[Federal Register Volume 63, Number 37 (Wednesday, February 25, 1998)]
[Notices]
[Pages 9581-9589]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-4761]


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NUCLEAR REGULATORY COMMISSION


Proposed Generic Communication; Laboratory Testing of Nuclear-
Grade Activated Charcoal (M97978)

AGENCY: Nuclear Regulatory Commission.

ACTION: Notice of opportunity for public comment.

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SUMMARY: The Nuclear Regulatory Commission (NRC) is proposing to issue 
a generic letter concerning the laboratory testing of nuclear-grade 
activated charcoal that is used in the safety-related air-cleaning 
units of engineered safety feature ventilation systems of nuclear power 
plants to reduce the potential onsite and offsite consequences of a 
radiological accident by adsorbing iodine. The purpose of the proposed 
generic letter is to: (1) Alert addressees that the NRC has determined 
that testing nuclear-grade activated charcoal to standards other than 
American Society for Testing and Materials (ASTM) D3803-1989, 
``Standard Test Method for Nuclear-Grade Activated Carbon,'' does not 
provide assurance for complying with their current licensing basis as 
it relates to the dose limits of General Design Criterion (GDC) 19 of 
Appendix A to 10 CFR Part 50 and Subpart A of 10 CFR Part 100, and that 
ASTM D3803-1989 should be used for both new and used charcoal because 
it allows for accurately monitoring the degradation of the charcoal 
over time; (2) request that addressees determine whether their 
technical specifications (TS) reference ASTM D3803-1989 for charcoal 
filter laboratory testing and if not, either amend their TS to 
reference ASTM D3803-1989 or propose an alternative test protocol and 
provide the requested information; (3) alert addressees of NRC intent 
to exercise enforcement discretion under certain conditions; and (4) 
require that addressees submit written responses to this generic 
letter.

[[Page 9582]]

The NRC is seeking comment from interested parties regarding both the 
technical and regulatory aspects of the proposed generic letter 
presented under the Supplementary Information heading.
    The proposed generic letter has been endorsed by the Committee to 
Review Generic Requirements (CRGR). Relevant information that was sent 
to the CRGR will be placed in the NRC Public Document Room. The NRC 
will consider comments received from interested parties in the final 
evaluation of the proposed generic letter. The NRC's final evaluation 
will include a review of the technical position and, as appropriate, an 
analysis of the value/impact on licensees. Should this generic letter 
be issued by the NRC, it will become available for public inspection in 
the NRC Public Document Room.

DATES: Comment period expires March 27, 1998. Comments submitted after 
this date will be considered if it is practical to do so, but assurance 
of consideration cannot be given except for comments received on or 
before this date.

ADDRESSES: Submit written comments to Chief, Rules and Directives 
Branch, Division of Administrative Services, U.S. Nuclear Regulatory 
Commission, Mail Stop T6-D69, Washington, DC 20555-0001. Written 
comments may also be delivered to 11545 Rockville Pike, Rockville, 
Maryland, between 7:45 a.m. to 4:15 p.m., Federal workdays. Copies of 
written comments received may be examined at the NRC Public Document 
Room, 2120 L Street, N.W. (Lower Level), Washington, D.C.

FOR FURTHER INFORMATION CONTACT: John P. Segala, (301) 415-1858.

SUPPLEMENTARY INFORMATION:

NRC Generic Letter 97-XX: Laboratory Testing of Nuclear-Grade 
Activated Charcoal

Addressees

    All holders of operating licenses for nuclear power reactors, 
except those who have permanently ceased operations and have certified 
that fuel has been permanently removed from the reactor vessel.

Purpose

    The U.S. Nuclear Regulatory Commission (NRC) is issuing this 
generic letter to:
    (1) Alert addressees that the NRC has determined that testing 
nuclear-grade activated charcoal to standards other than American 
Society for Testing and Materials (ASTM) D3803-1989, ``Standard Test 
Method for Nuclear-Grade Activated Carbon,'' does not provide assurance 
for complying with their current licensing basis as it relates to the 
dose limits of General Design Criterion (GDC) 19 of Appendix A to 10 
CFR Part 50 and Subpart A of 10 CFR Part 100. In addition, the staff 
has determined that ASTM D3803-1989 should be used for both new and 
used charcoal because it allows for accurately monitoring the 
degradation of the charcoal over time.
    (2) Request that all addressees determine whether their technical 
specifications (TS) reference ASTM D3803-1989 for charcoal filter 
laboratory testing. Addressees whose TS do not reference ASTM D3803-
1989 should either amend their TS to reference ASTM D3803-1989 or 
propose an alternative test protocol and provide the information 
discussed in the requested actions.
    (3) Alert addressees of the staff's intent to exercise enforcement 
discretion under certain conditions.
    (4) Require that all addressees send the NRC written responses to 
this generic letter, relating to implementation of the requested 
actions.

