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OFP CE OF AIR AND RADIATION

Dr. Dave Moody, Manager Carlsbad Field Office U.S. Department of Energy P.O. Box 3090 Carlsbad, New Mexico 88221-3090

Dear Dr. Moody:

This letter provides the results ofthe foliow-up inspection at the Carlsbad Field Office (CBFO) that U.S. Environmental Protection Agency's (EPA or we) conducted in December 2007. As a result of this inspection EPA determined that CBFO has adequately resolved EPA concems speeific from the EPA inspection of the W IPP (Waste Isolation Pilot Plant) Waste Information System (WWIS) conducted in January 2004 (EPA-CBFO-W WIS-01.04-24).

In ?Vlarch 2004, EPA issued a letter transmitting the inspection report (EPA Air DocketNo: A-98-49, II-A4-39). The letter stated that ". .. The WWIS is also adequate for the reporting of derived quantities, such as the total transuranic (TRU) alpha activity and TRU alpha concentration, pending resolution of the findings and concerns described in this report. EPA identified three (3) coneerns, all of which require a response from DOB. DOE should respond in writing to the three (3) concerns within 6 weeks of receipt of the enclosed report." These were not responded to within the 6 weeks, but EPA was able to evaluate and determine that site-specific waste data entered in the W WIS by the sites were appropriately modified to reflect changes made by the W WIS database manager to address the 2004 concerns. However, the formal closure of the concerns could only be obtained using the W WIS system maintained by the W WIS database manager in Carlsbad. 'I'his was accomplished in December 2007.

During EPA's December 2007 follow-up inspection in Cartsbad, EPA gathered the objective evidence to verify changes to the relevant W WIS algorithms had been satisfactorily changed, and the waste data have been correctly reported. The enclosed inspection report describes the concerns and their resolution following review of objective evidence.

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~ .epa_gov Recycled/Recyc4able 0 Printed with Vegetable Oil6ased Inks on SQO% Postconsumer, Process ChSorine Pree Recycled PaperIf you have any question, plea.se contact Rajani Joglekar at (202) 343-9462 or Ed

Feltcorn at (202) 343-9422.



### Sincer Iv,



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.~,~~ ~ Juan Reyes, Director Radiation Protection Division



### Enclosure

cc: Electronic Distribution Vernon Daub, CBFO Casey Gadbury, CBFO Courtland Fesmire, CBFO Norrna Castaneda, CBFO Ava Holland, CBFO Martin Navarrete, CBFO Dennis Miehls, CBFO Brian Littleton_ BPA Steve Zappe, NMED Allison Pangle, CTAC Wayne Ledford, CTACENCLOSURE

EPA Follow-up Inspeetion at W WIS, December 2007

Background:

On December 5, 2007, E PA conducted a follow-up inspection to verify that the changes made to address I:PA concerns are teehnically adequate. "I'he purpose of the meeting wasto discuss and close three concerns that originated from EPA Inspection No.EPA-CBFOW WIS-01.04-24 in 2004 that remained open. The EPA inspector met with the Carlsbad Field Office (CBFO) staff and the WIPP Waste Information System (W WIS) personnel to review objective evidence that addressed EPA's concem from the January 2004 W WIS inspection. EPA and CBFO personnel had discussions regarding these concerns on severai occasions and the only component that prevented closing the concerns was inspection of the objective evidence that addressed each concern. Attendees at the December 5, 2007 meeting were as follows:

EPA Concerns and Resolution:

Tlie three EPA concerns identifred during the January 2004 inspeetion are listed below, followed by the resolution for each.



### EPA Concern No. I— The total TRU activities reported tor eight of the ten inner containers in SRTP00114 are based not on the aetivities of the individually reported radionuclides, but on a MDC assigned to that container. In these instances, the total TRU activity reported for the inner container is significantly greater than that calculated by summing the reported activities of the individual TRU radionuclides. Between the other two inner containers in TDOP SRTP00114, the total TRU activity reported for inner container SR252852 is 15% greater than the sum of the aetivities of the individual "I RU radionuclides.



