ML20070K797
| ML20070K797 | |
| Person / Time | |
|---|---|
| Site: | Clinton  |
| Issue date: | 07/22/1994 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20070K793 | List: |
| References | |
| NUDOCS 9407270191 | |
| Download: ML20070K797 (4) | |
Text
[
UNITED STATES I
NUCLEAR REGULATORY COMMISSION f
(}
p WASHINGTON, D.C. 20556 4 1
,r SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 91 TO FACILITY OPERATING LICENSE NO. NPF-62 ILLIN0IS PQWER COMPANY. ET AL.
CLINTON POWER STATION. UNIT NO. 1 DOCKET NO. 50-461 1.0 JNTR0_ DUCTION The design of both the Control Room Ventilation System and the Standby Gas Treatment System includes charcoal filter beds that are used to reduce airborne radioactive firsion products following an accident.
The Control Room Ventilation System is designed to protect control room operators while the Standby Gas Treatment System is designed to reduce iodine and particulate concentrations in gases leaking from the primary containment that would potentially be present in the secondary containment.
Charcoal filters normally found in ventilation systems accumulate contaminates over time and must be periodically replaced.
Technical Specifications require periodic testing to verify the effectiveness of the charcoal filters to remove radiciodine.
Technical Specifications 3/4.6.6.3, " Control Room Ventilation System," and 3/4.7.2, " Standby Gas Treatment System," require testing at least once every 18 months or after any structural maintenance on the HEPA filter or charcoal adsorber housings, or following painting, fire, or chemical release in any ventilation zone communicating with the ventilation system.
In addition, testing must be performed after every 720 hours0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br /> of charcoal adsorber operation.
The specifications describe how the samples are to be obtained, the test methods to be used, and the final acceptance criteria.
Current Technical Specifications at the Clinton Power Station require that the testing methods be performed in accordance with the American Society for Testing and Materials (ASTM) Standard D-3803-1979, " Standard Methods for Radioiodine Testing of Nuclear-Grade Gas-Phase Adsorbents." This standard is also referred to as ASTM D3803-79.
ASTM D3803-79 was the subject of NRC Information Notice (IN) 87-32,
" Deficiencies in the Testing of Nuclear-Grade Activated Charcoal," issued on July 10, 1987.
It was reported that the ASME Committee on Nuclear Air and Gas Treatment conducted an interlaboratory comparison and found that seven U.S.
and eight foreign testing companies obtained vastly differing results from testing samples of the same charcoal.
IN 87-32 described serious deficiencies in ASTM D3803-79 along with problems with the capabilities of the testing companies.
Finally, it was stated that a new testing protocol had been developed and that the standard was being revised.
9407270191 94o7pp PDR ADOCK 05000461 P
pgg
. l The licensee's initial evaluation of IN 87-32 did not indicate a need to i
change their testing methods. However, an NRC inspection report at the Clinton Power Station conducted in November 1991 identified a significant amount of " data scatter" in test results.
Rather than showing a gradual decline in the effectiveness of the charcoal's ability to remove radiolodine, the test results indicated that the charcoal adsorbers had actually improved over time. As a result of this finding, Illinois Power committed to reevaluate IN 87-32.
Part of this revaluation was a review of the ASTM standard D3803 which was revised in 1989 to become ASTM D3803-89.
By letter dated April 18, 1994, the licensee requested a change to the Technical Specifications to allow use of the test methods found in ASTM D3803-89.
However, rather than specifying the year of the standard, the licensee requested to delete reference to the year.
By referencing " ASTM D3803" as opposed to " ASTM D3803-89," the licensee would have the flexibility of incorporating future revisions to the standard without the need of modifying the Technical Specifications.
2.0 EVALUATION The ASTM standard D3803 was revised in 1989 to address deficiencies identified in IN 87-32.
Changes to the standard included increased accuracies for testing and measuring equipment and adding a requirement to " equilibrate" samples prior to testing.