Background

    Safety-related air-cleaning units used in the engineered safety 
feature (ESF) ventilation systems of nuclear power plants reduce the 
potential onsite and offsite consequences of a radiological accident by 
adsorbing radioiodine. To ensure that the charcoal filters used in 
these systems will perform in a manner that is consistent with the 
licensing basis of a facility, most licensees have requirements in 
their facility TS to periodically test (in a laboratory) samples of 
charcoal taken from the air-cleaning units.
    The NRC's and the nuclear industry's understandings of the 
appropriate laboratory tests for nuclear-grade charcoal have evolved 
over the years since the issuance of Regulatory Guide (RG) 1.52, 
``Design, Testing, and Maintenance Criteria for Postaccident 
Engineered-Safety-Feature Atmosphere Cleanup System Air Filtration and 
Adsorption Units of Light-Water-Cooled Nuclear Power Plants,'' which is 
referenced in many plant TS. It was initially assumed that high-
temperature/high-relative humidity (RH) conditions were the most 
severe. Later, with more testing experience, it became clear that the 
most conservative test is at low temperature/high humidity. The use of 
outdated test protocols or inappropriate test conditions can lead to an 
overestimation of the charcoal's ability to adsorb radioiodine 
following an accident.
    Problems associated with the performance of the laboratory test of 
charcoal under inappropriate test conditions were discussed in 
Attachment 1 of Information Notice (IN) 86-76. Attachment 1, ``Summary 
of Control Room Habitability Reviews,'' noted that charcoal was being 
tested at much higher temperatures than any expected during the course 
of an accident, and that the performance of the laboratory test at that 
temperature can result in erroneously high efficiency measurements.
    In 1982, the American Society of Mechanical Engineers (ASME) 
Committee on Nuclear Air and Gas Treatment (CONAGT) conducted an inter-
laboratory comparison test using ASTM D3803-1979 and found that seven 
U.S. laboratories and eight foreign laboratories obtained vastly 
different results when testing samples of the same charcoal. After 
efforts to resolve the differences failed, the NRC contracted with EG&G 
at Idaho National Engineering Laboratory (INEL) to assess the problem. 
As a result of this assessment, the NRC issued IN 87-32. Through IN 87-
32, the NRC informed licensees of deficiencies in the testing of 
nuclear-grade charcoal, specifically noting serious problems with the 
capabilities of the testing laboratories and with the testing standard 
(ASTM D3803-1979). The NRC contractor detailed the specific problems in 
its technical evaluation report, EGG-CS-7653, ``Final Technical 
Evaluation Report for the NRC/INEL Activated Carbon Testing Program.'' 
Specifically, EG&G reported that ASTM D3803-1979 had unacceptable test 
parameter tolerances and instrument calibration requirements, and that 
ASTM D3803-1979 was nonconservative in not requiring humidity pre-
equilibration of used charcoal. The information notice indicated that 
the protocol developed by EG&G could be utilized for performing the 
laboratory test until the D-28 committee responsible for ASTM D3803 
revised the standard. The committee completed the revision and issued 
it in December 1989. The problems associated with the testing 
laboratories were resolved after the number of U.S. firms performing 
such tests dropped from seven to the current two.
    On April 29, 1993, representatives from ASME and CONAGT met with 
the NRC staff to express their concerns about laboratory testing of 
charcoal. CONAGT discussed the variation in laboratory test results 
obtained (methyl iodide penetration) when temperature, RH, face 
velocity, bed depth, test protocol, and impregnate were varied. CONAGT 
stated that the 1989 version of

[[Page 9583]]

ASTM D3803 is the only acceptable test method for TS applications and 
compared the results of laboratory tests performed using the 1986 
version of ASTM D3803 (which is the 1979 version with editorial 
changes) to results using the 1989 version. The results from the 1986 
protocol showed significantly higher iodine-removal capabilities than 
the results from the 1989 version.
    In addition, CONAGT indicated that testing charcoal at temperatures 
greater than 30  deg.C [86  deg.F] almost always results in the 
charcoal meeting the TS acceptance criteria, even when the charcoal is 
deficient. To support this premise, CONAGT presented the results of 
laboratory tests conducted at temperatures of 30  deg.C [86  deg.F], 80 
 deg.C [176  deg.F], and 130  deg.C [266  deg.F]. The data show 
significant increases in iodine-removal capabilities as the test 
temperature increases. CONAGT indicated that all systems located 
outside of containment should be tested at 30  deg.C [86  deg.F], which 
is more representative of the limiting accident conditions. Tests 
conducted at 80  deg.C [176  deg.F] or 130  deg.C [266  deg.F] are 
inappropriate because tests at these temperatures result in the 
regeneration of the charcoal. At elevated temperatures, the charcoal 
contains less moisture than at 25  deg.C [77  deg.F] and 30  deg.C [86 
deg.F] which results in the charcoal having more surface area available 
for adsorption of iodine. Therefore, testing at the elevated 
temperatures results in an overestimation of the actual iodine-removal 
capability of the charcoal, and testing at 25  deg.C [77  deg.F] or 30 
deg.C [86  deg.F] gives results that represent a more realistic 
assessment of the capability of the charcoal. CONAGT concluded its 
presentation by stating that the major problems associated with the 
laboratory test of charcoal are the designation of the test protocol 
and the TS that designate the test to be performed.
    On November 6, 1996, the staff visited the two remaining 
laboratories that test nuclear-grade activated charcoal, NCS 
Corporation and NUCON International, Inc. Both laboratories have 
resolved the poor reproducibility problem identified in the EG&G report 
by performing all tests with calibrated equipment that is capable of 
maintaining the tight tolerances of the test parameters as specified in 
ASTM D3803-1989. Tight tolerances are very important when tests are 
performed at high RH, because slight variations in RH result in 
unacceptably large differences in the tested efficiency of the 
charcoal.

