ML18194A605

Email Re_ Westinghouse Hdp Ventilation Survey Data

ML18194A605
Person / Time
Site:	07000036
Issue date:	07/12/2018
From:	Evers B Westinghouse Electric Corp
To:	James Smith Division of Decommissioning, Uranium Recovery and Waste Programs
J SMITH NMSS DUWP
References
Download: ML18194A605 (5)

Text

From:

Evers, William C.

To:

Smith, James; Pallagi, Kenneth E.

Cc:

Kelmeckis, Val J; Chapman, Gregory; Parks, Leah

Subject:

[External_Sender] RE: Westinghouse HDP Ventilation survey data Date:

Thursday, July 12, 2018 11:14:49 AM

Jim,

As discussed on our publicly noticed tele-conference this morning, I am sending this follow-up e-mail. This is Westinghouses confirmation that the discrepancy noted in the e-mail chain below (use of 4 pi calibrated efficiency versus 4 pi on-site efficiency), was an isolated occurrence, and was not repeated anywhere else on the project. This was the only instance where the FSS sub-contractor utilized a 4 pi efficiency to support the FSS program. All other Final Status surveys performed by the FSS sub-contractor were performed using a 2 pi efficiency, and were therefore un-affected.

Please let me know if there is anything else I can provide. Thank you.

W. Clark Evers, CHP Radiation Safety Officer Hematite Decommissioning Project

From: Smith, James [1]

Sent: Wednesday, July 11, 2018 1:04 PM To: Pallagi, Kenneth E.

Cc: Kelmeckis, Val J; Evers, William C.; Chapman, Gregory; Parks, Leah

Subject:

RE: Westinghouse HDP Ventilation survey data

Lets plan to discuss it tomorrow morning, and see if we can resolve whether there is anything that needs to be addressed further.

From: Pallagi, Kenneth E. [2]

Sent: Wednesday, July 11, 2018 9:28 AM To: Smith, James <James.Smith@nrc.gov>

Cc: Kelmeckis, Val J <kelmecvj@westinghouse.com>; Evers, William C.

<everswc@westinghouse.com>; Chapman, Gregory <Gregory.Chapman@nrc.gov>

Subject:

[External_Sender] Westinghouse HDP Ventilation survey data

Jim, Clark has completed his review of the documentation at the site relevant to Gregs question. Please find the response below.

Clark and I can be available for a call tomorrow if need be.

Westinghouse does not have any agenda items for a call.

Thanks, Ken

The short answer:

Even though the instrument efficiencies are significantly different, a 4 pi efficiency was used for both surveys. I was able to review the former survey records, and instrumentation paperwork and confirm this. However in reviewing the instrumentation paperwork I discovered that the former FSS sub-contractor mistakenly used the wrong 4 pi efficiency for the ventilation surveys performed in Building 110.

The long answer:

The building 230 ventilation BSA 02-20 was surveyed by Westinghouse on 3/14/16. Westinghouse used a Model 43-89 (125 cm2 active area) probe paired with a Model 2360 meter. The 43-89 probe used, assigned the letter A for easy reference was initially set up on-site using a Th-230 source for alpha efficiency, and a Tc-99 source for beta efficiency in a 4 pi geometry. For 43-89 A the established alpha efficiency was 12.2%, and the established beta efficiency was 5.3%. These efficiencies are near the low end of the range of expected typical instrument efficiencies, but are none the less appropriate. When 43-89 A was used for FSS, a 2 pi efficiency of 24.1% alpha, and 8.5% beta was used to determine a total weighted efficiency of 6.96%. The correct 4 pi efficiency was applied to the ventilation surveys performed in BSA 02-20.

The building 110 ventilation BSA 01-05, was surveyed by the FSS sub-contractor (Perma-fix) on 6/18/15. The FSS sub-contractor used Ludlum Model 43-93 (100 cm2 active area) probes paired with Model 2360 meters. The 43-93 probes used were assigned the letters F and H for easy reference. These instruments were calibrated off site and certified with a 4 pi calibration geometry, then set up on-site following Westinghouse procedures to establish a 2 pi efficiency for use in FSS surveys.