The equilibration, in conjunction with the use of more efficient backup beds for collection of the methyl iodide passing through the test bed and use of more accurate measuring equipment, provides more accurate and repeatable test results.
The test methodology for ASTM D3803-79 included the following steps for the i
methyl iodide penetration test. The charcoal test bed is initially brought to the specified temperature without any air flow. Once the specified temperature for the test bed is reached, a 60 minute " feed period" is initiated using a mixture of air and methyl iodide.
After the feed period is complete, air flow without methyl iodide is continued under the same controlled temperature and humidity conditions for an additional 240 minute "elution period." Throughout the test, the effluent from the test bed passes through a backup bed having a known high efficiency for removal of methyl iodide.
The backup bed, which traps essentially all of the remaining methyl iodide, is measured by a gamma counter following the elution period. The bed-depth penetration is ultimately calculated based on the ratio of the activity trapped in the backup bed to the combined activity trapped in the test and backup beds.
The major changes to the test methodology of ASTM D3803-89 include the following.
Prior to the feed period, a 16 hour1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> " pre-equilibration period" has i
been introduced which consists of purge air at the specified temperature and humidity. This is then followed by a two hour " equilibration period" which, in turn, is followed by a 60 minute feed period and a 60 minute elution period.
The two equilibration periods ensure that all samples have a common I
. starting point before introducing the methyl iodide flow.
In addition, the 1989 version requires rtdundant high efficiency backup beds.
These changes, along with the more accurate measuring instrumentation, ensure more accurate and repeatable test results.
Previous charcoal test data taken at the Clinton facility has yielded questionable results.
The test data does not always identify a gradual decline in the effectiveness of the charcoal filters to remove radiciodines.
ASTM D3803-89 was developed to correct the anomalous results of ASTM D3803-79 and should significantly improve the test results.
The licensee's letter stated their intention to adopt the provisions of ASTM D3803-89.
However, their proposal simply replaced all references to D3803-79 with a generic reference to the standard without specifying a year.
Such a change would permit the licensee to incorporate future revisions to the standard through the change control provisions of 10 CFR 50.59.
The staff had two objections to the licensee's proposal. The first objection was the grneric reference to the ASTM standard. Typically the staff requires plant Tcchnical Specifications to reference the year of the standard.
This prevents the use of future revisions that have not been previously reviewed and approved by the staff.
Second, the 1989 version of ASTM D3803 strictly specifies a test temperature of 30
- C.
This is a change from the 1979 version of the standard and reflects the finding that testing at temperatures above 30 *C is not sufficiently conservative for predicting charcoal performance during accident conditions.
In response to the staff's concerns, the licensee modified their proposal in a letter dated June 16, 1994.
This most recent letter references the 1989 version of the ASTM standard and specifies the test temperature for all charcoal filters to be 30
- C.
The staff has determined the licensee's proposal to be consistent with the staff's position on charcoal filter testing and, therefore, acceptable.
Bases Section 3/4.7.2, " Control Room Ventilation System," states that periodic surveillance testing will be performed to provide assurance that system and component performance continues to meet design specifications and applicable parts of ANSI N509-1980.
The licensee has indicated that the reference to ANSI N509-1980 is inappropriate because the standard addresses installation acceptance criteria. Therefore, the licensee has proposed to replace the reference to ANSI N509-1980 with a reference to ANSI N510-1980, which refers to periodic testing. While the Bases section is not part of the technical specifications as defined by 10 CFR 50.36, the staff finds the proposed change acceptable.
3.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Illinois State official was notified of the proposed issuance of the amendment. The State official had no comments.
l
. j t
4.0 INVIRONMENTAL CONSIDERATION l
This amendment changes a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20. The NRC staff has determir.ed that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure.
The Commission has previously issued a proposed finding that the amendment involves no significant hazards consideration and there has been no public comment on such finding (59 FR 24750). Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).
Pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendment.
5.0 CONCLUSION
The staff has concluded, based on the considerations discussed above, that:
(1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor: Douglas \\'.
Pickett Date: July 22, 1994
.