Discussion

    Although some licensees have changed their TS to reference the 
latest testing standard (ASTM D3803-1989), many still use outdated 
standards and/or test conditions that may overestimate the capability 
of the charcoal in their ESF systems. As a result, the ability of the 
charcoal filters in these systems to perform in a manner consistent 
with the licensing basis for the facility may be in question.
    The licensees of three plants (V.C. Summer, Davis-Besse and Oconee) 
determined that the tests they performed were not in compliance with 
their TS and submitted emergency TS amendments (see Enclosure 1 for 
details). As a result of the emergency TS changes, the staff has 
performed an internal survey of the TS of operating plants to determine 
whether other plants have the potential for similar compliance 
problems. The survey indicated that at least one-third of operating 
reactor licensees may be out of compliance with their TS because, 
although the plant TS reference RG 1.52 or American National Standards 
Institute (ANSI) N509-1976, ``Nuclear Power Plant Air-Cleaning Units 
and Components,'' the licensees may have used later versions of the 
standards for the laboratory tests of their nuclear-grade charcoal. On 
the basis of this survey, the staff established the following four 
groups of plants:
    (1) Plants in compliance with their TS that test in accordance with 
ASTM D3803-1989.
    (2) Plants in compliance with their TS that test in accordance with 
a test protocol other than ASTM D3803-1989.
    (3) Plants not in compliance with their TS that test in accordance 
with ASTM D3803-1989.
    (4) Plants not in compliance with their TS that test in accordance 
with a test protocol other than ASTM D3803-1989.
    Licensees in Group 1 have TS that require charcoal to be tested in 
accordance with ASTM D3803-1989, which adequately demonstrates the 
capability of the charcoal. As discussed in Enclosure 1, the staff 
considers ASTM D3803-1989 to be the most accurate and most realistic 
protocol for testing charcoal in ESF ventilation systems because it 
offers the greatest assurance of accurately and consistently 
determining the capability of the charcoal. For example, it requires 
the test to be performed at a constant low temperature of 30 deg.C 
[86 deg.F]; it provides for smaller tolerances in temperature, 
humidity, and air flow; and it has a humidity pre-equilibration.
    Licensees in Group 2 have TS that require charcoal to be tested in 
accordance with test standards other than ASTM D3803-1989. On the basis 
of available laboratory test results for more than 50 charcoal samples, 
there were significant differences in filter efficiencies for about 15 
to 20-percent of the tested samples when comparing the test results 
from ASTM D3803-1979 and ASTM D3803-1989. When the charcoal samples 
were tested in accordance with ASTM D3803-1979, they always appeared to 
have very high efficiencies. However, when the same charcoal samples 
were tested in accordance with ASTM D3803-1989, significant reduction 
in efficiency was noted. Depending on the system arrangement, this 
reduction in filter efficiency can result in calculated doses to the 
control room operators exceeding the GDC 19 limits by as much as a 
factor of 1.5 to 2. For pressurized-water reactors (PWRs) with 
secondary containments and for all boiling-water reactors (BWRs), this 
reduction in filter efficiency can result in offsite doses from a 
filtered pathway increasing by as much as a factor of 10 to 15. As a 
result, the testing of nuclear-grade activated charcoal to standards 
other than ASTM D3803-1989 does not provide assurance for complying 
with the plant's licensing basis as it relates to the dose limits of 
GDC 19 and Part 100.
    In addition, the staff has determined that ASTM D3803-1989 should 
be used for both new and used charcoal because it allows for accurately 
monitoring the degradation of the charcoal over time. The original 
rationale for testing used and new charcoal differently was the belief 
that a long equilibration period would regenerate the used charcoal by 
removing contaminants adsorbed by the charcoal during normal plant use. 
However, an EG&G technical evaluation report, described in Enclosure 1, 
demonstrated that this is not true. As a result, ASTM D3803-1989 
specifies testing both used and new charcoal in the same manner.
    Currently, before shipping, suppliers test most new charcoal with 
the ASTM D3803-1989 protocol at 30 deg.C [86 deg.F] and 95-percent RH 
in addition to the test protocol and test conditions the addressee 
records on the purchase order. The results from the new charcoal tested 
via ASTM D3803-1989 present a solid baseline for the initial capability 
of the charcoal. Using ASTM D3803-1989 to test used charcoal is a very 
accurate and reproducible method for determining the capability of the 
charcoal. By comparing the results of the used charcoal tests with the 
new charcoal test baseline, the addressee can be certain of the 
charcoal's level of degradation.
    Analyses of design-basis accidents assume a particular engineered 
safety features (ESF) charcoal filter adsorption

[[Page 9584]]

efficiency when calculating offsite and control room operator doses. 
Licensees then test charcoal filter samples to determine whether the 
filter adsorber efficiency is greater than that assumed in the design-
basis accident analysis. The laboratory test acceptance criteria 
contain a safety factor to ensure that the efficiency assumed in the 
accident analysis is still valid at the end of the operating cycle. 
Because ASTM D3803-1989 is a more accurate and demanding test than 
older tests, addressees that upgrade their TS to this new protocol will 
be able to use a safety factor as low as 2 for determining the 
acceptance criteria for charcoal filter efficiency. This safety factor 
can be used for systems with or without humidity control because the 
lack of humidity control is already accounted for in the test 
conditions (systems without humidity control test at 95-percent RH and 
systems with humidity control can test at 70-percent RH). The staff has 
previously approved reductions in the safety factor for plants adopting 
the ASTM D3803-1989 standard on a case-by-case basis. (The staff plans 
to make conforming changes to RG 1.52.)
    The licensees that received emergency TS changes were in Groups 3 
and 4. Licensees in Groups 3 and 4 have TS that require charcoal to be 
tested in accordance with RG 1.52 or ANSI N509-1976, and are not in 
compliance with their TS because the specified test protocol can not be 
successfully completed as discussed in Enclosure 1. These licensees are 
either (1) testing in accordance with the desired ASTM D3803-1989 
(Group 3) or (2) using earlier revisions of ASTM D3803 or an older 
standard which they believe are acceptable (Group 4). The staff does 
not have confidence that the results from RG 1.52 or ANSI N509-1976 
meet the intent of the TS which is to ensure that the doses are within 
the required limits. Therefore, licensees in these groups have not 
adequately demonstrated compliance with their licensing basis as it 
relates to the dose limits of GDC 19 and Part 100.
    The staff believes that (1) conflicting guidance, (2) complex and 
ambiguous standards, and (3) licensee belief that using later versions 
of the standard would satisfy their TS requirements, contributed to 
confusion regarding charcoal testing. These factors may explain why 
licensees did not adopt ASTM D3803-1989 (See Enclosure, for further 
discussion). In addition, based on the available laboratory test 
results, the staff believes that most charcoal in use is not degraded 
to an extent that would adversely affect control room habitability or 
public health and safety. This confidence in charcoal performance and 
given the low probability of a design basis accident, justify the time 
frames for the resolution of this matter. Therefore, the staff intends 
to exercise enforcement discretion, consistent with Section VII.B.6 of 
the Enforcement Policy, for all addressees in Groups 3 and 4, provided:
     Within 60 days of the date of this generic letter, either 
charcoal samples are tested in accordance with ASTM D3803-1989 and the 
results meet the current TS acceptance criteria or all of the charcoal 
is replaced with new charcoal that has been tested in accordance with 
ASTM D3803-1989;
     Acceptable charcoal sample test results discussed in the 
first condition are submitted to the NRC within 60 days of the date of 
this generic letter;
     A TS amendment request is submitted to the NRC within 60 
days of the date of this letter; and
     The charcoal samples continue to be tested in accordance 
with ASTM D3803-1989 until the TS amendment is approved by the NRC.
    In cases in which the charcoal samples have been previously tested 
in accordance with ASTM D3803-1989 for the last scheduled laboratory 
test and the results met the current TS acceptance criteria (Group 3), 
the results can be used to satisfy the first condition above.
    Licensees in Group 2 have been complying with their TS by testing 
their charcoal in accordance with their TS. Therefore, enforcement 
discretion is not required.

