark-up ofRCF Technical Specifications, page 17 Cc:
Dr. Shekhar Garde, Dean of Dr. Suvranu De, Head, Dr. Hyun Kang, Chair, NSRB Engineering Department of Mechanical, and Associate Professor Aerospace, and Nuclear Engineering Ms. Annette Chism, Director Mr. Glenn Winters, RCF EH&S and Risk Operations Supervisor Management
Attachment 1 Safety Evaluation ofRCF Fence Line Reconfiguration Glenn C Winters, RCF Operations Supervisor November 2018 Overview Construction around the L David Walthousen Laboratory required relocation of the fencing around the facility and new access road. The prior access road from Erie Blvd was cut by a dredged canal into a newly formed marina harbor. The fencing moved closer to the facility in some locations and further away in others. Fencing establishes the civil exclusion, referred to as the site boundary in the Emergency Plan. An inner fence defines the restricted area and is referred to as the operations boundary in the Emergency Plan.
The description ofthe fences in the Technical Specifications is:
"An inner fence of greater than 30 feet radius defines the restricted area. An outer fence and riverbank of greater than 50 feet radius defines the exclusion area."
A prior review of the effect of the relocated fencing compared the above description in the Technical Specification to the new location. This evaluation concluded that the new location for the fencing would fall outside the described circular areas. However, the prior evaluation did not consider the specific criteria in 10 CFRS0.59(c)(2). This was noted by the NRC in a routine inspection performed in September 2018.
In the same inspection, the NRC suggested that the center of the reactor should be the center of the two circular areas described in the Technical Specification.
Evaluation This is an evaluation of the repositioned fencing around the RCF in accordance with 10CFRS0.59(c)(2). Included is a calculation of the radiation dose rates where fencing is closer to the reactor than the prior location and a proposed change to the description of the fencing in the Technical Specification.
(1) Will the new fence positions result in more than a minimal increase in the frequency of occurrence of an accident previously evaluated in the final safety analysis report (as updated?
The repositioned fences do not affect the reactor accident described in the final safety analysis. This accident is an unplanned reactivity addition terminated by an automatic scram. The facility fences have no effect on the frequency of this accident.
(2) Will the new fence positions result in more than a minimal increase in the likelihood of occurrence of a malfunction of a structure, system, or component (SSC) important to safety previously evaluated in the final safety analysis report (as updated)?
No structure, system or component important to safety is affected by the fencing around the facility. The fence is an important security structure and one that establishes a radiation safety boundary for the general public. Calculations below show that the 10CFR20 limits for radiation exposure to members of the general
. public are not exceeded.
Attachment 1 (3) Will the new fence positions result in more than a minimal increase in the consequences of an accident previously evaluated in the final safety analysis report (as updated)?
There is no increase in the consequences of an accident previously evaluated in the final safety analysis report. "
(4) Will the new fence positions result in more than a minimal increase in the consequences of a malfunction of an SSC important to safety previously evaluated in the final safety analysis report (as updated)?
There is no increase in the consequences of a malfunction of an SSC important to
'safety previously evaluated in the final safety analysis report (5) Will the new fence positions create a possibility for an accident of a different type than any previously evaluated in the final safety analysis report (as updated)?
The rep9sitioned fencing does not create the possibility of a different accident than
. that previously evaluated in the final safety analysis report.
(6) Will the new fence positions create a pos~ibility for a malfunction of an SSC important to safety with a different result than any previously evaluated in the final safety analysis report (as updated)?
The repositioned fencing cannot cause a malfunction of an SSC important to safety.
(7) Will the new fence positions result in a design basis limit for a fission product barrier as described in the final safety analysis report (as updated) being exceeded or altered?
The repositioned fencing has no effect on the fission product barrier.
(8) Will the new fence positions result in a departure from a method of evaluation described in the final safety analysis report (as updated) used in establishing the design bases or in the safety analyses? ,
The evaluation methods described in the final safety analysis report are unaffected by the repositioned fencing.
Radiation Exposure to the General Public Radiation levels were measured during the relicensing process at a reactor power of 13 watts and extrapolated to the 100 watt license limit. No locations on the outer fence exceeded the 2 mr/hr limit for exposure to the general public in 10CFR20. The shortest distance from the reactor to the fence for that measurement was 45 feet and the extrapolated dose rate was 1.15 mr/hr. The exclusion area fence is now 35.4 feet from the center of the reactor. Assuming a l/r2 relationship, the dose rate at that outer fence location would be 1.85 mr/hr, below the 2 mr/hr limit. It is noteworthy to acknowledge that the RCF limits power to 15 watts by operating procedures. This would reduce the dose rate by about a factor of 6.
Technical Specification The description of the fences in the Technical Specification, Paragraph 5.1, does not provide a reference for the location of a point which is the center of the 30 feet radius and 50 feet radius areas. While a 30 feet radius circle can fit within the inner fence, it is not centered on the reactor.
Attachment 1 Similarly, the 50 feet radius circle will fit within the outer fence, but it also is not centered on the reactor.
Measuring from the center of the reactor, the closest section of inner fence is 28.3 feet and for the outer fence, 3 5 .4 feet.
A more correct, and clearer, description of the repositioned fences is:
"An inner fence more than 28 feet from the center of the reactor defines the restricted area.
An outer fence more than 35 feet from the center of the reactor defines the exclusion area."
Au.cbmc:nt 2 Speciflcatio,,
The criticality detector system, CAM and area gamma monitors shall be tested with a radiation source at least monthly and daily if the reactor is operated and calibrated semiannually.
Portable survey meters shall be calibrated at the manufacturer's recommended frequency.
Prior to discharge to the environment the moderator shall be monitored for radioactiv ity to prove that gross activity levels are lower that maximum levels permitted by 10 CFR 20 Appendix B Table 2.
Bases Experience has demonstrated that calibration of the criticality detectors. CAM and gamma monitors semiannnelly is adequate to ensure that significant deterioration in accuracy does not occur. Furthttmore, the operability or these radiation monitors is included in the daily pre,4arlUp cbeclc.list. If the reactor is not operated for more than a month, the instrumenlS are requ.ired to be checked to ensure operability. Portable instnunenas are calibrated at the manufacturer recommended frequency.
Experience has demoostrated that the moderator does not accwnulate radioactive material due to the low operating neutron Ouence. Therefore, periodic monitoring is not necessary. Verification is necessary, however, prior to d.iscbarge to the environment.
4.11 EJa:perinleats - Noae reqalred Since experiments may very drastically no general surveillances are defined. However, approved experimeotal procedures may contain experiment specif"ac surveillances.
4.9 Fadllty-spedllc Sunelllantt Requlrnne1tts - Nene reqlllred No facility specifte surveillances are required.
- 5. DESIGN FEATURES 5.1 Site and Facility DeKrlpdo*
Applicability These specifications apply to the design of the RCF and the surrounding site.
Obfectiw The purpose or these specifications is to provide a layout of the site and lhe structures that contain the reactor in a means to protect personoel.
Specification The facility is located on a site situated on the south bank of the Mohawk River in the City of Schenectady. An inner fence of greater than JO feet radius def"meg the restricted area.. An outer fence and riverbank of peter than :SO feet radius defines the exclus1on area. Replace highlighted text with* An inner f'cnce more than 28 feet from lhe cc:nta oftbc n:actor defines the rcmiclcd area. An outa fcncc more lhan 3S feet from lhe center oftbc reactor dcrmcs the exclusion an:a."
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