For 43-93 F the established calibration alpha efficiency was 20.34%, and the established calibration beta efficiency was 18.86%. For 43-93 H the established calibration alpha efficiency was 19.62%, and the established calibration beta efficiency was 16.84%. These efficiencies are near the high end of the range of expected typical instrument efficiencies, but are still in line with the expected 4 pi geometry following on-site Westinghouse procedures. When 43-93 F was used for FSS, a 2 pi efficiency of 25.27% alpha, and 25.54% beta was used to determine a total weighted efficiency of 9.07%. When 43-93 F was used for FSS, a 2 pi efficiency of 27.50%

alpha, and 28.74% beta was used to determine a total weighted efficiency of 9.97%.

Since the FSS sub-contractor only anticipated performing FSS surveys using a 2 pi geometry, a 4 pi geometry was not established for on-site use. However later when the time came to survey the ventilation systems in Building 110, it was apparent that a 4 pi geometry was needed for the release surveys. The FSS sub-contractor mistakenly selected the calibration 4 pi geometry, rather than establishing a new 4 pi geometry for on-site use following Westinghouse procedures. Had the FSS sub-contractor established a 4 pi geometry following on-site Westinghouse procedures prior to performing the ventilation surveys the established efficiencies would have been slightly different than those used for the ventilation release surveys.

For 43-93 F the established on-site alpha efficiency was 12.63%, and the established on-site beta efficiency was 15.90%. For 43-93 H the established on-site alpha efficiency was 13.75%, and the

established on-site beta efficiency was 17.90%. Using the correct 4 pi geometry established following on-site Westinghouse procedures represents a change in the final assessed activity for the ventilation survey. For meter F the alpha activity increased 38%, and the beta activity increased 16%. For meter H the alpha activity increased 30%, and the beta activity decreased by 6%.

Despite the use of the 4 pi calibration efficiency instead of establishing an on-site 4 pi instrument efficiency, the ventilation surveys still show that the interior surfaces of the Building 110 ventilation system meet the unrestricted release criteria, and support the conclusion of the FSS. The statement made in Volume 4, Chapter 16, Section 10.1 could be amended to state the following:

• The maximum observed total activity result in BSA 01-05 was compared to the unrestricted release criteria. Alpha was 2.3%1.6% and Beta 18.9%20% of the unrestricted release criteria.

Furthermore, there is no change to the final dose assessment of BSA 01-05 as the dose was assigned based on air sample activity, and the ventilation surveys still support the conclusion that the system is suitable for release.

W. Clark Evers

From: Smith, James [3]

Sent: Monday, July 09, 2018 9:09 AM To: Pallagi, Kenneth E.; Evers, William C.

Cc: Parks, Leah; Chapman, Gregory

Subject:

FW: Ventilation survey data

Ken and Clark

Think you can answer Gregs question below via email, or do we need a call on Thursday?

Jim

cid:image001.jpg@01D4176E.378017D0

From: Chapman, Gregory Sent: Monday, July 09, 2018 10:06 AM To: Smith, James <James.Smith@nrc.gov>

Cc: Parks, Leah <Leah.Parks@nrc.gov>

Subject:

Ventilation survey data

Jim,

Sorry to have just noticed thisbut I got to looking at the surveys for ventilation and noticed something a bit off. Specifically, the stated efficiencies for the probes used varied by building. The probes are essentially the same for both surveys, even though different models, with approximately the same manufacturer stated efficiencies for Pu-239 and Tc-99, so it seemed weird that the efficiencies for one buildings surveys were about half that of the other. It is possible that ventilation in one is a curved surface while the other is flat depending on what the duct is made of, but there is no indication that they did a surface efficiency correction. It is more likely that they used a 4pi efficiency in one case and a 2pi efficiency in the other. Can you ask Hematite why there is such a discrepancy? I think this is in the appendices for HEM-17-64dated October 24, 2017.

Greg Chapman CHP, PE 301-415-8718 NMSS/DUWP/MDB

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