Requested Actions

    Addressees are requested to take the following actions:
    1. If your current TS require the laboratory testing of charcoal 
samples for each ESF ventilation system to be conducted in accordance 
with ASTM D3803-1989, then no TS amendment is required.
    2. If your current TS do not require the laboratory testing of 
charcoal samples to be conducted in accordance with ASTM D3803-1989, 
then:
    (i) Your charcoal samples should be tested in accordance with ASTM 
D3803-1989 and the results should be submitted to the NRC within 60 
days of the date of this generic letter. If your charcoal samples were 
already tested in accordance with ASTM D3803-1989 for the last 
scheduled laboratory test and the results met the current TS acceptance 
criteria, then the results should be submitted to the NRC within 60 
days of the date of this generic letter. In either case, the charcoal 
samples should continue to be tested in accordance with ASTM D3803-1989 
until the TS amendment is approved by the NRC, and
    (ii) Your TS should be amended to require the laboratory testing of 
charcoal samples to be conducted in accordance with:
    (a) ASTM D3803-1989, or
    (b) An alternate test protocol should be proposed for the 
laboratory testing of charcoal and the following information should be 
submitted for staff review to determine the acceptability of the 
alternate protocol:

1. Summary of the test method
2. Precision of the method
3. Description of the test apparatus along with tolerances
4. Parameter specifications
5. Material requirements
6. Hazards
7. Preparation of the apparatus before initiation of the test
8. Calibration requirements of the test equipment
9. Test procedure
10. Manner of calculating penetration and error
11. Repeatability and reproducibility of the results for 1-percent and 
10-percent penetration and the penetration at a 95-percent confidence 
interval for charcoal tested at 70-percent RH and at 95-percent RH
12. Bias associated with the method
13. Results from an independent laboratory which demonstrate that the 
alternate test protocol gets results that are consistent with, or more 
conservative than, that associated with ASTM D3803-1989

    The demonstration identified in Item 13 above should be based upon 
a series of tests comparing the alternate test protocol and ASTM D3803-
1989, and it should apply to both new and used charcoal tested at 70-
percent RH and at 95-percent RH. The independent laboratory should be 
able to demonstrate that the alternate protocol is at least as 
conservative as ASTM D3803-1989, and should be able to perform the ASTM 
D3803-1989 test and achieve repeatable and reproducible results. The 
laboratory should not be engaged in the measurement of iodine 
penetration of charcoal as a business either for TS compliance purposes 
or for the sale and/or production of activated charcoal for nuclear 
power plant applications.

Requested Information

    Within 60 days of the date of this generic letter, addressees are 
requested to provide to the NRC the following information:
    1. Identify the current TS requirements for the laboratory testing

[[Page 9585]]

of charcoal samples for each ESF ventilation system including the 
specific test protocol, temperature, RH, and penetration at which the 
TS require the test to be performed. If your current TS specifically 
require testing in accordance with the ASTM D3803-1989 protocol, and 
you have been testing in accordance with this standard, then no 
additional information is required.
    2. If you choose to adopt the ASTM D3803-1989 protocol, then submit 
a TS amendment request to require testing to this protocol. The request 
should contain the test temperature, RH, and penetration at which the 
proposed TS will require the test to be performed and the basis for 
these values. If the system has a face velocity greater than 10 percent 
of 0.203 m/s [40 ft/min], then the revised TS should specify the face 
velocity. Also, indicate when the next laboratory test is scheduled to 
be performed. (Enclosure 2 is a sample TS that the NRC considers 
acceptable.)
    3. If you are proposing an alternate test protocol, then address 
the attributes discussed in Section 2(ii) of the Requested Actions and 
submit a TS amendment request to require testing to this alternate 
protocol. The request should contain the test temperature, RH, and 
penetration at which the proposed TS will require the test to be 
performed and the basis for these values. If the system has a face 
velocity greater than 10 percent of 0.203 m/s [40 ft/min], then the 
revised TS should specify the face velocity. Also, indicate when the 
next laboratory test is scheduled to be performed.

Required Response

    Within 30 days of the date of this generic letter, addressees are 
required to submit a written response indicating: (1) Whether the 
requested actions will be completed, (2) whether the requested 
information will be submitted and (3) whether the requested information 
will be submitted within the requested time period. Addressees who 
choose not to complete the requested actions, or choose not to submit 
the requested information, or are unable to satisfy the requested 
completion date, must describe in their response any alternative course 
of action that is proposed to be taken, including the basis for 
establishing the acceptability of the proposed alternative course of 
action and the basis for continued operability of affected systems and 
components as applicable.
    Address the required written response to the U.S. Nuclear 
Regulatory Commission, ATTN: Document Control Desk, Washington, D.C. 
20555-0001, under oath or affirmation, under the provisions of Section 
182a, Atomic Energy Act of 1954, as amended, and 10 CFR 50.54(f). In 
addition, send a copy to the appropriate regional administrator.

