Protecting People and the EnvironmentUNITED STATES NUCLEAR REGULATORY COMMISSION
SSINS No.: 6835
IN 82-43
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF INSPECTION AND ENFORCEMENT
WASHINGTON, D.C. 20555
November 16, 1982
Information Notice No. 82-43: DEFICIENCIES IN LWR AIR FILTRATION/
VENTILATION SYSTEMS
Addressees:
All nuclear power reactor facilities holding an operating license (OL) or
construction permit (CP).
Purpose:
This information notice is provided as notification of events that had
actual or potential radiological impact on the plant environs. It is
expected that recipients will review the information for applicability to
their facilities. No specific action or response is required.
Description of Circumstances:
Within the past 2-1/2 years, air filtration/ventilation systems at five
facilities were found to have serious deficiencies, ranging from overloaded
prefilters to evidence of a wetted high-efficiency particulate air (HEPA)
filter bank, to penetration of HEPA filter banks by substantive quantities
of radioactive resin beads. Deficiencies occurred in both safety-related
and non-safety-related systems.
In June 1982, radioactive spent resin was found on the grounds and roof
areas at Pilgrim 1. Principal radionuclides were Co-60, Cs-137, Cs-134, and
Mn-54; contamination ranged from 20,000 dpm/100 cm2 to 100,000 dpm/100 cm2.
The contamination penetrated damaged filters in a non-safety-grade HEPA
filter plenum. The degraded condition of these filters was not detected in
a timely manner because of a lack of surveillance or testing of the
filtration system. The HEPA filter failure occurred possibly as an end
result of a combination of high dust loadings and mechanical damage
resulting from the impact of disintegrating prefilters, as well as the
probable warping or distortion of HEPA filter frames under prolonged
exposure to water and high humidity.
In December 1980, the SGTS trains at Brunswick 1 were found to be operating
at close to 100% humidity, and condensation was observed on the interior
walls. Regulatory Guide 1.52 recommends operation at humidity of 70% or
less; operation at high humidity is known to cause substantial degradation
of the iodine-retention capacity of charcoal absorbers. Also, in December
1980, both filter trains in the turbine building filter system at Brunswick
were found to be operating with the upstream HEPA differential pressure
gauges offscale high. Also, in the turbine building filter system, 43% of
the upstream HEPA filters were improperly installed.
.
IN 82-43
November 16, 1982
Page 2 of 2
In August 1980, filters and charcoal adsorbers in the Surry 1 process vent
exhaust air treatment system were determined to have been half submerged in
water, and the HEPA filters were caked with dust. No pressure drop instru-
mentation was provided across the filter banks to ascertain their state of
loading. Also, in August 1980, pressure drop gauges across the HEPA filter
banks in the ventilation exhaust treatment system of the auxiliary building
at Surry 1 exceeded 5 inches, which is offscale high; this condition had
existed since May 1980.
In May 1980, the normal containment building exhaust filters at Turkey Point
were found to be overloaded with dust to such an extent that the filter
medium was separated from its frame in more than 50% of the filters. This
apparently allowed radioactive contamination resulting from explosive
plugging of steam generator tubes to be transported to the southeast sector
of the plant site.
In March 1980, it was determined that HEPA filters in the Big Rock Point
offgas and chemistry laboratory exhaust treatment systems were not being
tested for leakage in place. No records were maintained of pressure
differential across the laboratory HEPA filters which had not been replaced
for at least five years.
In each case described above, licensees initiated programs and procedures to
correct the deficiencies and to prevent or minimize their potential for
reoccurrence.
Air treatment systems which incorporate filtration or absorption media are
provided to reduce the potential release of radioactive materials to the
environs. In order to function as designed, such systems should be
installed, tested, and maintained to a degree consistent with their intended
function.
Guidance on installation, maintenance, and testing programs, of a degree and
nature which have been demonstrated to ensure proper system functioning, is
provided in Regulatory Guides 1.52 and 1.140.
No written response to this information notice is required. If you need
addi-tional information about this matter, please contact the Regional
Administrator of the appropriate NRC Regional Office or this office.
Edward L. Jordan, Director
Division of Engineering and
Quality Assurance
Office of Inspection and Enforcement
Technical Contacts: L.J. Cunningham, IE
301-492-8073
P.G. Stoddart, NRR
301-492-7633
Attachment:
List of Recently Issued IE Information Notices