### No. 1 Resolution — This concern had two components, the first of whieh was specific to the Imaging Passive-Active Neutron (IPAN) Non Destructive Assay (NDA) system at the Savannah River Site (SRS). 'T'he IPAN's software used the Lower Limit of Detection (LLD) value for 24 'Am as an actuai estimate of a waste drum's 241 Am content and ineluded it in the calculation of the drum's TRli Alpha Activity (TAA), which was incorrect. This component was isolated to the IPAN and was addressed previously and was not within the scope of the Deeember 5, 2007 meeting. "I'he second component of this eoncern was addressed by revising DOE-WIPP-02-3122, the CII TRU Waste Aeceptance Criteria (WAC), 6ppendi_x E, in accordance with the August 4, 2003 CBFOpoticy statement 

### Management of 

### TRUAlpha Activity Concentratfon. The essence of this

ehange is to prevent the reporting of quantitative LLD estimates to the WWIS, as specified in WIPP Waste Information System IJser's Manuai, DOE/CBFO 97-2273, Revision 12, WWIS Ver. 5.4a, Section 9.4, and incorporating these changes in the W WIS. This change adequately addresses EPA's concern and this concern is closed.



### EPA Concern No. 2— The method used to calculate the uncertainty in the TRtJ alpha aetivity (TAA) concentration of an overpack, including TDOP and S WB, is technically incorrect. When a derived quantity is the product (or quotient) of two independent random variables, the 

### relative uncertainty of the derived quantity is the square root of the sum of the squares of the reported 

### relative uncertainties of'the two independent random variables. 

### The absolute uncertainty of the derived quantity is calculated by multiplying the quantity by its relative uncertainty. The ealculation of the 

### absolute uncertainty in the TAA eoncentration of the overpack as the square root of the sum of the squares of the reported 

### absolute uncertainties in the total TRLT activity concentration of each of the inner eontainers, performed by the W WIS, is technically incorrect. The latter calculation eannot be shown to be mathematically equivalent to the fonner, and evidence indicates the quantitative differences in the results of the two methods are significant. Based on the reported uncertainties in the totai TAA and mass of waste in the payload container, reported uneertainties in the TAA are significantly greater than uncertainties expected.



### No, 2 Resolution — To address this concern the WAC was formally modified to refleet the lack of requirement to report the uncertainty associated with TAA concentration, including overpacks, "IDOPs and SWBs. "This is stated in DOE-WIPP-02-3122, Revision 0, dated May 17, 2002, Section 3.3.2, page 3-11. This WAC requirement is essentially the same in Revision 6.0, dated November 15, 2006. Accordingly, the uncertainty for TAA concentration is not calculated, making a discussion regarding the calculation's correctness irrelevant. The section of'software code that addresses this was reviewed and V ersion 4.17 states that the field for TAA concentration is optional. The data base modification was performed in aecordance with Proeedure WP 08-NT.04, 

### WIPP Waste Information System Conftguration Management and Sofnvare Ouality Assurance Program. This concern is closed.



### EPA Concern No. 3 — The W WIS does not have adequate quantitative checks to verifythat data concerning the radiological constituents of waste emplaced in the WIPP is selfeonsistent. At a minimum the following conditions should be met for payload containers as a whole, and individualiy for all of the inner containers included in an overpack: (1) the total TAA reported must be equai, wifli some reasonabie allowance for round-off errors, to the sum of the individually reported TRIJ radionuelide aetivities; (2) the TAA concentration reported must be equal, with some reasonable allowance for round-off errors, to the total TAA divided by the mass of waste in the container; and (3) thereported activity of each radionuclide should, with some reasonable allowance for roundoff errors and uneertainty in the radionuclide's specifie activity, agree with the reported mass of that radionuclide.

### No. 3 Resolution —The WIPP Waste Information System User's Vianual, DOE/CBFO

97-2273, Revision 12, WWIS Ver. 5.4a, Section 9.5 documents an edit/limit check that is performed to compare the reported TAA with the TAA calculated based on the sum of the individually reported TRIJ radionuclides. The difference between the reported and calculated values is limited to five pereent (5%), as specified in Figure 9-7 of the 

### WAC Limits Reference Table. An example ofthe reference table is provided in Section 9.8, Figure 9-6, 

### 7RUAlpha Activiry and TAAC Data F'ields. WWIS Version 4.16 requires a 5% agreement for each of these three quantities: the activity concentration of the TRII alpha radionuclides; the total TRU alpha aetivity; and, radionuclide activity relative to mass. These checks are implemented as documented in DOEICBFO 97-2273, and this practice adequately addresses EPA's concern. This concern is closed.

Conclusion:

Upon evatuating objective evidence showing changes to address the EPA concerns and discussion with the WWIS staff, EPA concludes that W WIS has adequately resolved ail three EPA concerns.