Backfit Discussion

    Appendix A to 10 CFR Part 50, General Design Criteria (GDC) for 
Nuclear Power Plants, and the plant safety analyses require and/or 
commit that licensees design and test safety-related structures, 
systems and components to offer adequate assurance that they can 
perform their safety functions. Specifically, GDC 19 of Appendix A to 
10 CFR Part 50 specifies dose limits to ensure that control room 
operators are provided with adequate radiation protection under 
accident conditions. Following the accident at Three Mile Island (TMI), 
TMI Action Plan Item III.D.3.4, ``Control Room Habitability 
Requirements,'' as specified in NUREG-0737, ``Clarification of TMI 
Action Plan Requirements,'' required all licensees to perform 
evaluations and identify appropriate modifications to ensure that 
control room operators are adequately protected from the release of 
radioactive gases and that the nuclear power plant can be safely 
operated or shut down under design-basis accident conditions (GDC 19). 
When modifications were proposed by licensees, the NRC issued Orders 
confirming licensee commitments. As a result, all licensees are 
required to meet the dose limits of GDC 19. In addition, Subpart A of 
10 CFR Part 100 specifies reference dose values which can be used in 
the evaluation of the suitability of proposed sites for nuclear power 
plants with respect to potential reactor accidents that could result in 
the release of significant quantities of radioactive fission products. 
The expectation is that the site location and the engineered safety 
features included as safeguards against the hazardous consequences of 
an accident, should one occur, should ensure a low risk of public 
exposure. In this regard, licensees commit to dose limits that can be 
used as the basis for assessing the performance of safety-related 
structures, systems and components. Accordingly, licensees are required 
to test the nuclear-grade activated charcoal of their engineered safety 
feature ventilation systems in accordance with a suitable testing 
standard to ensure that the charcoal filters are capable of performing 
their required safety function and that the licensing bases of their 
respective facilities regarding onsite and offsite dose consequences 
continue to be satisfied.
    The actions requested in this generic letter are considered 
compliance backfits under the provisions of 10 CFR 50.109. If some 
licensees test their charcoal in accordance with their TS which 
reference an outdated test standard, the staff does not have confidence 
that the results of those tests will demonstrate compliance with the 
plant's licensing basis as it relates to the dose requirements of GDC 
19 and Part 100, including commitment to the resolution of TMI Action 
Plan Item III.D.3.4. Therefore, the staff has endorsed the testing 
standard ASTM D3803-1989 for referencing in plant TS. In accordance 
with the provisions of 10 CFR 50.109(a)(4)(i), regarding compliance 
backfits, a full backfit analysis was not performed. However, an 
evaluation was performed in accordance with NRC procedures, including a 
statement of the objectives of and reasons for the requested actions 
and the basis for invoking the compliance exception and is reflected in 
this backfit discussion.

Federal Register Notification

(To be completed after the public comment period.)

Paperwork Reduction Act Statement

    This Generic Letter contains information collections that are 
subject to the Paperwork Reduction Act of 1995 (44 U.S.C. 3501 et 
seq.). These information collections were approved by the Office of 
Management and Budget, approval number 3150-0011, which expires 
September 30, 2000.
    The public reporting burden for this mandatory information 
collection is estimated to average 40 hours per response, including the 
time for reviewing instructions, searching existing data sources, 
gathering and maintaining the data needed, and completing and reviewing 
the information collection. The U.S. Nuclear Regulatory Commission is 
seeking public comment on the potential impact of the information 
collections contained in the generic letter and on the following 
issues:
    1. Is the proposed information collection necessary for the proper 
performance of the functions of the NRC, including whether the 
information will have practical utility?
    2. Is the estimate of burden accurate?
    3. Is there a way to enhance the quality, utility, and clarity of 
the information to be collected?
    4. How can the burden of the information collection be minimized, 
including the use of automated collection techniques?

[[Page 9586]]

    Send comments on any aspect of this information collection, 
including suggestions for reducing the burden, to the Information and 
Records Management Branch (T-6 F33), U.S. Nuclear Regulatory 
Commission, Washington, DC 20555-0001, or by Internet electronic mail 
at [email protected]; and to the Desk Officer, Office of Information and 
Regulatory Affairs, NEOB-10202, (3150-0011), Office of Management and 
Budget, Washington, DC 20503.

Public Protection Notification

    If an information collection does not display a currently valid OMB 
control number, the NRC may not conduct or sponsor, and a person is not 
required to respond to, the information collection.
    Enclosures:
    (1) Background Information on the Laboratory Testing of Nuclear-
Grade Activated Charcoal.
    (2) Sample Technical Specifications.
Enclosure 1

Background Information on the Laboratory Testing of Nuclear-Grade 
Activated Charcoal

Charcoal Testing Requirements

    Analyses of design-basis accidents assume a particular engineered 
safety features (ESF) charcoal filter adsorption efficiency when 
calculating offsite and control room operator doses. Licensees then 
test charcoal filter samples to determine whether the filter adsorber 
efficiency is greater than that assumed in the design-basis accident 
analysis. The laboratory test acceptance criteria contain a safety 
factor to ensure that the efficiency assumed in the accident analysis 
is still valid at the end of the operating cycle.
    Guidance on the frequency of, and the test method for, the 
laboratory testing of charcoal appears in various documents, including 
all revisions of Regulatory Guide (RG) 1.52, ``Design, Testing, and 
Maintenance Criteria for Postaccident Engineered-Safety-Feature 
Atmosphere Cleanup System Air Filtration and Adsorption Units of Light-
Water-Cooled Nuclear Power Plants,'' and other NRC documents on plant 
technical specifications (TS). Guidance on the laboratory test protocol 
appears in such standards as American National Standards Institute 
(ANSI) N509, ``Nuclear Power Plant Air-Cleaning Units and Components;'' 
ANSI N510, ``Testing of Nuclear Air-Cleaning Systems;'' Military 
Specification RDT M 16-1T, ``Gas Phase Adsorbents for Trapping 
Radioactive Iodine and Iodine Components;'' and American Society for 
Testing and Materials (ASTM) Standard D3803, ``Standard Test Method for 
Nuclear-Grade Activated Carbon.''
    All of the standards describe a pre-equilibration period, a 
challenge period, and an elution period. During the pre-equilibration 
(pre-sweep) period, the charcoal is exposed to a flow of air controlled 
at the test temperature and relative humidity (RH) before the challenge 
gas is fed through the charcoal. The pre-equilibration period ensures 
that the charcoal has stabilized at the specified test temperature and 
RH for a period of time, which results in the charcoal adsorbing all 
available moisture before the charcoal is challenged with methyl 
iodide. During the challenge period, air at the test temperature and RH 
with radio-labeled methyl iodide is injected through the charcoal beds 
to challenge the capability of the charcoal. During the elution (post-
sweep) period, air at the test temperature and RH is passed through the 
charcoal beds to evaluate the ability of the charcoal to hold the 
methyl iodide once it is captured.
    The ASTM D3803-1989 standard has two additional testing periods 
that are not required by other standards: the stabilization period and 
the equilibration period. During the stabilization period, air at the 
test temperature is passed through the charcoal beds to bring the 
system up to the operating temperature before the start of pre-
equilibration. During the equilibration period, air at the test 
temperature and RH is passed through the charcoal beds to ensure the 
charcoal adsorbs all the available moisture before the feed period. 
During this period, the system is more closely monitored than in the 
pre-equilibration period to ensure that all parameters are maintained 
within their limits.
    Depending upon the plant's TS, typical test temperatures are 
usually one of the following: 25 deg.C [77 deg.F], 30 deg.C [86 deg.F], 
80 deg.C [176 deg.F], or 130 deg.C [266 deg.F]. In addition, the TS 
usually require that the test be conducted at 70-percent RH if the ESF 
system controls the RH to 70-percent or less, or at 95-percent if the 
RH is not controlled to 70-percent.
    The standard technical specifications (STS) and many plant-specific 
TS specify Regulatory Position C.6.a of RG 1.52, Revision 2, as the 
requirement for the laboratory testing of the charcoal. Regulatory 
Position C.6.a refers to Table 2 of RG 1.52. Table 2 references Test 
5.b of Table 5-1 of ANSI N509-1976, ``Nuclear Power Plant Air-Cleaning 
Units and Components.'' Test 5.b references the test method from 
paragraph 4.5.3 of Military Specification RDT M 16-1T, ``Gas Phase 
Adsorbents for Trapping Radioactive Iodine and Iodine Components'' 
(date not indicated), but specifies that the test is to be conducted at 
80 deg.C [176 deg.F] and 95-percent RH with preloading and postloading 
sweep at 25 deg.C [77 deg.F]. This test is referred to as the ``25-80-
25 test.'' The essential elements of this test are as follows:
     70-percent or 95-percent RH.
     5-hour pre-equilibration (pre-sweep) time, with air at 
25 deg.C [77 deg.F] and plant-specific RH.
     2-hour challenge, with gas at 80 deg.C [176 deg.F] and 
plant-specific RH.
     A 2-hour elution (post-sweep) time, with air at 25 deg.C 
[77 deg.F] and plant-specific RH.
    The latest acceptable methodology for the laboratory testing of the 
charcoal is ASTM Standard D3803-1989, ``Standard Test Method for 
Nuclear-Grade Activated Carbon.'' ASTM D3803-1989 is updated guidance 
based on an NRC verification and validation effort on ASTM D3803-1979, 
which is updated guidance based on RDT M 16-1T. The essential elements 
of the ASTM D3803-1989 test are as follows:
     70-percent or 95-percent RH.
     2-hour thermal stabilization, with air at 30 deg.C 
[86 deg.F].
     16-hour pre-equilibration (pre-sweep) time, with air at 
30 deg.C [86 deg.F] and plant-specific RH.
     2-hour equilibration time, with air at 30 deg.C [86 deg.F] 
and plant-specific RH.
     1-hour challenge, with gas at 30 deg.C [86 deg.F] and 
plant-specific RH.
     1-hour elution (post-sweep) time, with air at 30 deg.C 
[86 deg.F] and plant-specific RH.
    The major differences between the ANSI N509-1976 and ASTM D3803-
1989 standards for charcoal testing are as follows:

----------------------------------------------------------------------------------------------------------------
           Major differences                      ASTM D3803-1989                       ANSI N509-1976          
----------------------------------------------------------------------------------------------------------------
Pre-Equilibration (Pre-Sweep)           30 deg.C [86 deg.F]                  25 deg.C [77 deg.F].               
 Temperature.                                                                                                   
Challenge Temperature.................  30 deg.C [86 deg.F]                  80 deg.C [176 deg.F].              
Elution (Post-Sweep) Temperature......  30 deg.C [86 deg.F]                  25 deg.C [77 deg.F].               
Total Pre-Test Equilibration..........  18 hours                             5 hours.                           

[[Page 9587]]

                                                                                                                
Tolerances of Test Parameters.........  Smaller                              Larger.                            
----------------------------------------------------------------------------------------------------------------

    As stated above, ASTM D3803-1989 challenges the representative 
charcoal samples at 30 deg.C [86 deg.F] rather than at 80 deg.C 
[176 deg.F]. The quantity of water retained by charcoal is dependent on 
temperature, and less water is retained as the temperature rises. The 
water retained by the charcoal decreases its efficiency in adsorbing 
other contaminants. At 30 deg.C [86 deg.F] and 95-percent RH, charcoal 
will retain about 40 weight-percent water. At 80 deg.C [176 deg.F] and 
95-percent RH, charcoal retains only about 2 to 3 weight-percent water. 
Because most charcoal is anticipated to be challenged at a temperature 
closer to 30 deg.C [86 deg.F] rather than 80 deg.C [176 deg.F], the 
lower temperature test condition of ASTM D3803-1989 will yield more 
realistic results than would a test performed at 80 deg.C [176 deg.F].
    ASTM D3803-1989 specifies a test temperature of 30 deg.C [86 deg.F] 
for both the pre- and post-test sweep rather than 25 deg.C [77 deg.F]. 
There is little difference in the adsorption behavior of charcoal 
between these two temperatures. A temperature of 25 deg.C [77 deg.F] is 
more conservative; however, the increase from 25 deg.C [77 deg.F] to 
30 deg.C [86 deg.F] does not represent a significant variation in the 
test results.
    ASTM D3803-1989 provides results that are reproducible compared to 
RDT M 16-1T because it has smaller tolerances on various test 
parameters, and it requires that the charcoal sample be pre-
equilibrated for a much longer period. The longer pre-equilibration 
time is more conservative because it will completely saturate the 
representative charcoal sample until it is in the condition to which 
the subject charcoal adsorbers are expected to be exposed during 
design-basis conditions. Therefore, testing in accordance with ASTM 
D3803-1989 will result in a more realistic prediction of the capability 
of the charcoal.

TS Testing Reference

    Laboratory tests of the charcoal are typically required (1) once 
every refueling outage, (2) when certain events occur that could 
adversely affect the ability of the charcoal to perform its intended 
function, and (3) following a defined period of ESF system operation. 
The TS require demonstration by laboratory testing that the charcoal is 
capable of performing at a level greater than that assumed in the NRC 
staff's safety evaluation report. If it fails to perform at that level, 
the charcoal must be replaced.
    The determination of the appropriate test conditions, test 
protocol, and acceptance criteria for laboratory testing of nuclear-
grade activated charcoal is frequently not a straightforward process. 
It sometimes requires a complex journey through a number of documents 
to ascertain the appropriate test conditions, test protocol, and 
acceptance criteria. As described earlier, if the plant has STS, the 
STS reference Regulatory Position C.6.a of RG 1.52 for the requirements 
for the laboratory testing of charcoal. Regulatory Position C.6.a 
refers to Table 2 of the regulatory guide. Table 2 references Test 5.b 
of Table 5-1 of ANSI N509-1976. Test 5.b from Table 5-1 references the 
test method from paragraph 4.5.3 of RDT M 16-1T (date not indicated), 
but specifies that the test is to be conducted at 80 deg.C [176 deg.F] 
and 95-percent RH with pre-loading and postloading sweep at 25 deg.C 
[77 deg.F]. This test is referred to as the ``25-80-25 test.''
    Also contributing to the potential confusion are the various ways 
in which TS are written, and conflicting NRC guidance on testing, 
particularly NRC letters to the nuclear industry and NRC papers 
presented at national conferences. This problem arose from the evolving 
understanding of what constituted an appropriate test. At various 
times, the NRC has stated that the newest version of a standard can be 
used and the test can be conducted at a temperature of 30  deg.C [86 
deg.F]. At other times, the NRC indicated that the TS are requirements 
and that the tests must be performed at the 25-80-25 conditions. In 
various forums, the NRC has also stated that a technical argument may 
be made for using the newer standard. However, in some instances when 
newer standards were utilized to demonstrate conformance with the TS, 
the NRC required licensees to submit TS amendment requests because the 
newer standards were not referenced in the TS. Therefore, it is 
understandable that licensees may be confused about laboratory testing 
protocols, testing conditions, and acceptance criteria. As a result, 
many licensees are not testing charcoal in accordance with their TS, 
although the tests they conduct may be more conservative than the tests 
required by the TS.
    Additionally, the 25-80-25 test has difficulties in that none of 
the protocols in any version of RDT M 16-1T or ASTM D3803 addresses 
performing the laboratory test at multiple temperatures as required by 
ANSI N509-1976. If the test protocol described in paragraph 4.5.3 of 
RDT M 16-1T (1973) is followed verbatim, a thermal step change must be 
made after the 5-hour pre-equilibration period to increase the 
temperature from 25  deg.C [77  deg.F] to 80  deg.C [176  deg.F] for 
the challenge period. The problem with such thermal step changes is 
that they result in condensation forming on the charcoal. The 
condensation of free water in the sample bed is cause for aborting the 
test, according to the 1977 version of RDT M 16-1T and subsequent 
versions of ASTM D3803. Therefore, the 25-80-25 test cannot be 
performed pursuant to any existing test protocol.
    Because paragraph 4.5.3 cannot be followed verbatim, a few 
licensees have changed the 25-80-25 test to thermally equilibrate the 
charcoal before introducing the challenge gas. Following the pre-sweep 
conditioning at 25  deg.C [77  deg.F], the bed temperature is raised to 
80  deg.C [176  deg.F] before introducing the challenge gas. Although 
such testing does not cause condensation in the test rig, it is not 
acceptable because the results are not easily reproducible, and even 
when the test is successfully completed, the results may not be 
conservative.
    Section 2 of ANSI N509-1976 states for the various documents that 
supplement ANSI N509 that the issuance of a document in effect at the 
time of the purchase order shall apply unless otherwise specified. In 
the case of charcoal, the purchase order date could be considered the 
date that the charcoal is procured. Therefore, TS that have the STS 
wording may allow the licensee the flexibility to use a more recent 
laboratory protocol than the 1973 version of RDT M 16-1T, depending on 
the procurement date for the charcoal, without a TS change. However, 
although the flexibility of protocol selection exists, the requirement 
to perform a 25-80-25 test for those plants that have TS that reference 
either Revision 1 or Revision 2 of RG 1.52, Table 5-1 of ANSI N509-
1976, or ANSI N510-1975 can only be relieved by license amendment.

[[Page 9588]]

Categorization of Plants

    Since February 1996, the staff has issued three emergency TS 
changes to licensees that had determined that the tests they performed 
were not in compliance with their TS, because the required testing 
standards and test protocols did not support a test in which the 
temperature is changed as required by the TS. If the temperature in the 
test apparatus is changed from 25  deg.C [77  deg.F] to 80  deg.C [176 
deg.F] during the test without modifying the test protocol, water 
condenses on the charcoal, thereby causing the test to be aborted (to 
fail). The emergency TS changes were issued for the V.C. Summer, Davis-
Besse, and Oconee facilities. The details of these TS changes are 
discussed below.
    On February 10, 1996, the licensee for the V.C. Summer Nuclear 
Station, South Carolina Electric & Gas Company (SCE&G), requested an 
emergency TS change. The systems involved were the control room 
emergency ventilation system and the fuel handling building exhaust 
system. On February 10, 1996, the NRC granted the emergency TS change. 
The emergency TS change was requested because SCE&G had determined that 
laboratory tests of the charcoal of the control room ventilation system 
and the fuel-handling building system had not been performed in 
compliance with the V.C. Summer TS. The laboratory test performed for 
V.C. Summer was a 25-25-25 test in lieu of the 25-80-25 required by its 
TS. The licensee had been performing the 25-25-25 test because, in 
consultation with its testing laboratory, it concluded that performance 
of the 25-80-25 test would result in condensation on the charcoal and, 
thus, an invalid test.
    On March 29, 1996, the Toledo Edison Company requested an emergency 
TS change for the Davis-Besse plant. The systems involved were the 
hydrogen purge, the shield building emergency ventilation, and the 
control room. The TS for Davis-Besse required the laboratory test to be 
performed in accordance with RG 1.52, Revision 2. In this case, the 
licensee was performing a 30-30-30 test using the testing protocol of 
ASTM D3803-1979 in lieu of the 25-80-25 test. On March 29, 1996, the 
NRC granted the emergency TS change to allow the 30-30-30 test.
    On April 2, 1996, Duke Power Company requested an emergency TS 
change for the Oconee Nuclear Station. The systems involved were the 
reactor building purge, the spent fuel pool ventilation, and the 
penetration room ventilation. The TS for Oconee required the laboratory 
test of charcoal to be performed in accordance with ANSI N510-1975, 
which requires the performance of the 25-80-25 test. However, the 
licensee was actually performing a 30-30-30 test using the test 
protocol of ASTM D3803-1989. The NRC granted an emergency TS change on 
April 2, 1996, to permit the 30-30-30 test.
    In each of these cases, the test performed to demonstrate 
compliance with TS provided results that the staff considered closer to 
reflecting the capability of the charcoal than the test required by the 
TS. In addition, the licensees believed that using the newer standard 
would satisfy their TS requirement. Their bases for this belief were 
the limitations of the test referenced in RG 1.52, their interpretation 
of ANSI N509 as allowing the use of later versions of the test 
protocol, and some of the guidance provided by the NRC. In the case of 
Oconee, the test actually performed is the test that the staff believes 
is the appropriate one, ASTM D3803-1989. However, because these tests 
had not been conducted in compliance with the plant's TS, each licensee 
would have had to shut down its plant or remain in a cold-shutdown mode 
until the test required by the TS could be successfully performed, or 
until the TS were amended.
    On March 21, 1996, Carolina Power & Light Company flew a charcoal 
sample from the Brunswick standby gas treatment system (SGTS) to its 
testing laboratory in Ohio for the performance of the 25-80-25 test to 
comply with the Brunswick TS before restart of an idle unit. The 
Brunswick TS required that the laboratory tests be performed in 
accordance with Revision 1 of RG 1.52. Previously, the licensee 
directed its testing laboratory to perform an 80-80-80 test. To perform 
the 25-80-25 test, the laboratory equilibrated the charcoal to 80 
deg.C [176  deg.F] before introducing the challenge gas. The licensee 
has not requested a TS change for Brunswick to correct the problem and 
is awaiting guidance from the NRC.
    As a result of the emergency TS changes, the staff has performed an 
internal survey of operating plant TS to determine whether other plants 
have the potential for similar problems with compliance. The survey 
indicated that at least one-third of operating reactor licensees may 
not be in compliance with their TS because they reference the flawed 
25-80-25 testing protocol and may have used later versions of the 
standards for the laboratory tests of their nuclear-grade charcoal. On 
the basis of this survey, the staff established the following four 
categories of plants:
    (1) Plants in compliance with their TS that test in accordance with 
ASTM D3803-1989.
    (2) Plants in compliance with their TS that test in accordance with 
a test protocol other than ASTM D3803-1989.
    (3) Plants not in compliance with their TS that test in accordance 
with ASTM D3803-1989.
    (4) Plants not in compliance with their TS that test in accordance 
with a test protocol other than ASTM D3803-1989.
    The licensees in Category 1 have TS that require charcoal to be 
tested in accordance with ASTM D3803-1989, which adequately 
demonstrates the capability of the charcoal. The licensees in Category 
2 have TS that require charcoal to be tested in accordance with test 
standards other than ASTM D3803-1989. The licensees that received 
emergency TS changes were in Categories 3 and 4. Licensees in 
Categories 3 and 4 have TS that require charcoal to be tested in 
accordance with the 25-80-25 test.
Enclosure 2

Sample Technical Specifications

For Plants With Improved Standard Technical Specifications

    C. Demonstrate for each of the ESF systems that a laboratory test 
of a sample of the charcoal adsorber, when obtained as described in 
[Regulatory Guide 1.52, Revision 2], shows the methyl iodide 
penetration less than the value specified below when tested in 
accordance with ASTM D3803-1989 at a temperature of  
30 deg.C [86 deg.F] and greater than or equal to the relative humidity 
specified below.

[[Page 9589]]

[GRAPHIC] [TIFF OMITTED] TN25FE98.003


    Note: The use of any standard other than ASTM D3803-1989 to test 
the charcoal sample may result in an overestimation of the 
capability of the charcoal to adsorb radioiodine. As a result, the 
ability of the charcoal filters to perform in a manner consistent 
with the licensing basis for the facility is indeterminate.
    ASTM D3803-1989 is a more stringent testing standard because it 
does not differentiate between used and new charcoal, it has a 
longer equilibration period performed at a temperature of 30 deg.C 
[86 deg.F] and a relative humidity (RH) of 95% (or 70% RH with 
humidity control), and it has more stringent tolerances that improve 
repeatability of the test
[GRAPHIC] [TIFF OMITTED] TN25FE98.004

    When ASTM D3803-1989 is used with 30 deg.C [86 deg.F] and 95% RH 
(or 70% RH with humidity control) is used, the staff will accept the 
following:
    Safety factor  2 for systems with or without humidity 
control.]

For Plants With Older Technical Specifications

    Each engineered safety feature (ESF) ventilation system shall be 
demonstrated OPERABLE:
    a. At least once per 18 months or (1) after any structural 
maintenance on the HEPA filter or charcoal adsorber housings, or (2) 
following painting, fire, or chemical release in any ventilation zone 
communicating with the system by:
    (1) Verifying, within 31 days after removal, that a laboratory test 
of a sample of the charcoal adsorber, when obtained in accordance with 
Regulatory Position C.6.b of Regulatory Guide 1.52, Revision 2, March 
1978, shows the methyl iodide penetration less than [see note in 
preceding section titled ``For Plants With Improved Standard Technical 
Specifications'']% when tested in accordance with ASTM D3803-1989 at a 
temperature of  30 deg.C [86 deg.F] and greater than or 
equal to a relative humidity of [see note in preceding section titled 
``For Plants With Improved Standard Technical Specifications'']%.
    b. After every 720 hours of charcoal adsorber operation, by 
verifying, within 31 days after removal, that a laboratory test of a 
sample of the charcoal adsorber, when obtained in accordance with 
Regulatory Position C.6.b of Regulatory Guide 1.52, Revision 2, March 
1978, shows the methyl iodide penetration less than [see note in 
preceding section titled ``For Plants With Improved Standard Technical 
Specifications'']% when tested in accordance with ASTM D3803-1989 at a 
temperature of  30 deg.C [86 deg.F] and greater than or 
equal to a relative humidity of [see note in preceding section titled 
``For Plants With Improved Standard Technical Specifications'']%.

    Dated at Rockville, Maryland, this 19th day of February 1998.

    For the Nuclear Regulatory Commission.
Jack W. Roe,
Acting Director, Division of Reactor Program Management, Office of 
Nuclear Reactor Regulation.
[FR Doc. 98-4761 Filed 2-24-98; 8:45 am]
BILLING CODE 7590-01-P